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Sample records for preoperative virtual navigation

  1. Design and development of a virtual anatomic atlas of the human skull for automatic segmentation in computer-assisted surgery, preoperative planning, and navigation.

    PubMed

    Metzger, M C; Bittermann, G; Dannenberg, L; Schmelzeisen, R; Gellrich, N-C; Hohlweg-Majert, B; Scheifele, C

    2013-09-01

    Manual segmentation of CT datasets for preoperative planning and intraoperative navigation is a time-consuming procedure. The purpose of this study was to develop an automated segmentation procedure for the facial skeleton based on a virtual anatomic atlas of the skull, to test its practicability, and to evaluate the accuracy of the segmented objects. The atlas skull was created by manually segmenting an unaffected skull CT dataset. For automated segmentation of cases via IPlan cranial (BrainLAB, Germany), the atlas skull underwent projection, controlled deformation, and a facultative threshold segmentation within the individual datasets, of which 16 routine CT (13 pathologies, 3 without) were processed. The variations of the no-threshold versus threshold segmentation results compared to the original were determined. The clinical usability of the results was assessed in a multicentre evaluation. Compared to the original dataset, the mean accuracy was [Formula: see text] mm for the threshold segmentation and 0.6-1.4 mm for the no-threshold segmentation. Comparing both methods together, the deviation was [Formula: see text] mm. An isolated no-threshold segmentation of the orbital cavity alone resulted in a mean accuracy of [Formula: see text] mm. With regard to clinical usability, the no-threshold method was clearly preferred, reaching modal scores of "good" to "moderate" in most areas. Limitations were seen in segmenting the TMJ, mandibular fractures, and thin bone in general. The feasibility of automated skull segmentation was demonstrated. The virtual anatomic atlas can improve the preprocessing of skull CT scans for computer assisted craniomaxillofacial surgery planning.

  2. Brain Activity on Navigation in Virtual Environments.

    ERIC Educational Resources Information Center

    Mikropoulos, Tassos A.

    2001-01-01

    Assessed the cognitive processing that takes place in virtual environments by measuring electrical brain activity using Fast Fourier Transform analysis. University students performed the same task in a real and a virtual environment, and eye movement measurements showed that all subjects were more attentive when navigating in the virtual world.…

  3. A study of navigation in virtual space

    NASA Technical Reports Server (NTRS)

    Darken, Rudy; Sibert, John L.; Shumaker, Randy

    1994-01-01

    In the physical world, man has developed efficient methods for navigation and orientation. These methods are dependent on the high-fidelity stimuli presented by the environment. When placed in a virtual world which cannot offer stimuli of the same quality due to computing constraints and immature technology, tasks requiring the maintenance of position and orientation knowledge become laborious. In this paper, we present a representative set of techniques based on principles of navigation derived from real world analogs including human and avian navigation behavior and cartography. A preliminary classification of virtual worlds is presented based on the size of the world, the density of objects in the world, and the level of activity taking place in the world. We also summarize an informal study we performed to determine how the tools influenced the subjects' navigation strategies and behavior. We conclude that principles extracted from real world navigation aids such as maps can be seen to apply in virtual environments.

  4. PROJECT HEAVEN: Preoperative Training in Virtual Reality.

    PubMed

    Iamsakul, Kiratipath; Pavlovcik, Alexander V; Calderon, Jesus I; Sanderson, Lance M

    2017-01-01

    A cephalosomatic anastomosis (CSA; also called HEAVEN: head anastomosis venture) has been proposed as an option for patients with neurological impairments, such as spinal cord injury (SCI), and terminal medical illnesses, for which medicine is currently powerless. Protocols to prepare a patient for life after CSA do not currently exist. However, methods used in conventional neurorehabilitation can be used as a reference for developing preparatory training. Studies on virtual reality (VR) technologies have documented VR's ability to enhance rehabilitation and improve the quality of recovery in patients with neurological disabilities. VR-augmented rehabilitation resulted in increased motivation towards performing functional training and improved the biopsychosocial state of patients. In addition, VR experiences coupled with haptic feedback promote neuroplasticity, resulting in the recovery of motor functions in neurologically-impaired individuals. To prepare the recipient psychologically for life after CSA, the development of VR experiences paired with haptic feedback is proposed. This proposal aims to innovate techniques in conventional neurorehabilitation to implement preoperative psychological training for the recipient of HEAVEN. Recipient's familiarity to body movements will prevent unexpected psychological reactions from occurring after the HEAVEN procedure.

  5. PROJECT HEAVEN: Preoperative Training in Virtual Reality

    PubMed Central

    Iamsakul, Kiratipath; Pavlovcik, Alexander V.; Calderon, Jesus I.; Sanderson, Lance M.

    2017-01-01

    A cephalosomatic anastomosis (CSA; also called HEAVEN: head anastomosis venture) has been proposed as an option for patients with neurological impairments, such as spinal cord injury (SCI), and terminal medical illnesses, for which medicine is currently powerless. Protocols to prepare a patient for life after CSA do not currently exist. However, methods used in conventional neurorehabilitation can be used as a reference for developing preparatory training. Studies on virtual reality (VR) technologies have documented VR's ability to enhance rehabilitation and improve the quality of recovery in patients with neurological disabilities. VR-augmented rehabilitation resulted in increased motivation towards performing functional training and improved the biopsychosocial state of patients. In addition, VR experiences coupled with haptic feedback promote neuroplasticity, resulting in the recovery of motor functions in neurologically-impaired individuals. To prepare the recipient psychologically for life after CSA, the development of VR experiences paired with haptic feedback is proposed. This proposal aims to innovate techniques in conventional neurorehabilitation to implement preoperative psychological training for the recipient of HEAVEN. Recipient's familiarity to body movements will prevent unexpected psychological reactions from occurring after the HEAVEN procedure. PMID:28540125

  6. Knowledge Navigation for Virtual Vehicles

    NASA Technical Reports Server (NTRS)

    Gomez, Julian E.

    2004-01-01

    A virtual vehicle is a digital model of the knowledge surrounding a potentially real vehicle. Knowledge consists not only of the tangible information, such as CAD, but also what is known about the knowledge - its metadata. This paper is an overview of technologies relevant to building a virtual vehicle, and an assessment of how to bring those technologies together.

  7. The value of preoperative functional cortical mapping using navigated TMS.

    PubMed

    Lefaucheur, Jean-Pascal; Picht, Thomas

    2016-04-01

    The surgical removal of brain tumours in so-called eloquent regions is frequently associated with a high risk of causing disabling postoperative deficits. Among the preoperative techniques proposed to help neurosurgical planning and procedure, navigated transcranial magnetic stimulation (nTMS) is increasingly performed. A high level of evidence is now available in the literature regarding the anatomical and functional accuracy of this mapping technique. This article presents the principles and facts demonstrating the value of using nTMS in clinical practice to preserve motor or language functions from deleterious lesions secondary to brain tumour resection or epilepsy surgery.

  8. Evaluation of navigation interfaces in virtual environments

    NASA Astrophysics Data System (ADS)

    Mestre, Daniel R.

    2014-02-01

    When users are immersed in cave-like virtual reality systems, navigational interfaces have to be used when the size of the virtual environment becomes larger than the physical extent of the cave floor. However, using navigation interfaces, physically static users experience self-motion (visually-induced vection). As a consequence, sensorial incoherence between vision (indicating self-motion) and other proprioceptive inputs (indicating immobility) can make them feel dizzy and disoriented. We tested, in two experimental studies, different locomotion interfaces. The objective was twofold: testing spatial learning and cybersickness. In a first experiment, using first-person navigation with a flystick ®, we tested the effect of sensorial aids, a spatialized sound or guiding arrows on the ground, attracting the user toward the goal of the navigation task. Results revealed that sensorial aids tended to impact negatively spatial learning. Moreover, subjects reported significant levels of cybersickness. In a second experiment, we tested whether such negative effects could be due to poorly controlled rotational motion during simulated self-motion. Subjects used a gamepad, in which rotational and translational displacements were independently controlled by two joysticks. Furthermore, we tested first- versus third-person navigation. No significant difference was observed between these two conditions. Overall, cybersickness tended to be lower, as compared to experiment 1, but the difference was not significant. Future research should evaluate further the hypothesis of the role of passively perceived optical flow in cybersickness, but manipulating the virtual environment'sperrot structure. It also seems that video-gaming experience might be involved in the user's sensitivity to cybersickness.

  9. Validation of a virtual preoperative evaluation clinic: a pilot study.

    PubMed

    Zetterman, Corey V; Sweitzer, Bobbie J; Webb, Brad; Barak-Bernhagen, Mary A; Boedeker, Ben H

    2011-01-01

    Patients scheduled for surgery at the Omaha VA Medical Center were evaluated preoperatively via telemedicine. Following the examination, patients filled out a 15 item, 5 point Likert scale questionnaire regarding their opinion of preoperative evaluation in a VTC format. Evaluations were performed under the direction of nationally recognized guidelines and recommendations of experts in the field of perioperative medicine and were overseen by a staff anesthesiologist from the Omaha VA Medical Center. No significant difficulties were encountered by the patient or the evaluator regarding the quality of the audio/visual capabilities of the VTC link and its ability to facilitate preoperative evaluation. 87.5% of patients felt that virtual evaluation would save them travel time; 87.5% felt virtual evaluation could save them money; 7.3% felt uncomfortable using the VTC link; 12.2% felt the virtual evaluation took longer than expected; 70.7% preferred to be evaluated via VTC link; 21.9% were undecided; 9.7% felt they would rather be evaluated face-to-face with 26.8% undecided; 85.0% felt that teleconsultation was as good as being seen at the Omaha surgical evaluation unit; 7.5% were undecided. Our study has shown that effective preoperative evaluation can be performed using a virtual preoperative evaluation clinic; patients are receptive to the VTC format and, in the majority of cases, prefer it to face-to-face evaluation.

  10. Accuracy of pedicle screw insertion in posterior scoliosis surgery: a comparison between intraoperative navigation and preoperative navigation techniques.

    PubMed

    Zhang, Wei; Takigawa, Tomoyuki; Wu, YongGang; Sugimoto, Yoshihisa; Tanaka, Masato; Ozaki, Toshifumi

    2017-06-01

    This study was conducted to compare the efficacy and accuracy of intraoperative navigation (O-arm or Arcadis navigation) and preoperative CT-based navigation in adolescent idiopathic scoliosis (AIS) surgery. Sixty-seven patients with scoliosis were grouped according to the method of navigation used in their fixation surgeries. A total of 492 pedicle screws were implanted in 27 patients using intraoperative navigation, and 626 screws were implanted in 40 patients using preoperative navigation. We analyzed the postoperative CT images for pedicle violations using the Gertzbein classification. There was no statistical difference in the accuracy of pedicle screw placement between two groups. However, in the apical region (the apex ± 2 vertebrae), the accuracy of safe pedicle screw placement (grades 0, 1) was significantly higher in the intraoperative navigation group than in the preoperative navigation group (94.8 vs 89.2%, respectively; P = 0.035). Intraoperative navigation significantly diminished medial perforation compared to preoperative navigation (P = 0.027), and the number of screws per vertebra that could be placed in the apical region was significantly higher in intraoperative navigation group (P < 0.001). In addition, the time required for the registration procedure and insertion of one pedicle screw was 11.3 ± 2.1 min in the preoperative group, but significantly decreased to 5.1 ± 1.1 min in the intraoperative group (P < 0.001). Both preoperative CT-based and intraoperative navigation systems provide sufficient accuracy and safety in pedicle screw insertion for AIS surgery. Intraoperative navigation systems facilitate pedicle screw insertion in the apical region and reduce registration time during AIS surgery which improves the efficacy and accuracy of pedicle screw insertion.

  11. Feedback from video for virtual reality Navigation

    SciTech Connect

    Tsap, L V

    2000-10-27

    Important preconditions for wide acceptance of virtual reality (VR) systems include their comfort, ease and naturalness to use. Most existing trackers super from discomfort-related issues. For example, body-based trackers (hand controllers, joysticks, helmet attachments, etc.) restrict spontaneity and naturalness of motion, while ground-based devices (e.g., hand controllers) limit the workspace by literally binding an operator to the ground. There are similar problems with controls. This paper describes using real-time video with registered depth information (from a commercially available camera) for virtual reality navigation. Camera-based setup can replace cumbersome trackers. The method includes selective depth processing for increased speed, and a robust skin-color segmentation for accounting illumination variations.

  12. Navigating mazes in a virtual environment

    NASA Astrophysics Data System (ADS)

    Browse, Roger A.; Skillicorn, David B.; Middleman, Darren

    2003-06-01

    In this research we are concerned with computer interfaces with which subjects navigate through maze simulations which are essentially buildings, with corridors and intersections, such as frequently encountered in computer games and simulations. We wish to determine if virtual reality interfaces introduce a performance enhancement that might be expected for display configurations which mimic natural perceptual experiences. We have experimented primarily with two display conditions for presentation of and navigation through the mazes. Subjects either view the maze on a desktop computer monitor, turning and moving within the maze with the mouse in a way that is similar to the configurations used in most first-person role playing computer games, or they viewed the maze from a standing position with a head-mounted display, being free to direct the view of the maze through body and head movements, and using the depression of a mouse button to effect movement in the direction that they were facing. Head-tracking was required for this latter condition. As expected there are striking individual differences in subjects" abilities to learn to traverse the mazes. Across a variety of maze configuration parameters which significantly do influence performance, the results indicate that the virtual reality enhancements have no effect subjects' ability to learn the mazes, either as route knowledge or as cognitive maps.

  13. NES: How to Navigate the Virtual Campus

    NASA Image and Video Library

    This video describes how to navigate the NASA Explorer Schools public website. Information includes descriptions of the left navigation, using the breadcrumbs, understanding the various announcemen...

  14. Navigation for the Blind through Audio-Based Virtual Environments.

    PubMed

    Sánchez, Jaime; Sáenz, Mauricio; Pascual-Leone, Alvaro; Merabet, Lotfi

    2010-01-01

    We present the design, development and an initial study changes and adaptations related to navigation that take place in the brain, by incorporating an Audio-Based Environments Simulator (AbES) within a neuroimaging environment. This virtual environment enables a blind user to navigate through a virtual representation of a real space in order to train his/her orientation and mobility skills. Our initial results suggest that this kind of virtual environment could be highly efficient as a testing, training and rehabilitation platform for learning and navigation.

  15. Virtual reality AYRA software for preoperative planning in facial allotransplantation.

    PubMed

    Fernandez-Alvarez, Jose-Alberto; Infante-Cossio, Pedro; Barrera-Pulido, Fernando; Gacto-Sanchez, Purificacion; Suarez-Mejias, Cristina; Gomez-Ciriza, Gorka; Sicilia-Castro, Domingo; Gomez-Cia, Tomas

    2014-09-01

    The purpose of this study was to validate a virtual reality software for the recording of anthropometric measurements as a first step towards matching donors with recipients in the preoperative planning process which precedes the harvest of a facial allograft. Anthropometric measurements of both soft and bone tissue were recorded in 5 cryopreserved human heads to compare conventional analogue measurements with digital measurements obtained from 3-dimensional (3D) reconstructions produced using AYRA software. To test the degree of correlation between both measuring methods, intraclass correlation coefficient (ICC) was applied to each pair of measurements. ICCs calculated were greater than 0.6 (substantial or almost perfect correlation) for all of the pairs of variables, with the exception of 2 of the measurements studied in bone tissue. In facial transplantation, preoperative planning is crucial to select an allograft whose anatomical compatibility with the recipient defect is as close as possible. The dimensions of the potential face donor must be congruent to ensure the procedure's feasibility and the adequate insertion of the allograft into the defect. The recording of anthropometric measurements with the virtual reality software displayed an equivalent correlation to those produced using a conventional analogue method. The 3D reconstructions obtained by using a virtual reality software can play a useful role to facilitate the characterization of the donor face.

  16. The Application of Virtual Planning and Navigation Devices for Mandible Reconstruction and Immediate Dental Implantation

    PubMed Central

    Rahimov, Chingiz R.; Farzaliyev, Ismayil M.; Fathi, Hamid Reza; Davudov, Mahammad M.; Aliyev, Anar; Hasanov, Emin

    2015-01-01

    Routine reconstruction of subtotal defects of the mandible and orthopedic rehabilitation supported by dental implants is achieved by means of detailed planning and lasts over a year. This article shows the outcomes of single-stage surgical treatment and immediate orthopedic rehabilitation performed with the help of preoperative virtual computer simulation. 3D investigation of pathological and donor sites, virtual simulation of tumor resection, positioning of the dental implants into fibula, virtual flap bending and transfer, virtual bending of fixing reconstruction plates, and fabrication of navigation templates and bridge prosthesis supported by dental implants were done preoperatively. The surgery included tumor resection, insertion of dental implants into fibula, elevation of fibula osteocutaneous free flap, rigid fixation within recipient site, and immediate loading by bridge orthopedic device. On 10-month follow-up, functional and esthetic results were asses as reasonable. Radiography showed dental implants to be integrated and positioned appropriately. We found that successful rehabilitation of the patients with extensive defects of the jaws could be achieved by ablative tumor resection, dental implants insertion prior to flap elevation guided by navigation templates, further osteotomy, modeling of the flap based on navigation template, flap transfer, and rigid fixation within recipient site by prebended plates, with application of prefabricated prosthesis. PMID:27162568

  17. Sex differences in virtual navigation influenced by scale and navigation experience.

    PubMed

    Padilla, Lace M; Creem-Regehr, Sarah H; Stefanucci, Jeanine K; Cashdan, Elizabeth A

    2017-04-01

    The Morris water maze is a spatial abilities test adapted from the animal spatial cognition literature and has been studied in the context of sex differences in humans. This is because its standard design, which manipulates proximal (close) and distal (far) cues, applies to human navigation. However, virtual Morris water mazes test navigation skills on a scale that is vastly smaller than natural human navigation. Many researchers have argued that navigating in large and small scales is fundamentally different, and small-scale navigation might not simulate natural human navigation. Other work has suggested that navigation experience could influence spatial skills. To address the question of how individual differences influence navigational abilities in differently scaled environments, we employed both a large- (146.4 m in diameter) and a traditional- (36.6 m in diameter) scaled virtual Morris water maze along with a novel measure of navigation experience (lifetime mobility). We found sex differences on the small maze in the distal cue condition only, but in both cue-conditions on the large maze. Also, individual differences in navigation experience modulated navigation performance on the virtual water maze, showing that higher mobility was related to better performance with proximal cues for only females on the small maze, but for both males and females on the large maze.

  18. From pre-operative cardiac modeling to intra-operative virtual environments for surgical guidance: an in vivo study

    NASA Astrophysics Data System (ADS)

    Linte, Cristian A.; Wierzbicki, Marcin; Moore, John; Wedlake, Christopher; Wiles, Andrew D.; Bainbridge, Daniel; Guiraudon, Gérard M.; Jones, Douglas L.; Peters, Terry M.

    2008-03-01

    As part of an ongoing theme in our laboratory on reducing morbidity during minimally-invasive intracardiac procedures, we developed a computer-assisted intervention system that provides safe access inside the beating heart and sufficient visualization to deliver therapy to intracardiac targets while maintaining the efficacy of the procedure. Integrating pre-operative information, 2D trans-esophageal ultrasound for real-time intra-operative imaging, and surgical tool tracking using the NDI Aurora magnetic tracking system in an augmented virtual environment, our system allows the surgeons to navigate instruments inside the heart in spite of the lack of direct target visualization. This work focuses on further enhancing intracardiac visualization and navigation by supplying the surgeons with detailed 3D dynamic cardiac models constructed from high-resolution pre-operative MR data and overlaid onto the intra-operative imaging environment. Here we report our experience during an in vivo porcine study. A feature-based registration technique previously explored and validated in our laboratory was employed for the pre-operative to intra-operative mapping. This registration method is suitable for in vivo interventional applications as it involves the selection of easily identifiable landmarks, while ensuring a good alignment of the pre-operative and intra-operative surgical targets. The resulting augmented reality environment fuses the pre-operative cardiac model with the intra-operative real-time US images with approximately 5 mm accuracy for structures located in the vicinity of the valvular region. Therefore, we strongly believe that our augmented virtual environment significantly enhances intracardiac navigation of surgical instruments, while on-target detailed manipulations are performed under real-time US guidance.

  19. Clinical application of a surgical navigation system based on virtual laparoscopy in laparoscopic gastrectomy for gastric cancer.

    PubMed

    Hayashi, Yuichiro; Misawa, Kazunari; Oda, Masahiro; Hawkes, David J; Mori, Kensaku

    2016-05-01

    Knowledge of the specific anatomical information of a patient is important when planning and undertaking laparoscopic surgery due to the restricted field of view and lack of tactile feedback compared to open surgery. To assist this type of surgery, we have developed a surgical navigation system that presents the patient's anatomical information synchronized with the laparoscope position. This paper presents the surgical navigation system and its clinical application to laparoscopic gastrectomy for gastric cancer. The proposed surgical navigation system generates virtual laparoscopic views corresponding to the laparoscope position recorded with a three-dimensional (3D) positional tracker. The virtual laparoscopic views are generated from preoperative CT images. A point-based registration aligns coordinate systems between the patient's anatomy and image coordinates. The proposed navigation system is able to display the virtual laparoscopic views using the registration result during surgery. We performed surgical navigation during laparoscopic gastrectomy in 23 cases. The navigation system was able to present the virtual laparoscopic views in synchronization with the laparoscopic position. The fiducial registration error was calculated in all 23 cases, and the average was 14.0 mm (range 6.1-29.8). The proposed surgical navigation system can provide CT-derived patient anatomy aligned to the laparoscopic view in real time during surgery. This system enables accurate identification of vascular anatomy as a guide to vessel clamping prior to total or partial gastrectomy.

  20. Preoperative surgical planning for intracranial meningioma resection by virtual reality.

    PubMed

    Tang, Hai-Liang; Sun, Hua-Ping; Gong, Ye; Mao, Ying; Wu, Jing-Song; Zhang, Xiao-Luo; Xie, Qing; Xie, Li-Qian; Zheng, Ming-Zhe; Wang, Dai-Jun; Zhu, Hong-da; Tang, Wei-Jun; Feng, Xiao-Yuan; Chen, Xian-Cheng; Zhou, Liang-Fu

    2012-06-01

    The Dextroscope system by Volume Interactions (Singapore) had been applied to minimally invasive neurosurgery in many units. This system enables the neurosurgeon to interact intuitively with the three-dimensional graphics in a direct manner resembling the way one communicates with the real objects. In the paper, we explored its values in pre-operation surgical planning for intracranial meningiomas resection. Brain computed tomography (CT), magnetic resonance imaging (MRI), and magnetic resonance venography (MRV) were performed on 10 patients with parasagittal and falcine meningiomas located on central groove area; brain CT, MRI and magnetic resonance angiography (MRA) were performed on 10 patients with anterior skull base meningiomas and 10 patients with sphenoid ridge meningiomas. All these data were transferred to Dextroscope virtual reality system, and reconstructed. Then meningiomas, skull base, brain tissue, drainage vein and cerebral arteries were displayed within the system, and their anatomic relationships were evaluated. Also, the simulation operations were performed. For parasagittal and falcine meningiomas, the relationships of tumor with drainage vein and superior sagittal sinus were clearly displayed in the Dextroscope system. For anterior skull base and sphenoid ridge meningiomas, the relationships of tumor with bilateral internal carotid arteries, anterior cerebral arteries, middle cerebral arteries and skull base were vividly displayed within the virtual reality system. Surgical planning and simulation operation of all cases were performed as well. The real operations of all patients were conducted according to the simulation with well outcomes. According to the virtual reality planning, neurosurgeons could get more anatomic information about meningioma and its surrounding structures, especially important vessels, and choose the best approach for tumor resection, which would lead to better prognosis for patients.

  1. Mongolian gerbils learn to navigate in complex virtual spaces.

    PubMed

    Thurley, Kay; Henke, Josephine; Hermann, Joachim; Ludwig, Benedikt; Tatarau, Christian; Wätzig, Aline; Herz, Andreas V M; Grothe, Benedikt; Leibold, Christian

    2014-06-01

    Virtual reality (VR) environments are increasingly used to study spatial navigation in rodents. So far behavioral paradigms in virtual realities have been limited to linear tracks or open fields. However, little is known whether rodents can learn to navigate in more complex virtual spaces. We used a VR setup with a spherical treadmill but no head-fixation, which permits animals not only to move in a virtual environment but also to freely rotate around their vertical body axis. We trained Mongolian gerbils to perform spatial tasks in virtual mazes of different complexity. Initially the animals learned to run back and forth between the two ends of a virtual linear track for food reward. Performance, measured as path length and running time between the virtual reward locations, improved to asymptotic performance within about five training sessions. When more complex mazes were presented after this training epoch, the animals generalized and explored the new environments already at their first exposure. In a final experiment, the animals also learned to perform a two-alternative forced choice task in a virtual Y-maze. Our data thus shows that gerbils can be trained to solve spatial tasks in virtual mazes and that this behavior can be used as a readout for psychophysical measurements.

  2. Dual Surgical Navigation Using Augmented and Virtual Environment Techniques

    NASA Astrophysics Data System (ADS)

    Kim, Sungmin; Hong, Jaesung; Joung, Sanghyun; Yamada, Atsushi; Matsumoto, Nozomu; Kim, Sun I.; Kim, Young Soo; Hashizume, Makoto

    2011-04-01

    To obtain additional depth and visual information in endoscopic surgery, a dual surgical navigation system using virtual reality (VR) and augmented reality (AR) techniques complementarily was developed. A VR environment was constructed in the default 3-D view of the navigation software and an AR environment was developed as a plug-in module. The spatial relationships among the target organ, endoscope, and surgical tools were visualized, and the visual information superimposing invisible organs on the endoscopic images was supplied using the AR environment. Phantom experiments and preliminary clinical application showed promising results for surgical navigation.

  3. Accuracy and reproducibility of virtual cutting guides and 3D-navigation for osteotomies of the mandible and maxilla

    PubMed Central

    Bernstein, Jonathan M.; Daly, Michael J.; Chan, Harley; Qiu, Jimmy; Goldstein, David; Muhanna, Nidal; de Almeida, John R.; Irish, Jonathan C.

    2017-01-01

    Background We set out to determine the accuracy of 3D-navigated mandibular and maxillary osteotomies with the ultimate aim to integrate virtual cutting guides and 3D-navigation into ablative and reconstructive head and neck surgery. Methods Four surgeons (two attending, two clinical fellows) completed 224 unnavigated and 224 3D-navigated osteotomies on anatomical models according to preoperative 3D plans. The osteotomized bones were scanned and analyzed. Results Median distance from the virtual plan was 2.1 mm unnavigated (IQR 2.6 mm, ≥3 mm in 33%) and 1.2 mm 3D-navigated (IQR 1.1 mm, ≥3 mm in 6%) (P<0.0001); median pitch was 4.5° unnavigated (IQR 7.1°) and 3.5° 3D-navigated (IQR 4.0°) (P<0.0001); median roll was 7.4° unnavigated (IQR 8.5°) and 2.6° 3D-navigated (IQR 3.8°) (P<0.0001). Conclusion 3D-rendering enables osteotomy navigation. 3 mm is an appropriate planning distance. The next steps are translating virtual cutting guides to free bone flap reconstruction and clinical use. PMID:28249001

  4. Visual landmarks facilitate rodent spatial navigation in virtual reality environments

    PubMed Central

    Youngstrom, Isaac A.; Strowbridge, Ben W.

    2012-01-01

    Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain areas. Virtual reality offers a unique approach to ask whether visual landmark cues alone are sufficient to improve performance in a spatial task. We found that mice could learn to navigate between two water reward locations along a virtual bidirectional linear track using a spherical treadmill. Mice exposed to a virtual environment with vivid visual cues rendered on a single monitor increased their performance over a 3-d training regimen. Training significantly increased the percentage of time avatars controlled by the mice spent near reward locations in probe trials without water rewards. Neither improvement during training or spatial learning for reward locations occurred with mice operating a virtual environment without vivid landmarks or with mice deprived of all visual feedback. Mice operating the vivid environment developed stereotyped avatar turning behaviors when alternating between reward zones that were positively correlated with their performance on the probe trial. These results suggest that mice are able to learn to navigate to specific locations using only visual cues presented within a virtual environment rendered on a single computer monitor. PMID:22345484

  5. Image Features As Virtual Beacons For Local Navigation

    NASA Astrophysics Data System (ADS)

    Engel, Antonie J.

    1989-03-01

    A technique for dynamic position correction using image features as virtual beacons is described. An algorithm which acquires new features, computes robot position correction vectors from tracked features, and maintains feature reliability statistics is detailed. The algorithm minimizes the use of matching to reduce computational expense and increase robustness. The principal inputs to the algorithm are the relative bearings observed between feature pairs. Unlike stereo-vision techniques it does not compute explicit feature range estimates. Unlike the bulk of vision based navigation methods, an accurate position estimate results from the integration of a large number of correction vectors derived from the low level analysis of many images. A control architecture for an autonomous mobile robot which makes use of this positioning technique is discussed. The general navigation problem of positioning, model building, path finding, and path execution is decomposed into local and global navigation. Local navigation is independent of high level representations, it is concerned with the immediately perceivable environment and deals with the bulk of the real-time constraints. Methods for coupling local and global navigation are explored. Simulation results showing the behavior of such a control system are presented. The motivation behind this research is the belief that a substantial subset of the navigation problem can be solved using only information obtained during early vision processing. This technique is expected to be more computationally tractable than methods based on optical flow field determination and more accurate than landmark based navigation methods.

  6. Endovascular navigation based on real/virtual environments cooperation for computer-assisted TEAM procedures

    NASA Astrophysics Data System (ADS)

    Goksu, Cemil; Haigron, Pascal; Acosta, Oscar; Lucas, Antoine

    2004-05-01

    Transfemoral Endovascular Aneurysm Management, the less invasive treatment of Aortic Abdominal Aneurysms (AAA), is a highly specialized procedure, using advanced devices and requiring a high degree of clinical expertise. There is a great need for a navigation guidance system able to make this procedure safer and more precise. In this context of computer-assisted minimally invasive interventional procedures, we propose a new framework based on the cooperation between the real environment where the intervention takes place and a patient-specific virtual environment, which contains a virtual operating room including a C-arm model as well as the 3D preoperative patient data. This approach aims to deal with the problem of lack of knowledge about soft tissue behavior by better exploiting available information before and during the intervention through a cooperative approach. In order to assist the TEAM procedure in standard interventional conditions, we applied this framework to design a 3D navigation guidance system, which has been successfully used during three TEAM interventions in the operating room. Intra-operatively, anatomical feature-based 2D/3D registration between a single 2D fluoroscopic view, reproduced from the pose planned in the virtual environment, and the preoperative CT volume, is performed by means of a chamfer distance map. The 3D localization of the endovascular devices (sheath, guide wire, prosthesis) tracked either interactively or automatically on 2D sequences, is constrained to either the 3D vascular tree or a 3D device model. Moreover, we propose a first solution to take into account the tissue deformations during this particular intervention and to update the virtual environment with the intraoperative data.

  7. Aging and Sensory Substitution in a Virtual Navigation Task.

    PubMed

    Levy-Tzedek, S; Maidenbaum, S; Amedi, A; Lackner, J

    2016-01-01

    Virtual environments are becoming ubiquitous, and used in a variety of contexts-from entertainment to training and rehabilitation. Recently, technology for making them more accessible to blind or visually impaired users has been developed, by using sound to represent visual information. The ability of older individuals to interpret these cues has not yet been studied. In this experiment, we studied the effects of age and sensory modality (visual or auditory) on navigation through a virtual maze. We added a layer of complexity by conducting the experiment in a rotating room, in order to test the effect of the spatial bias induced by the rotation on performance. Results from 29 participants showed that with the auditory cues, it took participants a longer time to complete the mazes, they took a longer path length through the maze, they paused more, and had more collisions with the walls, compared to navigation with the visual cues. The older group took a longer time to complete the mazes, they paused more, and had more collisions with the walls, compared to the younger group. There was no effect of room rotation on the performance, nor were there any significant interactions among age, feedback modality and room rotation. We conclude that there is a decline in performance with age, and that while navigation with auditory cues is possible even at an old age, it presents more challenges than visual navigation.

  8. Intracellular dynamics of hippocampal place cells during virtual navigation

    PubMed Central

    Harvey, Christopher D.; Collman, Forrest; Dombeck, Daniel A.; Tank, David W.

    2009-01-01

    Hippocampal place cells encode spatial information in rate and temporal codes. To examine the mechanisms underlying hippocampal coding, we measured the intracellular dynamics of place cells by combining in vivo whole cell recordings with a virtual reality system. Head-restrained mice, running on a spherical treadmill, interacted with a computer-generated visual environment to perform spatial behaviors. Robust place cell activity was present during movement along a virtual linear track. From whole cell recordings, we identified three subthreshold signatures of place fields: (1) an asymmetric ramp-like depolarization of the baseline membrane potential; (2) an increase in the amplitude of intracellular theta oscillations; and, (3) a phase precession of the intracellular theta oscillation relative to the extracellularly-recorded theta rhythm. These intracellular dynamics underlie the primary features of place cell rate and temporal codes. The virtual reality system developed here will enable new experimental approaches to study the neural circuits underlying navigation. PMID:19829374

  9. Ecological validity of virtual environments to assess human navigation ability

    PubMed Central

    van der Ham, Ineke J. M.; Faber, Annemarie M. E.; Venselaar, Matthijs; van Kreveld, Marc J.; Löffler, Maarten

    2015-01-01

    Route memory is frequently assessed in virtual environments. These environments can be presented in a fully controlled manner and are easy to use. Yet they lack the physical involvement that participants have when navigating real environments. For some aspects of route memory this may result in reduced performance in virtual environments. We assessed route memory performance in four different environments: real, virtual, virtual with directional information (compass), and hybrid. In the hybrid environment, participants walked the route outside on an open field, while all route information (i.e., path, landmarks) was shown simultaneously on a handheld tablet computer. Results indicate that performance in the real life environment was better than in the virtual conditions for tasks relying on survey knowledge, like pointing to start and end point, and map drawing. Performance in the hybrid condition however, hardly differed from real life performance. Performance in the virtual environment did not benefit from directional information. Given these findings, the hybrid condition may offer the best of both worlds: the performance level is comparable to that of real life for route memory, yet it offers full control of visual input during route learning. PMID:26074831

  10. Reference frames in virtual spatial navigation are viewpoint dependent

    PubMed Central

    Török, Ágoston; Nguyen, T. Peter; Kolozsvári, Orsolya; Buchanan, Robert J.; Nadasdy, Zoltan

    2014-01-01

    Spatial navigation in the mammalian brain relies on a cognitive map of the environment. Such cognitive maps enable us, for example, to take the optimal route from a given location to a known target. The formation of these maps is naturally influenced by our perception of the environment, meaning it is dependent on factors such as our viewpoint and choice of reference frame. Yet, it is unknown how these factors influence the construction of cognitive maps. Here, we evaluated how various combinations of viewpoints and reference frames affect subjects' performance when they navigated in a bounded virtual environment without landmarks. We measured both their path length and time efficiency and found that (1) ground perspective was associated with egocentric frame of reference, (2) aerial perspective was associated with allocentric frame of reference, (3) there was no appreciable performance difference between first and third person egocentric viewing positions and (4) while none of these effects were dependent on gender, males tended to perform better in general. Our study provides evidence that there are inherent associations between visual perspectives and cognitive reference frames. This result has implications about the mechanisms of path integration in the human brain and may also inspire designs of virtual reality applications. Lastly, we demonstrated the effective use of a tablet PC and spatial navigation tasks for studying spatial and cognitive aspects of human memory. PMID:25249956

  11. Navigation Using Sensory Substitution in Real and Virtual Mazes

    PubMed Central

    Chebat, Daniel-Robert; Maidenbaum, Shachar; Amedi, Amir

    2015-01-01

    Under certain specific conditions people who are blind have a perception of space that is equivalent to that of sighted individuals. However, in most cases their spatial perception is impaired. Is this simply due to their current lack of access to visual information or does the lack of visual information throughout development prevent the proper integration of the neural systems underlying spatial cognition? Sensory Substitution devices (SSDs) can transfer visual information via other senses and provide a unique tool to examine this question. We hypothesize that the use of our SSD (The EyeCane: a device that translates distance information into sounds and vibrations) can enable blind people to attain a similar performance level as the sighted in a spatial navigation task. We gave fifty-six participants training with the EyeCane. They navigated in real life-size mazes using the EyeCane SSD and in virtual renditions of the same mazes using a virtual-EyeCane. The participants were divided into four groups according to visual experience: congenitally blind, low vision & late blind, blindfolded sighted and sighted visual controls. We found that with the EyeCane participants made fewer errors in the maze, had fewer collisions, and completed the maze in less time on the last session compared to the first. By the third session, participants improved to the point where individual trials were no longer significantly different from the initial performance of the sighted visual group in terms of errors, time and collision. PMID:26039580

  12. Preoperative navigated transcranial magnetic stimulation in patients with motor eloquent lesions with emphasis on metastasis.

    PubMed

    Hendrix, Philipp; Senger, Sebastian; Griessenauer, Christoph J; Simgen, Andreas; Schwerdtfeger, Karsten; Oertel, Joachim

    2016-10-01

    Navigated transcranial magnetic stimulation (nTMS) is a frequently used, non-invasive method to map the motor cortex. It is of great value in the preoperative workup of patients that suffer from motor eloquent brain lesions. Here, we present a single-center experience using preoperative nTMS in cortical motor eloquent lesions with emphasis on metastasis. All patients that underwent preoperative nTMS between June 2013 and January 2016 were evaluated. A total of 61 patients underwent nTMS before undergoing surgery for a motor eloquent brain lesion. Patients suffered from cerebral metastasis (23), glioblastoma (16), high grade glioma WHO III (4), low grade glioma WHO II (4), lymphoma (2), meningioma (8), cavernous hemangioma (3), or arteriovenous malformation (1). Thirty patients (49.2%) presented with a preoperative motor deficit. One week after surgery, paresis had resolved or improved in 56.7% of the patients. Out of the patients with postoperative paresis, 89.5% experienced an improvement of motor status at follow-up. All metastatic lesions were completely resected compared to 78.9% of non-metastatic lesions (P = 0.02). Only 4.3% of patients with a metastatic lesion, but 26.3% of patients with a non-metastatic lesion experienced deterioration of motor function after surgery (P = 0.04). Preoperative nTMS is suitable for mapping of a variety of motor eloquent brain lesions resulting in favorable neurological outcome. Particularly in metastatic motor eloquent lesion, motor function appears to be preserved after surgery. Clin. Anat. 29:925-931, 2016. © 2016 Wiley Periodicals, Inc.

  13. Navigation based on a sensorimotor representation: a virtual reality study

    NASA Astrophysics Data System (ADS)

    Zetzsche, Christoph; Galbraith, Christopher; Wolter, Johannes; Schill, Kerstin

    2007-02-01

    We investigate the hypothesis that the basic representation of space which underlies human navigation does not resemble an image-like map and is not restricted by the laws of Euclidean geometry. For this we developed a new experimental technique in which we use the properties of a virtual environment (VE) to directly influence the development of the representation. We compared the navigation performance of human observers under two conditions. Either the VE is consistent with the geometrical properties of physical space and could hence be represented in a map-like fashion, or it contains severe violations of Euclidean metric and planar topology, and would thus pose difficulties for the correct development of such a representation. Performance is not influenced by this difference, suggesting that a map-like representation is not the major basis of human navigation. Rather, the results are consistent with a representation which is similar to a non-planar graph augmented with path length information, or with a sensorimotor representation which combines sensory properties and motor actions. The latter may be seen as part of a revised view of perceptual processes due to recent results in psychology and neurobiology, which indicate that the traditional strict separation of sensory and motor systems is no longer tenable.

  14. A Direct Comparison of Real-World and Virtual Navigation Performance in Chronic Stroke Patients.

    PubMed

    Claessen, Michiel H G; Visser-Meily, Johanna M A; de Rooij, Nicolien K; Postma, Albert; van der Ham, Ineke J M

    2016-04-01

    An increasing number of studies have presented evidence that various patient groups with acquired brain injury suffer from navigation problems in daily life. This skill is, however, scarcely addressed in current clinical neuropsychological practice and suitable diagnostic instruments are lacking. Real-world navigation tests are limited by geographical location and associated with practical constraints. It was, therefore, investigated whether virtual navigation might serve as a useful alternative. To investigate the convergent validity of virtual navigation testing, performance on the Virtual Tubingen test was compared to that on an analogous real-world navigation test in 68 chronic stroke patients. The same eight subtasks, addressing route and survey knowledge aspects, were assessed in both tests. In addition, navigation performance of stroke patients was compared to that of 44 healthy controls. A correlation analysis showed moderate overlap (r = .535) between composite scores of overall real-world and virtual navigation performance in stroke patients. Route knowledge composite scores correlated somewhat stronger (r = .523) than survey knowledge composite scores (r = .442). When comparing group performances, patients obtained lower scores than controls on seven subtasks. Whereas the real-world test was found to be easier than its virtual counterpart, no significant interaction-effects were found between group and environment. Given moderate overlap of the total scores between the two navigation tests, we conclude that virtual testing of navigation ability is a valid alternative to navigation tests that rely on real-world route exposure.

  15. An augmented reality navigation system for pediatric oncologic surgery based on preoperative CT and MRI images.

    PubMed

    Souzaki, Ryota; Ieiri, Satoshi; Uemura, Munenori; Ohuchida, Kenoki; Tomikawa, Morimasa; Kinoshita, Yoshiaki; Koga, Yuhki; Suminoe, Aiko; Kohashi, Kenichi; Oda, Yoshinao; Hara, Toshiro; Hashizume, Makoto; Taguchi, Tomoaki

    2013-12-01

    In pediatric endoscopic surgery, a limited view and lack of tactile sensation restrict the surgeon's abilities. Moreover, in pediatric oncology, it is sometimes difficult to detect and resect tumors due to the adhesion and degeneration of tumors treated with multimodality therapies. We developed an augmented reality (AR) navigation system based on preoperative CT and MRI imaging for use in endoscopic surgery for pediatric tumors. The patients preoperatively underwent either CT or MRI with body surface markers. We used an optical tracking system to register the reconstructed 3D images obtained from the CT and MRI data and body surface markers during surgery. AR visualization was superimposed with the 3D images projected onto captured live images. Six patients underwent surgery using this system. The median age of the patients was 3.5 years. Two of the six patients underwent laparoscopic surgery, two patients underwent thoracoscopic surgery, and two patients underwent laparotomy using this system. The indications for surgery were local recurrence of a Wilms tumor in one case, metastasis of rhabdomyosarcoma in one case, undifferentiated sarcoma in one case, bronchogenic cysts in two cases, and hepatoblastoma in one case. The average tumor size was 22.0±14.2 mm. Four patients were treated with chemotherapy, three patients were treated with radiotherapy before surgery, and four patients underwent reoperation. All six tumors were detected using the AR navigation system and successfully resected without any complications. The AR navigation system is very useful for detecting the tumor location during pediatric surgery, especially for endoscopic surgery. Crown Copyright © 2013. All rights reserved.

  16. Human sex differences in solving a virtual navigation problem.

    PubMed

    Astur, Robert S; Purton, Andrea J; Zaniewski, Melanie J; Cimadevilla, Jose; Markus, Etan J

    2016-07-15

    The current study examined sex differences in initial and subsequent strategies in solving a navigational problem within a virtual reality environment. We tested 163 undergraduates on a virtual T-maze task that included probe trials designed to assess whether participants were responding using either a place or response strategy. Participants were also tested on a mental rotation task and memory of the details of the virtual room. There were no differences between the sexes in copying or recalling a map of the room or on first trial performance of the T-maze. However, at trial two, males show a significant advantage in solving the task, and approximately 80% of the males adopt a place strategy to solve the T-maze whereas females at that point showed no strategy preference. Across all testing, both males and females preferentially used a place strategy. We discuss how factors such as spatial priming affect strategy preferences and how such factors may differentially affect males and females. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Correlates of Virtual Navigation Performance in Older Adults

    PubMed Central

    Korthauer, L.E.; Nowak, N.T.; Moffat, S.D.; An, Y.; Rowland, L.M; Barker, P.B.; Resnick, S.M.; Driscoll, I.

    2015-01-01

    Despite considerable evidence for deleterious effects of aging on place learning and memory, less is known about the trajectory and the putative neural mechanisms of these decrements. The virtual Morris Water Task (vMWT) is a human analog of a non-human spatial navigation task. The present study investigated longitudinal changes in place learning in 51 healthy, non-demented adults (age 30–83) who completed the vMWT and a neuropsychological battery at two time-points (interval= ~8 years). We also assessed cross-sectional associations between vMWT and brain structure, biochemical integrity, and standardized neuropsychological measures in a subset of 22 individuals who underwent MR imaging at follow-up. Despite no longitudinal decrement in vMWT performance, there were cross-sectional age differences on the vMWT favoring younger adults. Negative associations were observed between vMWT latency and gray matter volumes in the right hippocampus, bilateral thalamus, and right medial orbitofrontal cortex, and between vMWT latency and white matter fractional anisotropy in the bilateral uncinate fasciculus. Collectively, these results suggest a pattern of differences in the structural integrity of regions supporting successful navigation even in the absence of longitudinal performance decrements. PMID:26923408

  18. Interpreting collective neural activity underlying spatial navigation in virtual reality

    NASA Astrophysics Data System (ADS)

    Meshulam, Leenoy; Gauthier, Jeff; Tank, David; Bialek, William

    2015-03-01

    Traditionally, cognitive- demanding processes like spatial navigation were studied by recording the activity of single neurons. However, recent technological progress allows imaging the simultaneous activity of large neuronal populations in awake behaving animals. This progress in experimental work calls for a similar adjustments of the modeling frameworks. To achieve a description of the ``real thermodynamics'' of the neural system, we construct maximum entropy models for optical imaging data taken in vivo, from the hippocampus of mice navigating in a virtual reality environment. This provides a natural extension of statistical mechanics applicable to brain activity, by focusing on the interactions between cells rather than on single cell's activity. We aim to determine how the topology of the energy landscape predicted by the model corresponds to the location of the animal in the environment. Since large subpopulations of the neurons in this area are spatially modulated, we expect the landscape to exhibit a large ``valley'' structure of local minima, corresponding to the animal's position along the environment. Such a finding is especially of interest because the location information emerges solely from the activity patterns that are accessible to the brain.

  19. Verbalizing, Visualizing, and Navigating: The Effect of Strategies on Encoding a Large-Scale Virtual Environment

    ERIC Educational Resources Information Center

    Kraemer, David J. M.; Schinazi, Victor R.; Cawkwell, Philip B.; Tekriwal, Anand; Epstein, Russell A.; Thompson-Schill, Sharon L.

    2017-01-01

    Using novel virtual cities, we investigated the influence of verbal and visual strategies on the encoding of navigation-relevant information in a large-scale virtual environment. In 2 experiments, participants watched videos of routes through 4 virtual cities and were subsequently tested on their memory for observed landmarks and their ability to…

  20. Preoperative warm-up using a virtual reality simulator.

    PubMed

    Moldovanu, Radu; Târcoveanu, Eugen; Dimofte, Gabriel; Lupaşcu, Cristian; Bradea, Costel

    2011-01-01

    All modern surgical procedures require a high level of cognitive and psychomotor skills achieved using different training methods, but could be influenced by fatigue and other psychological factors. We evaluated the effect of warm-up exercises on operative laparoscopic performances. The surgical team operated on a consecutive series of 20 patients with gallstones. Patients were randomly allocated in 2 groups: group A to be operated on without warm-up exercises and group B to be operated on after a short-term warm-up. All the patients were operated on by the same surgical team. The full-time records of the operation were analyzed by 2 independent reviewers. A modified simplified Global Rating Score (GRS) was used to assess the surgical procedures. A training module using the Lap Mentor simulator was designed for the warm-up. Better performances were noted by both observers in group B only regarding "Respect for tissue" scores (3.75 0.16 vs 4.43 0.20, P=.021 and 3.87 0.22 vs 4.57 0.20, P=.041) achieving significant or marginally significant differences for all categories; GRS scores for "time and motion" and "overall impression" tend to be better after warm-up, but differences failed to reach statistical significance in our series. Surgeons, even the most experienced in laparoscopic surgery, can increase specific psychomotor skills associated with a laparoscopic environment by doing simple exercises on a virtual reality simulator, just before an operation. These improvements are reflected in more accurate handling of tissue during laparoscopic cholecystectomy.

  1. Preoperative Warm-Up Using a Virtual Reality Simulator

    PubMed Central

    Târcoveanu, Eugen; Dimofte, Gabriel; Lupaşcu, Cristian; Bradea, Costel

    2011-01-01

    Background and Objectives: All modern surgical procedures require a high level of cognitive and psychomotor skills achieved using different training methods, but could be influenced by fatigue and other psychological factors. We evaluated the effect of warm-up exercises on operative laparoscopic performances. Methods: The surgical team operated on a consecutive series of 20 patients with gallstones. Patients were randomly allocated in 2 groups: group A to be operated on without warm-up exercises and group B to be operated on after a short-term warm-up. All the patients were operated on by the same surgical team. The full-time records of the operation were analyzed by 2 independent reviewers. A modified simplified Global Rating Score (GRS) was used to assess the surgical procedures. A training module using the Lap Mentor simulator was designed for the warm-up. Results: Better performances were noted by both observers in group B only regarding “Respect for tissue” scores (3.75±0.16 vs 4.43±0.20, P=.021 and 3.87±0.22 vs 4.57±0.20, P=.041) achieving significant or marginally significant differences for all categories; GRS scores for “time and motion” and “overall impression” tend to be better after warm-up, but differences failed to reach statistical significance in our series. Conclusion: Surgeons, even the most experienced in laparoscopic surgery, can increase specific psychomotor skills associated with a laparoscopic environment by doing simple exercises on a virtual reality simulator, just before an operation. These improvements are reflected in more accurate handling of tissue during laparoscopic cholecystectomy. PMID:22643511

  2. Effect of an Immersive Preoperative Virtual Reality Experience on Patient Reported Outcomes: A Randomized Controlled Trial.

    PubMed

    Bekelis, Kimon; Calnan, Daniel; Simmons, Nathan; MacKenzie, Todd A; Kakoulides, George

    2017-06-01

    To investigate the effect of exposure to a virtual reality (VR) environment preoperatively on patient-reported outcomes for surgical operations. There is a scarcity of well-developed quality improvement initiatives targeting patient satisfaction. We performed a randomized controlled trial of patients undergoing cranial and spinal operations in a tertiary referral center. Patients underwent a 1:1 randomization to an immersive preoperative VR experience or standard preoperative experience stratified on type of operation. The primary outcome measures were the Evaluation du Vecu de l'Anesthesie Generale (EVAN-G) score and the Amsterdam Preoperative Anxiety and Information (APAIS) score, as markers of the patient's experience during the surgical encounter. During the study period, a total of 127 patients (mean age 55.3 years, 41.9% females) underwent randomization. The average EVAN-G score was 84.3 (standard deviation, SD, 6.4) after VR, and 64.3 (SD, 11.7) after standard preoperative experience (difference, 20.0; 95% confidence interval, CI, 16.6-23.3). Exposure to an immersive VR experience also led to higher APAIS score (difference, 29.9; 95% CI, 24.5-35.2). In addition, VR led to lower preoperative VAS stress score (difference, -41.7; 95% CI, -33.1 to -50.2), and higher preoperative VAS preparedness (difference, 32.4; 95% CI, 24.9-39.8), and VAS satisfaction (difference, 33.2; 95% CI, 25.4-41.0) scores. No association was identified with VAS stress score (difference, -1.6; 95% CI, -13.4 to 10.2). In a randomized controlled trial, we demonstrated that patients exposed to preoperative VR had increased satisfaction during the surgical encounter. Harnessing the power of this technology, hospitals can create an immersive environment that minimizes stress, and enhances the perioperative experience.

  3. Real world navigation independence in the early blind correlates with differential brain activity associated with virtual navigation.

    PubMed

    Halko, Mark A; Connors, Erin C; Sánchez, Jaime; Merabet, Lotfi B

    2014-06-01

    Navigating is a complex cognitive task that places high demands on spatial abilities, particularly in the absence of sight. Significant advances have been made in identifying the neural correlates associated with various aspects of this skill; however, how the brain is able to navigate in the absence of visual experience remains poorly understood. Furthermore, how neural network activity relates to the wide variability in navigational independence and skill in the blind population is also unknown. Using functional magnetic resonance imaging, we investigated the neural correlates of audio-based navigation within a large scale, indoor virtual environment in early profoundly blind participants with differing levels of spatial navigation independence (assessed by the Santa Barbara Sense of Direction scale). Performing path integration tasks in the virtual environment was associated with activation within areas of a core network implicated in navigation. Furthermore, we found a positive relationship between Santa Barbara Sense of Direction scores and activation within right temporal parietal junction during the planning and execution phases of the task. These findings suggest that differential navigational ability in the blind may be related to the utilization of different brain network structures. Further characterization of the factors that influence network activity may have important implications regarding how this skill is taught in the blind community. Copyright © 2013 Wiley Periodicals, Inc.

  4. Real world navigation independence in the early blind correlates with differential brain activity associated with virtual navigation

    PubMed Central

    Halko, Mark A.; Connors, Erin C.; Sánchez, Jaime; Merabet, Lotfi B.

    2014-01-01

    Navigating is a complex cognitive task that places high demands on spatial abilities, particularly in the absence of sight. Significant advances have been made in identifying the neural correlates associated with various aspects of this skill, however, how the brain is able to navigate in the absence of visual experience remains poorly understood. Furthermore, how neural network activity relates to the wide variability in navigational independence and skill in the blind population is also unknown. Using fMRI, we investigated the neural correlates of audio-based navigation within a large scale, indoor virtual environment in early profoundly blind participants with differing levels of spatial navigation independence (assessed by the Santa Barbara Sense of Direction (SBSoD) scale). Performing path integration tasks in the virtual environment was associated with activation within areas of a core network implicated in navigation. Furthermore, we found a positive relationship between SBSoD scores and activation within right temporal parietal junction (TPJ) during the planning and execution phases of the task. These findings suggest that differential navigational ability in the blind may be related to the utilization of different brain network structures. Further characterization of the factors that influence network activity may have important implications regarding how this skill is taught in the blind community. PMID:24027192

  5. Navigating through virtual environments: visual realism improves spatial cognition.

    PubMed

    Meijer, Frank; Geudeke, Branko L; van den Broek, Egon L

    2009-10-01

    Recent advances in computer technology have significantly facilitated the use of virtual environments (VE) for small and medium enterprises (SME). However, achieving visual realism in such VE requires high investments in terms of time and effort, while its usefulness has not yet become apparent from research. Other qualities of VE, such as the use of large displays, proved its effectiveness in enhancing the individual user's spatial cognition. The current study assessed whether the same benefits apply for visual realism in VE. Thirty-two participants were divided into two groups, who explored either a photorealistic or a nonrealistic supermarket presented on a large screen. The participants were asked to navigate through the supermarket on a predetermined route. Subsequently, spatial learning was tested in four pen-and-paper tests that assessed how accurately they had memorized the route and the environment's spatial layout. The study revealed increased spatial learning from the photorealistic compared to the nonrealistic supermarket. Specifically, participants performed better on tests that involved egocentric spatial knowledge. The results suggest visual realism is useful because it increases the user's spatial knowledge in the VE. Therefore, the current study provides clear evidence that it is worthwhile for SME to invest in achieving visual realism in VE.

  6. Neurocognitive Treatment for a Patient with Alzheimer’s Disease Using a Virtual Reality Navigational Environment

    PubMed Central

    White, Paul J.F.; Moussavi, Zahra

    2016-01-01

    In this case study, a man at the onset of Alzheimer’s disease (AD) was enrolled in a cognitive treatment program based upon spatial navigation in a virtual reality (VR) environment. We trained him to navigate to targets in a symmetric, landmark-less virtual building. Our research goals were to determine whether an individual with AD could learn to navigate in a simple VR navigation (VRN) environment and whether that training could also bring real-life cognitive benefits. The results show that our participant learned to perfectly navigate to desired targets in the VRN environment over the course of the training program. Furthermore, subjective feedback from his primary caregiver (his wife) indicated that his skill at navigating while driving improved noticeably and that he enjoyed cognitive improvement in his daily life at home. These results suggest that VRN treatments might benefit other people with AD. PMID:27840579

  7. Real-Time MRI Navigated Ultrasound for Preoperative Tumor Evaluation in Breast Cancer Patients: Technique and Clinical Implementation.

    PubMed

    Park, Ah Young; Seo, Bo Kyoung

    2016-01-01

    Real-time magnetic resonance imaging (MRI) navigated ultrasound is an image fusion technique to display the results of both MRI and ultrasonography on the same monitor. This system is a promising technique to improve lesion detection and analysis, to maximize advantages of each imaging modality, and to compensate the disadvantages of both MRI and ultrasound. In evaluating breast cancer stage preoperatively, MRI and ultrasound are the most representative imaging modalities. However, sometimes difficulties arise in interpreting and correlating the radiological features between these two different modalities. This pictorial essay demonstrates the technical principles of the real-time MRI navigated ultrasound, and clinical implementation of the system in preoperative evaluation of tumor extent, multiplicity, and nodal status in breast cancer patients.

  8. Virtual 3-dimensional preoperative planning with the dextroscope for excision of a 4th ventricular ependymoma.

    PubMed

    Anil, S M; Kato, Y; Hayakawa, M; Yoshida, K; Nagahisha, S; Kanno, T

    2007-04-01

    Advances in computer imaging and technology have facilitated enhancement in surgical planning with a 3-dimensional model of the surgical plan of action utilizing advanced visualization tools in order to plan individual interactive operations with the aid of the dextroscope. This provides a proper 3-dimensional imaging insight to the pathological anatomy and sets a new dimension in collaboration for training and education. The case of a seventeen-year-old female, being operated with the aid of a preoperative 3-dimensional virtual reality planning and the practical application of the neurosurgical operation, is presented. This young lady presented with a two-year history of recurrent episodes of severe, global, throbbing headache with episodes of projectile vomiting associated with shoulder pain which progressively worsened. She had no obvious neurological deficits on clinical examination. CT and MRI showed a contrast-enhancing midline posterior fossa space-occupying lesion. Utilizing virtual imaging technology with the aid of a dextroscope which generates stereoscopic images, a 3-dimensional image was produced with the CT and MRI images. A preoperative planning for excision of the lesion was made and a real-time 3-dimensional volume was produced and surgical planning with the dextroscope was made and the lesion excised. Virtual reality has brought new proportions in 3-dimensional planning and management of various complex neuroanatomical problems that are faced during various operations. Integration of 3-dimensional imaging with stereoscopic vision makes understanding the complex anatomy easier and helps improve decision making in patient management.

  9. Technologies Render Views of Earth for Virtual Navigation

    NASA Technical Reports Server (NTRS)

    2012-01-01

    On a December night in 1995, 159 passengers and crewmembers died when American Airlines Flight 965 flew into the side of a mountain while in route to Cali, Colombia. A key factor in the tragedy: The pilots had lost situational awareness in the dark, unfamiliar terrain. They had no idea the plane was approaching a mountain until the ground proximity warning system sounded an alarm only seconds before impact. The accident was of the kind most common at the time CFIT, or controlled flight into terrain says Trey Arthur, research aerospace engineer in the Crew Systems and Aviation Operations Branch at NASA s Langley Research Center. In situations such as bad weather, fog, or nighttime flights, pilots would rely on airspeed, altitude, and other readings to get an accurate sense of location. Miscalculations and rapidly changing conditions could contribute to a fully functioning, in-control airplane flying into the ground. To improve aviation safety by enhancing pilots situational awareness even in poor visibility, NASA began exploring the possibilities of synthetic vision creating a graphical display of the outside terrain on a screen inside the cockpit. How do you display a mountain in the cockpit? You have to have a graphics-powered computer, a terrain database you can render, and an accurate navigation solution, says Arthur. In the mid-1990s, developing GPS technology offered a means for determining an aircraft s position in space with high accuracy, Arthur explains. As the necessary technologies to enable synthetic vision emerged, NASA turned to an industry partner to develop the terrain graphical engine and database for creating the virtual rendering of the outside environment.

  10. Virtual navigation for memory rehabilitation in a traumatic brain injured patient.

    PubMed

    Caglio, M; Latini-Corazzini, L; D'Agata, F; Cauda, F; Sacco, K; Monteverdi, S; Zettin, M; Duca, S; Geminiani, G

    2012-01-01

    The use of 3D video games in memory rehabilitation has been explored very little. A virtual navigation task allows participants to encode the spatial layout of the virtual environment and activate areas involved in memory processing. We describe the rehabilitation of a 24-year-old man with traumatic brain injury presenting memory deficits, and evaluate the efficacy of a navigational training program measuring neuropsychological changes and fMRI modification cerebral activations. Memory improvement appears to be present both after navigational training and in follow-up testing. Furthermore, fMRI data suggest that this training may increase activation of the hippocampal and parahippocampal brain regions. The results suggest that intensive training in virtual navigational tasks may result in an enhancement of memory function in brain-damaged adults.

  11. Accuracy of pedicle screw placement based on preoperative computed tomography versus intraoperative data set acquisition for spinal navigation system.

    PubMed

    Liu, Hao; Chen, Weikai; Liu, Tao; Meng, Bin; Yang, Huilin

    2017-01-01

    To investigate the accuracy of pedicle screw placement based on preoperative computed tomography in comparison with intraoperative data set acquisition for spinal navigation system. The PubMed (MEDLINE), EMBASE, and Web of Science were systematically searched for the literature published up to September 2015. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Statistical analysis was performed using the Review Manager 5.3. The dichotomous data for the pedicle violation rate was summarized using relative risk (RR) and 95% confidence intervals (CIs) with the fixed-effects model. The level of significance was set at p < 0.05. For this meta-analysis, seven studies used a total of 579 patients and 2981 screws. The results revealed that the accuracy of intraoperative data set acquisition method is significantly higher than preoperative one using 2 mm grading criteria (RR: 1.82, 95% CI: 1.09, 3.04, I(2) = 0%, p = 0.02). However, there was no significant difference between two kinds of methods at the 0 mm grading criteria (RR: 1.13, 95% CI: 0.88, 1.46, I(2) = 17%, p = 0.34). Using the 2-mm grading criteria, there was a higher accuracy of pedicle screw insertion in O-arm-assisted navigation than CT-based navigation method (RR: 1.96, 95% CI: 1.05, 3.64, I(2) = 0%, p = 0.03). The accuracy between CT-based navigation and two-dimensional-based navigation showed no significant difference (RR: 1.02, 95% CI: 0.35-3.03, I(2) = 0%, p = 0.97). The intraoperative data set acquisition method may decrease the incidence of perforated screws over 2 mm but not increase the number of screws fully contained within the pedicle compared to preoperative CT-based navigation system. A significantly higher accuracy of intraoperative (O-arm) than preoperative CT-based navigation was revealed using 2 mm grading criteria.

  12. Low-frequency theta oscillations in the human hippocampus during real-world and virtual navigation

    PubMed Central

    Bohbot, Véronique D.; Copara, Milagros S.; Gotman, Jean; Ekstrom, Arne D.

    2017-01-01

    Low-Frequency Oscillations (LFO) in the range of 7–9 Hz, or theta rhythm, has been recorded in rodents ambulating in the real world. However, intra-hippocampus EEG recordings during virtual navigation in humans have consistently reported LFO that appear to predominate around 3–4 Hz. Here we report clear evidence of 7–9 Hz rhythmicity in raw intra-hippocampus EEG traces during real as well as virtual movement. Oscillations typically occur at a lower frequency in virtual than real world navigation. This study highlights the possibility that human and rodent hippocampal EEG activity are not as different as previously reported and this difference may arise, in part, due to the lack of actual movement in previous human navigation studies, which were virtual. PMID:28195129

  13. Low-frequency theta oscillations in the human hippocampus during real-world and virtual navigation.

    PubMed

    Bohbot, Véronique D; Copara, Milagros S; Gotman, Jean; Ekstrom, Arne D

    2017-02-14

    Low-Frequency Oscillations (LFO) in the range of 7-9 Hz, or theta rhythm, has been recorded in rodents ambulating in the real world. However, intra-hippocampus EEG recordings during virtual navigation in humans have consistently reported LFO that appear to predominate around 3-4 Hz. Here we report clear evidence of 7-9 Hz rhythmicity in raw intra-hippocampus EEG traces during real as well as virtual movement. Oscillations typically occur at a lower frequency in virtual than real world navigation. This study highlights the possibility that human and rodent hippocampal EEG activity are not as different as previously reported and this difference may arise, in part, due to the lack of actual movement in previous human navigation studies, which were virtual.

  14. Three-dimensional preoperative virtual planning and template use for surgical correction of craniosynostosis.

    PubMed

    Mardini, Samir; Alsubaie, Saad; Cayci, Cenk; Chim, Harvey; Wetjen, Nicholas

    2014-03-01

    Surgical correction of craniosynostosis aims to remodel the cranial vault to achieve a morphology approaching that of age-matched norms. However, current surgical technique is highly subjective and based largely on the surgeon's artistic vision in creating a normal head shape. Here, we present our technique and report our experience with the use of virtual surgery using computer-assisted design (CAD)/computer-assisted manufacturing (CAM) techniques to create a prefabricated template for the planning of osteotomies and the placement of bone segments, to achieve standardised, objective and precise correction of craniosynostosis. Four patients who underwent cranial vault remodelling (CVR; three metopic synostosis and one sagittal synostosis) underwent virtual surgical planning (VSP) preoperatively using CAD/CAM techniques. VSP allows pre-planning of osteotomies to achieve the desired cranial vault shape. Surgical osteotomies and placement of bone segments were performed intra-operatively based on prefabricated templates. All patients demonstrated markedly improved head shape postoperatively. One patient developed a subdural haematoma 6 weeks postoperatively subsequent to a fall where he hit his head. The haematoma was drained and a soft spot was present in that location 3 months postoperatively. The use of virtual surgery and prefabricated cutting guides allows for a more precise and rapid reconstruction. Surgical osteotomies are pre-planned and rapidly performed using a template, and precise placement of calvarial bone segments is achieved without the need for subjective assessment of the desired calvarial shape. In addition, patients and families have a significantly better understanding of the disease process and anticipated surgery preoperatively with the visualisation achieved through virtual surgery. This results in better alignment of hopes and expectations between the parents and surgeons. Copyright © 2013 British Association of Plastic, Reconstructive and

  15. Evaluation of a conceptual framework for predicting navigation performance in virtual reality.

    PubMed

    Grübel, Jascha; Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R

    2017-01-01

    Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition.

  16. Cognitive ergonomics in virtual environments: development of an intuitive and appropriate input device for navigating in a virtual maze.

    PubMed

    Stefani, Oliver; Mager, Ralph; Mueller-Spahn, Franz; Sulzenbacher, Hubert; Bekiaris, Evangelos; Wiederhold, Brenda K; Patel, Harshada; Bullinger, Alex H

    2005-09-01

    For patients suffering from mild cognitive impairments, the navigation through a virtual maze should be as intuitive and efficient as possible in order to minimize cognitive and physical strain. This paper discusses the appropriateness of interaction devices for being used for easy navigation tasks. Information gained from human centered evaluation was used to develop an intuitive and ergonomic interaction device. Two experiments examined the usability of tracked interaction devices. Usability problems with the devices are discussed. The findings from the experiments were translated into general design guidance, in addition to specific recommendations. A new device was designed on the basis of these recommendations and its usability was evaluated in a second experiment. The results were used to develop a lightweight interaction device for navigation in the virtual maze.

  17. [Application of virtual reality system for individualized preoperative planning of sphenoidal ridge meningioma].

    PubMed

    Ma, Shunchang; Chen, Suhua; Hu, Yeshuai; Qi, Jianfa; Li, Zhiqiang; Cun, Enhao; Wang, Liguo; Shi, Xiang'en; Yang, Jun

    2014-12-09

    To evaluate the usefulness of virtual reality (VR) technique for individualized preoperative planning of sphenoidal ridge meningioma. Multiple imaging data of CTA/MR were acquired from 41 surgical patients with sphenoidal ridge meningioma during the period from July 2009 to June 2013 were transferred into the Dextroscope system. A suite of built-in 3D tools enabled users to obtain measurement and simulated intraoperative viewpoint about the lesion and adjacent anatomic structures. A sophisticated preoperative plan was defined.Operative duration, total resection rate, complication rate and KPS scores were compared with control group undergoing routine operation (n = 27). 3D stereoscopic VR images in accordance with reality were reconstructed for 41 cases. As compared with control group,VR preoperative plan could shorten operative duration and reduce complication rate (P < 0.05). However, there was no improvement in total resection rate or KPS score (P > 0.50). VR technique of Dextroscope system offers comprehensive information of sphenoidal ridge and related neurovascular anatomical structure. Thus it may aid surgical planning and facilitate individualized operation.

  18. A model for predicting pathologist's velocity profiles when navigating virtual slides.

    PubMed

    Gómez, Francisco; Romero, Eduardo

    2010-02-01

    Navigation through large microscopic images is a potential benefit for histology or pathology teaching, for improving the quality of diagnosis in pathology, or for communicating pathologists in some telemedicine applications. However, the size of this kind of images is prohibitive for navigation with conventional techniques. This article presents a soft computing model, which permits to anticipate the pathologist trajectories in diagnosis tasks when exploring virtual slides. The Bayesian strategy combines an offline model of a baseline pathologist knowledge (the prior) and a prediction online module (the likelihood) that captures a particular pathologist navigation pattern. While optimal parameters for the biologically inspired offline model are calculated using an Expectation-Maximization strategy, prediction is carried out by a particle filter. Parameters are estimated from several series of actual navigations performed by several pathologists in different virtual slides. The present approach is compared with other conventional prediction methods and decreases the calculated MSE in about a 50% for the entire group of pathologists.

  19. Role of virtual surgery in preoperative planning: assessing the individual components of functional nasal airway surgery.

    PubMed

    Rhee, John S; Cannon, Daniel E; Frank, Dennis O; Kimbell, Julia S

    2012-01-01

    To demonstrate the effect of individual components of functional nasal airway surgery in a patient with multifactorial obstruction and to discuss the potential benefit of computational fluid dynamics (CFD)–aided virtual surgery. A 53-year-old woman underwent septoplasty,turbinate reduction, and nasal valve repair. Presurgery and postsurgery digital nasal models were created from computed tomographic images, and nasal resistance was calculated using CFD techniques. The digital models were then manipulated to isolate the effects of the components of the surgery, creating a nasal valverepair alone model and a septoplasty/turbinate reduction alone model. Bilateral nasal resistance in the postsurgery model was approximately 25% less than presurgery values.Similarly, CFD analysis showed reductions in nasal resistance of the virtual models: 19% reduction with intranasal surgery alone and 6% reduction with nasal valve repair alone. Most of the reduction in nasal resistance was accomplished with performance of septoplasty and inferior turbinate reduction. The contribution of nasal valve repair was less in comparison but not insignificant.This pilot study implies that CFD-aided virtual surgery may be useful as part of preoperative planning inpatients with multifactorial anatomical nasal airwayobstruction

  20. The effect of time pressure on stress levels during virtual wheelchair navigation.

    PubMed

    Lamti, Hachem A; Gorce, Philippe

    2016-08-01

    In this work stress is assessed based on EEG features. We focus our efforts on the correlation between subjective ratings and cerebral indices during virtual navigation scenarios. Ten male paraplegic subjects took part in the experiment and navigated in a virtual indoor environment. They had to fulfill two missions where time pressure parameter is introduced. Subjects were equipped with Electroencephalography sensors. Temporal and frequency data were filtered and extracted. A correlation study was conducted based on principal component analysis, Fisher's tests and ANOVA. The results showed that the introduction of time pressure has a significant impact on stress levels.

  1. Navigation strategy training using virtual reality in six chronic stroke patients: A novel and explorative approach to the rehabilitation of navigation impairment.

    PubMed

    Claessen, Michiel H G; van der Ham, Ineke J M; Jagersma, Elbrich; Visser-Meily, Johanna M A

    2016-10-01

    Recent studies have shown that navigation impairment is a common complaint after brain injury. Effective training programmes aiming to improve navigation ability in neurological patients are, however, scarce. The few reported programmes are merely focused on recalling specific routes rather than encouraging brain-damaged patients to use an alternative navigation strategy, applicable to any route. Our aim was therefore to investigate the feasibility of a (virtual reality) navigation training as a tool to instruct chronic stroke patients to adopt an alternative navigation strategy. Navigation ability was systematically assessed before the training. The training approach was then determined based on the individual pattern of navigation deficits of each patient. The use of virtual reality in the navigation strategy training in six middle-aged stroke patients was found to be highly feasible. Furthermore, five patients learned to (partially) apply an alternative navigation strategy in the virtual environment, suggesting that navigation strategies are mouldable rather than static. In the evaluation of their training experiences, the patients judged the training as valuable and proposed some suggestions for further improvement. The notion that the navigation strategy people use can be influenced after a short training procedure is a novel finding and initiates a direction for future studies.

  2. Detecting allocentric and egocentric navigation deficits in patients with schizophrenia and bipolar disorder using virtual reality.

    PubMed

    Mohammadi, Alireza; Hesami, Ehsan; Kargar, Mahmoud; Shams, Jamal

    2017-09-07

    Present evidence suggests that the use of virtual reality has great advantages in evaluating visuospatial navigation and memory for the diagnosis of psychiatric or other neurological disorders. There are a few virtual reality studies on allocentric and egocentric memories in schizophrenia, but studies on both memories in bipolar disorder are lacking. The objective of this study was to compare the performance of allocentric and egocentric memories in patients with schizophrenia and bipolar disorder. For this resolve, an advanced virtual reality navigation task (VRNT) was presented to distinguish the navigational performances of these patients. Twenty subjects with schizophrenia and 20 bipolar disorder patients were compared with 20 healthy-matched controls on the newly developed VRNT consisting of a virtual neighbourhood (allocentric memory) and a virtual maze (egocentric memory). The results demonstrated that schizophrenia patients were significantly impaired on all allocentric, egocentric, visual, and verbal memory tasks compared with patients with bipolar disorder and normal subjects. Dissimilarly, the performance of patients with bipolar disorder was slightly lower than that of control subjects in all these abilities, but no significant differences were observed. It was concluded that allocentric and egocentric navigation deficits are detectable in patients with schizophrenia and bipolar disorder using VRNT, and this task along with RAVLT and ROCFT can be used as a valid clinical tool for distinguishing these patients from normal subjects.

  3. Comparison of navigated transcranial magnetic stimulation and functional magnetic resonance imaging for preoperative mapping in rolandic tumor surgery.

    PubMed

    Coburger, Jan; Musahl, Christian; Henkes, Hans; Horvath-Rizea, Diana; Bittl, Markus; Weissbach, Claudia; Hopf, Nikolai

    2013-01-01

    Navigated transcranial magnetic stimulation (nTMS) is a novel tool for preoperative functional mapping. It detects eloquent cortical areas directly, comparable to intraoperative direct cortical stimulation (DCS). The aim of this study was to evaluate the advantage of nTMS in comparison with functional magnetic resonance imaging (fMRI) in the clinical setting. Special focus was placed on accuracy of motor cortex localization in patients with rolandic lesions. Thirty consecutive patients were enrolled in the study. All patients received an fMRI and nTMS examination preoperatively. Feasibility of the technique and spatial resolution of upper and lower extremity cortical mapping were compared with fMRI. Consistency of preoperative mapping with intraoperative DCS was assessed via the neuronavigation system. nTMS was feasible in all 30 patients. fMRI was impossible in 7 out of 30 patients with special clinical conditions, pediatric patients, central vascular lesions, or compliance issues. The mean accuracy to localize motor cortex of nTMS was higher than in fMRI. In the subgroup of intrinsic tumors, nTMS produced statistically significant higher accuracy scores of the lower extremity localization than fMRI. fMRI failed to localize hand or leg areas in 6 out of 23 cases. Using nTMS, a preoperative localization of the central sulcus was possible in all patients. Verification of nTMS motor cortex localization with DCS was achieved in all cases. The fMRI localization of the hand area proved to be postcentral in one case. nTMS has fewer restrictions for preoperative functional mapping than fMRI and requires only a limited level of compliance. nTMS scores higher on the accuracy scale than fMRI. nTMS represents a highly valuable supplement for the preoperative functional planning in the clinical routine.

  4. Active route learning in virtual environments: disentangling movement control from intention, instruction specificity, and navigation control.

    PubMed

    von Stülpnagel, Rul; Steffens, Melanie C

    2013-09-01

    Active navigation research examines how physiological and psychological involvement in navigation benefits spatial learning. However, existing conceptualizations of active navigation comprise separable, distinct factors. This research disentangles the contributions of movement control (i.e., self-contained vs. observed movement) as a central factor from learning intention (Experiment 1), instruction specificity and instruction control (Experiment 2), as well as navigation control (Experiment 3) to spatial learning in virtual environments. We tested the effects of these factors on landmark recognition (landmark knowledge), tour-integration and route navigation (route knowledge). Our findings suggest that movement control leads to robust advantages in landmark knowledge as compared to observed movement. Advantages in route knowledge do not depend on learning intention, but on the need to elaborate spatial information. Whenever the necessary level of elaboration is assured for observed movement, too, the development of route knowledge is not inferior to that for self-contained movement.

  5. Visual Landmarks Facilitate Rodent Spatial Navigation in Virtual Reality Environments

    ERIC Educational Resources Information Center

    Youngstrom, Isaac A.; Strowbridge, Ben W.

    2012-01-01

    Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain…

  6. Visual Landmarks Facilitate Rodent Spatial Navigation in Virtual Reality Environments

    ERIC Educational Resources Information Center

    Youngstrom, Isaac A.; Strowbridge, Ben W.

    2012-01-01

    Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain…

  7. The contribution of virtual reality to the diagnosis of spatial navigation disorders and to the study of the role of navigational aids: A systematic literature review.

    PubMed

    Cogné, M; Taillade, M; N'Kaoua, B; Tarruella, A; Klinger, E; Larrue, F; Sauzéon, H; Joseph, P-A; Sorita, E

    2017-06-01

    Spatial navigation, which involves higher cognitive functions, is frequently implemented in daily activities, and is critical to the participation of human beings in mainstream environments. Virtual reality is an expanding tool, which enables on one hand the assessment of the cognitive functions involved in spatial navigation, and on the other the rehabilitation of patients with spatial navigation difficulties. Topographical disorientation is a frequent deficit among patients suffering from neurological diseases. The use of virtual environments enables the information incorporated into the virtual environment to be manipulated empirically. But the impact of manipulations seems differ according to their nature (quantity, occurrence, and characteristics of the stimuli) and the target population. We performed a systematic review of research on virtual spatial navigation covering the period from 2005 to 2015. We focused first on the contribution of virtual spatial navigation for patients with brain injury or schizophrenia, or in the context of ageing and dementia, and then on the impact of visual or auditory stimuli on virtual spatial navigation. On the basis of 6521 abstracts identified in 2 databases (Pubmed and Scopus) with the keywords « navigation » and « virtual », 1103 abstracts were selected by adding the keywords "ageing", "dementia", "brain injury", "stroke", "schizophrenia", "aid", "help", "stimulus" and "cue"; Among these, 63 articles were included in the present qualitative analysis. Unlike pencil-and-paper tests, virtual reality is useful to assess large-scale navigation strategies in patients with brain injury or schizophrenia, or in the context of ageing and dementia. Better knowledge about both the impact of the different aids and the cognitive processes involved is essential for the use of aids in neurorehabilitation. Copyright © 2016. Published by Elsevier Masson SAS.

  8. Acute stress switches spatial navigation strategy from egocentric to allocentric in a virtual Morris water maze.

    PubMed

    van Gerven, Dustin J H; Ferguson, Thomas; Skelton, Ronald W

    2016-07-01

    Stress and stress hormones are known to influence the function of the hippocampus, a brain structure critical for cognitive-map-based, allocentric spatial navigation. The caudate nucleus, a brain structure critical for stimulus-response-based, egocentric navigation, is not as sensitive to stress. Evidence for this comes from rodent studies, which show that acute stress or stress hormones impair allocentric, but not egocentric navigation. However, there have been few studies investigating the effect of acute stress on human spatial navigation, and the results of these have been equivocal. To date, no study has investigated whether acute stress can shift human navigational strategy selection between allocentric and egocentric navigation. The present study investigated this question by exposing participants to an acute psychological stressor (the Paced Auditory Serial Addition Task, PASAT), before testing navigational strategy selection in the Dual-Strategy Maze, a modified virtual Morris water maze. In the Dual-Strategy maze, participants can chose to navigate using a constellation of extra-maze cues (allocentrically) or using a single cue proximal to the goal platform (egocentrically). Surprisingly, PASAT stress biased participants to solve the maze allocentrically significantly more, rather than less, often. These findings have implications for understanding the effects of acute stress on cognitive function in general, and the function of the hippocampus in particular.

  9. Neurodevelopmental aspects of spatial navigation: a virtual reality fMRI study.

    PubMed

    Pine, Daniel S; Grun, Joseph; Maguire, Eleanor A; Burgess, Neil; Zarahn, Eric; Koda, Vivian; Fyer, Abby; Szeszko, Philip R; Bilder, Robert M

    2002-02-01

    Navigation in spatial contexts has been studied in diverse species, yielding insights into underlying neural mechanisms and their phylogenetic progression. Spatial navigation in humans is marked by age-related changes that may carry important implications for understanding cortical development. The emergence of "allocentric" processing, reflecting that ability to use viewer-independent spatial abstractions, represents an important developmental change. We used fMRI to map brain regions engaged during memory-guided navigation in a virtual reality environment in adolescents and adults. Blood oxygen level-dependent (BOLD) signal was monitored in eight adolescents and eight adults in a 1.5-T MRI scanner during three conditions: (1) memory-guided navigation (NAV); (2) arrow-guided navigation (ARROW); and (3) fixation (FIX). We quantified navigation ability during scanning and allocentric memory after scanning, based on subjects' ability to label a previously unseen, aerial view of the town. Adolescents and adults exhibited similar memory-guided navigation ability, but adults exhibited superior allocentric memory ability. Memory-guided navigation ability during scanning correlated with BOLD change between NAV/ARROWS in various regions, including a right frontal and right-anterior medial temporal lobe region. Age group and allocentric memory together explained significant variance in BOLD change in temporoparietal association cortex and the cerebellum, particularly in the left hemisphere. Consistent with developmental models, these findings relate maturation in the coding of spatial information to functional changes in a distributed, left-lateralized neural network.

  10. Age and active navigation effects on episodic memory: A virtual reality study.

    PubMed

    Sauzéon, Hélène; N'Kaoua, Bernard; Arvind Pala, Prashant; Taillade, Mathieu; Guitton, Pascal

    2016-02-01

    We investigated the navigation-related age effects on learning, proactive interference semantic clustering, recognition hits, and false recognitions in a naturalistic situation using a virtual apartment-based task. We also examined the neuropsychological correlates (executive functioning [EF] and episodic memory) of navigation-related age effects on memory. Younger and older adults either actively navigated or passively followed the computer-guided tour of an apartment. The results indicated that active navigation increased recognition hits compared with passive navigation, but it did not influence other memory measures (learning, proactive interference, and semantic clustering) to a similar extent in either age group. Furthermore, active navigation helped to reduce false recognitions in younger adults but increased those made by older adults. This differential effect of active navigation for younger and older adults was accounted for by EF score. Like for the subject-performed task effects, the effects from the navigation manipulation were well accounted for by item-specific/relational processing distinction, and they were also consistent with a source monitoring deficit in older adults. © 2015 The British Psychological Society.

  11. VU-flow: a visualization tool for analyzing navigation in virtual environments.

    PubMed

    Chittaro, Luca; Ranon, Roberto; Ieronutti, Lucio

    2006-01-01

    This paper presents a tool for the visual analysis of navigation patterns of moving entities, such as users, virtual characters, or vehicles in 3D Virtual Environments (VEs). The tool, called VU-Flow, provides a set of interactive visualizations that highlight interesting navigation behaviors of single or groups of moving entities that were the VE together or separately. The visualizations help to improve the design of VEs and to study the navigation behavior of users, e.g., during controlled experiments. Besides VEs, the proposed techniques could also be applied to visualize real-world data recorded by positioning systems, allowing one to employ VU-Flow in domains such as urban planning, transportation, and emergency response.

  12. Wearable Virtual White Cane Network for navigating people with visual impairment.

    PubMed

    Gao, Yabiao; Chandrawanshi, Rahul; Nau, Amy C; Tse, Zion Tsz Ho

    2015-09-01

    Navigating the world with visual impairments presents inconveniences and safety concerns. Although a traditional white cane is the most commonly used mobility aid due to its low cost and acceptable functionality, electronic traveling aids can provide more functionality as well as additional benefits. The Wearable Virtual Cane Network is an electronic traveling aid that utilizes ultrasound sonar technology to scan the surrounding environment for spatial information. The Wearable Virtual Cane Network is composed of four sensing nodes: one on each of the user's wrists, one on the waist, and one on the ankle. The Wearable Virtual Cane Network employs vibration and sound to communicate object proximity to the user. While conventional navigation devices are typically hand-held and bulky, the hands-free design of our prototype allows the user to perform other tasks while using the Wearable Virtual Cane Network. When the Wearable Virtual Cane Network prototype was tested for distance resolution and range detection limits at various displacements and compared with a traditional white cane, all participants performed significantly above the control bar (p < 4.3 × 10(-5), standard t-test) in distance estimation. Each sensor unit can detect an object with a surface area as small as 1 cm(2) (1 cm × 1 cm) located 70 cm away. Our results showed that the walking speed for an obstacle course was increased by 23% on average when subjects used the Wearable Virtual Cane Network rather than the white cane. The obstacle course experiment also shows that the use of the white cane in combination with the Wearable Virtual Cane Network can significantly improve navigation over using either the white cane or the Wearable Virtual Cane Network alone (p < 0.05, paired t-test).

  13. Evaluation of a conceptual framework for predicting navigation performance in virtual reality

    PubMed Central

    Thrash, Tyler; Hölscher, Christoph; Schinazi, Victor R.

    2017-01-01

    Previous research in spatial cognition has often relied on simple spatial tasks in static environments in order to draw inferences regarding navigation performance. These tasks are typically divided into categories (e.g., egocentric or allocentric) that reflect different two-systems theories. Unfortunately, this two-systems approach has been insufficient for reliably predicting navigation performance in virtual reality (VR). In the present experiment, participants were asked to learn and navigate towards goal locations in a virtual city and then perform eight simple spatial tasks in a separate environment. These eight tasks were organised along four orthogonal dimensions (static/dynamic, perceived/remembered, egocentric/allocentric, and distance/direction). We employed confirmatory and exploratory analyses in order to assess the relationship between navigation performance and performances on these simple tasks. We provide evidence that a dynamic task (i.e., intercepting a moving object) is capable of predicting navigation performance in a familiar virtual environment better than several categories of static tasks. These results have important implications for studies on navigation in VR that tend to over-emphasise the role of spatial memory. Given that our dynamic tasks required efficient interaction with the human interface device (HID), they were more closely aligned with the perceptuomotor processes associated with locomotion than wayfinding. In the future, researchers should consider training participants on HIDs using a dynamic task prior to conducting a navigation experiment. Performances on dynamic tasks should also be assessed in order to avoid confounding skill with an HID and spatial knowledge acquisition. PMID:28915266

  14. A two-class brain computer interface to freely navigate through virtual worlds.

    PubMed

    Ron-Angevin, Ricardo; Díaz-Estrella, Antonio; Velasco-Alvarez, Francisco

    2009-06-01

    A brain computer interface that enables navigation through a virtual environment (VE) using four different navigation commands (turn right, turn left, move forward and move back) is presented. A graphical interface allows subjects to select a specific command. In this interface, the different navigation commands are surrounding a circle. A bar in the center of the circle is continuously rotating. The subject controls, by only two mental tasks, the bar extension to reach the chosen command. In this study, after an initial training based on three sessions, 8 out of 15 naive subjects were able to navigate through the VE discriminating between imagination of right-hand movements and relaxed state. All subjects (except one) improved their performance in each run and a mean error rate of 23.75% was obtained.

  15. Automatic path searching for interactive navigation support within virtual medical 3-dimensional objects.

    PubMed

    Noser, Hansrudi; Stern, Christian; Stucki, Peter

    2004-08-01

    This article proposes the use of a disembodied autonomous actor for navigation support within complex virtual medical objects reconstructed from Computed Tomography or Magnetic Resonance Imaging. Such objects are often maze-like, and users risk getting lost within them during Virtual Reality sessions. Therefore, users need paths for guided fly-throughs when performing non-invasive diagnostic tasks. We present a synthetic vision-based actor capable of finding collision-free paths from a given position to a goal point in environments containing loops and impasses. When navigating, the actor voxelizes the virtual environment and searches for collision-free paths in voxel space by using a back tracking search algorithm. Automata and rules control its search behaviour. The resulting paths can be used in dedicated virtual endoscopy applications. Our path search method has been tested within a variety of tubular virtual anatomical structures in 3D such as aortas, colons, or blood vessels of the brain. The actor finds paths within reasonable time limits, even when considering complex anatomical surface models. The method may be used as a valuable tool for assisting virtual endoscopic diagnostic and screening activities in the near future.

  16. Engagement of neural circuits underlying 2D spatial navigation in a rodent virtual reality system

    PubMed Central

    Aronov, Dmitriy; Tank, David W.

    2015-01-01

    SUMMARY Virtual reality (VR) enables precise control of an animal’s environment and otherwise impossible experimental manipulations. Neural activity in navigating rodents has been studied on virtual linear tracks. However, the spatial navigation system’s engagement in complete two-dimensional environments has not been shown. We describe a VR setup for rats, including control software and a large-scale electrophysiology system, which supports 2D navigation by allowing animals to rotate and walk in any direction. The entorhinal-hippocampal circuit, including place cells, grid cells, head direction cells and border cells, showed 2D activity patterns in VR similar to those in the real world. Hippocampal neurons exhibited various remapping responses to changes in the appearance or the shape of the virtual environment, including a novel form in which a VR-induced cue conflict caused remapping to lock to geometry rather than salient cues. These results suggest a general-purpose tool for novel types of experimental manipulations in navigating rats. PMID:25374363

  17. Large displays enhance optical flow cues and narrow the gender gap in 3-D virtual navigation.

    PubMed

    Tan, Desney S; Czerwinski, Mary P; Robertson, George G

    2006-01-01

    Existing reports suggest that males significantly outperform females in navigating 3-D virtual environments. Although researchers have recognized that this may be attributable to males and females possessing different spatial abilities, most work has attempted to reduce the gender gap by providing more training for females. In this paper, we explore using large displays to narrow the gender gap within these tasks. While evaluating various interaction techniques, we found that large displays affording wider fields of view seemed to improve virtual navigation performance in general and, additionally, to narrow the gender gap that existed on standard desktop displays. We conducted two experiments (32 and 22 participants) exploring the individual contributions of display and geometric fields of view to the observed effects as well as isolating factors explaining performance increases seen on the large displays. We show that wider fields of view on large displays not only increase performance of all users on average but also benefit females to such a degree as to allow them to perform as well as males do. We further demonstrate that these benefits can be attributed to better optical flow cues offered by the large displays. These findings provide a significant contribution, including recommendations for the improved presentation of 3-D environments, backed by empirical data demonstrating performance benefits during navigation tasks. APPLICATION. Results can be used to design systems that narrow the gender gap in domains such as teleoperation and virtual environments for entertainment, virtual training, or information visualization.

  18. Navigation of a robot-integrated fluorescence laparoscope in preoperative SPECT/CT and intraoperative freehand SPECT imaging data: a phantom study

    NASA Astrophysics Data System (ADS)

    van Oosterom, Matthias Nathanaël; Engelen, Myrthe Adriana; van den Berg, Nynke Sjoerdtje; KleinJan, Gijs Hendrik; van der Poel, Henk Gerrit; Wendler, Thomas; van de Velde, Cornelis Jan Hadde; Navab, Nassir; van Leeuwen, Fijs Willem Bernhard

    2016-08-01

    Robot-assisted laparoscopic surgery is becoming an established technique for prostatectomy and is increasingly being explored for other types of cancer. Linking intraoperative imaging techniques, such as fluorescence guidance, with the three-dimensional insights provided by preoperative imaging remains a challenge. Navigation technologies may provide a solution, especially when directly linked to both the robotic setup and the fluorescence laparoscope. We evaluated the feasibility of such a setup. Preoperative single-photon emission computed tomography/X-ray computed tomography (SPECT/CT) or intraoperative freehand SPECT (fhSPECT) scans were used to navigate an optically tracked robot-integrated fluorescence laparoscope via an augmented reality overlay in the laparoscopic video feed. The navigation accuracy was evaluated in soft tissue phantoms, followed by studies in a human-like torso phantom. Navigation accuracies found for SPECT/CT-based navigation were 2.25 mm (coronal) and 2.08 mm (sagittal). For fhSPECT-based navigation, these were 1.92 mm (coronal) and 2.83 mm (sagittal). All errors remained below the <1-cm detection limit for fluorescence imaging, allowing refinement of the navigation process using fluorescence findings. The phantom experiments performed suggest that SPECT-based navigation of the robot-integrated fluorescence laparoscope is feasible and may aid fluorescence-guided surgery procedures.

  19. Two-photon calcium imaging during fictive navigation in virtual environments.

    PubMed

    Ahrens, Misha B; Huang, Kuo Hua; Narayan, Sujatha; Mensh, Brett D; Engert, Florian

    2013-01-01

    A full understanding of nervous system function requires recording from large populations of neurons during naturalistic behaviors. Here we enable paralyzed larval zebrafish to fictively navigate two-dimensional virtual environments while we record optically from many neurons with two-photon imaging. Electrical recordings from motor nerves in the tail are decoded into intended forward swims and turns, which are used to update a virtual environment displayed underneath the fish. Several behavioral features-such as turning responses to whole-field motion and dark avoidance-are well-replicated in this virtual setting. We readily observed neuronal populations in the hindbrain with laterally selective responses that correlated with right or left optomotor behavior. We also observed neurons in the habenula, pallium, and midbrain with response properties specific to environmental features. Beyond single-cell correlations, the classification of network activity in such virtual settings promises to reveal principles of brainwide neural dynamics during behavior.

  20. Two-photon Calcium Imaging in Mice Navigating a Virtual Reality Environment

    PubMed Central

    Buchmann, Peter; Argast, Paul; Hübener, Mark; Bonhoeffer, Tobias; Keller, Georg B.

    2014-01-01

    In recent years, two-photon imaging has become an invaluable tool in neuroscience, as it allows for chronic measurement of the activity of genetically identified cells during behavior1-6. Here we describe methods to perform two-photon imaging in mouse cortex while the animal navigates a virtual reality environment. We focus on the aspects of the experimental procedures that are key to imaging in a behaving animal in a brightly lit virtual environment. The key problems that arise in this experimental setup that we here address are: minimizing brain motion related artifacts, minimizing light leak from the virtual reality projection system, and minimizing laser induced tissue damage. We also provide sample software to control the virtual reality environment and to do pupil tracking. With these procedures and resources it should be possible to convert a conventional two-photon microscope for use in behaving mice. PMID:24637961

  1. A novel virtual reality environment for preoperative planning and simulation of image guided intracardiac surgeries with robotic manipulators.

    PubMed

    Yeniaras, Erol; Deng, Zhigang; Syed, Mushabbar A; Davies, Mark G; Tsekos, Nikolaos V

    2011-01-01

    The evolution of image-guided and robot-assisted procedures can be beneficial to intracardiac interventions. This paper proposes a novel approach and a virtual reality system for preoperative planning and intraoperative guidance of cardiac procedures, and for investigating the kinematics and control of a virtual robotic manipulator, based on MRI CINE images. The system incorporates dedicated software modules for processing MR images, generating dynamic trajectories in the continuously changing environment of a beating heart, controlling a specific generic virtual manipulator along those trajectories, and a virtual reality interface that fuses all those information. The proposed system is applied for the simulation of accessing the aortic valve annulus via a small incision on the apex by maneuvering a robotic manipulator through an access corridor that safely transverses the left ventricle (LV) of the beating heart.

  2. Visual based navigation for power line inspection by using virtual environments

    NASA Astrophysics Data System (ADS)

    Cerón, Alexander; Mondragón, Iván. F.; Prieto, Flavio

    2015-01-01

    Power line inspection is an important task for the maintenance of electrical infrastructure. UAVs (Unmanned aerial vehicle) can be very useful in the inspection process because the high costs of obtaining images of power lines from different perspectives and the logistic problems of manned flights. The use of the power line as a reference for navigation can be difficult because the different backgrounds, we consider the use of the tower as a reference in order to improve the orientation of the UAV respect to the electrical grid. In this work we generate a process for navigation based in tower detection. The navigation is performed by using the information extracted from a frontal camera in a visual control scheme and validated in virtual environments.

  3. Turning bias in virtual spatial navigation: age-related differences and neuroanatomical correlates.

    PubMed

    Yuan, Peng; Daugherty, Ana M; Raz, Naftali

    2014-02-01

    Rodents frequently exhibit rotational bias associated with asymmetry in lesions and neurotransmitters in the striatum. However, in humans, turning preference is inconsistent across studies, and its neural correlates are unclear. We examined turning bias in 140 right-handed healthy adults (18-77 years old), who navigated a virtual Morris Water Maze. On magnetic resonance images, we measured volumes of brain regions relevant to spatial navigation. We classified turns that occurred during virtual navigation as veering (less than 10°), true turns (between 10° and 90°) and course reversals (over 90°). The results showed that performance (time of platform search and distance traveled) was negatively related to age. The distance traveled was positively associated with volume of the orbito-frontal cortex but not with the volumes of the cerebellum, the hippocampus or the primary visual cortex. Examination of turning behavior showed that all participants veered to the right. In turns and reversals, although on average there was no consistent direction preference, we observed significant individual biases. Virtual turning preference correlated with volumetric asymmetry in the striatum, cerebellum, and hippocampus but not in the prefrontal cortex. Participants preferred to turn toward the hemisphere with larger putamen, cerebellum and (in younger adults only) hippocampus. Advanced age was associated with greater rightward turning preference. Men showed greater leftward preference whereas women exhibited stronger rightward bias. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Simulating Navigation with Virtual 3d Geovisualizations - a Focus on Memory Related Factors

    NASA Astrophysics Data System (ADS)

    Lokka, I.; Çöltekin, A.

    2016-06-01

    The use of virtual environments (VE) for navigation-related studies, such as spatial cognition and path retrieval has been widely adopted in cognitive psychology and related fields. What motivates the use of VEs for such studies is that, as opposed to real-world, we can control for the confounding variables in simulated VEs. When simulating a geographic environment as a virtual world with the intention to train navigational memory in humans, an effective and efficient visual design is important to facilitate the amount of recall. However, it is not yet clear what amount of information should be included in such visual designs intended to facilitate remembering: there can be too little or too much of it. Besides the amount of information or level of detail, the types of visual features (`elements' in a visual scene) that should be included in the representations to create memorable scenes and paths must be defined. We analyzed the literature in cognitive psychology, geovisualization and information visualization, and identified the key factors for studying and evaluating geovisualization designs for their function to support and strengthen human navigational memory. The key factors we identified are: i) the individual abilities and age of the users, ii) the level of realism (LOR) included in the representations and iii) the context in which the navigation is performed, thus specific tasks within a case scenario. Here we present a concise literature review and our conceptual development for follow-up experiments.

  5. Design and Application of a Novel Virtual Reality Navigational Technology (VRNChair).

    PubMed

    Byagowi, Ahmad; Mohaddes, Danyal; Moussavi, Zahra

    2014-01-01

    This paper presents a novel virtual reality navigation (VRN) input device, called the VRNChair, offering an intuitive and natural way to interact with virtual reality (VR) environments. Traditionally, VR navigation tests are performed using stationary input devices such as keyboards or joysticks. However, in case of immersive VR environment experiments, such as our recent VRN assessment, the user may feel kinetosis (motion sickness) as a result of the disagreement between vestibular response and the optical flow. In addition, experience in using a joystick or any of the existing computer input devices may cause a bias in the accuracy of participant performance in VR environment experiments. Therefore, we have designed a VR navigational environment that is operated using a wheelchair (VRNChair). The VRNChair translates the movement of a manual wheelchair to feed any VR environment. We evaluated the VRNChair by testing on 34 young individuals in two groups performing the same navigational task with either the VRNChair or a joystick; also one older individual (55 years) performed the same experiment with both a joystick and the VRNChair. The results indicate that the VRNChair does not change the accuracy of the performance; thus removing the plausible bias of having experience using a joystick. More importantly, it significantly reduces the effect of kinetosis. While we developed VRNChair for our spatial cognition study, its application can be in many other studies involving neuroscience, neurorehabilitation, physiotherapy, and/or simply the gaming industry.

  6. Solar System Modeler: A Distributed, Virtual Environment for Space Visualization and GPS Navigation

    NASA Astrophysics Data System (ADS)

    Williams, Gary E.

    1996-12-01

    The Solar System Modeler (SM) extends the Space Modeler developed in 1994. It provides a virtual environment enabling an explorer to dynamically investigate near Earth satellites, deep space probes, planets, moons, and other celestial phenomena. The explorer navigates the virtual environment via mouse selected options from menu panels while wearing a tracked, head mounted display (HMD). Alternatively, a monitor may replace the HMD and keyboard controls replace head tracking. The SM's functionality is extended by the ability to broadcast simulated GPS satellite transmissions in compliance with Distributed Interactive Simulation (DIS) protocol standards. The transmissions include information found in true GPS broadcasts that is required for a receiver to determine its location. The Virtual GPS Receiver (VGPSR) receives the GPS transmissions from the SM and computes the receiver's position with a realistic error based on numerous variables simulating those encountered in the real GPS system. The VGPSR is designed as a plug-in module for simulations requiring virtual navigation. The receiver's client application provides the VGPSR with the simulation time and the true position of the receiver. In return, the application receives a GPS indicated position.

  7. Printed Three-dimensional Anatomic Templates for Virtual Preoperative Planning Before Reconstruction of Old Pelvic Injuries: Initial Results

    PubMed Central

    Wu, Xin-Bao; Wang, Jun-Qiang; Zhao, Chun-Peng; Sun, Xu; Shi, Yin; Zhang, Zi-An; Li, Yu-Neng; Wang, Man-Yi

    2015-01-01

    Background: Old pelvis fractures are among the most challenging fractures to treat because of their complex anatomy, difficult-to-access surgical sites, and the relatively low incidence of such cases. Proper evaluation and surgical planning are necessary to achieve the pelvic ring symmetry and stable fixation of the fracture. The goal of this study was to assess the use of three-dimensional (3D) printing techniques for surgical management of old pelvic fractures. Methods: First, 16 dried human cadaveric pelvises were used to confirm the anatomical accuracy of the 3D models printed based on radiographic data. Next, nine clinical cases between January 2009 and April 2013 were used to evaluate the surgical reconstruction based on the 3D printed models. The pelvic injuries were all type C, and the average time from injury to reconstruction was 11 weeks (range: 8–17 weeks). The workflow consisted of: (1) Printing patient-specific bone models based on preoperative computed tomography (CT) scans, (2) virtual fracture reduction using the printed 3D anatomic template, (3) virtual fracture fixation using Kirschner wires, and (4) preoperatively measuring the osteotomy and implant position relative to landmarks using the virtually defined deformation. These models aided communication between surgical team members during the procedure. This technique was validated by comparing the preoperative planning to the intraoperative procedure. Results: The accuracy of the 3D printed models was within specification. Production of a model from standard CT DICOM data took 7 hours (range: 6–9 hours). Preoperative planning using the 3D printed models was feasible in all cases. Good correlation was found between the preoperative planning and postoperative follow-up X-ray in all nine cases. The patients were followed for 3–29 months (median: 5 months). The fracture healing time was 9–17 weeks (mean: 10 weeks). No delayed incision healing, wound infection, or nonunions occurred. The

  8. Blind persons navigate in virtual reality (VR); hearing and feeling communicates "reality".

    PubMed

    Max, M L; Gonzalez, J R

    1997-01-01

    Can Virtual Reality (VR) developments in audio navigation for blind persons support therapies for all? Working with Crystal River Engineering we are developing navigable Virtual Reality worlds for blind users, using spatialized audio [1], [2]. All persons, however, use specialized channels, such as: visual, aural, and kinetic learning senses. Predominantly visual VR worlds and health informatics models from World Wide Webs, may be downloaded, tailored, augmented, and delivered to each of these learning senses using VR. We are also testing a proof of concept system with Boston Dynamics which downloads 3-dimensional, satellite-derived map models from the World Wide Web, and makes them navigable by "feeling" the terrain using haptic (tactual or force feedback to your hand) robotic interfaces. Ultimately, these multi-sensory VR access methods: sight, localization by audio, and "feeling" of data sets could open up the World Wide Web to individuals with sight impairments. This could also, however, benefit government, businesses, universities, and (elementary) education. It could contribute more powerful communications, education, and medical simulation applications on the World Wide Web. This work is part of government technology transfer to telemedicine, (elementary) education, disabilities access to the Web, and new Internet access and productivity efforts under Vice President Gore's National Performance Review.

  9. The effect of contextual auditory stimuli on virtual spatial navigation in patients with focal hemispheric lesions.

    PubMed

    Cogné, Mélanie; Knebel, Jean-François; Klinger, Evelyne; Bindschaedler, Claire; Rapin, Pierre-André; Joseph, Pierre-Alain; Clarke, Stephanie

    2016-01-06

    Topographical disorientation is a frequent deficit among patients suffering from brain injury. Spatial navigation can be explored in this population using virtual reality environments, even in the presence of motor or sensory disorders. Furthermore, the positive or negative impact of specific stimuli can be investigated. We studied how auditory stimuli influence the performance of brain-injured patients in a navigational task, using the Virtual Action Planning-Supermarket (VAP-S) with the addition of contextual ("sonar effect" and "name of product") and non-contextual ("periodic randomised noises") auditory stimuli. The study included 22 patients with a first unilateral hemispheric brain lesion and 17 healthy age-matched control subjects. After a software familiarisation, all subjects were tested without auditory stimuli, with a sonar effect or periodic random sounds in a random order, and with the stimulus "name of product". Contextual auditory stimuli improved patient performance more than control group performance. Contextual stimuli benefited most patients with severe executive dysfunction or with severe unilateral neglect. These results indicate that contextual auditory stimuli are useful in the assessment of navigational abilities in brain-damaged patients and that they should be used in rehabilitation paradigms.

  10. Verbalizing, visualizing, and navigating: The effect of strategies on encoding a large-scale virtual environment.

    PubMed

    Kraemer, David J M; Schinazi, Victor R; Cawkwell, Philip B; Tekriwal, Anand; Epstein, Russell A; Thompson-Schill, Sharon L

    2017-04-01

    Using novel virtual cities, we investigated the influence of verbal and visual strategies on the encoding of navigation-relevant information in a large-scale virtual environment. In 2 experiments, participants watched videos of routes through 4 virtual cities and were subsequently tested on their memory for observed landmarks and their ability to make judgments regarding the relative directions of the different landmarks along the route. In the first experiment, self-report questionnaires measuring visual and verbal cognitive styles were administered to examine correlations between cognitive styles, landmark recognition, and judgments of relative direction. Results demonstrate a tradeoff in which the verbal cognitive style is more beneficial for recognizing individual landmarks than for judging relative directions between them, whereas the visual cognitive style is more beneficial for judging relative directions than for landmark recognition. In a second experiment, we manipulated the use of verbal and visual strategies by varying task instructions given to separate groups of participants. Results confirm that a verbal strategy benefits landmark memory, whereas a visual strategy benefits judgments of relative direction. The manipulation of strategy by altering task instructions appears to trump individual differences in cognitive style. Taken together, we find that processing different details during route encoding, whether due to individual proclivities (Experiment 1) or task instructions (Experiment 2), results in benefits for different components of navigation-relevant information. These findings also highlight the value of considering multiple sources of individual differences as part of spatial cognition investigations. (PsycINFO Database Record

  11. Functional imaging of hippocampal place cells at cellular resolution during virtual navigation.

    PubMed

    Dombeck, Daniel A; Harvey, Christopher D; Tian, Lin; Looger, Loren L; Tank, David W

    2010-11-01

    Spatial navigation is often used as a behavioral task in studies of the neuronal circuits that underlie cognition, learning and memory in rodents. The combination of in vivo microscopy with genetically encoded indicators has provided an important new tool for studying neuronal circuits, but has been technically difficult to apply during navigation. Here we describe methods for imaging the activity of neurons in the CA1 region of the hippocampus with subcellular resolution in behaving mice. Neurons that expressed the genetically encoded calcium indicator GCaMP3 were imaged through a chronic hippocampal window. Head-restrained mice performed spatial behaviors in a setup combining a virtual reality system and a custom-built two-photon microscope. We optically identified populations of place cells and determined the correlation between the location of their place fields in the virtual environment and their anatomical location in the local circuit. The combination of virtual reality and high-resolution functional imaging should allow a new generation of studies to investigate neuronal circuit dynamics during behavior.

  12. Navigation performance in virtual environments varies with fractal dimension of landscape.

    PubMed

    Juliani, Arthur W; Bies, Alexander J; Boydston, Cooper R; Taylor, Richard P; Sereno, Margaret E

    2016-09-01

    Fractal geometry has been used to describe natural and built environments, but has yet to be studied in navigational research. In order to establish a relationship between the fractal dimension (D) of a natural environment and humans' ability to navigate such spaces, we conducted two experiments using virtual environments that simulate the fractal properties of nature. In Experiment 1, participants completed a goal-driven search task either with or without a map in landscapes that varied in D. In Experiment 2, participants completed a map-reading and location-judgment task in separate sets of fractal landscapes. In both experiments, task performance was highest at the low-to-mid range of D, which was previously reported as most preferred and discriminable in studies of fractal aesthetics and discrimination, respectively, supporting a theory of visual fluency. The applicability of these findings to architecture, urban planning, and the general design of constructed spaces is discussed.

  13. Role of virtual surgery in pre-operative planning: Assessing the individual components of functional nasal airway surgery

    PubMed Central

    Rhee, John S.; Cannon, Daniel E.; Frank, Dennis O.; Kimbell, Julia S.

    2013-01-01

    Introduction There are often multiple anatomic factors that contribute to nasal obstruction, creating difficulty in deciding which components to address for a successful outcome. The purpose of this pilot study is to demonstrate the effect of individual components of functional nasal airway surgery in a patient with multifactorial obstruction and discuss the potential benefit of computational fluid dynamics (CFD)-aided virtual surgery. Methods A 53 year old female underwent septoplasty, turbinate reduction, and nasal valve repair. Pre- and post-operative digital nasal models were created from CT images and nasal resistance was calculated using CFD techniques. The digital models were then manipulated to isolate the effects of the components of the surgery, creating a nasal valve repair alone model and a septoplasty/turbinate reduction alone model. Results Bilateral nasal resistance on the post-operative model was approximately 25% less than pre-operative values. Similarly, CFD analysis showed reductions in nasal resistance of the virtual models: 19% reduction with intranasal surgery alone and 6% reduction with nasal valve repair alone. Conclusions Most of the reduction in nasal resistance was accomplished with performance of septoplasty and inferior turbinate reduction. The contribution from nasal valve repair was less in comparison but not insignificant. This pilot study implies that CFD-aided virtual surgery may be useful as part of pre-operative planning in patients with multifactorial anatomic nasal airway obstruction. PMID:22508896

  14. [Image fusion, virtual reality, robotics and navigation. Effects on surgical practice].

    PubMed

    Maresceaux, J; Soler, L; Ceulemans, R; Garcia, A; Henri, M; Dutson, E

    2002-05-01

    In the new minimally invasive surgical era, virtual reality, robotics, and image merging have become topics on their own, offering the potential to revolutionize current surgical treatment and assessment. Improved patient care in the digital age seems to be the primary impetus for continued efforts in the field of telesurgery. The progress in endoscopic surgery with regard to telesurgery is manifested by digitization of the pre-, intra-, and postoperative interaction with the patients' surgical disease via computer system integration: so-called Computer Assisted Surgery (CAS). The preoperative assessment can be improved by 3D organ reconstruction, as in virtual colonoscopy or cholangiography, and by planning and practicing surgery using virtual or simulated organs. When integrating all of the data recorded during this preoperative stage, an enhanced reality can be made possible to improve intra-operative patient interactions. CAS allows for increased three-dimensional accuracy, improved precision and the reproducibility of procedures. The ability to store the actions of the surgeon as digitized information also allows for universal, rapid distribution: i.e., the surgeon's activity can be transmitted to the other side of the operating room or to a remote site via high-speed communications links, as was recently demonstrated by our own team during the Lindbergh operation. Furthermore, the surgeon will be able to share his expertise and skill through teleconsultation and telemanipulation, bringing the patient closer to the expert surgical team through electronic means and opening the way to advanced and continuous surgical learning. Finally, for postoperative interaction, virtual reality and simulation can provide us with 4 dimensional images, time being the fourth dimension. This should allow physicians to have a better idea of the disease process in evolution, and treatment modifications based on this view can be anticipated. We are presently determining the

  15. The effect of extended sensory range via the EyeCane sensory substitution device on the characteristics of visionless virtual navigation.

    PubMed

    Maidenbaum, Shachar; Levy-Tzedek, Shelly; Chebat, Daniel Robert; Namer-Furstenberg, Rinat; Amedi, Amir

    2014-01-01

    Mobility training programs for helping the blind navigate through unknown places with a White-Cane significantly improve their mobility. However, what is the effect of new assistive technologies, offering more information to the blind user, on the underlying premises of these programs such as navigation patterns? We developed the virtual-EyeCane, a minimalistic sensory substitution device translating single-point-distance into auditory cues identical to the EyeCane's in the real world. We compared performance in virtual environments when using the virtual-EyeCane, a virtual-White-Cane, no device and visual navigation. We show that the characteristics of virtual-EyeCane navigation differ from navigation with a virtual-White-Cane or no device, and that virtual-EyeCane users complete more levels successfully, taking shorter paths and with less collisions than these groups, and we demonstrate the relative similarity of virtual-EyeCane and visual navigation patterns. This suggests that additional distance information indeed changes navigation patterns from virtual-White-Cane use, and brings them closer to visual navigation.

  16. An investigation of the validity of the virtual spatial navigation assessment

    PubMed Central

    Ventura, Matthew; Shute, Valerie; Wright, Tim; Zhao, Weinan

    2013-01-01

    This correlational study investigated a new measure of environmental spatial ability (i.e., large scale spatial ability) called the virtual spatial navigation assessment (VSNA). In the VSNA, participants must find a set of gems in a virtual 3D environment using a first person avatar on a computer. The VSNA runs in a web browser and automatically collects the time taken to find each gem. The time taken to collect gems in the VSNA was significantly correlated to three other spatial ability measures, math standardized test scores, and choice to be in a STEM (science, technology, engineering, or math) career. These findings support the validity of the VSNA as a measure of environmental spatial ability. Finally, self-report video game experience was also significantly correlated to the VSNA suggesting that video game may improve environmental spatial ability. Recommendations are made for how the VSNA can be used to help guide individuals toward STEM career paths and identify weaknesses that might be addressed with large scale spatial navigation training. PMID:24379790

  17. A Wearable Virtual Usher for Vision-Based Cognitive Indoor Navigation.

    PubMed

    Li, Liyuan; Xu, Qianli; Chandrasekhar, Vijay; Lim, Joo-Hwee; Tan, Cheston; Mukawa, Michal Akira

    2017-04-01

    Inspired by progresses in cognitive science, artificial intelligence, computer vision, and mobile computing technologies, we propose and implement a wearable virtual usher for cognitive indoor navigation based on egocentric visual perception. A novel computational framework of cognitive wayfinding in an indoor environment is proposed, which contains a context model, a route model, and a process model. A hierarchical structure is proposed to represent the cognitive context knowledge of indoor scenes. Given a start position and a destination, a Bayesian network model is proposed to represent the navigation route derived from the context model. A novel dynamic Bayesian network (DBN) model is proposed to accommodate the dynamic process of navigation based on real-time first-person-view visual input, which involves multiple asynchronous temporal dependencies. To adapt to large variations in travel time through trip segments, we propose an online adaptation algorithm for the DBN model, leading to a self-adaptive DBN. A prototype system is built and tested for technical performance and user experience. The quantitative evaluation shows that our method achieves over 13% improvement in accuracy as compared to baseline approaches based on hidden Markov model. In the user study, our system guides the participants to their destinations, emulating a human usher in multiple aspects.

  18. Does an Oblique/Slanted Perspective during Virtual Navigation Engage Both Egocentric and Allocentric Brain Strategies?

    PubMed Central

    Barra, Julien; Laou, Laetitia; Poline, Jean-Baptiste; Lebihan, Denis; Berthoz, Alain

    2012-01-01

    Perspective (route or survey) during the encoding of spatial information can influence recall and navigation performance. In our experiment we investigated a third type of perspective, which is a slanted view. This slanted perspective is a compromise between route and survey perspectives, offering both information about landmarks as in route perspective and geometric information as in survey perspective. We hypothesized that the use of slanted perspective would allow the brain to use either egocentric or allocentric strategies during storage and recall. Twenty-six subjects were scanned (3-Tesla fMRI) during the encoding of a path (40-s navigation movie within a virtual city). They were given the task of encoding a segment of travel in the virtual city and of subsequent shortcut-finding for each perspective: route, slanted and survey. The analysis of the behavioral data revealed that perspective influenced response accuracy, with significantly more correct responses for slanted and survey perspectives than for route perspective. Comparisons of brain activation with route, slanted, and survey perspectives suggested that slanted and survey perspectives share common brain activity in the left lingual and fusiform gyri and lead to very similar behavioral performance. Slanted perspective was also associated with similar activation to route perspective during encoding in the right middle occipital gyrus. Furthermore, slanted perspective induced intermediate patterns of activation (in between route and survey) in some brain areas, such as the right lingual and fusiform gyri. Our results suggest that the slanted perspective may be considered as a hybrid perspective. This result offers the first empirical support for the choice to present the slanted perspective in many navigational aids. PMID:23209583

  19. Design of a Virtual Reality Navigational (VRN) experiment for assessment of egocentric spatial cognition.

    PubMed

    Byagowi, Ahmad; Moussavi, Zahra

    2012-01-01

    Virtual reality (VR) experiments are commonly used to assess human brain functions. We orient ourselves in an environment by computing precise self-to-object spatial relations (egocentric orientation) as well as object-to-object spatial relations (allocentric orientation). Egocentric orientation involves cues that depend on the position of the observer (i.e. left-right, front-behind), whereas allocentric orientation is maintained through the use of environmental features such as landmarks. As such, allocentric orientation involves short-term memory, whereas egocentric orientation does not. This paper presents a Virtual Reality Navigational (VRN) experiment specifically designed to assess egocentric spatial cognition. The design aimed to minimize the effect of spatial cues or landmarks for human navigation in a naturalistic VR environment. The VRN experiment designed for this study, called the Virtual House, is a symmetric three story cubic building, with 3 windows on each side on every floor, and one entrance on each side of the building. In each trial, a window is marked by a pseudo-random sequence as the objective. The marked window is shown to the participant from an outdoor view. The task is to reach the objective window using the shortest path through the building. The experiment entails 2 sets of 8 trials to cover all possibilities. The participants' performance error is measured by the difference between their traversed distance trajectory and the shortest natural distance (calculated using the VR engine), normalized by the shortest distance, in each trial. Fifty-two cognitively healthy adults participated in the study. The results show no learning effect during the 16 trails, implying that the experiment does not rely on short-term memory. Furthermore, the subjects' normalized performance error showed an almost linear increase with age, implying that egocentric spatial cognition ability declines with age.

  20. Incidental memory and navigation in panoramic virtual reality for electronic commerce.

    PubMed

    Howes, A; Miles, G E; Payne, S J; Mitchell, C D; Davies, A J

    2001-01-01

    Recently much effort has been dedicated to designing and implementing World Wide Web sites for virtual shopping and e-commerce. Despite this effort, relatively little empirical work has been done to determine the effectiveness with which different site designs sell products. We report three experiments in which participants were asked to search for products in various experimental e-commerce sites. Across the experiments participants were asked to search in either QTVR (QuickTime Virtual Reality), hypertext, or pictorially rich hypertext environments; they were then tested for their ability to recall the products seen and to recognize product locations. The experiments demonstrated that when using QTVR (Experiments 1, 2, and 3) or pictorial environments (Experiment 2), participants retained more information about products that were incidental to their goals. In two of the experiments it was shown that participants navigated more efficiently when using a QTVR environment. The costs and benefits of using 3D virtual environments for on-line shops are discussed. Actual or potential applications of this research include support for the development of e-commerce design guidelines.

  1. Evaluating the Usability of Pinchigator, a system for Navigating Virtual Worlds using Pinch Gloves

    NASA Technical Reports Server (NTRS)

    Hamilton, George S.; Brookman, Stephen; Dumas, Joseph D. II; Tilghman, Neal

    2003-01-01

    Appropriate design of two dimensional user interfaces (2D U/I) utilizing the well known WIMP (Window, Icon, Menu, Pointing device) environment for computer software is well studied and guidance can be found in several standards. Three-dimensional U/I design is not nearly so mature as 2D U/I, and standards bodies have not reached consensus on what makes a usable interface. This is especially true when the tools for interacting with the virtual environment may include stereo viewing, real time trackers and pinch gloves instead of just a mouse & keyboard. Over the last several years the authors have created a 3D U/I system dubbed Pinchigator for navigating virtual worlds based on the dVise dV/Mockup visualization software, Fakespace Pinch Gloves and Pohlemus trackers. The current work is to test the usability of the system on several virtual worlds, suggest improvements to increase Pinchigator s usability, and then to generalize about what was learned and how those lessons might be applied to improve other 3D U/I systems.

  2. Evaluating the Usability of Pinchigator, a system for Navigating Virtual Worlds using Pinch Gloves

    NASA Technical Reports Server (NTRS)

    Hamilton, George S.; Brookman, Stephen; Dumas, Joseph D. II; Tilghman, Neal

    2003-01-01

    Appropriate design of two dimensional user interfaces (2D U/I) utilizing the well known WIMP (Window, Icon, Menu, Pointing device) environment for computer software is well studied and guidance can be found in several standards. Three-dimensional U/I design is not nearly so mature as 2D U/I, and standards bodies have not reached consensus on what makes a usable interface. This is especially true when the tools for interacting with the virtual environment may include stereo viewing, real time trackers and pinch gloves instead of just a mouse & keyboard. Over the last several years the authors have created a 3D U/I system dubbed Pinchigator for navigating virtual worlds based on the dVise dV/Mockup visualization software, Fakespace Pinch Gloves and Pohlemus trackers. The current work is to test the usability of the system on several virtual worlds, suggest improvements to increase Pinchigator s usability, and then to generalize about what was learned and how those lessons might be applied to improve other 3D U/I systems.

  3. Prospective Evaluation of Precision Multimodal Gallbladder Surgery Navigation: Virtual Reality, Near-infrared Fluorescence, and X-ray-based Intraoperative Cholangiography.

    PubMed

    Diana, Michele; Soler, Luc; Agnus, Vincent; D'Urso, Antonio; Vix, Michel; Dallemagne, Bernard; Faucher, Vanina; Roy, Catherine; Mutter, Didier; Marescaux, Jacques; Pessaux, Patrick

    2017-07-24

    We aimed to prospectively evaluate NIR-C, VR-AR, and x-ray intraoperative cholangiography (IOC) during robotic cholecystectomy. Near-infrared cholangiography (NIR-C) provides real-time, radiation-free biliary anatomy enhancement. Three-dimensional virtual reality (VR) biliary anatomy models can be obtained via software manipulation of magnetic resonance cholangiopancreatography, enabling preoperative VR exploration, and intraoperative augmented reality (AR) navigation. Fifty-eight patients were scheduled for cholecystectomy for gallbladder lithiasis. VR surgical planning was performed on virtual models. At anesthesia induction, indocyanine green was injected intravenously. AR navigation was obtained by overlaying the virtual model onto real-time images. Before and after Calot triangle dissection, NIR-C was obtained by turning the camera to NIR mode. Finally, an IOC was performed. The 3 modality performances were evaluated and image quality was assessed with a Likert-scale questionnaire. The three-dimensional VR planning enabled the identification of 12 anatomical variants in 8 patients, of which only 7 were correctly reported by the radiologists (P = 0.037). A dangerous variant identified at VR induced a "fundus first" approach. The cystic-common bile duct junction was visualized before Calot triangle dissection at VR in 100% of cases, at NIR-C in 98.15%, and in 96.15% at IOC.Mean time to obtain relevant images was shorter with NIR-C versus AR (P = 0.008) and versus IOC (P = 0.00000003). Image quality scores were lower with NIR-C versus AR (P = 0.018) and versus IOC (P < 0.0001). This high-tech protocol illustrates the multimodal imaging of biliary anatomy towards precision cholecystectomy. Those visualization techniques could complement to reduce the likelihood of biliary injuries (NCT01881399).

  4. Real-time 3-dimensional virtual reality navigation system with open MRI for breast-conserving surgery.

    PubMed

    Tomikawa, Morimasa; Hong, Jaesung; Shiotani, Satoko; Tokunaga, Eriko; Konishi, Kozo; Ieiri, Satoshi; Tanoue, Kazuo; Akahoshi, Tomohiko; Maehara, Yoshihiko; Hashizume, Makoto

    2010-06-01

    The aim of this study was to report on the early experiences using a real-time 3-dimensional (3D) virtual reality navigation system with open MRI for breast-conserving surgery. We developed a real-time 3D virtual reality navigation system with open MRI, and evaluated the mismatch between the navigation system and real distance using a 3D phantom. Two patients with nonpalpable MRI-detected breast tumors underwent breast-conserving surgery under the guidance of the navigation system. An initial MRI for the breast tumor using skin-affixed markers was performed immediately before excision. A percutaneous intramammary dye marker was applied to delineate an excision line, and the computer software "3D Slicer" generated a real-time 3D virtual reality model of the tumor and the puncture needle in the breast. Excision of the tumor was performed in the usual manner along the excision line indicated with the dye. The resected specimens were carefully examined histopathologically. The mean mismatch between the navigation system and real distance was 2.01 +/- 0.32 mm when evaluated with the 3D phantom. Under guidance by the navigation system, a percutaneous intramammary dye marker was applied without any difficulty. Fiducial registration errors were 3.00 mm for patient no. 1, and 4.07 mm for patient no. 2. Histopathological examinations of the resected specimens of the 2 patients showed noninvasive ductal carcinoma in situ. The surgical margins were free of carcinoma cells. Real-time 3D virtual reality navigation system with open MRI is feasible for safe and accurate excision of nonpalpable MRI-detected breast tumors. Long-term outcomes of this technique should be evaluated further. Copyright (c) 2010 American College of Surgeons. All rights reserved.

  5. Biplane reconstruction and visualization of virtual endoscopic and fluoroscopic views for interventional device navigation

    NASA Astrophysics Data System (ADS)

    Wagner, Martin G.; Strother, Charles M.; Schafer, Sebastian; Mistretta, Charles A.

    2016-03-01

    Biplane fluoroscopic imaging is an important tool for minimally invasive procedures for the treatment of cerebrovascular diseases. However, finding a good working angle for the C-arms of the angiography system as well as navigating based on the 2D projection images can be a difficult task. The purpose of this work is to propose a novel 4D reconstruction algorithm for interventional devices from biplane fluoroscopy images and to propose new techniques for a better visualization of the results. The proposed reconstruction methods binarizes the fluoroscopic images using a dedicated noise reduction algorithm for curvilinear structures and a global thresholding approach. A topology preserving thinning algorithm is then applied and a path search algorithm minimizing the curvature of the device is used to extract the 2D device centerlines. Finally, the 3D device path is reconstructed using epipolar geometry. The point correspondences are determined by a monotonic mapping function that minimizes the reconstruction error. The three dimensional reconstruction of the device path allows the rendering of virtual fluoroscopy images from arbitrary angles as well as 3D visualizations like virtual endoscopic views or glass pipe renderings, where the vessel wall is rendered with a semi-transparent material. This work also proposes a combination of different visualization techniques in order to increase the usability and spatial orientation for the user. A combination of synchronized endoscopic and glass pipe views is proposed, where the virtual endoscopic camera position is determined based on the device tip location as well as the previous camera position using a Kalman filter in order to create a smooth path. Additionally, vessel centerlines are displayed and the path to the target is highlighted. Finally, the virtual endoscopic camera position is also visualized in the glass pipe view to further improve the spatial orientation. The proposed techniques could considerably improve

  6. 3D Printed Models and Navigation for Skull Base Surgery: Case Report and Virtual Validation.

    PubMed

    Ritacco, Lucas E; Di Lella, Federico; Mancino, Axel; Gonzalez Bernaldo de Quiros, Fernan; Boccio, Carlos; Milano, Federico E

    2015-01-01

    In recent years, computer-assisted surgery tools have become more versatile. Having access to a 3D printed model expands the possibility for surgeons to practice with the particular anatomy of a patient before surgery and improve their skills. Optical navigation is capable of guiding a surgeon according to a previously defined plan. These methods improve accuracy and safety at the moment of executing the operation. We intend to carry on a validation process for computed-assisted tools. The aim of this project is to propose a comparative validation method to enable physicians to evaluate differences between a virtual planned approach trajectory and a real executed course. Summarily, this project is focused on decoding data in order to obtain numerical values so as to establish the quality of surgical procedures.

  7. Gaze-informed, task-situated representation of space in primate hippocampus during virtual navigation.

    PubMed

    Wirth, Sylvia; Baraduc, Pierre; Planté, Aurélie; Pinède, Serge; Duhamel, Jean-René

    2017-02-01

    To elucidate how gaze informs the construction of mental space during wayfinding in visual species like primates, we jointly examined navigation behavior, visual exploration, and hippocampal activity as macaque monkeys searched a virtual reality maze for a reward. Cells sensitive to place also responded to one or more variables like head direction, point of gaze, or task context. Many cells fired at the sight (and in anticipation) of a single landmark in a viewpoint- or task-dependent manner, simultaneously encoding the animal's logical situation within a set of actions leading to the goal. Overall, hippocampal activity was best fit by a fine-grained state space comprising current position, view, and action contexts. Our findings indicate that counterparts of rodent place cells in primates embody multidimensional, task-situated knowledge pertaining to the target of gaze, therein supporting self-awareness in the construction of space.

  8. Gaze-informed, task-situated representation of space in primate hippocampus during virtual navigation

    PubMed Central

    Wirth, Sylvia; Baraduc, Pierre; Planté, Aurélie; Pinède, Serge; Duhamel, Jean-René

    2017-01-01

    To elucidate how gaze informs the construction of mental space during wayfinding in visual species like primates, we jointly examined navigation behavior, visual exploration, and hippocampal activity as macaque monkeys searched a virtual reality maze for a reward. Cells sensitive to place also responded to one or more variables like head direction, point of gaze, or task context. Many cells fired at the sight (and in anticipation) of a single landmark in a viewpoint- or task-dependent manner, simultaneously encoding the animal’s logical situation within a set of actions leading to the goal. Overall, hippocampal activity was best fit by a fine-grained state space comprising current position, view, and action contexts. Our findings indicate that counterparts of rodent place cells in primates embody multidimensional, task-situated knowledge pertaining to the target of gaze, therein supporting self-awareness in the construction of space. PMID:28241007

  9. When mental fatigue maybe characterized by Event Related Potential (P300) during virtual wheelchair navigation.

    PubMed

    Lamti, Hachem A; Gorce, Philippe; Ben Khelifa, Mohamed Moncef; Alimi, Adel M

    2016-12-01

    The goal of this study is to investigate the influence of mental fatigue on the event related potential P300 features (maximum pick, minimum amplitude, latency and period) during virtual wheelchair navigation. For this purpose, an experimental environment was set up based on customizable environmental parameters (luminosity, number of obstacles and obstacles velocities). A correlation study between P300 and fatigue ratings was conducted. Finally, the best correlated features supplied three classification algorithms which are MLP (Multi Layer Perceptron), Linear Discriminate Analysis and Support Vector Machine. The results showed that the maximum feature over visual and temporal regions as well as period feature over frontal, fronto-central and visual regions were correlated with mental fatigue levels. In the other hand, minimum amplitude and latency features didn't show any correlation. Among classification techniques, MLP showed the best performance although the differences between classification techniques are minimal. Those findings can help us in order to design suitable mental fatigue based wheelchair control.

  10. Place and response learning in human virtual navigation: behavioral measures and gender differences.

    PubMed

    Schmitzer-Torbert, Neil

    2007-04-01

    Two experiments examined the use of place and response strategies by humans navigating virtual multiple T mazes. In Experiment 1, probe trials revealed that participants commonly used place and response strategies, and place strategies were more frequent early in training, whereas response strategies were more frequent late in training. Compared with women, men learned the correct path through the maze more quickly and developed a more stable route through the maze. In Experiment 2, participants were trained to locate 2 targets. One target required participants to use either a place or response strategy, whereas the other target could be found using either strategy. Accuracy improved faster for place training compared with response training, and women outperformed men in both groups. Probe trials testing transfer of the imposed strategy to the other target found faster transfer for place training than for response training and that women demonstrated faster transfer than men. Accuracy on probe trials was correlated with poor route stability in the place-trained group and with good route stability in the response-trained group, indicating that navigation strategy use may be related to measures of improvement in performance on normal trials.

  11. Sexual Orientation-Related Differences in Virtual Spatial Navigation and Spatial Search Strategies.

    PubMed

    Rahman, Qazi; Sharp, Jonathan; McVeigh, Meadhbh; Ho, Man-Ling

    2017-04-11

    Spatial abilities are generally hypothesized to differ between men and women, and people with different sexual orientations. According to the cross-sex shift hypothesis, gay men are hypothesized to perform in the direction of heterosexual women and lesbian women in the direction of heterosexual men on cognitive tests. This study investigated sexual orientation differences in spatial navigation and strategy during a virtual Morris water maze task (VMWM). Forty-four heterosexual men, 43 heterosexual women, 39 gay men, and 34 lesbian/bisexual women (aged 18-54 years) navigated a desktop VMWM and completed measures of intelligence, handedness, and childhood gender nonconformity (CGN). We quantified spatial learning (hidden platform trials), probe trial performance, and cued navigation (visible platform trials). Spatial strategies during hidden and probe trials were classified into visual scanning, landmark use, thigmotaxis/circling, and enfilading. In general, heterosexual men scored better than women and gay men on some spatial learning and probe trial measures and used more visual scan strategies. However, some differences disappeared after controlling for age and estimated IQ (e.g., in visual scanning heterosexual men differed from women but not gay men). Heterosexual women did not differ from lesbian/bisexual women. For both sexes, visual scanning predicted probe trial performance. More feminine CGN scores were associated with lower performance among men and greater performance among women on specific spatial learning or probe trial measures. These results provide mixed evidence for the cross-sex shift hypothesis of sexual orientation-related differences in spatial cognition.

  12. Beyond Dizziness: Virtual Navigation, Spatial Anxiety and Hippocampal Volume in Bilateral Vestibulopathy.

    PubMed

    Kremmyda, Olympia; Hüfner, Katharina; Flanagin, Virginia L; Hamilton, Derek A; Linn, Jennifer; Strupp, Michael; Jahn, Klaus; Brandt, Thomas

    2016-01-01

    Bilateral vestibulopathy (BVP) is defined as the impairment or loss of function of either the labyrinths or the eighth nerves. Patients with total BVP due to bilateral vestibular nerve section exhibit difficulties in spatial memory and navigation and show a loss of hippocampal volume. In clinical practice, most patients do not have a complete loss of function but rather an asymmetrical residual functioning of the vestibular system. The purpose of the current study was to investigate navigational ability and hippocampal atrophy in BVP patients with residual vestibular function. Fifteen patients with BVP and a group of age- and gender- matched healthy controls were examined. Self-reported questionnaires on spatial anxiety and wayfinding were used to assess the applied strategy of wayfinding and quality of life. Spatial memory and navigation were tested directly using a virtual Morris Water Maze Task. The hippocampal volume of these two groups was evaluated by voxel-based morphometry. In the patients, the questionnaire showed a higher spatial anxiety and the Morris Water Maze Task a delayed spatial learning performance. MRI revealed a significant decrease in the gray matter mid-hippocampal volume (Left: p = 0.006, Z = 4.58, Right: p < 0.001, Z = 3.63) and posterior parahippocampal volume (Right: p = 0.005, Z = 4.65, Left: p < 0.001, Z = 3.87) compared to those of healthy controls. In addition, a decrease in hippocampal formation volume correlated with a more dominant route-finding strategy. Our current findings demonstrate that even partial bilateral vestibular loss leads to anatomical and functional changes in the hippocampal formation and objective and subjective behavioral deficits.

  13. Beyond Dizziness: Virtual Navigation, Spatial Anxiety and Hippocampal Volume in Bilateral Vestibulopathy

    PubMed Central

    Kremmyda, Olympia; Hüfner, Katharina; Flanagin, Virginia L.; Hamilton, Derek A.; Linn, Jennifer; Strupp, Michael; Jahn, Klaus; Brandt, Thomas

    2016-01-01

    Bilateral vestibulopathy (BVP) is defined as the impairment or loss of function of either the labyrinths or the eighth nerves. Patients with total BVP due to bilateral vestibular nerve section exhibit difficulties in spatial memory and navigation and show a loss of hippocampal volume. In clinical practice, most patients do not have a complete loss of function but rather an asymmetrical residual functioning of the vestibular system. The purpose of the current study was to investigate navigational ability and hippocampal atrophy in BVP patients with residual vestibular function. Fifteen patients with BVP and a group of age- and gender- matched healthy controls were examined. Self-reported questionnaires on spatial anxiety and wayfinding were used to assess the applied strategy of wayfinding and quality of life. Spatial memory and navigation were tested directly using a virtual Morris Water Maze Task. The hippocampal volume of these two groups was evaluated by voxel-based morphometry. In the patients, the questionnaire showed a higher spatial anxiety and the Morris Water Maze Task a delayed spatial learning performance. MRI revealed a significant decrease in the gray matter mid-hippocampal volume (Left: p = 0.006, Z = 4.58, Right: p < 0.001, Z = 3.63) and posterior parahippocampal volume (Right: p = 0.005, Z = 4.65, Left: p < 0.001, Z = 3.87) compared to those of healthy controls. In addition, a decrease in hippocampal formation volume correlated with a more dominant route-finding strategy. Our current findings demonstrate that even partial bilateral vestibular loss leads to anatomical and functional changes in the hippocampal formation and objective and subjective behavioral deficits. PMID:27065838

  14. Virtual navigation strategies from childhood to senescence: evidence for changes across the life span

    PubMed Central

    Bohbot, Veronique D.; McKenzie, Sam; Konishi, Kyoko; Fouquet, Celine; Kurdi, Vanessa; Schachar, Russel; Boivin, Michel; Robaey, Philippe

    2012-01-01

    This study sought to investigate navigational strategies across the life span, by testing 8-years old children to 80-years old healthy older adults on the 4 on 8 virtual maze (4/8VM). The 4/8VM was previously developed to assess spontaneous navigational strategies, i.e., hippocampal-dependent spatial strategies (navigation by memorizing relationships between landmarks) versus caudate nucleus-dependent response strategies (memorizing a series of left and right turns from a given starting position). With the 4/8VM, we previously demonstrated greater fMRI activity and gray matter in the hippocampus of spatial learners relative to response learners. A sample of 599 healthy participants was tested in the current study. Results showed that 84.4% of children, 46.3% of young adults, and 39.3% of older adults spontaneously used spatial strategies (p < 0.0001). Our results suggest that while children predominantly use spatial strategies, the proportion of participants using spatial strategies decreases across the life span, in favor of response strategies. Factors promoting response strategies include repetition, reward and stress. Since response strategies can result from successful repetition of a behavioral pattern, we propose that the increase in response strategies is a biological adaptive mechanism that allows for the automatization of behavior such as walking in order to free up hippocampal-dependent resources. However, the down-side of this shift from spatial to response strategies occurs if people stop building novel relationships, which occurs with repetition and routine, and thereby stop stimulating their hippocampus. Reduced fMRI activity and gray matter in the hippocampus were shown to correlate with cognitive deficits in normal aging. Therefore, these results have important implications regarding factors involved in healthy and successful aging. PMID:23162463

  15. Aneurysm Surgery with Preoperative Three-Dimensional Planning in a Virtual Reality Environment: Technique and Outcome Analysis.

    PubMed

    Kockro, Ralf A; Killeen, Tim; Ayyad, Ali; Glaser, Martin; Stadie, Axel; Reisch, Robert; Giese, Alf; Schwandt, Eike

    2016-12-01

    Aneurysm surgery demands precise spatial understanding of the vascular anatomy and its surroundings. We report on a decade of experience planning clipping procedures preoperatively in a virtual reality (VR) workstation and present outcomes with respect to mortality, morbidity, and aneurysm occlusion rate. Between 2006 and 2015, the clipping of 115 intracranial aneurysms in 105 patients was preoperatively planned with the Dextroscope, a stereoscopic, patient-specific VR environment. The outcome data for all cases, planned and performed in 3 institutions, were analyzed based on clinical charts and radiologic reports. Eighty-five incidental, unruptured aneurysms in 77 patients were electively planned and treated surgically. Mortality was 0% and morbidity (modified Rankin Scale score >2) was 2.6%. The rate of complete aneurysm obliteration on postoperative imaging was 91.8%. In addition, 30 aneurysms were treated in 28 patients with previous subarachnoid hemorrhage. Mortality in these cases was 3.6%, morbidity (modified Rankin Scale score >2) 7.1%, and the rate of complete aneurysm clipping was 90%. Meticulous three-dimensional surgical planning in a VR environment enhances the surgeon's spatial understanding of the individual vascular anatomy and allows clip preselection and positioning as well as anticipation of potential difficulties and complications. VR planning was associated, in this multi-institutional series, with excellent clinical outcomes and rates of complete aneurysm closure equivalent to benchmark cohorts. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  16. Hippocampal Volume Reduction in Humans Predicts Impaired Allocentric Spatial Memory in Virtual-Reality Navigation

    PubMed Central

    Dzieciol, Anna M.; Gadian, David G.; Jentschke, Sebastian; Doeller, Christian F.; Burgess, Neil; Mishkin, Mortimer

    2015-01-01

    The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with “moderate” hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. SIGNIFICANCE STATEMENT In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on

  17. Hippocampal Volume Reduction in Humans Predicts Impaired Allocentric Spatial Memory in Virtual-Reality Navigation.

    PubMed

    Guderian, Sebastian; Dzieciol, Anna M; Gadian, David G; Jentschke, Sebastian; Doeller, Christian F; Burgess, Neil; Mishkin, Mortimer; Vargha-Khadem, Faraneh

    2015-10-21

    The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with "moderate" hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on hippocampal integrity in humans is

  18. Virtual bronchoscopic navigation combined with endobronchial ultrasound to diagnose small peripheral pulmonary lesions: a randomised trial.

    PubMed

    Ishida, Takashi; Asano, Fumihiro; Yamazaki, Koichi; Shinagawa, Naofumi; Oizumi, Satoshi; Moriya, Hiroshi; Munakata, Mitsuru; Nishimura, Masaharu

    2011-12-01

    Bronchoscopy using endobronchial ultrasound (EBUS) can help to diagnose small peripheral pulmonary lesions. However, although biopsy sites can be confirmed, a bronchoscope cannot be guided in EBUS. Virtual bronchoscopic navigation (VBN) can guide a bronchoscope with virtual images, but its value has not been confirmed. This prospective multicentre study examines the value of VBN-assisted EBUS for diagnosing small peripheral pulmonary lesions. 199 patients with small peripheral pulmonary lesions (diameter ≤30 mm) were randomly assigned to VBN-assisted (VBNA) or non-VBN-assisted (NVBNA) groups. A bronchoscope was introduced into the target bronchus of the VBNA group using the VBN system. Sites of specimen sampling were verified using EBUS with a guide sheath under fluoroscopy. The diagnostic yield was higher for the VBNA than for the NVBNA group (80.4% vs 67.0%; p = 0.032). The duration of the examination and time elapsed until the start of sample collection were reduced in the VBNA compared with the NVBNA group (median (range), 24.0 (8.7-47.0) vs 26.2 (11.6-58.6) min, p = 0.016) and 8.1 (2.8-39.2) vs 9.8 (2.3-42.3) min, p = 0.045, respectively). The only adverse event was mild pneumothorax in a patient from the NVBNA group. The diagnostic yield for small peripheral pulmonary lesions is increased when VBN is combined with EBUS. Clinical trial number UMIN000000569.

  19. A 2D virtual reality system for visual goal-driven navigation in zebrafish larvae

    PubMed Central

    Jouary, Adrien; Haudrechy, Mathieu; Candelier, Raphaël; Sumbre, German

    2016-01-01

    Animals continuously rely on sensory feedback to adjust motor commands. In order to study the role of visual feedback in goal-driven navigation, we developed a 2D visual virtual reality system for zebrafish larvae. The visual feedback can be set to be similar to what the animal experiences in natural conditions. Alternatively, modification of the visual feedback can be used to study how the brain adapts to perturbations. For this purpose, we first generated a library of free-swimming behaviors from which we learned the relationship between the trajectory of the larva and the shape of its tail. Then, we used this technique to infer the intended displacements of head-fixed larvae, and updated the visual environment accordingly. Under these conditions, larvae were capable of aligning and swimming in the direction of a whole-field moving stimulus and produced the fine changes in orientation and position required to capture virtual prey. We demonstrate the sensitivity of larvae to visual feedback by updating the visual world in real-time or only at the end of the discrete swimming episodes. This visual feedback perturbation caused impaired performance of prey-capture behavior, suggesting that larvae rely on continuous visual feedback during swimming. PMID:27659496

  20. Redirecting walking and driving for natural navigation in immersive virtual environments.

    PubMed

    Bruder, Gerd; Interrante, Victoria; Phillips, Lane; Steinicke, Frank

    2012-04-01

    Walking is the most natural form of locomotion for humans, and real walking interfaces have demonstrated their benefits for several navigation tasks. With recently proposed redirection techniques it becomes possible to overcome space limitations as imposed by tracking sensors or laboratory setups, and, theoretically, it is now possible to walk through arbitrarily large virtual environments. However, walking as sole locomotion technique has drawbacks, in particular, for long distances, such that even in the real world we tend to support walking with passive or active transportation for longer-distance travel. In this article we show that concepts from the field of redirected walking can be applied to movements with transportation devices. We conducted psychophysical experiments to determine perceptual detection thresholds for redirected driving, and set these in relation to results from redirected walking. We show that redirected walking-and-driving approaches can easily be realized in immersive virtual reality laboratories, e. g., with electric wheelchairs, and show that such systems can combine advantages of real walking in confined spaces with benefits of using vehicle-based self-motion for longer-distance travel.

  1. A 2D virtual reality system for visual goal-driven navigation in zebrafish larvae.

    PubMed

    Jouary, Adrien; Haudrechy, Mathieu; Candelier, Raphaël; Sumbre, German

    2016-09-23

    Animals continuously rely on sensory feedback to adjust motor commands. In order to study the role of visual feedback in goal-driven navigation, we developed a 2D visual virtual reality system for zebrafish larvae. The visual feedback can be set to be similar to what the animal experiences in natural conditions. Alternatively, modification of the visual feedback can be used to study how the brain adapts to perturbations. For this purpose, we first generated a library of free-swimming behaviors from which we learned the relationship between the trajectory of the larva and the shape of its tail. Then, we used this technique to infer the intended displacements of head-fixed larvae, and updated the visual environment accordingly. Under these conditions, larvae were capable of aligning and swimming in the direction of a whole-field moving stimulus and produced the fine changes in orientation and position required to capture virtual prey. We demonstrate the sensitivity of larvae to visual feedback by updating the visual world in real-time or only at the end of the discrete swimming episodes. This visual feedback perturbation caused impaired performance of prey-capture behavior, suggesting that larvae rely on continuous visual feedback during swimming.

  2. Navigated bronchoscopy: a technical review.

    PubMed

    Reynisson, Pall J; Leira, Håkon O; Hernes, Toril N; Hofstad, Erlend F; Scali, Marta; Sorger, Hanne; Amundsen, Tore; Lindseth, Frank; Langø, Thomas

    2014-07-01

    Navigated bronchoscopy uses virtual 3-dimensional lung model visualizations created from preoperative computed tomography images often in synchronization with the video bronchoscope to guide a tool to peripheral lesions. Navigated bronchoscopy has developed fast since the introduction of virtual bronchoscopy with integrated electromagnetic sensors in the late 1990s. The purposes of the review are to give an overview and update of the technological components of navigated bronchoscopy, an assessment of its clinical usefulness, and a brief assessment of the commercial platforms for navigated bronchoscopy. We performed a literature search with relevant keywords to navigation and bronchoscopy and iterated on the reference lists of relevant papers, with emphasis on the last 5 years. The paper presents an overview of the components necessary for performing navigated bronchoscopy, assessment of the diagnostic accuracy of different approaches, and an analysis of the commercial systems. We were able to identify 4 commercial platforms and 9 research and development groups with considerable activity in the field. Finally, on the basis of our findings and our own experience, we provide a discussion on navigated bronchoscopy with focus on the next steps of development. The literature review showed that the peripheral diagnostic accuracy has improved using navigated bronchoscopy compared with traditional bronchoscopy. We believe that there is room for improvement in the diagnostic success rate by further refinement of methods, approaches, and tools used in navigated bronchoscopy.

  3. Personified and multistate camera motions for first-person navigation in desktop virtual reality.

    PubMed

    Terziman, Léo; Marchal, Maud; Multon, Franck; Arnaldi, Bruno; Lécuyer, Anatole

    2013-04-01

    In this paper we introduce novel 'Camera Motions' (CMs) to improve the sensations related to locomotion in virtual environments (VE). Traditional Camera Motions are artificial oscillating motions applied to the subjective viewpoint when walking in the VE, and they are meant to evoke and reproduce the visual flow generated during a human walk. Our novel camera motions are: (1) multistate, (2) personified, and (3) they can take into account the topography of the virtual terrain. Being multistate, our CMs can account for different states of locomotion in VE namely: walking, but also running and sprinting. Being personified, our CMs can be adapted to avatar's physiology such as to its size, weight or training status. They can then take into account avatar's fatigue and recuperation for updating visual CMs accordingly. Last, our approach is adapted to the topography of the VE. Running over a strong positive slope would rapidly decrease the advance speed of the avatar, increase its energy loss, and eventually change the locomotion mode, influencing the visual feedback of the camera motions. Our new approach relies on a locomotion simulator partially inspired by human physiology and implemented for a real-time use in Desktop VR. We have conducted a series of experiments to evaluate the perception of our new CMs by naive participants. Results notably show that participants could discriminate and perceive transitions between the different locomotion modes, by relying exclusively on our CMs. They could also perceive some properties of the avatar being used and, overall, very well appreciated the new CMs techniques. Taken together, our results suggest that our new CMs could be introduced in Desktop VR applications involving first-person navigation, in order to enhance sensations of walking, running, and sprinting, with potentially different avatars and over uneven terrains, such as for: training, virtual visits or video games.

  4. Electromagnetic navigation bronchoscopy guided injection of methylene blue combined with hookwire for preoperative localization of small pulmonary lesions in thoracoscopic surgery

    PubMed Central

    Sun, Jiayuan; Mao, Xiaowei; Xie, Fangfang

    2015-01-01

    Video-assisted thoracoscopic surgery (VATS) has been widely used in the resection of small pulmonary lesions in the clinical practice. The accurate preoperative localization of small pulmonary lesions is significant to guide the operation. We report a thoracoscopic pulmonary wedge resection with electromagnetic navigation bronchoscopy (ENB) guided injection of methylene blue combined with hookwire to localize the small pulmonary lesion in a 50-year-old woman. We successfully performed VATS followed by the combined localization of these two methods. This localization method has a higher accuracy and fewer complications, which can effectively guide the surgical resection. PMID:26793384

  5. Development of an audio-based virtual gaming environment to assist with navigation skills in the blind.

    PubMed

    Connors, Erin C; Yazzolino, Lindsay A; Sánchez, Jaime; Merabet, Lotfi B

    2013-03-27

    Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.

  6. C-Arm Cone-Beam CT Virtual Navigation-Guided Percutaneous Mediastinal Mass Biopsy: Diagnostic Accuracy and Complications.

    PubMed

    Kim, Hyungjin; Park, Chang Min; Lee, Sang Min; Goo, Jin Mo

    2015-12-01

    To assess the usefulness of C-arm cone-beam computed tomography (CBCT) virtual navigation-guided percutaneous mediastinal mass biopsy in terms of diagnostic accuracy and complication rates. Seventy-eight CBCT virtual navigation-guided percutaneous mediastinal mass biopsies were performed in 75 patients (M:F, 38:37; mean age, 48.55 ± 18.76 years). The procedural details, diagnostic sensitivity, specificity, accuracy and complication rate were investigated. Mean lesion size was 6.80 ± 3.08 cm, skin-to-target distance was 3.67 ± 1.80 cm, core needle biopsy rate was 96.2 % (75/78), needle indwelling time was 9.29 ± 4.34 min, total procedure time was 13.26 ± 5.29 min, number of biopsy specimens obtained was 3.13 ± 1.02, number of CBCTs performed was 3.03 ± 0.68, rate of lesion border discrimination from abutting mediastinal structures on CBCT was 26.9 % (21/78), technical success rate was 100 % (78/78), estimated effective dose was 5.33 ± 4.99 mSv, and the dose area product was 12,723.68 ± 10,665.74 mGy⋅cm(2). Among the 78 biopsies, 69 were malignant, 7 were benign and 2 were indeterminate. Diagnostic sensitivity, specificity and accuracy for the diagnosis of malignancies were 97.1 % (67/69), 100 % (7/7) and 97.4 % (74/76), respectively, with a complication rate of 3.85 % (3/78), all of which were small pneumothoraces. CBCT virtual navigation-guided biopsy is a highly accurate and safe procedure for the evaluation of mediastinal lesions. • CBCT virtual navigation-guided percutaneous mediastinal biopsy is highly accurate • CBCT virtual navigation-guided percutaneous mediastinal biopsy is a safe procedure • Mediastinal vascular injury can be avoided under CBCT virtual navigation guidance.

  7. Lost in Virtual Space: Studies in Human and Ideal Spatial Navigation

    ERIC Educational Resources Information Center

    Stankiewicz, Brian J.; Legge, Gordon E.; Mansfield, J. Stephen; Schlicht, Erik J.

    2006-01-01

    The authors describe 3 human spatial navigation experiments that investigate how limitations of perception, memory, uncertainty, and decision strategy affect human spatial navigation performance. To better understand the effect of these variables on human navigation performance, the authors developed an ideal-navigator model for indoor navigation…

  8. Lost in Virtual Space: Studies in Human and Ideal Spatial Navigation

    ERIC Educational Resources Information Center

    Stankiewicz, Brian J.; Legge, Gordon E.; Mansfield, J. Stephen; Schlicht, Erik J.

    2006-01-01

    The authors describe 3 human spatial navigation experiments that investigate how limitations of perception, memory, uncertainty, and decision strategy affect human spatial navigation performance. To better understand the effect of these variables on human navigation performance, the authors developed an ideal-navigator model for indoor navigation…

  9. A combination of three-dimensional printing and computer-assisted virtual surgical procedure for preoperative planning of acetabular fracture reduction.

    PubMed

    Zeng, Canjun; Xing, Weirong; Wu, Zhanglin; Huang, Huajun; Huang, Wenhua

    2016-10-01

    Treatment of acetabular fractures remains one of the most challenging tasks that orthopaedic surgeons face. An accurate assessment of the injuries and preoperative planning are essential for an excellent reduction. The purpose of this study was to evaluate the feasibility, accuracy and effectiveness of performing 3D printing technology and computer-assisted virtual surgical procedures for preoperative planning in acetabular fractures. We hypothesised that more accurate preoperative planning using 3D printing models will reduce the operation time and significantly improve the outcome of acetabular fracture repair. Ten patients with acetabular fractures were recruited prospectively and examined by CT scanning. A 3-D model of each acetabular fracture was reconstructed with MIMICS14.0 software from the DICOM file of the CT data. Bone fragments were moved and rotated to simulate fracture reduction and restore the pelvic integrity with virtual fixation. The computer-assisted 3D image of the reduced acetabula was printed for surgery simulation and plate pre-bending. The postoperative CT scan was performed to compare the consistency of the preoperative planning with the surgical implants by 3D-superimposition in MIMICS14.0, and evaluated by Matta's method. Computer-based pre-operations were precisely mimicked and consistent with the actual operations in all cases. The pre-bent fixation plates had an anatomical shape specifically fit to the individual pelvis without further bending or adjustment at the time of surgery and fracture reductions were significantly improved. Seven out of 10 patients had a displacement of fracture reduction of less than 1mm; 3 cases had a displacement of fracture reduction between 1 and 2mm. The 3D printing technology combined with virtual surgery for acetabular fractures is feasible, accurate, and effective leading to improved patient-specific preoperative planning and outcome of real surgery. The results provide useful technical tips in

  10. Does Virtual Touch IQ elastography help to improve the preoperative diagnosis of parotid tumors: A prospective trial.

    PubMed

    Zengel, Pamela; Notter, Florian; Reichel, Christoph A; Clevert, Dirk A

    2017-09-04

    It is difficult to assess tumors of the parotid gland preoperatively. However, it is essential for the surgeon to know which kind of tumor is present. Ultrasound is the method of choice, but there is still no reliable differential diagnostic tool for determining whether a tumor is malignant or benign. The aim of our study was to examine the value of Virtual Touch imaging quantification (VTIQ) elastograpy in distinguishing between malignant and benign tumors as well as in identifying the most common benign tumor types. The parenchyma of 100 parotid glands and 12 lymph nodes of healthy volunteers and 50 tumors of the parotid gland were analyzed via ultrasound, color Doppler ultrasound, and VTIQ, and the results were then compared with histopathology. In comparison with benign tumors, in malignant tumors the tumor border was diffuse, the perfusion higher, and the VTIQ quality much lower. Share wave velocity of the user-defined region of interest was more frequently higher than 6.8 m/s in malignant tumors in comparison to benign tumors. VTIQ in combination with ultrasound examination provides additional information for distinguishing between benign and malignant tumors and shows promise for integration into preexisting ultrasound protocols.

  11. Preoperative evaluation of neurovascular relationships for microvascular decompression in the cerebellopontine angle in a virtual reality environment.

    PubMed

    Du, Zhuo-Ying; Gao, Xiang; Zhang, Xiao-Luo; Wang, Zhi-Qiu; Tang, Wei-Jun

    2010-09-01

    In this paper the authors' goal was to evaluate the feasibility and efficacy of a virtual reality (VR) system in preoperative planning for microvascular decompression (MVD) procedures treating idiopathic trigeminal neuralgia and hemifacial spasm. The system's role in surgical simulation and training was also assessed. Between May 2008 and April 2009, the authors used the Dextroscope system to visualize the neurovascular complex and simulate MVD in the cerebellopontine angle in a VR environment in 16 patients (6 patients had trigeminal neuralgia and 10 had hemifacial spasm). Reconstructions were carried out 2-3 days before MVD. Images were printed in a red-blue stereoscopic format for teaching and discussion and were brought into the operating room to be compared with real-time intraoperative findings. The VR environment was a powerful aid for spatial understanding of the neurovascular relationship in MVD for operating surgeons and trainees. Through an initial series of comparison/confirmation experiences, the senior neurosurgeon became accustomed to the system. He could predict intraoperative problems and simulate surgical maneuvering, which increased his confidence in performing the procedure. The Dextroscope system is an easy and rapid method to create a stereoscopic neurovascular model for MVD that is highly concordant with intraoperative findings. It effectively shortens the learning curve and adds to the surgeon's confidence.

  12. Effects of head-slaved navigation and the use of teleports on spatial orientation in virtual environments.

    PubMed

    Bakker, Niels H; Passenier, Peter O; Werkhoven, Peter J

    2003-01-01

    The type of navigation interface in a virtual environment (VE)--head slaved or indirect--determines whether or not proprioceptive feedback stimuli are present during movement. In addition, teleports can be used, which do not provide continuous movement but, rather, discontinuously displace the viewpoint over large distances. A two-part experiment was performed. The first part investigated whether head-slaved navigation provides an advantage for spatial learning in a VE. The second part investigated the role of anticipation when using teleports. The results showed that head-slaved navigation has an advantage over indirect navigation for the acquisition of spatial knowledge in a VE. Anticipating the destination of the teleport prevented disorientation after the displacement to a great extent but not completely. The time that was needed for anticipation increased if the teleport involved a rotation of the viewing direction. This research shows the potential added value of using a head-slaved navigation interface--for example, when using VE for training purposes--and provides practical guidelines for the use of teleports in VE applications.

  13. A virtual water maze revisited: Two-year changes in navigation performance and their neural correlates in healthy adults.

    PubMed

    Daugherty, Ana M; Raz, Naftali

    2017-02-01

    Age-related declines in spatial navigation are associated with deficits in procedural and episodic memory and deterioration of their neural substrates. For the lack of longitudinal evidence, the pace and magnitude of these declines and their neural mediators remain unclear. Here we examined virtual navigation in healthy adults (N=213, age 18-77 years) tested twice, two years apart, with complementary indices of navigation performance (path length and complexity) measured over six learning trials at each occasion. Slopes of skill acquisition curves and longitudinal change therein were estimated in structural equation modeling, together with change in regional brain volumes and iron content (R2* relaxometry). Although performance on the first trial did not differ between occasions separated by two years, the slope of path length improvement over trials was shallower and end-of-session performance worse at follow-up. Advanced age, higher pulse pressure, smaller cerebellar and caudate volumes, and greater caudate iron content were associated with longer search paths, i.e. poorer navigation performance. In contrast, path complexity diminished faster over trials at follow-up, albeit less so in older adults. Improvement in path complexity after two years was predicted by lower baseline hippocampal iron content and larger parahippocampal volume. Thus, navigation path length behaves as an index of perceptual-motor skill that is vulnerable to age-related decline, whereas path complexity may reflect cognitive mapping in episodic memory that improves with repeated testing, although not enough to overcome age-related deficits.

  14. Human hippocampal and parahippocampal theta during goal-directed spatial navigation predicts performance on a virtual Morris water maze.

    PubMed

    Cornwell, Brian R; Johnson, Linda L; Holroyd, Tom; Carver, Frederick W; Grillon, Christian

    2008-06-04

    The hippocampus and parahippocampal cortices exhibit theta oscillations during spatial navigation in animals and humans, and in the former are thought to mediate spatial memory formation. Functional specificity of human hippocampal theta, however, is unclear. Neuromagnetic activity was recorded with a whole-head 275-channel magnetoencephalographic (MEG) system as healthy participants navigated to a hidden platform in a virtual reality Morris water maze. MEG data were analyzed for underlying oscillatory sources in the 4-8 Hz band using a spatial filtering technique (i.e., synthetic aperture magnetometry). Source analyses revealed greater theta activity in the left anterior hippocampus and parahippocampal cortices during goal-directed navigation relative to aimless movements in a sensorimotor control condition. Additional analyses showed that left anterior hippocampal activity was predominantly observed during the first one-half of training, pointing to a role for this region in early learning. Moreover, posterior hippocampal theta was highly correlated with navigation performance, with the former accounting for 76% of the variance of the latter. Our findings suggest human spatial learning is dependent on hippocampal and parahippocampal theta oscillations, extending to humans a significant body of research demonstrating such a pivotal role for hippocampal theta in animal navigation.

  15. Age-Related Differences and Cognitive Correlates of Self-Reported and Direct Navigation Performance: The Effect of Real and Virtual Test Conditions Manipulation.

    PubMed

    Taillade, Mathieu; N'Kaoua, Bernard; Sauzéon, Hélène

    2015-01-01

    The present study investigated the effect of aging on direct navigation measures and self-reported ones according to the real-virtual test manipulation. Navigation (wayfinding tasks) and spatial memory (paper-pencil tasks) performances, obtained either in real-world or in virtual-laboratory test conditions, were compared between young (n = 32) and older (n = 32) adults who had self-rated their everyday navigation behavior (SBSOD scale). Real age-related differences were observed in navigation tasks as well as in paper-pencil tasks, which investigated spatial learning relative to the distinction between survey-route knowledge. The manipulation of test conditions (real vs. virtual) did not change these age-related differences, which are mostly explained by age-related decline in both spatial abilities and executive functioning (measured with neuropsychological tests). In contrast, elderly adults did not differ from young adults in their self-reporting relative to everyday navigation, suggesting some underestimation of navigation difficulties by elderly adults. Also, spatial abilities in young participants had a mediating effect on the relations between actual and self-reported navigation performance, but not for older participants. So, it is assumed that the older adults carried out the navigation task with fewer available spatial abilities compared to young adults, resulting in inaccurate self-estimates.

  16. Age-Related Differences and Cognitive Correlates of Self-Reported and Direct Navigation Performance: The Effect of Real and Virtual Test Conditions Manipulation

    PubMed Central

    Taillade, Mathieu; N'Kaoua, Bernard; Sauzéon, Hélène

    2016-01-01

    The present study investigated the effect of aging on direct navigation measures and self-reported ones according to the real-virtual test manipulation. Navigation (wayfinding tasks) and spatial memory (paper-pencil tasks) performances, obtained either in real-world or in virtual-laboratory test conditions, were compared between young (n = 32) and older (n = 32) adults who had self-rated their everyday navigation behavior (SBSOD scale). Real age-related differences were observed in navigation tasks as well as in paper-pencil tasks, which investigated spatial learning relative to the distinction between survey-route knowledge. The manipulation of test conditions (real vs. virtual) did not change these age-related differences, which are mostly explained by age-related decline in both spatial abilities and executive functioning (measured with neuropsychological tests). In contrast, elderly adults did not differ from young adults in their self-reporting relative to everyday navigation, suggesting some underestimation of navigation difficulties by elderly adults. Also, spatial abilities in young participants had a mediating effect on the relations between actual and self-reported navigation performance, but not for older participants. So, it is assumed that the older adults carried out the navigation task with fewer available spatial abilities compared to young adults, resulting in inaccurate self-estimates. PMID:26834666

  17. Evaluation of preoperative high magnetic field motor functional MRI (3 Tesla) in glioma patients by navigated electrocortical stimulation and postoperative outcome.

    PubMed

    Roessler, K; Donat, M; Lanzenberger, R; Novak, K; Geissler, A; Gartus, A; Tahamtan, A R; Milakara, D; Czech, T; Barth, M; Knosp, E; Beisteiner, R

    2005-08-01

    The validity of 3 Tesla motor functional magnetic resonance imaging (fMRI) in patients with gliomas involving the primary motor cortex was investigated by intraoperative navigated motor cortex stimulation (MCS). Twenty two patients (10 males, 12 females, mean age 39 years, range 10-65 years) underwent preoperative fMRI studies, performing motor tasks including hand, foot, and mouth movements. A recently developed high field clinical fMRI technique was used to generate pre-surgical maps of functional high risk areas defining a motor focus. Motor foci were tested for validity by intraoperative motor cortex stimulation (MCS) employing image fusion and neuronavigation. Clinical outcome was assessed using the Modified Rankin Scale. FMRI motor foci were successfully detected in all patients preoperatively. In 17 of 22 patients (77.3%), a successful stimulation of the primary motor cortex was possible. All 17 correlated patients showed 100% agreement on MCS and fMRI motor focus within 10 mm. Technical problems during stimulation occurred in three patients (13.6%), no motor response was elicited in two (9.1%), and MCS induced seizures occurred in three (13.6%). Combined fMRI and MCS mapping results allowed large resections in 20 patients (91%) (gross total in nine (41%), subtotal in 11 (50%)) and biopsy in two patients (9%). Pathology revealed seven low grade and 15 high grade gliomas. Mild to moderate transient neurological deterioration occurred in six patients, and a severe hemiparesis in one. All patients recovered within 3 months (31.8% transient, 0% permanent morbidity). The validation of clinically optimised high magnetic field motor fMRI confirms high reliability as a preoperative and intraoperative adjunct in glioma patients selected for surgery within or adjacent to the motor cortex.

  18. The functional role of human right hippocampal/parahippocampal theta rhythm in environmental encoding during virtual spatial navigation.

    PubMed

    Pu, Yi; Cornwell, Brian R; Cheyne, Douglas; Johnson, Blake W

    2017-03-01

    Low frequency theta band oscillations (4-8 Hz) are thought to provide a timing mechanism for hippocampal place cell firing and to mediate the formation of spatial memory. In rodents, hippocampal theta has been shown to play an important role in encoding a new environment during spatial navigation, but a similar functional role of hippocampal theta in humans has not been firmly established. To investigate this question, we recorded healthy participants' brain responses with a 160-channel whole-head MEG system as they performed two training sets of a virtual Morris water maze task. Environment layouts (except for platform locations) of the two sets were kept constant to measure theta activity during spatial learning in new and familiar environments. In line with previous findings, left hippocampal/parahippocampal theta showed more activation navigating to a hidden platform relative to random swimming. Consistent with our hypothesis, right hippocampal/parahippocampal theta was stronger during the first training set compared to the second one. Notably, theta in this region during the first training set correlated with spatial navigation performance across individuals in both training sets. These results strongly argue for the functional importance of right hippocampal theta in initial encoding of configural properties of an environment during spatial navigation. Our findings provide important evidence that right hippocampal/parahippocampal theta activity is associated with environmental encoding in the human brain. Hum Brain Mapp 38:1347-1361, 2017. © 2016 Wiley Periodicals, Inc.

  19. Alpha- and theta-range cortical synchronization and corticomuscular coherence during joystick manipulation in a virtual navigation task.

    PubMed

    Hori, Satoshi; Matsumoto, Jumpei; Hori, Etsuro; Kuwayama, Naoya; Ono, Taketoshi; Kuroda, Satoshi; Nishijo, Hisao

    2013-10-01

    Previous studies have reported that multiple brain regions are activated during spatial navigation, but it remains unclear how this activation is converted to motor commands for navigation. This study was aimed to investigate synchronization across different brain regions and between cortical areas and muscles during spatial navigation. This synchronization has been suggested to be essential for integrating activity in the multiple brain areas to support higher cognitive functions and for conversion of cortical activity to motor commands. In the present study, the subjects were required to sequentially trace ten checkpoints in a virtual town by manipulating a joystick and to perform this three times while electroencephalograms and electromyograms from the right arm were monitored. Time spent on the task in the third trial was significantly lesser than that in the first trial indicating an improvement in task performance. This repeated learning was associated with an increase in alpha power at the electrodes over the contralateral sensorimotor region and in theta power at the electrodes over the bilateral premotor and frontotemporal regions. Alpha- and theta-range corticocortical coherences between these regions and other brain areas were also increased in the third trial compared to the first trial. Furthermore, alpha- and theta-range corticomuscular coherence was significantly increased in the second and third trials compared to the first trial. These results suggest that alpha- and theta-range synchronous activity across multiple systems is essential for the integrated brain activity required in spatial navigation and for the conversion of this activity to motor commands.

  20. Percutaneous transthoracic localization of pulmonary nodules under C-arm cone-beam CT virtual navigation guidance.

    PubMed

    Kim, Tae Ho; Park, Chang Min; Lee, Sang Min; McAdams, H Page; Kim, Young Tae; Goo, Jin Mo

    2016-01-01

    We aimed to describe our initial experience with percutaneous transthoracic localization (PTL) of pulmonary nodules using a C-arm cone-beam CT (CBCT) virtual navigation guidance system. From February 2013 to March 2014, 79 consecutive patients (mean age, 61±10 years) with 81 solid or ground-glass nodules (mean size, 12.36±7.21 mm; range, 4.8-25 mm) underwent PTLs prior to video-assisted thoracoscopic surgery (VATS) excision under CBCT virtual navigation guidance using lipiodol (mean volume, 0.18±0.04 mL). Their procedural details, radiation dose, and complication rates were described. All 81 target nodules were successfully localized within 10 mm (mean distance, 2.54±3.24 mm) from the lipiodol markings. Mean number of CT acquisitions was 3.2±0.7, total procedure time was 14.6±5.14 min, and estimated radiation exposure during the localization was 5.21±2.51 mSv. Postprocedural complications occurred in 14 cases (17.3%); complications were minimal pneumothorax (n=10, 12.3%), parenchymal hemorrhage (n=3, 3.7%), and a small amount of hemoptysis (n=1, 1.2%). All target nodules were completely resected; pathologic diagnosis included invasive adenocarcinoma (n=53), adenocarcinoma-in-situ (n=10), atypical adenomatous hyperplasia (n=4), metastasis (n=7), and benign lesions (n=7). PTL procedures can be performed safely and accurately under the guidance of a CBCT virtual navigation system.

  1. Radioguided surgery and the GOSTT concept: From pre-operative image and intraoperative navigation to image-assisted excision.

    PubMed

    Bowles, H; Sánchez, N; Tapias, A; Paredes, P; Campos, F; Bluemel, C; Valdés Olmos, R A; Vidal-Sicart, S

    Radio-guided surgery has been developed for application in those disease scheduled for surgical management, particularly in areas of complex anatomy. This is based on the use of pre-operative scintigraphic planar, tomographic and fused SPECT/CT images, and the possibility of 3D reconstruction for the subsequent intraoperative locating of active lesions using handheld devices (detection probes, gamma cameras, etc.). New tracers and technologies have also been incorporated into these surgical procedures. The combination of visual and acoustic signals during the intraoperative procedure has become possible with new portable imaging modalities. In daily practice, the images offered by these techniques and devices combine perioperative nuclear medicine imaging with the superior resolution of additional optical guidance in the operating room. In many ways they provide real-time images, allowing accurate guidance during surgery, a reduction in the time required for tissue location and an anatomical environment for surgical recognition. All these approaches have been included in the concept known as (radio) Guided intraOperative Scintigraphic Tumour Targeting (GOSTT). This article offers a general view of different nuclear medicine and allied technologies used for several GOSTT procedures, and illustrates the crossing of technological frontiers in radio-guided surgery. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

  2. Age-Related Differences in Associative Learning of Landmarks and Heading Directions in a Virtual Navigation Task

    PubMed Central

    Zhong, Jimmy Y.; Moffat, Scott D.

    2016-01-01

    Previous studies have showed that spatial memory declines with age but have not clarified the relevance of different landmark cues for specifying heading directions among different age groups. This study examined differences between younger, middle-aged and older adults in route learning and memory tasks after they navigated a virtual maze that contained: (a) critical landmarks that were located at decision points (i.e., intersections) and (b) non-critical landmarks that were located at non-decision points (i.e., the sides of the route). Participants were given a recognition memory test for critical and non-critical landmarks and also given a landmark-direction associative learning task. Compared to younger adults, older adults committed more navigation errors during route learning and were poorer at associating the correct heading directions with both critical and non-critical landmarks. Notably, older adults exhibited a landmark-direction associative memory deficit at decision points; this was the first finding to show that an associative memory deficit exist among older adults in a navigational context for landmarks that are pertinent for reaching a goal, and suggest that older adults may expend more cognitive resources on the encoding of landmark/object features than on the binding of landmark and directional information. This study is also the first to show that older adults did not have a tendency to process non-critical landmarks, which were regarded as distractors/irrelevant cues for specifying the directions to reach the goal, to an equivalent or larger extent than younger adults. We explain this finding in view of the low number of non-critical cues in our virtual maze (relative to a real-world urban environment) that might not have evoked older adults’ usual tendency toward processing or encoding distractors. We explain the age differences in navigational and cognitive performance with regards to functional and structural changes in the hippocampus and

  3. Cognitive Load of Navigating without Vision when Guided by Virtual Sound versus Spatial Language

    ERIC Educational Resources Information Center

    Klatzky, Roberta L.; Marston, James R.; Giudice, Nicholas A.; Golledge, Reginald G.; Loomis, Jack M.

    2006-01-01

    A vibrotactile N-back task was used to generate cognitive load while participants were guided along virtual paths without vision. As participants stepped in place, they moved along a virtual path of linear segments. Information was provided en route about the direction of the next turning point, by spatial language ("left," "right," or "straight")…

  4. Toward real-time endoscopically-guided robotic navigation based on a 3D virtual surgical field model

    NASA Astrophysics Data System (ADS)

    Gong, Yuanzheng; Hu, Danying; Hannaford, Blake; Seibel, Eric J.

    2015-03-01

    The challenge is to accurately guide the surgical tool within the three-dimensional (3D) surgical field for roboticallyassisted operations such as tumor margin removal from a debulked brain tumor cavity. The proposed technique is 3D image-guided surgical navigation based on matching intraoperative video frames to a 3D virtual model of the surgical field. A small laser-scanning endoscopic camera was attached to a mock minimally-invasive surgical tool that was manipulated toward a region of interest (residual tumor) within a phantom of a debulked brain tumor. Video frames from the endoscope provided features that were matched to the 3D virtual model, which were reconstructed earlier by raster scanning over the surgical field. Camera pose (position and orientation) is recovered by implementing a constrained bundle adjustment algorithm. Navigational error during the approach to fluorescence target (residual tumor) is determined by comparing the calculated camera pose to the measured camera pose using a micro-positioning stage. From these preliminary results, computation efficiency of the algorithm in MATLAB code is near real-time (2.5 sec for each estimation of pose), which can be improved by implementation in C++. Error analysis produced 3-mm distance error and 2.5 degree of orientation error on average. The sources of these errors come from 1) inaccuracy of the 3D virtual model, generated on a calibrated RAVEN robotic platform with stereo tracking; 2) inaccuracy of endoscope intrinsic parameters, such as focal length; and 3) any endoscopic image distortion from scanning irregularities. This work demonstrates feasibility of micro-camera 3D guidance of a robotic surgical tool.

  5. Virtual environment navigation with look-around mode to explore new real spaces by people who are blind.

    PubMed

    Lahav, Orly; Gedalevitz, Hadas; Battersby, Steven; Brown, David; Evett, Lindsay; Merritt, Patrick

    2017-02-10

    This paper examines the ability of people who are blind to construct a mental map and perform orientation tasks in real space by using Nintendo Wii technologies to explore virtual environments. The participant explores new spaces through haptic and auditory feedback triggered by pointing or walking in the virtual environments and later constructs a mental map, which can be used to navigate in real space. The study included 10 participants who were congenitally or adventitiously blind, divided into experimental and control groups. The research was implemented by using virtual environments exploration and orientation tasks in real spaces, using both qualitative and quantitative methods in its methodology. The results show that the mode of exploration afforded to the experimental group is radically new in orientation and mobility training; as a result 60% of the experimental participants constructed mental maps that were based on map model, compared with only 30% of the control group participants. Using technology that enabled them to explore and to collect spatial information in a way that does not exist in real space influenced the ability of the experimental group to construct a mental map based on the map model. Implications for rehabilitation The virtual cane system for the first time enables people who are blind to explore and collect spatial information via the look-around mode in addition to the walk-around mode. People who are blind prefer to use look-around mode to explore new spaces, as opposed to the walking mode. Although the look-around mode requires users to establish a complex collecting and processing procedure for the spatial data, people who are blind using this mode are able to construct a mental map as a map model. For people who are blind (as for the sighted) construction of a mental map based on map model offers more flexibility in choosing a walking path in a real space, accounting for changes that occur in the space.

  6. YouTube Videos to Create a “Virtual Hospital Experience” for Hip and Knee Replacement Patients to Decrease Preoperative Anxiety: A Randomized Trial

    PubMed Central

    Brennan, Katharyn; Kazmerchak, Shari; Pratt, Jason

    2016-01-01

    Background With declining reimbursement to health care systems, face-to-face time between patients and providers to optimize preoperative education and counseling may be challenging. Objective Because high patient anxiety prior to surgery has been linked to more severe and persistent pain after joint replacement surgery, the Orthopedic Surgery Department at Mayo Clinic in Florida created a playlist of 16 YouTube videos aimed at creating a virtual hospital experience for primary total hip and knee joint replacement patients. A randomized trial was then performed to evaluate the potential impact of viewing this playlist on preoperative anxiety. Methods Each patient completed a Generalized Anxiety Disorder (GAD) score assessment at the time of the routine preoperative clinic visit and then randomized based on his/her gender, type of surgery, and initial GAD score to either the control group of standard education (education at face-to-face clinical visits as well as printed educational materials) or the treatment group (standard education plus access to the YouTube playlist). On the morning of the patient’s surgery, the same survey was repeated. Of the 65 patients who consented to participate in the study, 53 completed the study (82%) with 28 of 29 (97% completed) in the control group and 25 of 36 (69% completed) in the treatment group. Results Overall, the results showed a trend toward less anxiety in patients who viewed the YouTube videos; this was exhibited by a reduction in the median GAD score by 1 point. This trend is more clearly present in patients with high preoperative anxiety (predominantly women), as seen in the reduction of the median GAD score by 6 points in the treatment group. Conclusions Although our experience is limited, our results indicate that a series of tailored videos may decrease patient anxiety preoperatively. We recommend further exploration of both this concept and the use of social media tools in preoperative patient education. Trial

  7. YouTube Videos to Create a "Virtual Hospital Experience" for Hip and Knee Replacement Patients to Decrease Preoperative Anxiety: A Randomized Trial.

    PubMed

    O'Connor, Mary I; Brennan, Katharyn; Kazmerchak, Shari; Pratt, Jason

    2016-04-18

    With declining reimbursement to health care systems, face-to-face time between patients and providers to optimize preoperative education and counseling may be challenging. Because high patient anxiety prior to surgery has been linked to more severe and persistent pain after joint replacement surgery, the Orthopedic Surgery Department at Mayo Clinic in Florida created a playlist of 16 YouTube videos aimed at creating a virtual hospital experience for primary total hip and knee joint replacement patients. A randomized trial was then performed to evaluate the potential impact of viewing this playlist on preoperative anxiety. Each patient completed a Generalized Anxiety Disorder (GAD) score assessment at the time of the routine preoperative clinic visit and then randomized based on his/her gender, type of surgery, and initial GAD score to either the control group of standard education (education at face-to-face clinical visits as well as printed educational materials) or the treatment group (standard education plus access to the YouTube playlist). On the morning of the patient's surgery, the same survey was repeated. Of the 65 patients who consented to participate in the study, 53 completed the study (82%) with 28 of 29 (97% completed) in the control group and 25 of 36 (69% completed) in the treatment group. Overall, the results showed a trend toward less anxiety in patients who viewed the YouTube videos; this was exhibited by a reduction in the median GAD score by 1 point. This trend is more clearly present in patients with high preoperative anxiety (predominantly women), as seen in the reduction of the median GAD score by 6 points in the treatment group. Although our experience is limited, our results indicate that a series of tailored videos may decrease patient anxiety preoperatively. We recommend further exploration of both this concept and the use of social media tools in preoperative patient education. Clinicaltrials.gov NCT02546180; http

  8. Modulation of spatial and response strategies by phase of the menstrual cycle in women tested in a virtual navigation task.

    PubMed

    Hussain, Dema; Hanafi, Sarah; Konishi, Kyoko; Brake, Wayne G; Bohbot, Véronique D

    2016-08-01

    Different memory systems are employed to navigate an environment. It has been consistently shown in rodents that estrogen impacts multiple memory system bias such that low estradiol (E2) is associated with increased use of a striatal-mediated response strategy whereas high E2 increases use of a hippocampal-dependent spatial memory. Low E2 also enhances performance on a response-based task whereas high E2 levels improve learning on a spatial task. The purpose of the present cross-sectional study was to investigate navigational strategies in young, healthy, naturally cycling women. Participants were split into either an early follicular (i.e., when E2 levels are low), ovulatory (i.e., when E2 levels are high) or mid/late luteal (i.e., end of the cycle, when E2 levels decrease and progesterone levels rise) phase group, using self-reported date of the menstrual cycle. Serum hormone level measurements (E2, progesterone, testosterone) were used to confirm cycle phase assignment. Participants were administered a verbal memory task as well as a virtual navigation task that can be solved by using either a response or spatial strategy. Women tested in the ovulatory phase, under high E2 conditions, performed better on a verbal memory task than women tested during the other phases of the cycle. Interestingly, women tested in the mid/late luteal phase, when progesterone is high, predominantly used a spatial strategy, whereas the opposite pattern was observed in the early follicular and ovulatory groups. Our data suggest that the specific memory system engaged differs depending on the phase of the menstrual cycle and may be mediated by both E2 and progesterone, rather than E2 alone. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Virtual Long Baseline (VLBL) Autonomous Underwater Vehicle Navigation Using a Single Transponder

    DTIC Science & Technology

    2006-06-01

    the VLBL navigation method with real-world data. These dives, ABE162 and ABE163, were both bottom survey operations done in the Juan de Fuca region...from ABE operations on the R/V Atlantis in the Juan de Fuca Straits in 2004. Section 5.1.1: Method of Analysis Data concerning the exact duration of...objectives. These survey missions are often carried out progressively along midocean ridges in a number of adjacent dive sites. Figure 32: The

  10. Impairment of preoperative language mapping by lesion location: a functional magnetic resonance imaging, navigated transcranial magnetic stimulation, and direct cortical stimulation study.

    PubMed

    Ille, Sebastian; Sollmann, Nico; Hauck, Theresa; Maurer, Stefanie; Tanigawa, Noriko; Obermueller, Thomas; Negwer, Chiara; Droese, Doris; Boeckh-Behrens, Tobias; Meyer, Bernhard; Ringel, Florian; Krieg, Sandro M

    2015-08-01

    Language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) is increasingly used and has already replaced functional MRI (fMRI) in some institutions for preoperative mapping of neurosurgical patients. Yet some factors affect the concordance of both methods with direct cortical stimulation (DCS), most likely by lesions affecting cortical oxygenation levels. Therefore, the impairment of the accuracy of rTMS and fMRI was analyzed and compared with DCS during awake surgery in patients with intraparenchymal lesions. Language mapping was performed by DCS, rTMS, and fMRI using an object-naming task in 27 patients with left-sided perisylvian lesions, and the induced language errors of each method were assigned to the cortical parcellation system. Subsequently, the receiver operating characteristics were calculated for rTMS and fMRI and compared with DCS as ground truth for regions with (w/) and without (w/o) the lesion in the mapped regions. The w/ subgroup revealed a sensitivity of 100% (w/o 100%), a specificity of 8% (w/o 5%), a positive predictive value of 34% (w/o: 53%), and a negative predictive value (NPV) of 100% (w/o: 100%) for the comparison of rTMS versus DCS. Findings for the comparison of fMRI versus DCS within the w/ subgroup revealed a sensitivity of 32% (w/o: 62%), a specificity of 88% (w/o: 60%), a positive predictive value of 56% (w/o: 62%), and a NPV of 73% (w/o: 60%). Although strengths and weaknesses exist for both rTMS and fMRI, the results show that rTMS is less affected by a brain lesion than fMRI, especially when performing mapping of language-negative cortical regions based on sensitivity and NPV.

  11. A Virtual Map to Support People Who Are Blind in Navigation through Real Spaces

    ERIC Educational Resources Information Center

    Lahav, Orly; Schloerb, David W.; Kumar, Siddarth; Srinivasan, Mandayam A.

    2011-01-01

    Most of the spatial information needed by sighted people to construct cognitive maps of spaces is gathered through the visual channel. Unfortunately, people who are blind lack the ability to collect the required spatial information in advance. The use of virtual reality as a learning and rehabilitation tool for people with disabilities has been on…

  12. Linking Audio and Visual Information while Navigating in a Virtual Reality Kiosk Display

    ERIC Educational Resources Information Center

    Sullivan, Briana; Ware, Colin; Plumlee, Matthew

    2006-01-01

    3D interactive virtual reality museum exhibits should be easy to use, entertaining, and informative. If the interface is intuitive, it will allow the user more time to learn the educational content of the exhibit. This research deals with interface issues concerning activating audio descriptions of images in such exhibits while the user is…

  13. Navigating Massively Multiplayer Online Games: Evaluating 21st Century Skills for Learning within Virtual Environments

    ERIC Educational Resources Information Center

    McCreery, Michael P.; Schrader, P. G.; Krach, S. Kathleen

    2011-01-01

    There is a substantial and growing interest in immersive virtual spaces as contexts for 21st century skills like problem solving, communication, and collaboration. However, little consideration has been given to the ways in which users become proficient in these environments or what types of target behaviors are associated with 21st century…

  14. A Virtual Map to Support People Who Are Blind in Navigation through Real Spaces

    ERIC Educational Resources Information Center

    Lahav, Orly; Schloerb, David W.; Kumar, Siddarth; Srinivasan, Mandayam A.

    2011-01-01

    Most of the spatial information needed by sighted people to construct cognitive maps of spaces is gathered through the visual channel. Unfortunately, people who are blind lack the ability to collect the required spatial information in advance. The use of virtual reality as a learning and rehabilitation tool for people with disabilities has been on…

  15. Linking Audio and Visual Information while Navigating in a Virtual Reality Kiosk Display

    ERIC Educational Resources Information Center

    Sullivan, Briana; Ware, Colin; Plumlee, Matthew

    2006-01-01

    3D interactive virtual reality museum exhibits should be easy to use, entertaining, and informative. If the interface is intuitive, it will allow the user more time to learn the educational content of the exhibit. This research deals with interface issues concerning activating audio descriptions of images in such exhibits while the user is…

  16. Navigating Massively Multiplayer Online Games: Evaluating 21st Century Skills for Learning within Virtual Environments

    ERIC Educational Resources Information Center

    McCreery, Michael P.; Schrader, P. G.; Krach, S. Kathleen

    2011-01-01

    There is a substantial and growing interest in immersive virtual spaces as contexts for 21st century skills like problem solving, communication, and collaboration. However, little consideration has been given to the ways in which users become proficient in these environments or what types of target behaviors are associated with 21st century…

  17. Virtual Patients in a Behavioral Medicine Massive Open Online Course (MOOC): A Case-Based Analysis of Technical Capacity and User Navigation Pathways

    PubMed Central

    Berman, Anne H; Stathakarou, Natalia; McGrath, Cormac; Bartyński, Tomasz; Nowakowski, Piotr; Malawski, Maciej; Zary, Nabil

    2015-01-01

    Background Massive open online courses (MOOCs) have been criticized for focusing on presentation of short video clip lectures and asking theoretical multiple-choice questions. A potential way of vitalizing these educational activities in the health sciences is to introduce virtual patients. Experiences from such extensions in MOOCs have not previously been reported in the literature. Objective This study analyzes technical challenges and solutions for offering virtual patients in health-related MOOCs and describes patterns of virtual patient use in one such course. Our aims are to reduce the technical uncertainty related to these extensions, point to aspects that could be optimized for a better learner experience, and raise prospective research questions by describing indicators of virtual patient use on a massive scale. Methods The Behavioral Medicine MOOC was offered by Karolinska Institutet, a medical university, on the EdX platform in the autumn of 2014. Course content was enhanced by two virtual patient scenarios presented in the OpenLabyrinth system and hosted on the VPH-Share cloud infrastructure. We analyzed web server and session logs and a participant satisfaction survey. Navigation pathways were summarized using a visual analytics tool developed for the purpose of this study. Results The number of course enrollments reached 19,236. At the official closing date, 2317 participants (12.1% of total enrollment) had declared completing the first virtual patient assignment and 1640 (8.5%) participants confirmed completion of the second virtual patient assignment. Peak activity involved 359 user sessions per day. The OpenLabyrinth system, deployed on four virtual servers, coped well with the workload. Participant survey respondents (n=479) regarded the activity as a helpful exercise in the course (83.1%). Technical challenges reported involved poor or restricted access to videos in certain areas of the world and occasional problems with lost sessions. The visual

  18. Virtual Patients in a Behavioral Medicine Massive Open Online Course (MOOC): A Case-Based Analysis of Technical Capacity and User Navigation Pathways.

    PubMed

    Kononowicz, Andrzej A; Berman, Anne H; Stathakarou, Natalia; McGrath, Cormac; Bartyński, Tomasz; Nowakowski, Piotr; Malawski, Maciej; Zary, Nabil

    2015-09-10

    Massive open online courses (MOOCs) have been criticized for focusing on presentation of short video clip lectures and asking theoretical multiple-choice questions. A potential way of vitalizing these educational activities in the health sciences is to introduce virtual patients. Experiences from such extensions in MOOCs have not previously been reported in the literature. This study analyzes technical challenges and solutions for offering virtual patients in health-related MOOCs and describes patterns of virtual patient use in one such course. Our aims are to reduce the technical uncertainty related to these extensions, point to aspects that could be optimized for a better learner experience, and raise prospective research questions by describing indicators of virtual patient use on a massive scale. The Behavioral Medicine MOOC was offered by Karolinska Institutet, a medical university, on the EdX platform in the autumn of 2014. Course content was enhanced by two virtual patient scenarios presented in the OpenLabyrinth system and hosted on the VPH-Share cloud infrastructure. We analyzed web server and session logs and a participant satisfaction survey. Navigation pathways were summarized using a visual analytics tool developed for the purpose of this study. The number of course enrollments reached 19,236. At the official closing date, 2317 participants (12.1% of total enrollment) had declared completing the first virtual patient assignment and 1640 (8.5%) participants confirmed completion of the second virtual patient assignment. Peak activity involved 359 user sessions per day. The OpenLabyrinth system, deployed on four virtual servers, coped well with the workload. Participant survey respondents (n=479) regarded the activity as a helpful exercise in the course (83.1%). Technical challenges reported involved poor or restricted access to videos in certain areas of the world and occasional problems with lost sessions. The visual analyses of user pathways display

  19. Characterizing student navigation in educational multiuser virtual environments: A case study using data from the River City project

    NASA Astrophysics Data System (ADS)

    Dukas, Georg

    Though research in emerging technologies is vital to fulfilling their incredible potential for educational applications, it is often fraught with analytic challenges related to large datasets. This thesis explores these challenges in researching multiuser virtual environments (MUVEs). In a MUVE, users assume a persona and traverse a virtual space often depicted as a physical world, interacting with other users and digital artifacts. As students participate in MUVE-based curricula, detailed records of their paths through the virtual world are typically collected in event logs. Although many studies have demonstrated the instructional power of MUVEs (e.g., Barab, Hay, Barnett, & Squire, 2001; Ketelhut, Dede, Clarke, Nelson, & Bowman, 2008), none have successfully quantified these student paths for analysis in the aggregate. This thesis constructs several frameworks for conducting research involving student navigational choices in MUVEs based on a case study of data generated from the River City project. After providing a context for the research and an introduction to the River City dataset, the first part of this thesis explores the issues associated with data compression and presents a grounded theory approach (Glaser & Strauss, 1967) to the cleaning, compacting, and coding or MUVE datasets. In summary of this section, I discuss the implication of preparation choices for further analysis. Second, two conceptually different approaches to analyzing behavioral sequences are investigated. For each approach, a theoretical context, description of possible exploratory and confirmatory methods, and illustrative examples from River City are provided. The thesis then situates these specific analytic approaches within the constellation of possible research utilizing MUVE event log data. Finally, based on the lessons of River City and the investigation of a spectrum of possible event logs, a set of design heuristics for data collection in MUVEs is constructed and a possible

  20. Navigation accuracy for an intracardiac procedure using ultrasound enhanced virtual reality

    NASA Astrophysics Data System (ADS)

    Wiles, Andrew D.; Guiraudon, Gerard M.; Moore, John; Wedlake, Christopher; Linte, Cristian A.; Bainbridge, Daniel; Jones, Douglas L.; Peters, Terry M.

    2007-03-01

    Minimally invasive techniques for use inside the beating heart, such as mitral valve replacement and septal defect repair, are the focus of this work. Traditional techniques for these procedures require an open chest approach and a cardiopulmonary bypass machine. New techniques using port access and a combined surgical guidance tool that includes an overlaid two-dimensional ultrasound image in a virtual reality environment are being developed. To test this technique, a cardiac phantom was developed to simulate the anatomy. The phantom consists of an acrylic box filled with a 7% glycerol solution with ultrasound properties similar to human tissue. Plate inserts mounted in the box simulate the physical anatomy. An accuracy assessment was completed to evaluate the performance of the system. Using the cardiac phantom, a 2mm diameter glass toroid was attached to a vertical plate as the target location. An elastic material was placed between the target and plate to simulate the target lying on a soft tissue structure. The target was measured using an independent measurement system and was represented as a sphere in the virtual reality system. The goal was to test the ability of a user to probe the target using three guidance methods: (i) 2D ultrasound only, (ii) virtual reality only and (iii) ultrasound enhanced virtual reality. Three users attempted the task three times each for each method. An independent measurement system was used to validate the measurement. The ultrasound imaging alone was poor in locating the target (5.42 mm RMS) while the other methods proved to be significantly better (1.02 mm RMS and 1.47 mm RMS respectively). The ultrasound enhancement is expected to be more useful in a dynamic environment where the system registration may be disturbed.

  1. Effectiveness of a Novel Augmented Reality-Based Navigation System in Treatment of Orbital Hypertelorism.

    PubMed

    Zhu, Ming; Chai, Gang; Lin, Li; Xin, Yu; Tan, Andy; Bogari, Melia; Zhang, Yan; Li, Qingfeng

    2016-12-01

    Augmented reality (AR) technology can superimpose the virtual image generated by computer onto the real operating field to present an integral image to enhance surgical safety. The purpose of our study is to develop a novel AR-based navigation system for craniofacial surgery. We focus on orbital hypertelorism correction, because the surgery requires high preciseness and is considered tough even for senior craniofacial surgeon. Twelve patients with orbital hypertelorism were selected. The preoperative computed tomography data were imported into 3-dimensional platform for preoperational design. The position and orientation of virtual information and real world were adjusted by image registration process. The AR toolkits were used to realize the integral image. Afterward, computed tomography was also performed after operation for comparing the difference between preoperational plan and actual operational outcome. Our AR-based navigation system was successfully used in these patients, directly displaying 3-dimensional navigational information onto the surgical field. They all achieved a better appearance by the guidance of navigation image. The difference in interdacryon distance and the dacryon point of each side appear no significant (P > 0.05) between preoperational plan and actual surgical outcome. This study reports on an effective visualized approach for guiding orbital hypertelorism correction. Our AR-based navigation system may lay a foundation for craniofacial surgery navigation. The AR technology could be considered as a helpful tool for precise osteotomy in craniofacial surgery.

  2. Performance-Driven Hybrid Full-Body Character Control for Navigation and Interaction in Virtual Environments

    NASA Astrophysics Data System (ADS)

    Mousas, Christos; Anagnostopoulos, Christos-Nikolaos

    2017-06-01

    This paper presents a hybrid character control interface that provides the ability to synthesize in real-time a variety of actions based on the user's performance capture. The proposed methodology enables three different performance interaction modules: the performance animation control that enables the direct mapping of the user's pose to the character, the motion controller that synthesizes the desired motion of the character based on an activity recognition methodology, and the hybrid control that lies within the performance animation and the motion controller. With the methodology presented, the user will have the freedom to interact within the virtual environment, as well as the ability to manipulate the character and to synthesize a variety of actions that cannot be performed directly by him/her, but which the system synthesizes. Therefore, the user is able to interact with the virtual environment in a more sophisticated fashion. This paper presents examples of different scenarios based on the three different full-body character control methodologies.

  3. Techniques of stapler-based navigational thoracoscopic segmentectomy using virtual assisted lung mapping (VAL-MAP)

    PubMed Central

    Murayama, Tomonori; Nakajima, Jun

    2016-01-01

    Anatomical segmentectomies play an important role in oncological lung resection, particularly for ground-glass types of primary lung cancers. This operation can also be applied to metastatic lung tumors deep in the lung. Virtual assisted lung mapping (VAL-MAP) is a novel technique that allows for bronchoscopic multi-spot dye markings to provide “geometric information” to the lung surface, using three-dimensional virtual images. In addition to wedge resections, VAL-MAP has been found to be useful in thoracoscopic segmentectomies, particularly complex segmentectomies, such as combined subsegmentectomies or extended segmentectomies. There are five steps in VAL-MAP-assisted segmentectomies: (I) “standing” stitches along the resection lines; (II) cleaning hilar anatomy; (III) confirming hilar anatomy; (IV) going 1 cm deeper; (V) step-by-step stapling technique. Depending on the anatomy, segmentectomies can be classified into linear (lingular, S6, S2), V- or U-shaped (right S1, left S3, S2b + S3a), and three dimensional (S7, S8, S9, S10) segmentectomies. Particularly three dimensional segmentectomies are challenging in the complexity of stapling techniques. This review focuses on how VAL-MAP can be utilized in segmentectomy, and how this technique can assist the stapling process in even the most challenging ones. PMID:28066675

  4. Techniques of stapler-based navigational thoracoscopic segmentectomy using virtual assisted lung mapping (VAL-MAP).

    PubMed

    Sato, Masaaki; Murayama, Tomonori; Nakajima, Jun

    2016-10-01

    Anatomical segmentectomies play an important role in oncological lung resection, particularly for ground-glass types of primary lung cancers. This operation can also be applied to metastatic lung tumors deep in the lung. Virtual assisted lung mapping (VAL-MAP) is a novel technique that allows for bronchoscopic multi-spot dye markings to provide "geometric information" to the lung surface, using three-dimensional virtual images. In addition to wedge resections, VAL-MAP has been found to be useful in thoracoscopic segmentectomies, particularly complex segmentectomies, such as combined subsegmentectomies or extended segmentectomies. There are five steps in VAL-MAP-assisted segmentectomies: (I) "standing" stitches along the resection lines; (II) cleaning hilar anatomy; (III) confirming hilar anatomy; (IV) going 1 cm deeper; (V) step-by-step stapling technique. Depending on the anatomy, segmentectomies can be classified into linear (lingular, S6, S2), V- or U-shaped (right S1, left S3, S2b + S3a), and three dimensional (S7, S8, S9, S10) segmentectomies. Particularly three dimensional segmentectomies are challenging in the complexity of stapling techniques. This review focuses on how VAL-MAP can be utilized in segmentectomy, and how this technique can assist the stapling process in even the most challenging ones.

  5. Virtual navigation performance: the relationship to field of view and prior video gaming experience.

    PubMed

    Richardson, Anthony E; Collaer, Marcia L

    2011-04-01

    Two experiments examined whether learning a virtual environment was influenced by field of view and how it related to prior video gaming experience. In the first experiment, participants (42 men, 39 women; M age = 19.5 yr., SD = 1.8) performed worse on a spatial orientation task displayed with a narrow field of view in comparison to medium and wide field-of-view displays. Counter to initial hypotheses, wide field-of-view displays did not improve performance over medium displays, and this was replicated in a second experiment (30 men, 30 women; M age = 20.4 yr., SD = 1.9) presenting a more complex learning environment. Self-reported video gaming experience correlated with several spatial tasks: virtual environment pointing and tests of Judgment of Line Angle and Position, mental rotation, and Useful Field of View (with correlations between .31 and .45). When prior video gaming experience was included as a covariate, sex differences in spatial tasks disappeared.

  6. Human navigation that requires calculating heading vectors recruits parietal cortex in a virtual and visually sparse water maze task in fMRI.

    PubMed

    Rodriguez, Paul F

    2010-08-01

    Spatial navigation in the real-world is a complex task that involves many functions, such as landmark identification, orientation, and the calculation of heading vectors. This study uses a 2 x 2 experimental design with fMRI to isolate mnemonic and navigational processes that accompany the calculation of heading vectors. The conditions are based on a working memory version of the Morris water maze task and navigation takes place in a visually austere virtual environment. In an allocentric condition, subjects navigate around a circular arena where there is one small red square on the wall. Each trial begins with an encoding phase in which subjects locate and navigate to a visible coin. Then, in a test phase, after being randomly repositioned, they retrieve the coin when it is invisible. In a control task, there are eight distinct cues around the arena that provide direct cue-place information. Results show significant interaction effects in bilateral posterior parietal cortex, which is compatible with evidence that parietal cortex helps translating between allocentric coordinates and egocentric directions. There was also greater activation for the allocentric task in right posterior hippocampus and left retrosplenial cortex, which could be related to self-localization and orientation. The findings are also compatible with the recent proposal by Kubie and Fenton (2009) that navigation primarily depends on heading vectors between salient places. 2010 APA, all rights reserved.

  7. Convergent validity and sex differences in healthy elderly adults for performance on 3D virtual reality navigation learning and 2D hidden maze tasks.

    PubMed

    Tippett, William J; Lee, Jang-Han; Mraz, Richard; Zakzanis, Konstantine K; Snyder, Peter J; Black, Sandra E; Graham, Simon J

    2009-04-01

    This study assessed the convergent validity of a virtual environment (VE) navigation learning task, the Groton Maze Learning Test (GMLT), and selected traditional neuropsychological tests performed in a group of healthy elderly adults (n = 24). The cohort was divided equally between males and females to explore performance variability due to sex differences, which were subsequently characterized and reported as part of the analysis. To facilitate performance comparisons, specific "efficiency" scores were created for both the VE navigation task and the GMLT. Men reached peak performance more rapidly than women during VE navigation and on the GMLT and significantly outperformed women on the first learning trial in the VE. Results suggest reasonable convergent validity across the VE task, GMLT, and selected neuropsychological tests for assessment of spatial memory.

  8. Virtualization

    NASA Astrophysics Data System (ADS)

    Garg, Vikas

    2012-11-01

    The main aim of the research was to get the knowledge of present trends and technologies used in it field. Virtualization Allows multiple applications to run in isolation within virtual machines on the same physical machine. Virtualization provides direct access to the hardware resources to give you much greater performance than software emulation. VMware provides hardware virtualization that presents a complete x86 platform to the virtual machine. By doing this project we get an opportunity to learn about an emerging field of IT Sector. They also gave us the details of project like 'Storage Vmmotioní on which HP is currently working.

  9. Gender differences in landmark learning for virtual navigation: the role of distance to a goal.

    PubMed

    Chamizo, V D; Artigas, A A; Sansa, J; Banterla, F

    2011-09-01

    We used a new virtual program in two experiments to prepare subjects to perform the Morris water task (www.nesplora.com). The subjects were Psychology students; they were trained to locate a safe platform amidst the presence of four pinpoint landmarks spaced around the edge of the pool (i.e., two landmarks relatively near the platform and two landmarks relatively distant away from it). At the end of the training phase, we administered one test trial without the platform and recorded the amount of time that the students had spent in the platform quadrant. In Experiment 1, we conducted the test trial in the presence of one or two of the distant landmarks. When only one landmark was present during testing, performance fell to chance. However, the men outperformed the women when the two distant landmarks were both present. Experiment 2 replicated the previous results and extended it by showing that no sex differences exist when the searching process is based on the near landmarks. Both the men and the women had similarly good performances when the landmarks were present both individually and together. When present together, an addition effect was found. Far landmark tests favor configural learning processes, whereas near landmark tests favor elemental learning. Our findings suggest that other factors in addition to the use of directional cues can underlie the sex differences in the spatial learning process. Thus, we expand upon previous research in the field.

  10. Virtual reality distraction decreases routine intravenous sedation and procedure-related pain during preoperative adductor canal catheter insertion: a retrospective study.

    PubMed

    Pandya, Pooja G; Kim, T Edward; Howard, Steven K; Stary, Erica; Leng, Jody C; Hunter, Oluwatobi O; Mariano, Edward R

    2017-08-01

    Virtual reality (VR) distraction is a nonpharmacological method to prevent acute pain that has not yet been thoroughly explored for anesthesiology. We present our experience using VR distraction to decrease routine intravenous sedation for patients undergoing preoperative perineural catheter insertion. This 1-month quality improvement project involved all elective unilateral primary total knee arthroplasty patients who received a preoperative adductor canal catheter. Clinical data were analyzed retrospectively. For the first half of the month, all patients received usual care; intravenous sedation was administered at the discretion of the regional anesthesiologist. For the second half of the month, patients were offered VR distraction with intravenous sedation upon request. The primary outcome was fentanyl dosage; other outcomes included midazolam dosage, procedure-related pain, procedural time, and blood pressure changes. Seven patients received usual care and seven used VR. In the VR group, 1/7 received intravenous sedation versus 6/7 who received usual care (P = 0.029). The fentanyl dose was lower (median [10th-90th percentiles]) in the VR group (0 [0-20] µg) versus the non-VR group (50 [30-100] µg; P = 0.008). Midazolam use was lower in the VR group (0 [0-0] mg) than in the non-VR group (1 [0-1] mg; P = 0.024). Procedure-related pain was lower in the VR group (1 [1-4] NRS) versus the non-VR group (3 [2-6] NRS; P = 0.032). There was no difference in other outcomes. VR distraction may provide an effective nonpharmacological alternative to intravenous sedation for the ultrasound-guided placement of certain perineural catheters.

  11. sLORETA current source density analysis of evoked potentials for spatial updating in a virtual navigation task.

    PubMed

    Nguyen, Hai M; Matsumoto, Jumpei; Tran, Anh H; Ono, Taketoshi; Nishijo, Hisao

    2014-01-01

    Previous studies have reported that multiple brain regions are activated during spatial navigation. However, it is unclear whether these activated brain regions are specifically associated with spatial updating or whether some regions are recruited for parallel cognitive processes. The present study aimed to localize current sources of event related potentials (ERPs) associated with spatial updating specifically. In the control phase of the experiment, electroencephalograms (EEGs) were recorded while subjects sequentially traced 10 blue checkpoints on the streets of a virtual town, which were sequentially connected by a green line, by manipulating a joystick. In the test phase of the experiment, the checkpoints and green line were not indicated. Instead, a tone was presented when the subjects entered the reference points where they were then required to trace the 10 invisible spatial reference points corresponding to the checkpoints. The vertex-positive ERPs with latencies of approximately 340 ms from the moment when the subjects entered the unmarked reference points were significantly larger in the test than in the control phases. Current source density analysis of the ERPs by standardized low-resolution brain electromagnetic tomography (sLORETA) indicated activation of brain regions in the test phase that are associated with place and landmark recognition (entorhinal cortex/hippocampus, parahippocampal and retrosplenial cortices, fusiform, and lingual gyri), detecting self-motion (posterior cingulate and posterior insular cortices), motor planning (superior frontal gyrus, including the medial frontal cortex), and regions that process spatial attention (inferior parietal lobule). The present results provide the first identification of the current sources of ERPs associated with spatial updating, and suggest that multiple systems are active in parallel during spatial updating.

  12. Non-rigid alignment of pre-operative MRI, fMRI, and DT-MRI with intra-operative MRI for enhanced visualization and navigation in image-guided neurosurgery.

    PubMed

    Archip, Neculai; Clatz, Olivier; Whalen, Stephen; Kacher, Dan; Fedorov, Andriy; Kot, Andriy; Chrisochoides, Nikos; Jolesz, Ferenc; Golby, Alexandra; Black, Peter M; Warfield, Simon K

    2007-04-01

    The usefulness of neurosurgical navigation with current visualizations is seriously compromised by brain shift, which inevitably occurs during the course of the operation, significantly degrading the precise alignment between the pre-operative MR data and the intra-operative shape of the brain. Our objectives were (i) to evaluate the feasibility of non-rigid registration that compensates for the brain deformations within the time constraints imposed by neurosurgery, and (ii) to create augmented reality visualizations of critical structural and functional brain regions during neurosurgery using pre-operatively acquired fMRI and DT-MRI. Eleven consecutive patients with supratentorial gliomas were included in our study. All underwent surgery at our intra-operative MR imaging-guided therapy facility and have tumors in eloquent brain areas (e.g. precentral gyrus and cortico-spinal tract). Functional MRI and DT-MRI, together with MPRAGE and T2w structural MRI were acquired at 3 T prior to surgery. SPGR and T2w images were acquired with a 0.5 T magnet during each procedure. Quantitative assessment of the alignment accuracy was carried out and compared with current state-of-the-art systems based only on rigid registration. Alignment between pre-operative and intra-operative datasets was successfully carried out during surgery for all patients. Overall, the mean residual displacement remaining after non-rigid registration was 1.82 mm. There is a statistically significant improvement in alignment accuracy utilizing our non-rigid registration in comparison to the currently used technology (p<0.001). We were able to achieve intra-operative rigid and non-rigid registration of (1) pre-operative structural MRI with intra-operative T1w MRI; (2) pre-operative fMRI with intra-operative T1w MRI, and (3) pre-operative DT-MRI with intra-operative T1w MRI. The registration algorithms as implemented were sufficiently robust and rapid to meet the hard real-time constraints of intra

  13. Non-rigid alignment of preoperative MRI, fMRI, and DT-MRI with intra-operative MRI for enhanced visualization and navigation in image-guided neurosurgery

    PubMed Central

    Archip, Neculai; Clatz, Olivier; Whalen, Stephen; Kacher, Dan; Fedorov, Andriy; Kot, Andriy; Chrisochoides, Nikos; Jolesz, Ferenc; Golby, Alexandra; Black, Peter M.; Warfield, Simon K.

    2012-01-01

    Objective The usefulness of neurosurgical navigation with current visualizations is seriously compromised by brain shift, which inevitably occurs during the course of the operation, significantly degrading the precise alignment between the preoperative MR data and the intra-operative shape of the brain. Our objectives were (i) to evaluate the feasibility of non-rigid registration that compensates for the brain deformations within the time constraints imposed by neurosurgery, and (ii) create augmented reality visualizations of critical structural and functional brain regions during neurosurgery using pre-operatively acquired fMRI and DT-MRI. Materials and Methods Eleven consecutive patients with supratentorial gliomas were included in our study. All underwent surgery at our intra-operative MR imaging–guided therapy facility and have tumors in eloquent brain areas (e.g. precentral gyrus and cortico-spinal tract). Functional MRI and DT-MRI, together with MPRAGE and T2w structural MRI were acquired at 3T prior to surgery. SPGR and T2w images were acquired with a 0.5T magnet during each procedure. Quantitative assessment of the alignment accuracy was carried out and compared with current state-of the-art systems based only on rigid-registration. Results Alignment between preoperative and intra-operative datasets was successfully carried out during surgery for all patients. Overall, the mean residual displacement remaining after non-rigid registration was 1.82 mm. There is a statistically significant improvement in alignment accuracy utilizing our non-rigid registration in comparison to the currently used technology (p<0.001). Conclusions We were able to achieve intra-operative rigid and non-rigid registration of (1) pre-operative structural MRI with intra-operative T1w MRI; (2) pre-operative FMRI with intra-operative T1w MRI, and (3) pre-operative DT-MRI with intra-operative T1w MRI. The registration algorithms as implemented were sufficiently robust and rapid to meet

  14. Virtual environments for the transfer of navigation skills in the blind: a comparison of directed instruction vs. video game based learning approaches

    PubMed Central

    Connors, Erin C.; Chrastil, Elizabeth R.; Sánchez, Jaime; Merabet, Lotfi B.

    2014-01-01

    For profoundly blind individuals, navigating in an unfamiliar building can represent a significant challenge. We investigated the use of an audio-based, virtual environment called Audio-based Environment Simulator (AbES) that can be explored for the purposes of learning the layout of an unfamiliar, complex indoor environment. Furthermore, we compared two modes of interaction with AbES. In one group, blind participants implicitly learned the layout of a target environment while playing an exploratory, goal-directed video game. By comparison, a second group was explicitly taught the same layout following a standard route and instructions provided by a sighted facilitator. As a control, a third group interacted with AbES while playing an exploratory, goal-directed video game however, the explored environment did not correspond to the target layout. Following interaction with AbES, a series of route navigation tasks were carried out in the virtual and physical building represented in the training environment to assess the transfer of acquired spatial information. We found that participants from both modes of interaction were able to transfer the spatial knowledge gained as indexed by their successful route navigation performance. This transfer was not apparent in the control participants. Most notably, the game-based learning strategy was also associated with enhanced performance when participants were required to find alternate routes and short cuts within the target building suggesting that a ludic-based training approach may provide for a more flexible mental representation of the environment. Furthermore, outcome comparisons between early and late blind individuals suggested that greater prior visual experience did not have a significant effect on overall navigation performance following training. Finally, performance did not appear to be associated with other factors of interest such as age, gender, and verbal memory recall. We conclude that the highly interactive

  15. Virtual environments for the transfer of navigation skills in the blind: a comparison of directed instruction vs. video game based learning approaches.

    PubMed

    Connors, Erin C; Chrastil, Elizabeth R; Sánchez, Jaime; Merabet, Lotfi B

    2014-01-01

    For profoundly blind individuals, navigating in an unfamiliar building can represent a significant challenge. We investigated the use of an audio-based, virtual environment called Audio-based Environment Simulator (AbES) that can be explored for the purposes of learning the layout of an unfamiliar, complex indoor environment. Furthermore, we compared two modes of interaction with AbES. In one group, blind participants implicitly learned the layout of a target environment while playing an exploratory, goal-directed video game. By comparison, a second group was explicitly taught the same layout following a standard route and instructions provided by a sighted facilitator. As a control, a third group interacted with AbES while playing an exploratory, goal-directed video game however, the explored environment did not correspond to the target layout. Following interaction with AbES, a series of route navigation tasks were carried out in the virtual and physical building represented in the training environment to assess the transfer of acquired spatial information. We found that participants from both modes of interaction were able to transfer the spatial knowledge gained as indexed by their successful route navigation performance. This transfer was not apparent in the control participants. Most notably, the game-based learning strategy was also associated with enhanced performance when participants were required to find alternate routes and short cuts within the target building suggesting that a ludic-based training approach may provide for a more flexible mental representation of the environment. Furthermore, outcome comparisons between early and late blind individuals suggested that greater prior visual experience did not have a significant effect on overall navigation performance following training. Finally, performance did not appear to be associated with other factors of interest such as age, gender, and verbal memory recall. We conclude that the highly interactive

  16. Development and clinical application of surgical navigation system for laparoscopic hepatectomy

    NASA Astrophysics Data System (ADS)

    Hayashi, Yuichiro; Igami, Tsuyoshi; Hirose, Tomoaki; Nagino, Masato; Mori, Kensaku

    2015-03-01

    This paper describes a surgical navigation system for laparoscopic surgery and its application to laparoscopic hepatectomy. The proposed surgical navigation system presents virtual laparoscopic views using a 3D positional tracker and preoperative CT images. We use an electromagnetic tracker for obtaining positional information of a laparoscope and a forceps. The point-pair matching registration method is performed for aligning coordinate systems between the 3D positional tracker and the CT images. Virtual laparoscopic views corresponding to the laparoscope position are generated from the obtained positional information, the registration results, and the CT images using a volume rendering method. We performed surgical navigation using the proposed system during laparoscopic hepatectomy for fourteen cases. The proposed system could generate virtual laparoscopic views in synchronization with the laparoscope position during surgery.

  17. Determining Virtual Environment "Fit": The Relationship Between Navigation Style in a Virtual Field Trip, Student Self-Reported Desire to Visit the Field Trip Site in the Real World, and the Purposes of Science Education

    NASA Astrophysics Data System (ADS)

    Tutwiler, M. Shane; Lin, Ming-Chao; Chang, Chun-Yen

    2013-06-01

    In this study, a follow-up analysis of the data reported in Lin et al. (Learn Media Technol. doi: 10.1080/17439884.2011.629660, 2011), we investigated the relationship between student use of a virtual field trip (VFT) system and the probability of students reporting wanting to visit the national park site upon which the VFT was modeled, controlling for content knowledge and prior visits to the park. Students who were able to navigate the VFT in teams were more likely than their peers who had the system demonstrated by a teacher to want to visit the national park. In addition, students with higher pre-intervention content knowledge were more likely to want to visit the national park than their peers with lower pre-test scores, in both the teacher demonstration and student co-navigation conditions.

  18. Decreased functional magnetic resonance imaging activity in the hippocampus in favor of the caudate nucleus in older adults tested in a virtual navigation task.

    PubMed

    Konishi, Kyoko; Etchamendy, Nicole; Roy, Shumita; Marighetto, Aline; Rajah, Natasha; Bohbot, Véronique D

    2013-11-01

    The neuroimaging literature has shown consistent decreases in functional magnetic resonance imaging (fMRI) activity in the hippocampus of healthy older adults engaged in a navigation task. However, navigation in a virtual maze relies on spatial or response strategies known to depend on the hippocampus and caudate nucleus, respectively. Therefore, since the proportion of people using spatial strategies decreases with normal aging, we hypothesized that it was responsible for the observed decreases in fMRI activity in the hippocampus reported in the literature. The aim of this study was to examine the effects of aging on the hippocampus and caudate nucleus during navigation while taking into account individual navigational strategies. Young (N = 23) and older adults (N = 29) were tested using fMRI on the Concurrent Spatial Discrimination Learning Task, a radial task that dissociates between spatial and response strategies (in Stage 2) after participants reached criteria (in Stage 1). Success on Stage 2 requires that participants have encoded the spatial relationship between the target object and environmental landmarks, that is, the spatial strategy. While older adults required more trials, all participants reached criterion. fMRI results showed that, as a group, young adults had significant activity in the hippocampus as opposed to older adults who instead had significant activity in the caudate nucleus. Importantly, individual differences showed that the older participants who used a spatial strategy to solve the task had significant activity in the hippocampus. These findings suggest that the aging process involves a shift from using the hippocampus toward the caudate nucleus during navigation but that activity in the hippocampus is sustained in a subset of healthy older adults engaged in spatial strategies. Copyright © 2013 Wiley Periodicals, Inc.

  19. Virtual Poetry.

    ERIC Educational Resources Information Center

    Gyori, Ladislao Pablo

    1996-01-01

    Presents a manifesto proposing the creation of a new kind of poetry--virtual poetry--that exists only in electronic space and computer networks. States that this new poetry is interactive, animated, hyper-linked, and navigational. (PA)

  20. Characterizing Student Navigation in Educational Multiuser Virtual Environments: A Case Study Using Data from the River City Project

    ERIC Educational Resources Information Center

    Dukas, Georg

    2009-01-01

    Though research in emerging technologies is vital to fulfilling their incredible potential for educational applications, it is often fraught with analytic challenges related to large datasets. This thesis explores these challenges in researching multiuser virtual environments (MUVEs). In a MUVE, users assume a persona and traverse a virtual space…

  1. Characterizing Student Navigation in Educational Multiuser Virtual Environments: A Case Study Using Data from the River City Project

    ERIC Educational Resources Information Center

    Dukas, Georg

    2009-01-01

    Though research in emerging technologies is vital to fulfilling their incredible potential for educational applications, it is often fraught with analytic challenges related to large datasets. This thesis explores these challenges in researching multiuser virtual environments (MUVEs). In a MUVE, users assume a persona and traverse a virtual space…

  2. Caudate nucleus-dependent response strategies in a virtual navigation task are associated with lower basal cortisol and impaired episodic memory.

    PubMed

    Bohbot, Véronique D; Gupta, Melini; Banner, Harrison; Dahmani, Louisa

    2011-09-01

    The present research examined the relationship between endogenous glucocorticoids, navigational strategies in a virtual navigation task, and performance on standard neuropsychological assessments of memory. Healthy young adult participants (N=66, mean age: 21.7) were tested on the 4 on 8 virtual maze (4/8 VM) and standard neuropsychological tests such as the Rey-Osterrieth Complex Figure (RO) and the Rey Auditory Verbal Learning Task (RAVLT), which measure episodic memory. The 4/8 VM differentiates between navigational strategies, where participants either use a hippocampal-dependent spatial strategy by building relationships between landmarks, or a caudate nucleus-dependent stimulus-response strategy by automatizing a pattern of open and closed arms to learn the location of objects within the maze. Degree of stress was assessed by administering the Perceived Stress Scale (PSS) questionnaire. Cortisol samples were taken on two consecutive days upon waking, 30 min after waking, at 11 am, 4 pm, and 9 pm. There was a significant difference in basal levels of cortisol between spatial and response learners. Interestingly, response learners had significantly lower cortisol levels throughout the day. The two groups did not differ in terms of perceived stress as measured with the PSS questionnaire. Moreover, there was no significant correlation between PSS scores and salivary cortisol levels, indicating that the higher cortisol levels in the spatial group were not associated with greater perceived stress. In addition, participants who spontaneously used a spatial strategy performed significantly better on the RAVLT and RO. These data indicate that the cortisol levels in the spatial group may be optimal in terms of episodic memory performance whereas the cortisol levels in the response group may be associated with poorer memory. These results are suggestive of an inverted U-shaped curve describing the effects of basal levels of circulating cortisol on memory in young adults.

  3. Effect of computerized cognitive training with virtual spatial navigation task during bed rest immobilization and recovery on vascular function: A pilot study

    PubMed Central

    Goswami, Nandu; Kavcic, Voyko; Marusic, Uros; Simunic, Bostjan; Rössler, Andreas; Hinghofer-Szalkay, Helmut; Pisot, Rado

    2015-01-01

    We investigated the effects of bed rest (BR) immobilization, with and without computerized cognitive training with virtual spatial navigation task (CCT), on vascular endothelium on older subjects. The effects of 14-day BR immobilization in healthy older males (n=16) of ages 53–65 years on endothelial function were studied using EndoPAT®, a noninvasive and user-independent method. From the group of 16 older men, 8 randomly received CCT during the BR, using virtual navigation tasks in a virtual environment with joystick device. In all the cases, EndoPAT assessments were done at pre- and post-BR immobilization as well as following 28 days of ambulatory recovery. The EndoPAT index increased from 1.53±0.09 (mean ± standard error of the mean) at baseline to 1.61±0.16 following immobilization (P=0.62) in the group with CCT. The EndoPAT index decreased from 2.06±0.13 (mean ± standard error of the mean) at baseline to 1.70±0.09 at the last day of BR study, day 14 (BR14) (P=0.09) in the control group. Additionally, there were no statistically significant differences between BR14 and at 28 days of follow-up (rehabilitation program) (R28). Our results show a trend of immobilization in older persons affecting the vasoconstrictory endothelial response. As the control subjects had a greater increase in EndoPAT index after R28 (+0.018) compared to subjects who had cognitive training (+0.11) (calculated from the first day of BR study), it is possible that cognitive training during BR does not improve endothelial function but rather contributes to slowing down the impairment of endothelial function. Finally, our results also show that EndoPAT may be a useful noninvasive tool to assess the vascular reactivity. PMID:25709419

  4. Soft tissue navigation for laparoscopic prostatectomy: evaluation of camera pose estimation for enhanced visualization

    NASA Astrophysics Data System (ADS)

    Baumhauer, M.; Simpfendörfer, T.; Schwarz, R.; Seitel, M.; Müller-Stich, B. P.; Gutt, C. N.; Rassweiler, J.; Meinzer, H.-P.; Wolf, I.

    2007-03-01

    We introduce a novel navigation system to support minimally invasive prostate surgery. The system utilizes transrectal ultrasonography (TRUS) and needle-shaped navigation aids to visualize hidden structures via Augmented Reality. During the intervention, the navigation aids are segmented once from a 3D TRUS dataset and subsequently tracked by the endoscope camera. Camera Pose Estimation methods directly determine position and orientation of the camera in relation to the navigation aids. Accordingly, our system does not require any external tracking device for registration of endoscope camera and ultrasonography probe. In addition to a preoperative planning step in which the navigation targets are defined, the procedure consists of two main steps which are carried out during the intervention: First, the preoperatively prepared planning data is registered with an intraoperatively acquired 3D TRUS dataset and the segmented navigation aids. Second, the navigation aids are continuously tracked by the endoscope camera. The camera's pose can thereby be derived and relevant medical structures can be superimposed on the video image. This paper focuses on the latter step. We have implemented several promising real-time algorithms and incorporated them into the Open Source Toolkit MITK (www.mitk.org). Furthermore, we have evaluated them for minimally invasive surgery (MIS) navigation scenarios. For this purpose, a virtual evaluation environment has been developed, which allows for the simulation of navigation targets and navigation aids, including their measurement errors. Besides evaluating the accuracy of the computed pose, we have analyzed the impact of an inaccurate pose and the resulting displacement of navigation targets in Augmented Reality.

  5. Accuracy of Dynamic Navigation for Dental Implant Placement-Model-Based Evaluation.

    PubMed

    Emery, Robert W; Merritt, Scott A; Lank, Kathryn; Gibbs, Jason D

    2016-10-01

    The purpose of this model-based study was to determine the accuracy of placing dental implants using a new dynamic navigation system. This investigation focuses on measurements of overall accuracy for implant placement relative to the virtual plan in both dentate and edentulous models, and provides a comparison with a meta-analysis of values reported in the literature for comparable static guidance, dynamic guidance, and freehand placement studies. This study involves 1 surgeon experienced with dynamic navigation placing implants in models under clinical simulation using a dynamic navigation system (X-Guide, X-Nav Technologies, LLC, Lansdale, Pa) based on optical triangulation tracking. Virtual implants were placed into planned sites using the navigation system computer. Post-implant placement cone-beam scans were taken. These scans were mesh overlaid with the virtual plan and used to determine deviations from the virtual plan. The primary outcome variables were platform and angular deviations comparing the actual placement to the virtual plan. The angular accuracy of implants delivered using the tested device was 0.89° ± 0.35° for dentate case types and 1.26° ± 0.66° for edentulous case types, measured relative to the preoperative implant plan. Three-dimensional positional accuracy was 0.38 ± 0.21 mm for dentate and 0.56 ± 0.17 mm for edentulous, measured from the implant apex.

  6. [Surgical reconstruction of posttraumatic defects and deformities of the orbit using frameless navigation].

    PubMed

    Davydov, D V; Levchenko, O V; Mikhaĭliukov, V M

    2014-01-01

    To explore the possibilities of frameless navigation surgery in patients with posttraumatic defects and deformities of the orbit. In order to develop frameless navigation technique for surgical treatment of posttraumatic defects and deformities of the orbit, examination and surgery were performed on 21 patients of the N.V. Sklifosovsky Research Institute of Emergency Medicine. Multi-slice spiral computed tomography was used for preoperative simulation and intraoperative control. Virtual layer-by-layer reconstruction of missing bone fragments and modeling of anatomical position of dislocated bone fragments in frontal, axial, and sagittal images were performed. Implant position control was done with pointer device of the navigation system. Good functional (disappearance of diplopia in primary position of gaze) and cosmetic results were obtained in all patients. None developed complications in the postoperative period. The use of frameless navigation in surgical treatment of posttraumatic defects and deformities of the orbit allows to obtain good and stable functional and cosmetic results.

  7. Navigation of a virtual exercise environment with Microsoft Kinect by people post-stroke or with cerebral palsy.

    PubMed

    Pool, Sean M; Hoyle, John M; Malone, Laurie A; Cooper, Lloyd; Bickel, C Scott; McGwin, Gerald; Rimmer, James H; Eberhardt, Alan W

    2016-04-08

    One approach to encourage and facilitate exercise is through interaction with virtual environments. The present study assessed the utility of Microsoft Kinect as an interface for choosing between multiple routes within a virtual environment through body gestures and voice commands. The approach was successfully tested on 12 individuals post-stroke and 15 individuals with cerebral palsy (CP). Participants rated their perception of difficulty in completing each gesture using a 5-point Likert scale questionnaire. The "most viable" gestures were defined as those with average success rates of 90% or higher and perception of difficulty ranging between easy and very easy. For those with CP, hand raises, hand extensions, and head nod gestures were found most viable. For those post-stroke, the most viable gestures were torso twists, head nods, as well as hand raises and hand extensions using the less impaired hand. Voice commands containing two syllables were viable (>85% successful) for those post-stroke; however, participants with CP were unable to complete any voice commands with a high success rate. This study demonstrated that Kinect may be useful for persons with mobility impairments to interface with virtual exercise environments, but the effectiveness of the various gestures depends upon the disability of the user.

  8. NewVision: a program for interactive navigation and analysis of multiple 3-D data sets using coordinated virtual cameras.

    PubMed

    Pixton, J L; Belmont, A S

    1996-01-01

    We describe "NewVision", a program designed for rapid interactive display, sectioning, and comparison of multiple large three-dimensional (3-D) reconstructions. User tools for navigating within large 3-D data sets and selecting local subvolumes for display, combined with view caching, fast integer interpolation, and background tasking, provide highly interactive viewing of arbitrarily sized data sets on Silicon Graphics systems ranging from simple workstations to supercomputers. Multiple windows, each showing different views of the same 3-D data set, are coordinated through mapping of local coordinate systems to a single global world coordinate system. Mapping to a world coordinate system allows quantitative measurements from any open window as well as creation of linked windows in which operations such as panning, zooming, and 3-D rotations of the viewing perspective in any one window are mirrored by corresponding transformations in the views shown in other linked windows. The specific example of tracing 3-D fiber trajectories is used to demonstrate the potential of the linked window concept. A global overview of NewVision's design and organization is provided, and future development directions are briefly discussed.

  9. Feasibility of Intraoperative Navigation for Liver Resection Using Real-time Virtual Sonography With Novel Automatic Registration System.

    PubMed

    Takamoto, Takeshi; Mise, Yoshihiro; Satou, Shouichi; Kobayashi, Yuta; Miura, Koui; Saiura, Akio; Hasegawa, Kiyoshi; Kokudo, Norihiro; Makuuchi, Masatoshi

    2017-09-06

    The clinical feasibility and usability of intraoperative ultrasonography (IOUS) tracked by computed tomography (CT) images have been proposed; however, it requires technically demanding manual registration procedure. A prospective study using real-time virtual sonography (RVS) with novel automatic registration system was conducted in four high-volume centers of liver resection from 2015 to 2016. The requiring time for registration of IOUS and CT images and positional error of confluence of middle hepatic venous tributaries (V8-MHV, V5-MHV) were measured in patients undergoing laparotomy. Automatic registration was successful in 43 of 52 enrolled patients (83%), with error ranges of 11.4 (3.1-69.4) mm for V8-MHV and 16.2 (4.3-66.8) mm for V5-MHV. Time required for total registration process was 36 (27-74) s. The RVS with novel automatic registration system can provide quick and easy registration and acceptable accuracy, which can promote the usage of IOUS.

  10. Putting 3D modelling and 3D printing into practice: virtual surgery and preoperative planning to reconstruct complex post-traumatic skeletal deformities and defects

    PubMed Central

    Tetsworth, Kevin; Block, Steve; Glatt, Vaida

    2017-01-01

    3D printing technology has revolutionized and gradually transformed manufacturing across a broad spectrum of industries, including healthcare. Nowhere is this more apparent than in orthopaedics with many surgeons already incorporating aspects of 3D modelling and virtual procedures into their routine clinical practice. As a more extreme application, patient-specific 3D printed titanium truss cages represent a novel approach for managing the challenge of segmental bone defects. This review illustrates the potential indications of this innovative technique using 3D printed titanium truss cages in conjunction with the Masquelet technique. These implants are custom designed during a virtual surgical planning session with the combined input of an orthopaedic surgeon, an orthopaedic engineering professional and a biomedical design engineer. The ability to 3D model an identical replica of the original intact bone in a virtual procedure is of vital importance when attempting to precisely reconstruct normal anatomy during the actual procedure. Additionally, other important factors must be considered during the planning procedure, such as the three-dimensional configuration of the implant. Meticulous design is necessary to allow for successful implantation through the planned surgical exposure, while being aware of the constraints imposed by local anatomy and prior implants. This review will attempt to synthesize the current state of the art as well as discuss our personal experience using this promising technique. It will address implant design considerations including the mechanical, anatomical and functional aspects unique to each case. PMID:28220752

  11. Putting 3D modelling and 3D printing into practice: virtual surgery and preoperative planning to reconstruct complex post-traumatic skeletal deformities and defects.

    PubMed

    Tetsworth, Kevin; Block, Steve; Glatt, Vaida

    2017-01-01

    3D printing technology has revolutionized and gradually transformed manufacturing across a broad spectrum of industries, including healthcare. Nowhere is this more apparent than in orthopaedics with many surgeons already incorporating aspects of 3D modelling and virtual procedures into their routine clinical practice. As a more extreme application, patient-specific 3D printed titanium truss cages represent a novel approach for managing the challenge of segmental bone defects. This review illustrates the potential indications of this innovative technique using 3D printed titanium truss cages in conjunction with the Masquelet technique. These implants are custom designed during a virtual surgical planning session with the combined input of an orthopaedic surgeon, an orthopaedic engineering professional and a biomedical design engineer. The ability to 3D model an identical replica of the original intact bone in a virtual procedure is of vital importance when attempting to precisely reconstruct normal anatomy during the actual procedure. Additionally, other important factors must be considered during the planning procedure, such as the three-dimensional configuration of the implant. Meticulous design is necessary to allow for successful implantation through the planned surgical exposure, while being aware of the constraints imposed by local anatomy and prior implants. This review will attempt to synthesize the current state of the art as well as discuss our personal experience using this promising technique. It will address implant design considerations including the mechanical, anatomical and functional aspects unique to each case.

  12. A new visualization method for navigated bronchoscopy.

    PubMed

    Reynisson, Pall Jens; Hofstad, Erlend Fagertun; Leira, Håkon Olav; Askeland, Christian; Langø, Thomas; Sorger, Hanne; Lindseth, Frank; Amundsen, Tore; Hernes, Toril Anita Nagelhus

    2017-05-30

    In flexible endoscopy techniques, such as bronchoscopy, there is often a challenge visualizing the path from start to target based on preoperative data and accessing these during the procedure. An example of this is visualizing only the inside of central airways in bronchoscopy. Virtual bronchoscopy (VB) does not meet the pulmonologist's need to detect, define and sample the frequent targets outside the bronchial wall. Our aim was to develop and study a new visualization technique for navigated bronchoscopy. We extracted the shortest possible path from the top of the trachea to the target along the airway centerline and a corresponding auxiliary route in the opposite lung. A surface structure between the centerlines was developed and displayed. The new technique was tested on non-selective CT data from eight patients using artificial lung targets. The new display technique anchored to centerline curved surface (ACCuSurf) made it easy to detect and interpret anatomical features, targets and neighboring anatomy outside the airways, in all eight patients. ACCuSurf can simplify planning and performing navigated bronchoscopy, meets the challenge of improving orientation and register the direction of the moving endoscope, thus creating an optimal visualization for navigated bronchoscopy.

  13. Preoperative planning with magnetic resonance imaging and computerized volume rendering in twin-to-twin transfusion syndrome.

    PubMed

    Luks, F I; Carr, S R; Ponte, B; Rogg, J M; Tracy, T F

    2001-07-01

    Our purpose was to illustrate the feasibility of preoperative planning with magnetic resonance imaging, 3-dimensional reconstruction, and volume-rendering techniques in twin-to-twin transfusion syndrome treated by endoscopic laser ablation of communicating vessels. After ultrasonographic determination of the syndrome and the indications for intervention, 2 patients with an anterior placenta underwent magnetic resonance imaging without the need for maternal or fetal sedation. Raw image data were downloaded into a desktop computer and manipulated with 3-dimensional reconstruction, volume rendering, and surgical navigation software. In both patients a virtual rendering of the fetuses, placenta, and uterus could be manipulated to expose all sides, demonstrate the location of the intertwin membrane, and plan the point of entry and curve of the endoscopic instruments. Preoperative planning and virtual surgical navigation in fetal surgery are now possible, as a result of shorter magnetic resonance imaging acquisition times and volume-rendering software. In this manner an entire virtual endoscopic fetal operation can be performed and fine-tuned before the actual procedure is to take place.

  14. Virtual Reality and Augmented Reality in Plastic Surgery: A Review.

    PubMed

    Kim, Youngjun; Kim, Hannah; Kim, Yong Oock

    2017-05-01

    Recently, virtual reality (VR) and augmented reality (AR) have received increasing attention, with the development of VR/AR devices such as head-mounted displays, haptic devices, and AR glasses. Medicine is considered to be one of the most effective applications of VR/AR. In this article, we describe a systematic literature review conducted to investigate the state-of-the-art VR/AR technology relevant to plastic surgery. The 35 studies that were ultimately selected were categorized into 3 representative topics: VR/AR-based preoperative planning, navigation, and training. In addition, future trends of VR/AR technology associated with plastic surgery and related fields are discussed.

  15. Virtual Satellite

    NASA Technical Reports Server (NTRS)

    Hammrs, Stephan R.

    2008-01-01

    Virtual Satellite (VirtualSat) is a computer program that creates an environment that facilitates the development, verification, and validation of flight software for a single spacecraft or for multiple spacecraft flying in formation. In this environment, enhanced functionality and autonomy of navigation, guidance, and control systems of a spacecraft are provided by a virtual satellite that is, a computational model that simulates the dynamic behavior of the spacecraft. Within this environment, it is possible to execute any associated software, the development of which could benefit from knowledge of, and possible interaction (typically, exchange of data) with, the virtual satellite. Examples of associated software include programs for simulating spacecraft power and thermal- management systems. This environment is independent of the flight hardware that will eventually host the flight software, making it possible to develop the software simultaneously with, or even before, the hardware is delivered. Optionally, by use of interfaces included in VirtualSat, hardware can be used instead of simulated. The flight software, coded in the C or C++ programming language, is compilable and loadable into VirtualSat without any special modifications. Thus, VirtualSat can serve as a relatively inexpensive software test-bed for development test, integration, and post-launch maintenance of spacecraft flight software.

  16. Recent advances in 3D computed tomography techniques for simulation and navigation in hepatobiliary pancreatic surgery.

    PubMed

    Uchida, Masafumi

    2014-04-01

    A few years ago it could take several hours to complete a 3D image using a 3D workstation. Thanks to advances in computer science, obtaining results of interest now requires only a few minutes. Many recent 3D workstations or multimedia computers are equipped with onboard 3D virtual patient modeling software, which enables patient-specific preoperative assessment and virtual planning, navigation, and tool positioning. Although medical 3D imaging can now be conducted using various modalities, including computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasonography (US) among others, the highest quality images are obtained using CT data, and CT images are now the most commonly used source of data for 3D simulation and navigation image. If the 2D source image is bad, no amount of 3D image manipulation in software will provide a quality 3D image. In this exhibition, the recent advances in CT imaging technique and 3D visualization of the hepatobiliary and pancreatic abnormalities are featured, including scan and image reconstruction technique, contrast-enhanced techniques, new application of advanced CT scan techniques, and new virtual reality simulation and navigation imaging.

  17. The use of virtual reality for the functional simulation of hepatic tumors (case control study).

    PubMed

    Chen, Gang; Li, Xue-cheng; Wu, Guo-qing; Wang, Yi; Fang, Bin; Xiong, Xiao-feng; Yang, Ri-gao; Tan, Li-wen; Zhang, Shao-xiang; Dong, Jia-hong

    2010-01-01

    To develop a technique for converting computed tomography (CT) data into a fully three-dimensional (3D) virtual reality (VR) environment. Preoperative simulation in 3D VR facilitates liver resection owing to the ability to view the tumor and its relative vessels. 3D-reconstruction of the liver was restored from spiral CT data by using LiVirtue software and the Dextrobeam (Volume Interactions Pte Ltd, Singapore) was applied to view this 3D model in the VR environment. In order to design a rational plan of operation, the liver and its anatomic structure were reconstructed to illuminate the location of the tumor and its related vessels. In our series of 38 hepatic resections, there was no significant difference between preoperatively calculated volumes of virtual resection part and actual volumes of resected specimen's weight. The LiVirtue can provide accurate and rapid results of individual hepatic volume and the character of anatomy structures. These models can be viewed and manipulated in the VR environment and on a personal computer. This preoperative simulation allowed surgeons to dissect the liver with reduced complications. Preoperative planning and intra-operative navigation based on this technique ensured the safety of liver resection. 3D models of the liver and its detailed structure articulate the possibility of intricate liver resection and the risk of the operation. This preoperative estimation from a 3D model of the liver benefits complicated liver resections greatly. Copyright 2009 Surgical Associates Ltd. All rights reserved.

  18. Patient-specific instrument can achieve same accuracy with less resection time than navigation assistance in periacetabular pelvic tumor surgery: a cadaveric study.

    PubMed

    Wong, Kwok-Chuen; Sze, Kwan-Yik; Wong, Irene Oi-Ling; Wong, Chung-Ming; Kumta, Shekhar-Madhukar

    2016-02-01

    Inaccurate resection in pelvic tumors can result in compromised margins with increase local recurrence. Navigation-assisted and patient-specific instrument (PSI) techniques have recently been reported in assisting pelvic tumor surgery with the tendency of improving surgical accuracy. We examined and compared the accuracy of transferring a virtual pelvic resection plan to actual surgery using navigation-assisted or PSI technique in a cadaver study. We performed CT scan in twelve cadaveric bodies including whole pelvic bones. Either supraacetabular or partial acetabular resection was virtually planned in a hemipelvis using engineering software. The virtual resection plan was transferred to a CT-based navigation system or was used for design and fabrication of PSI. Pelvic resections were performed using navigation assistance in six cadavers and PSI in another six. Post-resection images were co-registered with preoperative planning for comparative analysis of resection accuracy in the two techniques. The mean average deviation error from the planned resection was no different ([Formula: see text]) for the navigation and the PSI groups: 1.9 versus 1.4 mm, respectively. The mean time required for the bone resection was greater ([Formula: see text]) for the navigation group than for the PSI group: 16.2 versus 1.1 min, respectively. In simulated periacetabular pelvic tumor resections, PSI technique enabled surgeons to reproduce the virtual surgical plan with similar accuracy but with less bone resection time when compared with navigation assistance. Further studies are required to investigate the clinical benefits of PSI technique in pelvic tumor surgery.

  19. Application of surgical navigation in styloidectomy for treating Eagle's syndrome.

    PubMed

    Dou, Geng; Zhang, Yu; Zong, Chunlin; Chen, Yuanli; Guo, Yuxuan; Tian, Lei

    2016-01-01

    The present study aimed to evaluate the feasibility, accuracy, and clinical effect of intraoperative navigation for resection of elongated styloid process (ESP) in Eagle's syndrome. Twelve patients with Eagle's syndrome with clinically and radiologically established diagnoses of ESP were included in this study. Preoperatively, all patients accepted three-dimensional computed tomography scan, and their skulls' digital imaging and communications in medicine data were inputed into the navigation system workstation to make a virtual surgical plan in advance. During surgery, the intraoperative navigation was performed to excise the ESP accurately for both intraoral (without tonsillectomy) and extraoral approaches following the virtual plan. Postoperatively, the amount of bleeding, duration of operation and hospitalization, and the length of resected styloid process (SP) were measured and compared with those cases that had traditional styloidectomy without the help of surgical navigation (SN). A simple visual analog scale questionnaire was also used to assess patients' satisfaction and the surgery effect after 3 months. In total, 17 SPs from 12 patients were precisely resected by intraoral parapharyngeal approach and small cervical approach with the aid of SN. No severe complications occurred in any patients. The length of resected SPs was 21.93±14.26 mm. The average amount of bleeding and duration of operation were 22.50±8.54 mL and 40.35±11.81 minutes, respectively, which were all less than with traditional styloidectomy. The visual analog scale analysis showed that the discomfort in all patients was relieved, while ten patients' symptoms were improved greatly, and two patients had some improvement. The higher accuracy of surgery, lesser amount of bleeding, decreased duration of surgery and hospitalization, absence of complications, and improved subjective symptoms indicated that SN is an effective and minimally invasive surgical procedure suitable for resection of

  20. Enhancing Navigation Skills through Audio Gaming.

    PubMed

    Sánchez, Jaime; Sáenz, Mauricio; Pascual-Leone, Alvaro; Merabet, Lotfi

    2010-01-01

    We present the design, development and initial cognitive evaluation of an Audio-based Environment Simulator (AbES). This software allows a blind user to navigate through a virtual representation of a real space for the purposes of training orientation and mobility skills. Our findings indicate that users feel satisfied and self-confident when interacting with the audio-based interface, and the embedded sounds allow them to correctly orient themselves and navigate within the virtual world. Furthermore, users are able to transfer spatial information acquired through virtual interactions into real world navigation and problem solving tasks.

  1. Enhancing Navigation Skills through Audio Gaming

    PubMed Central

    Sánchez, Jaime; Sáenz, Mauricio; Pascual-Leone, Alvaro; Merabet, Lotfi

    2014-01-01

    We present the design, development and initial cognitive evaluation of an Audio-based Environment Simulator (AbES). This software allows a blind user to navigate through a virtual representation of a real space for the purposes of training orientation and mobility skills. Our findings indicate that users feel satisfied and self-confident when interacting with the audio-based interface, and the embedded sounds allow them to correctly orient themselves and navigate within the virtual world. Furthermore, users are able to transfer spatial information acquired through virtual interactions into real world navigation and problem solving tasks. PMID:25505796

  2. Update on three-dimensional image reconstruction for preoperative simulation in thoracic surgery

    PubMed Central

    Chen-Yoshikawa, Toyofumi F.

    2016-01-01

    Background Three-dimensional computed tomography (3D-CT) technologies have been developed and refined over time. Recently, high-speed and high-quality 3D-CT technologies have also been introduced to the field of thoracic surgery. The purpose of this manuscript is to demonstrate several examples of these 3D-CT technologies in various scenarios in thoracic surgery. Methods A newly-developed high-speed and high-quality 3D image analysis software system was used in Kyoto University Hospital. Simulation and/or navigation were performed using this 3D-CT technology in various thoracic surgeries. Results Preoperative 3D-CT simulation was performed in most patients undergoing video-assisted thoracoscopic surgery (VATS). Anatomical variation was frequently detected preoperatively, which was useful in performing VATS procedures when using only a monitor for vision. In sublobar resection, 3D-CT simulation was more helpful. In small lung lesions, which were supposedly neither visible nor palpable, preoperative marking of the lesions was performed using 3D-CT simulation, and wedge resection or segmentectomy was successfully performed with confidence. This technique also enabled virtual-reality endobronchial ultrasonography (EBUS), which made the procedure more safe and reliable. Furthermore, in living-donor lobar lung transplantation (LDLLT), surgical procedures for donor lobectomy were simulated preoperatively by 3D-CT angiography, which also affected surgical procedures for recipient surgery. New surgical techniques such as right and left inverted LDLLT were also established using 3D models created with this technique. Conclusions After the introduction of 3D-CT technology to the field of thoracic surgery, preoperative simulation has been developed for various thoracic procedures. In the near future, this technique will become more common in thoracic surgery, and frequent use by thoracic surgeons will be seen in worldwide daily practice. PMID:27014477

  3. AUTOMATIC NAVIGATION.

    DTIC Science & Technology

    NAVIGATION, REPORTS), (*CONTROL SYSTEMS, *INFORMATION THEORY), ABSTRACTS, OPTIMIZATION, DYNAMIC PROGRAMMING, GAME THEORY, NONLINEAR SYSTEMS, CORRELATION TECHNIQUES, FOURIER ANALYSIS, INTEGRAL TRANSFORMS, DEMODULATION, NAVIGATION CHARTS, PATTERN RECOGNITION, DISTRIBUTION THEORY , TIME SHARING, GRAPHICS, DIGITAL COMPUTERS, FEEDBACK, STABILITY

  4. What Is the Expected Learning Curve in Computer-assisted Navigation for Bone Tumor Resection?

    PubMed

    Farfalli, Germán L; Albergo, José I; Ritacco, Lucas E; Ayerza, Miguel A; Milano, Federico E; Aponte-Tinao, Luis A

    2017-03-01

    Computer navigation during surgery can help oncologic surgeons perform more accurate resections. However, some navigation studies suggest that this tool may result in unique intraoperative problems and increased surgical time. The degree to which these problems might diminish with experience-the learning curve-has not, to our knowledge, been evaluated for navigation-assisted tumor resections. (1) What intraoperative technical problems were observed during the first 2 years using navigation? (2) What was the mean time for navigation procedures and the time improvement during the learning curve? (3) Have there been any differences in the accuracy of the registration technique that occurred over time? (4) Did navigation achieve the goal of achieving a wide bone margin? All patients who underwent preoperative virtual planning for tumor bone resections and operated on with navigation assistance from 2010 to 2012 were prospectively collected. Two surgeons (GLF, LAA-T) performed the intraoperative navigation assistance. Both surgeons had more than 5 years of experience in orthopaedic oncology with more than 60 oncology cases per year per surgeon. This study includes from the very first patients performed with navigation. Although they did not take any formal training in orthopaedic oncology navigation, both surgeons were trained in navigation for knee prostheses. Between 2010 and 2012, we performed 124 bone tumor resections; of these, 78 (63%) cases were resected using intraoperative navigation assistance. During this period, our general indications for use of navigation included pelvic and sacral tumors and those tumors that were reconstructed with massive bone allografts to obtain precise matching of the host and allograft osteotomies. Seventy-eight patients treated with this technology were included in the study. Technical problems (crashes) and time for the navigation procedure were reported after surgery. Accuracy of the registration technique was defined and the

  5. Determining Virtual Environment "Fit": The Relationship between Navigation Style in a Virtual Field Trip, Student Self-Reported Desire to Visit the Field Trip Site in the Real World, and the Purposes of Science Education

    ERIC Educational Resources Information Center

    Tutwiler, M. Shane; Lin, Ming-Chao; Chang, Chun-Yen

    2013-01-01

    In this study, a follow-up analysis of the data reported in Lin et al. ("Learn Media Technol." doi: 10.1080/17439884.2011.629660 , 2011), we investigated the relationship between student use of a virtual field trip (VFT) system and the probability of students reporting wanting to visit the national park site upon which the VFT was modeled,…

  6. Determining Virtual Environment "Fit": The Relationship between Navigation Style in a Virtual Field Trip, Student Self-Reported Desire to Visit the Field Trip Site in the Real World, and the Purposes of Science Education

    ERIC Educational Resources Information Center

    Tutwiler, M. Shane; Lin, Ming-Chao; Chang, Chun-Yen

    2013-01-01

    In this study, a follow-up analysis of the data reported in Lin et al. ("Learn Media Technol." doi: 10.1080/17439884.2011.629660 , 2011), we investigated the relationship between student use of a virtual field trip (VFT) system and the probability of students reporting wanting to visit the national park site upon which the VFT was modeled,…

  7. Inertial Navigation

    DTIC Science & Technology

    also been well-known for some time. However, inertial navigation systems (called inertial guidance systems in rocket technology) which are composed of... navigation technology has developed rapidly, and the precision of inertial navigation has increased greatly. In 1944, the ’V-2’ rocket made the first...gyroscopes, accelerometers, and electronic computers have only been on the market for a little over twenty years. In the past twenty years, inertial

  8. [Application of computer navigation system in the treatment of post-traumatic reconstruction].

    PubMed

    Liu, Xiao-Jing; He, Yang; Gong, Xi; An, Jin-Gang; Guo, Chuan-Bin; Zhang, Yi

    2012-11-01

    To investigate the value of computer aided navigation system (CANS) in the treatment of post traumatic maxillofacial deformation. Fifty-four patients (M = 37, F = 17) were included in the study, including 31 cases of zygomatic fracture, 7 cases of pure orbital fracture, 11 cases of temporal mandibular joint ankylosis, 1 case of foreign body and 4 cases of defect reconstruction with custom implant. Data acquisition was done through CT scan, and DICOM data was transferred into workstation. Computer assisted design, including osteotomy, reposition, fibula flap design, orbital implant construction was performed using Surgicase CMF and Brain Lab Iplan system. The virtual design was transferred to Brain Lab navigation system, and the osteotomy, reduction, location of bone graft and custom implant were guided by navigation. Postoperative CT scan was required 48 - 72 hours after surgery. Preoperative and postoperative CT images were superimposed automatically in BrainLab Iplan system, and compared both in 3D objects and 2D slices. All the cases achieved good results without serious complication. The error of important corresponding points in zygomatic fracture reduction, orbital reconstruction and defect reconstruction was 0.2 - 3.5 mm, 0.8 - 2.0 mm and 0.2 - 2.2 mm respectively. Computer assisted design is of considerable value for the systematic and accurate planning for complicated post traumatic deformation. Virtual plan could be carried out accurately with the assistance of CANS.

  9. Three-dimensional surgical simulation-guided navigation in thoracic surgery: a new approach to improve results in chest wall resection and reconstruction for malignant diseases

    PubMed Central

    Stella, Franco; Dolci, Giampiero; Dell’Amore, Andrea; Badiali, Giovanni; De Matteis, Massimo; Asadi, Nizar; Marchetti, Claudio; Bini, Alessandro

    2014-01-01

    OBJECTIVES Oncological surgery of the chest wall should be performed to achieve free margins of at least 2 cm for metastasis or 4 cm for primary tumours. When the lesion is not visible or palpable, difficulty in identification may lead to a larger incision and a resection wider than is necessary. METHODS We report three cases of non-palpable metastatic chest wall lesions in which the preoperative surgical planning and the intraoperative identification of the tumour, and thus the subsequent chest wall reconstruction, was supported using computer-based surgery. RESULTS The application of high-resolution three-dimensional imaging technology and navigational systems is used in preoperative surgical planning to provide virtual simulations of a patient's skeletal changes and new soft tissue profile. Intraoperatively, a mobile navigation probe was used to identify the lesion, matching surgical landmarks and the preoperative computed tomography imaging, achieving the radical resection of the tumour with correct but not excessive surgical margins. Two patients underwent partial sternectomy followed by sternal allograft reconstruction. The third patient underwent chest wall resection followed by reconstruction using titanium bars and vicryl mesh. In all cases, the postoperative period was uneventful. After a follow-up period of 13.9 and 8 months, respectively, all patients are disease free, without complications. CONCLUSIONS Application of navigation technology in thoracic surgery should be encouraged because it is easy to use and requires a limited learning curve. PMID:24144806

  10. Micro Navigator

    NASA Technical Reports Server (NTRS)

    Blaes, B. R.; Kia, T.; Chau, S. N.

    2001-01-01

    Miniature high-performance low-mass space avionics systems are desired for planned future outer planetary exploration missions (i.e. Europa Orbiter/Lander, Pluto-Kuiper Express). The spacecraft fuel and mass requirements enabling orbit insertion is the driving requirement. The Micro Navigator is an integrated autonomous Guidance, Navigation & Control (GN&C)micro-system that would provide the critical avionics function for navigation, pointing, and precision landing. The Micro Navigator hardware and software allow fusion of data from multiple sensors to provide a single integrated vehicle state vector necessary for six degrees of freedom GN&C. The benefits of this MicroNavigator include: 1) The Micro Navigator employs MEMS devices that promise orders of magnitude reductions in mass power and volume of inertial sensors (accelerometers and gyroscopes), celestial sensing devices (startracker, sun sensor), and computing element; 2) The highly integrated nature of the unit will reduce the cost of flight missions. a) The advanced miniaturization technologies employed by the Micro Navigator lend themselves to mass production, and therefore will reduce production cost of spacecraft. b) The integral approach simplifies interface issues associated with discrete components and reduces cost associated with integration and test of multiple components; and 3) The integration of sensors and processing elements into a single unit will allow the Micro Navigator to encapsulate attitude information and determination functions into a single object. This is particularly beneficial for object-oriented software architectures that are used in advanced spacecraft. Additional information is contained in the original extended abstract.

  11. Micro Navigator

    NASA Astrophysics Data System (ADS)

    Blaes, B. R.; Kia, T.; Chau, S. N.

    2001-01-01

    Miniature high-performance low-mass space avionics systems are desired for planned future outer planetary exploration missions (i.e. Europa Orbiter/Lander, Pluto-Kuiper Express). The spacecraft fuel and mass requirements enabling orbit insertion is the driving requirement. The Micro Navigator is an integrated autonomous Guidance, Navigation & Control (GN&C)micro-system that would provide the critical avionics function for navigation, pointing, and precision landing. The Micro Navigator hardware and software allow fusion of data from multiple sensors to provide a single integrated vehicle state vector necessary for six degrees of freedom GN&C. The benefits of this MicroNavigator include: 1) The Micro Navigator employs MEMS devices that promise orders of magnitude reductions in mass power and volume of inertial sensors (accelerometers and gyroscopes), celestial sensing devices (startracker, sun sensor), and computing element; 2) The highly integrated nature of the unit will reduce the cost of flight missions. a) The advanced miniaturization technologies employed by the Micro Navigator lend themselves to mass production, and therefore will reduce production cost of spacecraft. b) The integral approach simplifies interface issues associated with discrete components and reduces cost associated with integration and test of multiple components; and 3) The integration of sensors and processing elements into a single unit will allow the Micro Navigator to encapsulate attitude information and determination functions into a single object. This is particularly beneficial for object-oriented software architectures that are used in advanced spacecraft. Additional information is contained in the original extended abstract.

  12. PATIENT NAVIGATION

    PubMed Central

    Wells, Kristen J.; Battaglia, Tracy A.; Dudley, Donald J.; Garcia, Roland; Greene, Amanda; Calhoun, Elizabeth; Mandelblatt, Jeanne S.; Paskett, Electra D.; Raich, Peter C.

    2008-01-01

    Background First implemented in 1990, patient navigation interventions are emerging as an approach to reduce cancer disparities. However, there is lack of consensus about how patient navigation is defined, what patient navigators do, and what their qualifications should be. Little is known about the efficacy and cost effectiveness of patient navigation. Methods We conducted a qualitative synthesis of published literature on cancer patient navigation. Using the keywords “navigator” or “navigation” and “cancer,” we identified 45 articles from Pubmed and reference searches that were published or in press through October 2007. 16 provided data on efficacy of navigation in improving timeliness and receipt of cancer screening, diagnostic follow-up care, and treatment. Patient navigation services are defined and differentiated from other outreach services. Results Overall there is evidence for some degree of efficacy for patient navigation in increasing participation in cancer screening and adherence to diagnostic follow-up care following an abnormality, with increases in screening ranging from 10.8% to 17.1% and increases in adherence to diagnostic follow-up care ranging from 21% to 29.2%, when compared to control patients. There is less evidence regarding efficacy of patient navigation in reducing either late stage cancer diagnosis or delays in initiation of cancer treatment or improving outcomes during cancer survivorship. There were methodological limitations in most studies, such as lack of control groups, small sample sizes, and contamination with other interventions. Conclusions Although cancer-related patient navigation interventions are being increasingly adopted across the U.S. and Canada, further research is necessary to evaluate their efficacy and cost-effectiveness in improving cancer care. PMID:18780320

  13. Modified Navigation Instructions for Spatial Navigation Assistance Systems Lead to Incidental Spatial Learning.

    PubMed

    Gramann, Klaus; Hoepner, Paul; Karrer-Gauss, Katja

    2017-01-01

    Spatial cognitive skills deteriorate with the increasing use of automated GPS navigation and a general decrease in the ability to orient in space might have further impact on independence, autonomy, and quality of life. In the present study we investigate whether modified navigation instructions support incidental spatial knowledge acquisition. A virtual driving environment was used to examine the impact of modified navigation instructions on spatial learning while using a GPS navigation assistance system. Participants navigated through a simulated urban and suburban environment, using navigation support to reach their destination. Driving performance as well as spatial learning was thereby assessed. Three navigation instruction conditions were tested: (i) a control group that was provided with classical navigation instructions at decision points, and two other groups that received navigation instructions at decision points including either (ii) additional irrelevant information about landmarks or (iii) additional personally relevant information (i.e., individual preferences regarding food, hobbies, etc.), associated with landmarks. Driving performance revealed no differences between navigation instructions. Significant improvements were observed in both modified navigation instruction conditions on three different measures of spatial learning and memory: subsequent navigation of the initial route without navigation assistance, landmark recognition, and sketch map drawing. Future navigation assistance systems could incorporate modified instructions to promote incidental spatial learning and to foster more general spatial cognitive abilities. Such systems might extend mobility across the lifespan.

  14. Modified Navigation Instructions for Spatial Navigation Assistance Systems Lead to Incidental Spatial Learning

    PubMed Central

    Gramann, Klaus; Hoepner, Paul; Karrer-Gauss, Katja

    2017-01-01

    Spatial cognitive skills deteriorate with the increasing use of automated GPS navigation and a general decrease in the ability to orient in space might have further impact on independence, autonomy, and quality of life. In the present study we investigate whether modified navigation instructions support incidental spatial knowledge acquisition. A virtual driving environment was used to examine the impact of modified navigation instructions on spatial learning while using a GPS navigation assistance system. Participants navigated through a simulated urban and suburban environment, using navigation support to reach their destination. Driving performance as well as spatial learning was thereby assessed. Three navigation instruction conditions were tested: (i) a control group that was provided with classical navigation instructions at decision points, and two other groups that received navigation instructions at decision points including either (ii) additional irrelevant information about landmarks or (iii) additional personally relevant information (i.e., individual preferences regarding food, hobbies, etc.), associated with landmarks. Driving performance revealed no differences between navigation instructions. Significant improvements were observed in both modified navigation instruction conditions on three different measures of spatial learning and memory: subsequent navigation of the initial route without navigation assistance, landmark recognition, and sketch map drawing. Future navigation assistance systems could incorporate modified instructions to promote incidental spatial learning and to foster more general spatial cognitive abilities. Such systems might extend mobility across the lifespan. PMID:28243219

  15. A pre-operative approach of range of motion simulation and verification for femoroacetabular impingement.

    PubMed

    Chang, Ta-Cheng; Kang, Hyosig; Arata, Louis; Zhao, Weizhao

    2011-09-01

    Femoroacetabular impingement (FAI) is increasingly recognized as a potential cause of hip osteoarthritis. A system capable of pre-operatively simulating hip range of motion (ROM) by given surface models from either healthy or FAI diseased bone is desirable. An impingement detection system using bounding sphere hierarchies was first developed. Both precision and accuracy of the impingement detection system were verified by a custom-designed phantom to imitate ball-and-socket hip movement. The impingement detection system was then implemented into the hip ROM simulation system to simulate the ROM of (1) healthy pelvis and femur, and (2) healthy pelvis and pathologic femur. The ROM simulation system was also verified by manipulating sawbones under the navigation of an optical tracking system. The impingement detection system achieved a distance error of 0.53 ± 0.06 mm and an angular error of 0.28 ± 0.03°. The impingement detection accuracies were 100%, 100%, and 96% in three different phantom orientations, respectively. The mean errors between simulated and verified ROM were 0.10 ± 1.39° for the 'healthy pelvis and femur' group, and - 2.38 ± 3.49° for the 'healthy pelvis and pathologic femur' group. The present study demonstrates a pre-operative approach to virtually simulate and predict the functional hip ROM based on the given bone models. The impingement detection and ROM simulation systems developed may also be used for other orthopedic applications. Copyright © 2011 John Wiley & Sons, Ltd.

  16. The indication and application of computer-assisted navigation in oral and maxillofacial surgery-Shanghai's experience based on 104 cases.

    PubMed

    Yu, Hongbo; Shen, Steve Guofang; Wang, Xudong; Zhang, Lei; Zhang, Shilei

    2013-12-01

    To explore the indication and application of computer-assisted navigation in oral and maxillofacial surgery. One hundred and four patients including 34 zygomatic-orbital-maxillary fractures, 27 unilateral TMJ ankylosis, 29 craniofacial fibrous dysplasia, 9 mandibular angle hypertrophia, 3 cartilage/bone tumours of jaw and 2 cases with facial foreign bodies were enrolled in this study. CT scans were performed and data was saved in DICOM (digital imaging and communications in medicine) format. The osteotomy lines, amount and range of resection, the reduction position of bony segments and the reconstruction morphology was determined and displayed by preoperative simulation with mirroring and superimposing procedures. All operations were performed under the guidance of navigation system. The accuracy of navigation was evaluated by comparing the postoperative CT 3-D model with preoperative surgical planning. Through registration, an accurate match between the intraoperative anatomy and the CT images was achieved. The systematic error checked by computer was within 1 mm. All operations were performed successfully with the guidance of real-time navigation. The mean error between virtual simulation and surgical results was 1.46 ± 0.24 mm. All patients healed uneventfully and function and profile was improved significantly. With the opportunity to perform preoperative planning, surgical simulation and postoperative prediction, computer-assisted navigation shows great value in improving the accuracy of maxillofacial surgery, reducing operation risk and postsurgical morbidity, and restoring facial symmetry. It is regarded as a valuable technique in these potentially complicated procedures. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  17. Preliminary clinical trial in percutaneous nephrolithotomy using a real-time navigation system for percutaneous kidney access

    NASA Astrophysics Data System (ADS)

    Rodrigues, Pedro L.; Moreira, António H. J.; Rodrigues, Nuno F.; Pinho, A. C. M.; Fonseca, Jaime C.; Lima, Estevão.; Vilaça, João. L.

    2014-03-01

    Background: Precise needle puncture of renal calyces is a challenging and essential step for successful percutaneous nephrolithotomy. This work tests and evaluates, through a clinical trial, a real-time navigation system to plan and guide percutaneous kidney puncture. Methods: A novel system, entitled i3DPuncture, was developed to aid surgeons in establishing the desired puncture site and the best virtual puncture trajectory, by gathering and processing data from a tracked needle with optical passive markers. In order to navigate and superimpose the needle to a preoperative volume, the patient, 3D image data and tracker system were previously registered intraoperatively using seven points that were strategically chosen based on rigid bone structures and nearby kidney area. In addition, relevant anatomical structures for surgical navigation were automatically segmented using a multi-organ segmentation algorithm that clusters volumes based on statistical properties and minimum description length criterion. For each cluster, a rendering transfer function enhanced the visualization of different organs and surrounding tissues. Results: One puncture attempt was sufficient to achieve a successful kidney puncture. The puncture took 265 seconds, and 32 seconds were necessary to plan the puncture trajectory. The virtual puncture path was followed correctively until the needle tip reached the desired kidney calyceal. Conclusions: This new solution provided spatial information regarding the needle inside the body and the possibility to visualize surrounding organs. It may offer a promising and innovative solution for percutaneous punctures.

  18. Application of surgical navigation in styloidectomy for treating Eagle’s syndrome

    PubMed Central

    Dou, Geng; Zhang, Yu; Zong, Chunlin; Chen, Yuanli; Guo, Yuxuan; Tian, Lei

    2016-01-01

    Purpose The present study aimed to evaluate the feasibility, accuracy, and clinical effect of intraoperative navigation for resection of elongated styloid process (ESP) in Eagle’s syndrome. Patients and methods Twelve patients with Eagle’s syndrome with clinically and radiologically established diagnoses of ESP were included in this study. Preoperatively, all patients accepted three-dimensional computed tomography scan, and their skulls’ digital imaging and communications in medicine data were inputed into the navigation system workstation to make a virtual surgical plan in advance. During surgery, the intraoperative navigation was performed to excise the ESP accurately for both intraoral (without tonsillectomy) and extraoral approaches following the virtual plan. Postoperatively, the amount of bleeding, duration of operation and hospitalization, and the length of resected styloid process (SP) were measured and compared with those cases that had traditional styloidectomy without the help of surgical navigation (SN). A simple visual analog scale questionnaire was also used to assess patients’ satisfaction and the surgery effect after 3 months. Results In total, 17 SPs from 12 patients were precisely resected by intraoral parapharyngeal approach and small cervical approach with the aid of SN. No severe complications occurred in any patients. The length of resected SPs was 21.93±14.26 mm. The average amount of bleeding and duration of operation were 22.50±8.54 mL and 40.35±11.81 minutes, respectively, which were all less than with traditional styloidectomy. The visual analog scale analysis showed that the discomfort in all patients was relieved, while ten patients’ symptoms were improved greatly, and two patients had some improvement. Conclusion The higher accuracy of surgery, lesser amount of bleeding, decreased duration of surgery and hospitalization, absence of complications, and improved subjective symptoms indicated that SN is an effective and

  19. Virtual Reality and Augmented Reality in Plastic Surgery: A Review

    PubMed Central

    Kim, Youngjun; Kim, Hannah

    2017-01-01

    Recently, virtual reality (VR) and augmented reality (AR) have received increasing attention, with the development of VR/AR devices such as head-mounted displays, haptic devices, and AR glasses. Medicine is considered to be one of the most effective applications of VR/AR. In this article, we describe a systematic literature review conducted to investigate the state-of-the-art VR/AR technology relevant to plastic surgery. The 35 studies that were ultimately selected were categorized into 3 representative topics: VR/AR-based preoperative planning, navigation, and training. In addition, future trends of VR/AR technology associated with plastic surgery and related fields are discussed. PMID:28573091

  20. Non-photorealistic rendering of virtual implant models for computer-assisted fluoroscopy-based surgical procedures

    NASA Astrophysics Data System (ADS)

    Zheng, Guoyan

    2007-03-01

    Surgical navigation systems visualize the positions and orientations of surgical instruments and implants as graphical overlays onto a medical image of the operated anatomy on a computer monitor. The orthopaedic surgical navigation systems could be categorized according to the image modalities that are used for the visualization of surgical action. In the so-called CT-based systems or 'surgeon-defined anatomy' based systems, where a 3D volume or surface representation of the operated anatomy could be constructed from the preoperatively acquired tomographic data or through intraoperatively digitized anatomy landmarks, a photorealistic rendering of the surgical action has been identified to greatly improve usability of these navigation systems. However, this may not hold true when the virtual representation of surgical instruments and implants is superimposed onto 2D projection images in a fluoroscopy-based navigation system due to the so-called image occlusion problem. Image occlusion occurs when the field of view of the fluoroscopic image is occupied by the virtual representation of surgical implants or instruments. In these situations, the surgeon may miss part of the image details, even if transparency and/or wire-frame rendering is used. In this paper, we propose to use non-photorealistic rendering to overcome this difficulty. Laboratory testing results on foamed plastic bones during various computer-assisted fluoroscopybased surgical procedures including total hip arthroplasty and long bone fracture reduction and osteosynthesis are shown.

  1. Optical augmented reality assisted navigation system for neurosurgery teaching and planning

    NASA Astrophysics Data System (ADS)

    Wu, Hui-Qun; Geng, Xing-Yun; Wang, Li; Zhang, Yuan-Peng; Jiang, Kui; Tang, Le-Min; Zhou, Guo-Min; Dong, Jian-Cheng

    2013-07-01

    This paper proposed a convenient navigation system for neurosurgeon's pre-operative planning and teaching with augmented reality (AR) technique, which maps the three-dimensional reconstructed virtual anatomy structures onto a skull model. This system included two parts, a virtual reality system and a skull model scence. In our experiment, a 73 year old right-handed man initially diagnosed with astrocytoma was selected as an example to vertify our system. His imaging data from different modalities were registered and the skull soft tissue, brain and inside vessels as well as tumor were reconstructed. Then the reconstructed models were overlayed on the real scence. Our findings showed that the reconstructed tissues were augmented into the real scence and the registration results were in good alignment. The reconstructed brain tissue was well distributed in the skull cavity. The probe was used by a neurosurgeon to explore the surgical pathway which could be directly posed into the tumor while not injuring important vessels. In this way, the learning cost for students and patients' education about surgical risks reduced. Therefore, this system could be a selective protocol for image guided surgery(IGS), and is promising for neurosurgeon's pre-operative planning and teaching.

  2. Superiority of autostereoscopic visualization for image-guided navigation in liver surgery

    NASA Astrophysics Data System (ADS)

    Vetter, Marcus; Hassenpflug, Peter; Thorn, Matthias; Cardenas, Carlos; Grenacher, Lars; Richter, Goetz M.; Lamade, Wolfram; Herfarth, Christian; Meinzer, Hans-Peter

    2002-05-01

    A substantial component of an image-guided surgery system (IGSS) is the kind of three-dimensional (3D) presentation to the surgeon because the visual depth perception of the complex anatomy is of significant relevance for orientation. Therefore, we examined for this contribution four different visualization techniques, which were evaluated by eight surgeons. The IGSS developed by our group supports the intraoperative orientation of the surgeon by presenting a visualization of the spatially tracked surgical instruments with respect to vitally important intrahepatic vessels, the tumor, and preoperatively calculated resection planes. In the preliminary trial presented here, we examined the human ability to perceive an intraoperative virtual scene and to solve given navigation tasks. The focus of the experiments was to measure the ability of eight surgeons to orientate themselves intrahepatically and to transfer the perceived virtual spatial relations to movements in real space. With auto-stereoscopic visualization making use of a prism-based display the navigation can be performed faster and more accurate than with the other visualization techniques.

  3. A Novel Augmented Reality-Based Navigation System in Perforator Flap Transplantation - A Feasibility Study.

    PubMed

    Jiang, Taoran; Zhu, Ming; Zan, Tao; Gu, Bin; Li, Qingfeng

    2017-08-01

    In perforator flap transplantation, dissection of the perforator is an important but difficult procedure because of the high variability in vascular anatomy. Preoperative imaging techniques could provide substantial information about vascular anatomy; however, it cannot provide direct guidance for surgeons during the operation. In this study, a navigation system (NS) was established to overlie a vascular map on surgical sites to further provide a direct guide for perforator flap transplantation. The NS was established based on computed tomographic angiography and augmented reality techniques. A virtual vascular map was reconstructed according to computed tomographic angiography data and projected onto real patient images using ARToolKit software. Additionally, a screw-fixation marker holder was created to facilitate registration. With the use of a tracking and display system, we conducted the NS on an animal model and measured the system error on a rapid prototyping model. The NS assistance allowed for correct identification, as well as a safe and precise dissection of the perforator. The mean value of the system error was determined to be 3.474 ± 1.546 mm. Augmented reality-based NS can provide precise navigation information by directly displaying a 3-dimensional individual anatomical virtual model onto the operative field in real time. It will allow rapid identification and safe dissection of a perforator in free flap transplantation surgery.

  4. [Preoperative analysis in rhinoplasty].

    PubMed

    Nguyen, P S; Bardot, J; Duron, J B; Levet, Y; Aiach, G

    2014-12-01

    Preoperative analysis in rhinoplasty consists in analyzing individual anatomical and functional characteristics without losing sight of the initial requirements of the patient to which priority should be given. The examination is primarily clinical but it also uses preoperative photographs taken at specific accurate angles. Detecting functional disorders or associated general pathologies, which will reduce the risk of complications. All of these factors taken into account, the surgeon can work out a rhinoplasty plan which he or she will subsequently explain to the patient and obtain his or her approbation.

  5. The Preoperative Neurological Evaluation

    PubMed Central

    Probasco, John; Sahin, Bogachan; Tran, Tung; Chung, Tae Hwan; Rosenthal, Liana Shapiro; Mari, Zoltan; Levy, Michael

    2013-01-01

    Neurological diseases are prevalent in the general population, and the neurohospitalist has an important role to play in the preoperative planning for patients with and at risk for developing neurological disease. The neurohospitalist can provide patients and their families as well as anesthesiologists, surgeons, hospitalists, and other providers guidance in particular to the patient’s neurological disease and those he or she is at risk for. Here we present considerations and guidance for the neurohospitalist providing preoperative consultation for the neurological patient with or at risk of disturbances of consciousness, cerebrovascular and carotid disease, epilepsy, neuromuscular disease, and Parkinson disease. PMID:24198903

  6. Fully Three-Dimensional Virtual-Reality System

    NASA Technical Reports Server (NTRS)

    Beckman, Brian C.

    1994-01-01

    Proposed virtual-reality system presents visual displays to simulate free flight in three-dimensional space. System, virtual space pod, is testbed for control and navigation schemes. Unlike most virtual-reality systems, virtual space pod would not depend for orientation on ground plane, which hinders free flight in three dimensions. Space pod provides comfortable seating, convenient controls, and dynamic virtual-space images for virtual traveler. Controls include buttons plus joysticks with six degrees of freedom.

  7. Fully Three-Dimensional Virtual-Reality System

    NASA Technical Reports Server (NTRS)

    Beckman, Brian C.

    1994-01-01

    Proposed virtual-reality system presents visual displays to simulate free flight in three-dimensional space. System, virtual space pod, is testbed for control and navigation schemes. Unlike most virtual-reality systems, virtual space pod would not depend for orientation on ground plane, which hinders free flight in three dimensions. Space pod provides comfortable seating, convenient controls, and dynamic virtual-space images for virtual traveler. Controls include buttons plus joysticks with six degrees of freedom.

  8. INL Autonomous Navigation System

    SciTech Connect

    2005-03-30

    The INL Autonomous Navigation System provides instructions for autonomously navigating a robot. The system permits high-speed autonomous navigation including obstacle avoidance, waypoing navigation and path planning in both indoor and outdoor environments.

  9. Virtual Prototyping at CERN

    NASA Astrophysics Data System (ADS)

    Gennaro, Silvano De

    The VENUS (Virtual Environment Navigation in the Underground Sites) project is probably the largest Virtual Reality application to Engineering design in the world. VENUS is just over one year old and offers a fully immersive and stereoscopic "flythru" of the LHC pits for the proposed experiments, including the experimental area equipment and the surface models that are being prepared for a territorial impact study. VENUS' Virtual Prototypes are an ideal replacement for the wooden models traditionally build for the past CERN machines, as they are generated directly from the EUCLID CAD files, therefore they are totally reliable, they can be updated in a matter of minutes, and they allow designers to explore them from inside, in a one-to-one scale. Navigation can be performed on the computer screen, on a stereoscopic large projection screen, or in immersive conditions, with an helmet and 3D mouse. By using specialised collision detection software, the computer can find optimal paths to lower each detector part into the pits and position it to destination, letting us visualize the whole assembly probess. During construction, these paths can be fed to a robot controller, which can operate the bridge cranes and build LHC almost without human intervention. VENUS is currently developing a multiplatform VR browser that will let the whole HEP community access LHC's Virtual Protoypes over the web. Many interesting things took place during the conference on Virtual Reality. For more information please refer to the Virtual Reality section.

  10. [Navigation techniques in surgery of cranio-cervical junction and upper cervical spine].

    PubMed

    Suchomel, P; Hradil, J; Frölich, R; Barsa, P; Lukás, R

    2009-04-01

    Spinal navigation has substantially advanced during the past ten years. Surgeons have gained sufficient skills and confidence, and have introduced this technology to the anatomically challenging region of the upper cervical spine and craniocervical junction. The detailed evaluation of individual anatomy, rational pre-operative planning and final intraoperative control improve the safety and precision of classical surgical procedures. As methods technologically evolve, indication criteria change accordingly, but the basic principles of a relevatn choice remain; these are to reduce morbidity due to its three main causes, i.e., mechanical, neurological and vascular. We present an overview of current techniques and discuss their applicability in the region of the upper cervical spine and craniocervical junction. The systems allowing us to obtain live images intra-operatively, such as fluoroscopy or intra.operative CT, seem to be most versatile and accurate, especially when combined with traditional virtual navigation systems. Based on case histories, the authors suggest trends in the development of this field, with a focus on minimally invasive techniques. Key words: navigation, upper cervical spine, craniocervical junction.

  11. Virtual Reality and Computer-Enhanced Training Applied to Wheeled Mobility: An Overview of Work in Pittsburgh

    ERIC Educational Resources Information Center

    Cooper, Rory A.; Ding, Dan; Simpson, Richard; Fitzgerald, Shirley G.; Spaeth, Donald M.; Guo, Songfeng; Koontz, Alicia M.; Cooper, Rosemarie; Kim, Jongbae; Boninger, Michael L.

    2005-01-01

    Some aspects of assistive technology can be enhanced by the application of virtual reality. Although virtual simulation offers a range of new possibilities, learning to navigate in a virtual environment is not equivalent to learning to navigate in the real world. Therefore, virtual reality simulation is advocated as a useful preparation for…

  12. Viking navigation

    NASA Technical Reports Server (NTRS)

    Oneil, W. J.; Rudd, R. P.; Farless, D. L.; Hildebrand, C. E.; Mitchell, R. T.; Rourke, K. H.; Euler, E. A.

    1979-01-01

    A comprehensive description of the navigation of the Viking spacecraft throughout their flight from Earth launch to Mars landing is given. The flight path design, actual inflight control, and postflight reconstruction are discussed in detail. The preflight analyses upon which the operational strategies and performance predictions were based are discussed. The inflight results are then discussed and compared with the preflight predictions and, finally, the results of any postflight analyses are presented.

  13. Situation awareness and driving performance in a simulated navigation task.

    PubMed

    Ma, R; Kaber, D B

    2007-08-01

    The objective of this study was to identify task and vehicle factors that may affect driver situation awareness (SA) and its relationship to performance, particularly in strategic (navigation) tasks. An experiment was conducted to assess the effects of in-vehicle navigation aids and reliability on driver SA and performance in a simulated navigation task. A total of 20 participants drove a virtual car and navigated a large virtual suburb. They were required to follow traffic signs and navigation directions from either a human aid via a mobile phone or an automated aid presented on a laptop. The navigation aids operated under three different levels of information reliability (100%, 80% and 60%). A control condition was used in which each aid presented a telemarketing survey and participants navigated using a map. Results revealed perfect navigation information generally improved driver SA and performance compared to unreliable navigation information and the control condition (task-irrelevant information). In-vehicle automation appears to mediate the relationship of driver SA to performance in terms of operational and strategic (navigation) behaviours. The findings of this work support consideration of driver SA in the design of future vehicle automation for navigation tasks.

  14. Navigating abstract virtual environment: an eeg study.

    PubMed

    Hakak, Alireza Mahdizadeh; Bhattacharya, Joydeep; Biloria, Nimish; de Kleijn, Roy; Shah-Mohammadi, Fanak

    2016-12-01

    Perceptions of different environments are different for different people. An abstract designed environment, with a degree of freedom from any visual reference in the physical world requests a completely different perception than a fully or semi-designed environment that has some correlation with the physical world. Maximal evidence on the manner in which the human brain is involved/operates in dealing with such novel perception comes from neuropsychology. Harnessing the tools and techniques involved in the domain of neuropsychology, the paper presents nee evidence on the role of pre-central gyrus in the perception of abstract spatial environments. In order to do so, the research team developed three different categories of designed environment with different characteristics: (1) Abstract environment, (2) Semi-designed environment, (3) Fully designed environment, as experimental sample environments. Perception of Fully-designed and semi-designed environments is almost the same, [maybe] since the brain can find a correlation between designed environments and already experienced physical world. In addition to this, the response to questionnaires accompanied with a list of buzzwords that have been provided after the experiments, also describe the characteristics of the chosen sample environments. Additionally, these results confirm the suitability of continuous electroencephalography (EEG) for studying Perception from the perspective of architectural environments.

  15. Pre-operative anaemia.

    PubMed

    Clevenger, B; Richards, T

    2015-01-01

    Pre-operative anaemia is a relatively common finding, affecting a third of patients undergoing elective surgery. Traditionally associated with chronic disease, management has historically focused on the use of blood transfusion as a solution for anaemia in the peri-operative period. Data from large series now suggest that anaemia is an independent risk associated with poor outcome in both cardiac and non-cardiac surgery. Furthermore, blood transfusion does not appear to ameliorate this risk, and in fact may increase the risk of postoperative complications and hospital length of stay. Consequently, there is a need to identify, diagnose and manage pre-operative anaemia to reduce surgical risk. Discoveries in the pathways of iron metabolism have found that chronic disease can cause a state of functional iron deficiency leading to anaemia. The key iron regulatory protein hepcidin, activated in response to inflammation, inhibits absorption of iron from the gastrointestinal tract and further reduces bioavailability of iron stores for red cell production. Consequently, although iron stores (predominantly ferritin) may be normal, the transport of iron either from the gastrointestinal tract or iron stores to the bone marrow is inhibited, leading to a state of 'functional' iron deficiency and subsequent anaemia. Since absorption from the gastrointestinal tract is blocked, increasing oral iron intake is ineffective, and studies are now looking at the role of intravenous iron to treat anaemia in the surgical setting. In this article, we review the incidence and impact of anaemia on the pre-operative patient. We explain how anaemia may be caused by functional iron deficiency, and how iron deficiency anaemia may be diagnosed and treated.

  16. Virtual modeling of robot-assisted manipulations in abdominal surgery

    PubMed Central

    Berelavichus, Stanislav V; Karmazanovsky, Grigory G; Shirokov, Vadim S; Kubyshkin, Valeriy A; Kriger, Andrey G; Kondratyev, Evgeny V; Zakharova, Olga P

    2012-01-01

    AIM: To determine the effectiveness of using multidetector computed tomography (MDCT) data in preoperative planning of robot-assisted surgery. METHODS: Fourteen patients indicated for surgery underwent MDCT using 64 and 256-slice MDCT. Before the examination, a specially constructed navigation net was placed on the patient’s anterior abdominal wall. Processing of MDCT data was performed on a Brilliance Workspace 4 (Philips). Virtual vectors that imitate robotic and assistant ports were placed on the anterior abdominal wall of the 3D model of the patient, considering the individual anatomy of the patient and the technical capabilities of robotic arms. Sites for location of the ports were directed by projection on the roentgen-positive tags of the navigation net. RESULTS: There were no complications observed during surgery or in the post-operative period. We were able to reduce robotic arm interference during surgery. The surgical area was optimal for robotic and assistant manipulators without any need for reinstallation of the trocars. CONCLUSION: This method allows modeling of the main steps in robot-assisted intervention, optimizing operation of the manipulator and lowering the risk of injuries to internal organs. PMID:22816028

  17. Establishing navigated control in head surgery.

    PubMed

    Hofer, M; Strauss, G; Koulechov, K; Strauss, M; Stopp, S; Pankau, A; Korb, W; Trantakis, Ch; Meixensberger, J; Dietz, A; Lüth, T

    2006-01-01

    Navigated Control (NC) describes an additional control for a tracked power driven instrument within a preoperatively segmented work space. In head surgery the authors first implemented NC in functional endoscopic sinus surgery (FESS). Recently the feasibility of NC for surgery on the petrosal bone is evaluated. NC in FESS and in petrosal bone surgery may reduce the risk of comorbidity and the time effort compared to the conventional surgical interventions.

  18. Simulation of multi-probe radiofrequency ablation guided by optical surgery navigation system under different active modes.

    PubMed

    Xu, Leyi; Cai, Ken; Yang, Rongqian; Lin, Qinyong; Yue, Hongwei; Liu, Feng

    2016-12-01

    Radiofrequency ablation (RFA) is a crucial alternative treatment for liver cancer with the advantages of minimal invasion and a fast prognosis. However, two problems limit its further application: the orientation of the puncture point and the ablation of large tumors. The optical surgery navigation system in the RFA presents a promising approach for solving the localization problem in the puncturing process, which greatly increases puncture accuracy and has overcome the disadvantages of traditional RFA surgery. In addition, the use of multiple electrodes in the RFA (multi-probe RFA) is proposed and is applied clinically to deal with large tumors. In this study, we present a multi-probe RFA model using the finite element method (FEM) combined with a self-developed optical surgical navigation system. A real 3D liver model was adopted as an effective reference. Based on this model, two-probe RFA simulations were performed under different active modes. An analysis was conducted from the perspective of the temperature and electric potential fields and cell necrosis. The simulation results showed that different active modes had separate advantages and were suitable for different situations. Understanding their advantages can not only help doctors make surgical plans that fit the patients' conditions, but also the understanding can offer a virtual surgery platform for further development in the preoperative planning of RFA incorporated with the surgery navigation system.

  19. Virtual Colonoscopy

    MedlinePlus

    ... for Symptoms That Are Being Studied Virtual Colonoscopy Virtual Colonoscopy Print Screening CT scan takes images of ... less than a regular colonoscopy Get the facts Virtual colonoscopy, also called CT colonography, is a relatively ...

  20. Virtual colonoscopy

    MedlinePlus

    Colonoscopy - virtual; CT colonography; Computed tomographic colonography; Colography - virtual ... Differences between virtual and conventional colonoscopy include: VC can view the colon from many different angles. This is not as easy ...

  1. Cognitive Styles and Virtual Environments.

    ERIC Educational Resources Information Center

    Ford, Nigel

    2000-01-01

    Discussion of navigation through virtual information environments focuses on the need for robust user models that take into account individual differences. Considers Pask's information processing styles and strategies; deep (transformational) and surface (reproductive) learning; field dependence/independence; divergent/convergent thinking;…

  2. NES: Search the Virtual Campus

    NASA Image and Video Library

    Discover how to use the resources available within the NES Virtual Campus. Learn how to use the built-in filter feature and the “browse all” buttons to quickly navigate through all of the featu...

  3. Right-lateralized brain oscillations in human spatial navigation.

    PubMed

    Jacobs, Joshua; Korolev, Igor O; Caplan, Jeremy B; Ekstrom, Arne D; Litt, Brian; Baltuch, Gordon; Fried, Itzhak; Schulze-Bonhage, Andreas; Madsen, Joseph R; Kahana, Michael J

    2010-05-01

    During spatial navigation, lesion and functional imaging studies suggest that the right hemisphere has a unique functional role. However, studies of direct human brain recordings have not reported interhemisphere differences in navigation-related oscillatory activity. We investigated this apparent discrepancy using intracranial electroencephalographic recordings from 24 neurosurgical patients playing a virtual taxi driver game. When patients were virtually moving in the game, brain oscillations at various frequencies increased in amplitude compared with periods of virtual stillness. Using log-linear analysis, we analyzed the region and frequency specificities of this pattern and found that neocortical movement-related gamma oscillations (34-54 Hz) were significantly lateralized to the right hemisphere, especially in posterior neocortex. We also observed a similar right lateralization of gamma oscillations related to searching for objects at unknown virtual locations. Thus, our results indicate that gamma oscillations in the right neocortex play a special role in human spatial navigation.

  4. Evaluation of visualization techniques for image-guided navigation in liver surgery.

    PubMed

    Vetter, Marcus; Hassenpflug, Peter; Thorn, Matthias; Cárdenas, Carlos; Richter, Götz Martin; Lamadé, Wolfram; Herfarth, Christian; Meinzer, Hans-Peter

    2002-01-01

    A substantial component of an image-guided surgery system (IGSS) is the kind of three-dimensional (3D) presentation to the surgeon because the visual depth perception of the complex anatomy is of significant relevance for orientation. Therefore, we examined in this contribution four different visualization techniques, which were evaluated by eight surgeons. The IGSS developed by our group supports the intraoperative orientation of the surgeon by depicting a visualization of the spatially tracked surgical instruments with respect to intrahepatic vessels that have to be conserved vitally, the tumor, and preoperatively calculated resection planes. In the prelimenary trial presented here we examined the human ability to percept an intraoperative virtual scene and to solve given navigation tasks. The focus of the experiments was to measure the ability of eight surgeons to orientate intrahepaticaly and to transfer the percepted spatial relation to movements in real space. An autostereoscopic visualization with a prism-based display yielded that the navigation can be performed faster and more accurately than with the other visualization techniques.

  5. Preoperative anxiety in neurosurgical patients.

    PubMed

    Perks, Anna; Chakravarti, Sucharita; Manninen, Pirjo

    2009-04-01

    Anxiety is common in surgical patients, with an incidence of 60% to 92%. There is little information on the incidence and severity of preoperative anxiety in patients scheduled for neurosurgery. The aim of this study was to measure the level of preoperative anxiety in neurosurgical patients and to assess any influencing factors. After the Institutional Review Board approval and informed written consent, 100 patients booked for neurosurgery were interviewed preoperatively. Each patient was asked to grade their preoperative anxiety level on a verbal analog scale, Amsterdam Preoperative Anxiety and Information Scale, and a set of specific anxiety-related questions. The anxiety scores and the responses to the questions were compared between the sex, age, weight, diagnosis, and history of previous surgery. The mean age (+/-SD) was 50+/-13 years. The preoperative diagnosis was tumor (n=64), aneurysm (n=14), and other (n=22). Overall verbal analog scale was 5.2+/-2.7; the score was higher for female (5.8+/-2.8) than male patients (4.6+/-2.5) (P<0.05). Amsterdam Preoperative Anxiety and Information Scale anxiety and knowledge scores were greater for surgery than for anesthesia. Questionnaire results showed that the most common anxieties were waiting for surgery, physical/mental harm, and results of the operation. In conclusion, our study showed that neurosurgical patients have high levels of anxiety, with a higher incidence in females. There was a moderately high need for information, particularly in patients with a high level of preoperative anxiety.

  6. Does Navigation Improve Pedicle Screw Placement Accuracy? Comparison Between Navigated and Non-navigated Percutaneous and Open Fixations.

    PubMed

    Innocenzi, Gualtiero; Bistazzoni, Simona; D'Ercole, Manuela; Cardarelli, Giovanni; Ricciardi, Francesco

    2017-01-01

    The aim of our study was to assess how a preoperative computed tomography (CT)-based navigation system affected the correctness and safety of transpedicular screw insertion, compared with standard techniques. Between January 2012 and February 2014, 203 patients underwent thoracic and lumbar fixation, with open and percutaneous techniques; 218 screws were implanted through an open navigated technique (1.0 Spine & Trauma 3d ver. 2.0 BrainLab, Feldkirchen Germany) in 43 patients; 220 screws were inserted with an open free-hand technique in 45 patients; 230 screws were implanted in 56 patients using percutaneous CT-based navigation; and 236 screws were inserted in 59 patients using a percutaneous fluoroscopy-guided technique. To our knowledge, this is the first work comparing these four different techniques. The position of each screw was evaluated on CT scan reconstruction and classified according to a four-point grading scale (grade 0: no breach, grade 1: breach < 2 mm, grade 2: breach between 2 and 4 mm; grade 3: breach >4 mm). Statistical analysis was assessed by two-way analysis of variance (ANOVA) t test, while the Fisher least significant difference (LSD) method was employed to determine statistical significance. Statistical analysis showed a significant difference in accuracy between the open CT-based navigation and the percutaneous CT-based navigation techniques (P= 0.0263) and between the open CT-based navigation and the percutaneous fluoroscopy-guided techniques (P=0.0258): a particular difference was observed in anterior misplacement between open CT-based navigation and the percutaneous fluoroscopy-guided technique (P= 0.0153). Our results confirm the advantages of the navigation technique, which ensures greater accuracy, in open as well as percutaneous procedures.

  7. Preoperative nuclear scans in patients with melanoma

    SciTech Connect

    Au, F.C.; Maier, W.P.; Malmud, L.S.; Goldman, L.I.; Clark, W.H. Jr.

    1984-05-15

    One hundred forty-one liver scans, 137 brain scans, and 112 bone scans were performed in 192 patients with clinical Stage 1 melanoma. One liver scan was interpreted as abnormal; liver biopsy of that patient showed no metastasis. There were 11 suggestive liver scans; three of the patients with suggestive liver scans had negative liver biopsies. The remaining eight patients were followed from 4 to 6 years and none of those patients developed clinical evidence of hepatic metastases. All of the brain scans were normal. Five patients had suggestive bone scans and none of those patients had manifested symptoms of osseous metastases with a follow-up of 2 to 4.5 years. This study demonstrates that the use of preoperative liver, brain and bone scan in the evaluation of patients with clinical Stage 1 melanoma is virtually unproductive.

  8. Research on the airborne SINS/CNS integrated navigation system assisted by BD navigation system

    NASA Astrophysics Data System (ADS)

    Xie, Mei-lin; Yang, Xiao-xu; Han, Jun-feng; Wei, Yu; Yue, Peng; Deng, Xiao-guo; Huang, Wei

    2016-01-01

    When the star navigation system working during the day, the strong sky background radiation lead to a result that the detect target light is too weak, in the field of view, because of the limitation on the number of the navigation star, usually choose the single star navigation work mode. In order to improve the reliability of the airborne SINS/CNS integrated navigation system, meet the demand of the long-endurance and high precision navigation, use the tight combination way, single star patrol algorithm to get the position and attitude. There exists filtering divergence problem because of the model error and the system measurement noise is uncertain, put forward a new fuzzy adaptive kalman filtering algorithm. Adjust the size of measurement noise to prevent the filter divergence; the positioning accuracy of integrated navigation system can be improved through BeiDou satellite. Without the information of BeiDou satellite, based on the level of the virtual reference, the navigation precision of integrated navigation system can be ensured over a period of time.

  9. Reference frames in learning from maps and navigation.

    PubMed

    Meilinger, Tobias; Frankenstein, Julia; Watanabe, Katsumi; Bülthoff, Heinrich H; Hölscher, Christoph

    2015-11-01

    In everyday life, navigators often consult a map before they navigate to a destination (e.g., a hotel, a room, etc.). However, not much is known about how humans gain spatial knowledge from seeing a map and direct navigation together. In the present experiments, participants learned a simple multiple corridor space either from a map only, only from walking through the virtual environment, first from the map and then from navigation, or first from navigation and then from the map. Afterwards, they conducted a pointing task from multiple body orientations to infer the underlying reference frames. We constructed the learning experiences in a way such that map-only learning and navigation-only learning triggered spatial memory organized along different reference frame orientations. When learning from maps before and during navigation, participants employed a map- rather than a navigation-based reference frame in the subsequent pointing task. Consequently, maps caused the employment of a map-oriented reference frame found in memory for highly familiar urban environments ruling out explanations from environmental structure or north preference. When learning from navigation first and then from the map, the pattern of results reversed and participants employed a navigation-based reference frame. The priority of learning order suggests that despite considerable difference between map and navigation learning participants did not use the more salient or in general more useful information, but relied on the reference frame established first.

  10. Navigating through digital folders uses the same brain structures as real world navigation.

    PubMed

    Benn, Yael; Bergman, Ofer; Glazer, Liv; Arent, Paris; Wilkinson, Iain D; Varley, Rosemary; Whittaker, Steve

    2015-10-01

    Efficient storage and retrieval of digital data is the focus of much commercial and academic attention. With personal computers, there are two main ways to retrieve files: hierarchical navigation and query-based search. In navigation, users move down their virtual folder hierarchy until they reach the folder in which the target item is stored. When searching, users first generate a query specifying some property of the target file (e.g., a word it contains), and then select the relevant file when the search engine returns a set of results. Despite advances in search technology, users prefer retrieving files using virtual folder navigation, rather than the more flexible query-based search. Using fMRI we provide an explanation for this phenomenon by demonstrating that folder navigation results in activation of the posterior limbic (including the retrosplenial cortex) and parahippocampal regions similar to that previously observed during real-world navigation in both animals and humans. In contrast, search activates the left inferior frontal gyrus, commonly observed in linguistic processing. We suggest that the preference for navigation may be due to the triggering of automatic object finding routines and lower dependence on linguistic processing. We conclude with suggestions for future computer systems design.

  11. Navigating through digital folders uses the same brain structures as real world navigation

    PubMed Central

    Benn, Yael; Bergman, Ofer; Glazer, Liv; Arent, Paris; Wilkinson, Iain D.; Varley, Rosemary; Whittaker, Steve

    2015-01-01

    Efficient storage and retrieval of digital data is the focus of much commercial and academic attention. With personal computers, there are two main ways to retrieve files: hierarchical navigation and query-based search. In navigation, users move down their virtual folder hierarchy until they reach the folder in which the target item is stored. When searching, users first generate a query specifying some property of the target file (e.g., a word it contains), and then select the relevant file when the search engine returns a set of results. Despite advances in search technology, users prefer retrieving files using virtual folder navigation, rather than the more flexible query-based search. Using fMRI we provide an explanation for this phenomenon by demonstrating that folder navigation results in activation of the posterior limbic (including the retrosplenial cortex) and parahippocampal regions similar to that previously observed during real-world navigation in both animals and humans. In contrast, search activates the left inferior frontal gyrus, commonly observed in linguistic processing. We suggest that the preference for navigation may be due to the triggering of automatic object finding routines and lower dependence on linguistic processing. We conclude with suggestions for future computer systems design. PMID:26423226

  12. An excellent navigation system and experience in craniomaxillofacial navigation surgery: a double-center study.

    PubMed

    Dai, Jiewen; Wu, Jinyang; Wang, Xudong; Yang, Xudong; Wu, Yunong; Xu, Bing; Shi, Jun; Yu, Hongbo; Cai, Min; Zhang, Wenbin; Zhang, Lei; Sun, Hao; Shen, Guofang; Zhang, Shilei

    2016-06-16

    Numerous problems regarding craniomaxillofacial navigation surgery are not well understood. In this study, we performed a double-center clinical study to quantitatively evaluate the characteristics of our navigation system and experience in craniomaxillofacial navigation surgery. Fifty-six patients with craniomaxillofacial disease were included and randomly divided into experimental (using our AccuNavi-A system) and control (using Strker system) groups to compare the surgical effects. The results revealed that the average pre-operative planning time was 32.32 mins vs 29.74 mins between the experimental and control group, respectively (p > 0.05). The average operative time was 295.61 mins vs 233.56 mins (p > 0.05). The point registration orientation accuracy was 0.83 mm vs 0.92 mm. The maximal average preoperative navigation orientation accuracy was 1.03 mm vs 1.17 mm. The maximal average persistent navigation orientation accuracy was 1.15 mm vs 0.09 mm. The maximal average navigation orientation accuracy after registration recovery was 1.15 mm vs 1.39 mm between the experimental and control group. All patients healed, and their function and profile improved. These findings demonstrate that although surgeons should consider the patients' time and monetary costs, our qualified navigation surgery system and experience could offer an accurate guide during a variety of craniomaxillofacial surgeries.

  13. An excellent navigation system and experience in craniomaxillofacial navigation surgery: a double-center study

    PubMed Central

    Dai, Jiewen; Wu, Jinyang; Wang, Xudong; Yang, Xudong; Wu, Yunong; Xu, Bing; Shi, Jun; Yu, Hongbo; Cai, Min; Zhang, Wenbin; Zhang, Lei; Sun, Hao; Shen, Guofang; Zhang, Shilei

    2016-01-01

    Numerous problems regarding craniomaxillofacial navigation surgery are not well understood. In this study, we performed a double-center clinical study to quantitatively evaluate the characteristics of our navigation system and experience in craniomaxillofacial navigation surgery. Fifty-six patients with craniomaxillofacial disease were included and randomly divided into experimental (using our AccuNavi-A system) and control (using Strker system) groups to compare the surgical effects. The results revealed that the average pre-operative planning time was 32.32 mins vs 29.74 mins between the experimental and control group, respectively (p > 0.05). The average operative time was 295.61 mins vs 233.56 mins (p > 0.05). The point registration orientation accuracy was 0.83 mm vs 0.92 mm. The maximal average preoperative navigation orientation accuracy was 1.03 mm vs 1.17 mm. The maximal average persistent navigation orientation accuracy was 1.15 mm vs 0.09 mm. The maximal average navigation orientation accuracy after registration recovery was 1.15 mm vs 1.39 mm between the experimental and control group. All patients healed, and their function and profile improved. These findings demonstrate that although surgeons should consider the patients’ time and monetary costs, our qualified navigation surgery system and experience could offer an accurate guide during a variety of craniomaxillofacial surgeries. PMID:27305855

  14. Navigation system measures AP and rotational knee laxity in ACL replacement.

    PubMed

    Jenny, Jean-Yves

    2009-10-01

    We used a non-image-based navigation system to measure anterior and rotational laxity during anterior cruciate ligament replacement. The preoperative and postoperative navigated measurements of anterior laxity were compared with the preoperative and postoperative stress radiographs. There was a significant difference between these 2 measurements, but they were significantly correlated. Navigated anterior laxity measurement can therefore be considered reliable. The intraoperative information about the correction of the anterior laxity may have relevance in controlling the quality of the procedure and improving reproducibility. Information about rotational laxity may be helpful, but its exact significance must be more precisely defined. Copyright 2009, SLACK Incorporated.

  15. Combining physical and semantical navigation in three-dimensional information visualization

    NASA Astrophysics Data System (ADS)

    Russo Dos Santos, Cristina; Gros, Pascal; Abel, Pierre

    2002-03-01

    The field of information visualization is in permanent expansion and new and innovative ways of visualizing large volumes of abstract data are being developed. The use of virtual metaphoric worlds is one of them, but these visualizations per se are only truly useful if the user is provided a means of exploring the information. A common way of data exploration is navigation. In the case of three-dimensional (3D) information visualization, navigation as a means of information exploration attains even more importance due to the extra exploitable dimension. Nonetheless, navigation in large virtual worlds is still a difficult task and not only for naive users; there is anecdotal evidence that electronic navigation is considered difficult even by the virtual worlds builders. Wayfinding, knowing where to go, is sometimes perceived as the hardest part; other times, it is the locomotion, getting there, that is found difficult. This paper presents a navigation strategy that attempts to solve these problems by combining physical/metaphoric navigation with semantic navigation. We present a framework for navigating large virtual worlds that relies heavily on the use of visual metaphors. The combination of physical and semantic navigation embedded in the metaphor components allows for a powerful data exploration and electronic navigation mechanism.

  16. Computer assisted surgery. Its usefulness in different levels of pre-operative deformities.

    PubMed

    Benavente, P; López Orosa, C; Oteo Maldonado, J A; Orois Codesal, A; García Lázaro, F J

    2015-01-01

    To compare the results obtained with computer assisted surgery with conventional techniques and evaluate the influence of navigation at different levels of preoperative deformity. A retrospective study was conducted on 100 cases with primary total knee arthroplasty performed with conventional or computer assisted surgery. A comparison was made of the post-operative mechanical axis of the lower limb between both groups and in terms of pre-operative deformity. Optimal alignment is most often obtained by using the navigation system (62%) than by a conventional technique (36%). Patients with deformities under 10° varus showed a mean post-operative alignment within the optimal range (0±3° deviation from the neutral mechanical axis), while those with more than 15° of varus show an alignment out of range, regardless of the technique used (p=.002). In those with a deformity of between 10 and 15° of pre-operative varus alignment, values were found closer to the neutral axis in the navigation group (178.7°) than in the conventional technique (175.5°), although these differences are not statistically significant (p=.127). Post-operative alignment obtained with navigation is better than with the conventional technique, with a smaller percentage of cases out of range, and greater accuracy in placing implants. A potential benefit was observed in navigation for cases with deformities of between 10 and 15° of varus. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  17. Can Active Navigation Be as Good as Driving? A Comparison of Spatial Memory in Drivers and Backseat Drivers

    ERIC Educational Resources Information Center

    von Stulpnagel, Rul; Steffens, Melanie C.

    2012-01-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario,…

  18. Can Active Navigation Be as Good as Driving? A Comparison of Spatial Memory in Drivers and Backseat Drivers

    ERIC Educational Resources Information Center

    von Stulpnagel, Rul; Steffens, Melanie C.

    2012-01-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario,…

  19. Gray and white matter correlates of navigational ability in humans.

    PubMed

    Wegman, Joost; Fonteijn, Hubert M; van Ekert, Janneke; Tyborowska, Anna; Jansen, Clemens; Janzen, Gabriele

    2014-06-01

    Humans differ widely in their navigational abilities. Studies have shown that self-reports on navigational abilities are good predictors of performance on navigation tasks in real and virtual environments. The caudate nucleus and medial temporal lobe regions have been suggested to subserve different navigational strategies. The ability to use different strategies might underlie navigational ability differences. This study examines the anatomical correlates of self-reported navigational ability in both gray and white matter. Local gray matter volume was compared between a group (N = 134) of good and bad navigators using voxel-based morphometry (VBM), as well as regional volumes. To compare between good and bad navigators, we also measured white matter anatomy using diffusion tensor imaging (DTI) and looked at fractional anisotropy (FA) values. We observed a trend toward higher local GM volume in right anterior parahippocampal/rhinal cortex for good versus bad navigators. Good male navigators showed significantly higher local GM volume in right hippocampus than bad male navigators. Conversely, bad navigators showed increased FA values in the internal capsule, the white matter bundle closest to the caudate nucleus and a trend toward higher local GM volume in the caudate nucleus. Furthermore, caudate nucleus regional volume correlated negatively with navigational ability. These convergent findings across imaging modalities are in line with findings showing that the caudate nucleus and the medial temporal lobes are involved in different wayfinding strategies. Our study is the first to show a link between self-reported large-scale navigational abilities and different measures of brain anatomy. Copyright © 2013 Wiley Periodicals, Inc.

  20. Navigating the Internet.

    PubMed Central

    Powsner, S M; Roderer, N K

    1994-01-01

    Navigating any complex set of information resources requires tools for both browsing and searching. A number of tools are available today for using Internet resources, and more are being developed. This article reviews existing navigational tools, including two developed at the Yale University School of Medicine, and points out their strengths and weaknesses. A major shortcoming of the present Internet navigation methods is the lack of controlled descriptions of the available resources. As a result, navigating the Internet is very difficult. PMID:7841913

  1. Design of a 3D Navigation Technique Supporting VR Interaction

    NASA Astrophysics Data System (ADS)

    Boudoin, Pierre; Otmane, Samir; Mallem, Malik

    2008-06-01

    Multimodality is a powerful paradigm to increase the realness and the easiness of the interaction in Virtual Environments (VEs). In particular, the search for new metaphors and techniques for 3D interaction adapted to the navigation task is an important stage for the realization of future 3D interaction systems that support multimodality, in order to increase efficiency and usability. In this paper we propose a new multimodal 3D interaction model called Fly Over. This model is especially devoted to the navigation task. We present a qualitative comparison between Fly Over and a classical navigation technique called gaze-directed steering. The results from preliminary evaluation on the IBISC semi-immersive Virtual Reality/Augmented Realty EVR@ platform show that Fly Over is a user friendly and efficient navigation technique.

  2. Learning navigation - Learning with navigation. A review.

    PubMed

    Jenny, Jean-Yves; Picard, Frederic

    2017-01-01

    The goal of this review paper is to retrieve from the existing literature relevant information (1) about the learning curve of the currently existing navigation systems and (2) about the use of navigation system for teaching orthopaedic procedures. All studies reporting on the learning curve of navigation systems support the hypothesis that computer-navigated total knee arthroplasty (TKA) involves only a short learning curve and that beginners can obtain good results from the beginning of their experience, as navigation provides continuous feedback during all phases of the knee replacement surgery and allows for correcting any bone cut errors. Interestingly, there is no comparable research on the learning curve of TKA with standard, manual instrumentation. One might postulate that this learning curve might be longer than with navigation, with potentially a higher rate of outliers. The current literature does support that navigation may be an efficient teaching tool for both experienced orthopaedic surgeons and trainees. Experienced surgeons may improve their skills with conventional techniques and learn new techniques more efficiently and more quickly. Trainees may have a better understanding of the procedure and learn standard techniques with a shorter learning curve. This is probably due to the immediate feedback of navigation systems. A shorter learning curve may be associated with improved clinical and functional results for the patient during this critical period. However, there is no evidence that training with navigation excludes trainees from the need to work in academic environments with experienced teachers. Future techniques in training may include the development of laboratory simulation procedures using navigated feedback. © The Authors, published by EDP Sciences, 2017.

  3. The virtual reality tool VirSSPA in planning DIEP microsurgical breast reconstruction.

    PubMed

    Gómez-Cía, T; Gacto-Sánchez, P; Sicilia, D; Suárez, C; Acha, B; Serrano, C; Parra, C; De La Higuera, J

    2009-06-01

    The significant variation in the vascular anatomy of the abdominal wall makes preoperative imaging essential when raising a DIEP (deep inferior epigastric artery perforator) flap due to the potential for maximizing operative success, reducing intraoperative error and minimizing operative complications. Variability in perforator anatomy makes DIEP flap surgery a suitable candidate for computer and virtual reality bio models. In this context, a study was undertaken to determine the feasibility of CTA-guided by VirSSPA application. VirSSPA is a virtual reality tool developed in our Hospital for surgical planning and training. This application allows surgeons to generate the three-dimensional (3D) model of the patient. In this paper, we present a study about VirSSPA tool for virtual reality navigation in DIEP flap surgery and compare findings with operative measurements. We recruited 12 consecutive patients planned for an elective DIEP flap for breast reconstruction. Each patient underwent preoperative imaging of the anterior abdominal wall vasculature with both conventional CTA and VirSSPA 3D reconstruction. Imaging findings were compared to operative findings. 3D reconstruction of the abdominal wall with VirSSPA demonstrated a significant good correlation with perforator location compared to operative findings, showing an average error rate of 0.228 cm (95% CI, 0.17-0.30). The Pearson product-moment correlation coefficient was found to be 0.99 (p = 0.01), reflecting an almost linear relationship between the two distances, intraoperative and the one measured in the 3D reconstruction. VirSSPA provides additional and potentially more accurate data over conventional CTA with regard to the site of the best perforators and its course through the muscle for DIEP micro-vascular surgery.

  4. Personal Navigation System

    DTIC Science & Technology

    2005-10-31

    the capabilities of prototype hardware for navigation in GPS - denied and significantly challenged environments. Two technologies, developed at...building operational navigation sequence: GPS position initialization, handover to Deep Integration tracking, GPS - denied navigation, and finally satellite...Vertical Gait CEP relative to entry Max Relative Error Position error at entry Entry to exit Time GPS denied or challenged Draper Indoor Course

  5. Coastal Navigation Portfolio Management

    DTIC Science & Technology

    2015-02-19

    CIRP.aspx Coastal Inlets Research Program Coastal Navigation Portfolio Management The Coastal Navigatoin Portfolio Management work unit...across the vast coastal navigation portfolio of projects. The USACE maintains a vast infrastructure portfolio of deep-draft coastal entrance...the Corps needs to be able to direct resources at the navigation projects that are most critical to overall marine transportation system performance

  6. Virtual Surgical Planning in Craniofacial Surgery

    PubMed Central

    Chim, Harvey; Wetjen, Nicholas; Mardini, Samir

    2014-01-01

    The complex three-dimensional anatomy of the craniofacial skeleton creates a formidable challenge for surgical reconstruction. Advances in computer-aided design and computer-aided manufacturing technology have created increasing applications for virtual surgical planning in craniofacial surgery, such as preoperative planning, fabrication of cutting guides, and stereolithographic models and fabrication of custom implants. In this review, the authors describe current and evolving uses of virtual surgical planning in craniofacial surgery. PMID:25210509

  7. Space Shuttle navigation validation

    NASA Astrophysics Data System (ADS)

    Ragsdale, A.

    The validation of the guidance, navigation, and control system of the Space Shuttle is explained. The functions of the ascent, on-board, and entry mission phases software of the navigation system are described. The common facility testing, which evaluates the simulations to be used in the navigation validation, is examined. The standard preflight analysis of the operational modes of the navigation software and the post-flight navigation analysis are explained. The conversion of the data into a useful reference frame and the use of orbit parameters in the analysis of the data are discussed. Upon entry the data received are converted to flags, ratios, and residuals in order to evaluate performance and detect errors. Various programs developed to support navigation validation are explained. A number of events that occurred with the Space Shuttle's navigation system are described.

  8. Space Shuttle navigation validation

    NASA Technical Reports Server (NTRS)

    Ragsdale, A.

    1985-01-01

    The validation of the guidance, navigation, and control system of the Space Shuttle is explained. The functions of the ascent, on-board, and entry mission phases software of the navigation system are described. The common facility testing, which evaluates the simulations to be used in the navigation validation, is examined. The standard preflight analysis of the operational modes of the navigation software and the post-flight navigation analysis are explained. The conversion of the data into a useful reference frame and the use of orbit parameters in the analysis of the data are discussed. Upon entry the data received are converted to flags, ratios, and residuals in order to evaluate performance and detect errors. Various programs developed to support navigation validation are explained. A number of events that occurred with the Space Shuttle's navigation system are described.

  9. Preoperative staging of rectal cancer.

    PubMed

    Smith, Neil; Brown, Gina

    2008-01-01

    Detailed preoperative staging using high resolution magnetic resonance imaging (MRI) enables the selection of patients that require preoperative therapy for tumour regression. This information can be used to instigate neoadjuvant therapy in those patients with poor prognostic features prior to disturbing the tumour bed and potentially disseminating disease. The design of trials incorporating MR assessment of prognostic factors prior to therapy has been found to be of value in assessing treatment modalities and outcomes that are targeted to these preoperative prognostic subgroups and in providing a quantifiable assessment of the efficacy of particular chemoradiation treatment protocols by comparing pre-treatment MR staging with post therapy histology assessment. At present, we are focused on achieving clear surgical margins of excision (CRM) to avoid local recurrence. We recommend that all patients with rectal cancer should undergo pre-operative MRI staging. Of these, about half will have good prognosis features (T1-T3b, N0, EMVI negative, CRM clear) and may safely undergo primary total mesorectal excision. Of the remainder, those with threatened or involved margins will certainly benefit from pre-operative chemoradiotherapy with the aim of downstaging to permit safe surgical excision. In the future, our ability to recognise features predicting distant failure, such as extramural vascular invasion (EMVI) may be used to stratify patients for neo-adjuvant systemic chemotherapy in an effort to prevent distant relapse. The optimal pre-operative treatment regimes for these patients (radiotherapy alone, systemic chemotherapy alone or combination chemo-radiotherapy) is the subject of current and future trials.

  10. Pre-operative preparation for otologic surgery: temporal bone simulation

    PubMed Central

    Sethia, Rishabh; Wiet, Gregory J.

    2015-01-01

    Purpose of review The field of temporal bone simulation (TBS) has largely focused on the development and validation of simulators as training and assessment tools. However, as technology has progressed over the years, researchers have envisioned new clinical applications for simulators extending to pre-operative surgical planning and case rehearsal. The purpose of this article is to review the current state of the art in TBS and to highlight recent advancements in the field. Due to space limitations, we will limit our discussion to computer-based virtual reality (VR) simulators. Recent findings A review of the recent literature on TBS revealed very limited application of VR simulators for pre-operative preparation. Current evidence suggests limitations in fidelity preclude successful patient-specific case rehearsal using VR simulation. Further investigation and clinical evaluation are required to validate its use outside of training and skill assessment. Summary This article provides an overview of the current use of VR simulators with emphasis on pre-operative planning. We evaluate the limitations of the technology, and discuss potential areas of improvement for the future. More studies are necessary to assess the value of VR simulation for pre-operative preparation. PMID:26339966

  11. Preoperative Psychological Preparation of Children

    PubMed Central

    Güleç, Ersel; Özcengiz, Dilek

    2015-01-01

    Surgery and anaesthesia are significant sources of anxiety for children. In the preoperative period, reducing anxiety helps in preventing the negative consequences that may occur after surgery. The predetermined high-risk children in terms of the development of anxiety play an important role in reducing the negative consequences. Recently featured approaches are modelling and coping techniques, although many techniques are used in the preoperative psychological preparation. The use of computer programs in this area may facilitate important achievements, and it needs to support new studies to be performed. PMID:27366525

  12. Virtual volatility

    NASA Astrophysics Data System (ADS)

    Silva, A. Christian; Prange, Richard E.

    2007-03-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation strategy.

  13. Virtual Reality

    DTIC Science & Technology

    1993-04-01

    AuD-A278 294 1993 Executive Research Project S12 Virtul Reality Lieutenant Colonel James F. Dailey U.S. Air Force Faculty Research Advisor Dr. C...until exhausted. SECURITY CLASSIFICATION OF THIS PAGE All other editions are obsolete. UNCLASSIFIED "VIRTUAL REALITY JAMES F. DAILEY, LIEUTENANT COLONEL...US" This paper reviews the exciting field of virtual reality . The author describes the basic concepts of virtual reality and finds that its numerous

  14. Anxiety in preoperative anesthetic procedures.

    PubMed

    Valenzuela Millán, Jaquelyn; Barrera Serrano, José René; Ornelas Aguirre, José Manuel

    2010-01-01

    Preoperative anxiety is a common and poorly evaluated condition in patients who will undergo an anesthetic and surgical intervention. The objective of this study was to determine the prevalence of anxiety in a group of patients undergoing elective surgery, as assessed by the Amsterdam Anxiety Preoperative and Information (AAPI) scale. We studied 135 patients scheduled for elective surgery applying the AAPI scale 24 h before the surgical procedure to evaluate the presence of anxiety and patient characteristics. A descriptive analysis with mean +/- standard deviation for categorical variables was done. For intragroup differences, chi(2) test was used. Pearson correlation for the association between anxiety and postoperative complications was carried out. A value of p =0.05 was considered significant. One hundred six patients were surgically treated, 88% were female (average age 44 +/- 12 years). Some degree of preoperative anxiety was present in 72 patients (76%; p = 0.001) with a grade point average on the AAPI scale equal to 17 +/- 7 points, of which 95 (70%, OR = 5.08; p = 0.002) were females. Results of this study suggest the presence of high levels of preoperative anxiety in patients scheduled for elective surgery. The origin of the anxiety appears to be related to many factors that can be evaluated in pre-anesthetic consultation. Further study is needed to prevent the presence of this disorder.

  15. FAA navigation program

    NASA Technical Reports Server (NTRS)

    Blake, N. A.

    1978-01-01

    The FAA navigation program, which includes two major activity areas: those associated with certification of navigation systems to meet current requirements and those associated with building the data base needed to define future system improvements is examined. The near term activities, including the VORTAC upgrading program, the development of the technical data base needed for certification of LORAN C and OMEGA as a part of the current air navigation system, and the development of area navigation standards are examined in regard to cost factors and user requirements. Future system activities discussed include analysis of alternative system configurations made up of system elements including VORTAC VOR-DME, OMEGA and differential OMEGA, LORAN C, and GPS. The interrelationships between the near and far term programs are discussed. A helicopter IFR program which includes an assessment of the operational suitability of several navigation system alternatives for meeting helicopter navigation requirements for CONUS and offshore operations is reported.

  16. Virtual Schooling: A Guide to Optimizing Your Child's Education

    ERIC Educational Resources Information Center

    Kanna, Elizabeth; Gillis, Lisa

    2009-01-01

    Today, millions of school-age children are learning outside of a traditional classroom and using cutting edge educational options. Policy experts predict that in a decade half of all education will be delivered virtually. In "Virtual Schooling" three top authorities help you navigate the fastest growing movement in education--regardless of whether…

  17. Brain Oscillatory Activity during Spatial Navigation: Theta and Gamma Activity Link Medial Temporal and Parietal Regions

    ERIC Educational Resources Information Center

    White, David J.; Congedo, Marco; Ciorciari, Joseph; Silberstein, Richard B.

    2012-01-01

    Brain oscillatory correlates of spatial navigation were investigated using blind source separation (BSS) and standardized low resolution electromagnetic tomography (sLORETA) analyses of 62-channel EEG recordings. Twenty-five participants were instructed to navigate to distinct landmark buildings in a previously learned virtual reality town…

  18. Brain Oscillatory Activity during Spatial Navigation: Theta and Gamma Activity Link Medial Temporal and Parietal Regions

    ERIC Educational Resources Information Center

    White, David J.; Congedo, Marco; Ciorciari, Joseph; Silberstein, Richard B.

    2012-01-01

    Brain oscillatory correlates of spatial navigation were investigated using blind source separation (BSS) and standardized low resolution electromagnetic tomography (sLORETA) analyses of 62-channel EEG recordings. Twenty-five participants were instructed to navigate to distinct landmark buildings in a previously learned virtual reality town…

  19. Virtual Congresses

    PubMed Central

    Lecueder, Silvia; Manyari, Dante E.

    2000-01-01

    A new form of scientific medical meeting has emerged in the last few years—the virtual congress. This article describes the general role of computer technologies and the Internet in the development of this new means of scientific communication, by reviewing the history of “cyber sessions” in medical education and the rationale, methods, and initial results of the First Virtual Congress of Cardiology. Instructions on how to participate in this virtual congress, either actively or as an observer, are included. Current advantages and disadvantages of virtual congresses, their impact on the scientific community at large, and future developments and possibilities in this area are discussed. PMID:10641960

  20. [Navigation-supported surgery in the head and neck region].

    PubMed

    Majdani, O; Leinung, M; Lenarz, T; Heermann, R

    2003-09-01

    Few of the pioneering manufacturers who attempted to develop navigation systems have been able to establish themselves within the market long-term. The same applies to the technological basis of these systems which aid intraoperative anatomical orientation. The first few systems registered the mechanical displacement of the navigational instrument's axes. Optoelectronic and electromagnetic methods are now prevalent. In contrast to electromagnetic systems, the "line of sight" between the camera system, the reference markers placed on the patient's head and the navigation instruments must remain unobstructed during the navigation process when using electrooptical navigation systems. Whereas, in the past, only preoperative CT scans were used for navigation, the integration of MRI and sonography--whose images can now be fused with each other and with those provided by other intraoperative imaging techniques such as fluoroscopy and endosonography--has become increasingly popular. Navigation systems require input of information about spatial conditions. This is carried out via procedures of registration and referencing, by means of which the relative position of reference markers at the head of the patient is correlated with the image data. The equipment is calibrated in the same way. Headsets, headbands and bone-anchored adapters are available for the fixation of the markers in the patient's head. Whereas the use of a headband or headset requires considerably less time, bone-anchored referencing increases the precision of the navigation system. The surgeon must be able to manage the different methods. In order to reduce the time required for preoperative preparation and to enhance the handling of the navigation processor for the surgeon, it is essential to have a clear menu. The surgeon is able to plan the steps involved in the surgery using the processor, define the access to the surgical site and control the surgery intraoperatively. Preoperative segmentation of

  1. A multimodal image guiding system for Navigated Ultrasound Bronchoscopy (EBUS): A human feasibility study

    PubMed Central

    Hofstad, Erlend Fagertun; Amundsen, Tore; Langø, Thomas; Bakeng, Janne Beate Lervik; Leira, Håkon Olav

    2017-01-01

    Background Endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) is the endoscopic method of choice for confirming lung cancer metastasis to mediastinal lymph nodes. Precision is crucial for correct staging and clinical decision-making. Navigation and multimodal imaging can potentially improve EBUS-TBNA efficiency. Aims To demonstrate the feasibility of a multimodal image guiding system using electromagnetic navigation for ultrasound bronchoschopy in humans. Methods Four patients referred for lung cancer diagnosis and staging with EBUS-TBNA were enrolled in the study. Target lymph nodes were predefined from the preoperative computed tomography (CT) images. A prototype convex probe ultrasound bronchoscope with an attached sensor for position tracking was used for EBUS-TBNA. Electromagnetic tracking of the ultrasound bronchoscope and ultrasound images allowed fusion of preoperative CT and intraoperative ultrasound in the navigation software. Navigated EBUS-TBNA was used to guide target lymph node localization and sampling. Navigation system accuracy was calculated, measured by the deviation between lymph node position in ultrasound and CT in three planes. Procedure time, diagnostic yield and adverse events were recorded. Results Preoperative CT and real-time ultrasound images were successfully fused and displayed in the navigation software during the procedures. Overall navigation accuracy (11 measurements) was 10.0 ± 3.8 mm, maximum 17.6 mm, minimum 4.5 mm. An adequate sample was obtained in 6/6 (100%) of targeted lymph nodes. No adverse events were registered. Conclusions Electromagnetic navigated EBUS-TBNA was feasible, safe and easy in this human pilot study. The clinical usefulness was clearly demonstrated. Fusion of real-time ultrasound, preoperative CT and electromagnetic navigational bronchoscopy provided a controlled guiding to level of target, intraoperative overview and procedure documentation. PMID:28182758

  2. Mixing navigation on networks

    NASA Astrophysics Data System (ADS)

    Zhou, Tao

    2008-05-01

    In this article, we propose a mixing navigation mechanism, which interpolates between random-walk and shortest-path protocol. The navigation efficiency can be remarkably enhanced via a few routers. Some advanced strategies are also designed: For non-geographical scale-free networks, the targeted strategy with a tiny fraction of routers can guarantee an efficient navigation with low and stable delivery time almost independent of network size. For geographical localized networks, the clustering strategy can simultaneously increase efficiency and reduce the communication cost. The present mixing navigation mechanism is of significance especially for information organization of wireless sensor networks and distributed autonomous robotic systems.

  3. Virtual Laboratories and Virtual Worlds

    NASA Astrophysics Data System (ADS)

    Hut, Piet

    2008-05-01

    Since we cannot put stars in a laboratory, astrophysicists had to wait till the invention of computers before becoming laboratory scientists. For half a century now, we have been conducting experiments in our virtual laboratories. However, we ourselves have remained behind the keyboard, with the screen of the monitor separating us from the world we are simulating. Recently, 3D on-line technology, developed first for games but now deployed in virtual worlds like Second Life, is beginning to make it possible for astrophysicists to enter their virtual labs themselves, in virtual form as avatars. This has several advantages, from new possibilities to explore the results of the simulations to a shared presence in a virtual lab with remote collaborators on different continents. I will report my experiences with the use of Qwaq Forums, a virtual world developed by a new company (see http://www.qwaq.com).

  4. Virtual Labs and Virtual Worlds

    NASA Astrophysics Data System (ADS)

    Boehler, Ted

    2006-12-01

    Virtual Labs and Virtual Worlds Coastline Community College has under development several virtual lab simulations and activities that range from biology, to language labs, to virtual discussion environments. Imagine a virtual world that students enter online, by logging onto their computer from home or anywhere they have web access. Upon entering this world they select a personalized identity represented by a digitized character (avatar) that can freely move about, interact with the environment, and communicate with other characters. In these virtual worlds, buildings, gathering places, conference rooms, labs, science rooms, and a variety of other “real world” elements are evident. When characters move about and encounter other people (players) they may freely communicate. They can examine things, manipulate objects, read signs, watch video clips, hear sounds, and jump to other locations. Goals of critical thinking, social interaction, peer collaboration, group support, and enhanced learning can be achieved in surprising new ways with this innovative approach to peer-to-peer communication in a virtual discussion world. In this presentation, short demos will be given of several online learning environments including a virtual biology lab, a marine science module, a Spanish lab, and a virtual discussion world. Coastline College has been a leader in the development of distance learning and media-based education for nearly 30 years and currently offers courses through PDA, Internet, DVD, CD-ROM, TV, and Videoconferencing technologies. Its distance learning program serves over 20,000 students every year. sponsor Jerry Meisner

  5. Virtual reality as a distraction technique in chronic pain patients.

    PubMed

    Wiederhold, Brenda K; Gao, Kenneth; Sulea, Camelia; Wiederhold, Mark D

    2014-06-01

    We explored the use of virtual reality distraction techniques for use as adjunctive therapy to treat chronic pain. Virtual environments were specifically created to provide pleasant and engaging experiences where patients navigated on their own through rich and varied simulated worlds. Real-time physiological monitoring was used as a guide to determine the effectiveness and sustainability of this intervention. Human factors studies showed that virtual navigation is a safe and effective method for use with chronic pain patients. Chronic pain patients demonstrated significant relief in subjective ratings of pain that corresponded to objective measurements in peripheral, noninvasive physiological measures.

  6. Virtual Reality as a Distraction Technique in Chronic Pain Patients

    PubMed Central

    Gao, Kenneth; Sulea, Camelia; Wiederhold, Mark D.

    2014-01-01

    Abstract We explored the use of virtual reality distraction techniques for use as adjunctive therapy to treat chronic pain. Virtual environments were specifically created to provide pleasant and engaging experiences where patients navigated on their own through rich and varied simulated worlds. Real-time physiological monitoring was used as a guide to determine the effectiveness and sustainability of this intervention. Human factors studies showed that virtual navigation is a safe and effective method for use with chronic pain patients. Chronic pain patients demonstrated significant relief in subjective ratings of pain that corresponded to objective measurements in peripheral, noninvasive physiological measures. PMID:24892196

  7. Virtual Acoustics

    NASA Astrophysics Data System (ADS)

    Lokki, Tapio; Savioja, Lauri

    The term virtual acoustics is often applied when sound signal is processed to contain features of a simulated acoustical space and sound is spatially reproduced either with binaural or with multichannel techniques. Therefore, virtual acoustics consists of spatial sound reproduction and room acoustics modeling.

  8. Virtually Possible

    ERIC Educational Resources Information Center

    Mellon, Ericka

    2011-01-01

    Diane Lewis began building her popular virtual education program in a storage closet. The drab room, just big enough to squeeze in a tiny table, was her office at the headquarters of Seminole County (Florida) Public Schools. She had a computer and a small staff of temporary workers. Lewis, who managed to open two successful virtual schools for…

  9. Virtually Possible

    ERIC Educational Resources Information Center

    Mellon, Ericka

    2011-01-01

    Diane Lewis began building her popular virtual education program in a storage closet. The drab room, just big enough to squeeze in a tiny table, was her office at the headquarters of Seminole County (Florida) Public Schools. She had a computer and a small staff of temporary workers. Lewis, who managed to open two successful virtual schools for…

  10. Applications of Virtual Reality to Nuclear Safeguards

    SciTech Connect

    Stansfield, S.

    1998-11-03

    This paper explores two potential applications of Virtual Reality (VR) to international nuclear safeguards: training and information organization and navigation. The applications are represented by two existing prototype systems, one for training nuclear weapons dismantlement and one utilizing a VR model to facilitate intuitive access to related sets of information.

  11. The Virtual Library: Pitfalls, Promises, and Potential.

    ERIC Educational Resources Information Center

    Rooks, Dana

    1993-01-01

    Discusses components of the emerging virtual library. Highlights include adopting technology to enhance library services; navigation problems; shared resources and services; costs; implementation challenges, including library instruction programs; control over intellectual content; technical design issues; and a brief overview of current virtual…

  12. The Virtual Library: Pitfalls, Promises, and Potential.

    ERIC Educational Resources Information Center

    Rooks, Dana

    1993-01-01

    Discusses components of the emerging virtual library. Highlights include adopting technology to enhance library services; navigation problems; shared resources and services; costs; implementation challenges, including library instruction programs; control over intellectual content; technical design issues; and a brief overview of current virtual…

  13. Emphysematous lungs do not affect visibility of virtual-assisted lung mapping.

    PubMed

    Yamanashi, Keiji; Sato, Masaaki; Marumo, Satoshi; Fukui, Takamasa; Sumitomo, Ryota; Shoji, Tsuyoshi; Otake, Yosuke; Katayama, Toshiro; Huang, Cheng-Long

    2016-02-01

    It has recently been suggested that virtual-assisted lung mapping may enable safer and more reliable intraoperative navigation compared to conventional preoperative lung marking strategies. This study aimed to examine the relationship between emphysematous lungs and the intraoperative visibility of virtual-assisted lung mapping markings. We retrospectively analyzed the data of 21 patients who underwent virtual-assisted lung mapping followed by lung resection between October 2013 and May 2015. The visibility of the intraoperative lung markings was graded. The degree of pulmonary emphysema was assessed by the percentage of low attenuation area on computed tomography. We elucidated the associations between the marking grade and other factors such as patient age or sex, pulmonary lobe mapped, marking operator, Brinkman index, and percentage of low attenuation area of the pulmonary lobe. In Spearman rank correlation analysis, there was no correlation between the Brinkman index and the percentage of low attenuation area (n = 26, r = -0.016, p = 0.937). In stepwise multivariate regression analysis, the marking grade correlated with the marking operator (p < 0.001) and the Brinkman index (p = 0.008), but not with patient age or sex, the pulmonary lobe mapped, or degree of pulmonary emphysema. The skill of the marking operator and the patient's smoking history had significant effects on the intraoperative visibility of markings made by virtual-assisted lung mapping, whereas emphysematous lungs did not affect the intraoperative visibility of lung markings. © The Author(s) 2016.

  14. Short-Term Memory Maintenance of Object Locations during Active Navigation: Which Working Memory Subsystem Is Essential?

    PubMed Central

    Baumann, Oliver; Skilleter, Ashley J.; Mattingley, Jason B.

    2011-01-01

    The goal of the present study was to examine the extent to which working memory supports the maintenance of object locations during active spatial navigation. Participants were required to navigate a virtual environment and to encode the location of a target object. In the subsequent maintenance period they performed one of three secondary tasks that were designed to selectively load visual, verbal or spatial working memory subsystems. Thereafter participants re-entered the environment and navigated back to the remembered location of the target. We found that while navigation performance in participants with high navigational ability was impaired only by the spatial secondary task, navigation performance in participants with poor navigational ability was impaired equally by spatial and verbal secondary tasks. The visual secondary task had no effect on navigation performance. Our results extend current knowledge by showing that the differential engagement of working memory subsystems is determined by navigational ability. PMID:21629686

  15. Maps and navigation methods

    NASA Technical Reports Server (NTRS)

    Duval, A

    1922-01-01

    Different maps and scales are discussed with particular emphasis on their use in aviation. The author makes the observation that current navigation methods are slow and dangerous and should be replaced by scientific methods of navigation based on loxodromy and the use of the compass.

  16. Autonomous Optical Lunar Navigation

    NASA Technical Reports Server (NTRS)

    Zanetti, Renato; Crouse, Brian; D'souza, Chris

    2009-01-01

    The performance of optical autonomous navigation is investigated for low lunar orbits and for high elliptical lunar orbits. Various options for employing the camera measurements are presented and compared. Strategies for improving navigation performance are developed and applied to the Orion vehicle lunar mission

  17. The Aging Navigational System.

    PubMed

    Lester, Adam W; Moffat, Scott D; Wiener, Jan M; Barnes, Carol A; Wolbers, Thomas

    2017-08-30

    The discovery of neuronal systems dedicated to computing spatial information, composed of functionally distinct cell types such as place and grid cells, combined with an extensive body of human-based behavioral and neuroimaging research has provided us with a detailed understanding of the brain's navigation circuit. In this review, we discuss emerging evidence from rodents, non-human primates, and humans that demonstrates how cognitive aging affects the navigational computations supported by these systems. Critically, we show 1) that navigational deficits cannot solely be explained by general deficits in learning and memory, 2) that there is no uniform decline across different navigational computations, and 3) that navigational deficits might be sensitive markers for impending pathological decline. Following an introduction to the mechanisms underlying spatial navigation and how they relate to general processes of learning and memory, the review discusses how aging affects the perception and integration of spatial information, the creation and storage of memory traces for spatial information, and the use of spatial information during navigational behavior. The closing section highlights the clinical potential of behavioral and neural markers of spatial navigation, with a particular emphasis on neurodegenerative disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Navigator program risk management

    NASA Technical Reports Server (NTRS)

    Wessen, Randii R.; Padilla, Deborah A.

    2004-01-01

    In this paper, program risk management as applied to the Navigator Program: In Search of New Worlds will be discussed. The Navigator Program's goals are to learn how planetary systems form and to search for those worlds that could or do harbor life.

  19. Navigator program risk management

    NASA Technical Reports Server (NTRS)

    Wessen, Randii R.; Padilla, Deborah A.

    2004-01-01

    In this paper, program risk management as applied to the Navigator Program: In Search of New Worlds will be discussed. The Navigator Program's goals are to learn how planetary systems form and to search for those worlds that could or do harbor life.

  20. High correlation between performance on a virtual-reality simulator and real-life cataract surgery.

    PubMed

    Thomsen, Ann Sofia Skou; Smith, Phillip; Subhi, Yousif; Cour, Morten la; Tang, Lilian; Saleh, George M; Konge, Lars

    2017-05-01

    To investigate the correlation in performance of cataract surgery between a virtual-reality simulator and real-life surgery using two objective assessment tools with evidence of validity. Cataract surgeons with varying levels of experience were included in the study. All participants performed and videorecorded three standard cataract surgeries before completing a proficiency-based test on the EyeSi virtual-reality simulator. Standard cataract surgeries were defined as: (1) surgery performed under local anaesthesia, (2) patient age >60 years, and (3) visual acuity >1/60 preoperatively. A motion-tracking score was calculated by multiplying average path length and average number of movements from the three real-life surgical videos of full procedures. The EyeSi test consisted of five abstract and two procedural modules: intracapsular navigation, antitremor training, intracapsular antitremor training, forceps training, bimanual training, capsulorhexis and phaco divide and conquer. Eleven surgeons were enrolled. After a designated warm-up period, the proficiency-based test on the EyeSi simulator was strongly correlated to real-life performance measured by motion-tracking software of cataract surgical videos with a Pearson correlation coefficient of -0.70 (p = 0.017). Performance on the EyeSi simulator is significantly and highly correlated to real-life surgical performance. However, it is recommended that performance assessments are made using multiple data sources. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  1. FFTF preoperational survey. Program report

    SciTech Connect

    Twitty, B.L.; Bicehouse, H.J.

    1980-12-01

    The FFTF will become operational with criticality early in 1980. This facility is composed of the test reactor, fuel examination cells, expended fuel storage systems and fuel handling systems. The reactor and storage systems are sodium-cooled with the heat load dumped to the ambient air through heat exchangers. In order to assure that the operation of the FFTF has minimal impact on the environment, a monitoring program has been established. Prior to operation of a new facility, a preoperational environmental survey is required. It is the purpose of this report to briefly describe the environmental survey program and to provide the background data obtained during the preoperational phase of the survey program. Nine stations in the program of particular importance to FFTF are discussed in detail with results of monitoring given. No unexplained trends were noted.

  2. [Preoperative fasting guidelines: an update].

    PubMed

    López Muñoz, A C; Busto Aguirreurreta, N; Tomás Braulio, J

    2015-03-01

    Anesthesiology societies have issued various guidelines on preoperative fasting since 1990, not only to decrease the incidence of lung aspiration and anesthetic morbidity, but also to increase patient comfort prior to anesthesia. Some of these societies have been updating their guidelines, as such that, since 2010, we now have 2 evidence-based preoperative fasting guidelines available. In this article, an attempt is made to review these updated guidelines, as well as the current instructions for more controversial patients such as infants, the obese, and a particular type of ophthalmic surgery. Copyright © 2014 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  3. [Algorithm for treating preoperative anemia].

    PubMed

    Bisbe Vives, E; Basora Macaya, M

    2015-06-01

    Hemoglobin optimization and treatment of preoperative anemia in surgery with a moderate to high risk of surgical bleeding reduces the rate of transfusions and improves hemoglobin levels at discharge and can also improve postoperative outcomes. To this end, we need to schedule preoperative visits sufficiently in advance to treat the anemia. The treatment algorithm we propose comes with a simple checklist to determine whether we should refer the patient to a specialist or if we can treat the patient during the same visit. With the blood count test and additional tests for iron metabolism, inflammation parameter and glomerular filtration rate, we can decide whether to start the treatment with intravenous iron alone or erythropoietin with or without iron. With significant anemia, a visit after 15 days might be necessary to observe the response and supplement the treatment if required. The hemoglobin objective will depend on the type of surgery and the patient's characteristics.

  4. Integrated multisensor navigation systems

    NASA Technical Reports Server (NTRS)

    Vangraas, Frank

    1988-01-01

    The multisensor navigation systems research evolved from the availability of several stand alone navigation systems and the growing concern for aircraft navigation reliability and safety. The intent is to develop a multisensor navigation system during the next decade that will be capable of providing reliable aircraft position data. These data will then be transmitted directly, or by satellite, to surveillance centers to aid the process of air traffic flow control. In order to satisfy the requirements for such a system, the following issues need to be examined: performance, coverage, reliability, availability, and integrity. The presence of a multisensor navigation system in all aircraft will improve safety for the aviation community and allow for more economical operation.

  5. Intelligent navigation to improve obstetrical sonography.

    PubMed

    Yeo, Lami; Romero, Roberto

    2016-04-01

    'Manual navigation' by the operator is the standard method used to obtain information from two-dimensional and volumetric sonography. Two-dimensional sonography is highly operator dependent and requires extensive training and expertise to assess fetal anatomy properly. Most of the sonographic examination time is devoted to acquisition of images, while 'retrieval' and display of diagnostic planes occurs rapidly (essentially instantaneously). In contrast, volumetric sonography has a rapid acquisition phase, but the retrieval and display of relevant diagnostic planes is often time-consuming, tedious and challenging. We propose the term 'intelligent navigation' to refer to a new method of interrogation of a volume dataset whereby identification and selection of key anatomical landmarks allow the system to: 1) generate a geometrical reconstruction of the organ of interest; and 2) automatically navigate, find, extract and display specific diagnostic planes. This is accomplished using operator-independent algorithms that are both predictable and adaptive. Virtual Intelligent Sonographer Assistance (VIS-Assistance®) is a tool that allows operator-independent sonographic navigation and exploration of the surrounding structures in previously identified diagnostic planes. The advantage of intelligent (over manual) navigation in volumetric sonography is the short time required for both acquisition and retrieval and display of diagnostic planes. Intelligent navigation technology automatically realigns the volume, and reorients and standardizes the anatomical position, so that the fetus and the diagnostic planes are consistently displayed in the same manner each time, regardless of the fetal position or the initial orientation. Automatic labeling of anatomical structures, subject orientation and each of the diagnostic planes is also possible. Intelligent navigation technology can operate on conventional computers, and is not dependent on specific ultrasound platforms or on the

  6. Virtual seminars

    NASA Astrophysics Data System (ADS)

    Nelson, H. Roice

    1997-06-01

    A virtual seminar (SM) is an economic and effective instructional tool for teaching students who are at a distance from their instructor. Like conventional class room teaching, a virtual seminar requires an instructor, a student, and a method of communication. Teleconferencing, video conferencing, intranets and the Internet give learners in a Virtual Seminar the ability to interact immediately with their mentors and receive real and relevant answers. This paper shows how industry and academia can benefit from using methods developed and experience gained in presenting the first virtual seminars to academic and petroleum industry participants in mid-1996. The information explosion in industry means that business or technical information is worthless until it is assimilated into a corporate knowledge management system. A search for specific information often turns into a filtering exercise or an attempt to find patterns and classify retrieved material. In the setting of an interactive corporate information system, virtual seminars meet the need for a productive new relationship between creative people and the flux of corporate knowledge. Experience shows that it is more efficient to circulate timesensitive and confidential information electronically through a virtual seminar. Automating the classification of information and removing that task from the usual work load creates an electronic corporate memory and enhances the value of the knowledge to both users and a corporation. Catalogued benchmarks, best-practice standards, and Knowledge Maps (SM) of experience serve as key aids to communicating knowledge through virtual seminars and converting that knowledge into a profit-making asset.

  7. Frontal alignment in total knee arthroplasty. Comparative study between radiographic measurement and surgical navigation.

    PubMed

    Hernandez-Vaquero, D; Noriega-Fernandez, A; Suarez-Vazquez, A; Roncero-Gonzalez, S; Sierra-Pereira, A A; Gil-Martinez, L; Fernandez-Carreira, J M

    To establish the concordance between angulation of the femoro-tibial mechanical axis measured with x-rays and surgical navigation in both the pre and postoperative period after a total knee arthroplasty (TKA) was implanted. Pre and postoperative measurements were analyzed in 88 TKA of the same model and all performed with the same surgical navigation system. The mechanical frontal angle (MFA) and femoro-tibial anatomic angle were measured before and after the TKA. The angulation was digitally measured with a teleradiography. In the navigation, the femoro-tibial angle at rest, forced varus and valgus were registered and the average of these three measurements was calculated. The mean preoperative MFA measured on the radiograph was 4.55°. The mean of the same angle measured on the postoperative radiograph was 1.72°, (p=0.05). The mean of the MFA measured with navigation before TKA was 3.12° and after the implant with navigation was 0.53 (P=.013). The concordance coefficient between the MFA in teleradiography and in navigation was 0.869 (P<.001) preoperatively and 0.709 postoperatively (P=.017). We found a strong concordance between radiographic and surgical navigation measurements of the MFA. This may imply that teleradiography is not necessary when using surgical navigation in TKA. Copyright © 2017 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. Comparison of Precision between Optical and Electromagnetic Navigation Systems in Total Knee Arthroplasty

    PubMed Central

    Rhee, Seung Joon; Park, Shi Hwan; Cho, He Myung

    2014-01-01

    Purpose The purpose of this study is to compare and analyze the precision of optical and electromagnetic navigation systems in total knee arthroplasty (TKA). Materials and Methods We retrospectively reviewed 60 patients who underwent TKA using an optical navigation system and 60 patients who underwent TKA using an electromagnetic navigation system from June 2010 to March 2012. The mechanical axis that was measured on preoperative radiographs and by the intraoperative navigation systems were compared between the groups. The postoperative positions of the femoral and tibial components in the sagittal and coronal plane were assessed. Results The difference of the mechanical axis measured on the preoperative radiograph and by the intraoperative navigation systems was 0.6 degrees more varus in the electromagnetic navigation system group than in the optical navigation system group, but showed no statistically significant difference between the two groups (p>0.05). The positions of the femoral and tibial components in the sagittal and coronal planes on the postoperative radiographs also showed no statistically significant difference between the two groups (p>0.05). Conclusions In TKA, both optical and electromagnetic navigation systems showed high accuracy and reproducibility, and the measurements from the postoperative radiographs showed no significant difference between the two groups. PMID:25505703

  9. Multimedia for mobile environment: image enhanced navigation

    NASA Astrophysics Data System (ADS)

    Gautam, Shantanu; Sarkis, Gabi; Tjandranegara, Edwin; Zelkowitz, Evan; Lu, Yung-Hsiang; Delp, Edward J.

    2006-01-01

    As mobile systems (such as laptops and mobile telephones) continue growing, navigation assistance and location-based services are becoming increasingly important. Existing technology allow mobile users to access Internet services (e.g. email and web surfing), simple multimedia services (e.g. music and video clips), and make telephone calls. However, the potential of advanced multimedia services has not been fully developed, especially multimedia for navigation or location based services. At Purdue University, we are developing an image database, known as LAID, in which every image is annotated with its location, compass heading, acquisition time, and weather conditions. LAID can be used to study several types of navigation problems: A mobile user can take an image and transmit the image to the LAID sever. The server compares the image with the images stored in the database to determine where the user is located. We refer to this as the "forward" navigation problem. The second type of problem is to provide a "virtual tour on demand". A user inputs a starting and an ending addresses and LAID retrieves the images along a route that connects the two addresses. This is a generalization of route planning. Our database currently contains over 20000 images and covers approximately 25% of the city of West Lafayette, Indiana.

  10. Learning to navigate: experience versus maps.

    PubMed

    Meilinger, Tobias; Frankenstein, Julia; Bülthoff, Heinrich H

    2013-10-01

    People use "route knowledge" to navigate to targets along familiar routes and "survey knowledge" to determine (by pointing, for example) a target's metric location. We show that both root in separate memories of the same environment: participants navigating through their home city relied on representations and reference frames different from those they used when doing a matched survey task. Tübingen residents recalled their way along a familiar route to a distant target while located in a photorealistic virtual 3D model of Tübingen, indicating their route decisions on a keyboard. Participants had previously done a survey task (pointing) using the same start points and targets. Errors and response latencies observed in route recall were completely unrelated to errors and latencies in pointing. This suggests participants employed different and independent representations for each task. Further, participants made fewer routing errors when asked to respond from a horizontal walking perspective rather than a constant aerial perspective. This suggests that instead of the single reference, north-up frame (similar to a conventional map) they used in the survey task, participants employed different, and most probably multiple, reference frames learned from "on the ground" navigating experience. The implication is that, within their everyday environment, people use map or navigation-based knowledge according to which best suits the task. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Spatial Navigation in Preclinical Alzheimer's Disease.

    PubMed

    Allison, Samantha L; Fagan, Anne M; Morris, John C; Head, Denise

    2016-02-09

    Although several previous studies have demonstrated navigational deficits in early-stage symptomatic Alzheimer's disease (AD), navigational abilities in preclinical AD have not been examined. The present investigation examined the effects of preclinical AD and early-stage symptomatic AD on spatial navigation performance. Performance on tasks of wayfinding and route learning in a virtual reality environment were examined. Comparisons were made across the following three groups: Clinically normal without preclinical AD (n = 42), clinically normal with preclinical AD (n = 13), and early-stage symptomatic AD (n = 16) groups. Preclinical AD was defined based on cerebrospinal fluid Aβ42 levels below 500 pg/ml. Preclinical AD was associated with deficits in the use of a wayfinding strategy, but not a route learning strategy. Moreover, post-hoc analyses indicated that wayfinding performance had moderate sensitivity and specificity. Results also confirmed early-stage symptomatic AD-related deficits in the use of both wayfinding and route learning strategies. The results of this study suggest that aspects of spatial navigation may be particularly sensitive at detecting the earliest cognitive deficits of AD.

  12. Grid-like Processing of Imagined Navigation

    PubMed Central

    Horner, Aidan J.; Bisby, James A.; Zotow, Ewa; Bush, Daniel; Burgess, Neil

    2016-01-01

    Summary Grid cells in the entorhinal cortex (EC) of rodents [1] and humans [2] fire in a hexagonally distributed spatially periodic manner. In concert with other spatial cells in the medial temporal lobe (MTL) [3, 4, 5, 6], they provide a representation of our location within an environment [7, 8] and are specifically thought to allow the represented location to be updated by self-motion [9]. Grid-like signals have been seen throughout the autobiographical memory system [10], suggesting a much more general role in memory [11, 12]. Grid cells may allow us to move our viewpoint in imagination [13], a useful function for goal-directed navigation and planning [12, 14, 15, 16], and episodic future thinking more generally [17, 18]. We used fMRI to provide evidence for similar grid-like signals in human entorhinal cortex during both virtual navigation and imagined navigation of the same paths. We show that this signal is present in periods of active navigation and imagination, with a similar orientation in both and with the specifically 6-fold rotational symmetry characteristic of grid cell firing. We therefore provide the first evidence suggesting that grid cells are utilized during movement of viewpoint within imagery, potentially underpinning our more general ability to mentally traverse possible routes in the service of planning and episodic future thinking. PMID:26972318

  13. Indocyanine green fluorescence-navigated robotic segmentectomy.

    PubMed

    Hsieh, Chen-Ping; Liu, Yun-Hen; Wu, Yi-Cheng; Hsieh, Ming-Ju; Chao, Yin-Kai

    2017-08-01

    Pulmonary segmentectomy with radical lymphadenopathy has been considered effective to manage small primary lung cancers [1, 2]. This procedure provides the advantages of minimal invasive surgery and is reported sufficient for safe margin. However, segmentectomy is more difficult to be performed than lobectomy because intersegmental plane cannot be detected easily. Several methods have been reported for identifying the actual intersegmental plane [3-7], but the sensitivity of these methods is limited to the lung conditions like patients with emphysematous lung and needed skilled surgeon to perform. We demonstrated the technique of visualizing the intersegmental plane via fluorescence navigated with indocyanine green (ICG) injection intravenously during robotic S6 segmentectomy. This video presents a case that 70-year-old male who has past history of rectal cancer status post-LAR in 1991, HCC status post-RFA, and hepatitis C was found a lung nodule over superior segment of left lower lobe during regular examination. The nodule was considered metastatic tumor preoperatively. The segmental pulmonary artery and pulmonary bronchus to superior segment of left lower lobe were ligated firstly, and the intersegmental plane was seen clearly after ICG injection intravenously under fluorescence navigated. Intersegmental plane was marked by electrocautery, and then, the target segment was resected by endostapler. Patient tolerated the procedure well. Chest tube was removed by postoperative day 3, and he was discharged smoothly by postoperative day 5. There were no complications. Postoperative chest X-ray revealed good lung expansion. Not as preoperative expectation, the final pathology was consistent with caseating granulomatous inflammation. It is difficult to identify intersegmental plane during segmentectomy. ICG fluorescence-navigated segmentectomy provides immediate visualization of the intersegmental plane and makes the procedure easy and fast.

  14. Neural correlates of virtual route recognition in congenital blindness.

    PubMed

    Kupers, Ron; Chebat, Daniel R; Madsen, Kristoffer H; Paulson, Olaf B; Ptito, Maurice

    2010-07-13

    Despite the importance of vision for spatial navigation, blind subjects retain the ability to represent spatial information and to move independently in space to localize and reach targets. However, the neural correlates of navigation in subjects lacking vision remain elusive. We therefore used functional MRI (fMRI) to explore the cortical network underlying successful navigation in blind subjects. We first trained congenitally blind and blindfolded sighted control subjects to perform a virtual navigation task with the tongue display unit (TDU), a tactile-to-vision sensory substitution device that translates a visual image into electrotactile stimulation applied to the tongue. After training, participants repeated the navigation task during fMRI. Although both groups successfully learned to use the TDU in the virtual navigation task, the brain activation patterns showed substantial differences. Blind but not blindfolded sighted control subjects activated the parahippocampus and visual cortex during navigation, areas that are recruited during topographical learning and spatial representation in sighted subjects. When the navigation task was performed under full vision in a second group of sighted participants, the activation pattern strongly resembled the one obtained in the blind when using the TDU. This suggests that in the absence of vision, cross-modal plasticity permits the recruitment of the same cortical network used for spatial navigation tasks in sighted subjects.

  15. Directing crowd simulations using navigation fields.

    PubMed

    Patil, Sachin; Berg, Jur van den; Curtis, Sean; Lin, Ming C; Manocha, Dinesh

    2011-02-01

    We present a novel approach to direct and control virtual crowds using navigation fields. Our method guides one or more agents toward desired goals based on guidance fields. The system allows the user to specify these fields by either sketching paths directly in the scene via an intuitive authoring interface or by importing motion flow fields extracted from crowd video footage. We propose a novel formulation to blend input guidance fields to create singularity-free, goal-directed navigation fields. Our method can be easily combined with the most current local collision avoidance methods and we use two such methods as examples to highlight the potential of our approach. We illustrate its performance on several simulation scenarios.

  16. Algorithm for navigated ESS.

    PubMed

    Baudoin, T; Grgić, M V; Zadravec, D; Geber, G; Tomljenović, D; Kalogjera, L

    2013-12-01

    ENT navigation has given new opportunities in performing Endoscopic Sinus Surgery (ESS) and improving surgical outcome of the patients` treatment. ESS assisted by a navigation system could be called Navigated Endoscopic Sinus Surgery (NESS). As it is generally accepted that the NESS should be performed only in cases of complex anatomy and pathology, it has not yet been established as a state-of-the-art procedure and thus not used on a daily basis. This paper presents an algorithm for use of a navigation system for basic ESS in the treatment of chronic rhinosinusitis (CRS). The algorithm includes five units that should be highlighted using a navigation system. They are as follows: 1) nasal vestibule unit, 2) OMC unit, 3) anterior ethmoid unit, 4) posterior ethmoid unit, and 5) sphenoid unit. Each unit has a shape of a triangular pyramid and consists of at least four reference points or landmarks. As many landmarks as possible should be marked when determining one of the five units. Navigated orientation in each unit should always precede any surgical intervention. The algorithm should improve the learning curve of trainees and enable surgeons to use the navigation system routinely and systematically.

  17. Do psychological interventions reduce preoperative anxiety?

    PubMed

    Renouf, Tessa; Leary, Alison; Wiseman, Theresa

    The systematic review investigates whether, during preoperative assessments, nurse-delivered psychological interventions reduce anxiety levels preoperatively for patients undergoing elective surgery. Seventeen studies met the inclusion criteria for data extraction and in-depth critiquing. Of these, two were discarded due to lack of validity, while the remaining studies were organised thematically in a narrative synthesis, generating two principal results: patients' preoperative anxieties were lowered by nurse-delivered general preoperative psychological interventions; and patients valued individualised preoperative interventions delivered by nurses. However, the single oncology study in the review showed an elevation in preoperative anxiety, regardless of intervention, and highlights the need for more research in this under-reviewed area. In the meantime, the authors believe that service improvements should be implemented to ensure that, where possible, psychological preoperative interventions are individualised.

  18. Virtual Teams.

    ERIC Educational Resources Information Center

    Geber, Beverly

    1995-01-01

    Virtual work teams scattered around the globe are becoming a feature of corporate workplaces. Although most people prefer face-to-face meetings and interactions, reality often requires telecommuting. (JOW)

  19. Virtual Worlds for Virtual Organizing

    NASA Astrophysics Data System (ADS)

    Rhoten, Diana; Lutters, Wayne

    The members and resources of a virtual organization are dispersed across time and space, yet they function as a coherent entity through the use of technologies, networks, and alliances. As virtual organizations proliferate and become increasingly important in society, many may exploit the technical architecture s of virtual worlds, which are the confluence of computer-mediated communication, telepresence, and virtual reality originally created for gaming. A brief socio-technical history describes their early origins and the waves of progress followed by stasis that brought us to the current period of renewed enthusiasm. Examination of contemporary examples demonstrates how three genres of virtual worlds have enabled new arenas for virtual organizing: developer-defined closed worlds, user-modifiable quasi-open worlds, and user-generated open worlds. Among expected future trends are an increase in collaboration born virtually rather than imported from existing organizations, a tension between high-fidelity recreations of the physical world and hyper-stylized imaginations of fantasy worlds, and the growth of specialized worlds optimized for particular sectors, companies, or cultures.

  20. Navigation lights color study

    NASA Astrophysics Data System (ADS)

    Barbosa, Jose G.; Alberg, Matthew T.

    2015-05-01

    The chromaticity of navigation lights are defined by areas on the International Commission on Illumination (CIE) 1931 chromaticity diagram. The corner coordinates for these areas are specified in the International Regulations for Prevention of Collisions at Sea, 1972 (72 COLREGS). The navigation light's color of white, red, green, and yellow are bounded by these areas. The chromaticity values specified by the COLREGS for navigation lights were intended for the human visual system (HVS). The HVS can determine the colors of these lights easily under various conditions. For digital color camera imaging systems the colors of these lights are dependent on the camera's color spectral sensitivity, settings, and color correction. At night the color of these lights are used to quickly determine the relative course of vessels. If these lights are incorrectly identified or there is a delay in identifying them this could be a potential safety of ship concern. Vessels that use camera imaging systems exclusively for sight, at night, need to detect, identify, and discriminate navigation lights for navigation and collision avoidance. The introduction of light emitting diode (LED) lights and lights with different spectral signatures have the potential to be imaged very differently with an RGB color filter array (CFA) color camera than with the human eye. It has been found that some green navigation lights' images appear blue verse green. This has an impact on vessels that use camera imaging systems exclusively for navigation. This paper will characterize color cameras ability to properly reproducing navigation lights' color and survey a set of navigation light to determine if they conform to the COLREGS.

  1. Virtual memory

    NASA Technical Reports Server (NTRS)

    Denning, P. J.

    1986-01-01

    Virtual memory was conceived as a way to automate overlaying of program segments. Modern computers have very large main memories, but need automatic solutions to the relocation and protection problems. Virtual memory serves this need as well and is thus useful in computers of all sizes. The history of the idea is traced, showing how it has become a widespread, little noticed feature of computers today.

  2. Space shuttle navigation analysis

    NASA Technical Reports Server (NTRS)

    Jones, H. L.; Luders, G.; Matchett, G. A.; Sciabarrasi, J. E.

    1976-01-01

    A detailed analysis of space shuttle navigation for each of the major mission phases is presented. A covariance analysis program for prelaunch IMU calibration and alignment for the orbital flight tests (OFT) is described, and a partial error budget is presented. The ascent, orbital operations and deorbit maneuver study considered GPS-aided inertial navigation in the Phase III GPS (1984+) time frame. The entry and landing study evaluated navigation performance for the OFT baseline system. Detailed error budgets and sensitivity analyses are provided for both the ascent and entry studies.

  3. Spacecraft Guidance, Navigation, and Control Visualization Tool

    NASA Technical Reports Server (NTRS)

    Mandic, Milan; Acikmese, Behcet; Blackmore, Lars

    2011-01-01

    G-View is a 3D visualization tool for supporting spacecraft guidance, navigation, and control (GN&C) simulations relevant to small-body exploration and sampling (see figure). The tool is developed in MATLAB using Virtual Reality Toolbox and provides users with the ability to visualize the behavior of their simulations, regardless of which programming language (or machine) is used to generate simulation results. The only requirement is that multi-body simulation data is generated and placed in the proper format before applying G-View.

  4. Update on Preoperative Breast Localization.

    PubMed

    Hayes, Mary K

    2017-05-01

    The radiologist plays an important role in detection, diagnosis, localization, pathologic correlation, and follow-up imaging of breast cancer. A successful breast surgical treatment program relies on the image guidance tools and skills of the radiologist and surgeon. This article reviews the evolving tools available for preoperative localization. Non-wire devices provide a safe, efficient, noninferior alternative to wire localization and can be placed 0 to 30 days before scheduled surgery. This technology may evolve to other longer-term, efficient, and cost-effective applications for patients who require neoadjuvant treatment or who have findings visible only at MR imaging. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Preoperative optimization and risk assessment.

    PubMed

    Nicholas, Joseph A

    2014-05-01

    Because most older adults with hip fractures require urgent surgical intervention, the preoperative medical evaluation focuses on the exclusion of the small number of contraindications to surgery, and rapid optimization of patients for operative repair. Although many geriatric fracture patients have significant chronic medical comorbidities, most patients can be safely stabilized for surgery with medical and orthopedic comanagement by anticipating a small number of common physiologic responses and perioperative complications. In addition to estimating perioperative risk, the team should focus on intravascular volume restoration, pain control, and avoidance of perioperative hypotension. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Preoperative Evaluation for Noncardiac Surgery.

    PubMed

    Cohn, Steven L

    2016-12-06

    This issue provides a clinical overview of preoperative evaluation for noncardiac surgery, focusing on risk factors, elements of evaluation, medication management, and practice improvement. The content of In the Clinic is drawn from the clinical information and education resources of the American College of Physicians (ACP), including MKSAP (Medical Knowledge and Self-Assessment Program). Annals of Internal Medicine editors develop In the Clinic in collaboration with the ACP's Medical Education and Publishing divisions and with the assistance of additional science writers and physician writers.

  7. Preoperation anxiety: a qualitative analysis

    PubMed Central

    Bodley, P. O.; Jones, H. V. R.; Mather, M. D.

    1974-01-01

    Twenty-eight patients were investigated psychologically before surgery. The purposes of the study were (1) to discover the nature of preoperative anxiety, and (2) to compare direct questioning with an indirect method. The merits and shortcomings of the two types of assessment emerged. The findings suggest that, in addition to worries about the operation and the anaesthetic, there was concern about leaving the home and family, which was accentuated by lack of communication and contact with hospital staff, including the surgical team. Pain was found to have a variety of implications including loneliness. These and other findings are discussed in relation to psychological theories. PMID:4819911

  8. Virtual Specimens

    NASA Astrophysics Data System (ADS)

    de Paor, D. G.

    2009-12-01

    Virtual Field Trips have been around almost as long as the Worldwide Web itself yet virtual explorers do not generally return to their desktops with folders full of virtual hand specimens. Collection of real specimens on fields trips for later analysis in the lab (or at least in the pub) has been an important part of classical field geoscience education and research for generations but concern for the landscape and for preservation of key outcrops from wanton destruction has lead to many restrictions. One of the author’s favorite outcrops was recently vandalized presumably by a geologist who felt the need to bash some of the world’s most spectacular buckle folds with a rock sledge. It is not surprising, therefore, that geologists sometimes leave fragile localities out of field trip itineraries. Once analyzed, most specimens repose in drawers or bins, never to be seen again. Some end up in teaching collections but recent pedagogical research shows that undergraduate students have difficulty relating specimens both to their collection location and ultimate provenance in the lithosphere. Virtual specimens can be created using 3D modeling software and imported into virtual globes such as Google Earth (GE) where, they may be linked to virtual field trip stops or restored to their source localities on the paleo-globe. Sensitive localities may be protected by placemark approximation. The GE application program interface (API) has a distinct advantage over the stand-alone GE application when it comes to viewing and manipulating virtual specimens. When instances of the virtual globe are embedded in web pages using the GE plug-in, Collada models of specimens can be manipulated with javascript controls residing in the enclosing HTML, permitting specimens to be magnified, rotated in 3D, and sliced. Associated analytical data may be linked into javascript and localities for comparison at various points on the globe referenced by ‘fetching’ KML. Virtual specimens open up

  9. Navigating Ski Slopes Safely

    MedlinePlus

    ... medlineplus.gov/news/fullstory_162902.html Navigating Ski Slopes Safely National Ski Areas Association offers advice on ... 2017 (HealthDay News) -- Many people head for the slopes at the first sign of snow, but it's ...

  10. Spatial cognition and navigation

    NASA Technical Reports Server (NTRS)

    Aretz, Anthony J.

    1989-01-01

    An experiment that provides data for the development of a cognitive model of pilot flight navigation is described. The experiment characterizes navigational awareness as the mental alignment of two frames of reference: (1) the ego centered reference frame that is established by the forward view out of the cockpit and (2) the world centered reference frame that is established by the aircraft's location on a map. The data support a model involving at least two components: (1) the perceptual encoding of the navigational landmarks and (2) the mental rotation of the map's world reference frame into alignment with the ego centered reference frame. The quantitative relationships of these two factors are provided as possible inputs for a computational model of spatial cognition during flight navigation.

  11. Spatial cognition and navigation

    NASA Technical Reports Server (NTRS)

    Aretz, Anthony J.

    1989-01-01

    An experiment that provides data for the development of a cognitive model of pilot flight navigation is described. The experiment characterizes navigational awareness as the mental alignment of two frames of reference: (1) the ego centered reference frame that is established by the forward view out of the cockpit and (2) the world centered reference frame that is established by the aircraft's location on a map. The data support a model involving at least two components: (1) the perceptual encoding of the navigational landmarks and (2) the mental rotation of the map's world reference frame into alignment with the ego centered reference frame. The quantitative relationships of these two factors are provided as possible inputs for a computational model of spatial cognition during flight navigation.

  12. Navigating the System

    MedlinePlus

    ... Text Size Print Navigating The System What You Need to Know to Work the System Here are ... confidentiality. Keep track of all the services you access and be knowledgeable about them. If you are ...

  13. Navigated unicompartmental knee replacement.

    PubMed

    Jenny, Jean-Yves

    2008-06-01

    Computer-aided systems have been developed recently to improve the precision of implantation of unicompartmental knee replacement (UKR) or total knee replacement. Minimal invasive techniques have been developed to decrease the surgical trauma related to the prosthesis implantation. However, there might be a concern about the potential of minimal invasive techniques for a loss of accuracy. Navigation systems might address this issue. We are currently using routinely a nonimage-based navigation for total knee replacement. We developed a modified system for UKR, suitable for either a conventional or a mini-invasive approach. Navigated implantation of a UKR allowed improving the accuracy of the radiologic implantation. Mini-invasive implantation was effective, but the accuracy may not reach that of the conventional navigated technique and should be still improved. Minimal invasive techniques have to be validated because a loss of accuracy will negatively influence long-term outcomes.

  14. Virtual reality in neurologic rehabilitation of spatial disorientation

    PubMed Central

    2013-01-01

    Background Topographical disorientation (TD) is a severe and persistent impairment of spatial orientation and navigation in familiar as well as new environments and a common consequence of brain damage. Virtual reality (VR) provides a new tool for the assessment and rehabilitation of TD. In VR training programs different degrees of active motor control over navigation may be implemented (i.e. more passive spatial navigation vs. more active). Increasing demands of active motor control may overload those visuo-spatial resources necessary for learning spatial orientation and navigation. In the present study we used a VR-based verbally-guided passive navigation training program to improve general spatial abilities in neurologic patients with spatial disorientation. Methods Eleven neurologic patients with focal brain lesions, which showed deficits in spatial orientation, as well as 11 neurologic healthy controls performed a route finding training in a virtual environment. Participants learned and recalled different routes for navigation in a virtual city over five training sessions. Before and after VR training, general spatial abilities were assessed with standardized neuropsychological tests. Results Route finding ability in the VR task increased over the five training sessions. Moreover, both groups improved different aspects of spatial abilities after VR training in comparison to the spatial performance before VR training. Conclusions Verbally-guided passive navigation training in VR enhances general spatial cognition in neurologic patients with spatial disorientation as well as in healthy controls and can therefore be useful in the rehabilitation of spatial deficits associated with TD. PMID:23394289

  15. Community and Virtual Community.

    ERIC Educational Resources Information Center

    Ellis, David; Oldridge, Rachel; Vasconcelos, Ana

    2004-01-01

    Presents a literature review that covers the following topics related to virtual communities: (1) information and virtual community; (2) virtual communities and communities of practice; (3) virtual communities and virtual arenas, including virtual community networks; and (4) networked virtual communities. (Contains 175 references.) (MES)

  16. Automated Satellite Image Navigation

    DTIC Science & Technology

    1992-12-01

    3b TIME . Master’s Thesis I . December 1992 16 SUPPIEMENoARY NOATIO; The views expressed in this thesis are those of the author and do not reflect...demand greater navigational accuracy. At the same time there is an increasing operational requirement to attain this greater accuracy via a method that is...resolution of Advanced Very High Resolution Radiometer (AVHRR) images (1.1 km) can be achieved. This "optimal" navigation has been achieved by the

  17. Onboard Navigation Systems Characteristics

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The space shuttle onboard navigation systems characteristics are described. A standard source of equations and numerical data for use in error analyses and mission simulations related to space shuttle development is reported. The sensor characteristics described are used for shuttle onboard navigation performance assessment. The use of complete models in the studies depend on the analyses to be performed, the capabilities of the computer programs, and the availability of computer resources.

  18. Stellar Inertial Navigation Workstation

    NASA Technical Reports Server (NTRS)

    Johnson, W.; Johnson, B.; Swaminathan, N.

    1989-01-01

    Software and hardware assembled to support specific engineering activities. Stellar Inertial Navigation Workstation (SINW) is integrated computer workstation providing systems and engineering support functions for Space Shuttle guidance and navigation-system logistics, repair, and procurement activities. Consists of personal-computer hardware, packaged software, and custom software integrated together into user-friendly, menu-driven system. Designed to operate on IBM PC XT. Applied in business and industry to develop similar workstations.

  19. USACE Navigation Strategic Vision

    DTIC Science & Technology

    2012-12-01

    Initiatives ( SNI ) within these Objectives. Figure 2 illustrates the relationship of SNI to the focus areas and guiding documents, the USACE Campaign...appreciation of the value provided by the MTS and proactive participation with the USACE navigation program. Figure 2. Strategic Navigation Initiatives ( SNI ...Campaign Plan Goal 5, Objective 4a, the CW Strategic Plan Goal 5, and NSV Objective 4 and two supporting SNIs .   7 Objective: Create an inventory of all

  20. Odometry and insect navigation.

    PubMed

    Wolf, Harald

    2011-05-15

    Animals have needed to find their way about almost since a free-living life style evolved. Particularly, if an animal has a home--shelter or nesting site--true navigation becomes necessary to shuttle between this home and areas of other activities, such as feeding. As old as navigation is in the animal kingdom, as diverse are its mechanisms and implementations, depending on an organism's ecology and its endowment with sensors and actuators. The use of landmarks for piloting or the use of trail pheromones for route following have been examined in great detail and in a variety of animal species. The same is true for senses of direction--the compasses for navigation--and the construction of vectors for navigation from compass and distance cues. The measurement of distance itself--odometry--has received much less attention. The present review addresses some recent progress in the understanding of odometers in invertebrates, after outlining general principles of navigation to put odometry in its proper context. Finally, a number of refinements that increase navigation accuracy and safety are addressed.

  1. Music interventions for preoperative anxiety.

    PubMed

    Bradt, Joke; Dileo, Cheryl; Shim, Minjung

    2013-06-06

    Patients awaiting surgical procedures often experience significant anxiety. Such anxiety may result in negative physiological manifestations, slower wound healing, increased risk of infection, and may complicate the induction of anaesthesia and impede postoperative recovery. To reduce patient anxiety, sedatives and anti-anxiety drugs are regularly administered before surgery. However, these often have negative side effects and may prolong patient recovery. Therefore, increasing attention is being paid to a variety of non-pharmacological interventions for reduction of preoperative anxiety such as music therapy and music medicine interventions. Interventions are categorized as 'music medicine' when passive listening to pre-recorded music is offered by medical personnel. In contrast, music therapy requires the implementation of a music intervention by a trained music therapist, the presence of a therapeutic process, and the use of personally tailored music experiences. A systematic review was needed to gauge the efficacy of both music therapy and music medicine interventions for reduction of preoperative anxiety. To examine the effects of music interventions with standard care versus standard care alone on preoperative anxiety in surgical patients. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 7), MEDLINE (1950 to August 2012), CINAHL (1980 to August 2012), AMED (1985 to April 2011; we no longer had access to AMED after this date), EMBASE (1980 to August 2012), PsycINFO (1967 to August 2012), LILACS (1982 to August 2012), Science Citation Index (1980 to August 2012), the specialist music therapy research database (March 1 2008; database is no longer functional), CAIRSS for Music (to August 2012), Proquest Digital Dissertations (1980 to August 2012), ClinicalTrials.gov (2000 to August 2012), Current Controlled Trials (1998 to August 2012), and the National Research Register (2000 to September 2007). We

  2. Tours in Virtual Globes

    NASA Astrophysics Data System (ADS)

    Treves, R.

    2009-12-01

    The most significant new feature to appear in Google Earth 5.0 in February was the tour feature, it can produce eye catching and appealing animations as was shown by the Apollo 11 Tour which shows a model of the lunar module descending to the surface of the moon. It allows users to record themselves navigating around Google Earth switching elements on and off. The use of the tour functionality goes beyond exciting animations, it has important applications as a way of; introducing users to a larger data set presented in a Virtual Globe, offering an alternative to PowerPoint as a platform to support presentations and as a quick way to produce powerful visualizations for education purposes. In this talk I will explore how best to use to tours to present a range of spatial data and examine how the Google Earth tour compares to similar functionality that is appearing in other Virtual Globes and other 3D environments such as Second Life.

  3. Total autogenous mandibular reconstruction using virtual surgical planning.

    PubMed

    Winters, Ryan; Saad, Adam; Beahm, Donald David; Wise, Matthew Whitten; St Hilaire, Hugo

    2012-09-01

    Free fibula transfer has become the workhorse in mandibular reconstruction. Total mandibular reconstruction is an uncommon procedure with added complexity. Numerous techniques have been described for such reconstruction, many requiring a temporomandibular joint prosthesis. We present a novel method where simultaneous bilateral free fibula transfer utilizing preoperative virtual surgical planning was used to produce a total autogenous reconstruction. The virtual surgical planning allows to effectively quantify the bone stock required preoperatively and facilitates intraoperative modeling of the fibula. Therefore, a more anatomically correct reconstruction is obtained resulting in improved functional and aesthetic outcomes.

  4. A systematic investigation of navigation impairment in chronic stroke patients: Evidence for three distinct types.

    PubMed

    Claessen, Michiel H G; Visser-Meily, Johanna M A; Meilinger, Tobias; Postma, Albert; de Rooij, Nicolien K; van der Ham, Ineke J M

    2017-08-01

    In a recent systematic review, Claessen and van der Ham (2017) have analyzed the types of navigation impairment in the single-case study literature. Three dissociable types related to landmarks, locations, and paths were identified. This recent model as well as previous models of navigation impairment have never been verified in a systematic manner. The aim of the current study was thus to investigate the prevalence of landmark-based, location-based, and path-based navigation impairment in a large sample of stroke patients. Navigation ability of 77 stroke patients in the chronic phase and 60 healthy participants was comprehensively evaluated using the Virtual Tübingen test, which contains twelve subtasks addressing various aspects of knowledge about landmarks, locations, and paths based on a newly learned virtual route. Participants also filled out the Wayfinding Questionnaire to allow for making a distinction between stroke patients with and without significant subjective navigation-related complaints. Analysis of responses on the Wayfinding Questionnaire indicated that 33 of the 77 participating stroke patients had significant navigation-related complaints. An examination of their performance on the Virtual Tübingen test established objective evidence for navigation impairment in 27 patients. Both landmark-based and path-based navigation impairment occurred in isolation, while location-based navigation impairment was only found along with the other two types. The current study provides the first empirical support for the distinction between landmark-based, location-based, and path-based navigation impairment. Future research relying on other assessment instruments of navigation ability might be helpful to further validate this distinction. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Virtual Violence.

    PubMed

    2016-08-01

    In the United States, exposure to media violence is becoming an inescapable component of children's lives. With the rise in new technologies, such as tablets and new gaming platforms, children and adolescents increasingly are exposed to what is known as "virtual violence." This form of violence is not experienced physically; rather, it is experienced in realistic ways via new technology and ever more intense and realistic games. The American Academy of Pediatrics continues to be concerned about children's exposure to virtual violence and the effect it has on their overall health and well-being. This policy statement aims to summarize the current state of scientific knowledge regarding the effects of virtual violence on children's attitudes and behaviors and to make specific recommendations for pediatricians, parents, industry, and policy makers.

  6. Virtual Tower

    SciTech Connect

    Wayne, R.A.

    1997-08-01

    The primary responsibility of an intrusion detection system (IDS) operator is to monitor the system, assess alarms, and summon and coordinate the response team when a threat is acknowledged. The tools currently provided to the operator are somewhat limited: monitors must be switched, keystrokes must be entered to call up intrusion sensor data, and communication with the response force must be maintained. The Virtual tower is an operator interface assembled from low-cost commercial-off-the-shelf hardware and software; it enables large amounts of data to be displayed in a virtual manner that provides instant recognition for the operator and increases assessment accuracy in alarm annunciator and control systems. This is accomplished by correlating and fusing the data into a 360-degree visual representation that employs color, auxiliary attributes, video, and directional audio to prompt the operator. The Virtual Tower would be a valuable low-cost enhancement to existing systems.

  7. 33 CFR 401.35 - Navigation underway.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Navigation underway. 401.35 Section 401.35 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.35 Navigation...

  8. 33 CFR 401.35 - Navigation underway.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Navigation underway. 401.35 Section 401.35 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.35 Navigation...

  9. 33 CFR 401.35 - Navigation underway.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Navigation underway. 401.35 Section 401.35 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.35 Navigation...

  10. 33 CFR 401.35 - Navigation underway.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Navigation underway. 401.35 Section 401.35 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.35 Navigation...

  11. 33 CFR 401.35 - Navigation underway.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Navigation underway. 401.35 Section 401.35 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.35 Navigation...

  12. Preoperative anemia and postoperative outcomes after hepatectomy

    PubMed Central

    Tohme, Samer; Varley, Patrick R.; Landsittel, Douglas P.; Chidi, Alexis P.; Tsung, Allan

    2015-01-01

    Background Preoperative anaemia is associated with adverse outcomes after surgery but outcomes after liver surgery specifically are not well established. We aimed to analyze the incidence of and effects of preoperative anemia on morbidity and mortality in patients undergoing liver resection. Methods All elective hepatectomies performed for the period 2005–2012 recorded in the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database were evaluated. We obtained anonymized data for 30-day mortality and major morbidity (one or more major complication), demographics, and preoperative and perioperative risk factors. We used multivariable logistic regression models to assess the adjusted effect of anemia, which was defined as (hematocrit <39% in men, <36% in women), on postoperative outcomes. Results We obtained data for 12,987 patients, of whom 4260 (32.8%) had preoperative anemia. Patients with preoperative anemia experienced higher postoperative major morbidity and mortality rates compared to those without anemia. After adjustment for predefined variables, preoperative anemia was an independent risk factor for postoperative major morbidity (adjusted OR 1.21, 1.09–1.33). After adjustment, there was no significant difference in postoperative mortality for patients with or without preoperative anemia (adjusted OR 0.88, 0.66–1.16). Conclusion Preoperative anemia is independently associated with an increased risk of major morbidity in patients undergoing hepatectomy. Therefore, it is crucial to readdress preoperative blood management in anemic patients prior to hepatectomy. PMID:27017165

  13. Navigating a Maze with Balance Board and Wiimote

    NASA Astrophysics Data System (ADS)

    Fikkert, Wim; Hoeijmakers, Niek; van der Vet, Paul; Nijholt, Anton

    Input from the lower body in human-computer interfaces can be beneficial, enjoyable and even entertaining when users are expected to perform tasks simultaneously. Users can navigate a virtual (game) world or even an (empirical) dataset while having their hands free to issue commands. We compared the Wii Balance Board to a hand-held Wiimote for navigating a maze and found that users completed this task slower with the Balance Board. However, the Balance Board was considered more intuitive, easy to learn and ‘much fun’.

  14. Vision-based augmented reality computer assisted surgery navigation system

    NASA Astrophysics Data System (ADS)

    Sun, Lei; Chen, Xin; Xu, Kebin; Li, Xin; Xu, Wei

    2007-12-01

    A vision-based Augmented Reality computer assisted surgery navigation system is presented in this paper. It applies the Augmented Reality technique to surgery navigation system, so the surgeon's vision of the real world is enhanced. In the system, the camera calibration is adopted to calculate the cameras projection matrix, and then make the virtual-real registration by using the transformation relation. The merging of synthetic 3D information into user's vision is realized by texture technique. The experiment results demonstrate the feasibility of the system we have designed.

  15. World Wind: NASA's Virtual Globe

    NASA Astrophysics Data System (ADS)

    Hogan, P.

    2007-12-01

    Virtual globes have set the standard for information exchange. Once you've experienced the visually rich and highly compelling nature of data delivered via virtual globes with their highly engaging context of 3D, it's hard to go back to a flat 2D world. Just as the sawbones of not-too-long-ago have given way to sophisticated surgical operating theater, today's medium for information exchange is just beginning to leap from the staid chalkboards and remote libraries to fingertip navigable 3D worlds. How we harness this technology to serve a world inundated with information will describe the quality of our future. Our instincts for discovery and entertainment urge us on. There's so much we could know if the world's knowledge was presented to us in its natural context. Virtual globes are almost magical in their ability to reveal natural wonders. Anyone flying along a chain of volcanoes, a mid-ocean ridge or deep ocean trench, while simultaneously seeing the different depths to the history of earthquakes in those areas, will be delighted to sense Earth's dynamic nature in a way that would otherwise take several paragraphs of "boring" text. The sophisticated concepts related to global climate change would be far more comprehensible when experienced via a virtual globe. There is a large universe of public and private geospatial data sets that virtual globes can bring to light. The benefit derived from access to this data within virtual globes represents a significant return on investment for government, industry, the general public, and especially in the realm of education. Data access remains a key issue. Just as the highway infrastructure allows unimpeded access from point A to point B, an open standards-based infrastructure for data access allows virtual globes to exchange data in the most efficient manner possible. This data can be either free or proprietary. The Open Geospatial Consortium is providing the leadership necessary for this open standards-based data access

  16. Predictability in orbital reconstruction. A human cadaver study, part III: Implant-oriented navigation for optimized reconstruction.

    PubMed

    Dubois, Leander; Essig, Harald; Schreurs, Ruud; Jansen, Jesper; Maal, Thomas J J; Gooris, Peter J J; Becking, Alfred G

    2015-12-01

    Navigation-assisted orbital reconstruction remains a challenge, because the surgeon focuses on a two-dimensional multiplanar view in relation to the preoperative planning. This study explored the addition of navigation markers in the implant design for three-dimensional (3D) orientation of the actual implant position relative to the preoperative planning for more fail-safe and consistent results. Pre-injury computed tomography (CT) was performed for 10 orbits in human cadavers, and complex orbital fractures (Class III/IV) were created. The orbits were reconstructed using preformed orbital mesh through a transconjunctival approach under image-guided navigation and navigation by referencing orientating markers in the implant design. Ideal implant positions were planned using preoperative CT scans. Implant placement accuracy was evaluated by comparing the planned and realized implant positions. Significantly better translation (3.53 mm vs. 1.44 mm, p = 0.001) and rotation (pitch: -1.7° vs. -2.2°, P = 0.52; yaw: 10.9° vs. 5.9°, P = 0.02; roll: -2.2° vs. -0.5°, P = 0.16) of the placed implant relative to the planned position were obtained by implant-oriented navigation. Navigation-assisted surgery can be improved by using navigational markers on the orbital implant for orientation, resulting in fail-safe reconstruction of complex orbital defects and consistent implant positioning.

  17. Improved surgical procedure using intraoperative navigation for the implantation of the SPG microstimulator in patients with chronic cluster headache.

    PubMed

    Kohlmeier, Carsten; Behrens, Peter; Böger, Andreas; Ramachandran, Brinda; Caparso, Anthony; Schulze, Dirk; Stude, Philipp; Heiland, Max; Assaf, Alexandre T

    2017-01-12

    The ATI SPG microstimulator is designed to be fixed on the posterior maxilla, with the integrated lead extending into the pterygopalatine fossa to electrically stimulate the sphenopalatine ganglion (SPG) as a treatment for cluster headache. Preoperative surgical planning to ensure the placement of the microstimulator in close proximity (within 5 mm) to the SPG is critical for treatment efficacy. The aim of this study was to improve the surgical procedure by navigating the initial dissection prior to implantation using a passive optical navigation system and to match the post-operative CBCT images with the preoperative treatment plan to verify the accuracy of the intraoperative placement of the microstimulator. Custom methods and software were used that result in a 3D rotatable digitally reconstructed fluoroscopic image illustrating the patient-specific placement with the ATI SPG microstimulator. Those software tools were preoperatively integrated with the planning software of the navigation system to be used intraoperatively for navigated placement. Intraoperatively, the SPG microstimulator was implanted by completing the initial dissection with CT navigation, while the final position of the stimulator was verified by 3D CBCT. Those reconstructed images were then immediately matched with the preoperative CT scans with the digitally inserted SPG microstimulator. This method allowed for visual comparison of both CT scans and verified correct positioning of the SPG microstimulator. Twenty-four surgeries were performed using this new method of CT navigated assistance during SPG microstimulator implantation. Those results were compared to results of 21 patients previously implanted without the assistance of CT navigation. Using CT navigation during the initial dissection, an average distance reduction of 1.2 mm between the target point and electrode tip of the SPG microstimulator was achieved. Using the navigation software for navigated implantation and matching the

  18. The Role of OsiriX Based Virtual Endoscopy in Planning Endoscopic Transsphenoidal Surgery for Pituitary Adenoma.

    PubMed

    Rotariu, Daniel Ilie; Ziyad, Faiyad; Budu, Alexandru; Poeata, Ion

    2017-01-01

    Virtual endoscopy (VE) is the navigation of a 3D model reconstructed from radiological image data. The aim of this paper is to evaluate the role and accuracy of the virtual endoscopy realized using commercially available software, OsiriX, as a method of planning of surgical interventions. The computed tomographies of 22 patients with pituitary adenomas proposed for endoscopic approach were reconstructed using OsiriX. VE was performed prior to surgery to assess the surgical corridor and particular anatomy. We evaluated the following landmarks: inferior and middle turbinate, sphenoid ostia (SO), choanal arch (Ch), sphenoethmoidal recess (SER), sphenoid septa, sella turcica, carotid prominences and opticocarotid recesses (OCR). The intraoperative endoscopic images were reviewed and compared with the virtual images. The virtual images had a good resemblance with the actual surgical images. All the structures from the nasal cavity were identified and had a perfect matching except the SO which was identified in 8 cases in VE vs. 12 intraoperative. All the structures from the sphenoid sinus were identified with perfect matching except the ipsilateral carotid prominence (14 in VE vs. 10 intraoperative) and the contralateral carotid prominence (16 in VE vs. 18 intraoperative). The VE could not show the state of the sellar floor and did not offer any information about the sellar content. VE realized in OsiriX represents an affordable alternative to the specially designed systems, offering reliable data and good quality images that are useful for the preoperative planning, but some limitations are present such as inability to obtain additional information in cases where the sphenoid sinus is fully occupied by tumor or not aerated, inability to clearly differentiate between structures at the level of the sella, and impossibility to simulate working instruments.

  19. Lunar rover navigation concepts

    NASA Technical Reports Server (NTRS)

    Burke, James D.

    1993-01-01

    With regard to the navigation of mobile lunar vehicles on the surface, candidate techniques are reviewed and progress of simulations and experiments made up to now are described. Progress that can be made through precursor investigations on Earth is considered. In the early seventies the problem was examined in a series of relevant tests made in the California desert. Meanwhile, Apollo rovers made short exploratory sorties and robotic Lunokhods traveled over modest distances on the Moon. In these early missions some of the required methods were demonstrated. The navigation problem for a lunar traverse can be viewed in three parts: to determine the starting point with enough accuracy to enable the desired mission; to determine the event sequence required to reach the site of each traverse objective; and to redetermine actual positions enroute. The navigator's first tool is a map made from overhead imagery. The Moon was almost completely photographed at moderate resolution by spacecraft launched in the sixties, but that data set provides imprecise topographic and selenodetic information. Therefore, more advanced orbital missions are now proposed as part of a resumed lunar exploration program. With the mapping coverage expected from such orbiters, it will be possible to use a combination of visual landmark navigation and external radio and optical references (Earth and Sun) to achieve accurate surface navigation almost everywhere on the near side of the Moon. On the far side and in permanently dark polar areas, there are interesting exploration targets where additional techniques will have to be used.

  20. Evaluation of a navigation system for dental implantation as a tool to train novice dental practitioners.

    PubMed

    Casap, Nardy; Nadel, Sahar; Tarazi, Eyal; Weiss, Ervin I

    2011-10-01

    This study evaluated the benefits of a virtual reality navigation system for teaching the surgical stage of dental implantation to final-year dental students. The study aimed to assess the students' performance in dental implantation assignments by comparing freehand protocols with virtual reality navigation. Forty final-year dentistry students without previous experience in dental implantation surgery were given an implantation assignment comprising 3 tasks. Marking, drilling, and widening of implant holes were executed by a freehand protocol on the 2 mandibular sides by 1 group and by virtual reality navigation on 1 side and contralaterally with the freehand protocol by the other group. Subjective and objective assessments of the students' performance were graded. Marking with the navigation system was more accurate than with the standard protocol. The 2 groups performed similarly in the 2-mm drilling on the 2 mandibular sides. Widening of the 2 mesial holes to 3 mm was significantly better with the second execution in the standard protocol group, but not in the navigation group. The navigation group's second-site freehand drilling of the molar was significantly worse than the first. The execution of all assignments was significantly faster in the freehand group than in the navigation group (60.75 vs 77.25 minutes, P = .02). Self-assessment only partly matched the objective measurements and was more realistic in the standard protocol group. Despite the improved performance with the navigation system, the added value of training in dental implantation surgery with virtual reality navigation was minimal. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  1. Virtual sound for virtual reality

    SciTech Connect

    Blattner, M.M. ||; Papp, A.L. III |

    1993-02-01

    The computational limitations of real-time interactive computing do not meet our requirements for producing realistic images for virtual reality in a convincing manner. Regardless of the real-time restrictions on virtual reality interfaces, the representations can be no better than the graphics. Computer graphics is still limited in its ability to generate complex objects such as landscapes and humans. Nevertheless, useful and convincing visualizations are made through a variety of techniques. The central theme of this article is that a similar situation is true with sound for virtual reality. It is beyond our abilityto create interactive soundscapes that create a faithful reproduction of real world sounds, however, by choosing one`s application carefully and using sound to enhance a display rather than only mimic real-world scenes, a very effective use of sound can be made.

  2. Virtual sound for virtual reality

    SciTech Connect

    Blattner, M.M. Cancer Center, Houston, TX . Dept. of Biomathematics Lawrence Livermore National Lab., CA California Univ., Davis, CA ); Papp, A.L. III Lawrence Livermore National Lab., CA )

    1993-02-01

    The computational limitations of real-time interactive computing do not meet our requirements for producing realistic images for virtual reality in a convincing manner. Regardless of the real-time restrictions on virtual reality interfaces, the representations can be no better than the graphics. Computer graphics is still limited in its ability to generate complex objects such as landscapes and humans. Nevertheless, useful and convincing visualizations are made through a variety of techniques. The central theme of this article is that a similar situation is true with sound for virtual reality. It is beyond our abilityto create interactive soundscapes that create a faithful reproduction of real world sounds, however, by choosing one's application carefully and using sound to enhance a display rather than only mimic real-world scenes, a very effective use of sound can be made.

  3. Virtual Learning

    ERIC Educational Resources Information Center

    Cvetkovic, Dragan, Ed.

    2016-01-01

    The first chapter provides an overview of the popular systems for distance learning. In the second chapter, a review of all major social and economic activities in order to improve the system of virtual learning is given. The third chapter deals with the influence of technology in the management of educational institutions. The fourth chapter…

  4. Virtual landmarks

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Odhner, Dewey; Bai, Peirui; Torigian, Drew A.

    2017-03-01

    Much has been published on finding landmarks on object surfaces in the context of shape modeling. While this is still an open problem, many of the challenges of past approaches can be overcome by removing the restriction that landmarks must be on the object surface. The virtual landmarks we propose may reside inside, on the boundary of, or outside the object and are tethered to the object. Our solution is straightforward, simple, and recursive in nature, proceeding from global features initially to local features in later levels to detect landmarks. Principal component analysis (PCA) is used as an engine to recursively subdivide the object region. The object itself may be represented in binary or fuzzy form or with gray values. The method is illustrated in 3D space (although it generalizes readily to spaces of any dimensionality) on four objects (liver, trachea and bronchi, and outer boundaries of left and right lungs along pleura) derived from 5 patient computed tomography (CT) image data sets of the thorax and abdomen. The virtual landmark identification approach seems to work well on different structures in different subjects and seems to detect landmarks that are homologously located in different samples of the same object. The approach guarantees that virtual landmarks are invariant to translation, scaling, and rotation of the object/image. Landmarking techniques are fundamental for many computer vision and image processing applications, and we are currently exploring the use virtual landmarks in automatic anatomy recognition and object analytics.

  5. Virtualize Me!

    ERIC Educational Resources Information Center

    Waters, John K.

    2009-01-01

    John Abdelmalak, director of technology for the School District of the Chathams, was pretty sure it was time to jump on the virtualization bandwagon last year when he invited Dell to conduct a readiness assessment of his district's servers. When he saw just how little of their capacity was being used, he lost all doubt. Abdelmalak is one of many…

  6. Virtualize Me!

    ERIC Educational Resources Information Center

    Waters, John K.

    2009-01-01

    John Abdelmalak, director of technology for the School District of the Chathams, was pretty sure it was time to jump on the virtualization bandwagon last year when he invited Dell to conduct a readiness assessment of his district's servers. When he saw just how little of their capacity was being used, he lost all doubt. Abdelmalak is one of many…

  7. Virtually There.

    ERIC Educational Resources Information Center

    Lanier, Jaron

    2001-01-01

    Describes tele-immersion, a new medium for human interaction enabled by digital technologies. It combines the display and interaction techniques of virtual reality with new vision technologies that transcend the traditional limitations of a camera. Tele-immersion stations observe people as moving sculptures without favoring a single point of view.…

  8. Virtually There.

    ERIC Educational Resources Information Center

    Lanier, Jaron

    2001-01-01

    Describes tele-immersion, a new medium for human interaction enabled by digital technologies. It combines the display and interaction techniques of virtual reality with new vision technologies that transcend the traditional limitations of a camera. Tele-immersion stations observe people as moving sculptures without favoring a single point of view.…

  9. Toward (Hybrid) Navigation of a Fluorescence Camera in an Open Surgery Setting.

    PubMed

    KleinJan, Gijs H; van den Berg, Nynke S; van Oosterom, Matthias N; Wendler, Thomas; Miwa, Mitsuharu; Bex, Axel; Hendricksen, Kees; Horenblas, Simon; van Leeuwen, Fijs W B

    2016-10-01

    With the introduction of the hybrid tracer indocyanine green (ICG)-(99m)Tc-nanocolloid, a direct relation between preoperative imaging and intraoperative fluorescence guidance was established. However, fluorescence guidance remains limited by its superficial nature. This study evaluated the feasibility of a nuclear medicine-based navigation concept that allowed intraoperative positioning of a fluorescence camera (FC) in the vicinity of preoperatively defined ICG-(99m)Tc-nanocolloid containing sentinel nodes (SNs). Five patients with penile cancer scheduled for SN biopsy were injected with ICG-(99m)Tc-nanocolloid followed by preoperative SPECT/CT imaging. The navigation device was used to provide a real-time augmented reality overlay of the SPECT/CT images and video output of the FC. This overlay was then used for FC navigation. SPECT/CT identified 13 SNs in 9 groins. FC navigation was successful for all 12 intraoperatively evaluated SNs (average error, 8.8 mm; range, 0-20 mm). This study reveals the potential benefits of FC navigation during open surgery procedures. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  10. Easy and effective virtual tour on the World Wide Web

    NASA Astrophysics Data System (ADS)

    Yoon, Ilmi; Kang, Andrew; Roberts, John; Yoon, Sanghyuk

    2005-01-01

    Web-based Virtual Tour has become a desirable and demanded application, yet challenging due to the nature of web application's running environment such as limited bandwidth and no guarantee of high computation power on the client side. Image-based rendering approach has attractive advantages over traditional 3D rendering approach in such Web Applications. Traditional geometry-based approach, such as VRML, requires labor-intensive 3D modeling process, high bandwidth and computation power especially for photo-realistic virtual scenes. QuickTime VR and IPIX as examples of image-based approach, use panoramic photos and the virtual scenes that can be generated from photos directly skipping the modeling process. But, QuickTime VR and IPIX may not only require special cameras or effort to take panoramic views but also provide only one fixed-point navigation (look-around and zooming in-out) rather than "walk around", that is a very important feature to provide immersive experience to virtual tourists. Easy and Effective Virtual Tour constructs virtual tour using several snap shots of conventional photos without special tools, build simple 3D space within each photo using spidery mesh, and expand the virtual spaces by connecting each other using simple user intervention to specify correspondence. The expanded virtual space provides virtual tourists with free navigation and immersive experience of walking around through the WWW.

  11. Easy and effective virtual tour on the World Wide Web

    NASA Astrophysics Data System (ADS)

    Yoon, Ilmi; Kang, Andrew; Roberts, John; Yoon, Sanghyuk

    2004-12-01

    Web-based Virtual Tour has become a desirable and demanded application, yet challenging due to the nature of web application"s running environment such as limited bandwidth and no guarantee of high computation power on the client side. Image-based rendering approach has attractive advantages over traditional 3D rendering approach in such Web Applications. Traditional geometry-based approach, such as VRML, requires labor-intensive 3D modeling process, high bandwidth and computation power especially for photo-realistic virtual scenes. QuickTime VR and IPIX as examples of image-based approach, use panoramic photos and the virtual scenes that can be generated from photos directly skipping the modeling process. But, QuickTime VR and IPIX may not only require special cameras or effort to take panoramic views but also provide only one fixed-point navigation (look-around and zooming in-out) rather than `walk around", that is a very important feature to provide immersive experience to virtual tourists. Easy and Effective Virtual Tour constructs virtual tour using several snap shots of conventional photos without special tools, build simple 3D space within each photo using spidery mesh, and expand the virtual spaces by connecting each other using simple user intervention to specify correspondence. The expanded virtual space provides virtual tourists with free navigation and immersive experience of walking around through the WWW.

  12. Aerocapture navigation at Neptune

    NASA Technical Reports Server (NTRS)

    Haw, Robert J.

    2003-01-01

    A proposed Neptune orbiter Aerocapture mission will use solar electric propulsion to send an orbiter to Neptune. Navigation feasibility of direct-entry aerocapture for orbit insertion at Neptune is shown. The navigation strategy baselines optical imaging and (delta)VLBI measurement in order to satisfy the flight system's atmosphere entry flight path angle, which is targeted to enter Neptune with an entry flight path angle of -11.6 . Error bars on the entry flight path angle of plus/minus0.55 (3(sigma)) are proposed. This requirement can be satisfied with a data cutoff 3.2 days prior to arrival. There is some margin in the arrival template to tighten (i.e. reduce) the entry corridor either by scheduling a data cutoff closer to Neptune or alternatively, reducing uncertainties by increasing the fidelity of the optical navigation camera.

  13. Personal Virtual Libraries

    ERIC Educational Resources Information Center

    Pappas, Marjorie L.

    2004-01-01

    Virtual libraries are becoming more and more common. Most states have a virtual library. A growing number of public libraries have a virtual presence on the Web. Virtual libraries are a growing addition to school library media collections. The next logical step would be personal virtual libraries. A personal virtual library (PVL) is a collection…

  14. Personal Virtual Libraries

    ERIC Educational Resources Information Center

    Pappas, Marjorie L.

    2004-01-01

    Virtual libraries are becoming more and more common. Most states have a virtual library. A growing number of public libraries have a virtual presence on the Web. Virtual libraries are a growing addition to school library media collections. The next logical step would be personal virtual libraries. A personal virtual library (PVL) is a collection…

  15. Virtual skeletal complex model- and landmark-guided orthognathic surgery system.

    PubMed

    Lee, Sang-Jeong; Woo, Sang-Yoon; Huh, Kyung-Hoe; Lee, Sam-Sun; Heo, Min-Suk; Choi, Soon-Chul; Han, Jeong Joon; Yang, Hoon Joo; Hwang, Soon Jung; Yi, Won-Jin

    2016-05-01

    In this study, correction of the maxillofacial deformities was performed by repositioning bone segments to an appropriate location according to the preoperative planning in orthognathic surgery. The surgery was planned using the patient's virtual skeletal models fused with optically scanned three-dimensional dentition. The virtual maxillomandibular complex (MMC) model of the patient's final occlusal relationship was generated by fusion of the maxillary and mandibular models with scanned occlusion. The final position of the MMC was simulated preoperatively by planning and was used as a goal model for guidance. During surgery, the intraoperative registration was finished immediately using only software processing. For accurate repositioning, the intraoperative MMC model was visualized on the monitor with respect to the simulated MMC model, and the intraoperative positions of multiple landmarks were also visualized on the MMC surface model. The deviation errors between the intraoperative and the final positions of each landmark were visualized quantitatively. As a result, the surgeon could easily recognize the three-dimensional deviation of the intraoperative MMC state from the final goal model without manually applying a pointing tool, and could also quickly determine the amount and direction of further MMC movements needed to reach the goal position. The surgeon could also perform various osteotomies and remove bone interference conveniently, as the maxillary tracking tool could be separated from the MMC. The root mean square (RMS) difference between the preoperative planning and the intraoperative guidance was 1.16 ± 0.34 mm immediately after repositioning. After surgery, the RMS differences between the planning and the postoperative computed tomographic model were 1.31 ± 0.28 mm and 1.74 ± 0.73 mm for the maxillary and mandibular landmarks, respectively. Our method provides accurate and flexible guidance for bimaxillary orthognathic surgery based on

  16. Awake craniotomy using electromagnetic navigation technology without rigid pin fixation.

    PubMed

    Morsy, Ahmed A; Ng, Wai Hoe

    2015-11-01

    We report our institutional experience using an electromagnetic navigation system, without rigid head fixation, for awake craniotomy patients. The StealthStation® S7 AxiEM™ navigation system (Medtronic, Inc.) was used for this technique. Detailed preoperative clinical and neuropsychological evaluations, patient education and contrast-enhanced MRI (thickness 1.5mm) were performed for each patient. The AxiEM Mobile Emitter was typically placed in a holder, which was mounted to the operating room table, and a non-invasive patient tracker was used as the patient reference device. A monitored conscious sedation technique was used in all awake craniotomy patients, and the AxiEM Navigation Pointer was used for navigation during the procedure. This offers the same accuracy as optical navigation, but without head pin fixation or interference with intraoperative neurophysiological techniques and surgical instruments. The application of the electromagnetic neuronavigation technology without rigid head fixation during an awake craniotomy is accurate, and offers superior patient comfort. It is recommended as an effective adjunctive technique for the conduct of awake surgery.

  17. Collective navigation of cargo-carrying swarms

    PubMed Central

    Shklarsh, Adi; Finkelshtein, Alin; Ariel, Gil; Kalisman, Oren; Ingham, Colin; Ben-Jacob, Eshel

    2012-01-01

    Much effort has been devoted to the study of swarming and collective navigation of micro-organisms, insects, fish, birds and other organisms, as well as multi-agent simulations and to the study of real robots. It is well known that insect swarms can carry cargo. The studies here are motivated by a less well-known phenomenon: cargo transport by bacteria swarms. We begin with a concise review of how bacteria swarms carry natural, micrometre-scale objects larger than the bacteria (e.g. fungal spores) as well as man-made beads and capsules (for drug delivery). A comparison of the trajectories of virtual beads in simulations (using different putative coupling between the virtual beads and the bacteria) with the observed trajectories of transported fungal spores implies the existence of adaptable coupling. Motivated by these observations, we devised new, multi-agent-based studies of cargo transport by agent swarms. As a first step, we extended previous modelling of collective navigation of simple bacteria-inspired agents in complex terrain, using three putative models of agent–cargo coupling. We found that cargo-carrying swarms can navigate efficiently in a complex landscape. We further investigated how the stability, elasticity and other features of agent–cargo bonds influence the collective motion and the transport of the cargo, and found sharp phase shifts and dual successful strategies for cargo delivery. Further understanding of such mechanisms may provide valuable clues to understand cargo-transport by smart swarms of other organisms as well as by man-made swarming robots. PMID:24312731

  18. Mariner 9 navigation

    NASA Technical Reports Server (NTRS)

    Neil, W. J.; Jordan, J. F.; Zielenbach, J. W.; Wong, S. K.; Mitchell, R. T.; Webb, W. A.; Koskela, P. E.

    1973-01-01

    A final, comprehensive description of the navigation of Mariner 9-the first U.S. spacecraft to orbit another planet is provided. The Mariner 9 navigation function included not only precision flight path control but also pointing of the spacecraft's scientific instruments mounted on a two degree of freedom scan platform. To the extent appropriate, each section describes the perflight analyses on which the operational strategies and performance predictions were based. Inflight results are then discussed and compared with the preflight predictions. Postflight analyses, which were primarily concerned with developing a thorough understanding of unexpected in-flight results, are also presented.

  19. Cassini tour navigation strategy

    NASA Technical Reports Server (NTRS)

    Roth, Duane; Alwar, Vijay; Bordi, John; Goodson, Troy; Hahn, Yungsun; Ionasescu, Rodica; Jones, Jeremy; Owen, William; Pojman, Joan; Roundhill, Ian; hide

    2003-01-01

    The Cassini-Huygens spacecraft was launched on October 15, 1997 as a joint NASA/ESA mission to explore Saturn. After a 7 year cruise the spacecraft will enter orbit around Saturn on 1 July 2004 for a 4 year investigation of the Saturnian system. The Cassini Navigation Team is responsible for designing the reference trajectory and conducting operations to realize this design. This paper describes the strategy for achieving project requirements, the characteristics of the Cassini navigation challenge, and the underlying assumptions.

  20. Cassini tour navigation strategy

    NASA Technical Reports Server (NTRS)

    Roth, Duane; Alwar, Vijay; Bordi, John; Goodson, Troy; Hahn, Yungsun; Ionasescu, Rodica; Jones, Jeremy; Owen, William; Pojman, Joan; Roundhill, Ian; Santos, Shawna; Strange, Nathan; Wagner, Sean; Wong, Mau

    2003-01-01

    The Cassini-Huygens spacecraft was launched on October 15, 1997 as a joint NASA/ESA mission to explore Saturn. After a 7 year cruise the spacecraft will enter orbit around Saturn on 1 July 2004 for a 4 year investigation of the Saturnian system. The Cassini Navigation Team is responsible for designing the reference trajectory and conducting operations to realize this design. This paper describes the strategy for achieving project requirements, the characteristics of the Cassini navigation challenge, and the underlying assumptions.

  1. Navigational Planning in Orienteering

    NASA Astrophysics Data System (ADS)

    Murakoshi, Shin

    Navigation is a human activity with the aim being to arrive at a predetermined destination. In order to find the way to the destination, the use of current input from the actual environment while travelling is needed as well as stored and organized knowledge of the local geography. Although the knowledge requirement has been studied extensively in the form of cognitive maps or other spatial representation, few studies deal with how the knowledge is used together with the input from the actual environment while navigating.

  2. Preoperative diagnosis of a pulmonary artery sarcoma.

    PubMed Central

    Velebit, V.; Christenson, J. T.; Simonet, F.; Maurice, J.; Schmuziger, M.; Hauser, H.; Didier, D.

    1995-01-01

    A pulmonary artery sarcoma was diagnosed preoperatively by magnetic resonance imaging enhanced with gadolinium and confirmed by percutaneous computed tomographic guided needle biopsy. Accurate preoperative diagnosis allowed planned curative surgery with removal of the right ventricular outflow tract and reconstructive surgery using a cryopreserved homograft. Images PMID:8539663

  3. Guideline implementation: preoperative patient skin antisepsis.

    PubMed

    Cowperthwaite, Liz; Holm, Rebecca L

    2015-01-01

    Performing preoperative skin antisepsis to remove soil and microorganisms at the surgical site may help prevent patients from developing a surgical site infection. The updated AORN "Guideline for preoperative skin antisepsis" addresses the topics of preoperative patient bathing and hair removal, selection and application of skin antiseptics, and safe handling, storage, and disposal of skin antiseptics. This article focuses on key points of the guideline to help perioperative personnel develop protocols for patient skin antisepsis. The key points include the need for the patient to take a preoperative bath or shower and the need for perioperative personnel to manage hair at the surgical site, select a safe and effective antiseptic for the individual patient, perform a safe preoperative surgical site prep, and appropriately store skin antiseptics. Perioperative RNs should review the complete guideline for additional information and for guidance when writing and updating policies and procedures.

  4. Space shuttle navigation analysis. Volume 2: Baseline system navigation

    NASA Technical Reports Server (NTRS)

    Jones, H. L.; Luders, G.; Matchett, G. A.; Rains, R. G.

    1980-01-01

    Studies related to the baseline navigation system for the orbiter are presented. The baseline navigation system studies include a covariance analysis of the Inertial Measurement Unit calibration and alignment procedures, postflight IMU error recovery for the approach and landing phases, on-orbit calibration of IMU instrument biases, and a covariance analysis of entry and prelaunch navigation system performance.

  5. Viewpoint tethering for remotely operated vehicles: effects on complex terrain navigation and spatial awareness.

    PubMed

    Hollands, Justin G; Lamb, Matthew

    2011-04-01

    The effect of viewpoint on the navigation of complex terrain and on spatial awareness was examined with the use of a simulated remotely operated vehicle. The ability to build terrain models in real time may soon allow remote vehicular control from any viewpoint. A virtual tether couples the viewpoint to the vehicle's position and orientation, but shows more of the terrain than a fully immersive egocentric display. In this sense, it provides visual momentum by providing a view that incorporates egocentric and exocentric qualities. For this study, 12 participants navigated a simulated vehicle across complex virtual terrain using five different display viewpoints: egocentric, dynamic tether, rigid tether, 3-D exocentric, and 2-D exocentric. While navigating, participants had to avoid being seen by simulated enemy units. After the navigation task, participants' spatial awareness was assessed using a recognition task. The tethered displays minimized the time during which the participant's vehicle was visible to enemy positions. The egocentric display was more effective than exocentric displays (2-D or 3-D) for navigation, and the exocentric displays were more effective than egocentric for time seen during navigation and the recognition task. The tethered displays produced intermediate results for navigation and recognition. Viewpoint tethering produced the most effective displays for minimizing time seen, but tethered displays were less effective than egocentric and exocentric displays for navigation and recognition, respectively. A tethered display is recommended for applications in which it is necessary to understand the relation of nearby locations to one's own location.

  6. Construction of a virtual bronchus endoscopy system

    NASA Astrophysics Data System (ADS)

    Liu, Xiaofeng; Chang, Xiaogang; Lu, Hanqing

    2001-09-01

    Virtual Endoscopy System is a new aided diagnosis method based on computer processing of 3D image slices to provide simulated visualizations of specific organs similar to those produced by standard endoscopy. Compare with real endoscopy, VES has much advantages and will have more applications in the future. We constructed a Virtual Bronchus Endoscopy System based on the techniques of image analysis, compute graphics, and so on. Based on the characteristic of bronchus, we adopted an improved 3D region-growing algorithm, which we call 3D scanline algorithm to extract the bronchus from the DICOM-formatted medical images, then the 3D polyhedral surface model of bronchus is obtained by triangulation with Marching Cubes Algorithm. Then the user is allowed to navigate freely inside the bronchus along the axis. We adopted surface rendering method in the rendering process. In application this system can meet the requirement of real-time navigation and has pretty good display.

  7. A Brief Nap Is Beneficial for Human Route-Learning: The Role of Navigation Experience and EEG Spectral Power

    ERIC Educational Resources Information Center

    Wamsley, Erin J.; Tucker, Matthew A.; Payne, Jessica D.; Stickgold, Robert

    2010-01-01

    Here, we examined the effect of a daytime nap on changes in virtual maze performance across a single day. Participants either took a short nap or remained awake following training on a virtual maze task. Post-training sleep provided a clear performance benefit at later retest, but only for those participants with prior experience navigating in a…

  8. A Brief Nap Is Beneficial for Human Route-Learning: The Role of Navigation Experience and EEG Spectral Power

    ERIC Educational Resources Information Center

    Wamsley, Erin J.; Tucker, Matthew A.; Payne, Jessica D.; Stickgold, Robert

    2010-01-01

    Here, we examined the effect of a daytime nap on changes in virtual maze performance across a single day. Participants either took a short nap or remained awake following training on a virtual maze task. Post-training sleep provided a clear performance benefit at later retest, but only for those participants with prior experience navigating in a…

  9. Inertial Navigation Components and Systems.

    DTIC Science & Technology

    INERTIAL NAVIGATION , SYMPOSIA, INERTIAL GUIDANCE, INSTRUMENTATION, GYROSCOPES, OPTIMIZATION, STABILIZED PLATFORMS, GYRO COMPASSES, ALIGNMENT, CALIBRATION, COST EFFECTIVENESS, AIR TO SURFACE MISSILES.

  10. 33 CFR 209.325 - Navigation lights, aids to navigation, navigation charts, and related data policy, practices and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Navigation lights, aids to... ADMINISTRATIVE PROCEDURE § 209.325 Navigation lights, aids to navigation, navigation charts, and related data... procedure to be used by all Corps of Engineers installations and activities in connection with aids...

  11. 33 CFR 209.325 - Navigation lights, aids to navigation, navigation charts, and related data policy, practices and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Navigation lights, aids to... ADMINISTRATIVE PROCEDURE § 209.325 Navigation lights, aids to navigation, navigation charts, and related data... procedure to be used by all Corps of Engineers installations and activities in connection with aids...

  12. 33 CFR 209.325 - Navigation lights, aids to navigation, navigation charts, and related data policy, practices and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Navigation lights, aids to... ADMINISTRATIVE PROCEDURE § 209.325 Navigation lights, aids to navigation, navigation charts, and related data... procedure to be used by all Corps of Engineers installations and activities in connection with aids...

  13. 33 CFR 209.325 - Navigation lights, aids to navigation, navigation charts, and related data policy, practices and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Navigation lights, aids to... ADMINISTRATIVE PROCEDURE § 209.325 Navigation lights, aids to navigation, navigation charts, and related data... procedure to be used by all Corps of Engineers installations and activities in connection with aids...

  14. 33 CFR 209.325 - Navigation lights, aids to navigation, navigation charts, and related data policy, practices and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Navigation lights, aids to... ADMINISTRATIVE PROCEDURE § 209.325 Navigation lights, aids to navigation, navigation charts, and related data... procedure to be used by all Corps of Engineers installations and activities in connection with aids...

  15. Pre-operative nutritional assessment.

    PubMed

    Corish, C A

    1999-11-01

    Protein-energy undernutrition, or the possibility of its development, has been documented to occur frequently in surgical patients admitted to hospital. Nutritional status is known to deteriorate over the course of the hospital stay, with poor awareness by medical and nursing staff as to the deleterious effects of impaired nutritional status on clinical outcome and hospital costs. While there is no consensus on the best method for assessment of the nutritional status of surgical patients pre-operatively, there are a number of techniques available. These techniques can be divided into two types, those suitable for screening for nutrition risk on admission to hospital and those used to fully assess nutritional status. Both techniques have their limitations, but if used correctly, and their limitations recognized, should identify the appropriate degree of nutritional intervention for an individual patient in a timely and cost-effective manner. The techniques currently available for nutritional screening and nutritional assessment are reviewed, and their applicability to the Irish setting are discussed in the present paper.

  16. Learning for autonomous navigation

    NASA Technical Reports Server (NTRS)

    Angelova, Anelia; Howard, Andrew; Matthies, Larry; Tang, Benyang; Turmon, Michael; Mjolsness, Eric

    2005-01-01

    Autonomous off-road navigation of robotic ground vehicles has important applications on Earth and in space exploration. Progress in this domain has been retarded by the limited lookahead range of 3-D sensors and by the difficulty of preprogramming systems to understand the traversability of the wide variety of terrain they can encounter.

  17. Navigation for everyday life

    SciTech Connect

    Fu, D.D.; Hammond, K.J.; Swain, M.J.

    1996-12-31

    Past work in navigation has worked toward the goal of producing an accurate map of the environment. While no one can deny the usefulness of such a map, the ideal of producing a complete map becomes unrealistic when an agent is faced with performing real tasks. And yet an agent accomplishing recurring tasks should navigate more efficiently as time goes by. We present a system which integrates navigation, planning, and vision. In this view, navigation supports the needs of a larger system as opposed to being a task in its own right. Whereas previous approaches assume an unknown and unstructured environment, we assume a structured environment whose organization is known, but whose specifics are unknown. The system is endowed with a wide range of visual capabilities as well as search plans for informed exploration of a simulated store constructed from real visual data. We demonstrate the agent finding items while mapping the world. In repeatedly retrieving items, the agent`s performance improves as the learned map becomes more useful.

  18. Inertial Navigation Sensors

    DTIC Science & Technology

    2010-03-01

    In theory, this means that atom interferometers could make the most accurate gyroscopes, accelerometers, gravity gradiometers , and precision clocks...improve navigation accuracy, which is ultimately limited by imperfect knowledge of the gravity vector. A superconducting gravity gradiometer (comprising...Interferometry, Physics, May 2001 [44] Moody M. and Ho Jung Paik, Canavan E., Three-Axis Superconducting Gravity Gradiometer for Sensitive Gravity

  19. Gaspra Optical Navigation Image

    NASA Image and Video Library

    1996-02-08

    This time-exposure picture of the asteroid Gaspra and background stars is one of four optical navigation images made by NASA Galileo imaging system to improve knowledge of Gaspra location for the spacecraft flyby. http://photojournal.jpl.nasa.gov/catalog/PIA00229

  20. Learning for autonomous navigation

    NASA Technical Reports Server (NTRS)

    Angelova, Anelia; Howard, Andrew; Matthies, Larry; Tang, Benyang; Turmon, Michael; Mjolsness, Eric

    2005-01-01

    Autonomous off-road navigation of robotic ground vehicles has important applications on Earth and in space exploration. Progress in this domain has been retarded by the limited lookahead range of 3-D sensors and by the difficulty of preprogramming systems to understand the traversability of the wide variety of terrain they can encounter.

  1. Navigating Mandated Instruction

    ERIC Educational Resources Information Center

    Ukpokodu, Omiunota Nelly; Hernandez-Scott, Erica; Brown, Takeisha

    2007-01-01

    In this paper, the authors--a university social studies professor and two elementary classroom teachers in a metropolitan urban community--share their perspectives, experiences, and commitment to keeping social studies in the curriculum. Specifically, they discuss practices that they have engaged in to navigate the school district's mandated…

  2. Navigating between the Dimensions

    ERIC Educational Resources Information Center

    Fleron, Julian F.; Ecke, Volker

    2011-01-01

    Generations have been inspired by Edwin A. Abbott's profound tour of the dimensions in his novella "Flatland: A Romance of Many Dimensions" (1884). This well-known satire is the story of a flat land inhabited by geometric shapes trying to navigate the subtleties of their geometric, social, and political positions. In this article, the authors…

  3. Navigating between the Dimensions

    ERIC Educational Resources Information Center

    Fleron, Julian F.; Ecke, Volker

    2011-01-01

    Generations have been inspired by Edwin A. Abbott's profound tour of the dimensions in his novella "Flatland: A Romance of Many Dimensions" (1884). This well-known satire is the story of a flat land inhabited by geometric shapes trying to navigate the subtleties of their geometric, social, and political positions. In this article, the authors…

  4. Virtual impactor

    DOEpatents

    Yeh, Hsu-Chi; Chen, Bean T.; Cheng, Yung-Sung; Newton, George J.

    1988-08-30

    A virtual impactor having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency.

  5. Virtual anthropology.

    PubMed

    Weber, Gerhard W

    2015-02-01

    Comparative morphology, dealing with the diversity of form and shape, and functional morphology, the study of the relationship between the structure and the function of an organism's parts, are both important subdisciplines in biological research. Virtual anthropology (VA) contributes to comparative morphology by taking advantage of technological innovations, and it also offers new opportunities for functional analyses. It exploits digital technologies and pools experts from different domains such as anthropology, primatology, medicine, paleontology, mathematics, statistics, computer science, and engineering. VA as a technical term was coined in the late 1990s from the perspective of anthropologists with the intent of being mostly applied to biological questions concerning recent and fossil hominoids. More generally, however, there are advanced methods to study shape and size or to manipulate data digitally suitable for application to all kinds of primates, mammals, other vertebrates, and invertebrates or to issues regarding plants, tools, or other objects. In this sense, we could also call the field "virtual morphology." The approach yields permanently available virtual copies of specimens and data that comprehensively quantify geometry, including previously neglected anatomical regions. It applies advanced statistical methods, supports the reconstruction of specimens based on reproducible manipulations, and promotes the acquisition of larger samples by data sharing via electronic archives. Finally, it can help identify new, hidden traits, which is particularly important in paleoanthropology, where the scarcity of material demands extracting information from fragmentary remains. This contribution presents a current view of the six main work steps of VA: digitize, expose, compare, reconstruct, materialize, and share. The VA machinery has also been successfully used in biomechanical studies which simulate the stress and strains appearing in structures. Although

  6. Virtual Mirrors

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2010-01-01

    The multiple-reflection photograph in Fig. 1 was taken in an elevator on board the cruise ship Norwegian Jade in March 2008. Three of the four walls of the elevator were mirrored, allowing me to see the combination of two standard arrangements of plane mirrors: two mirrors set at 90° to each other and two parallel mirrors. Optical phenomena of this complexity are most easily approached by the Method of Virtual Mirrors.

  7. Earthquake Safety Training through Virtual Drills.

    PubMed

    Li, Changyang; Liang, Wei; Quigley, Chris; Zhao, Yibiao; Yu, Lap-Fai

    2017-04-01

    Recent popularity of consumer-grade virtual reality devices, such as the Oculus Rift and the HTC Vive, has enabled household users to experience highly immersive virtual environments. We take advantage of the commercial availability of these devices to provide an immersive and novel virtual reality training approach, designed to teach individuals how to survive earthquakes, in common indoor environments. Our approach makes use of virtual environments realistically populated with furniture objects for training. During a training, a virtual earthquake is simulated. The user navigates in, and manipulates with, the virtual environments to avoid getting hurt, while learning the observation and self-protection skills to survive an earthquake. We demonstrated our approach for common scene types such as offices, living rooms and dining rooms. To test the effectiveness of our approach, we conducted an evaluation by asking users to train in several rooms of a given scene type and then test in a new room of the same type. Evaluation results show that our virtual reality training approach is effective, with the participants who are trained by our approach performing better, on average, than those trained by alternative approaches in terms of the capabilities to avoid physical damage and to detect potentially dangerous objects.

  8. Virtual reality and anthropology.

    PubMed

    Recheis, W; Weber, G W; Schäfer, K; Knapp, R; Seidler, H; zur Nedden, D

    1999-08-01

    Since the discovery of the Tyrolean Iceman in 1991 advanced imaging and post processing techniques were successfully applied in anthropology. Specific techniques include spiral computed tomography and 3-dimensional reconstructions including stereolithographic and fused deposition modeling of volume data sets. The Iceman's skull was the first to be reproduced using stereolithography, before this method was successfully applied in preoperative planning. With the advent of high-end graphics workstations and biomedical image processing software packages, 3-dimensional reconstructions were established as a routine tool for analyzing volume data sets. These techniques opened totally new insights in the field of physical anthropology. Computed tomography became the ideal research tool to access the internal structures of various precious fossils without damaging or even touching them. Many of the most precious specimens from the species Autralopithecus (1.8-3.5 Myears), Homo heidelbergensis (200-600 kyears) or Homo neanderthalensis (40-100 kyears) were scanned during the last 5 years. Often the fossils are filled with a stone matrix or other materials. During the postprocessing routines highly advanced algorithms were used to remove virtually these incrustations. Thus it was possible to visualize the morphological structures that lie beneath the matrix. Some specimen were partially destroyed, so the missing parts were reconstructed on computer screen in order to get estimations of the brain volume and endocranial morphology, both major fields of interest in physical anthropology. Moreover the computerized form of the data allows new descriptions of morphologic structures by the means of 'geometric morphometrics'. Some of the results may change aspects and interpretations in human evolution. The introduction of new imaging and post processing techniques created a new field of research: Virtual Anthropology.

  9. Navigating without vision: basic and applied research.

    PubMed

    Loomis, J M; Klatzky, R L; Golledge, R G

    2001-05-01

    We describe some of the results of our program of basic and applied research on navigating without vision. One basic research topic that we have studied extensively is path integration, a form of navigation in which perceived self-motion is integrated over time to obtain an estimate of current position and orientation. In experiments on pathway completion, one test of path integration ability, we have found that subjects who are passively guided over the outbound path without vision exhibit significant errors when attempting to return to the origin but are nevertheless sensitive to turns and segment lengths in the stimulus path. We have also found no major differences in path integration ability among blind and sighted populations. A model we have developed that attributes errors in path integration to errors in encoding the stimulus path is a good beginning toward understanding path integration performance. In other research on path integration, in which optic flow information was manipulated in addition to the proprioceptive and vestibular information of nonvisual locomotion, we have found that optic flow is a weak input to the path integration process. In other basic research, our studies of auditory distance perception in outdoor environments show systematic underestimation of sound source distance. Our applied research has been concerned with developing and evaluating a navigation system for the visually impaired that uses three recent technologies: the Global Positioning System, Geographic Information Systems, and virtual acoustics. Our work shows that there is considerable promise of these three technologies in allowing visually impaired individuals to navigate and learn about unfamiliar environments without the assistance of human guides.

  10. Endoscopic navigation for minimally invasive suturing.

    PubMed

    Wengert, Christian; Bossard, Lukas; Baur, Charles; Székely, Gábor; Cattin, Philippe C

    2008-09-01

    Manipulating small objects such as needles, screws or plates inside the human body during minimally invasive surgery can be very difficult for less experienced surgeons due to the loss of 3D depth perception. Classical navigation techniques are often incapable of providing support in such situations, as the augmentation of the scene with the necessary artificial markers--if possible at all--is usually cumbersome and leads to increased invasiveness. We present an approach relying solely on a standard endoscope as a tracking device for determining the pose of such objects, using the example of a suturing needle. The resulting pose information is then used to generate artificial 3D cues on the 2D screen to provide optimal support for surgeons during tissue suturing. In addition, if an external tracking device is provided to report the endoscope's position, the suturing needle can be directly tracked in the world coordinate system. Furthermore, a visual navigation aid can be incorporated if a 3D surface is intraoperatively reconstructed from the endoscopic video stream or registered from preoperative imaging.

  11. Communicating Situation Awareness in Virtual Environments

    DTIC Science & Technology

    1994-08-01

    Seattle, "The Treatment of Akinesia Using Virtual Images." Ph.D. M.E., In Progress, University of Washington, Seattle. Geoffrey M. Silverton (Research...hitl.washington.edu Robert G. Futamura UW / HITL futamura@u.washington.edu Jerry Prothero UW / HITL prothero@hitl.washington.edu Geoffrey Silverton UW / HITL geoffs...Glenna Satalich Navigating and wayfinding in VR Geoff Silverton HITLab Testbed specifications Ryoko Williamson Exploring the effect of information

  12. Coastal Piloting & Charting: Navigation 101.

    ERIC Educational Resources Information Center

    Osinski, Alison

    This curriculum guide for a beginning course on marine navigation describes marine navigation (the art of and science of determining position of a ship and its movement from one position to another in order to keep track of where the ship is and where it is going) and defines dead reckoning, piloting, electronic navigation, and celestial…

  13. Computed tomography is not necessary to assess rotation of the femoral component in navigation-assisted total knee replacement.

    PubMed

    Hernández-Vaquero, Daniel; Noriega-Fernandez, Alfonso; Perez-Coto, Ivan; Sandoval García, Manuel A; Sierra-Pereira, Andres A; Roncero-Gonzalez, Sergio; Fernandez-Carreira, Jose Manuel

    2016-12-01

    Objective To demonstrate that postoperative computed tomography (CT) is not needed if navigation is used to determine the rotational position of the femoral component during total knee replacement (TKR). Methods Preoperative CT, navigational, and postoperative CT data of 70 TKR procedures were analysed. The correlation between the rotational angulation of the femur measured by CT and that measured by perioperative navigation was examined. The correlation between the femoral component rotation determined by navigation and that determined by CT was also assessed. Results The mean femoral rotation determined by navigation was 2.64° ± 4.34°, while that shown by CT was 6.43° ± 1.65°. Postoperative rotation of the femoral component shown by CT was 3.09° ± 2.71°, which was closely correlated with the angle obtained through the intraoperative transepicondylar axis by navigation (Pearson's R = 0.930). Conclusions Navigation can be used to collect the preoperative, intraoperative, and postoperative data and final position of the TKR. The rotation of the femoral component can be determined using navigation without the need for CT.

  14. Image navigation as a means to expand the boundaries of fluorescence-guided surgery

    NASA Astrophysics Data System (ADS)

    Brouwer, Oscar R.; Buckle, Tessa; Bunschoten, Anton; Kuil, Joeri; Vahrmeijer, Alexander L.; Wendler, Thomas; Valdés-Olmos, Renato A.; van der Poel, Henk G.; van Leeuwen, Fijs W. B.

    2012-05-01

    Hybrid tracers that are both radioactive and fluorescent help extend the use of fluorescence-guided surgery to deeper structures. Such hybrid tracers facilitate preoperative surgical planning using (3D) scintigraphic images and enable synchronous intraoperative radio- and fluorescence guidance. Nevertheless, we previously found that improved orientation during laparoscopic surgery remains desirable. Here we illustrate how intraoperative navigation based on optical tracking of a fluorescence endoscope may help further improve the accuracy of hybrid surgical guidance. After feeding SPECT/CT images with an optical fiducial as a reference target to the navigation system, optical tracking could be used to position the tip of the fluorescence endoscope relative to the preoperative 3D imaging data. This hybrid navigation approach allowed us to accurately identify marker seeds in a phantom setup. The multispectral nature of the fluorescence endoscope enabled stepwise visualization of the two clinically approved fluorescent dyes, fluorescein and indocyanine green. In addition, the approach was used to navigate toward the prostate in a patient undergoing robot-assisted prostatectomy. Navigation of the tracked fluorescence endoscope toward the target identified on SPECT/CT resulted in real-time gradual visualization of the fluorescent signal in the prostate, thus providing an intraoperative confirmation of the navigation accuracy.

  15. Navigational strategies underlying phototaxis in larval zebrafish.

    PubMed

    Chen, Xiuye; Engert, Florian

    2014-01-01

    Understanding how the brain transforms sensory input into complex behavior is a fundamental question in systems neuroscience. Using larval zebrafish, we study the temporal component of phototaxis, which is defined as orientation decisions based on comparisons of light intensity at successive moments in time. We developed a novel "Virtual Circle" assay where whole-field illumination is abruptly turned off when the fish swims out of a virtually defined circular border, and turned on again when it returns into the circle. The animal receives no direct spatial cues and experiences only whole-field temporal light changes. Remarkably, the fish spends most of its time within the invisible virtual border. Behavioral analyses of swim bouts in relation to light transitions were used to develop four discrete temporal algorithms that transform the binary visual input (uniform light/uniform darkness) into the observed spatial behavior. In these algorithms, the turning angle is dependent on the behavioral history immediately preceding individual turning events. Computer simulations show that the algorithms recapture most of the swim statistics of real fish. We discovered that turning properties in larval zebrafish are distinctly modulated by temporal step functions in light intensity in combination with the specific motor history preceding these turns. Several aspects of the behavior suggest memory usage of up to 10 swim bouts (~10 sec). Thus, we show that a complex behavior like spatial navigation can emerge from a small number of relatively simple behavioral algorithms.

  16. Navigational strategies underlying phototaxis in larval zebrafish

    PubMed Central

    Chen, Xiuye; Engert, Florian

    2014-01-01

    Understanding how the brain transforms sensory input into complex behavior is a fundamental question in systems neuroscience. Using larval zebrafish, we study the temporal component of phototaxis, which is defined as orientation decisions based on comparisons of light intensity at successive moments in time. We developed a novel “Virtual Circle” assay where whole-field illumination is abruptly turned off when the fish swims out of a virtually defined circular border, and turned on again when it returns into the circle. The animal receives no direct spatial cues and experiences only whole-field temporal light changes. Remarkably, the fish spends most of its time within the invisible virtual border. Behavioral analyses of swim bouts in relation to light transitions were used to develop four discrete temporal algorithms that transform the binary visual input (uniform light/uniform darkness) into the observed spatial behavior. In these algorithms, the turning angle is dependent on the behavioral history immediately preceding individual turning events. Computer simulations show that the algorithms recapture most of the swim statistics of real fish. We discovered that turning properties in larval zebrafish are distinctly modulated by temporal step functions in light intensity in combination with the specific motor history preceding these turns. Several aspects of the behavior suggest memory usage of up to 10 swim bouts (~10 sec). Thus, we show that a complex behavior like spatial navigation can emerge from a small number of relatively simple behavioral algorithms. PMID:24723859

  17. 33 CFR 401.53 - Obstructing navigation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Obstructing navigation. 401.53 Section 401.53 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.53 Obstructing...

  18. Control algorithms for autonomous robot navigation

    SciTech Connect

    Jorgensen, C.C.

    1985-09-20

    This paper examines control algorithm requirements for autonomous robot navigation outside laboratory environments. Three aspects of navigation are considered: navigation control in explored terrain, environment interactions with robot sensors, and navigation control in unanticipated situations. Major navigation methods are presented and relevance of traditional human learning theory is discussed. A new navigation technique linking graph theory and incidental learning is introduced.

  19. 33 CFR 401.53 - Obstructing navigation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Obstructing navigation. 401.53 Section 401.53 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.53 Obstructing...

  20. 33 CFR 401.53 - Obstructing navigation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Obstructing navigation. 401.53 Section 401.53 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.53 Obstructing...

  1. 33 CFR 401.53 - Obstructing navigation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Obstructing navigation. 401.53 Section 401.53 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.53 Obstructing...

  2. 33 CFR 401.53 - Obstructing navigation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Obstructing navigation. 401.53 Section 401.53 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.53 Obstructing...

  3. Optic flow helps humans learn to navigate through synthetic environments.

    PubMed

    Kirschen, M P; Kahana, M J; Sekuler, R; Burack, B

    2000-01-01

    Self-movement through an environment generates optic flow, a potential source of heading information. But it is not certain that optic flow is sufficient to support navigation, particularly navigation along complex, multi-legged paths. To address this question, we studied human participants who navigated synthetic environments with and without salient optic flow. Participants used a keyboard to control realistic simulation of self-movement through computer-rendered, synthetic environments. Because these environments comprised series of identically textured virtual corridors and intersections, participants had to build up some mental representation of the environment in order to perform. The impact of optic flow on learning was examined in two experiments. In experiment 1, participants learned to navigate multiple T-junction mazes with and without accompanying optic flow. Optic flow promoted faster learning, mainly by preventing disorientation and backtracking in the maze. In experiment 2, participants found their way around a virtual city-block environment, experiencing two different kinds of optic flow as they went. By varying the rate at which the display was updated, we created optic flow that was either fluid or choppy. Here, fluid optic flow (as compared with choppy optic flow) enabled participants to locate a remembered target position more accurately. When other cues are unavailable, optic flow can be a significant aid in wayfinding. Among other things, optic flow can facilitate path integration, which involves updating a mental representation of place by combining the trajectories of previously travelled paths [corrected].

  4. Accuracy of Computed Tomography-Based Navigation-Assisted Total Knee Arthroplasty: Outlier Analysis.

    PubMed

    Miyasaka, Teruyuki; Kurosaka, Daisaburo; Saito, Mitsuru; Omori, Toshiyuki; Ikeda, Ryo; Marumo, Keishi

    2017-01-01

    Achieving neutral limb alignment during total knee arthroplasty (TKA) has been identified as a potential factor in long-term prosthesis survival. This study aimed to analyze the accuracy of component orientation and postoperative alignment of the leg after computed tomography (CT)-based navigation-assisted TKA, compare these parameters with those of a conventional technique, and analyze differences in the data of outliers. We retrospectively compared the alignment of 130 TKAs performed with a CT-based navigation system with that of 67 arthroplasties done with a conventional system. The knee joints were evaluated using radiographs. Mean hip-knee-ankle (HKA) angle, frontal femoral component angle, and frontal tibial component angle were 180.7°, 88.8°, and 90.6°, respectively, for the navigation-assisted arthroplasties and 181.1°, 88.7°, and 90.2°, respectively, for the conventional arthroplasties. All preoperative leg axes of 10 outliers in the navigation group were >193°, whereas the data of 17 outliers in the conventional group were scattered. This study demonstrates significant improvements in component positioning with the CT-based navigation system. Furthermore, when analyzing cases with preoperative HKA angles ≤192°, no outliers were found in the navigation group, indicating high alignment accuracy. However, in cases with preoperative HKA angles ≥193°, outliers were found in both groups, and no significant difference between the groups was observed (P = .08). Detailed analysis of the outlier cases in the navigation group revealed that the femoral component was placed in the varus position. These findings indicate that the varus knee is an important factor influencing accurate positioning of the femoral component and the postoperative leg axis. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. [Preoperative fluid management in pediatric patients].

    PubMed

    Hashimoto, Megumi; Fujii, Tomoko; Serada, Kazuyuki

    2011-07-01

    Preoperative fasting period is required in order to reducing the risk of pulmonary aspiration which may occur during pediatric general anesthesia. Overnight fasting is still prevalent in Japan. Children could be easily dehydrated or have hypoglycemia after such long fasting period. American Society of Anesthesiologists (ASA) issued a simple guideline as "practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration" in 1999. Cochrane Database evaluated this guideline twice in 2005 and in 2009. In this article, recent tactics of preoperative fasting in children is reviewed along the ASA guideline and the Cochrane report.

  6. Celestial navigation technique in the background of navigation war - the history, present situation and developing tendency of celestial navigation technique

    NASA Astrophysics Data System (ADS)

    Wang, Anguo

    2001-06-01

    This paper probes into the development of celestial navigation technique and its related theories or methods in the recent 30 years. It is introduced the attentions which the major military countries of the world has paid on celestial navigation technique. It is also discussed about the conspicuous superiority of celestial navigation technique in the background of navigation war. The main contents are: (1) The history and present situation of celestial navigation equipment, (2) new achievements of celstial navigation theory, (3) attitudes towards celestial navigation of major military countries, (4) superiority of celestial navigation, (5) key technique to the automation of celestial navigation and (6) developing tendency of automatic celestial navigation technique.

  7. Navigated laparoscopic ultrasound in abdominal soft tissue surgery: technological overview and perspectives.

    PubMed

    Langø, Thomas; Vijayan, Sinara; Rethy, Anna; Våpenstad, Cecilie; Solberg, Ole Vegard; Mårvik, Ronald; Johnsen, Gjermund; Hernes, Toril N

    2012-07-01

    Two-dimensinal laparoscopic ultrasound (LUS) is commonly used for many laparoscopic procedures, but 3D LUS and navigation technology are not conventional tools in the clinic. Navigated LUS can help the user understand and interpret the ultrasound images in relation to the laparoscopic view and preoperative images. When combined with information from MRI or CT, navigated LUS has the potential to provide information about anatomic shifts during the procedure. In this paper, we present an overview of the ongoing technological research and development related to LUS combined with navigation technology, The purpose of this overview is threefold: (1) an introduction for those new to the field of navigated LUS; (2) an overview for those working in the field and; and (3) as a reference for those searching for literature on technological developments related to navigation in ultrasound-guided laparoscopic surgery. Databases were searched to identify relevant publications from the last 10 years. We were able to identify 18 key papers in the area of navigated LUS for the abdomen, originating from about 10-11 groups. We present the literature overview, including descriptions of our own experience in the field, and a discussion of the important clinical and technological aspects related to navigated LUS. LUS integrated with miniaturized tracking technology is likely to play an important role in guiding future laparoscopic surgery.

  8. A Novel Augmented Reality Navigation System for Endoscopic Sinus and Skull Base Surgery: A Feasibility Study.

    PubMed

    Li, Liang; Yang, Jian; Chu, Yakui; Wu, Wenbo; Xue, Jin; Liang, Ping; Chen, Lei

    2016-01-01

    To verify the reliability and clinical feasibility of a self-developed navigation system based on an augmented reality technique for endoscopic sinus and skull base surgery. In this study we performed a head phantom and cadaver experiment to determine the display effect and accuracy of our navigational system. We compared cadaver head-based simulated operations, the target registration error, operation time, and National Aeronautics and Space Administration Task Load Index scores of our navigation system to conventional navigation systems. The navigation system developed in this study has a novel display mode capable of fusing endoscopic images to three-dimensional (3-D) virtual images. In the cadaver head experiment, the target registration error was 1.28 ± 0.45 mm, which met the accepted standards of a navigation system used for nasal endoscopic surgery. Compared with conventional navigation systems, the new system was more effective in terms of operation time and the mental workload of surgeons, which is especially important for less experienced surgeons. The self-developed augmented reality navigation system for endoscopic sinus and skull base surgery appears to have advantages that outweigh those of conventional navigation systems. We conclude that this navigational system will provide rhinologists with more intuitive and more detailed imaging information, thus reducing the judgment time and mental workload of surgeons when performing complex sinus and skull base surgeries. Ultimately, this new navigational system has potential to increase the quality of surgeries. In addition, the augmented reality navigational system could be of interest to junior doctors being trained in endoscopic techniques because it could speed up their learning. However, it should be noted that the navigation system serves as an adjunct to a surgeon's skills and knowledge, not as a substitute.

  9. A Novel Augmented Reality Navigation System for Endoscopic Sinus and Skull Base Surgery: A Feasibility Study

    PubMed Central

    Li, Liang; Yang, Jian; Chu, Yakui; Wu, Wenbo; Xue, Jin; Liang, Ping; Chen, Lei

    2016-01-01

    Objective To verify the reliability and clinical feasibility of a self-developed navigation system based on an augmented reality technique for endoscopic sinus and skull base surgery. Materials and Methods In this study we performed a head phantom and cadaver experiment to determine the display effect and accuracy of our navigational system. We compared cadaver head-based simulated operations, the target registration error, operation time, and National Aeronautics and Space Administration Task Load Index scores of our navigation system to conventional navigation systems. Results The navigation system developed in this study has a novel display mode capable of fusing endoscopic images to three-dimensional (3-D) virtual images. In the cadaver head experiment, the target registration error was 1.28 ± 0.45 mm, which met the accepted standards of a navigation system used for nasal endoscopic surgery. Compared with conventional navigation systems, the new system was more effective in terms of operation time and the mental workload of surgeons, which is especially important for less experienced surgeons. Conclusion The self-developed augmented reality navigation system for endoscopic sinus and skull base surgery appears to have advantages that outweigh those of conventional navigation systems. We conclude that this navigational system will provide rhinologists with more intuitive and more detailed imaging information, thus reducing the judgment time and mental workload of surgeons when performing complex sinus and skull base surgeries. Ultimately, this new navigational system has potential to increase the quality of surgeries. In addition, the augmented reality navigational system could be of interest to junior doctors being trained in endoscopic techniques because it could speed up their learning. However, it should be noted that the navigation system serves as an adjunct to a surgeon’s skills and knowledge, not as a substitute. PMID:26757365

  10. Communication Skills to Develop Trusting Relationships on Global Virtual Engineering Capstone Teams

    ERIC Educational Resources Information Center

    Zaugg, Holt; Davies, Randall S.

    2013-01-01

    As universities seek to provide cost-effective, cross-cultural experiences using global virtual (GV) teams, the "soft" communication skills typical of all teams, increases in importance for GV teams. Students need to be taught how to navigate through cultural issues and virtual tool issues to build strong trusting relationships with…

  11. Communication Skills to Develop Trusting Relationships on Global Virtual Engineering Capstone Teams

    ERIC Educational Resources Information Center

    Zaugg, Holt; Davies, Randall S.

    2013-01-01

    As universities seek to provide cost-effective, cross-cultural experiences using global virtual (GV) teams, the "soft" communication skills typical of all teams, increases in importance for GV teams. Students need to be taught how to navigate through cultural issues and virtual tool issues to build strong trusting relationships with…

  12. Attitude and Self-Efficacy Change: English Language Learning in Virtual Worlds

    ERIC Educational Resources Information Center

    Zheng, Dongping; Young, Michael F.; Brewer, Robert A.; Wagner, Manuela

    2009-01-01

    This study explored affective factors in learning English as a foreign language in a 3D game-like virtual world, Quest Atlantis (QA). Through the use of communication tools (e.g., chat, bulletin board, telegrams, and email), 3D avatars, and 2D webpage navigation tools in virtual space, nonnative English speakers (NNES) co-solved online…

  13. Brain tumor surgery with 3-dimensional surface navigation.

    PubMed

    Mert, Ayguel; Buehler, Katja; Sutherland, Garnette R; Tomanek, Boguslaw; Widhalm, Georg; Kasprian, Gregor; Knosp, Engelbert; Wolfsberger, Stefan

    2012-12-01

    Precise lesion localization is necessary for neurosurgical procedures not only during the operative approach, but also during the preoperative planning phase. To evaluate the advantages of 3-dimensional (3-D) brain surface visualization over conventional 2-dimensional (2-D) magnetic resonance images for surgical planning and intraoperative guidance in brain tumor surgery. Preoperative 3-D brain surface visualization was performed with neurosurgical planning software in 77 cases (58 gliomas, 7 cavernomas, 6 meningiomas, and 6 metastasis). Direct intraoperative navigation on the 3-D brain surface was additionally performed in the last 20 cases with a neurosurgical navigation system. For brain surface reconstruction, patient-specific anatomy was obtained from MR imaging and brain volume was extracted with skull stripping or watershed algorithms, respectively. Three-dimensional visualization was performed by direct volume rendering in both systems. To assess the value of 3-D brain surface visualization for topographic lesion localization, a multiple-choice test was developed. To assess accuracy and reliability of 3-D brain surface visualization for intraoperative orientation, we topographically correlated superficial vessels and gyral anatomy on 3-D brain models with intraoperative images. The rate of correct lesion localization with 3-D was significantly higher (P = .001, χ), while being significantly less time consuming (P < .001, χ) compared with 2-D images. Intraoperatively, visual correlation was found between the 3-D images, superficial vessels, and gyral anatomy. The proposed method of 3-D brain surface visualization is fast, clinically reliable for preoperative anatomic lesion localization and patient-specific planning, and, together with navigation, improves intraoperative orientation in brain tumor surgery and is relatively independent of brain shift.

  14. 33 CFR 207.185 - Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION...

  15. 33 CFR 207.185 - Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION...

  16. 33 CFR 207.185 - Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS...

  17. 33 CFR 207.185 - Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS...

  18. 33 CFR 207.185 - Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Taylors Bayou, Tex., Beaumont Navigation District Lock; use, administration, and navigation. 207.185 Section 207.185 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE NAVIGATION REGULATIONS...

  19. Virtual impactor

    DOEpatents

    Yeh, H.C.; Chen, B.T.; Cheng, Y.S.; Newton, G.J.

    1988-08-30

    A virtual impactor is described having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent to the inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency. 4 figs.

  20. Integrated navigation method based on inertial navigation system and Lidar

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyue; Shi, Haitao; Pan, Jianye; Zhang, Chunxi

    2016-04-01

    An integrated navigation method based on the inertial navigational system (INS) and Lidar was proposed for land navigation. Compared with the traditional integrated navigational method and dead reckoning (DR) method, the influence of the inertial measurement unit (IMU) scale factor and misalignment was considered in the new method. First, the influence of the IMU scale factor and misalignment on navigation accuracy was analyzed. Based on the analysis, the integrated system error model of INS and Lidar was established, in which the IMU scale factor and misalignment error states were included. Then the observability of IMU error states was analyzed. According to the results of the observability analysis, the integrated system was optimized. Finally, numerical simulation and a vehicle test were carried out to validate the availability and utility of the proposed INS/Lidar integrated navigational method. Compared with the test result of a traditional integrated navigation method and DR method, the proposed integrated navigational method could result in a higher navigation precision. Consequently, the IMU scale factor and misalignment error were effectively compensated by the proposed method and the new integrated navigational method is valid.

  1. Anterior knee laxity measurement using stress radiographs and the GNRB(®) system versus intraoperative navigation.

    PubMed

    Jenny, J-Y; Arndt, J

    2013-10-01

    Anterior knee laxity measurement serves both to diagnose and to evaluate the severity of anterior cruciate ligament (ACL) damage. We tested the hypothesis that anterior laxity measurements of ACL-deficient knees obtained using the GNRB(®) system and stress radiographs differed from each other and from intraoperative navigation measurement taken as the reference standard. Twenty-one patients with chronic ACL deficiency underwent arthroscopic ACL reconstruction. Anterior knee laxity was measured preoperatively using the GNRB(®) system without anaesthesia and anterior-drawer stress radiographs under anaesthesia then intraoperatively using a non-image-based navigation system. The three measurements differed significantly (P=0.05). A systematic measurement error of -3.7 mm occurred for both preoperative measurements versus the reference standard. No significant difference was found between the two preoperative measurements. The GNRB(®) system should be preferred over stress radiographs, as reliability is similar but no radiation exposure is required. Both preoperative measurement methods underestimate anterior laxity as measured intraoperatively using the navigation system. This systematic bias may be relevant to treatment decision-making. II, development of a diagnostic criterion in consecutive patients versus a validated reference standard. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  2. A fresh look at preoperative body washing

    PubMed Central

    Tanner, Judith; Gould, Dinah; Jenkins, Philip; Hilliam, Rachel; Mistry, Neetesh; Walsh, Susannah

    2012-01-01

    National guidelines do not support preoperative body washing to reduce surgical site infections, instead recommending bathing or showering with soap. Yet preoperative body washing continues to be widely used in many hospitals across Europe. This paper suggests that existing trials of preoperative body washing, upon which guidelines are based, are dated and proposes a new investigation of preoperative body washing using modern definitions of surgical site infection with standardised patient follow up, modern surgical techniques and well designed trials. This paper provides a critique of existing guidelines and describes a randomised trial with 60 participants to compare the effect of soap and two antiseptic washing products on colony forming units (CFUs) for up to six hours. Chlorhexidine gluconate and octenidine were significantly more effective than soap in reducing CFUs in the underarm, and chlorhexidine was significantly more effective than soap in reducing CFUs in the groin. PMID:22448182

  3. Preoperative antisepsis: critiquing a research article.

    PubMed

    Lipp, Allyson; Edwards, Peggy

    2010-11-01

    A critique of a research article on preoperative skin antisepsis was undertaken using a recognised framework. This critique drew out issues which may be of use for clinicians in making a judgement regarding implementing change into their clinical practice.

  4. Giotto navigation support

    NASA Technical Reports Server (NTRS)

    Mottinger, N. A.; Premkumar, R. I.

    1986-01-01

    Cooperative efforts between NASA and the European Space Agency (ESA) in supporting the flight of Giotto to Halley's Comet included prelaunch checks of ESA navigation software and delivery of validated DSN radio metric tracking data during the mission. Effects of drag from passing through the coma are seen in data received pre and post encounter. The post encounter Giotto trajectory provides a solar occultation in January 1988, prior to returning to the Earth in 1990 for possible retargeting to yet another comet.

  5. Space plane navigation simulation

    NASA Astrophysics Data System (ADS)

    Matsushima, Koichi; Murata, Masaaki; Shingu, Hirokimi; Shimizu, Tetsuo; Mikami, Tatsuo; Hashida, Yoshikazu

    A simulation program for a future Japanese space-plane (SP) considered for development is presented along with the results of the analysis of a candidate navigation configuration, focused on the terminal area energy management phase and the approach/landing phase of SP. The guidance laws and aerodynamic parameters which are applied to the program for the analysis are modeled using the laws and parameters of the U.S. Space Suttle, assuming typical values for the accuracy of sensors.

  6. Preoperative prediction of severe postoperative pain.

    PubMed

    Kalkman, C J; Visser, K; Moen, J; Bonsel, G J; Grobbee, D E; Moons, K G M

    2003-10-01

    We developed and validated a prediction rule for the occurrence of early postoperative severe pain in surgical inpatients, using predictors that can be easily documented in a preoperative setting. A cohort of surgical inpatients (n=1416) undergoing various procedures except cardiac surgery and intracranial neurosurgery in a University Hospital were studied. Preoperatively the following predictors were collected: age, gender, type of scheduled surgery, expected incision size, blood pressure, heart rate, Quetelet index, the presence and severity of preoperative pain, health-related quality of life the (SF-36), Spielberger's State-Trait Anxiety Inventory (STAI) and the Amsterdam Preoperative Anxiety and Information Scale (APAIS). The outcome was the presence of severe postoperative pain (defined as Numeric Rating Scale > or =8) within the first hour postoperatively. Multivariate logistic regression in combination with bootstrapping techniques (as a method for internal validation) was used to derive a stable prediction model. Independent predictors of severe postoperative pain were younger age, female gender, level of preoperative pain, incision size and type of surgery. The area under the receiver operator characteristic (ROC) curve was 0.71 (95% CI: 0.68-0.74). Adding APAIS scores (measures of preoperative anxiety and need for information), but not STAI, provided a slightly better model (ROC area 0.73). The reliability of this extended model was good (Hosmer and Lemeshow test p-value 0.78). We have demonstrated that severe postoperative pain early after awakening from general anesthesia can be predicted with a scoring rule, using a small set of variables that can be easily obtained from all patients at the preoperative visit. Before this internally validated preoperative prediction rule can be applied in clinical practice to support anticipatory pain management, external validation in other clinical settings is necessary.

  7. 3D surgical planning and navigation for CMF surgery

    NASA Astrophysics Data System (ADS)

    Chapuis, Jonas; Rudolph, Tobias; Borgesson, Blake; De Momi, Elena; Pappas, Ion P.; Hallermann, Wok; Schramm, Alexander; Caversaccio, Marco

    2004-05-01

    In this paper we describe a system for corrective and reconstructive CMF surgery that allows planning of bone segment relocations in 3D and transfer of the goal positions into an intra-operative navigation module, which provides guidance to realize the planned movement. In addition, the pre-operative planning module offers functions of mirroring and allows insertion of distraction devices. We present three clinical cases of CMF surgical procedures planned a posteriori with our application: bimaxillary realignment, involving subcondylar osteotomy of the mandible and LeFort I osteotomy, secondary orbital reconstruction and mandibular reconstruction.

  8. Persistent and stable biases in spatial learning mechanisms predict navigational style.

    PubMed

    Furman, Andrew J; Clements-Stephens, Amy M; Marchette, Steven A; Shelton, Amy L

    2014-12-01

    A wealth of evidence in rodents and humans supports the central roles of two learning systems--hippocampal place learning and striatal response learning--in the formation of spatial representations to support navigation. Individual differences in the ways that these mechanisms are engaged during initial encoding and subsequent navigation may provide a powerful framework for explaining the wide range of variability found in the strategies and solutions that make up human navigational styles. Previous work has revealed that activation in the hippocampal and striatal networks during learning could predict navigational style. Here, we used functional magnetic resonance imaging to investigate the relative activations in these systems during both initial encoding and the act of dynamic navigation in a learned environment. Participants learned a virtual environment and were tested on subsequent navigation to targets within the environment. We observed that a given individual had a consistent balance of memory system engagement across both initial encoding and subsequent navigation, a balance that successfully predicted the participants' tendencies to use novel shortcuts versus familiar paths during dynamic navigation. This was further supported by the observation that the activation during subsequent retrieval was not dependent on the type of solution used on a given trial. Taken together, our results suggest a model in which the place- and response-learning systems are present in parallel to support a variety of navigational behaviors, but stable biases in the engagement of these systems influence what solutions might be available for any given individual.

  9. Reduced Parahippocampal Theta Activity During Spatial Navigation in Low, but Not in High Elderly Performers.

    PubMed

    Lithfous, Ségolène; Dufour, André; Bouix, Cloé; Pebayle, Thierry; Després, Olivier

    2017-06-29

    Cognitive aging varies widely among individuals. Whereas optimal cognitive agers show highly preserved cognitive functions throughout life, other subjects experience cognitive deficits in various cognitive domains. Among them, elderly individuals frequently report difficulties in spatial navigation. In this study, we aimed to determine whether elderly participants with different cognitive profiles would perform differently at a navigation task, and explore underlying medial hippocampal activity. Two groups of elderly subjects were selected, high- and low-performing (HP and LP, respectively), based on their performance on a detailed neuropsychological examination. A group of young adults was recruited as controls. Cerebral activity was recorded by electroencephalography (EEG) during a virtual navigation task in which participants had 3 trials to find their way in mazes. We analyzed theta activity during navigation in the mazes and performed source reconstruction analyses. The LP group was less accurate than the HP group during the navigation task. Theta activity during navigation was greater in HP subjects compared with controls, whereas that theta activity was reduced in LP subjects. Moreover, theta activity in the left parahippocampal gyrus increased across trials in HP, but not in LP, subjects. Elderly participants performed differently at a navigation task according to their cognitive profile: elderly with cognitive deficits seem to have greater difficulties in spatial navigation than HP elderly. Navigational difficulties in elderly with cognitive deficits might be related to functional alteration of the parahippocampal gyrus. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  10. Computer navigation results in less severe flexion contracture following total knee arthroplasty.

    PubMed

    Bin Abd Razak, Hamid Rahmatullah; Yeo Jin, Seng; Chong Chi, Hwei

    2014-12-01

    We compared postoperative flexion contracture in navigated total knee arthroplasty (TKA) versus conventional TKA. Two groups (Group 1: conventional, Group 2: navigated) of 235 consecutive patients matched for age and gender were retrospectively compared. Range of motion, mechanical axes, Knee Society Scores, Oxford Knee Scores and Short Form-36® (SF-36) scores were collected prospectively and compared preoperatively and at 2years following TKA. At 2years, patients who underwent navigated TKA averaged significantly lesser flexion contracture of 1 degree compared to 6 degrees in patients who underwent conventional TKA. There were a significantly larger proportion of outliers in the conventional group. Computer navigation results in less severe flexion contracture and less frequent flexion contracture of more than 5 degrees as compared to conventional techniques. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Preoperative diagnosis of sentinel lymph node (SLN) metastasis using 3D CT lymphography (CTLG).

    PubMed

    Nakagawa, Misako; Morimoto, Masami; Takechi, Hirokazu; Tadokoro, Yukiko; Tangoku, Akira

    2016-05-01

    Sentinel lymph node biopsy (SLNB) became a standard procedure for patients with early breast cancer, however, an indication of SLN navigation to metastatic disease may lead to misdiagnosis for staging. Preoperative CTLG with a water-soluble iodinated contrast medium visualizes the correct primary SLNs and its afferent lymphatic channels surrounding detailed anatomy, therefore it can predict LN metastasis by visualizing the lymph vessel obstruction or stain defect of the SLN by tumor. The current study presents the value of CTLG for preoperative prediction for SLN status. A total of 228 patients with Tis-T2 breast cancer who did not receive primary chemotherapy were studied. SLN metastasis was diagnosed according to the following staining patterns of SLNs and afferent lymphatic vessels: stain defect of SLN, obstruction, stagnation, dilation, and detour of the lymphatic vessels by tumor occupation. The diagnosis was compared with the pathological results to evaluate the accuracy of prediction for SLN metastasis using CTLG. Twenty-seven of 228 patients had metastatic SLN pathologically. Twenty-five of these were diagnosed as metastatic preoperatively. The accuracy for metastatic diagnosis using CTLG was 89.0%, sensitivity was 92.6%, and specificity was 88.6%. The positive predictive value was 52.1% and negative predictive value was 98.8%. CTLG can select the candidate with truly node negative cases in early breast cancer patients, because it predicts lymph node metastasis preoperatively from natural status of the lymphographic image. It also might omit the SLN biopsy itself.

  12. Aging specifically impairs switching to an allocentric navigational strategy

    PubMed Central

    Harris, Mathew A.; Wiener, Jan M.; Wolbers, Thomas

    2012-01-01

    Navigation abilities decline with age, partly due to deficits in numerous component processes. Impaired switching between these various processes (i.e., switching navigational strategies) is also likely to contribute to age-related navigational impairments. We tested young and old participants on a virtual plus maze task (VPM), expecting older participants to exhibit a specific strategy switching deficit, despite unimpaired learning of allocentric (place) and egocentric (response) strategies following reversals within each strategy. Our initial results suggested that older participants performed worse during place trial blocks but not response trial blocks, as well as in trial blocks following a strategy switch but not those following a reversal. However, we then separated trial blocks by both strategy and change type, revealing that these initial results were due to a more specific deficit in switching to the place strategy. Place reversals and switches to response, as well as response reversals, were unaffected. We argue that this specific “switch-to-place” deficit could account for apparent impairments in both navigational strategy switching and allocentric processing and contributes more generally to age-related decline in navigation. PMID:23125833

  13. Cooperative interactions between hippocampal and striatal systems support flexible navigation

    PubMed Central

    Brown, Thackery I; Ross, Robert S; Tobyne, Sean M; Stern, Chantal E

    2012-01-01

    Research in animals and humans has demonstrated that the hippocampus is critical for retrieving distinct representations of overlapping sequences of information. There is recent evidence that the caudate nucleus and orbitofrontal cortex are also involved in disambiguation of overlapping spatial representations. The hippocampus and caudate are functionally distinct regions, but both have anatomical links with the orbitofrontal cortex. The present study used an fMRI-based functional connectivity analysis in humans to examine the functional relationship between the hippocampus, caudate, and orbitofrontal cortex when participants use contextual information to navigate well-learned spatial routes which share common elements. Participants were trained outside the scanner to navigate virtual mazes from a first-person perspective. Overlapping condition mazes began and ended at distinct locations, but converged in the middle to share some hallways with another maze. Non-overlapping condition mazes did not share any hallways with any other maze. Successful navigation through the overlapping hallways required contextual information identifying the current navigational route to guide the appropriate response for a given trial. Results revealed greater functional connectivity between the hippocampus, caudate, and orbitofrontal cortex for overlapping mazes compared to non-overlapping mazes. The current findings suggest that the hippocampus and caudate interact with prefrontal structures cooperatively for successful contextually-dependent navigation. PMID:22266411

  14. Image-guided Navigation of Single-element Focused Ultrasound Transducer

    PubMed Central

    Kim, Hyungmin; Chiu, Alan; Park, Shinsuk; Yoo, Seung-Schik

    2014-01-01

    The spatial specificity and controllability of focused ultrasound (FUS), in addition to its ability to modify the excitability of neural tissue, allows for the selective and reversible neuromodulation of the brain function, with great potential in neurotherapeutics. Intra-operative magnetic resonance imaging (MRI) guidance (in short, MRg) has limitations due to its complicated examination logistics, such as fixation through skull screws to mount the stereotactic frame, simultaneous sonication in the MRI environment, and restrictions in choosing MR-compatible materials. In order to overcome these limitations, an image-guidance system based on optical tracking and pre-operative imaging data is developed, separating the imaging acquisition for guidance and sonication procedure for treatment. Techniques to define the local coordinates of the focal point of sonication are presented. First, mechanical calibration detects the concentric rotational motion of a rigid-body optical tracker, attached to a straight rod mimicking the sonication path, pivoted at the virtual FUS focus. The spatial error presented in the mechanical calibration was compensated further by MRI-based calibration, which estimates the spatial offset between the navigated focal point and the ground-truth location of the sonication focus obtained from a temperature-sensitive MR sequence. MRI-based calibration offered a significant decrease in spatial errors (1.9±0.8 mm; 57% reduction) compared to the mechanical calibration method alone (4.4±0.9 mm). Using the presented method, pulse-mode FUS was applied to the motor area of the rat brain, and successfully stimulated the motor cortex. The presented techniques can be readily adapted for the transcranial application of FUS to intact human brain. PMID:25232203

  15. Virtual screening of virtual libraries.

    PubMed

    Green, Darren V S

    2003-01-01

    Virtual screening of virtual libraries (VSVL) is a rapidly changing area of research. Great efforts are being made to produce better algorithms, selection methods and infrastructure. Yet, the number of successful examples in the literature is not impressive, although the quality of work certainly is high. Why is this? One reason is that these methods tend to be applied at the lead generation stage and therefore there is a large lead-time before successful examples appear in the literature. However, any computational chemist would confirm that these methods are successful and there exists a glut of start-up companies specialising in virtual screening. Moreover, the scientific community would not be focussing so much attention on this area if it were not yielding results. Even so, the paucity of literature data is certainly a hindrance to the development of better methods. The VSVL process is unique within the discovery process, in that it is the only method that can screen the > 10(30) genuinely novel molecules out there. Already, some VSVL methods are evaluating 10(13) compounds, a capacity that high throughput screening can only dream of. There is a huge potential advantage for the company that develops efficient and effective methods, for lead generation, lead hopping and optimization of both potency and ADME properties. To do this, it requires more than the software, it requires confidence to exploit the methodology, to commit synthesis on the basis of it, and to build this approach into the medicinal chemistry strategy. It is a fact that these tools remain quite daunting for the majority of scientists working at the bench. The routine use of these methods is not simply a matter of education and training. Integration of these methods into accessible and robust end user software, without dilution of the science, must be a priority. We have reached a coincidence, where several technologies have the required level of maturity predictive computational chemistry

  16. Exploration through Virtual Reality: Encounters with the Target Culture

    ERIC Educational Resources Information Center

    O'Brien, Mary Grantham; Levy, Richard M.

    2008-01-01

    This paper presents the results of a study on the use of a virtual reality (VR) world in a German language classroom. After participating in a lesson on the use of commands, students experienced the language and culture through navigation in a VR world. It is argued that this new medium allows for students to be immersed in the target culture and…

  17. Implant Placement Is More Accurate Using Dynamic Navigation.

    PubMed

    Block, Michael S; Emery, Robert W; Cullum, Daniel R; Sheikh, Ali

    2017-07-01

    The purpose of this prospective study was to measure and compare the accuracy and precision of dynamic navigation with freehand (FH) implant fixture placement. The authors hypothesized that the evaluated dynamic navigation system would have high accuracy and precision and would be superior to FH methods. The authors designed and implemented a prospective cohort study and enrolled patients who had implants placed from December 2014 through December 2016. The predictor variable was implant placement technique comparing fully guided (FG) and partially guided (PG) dynamic navigation with FH placement. The outcome variables were accuracy measured as deviation from the virtual plan, and precision was represented as the standard deviation of the measurements. Analysis of variance (ANOVA) was used to compare measurements. Virtual implant placement was compared with post-implant placement using mesh analysis. Deviations from the virtual plan were recorded for each implant for each surgeon. FH implant placement was evaluated by comparing a virtual plan with postoperative scans for patients who did not have the navigation system used for their implant placement. One-way ANOVA was performed to determine within-group and between-groups differences to determine whether there were meaningful differences among surgeons and methods (FG, PG, and FH) of placement. Prospective data from 478 patients involving 714 implants were evaluated. There were no demographic differences among surgeons. The sample size differed by the number of implants placed by each surgeon. Within each method group, the only difference among surgeons was angular deviation. All surgeons' data were combined. For FG navigation, the mean angular deviation was 2.97 ± 2.09°, the mean global platform position deviation was 1.16 ± 0.59 mm, and the mean global apical position deviation was 1.29 ± 0.65 mm. For PG navigation, the mean angular deviation was 3.43 ± 2.33°, the mean global platform position

  18. Using virtual menus in a virtual environment

    NASA Technical Reports Server (NTRS)

    Jacoby, Richard H.; Ellis, Stephen R.

    1992-01-01

    Virtual environment interfaces to computer programs in several diverse application areas are currently being developed. The users of virtual environments will require many different methods to interact with the environments and the objects in them. This paper reports on our use of virtual menus as a method of interacting with virtual environments. Several aspects of virtual environments make menu interactions different from interactions with conventional menus. We review the relevant aspects of conventional menus and virtual environments, in order to provide a frame of reference for the design of virtual menus. We discuss the features and interaction methodologies of two different versions of virtual menus which have been developed and used in our lab. We also examine the problems associated with our original version, and the enhancements incorporated into our current version.

  19. Aeronautic Instruments. Section VI : Aerial Navigation and Navigating Instruments

    NASA Technical Reports Server (NTRS)

    Eaton, H N

    1923-01-01

    This report outlines briefly the methods of aerial navigation which have been developed during the past few years, with a description of the different instruments used. Dead reckoning, the most universal method of aerial navigation, is first discussed. Then follows an outline of the principles of navigation by astronomical observation; a discussion of the practical use of natural horizons, such as sea, land, and cloud, in making extant observations; the use of artificial horizons, including the bubble, pendulum, and gyroscopic types. A description is given of the recent development of the radio direction finder and its application to navigation.

  20. Can active navigation be as good as driving? A comparison of spatial memory in drivers and backseat drivers.

    PubMed

    von Stülpnagel, Rul; Steffens, Melanie C

    2012-06-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario, we manipulated movement control through seating participants in the front or the back position of a tandem bike, and navigation control by presenting differently detailed maps to participants unfamiliar (Experiment 1) or familiar (Experiment 2) with an environment. Landmark knowledge was tested with recognition tasks. For participants unfamiliar with the environment (Experiment 1), passive navigation enabled better landmark recognition than active navigation, but there was no effect of movement control. For participants more familiar with the environment (Experiment 2), there was no effect of navigation control, but drivers showed better landmark recognition than backseat drivers. These findings are discussed in relation to action memory research. Measures of route and survey knowledge demonstrated that good performance resulted from active navigation (Experiment 1-2). Moreover, with regard to these measures, driving compensated for passive navigation if the environment was familiar (Experiment 2). An additional experiment in a lab setting (Experiment 3) validated the manipulation of navigation control and the used tasks and demonstrated the importance of real environment exposure. As our findings suggest, driving may be more relevant for remembering landmarks, but actively controlling navigation (even as a backseat driver) is more relevant for remembering a route than maneuvering a vehicle.

  1. Navigation in GPS Challenged Environments Based Upon Ranging Imagery

    NASA Astrophysics Data System (ADS)

    Markiel, J. N. Nikki

    , particularly with respect to 2D datasets, has long been a difficult proposition when attempting to link overlapping data sets. 2) Secondly, an innovative methodology to segment a set of discrete 3D range measurements is presented. 3) Finally, the research develops a methodology to support navigation in environments previously infeasible for autonomous vehicles due to lack of position updates. This problem is well known in the navigation field; while Global Positioning Systems (GPS) provide excellent positional information, their signals can become unavailable in a wide variety of conditions. Current research in robotic manipulation rarely addresses the concept of operations within an unknown environment, and virtually never attempts navigation in the presence of non-static objects. The ability to extend the navigation solution beyond these limitations extends the possibilities for autonomous navigation and advances the field of navigation. The current algorithm cannot provide a navigation solution for an indefinite time period; it can extend the feasible extent of navigation without benefit of GPS positioning. While this research could not possibly claim to solve the problem of autonomous navigation, it represents an important step towards the vision of developing a machine to emulate cognitive navigation.

  2. Principles of JTIDS Relative Navigation

    NASA Astrophysics Data System (ADS)

    Ranger, J. F. O.

    This paper describes one of the key features of the JTIDS/Link 16 tactical data-link, namely its relative navigation facility. A brief overview of the general features of the JTIDS system is given to provide the necessary background to the navigation aspects, and some mention is made of the message-exchange facilities. The main part of the paper describes how the JTIDS system provides the capability to perform accurate navigation, and discusses the basic principles of its operation. Some applications of the navigation function which enhance operational effectiveness are then described. The following topics are covered:(ii) JTIDS Architecture(i) Definition of JTIDS/Link 16(iii) Principles of Relative Navigation(iv) Source Selection(v) The Kalman Filter(vi) Time Synchronization(vii) The Use of Relative Navigation(viii) The Relative Grid

  3. Effect of viewing mode on pathfinding in immersive Virtual Reality.

    PubMed

    White, Paul J; Byagowi, Ahmad; Moussavi, Zahra

    2015-08-01

    The use of Head Mounted Displays (HMDs) to view Virtual Reality Environments (VREs) has received much attention recently. This paper reports on the difference between actual humans' navigation in a VRE viewed through an HMD compared to that in the same VRE viewed on a laptop PC display. A novel Virtual Reality (VR) Navigation input device (VRNChair), designed by our team, was paired with an Oculus Rift DK2 Head-Mounted Display (HMD). People used the VRNChair to navigate a VRE, and we analyzed their navigational trajectories with and without the HMD to investigate plausible differences in performance due to the display device. It was found that people's navigational trajectories were more accurate while wearing the HMD compared to viewing an LCD monitor; however, the duration to complete a navigation task remained the same. This implies that increased immersion in VR results in an improvement in pathfinding. In addition, motion sickness caused by using an HMD can be reduced if one uses an input device such as our VRNChair. The VRNChair paired with an HMD provides vestibular stimulation as one moves in the VRE, because movements in the VRE are synchronized with movements in the real environment.

  4. Surgical safety of cervical pedicle screw placement with computer navigation system.

    PubMed

    Shimokawa, Nobuyuki; Takami, Toshihiro

    2017-04-01

    Cervical pedicle screw (CPS) may be the biomechanically best system for posterior cervical segmental fixation, but may carry a surgery-related risk. The purpose of this study was to evaluate the safety of CPS placement using computer navigation system for posterior cervical instrumented fixation and discuss its complication avoidance and management. Posterior cervical instrumented fixation using CPS was performed in a total of 128 patients during the period between 2007 and 2015. Intraoperative image guidance was achieved using a preoperative 3D CT-based or an intraoperative 3D CT-based navigation system. A total of 762 CPSs were placed in the spine level of C2 to Th3. The radiological accuracy of CPS placement was evaluated using postoperative CT. Accuracy of CPS placement using a preoperative 3D CT-based navigation system was 93.6 % (423 of 452 screws) in grade 0; the screw was completely contained in the pedicle, and accuracy of CPS placement using an intraoperative 3D CT-based navigation system was a little bit improved to 97.1 % (301 of 310 screws) in grade 0. CPS misplacement (more than half of screw) was 3.3 % (15 of 452 screws) using a preoperative 3D CT-based navigation system, and CPS misplacement (more than half of screw) was 0.6 % (2 of 310 screws) using an intraoperative 3D CT-based navigation system. In total, 38 screws (5.0 %) were found to perforate the cortex of pedicle, although any neural or vascular complications closely associated with CPS placement were not encountered. Twenty nine of 38 screws (76.3 %) were found to perforate laterally, and seven screws (18.4 %) were found to perforate medially. Image-guided CPS placement has been an important advancement to secure the safe surgery, although the use of CPS placement needs to be carefully determined based on the individual pathology.

  5. Three-Dimensional Virtual Bone Bank System Workflow for Structural Bone Allograft Selection: A Technical Report

    PubMed Central

    Ritacco, Lucas Eduardo; Farfalli, German Luis; Milano, Federico Edgardo; Ayerza, Miguel Angel; Muscolo, Domingo Luis

    2013-01-01

    Structural bone allograft has been used in bone defect reconstruction during the last fifty years with acceptable results. However, allograft selection methods were based on 2-dimensional templates using X-rays. Thanks to preoperative planning platforms, three-dimensional (3D) CT-derived bone models were used to define size and shape comparison between host and donor. The purpose of this study was to describe the workflow of this virtual technique in order to explain how to choose the best allograft using a virtual bone bank system. We measured all bones in a 3D virtual environment determining the best match. The use of a virtual bone bank system has allowed optimizing the allograft selection in a bone bank, providing more information to the surgeons before surgery. In conclusion, 3D preoperative planning in a virtual environment for allograft selection is an important and helpful tool in order to achieve a good match between host and donor. PMID:23690733

  6. On Navigation Sensor Error Correction

    NASA Astrophysics Data System (ADS)

    Larin, V. B.

    2016-01-01

    The navigation problem for the simplest wheeled robotic vehicle is solved by just measuring kinematical parameters, doing without accelerometers and angular-rate sensors. It is supposed that the steerable-wheel angle sensor has a bias that must be corrected. The navigation parameters are corrected using the GPS. The approach proposed regards the wheeled robot as a system with nonholonomic constraints. The performance of such a navigation system is demonstrated by way of an example

  7. Virtual reality and computer-enhanced training applied to wheeled mobility: an overview of work in Pittsburgh.

    PubMed

    Cooper, Rory A; Ding, Dan; Simpson, Richard; Fitzgerald, Shirley G; Spaeth, Donald M; Guo, Songfeng; Koontz, Alicia M; Cooper, Rosemarie; Kim, Jongbae; Boninger, Michael L

    2005-01-01

    Some aspects of assistive technology can be enhanced by the application of virtual reality. Although virtual simulation offers a range of new possibilities, learning to navigate in a virtual environment is not equivalent to learning to navigate in the real world. Therefore, virtual reality simulation is advocated as a useful preparation for assessment and training within the physical environment. We are engaged in several efforts to develop virtual environments and devices for mobility skills assessment and training, exercise training, and environment assessment. Virtual reality offers wheelchair users a training tool in different risk-free environments without any indoor (e.g., walls, furniture, and stairs) and outdoor (e.g., curb cuts, uneven terrain, and street traffic) physical constraints. Virtual reality technology will probably become more common in the field of assistive technology, especially given the rapid expansion of gaming technology and the continued exponential growth of computing power.

  8. Satellite Navigation Backup Study

    DTIC Science & Technology

    2007-09-19

    Stakeholder 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Ov era ll All AC All G A Go v/S tnd s To tal U S US AC US G A US G ov /St nd s To tal E uro pe Eu rop...Engineering and Technology of Ohio University, Jacob L. Campbell contains a good survey of TRN technology history, applications, and component trade...71 Honeywell Precision Terrain Aided Navigation (PTAN) summary found in Jacob L. Campbell citation. NGATS Institute

  9. Fundamentals of satellite navigation

    NASA Astrophysics Data System (ADS)

    Stiller, A. H.

    The basic operating principles and capabilities of conventional and satellite-based navigation systems for air, sea, and land vehicles are reviewed and illustrated with diagrams. Consideration is given to autonomous onboard systems; systems based on visible or radio beacons; the Transit, Cicada, Navstar-GPS, and Glonass satellite systems; the physical laws and parameters of satellite motion; the definition of time in satellite systems; and the content of the demodulated GPS data signal. The GPS and Glonass data format frames are presented graphically, and tables listing the GPS and Glonass satellites, their technical characteristics, and the (past or scheduled) launch dates are provided.

  10. Waves at Navigation Structures

    DTIC Science & Technology

    2014-10-27

    upgrades the Coastal Modeling System’s ( CMS ) wave model CMS -Wave, a phase-averaged spectral wave model, and BOUSS-2D, a Boussinesq-type nonlinear wave...provided by this work unit address these critical needs of the Corps’ navigation mission. Description Issue Addressed CMS -Wave application at Braddock...Bay, NY WaveNet application in Gulf of Mexico CMS -Wave and BOUSS-2D are two numerical wave models, and WaveNet and TideNet are two web-based

  11. A Microscopic Optically Tracking Navigation System That Uses High-resolution 3D Computer Graphics.

    PubMed

    Yoshino, Masanori; Saito, Toki; Kin, Taichi; Nakagawa, Daichi; Nakatomi, Hirofumi; Oyama, Hiroshi; Saito, Nobuhito

    2015-01-01

    Three-dimensional (3D) computer graphics (CG) are useful for preoperative planning of neurosurgical operations. However, application of 3D CG to intraoperative navigation is not widespread because existing commercial operative navigation systems do not show 3D CG in sufficient detail. We have developed a microscopic optically tracking navigation system that uses high-resolution 3D CG. This article presents the technical details of our microscopic optically tracking navigation system. Our navigation system consists of three components: the operative microscope, registration, and the image display system. An optical tracker was attached to the microscope to monitor the position and attitude of the microscope in real time; point-pair registration was used to register the operation room coordinate system, and the image coordinate system; and the image display system showed the 3D CG image in the field-of-view of the microscope. Ten neurosurgeons (seven males, two females; mean age 32.9 years) participated in an experiment to assess the accuracy of this system using a phantom model. Accuracy of our system was compared with the commercial system. The 3D CG provided by the navigation system coincided well with the operative scene under the microscope. Target registration error for our system was 2.9 ± 1.9 mm. Our navigation system provides a clear image of the operation position and the surrounding structures. Systems like this may reduce intraoperative complications.

  12. A Microscopic Optically Tracking Navigation System That Uses High-resolution 3D Computer Graphics

    PubMed Central

    YOSHINO, Masanori; SAITO, Toki; KIN, Taichi; NAKAGAWA, Daichi; NAKATOMI, Hirofumi; OYAMA, Hiroshi; SAITO, Nobuhito

    2015-01-01

    Three-dimensional (3D) computer graphics (CG) are useful for preoperative planning of neurosurgical operations. However, application of 3D CG to intraoperative navigation is not widespread because existing commercial operative navigation systems do not show 3D CG in sufficient detail. We have developed a microscopic optically tracking navigation system that uses high-resolution 3D CG. This article presents the technical details of our microscopic optically tracking navigation system. Our navigation system consists of three components: the operative microscope, registration, and the image display system. An optical tracker was attached to the microscope to monitor the position and attitude of the microscope in real time; point-pair registration was used to register the operation room coordinate system, and the image coordinate system; and the image display system showed the 3D CG image in the field-of-view of the microscope. Ten neurosurgeons (seven males, two females; mean age 32.9 years) participated in an experiment to assess the accuracy of this system using a phantom model. Accuracy of our system was compared with the commercial system. The 3D CG provided by the navigation system coincided well with the operative scene under the microscope. Target registration error for our system was 2.9 ± 1.9 mm. Our navigation system provides a clear image of the operation position and the surrounding structures. Systems like this may reduce intraoperative complications. PMID:26226982

  13. Space shuttle navigation analysis. Volume 1: GPS aided navigation

    NASA Technical Reports Server (NTRS)

    Matchett, G. A.; Vogel, M. A.; Macdonald, T. J.

    1980-01-01

    Analytical studies related to space shuttle navigation are presented. Studies related to the addition of NAVSTAR Global Positioning System user equipment to the shuttle avionics suite are presented. The GPS studies center about navigation accuracy covariance analyses for both developmental and operational phases of GPS, as well as for various orbiter mission phases.

  14. Acetabular component navigation in lateral decubitus based on EOS imaging: A preliminary study of 13 cases.

    PubMed

    Billaud, A; Verdier, N; de Bartolo, R; Lavoinne, N; Chauveaux, D; Fabre, T

    2015-05-01

    Acetabular component navigation classically requires palpation of the bone landmarks defining the anterior pelvic plane (APP) (anterior superior iliac spine [ASIS] and pubis), the recording of which is not very reliable when performed in lateral decubitus. The objectives of the current experimental study were: (1) to assess the clinical feasibility of NAVEOS navigation (based on EOS imaging) in lateral decubitus; and (2) to compare precision versus classical APP-based navigation (NAVAPP). Iliac plane navigation using EOS is as reliable as APP navigation. A continuous prospective series of 13 total hip replacements were implanted in lateral decubitus under APP-guided navigation (NAVAPP). Planning used preoperative EOS measurement. The ASIS, pubis and ipsilateral posterior superior iliac spine (PSIS) were located and exported to the navigator. Intra-operatively, NAVEOS landmarks (acetabular center, ASIS and PSIS on the operated side) were palpated. Postoperatively, cup inclination and anteversion with respect to the APP were measured on EOS imaging (SterEOS3D software). The SterEOS3D measurements were compared to those of the performed NAVAPP and simulated NAVEOS navigations. Three patients were excluded for technical reasons. In the remaining 10, inclination on NAVAPP and SterEOS3D differed by a median 4° (range, 0-12°), and on NAVEOS versus SteEOS3D by 5° (range, 2-10°); anteversion on NAVAPP and SterEOS3D differed by a median 4.5° (range, 0-12°), and on NAVEOS versus SteEOS3D by 4° (range, 0-14°). Precision was comparable between NAVEOS and classical navigation. NAVEOS simplifies cup navigation in lateral decubitus on initial acquisition. These results require validation on a larger sample. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  15. Learning for Autonomous Navigation

    NASA Technical Reports Server (NTRS)

    Angelova, Anelia; Howard, Andrew; Matthies, Larry; Tang, Benyang; Turmon, Michael; Mjolsness, Eric

    2005-01-01

    Robotic ground vehicles for outdoor applications have achieved some remarkable successes, notably in autonomous highway following (Dickmanns, 1987), planetary exploration (1), and off-road navigation on Earth (1). Nevertheless, major challenges remain to enable reliable, high-speed, autonomous navigation in a wide variety of complex, off-road terrain. 3-D perception of terrain geometry with imaging range sensors is the mainstay of off-road driving systems. However, the stopping distance at high speed exceeds the effective lookahead distance of existing range sensors. Prospects for extending the range of 3-D sensors is strongly limited by sensor physics, eye safety of lasers, and related issues. Range sensor limitations also allow vehicles to enter large cul-de-sacs even at low speed, leading to long detours. Moreover, sensing only terrain geometry fails to reveal mechanical properties of terrain that are critical to assessing its traversability, such as potential for slippage, sinkage, and the degree of compliance of potential obstacles. Rovers in the Mars Exploration Rover (MER) mission have got stuck in sand dunes and experienced significant downhill slippage in the vicinity of large rock hazards. Earth-based off-road robots today have very limited ability to discriminate traversable vegetation from non-traversable vegetation or rough ground. It is impossible today to preprogram a system with knowledge of these properties for all types of terrain and weather conditions that might be encountered.

  16. Learning for Autonomous Navigation

    NASA Technical Reports Server (NTRS)

    Angelova, Anelia; Howard, Andrew; Matthies, Larry; Tang, Benyang; Turmon, Michael; Mjolsness, Eric

    2005-01-01

    Robotic ground vehicles for outdoor applications have achieved some remarkable successes, notably in autonomous highway following (Dickmanns, 1987), planetary exploration (1), and off-road navigation on Earth (1). Nevertheless, major challenges remain to enable reliable, high-speed, autonomous navigation in a wide variety of complex, off-road terrain. 3-D perception of terrain geometry with imaging range sensors is the mainstay of off-road driving systems. However, the stopping distance at high speed exceeds the effective lookahead distance of existing range sensors. Prospects for extending the range of 3-D sensors is strongly limited by sensor physics, eye safety of lasers, and related issues. Range sensor limitations also allow vehicles to enter large cul-de-sacs even at low speed, leading to long detours. Moreover, sensing only terrain geometry fails to reveal mechanical properties of terrain that are critical to assessing its traversability, such as potential for slippage, sinkage, and the degree of compliance of potential obstacles. Rovers in the Mars Exploration Rover (MER) mission have got stuck in sand dunes and experienced significant downhill slippage in the vicinity of large rock hazards. Earth-based off-road robots today have very limited ability to discriminate traversable vegetation from non-traversable vegetation or rough ground. It is impossible today to preprogram a system with knowledge of these properties for all types of terrain and weather conditions that might be encountered.

  17. Benefits of pre-operative information programmes.

    PubMed

    Garretson, Sharon

    Thousands of patients undergo surgical procedures daily. Research has shown the benefits of giving pre-operative information to patients, which include decreased length of stay, less demand for analgesia post-operatively and increased patient satisfaction. However, despite this evidence, there are still many facilities with no formal policy or programme for giving pre-operative information. Nurses and managers should be made aware of the benefits and potential financial savings of pre-operative information programmes. Once education takes place, a concerted multidisciplinary effort should be made to implement a programme. This will help to ensure that patients no longer arrive at the operating theatre frightened and unaware of what will happen to them.

  18. Rethinking Virtual School

    ERIC Educational Resources Information Center

    Schomburg, Gary; Rippeth, Michelle

    2009-01-01

    Virtual schooling has been touted as one of the best ways to meet the needs of at-risk students, but what happens when a district's virtual education program is unsuccessful? That was the problem in Eastern Local School District, a small rural district in Beaver, Ohio. The district contracted virtual school services and used the virtual school for…

  19. Virtual Worlds, Real Learning

    ERIC Educational Resources Information Center

    Meyers, Eric M.

    2009-01-01

    Many children between the ages of four and twelve log in to Web-based virtual play spaces each day, and these virtual worlds are quickly becoming an important aspect of their out-of-school lives. Consequently, educators' challenge is to see how they can leverage virtual spaces, such as the virtual play spaces, for learning and literacy. Over the…

  20. Rethinking Virtual School

    ERIC Educational Resources Information Center

    Schomburg, Gary; Rippeth, Michelle

    2009-01-01

    Virtual schooling has been touted as one of the best ways to meet the needs of at-risk students, but what happens when a district's virtual education program is unsuccessful? That was the problem in Eastern Local School District, a small rural district in Beaver, Ohio. The district contracted virtual school services and used the virtual school for…

  1. 14 CFR 121.389 - Flight navigator and specialized navigation equipment.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Flight navigator and specialized navigation....389 Flight navigator and specialized navigation equipment. (a) No certificate holder may operate an... flight navigator certificate; or (2) Specialized means of navigation approved in accordance with § 121...

  2. 14 CFR 121.389 - Flight navigator and specialized navigation equipment.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Flight navigator and specialized navigation....389 Flight navigator and specialized navigation equipment. (a) No certificate holder may operate an... flight navigator certificate; or (2) Specialized means of navigation approved in accordance with § 121...

  3. 14 CFR 121.389 - Flight navigator and specialized navigation equipment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Flight navigator and specialized navigation....389 Flight navigator and specialized navigation equipment. (a) No certificate holder may operate an... flight navigator certificate; or (2) Specialized means of navigation approved in accordance with § 121...

  4. 14 CFR 121.389 - Flight navigator and specialized navigation equipment.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Flight navigator and specialized navigation....389 Flight navigator and specialized navigation equipment. (a) No certificate holder may operate an... flight navigator certificate; or (2) Specialized means of navigation approved in accordance with § 121...

  5. 14 CFR 121.389 - Flight navigator and specialized navigation equipment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Flight navigator and specialized navigation....389 Flight navigator and specialized navigation equipment. (a) No certificate holder may operate an... flight navigator certificate; or (2) Specialized means of navigation approved in accordance with § 121...

  6. Virtual Rover Drives Toward Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows a screenshot from the software used by engineers to test and drive the Mars Exploration Rover Spirit. The software simulates the rover's movements across the martian terrain, helping to plot a safe course. Here, engineers simulated Spirit's first post-egress drive on Mars Sunday. The 3-meter (10-foot) drive totaled approximately 30 minutes, including time to stop and take images. The rover drove toward its first rock target, a mountain-shaped rock called Adirondack. The blue line denotes the path of the rover's 'belly button,' as engineers like to call it, as the rover drove toward Adirondack. The virtual 3-D world around the rover was built from images taken by Spirit's stereo navigation cameras. Regions for which the rover has not yet acquired 3-D data are represented in beige.

  7. Learning navigation – Learning with navigation. A review

    PubMed Central

    Jenny, Jean-Yves; Picard, Frederic

    2017-01-01

    The goal of this review paper is to retrieve from the existing literature relevant information (1) about the learning curve of the currently existing navigation systems and (2) about the use of navigation system for teaching orthopaedic procedures. All studies reporting on the learning curve of navigation systems support the hypothesis that computer-navigated total knee arthroplasty (TKA) involves only a short learning curve and that beginners can obtain good results from the beginning of their experience, as navigation provides continuous feedback during all phases of the knee replacement surgery and allows for correcting any bone cut errors. Interestingly, there is no comparable research on the learning curve of TKA with standard, manual instrumentation. One might postulate that this learning curve might be longer than with navigation, with potentially a higher rate of outliers. The current literature does support that navigation may be an efficient teaching tool for both experienced orthopaedic surgeons and trainees. Experienced surgeons may improve their skills with conventional techniques and learn new techniques more efficiently and more quickly. Trainees may have a better understanding of the procedure and learn standard techniques with a shorter learning curve. This is probably due to the immediate feedback of navigation systems. A shorter learning curve may be associated with improved clinical and functional results for the patient during this critical period. However, there is no evidence that training with navigation excludes trainees from the need to work in academic environments with experienced teachers. Future techniques in training may include the development of laboratory simulation procedures using navigated feedback. PMID:28573966

  8. The role of preoperative CT scan in patients with tracheoesophageal fistula: a review.

    PubMed

    Garge, Saurabh; Rao, K L N; Bawa, Monika

    2013-09-01

    The morbidity and mortality associated with esophageal atresia with or without a fistula make it a challenging congenital abnormality for the pediatric surgeon. Anatomic factors like inter-pouch gap and origin of fistula are not taken into consideration in various prognostic classifications. The preoperative evaluation of these cases with computerized tomography (CT) has been used by various investigators to delineate these factors. We reviewed these studies to evaluate the usefulness of this investigation in the intra operative and post operative period. A literature search was done on all peer-reviewed articles published on preoperative computed tomography (CT) in cases of tracheoesophageal fistula using the PUBMED and MEDLINE search engines. Key words included tracheoesophageal fistula, computerized tomography, virtual bronchoscopy, and 3D computerized tomography reconstruction. Further, additional articles were selected from the list of references obtained from the retrieved publications. A total of 8 articles were selected for analysis. In most of the studies, comprising 96 patients, observations noted in preoperative CT were confirmed during surgery. In a study by Mahalik et al [Mahalik SK, Sodhi KS, Narasimhan KL, Rao KL. Role of preoperative 3D CT reconstruction for evaluation of patients with esophageal atresia and tracheoesophageal fistula. Pediatr Surg Int. 2012 Jun 22. [Epub ahead of print

  9. Development of preoperative planning software for transforaminal endoscopic surgery and the guidance for clinical applications.

    PubMed

    Chen, Xiaojun; Cheng, Jun; Gu, Xin; Sun, Yi; Politis, Constantinus

    2016-04-01

    Preoperative planning is of great importance for transforaminal endoscopic techniques applied in percutaneous endoscopic lumbar discectomy. In this study, a modular preoperative planning software for transforaminal endoscopic surgery was developed and demonstrated. The path searching method is based on collision detection, and the oriented bounding box was constructed for the anatomical models. Then, image reformatting algorithms were developed for multiplanar reconstruction which provides detailed anatomical information surrounding the virtual planned path. Finally, multithread technique was implemented to realize the steady-state condition of the software. A preoperative planning software for transforaminal endoscopic surgery (TE-Guider) was developed; seven cases of patients with symptomatic lumbar disc herniations were planned preoperatively using TE-Guider. The distances to the midlines and the direction of the optimal paths were exported, and each result was in line with the empirical value. TE-Guider provides an efficient and cost-effective way to search the ideal path and entry point for the puncture. However, more clinical cases will be conducted to demonstrate its feasibility and reliability.

  10. Virtual Laboratories

    NASA Astrophysics Data System (ADS)

    Hut, P.

    At the frontier of most areas in science, computer simulations playa central role. The traditional division of natural science into experimental and theoretical investigations is now completely outdated. Instead, theory, simulation, and experimentation form three equally essential aspects, each with its own unique flavor and challenges. Yet, education in computational science is still lagging far behind, and the number of text books in this area is minuscule compared to the many text books on theoretical and experimental science. As a result, many researchers still carry out simulations in a haphazard way, without properly setting up the computational equivalent of a well equipped laboratory. The art of creating such a virtual laboratory, while providing proper extensibility and documentation, is still in its infancy. A new approach is described here, Open Knowledge, as an extension of the notion of Open Source software. Besides open source code, manuals, and primers, an open knowledge project provides simulated dialogues between code developers, thus sharing not only the code, but also the motivations behind the code.

  11. [Preoperative correction of volemic disorders in thyrotoxicosis].

    PubMed

    Lukomskiĭ, G I; Ivanova, N A; Krivenko, N G

    1976-01-01

    The investigations conducted by the authors enabled them to pinpoint further the complex of symptoms determining a phase character of volemic disturbances in thyrotoxicosis. The phases somewhat reveal the volemic substrate of thyrotoxicosis, allowing an aimed management of some stages of the preoperative preparation. The latter is conventionally divided according to Sh. Milk into three periods: initial, intermediate and final. The main aim of the preoperative correction is to normalize hydration correlations, that is likely to be gained by excreting excessive sodium and replenishment of potassium deficit.

  12. Navigating the Seas of Policy.

    ERIC Educational Resources Information Center

    Cunningham, Stephanie; Kennedy, Steve; McAlonan, Susan; Hotchkiss, Heather

    As the sun, moon, and stars helped sea captains to navigate, policy (defined as a formalized idea to encourage change) indicates general direction and speed but does not establish a specific approach to achieve implementation. Formal and informal policies have advantages and disadvantages. These are steps in navigating policy formation: identify…

  13. Introductory Course on Satellite Navigation

    ERIC Educational Resources Information Center

    Giger, Kaspar; Knogl, J. Sebastian

    2012-01-01

    Satellite navigation is widely used for personal navigation and more and more in precise and safety-critical applications. Thus, the subject is suited for attracting the interest of young people in science and engineering. The practical applications allow catching the students' attention for the theoretical background. Educational material on the…

  14. A Navigation Compendium. Revised Edition.

    ERIC Educational Resources Information Center

    Naval Training Command, Pensacola, FL.

    This unit of instruction was prepared for use in navigation study at the Officer Candidate School, the various Naval ROTC Units, and within the fleet. It is considered a naval text. It covers a wide and expanding subject area with brevity. Basic and elementary navigational terms and instruments are presented and described. The use of charts and…

  15. Visual Navigation in Nocturnal Insects.

    PubMed

    Warrant, Eric; Dacke, Marie

    2016-05-01

    Despite their tiny eyes and brains, nocturnal insects have evolved a remarkable capacity to visually navigate at night. Whereas some use moonlight or the stars as celestial compass cues to maintain a straight-line course, others use visual landmarks to navigate to and from their nest. These impressive abilities rely on highly sensitive compound eyes and specialized visual processing strategies in the brain.

  16. Sea turtles: navigating with magnetism.

    PubMed

    Lohmann, Kenneth J

    2007-02-06

    Young sea turtles use the Earth's magnetic field as a source of navigational information during their epic transoceanic migrations and while homing. A new study using satellite telemetry has now demonstrated for the first time that adult turtles also navigate using the Earth's magnetic field.

  17. Virtual button interface

    DOEpatents

    Jones, J.S.

    1999-01-12

    An apparatus and method of issuing commands to a computer by a user interfacing with a virtual reality environment are disclosed. To issue a command, the user directs gaze at a virtual button within the virtual reality environment, causing a perceptible change in the virtual button, which then sends a command corresponding to the virtual button to the computer, optionally after a confirming action is performed by the user, such as depressing a thumb switch. 4 figs.

  18. Virtual button interface

    DOEpatents

    Jones, Jake S.

    1999-01-01

    An apparatus and method of issuing commands to a computer by a user interfacing with a virtual reality environment. To issue a command, the user directs gaze at a virtual button within the virtual reality environment, causing a perceptible change in the virtual button, which then sends a command corresponding to the virtual button to the computer, optionally after a confirming action is performed by the user, such as depressing a thumb switch.

  19. The real-world navigator

    NASA Technical Reports Server (NTRS)

    Balabanovic, Marko; Becker, Craig; Morse, Sarah K.; Nourbakhsh, Illah R.

    1994-01-01

    The success of every mobile robot application hinges on the ability to navigate robustly in the real world. The problem of robust navigation is separable from the challenges faced by any particular robot application. We offer the Real-World Navigator as a solution architecture that includes a path planner, a map-based localizer, and a motion control loop that combines reactive avoidance modules with deliberate goal-based motion. Our architecture achieves a high degree of reliability by maintaining and reasoning about an explicit description of positional uncertainty. We provide two implementations of real-world robot systems that incorporate the Real-World Navigator. The Vagabond Project culminated in a robot that successfully navigated a portion of the Stanford University campus. The Scimmer project developed successful entries for the AIAA 1993 Robotics Competition, placing first in one of the two contests entered.

  20. Virtual Goods Recommendations in Virtual Worlds

    PubMed Central

    Chen, Kuan-Yu; Liao, Hsiu-Yu; Chen, Jyun-Hung; Liu, Duen-Ren

    2015-01-01

    Virtual worlds (VWs) are computer-simulated environments which allow users to create their own virtual character as an avatar. With the rapidly growing user volume in VWs, platform providers launch virtual goods in haste and stampede users to increase sales revenue. However, the rapidity of development incurs virtual unrelated items which will be difficult to remarket. It not only wastes virtual global companies' intelligence resources, but also makes it difficult for users to find suitable virtual goods fit for their virtual home in daily virtual life. In the VWs, users decorate their houses, visit others' homes, create families, host parties, and so forth. Users establish their social life circles through these activities. This research proposes a novel virtual goods recommendation method based on these social interactions. The contact strength and contact influence result from interactions with social neighbors and influence users' buying intention. Our research highlights the importance of social interactions in virtual goods recommendation. The experiment's data were retrieved from an online VW platform, and the results show that the proposed method, considering social interactions and social life circle, has better performance than existing recommendation methods. PMID:25834837