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Sample records for preoperative virtual navigation

  1. Navigation in virtual environments

    NASA Astrophysics Data System (ADS)

    Arthur, Erik; Hancock, Peter A.; Telke, Susan

    1996-06-01

    Virtual environments show great promise in the area of training. ALthough such synthetic environments project homeomorphic physical representations of real- world layouts, it is not known how individuals develop models to match such environments. To evaluate this process, the present experiment examined the accuracy of triadic representations of objects having learned them previously under different conditions. The layout consisted of four different colored spheres arranged on a flat plane. These objects could be viewed in either a free navigation virtual environment condition (NAV) or a single body position virtual environment condition. The first condition allowed active exploration of the environment while the latter condition allowed the participant only a passive opportunity to observe form a single viewpoint. These viewing conditions were a between-subject variable with ten participants randomly assigned to each condition. Performance was assessed by the response latency to judge the accuracy of a layout of three objects over different rotations. Results showed linear increases in response latency as the rotation angle increased from the initial perspective in SBP condition. The NAV condition did not show a similar effect of rotation angle. These results suggest that the spatial knowledge acquisition from virtual environments through navigation is similar to actual navigation.

  2. 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.

  3. Interactive virtual navigation in human organs

    NASA Astrophysics Data System (ADS)

    Li, Guangming; Tian, Jie; Zhao, Mingchang; He, Huiguang

    2003-09-01

    Virtual endoscopy is meaningful for medical diagnosis and surgery. In this paper, a system framework for virtual endoscopy is proposed including automatic centerline extraction and view-dependent level-of-detail rendering techniques. Combining Hessian Matrix with distance mapping, our path planning method can generate accurate skeleton for virtual navigation. Furthermore real tim rendering can be achieved with our new view-dependent subdivision algorithm. The experimental results show the efficiency of our methods.

  4. 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.

  5. 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. PMID:27229765

  6. 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.

  7. 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.

  8. 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.

  9. NES: How to Navigate the Virtual Campus

    NASA Video Gallery

    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...

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

    PubMed

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

    2016-06-01

    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

  11. [Evaluation of a preoperative virtual tour for parents and children].

    PubMed

    Tourigny, Jocelyne; Chartrand, Julie

    2009-03-01

    A Canadian pediatric center has set a preoperative virtual tour on its website. This tour was evaluated by a descriptive study, in terms of utilization, efficacy and usefulness. The tour was utilized by 49.6% of the 123 families. Children of these families had a significant increase in knowledge from Time I (preop clinic) to Time 2 (day of surgery). Children and youth who did not use the tour reported themselves as more anxious the day of surgery but not significantly. There was no significant change in parents. The internet is a useful tool in families' preparation but cannot replace a direct interaction. Other researches are necessary in order to evaluate the impact of this type of preparation on the quality of care and on the child's recovery. PMID:19388414

  12. Effects of active navigation on object recognition in virtual environments.

    PubMed

    Hahm, Jinsun; Lee, Kanghee; Lim, Seung-Lark; Kim, Sei-Young; Kim, Hyun-Taek; Lee, Jang-Han

    2007-04-01

    We investigated the importance and efficiency of active and passive exploration on the recognition of objects in a variety of virtual environments (VEs). In this study, 54 participants were randomly allocated into one of active and passive navigation conditions. Active navigation was performed by allowing participants to self-pace and control their own navigation, but passive navigation was conducted by forced navigation. After navigating VEs, participants were asked to recognize the objects that had been in the VEs. Active navigation condition had a significantly higher percentage of hit responses (t (52) = 4.000, p < 0.01), and a significantly lower percentage of miss responses (t (52) = -3.763, p < 0.01) in object recognition than the passive condition. These results suggest that active navigation plays an important role in spatial cognition as well as providing an explanation for the efficiency of learning in a 3D-based program. PMID:17474852

  13. Human hippocampal theta activity during virtual navigation.

    PubMed

    Ekstrom, Arne D; Caplan, Jeremy B; Ho, Emily; Shattuck, Kirk; Fried, Itzhak; Kahana, Michael J

    2005-01-01

    This study examines whether 4-8-Hz theta oscillations can be seen in the human hippocampus, and whether these oscillations increase during virtual movement and searching, as they do in rodents. Recordings from both hippocampal and neocortical depth electrodes were analyzed while six epileptic patients played a virtual taxi-driver game. During the game, the patients alternated between searching for passengers, whose locations were random, and delivering them to stores, whose locations remained constant. In both hippocampus and neocortex, theta increased during virtual movement in all phases of the game. Hippocampal and neocortical theta activity were also significantly correlated with each other, but this correlation did not differ between neocortex and hippocampus and within disparate neocortical electrodes. Our findings demonstrate the existence of movement-related theta oscillations in human hippocampus, and suggest that both cortical and hippocampal oscillations play a role in attention and sensorimotor integration. PMID:16114040

  14. Image-based path planning for automated virtual colonoscopy navigation

    NASA Astrophysics Data System (ADS)

    Hong, Wei

    2008-03-01

    Virtual colonoscopy (VC) is a noninvasive method for colonic polyp screening, by reconstructing three-dimensional models of the colon using computerized tomography (CT). In virtual colonoscopy fly-through navigation, it is crucial to generate an optimal camera path for efficient clinical examination. In conventional methods, the centerline of the colon lumen is usually used as the camera path. In order to extract colon centerline, some time consuming pre-processing algorithms must be performed before the fly-through navigation, such as colon segmentation, distance transformation, or topological thinning. In this paper, we present an efficient image-based path planning algorithm for automated virtual colonoscopy fly-through navigation without the requirement of any pre-processing. Our algorithm only needs the physician to provide a seed point as the starting camera position using 2D axial CT images. A wide angle fisheye camera model is used to generate a depth image from the current camera position. Two types of navigational landmarks, safe regions and target regions are extracted from the depth images. Camera position and its corresponding view direction are then determined using these landmarks. The experimental results show that the generated paths are accurate and increase the user comfort during the fly-through navigation. Moreover, because of the efficiency of our path planning algorithm and rendering algorithm, our VC fly-through navigation system can still guarantee 30 FPS.

  15. Evidence of Separable Spatial Representations in a Virtual Navigation Task

    ERIC Educational Resources Information Center

    Gramann, Klaus; Muller, Hermann J.; Eick, Eva-Maria; Schonebeck, Bernd

    2005-01-01

    Three experiments investigated spatial orientation in a virtual navigation task. Subjects had to adjust a homing vector indicating their end position relative to the origin of the path. It was demonstrated that sparse visual flow was sufficient for accurate path integration. Moreover, subjects were found to prefer a distinct egocentric or…

  16. An experimental study of pathologist's navigation patterns in virtual microscopy.

    PubMed

    Roa-Peña, Lucia; Gómez, Francisco; Romero, Eduardo

    2010-01-01

    In virtual microscopy, a sequential process of captures of microscopical fields, allows to construct a virtual slide which is visualized using a specialized software, called the virtual microscopy viewer. This tool allows useful exploration of images, composed of thousands of microscopical fields of view at different levels of magnification, emulating an actual microscopical examination. The aim of this study was to establish the main pathologist's navigation patterns when exploring virtual microscopy slides, using a graphical user interface, adapted to the pathologist's workflow. Four pathologists with a similar level of experience, graduated from the same pathology program, navigated six virtual slides. Different issues were evaluated, namely, the percentage of common visited image regions, the time spent at each and its coincidence level, that is to say, the region of interest location. In addition, navigation patterns were also assessed, i.e., mouse movement velocities and linearity of the diagnostic paths. Results suggest that regions of interest are determined by a complex combination of the visited area, the time spent at each visit and the coincidence level among pathologists. Additionally, linear trajectories and particular velocity patterns were found for the registered diagnostic paths. PMID:21087502

  17. An experimental study of pathologist's navigation patterns in virtual microscopy

    PubMed Central

    2010-01-01

    In virtual microscopy, a sequential process of captures of microscopical fields, allows to construct a virtual slide which is visualized using a specialized software, called the virtual microscopy viewer. This tool allows useful exploration of images, composed of thousands of microscopical fields of view at different levels of magnification, emulating an actual microscopical examination. The aim of this study was to establish the main pathologist's navigation patterns when exploring virtual microscopy slides, using a graphical user interface, adapted to the pathologist's workflow. Four pathologists with a similar level of experience, graduated from the same pathology program, navigated six virtual slides. Different issues were evaluated, namely, the percentage of common visited image regions, the time spent at each and its coincidence level, that is to say, the region of interest location. In addition, navigation patterns were also assessed, i.e., mouse movement velocities and linearity of the diagnostic paths. Results suggest that regions of interest are determined by a complex combination of the visited area, the time spent at each visit and the coincidence level among pathologists. Additionally, linear trajectories and particular velocity patterns were found for the registered diagnostic paths. PMID:21087502

  18. Eye tracking, strategies, and sex differences in virtual navigation.

    PubMed

    Andersen, Nicolas E; Dahmani, Louisa; Konishi, Kyoko; Bohbot, Véronique D

    2012-01-01

    Reports of sex differences in wayfinding have typically used paradigms sensitive to the female advantage (navigation by landmarks) or sensitive to the male advantage (navigation by cardinal directions, Euclidian coordinates, environmental geometry, and absolute distances). The current virtual navigation paradigm allowed both men and women an equal advantage. We studied sex differences by systematically varying the number of landmarks. Eye tracking was used to quantify sex differences in landmark utilisation as participants solved an eight-arm radial maze task within different virtual environments. To solve the task, participants were required to remember the locations of target objects within environments containing 0, 2, 4, 6, or 8 landmarks. We found that, as the number of landmarks available in the environment increases, the proportion of time men and women spend looking at landmarks and the number of landmarks they use to find their way increases. Eye tracking confirmed that women rely more on landmarks to navigate, although landmark fixations were also associated with an increase in task completion time. Sex differences in navigational behaviour occurred only in environments devoid of landmarks and disappeared in environments containing multiple landmarks. Moreover, women showed sustained landmark-oriented gaze, while men's decreased over time. Finally, we found that men and women use spatial and response strategies to the same extent. Together, these results shed new light on the discrepancy in landmark utilisation between men and women and help explain the differences in navigational behaviour previously reported. PMID:22001012

  19. Interactive navigation and bronchial tube tracking in virtual bronchoscopy.

    PubMed

    Heng, P A; Fung, P F; Wong, T T; Siu, Y H; Sun, H

    1999-01-01

    An interactive virtual environment for simulation of bronchoscopy is developed. Medical doctor can safely plan their surgical bronchoscopy using the virtual environment without any invasive diagnosis which may risk the patient's health. The 3D pen input device of the system allows the doctor to navigate and visualize the bronchial tree of the patient naturally and interactively. To navigate the patient's bronchial tree, a vessel tracking process is required. While manual tracking is tedious and labor-intensive, fully automatic tracking may not be reliable. We propose a semi-automatic tracking technique called Intelligent Path Tracker which provides automation and enough user control during the vessel tracking. To support an interactive frame rate, we also introduce a new volume rendering acceleration technique, named as IsoRegion Leaping. The volume rendering is further accelerated by distributed rendering on a TCP/IP-based network of low-cost PCs. With these approaches, a 256 x 256 x 256 volume data of human lung, can be navigated and visualized at a frame rate of over 10 Hz in our virtual bronchoscopy system. PMID:10538342

  20. Aging and Sensory Substitution in a Virtual Navigation Task

    PubMed Central

    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. PMID:27007812

  1. 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. PMID:27007812

  2. 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

  3. 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

  4. 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

  5. Endoscopic bronchial occlusion with silicone spigots under virtual bronchoscopic navigation

    PubMed Central

    Sato, Shingo; Shiroyama, Takayuki; Nishida, Takuji; Nishihara, Takashi; Okamoto, Norio

    2016-01-01

    Abstract A 68‐year‐old woman with interstitial lung disease related to dermatomyositis and systemic scleroderma was admitted to our hospital with fever and dyspnoea. Although the fever was reduced after antibiotic therapy, a left pneumothorax suddenly occurred on day 27 after admission. A continuous air leak persisted despite chest drainage with three tubes and repeated pleurodesis. Chest computed tomography (CT) images showed a cavitary lesion with a pinhole in the left upper division, which was suspected to be the affected lesion with the air leak. Virtual bronchoscopic navigation images were constructed from CT data. Bronchial occlusion with Endobronchial Watanabe Spigots (EWSs) was performed on day 52. Two medium‐sized EWSs were inserted into the left B1 + 2a and B1 + 2b, and the air leak stopped immediately. No procedure‐related adverse events occurred. All three chest tubes were successfully removed by day 60. This case demonstrates that virtual bronchoscopic navigation can improve bronchial occlusion procedures using EWSs. PMID:27512560

  6. 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. PMID:27108050

  7. Correlates of virtual navigation performance in older adults.

    PubMed

    Korthauer, Laura E; Nowak, Nicole T; Moffat, Scott D; An, Yang; Rowland, Laura M; Barker, Peter B; Resnick, Susan M; Driscoll, Ira

    2016-03-01

    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 nonhuman spatial navigation task. The present study investigated longitudinal changes in place learning in 51 healthy, nondemented adults (age 30-83 years) who completed the vMWT and a neuropsychological battery at 2 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 magnetic resonance 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

  8. 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.

  9. 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. PMID:27587958

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

    PubMed Central

    Park, Ah Young

    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. PMID:27587958

  11. Assessment of spatial attention and neglect with a virtual wheelchair navigation task.

    PubMed

    Buxbaum, Laurel J; Palermo, Mary Ann; Mastrogiovanni, Dina; Read, Mary Schmidt; Rosenberg-Pitonyak, Ellen; Rizzo, Albert A; Coslett, H Branch

    2008-08-01

    A total of 9 participants with right-hemisphere stroke performed a new virtual reality (VR) wheelchair navigation test of lateralized spatial attention and neglect. The test consists of a virtual path along which participants navigate (or are navigated) as they name virtual objects encountered. There are 4 VR conditions, obtained by crossing the factors array complexity and driver. Participants performed the VR task, a real-life wheelchair navigation task, and a battery of attention and neglect tests. The VR test showed sensitivity to both array complexity and driver, exhibited strong correlations with the wheelchair navigation test, and detected lateralized attention deficits in mild patients. The VR task thus shows promise as a sensitive, efficient measure of real-life navigation. PMID:18608643

  12. 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

  13. 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. PMID:24027192

  14. 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.

  15. Brief report: total knee arthroplasty performed with patient-specific, pre-operative CT-guided navigation.

    PubMed

    Rubin, Lee E; Murgo, Kenneth T

    2013-03-01

    The clinical success and long-term outcomes of total knee arthroplasty (TKA) are dependent not only on the biomaterials within the prosthetic implant, but also on the surgeon's ability to correctly position the implants onto the bone. Intra-operative computer navigation and robotic surgery have emerged as options to increase the accuracy of implant placement and enhance the outcomes of TKA, with mixed clinical results to date. Pre-operative CT-guided, patient-specific navigation is a unique method for planning TKA surgery to achieving consistent implant positioning, especially for patients with retained surgical hardware or unusual bony anatomy. This technology has been used in Rhode Island in a limited series of patients to assess the utility of the technique and represents an interesting advance for both orthopaedic surgeons and their patients. PMID:23641437

  16. Virtual local target method for avoiding local minimum in potential field based robot navigation.

    PubMed

    Zou, Xi-Yong; Zhu, Jing

    2003-01-01

    A novel robot navigation algorithm with global path generation capability is presented. Local minimum is a most intractable but is an encountered frequently problem in potential field based robot navigation. Through appointing appropriately some virtual local targets on the journey, it can be solved effectively. The key concept employed in this algorithm are the rules that govern when and how to appoint these virtual local targets. When the robot finds itself in danger of local minimum, a virtual local target is appointed to replace the global goal temporarily according to the rules. After the virtual target is reached, the robot continues on its journey by heading towards the global goal. The algorithm prevents the robot from running into local minima anymore. Simulation results showed that it is very effective in complex obstacle environments. PMID:12765277

  17. 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…

  18. Virtual environment to evaluate multimodal feedback strategies for augmented navigation of the visually impaired.

    PubMed

    Hara, Masayuki; Shokur, Solaiman; Yamamoto, Akio; Higuchi, Toshiro; Gassert, Roger; Bleuler, Hannes

    2010-01-01

    This paper proposes a novel experimental environment to evaluate multimodal feedback strategies for augmented navigation of the visually impaired. The environment consists of virtual obstacles and walls, an optical tracking system and a simple device with audio and vibrotactile feedback that interacts with the virtual environment, and presents many advantages in terms of safety, flexibility, control over experimental parameters and cost. The subject can freely move in an empty room, while the position of head and arm are tracked in real time. A virtual environment (walls, obstacles) is randomly generated, and audio and vibrotactile feedback are given according to the distance from the subjects arm to the virtual walls/objects. We investigate the applicability of our environment using a simple, commercially available feedback device. Experiments with unimpaired subjects show that it is possible to use the setup to "blindly" navigate in an unpredictable virtual environment. This validates the environment as a test platform to investigate navigation and exploration strategies of the visually impaired, and to evaluate novel technologies for augmented navigation. PMID:21096984

  19. Partially segregated neural networks for spatial and contextual memory in virtual navigation.

    PubMed

    Rauchs, Géraldine; Orban, Pierre; Balteau, Evelyne; Schmidt, Christina; Degueldre, Christian; Luxen, André; Maquet, Pierre; Peigneux, Philippe

    2008-01-01

    Finding our way in a previously learned, ecologically valid environment concurrently involves spatial and contextual cognitive operations. The former process accesses a cognitive map representing the spatial interactions between all paths in the environment. The latter accesses stored associations between landmark objects and their milieu. Here, we aimed at dissociating their neural basis in the context of memory-based virtual navigation. To do so, subjects freely explored a virtual town for 1 h, then were scanned using fMRI while retrieving their way between two locations, under four navigation conditions designed to probe separately or jointly the spatial and contextual memory components. Besides prominent commonalities found in a large hippocampo-neocortical network classically involved in topographical navigation, results yield evidence for a partial dissociation between the brain areas supporting spatial and contextual components of memory-based navigation. Performance-related analyses indicate that hippocampal activity mostly supports the spatial component, whereas parahippocampal activity primarily supports the contextual component. Additionally, the recruitment of contextual memory during navigation was associated with higher frontal, posterior parietal and lateral temporal activity. These results provide evidence for a partial segregation of the neural substrates of two crucial memory components in human navigation, whose combined involvement eventually leads to efficient navigation behavior within a learned environment. PMID:18240326

  20. 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. PMID:22922991

  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. PMID:26040931

  2. Networked virtual reality for real-time 4D navigation of astrophysical turbulence data

    SciTech Connect

    Hudson, R.; Malagoli, A.

    1996-11-01

    This paper describes a prototype distributed virtual reality system for real-time spatial and temporal navigation of volumetric data generated by simulations of hydrodynamic turbulence on high-performance computers. This system makes use of a virtual environment connected to a scalably parallel computer via a scalably high-speed network. The data are either computed in real-time or precomputed on the parallel computer, then are transferred to the virtual environment where fast volume visualization is accomplished by using sophisticated three-dimensional texture-mapping hardware.

  3. Three-Dimensional Ultrasound-Based Navigation Combined with Preoperative CT During Abdominal Interventions: A Feasibility Study

    SciTech Connect

    Kaspersen, J.H. Sjolie, E.; Wesche, J.; Asland, J.; Lundbom, J.; Odegard, A.; Lindseth, F.; Nagelhus Hernes, T.A.

    2003-08-15

    Purpose: Three-dimensional (3D)intraoperative ultrasound may be easier to interpret when used in combination with less noisy preoperative image data such as CT. The purpose of this study was to evaluate the use of preoperative image data in a 3D ultrasound-based navigation system specially designed for minimally invasive abdominal surgery. A prototype system has been tested in patients with aortic aneurysms undergoing clinical assessment before and after abdominal aortic stent-graft implantation. Methods: All patients were first imaged by spiral CT followed by 3D ultrasound scanning. The CT volume was registered to the patient using fiducial markers. This enabled us to compare corresponding slices from 3D ultrasound and CT volumes. The accuracy of the patient registration was evaluated both using the external fiducial markers (artificial landmarks glued on the patient's skin) and using intraoperative 3D ultrasound as a measure of the true positioning of anatomic landmarks inside the body. Results: The mean registration accuracy on the surface was found to be 7.1 mm, but increased to 13.0 mm for specific landmarks inside the body. CT and ultrasound gave supplementary information of surrounding structures and position of the patient's anatomy. Fine-tuning the initial patient registration of the CT data with a multimodal CT to intraoperative 3D ultrasound registration (e.g., mutual information), as well as ensuring no movements between this registration and image guidance, may improve the registration accuracy. Conclusion: Preoperative CT in combination with 3D ultrasound might be helpful for guiding minimal invasive abdominal interventions.

  4. 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). PMID:26334037

  5. Virtual preoperative measurement and surgical manipulation of sagittal spinal alignment using a novel research and educational software program.

    PubMed

    Pettigrew, David B; Morgan, Chad J; Anderson, R Brian; Wilsey, Philip A; Kuntz, Charles

    2010-03-01

    Understanding regional as well as global spinal alignment is increasingly recognized as important for the spine surgeon. A novel software program for virtual preoperative measurement and surgical manipulation of sagittal spinal alignment was developed to provide a research and educational tool for spine surgeons. This first-generation software program provides tools to measure sagittal spinal alignment from the occiput to the pelvis, and to allow for virtual surgical manipulation of sagittal spinal alignment. The software was developed in conjunction with Clifton Labs, Inc. Photographs and radiographs were imported into the software program, and a 2D virtual spine was constructed from the images. The software then measured regional and global sagittal spinal alignment from the virtual spine construct, showing the user how to perform the measurements. After measuring alignment, the program allowed for virtual surgical manipulation, simulating surgical procedures such as interbody fusion, facet osteotomy, pedicle subtraction osteotomy, and reduction of spondylolisthesis, as well as allowing for rotation of the pelvis on the hip axis. Following virtual manipulation, the program remeasured regional and global sagittal spinal alignment. Computer software can be used to measure and manipulate sagittal spinal alignment virtually, providing a new research and educational tool. In the future, more comprehensive programs may allow for measurement and interaction in the coronal, axial, and sagittal planes. PMID:20192663

  6. Virtual environment navigation tasks and the assessment of cognitive deficits in individuals with brain injury.

    PubMed

    Livingstone, Sharon A; Skelton, Ronald W

    2007-12-11

    Navigation in real environments is often impaired by traumatic brain injury (TBI). These deficits in wayfinding appear to be due to disruption of cognitive processes underlying navigation and may in turn be due to damage to the hippocampus and frontal lobes. These wayfinding problems after TBI were investigated using a virtual simulation of a Morris Water Maze (MWM), a standard test of hippocampal function in laboratory animals. The virtual environment consisted of a large virtual arena in a very large virtual room whose walls provided views of a naturalistic landscape. Eleven community-dwelling TBI survivors and 12 comparison participants, matched for gender, age and education were tested to see if they could find a location in the arena marked by one of the following: (a) a visible platform, (b) a single proximal object, (c) a single proximal object among seven other distracter objects, or (d) distal features inside and outside the room. The proximal objects allowed participants to use egocentric (body-centered) navigational strategies that rely on relatively simple stimulus-response associations. The absence of proximal cues forced the participants to rely on distal features of the environment (room walls, landscape elements) and tested their ability to use allocentric (world-based) navigational strategies requiring cognitive mapping. Results indicated that the navigation of TBI survivors was not impaired when the proximal cues were present but was impaired when proximal cues were absent. These results provide more evidence that the navigational deficit after TBI is due to an inability to form, remember or use cognitive maps. PMID:17727970

  7. 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. PMID:27174311

  8. 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. PMID:26756717

  9. An adaptable navigation strategy for Virtual Microscopy from mobile platforms.

    PubMed

    Corredor, Germán; Romero, Eduardo; Iregui, Marcela

    2015-04-01

    Real integration of Virtual Microscopy with the pathologist service workflow requires the design of adaptable strategies for any hospital service to interact with a set of Whole Slide Images. Nowadays, mobile devices have the actual potential of supporting an online pervasive network of specialists working together. However, such devices are still very limited. This article introduces a novel highly adaptable strategy for streaming and visualizing WSI from mobile devices. The presented approach effectively exploits and extends the granularity of the JPEG2000 standard and integrates it with different strategies to achieve a lossless, loosely-coupled, decoder and platform independent implementation, adaptable to any interaction model. The performance was evaluated by two expert pathologists interacting with a set of 20 virtual slides. The method efficiently uses the available device resources: the memory usage did not exceed a 7% of the device capacity while the decoding times were smaller than the 200 ms per Region of Interest, i.e., a window of 256×256 pixels. This model is easily adaptable to other medical imaging scenarios. PMID:25684128

  10. 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. PMID:19469662

  11. 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

  12. Path Complexity in Virtual Water Maze Navigation: Differential Associations with Age, Sex, and Regional Brain Volume.

    PubMed

    Daugherty, Ana M; Yuan, Peng; Dahle, Cheryl L; Bender, Andrew R; Yang, Yiqin; Raz, Naftali

    2015-09-01

    Studies of human navigation in virtual maze environments have consistently linked advanced age with greater distance traveled between the start and the goal and longer duration of the search. Observations of search path geometry suggest that routes taken by older adults may be unnecessarily complex and that excessive path complexity may be an indicator of cognitive difficulties experienced by older navigators. In a sample of healthy adults, we quantify search path complexity in a virtual Morris water maze with a novel method based on fractal dimensionality. In a two-level hierarchical linear model, we estimated improvement in navigation performance across trials by a decline in route length, shortening of search time, and reduction in fractal dimensionality of the path. While replicating commonly reported age and sex differences in time and distance indices, a reduction in fractal dimension of the path accounted for improvement across trials, independent of age or sex. The volumes of brain regions associated with the establishment of cognitive maps (parahippocampal gyrus and hippocampus) were related to path dimensionality, but not to the total distance and time. Thus, fractal dimensionality of a navigational path may present a useful complementary method of quantifying performance in navigation. PMID:24860019

  13. Sex differences in human EEG theta oscillations during spatial navigation in virtual reality.

    PubMed

    Kober, Silvia Erika; Neuper, Christa

    2011-03-01

    The present study examines theta oscillations (electroencephalographic (EEG) activity with a frequency of 4-8 Hz) in male and female young adults during spatial navigation in virtual environments. Twenty-seven participants (13 males and 14 females) performed a spatial navigation task in a virtual maze where they had to find the shortest ways between landmarks. Absolute theta band power and event-related desynchronisation/synchronisation (ERD/ERS) in the theta frequency band was used to analyze the EEG data. Processing of spatial cues or landmarks induced cortical theta activity compared to a baseline condition, confirming the hypothesis that theta oscillations reflect sensorimotor integration. The sensorimotor integration hypothesis proposes that theta oscillations coordinate sensory information with a motor plan to direct wayfinding behaviour to known goal locations. No sex differences were found in spatial performance. However, female participants showed a stronger increase in theta oscillations during processing of landmarks as navigational aids compared to a baseline condition than men. Additionally, a higher theta power was associated with an increased navigation performance in women, whereas an increase in theta power was associated with a decreased navigation performance in men. These results might indicate a stronger sensorimotor integration in females than in males. Possible explanations for the emerged sex differences in cortical theta activity are discussed. PMID:21146566

  14. 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.

  15. 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.

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

    PubMed Central

    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. PMID:25161366

  17. 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.

  18. Investigating virtual reality navigation in amnestic mild cognitive impairment using fMRI.

    PubMed

    Migo, E M; O'Daly, O; Mitterschiffthaler, M; Antonova, E; Dawson, G R; Dourish, C T; Craig, K J; Simmons, A; Wilcock, G K; McCulloch, E; Jackson, S H D; Kopelman, M D; Williams, S C R; Morris, R G

    2016-01-01

    Spatial navigation requires a well-established network of brain regions, including the hippocampus, caudate nucleus, and retrosplenial cortex. Amnestic Mild Cognitive Impairment (aMCI) is a condition with predominantly memory impairment, conferring a high predictive risk factor for dementia. aMCI is associated with hippocampal atrophy and subtle deficits in spatial navigation. We present the first use of a functional Magnetic Resonance Imaging (fMRI) navigation task in aMCI, using a virtual reality analog of the Radial Arm Maze. Compared with controls, aMCI patients showed reduced activity in the hippocampus bilaterally, retrosplenial cortex, and left dorsolateral prefrontal cortex. Reduced activation in key areas for successful navigation, as well as additional regions, was found alongside relatively normal task performance. Results also revealed increased activity in the right dorsolateral prefrontal cortex in aMCI patients, which may reflect compensation for reduced activations elsewhere. These data support suggestions that fMRI spatial navigation tasks may be useful for staging of progression in MCI. PMID:26234803

  19. Gender differences in EEG coherent activity before and after training navigation skills in virtual environments.

    PubMed

    Ramos-Loyo, J; Sanchez-Loyo, L M

    2011-01-01

    Gender differences in electroencephalographic activity (EEG) changes during navigation task performance after training were assessed in young adults. Female and male subjects were matched on initial navigation performance. EEG recordings were obtained while subjects navigated in an immersive virtual environment without visual cues, before and after a navigational skills training (9 sessions). In spite of task performance was similar in both groups, females showed higher theta band coherent activity between frontal and parietal and frontal and central regions than males before training. Correlation in theta band between fronto-central, fronto-parietal, and centro-parietal regions was enhanced in the left hemisphere for females but in the right hemisphere for males after training. Females also demonstrated a decreased in correlation in theta band over the right hemisphere between centro-parietal regions, whereas males demonstrated a similar effect over the left hemisphere. Navigation training seems to promote fronto-central-parietal synchronization in both genders but in different hemisphere. These results are interpreted as reflecting verbal-analytical working memory functions in females and global-spatial working memory mode in males. PMID:22332431

  20. Design of fault diagnosis system for inertial navigation system based on virtual technology

    NASA Astrophysics Data System (ADS)

    Hu, Baiqing; Wang, Boxiong; Li, An; Zhang, Mingzhao; Qin, Fangjun; Pan, Hua

    2006-11-01

    With regard to the complex structure of the inertial navigation system and the low rate of fault detection with BITE (built-in test equipment), a fault diagnosis system for INS based on virtual technologies (virtual instrument and virtual equipment) is proposed in this paper. The hardware of the system is a PXI computer with highly stable performance and strong extensibility. In addition to the basic functions of digital multimeter, oscilloscope and cymometer, it can also measure the attitude of the ship in real-time, connect and control the measurement instruments with digital interface. The software is designed with the languages of Measurement Studio for VB, JAVA, and CULT3D. Using the extensively applied fault-tree reasoning and fault cases makes fault diagnosis. To suit the system to the diagnosis for various navigation electronic equipments, the modular design concept is adopted for the software programming. Knowledge of the expert system is digitally processed and the parameters of the system's interface and the expert diagnosis knowledge are stored in the database. The application shows that system is stable in operation, easy to use, quick and accurate in fault diagnosis.

  1. Real-time path planning in dynamic virtual environments using multiagent navigation graphs.

    PubMed

    Sud, Avneesh; Andersen, Erik; Curtis, Sean; Lin, Ming C; Manocha, Dinesh

    2008-01-01

    We present a novel approach for efficient path planning and navigation of multiple virtual agents in complex dynamic scenes. We introduce a new data structure, Multi-agent Navigation Graph (MaNG), which is constructed using first- and second-order Voronoi diagrams. The MaNG is used to perform route planning and proximity computations for each agent in real time. Moreover, we use the path information and proximity relationships for local dynamics computation of each agent by extending a social force model [Helbing05]. We compute the MaNG using graphics hardware and present culling techniques to accelerate the computation. We also address undersampling issues and present techniques to improve the accuracy of our algorithm. Our algorithm is used for real-time multi-agent planning in pursuit-evasion, terrain exploration and crowd simulation scenarios consisting of hundreds of moving agents, each with a distinct goal. PMID:18369262

  2. 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

  3. Virtual Reality in Assessing the Supportive Environment that Promotes Navigability of Persons with Alzheimer's disease.

    PubMed

    Che Me, Rosalam; Gramegna, Silvia Maria; Biamonti, Alessandro

    2015-01-01

    Spatial cognition and representation in persons with Alzheimer's disease (AD) is usually impaired, alongside with cognitive impairment. It is important to provide the supportive environments that support their ability of wayfinding to maintain the daily activities and autonomy. The aim of this paper is to emphasize how Virtual Reality (VR) system is used to assess the improved environmental design that promotes spatial navigability in persons with AD. The importance of supportive environments and significant studies that used VR in the wayfinding interventions is presented. The paper proposed a strategy to use Virtual Environment (VE), replacing the traditional assessment in the design development phase of supportive environment. Results from the preliminary valuation using interview show positive feedback by the medical experts, since immersive VE allows the experience being in actual environment. Also, the proposed strategy may reduce the costly and time-consuming design process. An evidence-based validation involving persons with AD will be conducted to investigate the effectiveness of this assessment strategy by comparing the individuals' navigational performances in both real and VE. PMID:26294591

  4. 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. PMID:23367004

  5. 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. PMID:11592665

  6. 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.

  7. 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

  8. Preoperative Planning of Virtual Osteotomies Followed by Fabrication of Patient Specific Reconstruction Plate for Secondary Correction and Fixation of Displaced Bilateral Mandibular Body Fracture.

    PubMed

    Thor, Andreas

    2016-06-01

    This paper describes the course of treatment of a severely diplaced bilateral mandibular body fracture, where the first osteosynthesis failed. The subject developed an open bite due to a posterior rotation of the distal part of the mandible and anterior rotation of the proximal parts of the mandible. This situation was evaluated with CBCT and the facial skeleton was segmented using computer software. Correct occlusion was virtually established by bilateral virtual osteotomies in the fracture areas of the mandible. After segmentation, the mandible was virtually rotated back into position and the open bite was closed. A patient specific mandibular reconstruction plate was outlined and fabricated from the new virtual situation and the plate was thereafter installed utilizing the preoperative plan. Osteotomy- and drill-guides was used and thus simplified the surgery resulting in uneventful healing. Virtual planning and patient specific implants and guides were valuable in this case of secondary reconstructive trauma surgery. PMID:27162581

  9. Rightward-biased hemodynamic response of the parahippocampal system during virtual navigation.

    PubMed

    Baker, Travis E; Umemoto, Akina; Krawitz, Adam; Holroyd, Clay B

    2015-01-01

    Phase reset of parahippocampal electrophysiological oscillations in the theta frequency range is said to contribute to item encoding and retrieval during spatial navigation. Although well-studied in non-human animals, this mechanism is poorly understood in humans. Previously we found that feedback stimuli presented in a virtual maze environment elicited a burst of theta power over right-posterior areas of the human scalp, and that the power and phase angle of these oscillations were greater following right turns compared to left turns in the maze. Here we investigated the source of this effect with functional magnetic resonance imaging. Consistent with our predictions, we found that 1) feedback encountered in the maze task activated right parahippocampal cortex (PHC), 2) right PHC was more activated by rewards following right turns compared to left turns in the maze, and 3) the rightward-biased activation was more pronounced in individuals who displayed good spatial abilities. These findings support our previous electrophysiological findings and highlight, in humans, a role for PHC theta oscillations in encoding salient information for the purpose of spatial navigation. PMID:25761577

  10. 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

  11. 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. PMID:27065838

  12. A technique for simulating visual field losses in virtual environments to study human navigation.

    PubMed

    Fortenbaugh, Francesca C; Hicks, John C; Hao, Lei; Turano, Kathleen A

    2007-08-01

    The following paper describes a new technique for simulating peripheral field losses in virtual environments to study the roles of the central and peripheral visual fields during navigation. Based on Geisler and Perry's (2002) gaze-contingent multiresolution display concept, the technique extends their methodology to work with three-dimensional images that are both transformed and rendered in real time by a computer graphics system. In order to assess the usefulness of this method for studying visual field losses, an experiment was run in which seven participants were required to walk to a target tree in a virtual forest as quickly and efficiently as possible while artificial head and eye-based delays were systematically introduced. Bilinear fits were applied to the mean trial times in order to assess at what delay lengths breaks in performance could be observed. Results suggest that breaks occur beyond the current delays inherent in the system. Increases in trial times across all delays tested were also observed when simulated peripheral field losses were applied compared to full FOV conditions. Possible applications and limitations of the system are discussed. The source code needed to program visual field losses can be found at lions.med.jhu.edu/archive/turanolab/Simulated_Visual_Field_Loss_Code.html. PMID:17958167

  13. 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

  14. 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

    2013-01-01

    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. PMID:23568182

  15. 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…

  16. Improved Redirection with Distractors: A Large-Scale-Real-Walking Locomotion Interface and its Effect on Navigation in Virtual Environments

    PubMed Central

    Peck, Tabitha C.; Fuchs, Henry; Whitton, Mary C.

    2014-01-01

    Users in virtual environments often find navigation more difficult than in the real world. Our new locomotion interface, Improved Redirection with Distractors (IRD), enables users to walk in larger-than-tracked space VEs without predefined waypoints. We compared IRD to the current best interface, really walking, by conducting a user study measuring navigational ability. Our results show that IRD users can really walk through VEs that are larger than the tracked space and can point to targets and complete maps of VEs no worse than when really walking. PMID:25429369

  17. 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. PMID:12916588

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

    PubMed Central

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

    2016-01-01

    PURPOSE 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. METHODS 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. RESULTS 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). CONCLUSION PTL procedures can be performed safely and accurately under the guidance of a CBCT virtual navigation system. PMID:27015318

  19. 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

  20. 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

  1. 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")…

  2. A PC-based high-quality and interactive virtual endoscopy navigating system using 3D texture based volume rendering.

    PubMed

    Hwang, Jin-Woo; Lee, Jong-Min; Kim, In-Young; Song, In-Ho; Lee, Yong-Hee; Kim, SunI

    2003-05-01

    As an alternative method to optical endoscopy, visual quality and interactivity are crucial for virtual endoscopy. One solution is to use the 3D texture map based volume rendering method that offers high rendering speed without reducing visual quality. However, it is difficult to apply the method to virtual endoscopy. First, 3D texture mapping requires a high-end graphic workstation. Second, texture memory limits reduce the frame-rate. Third, lack of shading reduces visual quality significantly. As 3D texture mapping has become available on personal computers recently, we developed an interactive navigation system using 3D texture mapping on a personal computer. We divided the volume data into small cubes and tested whether the cubes had meaningful data. Only the cubes that passed the test were loaded into the texture memory and rendered. With the amount of data to be rendered minimized, rendering speed increased remarkably. We also improved visual quality by implementing full Phong shading based on the iso-surface shading method without sacrificing interactivity. With the developed navigation system, 256 x 256 x 256 sized brain MRA data was interactively explored with good image quality. PMID:12725966

  3. 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

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

    PubMed

    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

  5. 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.

  6. 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…

  7. 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…

  8. 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…

  9. 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.

  10. Walking in a cube: novel metaphors for safely navigating large virtual environments in restricted real workspaces.

    PubMed

    Cirio, Gabriel; Vangorp, Peter; Chapoulie, Emmanuelle; Marchal, Maud; Lécuyer, Anatole; Drettakis, George

    2012-04-01

    Immersive spaces such as 4-sided displays with stereo viewing and high-quality tracking provide a very engaging and realistic virtual experience. However, walking is inherently limited by the restricted physical space, both due to the screens (limited translation) and the missing back screen (limited rotation). In this paper, we propose three novel locomotion techniques that have three concurrent goals: keep the user safe from reaching the translational and rotational boundaries; increase the amount of real walking and finally, provide a more enjoyable and ecological interaction paradigm compared to traditional controller-based approaches. We notably introduce the "Virtual Companion", which uses a small bird to guide the user through VEs larger than the physical space. We evaluate the three new techniques through a user study with travel-to-target and path following tasks. The study provides insight into the relative strengths of each new technique for the three aforementioned goals. Specifically, if speed and accuracy are paramount, traditional controller interfaces augmented with our novel warning techniques may be more appropriate; if physical walking is more important, two of our paradigms (extended Magic Barrier Tape and Constrained Wand) should be preferred; last, fun and ecological criteria would favor the Virtual Companion. PMID:22402681

  11. 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. PMID:27213559

  12. 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. PMID:21736927

  13. Preoperative planning for DIEP breast reconstruction: early experience of the use of computerised tomography angiography with VoNavix 3D software for perforator navigation.

    PubMed

    Pacifico, M D; See, M S; Cavale, N; Collyer, J; Francis, I; Jones, M E; Hazari, A; Boorman, J G; Smith, R W

    2009-11-01

    The deep inferior epigastric perforator (DIEP) flap is normally the first choice in breast reconstruction; however, due to the considerable vascular anatomical variation and the learning curve for the procedure, muscle-sparing transverse rectus abdominis musculocutaneous (TRAM) flaps are still frequently performed to reduce the rate of complications. Accurate preoperative investigation of the perforators would allow better operative preparation and possibly shorten the learning curve. In an effort to increase accuracy of preoperative planning and to aid preoperative decision-making in free abdominal flap breast reconstruction, we have acquired the use of VoNavix, software that creates three dimensional images from computerised tomography angiography (CTA) data. The use of the VoNavix software for analysis of CTA provides superior imaging that can be viewed in theatre. It, together with CTA, enables decisions to be made preoperatively, including: which side to raise the flap; whether to aim for a medial or lateral row perforator; whether to take a segment of muscle and whether to expect an easy or difficult dissection. We have now performed over 60 free abdominal flap breast reconstructions aided with CTA, and 10 of these cases also used VoNavix technology. This paper presents our initial experience with the use of this software, illustrated with three patient examples. The advantages and disadvantages are discussed. PMID:18708309

  14. Stop and look! Evidence for a bias towards virtual navigation response strategies in children with ADHD symptoms.

    PubMed

    Robaey, Philippe; McKenzie, Sam; Schachar, Russel; Boivin, Michel; Bohbot, Veronique D

    2016-02-01

    Studies in children show that the development of spatial competence emerges between seven and eight years of age. Multiple memory systems (hippocampus-dependent spatial and caudate nucleus-dependent response learning) are involved in parallel processing of information during navigation. As a hippocampus-dependent spatial strategy also relies on frontoparietal executive control and working memory networks that are impaired in ADHD, we predicted that children will be more likely to adopt a response strategy as they exhibit ADHD symptoms. We tested 285 healthy children on a virtual radial-arm maze paradigm in order to test this hypothesis. We found that children displaying at least one ADHD symptom were more likely to have a perfect performance on a probe trial, which suggests that they did not rely on environmental landmarks. Children with ADHD symptoms may primarily rely on caudate nucleus-dependent response learning strategies at the expense of hippocampus-dependent spatial strategies. Repetition and reward based learning strategies, which are hallmarks of response learning, may be most effective in children exhibiting ADHD symptoms. PMID:26310386

  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. 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

  17. 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.

  18. 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.

  19. A Spatial Cognitive Map and a Human-Like Memory Model Dedicated to Pedestrian Navigation in Virtual Urban Environments

    NASA Astrophysics Data System (ADS)

    Thomas, Romain; Donikian, Stéphane

    Many articles dealing with agent navigation in an urban environment involve the use of various heuristics. Among them, one is prevalent: the search of the shortest path between two points. This strategy impairs the realism of the resulting behaviour. Indeed, psychological studies state that such a navigation behaviour is conditioned by the knowledge the subject has of its environment. Furthermore, the path a city dweller can follow may be influenced by many factors like his daily habits, or the path simplicity in term of minimum of direction changes. It appeared interesting to us to investigate how to mimic human navigation behavior with an autonomous agent. The solution we propose relies on an architecture based on a generic model of informed environment, a spatial cognitive map model merged with a human-like memory model, representing the agent's temporal knowledge of the environment, it gained along its experiences of navigation.

  20. 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

  1. Advanced virtual endoscopic pituitary surgery.

    PubMed

    Neubauer, André; Wolfsberger, Stefan; Forster, Marie-Thérèse; Mroz, Lukas; Wegenkittl, Rainer; Bühler, Katja

    2005-01-01

    Endoscopy has recently been introduced to endonasal transsphenoidal pituitary surgery as a minimally invasive procedure for the removal of various kinds of pituitary tumors. To reduce morbidity and mortality with this new technique, the surgeon must be well-trained and well-prepared. Virtual endoscopy can be beneficial as a tool for training, preoperative planning, and intraoperative support. This paper introduces STEPS, a virtual endoscopy system designed to aid surgeons in getting acquainted with the endoscopic view of the anatomy, the handling of instruments, the transsphenoidal approach, and challenges associated with the procedure. STEPS also assists experienced surgeons in planning a real endoscopic intervention by getting familiar with the individual patient anatomy, identifying landmarks, planning the approach, and deciding upon the ideal target position of the actual surgical activity. The application provides interactive visualization, navigation, and perception aids and the possibility of simulating the procedure, including haptic feedback and simulation of surgical instruments. PMID:16144247

  2. An interactive physics-based unmanned ground vehicle simulator leveraging open source gaming technology: progress in the development and application of the virtual autonomous navigation environment (VANE) desktop

    NASA Astrophysics Data System (ADS)

    Rohde, Mitchell M.; Crawford, Justin; Toschlog, Matthew; Iagnemma, Karl D.; Kewlani, Guarav; Cummins, Christopher L.; Jones, Randolph A.; Horner, David A.

    2009-05-01

    It is widely recognized that simulation is pivotal to vehicle development, whether manned or unmanned. There are few dedicated choices, however, for those wishing to perform realistic, end-to-end simulations of unmanned ground vehicles (UGVs). The Virtual Autonomous Navigation Environment (VANE), under development by US Army Engineer Research and Development Center (ERDC), provides such capabilities but utilizes a High Performance Computing (HPC) Computational Testbed (CTB) and is not intended for on-line, real-time performance. A product of the VANE HPC research is a real-time desktop simulation application under development by the authors that provides a portal into the HPC environment as well as interaction with wider-scope semi-automated force simulations (e.g. OneSAF). This VANE desktop application, dubbed the Autonomous Navigation Virtual Environment Laboratory (ANVEL), enables analysis and testing of autonomous vehicle dynamics and terrain/obstacle interaction in real-time with the capability to interact within the HPC constructive geo-environmental CTB for high fidelity sensor evaluations. ANVEL leverages rigorous physics-based vehicle and vehicle-terrain interaction models in conjunction with high-quality, multimedia visualization techniques to form an intuitive, accurate engineering tool. The system provides an adaptable and customizable simulation platform that allows developers a controlled, repeatable testbed for advanced simulations. ANVEL leverages several key technologies not common to traditional engineering simulators, including techniques from the commercial video-game industry. These enable ANVEL to run on inexpensive commercial, off-the-shelf (COTS) hardware. In this paper, the authors describe key aspects of ANVEL and its development, as well as several initial applications of the system.

  3. 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.

  4. 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

  5. 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.

  6. 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. PMID:24464989

  7. Improved accuracy of 3D-printed navigational template during complicated tibial plateau fracture surgery.

    PubMed

    Huang, Huajun; Hsieh, Ming-Fa; Zhang, Guodong; Ouyang, Hanbin; Zeng, Canjun; Yan, Bin; Xu, Jing; Yang, Yang; Wu, Zhanglin; Huang, Wenhua

    2015-03-01

    This study was aimed to improve the surgical accuracy of plating and screwing for complicated tibial plateau fracture assisted by 3D implants library and 3D-printed navigational template. Clinical cases were performed whereby complicated tibial plateau fractures were imaged using computed tomography and reconstructed into 3D fracture prototypes. The preoperative planning of anatomic matching plate with appropriate screw trajectories was performed with the help of the library of 3D models of implants. According to the optimal planning, patient-specific navigational templates produced by 3D printer were used to accurately guide the real surgical implantation. The fixation outcomes in term of the deviations of screw placement between preoperative and postoperative screw trajectories were measured and compared, including the screw lengths, entry point locations and screw directions. With virtual preoperative planning, we have achieved optimal and accurate fixation outcomes in the real clinical surgeries. The deviations of screw length was 1.57 ± 5.77 mm, P > 0.05. The displacements of the entry points in the x-, y-, and z-axis were 0.23 ± 0.62, 0.83 ± 1.91, and 0.46 ± 0.67 mm, respectively, P > 0.05. The deviations of projection angle in the coronal (x-y) and transverse (x-z) planes were 6.34 ± 3.42° and 4.68 ± 3.94°, respectively, P > 0.05. There was no significant difference in the deviations of screw length, entry point and projection angle between the ideal and real screw trajectories. The ideal and accurate preoperative planning of plating and screwing can be achieved in the real surgery assisted by the 3D models library of implants and the patient-specific navigational template. This technology improves the accuracy and efficiency of personalized internal fixation surgery and we have proved this in our clinical applications. PMID:25663390

  8. Three-dimensional simulation, surgical navigation and thoracoscopic lung resection

    PubMed Central

    Kanzaki, Masato; Kikkawa, Takuma; Sakamoto, Kei; Maeda, Hideyuki; Wachi, Naoko; Komine, Hiroshi; Oyama, Kunihiro; Murasugi, Masahide; Onuki, Takamasa

    2013-01-01

    This report describes a 3-dimensional (3-D) video-assisted thoracoscopic lung resection guided by a 3-D video navigation system having a patient-specific 3-D reconstructed pulmonary model obtained by preoperative simulation. A 78-year-old man was found to have a small solitary pulmonary nodule in the left upper lobe in chest computed tomography. By a virtual 3-D pulmonary model the tumor was found to be involved in two subsegments (S1 + 2c and S3a). Complete video-assisted thoracoscopic surgery bi-subsegmentectomy was selected in simulation and was performed with lymph node dissection. A 3-D digital vision system was used for 3-D thoracoscopic performance. Wearing 3-D glasses, the patient's actual reconstructed 3-D model on 3-D liquid-crystal displays was observed, and the 3-D intraoperative field and the picture of 3-D reconstructed pulmonary model were compared. PMID:24964426

  9. Computer-aided navigation in secondary reconstruction of post-traumatic deformities of the zygoma.

    PubMed

    Watzinger, F; Wanschitz, F; Wagner, A; Enislidis, G; Millesi, W; Baumann, A; Ewers, R

    1997-08-01

    Augmented reality technology was used in 5 patients for secondary reconstruction of post-traumatic unilateral deformities of the zygomaticomaxillary complex. Three electromagnetic sensors interfaced to a computer-aided navigation system (ARTMA Biomedical Inc.) were utilized. The computer navigation procedure was planned by drawing graphic lines on the CT scan at the level of the zygomatic arch, representing the outer surface of the zygoma. The desired position of the displaced zygoma was planned by mirroring from the healthy side, using a virtual mid-sagittal plane. These virtual graphics were presented intraoperatively on a TV monitor and also on the surgeon's see-through head-mounted display. Correct reduction was assumed when the virtual line representing the position of the zygoma before the osteotomy reached the virtual line defined preoperatively as the desired position. The advantages of the technique presented are that a complete exposure of the zygomatic bone is no longer necessary, and coronal and subciliary incisions may be avoided unless enophthalmos correction has to be carried out, which was in fact necessary in 2 patients. The results of zygomatic reconstruction have been satisfactory in all 5 patients. PMID:9268898

  10. 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,…

  11. 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

  12. Avoiding Unnecessary Preoperative Testing.

    PubMed

    Rusk, Matthew H

    2016-09-01

    Given the low-risk nature of cataract surgery, no preoperative testing is indicated unless the patient needs it for another reason. Although electrocardiograms may have a role in preoperative testing in patients at high risk of cardiovascular disease, or if the procedure carries with it significant operative risks, they are often unnecessary. Urinalysis and coagulation studies not should be routine because they have not shown any value in predicting complications. Although these tests are not individually expensive, the aggregate cost is substantial. As good stewards of the medical system, physicians need to use these tests more judiciously. PMID:27542420

  13. Preoperative Laboratory Testing.

    PubMed

    Bock, Matthias; Fritsch, Gerhard; Hepner, David L

    2016-03-01

    Routine preoperative testing is not cost-effective, because it is unlikely to identify significant abnormalities. Abnormal findings from routine testing are more likely to be false positive, are costly to pursue, introduce a new risk, increase the patient's anxiety, and are inconvenient to the patient. Abnormal findings rarely alter the surgical or anesthetic plan, and there is usually no association between perioperative complications and abnormal laboratory results. Incidental findings and false positive results may lead to increased hospital visits and admissions. Preoperative testing needs to be done based on a targeted history and physical examination and the type of surgery. PMID:26927738

  14. 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

  15. 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.

  16. Interplanetary navigation

    NASA Technical Reports Server (NTRS)

    Stuart, J. R.

    1984-01-01

    The evolution of NASA's planetary navigation techniques is traced, and radiometric and optical data types are described. Doppler navigation; the Deep Space Network; differenced two-way range techniques; differential very long base interferometry; and optical navigation are treated. The Doppler system enables a spacecraft in cruise at high absolute declination to be located within a total angular uncertainty of 1/4 microrad. The two-station range measurement provides a 1 microrad backup at low declinations. Optical data locate the spacecraft relative to the target to an angular accuracy of 5 microrad. Earth-based radio navigation and its less accurate but target-relative counterpart, optical navigation, thus form complementary measurement sources, which provide a powerful sensory system to produce high-precision orbit estimates.

  17. [The preoperative anaesthetic visit].

    PubMed

    Harms, Christoph; Kindler, Christoph H

    2009-07-01

    Anaesthetists often visit their patients in exceptional situations characterised by preoperative anxiety or distress. Therefore, even brief contact with the patient can be considered intense and meaningful. The initial preoperative anaesthetic visit is the beginning of the relationship between patient and anaesthetist, and should help to explain the planned anaesthetic technique. Preoperative anaesthetic visits are intense and last for 20 minutes on average. They should assert a professional approach to the patient's emotions, particularly to preoperative anxiety, and a structured and clear collection of information including the past history of the patient. These visits should also provide information about the anaesthesia itself and instructions for the patient with respect to the perioperative period. Communication about the side effects and risks of anaesthetic techniques, and the discussion of potential alternatives are mandatory. Worldwide, courts of law increasingly require a documented discussion between the anaesthetist and patient based on risk-benefit evidence. Today, there is in general a shift away from decisions made solely by physicians, reflecting an increased respect for the autonomy of the patient towards a model of shared decision-making and informed choice. Ideally, the preoperative visit follows the four key habits of highly effective clinicians, i.e., to rapidly establish a rapport with the patient and provide an agenda for the visit, to explore the patient's perspectives and expectations, to demonstrate empathy, and to focus on the end of the visit with providing information and including the patient in the decision-making process. Visits are then concluded upon obtaining informed consent from the patient. PMID:19565444

  18. Synchronous navigation for CT colonography

    NASA Astrophysics Data System (ADS)

    Huang, Adam; Summers, Ronald M.; Roy, Dave

    2006-03-01

    We present a synchronous navigation module for CT colonography (CTC) reading. The need for such a system arises because most CTC protocols require a patient to be scanned in both supine and prone positions to increase sensitivity in detecting colonic polyps. However, existing clinical practices are limited to reading one scan at a time. Such limitation is due to the fact that building a reference system between scans for the highly flexible colon is a nontrivial task. The conventional centerline approach, generating only the longitudinal distance along the colon, falls short in providing the necessary orientation information to synchronize the virtual navigation cameras in both scanned positions. In this paper we describe a synchronous navigation system by using the teniae coli as anatomical references. Teniae coli are three parallel bands of longitudinal smooth muscle on the surface of the colon. They are morphologically distinguishable and form a piecewise triple helix structure from the appendix to the sigmoid colon. Because of these characteristics, they are ideal references to synchronize virtual cameras in both scanned positions. Our new navigation system consists of two side-by-side virtual colonoscopic view panels (for the supine and prone data sets respectively) and one single camera control unit (which controls both the supine and prone virtual cameras). The capability to examine the same colonic region simultaneously in both scanned images can raise an observer's confidence in polyp identification and potentially improve the performance of CT colonography.

  19. Preoperative biliary drainage.

    PubMed

    Saxena, Payal; Kumbhari, Vivek; Zein, Mohamad E L; Khashab, Mouen A

    2015-01-01

    The role of preoperative biliary drainage (PBD) in patients with distal or proximal biliary obstruction secondary to resectable tumors has been a matter for debate. A review of the literature using Medline, Embase and Cochrane databases was undertaken for studies evaluating routes of drainage (endoscopic or percutaneous) and stent types (plastic or metal) in patients with resectable disease. Preoperative biliary drainage is indicated for relief of symptomatic jaundice, cholangitis, patients undergoing neoadjuvant therapy or those patients where surgery may be delayed. Endoscopic methods are preferred over percutaneous methods because of lower complication rates. In patients with proximal biliary obstruction, PBD should be guided by imaging studies to aid in selective biliary cannulation for unilateral drainage in order to reduce the risk of cholangitis in undrained liver segments. PMID:25293587

  20. 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.

  1. 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.

  2. 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

  3. Which preoperative respiratory evaluation?

    PubMed

    Zraier, S; Haouache, H; Dhonneur, G

    2014-01-01

    The preoperative respiratory evaluation aims at predicting the occurrence of postoperative respiratory complications (PORC), such as: atelectasis, pulmonary infection (bronchitis and pneumonia), acute ventilatory distress, pleural effusion, prolonged mechanical ventilation, exacerbation of chronic respiratory disease and bronchospasm. The incidence of (PORC) all surgeries combined is 6.8%. Individual surgical and anesthetic factors are impacting on the occurrence of PORC. Simple scores, including anamnestic data, clinical examination and some biological parameters were validated to assess the risk of PORC depending on the type of surgery. Data from standard pulmonary function tests (PFT) is of little use to estimate the individual risk of PORC. Most of the time, PFT abnormal parameters only confirm the clinical assessment of the severity of the illness. PFT may however be useful to confirm an improvement in the clinical condition of the patient related to the preoperative preparation. Specialized EFR, including standardized testing efforts are sometimes required in the case of lung reduction surgery. These specialized explorations can predict lung function and post-interventional pulmonary oxygenation and ensure that these are viable. PMID:25168302

  4. Celestial Navigation

    ERIC Educational Resources Information Center

    Rosenkrantz, Kurt

    2005-01-01

    In the unit described in this article, students discover the main principles of navigation, build tools to observe celestial bodies, and apply their new skills to finding their position on Earth. Along the way students see how science, mathematics, technology, and history are intertwined.

  5. Virtual colonoscopy

    MedlinePlus

    Colonoscopy - virtual; CT colonography; Computed tomographic colonography; Colography - virtual ... Virtual colonoscopy is different from regular colonoscopy . Regular colonoscopy uses a long, lighted tool called a colonoscope that is ...

  6. 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.

  7. 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.

  8. 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.

  9. INL Autonomous Navigation System

    Energy Science and Technology Software Center (ESTSC)

    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.

  10. 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.

  11. An integrated system for planning, navigation and robotic assistance for skull base surgery

    PubMed Central

    Xia, Tian; Baird, Clint; Jallo, George; Hayes, Kathryn; Nakajima, Nobuyuki; Hata, Nobuhiko; Kazanzides, Peter

    2009-01-01

    Background We developed an image-guided robot system to provide mechanical assistance for skull base drilling, which is performed to gain access for some neurosurgical interventions, such as tumour resection. The motivation for introducing this robot was to improve safety by preventing the surgeon from accidentally damaging critical neurovascular structures during the drilling procedure. Methods We integrated a Stealthstation® navigation system, a NeuroMate® robotic arm with a six-degree-of-freedom force sensor, and the 3D Slicer visualization software to allow the robotic arm to be used in a navigated, cooperatively-controlled fashion by the surgeon. We employed virtual fixtures to constrain the motion of the robot-held cutting tool, so that it remained in the safe zone that was defined on a preoperative CT scan. Results We performed experiments on both foam skull and cadaver heads. The results for foam blocks cut using different registrations yielded an average placement error of 0.6 mm and an average dimensional error of 0.6 mm. We drilled the posterior porus acusticus in three cadaver heads and concluded that the robot-assisted procedure is clinically feasible and provides some ergonomic benefits, such as stabilizing the drill. We obtained postoperative CT scans of the cadaver heads to assess the accuracy and found that some bone outside the virtual fixture boundary was cut. The typical overcut was 1–2 mm, with a maximum overcut of about 3 mm. Conclusions The image-guided cooperatively-controlled robot system can improve the safety and ergonomics of skull base drilling by stabilizing the drill and enforcing virtual fixtures to protect critical neurovascular structures. The next step is to improve the accuracy so that the overcut can be reduced to a more clinically acceptable value of about 1 mm. PMID:18803337

  12. Virtual reality in rhinology-a new dimension of clinical experience.

    PubMed

    Klapan, Ivica; Raos, Pero; Galeta, Tomislav; Kubat, Goranka

    2016-07-01

    There is often a need to more precisely identify the extent of pathology and the fine elements of intracranial anatomic features during the diagnostic process and during many operations in the nose, sinus, orbit, and skull base region. In two case reports, we describe the methods used in the diagnostic workup and surgical therapy in the nose and paranasal sinus region. Besides baseline x-ray, multislice computed tomography, and magnetic resonance imaging, operative field imaging was performed via a rapid prototyping model, virtual endoscopy, and 3-D imaging. Different head tissues were visualized in different colors, showing their anatomic interrelations and the extent of pathologic tissue within the operative field. This approach has not yet been used as a standard preoperative or intraoperative procedure in otorhinolaryngology. In this way, we tried to understand the new, visualized "world of anatomic relations within the patient's head" by creating an impression of perception (virtual perception) of the given position of all elements in a particular anatomic region of the head, which does not exist in the real world (virtual world). This approach was aimed at upgrading the diagnostic workup and surgical therapy by ensuring a faster, safer and, above all, simpler operative procedure. In conclusion, any ENT specialist can provide virtual reality support in implementing surgical procedures, with additional control of risks and within the limits of normal tissue, without additional trauma to the surrounding tissue in the anatomic region. At the same time, the virtual reality support provides an impression of the virtual world as the specialist navigates through it and manipulates virtual objects. PMID:27434481

  13. 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…

  14. Virtual colonoscopy

    MedlinePlus

    Colonoscopy - virtual; CT colonography; Computed tomographic colonography; Colography - virtual ... standards for gastroenterologists for performing and interpreting diagnostic computed tomography colonography: 2011 update. Gastroenterology . 2011;141:2240-2266. ...

  15. Memory consolidation of landmarks in good navigators.

    PubMed

    Janzen, Gabriele; Jansen, Clemens; van Turennout, Miranda

    2008-01-01

    Landmarks play an important role in successful navigation. To successfully find your way around an environment, navigationally relevant information needs to be stored and become available at later moments in time. Evidence from functional magnetic resonance imaging (fMRI) studies shows that the human parahippocampal gyrus encodes the navigational relevance of landmarks. In the present event-related fMRI experiment, we investigated memory consolidation of navigationally relevant landmarks in the medial temporal lobe after route learning. Sixteen right-handed volunteers viewed two film sequences through a virtual museum with objects placed at locations relevant (decision points) or irrelevant (nondecision points) for navigation. To investigate consolidation effects, one film sequence was seen in the evening before scanning, the other one was seen the following morning, directly before scanning. Event-related fMRI data were acquired during an object recognition task. Participants decided whether they had seen the objects in the previously shown films. After scanning, participants answered standardized questions about their navigational skills, and were divided into groups of good and bad navigators, based on their scores. An effect of memory consolidation was obtained in the hippocampus: Objects that were seen the evening before scanning (remote objects) elicited more activity than objects seen directly before scanning (recent objects). This increase in activity in bilateral hippocampus for remote objects was observed in good navigators only. In addition, a spatial-specific effect of memory consolidation for navigationally relevant objects was observed in the parahippocampal gyrus. Remote decision point objects induced increased activity as compared with recent decision point objects, again in good navigators only. The results provide initial evidence for a connection between memory consolidation and navigational ability that can provide a basis for successful

  16. [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. PMID:25443866

  17. [Artificial nutrition and preoperative fasting].

    PubMed

    Francq, B; Sohawon, S; Perlot, I; Sekkat, H; Noordally, S O

    2012-01-01

    Preoperative fasting is a currently adopted measure since Mendelson's report pertaining to aspiration pneumonia as a cause of death following general anesthesia. From a metabolic point of view fasting is detrimental because surgery in itself causes a state of hypercatabolism and hyperglycemia as a result of insulinresistance. Preoperative fasting has become almost obsolete in certain elective surgical procedures. In these cases the use of clear liquids is now well established and this paper focuses on the safe use of clear fluids, postoperative insulinresistance, patient comfort and postoperative outcome as well as its effect on the length of stay. PMID:22812052

  18. 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

  19. 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. PMID:17558674

  20. NES: Search the Virtual Campus

    NASA Video Gallery

    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...

  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. 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

  3. Apollo Onboard Navigation Techniques

    NASA Technical Reports Server (NTRS)

    Interbartolo, Michael

    2009-01-01

    This viewgraph presentation reviews basic navigation concepts, describes coordinate systems and identifies attitude determination techniques including Primary Guidance, Navigation and Control System (PGNCS) IMU management and Command and Service Module Stabilization and Control System/Lunar Module (LM) Abort Guidance System (AGS) attitude management. The presentation also identifies state vector determination techniques, including PGNCS coasting flight navigation, PGNCS powered flight navigation and LM AGS navigation.

  4. Preoperative Oral Carbohydrate Loading in Pancreaticoduodenectomy

    PubMed Central

    Son, Kum-Hee; Kim, So-Young; Cho, Yeong-Ah; Han, Sung-Sik; Park, Sang-Jae

    2016-01-01

    Overnight fasting before elective surgery has been the routine to reduce the risk of pulmonary aspiration. Recently, several international guidelines for preoperative fasting recommend to intake carbohydrate-containing fluids up to 2 to 3 hours before the induction of anesthesia to improve postoperative recovery. Based on the recommendations, we developed a "preoperative carbohydrate diet" provided for the preoperative patients. The purpose of this case report is to share our experience of applying preoperative carbohydrate loading prior to surgery. PMID:27482525

  5. Planning of skull base surgery in the virtual workbench: clinical experiences.

    PubMed

    Kockro, R A; Serra, L; Tsai, Y T; Chan, C; Sitoh, Y Y; Chua, G G; Hern, N; Lee, E; Hoe, L Y; Nowinski, W

    1999-01-01

    Based on the KRDL Virtual Workbench, we present a neurosurgical planning system called VIVIAN (Virtual Intracranial Visualization And Navigation). This VR environment allows for fast and intuitive interaction with three-dimensional multimodal (MRI, MRA, MRV, CT) patient specific data-sets. The user reaches behind a mirror into a 3D workspace where the 3D data is surrounded by interactive virtual tools-racks. Tumors, blood vessels, cranial nerves and surgically relevant parts of the brain are segmented by interactive control of density transfer-functions or by manual outlining and tracing tools. A neurosurgical procedure is planned by using various visualization and measurement tools and the system allows for the simulation of bone drilling and tissue removal. We have planned 16 cases which required tumor surgery at the cranial base. VIVIAN provided an efficient and comprehensive way to understand pre-operatively the complexity of anatomical and pathological relationships. The ideal craniotomy and the extent of the required skull base exposure could be specified accurately. PMID:10538353

  6. Open-source platforms for navigated image-guided interventions.

    PubMed

    Ungi, Tamas; Lasso, Andras; Fichtinger, Gabor

    2016-10-01

    Navigation technology is changing the clinical standards in medical interventions by making existing procedures more accurate, and new procedures possible. Navigation is based on preoperative or intraoperative imaging combined with 3-dimensional position tracking of interventional tools registered to the images. Research of navigation technology in medical interventions requires significant engineering efforts. The difficulty of developing such complex systems has been limiting the clinical translation of new methods and ideas. A key to the future success of this field is to provide researchers with platforms that allow rapid implementation of applications with minimal resources spent on reimplementing existing system features. A number of platforms have been already developed that can share data in real time through standard interfaces. Complete navigation systems can be built using these platforms using a layered software architecture. In this paper, we review the most popular platforms, and show an effective way to take advantage of them through an example surgical navigation application. PMID:27344106

  7. 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.

  8. [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. PMID:26320341

  9. The value of preoperative planning.

    PubMed

    Graves, Matt L

    2013-10-01

    "Better to throw your disasters into the waste paper basket than to consign your patients to the scrap heap" has been a proverb of Jeff Mast, one of the greatest fracture and deformity surgeons in the history of our specialty. Stated slightly more scientifically, one of the major values of simulation is that it allows one to make mistakes in a consequence-free environment. Preoperative planning is the focus of this article. The primary goal is not to provide you with a recipe of how to steps. Rather, the primary goal of this article is to explain why preoperative planning should be standard, to clarify what should be included, and to provide examples of what can happen when planning is ignored. At the end of this, we should all feel the need to approach fracture care more intellectually with forethought, both in our own practices and in our educational system. PMID:23880563

  10. Surgical navigation-assisted mandibular reconstruction with fibula flaps.

    PubMed

    Shan, X-F; Chen, H-M; Liang, J; Huang, J-W; Zhang, L; Cai, Z-G; Guo, Chuanbin

    2016-04-01

    The mandible has an important role in appearance and function. The aim of this study was to describe and evaluate surgical navigation-assisted mandibular reconstruction with the fibula flap. Patients recruited into the study had a custom dental splint fabricated to maintain the mandible in a fixed position. Later, the computed tomography (CT) scan, preoperative design, and operation on the mandible were done in the same position. At 1 week after surgery, a CT scan was done to evaluate the repeatability between the preoperative design and the postoperative result. Twenty patients were enrolled in this study. Good repeatability between the postoperative CT and the preoperative design was found. The repeatability between the preoperative plan and postoperative outcome was 79.1±8.6% at within 1mm, 87.1±6.7% at within 2mm, and 91.9±5.4% at within 3mm. From this study, it can be concluded that surgical navigation techniques can precisely transfer the preoperative design to the operation in mandible reconstruction with a fibula flap. This will assist the surgeon in achieving good cosmetic and functional outcomes. PMID:26723498

  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. 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

    2015-01-01

    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

  13. Theta oscillations and human navigation: a magnetoencephalography study.

    PubMed

    de Araújo, Dráulio B; Baffa, Oswaldo; Wakai, Ronald T

    2002-01-01

    Magnetoencephalography (MEG) was used to study alpha and theta activity while subjects navigated through a computer-generated virtual reality town. The subjects were first allowed to explore the environment freely. They then had to navigate from a starting point to a destination, knowing that an obstruction would appear at one of several possible locations along the main route and force them to take a detour. Spatiotemporal analysis of the theta and alpha bands were performed (1) prior to the start of navigation, (2) from the start of navigation until the obstruction was encountered, (3) during the time subjects were contemplating a detour and were not navigating, and (4) from the resumption of navigation until the destination was reached. In all subjects, theta power was strongest during the two periods of navigation. The peak frequency of the oscillations was approximately 3.7 Hz. Control studies consisted of a motor task similar to that required for navigation, passive viewing of a tour through the same virtual reality town, and a mental concentration task. No consistent increases in theta power were seen in the MEG during any of the control tasks. The results suggest an association between theta rhythm and the performance of navigational tasks in humans. PMID:11798388

  14. Microcomputers and astronomical navigation.

    NASA Astrophysics Data System (ADS)

    Robin-Jouan, Y.

    1996-04-01

    Experienced navigators remember ancient astronomical navigation and its limitations. Using microcomputers in small packages and selecting up-to-date efficient methods will overcome many of these limitations. Both features lead to focus on observations, and encourage an increase in their numbers. With no intention of competing with satellite navigation, sextant navigation in the open sea can then be accessed again by anybody. It can be considered for demonstrative use or as a complement to the GPS.

  15. 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

  16. Evolution of patient navigation.

    PubMed

    Shockney, Lillie D

    2010-08-01

    The role of nurses in patient navigation has evolved over more than four decades. Navigators in cancer care can guide patients through the physical, emotional, and financial challenges that come with a diagnosis of cancer and facilitate communication among healthcare providers. Navigation has the potential to improve patient outcomes and system efficiency. Oncology nurses are well suited to help patients with cancer navigate the healthcare system from diagnosis and treatment through survivorship and palliative care. PMID:20682496

  17. 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. PMID:25416007

  18. Laparoscopic Navigated Liver Resection: Technical Aspects and Clinical Practice in Benign Liver Tumors

    PubMed Central

    Kleemann, Markus; Deichmann, Steffen; Esnaashari, Hamed; Besirevic, Armin; Shahin, Osama; Bruch, Hans-Peter; Laubert, Tilman

    2012-01-01

    Laparoscopic liver resection has been performed mostly in centers with an extended expertise in both hepatobiliary and laparoscopic surgery and only in highly selected patients. In order to overcome the obstacles of this technique through improved intraoperative visualization we developed a laparoscopic navigation system (LapAssistent) to register pre-operatively reconstructed three-dimensional CT or MRI scans within the intra-operative field. After experimental development of the navigation system, we commenced with the clinical use of navigation-assisted laparoscopic liver surgery in January 2010. In this paper we report the technical aspects of the navigation system and the clinical use in one patient with a large benign adenoma. Preoperative planning data were calculated by Fraunhofer MeVis Bremen, Germany. After calibration of the system including camera, laparoscopic instruments, and the intraoperative ultrasound scanner we registered the surface of the liver. Applying the navigated ultrasound the preoperatively planned resection plane was then overlain with the patient's liver. The laparoscopic navigation system could be used under sterile conditions and it was possible to register and visualize the preoperatively planned resection plane. These first results now have to be validated and certified in a larger patient collective. A nationwide prospective multicenter study (ProNavic I) has been conducted and launched. PMID:23133783

  19. 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

  20. 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

  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. Neural encoding of objects relevant for navigation and resting state correlations with navigational ability.

    PubMed

    Wegman, Joost; Janzen, Gabriele

    2011-12-01

    Objects along a route can help us to successfully navigate through our surroundings. Previous neuroimaging research has shown that the parahippocampal gyrus (PHG) distinguishes between objects that were previously encountered at navigationally relevant locations (decision points) and irrelevant locations (nondecision points) during simple object recognition. This study aimed at unraveling how this neural marking of objects relevant for navigation is established during learning and postlearning rest. Twenty-four participants were scanned using fMRI while they were viewing a route through a virtual environment. Eye movements were measured, and brain responses were time-locked to viewing each object. The PHG showed increased responses to decision point objects compared with nondecision point objects during route learning. We compared functional connectivity between the PHG and the rest of the brain in a resting state scan postlearning with such a scan prelearning. Results show that functional connectivity between the PHG and the hippocampus is positively related to participants' self-reported navigational ability. On the other hand, connectivity with the caudate nucleus correlated negatively with navigational ability. These results are in line with a distinction between egocentric and allocentric spatial representations in the caudate nucleus and the hippocampus, respectively. Our results thus suggest a relation between navigational ability and a neural preference for a specific type of spatial representation. Together, these results show that the PHG is immediately involved in the encoding of navigationally relevant object information. Furthermore, they provide insight into the neural correlates of individual differences in spatial ability. PMID:21671733

  3. Intelligent virtual interfaces for telerobotics

    NASA Astrophysics Data System (ADS)

    Grinstein, Georges G.; Maybury, Mark T.; Mitchell, Richard B.

    1992-11-01

    One promise of telerobotics is the ability to interact in environments that are distant (e.g., deep sea or deep space), dangerous (e.g., nuclear, chemical, or biological environments), or inaccessible by humans for political or legal reasons. A key component to such interactions are sophisticated human-computer interfaces that can replicate sufficient information about a local environment to permit remote navigation and manipulation. This environment replication can, in part, be provided by technologies such as virtual reality. In addition, however, telerobotic interfaces may need to enhance human-machine interaction to assist users in task performance, for example, governing motion or manipulation controls to avoid obstacles or to restrict interaction with certain objects (e.g., avoiding contact with a live mine or a deep sea treasure). Thus, effective interactions within remote environments require intelligent virtual interfaces to telerobotic devices. In part to address this problem, MITRE is investigating virtual reality architectures that will enable enhanced interaction within virtual environments. Key components to intelligent virtual interfaces include spoken language processing, gesture recognition algorithms, and more generally, task recognition. In addition, these interfaces will eventually have to take into account properties of the user, the task, and discourse context to be more adaptive to the current situation at hand. While our work has not yet investigated the connection of virtual interfaces to external robotic devices, we have begun developing the key components for intelligent virtual interfaces for information and training systems.

  4. 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).

  5. Computer Navigation-aided Resection of Sacral Chordomas

    PubMed Central

    Yang, Yong-Kun; Chan, Chung-Ming; Zhang, Qing; Xu, Hai-Rong; Niu, Xiao-Hui

    2016-01-01

    Background: Resection of sacral chordomas is challenging. The anatomy is complex, and there are often no bony landmarks to guide the resection. Achieving adequate surgical margins is, therefore, difficult, and the recurrence rate is high. Use of computer navigation may allow optimal preoperative planning and improve precision in tumor resection. The purpose of this study was to evaluate the safety and feasibility of computer navigation-aided resection of sacral chordomas. Methods: Between 2007 and 2013, a total of 26 patients with sacral chordoma underwent computer navigation-aided surgery were included and followed for a minimum of 18 months. There were 21 primary cases and 5 recurrent cases, with a mean age of 55.8 years old (range: 35–84 years old). Tumors were located above the level of the S3 neural foramen in 23 patients and below the level of the S3 neural foramen in 3 patients. Three-dimensional images were reconstructed with a computed tomography-based navigation system combined with the magnetic resonance images using the navigation software. Tumors were resected via a posterior approach assisted by the computer navigation. Mean follow-up was 38.6 months (range: 18–84 months). Results: Mean operative time was 307 min. Mean intraoperative blood loss was 3065 ml. For computer navigation, the mean registration deviation during surgery was 1.7 mm. There were 18 wide resections, 4 marginal resections, and 4 intralesional resections. All patients were alive at the final follow-up, with 2 (7.7%) exhibiting tumor recurrence. The other 24 patients were tumor-free. The mean Musculoskeletal Tumor Society Score was 27.3 (range: 19–30). Conclusions: Computer-assisted navigation can be safely applied to the resection of the sacral chordomas, allowing execution of preoperative plans, and achieving good oncological outcomes. Nevertheless, this needs to be accomplished by surgeons with adequate experience and skill. PMID:26830986

  6. Risk of Anterior Femoral Notching in Navigated Total Knee Arthroplasty

    PubMed Central

    Lee, Ju Hong

    2015-01-01

    Background We retrospectively investigated the prevalence of femoral anterior notching and risk factors after total knee arthroplasty (TKA) using an image-free navigation system. Methods We retrospectively reviewed 148 consecutive TKAs in 130 patients beginning in July 2005. Seventy knees (62 patients) underwent conventional TKA, and 78 knees (68 patients) received navigated TKA. We investigated the prevalence of femoral anterior notching and measured notching depth by conventional and navigated TKA. Additionally, the navigated TKA group was categorized into two subgroups according to whether anterior femoral notching had occurred. The degree of preoperative varus deformity, femoral bowing, and mediolateral suitability of the size of the femoral component were determined by reviewing preoperative and postoperative radiographs. The resection angle on the sagittal plane and the angle of external rotation that was set by the navigation system were checked when resecting the distal femur. Clinical outcomes were compared using range of motion (ROM) and the Hospital for Special Surgery (HSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAX) scores between the two groups. Results The prevalence of anterior femoral notching by conventional TKA was 5.7%, and that for navigated TKA was 16.7% (p = 0.037). Mean notching depth by conventional TKA was 2.92 ± 1.18 mm (range, 1.8 to 4.5 mm) and 3.32 ± 1.54 mm (range, 1.55 to 6.93 mm) by navigated TKA. Preoperative anterior femoral bowing was observed in 61.5% (p = 0.047) and both anterior and lateral femoral bowing in five cases in notching group during navigated TKA (p = 0.021). Oversized femoral components were inserted in 53.8% of cases (p = 0.035). No differences in clinical outcomes for ROM or the HSS and WOMAX scores were observed between the groups. A periprosthetic fracture, which was considered a notching-related side effect, occurred in one case each in the conventional and navigated TKA groups

  7. 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

  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. 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,…

  10. Augmented virtuality for arthroscopic knee surgery.

    PubMed

    Li, John M; Bardana, Davide D; Stewart, A James

    2011-01-01

    This paper describes a computer system to visualize the location and alignment of an arthroscope using augmented virtuality. A 3D computer model of the patient's joint (from CT) is shown, along with a model of the tracked arthroscopic probe and the projection of the camera image onto the virtual joint. A user study, using plastic bones instead of live patients, was made to determine the effectiveness of this navigated display; the study showed that the navigated display improves target localization in novice residents. PMID:22003616

  11. Generating Navigation Models from Existing Building Data

    NASA Astrophysics Data System (ADS)

    Liu, L.; Zlatanova, S.

    2013-11-01

    Research on indoor navigation models mainly focuses on geometric and logical models .The models are enriched with specific semantic information which supports localisation, navigation and guidance. Geometric models provide information about the structural (physical) distribution of spaces in a building, while logical models indicate relationships (connectivity and adjacency) between the spaces. In many cases geometric models contain virtual subdivisions to identify smaller spaces which are of interest for navigation (e.g. reception area) or make use of different semantics. The geometric models are used as basis to automatically derive logical models. However, there is seldom reported research on how to automatically realize such geometric models from existing building data (as floor plans) or indoor standards (CityGML LOD4 or IFC). In this paper, we present our experiments on automatic creation of logical models from floor plans and CityGML LOD4. For the creation we adopt the Indoor Spatial Navigation Model (INSM) which is specifically designed to support indoor navigation. The semantic concepts in INSM differ from daily used notations of indoor spaces such as rooms and corridors but they facilitate automatic creation of logical models.

  12. 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.

  13. A Virtual Tour of Virtual Schools.

    ERIC Educational Resources Information Center

    Joiner, Lottie L.

    2002-01-01

    Briefly describes the eight virtual schools in the United States: Kentucky Virtual High School; Illinois Virtual High School; Florida Virtual School; CCS Web Academy in Fayetteville, North Carolina; The Virtual High School in Hudson, Massachusetts; Basehor-Linwood Virtual Charter School in Kansas; Monte Vista Online Academy in Colorado; and…

  14. 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.

  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. Oncology nurse navigator.

    PubMed

    Case, Mary Ann B

    2011-02-01

    The purpose of this integrative review is to explore the presence of the oncology nurse as navigator on measurable patient outcomes. Eighteen primary nursing research studies were found using combinations of the following key words: advocate, cancer, case manager, coach, certification, guide, navigator, nurse, oncology, patient navigator, pivot nurse, and continuity of care. Nurse researchers identified nursing-sensitive patient outcomes related to the time to diagnosis and appropriate treatment, effect on mood states, satisfaction, support, continuity of care, and cost outcomes. Navigator roles are expanding globally, and nurses should continue to embrace opportunities to ensure the safe passage of patients with cancer along the entire trajectory of illness and to evaluate the implications for educational preparation, research, and practice of navigators of all kinds. PMID:21278039

  17. Virtual Colonoscopy

    MedlinePlus

    ... virtual colonoscopy include exposure to radiation perforation—a hole or tear in the lining of the colon ... colonoscopy include exposure to radiation and perforation—a hole or tear in the lining of the colon. [ ...

  18. 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.

  19. Virtual polytopes

    NASA Astrophysics Data System (ADS)

    Panina, G. Yu; Streinu, I.

    2015-12-01

    Originating in diverse branches of mathematics, from polytope algebra and toric varieties to the theory of stressed graphs, virtual polytopes represent a natural algebraic generalization of convex polytopes. Introduced as elements of the Grothendieck group associated to the semigroup of convex polytopes, they admit a variety of geometrizations. The present survey connects the theory of virtual polytopes with other geometrical subjects, describes a series of geometrizations together with relations between them, and gives a selection of applications. Bibliography: 50 titles.

  20. 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.

  1. Preoperative radiotherapy for colorectal cancer.

    PubMed Central

    Higgins, G A; Conn, J H; Jordan, P H; Humphrey, E W; Roswit, B; Keehn, R J

    1975-01-01

    In a prospective randomized trial, 700 patients with a confirmed histological diagnosis of adenocarcinoma of the rectum or rectosigmoid were randomized to receive radiotherapy prior to operation (2000 to 2500 rads in two weeks) or surgery alone. Five year observed survival in the 453 patients on whom "curative" resection was possible was 48.5% in the X-ray treated group compared with 38.8% in controls, while in the 305 having low lying lesions requiring abdominoperineal resection, survival in the treated group was 46.9% compared with 34.3% in controls. Although suggestive of a treatment benefit, neither is considered statistically significant. Histologically positive lymph nodes were found in 41.2% of the control group and in only 27.8% of the patients receiving radiotherapy. Reveiw of all patients who died during the study shows a consistently lower death rate from cancer in the radiotherapy group. Although this study suggests a treatment benefit from preoperative radiotherapy, further studies now in progress by this group and others are necessary to determine the optimal dose regimen. PMID:805571

  2. Effects of comfort warming on preoperative patients.

    PubMed

    Wagner, Doreen; Byrne, Michelle; Kolcaba, Katharine

    2006-09-01

    THERMAL COMFORT IS ONE DIMENSION of overall patient comfort, and it usually is addressed by covering the patient with warmed cotton blankets. WARMING HELPS A PATIENT maintain normothermia and appears to decrease patient anxiety. AN STUDY WAS CONDUCTED in a preoperative setting to compare the effects of preoperative warming with warmed cotton blankets versus patient-controlled warming gowns on patients' perceptions of thermal comfort and anxiety. BOTH WARMING INTERVENTIONS had a positive effect on patients' thermal comfort and sense of well-being. Patients who used the patient-controlled warming gown also experienced a significant reduction in preoperative anxiety. PMID:17004666

  3. [Preoperative assessment for extended hepatic resection].

    PubMed

    Martin, David; Roulin, Didier; Takamune, Yamaguchi; Demartines, Nicolas; Halkic, Nermin

    2016-06-15

    The number of major hepatectomy performed for the treatment of primary or secondary liver cancer has increased over the past two decades. By definition, a major hepatectomy includes the resection of at least three liversegments. Advances in anesthesiology, surgical and radiological techniques and perioperative management allowed a broad patient selection with increased security. Every case must be discussed in multidisciplinary tumor board, and preoperative assessment should include biological, volumetric and functional hepatic parameters. In case of preoperative insufficient liver volume, portal vein embolization allows increasing the size of liver remnant. This paper aims describing preoperative work-up. PMID:27487623

  4. Preoperative Evaluation of the Surgical Patient.

    PubMed

    O'Donnell, Frederick T

    2016-01-01

    Primary care physicians and specialists are frequently involved in the care of surgical patients. Changes in reimbursement have prompted re-examination of preoperative testing and health care expenditures. Physicians have additional incentives to improve health care delivery and reduce costs. The perioperative surgical home concept involves coordinating all aspects of patient care, including behavioral modifications, during the perioperative period. Evidence-based guidelines on preoperative evaluation are available to assist practitioners in managing cardiovascular disease, and communicating surgical risks. Shared decision making in the preoperative period can improve surgical outcomes and patient satisfaction. PMID:27443045

  5. 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. PMID:24260766

  6. 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.

  7. 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…

  8. Navigation Systems for Ablation

    PubMed Central

    Wood, B. J.; Kruecker, J.; Abi-Jaoudeh, N; Locklin, J.; Levy, E.; Xu, S.; Solbiati, L.; Kapoor, A.; Amalou, H.; Venkatesan, A.

    2010-01-01

    Navigation systems, devices and intra-procedural software are changing the way we practice interventional oncology. Prior to the development of precision navigation tools integrated with imaging systems, thermal ablation of hard-to-image lesions was highly dependent upon operator experience, spatial skills, and estimation of positron emission tomography-avid or arterial-phase targets. Numerous navigation systems for ablation bring the opportunity for standardization and accuracy that extends our ability to use imaging feedback during procedures. Existing systems and techniques are reviewed, and specific clinical applications for ablation are discussed to better define how these novel technologies address specific clinical needs, and fit into clinical practice. PMID:20656236

  9. 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…

  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. 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. PMID:24892196

  12. 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

  13. 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

  14. 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.

  15. Inertial/multisensor navigation

    NASA Technical Reports Server (NTRS)

    Alikiotis, Dimitri

    1987-01-01

    A Multisensor Navigation System as proposed by the Ohio University Avionics Engineering Center is illustrated. The proposed system incorporates radio (Lorac-C), satellite (Global Positioning System) and an inertial navigation system (INS). The inertial part of the system will be of a low grade since the INS will be used primarily for filtering the GPS data and for short term stability. Loran-C and GPS will be used for long term stability.

  16. 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.

  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. Grid-like Processing of Imagined Navigation.

    PubMed

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

    2016-03-21

    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) [3-6], 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, 14-16], 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

  19. 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

  20. Spatial Navigation in Preclinical Alzheimer's Disease.

    PubMed

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

    2016-02-01

    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. PMID:26967209

  1. 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. PMID:21525309

  2. 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.

  3. 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. PMID:27432848

  4. Environmental layout complexity affects neural activity during navigation in humans.

    PubMed

    Slone, Edward; Burles, Ford; Iaria, Giuseppe

    2016-05-01

    Navigating large-scale surroundings is a fundamental ability. In humans, it is commonly assumed that navigational performance is affected by individual differences, such as age, sex, and cognitive strategies adopted for orientation. We recently showed that the layout of the environment itself also influences how well people are able to find their way within it, yet it remains unclear whether differences in environmental complexity are associated with changes in brain activity during navigation. We used functional magnetic resonance imaging to investigate how the brain responds to a change in environmental complexity by asking participants to perform a navigation task in two large-scale virtual environments that differed solely in interconnection density, a measure of complexity defined as the average number of directional choices at decision points. The results showed that navigation in the simpler, less interconnected environment was faster and more accurate relative to the complex environment, and such performance was associated with increased activity in a number of brain areas (i.e. precuneus, retrosplenial cortex, and hippocampus) known to be involved in mental imagery, navigation, and memory. These findings provide novel evidence that environmental complexity not only affects navigational behaviour, but also modulates activity in brain regions that are important for successful orientation and navigation. PMID:26990572

  5. Endoscopic navigation for minimally invasive suturing.

    PubMed

    Wengert, Christian; Bossard, Lukas; Häberling, Armin; Baur, Charles; Székely, Gábor; Cattin, Philippe C

    2007-01-01

    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. This paper presents an approach for tracking a suturing needle using a standard endoscope. The resulting pose information of the needle is then used to generate artificial 3D cues on the 2D screen to optimally support surgeons during tissue suturing. Additionally, if an external tracking device is provided to report the endoscope's position, the suturing needle can be tracked in a hybrid fashion with sub-millimeter accuracy. Finally, a visual navigation aid can be incorporated, if a 3D surface is intraoperatively reconstructed from video or registered from preoperative imaging. PMID:18044620

  6. 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.

  7. 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

  8. 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 navigation, navigation charts, and related data policy, practices and procedure. 209.325 Section 209.325 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE ADMINISTRATIVE PROCEDURE § 209.325 Navigation...

  9. Engineering applications of virtual reality

    NASA Astrophysics Data System (ADS)

    Smith, James R.; Grimes, Robert V.; Plant, Tony A.

    1996-04-01

    This paper addresses some of the practical applications, advantages and difficulties associated with the engineering applications of virtual reality. The paper tracks actual investigative work in progress on this subject at the BNR research lab in RTP, NC. This work attempts to demonstrate the actual value added to the engineering process by using existing 3D CAD data for interactive information navigation and evaluation of design concepts and products. Specifically, the work includes translation of Parametric Technology's Pro/ENGINEER models into a virtual world to evaluate potential attributes such as multiple concept exploration and product installation assessment. Other work discussed in this paper includes extensive evaluation of two new tools, VRML and SGI's/Template Graphics' WebSpace for navigation through Pro/ENGINEER models with links to supporting technical documentation and data. The benefits of using these tolls for 3D interactive navigation and exploration throughout three key phases of the physical design process is discussed in depth. The three phases are Design Concept Development, Product Design Evaluation and Product Design Networking. The predicted values added include reduced time to `concept ready', reduced prototype iterations, increased `design readiness' and shorter manufacturing introduction cycles.

  10. Navigating the System

    MedlinePlus

    ... Webinars Widgets Wikis Follow Us on New Media Virtual Office Hours Registration News & Events Awareness Days National ... you access these services. Keep records of your lab tests and other test results and the name ...

  11. Computer navigation of soft tissues in total knee replacement.

    PubMed

    Kamat, Yogeesh D; Aurakzai, Kamran M; Adhikari, Ajeya R

    2013-06-01

    Following the success of computer navigation in producing consistently accurate alignment, the focus has shifted to use of these techniques for soft tissue assessment during total knee replacement (TKR). We undertook a prospectively randomized clinical study to compare two methods of tissue balancing in TKR. One method, called bone referencing (BR) employed independent cutting of the femur and tibia followed by subjective assessment with trial prostheses and soft tissue release as deemed necessary. The other method, termed ligament balancing (LB), involved cutting the tibia first and titration of tissue balance and alignment parameters to guide femoral cuts. Our total sample comprised 77 subjects with 80% statistical power. To assess tissue balance we used (a) coronal laxity testing and (b) computer navigation generated passive knee range of movement graphs. The graphical assessment was validated with coronal laxity testing. There was no difference between the resultant tissue balances achieved. However, correlation with preoperative status revealed the LB technique to show better results in a smaller subgroup of knees with greater preoperative tissue imbalance. We advocate variation of tissue balancing technique to suit the individual knee, based on preoperative assessment, to achieve an optimal result in all TKR. PMID:23288758

  12. Preoperative Antibiotics and Mortality in the Elderly

    PubMed Central

    Silber, Jeffrey H.; Rosenbaum, Paul R.; Trudeau, Martha E.; Chen, Wei; Zhang, Xuemei; Lorch, Scott A.; Kelz, Rachel Rapaport; Mosher, Rachel E.; Even-Shoshan, Orit

    2005-01-01

    Objective and Background: It is generally thought that the use of preoperative antibiotics reduces the risk of postoperative infection, yet few studies have described the association between preoperative antibiotics and the risk of dying. The objective of this study was to determine whether preoperative antibiotics are associated with a reduced risk of death. Methods: We performed a multivariate matched, population-based, case-control study of death following surgery on 1362 Pennsylvania Medicare patients between 65 and 85 years of age undergoing general and orthopedic surgery. Cases (681 deaths within 60 days from hospital admission) were randomly selected throughout Pennsylvania using claims from 1995 and 1996. Models were developed to scan Medicare claims, looking for controls who did not die and who were the closest matches to the previously selected cases based on preoperative characteristics. Cases and their controls were identified, and charts were abstracted to define antibiotic use and obtain baseline severity adjustment data. Results: For general surgery, the odds of dying within 60 days were less than half in those treated with preoperative antibiotics within 2 hours of incision as compared with those without such treatment: (odds ratio = 0.44; 95% confidence interval, 0.32–0.60), P < 0.0001). For orthopedic surgery, no significant mortality reduction was observed (OR = 0.85; 95% confidence interval, 0.54–1.32; P < 0.464). Interpretation: Preoperative antibiotics are associated with a substantially lower 60-day mortality rate in elderly patients undergoing general surgery. In patients who appear to be comparable, the risk of death was half as large among those who received preoperative antibiotics. PMID:15973108

  13. 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.

  14. 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.

  15. 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…

  16. Virtual Labs.

    ERIC Educational Resources Information Center

    Russo, Ruth

    1997-01-01

    Discusses the potential of computers in teaching laboratories to spare the lives of animals; however, it is felt that in areas of physiology education, virtual labs are not as desirable a learning experience for advanced students as live animal labs. (Author/AIM)

  17. Virtual Reality.

    ERIC Educational Resources Information Center

    Newby, Gregory B.

    1993-01-01

    Discusses the current state of the art in virtual reality (VR), its historical background, and future possibilities. Highlights include applications in medicine, art and entertainment, science, business, and telerobotics; and VR for information science, including graphical display of bibliographic data, libraries and books, and cyberspace.…

  18. 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.

  19. 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. PMID:26454321

  20. Recent advances in surgical planning & navigation for tumor biopsy and resection.

    PubMed

    Wang, Defeng; Ma, Diya; Wong, Matthew Lun; Wáng, Yì Xiáng J

    2015-10-01

    This paper highlights recent advancements in imaging technologies for surgical planning and navigation in tumor biopsy and resection which need high-precision in detection and characterization of lesion margin in preoperative planning and intraoperative navigation. Multimodality image-guided surgery platforms brought great benefits in surgical planning and operation accuracy via registration of various data sets with information on morphology [X-ray, magnetic resonance (MR), computed tomography (CT)], function connectivity [functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), rest-status fMRI], or molecular activity [positron emission tomography (PET)]. These image-guided platforms provide a correspondence between the pre-operative surgical planning and intra-operative procedure. We envisage that the combination of advanced multimodal imaging, three-dimensional (3D) printing, and cloud computing will play increasingly important roles in planning and navigation of surgery for tumor biopsy and resection in the coming years. PMID:26682133

  1. Recent advances in surgical planning & navigation for tumor biopsy and resection

    PubMed Central

    Ma, Diya; Wong, Matthew Lun; Wáng, Yì Xiáng J.

    2015-01-01

    This paper highlights recent advancements in imaging technologies for surgical planning and navigation in tumor biopsy and resection which need high-precision in detection and characterization of lesion margin in preoperative planning and intraoperative navigation. Multimodality image-guided surgery platforms brought great benefits in surgical planning and operation accuracy via registration of various data sets with information on morphology [X-ray, magnetic resonance (MR), computed tomography (CT)], function connectivity [functional magnetic resonance imaging (fMRI), diffusion tensor imaging (DTI), rest-status fMRI], or molecular activity [positron emission tomography (PET)]. These image-guided platforms provide a correspondence between the pre-operative surgical planning and intra-operative procedure. We envisage that the combination of advanced multimodal imaging, three-dimensional (3D) printing, and cloud computing will play increasingly important roles in planning and navigation of surgery for tumor biopsy and resection in the coming years. PMID:26682133

  2. Coordinating sensing and local navigation

    NASA Astrophysics Data System (ADS)

    Slack, Marc G.

    1991-07-01

    Based on Navigation Templates (or NaTs), this work presents a new paradigm for local navigation which addresses the noisy and uncertain nature of sensor data. Rather than creating a new navigation plan each time the robot's perception of the world changes, the technique incorporates perceptual changes directly into the existing navigation plan. In this way, the robot's navigation plan is quickly and continuously modified, resulting in actions that remain coordinated with its changing perception of the world.

  3. Voyager navigation strategy and accuracy

    NASA Technical Reports Server (NTRS)

    Jones, J. B.; Mcdanell, J. P.; Bantell, M. H., Jr.; Chadwick, C.; Jacobson, R. A.; Miller, L. J.; Synnott, S. P.; Van Allen, R. E.

    1977-01-01

    The paper presents the results of the prelaunch navigation studies conducted for the Mariner spacecraft launched toward encounters with the giant planets. The navigation system and the strategy for using this system are described. The requirements on the navigation system demanded by the goals of the project are mentioned, and the predicted navigational capability relative to each of the requirements is discussed. Baseline navigation results for three possible trajectories are analyzed.

  4. Coordinating sensing and local navigation

    NASA Technical Reports Server (NTRS)

    Slack, Marc G.

    1991-01-01

    Based on Navigation Templates (or NaTs), this work presents a new paradigm for local navigation which addresses the noisy and uncertain nature of sensor data. Rather than creating a new navigation plan each time the robot's perception of the world changes, the technique incorporates perceptual changes directly into the existing navigation plan. In this way, the robot's navigation plan is quickly and continuously modified, resulting in actions that remain coordinated with its changing perception of the world.

  5. Spatial navigation impairment is proportional to right hippocampal volume

    PubMed Central

    Nedelska, Zuzana; Andel, Ross; Laczó, Jan; Vlcek, Kamil; Horinek, Daniel; Lisy, Jiri; Sheardova, Katerina; Bureš, Jan; Hort, Jakub

    2012-01-01

    Cognitive deficits in older adults attributable to Alzheimer's disease (AD) pathology are featured early on by hippocampal impairment. Among these individuals, deterioration in spatial navigation, manifested by poor hippocampus-dependent allocentric navigation, may occur well before the clinical onset of dementia. Our aim was to determine whether allocentric spatial navigation impairment would be proportional to right hippocampal volume loss irrespective of general brain atrophy. We also contrasted the respective spatial navigation scores of the real-space human Morris water maze with its corresponding 2D computer version. We included 42 cognitively impaired patients with either amnestic mild cognitive impairment (n = 23) or mild and moderate AD (n = 19), and 14 cognitively intact older controls. All participants underwent 1.5T MRI brain scanning with subsequent automatic measurement of the total brain and hippocampal (right and left) volumes. Allocentric spatial navigation was tested in the real-space version of the human Morris water maze and in its corresponding computer version. Participants used two navigational cues to locate an invisible goal independent of the start position. We found that smaller right hippocampal volume was associated with poorer navigation performance in both the real-space (β = −0.62, P < 0.001) and virtual (β = −0.43, P = 0.026) versions, controlling for demographic variables, total brain and left hippocampal volumes. In subsequent analyses, the results were significant in cognitively impaired (P ≤ 0.05) but not in cognitively healthy (P > 0.59) subjects. The respective real-space and virtual scores strongly correlated with each other. Our findings indicate that the right hippocampus plays a critical role in allocentric navigation, particularly when cognitive impairment is present. PMID:22308496

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Preoperative planning and postoperative evaluation of total hip arthroplasty that takes combined anteversion.

    PubMed

    Imai, Hiroshi; Miyawaki, Joji; Kamada, Tomomi; Takeba, Jun; Mashima, Naohiko; Miura, Hiromasa

    2016-07-01

    The purpose of this study was to investigate whether postoperative combined anteversion (CA) can be kept within the safe zone while using cementless total hip arthroplasty (THA) using the operative technique which prepares the socket first for developmental dysplasia of the hip (DDH), by estimating the anteversion of the metaphyseal fit stem using preoperative three-dimensional (3D) computerized planning and by adjusting the anteversion of the socket using a navigation system that considers CA. Our subjects were 65 patients (65 hips) that had undergone cementless THA for DDH that could be observed for 1 year or more. Clinical assessments were made using the Japanese Orthopaedic Association's (JOA) hip score. For a radiological evaluation, we investigated 3D-planned stem versions, postoperative stem versions, preoperative and postoperative CA, and the relationship between CA and dislocation tendencies with temporary intraoperative reductions. JOA hip scores improved from 52.3 ± 11.4 points to 88.9 ± 8.6 points. CT evaluations revealed that 3D-planned stem versions were strongly correlated with postoperative stem versions (r = 0.80; p < 0.01). Preoperative CA was 50.5° ± 7.2°, and postoperative CA was 41.3° ± 8.6°. Postoperative CA was kept within the safe zone in 61 hips. No intraoperative dislocation tendencies were observed in any hips. By estimating the anteversion of the cementless metaphyseal fit stem using 3D planning preoperatively and adjusting the angle of anteversion of the socket using a navigation system that considers CA intraoperatively, postoperative CA can very frequently be kept within the safe zone, even with cementless THA using the operative technique which prepares the socket first for DDH. PMID:27154291

  11. A navigational guidance system in the human brain.

    PubMed

    Spiers, Hugo J; Maguire, Eleanor A

    2007-01-01

    Finding your way in large-scale space requires knowing where you currently are and how to get to your goal destination. While much is understood about the neural basis of one's current position during navigation, surprisingly little is known about how the human brain guides navigation to goals. Computational accounts argue that specific brain regions support navigational guidance by coding the proximity and direction to the goal, but empirical evidence for such mechanisms is lacking. Here, we scanned subjects with functional magnetic resonance imaging as they navigated to goal destinations in a highly accurate virtual simulation of a real city. Brain activity was then analyzed in combination with metric measures of proximity and direction to goal destinations that were derived from each individual subject's coordinates at every second of navigation. We found that activity in the medial prefrontal cortex was positively correlated, and activity in a right subicular/entorhinal region was negatively correlated with goal proximity. By contrast, activity in bilateral posterior parietal cortex was correlated with egocentric direction to goals. Our results provide empirical evidence for a navigational guidance system in the human brain, and define more precisely the contribution of these three brain regions to human navigation. In addition, these findings may also have wider implications for how the brain monitors and integrates different types of information in the service of goal-directed behavior in general. PMID:17492693

  12. A navigational guidance system in the human brain

    PubMed Central

    Spiers, Hugo J.; Maguire, Eleanor A.

    2008-01-01

    Finding your way in large-scale space requires knowing where you currently are and how to get to your goal destination. While much is understood about the neural basis of one’s current position during navigation, surprisingly little is known about how the human brain guides navigation to goals. Computational accounts argue that specific brain regions support navigational guidance by coding the proximity and direction to the goal, but empirical evidence for such mechanisms is lacking. Here, we scanned subjects with functional MRI (fMRI) as they navigated to goal destinations in a highly accurate virtual simulation of a real city. Brain activity was then analysed in combination with metric measures of proximity and direction to goal destinations which were derived from each individual subject’s coordinates at every second of navigation. We found that activity in the medial prefrontal cortex was positively correlated, and activity in a right subicular/entorhinal region was negatively correlated with goal proximity. By contrast, activity in bilateral posterior parietal cortex was correlated with egocentric direction to goals. Our results provide empirical evidence for a navigational guidance system in the human brain, and define more precisely the contribution of these three brain regions to human navigation. In addition, these findings may also have wider implications for how the brain monitors and integrates different types of information in the service of goal-directed behaviour in general. PMID:17492693

  13. 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

  14. 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.

  15. 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. PMID:26249245

  16. [Present status of preoperative staging and contemplation on preoperative precision staging for gastric cancer].

    PubMed

    Zhu, Zhenggang

    2016-02-25

    The aim of the preoperative staging of gastric cancer was to evaluate the depth of tumor infiltration (T-stage), the extent or number of metastasized lymph nodes (N-stage), and distant metastasis (M-stage) before surgery, to develop an optimal therapeutic scheme for the patients with gastric cancer. Traditional methods of preoperative staging for gastric cancer are usually imaging diagnostic techniques, such as endoscopic ultrasonography (EUS), CT scan, magnetic resonance imaging (MRI) and laparoscopic exploration. At present, the accuracy of preoperative TNM staging of gastric cancer can generally reach 70% to 85% with significant clinical benefit. The accurate preoperative staging for cancer patients can have a major role in determining the final clinical outcome and in predicting the prognosis. According to the concept of "precision medicine", to achieve "preoperative precision staging of gastric cancer", the application of imaging diagnostic techniques must be combined with the analysis of individual genetic information or tumor molecular pathological classification, which should be based on research of the disease genomics, proteomics and metabolomics. In this article, we provide a review of results on preoperative staging of gastric cancer in recent years, and we also discuss how to think about the "preoperative precision staging of gastric cancer", with special emphasis on the potential of molecular imaging techniques, circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA), molecular targets for tumor targeting therapy and molecular pathological classification, etc. in judging bio-molecular behavior of gastric cancer before surgery. PMID:26831874

  17. 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…

  18. Astronomy and Navigation

    NASA Astrophysics Data System (ADS)

    Pimenta, Fernando

    Different people, seafaring in different parts of the world, used strategies well adapted to their environment with the purpose of safely reaching their destination. Astronomical elements, present in their navigation "toolkit" for orientation, calendar purposes, and time reckoning, contributed to their conceptualization of space and time and were eventually integrated in their ritual, social organization, and social power structure.

  19. 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.

  20. 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.

  1. New orthopaedic implant management tool for computer-assisted planning, navigation, and simulation: from implant CAD files to a standardized XML-based implant database.

    PubMed

    Sagbo, S; Blochaou, F; Langlotz, F; Vangenot, C; Nolte, L-P; Zheng, G

    2005-01-01

    Computer-Assisted Orthopaedic Surgery (CAOS) has made much progress over the last 10 years. Navigation systems have been recognized as important tools that help surgeons, and various such systems have been developed. A disadvantage of these systems is that they use non-standard formalisms and techniques. As a result, there are no standard concepts for implant and tool management or data formats to store information for use in 3D planning and navigation. We addressed these limitations and developed a practical and generic solution that offers benefits for surgeons, implant manufacturers, and CAS application developers. We developed a virtual implant database containing geometrical as well as calibration information for orthopedic implants and instruments, with a focus on trauma. This database has been successfully tested for various applications in the client/server mode. The implant information is not static, however, because manufacturers periodically revise their implants, resulting in the deletion of some implants and the introduction of new ones. Tracking these continuous changes and keeping CAS systems up to date is a tedious task if done manually. This leads to additional costs for system development, and some errors are inevitably generated due to the huge amount of information that has to be processed. To ease management with respect to implant life cycle, we developed a tool to assist end-users (surgeons, hospitals, CAS system providers, and implant manufacturers) in managing their implants. Our system can be used for pre-operative planning and intra-operative navigation, and also for any surgical simulation involving orthopedic implants. Currently, this tool allows addition of new implants, modification of existing ones, deletion of obsolete implants, export of a given implant, and also creation of backups. Our implant management system has been successfully tested in the laboratory with very promising results. It makes it possible to fill the current gap

  2. 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’.

  3. Multimodal image registration for preoperative planning and image-guided neurosurgical procedures.

    PubMed

    Risholm, Petter; Golby, Alexandra J; Wells, William

    2011-04-01

    Image registration is the process of transforming images acquired at different time points, or with different imaging modalities, into the same coordinate system. It is an essential part of any neurosurgical planning and navigation system because it facilitates combining images with important complementary, structural, and functional information to improve the information based on which a surgeon makes critical decisions. Brigham and Women's Hospital (BWH) has been one of the pioneers in developing intraoperative registration methods for aligning preoperative and intraoperative images of the brain. This article presents an overview of intraoperative registration and highlights some recent developments at BWH. PMID:21435571

  4. 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

  5. Navigated Active Learning in an International Academic Virtual Enterprise

    ERIC Educational Resources Information Center

    Horvath, Imre; Wiersma, Meindert; Duhovnik, Joze; Stroud, Ian

    2004-01-01

    Active learning is an educational paradigm that has been reinvented and methodologically underpinned many times in order to intensify learning in various forms. This paper presents a complex approach to active learning in a design-centred academic course with international participation. Research and design were considered as vehicles of active…

  6. Preoperational test report, vent building ventilation system

    SciTech Connect

    Clifton, F.T.

    1997-11-04

    This represents a preoperational test report for Vent Building Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides Heating, Ventilation, and Air Conditioning (HVAC) for the W-030 Ventilation Building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  7. Preoperational test report, primary ventilation system

    SciTech Connect

    Clifton, F.T.

    1997-11-04

    This represents a preoperational test report for Primary Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space filtered venting of tanks AY101, AY102, AZ101, AZ102. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  8. 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.

  9. Intraoperative Fluorescence Imaging and Multimodal Surgical Navigation Using Goggle System.

    PubMed

    Mela, Christopher A; Papay, Francis A; Liu, Yang

    2016-01-01

    Intraoperative imaging is an invaluable tool in many surgical procedures. We have developed a wearable stereoscopic imaging and display system entitled Integrated Imaging Goggle, which can provide real-time multimodal image guidance. With the Integrated Imaging Goggle, wide field-of-view fluorescence imaging is tracked and registered with intraoperative ultrasound imaging and preoperative tomography-based surgical navigation, to provide integrated multimodal imaging capabilities in real-time. Herein we describe the system instrumentation and the methods of using the Integrated Imaging Goggle to guide surgeries. PMID:27283420

  10. Image navigation as a means to expand the boundaries of fluorescence-guided surgery.

    PubMed

    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

    2012-05-21

    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. PMID:22547491

  11. 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.

  12. Virtual Observatories

    NASA Astrophysics Data System (ADS)

    Genova, Françoise

    2011-06-01

    Astronomy has been at the forefront among scientific disciplines for the sharing of data, and the advent of the World Wide Web has produced a revolution in the way astronomers do science. The recent development of the concept of Virtual Observatory builds on these foundations. This is one of the truly global endeavours of astronomy, aiming at providing astronomers with seamless access to data and tools, including theoretical data. Astronomy on-line resources provide a rare example of a world-wide, discipline-wide knowledge infrastructure, based on internationally agreed interoperability standards.

  13. 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.

  14. Terrain-Adaptive Navigation Architecture

    NASA Technical Reports Server (NTRS)

    Helmick, Daniel M.; Angelova, Anelia; Matthies, Larry H.; Helmick, Daniel M.

    2008-01-01

    A navigation system designed for a Mars rover has been designed to deal with rough terrain and/or potential slip when evaluating and executing paths. The system also can be used for any off-road, autonomous vehicles. The system enables vehicles to autonomously navigate different terrain challenges including dry river channel systems, putative shorelines, and gullies emanating from canyon walls. Several of the technologies within this innovation increase the navigation system s capabilities compared to earlier rover navigation algorithms.

  15. 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…

  16. 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

  17. Self-navigating robot

    NASA Technical Reports Server (NTRS)

    Thompson, A. M.

    1978-01-01

    Rangefinding equipment and onboard navigation system determine best route from point to point. Research robot has two TV cameras and laser for scanning and mapping its environment. Path planner finds most direct, unobstructed route that requires minimum expenditure of energy. Distance is used as measure of energy expense, although other measures such as time or power consumption (which would depend on the topography of the path) may be used.

  18. Kinematic evaluation of virtual walking trajectories.

    PubMed

    Cirio, Gabriel; Olivier, Anne-Hélène; Marchal, Maud; Pettré, Julien

    2013-04-01

    Virtual walking, a fundamental task in Virtual Reality (VR), is greatly influenced by the locomotion interface being used, by the specificities of input and output devices, and by the way the virtual environment is represented. No matter how virtual walking is controlled, the generation of realistic virtual trajectories is absolutely required for some applications, especially those dedicated to the study of walking behaviors in VR, navigation through virtual places for architecture, rehabilitation and training. Previous studies focused on evaluating the realism of locomotion trajectories have mostly considered the result of the locomotion task (efficiency, accuracy) and its subjective perception (presence, cybersickness). Few focused on the locomotion trajectory itself, but in situation of geometrically constrained task. In this paper, we study the realism of unconstrained trajectories produced during virtual walking by addressing the following question: did the user reach his destination by virtually walking along a trajectory he would have followed in similar real conditions? To this end, we propose a comprehensive evaluation framework consisting on a set of trajectographical criteria and a locomotion model to generate reference trajectories. We consider a simple locomotion task where users walk between two oriented points in space. The travel path is analyzed both geometrically and temporally in comparison to simulated reference trajectories. In addition, we demonstrate the framework over a user study which considered an initial set of common and frequent virtual walking conditions, namely different input devices, output display devices, control laws, and visualization modalities. The study provides insight into the relative contributions of each condition to the overall realism of the resulting virtual trajectories. PMID:23428452

  19. Multisensor robot navigation system

    NASA Astrophysics Data System (ADS)

    Persa, Stelian; Jonker, Pieter P.

    2002-02-01

    Almost all robot navigation systems work indoors. Outdoor robot navigation systems offer the potential for new application areas. The biggest single obstacle to building effective robot navigation systems is the lack of accurate wide-area sensors for trackers that report the locations and orientations of objects in an environment. Active (sensor-emitter) tracking technologies require powered-device installation, limiting their use to prepared areas that are relative free of natural or man-made interference sources. The hybrid tracker combines rate gyros and accelerometers with compass and tilt orientation sensor and DGPS system. Sensor distortions, delays and drift required compensation to achieve good results. The measurements from sensors are fused together to compensate for each other's limitations. Analysis and experimental results demonstrate the system effectiveness. The paper presents a field experiment for a low-cost strapdown-IMU (Inertial Measurement Unit)/DGPS combination, with data processing for the determination of 2-D components of position (trajectory), velocity and heading. In the present approach we have neglected earth rotation and gravity variations, because of the poor gyroscope sensitivities of our low-cost ISA (Inertial Sensor Assembly) and because of the relatively small area of the trajectory. The scope of this experiment was to test the feasibility of an integrated DGPS/IMU system of this type and to develop a field evaluation procedure for such a combination.

  20. 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.

  1. Autonomous navigation - The ARMMS concept

    NASA Astrophysics Data System (ADS)

    Wood, L. J.; Jones, J. B.; Mease, K. D.; Kwok, J. H.; Goltz, G. L.; Kechichian, J. A.

    1984-08-01

    A conceptual design is outlined for the navigation subsystem of the Autonomous Redundancy and Maintenance Management Subsystem (ARMMS). The principal function of this navigation subsystem is to maintain the spacecraft over a specified equatorial longitude to within + or - 3 deg. In addition, the navigation subsystem must detect and correct internal faults. It comprises elements for a navigation executive and for orbit determination, trajectory, maneuver planning, and maneuver command. Each of these elements is described. The navigation subsystem is to be used in the DSCS III spacecraft.

  2. 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…

  3. Virtual endoscopy of the middle ear.

    PubMed

    Neri, E; Caramella, D; Panconi, M; Berrettini, S; Sellari Franceschini, S; Forli, F; Bartolozzi, C

    2001-01-01

    Virtual endoscopy is a computer-generated simulation of fiberoptic endoscopy, and its application to the study of the middle ear has been recently proposed. The need to represent the middle ear anatomy by means of virtual endoscopy arose from the increased interest of otolarygologists in transtympanic endoscopy. In fact, this imaging method allows the visualization of middle ear anatomy with high detail, but it is evasive and is essentially used for surgical guidance. Virtual endoscopy provides similar perspectives of the tympanic cavity but does not require the tympanic perforation. In the study of the middle ear, specific attention is given to the retroperitoneum. This region contains elevations of the medial wall (pyramidal eminence and ridge, styloid eminence and ridge, subiculum, ponticulus) and depressions (sinus tympani, posterior sinus tympani, facial sinus, fossula of Grivot, oval window fossula), which can be effectively displayed by virtual endoscopy. Virtual endoscopy is foreseen as a useful tool in preoperative management of patients who are candidates for middle ear surgery, since it can predict with high detail the patient's specific anatomy by imaging perspectives familiar to otosurgeons. PMID:11194916

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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.

  9. Preoperative Evaluation: Estimation of Pulmonary Risk.

    PubMed

    Lakshminarasimhachar, Anand; Smetana, Gerald W

    2016-03-01

    Postoperative pulmonary complications (PPCs) are common after major non-thoracic surgery and associated with significant morbidity and high cost of care. A number of risk factors are strong predictors of PPCs. The overall goal of the preoperative pulmonary evaluation is to identify these potential, patient and procedure-related risks and optimize the health of the patients before surgery. A thorough clinical examination supported by appropriate laboratory tests will help guide the clinician to provide optimal perioperative care. PMID:26927740

  10. Implications of preoperative hypoalbuminemia in colorectal surgery.

    PubMed

    Truong, Adam; Hanna, Mark H; Moghadamyeghaneh, Zhobin; Stamos, Michael J

    2016-05-27

    Serum albumin has traditionally been used as a quantitative measure of a patient's nutritional status because of its availability and low cost. While malnutrition has a clear definition within both the American and European Societies for Parenteral and Enteral Nutrition clinical guidelines, individual surgeons often determine nutritional status anecdotally. Preoperative albumin level has been shown to be the best predictor of mortality after colorectal cancer surgery. Specifically in colorectal surgical patients, hypoalbuminemia significantly increases the length of hospital stay, rates of surgical site infections, enterocutaneous fistula risk, and deep vein thrombosis formation. The delay of surgical procedures to allow for preoperative correction of albumin levels in hypoalbuminemic patients has been shown to improve the morbidity and mortality in patients with severe nutritional risk. The importance of preoperative albumin levels and the patient's chronic inflammatory state on the postoperative morbidity and mortality has led to the development of a variety of surgical scoring systems to predict outcomes efficiently. This review attempts to provide a systematic overview of albumin and its role and implications in colorectal surgery. PMID:27231513

  11. Implications of preoperative hypoalbuminemia in colorectal surgery

    PubMed Central

    Truong, Adam; Hanna, Mark H; Moghadamyeghaneh, Zhobin; Stamos, Michael J

    2016-01-01

    Serum albumin has traditionally been used as a quantitative measure of a patient’s nutritional status because of its availability and low cost. While malnutrition has a clear definition within both the American and European Societies for Parenteral and Enteral Nutrition clinical guidelines, individual surgeons often determine nutritional status anecdotally. Preoperative albumin level has been shown to be the best predictor of mortality after colorectal cancer surgery. Specifically in colorectal surgical patients, hypoalbuminemia significantly increases the length of hospital stay, rates of surgical site infections, enterocutaneous fistula risk, and deep vein thrombosis formation. The delay of surgical procedures to allow for preoperative correction of albumin levels in hypoalbuminemic patients has been shown to improve the morbidity and mortality in patients with severe nutritional risk. The importance of preoperative albumin levels and the patient’s chronic inflammatory state on the postoperative morbidity and mortality has led to the development of a variety of surgical scoring systems to predict outcomes efficiently. This review attempts to provide a systematic overview of albumin and its role and implications in colorectal surgery. PMID:27231513

  12. Virtual Reality and the Virtual Library.

    ERIC Educational Resources Information Center

    Oppenheim, Charles

    1993-01-01

    Explains virtual reality, including proper and improper uses of the term, and suggests ways that libraries might be affected by it. Highlights include elements of virtual reality systems; possible virtual reality applications, including architecture, the chemical industry, transport planning, armed forces, and entertainment; and the virtual…

  13. Quantitative error analysis for computer assisted navigation: a feasibility study

    PubMed Central

    Güler, Ö.; Perwög, M.; Kral, F.; Schwarm, F.; Bárdosi, Z. R.; Göbel, G.; Freysinger, W.

    2013-01-01

    Purpose The benefit of computer-assisted navigation depends on the registration process, at which patient features are correlated to some preoperative imagery. The operator-induced uncertainty in localizing patient features – the User Localization Error (ULE) - is unknown and most likely dominating the application accuracy. This initial feasibility study aims at providing first data for ULE with a research navigation system. Methods Active optical navigation was done in CT-images of a plastic skull, an anatomic specimen (both with implanted fiducials) and a volunteer with anatomical landmarks exclusively. Each object was registered ten times with 3, 5, 7, and 9 registration points. Measurements were taken at 10 (anatomic specimen and volunteer) and 11 targets (plastic skull). The active NDI Polaris system was used under ideal working conditions (tracking accuracy 0.23 mm root mean square, RMS; probe tip calibration was 0.18 mm RMS. Variances of tracking along the principal directions were measured as 0.18 mm2, 0.32 mm2, and 0.42 mm2. ULE was calculated from predicted application accuracy with isotropic and anisotropic models and from experimental variances, respectively. Results The ULE was determined from the variances as 0.45 mm (plastic skull), 0.60 mm (anatomic specimen), and 4.96 mm (volunteer). The predicted application accuracy did not yield consistent values for the ULE. Conclusions Quantitative data of application accuracy could be tested against prediction models with iso- and anisotropic noise models and revealed some discrepancies. This could potentially be due to the facts that navigation and one prediction model wrongly assume isotropic noise (tracking is anisotropic), while the anisotropic noise prediction model assumes an anisotropic registration strategy (registration is isotropic in typical navigation systems). The ULE data are presumably the first quantitative values for the precision of localizing anatomical landmarks and implanted fiducials

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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.

  5. 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.

  6. 3D navigation of endoscopic rhizotomy at the lumbar spine.

    PubMed

    Jentzsch, Thorsten; Sprengel, Kai; Peterer, Lorenz; Mica, Ladislav; Werner, Clément M L

    2016-01-01

    We present a detailed description of the surgical technique and the preliminary results of an endoscopic denervation for patients with chronic low back pain (CLBP) originating from the facet joints (FJ). Endoscopic denervation of the medial branches of the dorsal rami supplying the FJ has recently been appraised as providing excellent intraoperative visualization and long term pain relief for these patients. Conventional endoscopic rhizotomy has been expanded to include a the precise localization of 3D navigation. A surgical description and the results of our first four patients treated with 3D navigated endoscopic rhizotomy (3DNER) are presented. Four patients with a mean age of 59years and a follow-up time of 2months were included. All patients reported pain reduction in the immediate postoperative period, while three patients (75%) had long lasting relief. The patient without persisting relief had previously sustained a lumbar disc prolapse and only achieved minor pain relief with preoperative FJ infiltration, compared to the significant relief that was seen in the other patients. In contrast to conventional rhizotomy, 3DNER enables the surgeon to ablate more precisely and extensively, which is especially useful if scar tissue is present from previous injuries or surgeries. When successful, this technique may provide long lasting pain relief, especially if the preoperative FJ infiltrations are followed by a substantial pain reduction. PMID:26628214

  7. 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.

  8. 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.

  9. Ionospheric modelling for navigation

    NASA Astrophysics Data System (ADS)

    Aragon Angel, M. A.

    Signals transmitted to and from satellites for communication and navigation purposes must pass through the ionosphere Ionospheric irregularities most common at equatorial latitudes although they could occur anywhere can have a major impact on system performance and reliability and commercial navigation service satellite-based providers need to account for their effects For a GNSS single-frequency receiver the Slant Total Electron Content STEC must be known by the user through broadcast corrections In this context there are several sets of broadcast parameters that can be defined to take into account this ionospheric term The chosen model to generate the ionospheric correction coefficients for the present study is the NeQuick model although with a number of adaptations intended to improve effective ionospheric effect modelling performances The aim of this study is to describe a possible adaptation to the NeQuick model for real time purposes and suitable for single frequency users Therefore it will be necessary to determine the performance of this modified NeQuick model in correcting the ionospheric delay In order to generate the ionospheric corrections for single frequency receivers using the NeQuick model a certain approach should be followed to adapt the performance of NeQuick since this model was originally developed to provide TEC using averaged monthly information of the solar activity and not daily one Thus to use NeQuick for real time applications as an ionospheric broadcasted model such as Klobuchar solar daily information at the user point

  10. VERS: a virtual environment for reconstructive surgery planning

    NASA Astrophysics Data System (ADS)

    Montgomery, Kevin N.

    1997-05-01

    The virtual environment for reconstructive surgery (VERS) project at the NASA Ames Biocomputation Center is applying virtual reality technology to aid surgeons in planning surgeries. We are working with a craniofacial surgeon at Stanford to assemble and visualize the bone structure of patients requiring reconstructive surgery either through developmental abnormalities or trauma. This project is an extension of our previous work in 3D reconstruction, mesh generation, and immersive visualization. The current VR system, consisting of an SGI Onyx RE2, FakeSpace BOOM and ImmersiveWorkbench, Virtual Technologies CyberGlove and Ascension Technologies tracker, is currently in development and has already been used to visualize defects preoperatively. In the near future it will be used to more fully plan the surgery and compute the projected result to soft tissue structure. This paper presents the work in progress and details the production of a high-performance, collaborative, and networked virtual environment.

  11. KSpaceNavigator

    Energy Science and Technology Software Center (ESTSC)

    2009-08-03

    Intuitive GUI for manipulating microscope stages, allowing to align crystallographic data with stage coordinates and microscope images. Simulates kinematic diffraction patterns and Kikuchi line patterns. Simulated patterns can be displayed as overlay to actually measured data, allowing manual fingerprinting and angular alignment. Crystallographic data is fed to the program in form of CIF (crystallographic information file) files, which are available from many databases and cover virtually all crystal structure ever reported in any journal. Actualmore » goniometer scales can be linearized by lookup tables, program can be used with any microscope goniometer, double tilt and tilt-rotation type.« less

  12. KSpaceNavigator

    SciTech Connect

    Duden, Thomas

    2009-08-03

    Intuitive GUI for manipulating microscope stages, allowing to align crystallographic data with stage coordinates and microscope images. Simulates kinematic diffraction patterns and Kikuchi line patterns. Simulated patterns can be displayed as overlay to actually measured data, allowing manual fingerprinting and angular alignment. Crystallographic data is fed to the program in form of CIF (crystallographic information file) files, which are available from many databases and cover virtually all crystal structure ever reported in any journal. Actual goniometer scales can be linearized by lookup tables, program can be used with any microscope goniometer, double tilt and tilt-rotation type.

  13. Space Shuttle Orbiter descent navigation

    NASA Technical Reports Server (NTRS)

    Montez, M. N.; Madden, M. F.

    1982-01-01

    The entry operational sequence (OPS 3) begins approximately 2 hours prior to the deorbit maneuver and continues through atmospheric entry, terminal area energy management (TAEM), approach and landing, and rollout. During this flight phase, the navigation state vector is estimated by the Space Shuttle Orbiter onboard navigation system. This estimate is computed using a six-element sequential Kalman filter, which blends inertial measurement unit (IMU) delta-velocity data with external navaid data. The external navaids available to the filter are tactical air navigation (TACAN), barometric altimeter, and microwave scan beam landing system (MSBLS). Attention is given to the functional design of the Orbiter navigation system, the descent navigation sensors and measurement processing, predicted Kalman gains, correlation coefficients, and current flights navigation performance.

  14. 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…

  15. 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…

  16. Virtual courseware for geoscience education: Virtual Earthquake and Virtual Dating

    NASA Astrophysics Data System (ADS)

    Novak, Gary A.

    1999-05-01

    Virtual courseware developed for introductory-level, on-line geology labs is an interactive teaching/learning model that has an enormous pedagogical potential for making Web sites places where students learn by doing. Virtual Earthquake and Virtual Dating are modest examples of the `virtual courseware' paradigm. Virtual Earthquake helps students explore the techniques of how an earthquake's epicenter is located and how its Richter magnitude is determined. Virtual Dating models the theory and techniques of the radiometric age determination of rocks and minerals. Virtual courseware applications offer several advantages over traditional floppy disk or CD ROM-based courseware, the most significant being the ease of dissemination. The author's experience with bringing these two virtual applications on-line suggests that there is a need for interactive geology labs on-line and that the approach will be received with enthusiasm by the educational community. The widespread implementation and adoption of virtual courseware can bring meaningful educational content and interactivity for the geosciences that goes beyond multimedia on the World-Wide-Web.

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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…

  3. 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 distant team…

  4. Association of Preoperative Biliary Drainage With Postoperative Outcome Following Pancreaticoduodenectomy

    PubMed Central

    Povoski, Stephen P.; Karpeh, Martin S.; Conlon, Kevin C.; Blumgart, Leslie H.; Brennan, Murray F.

    1999-01-01

    Objective To determine whether preoperative biliary instrumentation and preoperative biliary drainage are associated with increased morbidity and mortality rates after pancreaticoduodenectomy. Summary Background Data Pancreaticoduodenectomy is accompanied by a considerable rate of postoperative complications and potential death. Controversy exists regarding the impact of preoperative biliary instrumentation and preoperative biliary drainage on morbidity and mortality rates after pancreaticoduodenectomy. Methods Two hundred forty consecutive cases of pancreaticoduodenectomy performed between January 1994 and January 1997 were analyzed. Multiple preoperative, intraoperative, and postoperative variables were examined. Pearson chi square analysis or Fisher’s exact test, when appropriate, was used for univariate comparison of all variables. Logistic regression was used for multivariate analysis. Results One hundred seventy-five patients (73%) underwent preoperative biliary instrumentation (endoscopic, percutaneous, or surgical instrumentation). One hundred twenty-six patients (53%) underwent preoperative biliary drainage (endoscopic stents, percutaneous drains/stents, or surgical drainage). The overall postoperative morbidity rate after pancreaticoduodenectomy was 48% (114/240). Infectious complications occurred in 34% (81/240) of patients. Intraabdominal abscess occurred in 14% (33/240) of patients. The postoperative mortality rate was 5% (12/240). Preoperative biliary drainage was determined to be the only statistically significant variable associated with complications (p = 0.025), infectious complications (p = 0.014), intraabdominal abscess (p = 0.022), and postoperative death (p = 0.037). Preoperative biliary instrumentation alone was not associated with complications, infectious complications, intraabdominal abscess, or postoperative death. Conclusions Preoperative biliary drainage, but not preoperative biliary instrumentation alone, is associated with increased

  5. A novel approach for a 2D/3D image registration routine for medical tool navigation in minimally invasive vascular interventions.

    PubMed

    Schwerter, Michael; Lietzmann, Florian; Schad, Lothar R

    2016-09-01

    Minimally invasive interventions are frequently aided by 2D projective image guidance. To facilitate the navigation of medical tools within the patient, information from preoperative 3D images can supplement interventional data. This work describes a novel approach to perform a 3D CT data registration to a single interventional native fluoroscopic frame. The goal of this procedure is to recover and visualize a current 2D interventional tool position in its corresponding 3D dataset. A dedicated routine was developed and tested on a phantom. The 3D position of a guidewire inserted into the phantom could successfully be reconstructed for varying 2D image acquisition geometries. The scope of the routine includes projecting the CT data into the plane of the fluoroscopy. A subsequent registration of the real and virtual projections is performed with an accuracy within the range of 1.16±0.17mm for fixed landmarks. The interventional tool is extracted from the fluoroscopy and matched to the corresponding part of the projected and transformed arterial vasculature. A root mean square error of up to 0.56mm for matched point pairs is reached. The desired 3D view is provided by backprojecting the matched guidewire through the CT array. Due to its potential to reduce patient dose and treatment times, the proposed routine has the capability of reducing patient stress at lower overall treatment costs. PMID:27157275

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Virtual PCR

    SciTech Connect

    Gardner, S N; Clague, D S; Vandersall, J A; Hon, G; Williams, P L

    2006-02-23

    The polymerase chain reaction (PCR) stands among the keystone technologies for analysis of biological sequence data. PCR is used to amplify DNA, to generate many copies from as little as a single template. This is essential, for example, in processing forensic DNA samples, pathogen detection in clinical or biothreat surveillance applications, and medical genotyping for diagnosis and treatment of disease. It is used in virtually every laboratory doing molecular, cellular, genetic, ecologic, forensic, or medical research. Despite its ubiquity, we lack the precise predictive capability that would enable detailed optimization of PCR reaction dynamics. In this LDRD, we proposed to develop Virtual PCR (VPCR) software, a computational method to model the kinetic, thermodynamic, and biological processes of PCR reactions. Given a successful completion, these tools will allow us to predict both the sequences and concentrations of all species that are amplified during PCR. The ability to answer the following questions will allow us both to optimize the PCR process and interpret the PCR results: What products are amplified when sequence mixtures are present, containing multiple, closely related targets and multiplexed primers, which may hybridize with sequence mismatches? What are the effects of time, temperature, and DNA concentrations on the concentrations of products? A better understanding of these issues will improve the design and interpretation of PCR reactions. The status of the VPCR project after 1.5 years of funding is consistent with the goals of the overall project which was scoped for 3 years of funding. At half way through the projected timeline of the project we have an early beta version of the VPCR code. We have begun investigating means to improve the robustness of the code, performed preliminary experiments to test the code and begun drafting manuscripts for publication. Although an experimental protocol for testing the code was developed, the preliminary

  11. Comprehension of Navigation Directions

    NASA Technical Reports Server (NTRS)

    Healy, Alice F.; Schneider, Vivian I.

    2002-01-01

    Subjects were shown navigation instructions varying in length directing them to move in a space represented by grids on a computer screen. They followed the instructions by clicking on the grids in the locations specified. Some subjects repeated back the instructions before following them, some did not, and others repeated back the instructions in reduced form, including only the critical words. The commands in each message were presented simultaneously for half of the subjects and sequentially for the others. For the longest messages, performance was better on the initial commands and worse on the final commands with simultaneous than with sequential presentation. Instruction repetition depressed performance, but reduced repetition removed this disadvantage. Effects of presentation format were attributed to visual scanning strategies. The advantage for reduced repetition was attributable either to enhanced visual scanning or to reduced output interference. A follow-up study with auditory presentation supported the visual scanning explanation.

  12. Automated satellite image navigation

    NASA Astrophysics Data System (ADS)

    Bassett, Robert M.

    1992-12-01

    The automated satellite image navigation method (Auto-Avian) developed and tested by Spaulding (1990) at the Naval Postgraduate School is investigated. The Auto-Avian method replaced the manual procedure of selecting Ground Control Points (GCP's) with an autocorrelation process that utilizes the World Vector Shoreline (WVS) provided by the Defense Mapping Agency (DMA) as a string of GCP's to rectify satellite images. The automatic cross-correlation of binary reference (WVS) and search (image) windows eliminated the subjective error associated with the manual selection of GCP's and produced accuracies comparable to the manual method. The scope of Spaulding's (1990) research was expanded. The worldwide application of the Auto-Avian method was demonstrated in three world regions (eastern North Pacific Ocean, eastern North Atlantic Ocean, and Persian Gulf). Using five case studies, the performance of the Auto-Avian method on 'less than optimum' images (i.e., islands, coastlines affected by lateral distortion and/or cloud cover) was investigated.

  13. Comprehension of Navigation Directions

    NASA Technical Reports Server (NTRS)

    Schneider, Vivian I.; Healy, Alice F.

    2000-01-01

    In an experiment simulating communication between air traffic controllers and pilots, subjects were given navigation instructions varying in length telling them to move in a space represented by grids on a computer screen. The subjects followed the instructions by clicking on the grids in the locations specified. Half of the subjects read the instructions, and half heard them. Half of the subjects in each modality condition repeated back the instructions before following them,and half did not. Performance was worse for the visual than for the auditory modality on the longer messages. Repetition of the instructions generally depressed performance, especially with the longer messages, which required more output than did the shorter messages, and especially with the visual modality, in which phonological recoding from the visual input to the spoken output was necessary. These results are explained in terms of the degrading effects of output interference on memory for instructions.

  14. Sensory bases of navigation.

    PubMed

    Gould, J L

    1998-10-01

    Navigating animals need to know both the bearing of their goal (the 'map' step), and how to determine that direction (the 'compass' step). Compasses are typically arranged in hierarchies, with magnetic backup as a last resort when celestial information is unavailable. Magnetic information is often essential to calibrating celestial cues, though, and repeated recalibration between celestial and magnetic compasses is important in many species. Most magnetic compasses are based on magnetite crystals, but others make use of induction or paramagnetic interactions between short-wavelength light and visual pigments. Though odors may be used in some cases, most if not all long-range maps probably depend on magnetite. Magnetitebased map senses are used to measure only latitude in some species, but provide the distance and direction of the goal in others. PMID:9778524

  15. Dynamic Transportation Navigation

    NASA Astrophysics Data System (ADS)

    Meng, Xiaofeng; Chen, Jidong

    Miniaturization of computing devices, and advances in wireless communication and sensor technology are some of the forces that are propagating computing from the stationary desktop to the mobile outdoors. Some important classes of new applications that will be enabled by this revolutionary development include intelligent traffic management, location-based services, tourist services, mobile electronic commerce, and digital battlefield. Some existing application classes that will benefit from the development include transportation and air traffic control, weather forecasting, emergency response, mobile resource management, and mobile workforce. Location management, i.e., the management of transient location information, is an enabling technology for all these applications. In this chapter, we present the applications of moving objects management and their functionalities, in particular, the application of dynamic traffic navigation, which is a challenge due to the highly variable traffic state and the requirement of fast, on-line computations.

  16. Stardust Navigation Covariance Analysis

    NASA Astrophysics Data System (ADS)

    Menon, Premkumar R.

    2000-01-01

    The Stardust spacecraft was launched on February 7, 1999 aboard a Boeing Delta-II rocket. Mission participants include the National Aeronautics and Space Administration (NASA), the Jet Propulsion Laboratory (JPL), Lockheed Martin Astronautics (LMA) and the University of Washington. The primary objective of the mission is to collect in-situ samples of the coma of comet Wild-2 and return those samples to the Earth for analysis. Mission design and operational navigation for Stardust is performed by the Jet Propulsion Laboratory (JPL). This paper will describe the extensive JPL effort in support of the Stardust pre-launch analysis of the orbit determination component of the mission covariance study. A description of the mission and it's trajectory will be provided first, followed by a discussion of the covariance procedure and models. Predicted accuracy's will be examined as they relate to navigation delivery requirements for specific critical events during the mission. Stardust was launched into a heliocentric trajectory in early 1999. It will perform an Earth Gravity Assist (EGA) on January 15, 2001 to acquire an orbit for the eventual rendezvous with comet Wild-2. The spacecraft will fly through the coma (atmosphere) on the dayside of Wild-2 on January 2, 2004. At that time samples will be obtained using an aerogel collector. After the comet encounter Stardust will return to Earth when the Sample Return Capsule (SRC) will separate and land at the Utah Test Site (UTTR) on January 15, 2006. The spacecraft will however be deflected off into a heliocentric orbit. The mission is divided into three phases for the covariance analysis. They are 1) Launch to EGA, 2) EGA to Wild-2 encounter and 3) Wild-2 encounter to Earth reentry. Orbit determination assumptions for each phase are provided. These include estimated and consider parameters and their associated a-priori uncertainties. Major perturbations to the trajectory include 19 deterministic and statistical maneuvers

  17. Magellan aerobrake navigation

    NASA Technical Reports Server (NTRS)

    Giorgini, Jon; Wong, S. Kuen; You, Tung-Han; Chadbourne, Pam; Lim, Lily

    1995-01-01

    The Magellan spacecraft has been aerobraked into a 197 x 541 km near-circular orbit around Venus from which it is conducting a high-resolution gravity mapping mission. This was the first interplanetary aerobrake maneuver and involved flying the spacecraft through the upper reaches of the Venusian atmosphere 730 times over a 70 day period. Round-trip light-time varied from 9.57 to 18.83 minutes during this period. Navigation for this dynamic phase of the Magellan mission was planned and executed in the face of budget-driven down-sizing with all spacecraft safe modes disabled and a flight-team one-third the size of comparable interplanetary missions. Successful execution of this manuever using spacecraft hardware not designed to operate in a planetary atmosphere, demonstrated a practical cost-saving technique for both large and small future interplanetary missions.

  18. Preoperative breast marking in reduction mammaplasty.

    PubMed

    Gasperoni, C; Salgarello, M

    1987-10-01

    A simple method of preoperative marking for reduction mammaplasty is described. This method may be used in macromastias when the technique chosen implies a postoperative scar with the shape of an inverted T. The marking sequence follows standard steps, but the drawing is always different because it is a consequence of the shape of the breast. This marking method reduces the chance of making mistakes due to excessive personal evaluations or to the use of standard drawing patterns that may be not suitable for all breast shapes. PMID:3688776

  19. Preoperational test report, recirculation ventilation systems

    SciTech Connect

    Clifton, F.T.

    1997-11-11

    This represents a preoperational test report for Recirculation Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102 and supports the ability to exhaust air from each tank. Each system consists of a valved piping loop, a fan, condenser, and moisture separator; equipment is located inside each respective tank farm in its own hardened building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  20. [Intestinal stoma: preoperative and postoperative management].

    PubMed

    Soravia, C; Beyeler, S; Lataillade, L

    2005-03-01

    The aim of this review is to present the management and indications of intestinal stomas. A stoma induces a body image alteration with important familial and social consequences. A preoperative visit to the stoma nurse prevents technical and/or psychological complications. Stoma nurses, surgeons and general practionners work together to help the patient in his/her new life. New stoma devices have also contributed to improve quality of life. Social and sexual activity can be maintain despite intestinal stoma with appropriate education. PMID:15828375

  1. Preoperative carbohydrate nutrition reduces postoperative nausea and vomiting compared to preoperative fasting

    PubMed Central

    Yilmaz, Neslihan; Çekmen, Nedim; Bilgin, Ferruh; Erten, Ela; Özhan, Mehmet Özhan; Coşar, Ahmet

    2013-01-01

    Background: The aim of this prospective, randomized, single-blinded study was to compare the effects of a carbohydrate drink 400 mL given 2 h before the surgery with preoperative overnight fasting on the gastric pH and residual volume, postoperative nausea and vomiting (PONV) and antiemetic consumption in patients undergoing laparoscopic cholecystectomy. Materials And Methods: Forty American Society of Anesthesiologists physical status I-II patients who underwent elective laparoscopic cholecystectomy. Randomized, prospective, controlled study, Gulhane Medical Faculty and Guven Hospital Department of Anesthesiology and Reanimation. Patients were randomly assigned into two groups: Pre-operative carbohydrate drink group (group C, n = 20) and preoperative fasting group (group F, n = 20). Group C was given a 400 mL carbohydrate drink 2 h before to the surgery. The patients of group F were fasted 8 h before the surgery. Both groups were operated under general anesthesia with volatile anesthetics. Results: Hemodynamic parameters, demographic data, gastric acidity and residual volumes were similar for both groups. No complications were observed. PONV and antiemetic consumption was lower in group C compared to group F (P = 0.001). Patient's satisfaction was higher in group C (P < 0.001). Conclusion: This study showed that pre-operative carbohydrate drink may be used safely and also improves patient's satisfaction and comfort in patients undergoing laparoscopic cholecystectomy. PMID:24497851

  2. 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

  3. 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…

  4. The Reality of Virtual Tours in ARL Libraries.

    ERIC Educational Resources Information Center

    Mach, Michelle; Oling, Lori

    2002-01-01

    One hundred twenty-three Association of Research Libraries (ARL) Web sites were examined for the presence of a virtual tour. Over half offered at least one. Each main or undergraduate library tour was reviewed for the use of standard Web conventions, features, content and navigation using a checklist of 32 items. Emerging trends and…

  5. Navigation by environmental geometry: the use of zebrafish as a model.

    PubMed

    Lee, Sang Ah; Vallortigara, Giorgio; Flore, Michele; Spelke, Elizabeth S; Sovrano, Valeria A

    2013-10-01

    Sensitivity to environmental shape in spatial navigation has been found, at both behavioural and neural levels, in virtually every species tested, starting early in development. Moreover, evidence that genetic deletions can cause selective deficits in such navigation behaviours suggests a genetic basis to navigation by environmental geometry. Nevertheless, the geometric computations underlying navigation have not been specified in any species. The present study teases apart the geometric components within the traditionally used rectangular enclosure and finds that zebrafish selectively represent distance and directional relationships between extended boundary surfaces. Similar behavioural results in geometric navigation tasks with human children provide prima facie evidence for similar underlying cognitive computations and open new doors for probing the genetic foundations that give rise to these computations. PMID:23788708

  6. Air Navigation. Aerospace Education II.

    ERIC Educational Resources Information Center

    Gromling, F. C.; Mackin, T. E.

    This book, which can be used only in the Air Force ROTC program, elucidates ideas about air navigation techniques. The book is divided into two main parts. The first part describes the earth's surface and different components of navigation. A chapter on charts provides ideas about different kinds of charts and a variety of symbols used in…

  7. 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…

  8. 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…

  9. Preoperative Imaging for Clinical Staging Prior to Radical Cystectomy.

    PubMed

    Hugen, Cory M; Duddalwar, Vinay; Daneshmand, Siamak

    2016-09-01

    The importance of patient selection for quality outcomes following radical cystectomy is critical. Clinical staging is one of the key elements necessary for patient selection, and staging relies on accurate preoperative imaging. Many imaging modalities are available and have been utilized for preoperative staging with published operating characteristics. In this update, we review recently published literature for advances in preoperative imaging prior to radical cystectomy. PMID:27432379

  10. Preoperative Preparation and Anesthesia for Trabeculectomy

    PubMed Central

    2016-01-01

    ABSTRACT Preoperative preparation should improve the likelihood of successful trabeculectomy surgery. The team can reconsider the appropriateness of the proposed surgery, and steps can be taken to maximize the chance of a good outcome. For example, adjustments to anti-hypertensive or anti-coagulant medications may be made, and topical ocular medications adjusted. Choice of anesthesia technique is of particular relevance to the trabeculectomy patient. Some anesthesia techniques are more likely to have serious complications, and glaucoma patients may be at higher risk of some sight-threatening complications, because the optic nerve is already damaged and vulnerable. Posterior placement of local anesthesia (retrobulbar, peribulbar, posterior sub-Tenon’s techniques) could potentially damage the optic nerve, and thereby cause “wipe-out” of vision. Anesthesia technique may influence the likelihood of vitreous bulge and surgical difficulty. Regarding long-term control of intraocular pressure, there is no good evidence to indicate that any particular anesthesia technique is better than another. There is little high-quality evidence on this topic. The author’s preferred technique for trabeculectomy is subconjunctival-intracameral anesthesia without sedation. How to cite this article: Eke T. Preoperative Preparation and Anesthesia for Trabeculectomy. J Curr Glaucoma Pract 2016; 10(1):21-35. PMID:27231416

  11. Preoperative transarterial Embolisation in bone tumors

    PubMed Central

    Gupta, Pankaj; Gamanagatti, Shivanand

    2012-01-01

    Bone tumors include a variety of lesions, both primary and metastatic. The treatment modalities for bone tumors vary with the individual lesion, but in general surgical excision is the treatment of choice with other adjunctive therapies. However, surgery for many bone tumors is complex due to several factors including tumor bulk, vascularity, vicinity to vital structures and potentially inaccessible location of the lesion. Transarterial Embolisation (TAE) is one of the important adjuvant treatment modalities and in some cases it may be the primary and curative treatment. Preoperative TAE has proved to be effective in both primary and metastatic bone tumors. It reduces tumor vascularity and intraoperative blood loss, the need for blood transfusion and associated complications, allows better definition of tissue planes at surgery affording more complete excision, and hence reduced recurrence. Preoperative chemoEmbolisation has also been shown to increase the sensitivity of some tumors to subsequent chemotherapy and radiotherapy. There are several techniques and embolic agents available for this purpose, but the ultimate aim is to achieve tumor devascularization. In this review, we discuss the techniques including the choice of embolic agent, application to individual lesions and potential complications. PMID:22761978

  12. [Preoperative oral hydration for pregnant women].

    PubMed

    Okutomi, Toshiyuki; Kato, Rie

    2011-07-01

    Preoperative oral hydration is an important component of "enhanced recovery after surgery" strategies. This was originally developed for patients undergoing colon surgery. The Obstetric Anesthesia Practice Guideline issued by American Society of Anesthesiologists states that intake of minimum amount of clear fluid 2 hours prior to surgery may be safe. However, anesthesiologists have to consider physiological changes that parturients undergo during pregnancy, such as increased risk of aspiration and impaired glucose tolerance. We also have to consider the potential effect of glucose loading on neonates. Mothers are more likely to develop ketosis by glucose loading. It also stimulates insulin release in the fetus, which can result in neonatal hypoglycemia. In addition, sodium overloading may deteriorate intra-vascular dehydration and cause lung edema to mothers. On the other hand, oral hydration can alleviate a sense of thirst and increase maternal satisfaction. Our data showed that maternal urinal ketone body at delivery tended to decrease with oral hydration during labor. Moreover, some articles suggest that oral hydration may improve utero-placental perfusion. Therefore, we have to balance risks and benefits of oral hydration in parturients. Further investigations are needed among this specific subgroup of patients in order to establish the safe application of preoperative oral hydration. PMID:21800658

  13. [Preoperative chemoradiotherapy for resectable lower rectal cancer].

    PubMed

    Takase, Shiro; Kamigaki, Takashi; Yamashita, Kimihiro; Nakamura, Tetsu; Nishimura, Hideki; Sasaki, Ryohei

    2009-11-01

    To suppress local recurrence and preserve sphincter function, we performed preoperative chemoradiotherapy( CRT) of rectal cancer. Sixteen patients with lower advanced rectal cancer received tegafur/uracil/calcium folinate+RT followed by curative resection with lateral lymph node dissection 2-8 weeks later. The male/female ratio was found to be 11:5 (41-75 years old) and the CRT was feasible for all patients. There were 11-PR and 5-SD according to RECIST criteria, and lower isotope accumulation was observed for all primary tumors in FDG-PET study. After CRT, all patients received R0 curative resection (11 APR, 2 LAR, 1 Hartmann and 1 ISR). On pathological study, 3 patients showed complete response. Surgical complications including pelvic infection, delayed a wound healing and deep venous thrombosis, etc. In conclusion, preoperative CRT of advanced rectal cancer could potentially be useful for local control and sphincter saving, however, it is necessary to manage specific surgical complications due to radiation. PMID:20037306

  14. Bevacizumab with preoperative chemotherapy versus preoperative chemotherapy alone for colorectal cancer liver metastases

    PubMed Central

    Lu, Zhen-Hai; Peng, Jian-Hong; Wang, Fu-Long; Yuan, Yun-Fei; Jiang, Wu; Li, Yu-Hong; Wu, Xiao-Jun; Chen, Gong; Ding, Pei-Rong; Li, Li-Ren; Kong, Ling-Heng; Lin, Jun-Zhong; Zhang, Rong-Xin; Wan, De-Sen; Pan, Zhi-Zhong

    2016-01-01

    Abstract This study aimed to assess the efficacy and safety of bevacizumab plus preoperative chemotherapy as first-line treatment for liver-only metastatic colorectal cancer in Chinese patients compared with those of preoperative chemotherapy alone. Patients with histologically confirmed liver-only metastatic colorectal cancer were sequentially reviewed, and received either preoperative chemotherapy plus bevacizumab (bevacizumab group, n = 32) or preoperative chemotherapy alone (chemotherapy group, n = 57). Progression-free survival, response rate, liver resection rate, conversion rate, and safety were analyzed. With median follow-up of 28.7 months, progression-free survival was 10.9 months (95% confidence interval: 8.7–13.1 months) in bevacizumab group and 9.9 months (95% confidence interval: 6.8–13.1 months) in chemotherapy group (P = 0.472). Response rates were 59.4% in bevacizumab group and 38.6% in chemotherapy group (P = 0.059). Overall liver resection (R0, R1, and R2) rate was 68.8% in bevacizumab group and 54.4% in chemotherapy group (P = 0.185). Conversion rate was 51.9% in bevacizumab group and 40.4% in chemotherapy group (P = 0.341). No postoperative complication was observed in all patients. Bevacizumab plus preoperative chemotherapy as first-line treatment for liver-only metastatic colorectal cancer tends to achieve better clinical benefit with controllable safety in Chinese patients. PMID:27583930

  15. 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.

  16. Jejunioleal Bypass Procedures in Morbid Obesity: Preoperative Psychological Findings

    ERIC Educational Resources Information Center

    Webb, Warren W.; And Others

    1976-01-01

    Seventy patients who averaged 155 percent overweight and requested jejunioleal bypass surgery as a treatment intervention for morbid obesity were studied preoperatively for prominent psychological characteristics. (Author)

  17. 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. PMID:24830787

  18. 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.

  19. Overview of Virtual Observatory Tools

    NASA Astrophysics Data System (ADS)

    Allen, M. G.

    2009-07-01

    I provide a brief introduction and tour of selected Virtual Observatory tools to highlight some of the core functions provided by the VO, and the way that astronomers may use the tools and services for doing science. VO tools provide advanced functions for searching and using images, catalogues and spectra that have been made available in the VO. The tools may work together by providing efficient and innovative browsing and analysis of data, and I also describe how many VO services may be accessed by a scripting or command line environment. Early science usage of the VO provides important feedback on the development of the system, and I show how VO portals try to address early user comments about the navigation and use of the VO.

  20. 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.

  1. Virtual Rover on Its Own

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows a screenshot from the software used by engineers to roll the Mars Exploration Rover Opportunity off its lander and onto martian soil. Engineers received confirmation that Opportunity's six wheels had touched ground at 3:01 a.m. PST, January 31, 2004, on the seventh martian day, or sol, of the mission. The software simulates the rover's movements, helping to plot a safe course. The virtual 3-D world around the rover is built from images taken by Opportunity's stereo navigation cameras. Regions for which the rover has not yet acquired 3-D data are represented in beige. The rover is approximately 1 meter (3 feet) in front of the lander, facing north.

  2. 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. PMID:16392719

  3. A projective surgical navigation system for cancer resection

    NASA Astrophysics Data System (ADS)

    Gan, Qi; Shao, Pengfei; Wang, Dong; Ye, Jian; Zhang, Zeshu; Wang, Xinrui; Xu, Ronald

    2016-03-01

    Near infrared (NIR) fluorescence imaging technique can provide precise and real-time information about tumor location during a cancer resection surgery. However, many intraoperative fluorescence imaging systems are based on wearable devices or stand-alone displays, leading to distraction of the surgeons and suboptimal outcome. To overcome these limitations, we design a projective fluorescence imaging system for surgical navigation. The system consists of a LED excitation light source, a monochromatic CCD camera, a host computer, a mini projector and a CMOS camera. A software program is written by C++ to call OpenCV functions for calibrating and correcting fluorescence images captured by the CCD camera upon excitation illumination of the LED source. The images are projected back to the surgical field by the mini projector. Imaging performance of this projective navigation system is characterized in a tumor simulating phantom. Image-guided surgical resection is demonstrated in an ex-vivo chicken tissue model. In all the experiments, the projected images by the projector match well with the locations of fluorescence emission. Our experimental results indicate that the proposed projective navigation system can be a powerful tool for pre-operative surgical planning, intraoperative surgical guidance, and postoperative assessment of surgical outcome. We have integrated the optoelectronic elements into a compact and miniaturized system in preparation for further clinical validation.

  4. The navigation of homing pigeons: Do they use sun Navigation?

    NASA Technical Reports Server (NTRS)

    Walcott, C.

    1972-01-01

    Experiments to determine the dependence of homing pigeons on the sun as a navigational cue are discussed. Various methods were employed to interrupt the circadian rhythms of the pigeons prior to release. It was determined that the sun may serve as a compass, but that topographic features are more important for navigation. The effects of a magnetic field produced by electric equipment carried by the bird were also investigated. It was concluded that magnetic fields may have a small effect on the homing ability. The exact nature of the homing pigeon's navigational ability is still unknown after years of elaborate experimentation.

  5. The navigation toolkit

    NASA Technical Reports Server (NTRS)

    Rich, William F.; Strom, Stephen W.

    1994-01-01

    This report summarizes the experience of the authors in managing, designing, and implementing an object-oriented applications framework for orbital navigation analysis for the Flight Design and Dynamics Department of the Rockwell Space Operations Company in Houston, in support of the Mission Operations Directorate of NASA's Johnson Space Center. The 8 person year project spanned 1.5 years and produced 30,000 lines of C++ code, replacing 150,000 lines of Fortran/C. We believe that our experience is important because it represents a 'second project' experience and generated real production-quality code - it was not a pilot. The project successfully demonstrated the use of 'continuous development' or rapid prototyping techniques. Use of formal methods and executable models contributed to the quality of the code. Keys to the success of the project were a strong architectural vision and highly skilled workers. This report focuses on process and methodology, and not on a detailed design description of the product. But the true importance of the object-oriented paradigm is its liberation of the developer to focus on the problem rather than the means used to solve the problem.

  6. Titan Probe navigation analysis

    NASA Technical Reports Server (NTRS)

    Vijayaraghavan, A.; Wood, L. J.

    1986-01-01

    In the proposed Cassini mission, a combined Saturn Orbiter/Titan Probe spacecraft will be launched from the Space Shuttle to arrive at Saturn around 2002, by means of a delta-VEGA trajectory. After Saturn-orbit insertion and a pericrone raise maneuver, the probe will be released to enter the Titan atmosphere and impact onto its surface. During its descent phase and impact onto Titan, the probe will maintain radio contact with the orbiter. Since the Titan-probe experimental phase lasts for only about four hours, probe-orbiter geometry and probe-delivery accuracy are critical to successful completion of this part of the mission. From a preliminary navigation analysis for probe delivery accuracy, it seems feasible to deliver the probe within 50 km (1-sigma value) of the desired aim-point in the Titan B-plane. The covariance study, however, clearly indicates the need for optical data, in addition to radio metric data. A Monte Carlo study indicates that a Delta-V capability of 98 m/sec for trajectory correction maneuvers will be sufficient to cover 99 percent of all contingencies during the segment from Saturn-orbit insertion to Titan-probe release.

  7. 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. PMID:26737323

  8. The feasibility of real-time bladder mapping using a stereotactic navigational system

    NASA Astrophysics Data System (ADS)

    Draga, Ronald O. P.; Noordmans, Herke Jan; Lock, M. T. W. Tycho; Grimbergen, Matthijs C. M.; Bosch, J. L. H. Ruud

    2010-02-01

    Stereotactic navigational devices have been implemented in neurosurgery, orthopedics and ear-nose-throat to improve surgical accuracy. However, the feasibility of navigating inside the bladder has not yet been investigated. Occasionally, transurethral resections of bladder tumors (TURBTs) are impeded by bleeding and cloudiness inside the bladder and, consequently, the bladder lesions are not found back easily. In addition, small bladder lesions are often concealed when viewed with the camera some distance away from the bladder wall due to low contrast differences. The aim of the study is to investigate the feasibility of real-time bladder mapping using the Medtronic Stealthstation system, without the use of pre-operative images. Seven patients scheduled for a TURBT were included in the study. During the TURBT procedure, the spatial coordinates of the bladder lesions were recorded two times independently, after filling the bladder with a fixed volume of 390 ml. The distance between the spatial coordinates of two consecutive measurements, in millimeters, was calculated. We found that bladder lesions can be found back using the navigational system with an accuracy of less than 12 mm. Real-time bladder navigation is feasible without the necessity of pre-operative images or calibration. If the coordinates are directly superimposed on the video image this could facilitate the retrieval of bladder lesions during TURBT. This system could reduce the stress for the surgeon and decrease the operating time.

  9. Lunar Navigation Architecture Design Considerations

    NASA Technical Reports Server (NTRS)

    D'Souza, Christopher; Getchius, Joel; Holt, Greg; Moreau, Michael

    2009-01-01

    The NASA Constellation Program is aiming to establish a long-term presence on the lunar surface. The Constellation elements (Orion, Altair, Earth Departure Stage, and Ares launch vehicles) will require a lunar navigation architecture for navigation state updates during lunar-class missions. Orion in particular has baselined earth-based ground direct tracking as the primary source for much of its absolute navigation needs. However, due to the uncertainty in the lunar navigation architecture, the Orion program has had to make certain assumptions on the capabilities of such architectures in order to adequately scale the vehicle design trade space. The following paper outlines lunar navigation requirements, the Orion program assumptions, and the impacts of these assumptions to the lunar navigation architecture design. The selection of potential sites was based upon geometric baselines, logistical feasibility, redundancy, and abort support capability. Simulated navigation covariances mapped to entry interface flightpath- angle uncertainties were used to evaluate knowledge errors. A minimum ground station architecture was identified consisting of Goldstone, Madrid, Canberra, Santiago, Hartebeeshoek, Dongora, Hawaii, Guam, and Ascension Island (or the geometric equivalent).

  10. 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 §...

  11. 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 §...

  12. 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 §...

  13. 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 §...

  14. 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 §...

  15. Navigable networks as Nash equilibria of navigation games

    NASA Astrophysics Data System (ADS)

    Gulyás, András; Bíró, József J.; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

    2015-07-01

    Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network.

  16. Navigable networks as Nash equilibria of navigation games.

    PubMed

    Gulyás, András; Bíró, József J; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

    2015-01-01

    Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network. PMID:26138277

  17. Navigable networks as Nash equilibria of navigation games

    PubMed Central

    Gulyás, András; Bíró, József J.; Kőrösi, Attila; Rétvári, Gábor; Krioukov, Dmitri

    2015-01-01

    Common sense suggests that networks are not random mazes of purposeless connections, but that these connections are organized so that networks can perform their functions well. One function common to many networks is targeted transport or navigation. Here, using game theory, we show that minimalistic networks designed to maximize the navigation efficiency at minimal cost share basic structural properties with real networks. These idealistic networks are Nash equilibria of a network construction game whose purpose is to find an optimal trade-off between the network cost and navigability. We show that these skeletons are present in the Internet, metabolic, English word, US airport, Hungarian road networks, and in a structural network of the human brain. The knowledge of these skeletons allows one to identify the minimal number of edges, by altering which one can efficiently improve or paralyse navigation in the network. PMID:26138277

  18. Virtual Reality as Metaphor.

    ERIC Educational Resources Information Center

    Gozzi, Raymond, Jr.

    1996-01-01

    Suggests that virtual reality technology has become popular because it is a miniaturization, a model, of something that already exists. Compares virtual reality to the news media, which centers on the gory, the sensational, and the distorted. (PA)

  19. Intelligent Virtual Station (IVS)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Intelligent Virtual Station (IVS) is enabling the integration of design, training, and operations capabilities into an intelligent virtual station for the International Space Station (ISS). A viewgraph of the IVS Remote Server is presented.

  20. Preoperational test report, recirculation condenser cooling systems

    SciTech Connect

    Clifton, F.T.

    1997-11-04

    This represents a preoperational test report for Recirculation Condenser Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The four system provide condenser cooling water for vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102. Each system consists of a valved piping loop, a pair of redundant recirculation pumps, a closed-loop evaporative cooling tower, and supporting instrumentation; equipment is located outside the farm on concrete slabs. Piping is routed to the each ventilation condenser inside the farm via below-grade concrete trenches. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

  1. Pre-operative optimisation of lung function

    PubMed Central

    Azhar, Naheed

    2015-01-01

    The anaesthetic management of patients with pre-existing pulmonary disease is a challenging task. It is associated with increased morbidity in the form of post-operative pulmonary complications. Pre-operative optimisation of lung function helps in reducing these complications. Patients are advised to stop smoking for a period of 4–6 weeks. This reduces airway reactivity, improves mucociliary function and decreases carboxy-haemoglobin. The widely used incentive spirometry may be useful only when combined with other respiratory muscle exercises. Volume-based inspiratory devices have the best results. Pharmacotherapy of asthma and chronic obstructive pulmonary disease must be optimised before considering the patient for elective surgery. Beta 2 agonists, inhaled corticosteroids and systemic corticosteroids, are the main drugs used for this and several drugs play an adjunctive role in medical therapy. A graded approach has been suggested to manage these patients for elective surgery with an aim to achieve optimal pulmonary function. PMID:26556913

  2. Pancoast tumors: characteristics and preoperative assessment

    PubMed Central

    Panagopoulos, Nikolaos; Leivaditis, Vasilios; Koletsis, Efstratios; Prokakis, Christos; Alexopoulos, Panagiotis; Baltayiannis, Nikolaos; Hatzimichalis, Antonios; Tsakiridis, Kosmas; Zarogoulidis, Konstantinos; Katsikogiannis, Nikolaos; Kougioumtzi, Ioanna; Machairiotis, Nikolaos; Tsiouda, Theodora; Kesisis, Georgios; Siminelakis, Stavros; Madesis, Athanasios; Dougenis, Dimitrios

    2014-01-01

    Superior sulcus tumors (SSTs), or as otherwise known Pancoast tumors, make up a clinically unique and challenging subset of non-small cell carcinoma of the lung (NSCLC). Although the outcome of patients with this disease has traditionally been poor, recent developments have contributed to a significant improvement in prognosis of SST patients. The combination of severe and unrelenting shoulder and arm pain along the distribution of the eighth cervical and first and second thoracic nerve trunks, Horner’s syndrome (ptosis, miosis, and anhidrosis) and atrophy of the intrinsic hand muscles comprises a clinical entity named as “Pancoast-Tobias syndrome”. Apart NSCLC, other lesions may, although less frequently, result in Pancoast syndrome. In the current review we will present the main characteristics of the disease and focus on the preoperative assessment. PMID:24672686

  3. Experiment D009: Simple navigation

    NASA Technical Reports Server (NTRS)

    Silva, R. M.; Jorris, T. R.; Vallerie, E. M., III

    1971-01-01

    Space position-fixing techniques have been investigated by collecting data on the observable phenomena of space flight that could be used to solve the problem of autonomous navigation by the use of optical data and manual computations to calculate the position of a spacecraft. After completion of the developmental and test phases, the product of the experiment would be a manual-optical technique of orbital space navigation that could be used as a backup to onboard and ground-based spacecraft-navigation systems.

  4. NASA tracking ship navigation systems

    NASA Technical Reports Server (NTRS)

    Mckenna, J. J.

    1976-01-01

    The ship position and attitude measurement system that was installed aboard the tracking ship Vanguard is described. An overview of the entire system is given along with a description of how precise time and frequency is utilized. The instrumentation is broken down into its basic components. Particular emphasis is given to the inertial navigation system. Each navigation system used, a mariner star tracker, navigation satellite system, Loran C and OMEGA in conjunction with the inertial system is described. The accuracy of each system is compared along with their limitations.

  5. Navigation/Prop Software Suite

    NASA Technical Reports Server (NTRS)

    Bruchmiller, Tomas; Tran, Sanh; Lee, Mathew; Bucker, Scott; Bupane, Catherine; Bennett, Charles; Cantu, Sergio; Kwong, Ping; Propst, Carolyn

    2012-01-01

    Navigation (Nav)/Prop software is used to support shuttle mission analysis, production, and some operations tasks. The Nav/Prop suite containing configuration items (CIs) resides on IPS/Linux workstations. It features lifecycle documents, and data files used for shuttle navigation and propellant analysis for all flight segments. This suite also includes trajectory server, archive server, and RAT software residing on MCC/Linux workstations. Navigation/Prop represents tool versions established during or after IPS Equipment Rehost-3 or after the MCC Rehost.

  6. Real Students and Virtual Field Trips

    NASA Astrophysics Data System (ADS)

    de Paor, D. G.; Whitmeyer, S. J.; Bailey, J. E.; Schott, R. C.; Treves, R.; Scientific Team Of Www. Digitalplanet. Org

    2010-12-01

    Field trips have always been one of the major attractions of geoscience education, distinguishing courses in geology, geography, oceanography, etc., from laboratory-bound sciences such as nuclear physics or biochemistry. However, traditional field trips have been limited to regions with educationally useful exposures and to student populations with the necessary free time and financial resources. Two-year or commuter colleges serving worker-students cannot realistically insist on completion of field assignments and even well-endowed universities cannot take students to more than a handful of the best available field localities. Many instructors have attempted to bring the field into the classroom with the aid of technology. So-called Virtual Field Trips (VFTs) cannot replace the real experience for those that experience it but they are much better than nothing at all. We have been working to create transformative improvements in VFTs using four concepts: (i) self-drive virtual vehicles that students use to navigate the virtual globe under their own control; (ii) GigaPan outcrops that reveal successively more details views of key locations; (iii) virtual specimens scanned from real rocks, minerals, and fossils; and (iv) embedded assessment via logging of student actions. Students are represented by avatars of their own choosing and travel either together in a virtual field vehicle, or separately. When they approach virtual outcrops, virtual specimens become collectable and can be examined using Javascript controls that change magnification and orientation. These instructional resources are being made available via a new server under the domain name www.DigitalPlanet.org. The server will log student progress and provide immediate feedback. We aim to disseminate these resources widely and welcome feedback from instructors and students.

  7. Pre-operative nutrition and carbohydrate loading.

    PubMed

    Kratzing, Caroline

    2011-08-01

    An optimal nutritional state is an important consideration in providing successful operative outcomes. Unfortunately, many aspects of surgery are not constructive to providing this. In addition, the metabolic and immune response to injury induces a catabolic state and insulin resistance, a known risk factor of post-operative complications. Aggressive insulin therapy post-operatively has been shown to reduce morbidity and mortality but similar results can be achieved when insulin resistance is lessened by the use of pre-operative carbohydrate loading. Consuming carbohydrate-containing drinks up to 2 h before surgery has been found to be an effective way to attenuate insulin resistance, minimise protein losses, reduce hospital stays and improve patient comfort without adversely affecting gastric emptying. Enhanced recovery programmes have employed carbohydrate loading as one of several strategies aimed at reducing post-operative stress and improving the recovery process. Studies examining the benefits of these programmes have demonstrated significantly shorter post-operative hospital stays, faster return to normal functions and lower occurrences of surgical complications. As a consequence of the favourable evidence they are now being implemented in many surgical units. Further benefit to post-operative recovery may be found with the use of immune-enhancing diets, i.e. supplementation with n-3 fatty acids, arginine, glutamine and/or nucleotides. These have the potential to boost the immune system, improve wound healing and reduce inflammatory markers. Research exploring the benefits of immunonutrition and solidifying the use of carbohydrate loading is ongoing; however, there is strong evidence to link good pre-operative nutrition and improved surgical outcomes. PMID:21781358

  8. Background parenchymal enhancement in preoperative breast MRI

    PubMed Central

    Kohara, Satoko; Ishigaki, Satoko; Satake, Hiroko; Kawamura, Akiko; Kawai, Hisashi; Kikumori, Toyone; Naganawa, Shinji

    2015-01-01

    ABSTRACT We aimed to assess the influence of background parenchymal enhancement (BPE) on surgical planning performed using preoperative MRI for breast cancer evaluation. Between January 2009 and December 2010, 91 newly diagnosed breast cancer patients (mean age, 55.5 years; range, 30−88 years) who underwent preoperative bilateral breast MRI followed by planned breast conservation therapy were retrospectively enrolled. MRI was performed to assess the tumor extent in addition to mammography and breast ultrasonography. BPE in the contralateral normal breast MRI at the early dynamic phase was visually classified as follows: minimal (n=49), mild (n=27), moderate (n=7), and marked (n=8). The correlations between the BPE grade and age, menopausal status, index tumor size, changes in surgical management based on MRI results, positive predictive value (PPV) of MRI, and surgical margins were assessed. Patients in the strong BPE groups were significantly younger (p=0.002) and generally premenopausal (p<0.001). Surgical treatment was not changed in 67 cases (73.6%), while extended excision and mastectomy were performed in 12 cases (13.2%), each based on additional lesions on MRI. Six of 79 (7.6%) patients who underwent breast conservation therapy had tumor-positive resection margins. In cases where surgical management was changed, the PPV for MRI-detected foci was high in the minimal (91.7%) and mild groups (66.7%), and 0% in the moderate and marked groups (p=0.002). Strong BPE causes false-positive MRI findings and may lead to overly extensive surgery, whereas MRI may be beneficial in select patients with weak BPE. PMID:26412883

  9. Bore hole navigator

    SciTech Connect

    Hoffman, G.J.

    1987-09-29

    A bore hole navigator is described comprising a two axis platform for lowering down a bore hole on a cable with its longitudinal axis parallel to the local bore hole direction. The two axis platform has an outer gimbal, bearing supported on the outer gimbal axis for rotation about the longitudinal axis of the platform, and an inner gimbal axis orthogonal the the outer gimbal axis. The inner gimbal axis has multiple axis segments spaced along the longitudinal axis of the platform and each bearing supported on the outer gimbal. The inner gimbal axis segment has a two axis gyro mounted thereon with its spin axis orthogonal to the respective inner gimbal axis segment, a first gyro sensitive axis parallel to the respective inner gimbal axis segment and a second gyro sensitive axis orthogonal to the spin axis. The second inner gimbal axis segment has a pitch torquer thereon operative to provide a controllable torque about the respective inner gimbal axis segment. The third inner gimbal axis segment has a pitch resolver thereon operative to measure rotation of the respective inner gimbal axis segment with respect to the outer gimbal. The first, second and third inner gimbal axis segments are coupled to rotate together. The outer gimbal has a yaw torquer thereon to provide a controllable torque about the outer gimbal axis, and a yaw resolver thereon to measure rotation of the outer gimbal about the outer gimbal axis. The outer gimbal also has a single axis accelerometer therein having its sensitive axis orthogonal to the outer gimbal axis and the inner gimbal axis segments.

  10. Navigating "Assisted Dying".

    PubMed

    Schipper, Harvey

    2016-02-01

    Carter is a bellwether decision, an adjudication on a narrow point of law whose implications are vast across society, and whose impact may not be realized for years. Coupled with Quebec's Act Respecting End-of-life Care it has sharply changed the legal landscape with respect to actively ending a person's life. "Medically assisted dying" will be permitted under circumstances, and through processes, which have yet to be operationally defined. This decision carries with it moral assumptions, which mean that it will be difficult to reach a unifying consensus. For some, the decision and Act reflect a modern acknowledgement of individual autonomy. For others, allowing such acts is morally unspeakable. Having opened the Pandora's Box, the question becomes one of navigating a tolerable societal path. I believe it is possible to achieve a workable solution based on the core principle that "medically assisted dying" should be a very rarely employed last option, subject to transparent ongoing review, specifically as to why it was deemed necessary. My analysis is based on 1. The societal conditions in which have fostered demand for "assisted dying", 2. Actions in other jurisdictions, 3. Carter and Quebec Bill 52, 4. Political considerations, 5. Current medical practice. Leading to a series of recommendations regarding. 1. Legislation and regulation, 2. The role of professional regulatory agencies, 3. Medical professions education and practice, 4. Public education, 5. Health care delivery and palliative care. Given the burden of public opinion, and the legal steps already taken, a process for assisted-dying is required. However, those legal and regulatory steps should only be considered a necessary and defensive first step in a two stage process. The larger goal, the second step, is to drive the improvement of care, and thus minimize assisted-dying. PMID:27169205

  11. Wellborne inertial navigation system

    SciTech Connect

    Kelsey, J.R.

    1983-01-01

    A phototype wireline tool which includes a downhole inertial platform and a surface computer to spatially map a well is described. The hardware consists of a single-gimbaled inertial platform with accelerometers and gyros to obtain three-axis motion information. The gyroscope and accelerometer outputs are transmitted to a computer at the surface which calculates probe attitude relative to north, east, and vertical. Double integration of the accelerometer data provides the position information. A conventional 7-conductor wireline is used for the system data transmission. System accuracy is enhanced by advances made in the computer software which processes the data received from the tool. The software uses statistical sampling estimation to obtain optimal estimates of the system errors. Measurement errors are determined by periodically stopping the tool during the logging procedure and observing the indicated velocity measurements. This procedure, known as Kalman filtering, results in increased accuracy of the data. Present mapping systems have an X-Y-Z location accuracy of +- 100 to +- 200 feet for a typical well depth of 10,000 feet. Test results show that the new system is accurate to about +- 1 foot per 1000 feet of well depth. Unlike conventional systems, the inertial navigator does not require any sort of projection of the cable length (which may not be accurately known). Also this system provides continuous data throughout the wellbore and logging speeds on the order of 10 ft/sec appear possible. The hardware and software associated with this mapping system are described and the recent field test results are reported.

  12. Guided exploration in virtual environments

    NASA Astrophysics Data System (ADS)

    Beckhaus, Steffi; Eckel, Gerhard; Strothotte, Thomas

    2001-06-01

    We describe an application supporting alternating interaction and animation for the purpose of exploration in a surround- screen projection-based virtual reality system. The exploration of an environment is a highly interactive and dynamic process in which the presentation of objects of interest can give the user guidance while exploring the scene. Previous systems for automatic presentation of models or scenes need either cinematographic rules, direct human interaction, framesets or precalculation (e.g. precalculation of paths to a predefined goal). We report on the development of a system that can deal with rapidly changing user interest in objects of a scene or model as well as with dynamic models and changes of the camera position introduced interactively by the user. It is implemented as a potential-field based camera data generating system. In this paper we describe the implementation of our approach in a virtual art museum on the CyberStage, our surround-screen projection-based stereoscopic display. The paradigm of guided exploration is introduced describing the freedom of the user to explore the museum autonomously. At the same time, if requested by the user, guided exploration provides just-in-time navigational support. The user controls this support by specifying the current field of interest in high-level search criteria. We also present an informal user study evaluating this approach.

  13. Prevention and Intervention Strategies to Alleviate Preoperative Anxiety in Children

    ERIC Educational Resources Information Center

    Wright, Kristi D.; Stewart, Sherry H.; Finley, G. Allen; Buffett-Jerrott, Susan E.

    2007-01-01

    Preoperative anxiety (anxiety regarding impending surgical experience) in children is a common phenomenon that has been associated with a number of negative behaviors during the surgery experience (e.g., agitation, crying, spontaneous urination, and the need for physical restraint during anesthetic induction). Preoperative anxiety has also been…

  14. Preoperative diagnosis of double gallbladder: a case report.

    PubMed

    Buluş, Hakan; Koyuncu, Ahmet; Coşkun, Ali

    2012-04-01

    Gallbladder duplication is a rare congenital anomaly of the biliary system. There are no specific symptoms for diagnosis. We present the case of a double gallbladder, which was diagnosed preoperatively. A laparoscopic cholecystectomy was performed successfully. We discuss that the preoperative diagnosis of this anomaly is especially important to prevent possible surgical complications and repeated laparotomies. PMID:22706748

  15. Computer aided preoperative evaluation of the residual liver volume using computed tomography images.

    PubMed

    Bliznakova, Kristina; Kolev, Nikola; Buliev, Ivan; Tonev, Anton; Encheva, Elitsa; Bliznakov, Zhivko; Ivanov, Krasimir

    2015-04-01

    Major hepatectomy causes a risk of postoperative liver dysfunction, failure, and infections like surgical site infection. Preoperative assessment of the liver volume and function of the remnant liver is a mandatory prerequisite before performing such surgery. The aim of this work is to develop and test a software application for evaluation of the residual function of the liver prior to the intervention of the surgeons. For this purpose, a technique for evaluation of liver volume from computed tomography (CT) images has been developed. Furthermore, the methodology algorithms were implemented and incorporated within a software tool with three basic functionalities: volume determination based on segmentation of liver from CT images, virtual tumour resection and estimation of the residual liver function and 3D visualisation. Forty-one sets of abdominal CT images consisting of different number of tomographic slice images were used to test and evaluate the proposed approach. Volumes that were obtained after manual tracing by two surgeon experts showed a relative difference of 3.5 %. The suggested methodology was encapsulated within an application with user-friendly interface that allows surgeons interactively to perform virtual tumour resection, to evaluate the relative residual liver and render the final result. Thereby, it is a tool in the surgeons' hands that significantly facilitates their duties, saves time, and allows them to objectively evaluate the situation and take the right decisions. At the same time, the tool appears to be appropriate educational instrument for virtual training of young surgeon specialists. PMID:25273505

  16. An ultrasound-based navigation system for minimally invasive neck surgery.

    PubMed

    Brennecke, Thorsten; Jansen, Nils; Raczkowsky, Joerg; Schipper, Joerg; Woern, Heinz

    2014-01-01

    Future minimally invasive neck surgery requires a navigation system adapted to the actual intra-operative bedding of the patient. The detection of the bedding-caused tissue shift is essential for a safe orientation for the surgeon new endoscopic operation procedures in neck surgery. It is essential to visualize the relation between important anatomic landmarks and operation instruments at any time. Within the scientific project SACAS we focus on developing an ultrasound supported navigation system based on preoperative imaging which considers the intra-operative tissue shift. A rotatable, flexible neck-model provides the basis for our analysis to evaluate the tissue shift and to invent the new navigation system for endoscopic neck surgery. The total registration error of the system was 2 mm. PMID:24732476

  17. Virtual trackballs revisited.

    PubMed

    Henriksen, Knud; Sporring, Jon; Hornbaek, Kasper

    2004-01-01

    Rotation of three-dimensional objects by a two-dimensional mouse is a typical task in computer-aided design, operation simulations, and desktop virtual reality. The most commonly used rotation technique is a virtual trackball surrounding the object and operated by the mouse pointer. This article reviews and provides a mathematical foundation for virtual trackballs. The first, but still popular, virtual trackball was described by Chen et al. We show that the virtual trackball by Chen et al. does not rotate the object along the intended great circular arc on the virtual trackball and we give a correction. Another popular virtual trackball is Shoemake's quaternion implementation, which we show to be a special case of the virtual trackball by Chen et al.. Shoemake extends the scope of the virtual trackball to the full screen. Unfortunately, Shoemake's virtual trackball is inhomogeneous and discontinuous with consequences for usability. Finally, we review Bell's virtual trackball and discuss studies of the usability of virtual trackballs. PMID:15384645

  18. Virtual Reference Services.

    ERIC Educational Resources Information Center

    Brewer, Sally

    2003-01-01

    As the need to access information increases, school librarians must create virtual libraries. Linked to reliable reference resources, the virtual library extends the physical collection and library hours and lets students learn to use Web-based resources in a protected learning environment. The growing number of virtual schools increases the need…

  19. Virtual Worlds? "Outlook Good"

    ERIC Educational Resources Information Center

    Kelton, AJ

    2008-01-01

    Many people believed that virtual worlds would end up like the eight-track audiotape: a memory of something no longer used (or useful). Yet today there are hundreds of higher education institutions represented in three-dimensional (3D) virtual worlds such as Active Worlds and Second Life. The movement toward the virtual realm as a viable teaching…

  20. Virtual Reality: An Overview.

    ERIC Educational Resources Information Center

    Franchi, Jorge

    1994-01-01

    Highlights of this overview of virtual reality include optics; interface devices; virtual worlds; potential applications, including medicine and archaeology; problems, including costs; current research and development; future possibilities; and a listing of vendors and suppliers of virtual reality products. (Contains 11 references.) (LRW)

  1. Navigating the Rockets Educator Guide

    NASA Video Gallery

    In this brief video overview, learn how to navigate the Rockets Educator Guide. Get a glimpse of the resources available in the guide, including a pictorial history, an overview of the physics cont...

  2. Almanac services for celestial navigation

    NASA Astrophysics Data System (ADS)

    Nelmes, S.; Whittaker, J.

    2015-08-01

    Celestial navigation remains a vitally important back up to Global Navigation Satellite Systems (GNSS) and relies on the use of almanac services. HM Nautical Almanac Office (HMNAO) provides a number of these services. The printed book, The Nautical Almanac, produced yearly and now available as an electronic publication, is continuously being improved, making use of the latest ideas and ephemerides to provide the user with their required data. HMNAO also produces NavPac, a software package that assists the user in calculating their position as well as providing additional navigational and astronomical tools. A new version of NavPac will be released in 2015 that will improve the user experience. The development of applications for mobile devices is also being considered. HMNAO continues to combine the latest improvements and theories of astrometry with the creation of books and software that best meet the needs of celestial navigation users.

  3. Orion Cislunar Guidance and Navigation

    NASA Technical Reports Server (NTRS)

    D'Souza, Christopher; Crain, Timothy; Clark, Fred C.

    2007-01-01

    The Orion vehicle is being designed to provide nominal crew transport to the lunar transportation stack in low Earth orbit, crew abort prior during transit to the moon, and crew return to Earth once lunar orbit is achieved. Design of guidance and navigation algorithms to perform maneuvers in support of these functions is dependent on the support provided by navigation infrastructure, the performance of the onboard GN&C system, and the choice of trajectory maneuver methodology for outbound and return mission phases. This paper documents the preliminary integrated analyses performed by members of the Orion Orbit GN&C System team investigating the navigation update accuracy of a modern equivalent to the Apollo era ground tracking network and the expected onboard dispersion and navigation errors during a lunar mission using a linear covariance error analysis technique.

  4. Potential applications of satellite navigation

    NASA Astrophysics Data System (ADS)

    Schaenzer, G.

    The applicability of Navstar GPS to civil air navigation is discussed. The accuracy of current air-navigation systems is reviewed; the basic principle and accuracy of GPS navigation are characterized; the relatively low cost of GPS receiving equipment is pointed out; and particular attention is given to hybrid systems combining GPS with inertial navigation. It is predicted that CAT III landings will be possible using such hybrid systems when the GPS satellites are fully deployed, even without access to the military GPS code. Techniques for GPS-based precision landings, reduced-noise landings, landings on parallel runways, control of taxiing maneuvers, and aircraft-based geodetic measurements are briefly described and illustrated with diagrams.

  5. Autonomous navigation using lunar beacons

    NASA Technical Reports Server (NTRS)

    Khatib, A. R.; Ellis, J.; French, J.; Null, G.; Yunck, T.; Wu, S.

    1983-01-01

    The concept of using lunar beacon signal transmission for on-board navigation for earth satellites and near-earth spacecraft is described. The system would require powerful transmitters on the earth-side of the moon's surface and black box receivers with antennae and microprocessors placed on board spacecraft for autonomous navigation. Spacecraft navigation requires three position and three velocity elements to establish location coordinates. Two beacons could be soft-landed on the lunar surface at the limits of allowable separation and each would transmit a wide-beam signal with cones reaching GEO heights and be strong enough to be received by small antennae in near-earth orbit. The black box processor would perform on-board computation with one-way Doppler/range data and dynamical models. Alternatively, GEO satellites such as the GPS or TDRSS spacecraft can be used with interferometric techniques to provide decimeter-level accuracy for aircraft navigation.

  6. SEXTANT: Navigating by Cosmic Beacon

    NASA Video Gallery

    Imagine a technology that would allow space travelers to transmit gigabytes of data per second over interplanetary distances or to navigate to Mars and beyond using powerful beams of light emanatin...

  7. Autonomous Navigation Using Celestial Objects

    NASA Technical Reports Server (NTRS)

    Folta, David; Gramling, Cheryl; Leung, Dominic; Belur, Sheela; Long, Anne

    1999-01-01

    In the twenty-first century, National Aeronautics and Space Administration (NASA) Enterprises envision frequent low-cost missions to explore the solar system, observe the universe, and study our planet. Satellite autonomy is a key technology required to reduce satellite operating costs. The Guidance, Navigation, and Control Center (GNCC) at the Goddard Space Flight Center (GSFC) currently sponsors several initiatives associated with the development of advanced spacecraft systems to provide autonomous navigation and control. Autonomous navigation has the potential both to increase spacecraft navigation system performance and to reduce total mission cost. By eliminating the need for routine ground-based orbit determination and special tracking services, autonomous navigation can streamline spacecraft ground systems. Autonomous navigation products can be included in the science telemetry and forwarded directly to the scientific investigators. In addition, autonomous navigation products are available onboard to enable other autonomous capabilities, such as attitude control, maneuver planning and orbit control, and communications signal acquisition. Autonomous navigation is required to support advanced mission concepts such as satellite formation flying. GNCC has successfully developed high-accuracy autonomous navigation systems for near-Earth spacecraft using NASA's space and ground communications systems and the Global Positioning System (GPS). Recently, GNCC has expanded its autonomous navigation initiative to include satellite orbits that are beyond the regime in which use of GPS is possible. Currently, GNCC is assessing the feasibility of using standard spacecraft attitude sensors and communication components to provide autonomous navigation for missions including: libration point, gravity assist, high-Earth, and interplanetary orbits. The concept being evaluated uses a combination of star, Sun, and Earth sensor measurements along with forward-link Doppler

  8. Interaction Design and Usability of Learning Spaces in 3D Multi-user Virtual Worlds

    NASA Astrophysics Data System (ADS)

    Minocha, Shailey; Reeves, Ahmad John

    Three-dimensional virtual worlds are multimedia, simulated environments, often managed over the Web, which users can 'inhabit' and interact via their own graphical, self-representations known as 'avatars'. 3D virtual worlds are being used in many applications: education/training, gaming, social networking, marketing and commerce. Second Life is the most widely used 3D virtual world in education. However, problems associated with usability, navigation and way finding in 3D virtual worlds may impact on student learning and engagement. Based on empirical investigations of learning spaces in Second Life, this paper presents design guidelines to improve the usability and ease of navigation in 3D spaces. Methods of data collection include semi-structured interviews with Second Life students, educators and designers. The findings have revealed that design principles from the fields of urban planning, Human- Computer Interaction, Web usability, geography and psychology can influence the design of spaces in 3D multi-user virtual environments.

  9. 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. PMID:27053732

  10. The navigation of space probes

    NASA Technical Reports Server (NTRS)

    Fliegel, H. F.; Ohandley, D. A.; Zielenbach, J. W.

    1974-01-01

    A new navigational method combining electronic measurement procedures and celestial mechanics makes it possible to conduct a space probe very close to a desired point in the neighborhood of a remote planet. Approaches for the determination of the position of the space probe in space are discussed, giving attention to the effects of errors in the employed data. The application of the navigational methods in a number of space missions is also considered.

  11. PandaEPL: A library for programming spatial navigation experiments

    PubMed Central

    Solway, Alec; Miller, Jonathan F.

    2013-01-01

    Recent advances in neuroimaging and neural recording techniques have enabled researchers to make significant progress in understanding the neural mechanisms underlying human spatial navigation. Because these techniques generally require participants to remain stationary, computer-generated virtual environments are used. We introduce PandaEPL, a programming library for the Python language designed to simplify the creation of computer-controlled spatial-navigation experiments. PandaEPL is built on top of Panda3D, a modern open-source game engine. It allows users to construct three-dimensional environments that participants can navigate from a first-person perspective. Sound playback and recording and also joystick support are provided through the use of additional optional libraries. PandaEPL also handles many tasks common to all cognitive experiments, including managing configuration files, logging all internal and participant-generated events, and keeping track of the experiment state. We describe how PandaEPL compares with other software for building spatial-navigation experiments and walk the reader through the process of creating a fully functional experiment. PMID:23549683

  12. The Taxiway Navigation and Situation Awareness (T-NASA) System

    NASA Technical Reports Server (NTRS)

    Foyle, David C.; Sridhar, Banavar (Technical Monitor)

    1997-01-01

    The goal of NASA's Terminal Area Productivity (TAP) Low-Visibility Landing and Surface Operations (LVLASO) subelement is to improve the efficiency of airport surface operations for commercial aircraft operating in weather conditions to Category IIIB while maintaining a high degree of safety. Currently, surface operations are one of the least technologically sophisticated components of the air transport system, being conducted in the 1990's with the same basic technology as in the 1930's. Pilots are given little or no explicit information about their current position, and routing information is limited to ATC communications and airport charts. In TAP/LVLASO, advanced technologies such as satellite navigation systems, digital data communications, advanced information presentation technology, and ground surveillance systems will be integrated into flight deck displays to enable expeditious and safe traffic movement on the airport surface. The cockpit display suite is called the T-NASA (Taxiway Navigation and Situation Awareness) System. This system has three integrated components: 1) Moving Map track-up airport surface display with own-ship, traffic and graphical route guidance 2) Scene-Linked Symbology - route/taxi information virtually projected via a Head-up Display (HUD) onto the forward scene; and, 3) 3-D Audio Ground Collision Avoidance and Navigation system - spatially-localized auditory traffic and navigation alerts. In the current paper, the design philosophy of the T-NASA system will be presented, and the T-NASA system display components described.

  13. FLASH LIDAR Based Relative Navigation

    NASA Technical Reports Server (NTRS)

    Brazzel, Jack; Clark, Fred; Milenkovic, Zoran

    2014-01-01

    Relative navigation remains the most challenging part of spacecraft rendezvous and docking. In recent years, flash LIDARs, have been increasingly selected as the go-to sensors for proximity operations and docking. Flash LIDARS are generally lighter and require less power that scanning Lidars. Flash LIDARs do not have moving parts, and they are capable of tracking multiple targets as well as generating a 3D map of a given target. However, there are some significant drawbacks of Flash Lidars that must be resolved if their use is to be of long-term significance. Overcoming the challenges of Flash LIDARs for navigation-namely, low technology readiness level, lack of historical performance data, target identification, existence of false positives, and performance of vision processing algorithms as intermediaries between the raw sensor data and the Kalman filter-requires a world-class testing facility, such as the Lockheed Martin Space Operations Simulation Center (SOSC). Ground-based testing is a critical step for maturing the next-generation flash LIDAR-based spacecraft relative navigation. This paper will focus on the tests of an integrated relative navigation system conducted at the SOSC in January 2014. The intent of the tests was to characterize and then improve the performance of relative navigation, while addressing many of the flash LIDAR challenges mentioned above. A section on navigation performance and future recommendation completes the discussion.

  14. Virtual Rover Takes its First Turn

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows a screenshot from the software used by engineers to drive the Mars Exploration Rover Spirit. The software simulates the rover's movements across the martian terrain, helping to plot a safe course for the rover. The virtual 3-D world around the rover is 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. This image depicts the state of the rover before it backed up and turned 45 degrees on Sol 11 (01-13-04).

  15. Optical Navigation Image of Ganymede

    NASA Technical Reports Server (NTRS)

    1996-01-01

    NASA's Galileo spacecraft, now in orbit around Jupiter, returned this optical navigation image June 3, 1996, showing that the spacecraft is accurately targeted for its first flyby of the giant moon Ganymede on June 27. The missing data in the frame is the result of a special editing feature recently added to the spacecraft's computer to transmit navigation images more quickly. This is first in a series of optical navigation frames, highly edited onboard the spacecraft, that will be used to fine-tune the spacecraft's trajectory as Galileo approaches Ganymede. The image, used for navigation purposes only, is the product of new computer processing capabilities on the spacecraft that allow Galileo to send back only the information required to show the spacecraft is properly targeted and that Ganymede is where navigators calculate it to be. 'This navigation image is totally different from the pictures we'll be taking for scientific study of Ganymede when we get close to it later this month,' said Galileo Project Scientist Dr. Torrence Johnson. On June 27, Galileo will fly just 844 kilometers (524 miles) above Ganymede and return the most detailed, full-frame, high-resolution images and other measurements of the satellite ever obtained. Icy Ganymede is the largest moon in the solar system and three-quarters the size of Mars. It is one of the four large Jovian moons that are special targets of study for the Galileo mission. Of the more than 5 million bits contained in a single image, Galileo performed on-board editing to send back a mere 24,000 bits containing the essential information needed to assure proper targeting. Only the light-to-dark transitions of the crescent Ganymede and reference star locations were transmitted to Earth. The navigation image was taken from a distance of 9.8 million kilometers (6.1 million miles). On June 27th, the spacecraft will be 10,000 times closer to Ganymede.

  16. 46 CFR 120.420 - Navigation lights.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Navigation lights. 120.420 Section 120.420 Shipping... Systems § 120.420 Navigation lights. All vessels must have navigation lights that are in compliance with... than 19.8 meters (65 feet) in length must also have navigation lights that meet UL 1104,...

  17. 46 CFR 183.420 - Navigation lights.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Navigation lights. 183.420 Section 183.420 Shipping...) ELECTRICAL INSTALLATION Lighting Systems § 183.420 Navigation lights. All vessels must have navigation lights..., except that a vessel of more than 19.8 meters (65 feet) in length must also have navigation lights...

  18. 46 CFR 183.420 - Navigation lights.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Navigation lights. 183.420 Section 183.420 Shipping...) ELECTRICAL INSTALLATION Lighting Systems § 183.420 Navigation lights. All vessels must have navigation lights..., except that a vessel of more than 19.8 meters (65 feet) in length must also have navigation lights...

  19. 46 CFR 120.420 - Navigation lights.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Navigation lights. 120.420 Section 120.420 Shipping... Systems § 120.420 Navigation lights. All vessels must have navigation lights that are in compliance with... than 19.8 meters (65 feet) in length must also have navigation lights that meet UL 1104,...

  20. 46 CFR 183.420 - Navigation lights.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Navigation lights. 183.420 Section 183.420 Shipping...) ELECTRICAL INSTALLATION Lighting Systems § 183.420 Navigation lights. All vessels must have navigation lights..., except that a vessel of more than 19.8 meters (65 feet) in length must also have navigation lights...

  1. 46 CFR 120.420 - Navigation lights.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Navigation lights. 120.420 Section 120.420 Shipping... Systems § 120.420 Navigation lights. All vessels must have navigation lights that are in compliance with... than 19.8 meters (65 feet) in length must also have navigation lights that meet UL 1104,...

  2. 46 CFR 183.420 - Navigation lights.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Navigation lights. 183.420 Section 183.420 Shipping...) ELECTRICAL INSTALLATION Lighting Systems § 183.420 Navigation lights. All vessels must have navigation lights..., except that a vessel of more than 19.8 meters (65 feet) in length must also have navigation lights...

  3. 46 CFR 120.420 - Navigation lights.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Navigation lights. 120.420 Section 120.420 Shipping... Systems § 120.420 Navigation lights. All vessels must have navigation lights that are in compliance with... than 19.8 meters (65 feet) in length must also have navigation lights that meet UL 1104,...

  4. 46 CFR 120.420 - Navigation lights.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Navigation lights. 120.420 Section 120.420 Shipping... Systems § 120.420 Navigation lights. All vessels must have navigation lights that are in compliance with... than 19.8 meters (65 feet) in length must also have navigation lights that meet UL 1104,...

  5. 46 CFR 183.420 - Navigation lights.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Navigation lights. 183.420 Section 183.420 Shipping...) ELECTRICAL INSTALLATION Lighting Systems § 183.420 Navigation lights. All vessels must have navigation lights..., except that a vessel of more than 19.8 meters (65 feet) in length must also have navigation lights...

  6. Increasing accessibility to the blind of virtual environments, using a virtual mobility aid based on the "EyeCane": feasibility study.

    PubMed

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

    2013-01-01

    Virtual worlds and environments are becoming an increasingly central part of our lives, yet they are still far from accessible to the blind. This is especially unfortunate as such environments hold great potential for them for uses such as social interaction, online education and especially for use with familiarizing the visually impaired user with a real environment virtually from the comfort and safety of his own home before visiting it in the real world. We have implemented a simple algorithm to improve this situation using single-point depth information, enabling the blind to use a virtual cane, modeled on the "EyeCane" electronic travel aid, within any virtual environment with minimal pre-processing. Use of the Virtual-EyeCane, enables this experience to potentially be later used in real world environments with identical stimuli to those from the virtual environment. We show the fast-learned practical use of this algorithm for navigation in simple environments. PMID:23977316

  7. Preoperative optimization of the vascular surgery patient.

    PubMed

    Zhan, Henry T; Purcell, Seth T; Bush, Ruth L

    2015-01-01

    It is well known that patients who suffer from peripheral (noncardiac) vascular disease often have coexisting atherosclerotic diseases of the heart. This may leave the patients susceptible to major adverse cardiac events, including death, myocardial infarction, unstable angina, and pulmonary edema, during the perioperative time period, in addition to the many other complications they may sustain as they undergo vascular surgery procedures, regardless of whether the procedure is performed as an open or endovascular modality. As these patients are at particularly high risk, up to 16% in published studies, for postoperative cardiac complications, many proposals and algorithms for perioperative optimization have been suggested and studied in the literature. Moreover, in patients with recent coronary stents, the risk of non-cardiac surgery on adverse cardiac events is incremental in the first 6 months following stent implantation. Just as postoperative management of patients is vital to the outcome of a patient, preoperative assessment and optimization may reduce, and possibly completely alleviate, the risks of major postoperative complications, as well as assist in the decision-making process regarding the appropriate surgical and anesthetic management. This review article addresses several tools and therapies that treating physicians may employ to medically optimize a patient before they undergo noncardiac vascular surgery. PMID:26170688

  8. The Preoperative Patient With a Systolic Murmur

    PubMed Central

    Cowie, Brian

    2015-01-01

    Context: Patients with undifferentiated systolic murmurs present commonly during the perioperative period. Traditional bedside assessment and auscultation has not changed significantly in almost 200 years and relies on interpreting indirect acoustic events as a means of evaluating underlying cardiac pathology. This is notoriously inaccurate, even in expert cardiology hands, since many different valvular and cardiac diseases present with a similar auditory signal. Evidence Acquisition: The data on systolic murmurs, physical examination, perioperative valvular disease in the setting of non-cardiac surgery is reviewed. Results: Significant valvular heart disease increases perioperative risk in major non-cardiac surgery and increases long term patient morbidity and mortality. We propose a more modern approach to physical examination that incorporates the use of focused echocardiography to allow direct visualization of cardiac structure and function. This improves the diagnostic accuracy of clinical assessment, allows rational planning of surgery and anaesthesia technique, risk stratification, postoperative monitoring and appropriate referral to physicians and cardiologists. Conclusions: With a thorough preoperative assessment incorporating focused echocardiography, anaesthetists are in the unique position to enhance their role as perioperative physicians and influence short and long term outcomes of their patients. PMID:26705529

  9. 33 CFR 66.10-15 - Aids to navigation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Aids to navigation. 66.10-15 Section 66.10-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System § 66.10-15 Aids to navigation....

  10. 33 CFR 66.10-15 - Aids to navigation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Aids to navigation. 66.10-15 Section 66.10-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System § 66.10-15 Aids to navigation....

  11. 33 CFR 66.10-15 - Aids to navigation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Aids to navigation. 66.10-15 Section 66.10-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System § 66.10-15 Aids to navigation....

  12. 33 CFR 66.10-15 - Aids to navigation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Aids to navigation. 66.10-15 Section 66.10-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System § 66.10-15 Aids to navigation....

  13. 33 CFR 66.10-15 - Aids to navigation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Aids to navigation. 66.10-15 Section 66.10-15 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System § 66.10-15 Aids to navigation....

  14. 33 CFR 66.10-35 - Navigation lights.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Navigation lights. 66.10-35 Section 66.10-35 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION PRIVATE AIDS TO NAVIGATION Uniform State Waterway Marking System § 66.10-35 Navigation lights....

  15. Modelling group navigation: transitive social structures improve navigational performance

    PubMed Central

    Flack, Andrea; Biro, Dora; Guilford, Tim; Freeman, Robin

    2015-01-01

    Collective navigation demands that group members reach consensus on which path to follow, a task that might become more challenging when the group's members have different social connections. Group decision-making mechanisms have been studied successfully in the past using individual-based modelling, although many of these studies have neglected the role of social connections between the group's interacting members. Nevertheless, empirical studies have demonstrated that individual recognition, previous shared experiences and inter-individual familiarity can influence the cohesion and the dynamics of the group as well as the relative spatial positions of specific individuals within it. Here, we use models of collective motion to study the impact of social relationships on group navigation by introducing social network structures into a model of collective motion. Our results show that groups consisting of equally informed individuals achieve the highest level of accuracy when they are hierarchically organized with the minimum number of preferred connections per individual. We also observe that the navigational accuracy of a group will depend strongly on detailed aspects of its social organization. More specifically, group navigation does not only depend on the underlying social relationships, but also on how much weight leading individuals put on following others. Also, we show that groups with certain social structures can compensate better for an increased level of navigational error. The results have broader implications for studies on collective navigation and motion because they show that only by considering a group's social system can we fully elucidate the dynamics and advantages of joint movements. PMID:26063820

  16. Modelling group navigation: transitive social structures improve navigational performance.

    PubMed

    Flack, Andrea; Biro, Dora; Guilford, Tim; Freeman, Robin

    2015-07-01

    Collective navigation demands that group members reach consensus on which path to follow, a task that might become more challenging when the group's members have different social connections. Group decision-making mechanisms have been studied successfully in the past using individual-based modelling, although many of these studies have neglected the role of social connections between the group's interacting members. Nevertheless, empirical studies have demonstrated that individual recognition, previous shared experiences and inter-individual familiarity can influence the cohesion and the dynamics of the group as well as the relative spatial positions of specific individuals within it. Here, we use models of collective motion to study the impact of social relationships on group navigation by introducing social network structures into a model of collective motion. Our results show that groups consisting of equally informed individuals achieve the highest level of accuracy when they are hierarchically organized with the minimum number of preferred connections per individual. We also observe that the navigational accuracy of a group will depend strongly on detailed aspects of its social organization. More specifically, group navigation does not only depend on the underlying social relationships, but also on how much weight leading individuals put on following others. Also, we show that groups with certain social structures can compensate better for an increased level of navigational error. The results have broader implications for studies on collective navigation and motion because they show that only by considering a group's social system can we fully elucidate the dynamics and advantages of joint movements. PMID:26063820

  17. Titanium-bone-anchored penile epithesis: preoperative planning and immediate postoperative results.

    PubMed

    Selvaggi, Gennaro; Branemark, Rickard; Elander, Anna; Liden, Mattias; Stalfors, Joacim

    2015-02-01

    The principle of osseointegration is accepted and used in reconstructive surgery. This study presents the first series of five patients where titanium implants have been implanted into the pubic bones of female-to-male (FTM) transsexual patients, in order to attach a "bone-anchored" penile epithesis. Following patient selection based on patients' wishes, pubic bones of 10 FTM transsexuals were analysed by CT-scan and a virtual planning was made. A surgical plan was also developed. To date, five FTM transsexuals have undergone the two-stage surgery. During stage-1, two titanium implants ("fixtures") are implanted onto the pubic bone. Four weeks postop, a new CT scan is performed to analyze osseointegration and the final implant position. During stage-2, the soft tissue of the pubic area is reduced; abutments are inserted and passed through the skin. A few weeks after stage 2 surgery, a penile epithesis is connected to the skin-penetrating titanium implants. Two out of 10 patients who received preoperative CT scan presented with smaller pubic bones, not able to accommodate the fixtures as chosen originally. Preoperative virtual planning is crucial for the selection of the appropriate implants size. The stage-1 and stage-2 surgery occurred uneventfully in all five patients. One patient presented with a wound infection 1 week after stage-2 surgery. Postoperative CT scan demonstrates implant osseointegration in all cases. This experimental clinical study demonstrates that titanium osseointegration is feasible onto the pubic bone. This new approach for penile reconstruction constitutes another alternative for both transsexual patients and cases following genital development disorders, post-trauma and surgery. PMID:24931337

  18. Orientation and metacognition in virtual space.

    PubMed

    Tenbrink, Thora; Salwiczek, Lucie H

    2016-05-01

    Cognitive scientists increasingly use virtual reality scenarios to address spatial perception, orientation, and navigation. If based on desktops rather than mobile immersive environments, this involves a discrepancy between the physically experienced static position and the visually perceived dynamic scene, leading to cognitive challenges that users of virtual worlds may or may not be aware of. The frequently reported loss of orientation and worse performance in point-to-origin tasks relate to the difficulty of establishing a consistent reference system on an allocentric or egocentric basis. We address the verbalizability of spatial concepts relevant in this regard, along with the conscious strategies reported by participants. Behavioral and verbal data were collected using a perceptually sparse virtual tunnel scenario that has frequently been used to differentiate between humans' preferred reference systems. Surprisingly, the linguistic data we collected relate to reference system verbalizations known from the earlier literature only to a limited extent, but instead reveal complex cognitive mechanisms and strategies. Orientation in desktop virtual reality appears to pose considerable challenges, which participants react to by conceptualizing the task in individual ways that do not systematically relate to the generic concepts of egocentric and allocentric reference frames. PMID:26594879

  19. Virtual VMASC: A 3D Game Environment

    NASA Technical Reports Server (NTRS)

    Manepalli, Suchitra; Shen, Yuzhong; Garcia, Hector M.; Lawsure, Kaleen

    2010-01-01

    The advantages of creating interactive 3D simulations that allow viewing, exploring, and interacting with land improvements, such as buildings, in digital form are manifold and range from allowing individuals from anywhere in the world to explore those virtual land improvements online, to training military personnel in dealing with war-time environments, and to making those land improvements available in virtual worlds such as Second Life. While we haven't fully explored the true potential of such simulations, we have identified a requirement within our organization to use simulations like those to replace our front-desk personnel and allow visitors to query, naVigate, and communicate virtually with various entities within the building. We implemented the Virtual VMASC 3D simulation of the Virginia Modeling Analysis and Simulation Center (VMASC) office building to not only meet our front-desk requirement but also to evaluate the effort required in designing such a simulation and, thereby, leverage the experience we gained in future projects of this kind. This paper describes the goals we set for our implementation, the software approach taken, the modeling contribution made, and the technologies used such as XNA Game Studio, .NET framework, Autodesk software packages, and, finally, the applicability of our implementation on a variety of architectures including Xbox 360 and PC. This paper also summarizes the result of our evaluation and the lessons learned from our effort.

  20. Automated flight path planning for virtual endoscopy.

    PubMed

    Paik, D S; Beaulieu, C F; Jeffrey, R B; Rubin, G D; Napel, S

    1998-05-01

    In this paper, a novel technique for rapid and automatic computation of flight paths for guiding virtual endoscopic exploration of three-dimensional medical images is described. While manually planning flight paths is a tedious and time consuming task, our algorithm is automated and fast. Our method for positioning the virtual camera is based on the medial axis transform but is much more computationally efficient. By iteratively correcting a path toward the medial axis, the necessity of evaluating simple point criteria during morphological thinning is eliminated. The virtual camera is also oriented in a stable viewing direction, avoiding sudden twists and turns. We tested our algorithm on volumetric data sets of eight colons, one aorta and one bronchial tree. The algorithm computed the flight paths in several minutes per volume on an inexpensive workstation with minimal computation time added for multiple paths through branching structures (10%-13% per extra path). The results of our algorithm are smooth, centralized paths that aid in the task of navigation in virtual endoscopic exploration of three-dimensional medical images. PMID:9608471

  1. Computed Tomography Angiography for Preoperative Thoracoabdominal Flap Planning.

    PubMed

    O'Malley, Ryan B; Robinson, Tracy J; Kozlow, Jeffrey H; Liu, Peter S

    2016-01-01

    Mastectomy rates have increased, coinciding with more advanced reconstruction options. Deep inferior epigastric perforator (DIEP) flaps decrease abdominal donor site morbidity, but require considerable technical expertise. Preoperative computed tomography angiography (CTA) can accurately demonstrate DIEA anatomy and perforator courses, facilitating preoperative planning and flap design, allowing for more targeted intraoperative microdissection. Patients who undergo CTA before DIEP flap have better clinical outcomes with shorter operative times and hospital length of stay, which can decrease overall associated health care costs. Future directions include selected imaging of the thoracic anatomy and recipient vasculature, allowing for additional preoperative planning and customization. PMID:26654396

  2. Computer-assisted virtual technology in intracapsular condylar fracture with two resorbable long-screws.

    PubMed

    Wang, W H; Deng, J Y; Zhu, J; Li, M; Xia, B; Xu, B

    2013-03-01

    Our aim was to fix intracapsular condylar fractures (ICF) with two resorbable long screws using preoperative computer-assisted virtual technology. From February 2008 to July 2011, 19 patients with ICF were treated with two resorbable long screws. Preoperatively we took panoramic radiographs and spiral computed tomography (CT). Depending on their digital imaging and communications in medicine (DICOM) data, the dislocated condylar segments were restored using the SimPlant Pro™ software, version 11.04. The mean (SD) widths of the condylar head and neck from lateral to medial were 19.01 (1.28)mm and 13.84 (1.13)mm, respectively. In all patients, the mandibles and the ICF seen intraoperatively corresponded with the preoperative three-dimensional and virtual reposition. All patients were followed up for 6-46 months (mean 21). Occlusion and mouth opening had been restored completely in all but one patient, and absolute anatomical reduction was also achieved in most cases. Computer-assisted virtual technology plays an important part in the diagnosis of ICF, as well as in its preoperative design. Fixation with only two resorbable long screws is an effective and reliable method for fixing ICF. PMID:22546281

  3. Autonomous navigation system. [gyroscopic pendulum for air navigation

    NASA Technical Reports Server (NTRS)

    Merhav, S. J. (Inventor)

    1981-01-01

    An inertial navigation system utilizing a servo-controlled two degree of freedom pendulum to obtain specific force components in the locally level coordinate system is described. The pendulum includes a leveling gyroscope and an azimuth gyroscope supported on a two gimbal system. The specific force components in the locally level coordinate system are converted to components in the geographical coordinate system by means of a single Euler transformation. The standard navigation equations are solved to determine longitudinal and lateral velocities. Finally, vehicle position is determined by a further integration.

  4. Mission Operations and Navigation Toolkit Environment

    NASA Technical Reports Server (NTRS)

    Sunseri, Richard F.; Wu, Hsi-Cheng; Hanna, Robert A.; Mossey, Michael P.; Duncan, Courtney B.; Evans, Scott E.; Evans, James R.; Drain, Theodore R.; Guevara, Michelle M.; Martin Mur, Tomas J.; Attiyah, Ahlam A.

    2009-01-01

    MONTE (Mission Operations and Navigation Toolkit Environment) Release 7.3 is an extensible software system designed to support trajectory and navigation analysis/design for space missions. MONTE is intended to replace the current navigation and trajectory analysis software systems, which, at the time of this reporting, are used by JPL's Navigation and Mission Design section. The software provides an integrated, simplified, and flexible system that can be easily maintained to serve the needs of future missions in need of navigation services.

  5. 14 CFR 125.267 - Flight navigator and long-range 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 long-range navigation... Requirements § 125.267 Flight navigator and long-range navigation equipment. (a) No certificate holder may... current flight navigator certificate; or (2) Two independent, properly functioning, and approved...

  6. 14 CFR 125.267 - Flight navigator and long-range 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 long-range navigation... Requirements § 125.267 Flight navigator and long-range navigation equipment. (a) No certificate holder may... current flight navigator certificate; or (2) Two independent, properly functioning, and approved...

  7. 14 CFR 125.267 - Flight navigator and long-range 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 long-range navigation... Requirements § 125.267 Flight navigator and long-range navigation equipment. (a) No certificate holder may... current flight navigator certificate; or (2) Two independent, properly functioning, and approved...

  8. 14 CFR 125.267 - Flight navigator and long-range 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 long-range navigation... Requirements § 125.267 Flight navigator and long-range navigation equipment. (a) No certificate holder may... current flight navigator certificate; or (2) Two independent, properly functioning, and approved...

  9. 14 CFR 125.267 - Flight navigator and long-range 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 long-range navigation... Requirements § 125.267 Flight navigator and long-range navigation equipment. (a) No certificate holder may...-range means of navigation which enable a reliable determination to be made of the position of...

  10. Action video game play and transfer of navigation and spatial cognition skills in adolescents who are blind.

    PubMed

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

    2014-01-01

    For individuals who are blind, navigating independently in an unfamiliar environment represents a considerable challenge. Inspired by the rising popularity of video games, we have developed a novel approach to train navigation and spatial cognition skills in adolescents who are blind. Audio-based Environment Simulator (AbES) is a software application that allows for the virtual exploration of an existing building set in an action video game metaphor. Using this ludic-based approach to learning, we investigated the ability and efficacy of adolescents with early onset blindness to acquire spatial information gained from the exploration of a target virtual indoor environment. Following game play, participants were assessed on their ability to transfer and mentally manipulate acquired spatial information on a set of navigation tasks carried out in the real environment. Success in transfer of navigation skill performance was markedly high suggesting that interacting with AbES leads to the generation of an accurate spatial mental representation. Furthermore, there was a positive correlation between success in game play and navigation task performance. The role of virtual environments and gaming in the development of mental spatial representations is also discussed. We conclude that this game based learning approach can facilitate the transfer of spatial knowledge and further, can be used by individuals who are blind for the purposes of navigation in real-world environments. PMID:24653690

  11. Action video game play and transfer of navigation and spatial cognition skills in adolescents who are blind

    PubMed Central

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

    2014-01-01

    For individuals who are blind, navigating independently in an unfamiliar environment represents a considerable challenge. Inspired by the rising popularity of video games, we have developed a novel approach to train navigation and spatial cognition skills in adolescents who are blind. Audio-based Environment Simulator (AbES) is a software application that allows for the virtual exploration of an existing building set in an action video game metaphor. Using this ludic-based approach to learning, we investigated the ability and efficacy of adolescents with early onset blindness to acquire spatial information gained from the exploration of a target virtual indoor environment. Following game play, participants were assessed on their ability to transfer and mentally manipulate acquired spatial information on a set of navigation tasks carried out in the real environment. Success in transfer of navigation skill performance was markedly high suggesting that interacting with AbES leads to the generation of an accurate spatial mental representation. Furthermore, there was a positive correlation between success in game play and navigation task performance. The role of virtual environments and gaming in the development of mental spatial representations is also discussed. We conclude that this game based learning approach can facilitate the transfer of spatial knowledge and further, can be used by individuals who are blind for the purposes of navigation in real-world environments. PMID:24653690

  12. Virtual Campus in the Context of an Educational Virtual City

    ERIC Educational Resources Information Center

    Fominykh, Mikhail; Prasolova-Forland, Ekaterina; Morozov, Mikhail; Gerasimov, Alexey

    2011-01-01

    This paper is focused on virtual campuses, i.e. virtual worlds representing real educational institutions that are based on the metaphor of a university and provide users with different learning tools. More specifically, the idea of integrating a virtual campus into the context of a virtual city is suggested. Such a virtual city, where students…

  13. Behavioral Mapless Navigation Using Rings

    NASA Technical Reports Server (NTRS)

    Monroe, Randall P.; Miller, Samuel A.; Bradley, Arthur T.

    2012-01-01

    This paper presents work on the development and implementation of a novel approach to robotic navigation. In this system, map-building and localization for obstacle avoidance are discarded in favor of moment-by-moment behavioral processing of the sonar sensor data. To accomplish this, we developed a network of behaviors that communicate through the passing of rings, data structures that are similar in form to the sonar data itself and express the decisions of each behavior. Through the use of these rings, behaviors can moderate each other, conflicting impulses can be mediated, and designers can easily connect modules to create complex emergent navigational techniques. We discuss the development of a number of these modules and their successful use as a navigation system in the Trinity omnidirectional robot.

  14. Navigation systems. [for interplanetary flight

    NASA Technical Reports Server (NTRS)

    Jordan, J. F.

    1985-01-01

    The elements of the measurement and communications network comprising the global deep space navigation system (DSN) for NASA missions are described. Among the measurement systems discussed are: VLBI, two-way Doppler and range measurements, and optical measurements carried out on board the spacecraft. Processing of navigation measurement is carried out using two modules: an N-body numerical integration of the trajectory (and state transition partial derivatives) based on pre-guessed initial conditions; and partial derivatives of simulated observables corresponding to each actual observation. Calculations of velocity correction parameters is performed by precise modelling of all physical phenomena influencing the observational measurements, including: planetary motions; tracking station locations, gravity field structure, and transmission media effects. Some of the contributions to earth-relative orbit estimate errors for the Doppler/range system on board Voyager are discussed in detail. A line drawing of the DSN navigation system is provided.

  15. Reducing preoperative fasting time: A trend based on evidence

    PubMed Central

    de Aguilar-Nascimento, José Eduardo; Dock-Nascimento, Diana Borges

    2010-01-01

    Preoperative fasting is mandatory before anesthesia to reduce the risk of aspiration. However, the prescribed 6-8 h of fasting is usually prolonged to 12-16 h for various reasons. Prolonged fasting triggers a metabolic response that precipitates gluconeogenesis and increases the organic response to trauma. Various randomized trials and meta-analyses have consistently shown that is safe to reduce the preoperative fasting time with a carbohydrate-rich drink up to 2 h before surgery. Benefits related to this shorter preoperative fasting include the reduction of postoperative gastrointestinal discomfort and insulin resistance. New formulas containing amino acids such as glutamine and other peptides are being studied and are promising candidates to be used to reduce preoperative fasting time. PMID:21160851

  16. Diversity in preoperative-assessment data collection, a literature review.

    PubMed

    Ahmadian, Leila; Cornet, Ronald; van Klei, Wilton A; de Keizer, Nicolette F

    2008-01-01

    The appropriate anesthetic techniques and care during and after operation rely on data gathered during the preoperative assessment. Because various people are involved, standardization of this process is important. This paper provides a systematic literature review about which data items are collected in the preoperative assessment. Thirty-two relevant articles were found by PubMed search. To categorize data SNOMED CT concepts are used, resulting in 13 categories totaling 540 data items. The two largest categories of data were "past history of clinical finding", and "physical examination procedure" with 251 and 75 data items respectively. Our study showed a high diversity of data items in the preoperative assessment. Because of the diversity of patients and treatment options available one undisputed preoperative assessment data set is hard to define. However, to solve the problem of exchangeability of the information at least anesthesiologists should use a same core set of data. PMID:18487719

  17. Preoperative patient assessment: a review of the literature and recommendations.

    PubMed Central

    Barnard, N. A.; Williams, R. W.; Spencer, E. M.

    1994-01-01

    The aims of preoperative assessment of patients are outlined, and the role of clinical and laboratory testing is defined. Following a review of the literature, guidelines for requesting such investigations are suggested. PMID:7979066

  18. Preoperative assessment and optimization in periampullary and pancreatic cancer.

    PubMed

    Myatra, S; Divatia, J V; Jibhkate, B; Barreto, G S; Shrikhande, S V

    2011-01-01

    Perioperative management of pancreatic and periampullary cancer poses a considerable challenge to the pancreatic surgeon, anesthesiologist, and the intensive care team. The preoperative surgical evaluation of a pancreatic lesion aims to define the nature of the lesion (malignant or benign), stage the tumor, and to determine resectability or other non-surgical treatment options. Patients are often elderly and may have significant comorbidities and malnutrition. Obstructive jaundice may lead to coagulopathy, infection, renal dysfunction, and adverse outcomes. Routine preoperative biliary drainage can result in higher complication rates, and metal stents may be preferred over plastic stents in selected patients with resectable disease. Judicious use of antibiotics and maintaining fluid volume preoperatively can reduce the incidence of infection and renal dysfunction, respectively. Perioperative fluid therapy with hemodynamic optimization using minimally invasive monitoring may help improve outcomes. Careful patient selection, appropriate preoperative evaluation and optimization can greatly contribute to a favorable outcome after major pancreatic resections. PMID:21248439

  19. Appraisal of guidelines for pre-operative body wash.

    PubMed

    Edström, Elisabet; Westerberg, Lisa; Henricson, Maria

    The pre-operative body wash is a strategy for reducing post-operative infection. However, there is a lack of knowledge about its importance. The purpose of the present study was to evaluate the quality of guidelines for the pre-operative body wash using the AGREE instrument--35 guidelines containing instructions for the pre-operative body wash or preparation were included. The AGREE instrument was employed to establish a quality assessment framework that facilitated a comparison of the guidelines. The results were based on the six domains of the AGREE instrument, all of which were found to have low adherence. Descriptive statistics were used to present the assessment score. The AGREE instrument is useful for evaluating the quality of clinical guidelines. The development of evidence-based guidelines must include clinical activities. Further research is required to clarify the pre-operative body wash process and how it should be performed to reduce post-operative infection. PMID:25426523

  20. Surgical navigation in oral implantology.

    PubMed

    Miller, Robert J; Bier, Jurgen

    2006-03-01

    The ability to generate 3-dimensional volumetric images of the maxillofacial area has allowed surgeons to evaluate anatomy before surgery and plan for the placement of implants in ideal positions. However, the ability to transfer that information to surgical reality has been the most challenging part of implant dentistry. With the advent of computer-assisted surgery, the surgeon may now navigate through the entire implant procedure with extremely high accuracy. A new portable laptop navigated system for oral implantology is discussed as an adjunct for complex implant cases. PMID:16569960

  1. Navigation: traveling the water highways!

    USGS Publications Warehouse

    Fisher, Marion; Vandas, Stephen; Farrar, Frank, (artist)

    1996-01-01

    NAVIGATION is travel or transportation over water. Many different kinds of boats and ships are used on rivers and oceans to move people and products from one place to another. Navigation was extremely important for foreign and domestic trade and travel in the early days of our country before cars, trucks, trains, and airplanes were invented. In those days, rivers were used as "roads" to connect inland settlements to river and coastal ports. Communities established at these commercial ports became important economic, cultural, and social hubs in the development of our Nation.

  2. Seamless Resource-Adaptive Navigation

    NASA Astrophysics Data System (ADS)

    Schwartz, Tim; Stahl, Christoph; Baus, Jörg; Wahlster, Wolfgang

    Research in the project RENA (REsource-Adapative NAvigation) together with DFKI GmbH, BMW Research and Technology AG, and Eyeled GmbH has been concerned with the conceptual and methodological foundations and the design of a resource-adaptive platform for seamless outdoor and indoor navigation that can serve as a basis for product development by the companies in the RENA consortium. Future in-car assistance systems will have a user interface, which adapts to the driveŕs current exposure caused by the actual traffic situation.

  3. A greedy-navigator approach to navigable city plans

    NASA Astrophysics Data System (ADS)

    Lee, Sang Hoon; Holme, Petter

    2013-01-01

    We use a set of four theoretical navigability indices for street maps to investigate the shape of the resulting street networks, if they are grown by optimizing these indices. The indices compare the performance of simulated navigators (having a partial information about the surroundings, like humans in many real situations) to the performance of optimally navigating individuals. We show that our simple greedy shortcut construction strategy generates the emerging structures that are different from real road network, but not inconceivable. The resulting city plans, for all navigation indices, share common qualitative properties such as the tendency for triangular blocks to appear, while the more quantitative features, such as degree distributions and clustering, are characteristically different depending on the type of metrics and routing strategies. We show that it is the type of metrics used which determines the overall shapes characterized by structural heterogeneity, but the routing schemes contribute to more subtle details of locality, which is more emphasized in case of unrestricted connections when the edge crossing is allowed.

  4. A novel approach to navigated implantation of S-2 alar iliac screws using inertial measurement units.

    PubMed

    Jost, Gregory F; Walti, Jonas; Mariani, Luigi; Cattin, Philippe

    2016-03-01

    OBJECT The authors report on a novel method of intraoperative navigation with inertial measurement units (IMUs) for implantation of S-2 alar iliac (S2AI) screws in sacropelvic fixation of the human spine and its application in cadaveric specimens. METHODS Screw trajectories were planned on a multiplanar reconstruction of the preoperative CT scan. The pedicle finder and screwdriver were equipped with IMUs to guide the axial and sagittal tilt angles of the planned trajectory, and navigation software was developed. The entry points were chosen according to anatomical landmarks on the exposed spine. After referencing, the sagittal and axial orientation of the pedicle finder and screwdriver were wirelessly monitored on a computer screen and aligned with the preoperatively planned tilt angles to implant the S2AI screws. The technique was performed without any intraoperative imaging. Screw positions were analyzed on postoperative CT scans. RESULTS Seventeen of 18 screws showed a good S2AI screw trajectory. Compared with the postoperatively measured tilt angles of the S2AI screws, the IMU readings on the screwdriver were within an axial plane deviation of 0° to 5° in 15 (83%) and 6° to 10° in 2 (11%) of the screws and within a sagittal plane deviation of 0° to 5° in 15 (83%) and 6° to 10° in 3 (17%) of the screws. CONCLUSIONS IMU-based intraoperative navigation may facilitate accurate placement of S2AI screws. PMID:26565762

  5. Improving pre-operative medicines reconciliation

    PubMed Central

    Brunswicker, Annemarie; Yogarajah, Amieth

    2014-01-01

    An audit of 143 surgical admissions showed that only 30% of general surgery and urology patients have complete medication charts on the day of surgery prior to going to theatre, compared to 94% of orthopaedic patients. This was despite having been seen previously in the pre-operative assessment clinic (POAC). These patients went to the wards post-operatively, where many then missed doses of their life-sustaining medications. Orthopaedic patients see a prescribing pharmacist in POAC who undertakes medicines reconciliation; this is performed by junior doctors for surgical patients. We designed three interventions to improve drug chart completion by junior doctors, and gathered prospective data for 22 weeks in the POAC. We also recorded attendance of junior doctors in the POAC and reasons for absence. Daily and weekly percentages of drug chart completion were plotted on a run chart. The baseline completion rate was 43%. This rose to 45% after the first and second interventions, and 51% after the third intervention. However, the completion rate remained markedly below our target of 94%. Junior doctors attended only 44% of POACs. They reported being “too busy to attend” 41% of the time, and could not be contacted on 11% of occasions. Junior doctors reported that they were unable to attend to both unwell inpatients and the POAC, the latter seeming less of a priority. This was despite a rota allocating doctors to attend POAC sessions free from clinical or teaching commitments. We were unable to increase the rate of drug chart completion with the resources available. We therefore recommend the employment of prescribing pharmacists in the POAC for general surgery and urology patients.

  6. Thoracoscopic surgical navigation system for cancer localization in collapsed lung based on estimation of lung deformation.

    PubMed

    Nakamoto, Masahiko; Aburaya, Naoki; Sato, Yoshinobu; Konishi, Kozo; Yoshino, Ichiro; Hashizume, Makoto; Tamura, Shinichi

    2007-01-01

    We have developed a thoracoscopic surgical navigation system for lung cancer localization. In our system, the thoracic cage and mediastinum are localized using rigid registration between the intraoperatively digitized surface points and the preoperative CT surface model, and then the lung deformation field is estimated using nonrigid registration between the registered and digitized point datasets on the collapsed lung surface and the preoperative CT lung surface model to predict cancer locations. In this paper, improved methods on key components of the system are investigated to realize clinically acceptable usability and accuracy. Firstly, we implement a non-contact surface digitizer under thoracoscopic control using an optically tracked laser pointer. Secondly, we establish a rigid registration protocol which minimizes the influence of the deformation in different patient's positions by analyzing MR images of volunteers. These techniques were evaluated by in vitro and clinical experiments. PMID:18044554

  7. Preoperative Planning of Orthopedic Procedures using Digitalized Software Systems.

    PubMed

    Steinberg, Ely L; Segev, Eitan; Drexler, Michael; Ben-Tov, Tomer; Nimrod, Snir

    2016-06-01

    The progression from standard celluloid films to digitalized technology led to the development of new software programs to fulfill the needs of preoperative planning. We describe here preoperative digitalized programs and the variety of conditions for which those programs can be used to facilitate preparation for surgery. A PubMed search using the keywords "digitalized software programs," "preoperative planning" and "total joint arthroplasty" was performed for all studies regarding preoperative planning of orthopedic procedures that were published from 1989 to 2014 in English. Digitalized software programs are enabled to import and export all picture archiving communication system (PACS) files (i.e., X-rays, computerized tomograms, magnetic resonance images) from either the local working station or from any remote PACS. Two-dimension (2D) and 3D CT scans were found to be reliable tools with a high preoperative predicting accuracy for implants. The short learning curve, user-friendly features, accurate prediction of implant size, decreased implant stocks and low-cost maintenance makes digitalized software programs an attractive tool in preoperative planning of total joint replacement, fracture fixation, limb deformity repair and pediatric skeletal disorders. PMID:27468530

  8. Preoperative transcutaneous electrical nerve stimulation for localizing superficial nerve paths.

    PubMed

    Natori, Yuhei; Yoshizawa, Hidekazu; Mizuno, Hiroshi; Hayashi, Ayato

    2015-12-01

    During surgery, peripheral nerves are often seen to follow unpredictable paths because of previous surgeries and/or compression caused by a tumor. Iatrogenic nerve injury is a serious complication that must be avoided, and preoperative evaluation of nerve paths is important for preventing it. In this study, transcutaneous electrical nerve stimulation (TENS) was used for an in-depth analysis of peripheral nerve paths. This study included 27 patients who underwent the TENS procedure to evaluate the peripheral nerve path (17 males and 10 females; mean age: 59.9 years, range: 18-83 years) of each patient preoperatively. An electrode pen coupled to an electrical nerve stimulator was used for superficial nerve mapping. The TENS procedure was performed on patients' major peripheral nerves that passed close to the surgical field of tumor resection or trauma surgery, and intraoperative damage to those nerves was apprehensive. The paths of the target nerve were detected in most patients preoperatively. The nerve paths of 26 patients were precisely under the markings drawn preoperatively. The nerve path of one patient substantially differed from the preoperative markings with numbness at the surgical region. During surgery, the nerve paths could be accurately mapped preoperatively using the TENS procedure as confirmed by direct visualization of the nerve. This stimulation device is easy to use and offers highly accurate mapping of nerves for surgical planning without major complications. The authors conclude that TENS is a useful tool for noninvasive nerve localization and makes tumor resection a safe and smooth procedure. PMID:26420473

  9. Mastectomy following preoperative chemotherapy. Strict operative criteria control operative morbidity.

    PubMed

    Broadwater, J R; Edwards, M J; Kuglen, C; Hortobagyi, G N; Ames, F C; Balch, C M

    1991-02-01

    The surgical morbidity associated with aggressive preoperative chemotherapy in 106 patients with advanced primary breast cancer who had chemotherapy followed by mastectomy was examined. These patients were compared with a group of 91 consecutive patients who had mastectomy without preoperative chemotherapy. Strict operative criteria were used to determine the timing of mastectomy following chemotherapy. Wound infection rates were no different in the preoperative chemotherapy group compared to the mastectomy-alone groups (7% versus 4%; p = 0.62). The incidence of wound necrosis was similar (11% versus 6%; p = 0.29). Seroma formation was decreased significantly in the preoperative chemotherapy group compared to the mastectomy-alone group (15% versus 28%; p = 0.04). Intensive preoperative chemotherapy did not delay the reinstitution of postoperative treatment (30% versus 20%; p = 0.27). However, when delay in instituting postoperative chemotherapy was more than 30 days, there was a significant decrease in overall survival rate (p = 0.04). This study provides evidence that intensive preoperative chemotherapy and mastectomy can be performed without increased morbidity. Furthermore it is important to institute systemic chemotherapy within 30 days of mastectomy to achieve maximum survival. PMID:1992938

  10. Reliable Alignment in Total Knee Arthroplasty by the Use of an iPod-Based Navigation System

    PubMed Central

    Koenen, Paola; Schneider, Marco M.; Fröhlich, Matthias; Driessen, Arne; Bouillon, Bertil; Bäthis, Holger

    2016-01-01

    Axial alignment is one of the main objectives in total knee arthroplasty (TKA). Computer-assisted surgery (CAS) is more accurate regarding limb alignment reconstruction compared to the conventional technique. The aim of this study was to analyse the precision of the innovative navigation system DASH® by Brainlab and to evaluate the reliability of intraoperatively acquired data. A retrospective analysis of 40 patients was performed, who underwent CAS TKA using the iPod-based navigation system DASH. Pre- and postoperative axial alignment were measured on standardized radiographs by two independent observers. These data were compared with the navigation data. Furthermore, interobserver reliability was measured. The duration of surgery was monitored. The mean difference between the preoperative mechanical axis by X-ray and the first intraoperatively measured limb axis by the navigation system was 2.4°. The postoperative X-rays showed a mean difference of 1.3° compared to the final navigation measurement. According to radiographic measurements, 88% of arthroplasties had a postoperative limb axis within ±3°. The mean additional time needed for navigation was 5 minutes. We could prove very good precision for the DASH system, which is comparable to established navigation devices with only negligible expenditure of time compared to conventional TKA. PMID:27313898

  11. Self-Navigating THE TERRAIN

    ERIC Educational Resources Information Center

    Anyaso, Hilary Hurd

    2008-01-01

    There's some good news in the academy regarding Black women: They occupy a number of high-profile executive posts in higher education. But whether Black women scholars want to follow in their footsteps or continue in a teaching or research capacity, the bad news is that many feel they are left to navigate the personal and professional politics of…

  12. Navigation - Project CAPE Teaching Module.

    ERIC Educational Resources Information Center

    Caldwell, Nadine; May, Charlaron

    Ten lessons are included in this interdisciplinary unit on navigation, designed to supplement fifth and sixth grade social studies and science curricula. Each lesson includes: (1) lesson concepts; (2) competency goals; (3) objectives; (4) materials; (5) list of key vocabulary words; (6) background information; (7) teacher preparation; (8) list of…

  13. Evaluation of STOL navigation avionics

    NASA Technical Reports Server (NTRS)

    Dunn, W. R., Jr.

    1977-01-01

    Research projects, including work on a vector magnetometer for aircraft attitude measurement, are summarized. The earth's electric field phenomena was investigated in its application to aircraft control and navigation. Research on electronic aircraft cabin noise suppression is reviewed and strapdown inertial reference unit technical support is outlined.

  14. Multiple source navigation signal generator

    NASA Astrophysics Data System (ADS)

    Bojda, Petr

    2010-09-01

    The paper presents a FPGA based digital VOR/LOC signal generator. It provides the composite signal, which consists of the particular signals of several predefined navigation sources - VOR beacons. Design of the generator is implemented into the two different FPGA DSP platforms.

  15. SMALL CRAFT OPERATION AND NAVIGATION.

    ERIC Educational Resources Information Center

    Louisiana State Dept. of Education, Baton Rouge.

    THIS REFERENCE TEXTBOOK WAS PREPARED FOR USE IN THE FIRST PART OF A TWO-PART COURSE IN MARINE NAVIGATION AND SMALL CRAFT OPERATION ON INLAND AND INTERNATIONAL WATERS. THE MATERIAL WAS DEVELOPED BY AN INDIVIDUAL AUTHOR FOR USE IN TRADE SCHOOL PREPARATORY AND EXTENSION CLASSES FOR MALE ADULTS WHO PLAN TO OPERATE BOATS. IT IS MAINLY CONCERNED WITH…

  16. The value of routine preoperative chest roentgenograms in infants and children

    SciTech Connect

    Farnsworth, P.B.; Steiner, E.; Klein, R.M.; SanFilippo, J.A.

    1980-08-01

    The charts and routine preoperative roentgenograms of 350 children admitted for elective pediatric surgery were analyzed to evaluate the clinical importance of routine preoperative chest roentgenograms. This analysis, and a review of the literature, should indicate that routine preoperative roentgenograms for elective pediatric surgery are unnecessary. Indications for selected preoperative roentgenograms based on patients' history and clinical findings are enumerated.

  17. Digging the Virtual Past

    ERIC Educational Resources Information Center

    Polymeropoulou, Panagiota

    2014-01-01

    In this paper we will investigate the way that the technological progress and the Informatics contributed greatly to the field of Archaeology. There will be analyzed the terms of virtual archaeology and virtual reality in archaeology and there will be an extended reference to the applications and the computer graphics that archaeologists could use…

  18. A Virtual Good Idea

    ERIC Educational Resources Information Center

    Bolch, Matt

    2009-01-01

    School districts across the country have always had to do more with less. Funding goes only so far, leaving administrators and IT staff to find innovative ways to save money while maintaining a high level of academic quality. Creating virtual servers accomplishes both tasks, district technology personnel say. Virtual environments not only allow…

  19. Teaching the Virtual Presentation

    ERIC Educational Resources Information Center

    Flatley, Marie E.

    2007-01-01

    Today, the virtual presentation is catching on rapidly in small, medium, and large businesses alike. A virtual presentation is one delivered live from a desktop or laptop computer to an audience anywhere in the world where there is Internet access. These new Web-based technologies are easy to use and inexpensive, making them readily accessible for…

  20. Virtual Schools. Literature Review

    ERIC Educational Resources Information Center

    Blazer, Christie

    2009-01-01

    The majority of school districts in the U.S. are providing some form of online learning for their students. In the past, virtual schools primarily targeted advanced students who didn't have access to certain courses in their regular schools. Recently, however, many virtual schools have shifted their focus to credit recovery as a way to provide…

  1. Virtual School Counseling

    ERIC Educational Resources Information Center

    Osborn, Debra S.; Peterson, Gary W.; Hale, Rebecca R.

    2015-01-01

    The advent of virtual schools opens doors to opportunity for delivery of student services via the Internet. Through the use of structured interviews with four practicing Florida virtual school counselors, and a follow-up survey, the authors examined the experiences and reflections of school counselors who are employed full time in a statewide…

  2. 10 Myths of Virtualization

    ERIC Educational Resources Information Center

    Schaffhauser, Dian

    2012-01-01

    Half of servers in higher ed are virtualized. But that number's not high enough for Link Alander, interim vice chancellor and CIO at the Lone Star College System (Texas). He aspires to see 100 percent of the system's infrastructure requirements delivered as IT services from its own virtualized data centers or other cloud-based operators. Back in…

  3. Virtual Peace Education

    ERIC Educational Resources Information Center

    Firer, Ruth

    2008-01-01

    This article is based on the convictions that peace education is the basis for any sustainable non-violent relations between parties in a conflict, and that virtual peace education is almost the only feasible way to practise peace education in an open violent conflict as is the current Israeli/Palestinians one. Moreover, virtual peace education…

  4. Virtual Worlds for Educators

    ERIC Educational Resources Information Center

    Dembo, Steve

    2008-01-01

    This article describes an online experience that has not only created a fantasy world for the general public but has enabled some tech-savvy educators to create virtual educational opportunities. Second Life, or SL, is a 3-D Internet-based virtual world created by Linden Lab and populated by nearly 1,000,000 active users worldwide since 2003.…

  5. Human hippocampal processing of environmental novelty during spatial navigation.

    PubMed

    Kaplan, Raphael; Horner, Aidan J; Bandettini, Peter A; Doeller, Christian F; Burgess, Neil

    2014-07-01

    The detection and processing of novel information encountered as we explore our environment is crucial for learning and adaptive behavior. The human hippocampus has been strongly implicated in laboratory tests of novelty detection and episodic memory, but has been less well studied during more ethological tasks such as spatial navigation, typically used in animals. We examined fMRI BOLD activity as a function of environmental and object novelty as humans performed an object-location virtual navigation task. We found greater BOLD response to novel relative to familiar environments in the hippocampus and adjacent parahippocampal gyrus. Object novelty was associated with increased activity in the posterior parahippocampal/fusiform gyrus and anterior hippocampus extending into the amygdala and superior temporal sulcus. Importantly, whilst mid-posterior hippocampus was more sensitive to environmental novelty than object novelty, the anterior hippocampus responded similarly to both forms of novelty. Amygdala activity showed an increase for novel objects that decreased linearly over the learning phase. By investigating how participants learn and use different forms of information during spatial navigation, we found that medial temporal lobe (MTL) activity reflects both the novelty of the environment and of the objects located within it. This novelty processing is likely supported by distinct, but partially overlapping, sets of regions within the MTL. PMID:24550152

  6. Intelligent virtual teacher

    NASA Astrophysics Data System (ADS)

    Takács, Ondřej; Kostolányová, Kateřina

    2016-06-01

    This paper describes the Virtual Teacher that uses a set of rules to automatically adapt the way of teaching. These rules compose of two parts: conditions on various students' properties or learning situation; conclusions that specify different adaptation parameters. The rules can be used for general adaptation of each subject or they can be specific to some subject. The rule based system of Virtual Teacher is dedicated to be used in pedagogical experiments in adaptive e-learning and is therefore designed for users without education in computer science. The Virtual Teacher was used in dissertation theses of two students, who executed two pedagogical experiments. This paper also describes the phase of simulating and modeling of the theoretically prepared adaptive process in the modeling tool, which has all the required parameters and has been created especially for the occasion. The experiments are being conducted on groups of virtual students and by using a virtual study material.

  7. 33 CFR 67.35-10 - Private aids to navigation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Private aids to navigation. 67.35-10 Section 67.35-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Applications §...

  8. 33 CFR 401.54 - Interference with navigation aids.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Interference with navigation aids. 401.54 Section 401.54 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION... with navigation aids. (a) Aids to navigation shall not be interfered with or used as moorings. (b)...

  9. 33 CFR 401.54 - Interference with navigation aids.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Interference with navigation aids. 401.54 Section 401.54 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION... with navigation aids. (a) Aids to navigation shall not be interfered with or used as moorings. (b)...

  10. 33 CFR 67.35-10 - Private aids to navigation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Private aids to navigation. 67.35-10 Section 67.35-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Applications §...

  11. 33 CFR 67.35-10 - Private aids to navigation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Private aids to navigation. 67.35-10 Section 67.35-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Applications §...

  12. 33 CFR 401.54 - Interference with navigation aids.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Interference with navigation aids. 401.54 Section 401.54 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION... with navigation aids. (a) Aids to navigation shall not be interfered with or used as moorings. (b)...

  13. 33 CFR 67.35-10 - Private aids to navigation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Private aids to navigation. 67.35-10 Section 67.35-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Applications §...

  14. 33 CFR 401.54 - Interference with navigation aids.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Interference with navigation aids. 401.54 Section 401.54 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION... with navigation aids. (a) Aids to navigation shall not be interfered with or used as moorings. (b)...

  15. 33 CFR 401.54 - Interference with navigation aids.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Interference with navigation aids. 401.54 Section 401.54 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION... with navigation aids. (a) Aids to navigation shall not be interfered with or used as moorings. (b)...

  16. 33 CFR 67.35-10 - Private aids to navigation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Private aids to navigation. 67.35-10 Section 67.35-10 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY AIDS TO NAVIGATION AIDS TO NAVIGATION ON ARTIFICIAL ISLANDS AND FIXED STRUCTURES Applications §...

  17. 33 CFR 164.13 - Navigation underway: tankers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Navigation underway: tankers. 164.13 Section 164.13 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.13 Navigation underway:...

  18. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  19. 33 CFR 164.11 - Navigation under way: General.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Navigation under way: General. 164.11 Section 164.11 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.11 Navigation under way:...

  20. 33 CFR 164.11 - Navigation under way: General.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Navigation under way: General. 164.11 Section 164.11 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.11 Navigation under way:...

  1. 33 CFR 164.11 - Navigation under way: General.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Navigation under way: General. 164.11 Section 164.11 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.11 Navigation under way:...

  2. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  3. 33 CFR 164.13 - Navigation underway: tankers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Navigation underway: tankers. 164.13 Section 164.13 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.13 Navigation underway:...

  4. 33 CFR 164.13 - Navigation underway: tankers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Navigation underway: tankers. 164.13 Section 164.13 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.13 Navigation underway:...

  5. 33 CFR 164.13 - Navigation underway: tankers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Navigation underway: tankers. 164.13 Section 164.13 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.13 Navigation underway:...

  6. 33 CFR 164.11 - Navigation under way: General.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Navigation under way: General. 164.11 Section 164.11 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.11 Navigation under way:...

  7. 33 CFR 263.21 - Small navigation project authority.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Small navigation project authority. 263.21 Section 263.21 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE CONTINUING AUTHORITIES PROGRAMS Navigation Policy § 263.21 Small navigation...

  8. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  9. 33 CFR 164.13 - Navigation underway: tankers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Navigation underway: tankers. 164.13 Section 164.13 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.13 Navigation underway:...

  10. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under...

  11. 33 CFR 164.78 - Navigation under way: Towing vessels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Navigation under way: Towing vessels. 164.78 Section 164.78 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY NAVIGATION SAFETY REGULATIONS § 164.78 Navigation under way: Towing vessels. (a) The owner, master,...

  12. 33 CFR 162.240 - Tongass Narrows, Alaska; navigation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Tongass Narrows, Alaska; navigation. 162.240 Section 162.240 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY INLAND WATERWAYS NAVIGATION REGULATIONS § 162.240 Tongass Narrows, Alaska; navigation. (a)...

  13. 33 CFR 263.21 - Small navigation project authority.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Small navigation project authority. 263.21 Section 263.21 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE CONTINUING AUTHORITIES PROGRAMS Navigation Policy § 263.21 Small navigation project authority. (a) Legislative...

  14. WeaVR: a self-contained and wearable immersive virtual environment simulation system.

    PubMed

    Hodgson, Eric; Bachmann, Eric R; Vincent, David; Zmuda, Michael; Waller, David; Calusdian, James

    2015-03-01

    We describe WeaVR, a computer simulation system that takes virtual reality technology beyond specialized laboratories and research sites and makes it available in any open space, such as a gymnasium or a public park. Novel hardware and software systems enable HMD-based immersive virtual reality simulations to be conducted in any arbitrary location, with no external infrastructure and little-to-no setup or site preparation. The ability of the WeaVR system to provide realistic motion-tracked navigation for users, to improve the study of large-scale navigation, and to generate usable behavioral data is shown in three demonstrations. First, participants navigated through a full-scale virtual grocery store while physically situated in an open grass field. Trajectory data are presented for both normal tracking and for tracking during the use of redirected walking that constrained users to a predefined area. Second, users followed a straight path within a virtual world for distances of up to 2 km while walking naturally and being redirected to stay within the field, demonstrating the ability of the system to study large-scale navigation by simulating virtual worlds that are potentially unlimited in extent. Finally, the portability and pedagogical implications of this system were demonstrated by taking it to a regional high school for live use by a computer science class on their own school campus. PMID:24737097

  15. Preoperative indicators of clinical outcome following stereotaxic pallidotomy.

    PubMed

    Kazumata, K; Antonini, A; Dhawan, V; Moeller, J R; Alterman, R L; Kelly, P; Sterio, D; Fazzini, E; Beric, A; Eidelberg, D

    1997-10-01

    We assessed the utility of preoperative clinical assessment and functional brain imaging with 18F-fluorodeoxyglucose (FDG) and positron emission tomography (PET) in predicting the clinical outcome of stereotaxic pallidotomy for the treatment of advanced Parkinson's disease (PD). Twenty-two PD patients undergoing posteroventral pallidotomy were assessed preoperatively with the Core Assessment Program for Intracerebral Transplantation (CAPIT) ratings measured on and off levodopa; quantitative FDG/PET was also performed before surgery. Preoperative clinical and metabolic measurements were correlated with changes in off-state CAPIT ratings determined 3 months after surgery. Clinical outcome following pallidotomy was also correlated with intraoperative measures of spontaneous pallidal single-unit activity as well as postoperative MRI measurements of lesion volume and location. We found that unilateral pallidotomy resulted in variable clinical improvement in off-state CAPIT scores for the contralateral limbs (mean change 30.9 +/- 15.5%). Postoperative MRI revealed that pallidotomy lesions were comparable in location and volume across the patients. Clinical outcome following surgery correlated significantly with preoperative measures of CAPIT score change with levodopa administration (r = 0.60, p < 0.005) and with preoperative FDG/PET measurements of lentiform glucose metabolism (r = 0.71, p < 0.0005). Operative outcome did not correlate with intraoperative measures of spontaneous pallidal neuronal firing rate. We conclude that preoperative measurements of lentiform glucose metabolism and levodopa responsiveness may be useful indicators of motor improvement following pallidotomy. Both preoperative quantitative measures, either singly or in combination, may be helpful in selecting optimal candidates for surgery. PMID:9339694

  16. Screening and dotting virtual slides: A new challenge for cytotechnologists.

    PubMed

    Khalbuss, Walid E; Cuda, Jackie; Cucoranu, Ioan C

    2013-01-01

    Digital images are increasingly being used in cytopathology. Whole-slide imaging (WSI) is a digital imaging modality that uses computerized technology to scan and convert entire cytology glass slides into digital images that can be viewed on a digital display using the image viewer software. Digital image acquisition of cytology glass slides has improved significantly over the years due to the use of liquid-based preparations and advances in WSI scanning technology such as automatic multipoint pre-scan focus technology or z-stack scanning technology. Screening cytotechnologists are responsible for every cell that is present on an imaged slide. One of the challenges users have to overcome is to establish a technique to review systematically the entire imaged slide and to dot selected abnormal or significant findings. The scope of this article is to review the current user interface technology available for virtual slide navigation when screening digital slides in cytology. WSI scanner vendors provide tools, built into the image viewer software that allow for a more systematic navigation of the virtual slides, such as auto-panning, keyboard-controlled slide navigation and track map. Annotation tools can improve communication between the screener and the final reviewer or can be used for education. The tracking functionality allows recording of the WSI navigation process and provides a mechanism for confirmation of slide coverage by the screening cytotechnologist as well as a useful tool for quality assurance. As the WSI technology matures, additional features and tools to support navigation of a cytology virtual slide are anticipated. PMID:24379891

  17. Screening and dotting virtual slides: A new challenge for cytotechnologists

    PubMed Central

    Khalbuss, Walid E.; Cuda, Jackie; Cucoranu, Ioan C.

    2013-01-01

    Digital images are increasingly being used in cytopathology. Whole-slide imaging (WSI) is a digital imaging modality that uses computerized technology to scan and convert entire cytology glass slides into digital images that can be viewed on a digital display using the image viewer software. Digital image acquisition of cytology glass slides has improved significantly over the years due to the use of liquid-based preparations and advances in WSI scanning technology such as automatic multipoint pre-scan focus technology or z-stack scanning technology. Screening cytotechnologists are responsible for every cell that is present on an imaged slide. One of the challenges users have to overcome is to establish a technique to review systematically the entire imaged slide and to dot selected abnormal or significant findings. The scope of this article is to review the current user interface technology available for virtual slide navigation when screening digital slides in cytology. WSI scanner vendors provide tools, built into the image viewer software that allow for a more systematic navigation of the virtual slides, such as auto-panning, keyboard-controlled slide navigation and track map. Annotation tools can improve communication between the screener and the final reviewer or can be used for education. The tracking functionality allows recording of the WSI navigation process and provides a mechanism for confirmation of slide coverage by the screening cytotechnologist as well as a useful tool for quality assurance. As the WSI technology matures, additional features and tools to support navigation of a cytology virtual slide are anticipated. PMID:24379891

  18. Virtual Worlds, Virtual Literacy: An Educational Exploration

    ERIC Educational Resources Information Center

    Stoerger, Sharon

    2008-01-01

    Virtual worlds enable students to learn through seeing, knowing, and doing within visually rich and mentally engaging spaces. Rather than reading about events, students become part of the events through the adoption of a pre-set persona. Along with visual feedback that guides the players' activities and the development of visual skills, visual…

  19. NAVIGATION PERFORMANCE IN HIGH EARTH ORBITS USING NAVIGATOR GPS RECEIVER

    NASA Technical Reports Server (NTRS)

    Bamford, William; Naasz, Bo; Moreau, Michael C.

    2006-01-01

    NASA GSFC has developed a GPS receiver that can acquire and track GPS signals with sensitivity significantly lower than conventional GPS receivers. This opens up the possibility of using GPS based navigation for missions in high altitude orbit, such as Geostationary Operational Environmental Satellites (GOES) in a geostationary orbit, and the Magnetospheric MultiScale (MMS) Mission, in highly eccentric orbits extending to 12 Earth radii and higher. Indeed much research has been performed to study the feasibility of using GPS navigation in high Earth orbits and the performance achievable. Recently, GSFC has conducted a series of hardware in-the-loop tests to assess the performance of this new GPS receiver in various high Earth orbits of interest. Tracking GPS signals to down to approximately 22-25 dB-Hz, including signals from the GPS transmitter side-lobes, steady-state navigation performance in a geostationary orbit is on the order of 10 meters. This paper presents the results of these tests, as well as sensitivity analysis to such factors as ionosphere masks, use of GPS side-lobe signals, and GPS receiver sensitivity.

  20. Virtual endoscopy in odontogenic sinus disease. Study technique and main pathological findings.

    PubMed

    Fanucci, Ezio; Leporace, Mario; Di Costanzo, Giuseppe; Mannino, Michela; Simonetti, Giovanni

    2004-09-01

    The use of CT scans in dental pathology is an established technique. The potential applications of Dentascan are further enhanced by the use of virtual navigation software, resulting in endoscopy-like imaging of the maxillary sinus, thus optimising both the diagnostic and therapeutic approach to sinus pathology of dental origin. The aim of this paper is to illustrate the technical-methodological aspects of maxillary sinus virtual endoscopy with Dentascan software and to document the most important and frequent diseases. PMID:15343137