Sample records for distributed block virtualization

  1. World Virtual Observatory Organization

    NASA Astrophysics Data System (ADS)

    Ignatyev, Mikhail; Pinigin, Gennadij

    On the base of experience of our Unoversity and Observatory we investigate the seven blocks model of virtual organization for consolidation of resources. This model consists of the next blocks: 1.Population-scientists students robots and agents. 2.Aspiration of population groups. 3.Territory. 4.Production. 5.Ecology and safety. 6.Finance. 7. External relations - input and output flows of population information resources.The world virtual observatory is the virtual world which consists of three groups of variables - appearances essences and structured uncertainty which defines the number and distribution of arbitrary coefficients in equivalent equations. The consolodation of recources permit to create the large telescopes with distributed structure on our planet and cosmos. Virtual instruments can have the best characteristics by means of collective effects which have investigated in our paper.

  2. Cognitive load in distributed and massed practice in virtual reality mastoidectomy simulation.

    PubMed

    Andersen, Steven Arild Wuyts; Mikkelsen, Peter Trier; Konge, Lars; Cayé-Thomasen, Per; Sørensen, Mads Sølvsten

    2016-02-01

    Cognitive load theory states that working memory is limited. This has implications for learning and suggests that reducing cognitive load (CL) could promote learning and skills acquisition. This study aims to explore the effect of repeated practice and simulator-integrated tutoring on CL in virtual reality (VR) mastoidectomy simulation. Prospective trial. Forty novice medical students performed 12 repeated virtual mastoidectomy procedures in the Visible Ear Simulator: 21 completed distributed practice with practice blocks spaced in time and 19 participants completed massed practice (all practices performed in 1 day). Participants were randomized for tutoring with the simulator-integrated tutor function. Cognitive load was estimated by measuring reaction time in a secondary task. Data were analyzed using linear mixed models for repeated measurements. The mean reaction time increased by 37% during the procedure compared with baseline, demonstrating that the procedure placed substantial cognitive demands. Repeated practice significantly lowered CL in the distributed practice group but not in massed practice group. In addition, CL was found to be further increased by 10.3% in the later and more complex stages of the procedure. The simulator-integrated tutor function did not have an impact on CL. Distributed practice decreased CL in repeated VR mastoidectomy training more consistently than was seen in massed practice. This suggests a possible effect of skills and memory consolidation occurring over time. To optimize technical skills learning, training should be organized as time-distributed practice rather than as a massed block of practice, which is common in skills-training courses. N/A. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  3. Distributed virtual environment for emergency medical training

    NASA Astrophysics Data System (ADS)

    Stytz, Martin R.; Banks, Sheila B.; Garcia, Brian W.; Godsell-Stytz, Gayl M.

    1997-07-01

    In many professions where individuals must work in a team in a high stress environment to accomplish a time-critical task, individual and team performance can benefit from joint training using distributed virtual environments (DVEs). One professional field that lacks but needs a high-fidelity team training environment is the field of emergency medicine. Currently, emergency department (ED) medical personnel train by using words to create a metal picture of a situation for the physician and staff, who then cooperate to solve the problems portrayed by the word picture. The need in emergency medicine for realistic virtual team training is critical because ED staff typically encounter rarely occurring but life threatening situations only once in their careers and because ED teams currently have no realistic environment in which to practice their team skills. The resulting lack of experience and teamwork makes diagnosis and treatment more difficult. Virtual environment based training has the potential to redress these shortfalls. The objective of our research is to develop a state-of-the-art virtual environment for emergency medicine team training. The virtual emergency room (VER) allows ED physicians and medical staff to realistically prepare for emergency medical situations by performing triage, diagnosis, and treatment on virtual patients within an environment that provides them with the tools they require and the team environment they need to realistically perform these three tasks. There are several issues that must be addressed before this vision is realized. The key issues deal with distribution of computations; the doctor and staff interface to the virtual patient and ED equipment; the accurate simulation of individual patient organs' response to injury, medication, and treatment; and an accurate modeling of the symptoms and appearance of the patient while maintaining a real-time interaction capability. Our ongoing work addresses all of these issues. In this

  4. Evidence of Blocking with Geometric Cues in a Virtual Watermaze

    ERIC Educational Resources Information Center

    Redhead, Edward S.; Hamilton, Derek A.

    2009-01-01

    Three computer based experiments, testing human participants in a non-immersive virtual watermaze task, used a blocking design to assess whether two sets of geometric cues would compete in a manner described by associative models of learning. In stage 1, participants were required to discriminate between visually distinct platforms. In stage 2,…

  5. Exploiting virtual synchrony in distributed systems

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.; Joseph, Thomas A.

    1987-01-01

    Applications of a virtually synchronous environment are described for distributed programming, which underlies a collection of distributed programming tools in the ISIS2 system. A virtually synchronous environment allows processes to be structured into process groups, and makes events like broadcasts to the group as an entity, group membership changes, and even migration of an activity from one place to another appear to occur instantaneously, in other words, synchronously. A major advantage to this approach is that many aspects of a distributed application can be treated independently without compromising correctness. Moreover, user code that is designed as if the system were synchronous can often be executed concurrently. It is argued that this approach to building distributed and fault tolerant software is more straightforward, more flexible, and more likely to yield correct solutions than alternative approaches.

  6. Guidelines for developing distributed virtual environment applications

    NASA Astrophysics Data System (ADS)

    Stytz, Martin R.; Banks, Sheila B.

    1998-08-01

    We have conducted a variety of projects that served to investigate the limits of virtual environments and distributed virtual environment (DVE) technology for the military and medical professions. The projects include an application that allows the user to interactively explore a high-fidelity, dynamic scale model of the Solar System and a high-fidelity, photorealistic, rapidly reconfigurable aircraft simulator. Additional projects are a project for observing, analyzing, and understanding the activity in a military distributed virtual environment, a project to develop a distributed threat simulator for training Air Force pilots, a virtual spaceplane to determine user interface requirements for a planned military spaceplane system, and an automated wingman for use in supplementing or replacing human-controlled systems in a DVE. The last two projects are a virtual environment user interface framework; and a project for training hospital emergency department personnel. In the process of designing and assembling the DVE applications in support of these projects, we have developed rules of thumb and insights into assembling DVE applications and the environment itself. In this paper, we open with a brief review of the applications that were the source for our insights and then present the lessons learned as a result of these projects. The lessons we have learned fall primarily into five areas. These areas are requirements development, software architecture, human-computer interaction, graphical database modeling, and construction of computer-generated forces.

  7. Distributed Virtual System (DIVIRS) project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, B. Clifford

    1993-01-01

    As outlined in the continuation proposal 92-ISI-50R (revised) on NASA cooperative agreement NCC 2-539, the investigators are developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to develop and execute parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; developing communications routines that support the abstractions implemented; continuing the development of file and information systems based on the Virtual System Model; and incorporating appropriate security measures to allow the mechanisms developed to be used on an open network. The goal throughout the work is to provide a uniform model that can be applied to both parallel and distributed systems. The authors believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. The work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  8. Running a distributed virtual observatory: U.S. Virtual Astronomical Observatory operations

    NASA Astrophysics Data System (ADS)

    McGlynn, Thomas A.; Hanisch, Robert J.; Berriman, G. Bruce; Thakar, Aniruddha R.

    2012-09-01

    Operation of the US Virtual Astronomical Observatory shares some issues with modern physical observatories, e.g., intimidating data volumes and rapid technological change, and must also address unique concerns like the lack of direct control of the underlying and scattered data resources, and the distributed nature of the observatory itself. In this paper we discuss how the VAO has addressed these challenges to provide the astronomical community with a coherent set of science-enabling tools and services. The distributed nature of our virtual observatory-with data and personnel spanning geographic, institutional and regime boundaries-is simultaneously a major operational headache and the primary science motivation for the VAO. Most astronomy today uses data from many resources. Facilitation of matching heterogeneous datasets is a fundamental reason for the virtual observatory. Key aspects of our approach include continuous monitoring and validation of VAO and VO services and the datasets provided by the community, monitoring of user requests to optimize access, caching for large datasets, and providing distributed storage services that allow user to collect results near large data repositories. Some elements are now fully implemented, while others are planned for subsequent years. The distributed nature of the VAO requires careful attention to what can be a straightforward operation at a conventional observatory, e.g., the organization of the web site or the collection and combined analysis of logs. Many of these strategies use and extend protocols developed by the international virtual observatory community. Our long-term challenge is working with the underlying data providers to ensure high quality implementation of VO data access protocols (new and better 'telescopes'), assisting astronomical developers to build robust integrating tools (new 'instruments'), and coordinating with the research community to maximize the science enabled.

  9. Distributed Virtual System (DIVIRS) Project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, B. Clifford

    1993-01-01

    As outlined in our continuation proposal 92-ISI-50R (revised) on contract NCC 2-539, we are (1) developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to program parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; (2) developing communications routines that support the abstractions implemented in item one; (3) continuing the development of file and information systems based on the virtual system model; and (4) incorporating appropriate security measures to allow the mechanisms developed in items 1 through 3 to be used on an open network. The goal throughout our work is to provide a uniform model that can be applied to both parallel and distributed systems. We believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. Our work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  10. DIstributed VIRtual System (DIVIRS) project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, B. Clifford

    1994-01-01

    As outlined in our continuation proposal 92-ISI-. OR (revised) on NASA cooperative agreement NCC2-539, we are (1) developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to develop and execute parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; (2) developing communications routines that support the abstractions implemented in item one; (3) continuing the development of file and information systems based on the Virtual System Model; and (4) incorporating appropriate security measures to allow the mechanisms developed in items 1 through 3 to be used on an open network. The goal throughout our work is to provide a uniform model that can be applied to both parallel and distributed systems. We believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. Our work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  11. DIstributed VIRtual System (DIVIRS) project

    NASA Technical Reports Server (NTRS)

    Schorr, Herbert; Neuman, Clifford B.

    1995-01-01

    As outlined in our continuation proposal 92-ISI-50R (revised) on NASA cooperative agreement NCC2-539, we are (1) developing software, including a system manager and a job manager, that will manage available resources and that will enable programmers to develop and execute parallel applications in terms of a virtual configuration of processors, hiding the mapping to physical nodes; (2) developing communications routines that support the abstractions implemented in item one; (3) continuing the development of file and information systems based on the Virtual System Model; and (4) incorporating appropriate security measures to allow the mechanisms developed in items 1 through 3 to be used on an open network. The goal throughout our work is to provide a uniform model that can be applied to both parallel and distributed systems. We believe that multiprocessor systems should exist in the context of distributed systems, allowing them to be more easily shared by those that need them. Our work provides the mechanisms through which nodes on multiprocessors are allocated to jobs running within the distributed system and the mechanisms through which files needed by those jobs can be located and accessed.

  12. [Distribution of virtual water of crops in Beijing].

    PubMed

    Wang, Hong-Rui; Dong, Yan-Yan; Wang, Jun-Hong; Wang, Yan; Han, Zhao-Xing

    2007-11-01

    Virtual water content of grains and vegetables in Beijing's districts is calculated and analyzed for many years by irrigating water quota method, which is compared with the distribution and exploitation of groundwater in Beijing. The results indicate the virtual water content of grains shows a downward trend in all the districts, but the grain production in Yanqing district brings great pressure to the local groundwater. Secondly, the virtual water content of vegetables shows an upward trend in Shunyi District, Daxing district and Pinggu District and is accounting for more and more gradually. Thirdly, the total virtual water volume of grains is decreasing, and the total virtual water volume of vegetables is increasing and the total virtual water volume of crops in Beijing is reducing in recent years, which corresponds with the structural adjustment of policies.

  13. Digitization of Blocks and Virtual Anastylosis of AN Antique Facade in Pont-Sainte (france)

    NASA Astrophysics Data System (ADS)

    Alby, E.; Grussenmeyer, P.; Bitard, L.; Guillemin, S.; Brunet-Gaston, V.; Gaston, C.; Rougier, R.

    2017-08-01

    This paper is dedicated to the digitization of blocks and virtual anastylosis of an antique façade in Pont-Sainte-Maxence (France). In 2014 during the construction of a shopping center, the National Institute for Preventive Archaeological Research (INRAP) discovered a Gallo-Roman site from the 2nd century AD. The most interesting part of the site for the study is a façade of 70 meters long by nearly 10 meters high. The state of the conservation of the blocks of the façade makes them exceptional due to the question raised by the collapse. Representative and symbolic blocks of this building have been selected for a virtual anastylosis study. The blocks discovered belong to different types: decorated architectural blocks, monumental statuary elements and details of very fine decorations. The digital reproduction of the façade will facilitate the formulation of hypothesis for the collapse of the structure. The Photogrammetry and Geomatics Group from INSA Strasbourg is in charge of the digitization, the anastylosis and the development of exploratory methods for understanding the ruin of the façade. To develop the three-dimensional model of the facade, approximately 70 blocks of various dimensions were chosen by the archaeologists. The choice of the digitization technique is made according to the following pragmatic criterion: the movable objects are acquired with a scan-arm or a hand-held scanner in the laboratory and the largest blocks are recorded by photogrammetry at the repository near Paris. The expected types of deliverables are multiple: very accurate 3D models with the most faithful representation to document the objects in the best way and with optimized size model allowing easy handling during anastylosis tests. The visual aspect of the models is also a very important issue. Indeed, textures from photos are an excellent way to bring about the realism of the virtual model, but fine details of the object are sometimes blurred by the uniformity of the color

  14. New database for improving virtual system “body-dress”

    NASA Astrophysics Data System (ADS)

    Yan, J. Q.; Zhang, S. C.; Kuzmichev, V. E.; Adolphe, D. C.

    2017-10-01

    The aim of this exploration is to develop a new database of solid algorithms and relations between the dress fit and the fabric mechanical properties, the pattern block construction for improving the reality of virtual system “body-dress”. In virtual simulation, the system “body-clothing” sometimes shown distinct results with reality, especially when important changes in pattern block and fabrics were involved. In this research, to enhance the simulation process, diverse fit parameters were proposed: bottom height of dress, angle of front center contours, air volume and its distribution between dress and dummy. Measurements were done and optimized by ruler, camera, 3D body scanner image processing software and 3D modeling software. In the meantime, pattern block indexes were measured and fabric properties were tested by KES. Finally, the correlation and linear regression equations between indexes of fabric properties, pattern blocks and fit parameters were investigated. In this manner, new database could be extended in programming modules of virtual design for more realistic results.

  15. Distributed collaborative environments for virtual capability-based planning

    NASA Astrophysics Data System (ADS)

    McQuay, William K.

    2003-09-01

    Distributed collaboration is an emerging technology that will significantly change how decisions are made in the 21st century. Collaboration involves two or more geographically dispersed individuals working together to share and exchange data, information, knowledge, and actions. The marriage of information, collaboration, and simulation technologies provides the decision maker with a collaborative virtual environment for planning and decision support. This paper reviews research that is focusing on the applying open standards agent-based framework with integrated modeling and simulation to a new Air Force initiative in capability-based planning and the ability to implement it in a distributed virtual environment. Virtual Capability Planning effort will provide decision-quality knowledge for Air Force resource allocation and investment planning including examining proposed capabilities and cost of alternative approaches, the impact of technologies, identification of primary risk drivers, and creation of executable acquisition strategies. The transformed Air Force business processes are enabled by iterative use of constructive and virtual modeling, simulation, and analysis together with information technology. These tools are applied collaboratively via a technical framework by all the affected stakeholders - warfighter, laboratory, product center, logistics center, test center, and primary contractor.

  16. Distributed deformation and block rotation in 3D

    NASA Technical Reports Server (NTRS)

    Scotti, Oona; Nur, Amos; Estevez, Raul

    1990-01-01

    The authors address how block rotation and complex distributed deformation in the Earth's shallow crust may be explained within a stationary regional stress field. Distributed deformation is characterized by domains of sub-parallel fault-bounded blocks. In response to the contemporaneous activity of neighboring domains some domains rotate, as suggested by both structural and paleomagnetic evidence. Rotations within domains are achieved through the contemporaneous slip and rotation of the faults and of the blocks they bound. Thus, in regions of distributed deformation, faults must remain active in spite of their poor orientation in the stress field. The authors developed a model that tracks the orientation of blocks and their bounding faults during rotation in a 3D stress field. In the model, the effective stress magnitudes of the principal stresses (sigma sub 1, sigma sub 2, and sigma sub 3) are controlled by the orientation of fault sets in each domain. Therefore, adjacent fault sets with differing orientations may be active and may display differing faulting styles, and a given set of faults may change its style of motion as it rotates within a stationary stress regime. The style of faulting predicted by the model depends on a dimensionless parameter phi = (sigma sub 2 - sigma sub 3)/(sigma sub 1 - sigma sub 3). Thus, the authors present a model for complex distributed deformation and complex offset history requiring neither geographical nor temporal changes in the stress regime. They apply the model to the Western Transverse Range domain of southern California. There, it is mechanically feasible for blocks and faults to have experienced up to 75 degrees of clockwise rotation in a phi = 0.1 strike-slip stress regime. The results of the model suggest that this domain may first have accommodated deformation along preexisting NNE-SSW faults, reactivated as normal faults. After rotation, these same faults became strike-slip in nature.

  17. Performance Studies on Distributed Virtual Screening

    PubMed Central

    Krüger, Jens; de la Garza, Luis; Kohlbacher, Oliver; Nagel, Wolfgang E.

    2014-01-01

    Virtual high-throughput screening (vHTS) is an invaluable method in modern drug discovery. It permits screening large datasets or databases of chemical structures for those structures binding possibly to a drug target. Virtual screening is typically performed by docking code, which often runs sequentially. Processing of huge vHTS datasets can be parallelized by chunking the data because individual docking runs are independent of each other. The goal of this work is to find an optimal splitting maximizing the speedup while considering overhead and available cores on Distributed Computing Infrastructures (DCIs). We have conducted thorough performance studies accounting not only for the runtime of the docking itself, but also for structure preparation. Performance studies were conducted via the workflow-enabled science gateway MoSGrid (Molecular Simulation Grid). As input we used benchmark datasets for protein kinases. Our performance studies show that docking workflows can be made to scale almost linearly up to 500 concurrent processes distributed even over large DCIs, thus accelerating vHTS campaigns significantly. PMID:25032219

  18. Exploiting Virtual Synchrony in Distributed Systems

    DTIC Science & Technology

    1987-02-01

    for distributed systems yield the best performance relative to the level of synchronization guaranteed by the primitive . A pro- grammer could then... synchronization facility. Semaphores Replicated binary and general semaphores . Monitors Monitor lock, condition variables and signals. Deadlock detection...We describe applications of a new software abstraction called the virtually synchronous process group. Such a group consists of a set of processes

  19. Distributing Variable Star Data to the Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Kinne, Richard C.; Templeton, M. R.; Henden, A. A.; Zografou, P.; Harbo, P.; Evans, J.; Rots, A. H.; LAZIO, J.

    2013-01-01

    Effective distribution of data is a core element of effective astronomy today. The AAVSO is the home of several different unique databases. The AAVSO International Database (AID) contains over a century of photometric and time-series data on thousands of individual variable stars comprising over 22 million observations. The AAVSO Photometric All-Sky Survey (APASS) is a new photometric catalog containing calibrated photometry in Johnson B, V and Sloan g', r' and i' filters for stars with magnitudes of 10 < V < 17. The AAVSO is partnering with researchers and technologists at the Virtual Astronomical Observatory (VAO) to solve the data distribution problem for these datasets by making them available via various VO tools. We give specific examples of how these data can be accessed through Virtual Observatory (VO) toolsets and utilized for astronomical research.

  20. MISR Center Block Time Tool

    Atmospheric Science Data Center

    2013-04-01

      MISR Center Block Time Tool The misr_time tool calculates the block center times for MISR Level 1B2 files. This is ... version of the IDL package or by using the IDL Virtual Machine application. The IDL Virtual Machine is bundled with IDL and is ...

  1. Learning Curves of Virtual Mastoidectomy in Distributed and Massed Practice.

    PubMed

    Andersen, Steven Arild Wuyts; Konge, Lars; Cayé-Thomasen, Per; Sørensen, Mads Sølvsten

    2015-10-01

    Repeated and deliberate practice is crucial in surgical skills training, and virtual reality (VR) simulation can provide self-directed training of basic surgical skills to meet the individual needs of the trainee. Assessment of the learning curves of surgical procedures is pivotal in understanding skills acquisition and best-practice implementation and organization of training. To explore the learning curves of VR simulation training of mastoidectomy and the effects of different practice sequences with the aim of proposing the optimal organization of training. A prospective trial with a 2 × 2 design was conducted at an academic teaching hospital. Participants included 43 novice medical students. Of these, 21 students completed time-distributed practice from October 14 to November 29, 2013, and a separate group of 19 students completed massed practice on May 16, 17, or 18, 2014. Data analysis was performed from June 6, 2014, to March 3, 2015. Participants performed 12 repeated virtual mastoidectomies using a temporal bone surgical simulator in either a distributed (practice blocks spaced in time) or massed (all practice in 1 day) training program with randomization for simulator-integrated tutoring during the first 5 sessions. Performance was assessed using a modified Welling Scale for final product analysis by 2 blinded senior otologists. Compared with the 19 students in the massed practice group, the 21 students in the distributed practice group were older (mean age, 25.1 years), more often male (15 [62%]), and had slightly higher mean gaming frequency (2.3 on a 1-5 Likert scale). Learning curves were established and distributed practice was found to be superior to massed practice, reported as mean end score (95% CI) of 15.7 (14.4-17.0) in distributed practice vs. 13.0 (11.9-14.1) with massed practice (P = .002). Simulator-integrated tutoring accelerated the initial performance, with mean score for tutored sessions of 14.6 (13.9-15.2) vs. 13.4 (12.8-14.0) for

  2. Deeply Virtual Exclusive Processes and Generalized Parton Distributions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    ,

    2011-06-01

    The goal of the comprehensive program in Deeply Virtual Exclusive Scattering at Jefferson Laboratory is to create transverse spatial images of quarks and gluons as a function of their longitudinal momentum fraction in the proton, the neutron, and in nuclei. These functions are the Generalized Parton Distributions (GPDs) of the target nucleus. Cross section measurements of the Deeply Virtual Compton Scattering (DVCS) reaction ep {yields} ep{gamma} in Hall A support the QCD factorization of the scattering amplitude for Q^2 {>=} 2 GeV^2. Quasi-free neutron-DVCS measurements on the Deuteron indicate sensitivity to the quark angular momentum sum rule. Fully exclusive H(e,more » e'p{gamma} ) measurements have been made in a wide kinematic range in CLAS with polarized beam, and with both unpolarized and longitudinally polarized targets. Existing models are qualitatively consistent with the JLab data, but there is a clear need for less constrained models. Deeply virtual vector meson production is studied in CLAS. The 12 GeV upgrade will be essential for for these channels. The {rho} and {omega} channels reactions offer the prospect of flavor sensitivity to the quark GPDs, while the {phi}-production channel is dominated by the gluon distribution.« less

  3. Dynamic shared state maintenance in distributed virtual environments

    NASA Astrophysics Data System (ADS)

    Hamza-Lup, Felix George

    Advances in computer networks and rendering systems facilitate the creation of distributed collaborative environments in which the distribution of information at remote locations allows efficient communication. Particularly challenging are distributed interactive Virtual Environments (VE) that allow knowledge sharing through 3D information. The purpose of this work is to address the problem of latency in distributed interactive VE and to develop a conceptual model for consistency maintenance in these environments based on the participant interaction model. An area that needs to be explored is the relationship between the dynamic shared state and the interaction with the virtual entities present in the shared scene. Mixed Reality (MR) and VR environments must bring the human participant interaction into the loop through a wide range of electronic motion sensors, and haptic devices. Part of the work presented here defines a novel criterion for categorization of distributed interactive VE and introduces, as well as analyzes, an adaptive synchronization algorithm for consistency maintenance in such environments. As part of the work, a distributed interactive Augmented Reality (AR) testbed and the algorithm implementation details are presented. Currently the testbed is part of several research efforts at the Optical Diagnostics and Applications Laboratory including 3D visualization applications using custom built head-mounted displays (HMDs) with optical motion tracking and a medical training prototype for endotracheal intubation and medical prognostics. An objective method using quaternion calculus is applied for the algorithm assessment. In spite of significant network latency, results show that the dynamic shared state can be maintained consistent at multiple remotely located sites. In further consideration of the latency problems and in the light of the current trends in interactive distributed VE applications, we propose a hybrid distributed system architecture for

  4. Modeling of luminance distribution in CAVE-type virtual reality systems

    NASA Astrophysics Data System (ADS)

    Meironke, Michał; Mazikowski, Adam

    2017-08-01

    At present, one of the most advanced virtual reality systems are CAVE-type (Cave Automatic Virtual Environment) installations. Such systems are usually consisted of four, five or six projection screens and in case of six screens arranged in form of a cube. Providing the user with a high level of immersion feeling in such systems is largely dependent of optical properties of the system. The modeling of physical phenomena plays nowadays a huge role in the most fields of science and technology. It allows to simulate work of device without a need to make any changes in the physical constructions. In this paper distribution of luminance in CAVE-type virtual reality systems were modelled. Calculations were performed for the model of 6-walled CAVE-type installation, based on Immersive 3D Visualization Laboratory, situated at the Faculty of Electronics, Telecommunications and Informatics at the Gdańsk University of Technology. Tests have been carried out for two different scattering distribution of the screen material in order to check how these characteristicinfluence on the luminance distribution of the whole CAVE. The basis assumption and simplification of modeled CAVE-type installation and results were presented. The brief discussion about the results and usefulness of developed model were also carried out.

  5. Improvement of two-way continuous-variable quantum key distribution with virtual photon subtraction

    NASA Astrophysics Data System (ADS)

    Zhao, Yijia; Zhang, Yichen; Li, Zhengyu; Yu, Song; Guo, Hong

    2017-08-01

    We propose a method to improve the performance of two-way continuous-variable quantum key distribution protocol by virtual photon subtraction. The virtual photon subtraction implemented via non-Gaussian post-selection not only enhances the entanglement of two-mode squeezed vacuum state but also has advantages in simplifying physical operation and promoting efficiency. In two-way protocol, virtual photon subtraction could be applied on two sources independently. Numerical simulations show that the optimal performance of renovated two-way protocol is obtained with photon subtraction only used by Alice. The transmission distance and tolerable excess noise are improved by using the virtual photon subtraction with appropriate parameters. Moreover, the tolerable excess noise maintains a high value with the increase in distance so that the robustness of two-way continuous-variable quantum key distribution system is significantly improved, especially at long transmission distance.

  6. Web Service Distributed Management Framework for Autonomic Server Virtualization

    NASA Astrophysics Data System (ADS)

    Solomon, Bogdan; Ionescu, Dan; Litoiu, Marin; Mihaescu, Mircea

    Virtualization for the x86 platform has imposed itself recently as a new technology that can improve the usage of machines in data centers and decrease the cost and energy of running a high number of servers. Similar to virtualization, autonomic computing and more specifically self-optimization, aims to improve server farm usage through provisioning and deprovisioning of instances as needed by the system. Autonomic systems are able to determine the optimal number of server machines - real or virtual - to use at a given time, and add or remove servers from a cluster in order to achieve optimal usage. While provisioning and deprovisioning of servers is very important, the way the autonomic system is built is also very important, as a robust and open framework is needed. One such management framework is the Web Service Distributed Management (WSDM) system, which is an open standard of the Organization for the Advancement of Structured Information Standards (OASIS). This paper presents an open framework built on top of the WSDM specification, which aims to provide self-optimization for applications servers residing on virtual machines.

  7. Virtual time and time warp on the JPL hypercube. [operating system implementation for distributed simulation

    NASA Technical Reports Server (NTRS)

    Jefferson, David; Beckman, Brian

    1986-01-01

    This paper describes the concept of virtual time and its implementation in the Time Warp Operating System at the Jet Propulsion Laboratory. Virtual time is a distributed synchronization paradigm that is appropriate for distributed simulation, database concurrency control, real time systems, and coordination of replicated processes. The Time Warp Operating System is targeted toward the distributed simulation application and runs on a 32-node JPL Mark II Hypercube.

  8. ChemScreener: A Distributed Computing Tool for Scaffold based Virtual Screening.

    PubMed

    Karthikeyan, Muthukumarasamy; Pandit, Deepak; Vyas, Renu

    2015-01-01

    In this work we present ChemScreener, a Java-based application to perform virtual library generation combined with virtual screening in a platform-independent distributed computing environment. ChemScreener comprises a scaffold identifier, a distinct scaffold extractor, an interactive virtual library generator as well as a virtual screening module for subsequently selecting putative bioactive molecules. The virtual libraries are annotated with chemophore-, pharmacophore- and toxicophore-based information for compound prioritization. The hits selected can then be further processed using QSAR, docking and other in silico approaches which can all be interfaced within the ChemScreener framework. As a sample application, in this work scaffold selectivity, diversity, connectivity and promiscuity towards six important therapeutic classes have been studied. In order to illustrate the computational power of the application, 55 scaffolds extracted from 161 anti-psychotic compounds were enumerated to produce a virtual library comprising 118 million compounds (17 GB) and annotated with chemophore, pharmacophore and toxicophore based features in a single step which would be non-trivial to perform with many standard software tools today on libraries of this size.

  9. Virtual Solar Observatory Distributed Query Construction

    NASA Technical Reports Server (NTRS)

    Gurman, J. B.; Dimitoglou, G.; Bogart, R.; Davey, A.; Hill, F.; Martens, P.

    2003-01-01

    Through a prototype implementation (Tian et al., this meeting) the VSO has already demonstrated the capability of unifying geographically distributed data sources following the Web Services paradigm and utilizing mechanisms such as the Simple Object Access Protocol (SOAP). So far, four participating sites (Stanford, Montana State University, National Solar Observatory and the Solar Data Analysis Center) permit Web-accessible, time-based searches that allow browse access to a number of diverse data sets. Our latest work includes the extension of the simple, time-based queries to include numerous other searchable observation parameters. For VSO users, this extended functionality enables more refined searches. For the VSO, it is a proof of concept that more complex, distributed queries can be effectively constructed and that results from heterogeneous, remote sources can be synthesized and presented to users as a single, virtual data product.

  10. A virtual tour of virtual reality

    NASA Astrophysics Data System (ADS)

    Harris, Margaret

    2018-03-01

    Virtual-reality glasses might still be on the starting blocks, but plenty of companies are working on the technology. Margaret Harris tries on some examples at the Photonics West show in San Francisco

  11. Experiential Virtual Scenarios With Real-Time Monitoring (Interreality) for the Management of Psychological Stress: A Block Randomized Controlled Trial

    PubMed Central

    Pallavicini, Federica; Morganti, Luca; Serino, Silvia; Scaratti, Chiara; Briguglio, Marilena; Crifaci, Giulia; Vetrano, Noemi; Giulintano, Annunziata; Bernava, Giuseppe; Tartarisco, Gennaro; Pioggia, Giovanni; Raspelli, Simona; Cipresso, Pietro; Vigna, Cinzia; Grassi, Alessandra; Baruffi, Margherita; Wiederhold, Brenda; Riva, Giuseppe

    2014-01-01

    Background The recent convergence between technology and medicine is offering innovative methods and tools for behavioral health care. Among these, an emerging approach is the use of virtual reality (VR) within exposure-based protocols for anxiety disorders, and in particular posttraumatic stress disorder. However, no systematically tested VR protocols are available for the management of psychological stress. Objective Our goal was to evaluate the efficacy of a new technological paradigm, Interreality, for the management and prevention of psychological stress. The main feature of Interreality is a twofold link between the virtual and the real world achieved through experiential virtual scenarios (fully controlled by the therapist, used to learn coping skills and improve self-efficacy) with real-time monitoring and support (identifying critical situations and assessing clinical change) using advanced technologies (virtual worlds, wearable biosensors, and smartphones). Methods The study was designed as a block randomized controlled trial involving 121 participants recruited from two different worker populations—teachers and nurses—that are highly exposed to psychological stress. Participants were a sample of teachers recruited in Milan (Block 1: n=61) and a sample of nurses recruited in Messina, Italy (Block 2: n=60). Participants within each block were randomly assigned to the (1) Experimental Group (EG): n=40; B1=20, B2=20, which received a 5-week treatment based on the Interreality paradigm; (2) Control Group (CG): n=42; B1=22, B2=20, which received a 5-week traditional stress management training based on cognitive behavioral therapy (CBT); and (3) the Wait-List group (WL): n=39, B1=19, B2=20, which was reassessed and compared with the two other groups 5 weeks after the initial evaluation. Results Although both treatments were able to significantly reduce perceived stress better than WL, only EG participants reported a significant reduction (EG=12% vs CG=0

  12. The Integrated Distributed Virtual Research Network: An Introduction

    DTIC Science & Technology

    2014-06-01

    Tom Kile , Theron Trout, and Gary Cohn for their extensive contribution to this document to include reviews, comments, and edits, which contributed...to the quality of the document. The ARL Integrated Distributed Virtual Research Testbed (IDVRT) team, consisting of Alex Tarantin, Khoa Bui, Tom Kile ...n. Network Engineer (non-voting member) Tom Kile o. Network Engineer (non-voting member) Theron Trout p. Non-voting members (serving at the

  13. Virtual Plant Tissue: Building Blocks for Next-Generation Plant Growth Simulation

    PubMed Central

    De Vos, Dirk; Dzhurakhalov, Abdiravuf; Stijven, Sean; Klosiewicz, Przemyslaw; Beemster, Gerrit T. S.; Broeckhove, Jan

    2017-01-01

    Motivation: Computational modeling of plant developmental processes is becoming increasingly important. Cellular resolution plant tissue simulators have been developed, yet they are typically describing physiological processes in an isolated way, strongly delimited in space and time. Results: With plant systems biology moving toward an integrative perspective on development we have built the Virtual Plant Tissue (VPTissue) package to couple functional modules or models in the same framework and across different frameworks. Multiple levels of model integration and coordination enable combining existing and new models from different sources, with diverse options in terms of input/output. Besides the core simulator the toolset also comprises a tissue editor for manipulating tissue geometry and cell, wall, and node attributes in an interactive manner. A parameter exploration tool is available to study parameter dependence of simulation results by distributing calculations over multiple systems. Availability: Virtual Plant Tissue is available as open source (EUPL license) on Bitbucket (https://bitbucket.org/vptissue/vptissue). The project has a website https://vptissue.bitbucket.io. PMID:28523006

  14. Distribution of Injectate and Sensory-Motor Blockade After Adductor Canal Block.

    PubMed

    Gautier, Philippe E; Hadzic, Admir; Lecoq, Jean-Pierre; Brichant, Jean Francois; Kuroda, Maxine M; Vandepitte, Catherine

    2016-01-01

    The analgesic efficacy reported for the adductor canal block may be related to the spread of local anesthetic outside the adductor canal. Fifteen patients undergoing knee surgery received ultrasound-guided injections of local anesthetic at the level of the adductor hiatus. Sensory-motor block and spread of contrast solution were assessed. Sensation was rated as "markedly diminished" or "absent" in the saphenous nerve distribution and "slightly diminished" in the sciatic nerve territory without motor deficits. Contrast solution was found in the popliteal fossa. The spread of injectate to the popliteal fossa may contribute to the analgesic efficacy of adductor canal block.

  15. The Impact of Virtual Collaboration and Collaboration Technologies on Knowledge Transfer and Team Performance in Distributed Organizations

    ERIC Educational Resources Information Center

    Ngoma, Ngoma Sylvestre

    2013-01-01

    Virtual teams are increasingly viewed as a powerful determinant of competitive advantage in geographically distributed organizations. This study was designed to provide insights into the interdependencies between virtual collaboration, collaboration technologies, knowledge transfer, and virtual team performance in an effort to understand whether…

  16. Research on Collaborative Technology in Distributed Virtual Reality System

    NASA Astrophysics Data System (ADS)

    Lei, ZhenJiang; Huang, JiJie; Li, Zhao; Wang, Lei; Cui, JiSheng; Tang, Zhi

    2018-01-01

    Distributed virtual reality technology applied to the joint training simulation needs the CSCW (Computer Supported Cooperative Work) terminal multicast technology to display and the HLA (high-level architecture) technology to ensure the temporal and spatial consistency of the simulation, in order to achieve collaborative display and collaborative computing. In this paper, the CSCW’s terminal multicast technology has been used to modify and expand the implementation framework of HLA. During the simulation initialization period, this paper has used the HLA statement and object management service interface to establish and manage the CSCW network topology, and used the HLA data filtering mechanism for each federal member to establish the corresponding Mesh tree. During the simulation running period, this paper has added a new thread for the RTI and the CSCW real-time multicast interactive technology into the RTI, so that the RTI can also use the window message mechanism to notify the application update the display screen. Through many applications of submerged simulation training in substation under the operation of large power grid, it is shown that this paper has achieved satisfactory training effect on the collaborative technology used in distributed virtual reality simulation.

  17. Block distributions on the lunar surface: A comparison between measurements obtained from surface and orbital photography

    NASA Technical Reports Server (NTRS)

    Cintala, Mark J.; Mcbride, Kathleen M.

    1995-01-01

    Among the hazards that must be negotiated by lunar-landing spacecraft are blocks on the surface of the Moon. Unfortunately, few data exist that can be used to evaluate the threat posed by such blocks to landing spacecraft. Perhaps the best information is that obtained from Surveyor photographs, but those data do not extend to the dimensions of the large blocks that would pose the greatest hazards. Block distributions in the vicinities of the Surveyor 1, 3, 6, and 7 sites have been determined from Lunar Orbiter photography and are presented here. Only large (i.e., greater than or equal to 2.5 m) blocks are measurable in these pictures, resulting in a size gap between the Surveyor and Lunar Orbiter distributions. Nevertheless, the orbital data are self-consistent, a claim supported by the similarity in behavior between the subsets of data from the Surveyor 1, 3, and 6 sites and by the good agreement in position (if not slopes) between the data obtained from the Surveyor 3 photography and those derived from the Lunar Orbiter photographs. Confidence in the results is also justified by the well-behaved distribution of large blocks at the surveyor site. Comparisons between the Surveyor distributions and those derived from the orbital photography permit these observations: (1) in all cases but that for Surveyor 3, the density of large blocks is overestimated by extrapolation of the Surveyor-derived trends; (2) the slopes of the Surveyor-derived distributions are consistently lower than those determined for the large blocks; and (3) these apparent disagreements could be mitigated if the overall shapes of the cumulative lunar block populations were nonlinear, allowing for different slopes over different size intervals. The relatively large gaps between the Surveyor-derived and Orbiter-derived data sets, however, do not permit a determination of those shapes.

  18. Exponential blocking-temperature distribution in ferritin extracted from magnetization measurements

    NASA Astrophysics Data System (ADS)

    Lee, T. H.; Choi, K.-Y.; Kim, G.-H.; Suh, B. J.; Jang, Z. H.

    2014-11-01

    We developed a direct method to extract the zero-field zero-temperature anisotropy energy barrier distribution of magnetic particles in the form of a blocking-temperature distribution. The key idea is to modify measurement procedures slightly to make nonequilibrium magnetization calculations (including the time evolution of magnetization) easier. We applied this method to the biomagnetic molecule ferritin and successfully reproduced field-cool magnetization by using the extracted distribution. We find that the resulting distribution is more like an exponential type and that the distribution cannot be correlated simply to the widely known log-normal particle-size distribution. The method also allows us to determine the values of the zero-temperature coercivity and Bloch coefficient, which are in good agreement with those determined from other techniques.

  19. A Proposal for the Distribution of Federal Block Grant Funds in Illinois.

    ERIC Educational Resources Information Center

    Hickrod, G. Alan; And Others

    It is proposed that federal block grants to Illinois be distributed to school districts according to four characteristics of those districts. Funds will be distributed inversely proportional to property valuation per pupil, directly proportional to percentage of minority children, directly proportional to percentage of poverty children (Title I…

  20. Managing distributed software development in the Virtual Astronomical Observatory

    NASA Astrophysics Data System (ADS)

    Evans, Janet D.; Plante, Raymond L.; Boneventura, Nina; Busko, Ivo; Cresitello-Dittmar, Mark; D'Abrusco, Raffaele; Doe, Stephen; Ebert, Rick; Laurino, Omar; Pevunova, Olga; Refsdal, Brian; Thomas, Brian

    2012-09-01

    The U.S. Virtual Astronomical Observatory (VAO) is a product-driven organization that provides new scientific research capabilities to the astronomical community. Software development for the VAO follows a lightweight framework that guides development of science applications and infrastructure. Challenges to be overcome include distributed development teams, part-time efforts, and highly constrained schedules. We describe the process we followed to conquer these challenges while developing Iris, the VAO application for analysis of 1-D astronomical spectral energy distributions (SEDs). Iris was successfully built and released in less than a year with a team distributed across four institutions. The project followed existing International Virtual Observatory Alliance inter-operability standards for spectral data and contributed a SED library as a by-product of the project. We emphasize lessons learned that will be folded into future development efforts. In our experience, a well-defined process that provides guidelines to ensure the project is cohesive and stays on track is key to success. Internal product deliveries with a planned test and feedback loop are critical. Release candidates are measured against use cases established early in the process, and provide the opportunity to assess priorities and make course corrections during development. Also key is the participation of a stakeholder such as a lead scientist who manages the technical questions, advises on priorities, and is actively involved as a lead tester. Finally, frequent scheduled communications (for example a bi-weekly tele-conference) assure issues are resolved quickly and the team is working toward a common vision.

  1. Pacemaker rate and depolarization block in nigral dopamine neurons: a somatic sodium channel balancing act

    PubMed Central

    Tucker, Kristal R.; Huertas, Marco A.; Horn, John P.; Canavier, Carmen C.; Levitan, Edwin S.

    2012-01-01

    Midbrain dopamine (DA) neurons are slow intrinsic pacemakers that undergo depolarization (DP) block upon moderate stimulation. Understanding DP block is important because it has been correlated with the clinical efficacy of chronic antipsychotic drug treatment. Here we describe how voltage-gated sodium (NaV) channels regulate DP block and pacemaker activity in DA neurons of the substantia nigra using rat brain slices. The distribution, density and gating of NaV currents were manipulated by blocking native channels with tetrodotoxin and by creating virtual channels and anti-channels with dynamic clamp. Although action potentials initiate in the axon initial segment (AIS) and NaV channels are distributed in multiple dendrites, selective reduction of NaV channel activity in the soma was sufficient to decrease pacemaker frequency and increase susceptibility to DP block. Conversely, increasing somatic NaV current density raised pacemaker frequency and lowered susceptibility to DP block. Finally, when NaV currents were restricted to the soma, pacemaker activity occurred at abnormally high rates due to excessive local subthreshold NaV current. Together with computational simulations, these data show that both the slow pacemaker rate and the sensitivity to DP block that characterizes DA neurons result from the low density of somatic NaV channels. More generally, we conclude that the somatodendritic distribution of NaV channels is a major determinant of repetitive spiking frequency. PMID:23077037

  2. A Virtual Hosting Environment for Distributed Online Gaming

    NASA Astrophysics Data System (ADS)

    Brossard, David; Prieto Martinez, Juan Luis

    With enterprise boundaries becoming fuzzier, it’s become clear that businesses need to share resources, expose services, and interact in many different ways. In order to achieve such a distribution in a dynamic, flexible, and secure way, we have designed and implemented a virtual hosting environment (VHE) which aims at integrating business services across enterprise boundaries and virtualising the ICT environment within which these services operate in order to exploit economies of scale for the businesses as well as achieve shorter concept-to-market time scales. To illustrate the relevance of the VHE, we have applied it to the online gaming world. Online gaming is an early adopter of distributed computing and more than 30% of gaming developer companies, being aware of the shift, are focusing on developing high performance platforms for the new online trend.

  3. Addressing security issues related to virtual institute distributed activities

    NASA Astrophysics Data System (ADS)

    Stytz, Martin R.; Banks, Sheila B.

    2008-03-01

    One issue confounding the development and experimentation of distributed modeling and simulation environments is the inability of the project team to identify and collaborate with resources, both human and technical, from outside the United States. This limitation is especially significant within the human behavior representation area where areas such as cultural effects research and joint command team behavior modeling require the participation of various cultural and national representatives. To address this limitation, as well as other human behavior representation research issues, NATO Research and Technology Organization initiated a project to develop a NATO virtual institute that enables more effective and more collaborative research into human behavior representation. However, in building and operating a virtual institute one of the chief concerns must be the cyber security of the institute. Because the institute "exists" in cyberspace, all of its activities are susceptible to cyberattacks, subterfuge, denial of service and all of the vulnerabilities that networked computers must face. In our opinion, for the concept of virtual institutes to be successful and useful, their operations and services must be protected from the threats in the cyber environment. A key to developing the required protection is the development and promulgation of standards for cyber security. In this paper, we discuss the types of cyber standards that are required, how new internet technologies can be exploited and can benefit the promulgation, development, maintenance, and robustness of the standards. This paper is organized as follows. Section One introduces the concept of the virtual institutes, the expected benefits, and the motivation for our research and for research in this area. Section Two presents background material and a discussion of topics related to VIs, uman behavior and cultural modeling, and network-centric warfare. Section Three contains a discussion of the

  4. Slip-Size Distribution and Self-Organized Criticality in Block-Spring Models with Quenched Randomness

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Hidetsugu; Kadowaki, Shuntaro

    2017-07-01

    We study slowly pulling block-spring models in random media. Second-order phase transitions exist in a model pulled by a constant force in the case of velocity-strengthening friction. If external forces are slowly increased, nearly critical states are self-organized. Slips of various sizes occur, and the probability distributions of slip size roughly obey power laws. The exponent is close to that in the quenched Edwards-Wilkinson model. Furthermore, the slip-size distributions are investigated in cases of Coulomb friction, velocity-weakening friction, and two-dimensional block-spring models.

  5. Drift-insensitive distributed calibration of probe microscope scanner in nanometer range: Virtual mode

    NASA Astrophysics Data System (ADS)

    Lapshin, Rostislav V.

    2016-08-01

    A method of distributed calibration of a probe microscope scanner is suggested. The main idea consists in a search for a net of local calibration coefficients (LCCs) in the process of automatic measurement of a standard surface, whereby each point of the movement space of the scanner can be characterized by a unique set of scale factors. Feature-oriented scanning (FOS) methodology is used as a basis for implementation of the distributed calibration permitting to exclude in situ the negative influence of thermal drift, creep and hysteresis on the obtained results. Possessing the calibration database enables correcting in one procedure all the spatial systematic distortions caused by nonlinearity, nonorthogonality and spurious crosstalk couplings of the microscope scanner piezomanipulators. To provide high precision of spatial measurements in nanometer range, the calibration is carried out using natural standards - constants of crystal lattice. One of the useful modes of the developed calibration method is a virtual mode. In the virtual mode, instead of measurement of a real surface of the standard, the calibration program makes a surface image ;measurement; of the standard, which was obtained earlier using conventional raster scanning. The application of the virtual mode permits simulation of the calibration process and detail analysis of raster distortions occurring in both conventional and counter surface scanning. Moreover, the mode allows to estimate the thermal drift and the creep velocities acting while surface scanning. Virtual calibration makes possible automatic characterization of a surface by the method of scanning probe microscopy (SPM).

  6. Chain end distribution of block copolymer in two-dimensional microphase-separated structure studied by scanning near-field optical microscopy.

    PubMed

    Sekine, Ryojun; Aoki, Hiroyuki; Ito, Shinzaburo

    2009-10-01

    The chain end distribution of a block copolymer in a two-dimensional microphase-separated structure was studied by scanning near-field optical microscopy (SNOM). In the monolayer of poly(octadecyl methacrylate)-block-poly(isobutyl methacrylate) (PODMA-b-PiBMA), the free end of the PiBMA subchain was directly observed by SNOM, and the spatial distributions of the whole block and the chain end are examined and compared with the convolution of the point spread function of the microscope and distribution function of the model structures. It was found that the chain end distribution of the block copolymer confined in two dimensions has a peak near the domain center, being concentrated in the narrower region, as compared with three-dimensional systems.

  7. Spatial distribution of block falls using volumetric GIS-decision-tree models

    NASA Astrophysics Data System (ADS)

    Abdallah, C.

    2010-10-01

    Block falls are considered a significant aspect of surficial instability contributing to losses in land and socio-economic aspects through their damaging effects to natural and human environments. This paper predicts and maps the geographic distribution and volumes of block falls in central Lebanon using remote sensing, geographic information systems (GIS) and decision-tree modeling (un-pruned and pruned trees). Eleven terrain parameters (lithology, proximity to fault line, karst type, soil type, distance to drainage line, elevation, slope gradient, slope aspect, slope curvature, land cover/use, and proximity to roads) were generated to statistically explain the occurrence of block falls. The latter were discriminated using SPOT4 satellite imageries, and their dimensions were determined during field surveys. The un-pruned tree model based on all considered parameters explained 86% of the variability in field block fall measurements. Once pruned, it classifies 50% in block falls' volumes by selecting just four parameters (lithology, slope gradient, soil type, and land cover/use). Both tree models (un-pruned and pruned) were converted to quantitative 1:50,000 block falls' maps with different classes; starting from Nil (no block falls) to more than 4000 m 3. These maps are fairly matching with coincidence value equal to 45%; however, both can be used to prioritize the choice of specific zones for further measurement and modeling, as well as for land-use management. The proposed tree models are relatively simple, and may also be applied to other areas (i.e. the choice of un-pruned or pruned model is related to the availability of terrain parameters in a given area).

  8. Large-scale P2P network based distributed virtual geographic environment (DVGE)

    NASA Astrophysics Data System (ADS)

    Tan, Xicheng; Yu, Liang; Bian, Fuling

    2007-06-01

    Virtual Geographic Environment has raised full concern as a kind of software information system that helps us understand and analyze the real geographic environment, and it has also expanded to application service system in distributed environment--distributed virtual geographic environment system (DVGE), and gets some achievements. However, limited by the factor of the mass data of VGE, the band width of network, as well as numerous requests and economic, etc. DVGE still faces some challenges and problems which directly cause the current DVGE could not provide the public with high-quality service under current network mode. The Rapid development of peer-to-peer network technology has offered new ideas of solutions to the current challenges and problems of DVGE. Peer-to-peer network technology is able to effectively release and search network resources so as to realize efficient share of information. Accordingly, this paper brings forth a research subject on Large-scale peer-to-peer network extension of DVGE as well as a deep study on network framework, routing mechanism, and DVGE data management on P2P network.

  9. Iris: Constructing and Analyzing Spectral Energy Distributions with the Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Laurino, O.; Budynkiewicz, J.; Busko, I.; Cresitello-Dittmar, M.; D'Abrusco, R.; Doe, S.; Evans, J.; Pevunova, O.

    2014-05-01

    We present Iris 2.0, the latest release of the Virtual Astronomical Observatory application for building and analyzing Spectral Energy Distributions (SEDs). With Iris, users may read in and display SEDs inspect and edit any selection of SED data, fit models to SEDs in arbitrary spectral ranges, and calculate confidence limits on best-fit parameters. SED data may be loaded into the application from VOTable and FITS files compliant with the International Virtual Observatoy Alliance interoperable data models, or retrieved directly from NED or the Italian Space Agency Science Data Center; data in non-standard formats may also be converted within the application. Users may seamlessy exchange data between Iris and other Virtual Observatoy tools using the Simple Application Messaging Protocol. Iris 2.0 also provides a tool for redshifting, interpolating, and measuring integratd fluxes, and allows simple aperture corrections for individual points and SED segments. Custom Python functions, template models and template libraries may be imported into Iris for fitting SEDs. Iris may be extended through Java plugins; users can install third-party packages, or develop their own plugin using Iris' Software Development Kit. Iris 2.0 is available for Linux and Mac OS X systems.

  10. Research on distributed virtual reality system in electronic commerce

    NASA Astrophysics Data System (ADS)

    Xue, Qiang; Wang, Jiening; Sun, Jizhou

    2004-03-01

    In this paper, Distributed Virtual Reality (DVR) technology applied in Electronical Commerce (EC) is discussed. DVR has the capability of providing a new means for human being to recognize, analyze and resolve the large scale, complex problems, which makes it develop quickly in EC fields. The technology of CSCW (Computer Supported Cooperative Work) and middleware is introduced into the development of EC-DVR system to meet the need of a platform which can provide the necessary cooperation and communication services to avoid developing the basic module repeatedly. Finally, the paper gives a platform structure of EC-DVR system.

  11. Distributed interactive virtual environments for collaborative experiential learning and training independent of distance over Internet2.

    PubMed

    Alverson, Dale C; Saiki, Stanley M; Jacobs, Joshua; Saland, Linda; Keep, Marcus F; Norenberg, Jeffrey; Baker, Rex; Nakatsu, Curtis; Kalishman, Summers; Lindberg, Marlene; Wax, Diane; Mowafi, Moad; Summers, Kenneth L; Holten, James R; Greenfield, John A; Aalseth, Edward; Nickles, David; Sherstyuk, Andrei; Haines, Karen; Caudell, Thomas P

    2004-01-01

    Medical knowledge and skills essential for tomorrow's healthcare professionals continue to change faster than ever before creating new demands in medical education. Project TOUCH (Telehealth Outreach for Unified Community Health) has been developing methods to enhance learning by coupling innovations in medical education with advanced technology in high performance computing and next generation Internet2 embedded in virtual reality environments (VRE), artificial intelligence and experiential active learning. Simulations have been used in education and training to allow learners to make mistakes safely in lieu of real-life situations, learn from those mistakes and ultimately improve performance by subsequent avoidance of those mistakes. Distributed virtual interactive environments are used over distance to enable learning and participation in dynamic, problem-based, clinical, artificial intelligence rules-based, virtual simulations. The virtual reality patient is programmed to dynamically change over time and respond to the manipulations by the learner. Participants are fully immersed within the VRE platform using a head-mounted display and tracker system. Navigation, locomotion and handling of objects are accomplished using a joy-wand. Distribution is managed via the Internet2 Access Grid using point-to-point or multi-casting connectivity through which the participants can interact. Medical students in Hawaii and New Mexico (NM) participated collaboratively in problem solving and managing of a simulated patient with a closed head injury in VRE; dividing tasks, handing off objects, and functioning as a team. Students stated that opportunities to make mistakes and repeat actions in the VRE were extremely helpful in learning specific principles. VRE created higher performance expectations and some anxiety among VRE users. VRE orientation was adequate but students needed time to adapt and practice in order to improve efficiency. This was also demonstrated successfully

  12. Generalized parton distributions from deep virtual compton scattering at CLAS

    DOE PAGES

    Guidal, M.

    2010-04-24

    Here, we have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factorsmore » $$H_{Im}$$ and $$\\tilde{H}_{Im}$$ with uncertainties, in average, of the order of 30%.« less

  13. Virtual Reality simulator for dental anesthesia training in the inferior alveolar nerve block.

    PubMed

    Corrêa, Cléber Gimenez; Machado, Maria Aparecida de Andrade Moreira; Ranzini, Edith; Tori, Romero; Nunes, Fátima de Lourdes Santos

    2017-01-01

    This study shows the development and validation of a dental anesthesia-training simulator, specifically for the inferior alveolar nerve block (IANB). The system developed provides the tactile sensation of inserting a real needle in a human patient, using Virtual Reality (VR) techniques and a haptic device that can provide a perceived force feedback in the needle insertion task during the anesthesia procedure. To simulate a realistic anesthesia procedure, a Carpule syringe was coupled to a haptic device. The Volere method was used to elicit requirements from users in the Dentistry area; Repeated Measures Two-Way ANOVA (Analysis of Variance), Tukey post-hoc test and averages for the results' analysis. A questionnaire-based subjective evaluation method was applied to collect information about the simulator, and 26 people participated in the experiments (12 beginners, 12 at intermediate level, and 2 experts). The questionnaire included profile, preferences (number of viewpoints, texture of the objects, and haptic device handler), as well as visual (appearance, scale, and position of objects) and haptic aspects (motion space, tactile sensation, and motion reproduction). The visual aspect was considered appropriate and the haptic feedback must be improved, which the users can do by calibrating the virtual tissues' resistance. The evaluation of visual aspects was influenced by the participants' experience, according to ANOVA test (F=15.6, p=0.0002, with p<0.01). The user preferences were the simulator with two viewpoints, objects with texture based on images and the device with a syringe coupled to it. The simulation was considered thoroughly satisfactory for the anesthesia training, considering the needle insertion task, which includes the correct insertion point and depth, as well as the perception of tissues resistances during the insertion.

  14. Rapid prototyping, astronaut training, and experiment control and supervision: distributed virtual worlds for COLUMBUS, the European Space Laboratory module

    NASA Astrophysics Data System (ADS)

    Freund, Eckhard; Rossmann, Juergen

    2002-02-01

    In 2004, the European COLUMBUS Module is to be attached to the International Space Station. On the way to the successful planning, deployment and operation of the module, computer generated and animated models are being used to optimize performance. Under contract of the German Space Agency DLR, it has become IRF's task to provide a Projective Virtual Reality System to provide a virtual world built after the planned layout of the COLUMBUS module let astronauts and experimentators practice operational procedures and the handling of experiments. The key features of the system currently being realized comprise the possibility for distributed multi-user access to the virtual lab and the visualization of real-world experiment data. Through the capabilities to share the virtual world, cooperative operations can be practiced easily, but also trainers and trainees can work together more effectively sharing the virtual environment. The capability to visualize real-world data will be used to introduce measured data of experiments into the virtual world online in order to realistically interact with the science-reference model hardware: The user's actions in the virtual world are translated into corresponding changes of the inputs of the science reference model hardware; the measured data is than in turn fed back into the virtual world. During the operation of COLUMBUS, the capabilities for distributed access and the capabilities to visualize measured data through the use of metaphors and augmentations of the virtual world may be used to provide virtual access to the COLUMBUS module, e.g. via Internet. Currently, finishing touches are being put to the system. In November 2001 the virtual world shall be operational, so that besides the design and the key ideas, first experimental results can be presented.

  15. Block distributions on the lunar surface: A comparison between measurements obtained from surface and orbital photography

    NASA Technical Reports Server (NTRS)

    Cintala, Mark J.; Mcbride, Kathleen M.

    1994-01-01

    Enlargements of Lunar-Orbiter photography were used in conjunction with a digitizing tablet to collect the locations and dimensions of blocks surrounding the Surveyor 1, 3, 6, and 7 landing sites. Data were reduced to the location and the major axis of the visible portion of each block. Shadows sometimes made it difficult to assess whether the visible major axis corresponded with the actual principal dimension. These data were then correlated with the locations of major craters in the study areas, thus subdividing the data set into blocks obviously associated with craters and those in intercrater areas. A block was arbitrarily defined to be associated with a crater when its location was within 1.1 crater radii of the crater's center. Since this study was commissioned for the ultimate purpose of determining hazards to landing spacecraft, such a definition was deemed appropriate in defining block-related hazards associated with craters. Size distributions of smaller fragments as determined from Surveyor photography were obtained as measurements from graphical data. Basic comparisons were performed through use of cumulative frequency distributions identical to those applied to studies of crater-count data.

  16. Continuous-variable measurement-device-independent quantum key distribution with virtual photon subtraction

    NASA Astrophysics Data System (ADS)

    Zhao, Yijia; Zhang, Yichen; Xu, Bingjie; Yu, Song; Guo, Hong

    2018-04-01

    The method of improving the performance of continuous-variable quantum key distribution protocols by postselection has been recently proposed and verified. In continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocols, the measurement results are obtained from untrusted third party Charlie. There is still not an effective method of improving CV-MDI QKD by the postselection with untrusted measurement. We propose a method to improve the performance of coherent-state CV-MDI QKD protocol by virtual photon subtraction via non-Gaussian postselection. The non-Gaussian postselection of transmitted data is equivalent to an ideal photon subtraction on the two-mode squeezed vacuum state, which is favorable to enhance the performance of CV-MDI QKD. In CV-MDI QKD protocol with non-Gaussian postselection, two users select their own data independently. We demonstrate that the optimal performance of the renovated CV-MDI QKD protocol is obtained with the transmitted data only selected by Alice. By setting appropriate parameters of the virtual photon subtraction, the secret key rate and tolerable excess noise are both improved at long transmission distance. The method provides an effective optimization scheme for the application of CV-MDI QKD protocols.

  17. Estimate Soil Erodibility Factors Distribution for Maioli Block

    NASA Astrophysics Data System (ADS)

    Lee, Wen-Ying

    2014-05-01

    The natural conditions in Taiwan are poor. Because of the steep slopes, rushing river and fragile geology, soil erosion turn into a serious problem. Not only undermine the sloping landscape, but also created sediment disaster like that reservoir sedimentation, river obstruction…etc. Therefore, predict and control the amount of soil erosion has become an important research topic. Soil erodibility factor (K) is a quantitative index of distinguish the ability of soil to resist the erosion separation and handling. Taiwan soil erodibility factors have been calculated 280 soil samples' erodibility factors by Wann and Huang (1989) use the Wischmeier and Smith nomorgraph. 221 samples were collected at the Maioli block in Miaoli. The coordinates of every sample point and the land use situations were recorded. The physical properties were analyzed for each sample. Three estimation methods, consist of Kriging, Inverse Distance Weighted (IDW) and Spline, were applied to estimate soil erodibility factors distribution for Maioli block by using 181 points data, and the remaining 40 points for the validation. Then, the SPSS regression analysis was used to comparison of the accuracy of the training data and validation data by three different methods. Then, the best method can be determined. In the future, we can used this method to predict the soil erodibility factors in other areas.

  18. Blocking of Goal-Location Learning Based on Shape

    ERIC Educational Resources Information Center

    Alexander, Tim; Wilson, Stuart P.; Wilson, Paul N.

    2009-01-01

    Using desktop, computer-simulated virtual environments (VEs), the authors conducted 5 experiments to investigate blocking of learning about a goal location based on Shape B as a consequence of preliminary training to locate that goal using Shape A. The shapes were large 2-dimensional horizontal figures on the ground. Blocking of spatial learning…

  19. No Additional Benefits of Block- Over Evenly-Distributed High-Intensity Interval Training within a Polarized Microcycle

    PubMed Central

    McGawley, Kerry; Juudas, Elisabeth; Kazior, Zuzanna; Ström, Kristoffer; Blomstrand, Eva; Hansson, Ola; Holmberg, Hans-Christer

    2017-01-01

    Introduction: The current study aimed to investigate the responses to block- versus evenly-distributed high-intensity interval training (HIT) within a polarized microcycle. Methods: Twenty well-trained junior cross-country skiers (10 males, age 17.6 ± 1.5 and 10 females, age 17.3 ± 1.5) completed two, 3-week periods of training (EVEN and BLOCK) in a randomized, crossover-design study. In EVEN, 3 HIT sessions (5 × 4-min of diagonal-stride roller-skiing) were completed at a maximal sustainable intensity each week while low-intensity training (LIT) was distributed evenly around the HIT. In BLOCK, the same 9 HIT sessions were completed in the second week while only LIT was completed in the first and third weeks. Heart rate (HR), session ratings of perceived exertion (sRPE), and perceived recovery (pREC) were recorded for all HIT and LIT sessions, while distance covered was recorded for each HIT interval. The recovery-stress questionnaire for athletes (RESTQ-Sport) was completed weekly. Before and after EVEN and BLOCK, resting saliva and muscle samples were collected and an incremental test and 600-m time-trial (TT) were completed. Results: Pre- to post-testing revealed no significant differences between EVEN and BLOCK for changes in resting salivary cortisol, testosterone, or IgA, or for changes in muscle capillary density, fiber area, fiber composition, enzyme activity (CS, HAD, and PFK) or the protein content of VEGF or PGC-1α. Neither were any differences observed in the changes in skiing economy, V˙O2max or 600-m time-trial performance between interventions. These findings were coupled with no significant differences between EVEN and BLOCK for distance covered during HIT, summated HR zone scores, total sRPE training load, overall pREC or overall recovery-stress state. However, 600-m TT performance improved from pre- to post-training, irrespective of intervention (P = 0.003), and a number of hormonal and muscle biopsy markers were also significantly altered

  20. No Additional Benefits of Block- Over Evenly-Distributed High-Intensity Interval Training within a Polarized Microcycle.

    PubMed

    McGawley, Kerry; Juudas, Elisabeth; Kazior, Zuzanna; Ström, Kristoffer; Blomstrand, Eva; Hansson, Ola; Holmberg, Hans-Christer

    2017-01-01

    Introduction: The current study aimed to investigate the responses to block- versus evenly-distributed high-intensity interval training (HIT) within a polarized microcycle. Methods: Twenty well-trained junior cross-country skiers (10 males, age 17.6 ± 1.5 and 10 females, age 17.3 ± 1.5) completed two, 3-week periods of training (EVEN and BLOCK) in a randomized, crossover-design study. In EVEN, 3 HIT sessions (5 × 4-min of diagonal-stride roller-skiing) were completed at a maximal sustainable intensity each week while low-intensity training (LIT) was distributed evenly around the HIT. In BLOCK, the same 9 HIT sessions were completed in the second week while only LIT was completed in the first and third weeks. Heart rate (HR), session ratings of perceived exertion (sRPE), and perceived recovery (pREC) were recorded for all HIT and LIT sessions, while distance covered was recorded for each HIT interval. The recovery-stress questionnaire for athletes (RESTQ-Sport) was completed weekly. Before and after EVEN and BLOCK, resting saliva and muscle samples were collected and an incremental test and 600-m time-trial (TT) were completed. Results: Pre- to post-testing revealed no significant differences between EVEN and BLOCK for changes in resting salivary cortisol, testosterone, or IgA, or for changes in muscle capillary density, fiber area, fiber composition, enzyme activity (CS, HAD, and PFK) or the protein content of VEGF or PGC-1α. Neither were any differences observed in the changes in skiing economy, [Formula: see text] or 600-m time-trial performance between interventions. These findings were coupled with no significant differences between EVEN and BLOCK for distance covered during HIT, summated HR zone scores, total sRPE training load, overall pREC or overall recovery-stress state. However, 600-m TT performance improved from pre- to post-training, irrespective of intervention ( P = 0.003), and a number of hormonal and muscle biopsy markers were also significantly

  1. Mechanics of distributed fault and block rotation

    NASA Technical Reports Server (NTRS)

    Nur, A.; Scotti, O.; Ron, H.

    1989-01-01

    Paleomagnetic data, structural geology, and rock mechanics are used to explore the validity and significance of the block rotation concept. The analysis is based on data from Northern Israel, where fault slip and spacing are used to predict block rotation; the Mojave Desert, with well documented strike-slip sets; the Lake Mead, Nevada fault system with well-defined sets of strike-slip faults; and the San Gabriel Mountains domain with a multiple set of strike-slip faults. The results of the analysis indicate that block rotations can have a profound influence on the interpretation of geodetic measurments and the inversion of geodetic data. Furthermore, the block rotations and domain boundaries may be involved in creating the heterogeneities along active fault systems which may be responsible for the initiation and termination of earthquake rupture.

  2. Distribution of short block copolymer chains in Binary Blends of Block Copolymers Having Hydrogen Bonding

    NASA Astrophysics Data System (ADS)

    Kwak, Jongheon; Han, Sunghyun; Kim, Jin Kon

    2014-03-01

    A binary mixture of two block copolymers whose blocks are capable of forming the hydrogen bonding allows one to obtain various microdomains that could not be expected for neat block copolymer. For instance, the binary blend of symmetric polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP) and polystyrene-block-polyhydroxystyrene copolymer (PS-b-PHS) blends where the hydrogen bonding occurred between P2VP and PHS showed hexagonally packed (HEX) cylindrical and body centered cubic (BCC) spherical microdomains. To know the exact location of short block copolymer chains at the interface, we synthesized deuterated polystyrene-block-polyhydroxystyrene copolymer (dPS-b-PHS) and prepared a binary mixture with PS-b-P2VP. We investigate, via small angle X-ray scattering (SAXS) and neutron reflectivity (NR), the exact location of shorter dPS block chain near the interface of the microdomains.

  3. Efficacy of virtual block objects in reducing the lung dose in helical tomotherapy planning for cervical oesophageal cancer: a planning study.

    PubMed

    Ito, Makoto; Shimizu, Hidetoshi; Aoyama, Takahiro; Tachibana, Hiroyuki; Tomita, Natsuo; Makita, Chiyoko; Koide, Yutaro; Kato, Daiki; Ishiguchi, Tsuneo; Kodaira, Takeshi

    2018-04-04

    Intensity-modulated radiotherapy is useful for cervical oesophageal carcinoma (CEC); however, increasing low-dose exposure to the lung may lead to radiation pneumonitis. Nevertheless, an irradiation technique that avoids the lungs has never been examined due to the high difficulty of dose optimization. In this study, we examined the efficacy of helical tomotherapy that can restrict beamlets passing virtual blocks during dose optimization computing (block plan) in reducing the lung dose. Fifteen patients with CEC were analysed. The primary/nodal lesion and prophylactic nodal region with adequate margins were defined as the planning target volume (PTV)-60 Gy and PTV-48 Gy, respectively. Nineteen plans per patient were made and compared (total: 285 plans), including non-block and block plans with several shapes and sizes. The most appropriate block model was semi-circular, 8 cm outside of the tracheal bifurcation, with a significantly lower lung dose compared to that of non-block plans; the mean lung volumes receiving 5 Gy, 10 Gy, 20 Gy, and the mean lung dose were 31.3% vs. 48.0% (p <  0.001), 22.4% vs. 39.4% (p <  0.001), 13.2% vs. 16.0% (p = 0.028), and 7.1 Gy vs. 9.6 Gy (p <  0.001), respectively. Both the block and non-block plans were comparable in terms of the homogeneity and conformity indexes of PTV-60 Gy: 0.05 vs. 0.04 (p = 0.100) and 0.82 vs. 0.85 (p = 0.616), respectively. The maximum dose of the spinal cord planning risk volume increased slightly (49.4 Gy vs. 47.9 Gy, p = 0.002). There was no significant difference in the mean doses to the heart and the thyroid gland. Prolongation of the delivery time was less than 1 min (5.6 min vs. 4.9 min, p = 0.010). The block plan for CEC could significantly reduce the lung dose, with acceptable increment in the spinal dose and a slightly prolonged delivery time.

  4. Virtual Machine Language

    NASA Technical Reports Server (NTRS)

    Grasso, Christopher; Page, Dennis; O'Reilly, Taifun; Fteichert, Ralph; Lock, Patricia; Lin, Imin; Naviaux, Keith; Sisino, John

    2005-01-01

    Virtual Machine Language (VML) is a mission-independent, reusable software system for programming for spacecraft operations. Features of VML include a rich set of data types, named functions, parameters, IF and WHILE control structures, polymorphism, and on-the-fly creation of spacecraft commands from calculated values. Spacecraft functions can be abstracted into named blocks that reside in files aboard the spacecraft. These named blocks accept parameters and execute in a repeatable fashion. The sizes of uplink products are minimized by the ability to call blocks that implement most of the command steps. This block approach also enables some autonomous operations aboard the spacecraft, such as aerobraking, telemetry conditional monitoring, and anomaly response, without developing autonomous flight software. Operators on the ground write blocks and command sequences in a concise, high-level, human-readable programming language (also called VML ). A compiler translates the human-readable blocks and command sequences into binary files (the operations products). The flight portion of VML interprets the uplinked binary files. The ground subsystem of VML also includes an interactive sequence- execution tool hosted on workstations, which runs sequences at several thousand times real-time speed, affords debugging, and generates reports. This tool enables iterative development of blocks and sequences within times of the order of seconds.

  5. Virtuality and transverse momentum dependence of the pion distribution amplitude

    DOE PAGES

    Radyushkin, Anatoly V.

    2016-03-08

    We describe basics of a new approach to transverse momentum dependence in hard exclusive processes. We develop it in application to the transition process γ*γ → π 0 at the handbag level. Our starting point is coordinate representation for matrix elements of operators (in the simplest case, bilocal O (0,z)) describing a hadron with momentum p. Treated as functions of (pz) and z 2, they are parametrized through virtuality distribution amplitudes (VDA) Φ(x,σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z 2. For intervals with z + = 0, we introduce the transverse momentum distribution amplitude (TMDA)more » ψ(x, k), and write it in terms of VDA Φ(x,σ). The results of covariant calculations, written in terms of Φ(x, σ) are converted into expressions involving ψ(x, k). Starting with scalar toy models, we extend the analysis onto the case of spin-1/2 quarks and QCD. We propose simple models for soft VDAs/TMDAs, and use them for comparison of handbag results with experimental (BaBar and BELLE) data on the pion transition form factor. Furthermore, we discuss how one can generate high-k tails from primordial soft distributions.« less

  6. Synchronizing Self and Object Movement: How Child and Adult Cyclists Intercept Moving Gaps in a Virtual Environment

    ERIC Educational Resources Information Center

    Chihak, Benjamin J.; Plumert, Jodie M.; Ziemer, Christine J.; Babu, Sabarish; Grechkin, Timofey; Cremer, James F.; Kearney, Joseph K.

    2010-01-01

    Two experiments examined how 10- and 12-year-old children and adults intercept moving gaps while bicycling in an immersive virtual environment. Participants rode an actual bicycle along a virtual roadway. At 12 test intersections, participants attempted to pass through a gap between 2 moving, car-sized blocks without stopping. The blocks were…

  7. Research on the control strategy of distributed energy resources inverter based on improved virtual synchronous generator.

    PubMed

    Gao, Changwei; Liu, Xiaoming; Chen, Hai

    2017-08-22

    This paper focus on the power fluctuations of the virtual synchronous generator(VSG) during the transition process. An improved virtual synchronous generator(IVSG) control strategy based on feed-forward compensation is proposed. Adjustable parameter of the compensation section can be modified to achieve the goal of reducing the order of the system. It can effectively suppress the power fluctuations of the VSG in transient process. To verify the effectiveness of the proposed control strategy for distributed energy resources inverter, the simulation model is set up in MATLAB/SIMULINK platform and physical experiment platform is established. Simulation and experiment results demonstrate the effectiveness of the proposed IVSG control strategy.

  8. Integration of the SSPM and STAGE with the MPACT Virtual Facility Distributed Test Bed.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cipiti, Benjamin B.; Shoman, Nathan

    The Material Protection Accounting and Control Technologies (MPACT) program within DOE NE is working toward a 2020 milestone to demonstrate a Virtual Facility Distributed Test Bed. The goal of the Virtual Test Bed is to link all MPACT modeling tools, technology development, and experimental work to create a Safeguards and Security by Design capability for fuel cycle facilities. The Separation and Safeguards Performance Model (SSPM) forms the core safeguards analysis tool, and the Scenario Toolkit and Generation Environment (STAGE) code forms the core physical security tool. These models are used to design and analyze safeguards and security systems and generatemore » performance metrics. Work over the past year has focused on how these models will integrate with the other capabilities in the MPACT program and specific model changes to enable more streamlined integration in the future. This report describes the model changes and plans for how the models will be used more collaboratively. The Virtual Facility is not designed to integrate all capabilities into one master code, but rather to maintain stand-alone capabilities that communicate results between codes more effectively.« less

  9. RAID Unbound: Storage Fault Tolerance in a Distributed Environment

    NASA Technical Reports Server (NTRS)

    Ritchie, Brian

    1996-01-01

    Mirroring, data replication, backup, and more recently, redundant arrays of independent disks (RAID) are all technologies used to protect and ensure access to critical company data. A new set of problems has arisen as data becomes more and more geographically distributed. Each of the technologies listed above provides important benefits; but each has failed to adapt fully to the realities of distributed computing. The key to data high availability and protection is to take the technologies' strengths and 'virtualize' them across a distributed network. RAID and mirroring offer high data availability, which data replication and backup provide strong data protection. If we take these concepts at a very granular level (defining user, record, block, file, or directory types) and them liberate them from the physical subsystems with which they have traditionally been associated, we have the opportunity to create a highly scalable network wide storage fault tolerance. The network becomes the virtual storage space in which the traditional concepts of data high availability and protection are implemented without their corresponding physical constraints.

  10. Skill training in multimodal virtual environments.

    PubMed

    Gopher, Daniel

    2012-01-01

    Multimodal, immersive, virtual reality (VR) techniques open new perspectives for perceptual-motor skill trainers. They also introduce new risks and dangers. This paper describes the benefits and pitfalls of multimodal training and the cognitive building blocks of a multimodal, VR training simulators.

  11. Derived virtual devices: a secure distributed file system mechanism

    NASA Technical Reports Server (NTRS)

    VanMeter, Rodney; Hotz, Steve; Finn, Gregory

    1996-01-01

    This paper presents the design of derived virtual devices (DVDs). DVDs are the mechanism used by the Netstation Project to provide secure shared access to network-attached peripherals distributed in an untrusted network environment. DVDs improve Input/Output efficiency by allowing user processes to perform I/O operations directly from devices without intermediate transfer through the controlling operating system kernel. The security enforced at the device through the DVD mechanism includes resource boundary checking, user authentication, and restricted operations, e.g., read-only access. To illustrate the application of DVDs, we present the interactions between a network-attached disk and a file system designed to exploit the DVD abstraction. We further discuss third-party transfer as a mechanism intended to provide for efficient data transfer in a typical NAP environment. We show how DVDs facilitate third-party transfer, and provide the security required in a more open network environment.

  12. Crosstalk-aware virtual network embedding over inter-datacenter optical networks with few-mode fibers

    NASA Astrophysics Data System (ADS)

    Huang, Haibin; Guo, Bingli; Li, Xin; Yin, Shan; Zhou, Yu; Huang, Shanguo

    2017-12-01

    Virtualization of datacenter (DC) infrastructures enables infrastructure providers (InPs) to provide novel services like virtual networks (VNs). Furthermore, optical networks have been employed to connect the metro-scale geographically distributed DCs. The synergistic virtualization of the DC infrastructures and optical networks enables the efficient VN service over inter-DC optical networks (inter-DCONs). While the capacity of the used standard single-mode fiber (SSMF) is limited by their nonlinear characteristics. Thus, mode-division multiplexing (MDM) technology based on few-mode fibers (FMFs) could be employed to increase the capacity of optical networks. Whereas, modal crosstalk (XT) introduced by optical fibers and components deployed in the MDM optical networks impacts the performance of VN embedding (VNE) over inter-DCONs with FMFs. In this paper, we propose a XT-aware VNE mechanism over inter-DCONs with FMFs. The impact of XT is considered throughout the VNE procedures. The simulation results show that the proposed XT-aware VNE can achieves better performances of blocking probability and spectrum utilization compared to conventional VNE mechanisms.

  13. A Distributed Parallel Genetic Algorithm of Placement Strategy for Virtual Machines Deployment on Cloud Platform

    PubMed Central

    Dong, Yu-Shuang; Xu, Gao-Chao; Fu, Xiao-Dong

    2014-01-01

    The cloud platform provides various services to users. More and more cloud centers provide infrastructure as the main way of operating. To improve the utilization rate of the cloud center and to decrease the operating cost, the cloud center provides services according to requirements of users by sharding the resources with virtualization. Considering both QoS for users and cost saving for cloud computing providers, we try to maximize performance and minimize energy cost as well. In this paper, we propose a distributed parallel genetic algorithm (DPGA) of placement strategy for virtual machines deployment on cloud platform. It executes the genetic algorithm parallelly and distributedly on several selected physical hosts in the first stage. Then it continues to execute the genetic algorithm of the second stage with solutions obtained from the first stage as the initial population. The solution calculated by the genetic algorithm of the second stage is the optimal one of the proposed approach. The experimental results show that the proposed placement strategy of VM deployment can ensure QoS for users and it is more effective and more energy efficient than other placement strategies on the cloud platform. PMID:25097872

  14. A distributed parallel genetic algorithm of placement strategy for virtual machines deployment on cloud platform.

    PubMed

    Dong, Yu-Shuang; Xu, Gao-Chao; Fu, Xiao-Dong

    2014-01-01

    The cloud platform provides various services to users. More and more cloud centers provide infrastructure as the main way of operating. To improve the utilization rate of the cloud center and to decrease the operating cost, the cloud center provides services according to requirements of users by sharding the resources with virtualization. Considering both QoS for users and cost saving for cloud computing providers, we try to maximize performance and minimize energy cost as well. In this paper, we propose a distributed parallel genetic algorithm (DPGA) of placement strategy for virtual machines deployment on cloud platform. It executes the genetic algorithm parallelly and distributedly on several selected physical hosts in the first stage. Then it continues to execute the genetic algorithm of the second stage with solutions obtained from the first stage as the initial population. The solution calculated by the genetic algorithm of the second stage is the optimal one of the proposed approach. The experimental results show that the proposed placement strategy of VM deployment can ensure QoS for users and it is more effective and more energy efficient than other placement strategies on the cloud platform.

  15. Efficient Distribution of Triggered Synchronous Block Diagrams

    DTIC Science & Technology

    2011-10-21

    corresponding FFP processes, from P to P ′. The sizes of the queues are as in [23]. In particular, if M is not Moore, a queue of size 1 suffices; ifM is Moore...computer systems. Real-Time Systems, 14(3):219–250, 1998. [23] S . Tripakis, C. Pinello, A . Benveniste, A . Sangiovanni-Vincent, P. Caspi, and M . Di...of connections: a data connection connects some output port of a block M to some input port of another block M ′; a trigger connection connects some

  16. Evolution of A Distributed Live, Virtual, Constructive Environment for Human in the Loop Unmanned Aircraft Testing

    NASA Technical Reports Server (NTRS)

    Murphy, James R.; Otto, Neil M.

    2017-01-01

    NASA's Unmanned Aircraft Systems Integration in the National Airspace System Project is conducting human in the loop simulations and flight testing intended to reduce barriers associated with enabling routine airspace access for unmanned aircraft. The primary focus of these tests is interaction of the unmanned aircraft pilot with the display of detect and avoid alerting and guidance information. The project's integrated test and evaluation team was charged with developing the test infrastructure. As with any development effort, compromises in the underlying system architecture and design were made to allow for the rapid prototyping and open-ended nature of the research. In order to accommodate these design choices, a distributed test environment was developed incorporating Live, Virtual, Constructive, (LVC) concepts. The LVC components form the core infrastructure support simulation of UAS operations by integrating live and virtual aircraft in a realistic air traffic environment. This LVC infrastructure enables efficient testing by leveraging the use of existing assets distributed across multiple NASA Centers. Using standard LVC concepts enable future integration with existing simulation infrastructure.

  17. Evolution of A Distributed Live, Virtual, Constructive Environment for Human in the Loop Unmanned Aircraft Testing

    NASA Technical Reports Server (NTRS)

    Murphy, Jim; Otto, Neil

    2017-01-01

    NASA's Unmanned Aircraft Systems Integration in the National Airspace System Project is conducting human in the loop simulations and flight testing intended to reduce barriers associated with enabling routine airspace access for unmanned aircraft. The primary focus of these tests is interaction of the unmanned aircraft pilot with the display of detect and avoid alerting and guidance information. The projects integrated test and evaluation team was charged with developing the test infrastructure. As with any development effort, compromises in the underlying system architecture and design were made to allow for the rapid prototyping and open-ended nature of the research. In order to accommodate these design choices, a distributed test environment was developed incorporating Live, Virtual, Constructive, (LVC) concepts. The LVC components form the core infrastructure support simulation of UAS operations by integrating live and virtual aircraft in a realistic air traffic environment. This LVC infrastructure enables efficient testing by leveraging the use of existing assets distributed across multiple NASA Centers. Using standard LVC concepts enable future integration with existing simulation infrastructure.

  18. Distributed Cognition in a Virtual World

    ERIC Educational Resources Information Center

    Gillen, Julia; Ferguson, Rebecca; Peachey, Anna; Twining, Peter

    2012-01-01

    Over a 13-month period, the Schome Park Programme operated the first "closed" (i.e. protected) Teen Second Life project in Europe. The project organised diverse educational events that centred on use of a virtual world and an associated asynchronous forum and wiki. Students and staff together exploited the affordances of the environment…

  19. Retention of Mastoidectomy Skills After Virtual Reality Simulation Training.

    PubMed

    Andersen, Steven Arild Wuyts; Konge, Lars; Cayé-Thomasen, Per; Sørensen, Mads Sølvsten

    2016-07-01

    The ultimate goal of surgical training is consolidated skills with a consistently high performance. However, surgical skills are heterogeneously retained and depend on a variety of factors, including the task, cognitive demands, and organization of practice. Virtual reality (VR) simulation is increasingly being used in surgical skills training, including temporal bone surgery, but there is a gap in knowledge on the retention of mastoidectomy skills after VR simulation training. To determine the retention of mastoidectomy skills after VR simulation training with distributed and massed practice and to investigate participants' cognitive load during retention procedures. A prospective 3-month follow-up study of a VR simulation trial was conducted from February 6 to September 19, 2014, at an academic teaching hospital among 36 medical students: 19 from a cohort trained with distributed practice and 17 from a cohort trained with massed practice. Participants performed 2 virtual mastoidectomies in a VR simulator a mean of 3.2 months (range, 2.4-5.0 months) after completing initial training with 12 repeated procedures. Practice blocks were spaced apart in time (distributed), or all procedures were performed in 1 day (massed). Performance of the virtual mastoidectomy as assessed by 2 masked senior otologists using a modified Welling scale, as well as cognitive load as estimated by reaction time to perform a secondary task. Among 36 participants, mastoidectomy final-product skills were largely retained at 3 months (mean change in score, 0.1 points; P = .89) regardless of practice schedule, but the group trained with massed practice took more time to complete the task. The performance of the massed practice group increased significantly from the first to the second retention procedure (mean change, 1.8 points; P = .001), reflecting that skills were less consolidated. For both groups, increases in reaction times in the secondary task (distributed practice group: mean

  20. Distributed attitude synchronization of formation flying via consensus-based virtual structure

    NASA Astrophysics Data System (ADS)

    Cong, Bing-Long; Liu, Xiang-Dong; Chen, Zhen

    2011-06-01

    This paper presents a general framework for synchronized multiple spacecraft rotations via consensus-based virtual structure. In this framework, attitude control systems for formation spacecrafts and virtual structure are designed separately. Both parametric uncertainty and external disturbance are taken into account. A time-varying sliding mode control (TVSMC) algorithm is designed to improve the robustness of the actual attitude control system. As for the virtual attitude control system, a behavioral consensus algorithm is presented to accomplish the attitude maneuver of the entire formation and guarantee a consistent attitude among the local virtual structure counterparts during the attitude maneuver. A multiple virtual sub-structures (MVSSs) system is introduced to enhance current virtual structure scheme when large amounts of spacecrafts are involved in the formation. The attitude of spacecraft is represented by modified Rodrigues parameter (MRP) for its non-redundancy. Finally, a numerical simulation with three synchronization situations is employed to illustrate the effectiveness of the proposed strategy.

  1. Managing Distributed Innovation Processes in Virtual Organizations by Applying the Collaborative Network Relationship Analysis

    NASA Astrophysics Data System (ADS)

    Eschenbächer, Jens; Seifert, Marcus; Thoben, Klaus-Dieter

    Distributed innovation processes are considered as a new option to handle both the complexity and the speed in which new products and services need to be prepared. Indeed most research on innovation processes was focused on multinational companies with an intra-organisational perspective. The phenomena of innovation processes in networks - with an inter-organisational perspective - have been almost neglected. Collaborative networks present a perfect playground for such distributed innovation processes whereas the authors highlight in specific Virtual Organisation because of their dynamic behaviour. Research activities supporting distributed innovation processes in VO are rather new so that little knowledge about the management of such research is available. With the presentation of the collaborative network relationship analysis this gap will be addressed. It will be shown that a qualitative planning of collaboration intensities can support real business cases by proving knowledge and planning data.

  2. Virtual Vision

    NASA Astrophysics Data System (ADS)

    Terzopoulos, Demetri; Qureshi, Faisal Z.

    Computer vision and sensor networks researchers are increasingly motivated to investigate complex multi-camera sensing and control issues that arise in the automatic visual surveillance of extensive, highly populated public spaces such as airports and train stations. However, they often encounter serious impediments to deploying and experimenting with large-scale physical camera networks in such real-world environments. We propose an alternative approach called "Virtual Vision", which facilitates this type of research through the virtual reality simulation of populated urban spaces, camera sensor networks, and computer vision on commodity computers. We demonstrate the usefulness of our approach by developing two highly automated surveillance systems comprising passive and active pan/tilt/zoom cameras that are deployed in a virtual train station environment populated by autonomous, lifelike virtual pedestrians. The easily reconfigurable virtual cameras distributed in this environment generate synthetic video feeds that emulate those acquired by real surveillance cameras monitoring public spaces. The novel multi-camera control strategies that we describe enable the cameras to collaborate in persistently observing pedestrians of interest and in acquiring close-up videos of pedestrians in designated areas.

  3. The National Virtual Observatory

    NASA Astrophysics Data System (ADS)

    Hanisch, Robert J.

    2001-06-01

    The National Virtual Observatory is a distributed computational facility that will provide access to the ``virtual sky''-the federation of astronomical data archives, object catalogs, and associated information services. The NVO's ``virtual telescope'' is a common framework for requesting, retrieving, and manipulating information from diverse, distributed resources. The NVO will make it possible to seamlessly integrate data from the new all-sky surveys, enabling cross-correlations between multi-Terabyte catalogs and providing transparent access to the underlying image or spectral data. Success requires high performance computational systems, high bandwidth network services, agreed upon standards for the exchange of metadata, and collaboration among astronomers, astronomical data and information service providers, information technology specialists, funding agencies, and industry. International cooperation at the onset will help to assure that the NVO simultaneously becomes a global facility. .

  4. Distribution of bupivacaine hydrochloride after sciatic and femoral nerve blocks in cats: A magnetic resonance imaging study.

    PubMed

    Evangelista, Marina C; de Lassalle, Julie; Chevrier, Christine; Carmel, Eric N; Fantoni, Denise T; Steagall, Paulo V M

    2017-12-01

    The objective of this study was to evaluate the distribution of bupivacaine hydrochloride using magnetic resonance imaging (MRI) after electrical nerve stimulator (ENS)-guided sciatic (ScN) and femoral (FN) nerve blocks in cats. Six adult cats (body weight 4.8±0.6kg) were anesthetized with acepromazine-buprenorphine-propofol-isoflurane. Transverse and sagittal plan sequences of pelvic limbs were obtained using a high-field magnet (1.5T). Afterwards, the ScN and FN blocks (one block per limb) were performed using 0.1mL/kg of bupivacaine 0.5% per site and the MRI sequence was repeated after each block. The injection was considered successful when bupivacaine was in contact with the nerve. Injectate location and complications were recorded. The length (mm) of contact (spread) between bupivacaine and nerves was measured and classified as fair (<15mm) or adequate (≥15mm). Five out of six ScN injections were successful; of these, four had adequate spread over the nerve [26 (13-39) mm]. All FN injections were successful, but in one case bupivacaine was administered over the motor branch of FN, distally to the bifurcation between the femoral and saphenous nerve. It was not possible to measure neither the length of contact between bupivacaine and FN nor to identify iatrogenic trauma caused by the injections. MRI can be used for the evaluation of bupivacaine distribution, but not complications, following ENS-guided ScN and FN blocks in cats. Despite most of the injections were considered successful, individual variability regarding the injectate location may explain differences in efficacy in the clinical setting. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Virtuality Distributions and γγ * -> π 0 Transition at Handbag Level

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Radyushkin, Anatoly V.

    2015-09-01

    We outline a new approach to transverse momentum dependence in hard processes using as an example the exclusive transitionmore » $${\\gamma^{*}\\gamma \\to \\pi^{0}}$$ at the handbag level. We start with the coordinate representation for a matrix element $${\\langle p |{\\cal O}(0,z) |0 \\rangle}$$ of a bilocal operator $${{\\cal O} (0,z)}$$ describing a hadron with momentum p. Treated as a function of (pz) and z$$^{2}$$, it is parametrized through virtuality distribution amplitude (VDA) Φ (x, σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z$$^{2}$$. For intervals with z$$^{+}$$ = 0, we introduce the transverse momentum distribution amplitude (TMDA) $${\\Ψ (x,k_{\\perp})}$$ , and write it in terms of VDA Φ (x, σ). The results of covariant calculations, written in terms of Φ (x, σ) are converted into expressions involving $${\\Ψ (x,k_{\\perp})}$$ . We propose simple models for soft VDAs/TMDAs, and use them for comparison of handbag results with experimental (BaBar and BELLE) data on the pion transition form factor.« less

  6. Ambient clumsiness in virtual environments

    NASA Astrophysics Data System (ADS)

    Ruzanka, Silvia; Behar, Katherine

    2010-01-01

    A fundamental pursuit of Virtual Reality is the experience of a seamless connection between the user's body and actions within the simulation. Virtual worlds often mediate the relationship between the physical and virtual body through creating an idealized representation of the self in an idealized space. This paper argues that the very ubiquity of the medium of virtual environments, such as the massively popular Second Life, has now made them mundane, and that idealized representations are no longer appropriate. In our artwork we introduce the attribute of clumsiness to Second Life by creating and distributing scripts that cause users' avatars to exhibit unpredictable stumbling, tripping, and momentary poor coordination, thus subtly and unexpectedly intervening with, rather than amplifying, a user's intent. These behaviors are publicly distributed, and manifest only occasionally - rather than intentional, conscious actions, they are involuntary and ambient. We suggest that the physical human body is itself an imperfect interface, and that the continued blurring of distinctions between the physical body and virtual representations calls for the introduction of these mundane, clumsy elements.

  7. Exploiting Molecular Weight Distribution Shape to Tune Domain Spacing in Block Copolymer Thin Films.

    PubMed

    Gentekos, Dillon T; Jia, Junteng; Tirado, Erika S; Barteau, Katherine P; Smilgies, Detlef-M; DiStasio, Robert A; Fors, Brett P

    2018-04-04

    We report a method for tuning the domain spacing ( D sp ) of self-assembled block copolymer thin films of poly(styrene- block-methyl methacrylate) (PS- b-PMMA) over a large range of lamellar periods. By modifying the molecular weight distribution (MWD) shape (including both the breadth and skew) of the PS block via temporal control of polymer chain initiation in anionic polymerization, we observe increases of up to 41% in D sp for polymers with the same overall molecular weight ( M n ≈ 125 kg mol -1 ) without significantly changing the overall morphology or chemical composition of the final material. In conjunction with our experimental efforts, we have utilized concepts from population statistics and least-squares analysis to develop a model for predicting D sp based on the first three moments of the MWDs. This statistical model reproduces experimental D sp values with high fidelity (with mean absolute errors of 1.2 nm or 1.8%) and provides novel physical insight into the individual and collective roles played by the MWD moments in determining this property of interest. This work demonstrates that both MWD breadth and skew have a profound influence over D sp , thereby providing an experimental and conceptual platform for exploiting MWD shape as a simple and modular handle for fine-tuning D sp in block copolymer thin films.

  8. Block Distribution Analysis of Impact Craters in the Tharsis and Elysium Planitia Regions on Mars

    NASA Astrophysics Data System (ADS)

    Button, N.; Karunatillake, S.; Diaz, C.; Zadei, S.; Rajora, V.; Barbato, A.; Piorkowski, M.

    2017-12-01

    The block distribution pattern of ejecta surrounding impact craters reveals clues about their formation. Using images from High Resolution Imaging Science Experiment (HiRISE) image onboard the Mars Reconnaissance Orbiter (MRO), we indentified two rayed impact craters on Mars with measurable ejecta fields to quantitatively investigate in this study. Impact Crater 1 (HiRISE image PSP_008011_1975) is located in the Tharsis region at 17.41°N, 248.75°E and is 175 m in diameter. Impact Crater 2 (HiRISE image ESP_018352_1805) is located in Elysium Planitia at 0.51°N, 163.14°E and is 320 m in diameter. Our block measurements, used to determine the area, were conducted using HiView. Employing methods similar to Krishna and Kumar (2016), we compared block size and axis ratio to block distance from the center of the crater, impact angle, and direction. Preliminary analysis of sixteen radial sectors around Impact Crater 1 revealed that in sectors containing mostly small blocks (less than 10 m2), the small blocks were ejected up to three times the diameter of the crater from the center of the crater. These small block-dominated sectors lacked blocks larger than 10 m2. Contrastingly, in large block-dominated sectors (larger than 30 m2) blocks rarely traveled farther than 200 m from the center of the crater. We also seek to determine the impact angle and direction. Krishna and Kumar (2016) calculate the b-value (N(a) = Ca-b; "N(a) equals the number of fragments or craters with a size greater than a, C is a constant, and -b is a power index") as a method to determine the impact direction. Our preliminary results for Impact Crater 1 did not clearly indicate the impact angle. With improved measurements and the assessment of Impact Crater 2, we will compare Impact Crater 1 to Impact Crater 2 as well as assess the impact angle and direction in order to determine if the craters are secondary craters. Hood, D. and Karunatillake, S. (2017), LPSC, Abstract #2640 Krishna, N., and P. S

  9. Transition of a dental histology course from light to virtual microscopy.

    PubMed

    Weaker, Frank J; Herbert, Damon C

    2009-10-01

    The transition of the dental histology course at the University of Texas Health Science Center at San Antonio Dental School was completed gradually over a five-year period. A pilot project was initially conducted to study the feasibility of integrating virtual microscopy into a traditional light microscopic lecture and laboratory course. Because of the difficulty of procuring quality calcified and decalcified sections of teeth, slides from the student loan collection in the oral histology block of the course were outsourced for conversion to digital images and placed on DVDs along with a slide viewer. The slide viewer mimicked the light microscope, allowing horizontal and vertical movement and changing of magnification, and, in addition, a feature to capture static images. In a survey, students rated the ease of use of the software, quality of the images, maneuverability of the images, and questions regarding use of the software, effective use of laboratory, and faculty time. Because of the positive support from the students, our entire student loan collection of 153 glass slides was subsequently converted to virtual images and distributed on an Apricorn pocket external hard drive. Students were asked to assess the virtual microscope over a four-year period. As a result of the surveys, light microscopes have been totally eliminated, and microscope exams have been replaced with project slide examinations. In the future, we plan to expand our virtual slides and incorporate computer testing.

  10. Agreements in Virtual Organizations

    NASA Astrophysics Data System (ADS)

    Pankowska, Malgorzata

    This chapter is an attempt to explain the important impact that contract theory delivers with respect to the concept of virtual organization. The author believes that not enough research has been conducted in order to transfer theoretical foundations for networking to the phenomena of virtual organizations and open autonomic computing environment to ensure the controllability and management of them. The main research problem of this chapter is to explain the significance of agreements for virtual organizations governance. The first part of this chapter comprises explanations of differences among virtual machines and virtual organizations for further descriptions of the significance of the first ones to the development of the second. Next, the virtual organization development tendencies are presented and problems of IT governance in highly distributed organizational environment are discussed. The last part of this chapter covers analysis of contracts and agreements management for governance in open computing environments.

  11. Distribution and absorption of local anesthetics in inferior alveolar nerve block: evaluation by magnetic resonance imaging.

    PubMed

    Ay, Sinan; Küçük, Dervisşhan; Gümüş, Cesur; Kara, M Isa

    2011-11-01

    The aim of this study was to evaluate the distribution and absorption of local anesthetic solutions in inferior alveolar nerve block using magnetic resonance imaging. Forty healthy volunteers were divided into 4 groups and injected with 1.5 mL for inferior alveolar nerve block and 0.3 mL for lingual nerve block. The solutions used for the different groups were 2% lidocaine, 2% lidocaine with 0.125 mg/mL epinephrine, 4% articaine with 0.006 mg/mL epinephrine, and 4% articaine with 0.012 mg/mL epinephrine. All subjects had axial T2-weighted and fat-suppressed images at 0, 60, and 120 minutes after injection. The localization, area, and intensity (signal characteristics) of the solutions were analyzed and onset and duration times of the anesthesia were recorded. There were no significant differences between groups with regard to the intensity and area of the solutions at 0, 60, and 120 minutes after injection, but differences were found within each group. No between-group differences were found on magnetic resonance imaging in the distribution and absorption of lidocaine with or without epinephrine and articaine with 0.006 and 0.012 mg/mL epinephrine. All solutions were noticeably absorbed at 120 minutes after injection. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  12. Near-exact distributions for the block equicorrelation and equivariance likelihood ratio test statistic

    NASA Astrophysics Data System (ADS)

    Coelho, Carlos A.; Marques, Filipe J.

    2013-09-01

    In this paper the authors combine the equicorrelation and equivariance test introduced by Wilks [13] with the likelihood ratio test (l.r.t.) for independence of groups of variables to obtain the l.r.t. of block equicorrelation and equivariance. This test or its single block version may find applications in many areas as in psychology, education, medicine, genetics and they are important "in many tests of multivariate analysis, e.g. in MANOVA, Profile Analysis, Growth Curve analysis, etc" [12, 9]. By decomposing the overall hypothesis into the hypotheses of independence of groups of variables and the hypothesis of equicorrelation and equivariance we are able to obtain the expressions for the overall l.r.t. statistic and its moments. From these we obtain a suitable factorization of the characteristic function (c.f.) of the logarithm of the l.r.t. statistic, which enables us to develop highly manageable and precise near-exact distributions for the test statistic.

  13. De novo design of molecular architectures by evolutionary assembly of drug-derived building blocks.

    PubMed

    Schneider, G; Lee, M L; Stahl, M; Schneider, P

    2000-07-01

    An evolutionary algorithm was developed for fragment-based de novo design of molecules (TOPAS, TOPology-Assigning System). This stochastic method aims at generating a novel molecular structure mimicking a template structure. A set of approximately 25,000 fragment structures serves as the building block supply, which were obtained by a straightforward fragmentation procedure applied to 36,000 known drugs. Eleven reaction schemes were implemented for both fragmentation and building block assembly. This combination of drug-derived building blocks and a restricted set of reaction schemes proved to be a key for the automatic development of novel, synthetically tractable structures. In a cyclic optimization process, molecular architectures were generated from a parent structure by virtual synthesis, and the best structure of a generation was selected as the parent for the subsequent TOPAS cycle. Similarity measures were used to define 'fitness', based on 2D-structural similarity or topological pharmacophore distance between the template molecule and the variants. The concept of varying library 'diversity' during a design process was consequently implemented by using adaptive variant distributions. The efficiency of the design algorithm was demonstrated for the de novo construction of potential thrombin inhibitors mimicking peptide and non-peptide template structures.

  14. WarpEngine, a Flexible Platform for Distributed Computing Implemented in the VEGA Program and Specially Targeted for Virtual Screening Studies.

    PubMed

    Pedretti, Alessandro; Mazzolari, Angelica; Vistoli, Giulio

    2018-05-21

    The manuscript describes WarpEngine, a novel platform implemented within the VEGA ZZ suite of software for performing distributed simulations both in local and wide area networks. Despite being tailored for structure-based virtual screening campaigns, WarpEngine possesses the required flexibility to carry out distributed calculations utilizing various pieces of software, which can be easily encapsulated within this platform without changing their source codes. WarpEngine takes advantages of all cheminformatics features implemented in the VEGA ZZ program as well as of its largely customizable scripting architecture thus allowing an efficient distribution of various time-demanding simulations. To offer an example of the WarpEngine potentials, the manuscript includes a set of virtual screening campaigns based on the ACE data set of the DUD-E collections using PLANTS as the docking application. Benchmarking analyses revealed a satisfactory linearity of the WarpEngine performances, the speed-up values being roughly equal to the number of utilized cores. Again, the computed scalability values emphasized that a vast majority (i.e., >90%) of the performed simulations benefit from the distributed platform presented here. WarpEngine can be freely downloaded along with the VEGA ZZ program at www.vegazz.net .

  15. Grids, virtualization, and clouds at Fermilab

    NASA Astrophysics Data System (ADS)

    Timm, S.; Chadwick, K.; Garzoglio, G.; Noh, S.

    2014-06-01

    Fermilab supports a scientific program that includes experiments and scientists located across the globe. To better serve this community, in 2004, the (then) Computing Division undertook the strategy of placing all of the High Throughput Computing (HTC) resources in a Campus Grid known as FermiGrid, supported by common shared services. In 2007, the FermiGrid Services group deployed a service infrastructure that utilized Xen virtualization, LVS network routing and MySQL circular replication to deliver highly available services that offered significant performance, reliability and serviceability improvements. This deployment was further enhanced through the deployment of a distributed redundant network core architecture and the physical distribution of the systems that host the virtual machines across multiple buildings on the Fermilab Campus. In 2010, building on the experience pioneered by FermiGrid in delivering production services in a virtual infrastructure, the Computing Sector commissioned the FermiCloud, General Physics Computing Facility and Virtual Services projects to serve as platforms for support of scientific computing (FermiCloud 6 GPCF) and core computing (Virtual Services). This work will present the evolution of the Fermilab Campus Grid, Virtualization and Cloud Computing infrastructure together with plans for the future.

  16. Constraints on the H˜ generalized parton distribution from deep virtual Compton scattering measured at HERMES

    NASA Astrophysics Data System (ADS)

    Guidal, M.

    2010-09-01

    We have analyzed the longitudinally polarized proton target asymmetry data of the Deep Virtual Compton process recently published by the HERMES Collaboration in terms of Generalized Parton Distributions. We have fitted these new data in a largely model-independent fashion and the procedure results in numerical constraints on the accent="true">H˜Im Compton Form Factor. We present its t- and ξ-dependencies. We also find improvement on the determination of two other Compton Form Factors, HRe and HIm.

  17. Models and algorithm of optimization launch and deployment of virtual network functions in the virtual data center

    NASA Astrophysics Data System (ADS)

    Bolodurina, I. P.; Parfenov, D. I.

    2017-10-01

    The goal of our investigation is optimization of network work in virtual data center. The advantage of modern infrastructure virtualization lies in the possibility to use software-defined networks. However, the existing optimization of algorithmic solutions does not take into account specific features working with multiple classes of virtual network functions. The current paper describes models characterizing the basic structures of object of virtual data center. They including: a level distribution model of software-defined infrastructure virtual data center, a generalized model of a virtual network function, a neural network model of the identification of virtual network functions. We also developed an efficient algorithm for the optimization technology of containerization of virtual network functions in virtual data center. We propose an efficient algorithm for placing virtual network functions. In our investigation we also generalize the well renowned heuristic and deterministic algorithms of Karmakar-Karp.

  18. A virtual reality-based system integrated with fmri to study neural mechanisms of action observation-execution: A proof of concept study

    PubMed Central

    Adamovich, S.V.; August, K.; Merians, A.; Tunik, E.

    2017-01-01

    Purpose Emerging evidence shows that interactive virtual environments (VEs) may be a promising tool for studying sensorimotor processes and for rehabilitation. However, the potential of VEs to recruit action observation-execution neural networks is largely unknown. For the first time, a functional MRI-compatible virtual reality system (VR) has been developed to provide a window into studying brain-behavior interactions. This system is capable of measuring the complex span of hand-finger movements and simultaneously streaming this kinematic data to control the motion of representations of human hands in virtual reality. Methods In a blocked fMRI design, thirteen healthy subjects observed, with the intent to imitate (OTI), finger sequences performed by the virtual hand avatar seen in 1st person perspective and animated by pre-recorded kinematic data. Following this, subjects imitated the observed sequence while viewing the virtual hand avatar animated by their own movement in real-time. These blocks were interleaved with rest periods during which subjects viewed static virtual hand avatars and control trials in which the avatars were replaced with moving non-anthropomorphic objects. Results We show three main findings. First, both observation with intent to imitate and imitation with real-time virtual avatar feedback, were associated with activation in a distributed frontoparietal network typically recruited for observation and execution of real-world actions. Second, we noted a time-variant increase in activation in the left insular cortex for observation with intent to imitate actions performed by the virtual avatar. Third, imitation with virtual avatar feedback (relative to the control condition) was associated with a localized recruitment of the angular gyrus, precuneus, and extrastriate body area, regions which are (along with insular cortex) associated with the sense of agency. Conclusions Our data suggest that the virtual hand avatars may have served as

  19. Constructing Virtual Training Demonstrations

    DTIC Science & Technology

    2008-12-01

    virtual environments have been shown to be effective for training, and distributed game -based architectures contribute an added benefit of wide...investigation of how a demonstration authoring toolset can be constructed from existing virtual training environments using 3-D multiplayer gaming ...intelligent agents project to create AI middleware for simulations and videogames . The result was SimBionic®, which enables users to graphically author

  20. A Blueprint for Effectively Using RTI Intervention Block Time

    ERIC Educational Resources Information Center

    Higgins Averill, Orla; Baker, Diana; Rinaldi, Claudia

    2014-01-01

    Many schools have adopted schoolwide intervention blocks as a component of response-to-intervention (RTI) implementation to ensure that students who need intervention are receiving it. However, virtually no peer-reviewed guidance exists for helping teachers manage this time effectively. This article presents a blueprint for organizing intervention…

  1. Virtual patient simulator for distributed collaborative medical education.

    PubMed

    Caudell, Thomas P; Summers, Kenneth L; Holten, Jim; Hakamata, Takeshi; Mowafi, Moad; Jacobs, Joshua; Lozanoff, Beth K; Lozanoff, Scott; Wilks, David; Keep, Marcus F; Saiki, Stanley; Alverson, Dale

    2003-01-01

    Project TOUCH (Telehealth Outreach for Unified Community Health; http://hsc.unm.edu/touch) investigates the feasibility of using advanced technologies to enhance education in an innovative problem-based learning format currently being used in medical school curricula, applying specific clinical case models, and deploying to remote sites/workstations. The University of New Mexico's School of Medicine and the John A. Burns School of Medicine at the University of Hawai'i face similar health care challenges in providing and delivering services and training to remote and rural areas. Recognizing that health care needs are local and require local solutions, both states are committed to improving health care delivery to their unique populations by sharing information and experiences through emerging telehealth technologies by using high-performance computing and communications resources. The purpose of this study is to describe the deployment of a problem-based learning case distributed over the National Computational Science Alliance's Access Grid. Emphasis is placed on the underlying technical components of the TOUCH project, including the virtual reality development tool Flatland, the artificial intelligence-based simulation engine, the Access Grid, high-performance computing platforms, and the software that connects them all. In addition, educational and technical challenges for Project TOUCH are identified. Copyright 2003 Wiley-Liss, Inc.

  2. Using Hierarchical Virtual Screening To Combat Drug Resistance of the HIV-1 Protease.

    PubMed

    Li, Nan; Ainsworth, Richard I; Ding, Bo; Hou, Tingjun; Wang, Wei

    2015-07-27

    Human immunodeficiency virus (HIV) protease inhibitors (PIs) are important components of highly active anti-retroviral therapy (HAART) that block the catalytic site of HIV protease, thus preventing maturation of the HIV virion. However, with two decades of PI prescriptions in clinical practice, drug-resistant HIV mutants have now been found for all of the PI drugs. Therefore, the continuous development of new PI drugs is crucial both to combat the existing drug-resistant HIV strains and to provide treatments for future patients. Here we purpose an HIV PI drug design strategy to select candidate PIs with binding energy distributions dominated by interactions with conserved protease residues in both wild-type and various drug-resistant mutants. On the basis of this strategy, we have constructed a virtual screening pipeline including combinatorial library construction, combinatorial docking, MM/GBSA-based rescoring, and reranking on the basis of the binding energy distribution. We have tested our strategy on lopinavir by modifying its two functional groups. From an initial 751 689 candidate molecules, 18 candidate inhibitors were selected using the pipeline for experimental validation. IC50 measurements and drug resistance predictions successfully identified two ligands with both HIV protease inhibitor activity and an improved drug resistance profile on 2382 HIV mutants. This study provides a proof of concept for the integration of MM/GBSA energy analysis and drug resistance information at the stage of virtual screening and sheds light on future HIV drug design and the use of virtual screening to combat drug resistance.

  3. NASA Team Collaboration Pilot: Enabling NASA's Virtual Teams

    NASA Technical Reports Server (NTRS)

    Prahst, Steve

    2003-01-01

    Most NASA projects and work activities are accomplished by teams of people. These teams are often geographically distributed - across NASA centers and NASA external partners, both domestic and international. NASA "virtual" teams are stressed by the challenge of getting team work done - across geographic boundaries and time zones. To get distributed work done, teams rely on established methods - travel, telephones, Video Teleconferencing (NASA VITS), and email. Time is our most critical resource - and team members are hindered by the overhead of travel and the difficulties of coordinating work across their virtual teams. Modern, Internet based team collaboration tools offer the potential to dramatically improve the ability of virtual teams to get distributed work done.

  4. Distributed Drug Discovery, Part 2: Global Rehearsal of Alkylating Agents for the Synthesis of Resin-Bound Unnatural Amino Acids and Virtual D3 Catalog Construction

    PubMed Central

    2008-01-01

    Distributed Drug Discovery (D3) proposes solving large drug discovery problems by breaking them into smaller units for processing at multiple sites. A key component of the synthetic and computational stages of D3 is the global rehearsal of prospective reagents and their subsequent use in the creation of virtual catalogs of molecules accessible by simple, inexpensive combinatorial chemistry. The first section of this article documents the feasibility of the synthetic component of Distributed Drug Discovery. Twenty-four alkylating agents were rehearsed in the United States, Poland, Russia, and Spain, for their utility in the synthesis of resin-bound unnatural amino acids 1, key intermediates in many combinatorial chemistry procedures. This global reagent rehearsal, coupled to virtual library generation, increases the likelihood that any member of that virtual library can be made. It facilitates the realistic integration of worldwide virtual D3 catalog computational analysis with synthesis. The second part of this article describes the creation of the first virtual D3 catalog. It reports the enumeration of 24 416 acylated unnatural amino acids 5, assembled from lists of either rehearsed or well-precedented alkylating and acylating reagents, and describes how the resulting catalog can be freely accessed, searched, and downloaded by the scientific community. PMID:19105725

  5. Quantification of hepatic flow distribution using particle tracking for patient specific virtual Fontan surgery

    NASA Astrophysics Data System (ADS)

    Yang, Weiguang; Vignon-Clementel, Irene; Troianowski, Guillaume; Shadden, Shawn; Mohhan Reddy, V.; Feinstein, Jeffrey; Marsden, Alison

    2010-11-01

    The Fontan surgery is the third and final stage in a palliative series to treat children with single ventricle heart defects. In the extracardiac Fontan procedure, the inferior vena cava (IVC) is connected to the pulmonary arteries via a tube-shaped Gore-tex graft. Clinical observations have shown that the absence of a hepatic factor, carried in the IVC flow, can cause pulmonary arteriovenous malformations. Although it is clear that hepatic flow distribution is an important determinant of Fontan performance, few studies have quantified its relation to Fontan design. In this study, we virtually implanted three types of grafts (T-junction, offset and Y-graft) into 5 patient specific models of the Glenn (stage 2) anatomy. We then performed 3D time-dependent simulations and systematically compared the IVC flow distribution, energy loss, and pressure levels in different surgical designs. A robustness test is performed to evaluate the sensitivity of hepatic distribution to pulmonary flow split. Results show that the Y-graft design effectively improves the IVC flow distribution, compared to traditional designs and that surgical designs could be customized on a patient-by-patient basis.

  6. Influence of scale-dependent fracture intensity on block size distribution and rock slope failure mechanisms in a DFN framework

    NASA Astrophysics Data System (ADS)

    Agliardi, Federico; Galletti, Laura; Riva, Federico; Zanchi, Andrea; Crosta, Giovanni B.

    2017-04-01

    An accurate characterization of the geometry and intensity of discontinuities in a rock mass is key to assess block size distribution and degree of freedom. These are the main controls on the magnitude and mechanisms of rock slope instabilities (structurally-controlled, step-path or mass failures) and rock mass strength and deformability. Nevertheless, the use of over-simplified discontinuity characterization approaches, unable to capture the stochastic nature of discontinuity features, often hampers a correct identification of dominant rock mass behaviour. Discrete Fracture Network (DFN) modelling tools have provided new opportunities to overcome these caveats. Nevertheless, their ability to provide a representative picture of reality strongly depends on the quality and scale of field data collection. Here we used DFN modelling with FracmanTM to investigate the influence of fracture intensity, characterized on different scales and with different techniques, on the geometry and size distribution of generated blocks, in a rock slope stability perspective. We focused on a test site near Lecco (Southern Alps, Italy), where 600 m high cliffs in thickly-bedded limestones folded at the slope scale impend on the Lake Como. We characterized the 3D slope geometry by Structure-from-Motion photogrammetry (range: 150-1500m; point cloud density > 50 pts/m2). Since the nature and attributes of discontinuities are controlled by brittle failure processes associated to large-scale folding, we performed a field characterization of meso-structural features (faults and related kinematics, vein and joint associations) in different fold domains. We characterized the discontinuity populations identified by structural geology on different spatial scales ranging from outcrops (field surveys and photo-mapping) to large slope sectors (point cloud and photo-mapping). For each sampling domain, we characterized discontinuity orientation statistics and performed fracture mapping and circular

  7. Grids, virtualization, and clouds at Fermilab

    DOE PAGES

    Timm, S.; Chadwick, K.; Garzoglio, G.; ...

    2014-06-11

    Fermilab supports a scientific program that includes experiments and scientists located across the globe. To better serve this community, in 2004, the (then) Computing Division undertook the strategy of placing all of the High Throughput Computing (HTC) resources in a Campus Grid known as FermiGrid, supported by common shared services. In 2007, the FermiGrid Services group deployed a service infrastructure that utilized Xen virtualization, LVS network routing and MySQL circular replication to deliver highly available services that offered significant performance, reliability and serviceability improvements. This deployment was further enhanced through the deployment of a distributed redundant network core architecture andmore » the physical distribution of the systems that host the virtual machines across multiple buildings on the Fermilab Campus. In 2010, building on the experience pioneered by FermiGrid in delivering production services in a virtual infrastructure, the Computing Sector commissioned the FermiCloud, General Physics Computing Facility and Virtual Services projects to serve as platforms for support of scientific computing (FermiCloud 6 GPCF) and core computing (Virtual Services). Lastly, this work will present the evolution of the Fermilab Campus Grid, Virtualization and Cloud Computing infrastructure together with plans for the future.« less

  8. Virtual Observatory and Distributed Data Mining

    NASA Astrophysics Data System (ADS)

    Borne, Kirk D.

    2012-03-01

    New modes of discovery are enabled by the growth of data and computational resources (i.e., cyberinfrastructure) in the sciences. This cyberinfrastructure includes structured databases, virtual observatories (distributed data, as described in Section 20.2.1 of this chapter), high-performance computing (petascale machines), distributed computing (e.g., the Grid, the Cloud, and peer-to-peer networks), intelligent search and discovery tools, and innovative visualization environments. Data streams from experiments, sensors, and simulations are increasingly complex and growing in volume. This is true in most sciences, including astronomy, climate simulations, Earth observing systems, remote sensing data collections, and sensor networks. At the same time, we see an emerging confluence of new technologies and approaches to science, most clearly visible in the growing synergism of the four modes of scientific discovery: sensors-modeling-computing-data (Eastman et al. 2005). This has been driven by numerous developments, including the information explosion, development of large-array sensors, acceleration in high-performance computing (HPC) power, advances in algorithms, and efficient modeling techniques. Among these, the most extreme is the growth in new data. Specifically, the acquisition of data in all scientific disciplines is rapidly accelerating and causing a data glut (Bell et al. 2007). It has been estimated that data volumes double every year—for example, the NCSA (National Center for Supercomputing Applications) reported that their users cumulatively generated one petabyte of data over the first 19 years of NCSA operation, but they then generated their next one petabyte in the next year alone, and the data production has been growing by almost 100% each year after that (Butler 2008). The NCSA example is just one of many demonstrations of the exponential (annual data-doubling) growth in scientific data collections. In general, this putative data-doubling is an

  9. The effect of distributed virtual reality simulation training on cognitive load during subsequent dissection training.

    PubMed

    Andersen, Steven Arild Wuyts; Konge, Lars; Sørensen, Mads Sølvsten

    2018-05-07

    Complex tasks such as surgical procedures can induce excessive cognitive load (CL), which can have a negative effect on learning, especially for novices. To investigate if repeated and distributed virtual reality (VR) simulation practice induces a lower CL and higher performance in subsequent cadaveric dissection training. In a prospective, controlled cohort study, 37 residents in otorhinolaryngology received VR simulation training either as additional distributed practice prior to course participation (intervention) (9 participants) or as standard practice during the course (control) (28 participants). Cognitive load was estimated as the relative change in secondary-task reaction time during VR simulation and cadaveric procedures. Structured distributed VR simulation practice resulted in lower mean reaction times (32% vs. 47% for the intervention and control group, respectively, p < 0.01) as well as a superior final-product performance during subsequent cadaveric dissection training. Repeated and distributed VR simulation causes a lower CL to be induced when the learning situation is increased in complexity. A suggested mechanism is the formation of mental schemas and reduction of the intrinsic CL. This has potential implications for surgical skills training and suggests that structured, distributed training be systematically implemented in surgical training curricula.

  10. Revolutionizing Education: The Promise of Virtual Reality

    ERIC Educational Resources Information Center

    Gadelha, Rene

    2018-01-01

    Virtual reality (VR) has the potential to revolutionize education, as it immerses students in their learning more than any other available medium. By blocking out visual and auditory distractions in the classroom, it has the potential to help students deeply connect with the material they are learning in a way that has never been possible before.…

  11. Open multi-agent control architecture to support virtual-reality-based man-machine interfaces

    NASA Astrophysics Data System (ADS)

    Freund, Eckhard; Rossmann, Juergen; Brasch, Marcel

    2001-10-01

    Projective Virtual Reality is a new and promising approach to intuitively operable man machine interfaces for the commanding and supervision of complex automation systems. The user interface part of Projective Virtual Reality heavily builds on latest Virtual Reality techniques, a task deduction component and automatic action planning capabilities. In order to realize man machine interfaces for complex applications, not only the Virtual Reality part has to be considered but also the capabilities of the underlying robot and automation controller are of great importance. This paper presents a control architecture that has proved to be an ideal basis for the realization of complex robotic and automation systems that are controlled by Virtual Reality based man machine interfaces. The architecture does not just provide a well suited framework for the real-time control of a multi robot system but also supports Virtual Reality metaphors and augmentations which facilitate the user's job to command and supervise a complex system. The developed control architecture has already been used for a number of applications. Its capability to integrate sensor information from sensors of different levels of abstraction in real-time helps to make the realized automation system very responsive to real world changes. In this paper, the architecture will be described comprehensively, its main building blocks will be discussed and one realization that is built based on an open source real-time operating system will be presented. The software design and the features of the architecture which make it generally applicable to the distributed control of automation agents in real world applications will be explained. Furthermore its application to the commanding and control of experiments in the Columbus space laboratory, the European contribution to the International Space Station (ISS), is only one example which will be described.

  12. Interevent time distributions of human multi-level activity in a virtual world

    NASA Astrophysics Data System (ADS)

    Mryglod, O.; Fuchs, B.; Szell, M.; Holovatch, Yu.; Thurner, S.

    2015-02-01

    Studying human behavior in virtual environments provides extraordinary opportunities for a quantitative analysis of social phenomena with levels of accuracy that approach those of the natural sciences. In this paper we use records of player activities in the massive multiplayer online game Pardus over 1238 consecutive days, and analyze dynamical features of sequences of actions of players. We build on previous work where temporal structures of human actions of the same type were quantified, and provide an empirical understanding of human actions of different types. This study of multi-level human activity can be seen as a dynamic counterpart of static multiplex network analysis. We show that the interevent time distributions of actions in the Pardus universe follow highly non-trivial distribution functions, from which we extract action-type specific characteristic 'decay constants'. We discuss characteristic features of interevent time distributions, including periodic patterns on different time scales, bursty dynamics, and various functional forms on different time scales. We comment on gender differences of players in emotional actions, and find that while males and females act similarly when performing some positive actions, females are slightly faster for negative actions. We also observe effects on the age of players: more experienced players are generally faster in making decisions about engaging in and terminating enmity and friendship, respectively.

  13. Impact of distributed virtual reality on engineering knowledge retention and student engagement

    NASA Astrophysics Data System (ADS)

    Sulbaran, Tulio Alberto

    Engineering Education is facing many problems, one of which is poor knowledge retention among engineering students. This problem affects the Architecture, Engineering, and Construction (A/E/C) industry, because students are unprepared for many necessary job skills. This problem of poor knowledge retention is caused by many factors, one of which is the mismatch between student learning preferences and the media used to teach engineering. The purpose of this research is to assess the impact of Distributed Virtual Reality (DVR) as an engineering teaching tool. The implementation of DVR addresses the issue of poor knowledge retention by impacting the mismatch between learning and teaching style in the visual versus verbal spectrum. Using as a point of departure three knowledge domain areas (Learning and Instruction, Distributed Virtual Reality and Crane Selection as Part of Crane Lift Planning), a DVR engineering teaching tool is developed, deployed and assessed in engineering classrooms. The statistical analysis of the data indicates that: (1) most engineering students are visual learners; (2) most students would like more classes using DVR; (3) engineering students find DVR more engaging than traditional learning methods; (4) most students find the responsiveness of the DVR environments to be either good or very good; (5) all students are able to interact with DVR and most of the students found it easy or very easy to navigate (without previous formal training in how to use DVR); (6) students' knowledge regarding the subject (crane selection) is higher after the experiment; and, (7) students' using different instructional media do not demonstrate statistical difference in knowledge retained after the experiment. This inter-disciplinary research offers opportunities for direct and immediate application in education, research, and industry, due to the fact that the instructional module developed (on crane selection as part of construction crane lift planning) can be

  14. Energies and radial distributions of Bs mesons - the effect of hypercubic blocking

    NASA Astrophysics Data System (ADS)

    Koponen, Jonna

    2006-12-01

    This is a follow-up to our earlier work for the energies and the charge (vector) and matter (scalar) distributions for S-wave states in a heavy-light meson, where the heavy quark is static and the light quark has a mass about that of the strange quark. We study the radial distributions of higher angular momentum states, namely P- and D-wave states, using a "fuzzy" static quark. A new improvement is the use of hypercubic blocking in the time direction, which effectively constrains the heavy quark to move within a 2a hypercube (a is the lattice spacing). The calculation is carried out with dynamical fermions on a 163 × 32 lattice with a ≈ 0.10 fm generated using the non-perturbatively improved clover action. The configurations were gener- ated by the UKQCD Collaboration using lattice action parameters β = 5.2, c SW = 2.0171 and κ = 0.1350. In nature the closest equivalent of this heavy-light system is the Bs meson. Attempts are now being made to understand these results in terms of the Dirac equation.

  15. The virtual-casing principle and Helmholtz's theorem

    DOE PAGES

    Hanson, J. D.

    2015-09-10

    The virtual-casing principle is used in plasma physics to convert a Biot–Savart integration over a current distribution into a surface integral over a surface that encloses the current. In many circumstances, use of virtual casing can significantly speed up the computation of magnetic fields. In this paper, a virtual-casing principle is derived for a general vector field with arbitrary divergence and curl. This form of the virtual-casing principle is thus applicable to both magnetostatic fields and electrostatic fields. The result is then related to Helmholtz's theorem.

  16. Blocking Strategies for Performing Entity Resolution in a Distributed Computing Environment

    ERIC Educational Resources Information Center

    Wang, Pei

    2016-01-01

    Entity resolution (ER) is an O(n[superscript 2]) problem where n is the number of records to be processed. The pair-wise nature of ER makes it impractical to perform on large datasets without the use of a technique called blocking. In blocking the records are separated into groups (called blocks) in such a way the records most likely to match are…

  17. Guest Editor's introduction: Special issue on distributed virtual environments

    NASA Astrophysics Data System (ADS)

    Lea, Rodger

    1998-09-01

    Distributed virtual environments (DVEs) combine technology from 3D graphics, virtual reality and distributed systems to provide an interactive 3D scene that supports multiple participants. Each participant has a representation in the scene, often known as an avatar, and is free to navigate through the scene and interact with both the scene and other viewers of the scene. Changes to the scene, for example, position changes of one avatar as the associated viewer navigates through the scene, or changes to objects in the scene via manipulation, are propagated in real time to all viewers. This ensures that all viewers of a shared scene `see' the same representation of it, allowing sensible reasoning about the scene. Early work on such environments was restricted to their use in simulation, in particular in military simulation. However, over recent years a number of interesting and potentially far-reaching attempts have been made to exploit the technology for a range of other uses, including: Social spaces. Such spaces can be seen as logical extensions of the familiar text chat space. In 3D social spaces avatars, representing participants, can meet in shared 3D scenes and in addition to text chat can use visual cues and even in some cases spatial audio. Collaborative working. A number of recent projects have attempted to explore the use of DVEs to facilitate computer-supported collaborative working (CSCW), where the 3D space provides a context and work space for collaboration. Gaming. The shared 3D space is already familiar, albeit in a constrained manner, to the gaming community. DVEs are a logical superset of existing 3D games and can provide a rich framework for advanced gaming applications. e-commerce. The ability to navigate through a virtual shopping mall and to look at, and even interact with, 3D representations of articles has appealed to the e-commerce community as it searches for the best method of presenting merchandise to electronic consumers. The technology

  18. Nerve Blocks

    MedlinePlus

    ... turn off" a pain signal along a specific distribution of nerve. Imaging guidance may be used to place the needle in the most appropriate location for maximum benefit. A nerve block may allow a damaged nerve time to heal, provide temporary pain relief and help ...

  19. Evolving virtual creatures and catapults.

    PubMed

    Chaumont, Nicolas; Egli, Richard; Adami, Christoph

    2007-01-01

    We present a system that can evolve the morphology and the controller of virtual walking and block-throwing creatures (catapults) using a genetic algorithm. The system is based on Sims' work, implemented as a flexible platform with an off-the-shelf dynamics engine. Experiments aimed at evolving Sims-type walkers resulted in the emergence of various realistic gaits while using fairly simple objective functions. Due to the flexibility of the system, drastically different morphologies and functions evolved with only minor modifications to the system and objective function. For example, various throwing techniques evolved when selecting for catapults that propel a block as far as possible. Among the strategies and morphologies evolved, we find the drop-kick strategy, as well as the systematic invention of the principle behind the wheel, when allowing mutations to the projectile.

  20. Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kroll, Florian; Karsch, Leonhard; Pawelke, Jörg

    2013-08-15

    Purpose: Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-termmore » stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time.Methods: A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators.Results: Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account

  1. Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography.

    PubMed

    Kroll, Florian; Pawelke, Jörg; Karsch, Leonhard

    2013-08-01

    Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-term stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time. A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators. Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account, determined dose profiles are in

  2. Accuracy Validation of Large-scale Block Adjustment without Control of ZY3 Images over China

    NASA Astrophysics Data System (ADS)

    Yang, Bo

    2016-06-01

    Mapping from optical satellite images without ground control is one of the goals of photogrammetry. Using 8802 three linear array stereo images (a total of 26406 images) of ZY3 over China, we propose a large-scale and non-control block adjustment method of optical satellite images based on the RPC model, in which a single image is regarded as an adjustment unit to be organized. To overcome the block distortion caused by unstable adjustment without ground control and the excessive accumulation of errors, we use virtual control points created by the initial RPC model of the images as the weighted observations and add them into the adjustment model to refine the adjustment. We use 8000 uniformly distributed high precision check points to evaluate the geometric accuracy of the DOM (Digital Ortho Model) and DSM (Digital Surface Model) production, for which the standard deviations of plane and elevation are 3.6 m and 4.2 m respectively. The geometric accuracy is consistent across the whole block and the mosaic accuracy of neighboring DOM is within a pixel, thus, the seamless mosaic could take place. This method achieves the goal of an accuracy of mapping without ground control better than 5 m for the whole China from ZY3 satellite images.

  3. Distributed event-triggered consensus tracking of second-order multi-agent systems with a virtual leader

    NASA Astrophysics Data System (ADS)

    Jie, Cao; Zhi-Hai, Wu; Li, Peng

    2016-05-01

    This paper investigates the consensus tracking problems of second-order multi-agent systems with a virtual leader via event-triggered control. A novel distributed event-triggered transmission scheme is proposed, which is intermittently examined at constant sampling instants. Only partial neighbor information and local measurements are required for event detection. Then the corresponding event-triggered consensus tracking protocol is presented to guarantee second-order multi-agent systems to achieve consensus tracking. Numerical simulations are given to illustrate the effectiveness of the proposed strategy. Project supported by the National Natural Science Foundation of China (Grant Nos. 61203147, 61374047, and 61403168).

  4. Practical quantum private query of blocks based on unbalanced-state Bennett-Brassard-1984 quantum-key-distribution protocol

    NASA Astrophysics Data System (ADS)

    Wei, Chun-Yan; Gao, Fei; Wen, Qiao-Yan; Wang, Tian-Yin

    2014-12-01

    Until now, the only kind of practical quantum private query (QPQ), quantum-key-distribution (QKD)-based QPQ, focuses on the retrieval of a single bit. In fact, meaningful message is generally composed of multiple adjacent bits (i.e., a multi-bit block). To obtain a message from database, the user Alice has to query l times to get each ai. In this condition, the server Bob could gain Alice's privacy once he obtains the address she queried in any of the l queries, since each ai contributes to the message Alice retrieves. Apparently, the longer the retrieved message is, the worse the user privacy becomes. To solve this problem, via an unbalanced-state technique and based on a variant of multi-level BB84 protocol, we present a protocol for QPQ of blocks, which allows the user to retrieve a multi-bit block from database in one query. Our protocol is somewhat like the high-dimension version of the first QKD-based QPQ protocol proposed by Jacobi et al., but some nontrivial modifications are necessary.

  5. Practical quantum private query of blocks based on unbalanced-state Bennett-Brassard-1984 quantum-key-distribution protocol

    PubMed Central

    Wei, Chun-Yan; Gao, Fei; Wen, Qiao-Yan; Wang, Tian-Yin

    2014-01-01

    Until now, the only kind of practical quantum private query (QPQ), quantum-key-distribution (QKD)-based QPQ, focuses on the retrieval of a single bit. In fact, meaningful message is generally composed of multiple adjacent bits (i.e., a multi-bit block). To obtain a message from database, the user Alice has to query l times to get each ai. In this condition, the server Bob could gain Alice's privacy once he obtains the address she queried in any of the l queries, since each ai contributes to the message Alice retrieves. Apparently, the longer the retrieved message is, the worse the user privacy becomes. To solve this problem, via an unbalanced-state technique and based on a variant of multi-level BB84 protocol, we present a protocol for QPQ of blocks, which allows the user to retrieve a multi-bit block from database in one query. Our protocol is somewhat like the high-dimension version of the first QKD-based QPQ protocol proposed by Jacobi et al., but some nontrivial modifications are necessary. PMID:25518810

  6. SU-F-T-436: A Method to Evaluate Dosimetric Properties of SFGRT in Eclipse TPS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, M; Tobias, R; Pankuch, M

    Purpose: The objective was to develop a method for dose distribution calculation of spatially-fractionated-GRID-radiotherapy (SFGRT) in Eclipse treatment-planning-system (TPS). Methods: Patient treatment-plans with SFGRT for bulky tumors were generated in Varian Eclipse version11. A virtual structure based on the GRID pattern was created and registered to a patient CT image dataset. The virtual GRID structure was positioned on the iso-center level together with matching beam geometries to simulate a commercially available GRID block made of brass. This method overcame the difficulty in treatment-planning and dose-calculation due to the lack o-the option to insert a GRID block add-on in Eclipse TPS.more » The patient treatment-planning displayed GRID effects on the target, critical structures, and dose distribution. The dose calculations were compared to the measurement results in phantom. Results: The GRID block structure was created to follow the beam divergence to the patient CT images. The inserted virtual GRID block made it possible to calculate the dose distributions and profiles at various depths in Eclipse. The virtual GRID block was added as an option to TPS. The 3D representation of the isodose distribution of the spatially-fractionated beam was generated in axial, coronal, and sagittal planes. Physics of GRID can be different from that for fields shaped by regular blocks because the charge-particle-equilibrium cannot be guaranteed for small field openings. Output factor (OF) measurement was required to calculate the MU to deliver the prescribed dose. The calculated OF based on the virtual GRID agreed well with the measured OF in phantom. Conclusion: The method to create the virtual GRID block has been proposed for the first time in Eclipse TPS. The dosedistributions, in-plane and cross-plane profiles in PTV can be displayed in 3D-space. The calculated OF’s based on the virtual GRID model compare well to the measured OF’s for SFGRT clinical use.« less

  7. Shared virtual environments for aerospace training

    NASA Technical Reports Server (NTRS)

    Loftin, R. Bowen; Voss, Mark

    1994-01-01

    Virtual environments have the potential to significantly enhance the training of NASA astronauts and ground-based personnel for a variety of activities. A critical requirement is the need to share virtual environments, in real or near real time, between remote sites. It has been hypothesized that the training of international astronaut crews could be done more cheaply and effectively by utilizing such shared virtual environments in the early stages of mission preparation. The Software Technology Branch at NASA's Johnson Space Center has developed the capability for multiple users to simultaneously share the same virtual environment. Each user generates the graphics needed to create the virtual environment. All changes of object position and state are communicated to all users so that each virtual environment maintains its 'currency.' Examples of these shared environments will be discussed and plans for the utilization of the Department of Defense's Distributed Interactive Simulation (DIS) protocols for shared virtual environments will be presented. Finally, the impact of this technology on training and education in general will be explored.

  8. Simplified Virtualization in a HEP/NP Environment with Condor

    NASA Astrophysics Data System (ADS)

    Strecker-Kellogg, W.; Caramarcu, C.; Hollowell, C.; Wong, T.

    2012-12-01

    In this work we will address the development of a simple prototype virtualized worker node cluster, using Scientific Linux 6.x as a base OS, KVM and the libvirt API for virtualization, and the Condor batch software to manage virtual machines. The discussion in this paper provides details on our experience with building, configuring, and deploying the various components from bare metal, including the base OS, creation and distribution of the virtualized OS images and the integration of batch services with the virtual machines. Our focus was on simplicity and interoperability with our existing architecture.

  9. Virtual Astronomy: The Legacy of the Virtual Astronomical Observatory

    NASA Astrophysics Data System (ADS)

    Hanisch, Robert J.; Berriman, G. B.; Lazio, J.; Szalay, A. S.; Fabbiano, G.; Plante, R. L.; McGlynn, T. A.; Evans, J.; Emery Bunn, S.; Claro, M.; VAO Project Team

    2014-01-01

    Over the past ten years, the Virtual Astronomical Observatory (VAO, http://usvao.org) and its predecessor, the National Virtual Observatory (NVO), have developed and operated a software infrastructure consisting of standards and protocols for data and science software applications. The Virtual Observatory (VO) makes it possible to develop robust software for the discovery, access, and analysis of astronomical data. Every major publicly funded research organization in the US and worldwide has deployed at least some components of the VO infrastructure; tens of thousands of VO-enabled queries for data are invoked daily against catalog, image, and spectral data collections; and groups within the community have developed tools and applications building upon the VO infrastructure. Further, NVO and VAO have helped ensure access to data internationally by co-founding the International Virtual Observatory Alliance (IVOA, http://ivoa.net). The products of the VAO are being archived in a publicly accessible repository. Several science tools developed by the VAO will continue to be supported by the organizations that developed them: the Iris spectral energy distribution package (SAO), the Data Discovery Tool (STScI/MAST, HEASARC), and the scalable cross-comparison service (IPAC). The final year of VAO is focused on development of the data access protocol for data cubes, creation of Python language bindings to VO services, and deployment of a cloud-like data storage service that links to VO data discovery tools (SciDrive). We encourage the community to make use of these tools and services, to extend and improve them, and to carry on with the vision for virtual astronomy: astronomical research enabled by easy access to distributed data and computational resources. Funding for VAO development and operations has been provided jointly by NSF and NASA since May 2010. NSF funding will end in September 2014, though with the possibility of competitive solicitations for VO-based tool

  10. Full State Feedback Control for Virtual Power Plants

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Johnson, Jay Tillay

    This report presents an object-oriented implementation of full state feedback control for virtual power plants (VPP). The components of the VPP full state feedback control are (1) objectoriented high-fidelity modeling for all devices in the VPP; (2) Distribution System Distributed Quasi-Dynamic State Estimation (DS-DQSE) that enables full observability of the VPP by augmenting actual measurements with virtual, derived and pseudo measurements and performing the Quasi-Dynamic State Estimation (QSE) in a distributed manner, and (3) automated formulation of the Optimal Power Flow (OPF) in real time using the output of the DS-DQSE, and solving the distributed OPF to provide the optimalmore » control commands to the DERs of the VPP.« less

  11. Social pressure-induced craving in patients with alcohol dependence: application of virtual reality to coping skill training.

    PubMed

    Lee, Jung Suk; Namkoong, Kee; Ku, Jeonghun; Cho, Sangwoo; Park, Ji Yeon; Choi, You Kyong; Kim, Jae-Jin; Kim, In Young; Kim, Sun I; Jung, Young-Chul

    2008-12-01

    This study was conducted to assess the interaction between alcohol cues and social pressure in the induction of alcohol craving. Fourteen male patients with alcohol dependence and 14 age-matched social drinkers completed a virtual reality coping skill training program composed of four blocks according to the presence of alcohol cues (x2) and social pressure (x2). Before and after each block, the craving levels were measured using a visual analogue scale. Patients with alcohol dependence reported extremely high levels of craving immediately upon exposure to a virtual environment with alcohol cues, regardless of social pressure. In contrast, the craving levels of social drinkers were influenced by social pressure from virtual avatars. Our findings imply that an alcohol cue-laden environment should interfere with the ability to use coping skills against social pressure in real-life situations.

  12. The virtual-casing principle and Helmholtz’s theorem

    DOE PAGES

    Hanson, J. D.

    2015-09-10

    The virtual-casing principle is used in plasma physics to convert a Biot–Savart integration over a current distribution into a surface integral over a surface that encloses the current. In many circumstances, use of virtual casing can significantly speed up the computation of magnetic fields. In this paper, a virtual-casing principle is derived for a general vector field with arbitrary divergence and curl. This form of the virtual-casing principle is thus applicable to both magnetostatic fields and electrostatic fields. The result is then related to Helmholtz’s theorem.

  13. Shared protection based virtual network mapping in space division multiplexing optical networks

    NASA Astrophysics Data System (ADS)

    Zhang, Huibin; Wang, Wei; Zhao, Yongli; Zhang, Jie

    2018-05-01

    Space Division Multiplexing (SDM) has been introduced to improve the capacity of optical networks. In SDM optical networks, there are multiple cores/modes in each fiber link, and spectrum resources are multiplexed in both frequency and core/modes dimensions. Enabled by network virtualization technology, one SDM optical network substrate can be shared by several virtual networks operators. Similar with point-to-point connection services, virtual networks (VN) also need certain survivability to guard against network failures. Based on customers' heterogeneous requirements on the survivability of their virtual networks, this paper studies the shared protection based VN mapping problem and proposes a Minimum Free Frequency Slots (MFFS) mapping algorithm to improve spectrum efficiency. Simulation results show that the proposed algorithm can optimize SDM optical networks significantly in terms of blocking probability and spectrum utilization.

  14. Toward a comprehensive hybrid physical-virtual reality simulator of peripheral anesthesia with ultrasound and neurostimulator guidance.

    PubMed

    Samosky, Joseph T; Allen, Pete; Boronyak, Steve; Branstetter, Barton; Hein, Steven; Juhas, Mark; Nelson, Douglas A; Orebaugh, Steven; Pinto, Rohan; Smelko, Adam; Thompson, Mitch; Weaver, Robert A

    2011-01-01

    We are developing a simulator of peripheral nerve block utilizing a mixed-reality approach: the combination of a physical model, an MRI-derived virtual model, mechatronics and spatial tracking. Our design uses tangible (physical) interfaces to simulate surface anatomy, haptic feedback during needle insertion, mechatronic display of muscle twitch corresponding to the specific nerve stimulated, and visual and haptic feedback for the injection syringe. The twitch response is calculated incorporating the sensed output of a real neurostimulator. The virtual model is isomorphic with the physical model and is derived from segmented MRI data. This model provides the subsurface anatomy and, combined with electromagnetic tracking of a sham ultrasound probe and a standard nerve block needle, supports simulated ultrasound display and measurement of needle location and proximity to nerves and vessels. The needle tracking and virtual model also support objective performance metrics of needle targeting technique.

  15. A workout for virtual bodybuilders (design issues for embodiment in multi-actor virtual environments)

    NASA Technical Reports Server (NTRS)

    Benford, Steve; Bowers, John; Fahlen, Lennart E.; Greenhalgh, Chris; Snowdon, Dave

    1994-01-01

    This paper explores the issue of user embodiment within collaborative virtual environments. By user embodiment we mean the provision of users with appropriate body images so as to represent them to others and also to themselves. By collaborative virtual environments we mean multi-user virtual reality systems which support cooperative work (although we argue that the results of our exploration may also be applied to other kinds of collaborative systems). The main part of the paper identifies a list of embodiment design issues including: presence, location, identity, activity, availability, history of activity, viewpoint, action point, gesture, facial expression, voluntary versus involuntary expression, degree of presence, reflecting capabilities, manipulating the user's view of others, representation across multiple media, autonomous and distributed body parts, truthfulness and efficiency. Following this, we show how these issues are reflected in our own DIVE and MASSIVE prototype collaborative virtual environments.

  16. Catchment virtual observatory for sharing flow and transport models outputs: using residence time distribution to compare contrasting catchments

    NASA Astrophysics Data System (ADS)

    Thomas, Zahra; Rousseau-Gueutin, Pauline; Kolbe, Tamara; Abbott, Ben; Marcais, Jean; Peiffer, Stefan; Frei, Sven; Bishop, Kevin; Le Henaff, Geneviève; Squividant, Hervé; Pichelin, Pascal; Pinay, Gilles; de Dreuzy, Jean-Raynald

    2017-04-01

    The distribution of groundwater residence time in a catchment provides synoptic information about catchment functioning (e.g. nutrient retention and removal, hydrograph flashiness). In contrast with interpreted model results, which are often not directly comparable between studies, residence time distribution is a general output that could be used to compare catchment behaviors and test hypotheses about landscape controls on catchment functioning. In this goal, we created a virtual observatory platform called Catchment Virtual Observatory for Sharing Flow and Transport Model Outputs (COnSOrT). The main goal of COnSOrT is to collect outputs from calibrated groundwater models from a wide range of environments. By comparing a wide variety of catchments from different climatic, topographic and hydrogeological contexts, we expect to enhance understanding of catchment connectivity, resilience to anthropogenic disturbance, and overall functioning. The web-based observatory will also provide software tools to analyze model outputs. The observatory will enable modelers to test their models in a wide range of catchment environments to evaluate the generality of their findings and robustness of their post-processing methods. Researchers with calibrated numerical models can benefit from observatory by using the post-processing methods to implement a new approach to analyzing their data. Field scientists interested in contributing data could invite modelers associated with the observatory to test their models against observed catchment behavior. COnSOrT will allow meta-analyses with community contributions to generate new understanding and identify promising pathways forward to moving beyond single catchment ecohydrology. Keywords: Residence time distribution, Models outputs, Catchment hydrology, Inter-catchment comparison

  17. Anesthesiology training using 3D imaging and virtual reality

    NASA Astrophysics Data System (ADS)

    Blezek, Daniel J.; Robb, Richard A.; Camp, Jon J.; Nauss, Lee A.

    1996-04-01

    Current training for regional nerve block procedures by anesthesiology residents requires expert supervision and the use of cadavers; both of which are relatively expensive commodities in today's cost-conscious medical environment. We are developing methods to augment and eventually replace these training procedures with real-time and realistic computer visualizations and manipulations of the anatomical structures involved in anesthesiology procedures, such as nerve plexus injections (e.g., celiac blocks). The initial work is focused on visualizations: both static images and rotational renderings. From the initial results, a coherent paradigm for virtual patient and scene representation will be developed.

  18. Live Virtual Constructive Distributed Test Environment Characterization Report

    NASA Technical Reports Server (NTRS)

    Murphy, Jim; Kim, Sam K.

    2013-01-01

    This report documents message latencies observed over various Live, Virtual, Constructive, (LVC) simulation environment configurations designed to emulate possible system architectures for the Unmanned Aircraft Systems (UAS) Integration in the National Airspace System (NAS) Project integrated tests. For each configuration, four scenarios with progressively increasing air traffic loads were used to determine system throughput and bandwidth impacts on message latency.

  19. Estimation of distribution algorithm with path relinking for the blocking flow-shop scheduling problem

    NASA Astrophysics Data System (ADS)

    Shao, Zhongshi; Pi, Dechang; Shao, Weishi

    2018-05-01

    This article presents an effective estimation of distribution algorithm, named P-EDA, to solve the blocking flow-shop scheduling problem (BFSP) with the makespan criterion. In the P-EDA, a Nawaz-Enscore-Ham (NEH)-based heuristic and the random method are combined to generate the initial population. Based on several superior individuals provided by a modified linear rank selection, a probabilistic model is constructed to describe the probabilistic distribution of the promising solution space. The path relinking technique is incorporated into EDA to avoid blindness of the search and improve the convergence property. A modified referenced local search is designed to enhance the local exploitation. Moreover, a diversity-maintaining scheme is introduced into EDA to avoid deterioration of the population. Finally, the parameters of the proposed P-EDA are calibrated using a design of experiments approach. Simulation results and comparisons with some well-performing algorithms demonstrate the effectiveness of the P-EDA for solving BFSP.

  20. Column generation algorithms for virtual network embedding in flexi-grid optical networks.

    PubMed

    Lin, Rongping; Luo, Shan; Zhou, Jingwei; Wang, Sheng; Chen, Bin; Zhang, Xiaoning; Cai, Anliang; Zhong, Wen-De; Zukerman, Moshe

    2018-04-16

    Network virtualization provides means for efficient management of network resources by embedding multiple virtual networks (VNs) to share efficiently the same substrate network. Such virtual network embedding (VNE) gives rise to a challenging problem of how to optimize resource allocation to VNs and to guarantee their performance requirements. In this paper, we provide VNE algorithms for efficient management of flexi-grid optical networks. We provide an exact algorithm aiming to minimize the total embedding cost in terms of spectrum cost and computation cost for a single VN request. Then, to achieve scalability, we also develop a heuristic algorithm for the same problem. We apply these two algorithms for a dynamic traffic scenario where many VN requests arrive one-by-one. We first demonstrate by simulations for the case of a six-node network that the heuristic algorithm obtains very close blocking probabilities to exact algorithm (about 0.2% higher). Then, for a network of realistic size (namely, USnet) we demonstrate that the blocking probability of our new heuristic algorithm is about one magnitude lower than a simpler heuristic algorithm, which was a component of an earlier published algorithm.

  1. Calcium Channel Block by Cadmium in Chicken Sensory Neurons

    NASA Astrophysics Data System (ADS)

    Swandulla, D.; Armstrong, C. M.

    1989-03-01

    Cadmium block of calcium channels was studied in chicken dorsal root ganglion cells by a whole-cell patch clamp that provides high time resolution. Barium ion was the current carrier, and the channel type studied had a high threshold of activation and fast deactivation (type FD). Block of these channels by 20 μ M external Cd2+ is voltage dependent. Cd2+ ions can be cleared from blocked channels by stepping the membrane voltage (Vm) to a negative value. Clearing the channels is progressively faster and more complete as Vm is made more negative. Once cleared of Cd2+, the channels conduct transiently on reopening but reequilibrate with Cd2+ and become blocked within a few milliseconds. Cd2+ equilibrates much more slowly with closed channels, but at a holding potential of -80 mV virtually all channels are blocked at equilibrium. Cd2+ does not slow closing of the channels, as would be expected if it were necessary for Cd2+ to leave the channels before closing occurred. Instead, the data show unambiguously that the channel gate can close when the channel is Cd2+ occupied.

  2. Extraction of Generalized Parton Distributions from combined Deeply Virtual Compton Scattering and Timelike Compton scattering fits

    NASA Astrophysics Data System (ADS)

    Boer, Marie

    2017-09-01

    Generalized Parton Distributions (GPDs) contain the correlation between the parton's longitudinal momentum and their transverse distribution. They are accessed through hard exclusive processes, such as Deeply Virtual Compton Scattering (DVCS). DVCS has already been measured in several experiments and several models allow for extracting GPDs from these measurements. Timelike Compton Scattering (TCS) is, at leading order, the time-reversal equivalent process to DVCS and accesses GPDs at the same kinematics. Comparing GPDs extracted from DVCS and TCS is a unique way for proving GPD universality. Combining fits from the two processes will also allow for better constraining the GPDs. We will present our method for extracting GPDs from DVCS and TCS pseudo-data. We will compare fit results from the two processes in similar conditions and present what can be expected in term of contraints on GPDs from combined fits.

  3. Reports on block rotations, fault domains and crustal deformation

    NASA Technical Reports Server (NTRS)

    Nur, Amos

    1990-01-01

    Studies of block rotations, fault domains and crustal deformation in the western United States, Israel, and China are discussed. Topics include a three-dimensional model of crustal fracture by distributed fault sets, distributed deformation and block rotation in 3D, stress field rotation, and multiple strike slip fault sets.

  4. Practical quantum private query of blocks based on unbalanced-state Bennett-Brassard-1984 quantum-key-distribution protocol.

    PubMed

    Wei, Chun-Yan; Gao, Fei; Wen, Qiao-Yan; Wang, Tian-Yin

    2014-12-18

    Until now, the only kind of practical quantum private query (QPQ), quantum-key-distribution (QKD)-based QPQ, focuses on the retrieval of a single bit. In fact, meaningful message is generally composed of multiple adjacent bits (i.e., a multi-bit block). To obtain a message a1a2···al from database, the user Alice has to query l times to get each ai. In this condition, the server Bob could gain Alice's privacy once he obtains the address she queried in any of the l queries, since each a(i) contributes to the message Alice retrieves. Apparently, the longer the retrieved message is, the worse the user privacy becomes. To solve this problem, via an unbalanced-state technique and based on a variant of multi-level BB84 protocol, we present a protocol for QPQ of blocks, which allows the user to retrieve a multi-bit block from database in one query. Our protocol is somewhat like the high-dimension version of the first QKD-based QPQ protocol proposed by Jacobi et al., but some nontrivial modifications are necessary.

  5. Virtual gonio-spectrophotometer for validation of BRDF designs

    NASA Astrophysics Data System (ADS)

    Mihálik, Andrej; Ďurikovič, Roman

    2011-10-01

    Measurement of the appearance of an object consists of a group of measurements to characterize the color and surface finish of the object. This group of measurements involves the spectral energy distribution of propagated light measured in terms of reflectance and transmittance, and the spatial energy distribution of that light measured in terms of the bidirectional reflectance distribution function (BRDF). In this article we present the virtual gonio-spectrophotometer, a device that measures flux (power) as a function of illumination and observation. Virtual gonio-spectrophotometer measurements allow the determination of the scattering profile of specimens that can be used to verify the physical characteristics of the computer model used to simulate the scattering profile. Among the characteristics that we verify is the energy conservation of the computer model. A virtual gonio-spectrophotometer is utilized to find the correspondence between industrial measurements obtained from gloss meters and the parameters of a computer reflectance model.

  6. On delay adjustment for dynamic load balancing in distributed virtual environments.

    PubMed

    Deng, Yunhua; Lau, Rynson W H

    2012-04-01

    Distributed virtual environments (DVEs) are becoming very popular in recent years, due to the rapid growing of applications, such as massive multiplayer online games (MMOGs). As the number of concurrent users increases, scalability becomes one of the major challenges in designing an interactive DVE system. One solution to address this scalability problem is to adopt a multi-server architecture. While some methods focus on the quality of partitioning the load among the servers, others focus on the efficiency of the partitioning process itself. However, all these methods neglect the effect of network delay among the servers on the accuracy of the load balancing solutions. As we show in this paper, the change in the load of the servers due to network delay would affect the performance of the load balancing algorithm. In this work, we conduct a formal analysis of this problem and discuss two efficient delay adjustment schemes to address the problem. Our experimental results show that our proposed schemes can significantly improve the performance of the load balancing algorithm with neglectable computation overhead.

  7. Manipulation of volumetric patient data in a distributed virtual reality environment.

    PubMed

    Dech, F; Ai, Z; Silverstein, J C

    2001-01-01

    Due to increases in network speed and bandwidth, distributed exploration of medical data in immersive Virtual Reality (VR) environments is becoming increasingly feasible. The volumetric display of radiological data in such environments presents a unique set of challenges. The shear size and complexity of the datasets involved not only make them difficult to transmit to remote sites, but these datasets also require extensive user interaction in order to make them understandable to the investigator and manageable to the rendering hardware. A sophisticated VR user interface is required in order for the clinician to focus on the aspects of the data that will provide educational and/or diagnostic insight. We will describe a software system of data acquisition, data display, Tele-Immersion, and data manipulation that supports interactive, collaborative investigation of large radiological datasets. The hardware required in this strategy is still at the high-end of the graphics workstation market. Future software ports to Linux and NT, along with the rapid development of PC graphics cards, open the possibility for later work with Linux or NT PCs and PC clusters.

  8. KNBD: A Remote Kernel Block Server for Linux

    NASA Technical Reports Server (NTRS)

    Becker, Jeff

    1999-01-01

    I am developing a prototype of a Linux remote disk block server whose purpose is to serve as a lower level component of a parallel file system. Parallel file systems are an important component of high performance supercomputers and clusters. Although supercomputer vendors such as SGI and IBM have their own custom solutions, there has been a void and hence a demand for such a system on Beowulf-type PC Clusters. Recently, the Parallel Virtual File System (PVFS) project at Clemson University has begun to address this need (1). Although their system provides much of the functionality of (and indeed was inspired by) the equivalent file systems in the commercial supercomputer market, their system is all in user-space. Migrating their 10 services to the kernel could provide a performance boost, by obviating the need for expensive system calls. Thanks to Pavel Machek, the Linux kernel has provided the network block device (2) with kernels 2.1.101 and later. You can configure this block device to redirect reads and writes to a remote machine's disk. This can be used as a building block for constructing a striped file system across several nodes.

  9. Using Immersive Virtual Reality for Electrical Substation Training

    ERIC Educational Resources Information Center

    Tanaka, Eduardo H.; Paludo, Juliana A.; Cordeiro, Carlúcio S.; Domingues, Leonardo R.; Gadbem, Edgar V.; Euflausino, Adriana

    2015-01-01

    Usually, distribution electricians are called upon to solve technical problems found in electrical substations. In this project, we apply problem-based learning to a training program for electricians, with the help of a virtual reality environment that simulates a real substation. Using this virtual substation, users may safely practice maneuvers…

  10. Performance Analysis of Ivshmem for High-Performance Computing in Virtual Machines

    NASA Astrophysics Data System (ADS)

    Ivanovic, Pavle; Richter, Harald

    2018-01-01

    High-Performance computing (HPC) is rarely accomplished via virtual machines (VMs). In this paper, we present a remake of ivshmem which can change this. Ivshmem was a shared memory (SHM) between virtual machines on the same server, with SHM-access synchronization included, until about 5 years ago when newer versions of Linux and its virtualization library libvirt evolved. We restored that SHM-access synchronization feature because it is indispensable for HPC and made ivshmem runnable with contemporary versions of Linux, libvirt, KVM, QEMU and especially MPICH, which is an implementation of MPI - the standard HPC communication library. Additionally, MPICH was transparently modified by us to get ivshmem included, resulting in a three to ten times performance improvement compared to TCP/IP. Furthermore, we have transparently replaced MPI_PUT, a single-side MPICH communication mechanism, by an own MPI_PUT wrapper. As a result, our ivshmem even surpasses non-virtualized SHM data transfers for block lengths greater than 512 KBytes, showing the benefits of virtualization. All improvements were possible without using SR-IOV.

  11. Cooperative storage of shared files in a parallel computing system with dynamic block size

    DOEpatents

    Bent, John M.; Faibish, Sorin; Grider, Gary

    2015-11-10

    Improved techniques are provided for parallel writing of data to a shared object in a parallel computing system. A method is provided for storing data generated by a plurality of parallel processes to a shared object in a parallel computing system. The method is performed by at least one of the processes and comprises: dynamically determining a block size for storing the data; exchanging a determined amount of the data with at least one additional process to achieve a block of the data having the dynamically determined block size; and writing the block of the data having the dynamically determined block size to a file system. The determined block size comprises, e.g., a total amount of the data to be stored divided by the number of parallel processes. The file system comprises, for example, a log structured virtual parallel file system, such as a Parallel Log-Structured File System (PLFS).

  12. [Virtual water content of livestock products in China].

    PubMed

    Wang, Hong-rui; Wang, Jun-hong

    2006-04-01

    The paper expatiated the virtual water content concept of livestock products and the study meaning on developing virtual water trade of livestock products in China, then summarized the calculation methods on virtual water and virtual water trade of livestock products. Based on these, the paper analyzed and researched every province virtual water content of livestock products in details, then elicited various situation of every province virtual water content of livestock products in China by year. Moreover, it compared virtual water content of livestock products with local water resources. The study indicated the following results: (1) The virtual water content of livestock products is increasing rapidly in China recently, especially poultry eggs and pork. (2) The distribution of virtual water content of livestock products is not balanced, mainly lies in North China, East China and so on; (3) The increasing production of livestock in Beijing City, Tianjin City, Hebei, Nei Monggol, Liaononing, Jilin, Shandong, Henan and Ningxia province and autonom ous region will bring pressure to local water shortage.

  13. RoBlock: a prototype autonomous manufacturing cell

    NASA Astrophysics Data System (ADS)

    Baekdal, Lars K.; Balslev, Ivar; Eriksen, Rene D.; Jensen, Soren P.; Jorgensen, Bo N.; Kirstein, Brian; Kristensen, Bent B.; Olsen, Martin M.; Perram, John W.; Petersen, Henrik G.; Petersen, Morten L.; Ruhoff, Peter T.; Skjolstrup, Carl E.; Sorensen, Anders S.; Wagenaar, Jeroen M.

    2000-10-01

    RoBlock is the first phase of an internally financed project at the Institute aimed at building a system in which two industrial robots suspended from a gantry, as shown below, cooperate to perform a task specified by an external user, in this case, assembling an unstructured collection of colored wooden blocks into a specified 3D pattern. The blocks are identified and localized using computer vision and grasped with a suction cup mechanism. Future phases of the project will involve other processes such as grasping and lifting, as well as other types of robot such as autonomous vehicles or variable geometry trusses. Innovative features of the control software system include: The use of an advanced trajectory planning system which ensures collision avoidance based on a generalization of the method of artificial potential fields, the use of a generic model-based controller which learns the values of parameters, including static and kinetic friction, of a detailed mechanical model of itself by comparing actual with planned movements, the use of fast, flexible, and robust pattern recognition and 3D-interpretation strategies, integration of trajectory planning and control with the sensor systems in a distributed Java application running on a network of PC's attached to the individual physical components. In designing this first stage, the aim was to build in the minimum complexity necessary to make the system non-trivially autonomous and to minimize the technological risks. The aims of this project, which is planned to be operational during 2000, are as follows: To provide a platform for carrying out experimental research in multi-agent systems and autonomous manufacturing systems, to test the interdisciplinary cooperation architecture of the Maersk Institute, in which researchers in the fields of applied mathematics (modeling the physical world), software engineering (modeling the system) and sensor/actuator technology (relating the virtual and real worlds) could

  14. Effect of virtual reality-based rehabilitation on upper-extremity function in patients with brain tumor: controlled trial.

    PubMed

    Yoon, Jisun; Chun, Min Ho; Lee, Sook Joung; Kim, Bo Ryun

    2015-06-01

    The aim of this study was to evaluate the benefit of virtual reality-based rehabilitation on upper-extremity function in patients with brain tumor. Patients with upper-extremity dysfunction were divided into age-matched and tumor type-matched two groups. The intervention group performed the virtual reality program 30 mins per session for 9 sessions and conventional occupational therapy 30 mins per session for 6 sessions for 3 wks, whereas the control group received conventional occupational therapy alone 30 mins per session for 15 sessions for 3 wks. The Box and Block test, the Manual Function test, and the Fugl-Meyer scale were used to evaluate upper-extremity function. The Korean version of the Modified Barthel Index was used to assess activities of daily living. Forty patients completed the study (20 for each group). Each group exhibited significant posttreatment improvements in the Box and Block test, Manual Function test, Fugl-Meyer scale, and Korean version of the Modified Barthel Index scores. The Box and Block test, the Fugl-Meyer scale, and the Manual Function test showed greater improvements in shoulder/elbow/forearm function in the intervention group and hand function in the control group. Virtual reality-based rehabilitation combined with conventional occupational therapy may be more effective than conventional occupational therapy, especially for proximal upper-extremity function in patients with brain tumor. Further studies considering hand function, such as use of virtual reality programs that targeting hand use, are required.

  15. Visual appearance of a virtual upper limb modulates the temperature of the real hand: a thermal imaging study in Immersive Virtual Reality.

    PubMed

    Tieri, Gaetano; Gioia, Annamaria; Scandola, Michele; Pavone, Enea F; Aglioti, Salvatore M

    2017-05-01

    To explore the link between Sense of Embodiment (SoE) over a virtual hand and physiological regulation of skin temperature, 24 healthy participants were immersed in virtual reality through a Head Mounted Display and had their real limb temperature recorded by means of a high-sensitivity infrared camera. Participants observed a virtual right upper limb (appearing either normally, or with the hand detached from the forearm) or limb-shaped non-corporeal control objects (continuous or discontinuous wooden blocks) from a first-person perspective. Subjective ratings of SoE were collected in each observation condition, as well as temperatures of the right and left hand, wrist and forearm. The observation of these complex, body and body-related virtual scenes resulted in increased real hand temperature when compared to a baseline condition in which a 3d virtual ball was presented. Crucially, observation of non-natural appearances of the virtual limb (discontinuous limb) and limb-shaped non-corporeal objects elicited high increase in real hand temperature and low SoE. In contrast, observation of the full virtual limb caused high SoE and low temperature changes in the real hand with respect to the other conditions. Interestingly, the temperature difference across the different conditions occurred according to a topographic rule that included both hands. Our study sheds new light on the role of an external hand's visual appearance and suggests a tight link between higher-order bodily self-representations and topographic regulation of skin temperature. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  16. Evaluating small-body landing hazards due to blocks

    NASA Astrophysics Data System (ADS)

    Ernst, C.; Rodgers, D.; Barnouin, O.; Murchie, S.; Chabot, N.

    2014-07-01

    of several to ten), the size-frequency distribution of blocks can be modeled, allowing extrapolation from large block distributions to estimate small block densities. From that estimate, the probability of a lander encountering hazardous blocks can be calculated for a given lander design. Such calculations are used routinely to vet candidate sites for Mars landers [5--8]. Application to Small Bodies: To determine whether a similar approach will work for small bodies, we must determine if the large and small block populations can be linked. To do so, we analyze the comprehensive block datasets for the intermediate-sized Eros [9,10] and the small Itokawa [11,12]. Global and local block size-frequency distributions for Eros and Itokawa have power-law slopes on the order of -3 and match reasonably well between larger block sizes (from lower-resolution images) and smaller block sizes (from higher-resolution images). Although absolute block densities differ regionally on each asteroid, the slopes match reasonably well between Itokawa and Eros, with the geologic implications of this result discussed in [10]. For Eros and Itokawa, the approach of extending the size-frequency distribution from large, tens-of-meter-sized blocks down to small, tens-of-centimeter-sized blocks using a power-law fit to the large population yields reasonable estimates of small block populations. It is important to note that geologic context matters for the absolute block density --- if the global counts include multiple geologic settings, they will not directly extend to local areas containing only one setting [10]. A small number of high-resolution images of Phobos are sufficient for measuring blocks. These images are concentrated in the area outside of Stickney crater, which is thought to be the source of most of the observed blocks [13]. Block counts by Thomas et al. [13] suggest a power-law slope similar to those of Eros [9] and Itokawa global counts, with the absolute density of blocks similar

  17. Virtual Sensor Test Instrumentation

    NASA Technical Reports Server (NTRS)

    Wang, Roy

    2011-01-01

    Virtual Sensor Test Instrumentation is based on the concept of smart sensor technology for testing with intelligence needed to perform sell-diagnosis of health, and to participate in a hierarchy of health determination at sensor, process, and system levels. A virtual sensor test instrumentation consists of five elements: (1) a common sensor interface, (2) microprocessor, (3) wireless interface, (4) signal conditioning and ADC/DAC (analog-to-digital conversion/ digital-to-analog conversion), and (5) onboard EEPROM (electrically erasable programmable read-only memory) for metadata storage and executable software to create powerful, scalable, reconfigurable, and reliable embedded and distributed test instruments. In order to maximize the efficient data conversion through the smart sensor node, plug-and-play functionality is required to interface with traditional sensors to enhance their identity and capabilities for data processing and communications. Virtual sensor test instrumentation can be accessible wirelessly via a Network Capable Application Processor (NCAP) or a Smart Transducer Interlace Module (STIM) that may be managed under real-time rule engines for mission-critical applications. The transducer senses the physical quantity being measured and converts it into an electrical signal. The signal is fed to an A/D converter, and is ready for use by the processor to execute functional transformation based on the sensor characteristics stored in a Transducer Electronic Data Sheet (TEDS). Virtual sensor test instrumentation is built upon an open-system architecture with standardized protocol modules/stacks to interface with industry standards and commonly used software. One major benefit for deploying the virtual sensor test instrumentation is the ability, through a plug-and-play common interface, to convert raw sensor data in either analog or digital form, to an IEEE 1451 standard-based smart sensor, which has instructions to program sensors for a wide variety of

  18. Ballistic Blocks Surrounding Kilauea's Caldera

    NASA Astrophysics Data System (ADS)

    Swanson, D.; Zolkos, S.; Haravitch, B.

    2010-12-01

    Thousands of lithic blocks dot the surface around Kilauea’s caldera, erupted ballistically at the end of the 1790 eruption or soon thereafter. Most of the blocks occur in the western and southern sectors, probably reflecting the proximity of vents on the caldera floor. We mapped the ejecta field, measuring most of the blocks with nominal diameters ((a+b+c)/3) more than 75 cm and many of the smaller ones, noting distinctive lithologies. The distributions, sizes, and lithologies suggest 7-8 different ballistic bursts from 3-4 generalized vent areas. We measured 15 blocks with nominal diameters (ND) of 150-201 cm, 169 blocks with ND 100-149 cm, 308 blocks with ND 75-99 cm, 684 blocks with ND 50-74 cm, and 545 blocks with ND 25-49 cm. The smaller blocks were measured only in outlying areas, where they were the largest in the neighborhood, but they occur throughout the field. Twelve blocks with ND >150 cm lie within 1.7 km west and south of the center of Halema`uma`u; a vent near this location likely erupted the blocks. Three of the largest blocks, however, are 2.2-2.7 km north of Halema`uma`u and probably came from a more northerly vent. This interpretation is supported by the distributions of all blocks with ND >100 cm, which define at least 4, and possibly 5, different dispersal lobes; three cluster near Halema`uma`u, one is slightly north, and the one with the three large blocks is still farther north. The blocks have typical lithologies for Kilauea’s summit, including coarse basalt or fine gabbro derived from the centers of thick flows, solidified lakes, or small intrusions. Three lithologies are distinctive and help define 3, possibly 4, discrete bursts. Blocks of fine-grained basalt riddled with segregation veins occur only in a lobe 1.3 km wide reaching as far as 1.8 km southwest of Halema`uma`u; this lobe overlaps slightly with one defined by block size but is mostly distinct and probably indicates a separate burst. A cluster of blocks with puffy, somewhat

  19. Design of virtual display and testing system for moving mass electromechanical actuator

    NASA Astrophysics Data System (ADS)

    Gao, Zhigang; Geng, Keda; Zhou, Jun; Li, Peng

    2015-12-01

    Aiming at the problem of control, measurement and movement virtual display of moving mass electromechanical actuator(MMEA), the virtual testing system of MMEA was developed based on the PC-DAQ architecture and the software platform of LabVIEW, and the comprehensive test task such as drive control of MMEA, tests of kinematic parameter, measurement of centroid position and virtual display of movement could be accomplished. The system could solve the alignment for acquisition time between multiple measurement channels in different DAQ cards, then on this basis, the researches were focused on the dynamic 3D virtual display by the LabVIEW, and the virtual display of MMEA were realized by the method of calling DLL and the method of 3D graph drawing controls. Considering the collaboration with the virtual testing system, including the hardware drive, the measurement software of data acquisition, and the 3D graph drawing controls method was selected, which could obtained the synchronization measurement, control and display. The system can measure dynamic centroid position and kinematic position of movable mass block while controlling the MMEA, and the interface of 3D virtual display has realistic effect and motion smooth, which can solve the problem of display and playback about MMEA in the closed shell.

  20. Distribution of blocking temperatures in nano-oxide layers of specular spin valves

    NASA Astrophysics Data System (ADS)

    Ventura, J.; Araujo, J. P.; Sousa, J. B.; Veloso, A.; Freitas, P. P.

    2007-06-01

    Specular spin valves show enhanced giant magnetoresistive (GMR) ratio when compared to other, simpler, spin valve structures. The enhancement of GMR results from specular reflection in nano-oxide layers (NOLs) formed by the partial oxidation of the pinned and free layer. These oxides forming the NOL order antiferromagnetically (AFM) below a temperature T ˜175 K. Here, we study the effects of the pinned layer magnetization and its domain structure on the AFM ordering of the NOL by performing field cooling measurements with different cooling fields (H0). We observe enhanced (reduced) exchange field and magnetoresistive ratio for H0>0(<0), i.e., parallel (antiparallel) to the pinned magnetization. These measurements allowed us to confirm the existence of a wide distribution of blocking temperatures (TB) in the NOL of specular spin valves, having a maximum at T ≈175 K, and extending to NOL regions with TB as low as 15 K.

  1. A Study Comparing the Pedagogical Effectiveness of Virtual Worlds and of Classical Methods

    DTIC Science & Technology

    2014-08-01

    Approved for public release; distribution is unlimited. A Study Comparing the Pedagogical Effectiveness of Virtual Worlds and of Classical Methods...ABSTRACT A Study Comparing the Pedagogical Effectiveness of Virtual Worlds and of Classical Methods Report Title This experiment tests whether a virtual... PEDAGOGICAL EFFECTIVENESS OF VIRTUAL WORLDS AND OF TRADITIONAL TRAINING METHODS A Thesis by BENJAMIN PETERS

  2. Virtual goods recommendations in virtual worlds.

    PubMed

    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.

  3. 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

  4. Molecular dynamics study of the encapsulation capability of a PCL-PEO based block copolymer for hydrophobic drugs with different spatial distributions of hydrogen bond donors and acceptors.

    PubMed

    Patel, Sarthak K; Lavasanifar, Afsaneh; Choi, Phillip

    2010-03-01

    Molecular dynamics simulation was used to study the potential of using a block copolymer containing three poly(epsilon-caprolactone) (PCL) blocks of equal length connected to one end of a poly(ethylene oxide) (PEO) block, designated as PEO-b-3PCL, to encapsulate two classes of hydrophobic drugs with distinctively different molecular structures. In particular, the first class of drugs consisted of two cucurbitacin drugs (CuB and CuI) that contain multiple hydrogen bond donors and acceptors evenly distributed on their molecules while the other class of drugs (fenofibrate and nimodipine) contain essentially only clustered hydrogen bond acceptors. In the case of cucurbitacin drugs, the results showed that PEO-b-3PCL lowered the Flory-Huggins interaction parameters (chi) considerably (i.e., increased the drug solubility) compared to the linear di-block copolymer PEO-b-PCL with the same PCL/PEO (w/w) ratio of 1.0. However, the opposite effect was observed for fenofibrate and nimodipine. Analysis of the intermolecular interactions indicates that the number of hydrogen bonds formed between the three PCL blocks and cucurbitacin drugs is significantly higher than that of the linear di-block copolymer. On the other hand, owing to the absence of hydrogen bond donors and the clustering of the hydrogen bond acceptors on the fenofibrate and nimodipine molecules, this significantly reduces the number of hydrogen bonds formed in the multi-PCL block environment, leading to unfavourable chi values. The findings of the present work suggest that multi-hydrophobic block architecture could potentially increase the drug loading for hydrophobic drugs with structures containing evenly distributed multiple hydrogen bond donors and acceptors. (c) 2009 Elsevier Ltd. All rights reserved.

  5. Memory access in shared virtual memory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berrendorf, R.

    1992-01-01

    Shared virtual memory (SVM) is a virtual memory layer with a single address space on top of a distributed real memory on parallel computers. We examine the behavior and performance of SVM running a parallel program with medium-grained, loop-level parallelism on top of it. A simulator for the underlying parallel architecture can be used to examine the behavior of SVM more deeply. The influence of several parameters, such as the number of processors, page size, cold or warm start, and restricted page replication, is studied.

  6. Memory access in shared virtual memory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berrendorf, R.

    1992-09-01

    Shared virtual memory (SVM) is a virtual memory layer with a single address space on top of a distributed real memory on parallel computers. We examine the behavior and performance of SVM running a parallel program with medium-grained, loop-level parallelism on top of it. A simulator for the underlying parallel architecture can be used to examine the behavior of SVM more deeply. The influence of several parameters, such as the number of processors, page size, cold or warm start, and restricted page replication, is studied.

  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. 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.

  9. Improved block copolymer domain dispersity on chemical patterns via homopolymer-blending and molecular transfer printing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Guoliang; Nealey, Paul F.

    Herein we have investigated the domain width distributions of block copolymers and their ternary blends after directed assembly on chemically patterned surfaces with and without density multiplication. On chemical patterns with density multiplication, the width of the interpolated block copolymer domains was bimodal. Once blended with the corresponding homopolymers, the block copolymers exhibited unimodal distributions of domain width due to the redistribution of homopolymers in the block copolymer domains. When the block copolymers were blended with hydroxyl-terminated homopolymers, the homopolymers with functional end-groups healed the chemical patterns and facilitated the formation of nanostructures with further improved domain width distributions. Lastly,more » it is demonstrated that the block copolymers achieved the most improved domain width distributions when directed to assemble without density multiplication on one-to-one chemical patterns generated by molecular transfer printing.« less

  10. Cutaneous Sensory Block Area, Muscle-Relaxing Effect, and Block Duration of the Transversus Abdominis Plane Block: A Randomized, Blinded, and Placebo-Controlled Study in Healthy Volunteers.

    PubMed

    Støving, Kion; Rothe, Christian; Rosenstock, Charlotte V; Aasvang, Eske K; Lundstrøm, Lars H; Lange, Kai H W

    2015-01-01

    The transversus abdominis plane (TAP) block is a widely used nerve block. However, basic block characteristics are poorly described. The purpose of this study was to assess the cutaneous sensory block area, muscle-relaxing effect, and block duration. Sixteen healthy volunteers were randomized to receive an ultrasound-guided unilateral TAP block with 20 mL 7.5 mg/mL ropivacaine and placebo on the contralateral side. Measurements were performed at baseline and 90 minutes after performing the block. Cutaneous sensory block area was mapped and separated into a medial and lateral part by a vertical line through the anterior superior iliac spine. We measured muscle thickness of the 3 lateral abdominal muscle layers with ultrasound in the relaxed state and during maximal voluntary muscle contraction. The volunteers reported the duration of the sensory block and the abdominal muscle-relaxing effect. The lateral part of the cutaneous sensory block area was a median of 266 cm2 (interquartile range, 191-310 cm2) and the medial part 76 cm 2(interquartile range, 54-127 cm2). In all the volunteers, lateral wall muscle thickness decreased significantly by 9.2 mm (6.9-15.7 mm) during a maximal contraction. Sensory block and muscle-relaxing effect duration were 570 minutes (512-716 minutes) and 609 minutes (490-724 minutes), respectively. Cutaneous sensory block area of the TAP block is predominantly located lateral to a vertical line through the anterior superior iliac spine. The distribution is nondermatomal and does not cross the midline. The muscle-relaxing effect is significant and consistent. The block duration is approximately 10 hours with large variation.

  11. 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).

  12. Multi-level bandwidth efficient block modulation codes

    NASA Technical Reports Server (NTRS)

    Lin, Shu

    1989-01-01

    The multilevel technique is investigated for combining block coding and modulation. There are four parts. In the first part, a formulation is presented for signal sets on which modulation codes are to be constructed. Distance measures on a signal set are defined and their properties are developed. In the second part, a general formulation is presented for multilevel modulation codes in terms of component codes with appropriate Euclidean distances. The distance properties, Euclidean weight distribution and linear structure of multilevel modulation codes are investigated. In the third part, several specific methods for constructing multilevel block modulation codes with interdependency among component codes are proposed. Given a multilevel block modulation code C with no interdependency among the binary component codes, the proposed methods give a multilevel block modulation code C which has the same rate as C, a minimum squared Euclidean distance not less than that of code C, a trellis diagram with the same number of states as that of C and a smaller number of nearest neighbor codewords than that of C. In the last part, error performance of block modulation codes is analyzed for an AWGN channel based on soft-decision maximum likelihood decoding. Error probabilities of some specific codes are evaluated based on their Euclidean weight distributions and simulation results.

  13. Rapid prototyping 3D virtual world interfaces within a virtual factory environment

    NASA Technical Reports Server (NTRS)

    Kosta, Charles Paul; Krolak, Patrick D.

    1993-01-01

    On-going work into user requirements analysis using CLIPS (NASA/JSC) expert systems as an intelligent event simulator has led to research into three-dimensional (3D) interfaces. Previous work involved CLIPS and two-dimensional (2D) models. Integral to this work was the development of the University of Massachusetts Lowell parallel version of CLIPS, called PCLIPS. This allowed us to create both a Software Bus and a group problem-solving environment for expert systems development. By shifting the PCLIPS paradigm to use the VEOS messaging protocol we have merged VEOS (HlTL/Seattle) and CLIPS into a distributed virtual worlds prototyping environment (VCLIPS). VCLIPS uses the VEOS protocol layer to allow multiple experts to cooperate on a single problem. We have begun to look at the control of a virtual factory. In the virtual factory there are actors and objects as found in our Lincoln Logs Factory of the Future project. In this artificial reality architecture there are three VCLIPS entities in action. One entity is responsible for display and user events in the 3D virtual world. Another is responsible for either simulating the virtual factory or communicating with the real factory. The third is a user interface expert. The interface expert maps user input levels, within the current prototype, to control information for the factory. The interface to the virtual factory is based on a camera paradigm. The graphics subsystem generates camera views of the factory on standard X-Window displays. The camera allows for view control and object control. Control or the factory is accomplished by the user reaching into the camera views to perform object interactions. All communication between the separate CLIPS expert systems is done through VEOS.

  14. Unraveling the Agglomeration Mechanism in Charged Block Copolymer and Surfactant Complexes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Borreguero, Jose M.; Pincus, Philip A.; Sumpter, Bobby G.

    Here, we report a molecular dynamics simulation investigation of self-assembly and complex formation of charged-neutral double hydrophilic and hydrophobic-hydrophilic block copolymers (BCP) with oppositely charged surfactants. Furthermore, the structure of the surfactant micelles and the BCP aggregation on the micelle surface is systematically studied for five different BCP volume fractions that also mimics a reduction of the surfactant concentration. The local electrostatic interactions between the oppositely charged species encourage the formation of core-shell structures between the surfactant micelles where the surfactants form the cores and the charged blocks of the BCP form the corona. The emergent morphologies of these aggregatesmore » are contingent upon the nature of the BCP neutral blocks. The hydrophilic neutral blocks agglomerate with the micelles as hairy colloidal structures while the hydrophobic neutrals agglomerate in lamellar structures with the surfactant micelles. The distribution of counterion charges along the simulation box show a close-to-normal density distribution for the hydrophilic neutral blocks and a binodal distribution for hydrophobic neutral blocks. No specific surfactant concentration dependent scaling relation is observed as opposed to the simpler case of homo-polyelectrolytes.« less

  15. Unraveling the Agglomeration Mechanism in Charged Block Copolymer and Surfactant Complexes

    DOE PAGES

    Borreguero, Jose M.; Pincus, Philip A.; Sumpter, Bobby G.; ...

    2017-01-27

    Here, we report a molecular dynamics simulation investigation of self-assembly and complex formation of charged-neutral double hydrophilic and hydrophobic-hydrophilic block copolymers (BCP) with oppositely charged surfactants. Furthermore, the structure of the surfactant micelles and the BCP aggregation on the micelle surface is systematically studied for five different BCP volume fractions that also mimics a reduction of the surfactant concentration. The local electrostatic interactions between the oppositely charged species encourage the formation of core-shell structures between the surfactant micelles where the surfactants form the cores and the charged blocks of the BCP form the corona. The emergent morphologies of these aggregatesmore » are contingent upon the nature of the BCP neutral blocks. The hydrophilic neutral blocks agglomerate with the micelles as hairy colloidal structures while the hydrophobic neutrals agglomerate in lamellar structures with the surfactant micelles. The distribution of counterion charges along the simulation box show a close-to-normal density distribution for the hydrophilic neutral blocks and a binodal distribution for hydrophobic neutral blocks. No specific surfactant concentration dependent scaling relation is observed as opposed to the simpler case of homo-polyelectrolytes.« less

  16. Architectural Principles and Experimentation of Distributed High Performance Virtual Clusters

    ERIC Educational Resources Information Center

    Younge, Andrew J.

    2016-01-01

    With the advent of virtualization and Infrastructure-as-a-Service (IaaS), the broader scientific computing community is considering the use of clouds for their scientific computing needs. This is due to the relative scalability, ease of use, advanced user environment customization abilities, and the many novel computing paradigms available for…

  17. Teaching Mathematics to Young Children through the Use of Concrete and Virtual Manipulatives

    ERIC Educational Resources Information Center

    D'Angelo, Frank; Iliev, Nevin

    2012-01-01

    The use of manipulatives is an essential key to teaching mathematics to young children. Throughout history, different types of manipulatives have been used to aid in comprehension of mathematical concepts including quipu, abaci and pattern blocks. Today, concrete and virtual manipulatives are the tools that early childhood teachers are using in…

  18. Block-Parallel Data Analysis with DIY2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Morozov, Dmitriy; Peterka, Tom

    DIY2 is a programming model and runtime for block-parallel analytics on distributed-memory machines. Its main abstraction is block-structured data parallelism: data are decomposed into blocks; blocks are assigned to processing elements (processes or threads); computation is described as iterations over these blocks, and communication between blocks is defined by reusable patterns. By expressing computation in this general form, the DIY2 runtime is free to optimize the movement of blocks between slow and fast memories (disk and flash vs. DRAM) and to concurrently execute blocks residing in memory with multiple threads. This enables the same program to execute in-core, out-of-core, serial,more » parallel, single-threaded, multithreaded, or combinations thereof. This paper describes the implementation of the main features of the DIY2 programming model and optimizations to improve performance. DIY2 is evaluated on benchmark test cases to establish baseline performance for several common patterns and on larger complete analysis codes running on large-scale HPC machines.« less

  19. Flying Cassini with Virtual Operations Teams

    NASA Technical Reports Server (NTRS)

    Dodd, Suzanne; Gustavson, Robert

    1998-01-01

    The Cassini Program's challenge is to fly a large, complex mission with a reduced operations budget. A consequence of the reduced budget is elimination of the large, centrally located group traditionally used for uplink operations. Instead, responsibility for completing parts of the uplink function is distributed throughout the Program. A critical strategy employed to handle this challenge is the use of Virtual Uplink Operations Teams. A Virtual Team is comprised of a group of people with the necessary mix of engineering and science expertise who come together for the purpose of building a specific uplink product. These people are drawn from throughout the Cassini Program and participate across a large geographical area (from Germany to the West coast of the USA), covering ten time zones. The participants will often split their time between participating in the Virtual Team and accomplishing their core responsibilities, requiring significant planning and time management. When the particular uplink product task is complete, the Virtual Team disbands and the members turn back to their home organization element for future work assignments. This time-sharing of employees is used on Cassini to build mission planning products, via the Mission Planning Virtual Team, and sequencing products and monitoring of the sequence execution, via the Sequence Virtual Team. This challenging, multitasking approach allows efficient use of personnel in a resource constrained environment.

  20. Numerical Solutions of One Reduced Bethe-Salpeter Equation for the Coulombic Bound States Composed of Virtual Constituents

    NASA Astrophysics Data System (ADS)

    Chen, Jiao-Kai

    2018-04-01

    We present one reduction of the Bethe-Salpeter equation for the bound states composed of two off-mass-shell constituents. Both the relativistic effects and the virtuality effects can be considered in the obtained spinless virtuality distribution equation. The eigenvalues of the spinless virtuality distribution equation are perturbatively calculated and the bound states e+e-, μ+μ-, τ+τ-, μ+e-, and τ+e- are discussed.

  1. Pion distribution amplitude and quasidistributions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Radyushkin, Anatoly V.

    2017-03-27

    We extend our analysis of quasidistributions onto the pion distribution amplitude. Using the formalism of parton virtuality distribution amplitudes, we establish a connection between the pion transverse momentum dependent distribution amplitude Ψ(x,k 2 ⊥) and the pion quasidistribution amplitude (QDA) Q π(y,p 3). We build models for the QDAs from the virtuality-distribution-amplitude-based models for soft transverse momentum dependent distribution amplitudes, and analyze the p3 dependence of the resulting QDAs. As there are many models claimed to describe the primordial shape of the pion distribution amplitude, we present the p 3-evolution patterns for models producing some popular proposals: Chernyak-Zhitnitsky, flat, andmore » asymptotic distribution amplitude. Finally, our results may be used as a guide for future studies of the pion distribution amplitude on the lattice using the quasidistribution approach.« less

  2. A virtual water network of the Roman world

    NASA Astrophysics Data System (ADS)

    Dermody, B. J.; van Beek, R. P. H.; Meeks, E.; Klein Goldewijk, K.; Scheidel, W.; van der Velde, Y.; Bierkens, M. F. P.; Wassen, M. J.; Dekker, S. C.

    2014-12-01

    The Romans were perhaps the most impressive exponents of water resource management in preindustrial times with irrigation and virtual water trade facilitating unprecedented urbanization and socioeconomic stability for hundreds of years in a region of highly variable climate. To understand Roman water resource management in response to urbanization and climate variability, a Virtual Water Network of the Roman World was developed. Using this network we find that irrigation and virtual water trade increased Roman resilience to interannual climate variability. However, urbanization arising from virtual water trade likely pushed the Empire closer to the boundary of its water resources, led to an increase in import costs, and eroded its resilience to climate variability in the long term. In addition to improving our understanding of Roman water resource management, our cost-distance-based analysis illuminates how increases in import costs arising from climatic and population pressures are likely to be distributed in the future global virtual water network.

  3. A virtual water network of the Roman world

    NASA Astrophysics Data System (ADS)

    Dermody, B. J.; van Beek, R. P. H.; Meeks, E.; Klein Goldewijk, K.; Scheidel, W.; van der Velde, Y.; Bierkens, M. F. P.; Wassen, M. J.; Dekker, S. C.

    2014-06-01

    The Romans were perhaps the most impressive exponents of water resource management in preindustrial times with irrigation and virtual water trade facilitating unprecedented urbanisation and socioeconomic stability for hundreds of years in a region of highly variable climate. To understand Roman water resource management in response to urbanisation and climate variability, a Virtual Water Network of the Roman World was developed. Using this network we find that irrigation and virtual water trade increased Roman resilience to climate variability in the short term. However, urbanisation arising from virtual water trade likely pushed the Empire closer to the boundary of its water resources, led to an increase in import costs, and reduced its resilience to climate variability in the long-term. In addition to improving our understanding of Roman water resource management, our cost-distance based analysis illuminates how increases in import costs arising from climatic and population pressures are likely to be distributed in the future global virtual water network.

  4. Factors to keep in mind when introducing virtual microscopy.

    PubMed

    Glatz-Krieger, Katharina; Spornitz, Udo; Spatz, Alain; Mihatsch, Michael J; Glatz, Dieter

    2006-03-01

    Digitization of glass slides and delivery of so-called virtual slides (VS) emulating a real microscope over the Internet have become reality due to recent improvements in technology. We have implemented a virtual microscope for instruction of medical students and for continuing medical education. Up to 30,000 images per slide are captured using a microscope with an automated stage. The images are post-processed and then served by a plain hypertext transfer protocol (http)-server. A virtual slide client (vMic) based on Macromedia's Flash MX, a highly accepted technology available on every modern Web browser, has been developed. All necessary virtual slide parameters are stored in an XML file together with the image. Evaluation of the courses by questionnaire indicated that most students and many but not all pathologists regard virtual slides as an adequate replacement for traditional slides. All our virtual slides are publicly accessible over the World Wide Web (WWW) at http://vmic.unibas.ch . Recently, several commercially available virtual slide acquisition systems (VSAS) have been developed that use various technologies to acquire and distribute virtual slides. These systems differ in speed, image quality, compatibility, viewer functionalities and price. This paper gives an overview of the factors to keep in mind when introducing virtual microscopy.

  5. A prospective, randomized evaluation of the effects of epidural needle rotation on the distribution of epidural block.

    PubMed

    Borghi, Battista; Agnoletti, Vanni; Ricci, Alessandro; van Oven, Hanna; Montone, Nicoletta; Casati, Andrea

    2004-05-01

    We evaluated the effects of turning the tip of the Tuohy needle 45 degrees toward the operative side before threading the epidural catheter (45 degrees -rotation group, n = 24) as compared to a conventional insertion technique with the tip of the Tuohy needle oriented at 90 degrees cephalad (control group, n = 24) on the distribution of 10 mL of 0.75% ropivacaine with 10 microg sufentanil in 48 patients undergoing total hip replacement. The catheter was introduced 3 to 4 cm beyond the tip of the Tuohy needle. A blinded observer recorded sensory and motor blocks on both sides, quality of analgesia, and volumes of local anesthetic used during the first 48 h of patient-controlled epidural analgesia. Readiness to surgery required 21 +/- 6 min in the control group and 17 +/- 7 min in the 45 degree-rotation group (P > 0.50). The maximum sensory level reached on the operative side was T10 (T10-7) in the control group and T9 (T10-6) in the 45 degree-rotation group (P > 0.50); whereas the maximum sensory level reached on the nonoperative side was T10 (T12-9) in the control group and L3 (L5-T12) in the 45 degree-rotation group (P = 0.0005). Complete motor blockade of the operative limb was achieved earlier in the 45 degree-rotation than in the control group, and motor block of the nonoperative side was more intense in patients in the control group. Two-segment regression of sensory level on the surgical side was similar in the two groups, but occurred earlier on the nonoperative side in the 45 degree-rotation group (94 +/- 70 min) than in the control group (178 +/- 40 min) (P = 0.0005). Postoperative analgesia was similar in the 2 groups, but the 45 degree-rotation group consumed less local anesthetic (242 +/- 35 mL) than the control group (297 +/- 60 mL) (P = 0.0005). We conclude that the rotation of the Tuohy introducer needle 45 degrees toward the operative side before threading the epidural catheter provides a preferential distribution of sensory and motor block toward

  6. A spring-block analogy for the dynamics of stock indexes

    NASA Astrophysics Data System (ADS)

    Sándor, Bulcsú; Néda, Zoltán

    2015-06-01

    A spring-block chain placed on a running conveyor belt is considered for modeling stylized facts observed in the dynamics of stock indexes. Individual stocks are modeled by the blocks, while the stock-stock correlations are introduced via simple elastic forces acting in the springs. The dragging effect of the moving belt corresponds to the expected economic growth. The spring-block system produces collective behavior and avalanche like phenomena, similar to the ones observed in stock markets. An artificial index is defined for the spring-block chain, and its dynamics is compared with the one measured for the Dow Jones Industrial Average. For certain parameter regions the model reproduces qualitatively well the dynamics of the logarithmic index, the logarithmic returns, the distribution of the logarithmic returns, the avalanche-size distribution and the distribution of the investment horizons. A noticeable success of the model is that it is able to account for the gain-loss asymmetry observed in the inverse statistics. Our approach has mainly a pedagogical value, bridging between a complex socio-economic phenomena and a basic (mechanical) model in physics.

  7. Addressing data privacy in matched studies via virtual pooling.

    PubMed

    Saha-Chaudhuri, P; Weinberg, C R

    2017-09-07

    Data confidentiality and shared use of research data are two desirable but sometimes conflicting goals in research with multi-center studies and distributed data. While ideal for straightforward analysis, confidentiality restrictions forbid creation of a single dataset that includes covariate information of all participants. Current approaches such as aggregate data sharing, distributed regression, meta-analysis and score-based methods can have important limitations. We propose a novel application of an existing epidemiologic tool, specimen pooling, to enable confidentiality-preserving analysis of data arising from a matched case-control, multi-center design. Instead of pooling specimens prior to assay, we apply the methodology to virtually pool (aggregate) covariates within nodes. Such virtual pooling retains most of the information used in an analysis with individual data and since individual participant data is not shared externally, within-node virtual pooling preserves data confidentiality. We show that aggregated covariate levels can be used in a conditional logistic regression model to estimate individual-level odds ratios of interest. The parameter estimates from the standard conditional logistic regression are compared to the estimates based on a conditional logistic regression model with aggregated data. The parameter estimates are shown to be similar to those without pooling and to have comparable standard errors and confidence interval coverage. Virtual data pooling can be used to maintain confidentiality of data from multi-center study and can be particularly useful in research with large-scale distributed data.

  8. The Evolution of Constructivist Learning Environments: Immersion in Distributed, Virtual Worlds.

    ERIC Educational Resources Information Center

    Dede, Chris

    1995-01-01

    Discusses the evolution of constructivist learning environments and examines the collaboration of simulated software models, virtual environments, and evolving mental models via immersion in artificial realities. A sidebar gives a realistic example of a student navigating through cyberspace. (JMV)

  9. VIRTUAL REALITY HYPNOSIS

    PubMed Central

    Askay, Shelley Wiechman; Patterson, David R.; Sharar, Sam R.

    2010-01-01

    Scientific evidence for the viability of hypnosis as a treatment for pain has flourished over the past two decades (Rainville, Duncan, Price, Carrier and Bushnell, 1997; Montgomery, DuHamel and Redd, 2000; Lang and Rosen, 2002; Patterson and Jensen, 2003). However its widespread use has been limited by factors such as the advanced expertise, time and effort required by clinicians to provide hypnosis, and the cognitive effort required by patients to engage in hypnosis. The theory in developing virtual reality hypnosis was to apply three-dimensional, immersive, virtual reality technology to guide the patient through the same steps used when hypnosis is induced through an interpersonal process. Virtual reality replaces many of the stimuli that the patients have to struggle to imagine via verbal cueing from the therapist. The purpose of this paper is to explore how virtual reality may be useful in delivering hypnosis, and to summarize the scientific literature to date. We will also explore various theoretical and methodological issues that can guide future research. In spite of the encouraging scientific and clinical findings, hypnosis for analgesia is not universally used in medical centres. One reason for the slow acceptance is the extensive provider training required in order for hypnosis to be an effective pain management modality. Training in hypnosis is not commonly offered in medical schools or even psychology graduate curricula. Another reason is that hypnosis requires far more time and effort to administer than an analgesic pill or injection. Hypnosis requires training, skill and patience to deliver in medical centres that are often fast-paced and highly demanding of clinician time. Finally, the attention and cognitive effort required for hypnosis may be more than patients in an acute care setting, who may be under the influence of opiates and benzodiazepines, are able to impart. It is a challenge to make hypnosis a standard part of care in this environment

  10. VIRTUAL REALITY HYPNOSIS.

    PubMed

    Askay, Shelley Wiechman; Patterson, David R; Sharar, Sam R

    2009-03-01

    Scientific evidence for the viability of hypnosis as a treatment for pain has flourished over the past two decades (Rainville, Duncan, Price, Carrier and Bushnell, 1997; Montgomery, DuHamel and Redd, 2000; Lang and Rosen, 2002; Patterson and Jensen, 2003). However its widespread use has been limited by factors such as the advanced expertise, time and effort required by clinicians to provide hypnosis, and the cognitive effort required by patients to engage in hypnosis.The theory in developing virtual reality hypnosis was to apply three-dimensional, immersive, virtual reality technology to guide the patient through the same steps used when hypnosis is induced through an interpersonal process. Virtual reality replaces many of the stimuli that the patients have to struggle to imagine via verbal cueing from the therapist. The purpose of this paper is to explore how virtual reality may be useful in delivering hypnosis, and to summarize the scientific literature to date. We will also explore various theoretical and methodological issues that can guide future research.In spite of the encouraging scientific and clinical findings, hypnosis for analgesia is not universally used in medical centres. One reason for the slow acceptance is the extensive provider training required in order for hypnosis to be an effective pain management modality. Training in hypnosis is not commonly offered in medical schools or even psychology graduate curricula. Another reason is that hypnosis requires far more time and effort to administer than an analgesic pill or injection. Hypnosis requires training, skill and patience to deliver in medical centres that are often fast-paced and highly demanding of clinician time. Finally, the attention and cognitive effort required for hypnosis may be more than patients in an acute care setting, who may be under the influence of opiates and benzodiazepines, are able to impart. It is a challenge to make hypnosis a standard part of care in this environment

  11. The virtual water content of major grain crops and virtual water flows between regions in China.

    PubMed

    Sun, Shi-Kun; Wu, Pu-Te; Wang, Yu-Bao; Zhao, Xi-Ning

    2013-04-01

    The disproportionate distribution of arable land and water resources has become a bottleneck for guaranteeing food security in China. Virtual water and virtual water trade theory have provided a potential solution to improve water resources management in agriculture and alleviate water crises in water-scarce regions. The present study evaluates the green and blue virtual water content of wheat, maize and rice at the regional scale in China. It then assesses the water-saving benefits of virtual water flows related to the transfer of the three crops between regions. The national average virtual water content of wheat, maize and rice were 1071 m(3) per ton (50.98% green water, 49.02% blue water ), 830 m(3) per ton (76.27% green water, 23.73% blue water) and 1294 m(3) per ton (61.90% green water, 38.10% blue water), respectively. With the regional transfer of wheat, maize and rice, virtual water flows reached 30.08 Gm(3) (59.91% green water, 40.09% blue water). Meanwhile, China saved 11.47 Gm(3) green water, while it consumed 7.84 Gm(3) more blue water than with a no-grain transfer scenario in 2009. In order to guarantee food security in China, the government should improve water productivity (reduce virtual water content of crops) during the grain production process. Meanwhile, under the preconditions of economic feasibility and land-water resources availability, China should guarantee the grain-sown area in southern regions for taking full advantage of green water resources and to alleviate the pressure on water resources. © 2012 Society of Chemical Industry.

  12. ViRPET--combination of virtual reality and PET brain imaging

    DOEpatents

    Majewski, Stanislaw; Brefczynski-Lewis, Julie

    2017-05-23

    Various methods, systems and apparatus are provided for brain imaging during virtual reality stimulation. In one example, among others, a system for virtual ambulatory environment brain imaging includes a mobile brain imager configured to obtain positron emission tomography (PET) scans of a subject in motion, and a virtual reality (VR) system configured to provide one or more stimuli to the subject during the PET scans. In another example, a method for virtual ambulatory environment brain imaging includes providing stimulation to a subject through a virtual reality (VR) system; and obtaining a positron emission tomography (PET) scan of the subject while moving in response to the stimulation from the VR system. The mobile brain imager can be positioned on the subject with an array of imaging photodetector modules distributed about the head of the subject.

  13. Increase in specific density of levobupivacaine and fentanyl solution ensures lower incidence of inadequate block.

    PubMed

    Djeno, Ivana Tudorić; Duzel, Viktor; Ajduk, Marko; Oremus, Zrinka Safarić; Zupcić, Miroslav; Dusper, Silva; Jukić, Dubravko; Husedzinović, Ino

    2012-06-01

    The clinical presentation of a subarachnoid block (SAB) is dependent upon the intrathecal spread of local anesthetic (LA). Intrathecal distribution depends on the chemical and physical characteristics of LA, puncture site, technique used, patient anatomical characteristics and hydrodynamic properties of cerebrospinal fluid. We tried to determine whether a combined glucose/LA solution can render a clinically significant difference in sensory block distribution and motor block intensity.This was a controlled, randomized and double blinded study. The surgical procedures were stripping of the great or small saphenous vein and extirpation of remaining varicose veins. The study included 110 patients distributed into two groups: Hyperbaric (7.5 mg levobupivacaine (1.5 ml 0.5% Chirocaine) + 50 microg Fentanyl (0.5 ml Fentanil) and 1 ml 10% glucose (Pliva)) vs. Hypobaric (7.5 mg levobupivacaine (1.5 ml 0.5% Chirocaine) + 50 microg Fentanyl (0.5 ml Fentanil) and 1 ml 0.9% NaCl (Pliva, Zagreb)) adding to a total volume of 3.5 ml per solution. Spinal puncture was at L3-L4 level. Spinal block distribution was assessed in five minute intervals and intensity of motor block was assessed according to the modified Bromage scale. Pain was assessed with the Visual Analogue Scale. A statistically significant difference in sensory block distribution, motor block intensity and recovery time was established between hyperbaric and hypobaric solutions. By increasing the specific density of anesthetic solution, a higher sensory block, with lesser variability, a diminished influence of Body Mass Index, decreased motor block intensity and faster recovery time may be achieved.

  14. LHCb experience with running jobs in virtual machines

    NASA Astrophysics Data System (ADS)

    McNab, A.; Stagni, F.; Luzzi, C.

    2015-12-01

    The LHCb experiment has been running production jobs in virtual machines since 2013 as part of its DIRAC-based infrastructure. We describe the architecture of these virtual machines and the steps taken to replicate the WLCG worker node environment expected by user and production jobs. This relies on the uCernVM system for providing root images for virtual machines. We use the CernVM-FS distributed filesystem to supply the root partition files, the LHCb software stack, and the bootstrapping scripts necessary to configure the virtual machines for us. Using this approach, we have been able to minimise the amount of contextualisation which must be provided by the virtual machine managers. We explain the process by which the virtual machine is able to receive payload jobs submitted to DIRAC by users and production managers, and how this differs from payloads executed within conventional DIRAC pilot jobs on batch queue based sites. We describe our operational experiences in running production on VM based sites managed using Vcycle/OpenStack, Vac, and HTCondor Vacuum. Finally we show how our use of these resources is monitored using Ganglia and DIRAC.

  15. 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…

  16. Virtual reality applied to teletesting

    NASA Astrophysics Data System (ADS)

    van den Berg, Thomas J.; Smeenk, Roland J. M.; Mazy, Alain; Jacques, Patrick; Arguello, Luis; Mills, Simon

    2003-05-01

    The activity "Virtual Reality applied to Teletesting" is related to a wider European Space Agency (ESA) initiative of cost reduction, in particular the reduction of test costs. Reduction of costs of space related projects have to be performed on test centre operating costs and customer company costs. This can accomplished by increasing the automation and remote testing ("teletesting") capabilities of the test centre. Main problems related to teletesting are a lack of situational awareness and the separation of control over the test environment. The objective of the activity is to evaluate the use of distributed computing and Virtual Reality technology to support the teletesting of a payload under vacuum conditions, and to provide a unified man-machine interface for the monitoring and control of payload, vacuum chamber and robotics equipment. The activity includes the development and testing of a "Virtual Reality Teletesting System" (VRTS). The VRTS is deployed at one of the ESA certified test centres to perform an evaluation and test campaign using a real payload. The VRTS is entirely written in the Java programming language, using the J2EE application model. The Graphical User Interface runs as an applet in a Web browser, enabling easy access from virtually any place.

  17. Virtual Collaboration Readiness Measurement a Case Study in the Automobile Industry

    NASA Astrophysics Data System (ADS)

    Ziarati, Koorush; Khayami, Raouf; Parvinnia, Elham; Afroozi Milani, Ghazal

    In end of the last century information and communication technology caused a veritable evolution in the world of business and commerce. Globalization has changed all the commerce equations and business plans. Old companies have to change their strategies if they want to survive after this technological revolution. A new form of collaboration between the distributed and networked organizations has emerged as the "Virtual Organization" paradigm. A company can not join a virtual organization before obtaining a virtual maturity. This maturity shows the readiness of the company to begin a virtual collaboration. In this paper, based on the coherent and formal definition of virtual organizations, the criteria for measuring the readiness of companies are proposed. Our criteria are confirmed, modified or combined by using the factor analysis method on a sufficient number of virtual companies in the automobile manufacturing industry.

  18. Developing a Hybrid Virtualization Platform Design for Cyber Warfare Training and Education

    DTIC Science & Technology

    2010-06-01

    CYBER WARFARE TRAINING AND EDUCATION THESIS Kyle E. Stewart 2nd...Government. AFIT/GCE/ENG/10-06 DEVELOPING A HYBRID VIRTUALIZATION PLATFORM DESIGN FOR CYBER WARFARE TRAINING...APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. AFIT/GCE/ENG/10-06 DEVELOPING A HYBRID VIRTUALIZATION PLATFORM DESIGN FOR CYBER WARFARE

  19. The building blocks of the full body ownership illusion

    PubMed Central

    Maselli, Antonella; Slater, Mel

    2013-01-01

    Previous work has reported that it is not difficult to give people the illusion of ownership over an artificial body, providing a powerful tool for the investigation of the neural and cognitive mechanisms underlying body perception and self consciousness. We present an experimental study that uses immersive virtual reality (IVR) focused on identifying the perceptual building blocks of this illusion. We systematically manipulated visuotactile and visual sensorimotor contingencies, visual perspective, and the appearance of the virtual body in order to assess their relative role and mutual interaction. Consistent results from subjective reports and physiological measures showed that a first person perspective over a fake humanoid body is essential for eliciting a body ownership illusion. We found that the illusion of ownership can be generated when the virtual body has a realistic skin tone and spatially substitutes the real body seen from a first person perspective. In this case there is no need for an additional contribution of congruent visuotactile or sensorimotor cues. Additionally, we found that the processing of incongruent perceptual cues can be modulated by the level of the illusion: when the illusion is strong, incongruent cues are not experienced as incorrect. Participants exposed to asynchronous visuotactile stimulation can experience the ownership illusion and perceive touch as originating from an object seen to contact the virtual body. Analogously, when the level of realism of the virtual body is not high enough and/or when there is no spatial overlap between the two bodies, then the contribution of congruent multisensory and/or sensorimotor cues is required for evoking the illusion. On the basis of these results and inspired by findings from neurophysiological recordings in the monkey, we propose a model that accounts for many of the results reported in the literature. PMID:23519597

  20. Distribution of radiodense contrast medium after perineural injection of the palmar and palmar metacarpal nerves (low 4-point nerve block): an in vivo and ex vivo study in horses.

    PubMed

    Nagy, A; Bodò, G; Dyson, S J; Compostella, F; Barr, A R S

    2010-09-01

    Evidence-based information is limited on distribution of local anaesthetic solution following perineural analgesia of the palmar (Pa) and palmar metacarpal (PaM) nerves in the distal aspect of the metacarpal (Mc) region ('low 4-point nerve block'). To demonstrate the potential distribution of local anaesthetic solution after a low 4-point nerve block using a radiographic contrast model. A radiodense contrast medium was injected subcutaneously over the medial or the lateral Pa nerve at the junction of the proximal three-quarters and distal quarter of the Mc region (Pa injection) and over the ipsilateral PaM nerve immediately distal to the distal aspect of the second or fourth Mc bones (PaM injection) in both forelimbs of 10 mature horses free from lameness. Radiographs were obtained 0, 10 and 20 min after injection and analysed subjectively and objectively. Methylene blue and a radiodense contrast medium were injected in 20 cadaver limbs using the same techniques. Radiographs were obtained and the limbs dissected. After 31/40 (77.5%) Pa injections, the pattern of the contrast medium suggested distribution in the neurovascular bundle. There was significant proximal diffusion with time, but the main contrast medium patch never progressed proximal to the mid-Mc region. The radiological appearance of 2 limbs suggested that contrast medium was present in the digital flexor tendon sheath (DFTS). After PaM injections, the contrast medium was distributed diffusely around the injection site in the majority of the limbs. In cadaver limbs, after Pa injections, the contrast medium and the dye were distributed in the neurovascular bundle in 8/20 (40%) limbs and in the DFTS in 6/20 (30%) of limbs. After PaM injections, the contrast and dye were distributed diffusely around the injection site in 9/20 (45%) limbs and showed diffuse and tubular distribution in 11/20 (55%) limbs. Proximal diffusion of local anaesthetic solution after a low 4-point nerve block is unlikely to be

  1. Virtual Reality Simulation of the International Space Welding Experiment

    NASA Technical Reports Server (NTRS)

    Phillips, James A.

    1996-01-01

    Virtual Reality (VR) is a set of breakthrough technologies that allow a human being to enter and fully experience a 3-dimensional, computer simulated environment. A true virtual reality experience meets three criteria: (1) It involves 3-dimensional computer graphics; (2) It includes real-time feedback and response to user actions; and (3) It must provide a sense of immersion. Good examples of a virtual reality simulator are the flight simulators used by all branches of the military to train pilots for combat in high performance jet fighters. The fidelity of such simulators is extremely high -- but so is the price tag, typically millions of dollars. Virtual reality teaching and training methods are manifestly effective, and we have therefore implemented a VR trainer for the International Space Welding Experiment. My role in the development of the ISWE trainer consisted of the following: (1) created texture-mapped models of the ISWE's rotating sample drum, technology block, tool stowage assembly, sliding foot restraint, and control panel; (2) developed C code for control panel button selection and rotation of the sample drum; (3) In collaboration with Tim Clark (Antares Virtual Reality Systems), developed a serial interface box for the PC and the SGI Indigo so that external control devices, similar to ones actually used on the ISWE, could be used to control virtual objects in the ISWE simulation; (4) In collaboration with Peter Wang (SFFP) and Mark Blasingame (Boeing), established the interference characteristics of the VIM 1000 head-mounted-display and tested software filters to correct the problem; (5) In collaboration with Peter Wang and Mark Blasingame, established software and procedures for interfacing the VPL DataGlove and the Polhemus 6DOF position sensors to the SGI Indigo serial ports. The majority of the ISWE modeling effort was conducted on a PC-based VR Workstation, described below.

  2. Characterization of a small Terfenol-D transducer in mechanically blocked configuration

    NASA Astrophysics Data System (ADS)

    Faidley, LeAnn E.; Dapino, Marcelo J.; Flatau, Alison B.

    2001-08-01

    In numerous applications, smart material transducers are employed to actuate upon virtually immovable structures, that is, structures whose stiffness approaches infinity in comparison with that of the transducer itself. Such mechanically blocked transducer configurations can be found in applications ranging from seismic testing and isolation of civil structures, to clamping mechanisms in linear or rotational inchworm motors. In addition to providing high blocking forces, smart materials for this type of applications must often be small in size and lightweight in order for design constraints to be met. This paper provides a characterization of the force produced by a 0.9 cm (0.35 in) diameter, 2.0 cm (0.79i in) long Terfenol-D operated under mechanically blocked conditions. Experimental results are shown for several mechanical preloads as well as various magnetic field intensities, waveforms, and frequencies. Optimal levels are deduced and discussed and the results are compared to published data for a PZT transducer of similar size operated in mechanically blocked configuration. The comparison reveals that the Terfenol-D rod provides higher blocking forces than its PZT counterpart. It is thus feasible to employ small magnetostrictive drivers in applications involving zero or near-zero displacement, particularly those based on hybrid magnetostrictive/piezoelectric designs in which high efficiencies are achieved by driving the two electrically complementary transducer materials at electrical resonance.

  3. The effects of game-based virtual reality movement therapy plus mental practice on upper extremity function in chronic stroke patients with hemiparesis: a randomized controlled trial

    PubMed Central

    Park, Jin-Hyuck; Park, Ji-Hyuk

    2016-01-01

    [Purpose] The purpose of this study was to investigate the effects of game-based virtual reality movement therapy plus mental practice on upper extremity function in chronic stroke patients with hemiparesis. [Subjects] The subjects were chronic stroke patients with hemiparesis. [Methods] Thirty subjects were randomly assigned to either the control group or experimental group. All subjects received 20 sessions (5 days in a week) of virtual reality movement therapy using the Nintendo Wii. In addition to Wii-based virtual reality movement therapy, experimental group subjects performed mental practice consisting of 5 minutes of relaxation, Wii games imagination, and normalization phases before the beginning of Wii games. To compare the two groups, the upper extremity subtest of the Fugl-Meyer Assessment, Box and Block Test, and quality of movement subscale of the Motor Activity Log were performed. [Results] Both groups showed statistically significant improvement in the Fugl-Meyer Assessment, Box and Block Test, and quality of the movement subscale of Motor Activity Log after the interventions. Also, there were significant differences in the Fugl-Meyer Assessment, Box and Block Test, and quality of movement subscale of the Motor Activity Log between the two groups. [Conclusion] Game-based virtual reality movement therapy alone may be helpful to improve functional recovery of the upper extremity, but the addition of MP produces a lager improvement. PMID:27134363

  4. The effects of game-based virtual reality movement therapy plus mental practice on upper extremity function in chronic stroke patients with hemiparesis: a randomized controlled trial.

    PubMed

    Park, Jin-Hyuck; Park, Ji-Hyuk

    2016-03-01

    [Purpose] The purpose of this study was to investigate the effects of game-based virtual reality movement therapy plus mental practice on upper extremity function in chronic stroke patients with hemiparesis. [Subjects] The subjects were chronic stroke patients with hemiparesis. [Methods] Thirty subjects were randomly assigned to either the control group or experimental group. All subjects received 20 sessions (5 days in a week) of virtual reality movement therapy using the Nintendo Wii. In addition to Wii-based virtual reality movement therapy, experimental group subjects performed mental practice consisting of 5 minutes of relaxation, Wii games imagination, and normalization phases before the beginning of Wii games. To compare the two groups, the upper extremity subtest of the Fugl-Meyer Assessment, Box and Block Test, and quality of movement subscale of the Motor Activity Log were performed. [Results] Both groups showed statistically significant improvement in the Fugl-Meyer Assessment, Box and Block Test, and quality of the movement subscale of Motor Activity Log after the interventions. Also, there were significant differences in the Fugl-Meyer Assessment, Box and Block Test, and quality of movement subscale of the Motor Activity Log between the two groups. [Conclusion] Game-based virtual reality movement therapy alone may be helpful to improve functional recovery of the upper extremity, but the addition of MP produces a lager improvement.

  5. A Virtual Rat for Simulating Environmental and Exertional Heat Stress

    DTIC Science & Technology

    2014-10-02

    unsuitable for accurately determin- ing the spatiotemporal temperature distribution in the animal due to heat stress and for performing mechanistic analysis ...possible in the original experiments. Finally, we performed additional simu- lations using the virtual rat to facilitate comparative analysis of the...capability of the virtual rat to account for the circadian rhythmicity in core temperatures during an in- crease in the external temperature from 22

  6. Inferred Lunar Boulder Distributions at Decimeter Scales

    NASA Technical Reports Server (NTRS)

    Baloga, S. M.; Glaze, L. S.; Spudis, P. D.

    2012-01-01

    Block size distributions of impact deposits on the Moon are diagnostic of the impact process and environmental effects, such as target lithology and weathering. Block size distributions are also important factors in trafficability, habitability, and possibly the identification of indigenous resources. Lunar block sizes have been investigated for many years for many purposes [e.g., 1-3]. An unresolved issue is the extent to which lunar block size distributions can be extrapolated to scales smaller than limits of resolution of direct measurement. This would seem to be a straightforward statistical application, but it is complicated by two issues. First, the cumulative size frequency distribution of observable boulders rolls over due to resolution limitations at the small end. Second, statistical regression provides the best fit only around the centroid of the data [4]. Confidence and prediction limits splay away from the best fit at the endpoints resulting in inferences in the boulder density at the CPR scale that can differ by many orders of magnitude [4]. These issues were originally investigated by Cintala and McBride [2] using Surveyor data. The objective of this study was to determine whether the measured block size distributions from Lunar Reconnaissance Orbiter Camera - Narrow Angle Camera (LROC-NAC) images (m-scale resolution) can be used to infer the block size distribution at length scales comparable to Mini-RF Circular Polarization Ratio (CPR) scales, nominally taken as 10 cm. This would set the stage for assessing correlations of inferred block size distributions with CPR returns [6].

  7. Improving Balance in TBI Using a Low-Cost Customized Virtual Reality Rehabilitation Tool

    DTIC Science & Technology

    2016-10-01

    AWARD NUMBER: W81XWH-14-2-0150 TITLE: Improving Balance in TBI Using a Low-Cost Customized Virtual Reality Rehabilitation Tool PRINCIPAL...AND SUBTITLE Improving Balance in TBI Using a Low-Cost Customized Virtual Reality Rehabilitation Tool 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH...Distribution Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The proposed study will implement and evaluate a novel, low-cost, Virtual Reality (VR

  8. Large Block Test Final Report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lin, W

    2001-12-01

    This report documents the Large-Block Test (LBT) conducted at Fran Ridge near Yucca Mountain, Nevada. The LBT was a thermal test conducted on an exposed block of middle non-lithophysal Topopah Spring tuff (Tptpmn) and was designed to assist in understanding the thermal-hydrological-mechanical-chemical (THMC) processes associated with heating and then cooling a partially saturated fractured rock mass. The LBT was unique in that it was a large (3 x 3 x 4.5 m) block with top and sides exposed. Because the block was exposed at the surface, boundary conditions on five of the six sides of the block were relatively wellmore » known and controlled, making this test both easier to model and easier to monitor. This report presents a detailed description of the test as well as analyses of the data and conclusions drawn from the test. The rock block that was tested during the LBT was exposed by excavation and removal of the surrounding rock. The block was characterized and instrumented, and the sides were sealed and insulated to inhibit moisture and heat loss. Temperature on the top of the block was also controlled. The block was heated for 13 months, during which time temperature, moisture distribution, and deformation were monitored. After the test was completed and the block cooled down, a series of boreholes were drilled, and one of the heater holes was over-cored to collect samples for post-test characterization of mineralogy and mechanical properties. Section 2 provides background on the test. Section 3 lists the test objectives and describes the block site, the site configuration, and measurements made during the test. Section 3 also presents a chronology of events associated with the LBT, characterization of the block, and the pre-heat analyses of the test. Section 4 describes the fracture network contained in the block. Section 5 describes the heating/cooling system used to control the temperature in the block and presents the thermal history of the block during the

  9. Welfare Impact of Virtual Trading on Wholesale Electricity Markets

    NASA Astrophysics Data System (ADS)

    Giraldo, Juan S.

    market since it became available to be used by financial traders in September 2010. Stylized models are used to determine the optimal bidding strategy for the different virtual bids under different scenarios. The welfare analysis shows that the main impact of virtual bidding is surplus reallocation and that the impact on market efficiency is small by comparison. The market structure is such that it is more likely to see surplus transfers from consumers to producers. The results also show that outcomes with greater price convergence as a result of virtual bidding activity were not necessarily more efficient, nor do they always correct surplus distribution distortions that result from bias in the DA expectation of RT load. Compared to INCs and DECs, the UTC analysis showed that UTCs do not have the same self-corrective incentives towards price convergence and are less likely to lead to nodal price convergence or correct for surplus distribution distortions caused by uncertainty and bias in the DA expectation of RT load. Additionally, the analysis showed that UTCs allow financial traders to engage in low risk high volume trading strategies that, while profitable, may have little to no impact on price convergence or market efficiency.

  10. New developments in digital pathology: from telepathology to virtual pathology laboratory.

    PubMed

    Kayser, Klaus; Kayser, Gian; Radziszowski, Dominik; Oehmann, Alexander

    2004-01-01

    To analyse the present status and future development of computerized diagnostic pathology in terms of work-flow integrative telepathology and virtual laboratory. Telepathology has left its childhood. The technical development of telepathology is mature, in contrast to that of virtual pathology. Two kinds of virtual pathology laboratories are emerging: a) those with distributed pathologists and distributed (>=1) laboratories associated to individual biopsy stations/surgical theatres, and b) distributed pathologists working in a centralized laboratory. Both are under technical development. Telepathology can be used for e-learning and e-training in pathology, as exemplarily demonstrated on Digital Lung Pathology Pathology (www.pathology-online.org). A virtual pathology institution (mode a) accepts a complete case with the patient's history, clinical findings, and (pre-selected) images for first diagnosis. The diagnostic responsibility is that of a conventional institution. The internet serves as platform for information transfer, and an open server such as the iPATH (http://telepath.patho.unibas.ch) for coordination and performance of the diagnostic procedure. The size of images has to be limited, and usual different magnifications have to be used. A group of pathologists is "on duty", or selects one member for a predefined duty period. The diagnostic statement of the pathologist(s) on duty is retransmitted to the sender with full responsibility. First experiences of a virtual pathology institution group working with the iPATH server (Dr. L. Banach, Dr. G. Haroske, Dr. I. Hurwitz, Dr. K. Kayser, Dr. K.D. Kunze, Dr. M. Oberholzer,) working with a small hospital of the Salomon islands are promising. A centralized virtual pathology institution (mode b) depends upon the digitalisation of a complete slide, and the transfer of large sized images to different pathologists working in one institution. The technical performance of complete slide digitalisation is still under

  11. Block copolymer adhesion promoters via ring-opening metathesis polymerization

    DOEpatents

    Kent, Michael S.; Saunders, Randall

    1997-01-01

    Coupling agents based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization.

  12. Dynamic Fragmentation of Jointed Rock Blocks During Rockslide-Avalanches: Insights From Discrete Element Analyses

    NASA Astrophysics Data System (ADS)

    Zhao, Tao; Crosta, Giovanni Battista; Dattola, Giuseppe; Utili, Stefano

    2018-04-01

    The dynamic fragmentation of jointed rock blocks during rockslide avalanches has been investigated by discrete element method simulations for a multiple arrangement of a rock block sliding over a simple slope geometry. The rock blocks are released along an inclined sliding plane and subsequently collide onto a flat horizontal plane at a sharp kink point. The contact force chains generated by the impact appear initially at the bottom frontal corner of the rock block and then propagate radially upward to the top rear part of the block. The jointed rock blocks exhibit evident contact force concentration and discontinuity of force wave propagation near the joint, associating with high energy dissipation of granular dynamics. The corresponding force wave propagation velocity can be less than 200 m/s, which is much smaller than that of an intact rock (1,316 m/s). The concentration of contact forces at the bottom leads to high rock fragmentation intensity and momentum boosts, facilitating the spreading of many fine fragments to the distal ends. However, the upper rock block exhibits very low rock fragmentation intensity but high energy dissipation due to intensive friction and damping, resulting in the deposition of large fragments near the slope toe. The size and shape of large fragments are closely related to the orientation and distribution of the block joints. The cumulative fragment size distribution can be well fitted by the Weibull's distribution function, with very gentle and steep curvatures at the fine and coarse size ranges, respectively. The numerical results of fragment size distribution can match well some experimental and field observations.

  13. A virtual data language and system for scientific workflow management in data grid environments

    NASA Astrophysics Data System (ADS)

    Zhao, Yong

    With advances in scientific instrumentation and simulation, scientific data is growing fast in both size and analysis complexity. So-called Data Grids aim to provide high performance, distributed data analysis infrastructure for data- intensive sciences, where scientists distributed worldwide need to extract information from large collections of data, and to share both data products and the resources needed to produce and store them. However, the description, composition, and execution of even logically simple scientific workflows are often complicated by the need to deal with "messy" issues like heterogeneous storage formats and ad-hoc file system structures. We show how these difficulties can be overcome via a typed workflow notation called virtual data language, within which issues of physical representation are cleanly separated from logical typing, and by the implementation of this notation within the context of a powerful virtual data system that supports distributed execution. The resulting language and system are capable of expressing complex workflows in a simple compact form, enacting those workflows in distributed environments, monitoring and recording the execution processes, and tracing the derivation history of data products. We describe the motivation, design, implementation, and evaluation of the virtual data language and system, and the application of the virtual data paradigm in various science disciplines, including astronomy, cognitive neuroscience.

  14. Intelligent web agents for a 3D virtual community

    NASA Astrophysics Data System (ADS)

    Dave, T. M.; Zhang, Yanqing; Owen, G. S. S.; Sunderraman, Rajshekhar

    2003-08-01

    In this paper, we propose an Avatar-based intelligent agent technique for 3D Web based Virtual Communities based on distributed artificial intelligence, intelligent agent techniques, and databases and knowledge bases in a digital library. One of the goals of this joint NSF (IIS-9980130) and ACM SIGGRAPH Education Committee (ASEC) project is to create a virtual community of educators and students who have a common interest in comptuer graphics, visualization, and interactive techniqeus. In this virtual community (ASEC World) Avatars will represent the educators, students, and other visitors to the world. Intelligent agents represented as specially dressed Avatars will be available to assist the visitors to ASEC World. The basic Web client-server architecture of the intelligent knowledge-based avatars is given. Importantly, the intelligent Web agent software system for the 3D virtual community is implemented successfully.

  15. Virtual Team Governance: Addressing the Governance Mechanisms and Virtual Team Performance

    NASA Astrophysics Data System (ADS)

    Zhan, Yihong; Bai, Yu; Liu, Ziheng

    As technology has improved and collaborative software has been developed, virtual teams with geographically dispersed members spread across diverse physical locations have become increasingly prominent. Virtual team is supported by advancing communication technologies, which makes virtual teams able to largely transcend time and space. Virtual teams have changed the corporate landscape, which are more complex and dynamic than traditional teams since the members of virtual teams are spread on diverse geographical locations and their roles in the virtual team are different. Therefore, how to realize good governance of virtual team and arrive at good virtual team performance is becoming critical and challenging. Good virtual team governance is essential for a high-performance virtual team. This paper explores the performance and the governance mechanism of virtual team. It establishes a model to explain the relationship between the performance and the governance mechanisms in virtual teams. This paper is focusing on managing virtual teams. It aims to find the strategies to help business organizations to improve the performance of their virtual teams and arrive at the objectives of good virtual team management.

  16. Tharsis block tectonics on Mars

    NASA Technical Reports Server (NTRS)

    Raitala, Jouko T.

    1988-01-01

    The concept of block tectonics provides a framework for understanding many aspects of Tharsis and adjoining structures. This Tharsis block tectonics on Mars is manifested partly by mantle-related doming and partly by response to loading by subsequent volcanic construction. Although the origin of the volcanism from beneath Tharsis is a subject of controversy explanations have to include inhomogeneities in Martian internal structure, energy distribution, magma accumulation and motion below the lithosphere. Thermal convection can be seen as a necessary consequence for transient initial phase of Martian cooling. This produced part of the elevated topography with tensional stresses and graben systems radial to the main bulge. The linear grabens, radial to the Tharsis center, can be interpreted to indicate rift zones that define the crustal block boundaries. The load-induced stresses may then have contributed on further graben and ridge formation over an extended period of time.

  17. Virtual worlds to support patient group communication? A questionnaire study investigating potential for virtual world focus group use by respiratory patients.

    PubMed

    Taylor, Michael J; Taylor, Dave; Vlaev, Ivo; Elkin, Sarah

    2017-01-01

    Recent advances in communication technologies enable potential provision of remote education for patients using computer-generated environments known as virtual worlds. Previous research has revealed highly variable levels of patient receptiveness to using information technologies for healthcare-related purposes. This preliminary study involved implementing a questionnaire investigating attitudes and access to computer technologies of respiratory outpatients, in order to assess potential for use of virtual worlds to facilitate health-related education for this sample. Ninety-four patients with a chronic respiratory condition completed surveys, which were distributed at a Chest Clinic. In accordance with our prediction, younger participants were more likely to be able to use, and have access to a computer and some patients were keen to explore use virtual worlds for healthcare-related purposes: Of those with access to computer facilities, 14.50% expressed a willingness to attend a virtual world focus group. Results indicate future virtual world health education facilities should be designed to cater for younger patients, because this group are most likely to accept and use such facilities. Within the study sample, this is likely to comprise of people diagnosed with asthma. Future work could investigate the potential of creating a virtual world asthma education facility.

  18. Virtual worlds to support patient group communication? A questionnaire study investigating potential for virtual world focus group use by respiratory patients

    PubMed Central

    Taylor, Michael J.; Taylor, Dave; Vlaev, Ivo; Elkin, Sarah

    2015-01-01

    Recent advances in communication technologies enable potential provision of remote education for patients using computer-generated environments known as virtual worlds. Previous research has revealed highly variable levels of patient receptiveness to using information technologies for healthcare-related purposes. This preliminary study involved implementing a questionnaire investigating attitudes and access to computer technologies of respiratory outpatients, in order to assess potential for use of virtual worlds to facilitate health-related education for this sample. Ninety-four patients with a chronic respiratory condition completed surveys, which were distributed at a Chest Clinic. In accordance with our prediction, younger participants were more likely to be able to use, and have access to a computer and some patients were keen to explore use virtual worlds for healthcare-related purposes: Of those with access to computer facilities, 14.50% expressed a willingness to attend a virtual world focus group. Results indicate future virtual world health education facilities should be designed to cater for younger patients, because this group are most likely to accept and use such facilities. Within the study sample, this is likely to comprise of people diagnosed with asthma. Future work could investigate the potential of creating a virtual world asthma education facility. PMID:28239187

  19. Working Group Reports and Presentations: Virtual Worlds and Virtual Exploration

    NASA Technical Reports Server (NTRS)

    LAmoreaux, Claudia

    2006-01-01

    Scientists and engineers are continually developing innovative methods to capitalize on recent developments in computational power. Virtual worlds and virtual exploration present a new toolset for project design, implementation, and resolution. Replication of the physical world in the virtual domain provides stimulating displays to augment current data analysis techniques and to encourage public participation. In addition, the virtual domain provides stakeholders with a low cost, low risk design and test environment. The following document defines a virtual world and virtual exploration, categorizes the chief motivations for virtual exploration, elaborates upon specific objectives, identifies roadblocks and enablers for realizing the benefits, and highlights the more immediate areas of implementation (i.e. the action items). While the document attempts a comprehensive evaluation of virtual worlds and virtual exploration, the innovative nature of the opportunities presented precludes completeness. The authors strongly encourage readers to derive additional means of utilizing the virtual exploration toolset.

  20. Field-theoretic simulations of block copolymer nanocomposites in a constant interfacial tension ensemble.

    PubMed

    Koski, Jason P; Riggleman, Robert A

    2017-04-28

    Block copolymers, due to their ability to self-assemble into periodic structures with long range order, are appealing candidates to control the ordering of functionalized nanoparticles where it is well-accepted that the spatial distribution of nanoparticles in a polymer matrix dictates the resulting material properties. The large parameter space associated with block copolymer nanocomposites makes theory and simulation tools appealing to guide experiments and effectively isolate parameters of interest. We demonstrate a method for performing field-theoretic simulations in a constant volume-constant interfacial tension ensemble (nVγT) that enables the determination of the equilibrium properties of block copolymer nanocomposites, including when the composites are placed under tensile or compressive loads. Our approach is compatible with the complex Langevin simulation framework, which allows us to go beyond the mean-field approximation. We validate our approach by comparing our nVγT approach with free energy calculations to determine the ideal domain spacing and modulus of a symmetric block copolymer melt. We analyze the effect of numerical and thermodynamic parameters on the efficiency of the nVγT ensemble and subsequently use our method to investigate the ideal domain spacing, modulus, and nanoparticle distribution of a lamellar forming block copolymer nanocomposite. We find that the nanoparticle distribution is directly linked to the resultant domain spacing and is dependent on polymer chain density, nanoparticle size, and nanoparticle chemistry. Furthermore, placing the system under tension or compression can qualitatively alter the nanoparticle distribution within the block copolymer.

  1. Block copolymer adhesion promoters via ring-opening metathesis polymerization

    DOEpatents

    Kent, M.S.; Saunders, R.

    1997-02-18

    Coupling agents are disclosed based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization. 18 figs.

  2. Innovative application of virtual display technique in virtual museum

    NASA Astrophysics Data System (ADS)

    Zhang, Jiankang

    2017-09-01

    Virtual museum refers to display and simulate the functions of real museum on the Internet in the form of 3 Dimensions virtual reality by applying interactive programs. Based on Virtual Reality Modeling Language, virtual museum building and its effective interaction with the offline museum lie in making full use of 3 Dimensions panorama technique, virtual reality technique and augmented reality technique, and innovatively taking advantages of dynamic environment modeling technique, real-time 3 Dimensions graphics generating technique, system integration technique and other key virtual reality techniques to make sure the overall design of virtual museum.3 Dimensions panorama technique, also known as panoramic photography or virtual reality, is a technique based on static images of the reality. Virtual reality technique is a kind of computer simulation system which can create and experience the interactive 3 Dimensions dynamic visual world. Augmented reality, also known as mixed reality, is a technique which simulates and mixes the information (visual, sound, taste, touch, etc.) that is difficult for human to experience in reality. These technologies make virtual museum come true. It will not only bring better experience and convenience to the public, but also be conducive to improve the influence and cultural functions of the real museum.

  3. Virtual network embedding in cross-domain network based on topology and resource attributes

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Zhang, Zhizhong; Feng, Linlin; Liu, Lilan

    2018-03-01

    Aiming at the network architecture ossification and the diversity of access technologies issues, this paper researches the cross-domain virtual network embedding algorithm. By analysing the topological attribute from the local and global perspective of nodes in the virtual network and the physical network, combined with the local network resource property, we rank the embedding priority of the nodes with PCA and TOPSIS methods. Besides, the link load distribution is considered. Above all, We proposed an cross-domain virtual network embedding algorithm based on topology and resource attributes. The simulation results depicts that our algorithm increases the acceptance rate of multi-domain virtual network requests, compared with the existing virtual network embedding algorithm.

  4. Personal Virtual Libraries

    ERIC Educational Resources Information Center

    Pappas, Marjorie L.

    2004-01-01

    Virtual libraries are becoming more and more common. Most states have a virtual library. A growing number of public libraries have a virtual presence on the Web. Virtual libraries are a growing addition to school library media collections. The next logical step would be personal virtual libraries. A personal virtual library (PVL) is a collection…

  5. Virtual aluminum castings: An industrial application of ICME

    NASA Astrophysics Data System (ADS)

    Allison, John; Li, Mei; Wolverton, C.; Su, Xuming

    2006-11-01

    The automotive product design and manufacturing community is continually besieged by Hercule an engineering, timing, and cost challenges. Nowhere is this more evident than in the development of designs and manufacturing processes for cast aluminum engine blocks and cylinder heads. Increasing engine performance requirements coupled with stringent weight and packaging constraints are pushing aluminum alloys to the limits of their capabilities. To provide high-quality blocks and heads at the lowest possible cost, manufacturing process engineers are required to find increasingly innovative ways to cast and heat treat components. Additionally, to remain competitive, products and manufacturing methods must be developed and implemented in record time. To bridge the gaps between program needs and engineering reality, the use of robust computational models in up-front analysis will take on an increasingly important role. This article describes just such a computational approach, the Virtual Aluminum Castings methodology, which was developed and implemented at Ford Motor Company and demonstrates the feasibility and benefits of integrated computational materials engineering.

  6. 31 CFR 510.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Blocked account; blocked property. 510.301 Section 510.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... Definitions § 510.301 Blocked account; blocked property. The terms blocked account and blocked property shall...

  7. 31 CFR 510.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Blocked account; blocked property. 510.301 Section 510.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... Definitions § 510.301 Blocked account; blocked property. The terms blocked account and blocked property shall...

  8. 31 CFR 510.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Blocked account; blocked property. 510.301 Section 510.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... Definitions § 510.301 Blocked account; blocked property. The terms blocked account and blocked property shall...

  9. Toward a Virtual Solar Observatory: Starting Before the Petabytes Fall

    NASA Technical Reports Server (NTRS)

    Gurman, J. B.; Fisher, Richard R. (Technical Monitor)

    2002-01-01

    NASA is currently engaged in the study phase of a modest effort to establish a Virtual Solar Observatory (VSO). The VSO would serve ground- and space-based solar physics data sets from a distributed network of archives through a small number of interfaces to the scientific community. The basis of this approach, as of all planned virtual observatories, is the translation of metadata from the various sources via source-specific dictionaries so the user will not have to distinguish among keyword usages. A single Web interface should give access to all the distributed data. We present the current status of the VSO, its initial scope, and its relation to the European EGSO effort.

  10. Multi-Agent Framework for Virtual Learning Spaces.

    ERIC Educational Resources Information Center

    Sheremetov, Leonid; Nunez, Gustavo

    1999-01-01

    Discussion of computer-supported collaborative learning, distributed artificial intelligence, and intelligent tutoring systems focuses on the concept of agents, and describes a virtual learning environment that has a multi-agent system. Describes a model of interactions in collaborative learning and discusses agents for Web-based virtual…

  11. Virtual Teaming: Faculty Collaboration in Online Spaces

    ERIC Educational Resources Information Center

    Almjeld, Jen; Rybas, Natalia; Rybas, Sergey

    2013-01-01

    This collaborative article chronicles the experiences of three faculty at three universities utilizing wiki technology to transform themselves and their students into a virtual team. Rooted in workplace approaches to distributed teaming, the project expands notions of classroom collaboration to include planning, administration, and assessment of a…

  12. Virtual Sensor Web Architecture

    NASA Astrophysics Data System (ADS)

    Bose, P.; Zimdars, A.; Hurlburt, N.; Doug, S.

    2006-12-01

    NASA envisions the development of smart sensor webs, intelligent and integrated observation network that harness distributed sensing assets, their associated continuous and complex data sets, and predictive observation processing mechanisms for timely, collaborative hazard mitigation and enhanced science productivity and reliability. This paper presents Virtual Sensor Web Infrastructure for Collaborative Science (VSICS) Architecture for sustained coordination of (numerical and distributed) model-based processing, closed-loop resource allocation, and observation planning. VSICS's key ideas include i) rich descriptions of sensors as services based on semantic markup languages like OWL and SensorML; ii) service-oriented workflow composition and repair for simple and ensemble models; event-driven workflow execution based on event-based and distributed workflow management mechanisms; and iii) development of autonomous model interaction management capabilities providing closed-loop control of collection resources driven by competing targeted observation needs. We present results from initial work on collaborative science processing involving distributed services (COSEC framework) that is being extended to create VSICS.

  13. New trends in the virtualization of hospitals--tools for global e-Health.

    PubMed

    Graschew, Georgi; Roelofs, Theo A; Rakowsky, Stefan; Schlag, Peter M; Heinzlreiter, Paul; Kranzlmüller, Dieter; Volkert, Jens

    2006-01-01

    The development of virtual hospitals and digital medicine helps to bridge the digital divide between different regions of the world and enables equal access to high-level medical care. Pre-operative planning, intra-operative navigation and minimally-invasive surgery require a digital and virtual environment supporting the perception of the physician. As data and computing resources in a virtual hospital are distributed over many sites the concept of the Grid should be integrated with other communication networks and platforms. A promising approach is the implementation of service-oriented architectures for an invisible grid, hiding complexity for both application developers and end-users. Examples of promising medical applications of Grid technology are the real-time 3D-visualization and manipulation of patient data for individualized treatment planning and the creation of distributed intelligent databases of medical images.

  14. NASA Virtual Glovebox: An Immersive Virtual Desktop Environment for Training Astronauts in Life Science Experiments

    NASA Technical Reports Server (NTRS)

    Twombly, I. Alexander; Smith, Jeffrey; Bruyns, Cynthia; Montgomery, Kevin; Boyle, Richard

    2003-01-01

    The International Space Station will soon provide an unparalleled research facility for studying the near- and longer-term effects of microgravity on living systems. Using the Space Station Glovebox Facility - a compact, fully contained reach-in environment - astronauts will conduct technically challenging life sciences experiments. Virtual environment technologies are being developed at NASA Ames Research Center to help realize the scientific potential of this unique resource by facilitating the experimental hardware and protocol designs and by assisting the astronauts in training. The Virtual GloveboX (VGX) integrates high-fidelity graphics, force-feedback devices and real- time computer simulation engines to achieve an immersive training environment. Here, we describe the prototype VGX system, the distributed processing architecture used in the simulation environment, and modifications to the visualization pipeline required to accommodate the display configuration.

  15. A virtual size-variable pinhole for single photon confocal microscopy

    NASA Astrophysics Data System (ADS)

    Gao, Guangjun; Khoobehi, Bahram

    2013-03-01

    Pinhole is a critical device in single photon confocal microscopy (SPCM) owning to its ability to block the background noise scattered from back and forth of the focal plane. Without pinhole, the sectioning ability of SPCM will be degraded and many background noise signals will occurred together with useful signals, and sometimes these bad noises can submerge the details that we are interested in. However a pinhole with too small diameter will block both background noises and part of signals and decrease the intensity of the image. Therefore in many cases pinhole size should be selected carefully. Unfortunately because of constrains in mechanics, a pinhole that can change its size continuously, for example from 10 μm to 100 μm, is unavailable. For most commercial confocal microscopies, only several discrete pinhole sizes are provided, such as 10 μm, 30 μm, 60 μm etc. Things will be even harder for some imaging systems which use the input interface of a single mode fiber as the pinhole of SPCM, and then the pinhole size of these systems will be fixed, which far limit the optimization of systems' performance. In this paper, we design a size-variable pinhole setup that can offer a virtual pinhole with its diameter adjustable, which includes a physical pinhole (or single mode fiber) and a fine designed zoom relay (ZR) optical system. The magnification ratio of this ZR can vary smoothly while keeping the conjugation distance unchanged. The aberrations of the ZR are well balanced and diffraction-limited image performance are obtained so that the virtual pinhole can block background scattering noise and pass the in-focus signal effectively and accurately. Simulation results are also provided and discussed.

  16. Ephedrine fails to accelerate the onset of neuromuscular block by vecuronium.

    PubMed

    Komatsu, Ryu; Nagata, Osamu; Ozaki, Makoto; Sessler, Daniel I

    2003-08-01

    The onset time of neuromuscular blocking drugs is partially determined by circulatory factors, including muscle blood flow and cardiac output. We thus tested the hypothesis that a bolus of ephedrine accelerates the onset of vecuronium neuromuscular block by increasing cardiac output. A prospective, randomized study was conducted in 53 patients scheduled for elective surgery. After the induction of anesthesia, the ulnar nerve was stimulated supramaximally every 10 s, and the evoked twitch response of the adductor pollicis was recorded with accelerometry. Patients were maintained under anesthesia with continuous infusion of propofol for 10 min and then randomly assigned to ephedrine 210 microg/kg (n = 27) or an equivalent volume of saline (n = 26). The test solution was given 1 min before the administration of 0.1 mg/kg of vecuronium. Cardiac output was monitored with impedance cardiography. Ephedrine, but not saline, increased cardiac index (17%; P = 0.003). Nonetheless, the onset of 90% neuromuscular block was virtually identical in the patients given ephedrine (183 +/- 41 s) and saline (181 +/- 47 s). There was no correlation between cardiac index and onset of the blockade. We conclude that the onset of the vecuronium-induced neuromuscular block is primarily determined by factors other than cardiac output. The combination of ephedrine and vecuronium thus cannot be substituted for rapid-acting nondepolarizing muscle relaxants. Ephedrine increased cardiac index but failed to speed onset of neuromuscular block with vecuronium. We conclude that ephedrine administration does not shorten the onset time of vecuronium.

  17. Radiometric Block Adjusment and Digital Radiometric Model Generation

    NASA Astrophysics Data System (ADS)

    Pros, A.; Colomina, I.; Navarro, J. A.; Antequera, R.; Andrinal, P.

    2013-05-01

    In this paper we present a radiometric block adjustment method that is related to geometric block adjustment and to the concept of a terrain Digital Radiometric Model (DRM) as a complement to the terrain digital elevation and surface models. A DRM, in our concept, is a function that for each ground point returns a reflectance value and a Bidirectional Reflectance Distribution Function (BRDF). In a similar way to the terrain geometric reconstruction procedure, given an image block of some terrain area, we split the DRM generation in two phases: radiometric block adjustment and DRM generation. In the paper we concentrate on the radiometric block adjustment step, but we also describe a preliminary DRM generator. In the block adjustment step, after a radiometric pre-calibraton step, local atmosphere radiative transfer parameters, and ground reflectances and BRDFs at the radiometric tie points are estimated. This radiometric block adjustment is based on atmospheric radiative transfer (ART) models, pre-selected BRDF models and radiometric ground control points. The proposed concept is implemented and applied in an experimental campaign, and the obtained results are presented. The DRM and orthophoto mosaics are generated showing no radiometric differences at the seam lines.

  18. "Science SQL" as a Building Block for Flexible, Standards-based Data Infrastructures

    NASA Astrophysics Data System (ADS)

    Baumann, Peter

    2016-04-01

    We have learnt to live with the pain of separating data and metadata into non-interoperable silos. For metadata, we enjoy the flexibility of databases, be they relational, graph, or some other NoSQL. Contrasting this, users still "drown in files" as an unstructured, low-level archiving paradigm. It is time to bridge this chasm which once was technologically induced, but today can be overcome. One building block towards a common re-integrated information space is to support massive multi-dimensional spatio-temporal arrays. These "datacubes" appear as sensor, image, simulation, and statistics data in all science and engineering domains, and beyond. For example, 2-D satellilte imagery, 2-D x/y/t image timeseries and x/y/z geophysical voxel data, and 4-D x/y/z/t climate data contribute to today's data deluge in the Earth sciences. Virtual observatories in the Space sciences routinely generate Petabytes of such data. Life sciences deal with microarray data, confocal microscopy, human brain data, which all fall into the same category. The ISO SQL/MDA (Multi-Dimensional Arrays) candidate standard is extending SQL with modelling and query support for n-D arrays ("datacubes") in a flexible, domain-neutral way. This heralds a new generation of services with new quality parameters, such as flexibility, ease of access, embedding into well-known user tools, and scalability mechanisms that remain completely transparent to users. Technology like the EU rasdaman ("raster data manager") Array Database system can support all of the above examples simultaneously, with one technology. This is practically proven: As of today, rasdaman is in operational use on hundreds of Terabytes of satellite image timeseries datacubes, with transparent query distribution across more than 1,000 nodes. Therefore, Array Databases offering SQL/MDA constitute a natural common building block for next-generation data infrastructures. Being initiator and editor of the standard we present principles

  19. Polydispersity-Driven Block Copolymer Amphiphile Self-Assembly into Prolate-Spheroid Micelles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schmitt, Andrew L.; Repollet-Pedrosa, Milton H.; Mahanthappa, Mahesh K.

    The aqueous self-assembly behavior of polydisperse poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) macromolecular triblock amphiphiles is examined to discern the implications of continuous polydispersity in the hydrophobic block on the resulting aqueous micellar morphologies of otherwise monodisperse polymer surfactants. The chain length polydispersity and implicit composition polydispersity of these samples furnishes a distribution of preferred interfacial curvatures, resulting in dilute aqueous block copolymer dispersions exhibiting coexisting spherical and rod-like micelles with vesicles in a single sample with a O weight fraction, w{sub O}, of 0.18. At higher w{sub O} = 0.51-0.68, the peak in the interfacial curvature distribution shifts and we observemore » the formation of only American football-shaped micelles. We rationalize the formation of these anisotropically shaped aggregates based on the intrinsic distribution of preferred curvatures adopted by the polydisperse copolymer amphiphiles and on the relief of core block chain stretching by chain-length-dependent intramicellar segregation.« less

  20. User modeling for distributed virtual environment intelligent agents

    NASA Astrophysics Data System (ADS)

    Banks, Sheila B.; Stytz, Martin R.

    1999-07-01

    This paper emphasizes the requirement for user modeling by presenting the necessary information to motivate the need for and use of user modeling for intelligent agent development. The paper will present information on our current intelligent agent development program, the Symbiotic Information Reasoning and Decision Support (SIRDS) project. We then discuss the areas of intelligent agents and user modeling, which form the foundation of the SIRDS project. Included in the discussion of user modeling are its major components, which are cognitive modeling and behavioral modeling. We next motivate the need for and user of a methodology to develop user models to encompass work within cognitive task analysis. We close the paper by drawing conclusions from our current intelligent agent research project and discuss avenues of future research in the utilization of user modeling for the development of intelligent agents for virtual environments.

  1. Distributed computing environments for future space control systems

    NASA Technical Reports Server (NTRS)

    Viallefont, Pierre

    1993-01-01

    The aim of this paper is to present the results of a CNES research project on distributed computing systems. The purpose of this research was to study the impact of the use of new computer technologies in the design and development of future space applications. The first part of this study was a state-of-the-art review of distributed computing systems. One of the interesting ideas arising from this review is the concept of a 'virtual computer' allowing the distributed hardware architecture to be hidden from a software application. The 'virtual computer' can improve system performance by adapting the best architecture (addition of computers) to the software application without having to modify its source code. This concept can also decrease the cost and obsolescence of the hardware architecture. In order to verify the feasibility of the 'virtual computer' concept, a prototype representative of a distributed space application is being developed independently of the hardware architecture.

  2. Intelligent distributed medical image management

    NASA Astrophysics Data System (ADS)

    Garcia, Hong-Mei C.; Yun, David Y.

    1995-05-01

    The rapid advancements in high performance global communication have accelerated cooperative image-based medical services to a new frontier. Traditional image-based medical services such as radiology and diagnostic consultation can now fully utilize multimedia technologies in order to provide novel services, including remote cooperative medical triage, distributed virtual simulation of operations, as well as cross-country collaborative medical research and training. Fast (efficient) and easy (flexible) retrieval of relevant images remains a critical requirement for the provision of remote medical services. This paper describes the database system requirements, identifies technological building blocks for meeting the requirements, and presents a system architecture for our target image database system, MISSION-DBS, which has been designed to fulfill the goals of Project MISSION (medical imaging support via satellite integrated optical network) -- an experimental high performance gigabit satellite communication network with access to remote supercomputing power, medical image databases, and 3D visualization capabilities in addition to medical expertise anywhere and anytime around the country. The MISSION-DBS design employs a synergistic fusion of techniques in distributed databases (DDB) and artificial intelligence (AI) for storing, migrating, accessing, and exploring images. The efficient storage and retrieval of voluminous image information is achieved by integrating DDB modeling and AI techniques for image processing while the flexible retrieval mechanisms are accomplished by combining attribute- based and content-based retrievals.

  3. Mentally simulated movements in virtual reality: does Fitts's law hold in motor imagery?

    PubMed

    Decety, J; Jeannerod, M

    1995-12-14

    This study was designed to investigate mentally simulated actions in a virtual reality environment. Naive human subjects (n = 15) were instructed to imagine themselves walking in a three-dimensional virtual environment toward gates of different apparent widths placed at three different apparent distances. Each subject performed nine blocks of six trials in a randomised order. The response time (reaction time and mental walking time) was measured as the duration between an acoustic go signal and a motor signal produced by the subject. There was a combined effect on response time of both gate width and distance. Response time increased for decreasing apparent gate widths when the gate was placed at different distances. These results support the notion that mentally simulated actions are governed by central motor rules.

  4. Sensitivity-based virtual fields for the non-linear virtual fields method

    NASA Astrophysics Data System (ADS)

    Marek, Aleksander; Davis, Frances M.; Pierron, Fabrice

    2017-09-01

    The virtual fields method is an approach to inversely identify material parameters using full-field deformation data. In this manuscript, a new set of automatically-defined virtual fields for non-linear constitutive models has been proposed. These new sensitivity-based virtual fields reduce the influence of noise on the parameter identification. The sensitivity-based virtual fields were applied to a numerical example involving small strain plasticity; however, the general formulation derived for these virtual fields is applicable to any non-linear constitutive model. To quantify the improvement offered by these new virtual fields, they were compared with stiffness-based and manually defined virtual fields. The proposed sensitivity-based virtual fields were consistently able to identify plastic model parameters and outperform the stiffness-based and manually defined virtual fields when the data was corrupted by noise.

  5. 31 CFR 598.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Blocked account; blocked property. 598.301 Section 598.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... REGULATIONS General Definitions § 598.301 Blocked account; blocked property. The terms blocked account and...

  6. 31 CFR 598.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Blocked account; blocked property. 598.301 Section 598.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... REGULATIONS General Definitions § 598.301 Blocked account; blocked property. The terms blocked account and...

  7. 31 CFR 598.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Blocked account; blocked property. 598.301 Section 598.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... REGULATIONS General Definitions § 598.301 Blocked account; blocked property. The terms blocked account and...

  8. 31 CFR 598.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Blocked account; blocked property. 598.301 Section 598.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued... REGULATIONS General Definitions § 598.301 Blocked account; blocked property. The terms blocked account and...

  9. Virtual Reality

    DTIC Science & Technology

    1993-04-01

    until exhausted. SECURITY CLASSIFICATION OF THIS PAGE All other editions are obsolete. UNCLASSIFIED " VIRTUAL REALITY JAMES F. DAILEY, LIEUTENANT COLONEL...US" This paper reviews the exciting field of virtual reality . The author describes the basic concepts of virtual reality and finds that its numerous...potential benefits to society could revolutionize everyday life. The various components that make up a virtual reality system are described in detail

  10. Virtual Collaborative Simulation Environment for Integrated Product and Process Development

    NASA Technical Reports Server (NTRS)

    Gulli, Michael A.

    1997-01-01

    Deneb Robotics is a leader in the development of commercially available, leading edge three- dimensional simulation software tools for virtual prototyping,, simulation-based design, manufacturing process simulation, and factory floor simulation and training applications. Deneb has developed and commercially released a preliminary Virtual Collaborative Engineering (VCE) capability for Integrated Product and Process Development (IPPD). This capability allows distributed, real-time visualization and evaluation of design concepts, manufacturing processes, and total factory and enterprises in one seamless simulation environment.

  11. Community and Virtual Community.

    ERIC Educational Resources Information Center

    Ellis, David; Oldridge, Rachel; Vasconcelos, Ana

    2004-01-01

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

  12. Block rotations, fault domains and crustal deformation in the western US

    NASA Technical Reports Server (NTRS)

    Nur, Amos

    1990-01-01

    The aim of the project was to develop a 3D model of crustal deformation by distributed fault sets and to test the model results in the field. In the first part of the project, Nur's 2D model (1986) was generalized to 3D. In Nur's model the frictional strength of rocks and faults of a domain provides a tight constraint on the amount of rotation that a fault set can undergo during block rotation. Domains of fault sets are commonly found in regions where the deformation is distributed across a region. The interaction of each fault set causes the fault bounded blocks to rotate. The work that has been done towards quantifying the rotation of fault sets in a 3D stress field is briefly summarized. In the second part of the project, field studies were carried out in Israel, Nevada and China. These studies combined both paleomagnetic and structural information necessary to test the block rotation model results. In accordance with the model, field studies demonstrate that faults and attending fault bounded blocks slip and rotate away from the direction of maximum compression when deformation is distributed across fault sets. Slip and rotation of fault sets may continue as long as the earth's crustal strength is not exceeded. More optimally oriented faults must form, for subsequent deformation to occur. Eventually the block rotation mechanism may create a complex pattern of intersecting generations of faults.

  13. Fault-tolerant computer study. [logic designs for building block circuits

    NASA Technical Reports Server (NTRS)

    Rennels, D. A.; Avizienis, A. A.; Ercegovac, M. D.

    1981-01-01

    A set of building block circuits is described which can be used with commercially available microprocessors and memories to implement fault tolerant distributed computer systems. Each building block circuit is intended for VLSI implementation as a single chip. Several building blocks and associated processor and memory chips form a self checking computer module with self contained input output and interfaces to redundant communications buses. Fault tolerance is achieved by connecting self checking computer modules into a redundant network in which backup buses and computer modules are provided to circumvent failures. The requirements and design methodology which led to the definition of the building block circuits are discussed.

  14. Technophiles to Newbies: The Challenge of Supporting Distributed Teams to Maintain Engagement in Virtual Worlds

    NASA Technical Reports Server (NTRS)

    Griffith, Karen

    2011-01-01

    The purpose of this paper is to look for links in a virtual trainee's interest and self-efficacy in a simulated event as it relates to their previous self-reported technical skill level. Ultimately, the idea would be to provide the right amount of support at the right place at the right time to set the conditions for maximum transfer of the skill sets to the work place. An anecdotal recap of a recent experiment of a medium-scale training event produced in a virtual world will provide examples for discussion. In July 2010, a virtual training event was produced for the Air Force Research Lab's Games for Team Training (GaMeTT) at the Patriot Exercise at Volk Field in Wisconsin. There were 29 EMEDS participants who completed the simulated OCO event using the OLIVE gaming engine. Approximately 25 avatars were present at any given time; including role players, observers, coordinators and participants.

  15. Anomalous neural circuit function in schizophrenia during a virtual Morris water task.

    PubMed

    Folley, Bradley S; Astur, Robert; Jagannathan, Kanchana; Calhoun, Vince D; Pearlson, Godfrey D

    2010-02-15

    Previous studies have reported learning and navigation impairments in schizophrenia patients during virtual reality allocentric learning tasks. The neural bases of these deficits have not been explored using functional MRI despite well-explored anatomic characterization of these paradigms in non-human animals. Our objective was to characterize the differential distributed neural circuits involved in virtual Morris water task performance using independent component analysis (ICA) in schizophrenia patients and controls. Additionally, we present behavioral data in order to derive relationships between brain function and performance, and we have included a general linear model-based analysis in order to exemplify the incremental and differential results afforded by ICA. Thirty-four individuals with schizophrenia and twenty-eight healthy controls underwent fMRI scanning during a block design virtual Morris water task using hidden and visible platform conditions. Independent components analysis was used to deconstruct neural contributions to hidden and visible platform conditions for patients and controls. We also examined performance variables, voxel-based morphometry and hippocampal subparcellation, and regional BOLD signal variation. Independent component analysis identified five neural circuits. Mesial temporal lobe regions, including the hippocampus, were consistently task-related across conditions and groups. Frontal, striatal, and parietal circuits were recruited preferentially during the visible condition for patients, while frontal and temporal lobe regions were more saliently recruited by controls during the hidden platform condition. Gray matter concentrations and BOLD signal in hippocampal subregions were associated with task performance in controls but not patients. Patients exhibited impaired performance on the hidden and visible conditions of the task, related to negative symptom severity. While controls showed coupling between neural circuits, regional

  16. A direct observation method for auditing large urban centers using stratified sampling, mobile GIS technology and virtual environments.

    PubMed

    Lafontaine, Sean J V; Sawada, M; Kristjansson, Elizabeth

    2017-02-16

    With the expansion and growth of research on neighbourhood characteristics, there is an increased need for direct observational field audits. Herein, we introduce a novel direct observational audit method and systematic social observation instrument (SSOI) for efficiently assessing neighbourhood aesthetics over large urban areas. Our audit method uses spatial random sampling stratified by residential zoning and incorporates both mobile geographic information systems technology and virtual environments. The reliability of our method was tested in two ways: first, in 15 Ottawa neighbourhoods, we compared results at audited locations over two subsequent years, and second; we audited every residential block (167 blocks) in one neighbourhood and compared the distribution of SSOI aesthetics index scores with results from the randomly audited locations. Finally, we present interrater reliability and consistency results on all observed items. The observed neighbourhood average aesthetics index score estimated from four or five stratified random audit locations is sufficient to characterize the average neighbourhood aesthetics. The SSOI was internally consistent and demonstrated good to excellent interrater reliability. At the neighbourhood level, aesthetics is positively related to SES and physical activity and negatively correlated with BMI. The proposed approach to direct neighbourhood auditing performs sufficiently and has the advantage of financial and temporal efficiency when auditing a large city.

  17. Testing block subdivision algorithms on block designs

    NASA Astrophysics Data System (ADS)

    Wiseman, Natalie; Patterson, Zachary

    2016-01-01

    Integrated land use-transportation models predict future transportation demand taking into account how households and firms arrange themselves partly as a function of the transportation system. Recent integrated models require parcels as inputs and produce household and employment predictions at the parcel scale. Block subdivision algorithms automatically generate parcel patterns within blocks. Evaluating block subdivision algorithms is done by way of generating parcels and comparing them to those in a parcel database. Three block subdivision algorithms are evaluated on how closely they reproduce parcels of different block types found in a parcel database from Montreal, Canada. While the authors who developed each of the algorithms have evaluated them, they have used their own metrics and block types to evaluate their own algorithms. This makes it difficult to compare their strengths and weaknesses. The contribution of this paper is in resolving this difficulty with the aim of finding a better algorithm suited to subdividing each block type. The proposed hypothesis is that given the different approaches that block subdivision algorithms take, it's likely that different algorithms are better adapted to subdividing different block types. To test this, a standardized block type classification is used that consists of mutually exclusive and comprehensive categories. A statistical method is used for finding a better algorithm and the probability it will perform well for a given block type. Results suggest the oriented bounding box algorithm performs better for warped non-uniform sites, as well as gridiron and fragmented uniform sites. It also produces more similar parcel areas and widths. The Generalized Parcel Divider 1 algorithm performs better for gridiron non-uniform sites. The Straight Skeleton algorithm performs better for loop and lollipop networks as well as fragmented non-uniform and warped uniform sites. It also produces more similar parcel shapes and patterns.

  18. Comparison of the post-operative analgesic effect of paravertebral block, pectoral nerve block and local infiltration in patients undergoing modified radical mastectomy: A randomised double-blind trial.

    PubMed

    Syal, Kartik; Chandel, Ankita

    2017-08-01

    Paravertebral block, pectoral nerve (Pecs) block and wound infiltration are three modalities for post-operative analgesia following breast surgery. This study compares the analgesic efficacy of these techniques for post-operative analgesia. Sixty-five patients with American Society of Anesthesiologists' physical status 1 or 2 undergoing modified radical mastectomy with axillary dissection were recruited for the study. All patients received 21 mL 0.5% bupivacaine with adrenaline in the technique which was performed at the end of the surgery prior to extubation. Patients in Group 1 (local anaesthetic [LA], n = 22) received infiltration at the incision site after surgery, Group 2 patients (paravertebral block [PVB], n = 22) received ultrasound-guided ipsilateral paravertebral block while Group 3 patients [PECT] ( n = 21) received ultrasound-guided ipsilateral Pecs blocks I and II. Patients were evaluated for pain scores at 0, 2, 4, 6, 12 and 24 h, duration of post-operative analgesia and rescue analgesic doses required. Non-normally distributed data were analysed using the Kruskal-Wallis test and Analysis of variance for normal distribution. The post-operative visual analogue scale scores were lower in PVB group compared with others at 0, 2, 4, 12 and 24 h ( P < 0.05). Mean duration of analgesia was significantly prolonged in PVB group ( P < 0.001) with lesser rescue analgesic consumption up to 24 h. Ultrasound-guided paravertebral block reduces post-operative pain scores, prolongs the duration of analgesia and decreases demands for rescue analgesics in the first 24 h of post-operative period compared to ultrasound-guided Pecs block and local infiltration block.

  19. Surface plasmon enhanced cell microscopy with blocked random spatial activation

    NASA Astrophysics Data System (ADS)

    Son, Taehwang; Oh, Youngjin; Lee, Wonju; Yang, Heejin; Kim, Donghyun

    2016-03-01

    We present surface plasmon enhanced fluorescence microscopy with random spatial sampling using patterned block of silver nanoislands. Rigorous coupled wave analysis was performed to confirm near-field localization on nanoislands. Random nanoislands were fabricated in silver by temperature annealing. By analyzing random near-field distribution, average size of localized fields was found to be on the order of 135 nm. Randomly localized near-fields were used to spatially sample F-actin of J774 cells (mouse macrophage cell-line). Image deconvolution algorithm based on linear imaging theory was established for stochastic estimation of fluorescent molecular distribution. The alignment between near-field distribution and raw image was performed by the patterned block. The achieved resolution is dependent upon factors including the size of localized fields and estimated to be 100-150 nm.

  20. Sensorimotor Learning during a Marksmanship Task in Immersive Virtual Reality

    PubMed Central

    Rao, Hrishikesh M.; Khanna, Rajan; Zielinski, David J.; Lu, Yvonne; Clements, Jillian M.; Potter, Nicholas D.; Sommer, Marc A.; Kopper, Regis; Appelbaum, Lawrence G.

    2018-01-01

    Sensorimotor learning refers to improvements that occur through practice in the performance of sensory-guided motor behaviors. Leveraging novel technical capabilities of an immersive virtual environment, we probed the component kinematic processes that mediate sensorimotor learning. Twenty naïve subjects performed a simulated marksmanship task modeled after Olympic Trap Shooting standards. We measured movement kinematics and shooting performance as participants practiced 350 trials while receiving trial-by-trial feedback about shooting success. Spatiotemporal analysis of motion tracking elucidated the ballistic and refinement phases of hand movements. We found systematic changes in movement kinematics that accompanied improvements in shot accuracy during training, though reaction and response times did not change over blocks. In particular, we observed longer, slower, and more precise ballistic movements that replaced effort spent on corrections and refinement. Collectively, these results leverage developments in immersive virtual reality technology to quantify and compare the kinematics of movement during early learning of full-body sensorimotor orienting. PMID:29467693

  1. The Fold Analysis Challenge: A virtual globe-based educational resource

    NASA Astrophysics Data System (ADS)

    De Paor, Declan G.; Dordevic, Mladen M.; Karabinos, Paul; Tewksbury, Barbara J.; Whitmeyer, Steven J.

    2016-04-01

    We present an undergraduate structural geology laboratory exercise using the Google Earth virtual globe with COLLADA models, optionally including an interactive stereographic projection and JavaScript controls. The learning resource challenges students to identify bedding traces and estimate bedding orientation at several locations on a fold, to fit the fold axis and axial plane to stereographic projection data, and to fit a doubly-plunging fold model to the large-scale structure. The chosen fold is the Sheep Mountain Anticline, a Laramide uplift in the Big Horn Basin of Wyoming. We take an education research-based approach, guiding students through three levels of difficulty. The exercise aims to counter common student misconceptions and stumbling blocks regarding penetrative structures. It can be used in preparation for an in-person field trip, for post-trip reinforcement, or as a virtual field experience in an online-only course. Our KML scripts can be easily transferred to other fold structures around the globe.

  2. A constraint optimization based virtual network mapping method

    NASA Astrophysics Data System (ADS)

    Li, Xiaoling; Guo, Changguo; Wang, Huaimin; Li, Zhendong; Yang, Zhiwen

    2013-03-01

    Virtual network mapping problem, maps different virtual networks onto the substrate network is an extremely challenging work. This paper proposes a constraint optimization based mapping method for solving virtual network mapping problem. This method divides the problem into two phases, node mapping phase and link mapping phase, which are all NP-hard problems. Node mapping algorithm and link mapping algorithm are proposed for solving node mapping phase and link mapping phase, respectively. Node mapping algorithm adopts the thinking of greedy algorithm, mainly considers two factors, available resources which are supplied by the nodes and distance between the nodes. Link mapping algorithm is based on the result of node mapping phase, adopts the thinking of distributed constraint optimization method, which can guarantee to obtain the optimal mapping with the minimum network cost. Finally, simulation experiments are used to validate the method, and results show that the method performs very well.

  3. Attentional Demand of a Virtual Reality-Based Reaching Task in Nondisabled Older Adults.

    PubMed

    Chen, Yi-An; Chung, Yu-Chen; Proffitt, Rachel; Wade, Eric; Winstein, Carolee

    2015-12-01

    Attention during exercise is known to affect performance; however, the attentional demand inherent to virtual reality (VR)-based exercise is not well understood. We used a dual-task paradigm to compare the attentional demands of VR-based and non-VR-based (conventional, real-world) exercise: 22 non-disabled older adults performed a primary reaching task to virtual and real targets in a counterbalanced block order while verbally responding to an unanticipated auditory tone in one third of the trials. The attentional demand of the primary reaching task was inferred from the voice response time (VRT) to the auditory tone. Participants' engagement level and task experience were also obtained using questionnaires. The virtual target condition was more attention demanding (significantly longer VRT) than the real target condition. Secondary analyses revealed a significant interaction between engagement level and target condition on attentional demand. For participants who were highly engaged, attentional demand was high and independent of target condition. However, for those who were less engaged, attentional demand was low and depended on target condition (i.e., virtual > real). These findings add important knowledge to the growing body of research pertaining to the development and application of technology-enhanced exercise for elders and for rehabilitation purposes.

  4. Attentional Demand of a Virtual Reality-Based Reaching Task in Nondisabled Older Adults

    PubMed Central

    Chen, Yi-An; Chung, Yu-Chen; Proffitt, Rachel; Wade, Eric; Winstein, Carolee

    2015-01-01

    Attention during exercise is known to affect performance; however, the attentional demand inherent to virtual reality (VR)-based exercise is not well understood. We used a dual-task paradigm to compare the attentional demands of VR-based and non-VR-based (conventional, real-world) exercise: 22 non-disabled older adults performed a primary reaching task to virtual and real targets in a counterbalanced block order while verbally responding to an unanticipated auditory tone in one third of the trials. The attentional demand of the primary reaching task was inferred from the voice response time (VRT) to the auditory tone. Participants' engagement level and task experience were also obtained using questionnaires. The virtual target condition was more attention demanding (significantly longer VRT) than the real target condition. Secondary analyses revealed a significant interaction between engagement level and target condition on attentional demand. For participants who were highly engaged, attentional demand was high and independent of target condition. However, for those who were less engaged, attentional demand was low and depended on target condition (i.e., virtual > real). These findings add important knowledge to the growing body of research pertaining to the development and application of technology-enhanced exercise for elders and for rehabilitation purposes. PMID:27004233

  5. Scalable, High-performance 3D Imaging Software Platform: System Architecture and Application to Virtual Colonoscopy

    PubMed Central

    Yoshida, Hiroyuki; Wu, Yin; Cai, Wenli; Brett, Bevin

    2013-01-01

    One of the key challenges in three-dimensional (3D) medical imaging is to enable the fast turn-around time, which is often required for interactive or real-time response. This inevitably requires not only high computational power but also high memory bandwidth due to the massive amount of data that need to be processed. In this work, we have developed a software platform that is designed to support high-performance 3D medical image processing for a wide range of applications using increasingly available and affordable commodity computing systems: multi-core, clusters, and cloud computing systems. To achieve scalable, high-performance computing, our platform (1) employs size-adaptive, distributable block volumes as a core data structure for efficient parallelization of a wide range of 3D image processing algorithms; (2) supports task scheduling for efficient load distribution and balancing; and (3) consists of a layered parallel software libraries that allow a wide range of medical applications to share the same functionalities. We evaluated the performance of our platform by applying it to an electronic cleansing system in virtual colonoscopy, with initial experimental results showing a 10 times performance improvement on an 8-core workstation over the original sequential implementation of the system. PMID:23366803

  6. 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.

  7. Mapping, Awareness, And Virtualization Network Administrator Training Tool Virtualization Module

    DTIC Science & Technology

    2016-03-01

    AND VIRTUALIZATION NETWORK ADMINISTRATOR TRAINING TOOL VIRTUALIZATION MODULE by Erik W. Berndt March 2016 Thesis Advisor: John Gibson...REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE MAPPING, AWARENESS, AND VIRTUALIZATION NETWORK ADMINISTRATOR TRAINING TOOL... VIRTUALIZATION MODULE 5. FUNDING NUMBERS 6. AUTHOR(S) Erik W. Berndt 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Postgraduate School

  8. Blocking performance of the hose model and the pipe model for VPN service provisioning over WDM optical networks

    NASA Astrophysics Data System (ADS)

    Wang, Haibo; Swee Poo, Gee

    2004-08-01

    We study the provisioning of virtual private network (VPN) service over WDM optical networks. For this purpose, we investigate the blocking performance of the hose model versus the pipe model for the provisioning. Two techniques are presented: an analytical queuing model and a discrete event simulation. The queuing model is developed from the multirate reduced-load approximation technique. The simulation is done with the OPNET simulator. Several experimental situations were used. The blocking probabilities calculated from the two approaches show a close match, indicating that the multirate reduced-load approximation technique is capable of predicting the blocking performance for the pipe model and the hose model in WDM networks. A comparison of the blocking behavior of the two models shows that the hose model has superior blocking performance as compared with pipe model. By and large, the blocking probability of the hose model is better than that of the pipe model by a few orders of magnitude, particularly at low load regions. The flexibility of the hose model allowing for the sharing of resources on a link among all connections accounts for its superior performance.

  9. Can virtual reality be used to conduct mass prophylaxis clinic training? A pilot program.

    PubMed

    Yellowlees, Peter; Cook, James N; Marks, Shayna L; Wolfe, Daniel; Mangin, Elanor

    2008-03-01

    To create and evaluate a pilot bioterrorism defense training environment using virtual reality technology. The present pilot project used Second Life, an internet-based virtual world system, to construct a virtual reality environment to mimic an actual setting that might be used as a Strategic National Stockpile (SNS) distribution site for northern California in the event of a bioterrorist attack. Scripted characters were integrated into the system as mock patients to analyze various clinic workflow scenarios. Users tested the virtual environment over two sessions. Thirteen users who toured the environment were asked to complete an evaluation survey. Respondents reported that the virtual reality system was relevant to their practice and had potential as a method of bioterrorism defense training. Computer simulations of bioterrorism defense training scenarios are feasible with existing personal computer technology. The use of internet-connected virtual environments holds promise for bioterrorism defense training. Recommendations are made for public health agencies regarding the implementation and benefits of using virtual reality for mass prophylaxis clinic training.

  10. 31 CFR 598.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... 598.301 Section 598.301 Money and Finance: Treasury Regulations Relating to Money and Finance... REGULATIONS General Definitions § 598.301 Blocked account; blocked property. The terms blocked account and blocked property mean any account or property subject to § 598.202 held in the name of a specially...

  11. 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.

  12. 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.

  13. Block correlated second order perturbation theory with a generalized valence bond reference function.

    PubMed

    Xu, Enhua; Li, Shuhua

    2013-11-07

    The block correlated second-order perturbation theory with a generalized valence bond (GVB) reference (GVB-BCPT2) is proposed. In this approach, each geminal in the GVB reference is considered as a "multi-orbital" block (a subset of spin orbitals), and each occupied or virtual spin orbital is also taken as a single block. The zeroth-order Hamiltonian is set to be the summation of the individual Hamiltonians of all blocks (with explicit two-electron operators within each geminal) so that the GVB reference function and all excited configuration functions are its eigenfunctions. The GVB-BCPT2 energy can be directly obtained without iteration, just like the second order Mo̸ller-Plesset perturbation method (MP2), both of which are size consistent. We have applied this GVB-BCPT2 method to investigate the equilibrium distances and spectroscopic constants of 7 diatomic molecules, conformational energy differences of 8 small molecules, and bond-breaking potential energy profiles in 3 systems. GVB-BCPT2 is demonstrated to have noticeably better performance than MP2 for systems with significant multi-reference character, and provide reasonably accurate results for some systems with large active spaces, which are beyond the capability of all CASSCF-based methods.

  14. [The virtual university in medicine. Context, concepts, specifications, users' manual].

    PubMed

    Duvauferrier, R; Séka, L P; Rolland, Y; Rambeau, M; Le Beux, P; Morcet, N

    1998-09-01

    The widespread use of Web servers, with the emergence of interactive functions and the possibility of credit card payment via Internet, together with the requirement for continuing education and the subsequent need for a computer to link into the health care network have incited the development of a virtual university scheme on Internet. The Virtual University of Radiology is not only a computer-assisted teaching tool with a set of attractive features, but also a powerful engine allowing the organization, distribution and control of medical knowledge available in the www.server. The scheme provides patient access to general information, a secretary's office for enrollment and the Virtual University itself, with its library, image database, a forum for subspecialties and clinical case reports, an evaluation module and various guides and help tools for diagnosis, prescription and indexing. Currently the Virtual University of Radiology offers diagnostic imaging, but can also be used by other specialties and for general practice.

  15. Neurostimulation in ultrasound-guided infraclavicular block: a prospective randomized trial.

    PubMed

    Dingemans, Emmanuel; Williams, Stephan R; Arcand, Geneviève; Chouinard, Philippe; Harris, Patrick; Ruel, Monique; Girard, François

    2007-05-01

    Ultrasound guidance (USG) for infraclavicular blocks provides real time visualization of the advancing needle and local anesthetic distribution. Whether visualization of local anesthetic spread can supplant neurostimulation as the end point for local anesthetic injection during USG block has never been formally evaluated. Therefore, for this prospective randomized study, we recruited 72 patients scheduled for hand or forearm surgery and compared the speed of execution and quality of USG infraclavicular block with either USG alone (Group U) or USG combined with neurostimulation (Group S). In Group U, local anesthetic was deposited in a U-shaped distribution posterior and to each side of the axillary artery using as few injections as possible (1, 2, and 3 injections in 29, 6, and 3 patients, respectively). In Group S, a single injection was made after obtaining a distal motor response with a stimulating current between 0.3 and 0.6 mA. The anesthetic solution consisted of 0.5 mL/kg of lidocaine 1.5%, bupivacaine 0.125%, and epinephrine 1:200 000 (final concentrations). Procedure times were significantly shorter in Group U compared with Group S (3.1 +/- 1.6 min and 5.2 +/- 4.7 min, respectively; P = 0.006). In Group S, anesthetic spread was mainly anterior to the axillary artery in 37% of patients and mainly posterior in 63% of patients. Thirty minutes after the injection, 86% of patients in Group U had complete sensory block in the musculocutaneous, median, radial, and ulnar nerve territories compared with 57% in Group S (P = 0.007). Patients blocked in Group U with a single injection had the same rate of complete block (86%) as those blocked with more than one injection (86%). Block supplementation rates were 8% in Group U versus 26% in Group S (P = 0.049). Block failure occurred in one patient in Group S because of an inability to obtain a distal stimulation after 20 min. We conclude that USG infraclavicular block is more rapidly performed and yields a higher

  16. A Robust, Low-Cost Virtual Archive for Science Data

    NASA Technical Reports Server (NTRS)

    Lynnes, Christopher; Vollmer, Bruce

    2005-01-01

    Despite their expense tape silos are still often the only affordable option for petabytescale science data archives, particularly when other factors such as data reliability, floor space, power and cooling load are accounted for. However, the complexity, management software, hardware reliability and access latency of tape silos make online data storage ever more attractive. Drastic reductions in low-cost mass-market PC disk drivers help to make this more affordable (approx. 1$/GB), but are challenging to scale to the petabyte range and of questionable reliability for archival use, On the other hand, if much of the science archive could be "virtualized", i.e., produced on demand when requested by users, we would need store only a fraction of the data online, perhaps bringing an online-only system into in affordable range. Radiance data from the satellite-borne Moderate Resolution Imaging Spectroradiometer (MODIS) instrument provides a good opportunity for such a virtual archive: the raw data amount to 140 GB/day, but these are small relative to the 550 GB/day making up the radiance products. These data are routinely processed as inputs for geophysical parameter products and then archived on tape at the Goddard Earth Sciences Distributed Active Archive (GES DAAC) for distributing to users. Virtualizing them would be an immediate and signifcant reduction in the amount of data being stored in the tape archives and provide more customizable products. A prototype of such a virtual archive is being developed to prove the concept and develop ways of incorporating the robustness that a science data archive requires.

  17. Blocking the interaction between HIV-1 integrase and human LEDGF/p75: mutational studies, virtual screening and molecular dynamics simulations.

    PubMed

    Reddy, Karnati Konda; Singh, Poonam; Singh, Sanjeev Kumar

    2014-03-04

    HIV-1 integrase (IN) mediates integration of viral cDNA into the host cell genome, an essential step in the retroviral life cycle. The human lens epithelium-derived growth factor (LEDGF/p75) is a co-factor of HIV-1 IN that plays a crucial role in viral integration. Because of its crucial role in early steps of HIV replication, the IN-LEDGF/p75 interaction represents an attractive target for anti-HIV drug discovery. In this study, the IN-LEDGF/p75 interaction was studied by in silico mutational studies and molecular dynamics simulations. The results showed that all of the key residues in the LEDGF/p75 binding pocket of IN protein are important for stabilization of the complex. Structure-based virtual screening against HIV-1 IN using the ChemBridge database was performed through three different protocols of docking simulations with varying precisions and computational intensities. Six compounds based on the docking score, binding affinity and pharmacokinetic parameters were selected and an analysis of the interactions with key amino acid residues of IN was carried out. Subsequently, molecular dynamics simulations of these compounds in the LEDGF/p75 binding site of IN were carried out in order to study the stability of complexes and their hydrogen bonding interactions. IN residues Glu170, His171, and Thr174 in chain A as well as Gln95 and Thr125 in chain B were discovered to play important roles in the binding of compounds. These findings could be helpful for blocking IN-LEDGF/p75 interaction, and provide a method for avoiding viral resistance and cross-resistance.

  18. Recent evolution of China's virtual water trade: analysis of selected crops and considerations for policy

    NASA Astrophysics Data System (ADS)

    Shi, J.; Liu, J.; Pinter, L.

    2014-04-01

    China has dramatically increased its virtual water import over recent years. Many studies have focused on the quantity of traded virtual water, but very few go into analysing geographic distribution and the properties of China's virtual water trade network. This paper provides a calculation and analysis of the crop-related virtual water trade network of China based on 27 major primary crops between 1986 and 2009. The results show that China is a net importer of virtual water from water-abundant areas of North America and South America, and a net virtual water exporter to water-stressed areas of Asia, Africa, and Europe. Virtual water import is far larger than virtual water export, and in both import and export a small number of trade partners control the supply chain. Grain crops are the major contributors to virtual water trade, and among grain crops, soybeans, mostly imported from the US, Brazil and Argentina, are the most significant. In order to mitigate water scarcity and secure the food supply, virtual water should actively be incorporated into national water management strategies. And the sources of virtual water import need to be further diversified to reduce supply chain risks and increase resilience.

  19. Development of visual 3D virtual environment for control software

    NASA Technical Reports Server (NTRS)

    Hirose, Michitaka; Myoi, Takeshi; Amari, Haruo; Inamura, Kohei; Stark, Lawrence

    1991-01-01

    Virtual environments for software visualization may enable complex programs to be created and maintained. A typical application might be for control of regional electric power systems. As these encompass broader computer networks than ever, construction of such systems becomes very difficult. Conventional text-oriented environments are useful in programming individual processors. However, they are obviously insufficient to program a large and complicated system, that includes large numbers of computers connected to each other; such programming is called 'programming in the large.' As a solution for this problem, the authors are developing a graphic programming environment wherein one can visualize complicated software in virtual 3D world. One of the major features of the environment is the 3D representation of concurrent process. 3D representation is used to supply both network-wide interprocess programming capability (capability for 'programming in the large') and real-time programming capability. The authors' idea is to fuse both the block diagram (which is useful to check relationship among large number of processes or processors) and the time chart (which is useful to check precise timing for synchronization) into a single 3D space. The 3D representation gives us a capability for direct and intuitive planning or understanding of complicated relationship among many concurrent processes. To realize the 3D representation, a technology to enable easy handling of virtual 3D object is a definite necessity. Using a stereo display system and a gesture input device (VPL DataGlove), our prototype of the virtual workstation has been implemented. The workstation can supply the 'sensation' of the virtual 3D space to a programmer. Software for the 3D programming environment is implemented on the workstation. According to preliminary assessments, a 50 percent reduction of programming effort is achieved by using the virtual 3D environment. The authors expect that the 3D

  20. Blocking probability in the hose-model optical VPN with different number of wavelengths

    NASA Astrophysics Data System (ADS)

    Roslyakov, Alexander V.

    2017-04-01

    Connection setup with guaranteed quality of service (QoS) in the optical virtual private network (OVPN) is a major goal for the network providers. In order to support this we propose a QoS based OVPN connection set up mechanism over WDM network to the end customer. The proposed WDM network model can be specified in terms of QoS parameter such as blocking probability. We estimated this QoS parameter based on the hose-model OVPN. In this mechanism the OVPN connections also can be created or deleted according to the availability of the wavelengths in the optical path. In this paper we have considered the impact of the number of wavelengths on the computation of blocking probability. The goal of the work is to dynamically provide a best OVPN connection during frequent arrival of connection requests with QoS requirements.

  1. Euro-VO-Coordination of virtual observatory activities in Europe

    NASA Astrophysics Data System (ADS)

    Genova, Françoise; Allen, Mark G.; Arviset, Christophe; Lawrence, Andy; Pasian, Fabio; Solano, Enrique; Wambsganss, Joachim

    2015-06-01

    The European Virtual Observatory Euro-VO has been coordinating European VO activities through a series of projects co-funded by the European Commission over the last 15 years. The bulk of VO work in Europe is ensured by the national VO initiatives and those of intergovernmental agencies. VO activities at the European level coordinate the work in support of the three "pillars" of the Virtual Observatory: support to the scientific community, take-up by the data providers, and technological activities. Several Euro-VO projects have also provided direct support to selected developments and prototyping. This paper explains the methodology used by Euro-VO over the years. It summarises the activities which were performed and their evolutions at different stages of the development of the VO, explains the Euro-VO role with respect to the international and national levels of VO activities, details the lessons learnt for best practices for the coordination of the VO building blocks, and the liaison with other European initiatives, documenting the added-value of European coordination. Finally, the current status and next steps of Euro-VO are briefly addressed.

  2. Holding-time-aware asymmetric spectrum allocation in virtual optical networks

    NASA Astrophysics Data System (ADS)

    Lyu, Chunjian; Li, Hui; Liu, Yuze; Ji, Yuefeng

    2017-10-01

    Virtual optical networks (VONs) have been considered as a promising solution to support current high-capacity dynamic traffic and achieve rapid applications deployment. Since most of the network services (e.g., high-definition video service, cloud computing, distributed storage) in VONs are provisioned by dedicated data centers, needing different amount of bandwidth resources in both directions, the network traffic is mostly asymmetric. The common strategy, symmetric provisioning of traffic in optical networks, leads to a waste of spectrum resources in such traffic patterns. In this paper, we design a holding-time-aware asymmetric spectrum allocation module based on SDON architecture and an asymmetric spectrum allocation algorithm based on the module is proposed. For the purpose of reducing spectrum resources' waste, the algorithm attempts to reallocate the idle unidirectional spectrum slots in VONs, which are generated due to the asymmetry of services' bidirectional bandwidth. This part of resources can be exploited by other requests, such as short-time non-VON requests. We also introduce a two-dimensional asymmetric resource model for maintaining idle spectrum resources information of VON in spectrum and time domains. Moreover, a simulation is designed to evaluate the performance of the proposed algorithm, and results show that our proposed asymmetric spectrum allocation algorithm can improve the resource waste and reduce blocking probability.

  3. Parallel-distributed mobile robot simulator

    NASA Astrophysics Data System (ADS)

    Okada, Hiroyuki; Sekiguchi, Minoru; Watanabe, Nobuo

    1996-06-01

    The aim of this project is to achieve an autonomous learning and growth function based on active interaction with the real world. It should also be able to autonomically acquire knowledge about the context in which jobs take place, and how the jobs are executed. This article describes a parallel distributed movable robot system simulator with an autonomous learning and growth function. The autonomous learning and growth function which we are proposing is characterized by its ability to learn and grow through interaction with the real world. When the movable robot interacts with the real world, the system compares the virtual environment simulation with the interaction result in the real world. The system then improves the virtual environment to match the real-world result more closely. This the system learns and grows. It is very important that such a simulation is time- realistic. The parallel distributed movable robot simulator was developed to simulate the space of a movable robot system with an autonomous learning and growth function. The simulator constructs a virtual space faithful to the real world and also integrates the interfaces between the user, the actual movable robot and the virtual movable robot. Using an ultrafast CG (computer graphics) system (FUJITSU AG series), time-realistic 3D CG is displayed.

  4. Comparison of the post-operative analgesic effect of paravertebral block, pectoral nerve block and local infiltration in patients undergoing modified radical mastectomy: A randomised double-blind trial

    PubMed Central

    Syal, Kartik; Chandel, Ankita

    2017-01-01

    Background and Aims: Paravertebral block, pectoral nerve (Pecs) block and wound infiltration are three modalities for post-operative analgesia following breast surgery. This study compares the analgesic efficacy of these techniques for post-operative analgesia. Methods: Sixty-five patients with American Society of Anesthesiologists’ physical status 1 or 2 undergoing modified radical mastectomy with axillary dissection were recruited for the study. All patients received 21 mL 0.5% bupivacaine with adrenaline in the technique which was performed at the end of the surgery prior to extubation. Patients in Group 1 (local anaesthetic [LA], n = 22) received infiltration at the incision site after surgery, Group 2 patients (paravertebral block [PVB], n = 22) received ultrasound-guided ipsilateral paravertebral block while Group 3 patients [PECT] (n = 21) received ultrasound-guided ipsilateral Pecs blocks I and II. Patients were evaluated for pain scores at 0, 2, 4, 6, 12 and 24 h, duration of post-operative analgesia and rescue analgesic doses required. Non-normally distributed data were analysed using the Kruskal-Wallis test and Analysis of variance for normal distribution. Results: The post-operative visual analogue scale scores were lower in PVB group compared with others at 0, 2, 4, 12 and 24 h (P < 0.05). Mean duration of analgesia was significantly prolonged in PVB group (P < 0.001) with lesser rescue analgesic consumption up to 24 h. Conclusion: Ultrasound-guided paravertebral block reduces post-operative pain scores, prolongs the duration of analgesia and decreases demands for rescue analgesics in the first 24 h of post-operative period compared to ultrasound-guided Pecs block and local infiltration block. PMID:28890559

  5. Virtual hand: a 3D tactile interface to virtual environments

    NASA Astrophysics Data System (ADS)

    Rogowitz, Bernice E.; Borrel, Paul

    2008-02-01

    We introduce a novel system that allows users to experience the sensation of touch in a computer graphics environment. In this system, the user places his/her hand on an array of pins, which is moved about space on a 6 degree-of-freedom robot arm. The surface of the pins defines a surface in the virtual world. This "virtual hand" can move about the virtual world. When the virtual hand encounters an object in the virtual world, the heights of the pins are adjusted so that they represent the object's shape, surface, and texture. A control system integrates pin and robot arm motions to transmit information about objects in the computer graphics world to the user. It also allows the user to edit, change and move the virtual objects, shapes and textures. This system provides a general framework for touching, manipulating, and modifying objects in a 3-D computer graphics environment, which may be useful in a wide range of applications, including computer games, computer aided design systems, and immersive virtual worlds.

  6. Entropy of Egypt's virtual water trade gravity field

    NASA Astrophysics Data System (ADS)

    Karakatsanis, Georgios; Bierbach, Sandra

    2016-04-01

    The study investigates the entropy of Egypt's virtual water trade gravity distribution, in order to provide a chart of Egypt's embodied water balance in agricultural trade, in relation to distances with its major counterparties. Moreover, our calculations on the amount of the embodied water traded between Egypt and each of its partners take place according to a combination of available data on the blue, green and grey water footprints as well as the Food and Agriculture Organization (FAO) database of traded amounts per crop type. A study on the virtual water trade gravity, enables us to enrich former related studies (Fracasso 2014; Fracasso, Sartori and Schiavo 2014) via examining Egypt's water supply dependence on the Nile River and if comparative advantages -purely from the side of water quantities- can be identified via recognizing which water footprint categories are particularly high. Additionally, this methodology can comprise -from a fundamental level- a guide for revealing the importance of water footprint types for Egypt's agricultural sector; hence, Egypt's potential comparative advantages, as far as quantitative water endowments are exclusively concerned (without consideration of water or crop prices). Although it is pointed out very correctly by various authors (Antonelli and Sartori 2014) that the virtual water trade concept does not incorporate many important aspects of water supply -such as heavy water price subsidizing- to be used accurately for the identification of comparative advantages, we consider that the purely quantitative examination can provide strong fundamental indications -especially for green and grey water footprints, which are hypothesized to be less sensitive to subsidizing. In overall, this effect can very well provide a primary indication on the organization of the global alimentation trade network (Yang et al. 2006). The gravity equation used contains water footprint data for the 15 top traded crops and the distances for Egypt

  7. Virtual reality as a tool for cross-cultural communication: an example from military team training

    NASA Astrophysics Data System (ADS)

    Downes-Martin, Stephen; Long, Mark; Alexander, Joanna R.

    1992-06-01

    A major problem with communication across cultures, whether professional or national, is that simple language translation if often insufficient to communicate the concepts. This is especially true when the communicators come from highly specialized fields of knowledge or from national cultures with long histories of divergence. This problem becomes critical when the goal of the communication is national negotiation dealing with such high risk items as arms negotiation or trade wars. Virtual Reality technology has considerable potential for facilitating communication across cultures, by immersing the communicators within multiple visual representations of the concepts, and providing control over those representations. Military distributed team training provides a model for virtual reality suitable for cross cultural communication such as negotiation. In both team training and negotiation, the participants must cooperate, agree on a set of goals, and achieve mastery over the concepts being negotiated. Team training technologies suitable for supporting cross cultural negotiation exist (branch wargaming, computer image generation and visualization, distributed simulation), and have developed along different lines than traditional virtual reality technology. Team training de-emphasizes the realism of physiological interfaces between the human and the virtual reality, and emphasizes the interaction of humans with each other and with intelligent simulated agents within the virtual reality. This approach to virtual reality is suggested as being more fruitful for future work.

  8. Amphiphilic Polysaccharide Block Copolymers for pH-Responsive Micellar Nanoparticles.

    PubMed

    Breitenbach, Benjamin B; Schmid, Ira; Wich, Peter R

    2017-09-11

    A full polysaccharide amphiphilic block copolymer was prepared from end group-functionalized dextrans using copper-mediated azide-alkyne click chemistry. Sufficient modification of the reducing end in both blocks was achieved by microwave-enhanced reductive amination in a borate-buffer/methanol solvent system. The combination of a hydrophilic dextran block with a hydrophobic acetalated dextran block results in an amphiphilic structure that turns water-soluble upon acid treatment. The material has a low critical micelle concentration and self-assembles in water to spherical micellar nanoparticles. The formed nanoparticles have a narrow size distribution below 70 nm in diameter and disassemble in slightly acidic conditions. The amphiphilic polysaccharide system shows low toxicity and can stabilize the hydrophobic model drug curcumin in aqueous solutions over extended time periods.

  9. Spectral Analysis within the Virtual Observatory: The GAVO Service TheoSSA

    NASA Astrophysics Data System (ADS)

    Ringat, E.

    2012-03-01

    In the last decade, numerous Virtual Observatory organizations were established. One of these is the German Astrophysical Virtual Observatory (GAVO) that e.g. provides access to spectral energy distributions via the service TheoSSA. In a pilot phase, these are based on the Tübingen NLTE Model-Atmosphere Package (TMAP) and suitable for hot, compact stars. We demonstrate the power of TheoSSA in an application to the sdOB primary of AA Doradus by comparison with a “classical” spectral analysis.

  10. Simulated Tempering Distributed Replica Sampling, Virtual Replica Exchange, and Other Generalized-Ensemble Methods for Conformational Sampling.

    PubMed

    Rauscher, Sarah; Neale, Chris; Pomès, Régis

    2009-10-13

    Generalized-ensemble algorithms in temperature space have become popular tools to enhance conformational sampling in biomolecular simulations. A random walk in temperature leads to a corresponding random walk in potential energy, which can be used to cross over energetic barriers and overcome the problem of quasi-nonergodicity. In this paper, we introduce two novel methods: simulated tempering distributed replica sampling (STDR) and virtual replica exchange (VREX). These methods are designed to address the practical issues inherent in the replica exchange (RE), simulated tempering (ST), and serial replica exchange (SREM) algorithms. RE requires a large, dedicated, and homogeneous cluster of CPUs to function efficiently when applied to complex systems. ST and SREM both have the drawback of requiring extensive initial simulations, possibly adaptive, for the calculation of weight factors or potential energy distribution functions. STDR and VREX alleviate the need for lengthy initial simulations, and for synchronization and extensive communication between replicas. Both methods are therefore suitable for distributed or heterogeneous computing platforms. We perform an objective comparison of all five algorithms in terms of both implementation issues and sampling efficiency. We use disordered peptides in explicit water as test systems, for a total simulation time of over 42 μs. Efficiency is defined in terms of both structural convergence and temperature diffusion, and we show that these definitions of efficiency are in fact correlated. Importantly, we find that ST-based methods exhibit faster temperature diffusion and correspondingly faster convergence of structural properties compared to RE-based methods. Within the RE-based methods, VREX is superior to both SREM and RE. On the basis of our observations, we conclude that ST is ideal for simple systems, while STDR is well-suited for complex systems.

  11. Geospatial-enabled Data Exploration and Computation through Data Infrastructure Building Blocks

    NASA Astrophysics Data System (ADS)

    Song, C. X.; Biehl, L. L.; Merwade, V.; Villoria, N.

    2015-12-01

    Geospatial data are present everywhere today with the proliferation of location-aware computing devices and sensors. This is especially true in the scientific community where large amounts of data are driving research and education activities in many domains. Collaboration over geospatial data, for example, in modeling, data analysis and visualization, must still overcome the barriers of specialized software and expertise among other challenges. The GABBs project aims at enabling broader access to geospatial data exploration and computation by developing spatial data infrastructure building blocks that leverage capabilities of end-to-end application service and virtualized computing framework in HUBzero. Funded by NSF Data Infrastructure Building Blocks (DIBBS) initiative, GABBs provides a geospatial data architecture that integrates spatial data management, mapping and visualization and will make it available as open source. The outcome of the project will enable users to rapidly create tools and share geospatial data and tools on the web for interactive exploration of data without requiring significant software development skills, GIS expertise or IT administrative privileges. This presentation will describe the development of geospatial data infrastructure building blocks and the scientific use cases that help drive the software development, as well as seek feedback from the user communities.

  12. Distributed Pervasive Worlds: The Case of Exergames

    ERIC Educational Resources Information Center

    Laine, Teemu H.; Sedano, Carolina Islas

    2015-01-01

    Pervasive worlds are computing environments where a virtual world converges with the physical world through context-aware technologies such as sensors. In pervasive worlds, technology is distributed among entities that may be distributed geographically. We explore the concept, possibilities, and challenges of distributed pervasive worlds in a case…

  13. A comparative analysis of dynamic grids vs. virtual grids using the A3pviGrid framework.

    PubMed

    Shankaranarayanan, Avinas; Amaldas, Christine

    2010-11-01

    With the proliferation of Quad/Multi-core micro-processors in mainstream platforms such as desktops and workstations; a large number of unused CPU cycles can be utilized for running virtual machines (VMs) as dynamic nodes in distributed environments. Grid services and its service oriented business broker now termed cloud computing could deploy image based virtualization platforms enabling agent based resource management and dynamic fault management. In this paper we present an efficient way of utilizing heterogeneous virtual machines on idle desktops as an environment for consumption of high performance grid services. Spurious and exponential increases in the size of the datasets are constant concerns in medical and pharmaceutical industries due to the constant discovery and publication of large sequence databases. Traditional algorithms are not modeled at handing large data sizes under sudden and dynamic changes in the execution environment as previously discussed. This research was undertaken to compare our previous results with running the same test dataset with that of a virtual Grid platform using virtual machines (Virtualization). The implemented architecture, A3pviGrid utilizes game theoretic optimization and agent based team formation (Coalition) algorithms to improve upon scalability with respect to team formation. Due to the dynamic nature of distributed systems (as discussed in our previous work) all interactions were made local within a team transparently. This paper is a proof of concept of an experimental mini-Grid test-bed compared to running the platform on local virtual machines on a local test cluster. This was done to give every agent its own execution platform enabling anonymity and better control of the dynamic environmental parameters. We also analyze performance and scalability of Blast in a multiple virtual node setup and present our findings. This paper is an extension of our previous research on improving the BLAST application framework

  14. The Virtual Tablet: Virtual Reality as a Control System

    NASA Technical Reports Server (NTRS)

    Chronister, Andrew

    2016-01-01

    In the field of human-computer interaction, Augmented Reality (AR) and Virtual Reality (VR) have been rapidly growing areas of interest and concerted development effort thanks to both private and public research. At NASA, a number of groups have explored the possibilities afforded by AR and VR technology, among which is the IT Advanced Concepts Lab (ITACL). Within ITACL, the AVR (Augmented/Virtual Reality) Lab focuses on VR technology specifically for its use in command and control. Previous work in the AVR lab includes the Natural User Interface (NUI) project and the Virtual Control Panel (VCP) project, which created virtual three-dimensional interfaces that users could interact with while wearing a VR headset thanks to body- and hand-tracking technology. The Virtual Tablet (VT) project attempts to improve on these previous efforts by incorporating a physical surrogate which is mirrored in the virtual environment, mitigating issues with difficulty of visually determining the interface location and lack of tactile feedback discovered in the development of previous efforts. The physical surrogate takes the form of a handheld sheet of acrylic glass with several infrared-range reflective markers and a sensor package attached. Using the sensor package to track orientation and a motion-capture system to track the marker positions, a model of the surrogate is placed in the virtual environment at a position which corresponds with the real-world location relative to the user's VR Head Mounted Display (HMD). A set of control mechanisms is then projected onto the surface of the surrogate such that to the user, immersed in VR, the control interface appears to be attached to the object they are holding. The VT project was taken from an early stage where the sensor package, motion-capture system, and physical surrogate had been constructed or tested individually but not yet combined or incorporated into the virtual environment. My contribution was to combine the pieces of

  15. From telepathology to virtual pathology institution: the new world of digital pathology.

    PubMed

    Kayser, K; Kayser, G; Radziszowski, D; Oehmann, A

    Telepathology has left its childhood. Its technical development is mature, and its use for primary (frozen section) and secondary (expert consultation) diagnosis has been expanded to a great amount. This is in contrast to a virtual pathology laboratory, which is still under technical constraints. Similar to telepathology, which can also be used for e-learning and e-training in pathology, as exemplarily is demonstrated on Digital Lung Pathology (Klaus.Kayser@charite.de) at least two kinds of virtual pathology laboratories will be implemented in the near future: a) those with distributed pathologists and distributed (> or = 1) laboratories associated to individual biopsy stations/surgical theatres, and b) distributed pathologists (usually situated in one institution) and a centralized laboratory, which digitizes complete histological slides. Both scenarios are under intensive technical investigations. The features of virtual pathology comprise a virtual pathology institution (mode a) that accepts a complete case with the patient's history, clinical findings, and (pre-selected) images for first diagnosis. The diagnostic responsibility is that of a conventional institution. The Internet serves as platform for information transfer, and an open server such as the iPATH (http://telepath.patho.unibas.ch) for coordination and performance of the diagnostic procedure. The size and number of transferred images have to be limited, and usual different magnifications have to be used. The sender needs to possess experiences in image sampling techniques, which present with the most significant information. A group of pathologists is "on duty", or selects one member for a predefined duty period. The diagnostic statement of the pathologist(s) on duty is retransmitted to the sender with full responsibility. The first experiences of a virtual pathology institution group working with the iPATH server working with a small hospital of the Salomon islands are promising. A centralized

  16. Virtual agents in a simulated virtual training environment

    NASA Technical Reports Server (NTRS)

    Achorn, Brett; Badler, Norman L.

    1993-01-01

    A drawback to live-action training simulations is the need to gather a large group of participants in order to train a few individuals. One solution to this difficulty is the use of computer-controlled agents in a virtual training environment. This allows a human participant to be replaced by a virtual, or simulated, agent when only limited responses are needed. Each agent possesses a specified set of behaviors and is capable of limited autonomous action in response to its environment or the direction of a human trainee. The paper describes these agents in the context of a simulated hostage rescue training session, involving two human rescuers assisted by three virtual (computer-controlled) agents and opposed by three other virtual agents.

  17. 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

  18. Characterizing the Temporal and Spatial Distribution of Earthquake Swarms in the Puerto Rico - Virgin Island Block

    NASA Astrophysics Data System (ADS)

    Hernandez, F. J.; Lopez, A. M.; Vanacore, E. A.

    2017-12-01

    The presence of earthquake swarms and clusters in the north and northeast of the island of Puerto Rico in the northeastern Caribbean have been recorded by the Puerto Rico Seismic Network (PRSN) since it started operations in 1974. Although clusters in the Puerto Rico-Virgin Island (PRVI) block have been observed for over forty years, the nature of their enigmatic occurrence is still poorly understood. In this study, the entire seismic catalog of the PRSN, of approximately 31,000 seismic events, has been limited to a sub-set of 18,000 events located all along north of Puerto Rico in an effort to characterize and understand the underlying mechanism of these clusters. This research uses two de-clustering methods to identify cluster events in the PRVI block. The first method, known as Model Independent Stochastic Declustering (MISD), filters the catalog sub-set into cluster and background seismic events, while the second method uses a spatio-temporal algorithm applied to the catalog in order to link the separate seismic events into clusters. After using these two methods, identified clusters were classified into either earthquake swarms or seismic sequences. Once identified, each cluster was analyzed to identify correlations against other clusters in their geographic region. Results from this research seek to : (1) unravel their earthquake clustering behavior through the use of different statistical methods and (2) better understand the mechanism for these clustering of earthquakes. Preliminary results have allowed to identify and classify 128 clusters categorized in 11 distinctive regions based on their centers, and their spatio-temporal distribution have been used to determine intra- and interplate dynamics.

  19. ["Habitual" left branch block alternating with 2 "disguised" bracnch block].

    PubMed

    Lévy, S; Jullien, G; Mathieu, P; Mostefa, S; Gérard, R

    1976-10-01

    Two cases of alternating left bundle branch block and "masquerading block" (with left bundle branch morphology in the stnadard leads and right bundle branch block morphology in the precordial leads) were studied by serial tracings and his bundle electrocardiography. In case 1 "the masquerading" block was associated with a first degree AV block related to a prolongation of HV interval. This case is to our knowledge the first cas of alternating bundle branch block in which his bundle activity was recorded in man. In case 2, the patient had atrial fibrilation and His bundle recordings were performed while differents degrees of left bundle branch block were present: The mechanism of the alternation and the concept of "masquerading" block are discussed. It is suggested that this type of block represents a right bundle branch block associated with severe lesions of the "left system".

  20. Spatial organization and drivers of the virtual water trade: a community-structure analysis

    NASA Astrophysics Data System (ADS)

    D'Odorico, Paolo; Carr, Joel; Laio, Francesco; Ridolfi, Luca

    2012-09-01

    The trade of agricultural commodities can be associated with a virtual transfer of the local freshwater resources used for the production of these goods. Thus, trade of food products virtually transfers large amounts of water from areas of food production to far consumption regions, a process termed the ‘globalization of water’. We consider the (time-varying) community structure of the virtual water network for the years 1986-2008. The communities are groups of countries with dense internal connections, while the connections are sparser among different communities. Between 1986 and 2008, the ratio between virtual water flows within communities and the total global trade of virtual water has continuously increased, indicating the existence of well defined clusters of virtual water transfers. In some cases (e.g. Central and North America and Europe in recent years) the virtual water communities correspond to geographically coherent regions, suggesting the occurrence of an ongoing process of regionalization of water resources. However, most communities also include countries located on different ‘sides’ of the world. As such, geographic proximity only partly explains the community structure of virtual water trade. Similarly, the global distribution of people and wealth, whose effect on the virtual water trade is expressed through simple ‘gravity models’, is unable to explain the strength of virtual water communities observed in the past few decades. A gravity model based on the availability of and demand for virtual water in different countries has higher explanatory power, but the drivers of the virtual water fluxes are yet to be adequately identified.

  1. Optimal Regulation of Virtual Power Plants

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dall Anese, Emiliano; Guggilam, Swaroop S.; Simonetto, Andrea

    This paper develops a real-time algorithmic framework for aggregations of distributed energy resources (DERs) in distribution networks to provide regulation services in response to transmission-level requests. Leveraging online primal-dual-type methods for time-varying optimization problems and suitable linearizations of the nonlinear AC power-flow equations, we believe this work establishes the system-theoretic foundation to realize the vision of distribution-level virtual power plants. The optimization framework controls the output powers of dispatchable DERs such that, in aggregate, they respond to automatic-generation-control and/or regulation-services commands. This is achieved while concurrently regulating voltages within the feeder and maximizing customers' and utility's performance objectives. Convergence andmore » tracking capabilities are analytically established under suitable modeling assumptions. Simulations are provided to validate the proposed approach.« less

  2. Evolution-based Virtual Content Insertion with Visually Virtual Interactions in Videos

    NASA Astrophysics Data System (ADS)

    Chang, Chia-Hu; Wu, Ja-Ling

    With the development of content-based multimedia analysis, virtual content insertion has been widely used and studied for video enrichment and multimedia advertising. However, how to automatically insert a user-selected virtual content into personal videos in a less-intrusive manner, with an attractive representation, is a challenging problem. In this chapter, we present an evolution-based virtual content insertion system which can insert virtual contents into videos with evolved animations according to predefined behaviors emulating the characteristics of evolutionary biology. The videos are considered not only as carriers of message conveyed by the virtual content but also as the environment in which the lifelike virtual contents live. Thus, the inserted virtual content will be affected by the videos to trigger a series of artificial evolutions and evolve its appearances and behaviors while interacting with video contents. By inserting virtual contents into videos through the system, users can easily create entertaining storylines and turn their personal videos into visually appealing ones. In addition, it would bring a new opportunity to increase the advertising revenue for video assets of the media industry and online video-sharing websites.

  3. Theft of Virtual Property — Towards Security Requirements for Virtual Worlds

    NASA Astrophysics Data System (ADS)

    Beyer, Anja

    The article is focused to introduce the topic of information technology security for Virtual Worlds to a security experts’ audience. Virtual Worlds are Web 2.0 applications where the users cruise through the world with their individually shaped avatars to find either amusement, challenges or the next best business deal. People do invest a lot of time but beyond they invest in buying virtual assets like fantasy witcheries, wepaons, armour, houses, clothes,...etc with the power of real world money. Although it is called “virtual” (which is often put on the same level as “not existent”) there is a real value behind it. In November 2007 dutch police arrested a seventeen years old teenager who was suspicted to have stolen virtual items in a Virtual World called Habbo Hotel [Reuters07]. In order to successfully provide security mechanisms into Virtual Worlds it is necessarry to fully understand the domain for which the security mechansims are defined. As Virtual Worlds must be clasified into the domain of Social Software the article starts with an overview of how to understand Web 2.0 and gives a short introduction to Virtual Worlds. The article then provides a consideration of assets of Virtual Worlds participants, describes how these assets can be threatened and gives an overview of appopriate security requirements and completes with an outlook of possible countermeasures.

  4. Distributed Learning Metadata Standards

    ERIC Educational Resources Information Center

    McClelland, Marilyn

    2004-01-01

    Significant economies can be achieved in distributed learning systems architected with a focus on interoperability and reuse. The key building blocks of an efficient distributed learning architecture are the use of standards and XML technologies. The goal of plug and play capability among various components of a distributed learning system…

  5. Virtualizing access to scientific applications with the Application Hosting Environment

    NASA Astrophysics Data System (ADS)

    Zasada, S. J.; Coveney, P. V.

    2009-12-01

    The growing power and number of high performance computing resources made available through computational grids present major opportunities as well as a number of challenges to the user. At issue is how these resources can be accessed and how their power can be effectively exploited. In this paper we first present our views on the usability of contemporary high-performance computational resources. We introduce the concept of grid application virtualization as a solution to some of the problems with grid-based HPC usability. We then describe a middleware tool that we have developed to realize the virtualization of grid applications, the Application Hosting Environment (AHE), and describe the features of the new release, AHE 2.0, which provides access to a common platform of federated computational grid resources in standard and non-standard ways. Finally, we describe a case study showing how AHE supports clinical use of whole brain blood flow modelling in a routine and automated fashion. Program summaryProgram title: Application Hosting Environment 2.0 Catalogue identifier: AEEJ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEJ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU Public Licence, Version 2 No. of lines in distributed program, including test data, etc.: not applicable No. of bytes in distributed program, including test data, etc.: 1 685 603 766 Distribution format: tar.gz Programming language: Perl (server), Java (Client) Computer: x86 Operating system: Linux (Server), Linux/Windows/MacOS (Client) RAM: 134 217 728 (server), 67 108 864 (client) bytes Classification: 6.5 External routines: VirtualBox (server), Java (client) Nature of problem: The middleware that makes grid computing possible has been found by many users to be too unwieldy, and presents an obstacle to use rather than providing assistance [1,2]. Such problems are compounded when one attempts to harness the

  6. The architecture of a virtual grid GIS server

    NASA Astrophysics Data System (ADS)

    Wu, Pengfei; Fang, Yu; Chen, Bin; Wu, Xi; Tian, Xiaoting

    2008-10-01

    The grid computing technology provides the service oriented architecture for distributed applications. The virtual Grid GIS server is the distributed and interoperable enterprise application GIS architecture running in the grid environment, which integrates heterogeneous GIS platforms. All sorts of legacy GIS platforms join the grid as members of GIS virtual organization. Based on Microkernel we design the ESB and portal GIS service layer, which compose Microkernel GIS. Through web portals, portal GIS services and mediation of service bus, following the principle of SoC, we separate business logic from implementing logic. Microkernel GIS greatly reduces the coupling degree between applications and GIS platforms. The enterprise applications are independent of certain GIS platforms, and making the application developers to pay attention to the business logic. Via configuration and orchestration of a set of fine-grained services, the system creates GIS Business, which acts as a whole WebGIS request when activated. In this way, the system satisfies a business workflow directly and simply, with little or no new code.

  7. Virtual facebow technique.

    PubMed

    Solaberrieta, Eneko; Garmendia, Asier; Minguez, Rikardo; Brizuela, Aritza; Pradies, Guillermo

    2015-12-01

    This article describes a virtual technique for transferring the location of a digitized cast from the patient to a virtual articulator (virtual facebow transfer). Using a virtual procedure, the maxillary digital cast is transferred to a virtual articulator by means of reverse engineering devices. The following devices necessary to carry out this protocol are available in many contemporary practices: an intraoral scanner, a digital camera, and specific software. Results prove the viability of integrating different tools and software and of completely integrating this procedure into a dental digital workflow. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  8. The Organization and Management of the Virtual Astronomical Observatory

    NASA Technical Reports Server (NTRS)

    Berriman, G. Bruce; Hanisch, Robert J.; Lazio, T. Joseph W.; Szalay, Alexander; Fabbiano, Giussepina

    2012-01-01

    The U.S. Virtual Astronomical Observatory (VAO; http://www.us-vao.org/) has been in operation since May 2010. Its goal is to enable new science through efficient integration of distributed multi-wavelength data. This paper describes the management and organization of the VAO, and emphasizes the techniques used to ensure efficiency in a distributed organization. Management methods include using an annual program plan as the basis for establishing contracts with member organizations, regular communication, and monitoring of processes.

  9. The organization and management of the Virtual Astronomical Observatory

    NASA Astrophysics Data System (ADS)

    Berriman, G. Bruce; Hanisch, Robert J.; Lazio, T. Joseph W.; Szalay, Alexander; Fabbiano, Giuseppina

    2012-09-01

    The U.S. Virtual Astronomical Observatory (VAO; http://www.us-vao.org/) has been in operation since May 2010. Its goal is to enable new science through efficient integration of distributed multi-wavelength data. This paper describes the management and organization of the VAO, and emphasizes the techniques used to ensure efficiency in a distributed organization. Management methods include using an annual program plan as the basis for establishing contracts with member organizations, regular communication, and monitoring of processes.

  10. Virtual Specimens

    NASA Astrophysics Data System (ADS)

    de Paor, D. G.

    2009-12-01

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

  11. Block versus Random Amphiphilic Glycopolymer Nanopaticles as Glucose-Responsive Vehicles.

    PubMed

    Guo, Qianqian; Zhang, Tianqi; An, Jinxia; Wu, Zhongming; Zhao, Yu; Dai, Xiaomei; Zhang, Xinge; Li, Chaoxing

    2015-10-12

    To explore the effect of polymer structure on their self-assembled aggregates and their unique characteristics, this study was devoted to developing a series of amphiphilic block and random phenylboronic acid-based glycopolymers by RAFT polymerization. The amphiphilic glycopolymers were successfully self-assembled into spherically shaped nanoparticles with narrow size distribution in aqueous solution. For block and random copolymers with similar monomer compositions, block copolymer nanoparticles exhibited a more regular transmittance change with the increasing glucose level, while a more evident variation of size and quicker decreasing tendency in I/I0 behavior in different glucose media were observed for random copolymer nanoparticles. Cell viability of all the polymer nanoparticles investigated by MTT assay was higher than 80%, indicating that both block and random copolymers had good cytocompatibility. Insulin could be encapsulated into both nanoparticles, and insulin release rate for random glycopolymer was slightly quicker than that for the block ones. We speculate that different chain conformations between block and random glycopolymers play an important role in self-assembled nanoaggregates and underlying glucose-sensitive behavior.

  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. Real-time, rapidly updating severe weather products for virtual globes

    NASA Astrophysics Data System (ADS)

    Smith, Travis M.; Lakshmanan, Valliappa

    2011-01-01

    It is critical that weather forecasters are able to put severe weather information from a variety of observational and modeling platforms into a geographic context so that warning information can be effectively conveyed to the public, emergency managers, and disaster response teams. The availability of standards for the specification and transport of virtual globe data products has made it possible to generate spatially precise, geo-referenced images and to distribute these centrally created products via a web server to a wide audience. In this paper, we describe the data and methods for enabling severe weather threat analysis information inside a KML framework. The method of creating severe weather diagnosis products that are generated and translating them to KML and image files is described. We illustrate some of the practical applications of these data when they are integrated into a virtual globe display. The availability of standards for interoperable virtual globe clients has not completely alleviated the need for custom solutions. We conclude by pointing out several of the limitations of the general-purpose virtual globe clients currently available.

  14. A Downloadable Three-Dimensional Virtual Model of the Visible Ear

    PubMed Central

    Wang, Haobing; Merchant, Saumil N.; Sorensen, Mads S.

    2008-01-01

    Purpose To develop a three-dimensional (3-D) virtual model of a human temporal bone and surrounding structures. Methods A fresh-frozen human temporal bone was serially sectioned and digital images of the surface of the tissue block were recorded (the ‘Visible Ear’). The image stack was resampled at a final resolution of 50 × 50 × 50/100 µm/voxel, registered in custom software and segmented in PhotoShop® 7.0. The segmented image layers were imported into Amira® 3.1 to generate smooth polygonal surface models. Results The 3-D virtual model presents the structures of the middle, inner and outer ears in their surgically relevant surroundings. It is packaged within a cross-platform freeware, which allows for full rotation, visibility and transparency control, as well as the ability to slice the 3-D model open at any section. The appropriate raw image can be superimposed on the cleavage plane. The model can be downloaded at https://research.meei.harvard.edu/Otopathology/3dmodels/ PMID:17124433

  15. Electrophysiological characterization of 14-benzoyltalatisamine, a selective blocker of the delayed rectifier K+ channel found in virtual screening.

    PubMed

    Song, Ming-Ke; Liu, Hong; Jiang, Hua-Liang; Yue, Jian-Min; Hu, Guo-Yuan

    2006-02-15

    14-Benzoyltalatisamine is a potent and selective blocker of the delayed rectifier K+ channel found in a computational virtual screening study. The compound was found to block the K+ channel from the extracellular side. However, it is unclear whether 14-benzoyltalatisamine shares the same block mechanism with tetraethylammonium (TEA). In order to elucidate how the hit compound found by the virtual screening interacts with the outer vestibule of the K+ channel, the effects of 14-benzoyltalatisamine and TEA on the delayed rectifier K+ current of rat dissociated hippocampal neurons were compared using whole-cell voltage-clamp recording. External application of 14-benzoyltalatisamine and TEA reversibly inhibited the current with IC50 values of 10.1+/-2.2 microM and 1.05+/-0.21 mM, respectively. 14-Benzoyltalatisamine exerted voltage-dependent inhibition, markedly accelerated the decay of the current, and caused a significant hyperpolarizing shift of the steady-state activation curve, whereas TEA caused voltage-independent inhibition, without affecting the kinetic parameters of the current. The blockade by 14-benzoyltalatisamine, but not by TEA, was significantly diminished in a high K+ (60 mM) external solution. The potency of 14-benzoyltalatisamine was markedly reduced in the presence of 15 mM TEA. The results suggest that 14-benzoyltalatisamine bind to the external pore entry of the delayed rectifier K+ channel with partial insertion into the selectivity filter, which is in conformity with that predicted by the molecular docking model in the virtual screening.

  16. Maintaining consistency in distributed systems

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.

    1991-01-01

    In systems designed as assemblies of independently developed components, concurrent access to data or data structures normally arises within individual programs, and is controlled using mutual exclusion constructs, such as semaphores and monitors. Where data is persistent and/or sets of operation are related to one another, transactions or linearizability may be more appropriate. Systems that incorporate cooperative styles of distributed execution often replicate or distribute data within groups of components. In these cases, group oriented consistency properties must be maintained, and tools based on the virtual synchrony execution model greatly simplify the task confronting an application developer. All three styles of distributed computing are likely to be seen in future systems - often, within the same application. This leads us to propose an integrated approach that permits applications that use virtual synchrony with concurrent objects that respect a linearizability constraint, and vice versa. Transactional subsystems are treated as a special case of linearizability.

  17. [Virtual + 1] * Reality

    NASA Astrophysics Data System (ADS)

    Beckhaus, Steffi

    Virtual Reality aims at creating an artificial environment that can be perceived as a substitute to a real setting. Much effort in research and development goes into the creation of virtual environments that in their majority are perceivable only by eyes and hands. The multisensory nature of our perception, however, allows and, arguably, also expects more than that. As long as we are not able to simulate and deliver a fully sensory believable virtual environment to a user, we could make use of the fully sensory, multi-modal nature of real objects to fill in for this deficiency. The idea is to purposefully integrate real artifacts into the application and interaction, instead of dismissing anything real as hindering the virtual experience. The term virtual reality - denoting the goal, not the technology - shifts from a core virtual reality to an “enriched” reality, technologically encompassing both the computer generated and the real, physical artifacts. Together, either simultaneously or in a hybrid way, real and virtual jointly provide stimuli that are perceived by users through their senses and are later formed into an experience by the user's mind.

  18. The communication in industrialised building system (IBS) construction project: Virtual environment

    NASA Astrophysics Data System (ADS)

    Pozin, Mohd Affendi Ahmad; Nawi, Mohd Nasrun Mohd

    2017-10-01

    Large portion of numbers team organization in the IBS construction sector is known are being fragmented. That is contributed from a segregation of construction activity thus create team working in virtually. Virtual team are the nature when teams are working in distributed area, across culture and time. Therefore, teams can be respond to the task without relocating to the site project and settle down a problem through information and communication technology (ICT). The emergence of virtual team are carry out by advancements in communication technologies as a medium to improve project team communication in project delivery process on IBS construction. Based on literature review from previous study and data collected from interviewing, this paper aim to identified communication challenges among project team members according to current project development practices in IBS construction project. Hence, in attempt to develop effective communication through the advantages of virtual team approach for IBS construction project. In order to ensure the data is gathered comprehensively and accurately, the data was collected from project managers by using semi structured interview method. It was found that virtual team approach could be enable competitive challenges on complexity in the construction project management process.

  19. Staghorn: An Automated Large-Scale Distributed System Analysis Platform

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gabert, Kasimir; Burns, Ian; Elliott, Steven

    2016-09-01

    Conducting experiments on large-scale distributed computing systems is becoming significantly easier with the assistance of emulation. Researchers can now create a model of a distributed computing environment and then generate a virtual, laboratory copy of the entire system composed of potentially thousands of virtual machines, switches, and software. The use of real software, running at clock rate in full virtual machines, allows experiments to produce meaningful results without necessitating a full understanding of all model components. However, the ability to inspect and modify elements within these models is bound by the limitation that such modifications must compete with the model,more » either running in or alongside it. This inhibits entire classes of analyses from being conducted upon these models. We developed a mechanism to snapshot an entire emulation-based model as it is running. This allows us to \\freeze time" and subsequently fork execution, replay execution, modify arbitrary parts of the model, or deeply explore the model. This snapshot includes capturing packets in transit and other input/output state along with the running virtual machines. We were able to build this system in Linux using Open vSwitch and Kernel Virtual Machines on top of Sandia's emulation platform Firewheel. This primitive opens the door to numerous subsequent analyses on models, including state space exploration, debugging distributed systems, performance optimizations, improved training environments, and improved experiment repeatability.« less

  20. Epidural block

    MedlinePlus

    ... body. This lessens the pain of contractions during childbirth. An epidural block may also be used to ... extremities. This article focuses on epidural blocks during childbirth. How is the Epidural Given? The block or ...

  1. Closed-loop dialog model of face-to-face communication with a photo-real virtual human

    NASA Astrophysics Data System (ADS)

    Kiss, Bernadette; Benedek, Balázs; Szijárto, Gábor; Takács, Barnabás

    2004-01-01

    We describe an advanced Human Computer Interaction (HCI) model that employs photo-realistic virtual humans to provide digital media users with information, learning services and entertainment in a highly personalized and adaptive manner. The system can be used as a computer interface or as a tool to deliver content to end-users. We model the interaction process between the user and the system as part of a closed loop dialog taking place between the participants. This dialog, exploits the most important characteristics of a face-to-face communication process, including the use of non-verbal gestures and meta communication signals to control the flow of information. Our solution is based on a Virtual Human Interface (VHI) technology that was specifically designed to be able to create emotional engagement between the virtual agent and the user, thus increasing the efficiency of learning and/or absorbing any information broadcasted through this device. The paper reviews the basic building blocks and technologies needed to create such a system and discusses its advantages over other existing methods.

  2. Virtual volatility

    NASA Astrophysics Data System (ADS)

    Silva, A. Christian; Prange, Richard E.

    2007-03-01

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

  3. Exploring the simulation requirements for virtual regional anesthesia training

    NASA Astrophysics Data System (ADS)

    Charissis, V.; Zimmer, C. R.; Sakellariou, S.; Chan, W.

    2010-01-01

    This paper presents an investigation towards the simulation requirements for virtual regional anaesthesia training. To this end we have developed a prototype human-computer interface designed to facilitate Virtual Reality (VR) augmenting educational tactics for regional anaesthesia training. The proposed interface system, aims to compliment nerve blocking techniques methods. The system is designed to operate in real-time 3D environment presenting anatomical information and enabling the user to explore the spatial relation of different human parts without any physical constrains. Furthermore the proposed system aims to assist the trainee anaesthetists so as to build a mental, three-dimensional map of the anatomical elements and their depictive relationship to the Ultra-Sound imaging which is used for navigation of the anaesthetic needle. Opting for a sophisticated approach of interaction, the interface elements are based on simplified visual representation of real objects, and can be operated through haptic devices and surround auditory cues. This paper discusses the challenges involved in the HCI design, introduces the visual components of the interface and presents a tentative plan of future work which involves the development of realistic haptic feedback and various regional anaesthesia training scenarios.

  4. 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…

  5. Structural Genomics: Correlation Blocks, Population Structure, and Genome Architecture

    PubMed Central

    Hu, Xin-Sheng; Yeh, Francis C.; Wang, Zhiquan

    2011-01-01

    An integration of the pattern of genome-wide inter-site associations with evolutionary forces is important for gaining insights into the genomic evolution in natural or artificial populations. Here, we assess the inter-site correlation blocks and their distributions along chromosomes. A correlation block is broadly termed as the DNA segment within which strong correlations exist between genetic diversities at any two sites. We bring together the population genetic structure and the genomic diversity structure that have been independently built on different scales and synthesize the existing theories and methods for characterizing genomic structure at the population level. We discuss how population structure could shape correlation blocks and their patterns within and between populations. Effects of evolutionary forces (selection, migration, genetic drift, and mutation) on the pattern of genome-wide correlation blocks are discussed. In eukaryote organisms, we briefly discuss the associations between the pattern of correlation blocks and genome assembly features in eukaryote organisms, including the impacts of multigene family, the perturbation of transposable elements, and the repetitive nongenic sequences and GC-rich isochores. Our reviews suggest that the observable pattern of correlation blocks can refine our understanding of the ecological and evolutionary processes underlying the genomic evolution at the population level. PMID:21886455

  6. Role of Polyalanine Domains in -Sheet Formation in Spider Silk Block Copolymers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rabotyagova, O.; Cebe, P; Kaplan, D

    2010-01-01

    Genetically engineered spider silk-like block copolymers were studied to determine the influence of polyalanine domain size on secondary structure. The role of polyalanine block distribution on {beta}-sheet formation was explored using FT-IR and WAXS. The number of polyalanine blocks had a direct effect on the formation of crystalline {beta}-sheets, reflected in the change in crystallinity index as the blocks of polyalanines increased. WAXS analysis confirmed the crystalline nature of the sample with the largest number of polyalanine blocks. This approach provides a platform for further exploration of the role of specific amino acid chemistries in regulating the assembly of {beta}-sheetmore » secondary structures, leading to options to regulate material properties through manipulation of this key component in spider silks.« less

  7. Game-Based Virtual Worlds as Decentralized Virtual Activity Systems

    NASA Astrophysics Data System (ADS)

    Scacchi, Walt

    There is widespread interest in the development and use of decentralized systems and virtual world environments as possible new places for engaging in collaborative work activities. Similarly, there is widespread interest in stimulating new technological innovations that enable people to come together through social networking, file/media sharing, and networked multi-player computer game play. A decentralized virtual activity system (DVAS) is a networked computer supported work/play system whose elements and social activities can be both virtual and decentralized (Scacchi et al. 2008b). Massively multi-player online games (MMOGs) such as World of Warcraft and online virtual worlds such as Second Life are each popular examples of a DVAS. Furthermore, these systems are beginning to be used for research, deve-lopment, and education activities in different science, technology, and engineering domains (Bainbridge 2007, Bohannon et al. 2009; Rieber 2005; Scacchi and Adams 2007; Shaffer 2006), which are also of interest here. This chapter explores two case studies of DVASs developed at the University of California at Irvine that employ game-based virtual worlds to support collaborative work/play activities in different settings. The settings include those that model and simulate practical or imaginative physical worlds in different domains of science, technology, or engineering through alternative virtual worlds where players/workers engage in different kinds of quests or quest-like workflows (Jakobsson 2006).

  8. Virtual water balance estimation in Tunisia

    NASA Astrophysics Data System (ADS)

    Stambouli, Talel; Benalaya, Abdallah; Ghezal, Lamia; Ali, Chebil; Hammami, Rifka; Souissi, Asma

    2015-04-01

    The water in Tunisia is limited and unevenly distributed in the different regions, especially in arid zones. In fact, the annual rainfall average varies from less than 100 mm in the extreme South to over 1500 mm in the extreme North of the country. Currently, the conventional potential of water resources of the country is estimated about 4.84 billion m³ / year of which 2.7 billion cubic meters / year of surface water and 2.14 billion cubic meters / year of groundwater, characterizing a structural shortage for water safety in Tunisia (under 500m3/inhabitant/year). With over than 80% of water volumes have been mobilized for agriculture. The virtual water concept, defined by Allan (1997), as the amount of water needed to generate a product of both natural and artificial origin, this concept establish a similarity between product marketing and water trade. Given the influence of water in food production, virtual water studies focus generally on food products. At a global scale, the influence of these product's markets with water management was not seen. Influence has appreciated only by analyzing water-scarce countries, but at the detail level, should be increased, as most studies consider a country as a single geographical point, leading to considerable inaccuracies. The main objective of this work is the virtual water balance estimation of strategic crops in Tunisia (both irrigated and dry crops) to determine their influence on the water resources management and to establish patterns for improving it. The virtual water balance was performed basing on farmer's surveys, crop and meteorological data, irrigation management and regional statistics. Results show that the majority of farmers realize a waste of the irrigation water especially at the vegetable crops and fruit trees. Thus, a good control of the cultural package may result in lower quantities of water used by crops while ensuring good production with a suitable economic profitability. Then, the virtual water

  9. The Tale of Two Virtual Teacher Professional Development Modules

    ERIC Educational Resources Information Center

    Keown, Paul

    2009-01-01

    Virtual communities of practice (VCoP) have been advocated for some time as a promising means of taking professional development to teachers in widely distributed locations. However, geography, and indeed education literature as a whole, contains very few examples where this has been achieved. This paper reports on two VCoP professional…

  10. CPU-GPU mixed implementation of virtual node method for real-time interactive cutting of deformable objects using OpenCL.

    PubMed

    Jia, Shiyu; Zhang, Weizhong; Yu, Xiaokang; Pan, Zhenkuan

    2015-09-01

    Surgical simulators need to simulate interactive cutting of deformable objects in real time. The goal of this work was to design an interactive cutting algorithm that eliminates traditional cutting state classification and can work simultaneously with real-time GPU-accelerated deformation without affecting its numerical stability. A modified virtual node method for cutting is proposed. Deformable object is modeled as a real tetrahedral mesh embedded in a virtual tetrahedral mesh, and the former is used for graphics rendering and collision, while the latter is used for deformation. Cutting algorithm first subdivides real tetrahedrons to eliminate all face and edge intersections, then splits faces, edges and vertices along cutting tool trajectory to form cut surfaces. Next virtual tetrahedrons containing more than one connected real tetrahedral fragments are duplicated, and connectivity between virtual tetrahedrons is updated. Finally, embedding relationship between real and virtual tetrahedral meshes is updated. Co-rotational linear finite element method is used for deformation. Cutting and collision are processed by CPU, while deformation is carried out by GPU using OpenCL. Efficiency of GPU-accelerated deformation algorithm was tested using block models with varying numbers of tetrahedrons. Effectiveness of our cutting algorithm under multiple cuts and self-intersecting cuts was tested using a block model and a cylinder model. Cutting of a more complex liver model was performed, and detailed performance characteristics of cutting, deformation and collision were measured and analyzed. Our cutting algorithm can produce continuous cut surfaces when traditional minimal element creation algorithm fails. Our GPU-accelerated deformation algorithm remains stable with constant time step under multiple arbitrary cuts and works on both NVIDIA and AMD GPUs. GPU-CPU speed ratio can be as high as 10 for models with 80,000 tetrahedrons. Forty to sixty percent real

  11. Wave field synthesis of moving virtual sound sources with complex radiation properties.

    PubMed

    Ahrens, Jens; Spors, Sascha

    2011-11-01

    An approach to the synthesis of moving virtual sound sources with complex radiation properties in wave field synthesis is presented. The approach exploits the fact that any stationary sound source of finite spatial extent radiates spherical waves at sufficient distance. The angular dependency of the radiation properties of the source under consideration is reflected by the amplitude and phase distribution on the spherical wave fronts. The sound field emitted by a uniformly moving monopole source is derived and the far-field radiation properties of the complex virtual source under consideration are incorporated in order to derive a closed-form expression for the loudspeaker driving signal. The results are illustrated via numerical simulations of the synthesis of the sound field of a sample moving complex virtual source.

  12. Main rotor-body action for virtual blades model

    NASA Astrophysics Data System (ADS)

    Kusyumov, Alexander; Kusyumov, Sergey; Mikhailov, Sergey; Romanova, Elena; Phayzullin, Konstantin; Lopatin, Evgeny; Barakos, G.

    2018-06-01

    This research aims to investigate a virtual blade model and assess rotor influence on helicopter fuselage aerodynamics. The rotor disk is discretized in the azimuthal direction, and a time-varied pressure jump is applied in regions occupied by the blades. To obtain the pressure jump, an actuator disk is employed using uniform and non-uniform blade load distribution, based on momentum theory.

  13. Virtual performer: single camera 3D measuring system for interaction in virtual space

    NASA Astrophysics Data System (ADS)

    Sakamoto, Kunio; Taneji, Shoto

    2006-10-01

    The authors developed interaction media systems in the 3D virtual space. In these systems, the musician virtually plays an instrument like the theremin in the virtual space or the performer plays a show using the virtual character such as a puppet. This interactive virtual media system consists of the image capture, measuring performer's position, detecting and recognizing motions and synthesizing video image using the personal computer. In this paper, we propose some applications of interaction media systems; a virtual musical instrument and superimposing CG character. Moreover, this paper describes the measuring method of the positions of the performer, his/her head and both eyes using a single camera.

  14. A digital atlas of breast histopathology: an application of web based virtual microscopy

    PubMed Central

    Lundin, M; Lundin, J; Helin, H; Isola, J

    2004-01-01

    Aims: To develop an educationally useful atlas of breast histopathology, using advanced web based virtual microscopy technology. Methods: By using a robotic microscope and software adopted and modified from the aerial and satellite imaging industry, a virtual microscopy system was developed that allows fully automated slide scanning and image distribution via the internet. More than 150 slides were scanned at high resolution with an oil immersion ×40 objective (numerical aperture, 1.3) and archived on an image server residing in a high speed university network. Results: A publicly available website was constructed, http://www.webmicroscope.net/breastatlas, which features a comprehensive virtual slide atlas of breast histopathology according to the World Health Organisation 2003 classification. Users can view any part of an entire specimen at any magnification within a standard web browser. The virtual slides are supplemented with concise textual descriptions, but can also be viewed without diagnostic information for self assessment of histopathology skills. Conclusions: Using the technology described here, it is feasible to develop clinically and educationally useful virtual microscopy applications. Web based virtual microscopy will probably become widely used at all levels in pathology teaching. PMID:15563669

  15. Creating virtual humans for simulation-based training and planning

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stansfield, S.; Sobel, A.

    1998-05-12

    Sandia National Laboratories has developed a distributed, high fidelity simulation system for training and planning small team Operations. The system provides an immersive environment populated by virtual objects and humans capable of displaying complex behaviors. The work has focused on developing the behaviors required to carry out complex tasks and decision making under stress. Central to this work are techniques for creating behaviors for virtual humans and for dynamically assigning behaviors to CGF to allow scenarios without fixed outcomes. Two prototype systems have been developed that illustrate these capabilities: MediSim, a trainer for battlefield medics and VRaptor, a system formore » planning, rehearsing and training assault operations.« less

  16. Evaluating atmospheric blocking in the global climate model EC-Earth

    NASA Astrophysics Data System (ADS)

    Hartung, Kerstin; Hense, Andreas; Kjellström, Erik

    2013-04-01

    Atmospheric blocking is a phenomenon of the midlatitudal troposphere, which plays an important role in climate variability. Therefore a correct representation of blocking in climate models is necessary, especially for evaluating the results of climate projections. In my master's thesis a validation of blocking in the coupled climate model EC-Earth is performed. Blocking events are detected based on the Tibaldi-Molteni Index. At first, a comparison with the reanalysis dataset ERA-Interim is conducted. The blocking frequency depending on longitude shows a small general underestimation of blocking in the model - a well known problem. Scaife et al. (2011) proposed the correction of model bias as a way to solve this problem. However, applying the correction to the higher resolution EC-Earth model does not yield any improvement. Composite maps show a link between blocking events and surface variables. One example is the formation of a positive surface temperature anomaly north and a negative anomaly south of the blocking anticyclone. In winter the surface temperature in EC-Earth can be reproduced quite well, but in summer a cold bias over the inner-European ocean is present. Using generalized linear models (GLMs) I want to study the connection between regional blocking and global atmospheric variables further. GLMs have the advantage of being applicable to non-Gaussian variables. Therefore the blocking index at each longitude, which is Bernoulli distributed, can be analysed statistically with GLMs. I applied a logistic regression between the blocking index and the geopotential height at 500 hPa to study the teleconnection of blocking events at midlatitudes with global geopotential height. GLMs also offer the possibility of quantifying the connections shown in composite maps. The implementation of the logistic regression can even be expanded to a search for trends in blocking frequency, for example in the scenario simulations.

  17. Using PVM to host CLIPS in distributed environments

    NASA Technical Reports Server (NTRS)

    Myers, Leonard; Pohl, Kym

    1994-01-01

    It is relatively easy to enhance CLIPS (C Language Integrated Production System) to support multiple expert systems running in a distributed environment with heterogeneous machines. The task is minimized by using the PVM (Parallel Virtual Machine) code from Oak Ridge Labs to provide the distributed utility. PVM is a library of C and FORTRAN subprograms that supports distributive computing on many different UNIX platforms. A PVM deamon is easily installed on each CPU that enters the virtual machine environment. Any user with rsh or rexec access to a machine can use the one PVM deamon to obtain a generous set of distributed facilities. The ready availability of both CLIPS and PVM makes the combination of software particularly attractive for budget conscious experimentation of heterogeneous distributive computing with multiple CLIPS executables. This paper presents a design that is sufficient to provide essential message passing functions in CLIPS and enable the full range of PVM facilities.

  18. The art and science of data curation: Lessons learned from constructing a virtual collection

    NASA Astrophysics Data System (ADS)

    Bugbee, Kaylin; Ramachandran, Rahul; Maskey, Manil; Gatlin, Patrick

    2018-03-01

    A digital, or virtual, collection is a value added service developed by libraries that curates information and resources around a topic, theme or organization. Adoption of the virtual collection concept as an Earth science data service improves the discoverability, accessibility and usability of data both within individual data centers but also across data centers and disciplines. In this paper, we introduce a methodology for systematically and rigorously curating Earth science data and information into a cohesive virtual collection. This methodology builds on the geocuration model of searching, selecting and synthesizing Earth science data, metadata and other information into a single and useful collection. We present our experiences curating a virtual collection for one of NASA's twelve Distributed Active Archive Centers (DAACs), the Global Hydrology Resource Center (GHRC), and describe lessons learned as a result of this curation effort. We also provide recommendations and best practices for data centers and data providers who wish to curate virtual collections for the Earth sciences.

  19. Distributed analysis at LHCb

    NASA Astrophysics Data System (ADS)

    Williams, Mike; Egede, Ulrik; Paterson, Stuart; LHCb Collaboration

    2011-12-01

    The distributed analysis experience to date at LHCb has been positive: job success rates are high and wait times for high-priority jobs are low. LHCb users access the grid using the GANGA job-management package, while the LHCb virtual organization manages its resources using the DIRAC package. This clear division of labor has benefitted LHCb and its users greatly; it is a major reason why distributed analysis at LHCb has been so successful. The newly formed LHCb distributed analysis support team has also proved to be a success.

  20. The Virtual Space Telescope: A New Class of Science Missions

    NASA Technical Reports Server (NTRS)

    Shah, Neerav; Calhoun, Philip

    2016-01-01

    Many science investigations proposed by GSFC require two spacecraft alignment across a long distance to form a virtual space telescope. Forming a Virtual Space telescope requires advances in Guidance, Navigation, and Control (GNC) enabling the distribution of monolithic telescopes across multiple space platforms. The capability to align multiple spacecraft to an intertial target is at a low maturity state and we present a roadmap to advance the system-level capability to be flight ready in preparation of various science applications. An engineering proof of concept, called the CANYVAL-X CubeSat MIssion is presented. CANYVAL-X's advancement will decrease risk for a potential starshade mission that would fly with WFIRST.

  1. Phases and Patterns of Group Development in Virtual Learning Teams

    ERIC Educational Resources Information Center

    Yoon, Seung Won; Johnson, Scott D.

    2008-01-01

    With the advancement of Internet communication technologies, distributed work groups have great potential for remote collaboration and use of collective knowledge. Adopting the Complex Adaptive System (CAS) perspective (McGrath, Arrow, & Berdhal, "Personal Soc Psychol Rev" 4 (2000) 95), which views virtual learning teams as an adaptive and…

  2. Using a Virtual Population to Authentically Teach Epidemiology and Biostatistics

    ERIC Educational Resources Information Center

    Dunn, Peter K.; Donnison, Sharn; Cole, Rachel; Bulmer, Michael

    2017-01-01

    Epidemiology is the study of the distribution of disease in human populations. This means that authentically teaching primary data collection in epidemiology is difficult as students cannot easily access suitable human populations. Using an action research methodology, this paper studied the use of a virtual human population (called "The…

  3. Virtual reality intervention for older women with breast cancer.

    PubMed

    Schneider, Susan M; Ellis, Mathew; Coombs, William T; Shonkwiler, Erin L; Folsom, Linda C

    2003-06-01

    This study examined the effects of a virtual reality distraction intervention on chemotherapy-related symptom distress levels in 16 women aged 50 and older. A cross-over design was used to answer the following research questions: (1) Is virtual reality an effective distraction intervention for reducing chemotherapy-related symptom distress levels in older women with breast cancer? (2) Does virtual reality have a lasting effect? Chemotherapy treatments are intensive and difficult to endure. One way to cope with chemotherapy-related symptom distress is through the use of distraction. For this study, a head-mounted display (Sony PC Glasstron PLM - S700) was used to display encompassing images and block competing stimuli during chemotherapy infusions. The Symptom Distress Scale (SDS), Revised Piper Fatigue Scale (PFS), and the State Anxiety Inventory (SAI) were used to measure symptom distress. For two matched chemotherapy treatments, one pre-test and two post-test measures were employed. Participants were randomly assigned to receive the VR distraction intervention during one chemotherapy treatment and received no distraction intervention (control condition) during an alternate chemotherapy treatment. Analysis using paired t-tests demonstrated a significant decrease in the SAI (p = 0.10) scores immediately following chemotherapy treatments when participants used VR. No significant changes were found in SDS or PFS values. There was a consistent trend toward improved symptoms on all measures 48 h following completion of chemotherapy. Evaluation of the intervention indicated that women thought the head mounted device was easy to use, they experienced no cybersickness, and 100% would use VR again.

  4. Virtual Reality Intervention for Older Women with Breast Cancer

    PubMed Central

    SCHNEIDER, SUSAN M.; ELLIS, MATHEW; COOMBS, WILLIAM T.; SHONKWILER, ERIN L.; FOLSOM, LINDA C.

    2013-01-01

    This study examined the effects of a virtual reality distraction intervention on chemotherapy-related symptom distress levels in 16 women aged 50 and older. A cross-over design was used to answer the following research questions: (1) Is virtual reality an effective distraction intervention for reducing chemotherapy-related symptom distress levels in older women with breast cancer? (2) Does virtual reality have a lasting effect? Chemotherapy treatments are intensive and difficult to endure. One way to cope with chemotherapy-related symptom distress is through the use of distraction. For this study, a head-mounted display (Sony PC Glasstron PLM—S700) was used to display encompassing images and block competing stimuli during chemotherapy infusions. The Symptom Distress Scale (SDS), Revised Piper Fatigue Scale (PFS), and the State Anxiety Inventory (SAI) were used to measure symptom distress. For two matched chemotherapy treatments, one pre-test and two post-test measures were employed. Participants were randomly assigned to receive the VR distraction intervention during one chemotherapy treatment and received no distraction intervention (control condition) during an alternate chemotherapy treatment. Analysis using paired t-tests demonstrated a significant decrease in the SAI (p = 0.10) scores immediately following chemotherapy treatments when participants used VR. No significant changes were found in SDS or PFS values. There was a consistent trend toward improved symptoms on all measures 48 h following completion of chemotherapy. Evaluation of the intervention indicated that women thought the head mounted device was easy to use, they experienced no cybersickness, and 100% would use VR again. PMID:12855087

  5. Embodying self-compassion within virtual reality and its effects on patients with depression.

    PubMed

    Falconer, Caroline J; Rovira, Aitor; King, John A; Gilbert, Paul; Antley, Angus; Fearon, Pasco; Ralph, Neil; Slater, Mel; Brewin, Chris R

    2016-01-01

    Self-criticism is a ubiquitous feature of psychopathology and can be combatted by increasing levels of self-compassion. However, some patients are resistant to self-compassion. To investigate whether the effects of self-identification with virtual bodies within immersive virtual reality could be exploited to increase self-compassion in patients with depression. We developed an 8-minute scenario in which 15 patients practised delivering compassion in one virtual body and then experienced receiving it from themselves in another virtual body. In an open trial, three repetitions of this scenario led to significant reductions in depression severity and self-criticism, as well as to a significant increase in self-compassion, from baseline to 4-week follow-up. Four patients showed clinically significant improvement. The results indicate that interventions using immersive virtual reality may have considerable clinical potential and that further development of these methods preparatory to a controlled trial is now warranted. None. © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY) licence.

  6. Inhibitors of Helicobacter pylori Protease HtrA Found by ‘Virtual Ligand’ Screening Combat Bacterial Invasion of Epithelia

    PubMed Central

    Schneider, Petra; Hoy, Benjamin; Wessler, Silja; Schneider, Gisbert

    2011-01-01

    Background The human pathogen Helicobacter pylori (H. pylori) is a main cause for gastric inflammation and cancer. Increasing bacterial resistance against antibiotics demands for innovative strategies for therapeutic intervention. Methodology/Principal Findings We present a method for structure-based virtual screening that is based on the comprehensive prediction of ligand binding sites on a protein model and automated construction of a ligand-receptor interaction map. Pharmacophoric features of the map are clustered and transformed in a correlation vector (‘virtual ligand’) for rapid virtual screening of compound databases. This computer-based technique was validated for 18 different targets of pharmaceutical interest in a retrospective screening experiment. Prospective screening for inhibitory agents was performed for the protease HtrA from the human pathogen H. pylori using a homology model of the target protein. Among 22 tested compounds six block E-cadherin cleavage by HtrA in vitro and result in reduced scattering and wound healing of gastric epithelial cells, thereby preventing bacterial infiltration of the epithelium. Conclusions/Significance This study demonstrates that receptor-based virtual screening with a permissive (‘fuzzy’) pharmacophore model can help identify small bioactive agents for combating bacterial infection. PMID:21483848

  7. STS-88 crew use simulators and virtual reality in preflight training

    NASA Image and Video Library

    1998-04-08

    S98-05075 (8 Apr. 1998) --- Astronaut Nancy J. Currie, assigned as a mission specialist for the mission, uses hardware in the virtual reality lab at the Johnson Space Center (JSC) to train for her duties aboard the Space Shuttle Endeavour. This type computer interface paired with virtual reality training hardware for the assigned space-walking astronauts -- in this case, Jerry L. Ross and James H. Newman -- helps to prepare the entire team for dealing with International Space Station (ISS) elements. One of those elements will be the Functional Cargo Block (FGB), which will have been launched a couple of weeks prior to STS-88. Once the FGB is captured using the Remote Manipulator System (RMS) of the Endeavour, Currie will maneuver the robot arm to dock the FGB to the conical mating adapter at the top of Node 1, to be carried in the Endeavour?s cargo bay. In ensuing days, three Extravehicular Activity?s (EVA) by Ross and Newman will be performed to make power, data and utility connections between the two modules.

  8. Population Blocks.

    ERIC Educational Resources Information Center

    Smith, Martin H.

    1992-01-01

    Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…

  9. Highly Ordered Block Copolymer Templates for the Generation of Nanostructured Materials

    NASA Astrophysics Data System (ADS)

    Bhoje Gowd, E.; Nandan, Bhanu; Bigall, Nadja C.; Eychmuller, Alexander; Stamm, Manfred

    2009-03-01

    Among many different types of self-assembled materials, block copolymers have attracted immense interest for applications in nanotechnology. Block copolymer thin film can be used as a template for patterning of hard inorganic materials such as metal nanoparticles. In the present work, we demonstrate a new approach to fabricate highly ordered arrays of nanoscopic inorganic dots and wires using switchable block copolymer thin films. Various inorganic nanoparticles from a simple aqueous solution were directly deposited on the surface reconstructed block copolymer templates. The preferential interaction of the nanoparticles with one of the blocks is mainly responsible for the lateral distribution of the nanoparticles in addition to the capillary forces. Subsequent stabilization by UV-irradiation followed by pyrolysis in air at 450 ^oC removes the polymer to produce highly ordered metallic nanostructures. This method is highly versatile as the procedure used here is simple, eco-friendly and provides a facile approach to fabricate a broad range of nanoscaled architectures with tunable lateral spacing.

  10. VERSE - Virtual Equivalent Real-time Simulation

    NASA Technical Reports Server (NTRS)

    Zheng, Yang; Martin, Bryan J.; Villaume, Nathaniel

    2005-01-01

    Distributed real-time simulations provide important timing validation and hardware in the- loop results for the spacecraft flight software development cycle. Occasionally, the need for higher fidelity modeling and more comprehensive debugging capabilities - combined with a limited amount of computational resources - calls for a non real-time simulation environment that mimics the real-time environment. By creating a non real-time environment that accommodates simulations and flight software designed for a multi-CPU real-time system, we can save development time, cut mission costs, and reduce the likelihood of errors. This paper presents such a solution: Virtual Equivalent Real-time Simulation Environment (VERSE). VERSE turns the real-time operating system RTAI (Real-time Application Interface) into an event driven simulator that runs in virtual real time. Designed to keep the original RTAI architecture as intact as possible, and therefore inheriting RTAI's many capabilities, VERSE was implemented with remarkably little change to the RTAI source code. This small footprint together with use of the same API allows users to easily run the same application in both real-time and virtual time environments. VERSE has been used to build a workstation testbed for NASA's Space Interferometry Mission (SIM PlanetQuest) instrument flight software. With its flexible simulation controls and inexpensive setup and replication costs, VERSE will become an invaluable tool in future mission development.

  11. Investigation on Consumers’ Behaviour towards Energy Saving through Utilisation of Virtual SED (Smart Energy Displays) in Residential Building

    NASA Astrophysics Data System (ADS)

    Adlisia Puspa Harani, Sandhika

    2018-05-01

    The study is conducted by gathering data from interviews an in-home experiment, to examine the impacts of both virtual and physical SED toward user engagement. Business opportunity and benefits of virtual SED for stake holders are also discussed in this study. The research was conducted by interviewing method to respondens in Nottingham, UK. By comparing consumers’ energy saving behaviour from physical and virtual SED users, virtual SED shows similar level of effectiveness as physical SED, but there is no evidence that the virtual versions are better than the physical ones in terms of reducing energy consumption. Nevertheless, virtual SED can be more beneficial for consumers who can get easier access. They also help educating users to be more concern about energy issue. Energy suppliers get benefits by having virtual versions of SED, in which they can reduce production and distribution costs, as well as diminishing waste from physical SED.

  12. Tyre tread-block friction: modelling, simulation and experimental validation

    NASA Astrophysics Data System (ADS)

    Wallaschek, Jörg; Wies, Burkard

    2013-07-01

    Pneumatic tyres are used in vehicles since the beginning of the last century. They generate braking and steering forces for bicycles, motor cycles, cars, busses, trucks, agricultural vehicles and aircraft. These forces are generated in the usually very small contact area between tyre and road and their performance characteristics are of eminent importance for safety and comfort. Much research has been addressed to optimise tyre design with respect to footprint pressure and friction. In this context, the development of virtual tyre prototypes, that is, simulation models for the tyre, has grown to a science in its own. While the modelling of the structural dynamics of the tyre has reached a very advanced level, which allows to take into account effects like the rate-independent inelasticity of filled elastomers or the transient 3D deformations of the ply-reinforced tread, shoulder and sidewalls, little is known about the friction between tread-block elements and road. This is particularly obvious in the case when snow, ice, water or a third-body layer are present in the tyre-road contact. In the present paper, we give a survey on the present state of knowledge in the modelling, simulation and experimental validation of tyre tread-block friction processes. We concentrate on experimental techniques.

  13. Virtual IED sensor at an rf-biased electrode in low-pressure plasma

    NASA Astrophysics Data System (ADS)

    Bogdanova, Maria; Lopaev, Dmitry; Zyryanov, Sergey; Rakhimov, Alexander

    2016-09-01

    The majority of present-day technologies resort to ion-assisted processes in rf low-pressure plasma. In order to control the process precisely, the energy distribution of ions (IED) bombarding the sample placed on the rf-biased electrode should be tracked. In this work the ``Virtual IED sensor'' concept is considered. The idea is to obtain the IED ``virtually'' from the plasma sheath model including a set of externally measurable discharge parameters. The applicability of the ``Virtual IED sensor'' concept was studied for dual-frequency asymmetric ICP and CCP discharges. The IED measurements were carried out in Ar and H2 plasmas in a wide range of conditions. The calculated IEDs were compared to those measured by the Retarded Field Energy Analyzer. To calibrate the ``Virtual IED sensor'', the ion flux was measured by the pulsed self-bias method and then compared to plasma density measurements by Langmuir and hairpin probes. It is shown that if there is a reliable calibration procedure, the ``Virtual IED sensor'' can be successfully realized on the basis of analytical and semianalytical plasma sheath models including measurable discharge parameters. This research is supported by Russian Science Foundation (RSF) Grant 14-12-01012.

  14. Studies of the field-of-view resolution tradeoff in virtual-reality systems

    NASA Technical Reports Server (NTRS)

    Piantanida, Thomas P.; Boman, Duane; Larimer, James; Gille, Jennifer; Reed, Charles

    1992-01-01

    Most virtual-reality systems use LCD-based displays that achieve a large field-of-view at the expense of resolution. A typical display will consist of approximately 86,000 pixels uniformly distributed over an 80-degree by 60-degree image. Thus, each pixel subtends about 13 minutes of arc at the retina; about the same as the resolvable features of the 20/200 line of a Snellen Eye Chart. The low resolution of LCD-based systems limits task performance in some applications. We have examined target-detection performance in a low-resolution virtual world. Our synthesized three-dimensional virtual worlds consisted of target objects that could be positioned at a fixed distance from the viewer, but at random azimuth and constrained elevation. A virtual world could be bounded by chromatic walls or by wire-frame, or it could be unbounded. Viewers scanned these worlds and indicated by appropriate gestures when they had detected the target object. By manipulating the viewer's field size and the chromatic and luminance contrast of annuli surrounding the field-of-view, we were able to assess the effect of field size on the detection of virtual objects in low-resolution synthetic worlds.

  15. The Virtual Climate Data Server (vCDS): An iRODS-Based Data Management Software Appliance Supporting Climate Data Services and Virtualization-as-a-Service in the NASA Center for Climate Simulation

    NASA Technical Reports Server (NTRS)

    Schnase, John L.; Tamkin, Glenn S.; Ripley, W. David III; Stong, Savannah; Gill, Roger; Duffy, Daniel Q.

    2012-01-01

    Scientific data services are becoming an important part of the NASA Center for Climate Simulation's mission. Our technological response to this expanding role is built around the concept of a Virtual Climate Data Server (vCDS), repetitive provisioning, image-based deployment and distribution, and virtualization-as-a-service. The vCDS is an iRODS-based data server specialized to the needs of a particular data-centric application. We use RPM scripts to build vCDS images in our local computing environment, our local Virtual Machine Environment, NASA s Nebula Cloud Services, and Amazon's Elastic Compute Cloud. Once provisioned into one or more of these virtualized resource classes, vCDSs can use iRODS s federation capabilities to create an integrated ecosystem of managed collections that is scalable and adaptable to changing resource requirements. This approach enables platform- or software-asa- service deployment of vCDS and allows the NCCS to offer virtualization-as-a-service: a capacity to respond in an agile way to new customer requests for data services.

  16. View of cell block eight (left), cell block seven, and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of cell block eight (left), cell block seven, and southwest guard tower, looking from cell block eight roof - Eastern State Penitentiary, 2125 Fairmount Avenue, Philadelphia, Philadelphia County, PA

  17. Cell block eleven (left) and cell block fifteen, looking from ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Cell block eleven (left) and cell block fifteen, looking from cell block two into the "Death Row" exercise yard - Eastern State Penitentiary, 2125 Fairmount Avenue, Philadelphia, Philadelphia County, PA

  18. Analysis of scalability of high-performance 3D image processing platform for virtual colonoscopy

    NASA Astrophysics Data System (ADS)

    Yoshida, Hiroyuki; Wu, Yin; Cai, Wenli

    2014-03-01

    One of the key challenges in three-dimensional (3D) medical imaging is to enable the fast turn-around time, which is often required for interactive or real-time response. This inevitably requires not only high computational power but also high memory bandwidth due to the massive amount of data that need to be processed. For this purpose, we previously developed a software platform for high-performance 3D medical image processing, called HPC 3D-MIP platform, which employs increasingly available and affordable commodity computing systems such as the multicore, cluster, and cloud computing systems. To achieve scalable high-performance computing, the platform employed size-adaptive, distributable block volumes as a core data structure for efficient parallelization of a wide range of 3D-MIP algorithms, supported task scheduling for efficient load distribution and balancing, and consisted of a layered parallel software libraries that allow image processing applications to share the common functionalities. We evaluated the performance of the HPC 3D-MIP platform by applying it to computationally intensive processes in virtual colonoscopy. Experimental results showed a 12-fold performance improvement on a workstation with 12-core CPUs over the original sequential implementation of the processes, indicating the efficiency of the platform. Analysis of performance scalability based on the Amdahl's law for symmetric multicore chips showed the potential of a high performance scalability of the HPC 3DMIP platform when a larger number of cores is available.

  19. The development of a micro-shunt made from poly(styrene-block-isobutylene-block-styrene) to treat glaucoma.

    PubMed

    Pinchuk, Leonard; Riss, Isabelle; Batlle, Juan F; Kato, Yasushi P; Martin, John B; Arrieta, Esdras; Palmberg, Paul; Parrish, Richard K; Weber, Bruce A; Kwon, Yongmoon; Parel, Jean-Marie

    2017-01-01

    Glaucoma is the second leading cause of blindness with ∼70 million people worldwide who are blind from this disease. The currently practiced trabeculectomy surgery, the gold standard treatment used to stop the progression of vision loss, is rather draconian, traumatic to the patient and requires much surgical skill to perform. This article summarizes the more than 10-year development path of a novel device called the InnFocus MicroShunt®, which is a minimally invasive glaucoma drainage micro-tube used to shunt aqueous humor from the anterior chamber of the eye to a flap formed under the conjunctiva and Tenon's Capsule. The safety and clinical performance of this device approaches that of trabeculectomy. The impetus to develop this device stemmed from the invention of a new biomaterial called poly(styrene-block-isobutylene-block-styrene), or "SIBS." SIBS is ultra-stable with virtually no foreign body reaction in the body, which manifests in the eye as clinically insignificant inflammation and capsule formation. The quest for an easier, safer, and more effective method of treating glaucoma led to the marriage of SIBS with this glaucoma drainage micro-tube. This article summarizes the development of SIBS and the subsequent three iterations of design and four clinical trials that drove the one-year qualified success rate of the device from 43% to 100%. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 211-221, 2017. © 2015 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

  20. Creating Virtual-hand and Virtual-face Illusions to Investigate Self-representation

    PubMed Central

    Ma, Ke; Lippelt, Dominique P.; Hommel, Bernhard

    2017-01-01

    Studies investigating how people represent themselves and their own body often use variants of "ownership illusions", such as the traditional rubber-hand illusion or the more recently discovered enfacement illusion. However, these examples require rather artificial experimental setups, in which the artificial effector needs to be stroked in synchrony with the participants' real hand or face—a situation in which participants have no control over the stroking or the movements of their real or artificial effector. Here, we describe a technique to establish ownership illusions in a setup that is more realistic, more intuitive, and of presumably higher ecological validity. It allows creating the virtual-hand illusion by having participants control the movements of a virtual hand presented on a screen or in virtual space in front of them. If the virtual hand moves in synchrony with the participants' own real hand, they tend to perceive the virtual hand as part of their own body. The technique also creates the virtual-face illusion by having participants control the movements of a virtual face in front of them, again with the effect that they tend to perceive the face as their own if it moves in synchrony with their real face. Studying the circumstances that illusions of this sort can be created, increased, or reduced provides important information about how people create and maintain representations of themselves. PMID:28287602

  1. Recent evolution of China's virtual water trade: analysis of selected crops and considerations for policy

    NASA Astrophysics Data System (ADS)

    Shi, J.; Liu, J.; Pinter, L.

    2013-09-01

    China has dramatically increased its virtual water import unconsciously for recent years. Many studies have focused on the quantity of traded virtual water but very few go into analysing geographic distribution and the properties of China's virtual water trade network. This paper provides a calculation and analysis of the crop-related virtual water trade network of China based on 27 major primary crops between 1986 and 2009. The results show that China is a net importer of virtual water from water-abundant areas of North and South America, and a net virtual water exporter to water-stressed areas of Asia, Africa, and Europe. Virtual water import is far larger than virtual water export and in both import and export a small number of trade partners control the supply chain. Grain crops are the major contributors to virtual water trade, and among grain crops soybeans, mostly imported from the US, Brazil and Argentina are the most significant. As crop yield and crop water productivity in North and South America are generally higher than those in Asia and Africa, the effect of China's crop-related virtual water trade positively contributes to optimizing crop water use efficiency at the global scale. In order to mitigate water scarcity and secure the food supply, virtual water should be actively incorporated into national water management strategies. From the national perspective, China should reduce the export and increase the import of water-intensive crops. But the sources of virtual water import need to be further diversified to reduce supply chain risks and increase resilience.

  2. Second diastolic pulmonary venous flow and isolated late diastolic mitral valve regurgitation in first-degree atrioventricular block.

    PubMed

    Leibundgut, Gregor; Bernheim, Alain M

    2010-04-01

    The authors report the case of a 77-year-old male patient with sinus rhythm and a first-degree atrioventricular (AV) block who was referred for echocardiographic follow-up 18 years after aortic valve replacement. Left ventricular systolic function as well as the function of the aortic prosthesis was normal. Systolic mitral regurgitation (MR) was virtually absent, but isolated late diastolic MR was detected by colour Doppler imaging. Coincidental to the occurrence of diastolic MR, a second late diastolic forward flow in the pulmonary veins was observed. Therefore, during the prolonged left atrial relaxation caused by first-degree AV block, the left atrial pressure drops below the pressure in both adjacent chambers in late diastole, resulting in both late diastolic MR and a second diastolic pulmonary venous forward flow.

  3. SmallTool - a toolkit for realizing shared virtual environments on the Internet

    NASA Astrophysics Data System (ADS)

    Broll, Wolfgang

    1998-09-01

    With increasing graphics capabilities of computers and higher network communication speed, networked virtual environments have become available to a large number of people. While the virtual reality modelling language (VRML) provides users with the ability to exchange 3D data, there is still a lack of appropriate support to realize large-scale multi-user applications on the Internet. In this paper we will present SmallTool, a toolkit to support shared virtual environments on the Internet. The toolkit consists of a VRML-based parsing and rendering library, a device library, and a network library. This paper will focus on the networking architecture, provided by the network library - the distributed worlds transfer and communication protocol (DWTP). DWTP provides an application-independent network architecture to support large-scale multi-user environments on the Internet.

  4. Virtual data

    NASA Astrophysics Data System (ADS)

    Bjorklund, E.

    1994-12-01

    In the 1970s, when computers were memory limited, operating system designers created the concept of "virtual memory", which gave users the ability to address more memory than physically existed. In the 1990s, many large control systems have the potential of becoming data limited. We propose that many of the principles behind virtual memory systems (working sets, locality, caching and clustering) can also be applied to data-limited systems, creating, in effect, "virtual data systems". At the Los Alamos National Laboratory's Clinton P. Anderson Meson Physics Facility (LAMPF), we have applied these principles to a moderately sized (10 000 data points) data acquisition and control system. To test the principles, we measured the system's performance during tune-up, production, and maintenance periods. In this paper, we present a general discussion of the principles of a virtual data system along with some discussion of our own implementation and the results of our performance measurements.

  5. A graph-based approach to construct target-focused libraries for virtual screening.

    PubMed

    Naderi, Misagh; Alvin, Chris; Ding, Yun; Mukhopadhyay, Supratik; Brylinski, Michal

    2016-01-01

    Due to exorbitant costs of high-throughput screening, many drug discovery projects commonly employ inexpensive virtual screening to support experimental efforts. However, the vast majority of compounds in widely used screening libraries, such as the ZINC database, will have a very low probability to exhibit the desired bioactivity for a given protein. Although combinatorial chemistry methods can be used to augment existing compound libraries with novel drug-like compounds, the broad chemical space is often too large to be explored. Consequently, the trend in library design has shifted to produce screening collections specifically tailored to modulate the function of a particular target or a protein family. Assuming that organic compounds are composed of sets of rigid fragments connected by flexible linkers, a molecule can be decomposed into its building blocks tracking their atomic connectivity. On this account, we developed eSynth, an exhaustive graph-based search algorithm to computationally synthesize new compounds by reconnecting these building blocks following their connectivity patterns. We conducted a series of benchmarking calculations against the Directory of Useful Decoys, Enhanced database. First, in a self-benchmarking test, the correctness of the algorithm is validated with the objective to recover a molecule from its building blocks. Encouragingly, eSynth can efficiently rebuild more than 80 % of active molecules from their fragment components. Next, the capability to discover novel scaffolds is assessed in a cross-benchmarking test, where eSynth successfully reconstructed 40 % of the target molecules using fragments extracted from chemically distinct compounds. Despite an enormous chemical space to be explored, eSynth is computationally efficient; half of the molecules are rebuilt in less than a second, whereas 90 % take only about a minute to be generated. eSynth can successfully reconstruct chemically feasible molecules from molecular fragments

  6. Fiberglass distribution poles: A case study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miller, M.F.; Hosford, G.S.; Boozer, J.F. III

    1995-01-01

    This paper addresses the design considerations and manufacturing techniques along with mechanical test results of fiberglass reinforced composite (FRC) primary distribution poles. With it`s light weight, and virtually no maintenance it offers a viable alternative for use in remote and inaccessible locations. This paper also discusses a case study where seventy five FRC primary distribution poles have been installed on a distribution system in a remote area accessible only by foot and helicopter.

  7. The Breakdown: Hillslope Sources of Channel Blocks in Bedrock Landscapes

    NASA Astrophysics Data System (ADS)

    Selander, B.; Anderson, S. P.; Rossi, M.

    2017-12-01

    Block delivery from hillslopes is a poorly understood process that influences bedrock channel incision rates and shapes steep terrain. Previous studies demonstrate that hillslope sediment delivery rate and grain size increases with channel downcutting rate or fracture density (Attal et al., 2015, ESurf). However, blocks that exceed the competence of the channel can inhibit incision. In Boulder Creek, a bedrock channel in the Colorado Front Range, large boulders (>1 m diameter) are most numerous in the steepest channel reaches; their distribution seems to reflect autogenic channel-hillslope feedback between incision rate and block delivery (Shobe et al., 2016, GRL). It is clear that the processes, rates of production, and delivery of large blocks from hillslopes into channels are critical to our understanding of steep terrain evolution. Fundamental questions are 1) whether block production or block delivery is rate limiting, 2) what mechanisms release blocks, and 3) how block production and transport affect slope morphology. As a first step, we map rock outcrops on the granodiorite hillslopes lining Boulder Creek within Boulder Canyon using a high resolution DEM. Our algorithm uses high ranges of curvature values in conjunction with slopes steeper than the angle of repose to quickly identify rock outcrops. We field verified mapped outcrop and sediment-mantled locations on hillslopes above and below the channel knickzone. We find a greater abundance of exposed rock outcrops on steeper hillslopes in Boulder Canyon. Additionally, we find that channel reaches with large in-channel blocks are located at the base of hillslopes with large areas of exposed bedrock, while reaches lacking large in-channel blocks tend to be at the base of predominately soil mantled and forested hillslopes. These observations support the model of block delivery and channel incision of Shobe et al. (2016, GRL). Moreover, these results highlight the conundrum of how rapid channel incision is

  8. Block LU factorization

    NASA Technical Reports Server (NTRS)

    Demmel, James W.; Higham, Nicholas J.; Schreiber, Robert S.

    1992-01-01

    Many of the currently popular 'block algorithms' are scalar algorithms in which the operations have been grouped and reordered into matrix operations. One genuine block algorithm in practical use is block LU factorization, and this has recently been shown by Demmel and Higham to be unstable in general. It is shown here that block LU factorization is stable if A is block diagonally dominant by columns. Moreover, for a general matrix the level of instability in block LU factorization can be founded in terms of the condition number kappa(A) and the growth factor for Gaussian elimination without pivoting. A consequence is that block LU factorization is stable for a matrix A that is symmetric positive definite or point diagonally dominant by rows or columns as long as A is well-conditioned.

  9. Virtual Facility at Fermilab: Infrastructure and Services Expand to Public Clouds

    DOE PAGES

    Timm, Steve; Garzoglio, Gabriele; Cooper, Glenn; ...

    2016-02-18

    In preparation for its new Virtual Facility Project, Fermilab has launched a program of work to determine the requirements for running a computation facility on-site, in public clouds, or a combination of both. This program builds on the work we have done to successfully run experimental workflows of 1000-VM scale both on an on-site private cloud and on Amazon AWS. To do this at scale we deployed dynamically launched and discovered caching services on the cloud. We are now testing the deployment of more complicated services on Amazon AWS using native load balancing and auto scaling features they provide. Themore » Virtual Facility Project will design and develop a facility including infrastructure and services that can live on the site of Fermilab, off-site, or a combination of both. We expect to need this capacity to meet the peak computing requirements in the future. The Virtual Facility is intended to provision resources on the public cloud on behalf of the facility as a whole instead of having each experiment or Virtual Organization do it on their own. We will describe the policy aspects of a distributed Virtual Facility, the requirements, and plans to make a detailed comparison of the relative cost of the public and private clouds. Furthermore, this talk will present the details of the technical mechanisms we have developed to date, and the plans currently taking shape for a Virtual Facility at Fermilab.« less

  10. Virtual Facility at Fermilab: Infrastructure and Services Expand to Public Clouds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Timm, Steve; Garzoglio, Gabriele; Cooper, Glenn

    In preparation for its new Virtual Facility Project, Fermilab has launched a program of work to determine the requirements for running a computation facility on-site, in public clouds, or a combination of both. This program builds on the work we have done to successfully run experimental workflows of 1000-VM scale both on an on-site private cloud and on Amazon AWS. To do this at scale we deployed dynamically launched and discovered caching services on the cloud. We are now testing the deployment of more complicated services on Amazon AWS using native load balancing and auto scaling features they provide. Themore » Virtual Facility Project will design and develop a facility including infrastructure and services that can live on the site of Fermilab, off-site, or a combination of both. We expect to need this capacity to meet the peak computing requirements in the future. The Virtual Facility is intended to provision resources on the public cloud on behalf of the facility as a whole instead of having each experiment or Virtual Organization do it on their own. We will describe the policy aspects of a distributed Virtual Facility, the requirements, and plans to make a detailed comparison of the relative cost of the public and private clouds. Furthermore, this talk will present the details of the technical mechanisms we have developed to date, and the plans currently taking shape for a Virtual Facility at Fermilab.« less

  11. Block Transfer Handbook: Constructing and Negotiating Block Transfer Agreements.

    ERIC Educational Resources Information Center

    Finlay, Finola

    The purpose of this handbook is to provide resources for institutions or articulation committees who are engaged in the task of investigating the feasibility of block transfer agreements. Block transfer is the process whereby a block of credits is granted to students who have successfully completed a certificate, diploma, or cluster of courses…

  12. Accuracy Analysis on Large Blocks of High Resolution Images

    NASA Technical Reports Server (NTRS)

    Passini, Richardo M.

    2007-01-01

    Although high altitude frequencies effects are removed at the time of basic image generation, low altitude (Yaw) effects are still present in form of affinity/angular affinity. They are effectively removed by additional parameters. Bundle block adjustment based on properly weighted ephemeris/altitude quaternions (BBABEQ) are not enough to remove the systematic effect. Moreover, due to the narrow FOV of the HRSI, position and altitude are highly correlated making it almost impossible to separate and remove their systematic effects without extending the geometric model (Self-Calib.) The systematic effects gets evident on the increase of accuracy (in terms of RMSE at GCPs) for looser and relaxed ground control at the expense of large and strong block deformation with large residuals at check points. Systematic errors are most freely distributed and their effects propagated all over the block.

  13. Virtualized Networks and Virtualized Optical Line Terminal (vOLT)

    NASA Astrophysics Data System (ADS)

    Ma, Jonathan; Israel, Stephen

    2017-03-01

    The success of the Internet and the proliferation of the Internet of Things (IoT) devices is forcing telecommunications carriers to re-architecture a central office as a datacenter (CORD) so as to bring the datacenter economics and cloud agility to a central office (CO). The Open Network Operating System (ONOS) is the first open-source software-defined network (SDN) operating system which is capable of managing and controlling network, computing, and storage resources to support CORD infrastructure and network virtualization. The virtualized Optical Line Termination (vOLT) is one of the key components in such virtualized networks.

  14. Using virtual machine monitors to overcome the challenges of monitoring and managing virtualized cloud infrastructures

    NASA Astrophysics Data System (ADS)

    Bamiah, Mervat Adib; Brohi, Sarfraz Nawaz; Chuprat, Suriayati

    2012-01-01

    Virtualization is one of the hottest research topics nowadays. Several academic researchers and developers from IT industry are designing approaches for solving security and manageability issues of Virtual Machines (VMs) residing on virtualized cloud infrastructures. Moving the application from a physical to a virtual platform increases the efficiency, flexibility and reduces management cost as well as effort. Cloud computing is adopting the paradigm of virtualization, using this technique, memory, CPU and computational power is provided to clients' VMs by utilizing the underlying physical hardware. Beside these advantages there are few challenges faced by adopting virtualization such as management of VMs and network traffic, unexpected additional cost and resource allocation. Virtual Machine Monitor (VMM) or hypervisor is the tool used by cloud providers to manage the VMs on cloud. There are several heterogeneous hypervisors provided by various vendors that include VMware, Hyper-V, Xen and Kernel Virtual Machine (KVM). Considering the challenge of VM management, this paper describes several techniques to monitor and manage virtualized cloud infrastructures.

  15. 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.

  16. Perception of Virtual Audiences.

    PubMed

    Chollet, Mathieu; Scherer, Stefan

    2017-01-01

    A growing body of evidence shows that virtual audiences are a valuable tool in the treatment of social anxiety, and recent works show that it also a useful in public-speaking training programs. However, little research has focused on how such audiences are perceived and on how the behavior of virtual audiences can be manipulated to create various types of stimuli. The authors used a crowdsourcing methodology to create a virtual audience nonverbal behavior model and, with it, created a dataset of videos with virtual audiences containing varying behaviors. Using this dataset, they investigated how virtual audiences are perceived and which factors affect this perception.

  17. A virtual test system representing the distribution of pedestrian impact configurations for future vehicle front-end optimization.

    PubMed

    Li, Guibing; Yang, Jikuang; Simms, Ciaran

    2016-07-03

    The purpose of this study is to define a computationally efficient virtual test system (VTS) to assess the aggressivity of vehicle front-end designs to pedestrians considering the distribution of pedestrian impact configurations for future vehicle front-end optimization. The VTS should represent real-world impact configurations in terms of the distribution of vehicle impact speeds, pedestrian walking speeds, pedestrian gait, and pedestrian height. The distribution of injuries as a function of body region, vehicle impact speed, and pedestrian size produced using this VTS should match the distribution of injuries observed in the accident data. The VTS should have the predictive ability to distinguish the aggressivity of different vehicle front-end designs to pedestrians. The proposed VTS includes 2 parts: a simulation test sample (STS) and an injury weighting system (IWS). The STS was defined based on MADYMO multibody vehicle to pedestrian impact simulations accounting for the range of vehicle impact speeds, pedestrian heights, pedestrian gait, and walking speed to represent real world impact configurations using the Pedestrian Crash Data Study (PCDS) and anthropometric data. In total 1,300 impact configurations were accounted for in the STS. Three vehicle shapes were then tested using the STS. The IWS was developed to weight the predicted injuries in the STS using the estimated proportion of each impact configuration in the PCDS accident data. A weighted injury number (WIN) was defined as the resulting output of the VTS. The WIN is the weighted number of average Abbreviated Injury Scale (AIS) 2+ injuries recorded per impact simulation in the STS. Then the predictive capability of the VTS was evaluated by comparing the distributions of AIS 2+ injuries to different pedestrian body regions and heights, as well as vehicle types and impact speeds, with that from the PCDS database. Further, a parametric analysis was performed with the VTS to assess the sensitivity of the

  18. European temperature responses to blocking and ridge regional patterns

    NASA Astrophysics Data System (ADS)

    Sousa, Pedro M.; Trigo, Ricardo M.; Barriopedro, David; Soares, Pedro M. M.; Santos, João A.

    2018-01-01

    Blocking occurrence and its impacts on European temperature have been studied in the last decade. However, most previous studies on blocking impacts have focused on winter only, disregarding its fingerprint in summer and differences with other synoptic patterns that also trigger temperature extremes. In this work, we provide a clear distinction between high-latitude blocking and sub-tropical ridges occurring in three sectors of the Euro-Atlantic region, describing their climatology and consequent impacts on European temperature during both winter and summer. Winter blocks (ridges) are generally associated to colder (warmer) than average conditions over large regions of Europe, in some areas with anomalies larger than 5 °C, particularly for the patterns occurring in the Atlantic and Central European sectors. During summer, there is a more regional response characterized by above average temperature for both blocking and ridge patterns, especially those occurring in continental areas, although negative temperature anomalies persist in southernmost areas during blocking. An objective analysis of the different forcing mechanisms associated to each considered weather regime has been performed, quantifying the importance of the following processes in causing the temperature anomalies: horizontal advection, vertical advection and diabatic heating. While during winter advection processes tend to be more relevant to explain temperature responses, in summer radiative heating under enhanced insolation plays a crucial role for both blocking and ridges. Finally, the changes in the distributions of seasonal temperature and in the frequencies of extreme temperature indices were also examined for specific areas of Europe. Winter blocking and ridge patterns are key drivers in the occurrence of regional cold and warm extreme temperatures, respectively. In summer, they are associated with substantial changes in the frequency of extremely warm days, but with different signatures in

  19. Statistical molecular design of building blocks for combinatorial chemistry.

    PubMed

    Linusson, A; Gottfries, J; Lindgren, F; Wold, S

    2000-04-06

    The reduction of the size of a combinatorial library can be made in two ways, either base the selection on the building blocks (BB's) or base it on the full set of virtually constructed products. In this paper we have investigated the effects of applying statistical designs to BB sets compared to selections based on the final products. The two sets of BB's and the virtually constructed library were described by structural parameters, and the correlation between the two characterizations was investigated. Three different selection approaches were used both for the BB sets and for the products. In the first two the selection algorithms were applied directly to the data sets (D-optimal design and space-filling design), while for the third a cluster analysis preceded the selection (cluster-based design). The selections were compared using visual inspection, the Tanimoto coefficient, the Euclidean distance, the condition number, and the determinant of the resulting data matrix. No difference in efficiency was found between selections made in the BB space and in the product space. However, it is of critical importance to investigate the BB space carefully and to select an appropriate number of BB's to result in an adequate diversity. An example from the pharmaceutical industry is then presented, where selection via BB's was made using a cluster-based design.

  20. THE VIRTUAL INSTRUMENT: SUPPORT FOR GRID-ENABLED MCELL SIMULATIONS

    PubMed Central

    Casanova, Henri; Berman, Francine; Bartol, Thomas; Gokcay, Erhan; Sejnowski, Terry; Birnbaum, Adam; Dongarra, Jack; Miller, Michelle; Ellisman, Mark; Faerman, Marcio; Obertelli, Graziano; Wolski, Rich; Pomerantz, Stuart; Stiles, Joel

    2010-01-01

    Ensembles of widely distributed, heterogeneous resources, or Grids, have emerged as popular platforms for large-scale scientific applications. In this paper we present the Virtual Instrument project, which provides an integrated application execution environment that enables end-users to run and interact with running scientific simulations on Grids. This work is performed in the specific context of MCell, a computational biology application. While MCell provides the basis for running simulations, its capabilities are currently limited in terms of scale, ease-of-use, and interactivity. These limitations preclude usage scenarios that are critical for scientific advances. Our goal is to create a scientific “Virtual Instrument” from MCell by allowing its users to transparently access Grid resources while being able to steer running simulations. In this paper, we motivate the Virtual Instrument project and discuss a number of relevant issues and accomplishments in the area of Grid software development and application scheduling. We then describe our software design and report on the current implementation. We verify and evaluate our design via experiments with MCell on a real-world Grid testbed. PMID:20689618

  1. Nomad devices for interactions in immersive virtual environments

    NASA Astrophysics Data System (ADS)

    George, Paul; Kemeny, Andras; Merienne, Frédéric; Chardonnet, Jean-Rémy; Thouvenin, Indira Mouttapa; Posselt, Javier; Icart, Emmanuel

    2013-03-01

    Renault is currently setting up a new CAVE™, a 5 rear-projected wall virtual reality room with a combined 3D resolution of 100 Mpixels, distributed over sixteen 4k projectors and two 2k projector as well as an additional 3D HD collaborative powerwall. Renault's CAVE™ aims at answering needs of the various vehicle conception steps [1]. Starting from vehicle Design, through the subsequent Engineering steps, Ergonomic evaluation and perceived quality control, Renault has built up a list of use-cases and carried out an early software evaluation in the four sided CAVE™ of Institute Image, called MOVE. One goal of the project is to study interactions in a CAVE™, especially with nomad devices such as IPhone or IPad to manipulate virtual objects and to develop visualization possibilities. Inspired by nomad devices current uses (multi-touch gestures, IPhone UI look'n'feel and AR applications), we have implemented an early feature set taking advantage of these popular input devices. In this paper, we present its performance through measurement data collected in our test platform, a 4-sided homemade low-cost virtual reality room, powered by ultra-short-range and standard HD home projectors.

  2. Virtual School Startups: Founder Processes in American K-12 Public Virtual Schools

    ERIC Educational Resources Information Center

    Taylor, Brett D.; McNair, Delores E.

    2018-01-01

    Traditional school districts do not have a lot of experience with virtual schools and have lost students to state and charter virtual schools. To retain students and offer alternative learning opportunities, more public districts are starting their own virtual schools. This study was an examination of foundational processes at three California…

  3. Effects of virtual reality training with modified constraint-induced movement therapy on upper extremity function in acute stage stroke: a preliminary study.

    PubMed

    Ji, Eun-Kyu; Lee, Sang-Heon

    2016-11-01

    [Purpose] The purpose of this study was to investigate the effects of virtual reality training combined with modified constraint-induced movement therapy on upper extremity motor function recovery in acute stage stroke patients. [Subjects and Methods] Four acute stage stroke patients participated in the study. A multiple baseline single subject experimental design was utilized. Modified constraint-induced movement therapy was used according to the EXplaining PLastICITy after stroke protocol during baseline sessions. Virtual reality training with modified constraint-induced movement therapy was applied during treatment sessions. The Manual Function Test and the Box and Block Test were used to measure upper extremity function before every session. [Results] The subjects' upper extremity function improved during the intervention period. [Conclusion] Virtual reality training combined with modified constraint-induced movement is effective for upper extremity function recovery in acute stroke patients.

  4. Minimum Description Length Block Finder, a Method to Identify Haplotype Blocks and to Compare the Strength of Block Boundaries

    PubMed Central

    Mannila, H.; Koivisto, M.; Perola, M.; Varilo, T.; Hennah, W.; Ekelund, J.; Lukk, M.; Peltonen, L.; Ukkonen, E.

    2003-01-01

    We describe a new probabilistic method for finding haplotype blocks that is based on the use of the minimum description length (MDL) principle. We give a rigorous definition of the quality of a segmentation of a genomic region into blocks and describe a dynamic programming algorithm for finding the optimal segmentation with respect to this measure. We also describe a method for finding the probability of a block boundary for each pair of adjacent markers: this gives a tool for evaluating the significance of each block boundary. We have applied the method to the published data of Daly and colleagues. The results expose some problems that exist in the current methods for the evaluation of the significance of predicted block boundaries. Our method, MDL block finder, can be used to compare block borders in different sample sets, and we demonstrate this by applying the MDL-based method to define the block structure in chromosomes from population isolates. PMID:12761696

  5. Minimum description length block finder, a method to identify haplotype blocks and to compare the strength of block boundaries.

    PubMed

    Mannila, H; Koivisto, M; Perola, M; Varilo, T; Hennah, W; Ekelund, J; Lukk, M; Peltonen, L; Ukkonen, E

    2003-07-01

    We describe a new probabilistic method for finding haplotype blocks that is based on the use of the minimum description length (MDL) principle. We give a rigorous definition of the quality of a segmentation of a genomic region into blocks and describe a dynamic programming algorithm for finding the optimal segmentation with respect to this measure. We also describe a method for finding the probability of a block boundary for each pair of adjacent markers: this gives a tool for evaluating the significance of each block boundary. We have applied the method to the published data of Daly and colleagues. The results expose some problems that exist in the current methods for the evaluation of the significance of predicted block boundaries. Our method, MDL block finder, can be used to compare block borders in different sample sets, and we demonstrate this by applying the MDL-based method to define the block structure in chromosomes from population isolates.

  6. Present-day kinematics of the Danakil block (southern Red Sea-Afar) constrained by GPS

    NASA Astrophysics Data System (ADS)

    Ladron de Guevara, R.; Jonsson, S.; Ruch, J.; Doubre, C.; Reilinger, R. E.; Ogubazghi, G.; Floyd, M.; Vasyura-Bathke, H.

    2017-12-01

    The rifting of the Arabian plate from the Nubian and Somalian plates is primarily accommodated by seismic and magmatic activity along two rift arms of the Afar triple junction (the Red Sea and Gulf of Aden rifts). The spatial distribution of active deformation in the Afar region have been constrained with geodetic observations. However, the plate boundary configuration in which this deformation occurs is still not fully understood. South of 17°N, the Red Sea rift is composed of two parallel and overlapping rift branches separated by the Danakil block. The distribution of the extension across these two overlapping rifts, their potential connection through a transform fault zone and the counterclockwise rotation of the Danakil block have not yet been fully resolved. Here we analyze new GPS observations from the Danakil block, the Gulf of Zula area (Eritrea) and Afar (Ethiopia) together with previous geodetic survey data to better constrain the plate kinematics and active deformation of the region. The new data has been collected in 2016 and add up to 5 years to the existing geodetic observations (going back to 2000). Our improved GPS velocity field shows differences with previously modeled GPS velocities, suggesting that the rate and rotation of the Danakil block need to be updated. The new velocity field also shows that the plate-boundary strain is accommodated by broad deformation zones rather than across sharp boundaries between tectonic blocks. To better determine the spatial distribution of the strain, we first implement a rigid block model to constrain the overall regional plate kinematics and to isolate the plate-boundary deformation at the western boundary of the Danakil block. We then study whether the recent southern Red Sea rifting events have caused detectable changes in observed GPS velocities and if the observations can be used to constrain the scale of this offshore rift activity. Finally, we investigate different geometries of transform faults that

  7. 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)

  8. Pinpoint Delivery of Molecules by Using Electron Beam Addressing Virtual Cathode Display.

    PubMed

    Hoshino, Takayuki; Yoshioka, Moto; Wagatsuma, Akira; Miyazako, Hiroki; Mabuchi, Kunihiko

    2018-03-01

    Electroporation, a physical transfection method to introduce genomic molecules in selective living cells, could be implemented by microelectrode devices. A local electric field generated by a finer electrode can induces cytomembrane poration in the electrode vicinity. To employ fine, high-speed scanning electrodes, we developed a fine virtual cathode pattern, which was generated on a cell adhesive surface of 100-nm-thick SiN membrane by inverted-electron beam lithography. The SiN membrane works as both a vacuum barrier and the display screen of the virtual cathode. The kinetic energy of the incident primary electrons to the SiN membrane was completely blocked, whereas negative charges and leaking electric current appeared on the surface of the dielectric SiN membrane within a region of 100 nm. Locally controlled transmembrane molecular delivery was demonstrated on adhered C2C12 myoblast cells in a culturing medium with fluorescent dye propidium iodide (PI). Increasing fluorescence of pre-diluted PI indicated local poration and transmembrane inflow at the virtual cathode position, as well as intracellular diffusion. The transmembrane inflows depended on beam duration time and acceleration voltage. At the post-molecular delivery, a slight decrease in intracellular PI fluorescence intensity indicates membrane recovery from the poration. Cell viability was confirmed by time-lapse cell imaging of post-exposure cell migration.

  9. A discrete element modelling approach for block impacts on trees

    NASA Astrophysics Data System (ADS)

    Toe, David; Bourrier, Franck; Olmedo, Ignatio; Berger, Frederic

    2015-04-01

    These past few year rockfall models explicitly accounting for block shape, especially those using the Discrete Element Method (DEM), have shown a good ability to predict rockfall trajectories. Integrating forest effects into those models still remain challenging. This study aims at using a DEM approach to model impacts of blocks on trees and identify the key parameters controlling the block kinematics after the impact on a tree. A DEM impact model of a block on a tree was developed and validated using laboratory experiments. Then, key parameters were assessed using a global sensitivity analyse. Modelling the impact of a block on a tree using DEM allows taking into account large displacements, material non-linearities and contacts between the block and the tree. Tree stems are represented by flexible cylinders model as plastic beams sustaining normal, shearing, bending, and twisting loading. Root soil interactions are modelled using a rotation stiffness acting on the bending moment at the bottom of the tree and a limit bending moment to account for tree overturning. The crown is taken into account using an additional mass distribute uniformly on the upper part of the tree. The block is represented by a sphere. The contact model between the block and the stem consists of an elastic frictional model. The DEM model was validated using laboratory impact tests carried out on 41 fresh beech (Fagus Sylvatica) stems. Each stem was 1,3 m long with a diameter between 3 to 7 cm. Wood stems were clamped on a rigid structure and impacted by a 149 kg charpy pendulum. Finally an intensive simulation campaign of blocks impacting trees was done to identify the input parameters controlling the block kinematics after the impact on a tree. 20 input parameters were considered in the DEM simulation model : 12 parameters were related to the tree and 8 parameters to the block. The results highlight that the impact velocity, the stem diameter, and the block volume are the three input

  10. View southeast of caps for blocks for JFK; blocks are ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View southeast of caps for blocks for JFK; blocks are used to support ship when it is repositioned to paint inaccessible areas masked by original support blocks. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Carpentry Shop, League Island, Philadelphia, Philadelphia County, PA

  11. Raising Virtual Laboratories in Australia onto global platforms

    NASA Astrophysics Data System (ADS)

    Wyborn, L. A.; Barker, M.; Fraser, R.; Evans, B. J. K.; Moloney, G.; Proctor, R.; Moise, A. F.; Hamish, H.

    2016-12-01

    Across the globe, Virtual Laboratories (VLs), Science Gateways (SGs), and Virtual Research Environments (VREs) are being developed that enable users who are not co-located to actively work together at various scales to share data, models, tools, software, workflows, best practices, etc. Outcomes range from enabling `long tail' researchers to more easily access specific data collections, to facilitating complex workflows on powerful supercomputers. In Australia, government funding has facilitated the development of a range of VLs through the National eResearch Collaborative Tools and Resources (NeCTAR) program. The VLs provide highly collaborative, research-domain oriented, integrated software infrastructures that meet user community needs. Twelve VLs have been funded since 2012, including the Virtual Geophysics Laboratory (VGL); Virtual Hazards, Impact and Risk Laboratory (VHIRL); Climate and Weather Science Laboratory (CWSLab); Marine Virtual Laboratory (MarVL); and Biodiversity and Climate Change Virtual Laboratory (BCCVL). These VLs share similar technical challenges, with common issues emerging on integration of tools, applications and access data collections via both cloud-based environments and other distributed resources. While each VL began with a focus on a specific research domain, communities of practice have now formed across the VLs around common issues, and facilitate identification of best practice case studies, and new standards. As a result, tools are now being shared where the VLs access data via data services using international standards such as ISO, OGC, W3C. The sharing of these approaches is starting to facilitate re-usability of infrastructure and is a step towards supporting interdisciplinary research. Whilst the focus of the VLs are Australia-centric, by using standards, these environments are able to be extended to analysis on other international datasets. Many VL datasets are subsets of global datasets and so extension to global is a

  12. 75 FR 5561 - Notice of Funds Availability (NOFA) Inviting Applications for the Specialty Crop Block Grant...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-03

    ... Availability (NOFA) Inviting Applications for the Specialty Crop Block Grant Program--Farm Bill (SCBGP-FB... entities in the specialty crop distribution chain in developing ``Good Agricultural Practices'', ``Good... on a previous Specialty Crop Block Grant Program (SCBGP) or SCBGP-FB project, indicate clearly how...

  13. A virtual fluoroscopy system to verify seed positioning accuracy during prostate permanent seed implants.

    PubMed

    Sarkar, V; Gutierrez, A N; Stathakis, S; Swanson, G P; Papanikolaou, N

    2009-01-01

    The purpose of this project was to develop a software platform to produce a virtual fluoroscopic image as an aid for permanent prostate seed implants. Seed location information from a pre-plan was extracted and used as input to in-house developed software to produce a virtual fluoroscopic image. In order to account for differences in patient positioning on the day of treatment, the user was given the ability to make changes to the virtual image. The system has been shown to work as expected for all test cases. The system allows for quick (on average less than 10 sec) generation of a virtual fluoroscopic image of the planned seed pattern. The image can be used as a verification tool to aid the physician in evaluating how close the implant is to the planned distribution throughout the procedure and enable remedial action should a large deviation be observed.

  14. Developmental gender differences in children in a virtual spatial memory task.

    PubMed

    León, Irene; Cimadevilla, José Manuel; Tascón, Laura

    2014-07-01

    Behavioral achievements are the product of brain maturation. During postnatal development, the medial temporal lobe completes its maturation, and children acquire new memory abilities. In recent years, virtual reality-based tasks have been introduced in the neuropsychology field to assess different cognitive functions. In this work, desktop virtual reality tasks are combined with classic psychometric tests to assess spatial abilities in 4- to 10-year-old children. Fifty boys and 50 girls 4-10-years of age participated in this study. Spatial reference memory and spatial working memory were assessed using a desktop virtual reality-based task. Other classic psychometric tests were also included in this work (e.g., the Corsi Block Tapping Test, digit tests, 10/36 Spatial Recall Test). In general terms, 4- and 5-year-old groups showed poorer performance than the older groups. However, 5-year-old children showed basic spatial navigation abilities with little difficulty. In addition, boys outperformed girls from the 6-8-year-old groups. Gender differences only emerged in the reference-memory version of the spatial task, whereas both sexes displayed similar performances in the working-memory version. There was general improvement in the performance of different tasks in children older than 5 years. However, results also suggest that brain regions involved in allocentric memory are functional even at the age of 5. In addition, the brain structures underlying reference memory mature later in girls than those required for the working memory.

  15. [Virtual reality in neurosurgery].

    PubMed

    Tronnier, V M; Staubert, A; Bonsanto, M M; Wirtz, C R; Kunze, S

    2000-03-01

    Virtual reality enables users to immerse themselves in a virtual three-dimensional world and to interact in this world. The simulation is different from the kind in computer games, in which the viewer is active but acts in a nonrealistic world, or on the TV screen, where we are passively driven in an active world. In virtual reality elements look realistic, they change their characteristics and have almost real-world unpredictability. Virtual reality is not only implemented in gambling dens and the entertainment industry but also in manufacturing processes (cars, furniture etc.), military applications and medicine. Especially the last two areas are strongly correlated, because telemedicine or telesurgery was originated for military reasons to operate on war victims from a secure distance or to perform surgery on astronauts in an orbiting space station. In medicine and especially neurosurgery virtual-reality methods are used for education, surgical planning and simulation on a virtual patient.

  16. Study on virtual instrument developing system based on intelligent virtual control

    NASA Astrophysics Data System (ADS)

    Tang, Baoping; Cheng, Fabin; Qin, Shuren

    2005-01-01

    The paper introduces a non-programming developing system of a virtual instument (VI), i.e., a virtual measurement instrument developing system (VMIDS) based on intelligent virtual control (IVC). The background of the IVC-based VMIDS is described briefly, and the hierarchical message bus (HMB)-based software architecture of VMIDS is discussed in detail. The three parts and functions of VMIDS are introduced, and the process of non-programming developing VI is further described.

  17. A Shifted Block Lanczos Algorithm 1: The Block Recurrence

    NASA Technical Reports Server (NTRS)

    Grimes, Roger G.; Lewis, John G.; Simon, Horst D.

    1990-01-01

    In this paper we describe a block Lanczos algorithm that is used as the key building block of a software package for the extraction of eigenvalues and eigenvectors of large sparse symmetric generalized eigenproblems. The software package comprises: a version of the block Lanczos algorithm specialized for spectrally transformed eigenproblems; an adaptive strategy for choosing shifts, and efficient codes for factoring large sparse symmetric indefinite matrices. This paper describes the algorithmic details of our block Lanczos recurrence. This uses a novel combination of block generalizations of several features that have only been investigated independently in the past. In particular new forms of partial reorthogonalization, selective reorthogonalization and local reorthogonalization are used, as is a new algorithm for obtaining the M-orthogonal factorization of a matrix. The heuristic shifting strategy, the integration with sparse linear equation solvers and numerical experience with the code are described in a companion paper.

  18. Impact of Machine Virtualization on Timing Precision for Performance-critical Tasks

    NASA Astrophysics Data System (ADS)

    Karpov, Kirill; Fedotova, Irina; Siemens, Eduard

    2017-07-01

    In this paper we present a measurement study to characterize the impact of hardware virtualization on basic software timing, as well as on precise sleep operations of an operating system. We investigated how timer hardware is shared among heavily CPU-, I/O- and Network-bound tasks on a virtual machine as well as on the host machine. VMware ESXi and QEMU/KVM have been chosen as commonly used examples of hypervisor- and host-based models. Based on statistical parameters of retrieved distributions, our results provide a very good estimation of timing behavior. It is essential for real-time and performance-critical applications such as image processing or real-time control.

  19. PROVIDE: A Pedagogical Reference Oracle for Virtual IntegrateD E-ducation

    ERIC Educational Resources Information Center

    Narasimhan, V. Lakshmi; Zhao, Shuxin; Liang, Hailong; Zhang, Shuangyi

    2006-01-01

    This paper presents an interactive educational environment for use over both "in situ" and distance-based modalities of teaching. Several technological issues relating to the design and development of the distributed virtual learning environment have also been raised. The PROVIDE framework proposed in this paper is a seamless distributed…

  20. Embodying self-compassion within virtual reality and its effects on patients with depression

    PubMed Central

    Falconer, Caroline J.; Rovira, Aitor; King, John A.; Gilbert, Paul; Antley, Angus; Fearon, Pasco; Ralph, Neil; Slater, Mel

    2016-01-01

    Background Self-criticism is a ubiquitous feature of psychopathology and can be combatted by increasing levels of self-compassion. However, some patients are resistant to self-compassion. Aims To investigate whether the effects of self-identification with virtual bodies within immersive virtual reality could be exploited to increase self-compassion in patients with depression. Method We developed an 8-minute scenario in which 15 patients practised delivering compassion in one virtual body and then experienced receiving it from themselves in another virtual body. Results In an open trial, three repetitions of this scenario led to significant reductions in depression severity and self-criticism, as well as to a significant increase in self-compassion, from baseline to 4-week follow-up. Four patients showed clinically significant improvement. Conclusions The results indicate that interventions using immersive virtual reality may have considerable clinical potential and that further development of these methods preparatory to a controlled trial is now warranted. Declaration of interest None. Copyright and usage © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY) licence. PMID:27703757

  1. Spherical harmonics coefficients for ligand-based virtual screening of cyclooxygenase inhibitors.

    PubMed

    Wang, Quan; Birod, Kerstin; Angioni, Carlo; Grösch, Sabine; Geppert, Tim; Schneider, Petra; Rupp, Matthias; Schneider, Gisbert

    2011-01-01

    Molecular descriptors are essential for many applications in computational chemistry, such as ligand-based similarity searching. Spherical harmonics have previously been suggested as comprehensive descriptors of molecular structure and properties. We investigate a spherical harmonics descriptor for shape-based virtual screening. We introduce and validate a partially rotation-invariant three-dimensional molecular shape descriptor based on the norm of spherical harmonics expansion coefficients. Using this molecular representation, we parameterize molecular surfaces, i.e., isosurfaces of spatial molecular property distributions. We validate the shape descriptor in a comprehensive retrospective virtual screening experiment. In a prospective study, we virtually screen a large compound library for cyclooxygenase inhibitors, using a self-organizing map as a pre-filter and the shape descriptor for candidate prioritization. 12 compounds were tested in vitro for direct enzyme inhibition and in a whole blood assay. Active compounds containing a triazole scaffold were identified as direct cyclooxygenase-1 inhibitors. This outcome corroborates the usefulness of spherical harmonics for representation of molecular shape in virtual screening of large compound collections. The combination of pharmacophore and shape-based filtering of screening candidates proved to be a straightforward approach to finding novel bioactive chemotypes with minimal experimental effort.

  2. Linking atmospheric blocking to European temperature extremes in spring

    NASA Astrophysics Data System (ADS)

    Brunner, Lukas; Hegerl, Gabriele; Steiner, Andrea

    2017-04-01

    The weather in Europe is influenced by a range of dynamical features such as the Atlantic storm tracks, the jet stream, and atmospheric blocking. Blocking describes an atmospheric situation in which a stationary and persistent high pressure system interrupts the climatological flow for several days to weeks. It can trigger cold and warm spells which is of special relevance during the spring season because vegetation is particularly vulnerable to extreme temperatures in the early greening phase. We investigate European cold and warm spells in the 36 springs from 1979 to 2014 in temperature data from the European daily high-resolution gridded dataset (E-OBS) and connect them to blocking derived from geopotential height fields from ERA-Interim. A highly significant link between blocking and both, cold and warm spells is found that changes during spring. Resolving monthly frequencies, we find a shift in the preferred locations of blocking throughout spring. The maximum blocking frequency during cold spells shifts from Scandinavia to the British Isles in March and April. During warm spells it continuously shifts further northward during the spring season. The location of the block is found to be essential for the sign of the relationship. Blocking over the north-eastern Atlantic and over northern Europe is strongly linked to cold conditions, while blocking over central Europe is associated with warm conditions. Consistently the spatial distribution of temperature extremes across Europe is highly sensitive to the occurrence of blocking. More than 80 % of cold spells in south-eastern Europe occur during blocking, compared to less than 30 % in northern Europe. Warm spells show the opposite pattern and more than 70 % co-occur with blocking in northern Europe, compared to less than 30 % in parts of southern Europe. We find considerable interannual variability over the analysis period from 1979 to 2014 but also a decrease in cold spells and an increase in warm spells

  3. Finite-Size Scaling for the Baxter-Wu Model Using Block Distribution Functions

    NASA Astrophysics Data System (ADS)

    Velonakis, Ioannis N.; Hadjiagapiou, Ioannis A.

    2018-05-01

    In the present work, we present an alternative way of applying the well-known finite-size scaling (FSS) theory in the case of a Baxter-Wu model using Binder-like blocks. Binder's ideas are extended to estimate phase transition points and the corresponding scaling exponents not only for magnetic but also for energy properties, saving computational time and effort. The vast majority of our conclusions can be easily generalized to other models.

  4. 1001 Ways to run AutoDock Vina for virtual screening

    NASA Astrophysics Data System (ADS)

    Jaghoori, Mohammad Mahdi; Bleijlevens, Boris; Olabarriaga, Silvia D.

    2016-03-01

    Large-scale computing technologies have enabled high-throughput virtual screening involving thousands to millions of drug candidates. It is not trivial, however, for biochemical scientists to evaluate the technical alternatives and their implications for running such large experiments. Besides experience with the molecular docking tool itself, the scientist needs to learn how to run it on high-performance computing (HPC) infrastructures, and understand the impact of the choices made. Here, we review such considerations for a specific tool, AutoDock Vina, and use experimental data to illustrate the following points: (1) an additional level of parallelization increases virtual screening throughput on a multi-core machine; (2) capturing of the random seed is not enough (though necessary) for reproducibility on heterogeneous distributed computing systems; (3) the overall time spent on the screening of a ligand library can be improved by analysis of factors affecting execution time per ligand, including number of active torsions, heavy atoms and exhaustiveness. We also illustrate differences among four common HPC infrastructures: grid, Hadoop, small cluster and multi-core (virtual machine on the cloud). Our analysis shows that these platforms are suitable for screening experiments of different sizes. These considerations can guide scientists when choosing the best computing platform and set-up for their future large virtual screening experiments.

  5. 1001 Ways to run AutoDock Vina for virtual screening.

    PubMed

    Jaghoori, Mohammad Mahdi; Bleijlevens, Boris; Olabarriaga, Silvia D

    2016-03-01

    Large-scale computing technologies have enabled high-throughput virtual screening involving thousands to millions of drug candidates. It is not trivial, however, for biochemical scientists to evaluate the technical alternatives and their implications for running such large experiments. Besides experience with the molecular docking tool itself, the scientist needs to learn how to run it on high-performance computing (HPC) infrastructures, and understand the impact of the choices made. Here, we review such considerations for a specific tool, AutoDock Vina, and use experimental data to illustrate the following points: (1) an additional level of parallelization increases virtual screening throughput on a multi-core machine; (2) capturing of the random seed is not enough (though necessary) for reproducibility on heterogeneous distributed computing systems; (3) the overall time spent on the screening of a ligand library can be improved by analysis of factors affecting execution time per ligand, including number of active torsions, heavy atoms and exhaustiveness. We also illustrate differences among four common HPC infrastructures: grid, Hadoop, small cluster and multi-core (virtual machine on the cloud). Our analysis shows that these platforms are suitable for screening experiments of different sizes. These considerations can guide scientists when choosing the best computing platform and set-up for their future large virtual screening experiments.

  6. [Research on the virtual water composition and virtual water trade for agriculture in Beijing].

    PubMed

    Wang, Hong-rui; Wang, Yan; Wang, Jun-hong; Dong, Yan-yan; Han, Zhao-xing

    2007-12-01

    Based on the irrigation norm of typical district and county, and revised by the isoline map of Chinese crops water demand, the change of crops program was analyzed as well as the agricultural water use and its GDP benefits. Then the virtual water was calculated for years. At last, the input-output method was used to calculate the trade of virtual water in Beijing. As the results, the virtual water for cereal crops has been decreasing in Beijing, from 1.832 x 10(9) m3 in 1990 to 4.283 x 10(8) m3 in 2004. Otherwise the virtual water for technical crops has been increasing, which is from 9.06 x 10(8) m3 in 1990 to 1.492 x 10(9) m3 in 2004. On the whole, the virtual water for crops has been decreasing in Beijing. From the angle of primary products Beijing is a virtual water importing area. Virtual water importing of annual average is 2.37 x 10(8) m3, which is about 5.93% of the total water of Beijing. Virtual water has been an important supplement of local real water of Beijing.

  7. 17 CFR 240.16a-7 - Transactions effected in connection with a distribution.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... good faith in the distribution of such block of securities; or (ii) A security purchased in good faith... the transaction is engaged in the business of distributing securities and is participating in good faith, in the ordinary course of such business, in the distribution of such block of securities; and (2...

  8. Modified round block mastopexy versus traditional round block mastopexy.

    PubMed

    Sterodimas, A; Nicaretta, B; Boriani, F

    2015-01-01

    Breast ptosis may be caused by several factors, including significant weight loss, pregnancy, long breastfeeding periods, and involution of the postmenopausal breast tissue. The authors performed a prospective study to evaluate patient satisfaction and the rate of complications after modified round block mastopexy versus traditional round block mastopexy. Forty-four patients fulfilled the inclusion criteria for undergoing round block mastopexy in a prospective randomized controlled study performed from 2007 to 2008. All the patients received polyurethane silicone implants. Group A included patients who underwent the traditional round block technique described by Benelli. Group B included patients who underwent the traditional round block and 4 cardinal glando-glandular permanent sutures. The overall satisfaction with body appearance after breast mastopexy was rated on a scale of 1 (poor), 2 (fair), 3 (good), 4 (very good), and 5 (excellent). Group A patient ages ranged from 28 to 52 years and in Group B ranged from 29 to 49 years. The mean implant volume was 215 cc in both Groups. The complication and satisfaction rates for both Groups are reported. The combination of the cardinal glandulo-glandular sutures along with the traditional round block appears to be key to preventing the areolar enlargement and persistent breast ptosis. The satisfaction rates in patients who underwent the modified round mastopexy appear superior when compared to the traditional round block mastopexy. Furhter long-term follow-up need to be performed in order to confirm the favorable results seen in this series of cases.

  9. A Virtual Object-Location Task for Children: Gender and Videogame Experience Influence Navigation; Age Impacts Memory and Completion Time.

    PubMed

    Rodriguez-Andres, David; Mendez-Lopez, Magdalena; Juan, M-Carmen; Perez-Hernandez, Elena

    2018-01-01

    The use of virtual reality-based tasks for studying memory has increased considerably. Most of the studies that have looked at child population factors that influence performance on such tasks have been focused on cognitive variables. However, little attention has been paid to the impact of non-cognitive skills. In the present paper, we tested 52 typically-developing children aged 5-12 years in a virtual object-location task. The task assessed their spatial short-term memory for the location of three objects in a virtual city. The virtual task environment was presented using a 3D application consisting of a 120″ stereoscopic screen and a gamepad interface. Measures of learning and displacement indicators in the virtual environment, 3D perception, satisfaction, and usability were obtained. We assessed the children's videogame experience, their visuospatial span, their ability to build blocks, and emotional and behavioral outcomes. The results indicate that learning improved with age. Significant effects on the speed of navigation were found favoring boys and those more experienced with videogames. Visuospatial skills correlated mainly with ability to recall object positions, but the correlation was weak. Longer paths were related with higher scores of withdrawal behavior, attention problems, and a lower visuospatial span. Aggressiveness and experience with the device used for interaction were related with faster navigation. However, the correlations indicated only weak associations among these variables.

  10. A Virtual Object-Location Task for Children: Gender and Videogame Experience Influence Navigation; Age Impacts Memory and Completion Time

    PubMed Central

    Rodriguez-Andres, David; Mendez-Lopez, Magdalena; Juan, M.-Carmen; Perez-Hernandez, Elena

    2018-01-01

    The use of virtual reality-based tasks for studying memory has increased considerably. Most of the studies that have looked at child population factors that influence performance on such tasks have been focused on cognitive variables. However, little attention has been paid to the impact of non-cognitive skills. In the present paper, we tested 52 typically-developing children aged 5–12 years in a virtual object-location task. The task assessed their spatial short-term memory for the location of three objects in a virtual city. The virtual task environment was presented using a 3D application consisting of a 120″ stereoscopic screen and a gamepad interface. Measures of learning and displacement indicators in the virtual environment, 3D perception, satisfaction, and usability were obtained. We assessed the children’s videogame experience, their visuospatial span, their ability to build blocks, and emotional and behavioral outcomes. The results indicate that learning improved with age. Significant effects on the speed of navigation were found favoring boys and those more experienced with videogames. Visuospatial skills correlated mainly with ability to recall object positions, but the correlation was weak. Longer paths were related with higher scores of withdrawal behavior, attention problems, and a lower visuospatial span. Aggressiveness and experience with the device used for interaction were related with faster navigation. However, the correlations indicated only weak associations among these variables. PMID:29674988

  11. Building interactive virtual environments for simulated training in medicine using VRML and Java/JavaScript.

    PubMed

    Korocsec, D; Holobar, A; Divjak, M; Zazula, D

    2005-12-01

    Medicine is a difficult thing to learn. Experimenting with real patients should not be the only option; simulation deserves a special attention here. Virtual Reality Modelling Language (VRML) as a tool for building virtual objects and scenes has a good record of educational applications in medicine, especially for static and animated visualisations of body parts and organs. However, to create computer simulations resembling situations in real environments the required level of interactivity and dynamics is difficult to achieve. In the present paper we describe some approaches and techniques which we used to push the limits of the current VRML technology further toward dynamic 3D representation of virtual environments (VEs). Our demonstration is based on the implementation of a virtual baby model, whose vital signs can be controlled from an external Java application. The main contributions of this work are: (a) outline and evaluation of the three-level VRML/Java implementation of the dynamic virtual environment, (b) proposal for a modified VRML Timesensor node, which greatly improves the overall control of system performance, and (c) architecture of the prototype distributed virtual environment for training in neonatal resuscitation comprising the interactive virtual newborn, active bedside monitor for vital signs and full 3D representation of the surgery room.

  12. 76 FR 312 - Notice of Funds Availability (NOFA) Inviting Applications for the Specialty Crop Block Grant...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-04

    ... Specialty Crop Block Grant Program-Farm Bill (SCBGP-FB) AGENCY: Agricultural Marketing Service, USDA. ACTION... systems; assisting all entities in the specialty crop distribution chain in developing ``Good Agricultural... Crop Block Grant Program (SCBGP). Identify by project title if an award was made to either a socially...

  13. Algorithm and Application of Gcp-Independent Block Adjustment for Super Large-Scale Domestic High Resolution Optical Satellite Imagery

    NASA Astrophysics Data System (ADS)

    Sun, Y. S.; Zhang, L.; Xu, B.; Zhang, Y.

    2018-04-01

    The accurate positioning of optical satellite image without control is the precondition for remote sensing application and small/medium scale mapping in large abroad areas or with large-scale images. In this paper, aiming at the geometric features of optical satellite image, based on a widely used optimization method of constraint problem which is called Alternating Direction Method of Multipliers (ADMM) and RFM least-squares block adjustment, we propose a GCP independent block adjustment method for the large-scale domestic high resolution optical satellite image - GISIBA (GCP-Independent Satellite Imagery Block Adjustment), which is easy to parallelize and highly efficient. In this method, the virtual "average" control points are built to solve the rank defect problem and qualitative and quantitative analysis in block adjustment without control. The test results prove that the horizontal and vertical accuracy of multi-covered and multi-temporal satellite images are better than 10 m and 6 m. Meanwhile the mosaic problem of the adjacent areas in large area DOM production can be solved if the public geographic information data is introduced as horizontal and vertical constraints in the block adjustment process. Finally, through the experiments by using GF-1 and ZY-3 satellite images over several typical test areas, the reliability, accuracy and performance of our developed procedure will be presented and studied in this paper.

  14. Can a simple lumped parameter model simulate complex transit time distributions? Benchmarking experiments in a virtual watershed.

    NASA Astrophysics Data System (ADS)

    Wilusz, D. C.; Maxwell, R. M.; Buda, A. R.; Ball, W. P.; Harman, C. J.

    2016-12-01

    The catchment transit-time distribution (TTD) is the time-varying, probabilistic distribution of water travel times through a watershed. The TTD is increasingly recognized as a useful descriptor of a catchment's flow and transport processes. However, TTDs are temporally complex and cannot be observed directly at watershed scale. Estimates of TTDs depend on available environmental tracers (such as stable water isotopes) and an assumed model whose parameters can be inverted from tracer data. All tracers have limitations though, such as (typically) short periods of observation or non-conservative behavior. As a result, models that faithfully simulate tracer observations may nonetheless yield TTD estimates with significant errors at certain times and water ages, conditioned on the tracer data available and the model structure. Recent advances have shown that time-varying catchment TTDs can be parsimoniously modeled by the lumped parameter rank StorAge Selection (rSAS) model, in which an rSAS function relates the distribution of water ages in outflows to the composition of age-ranked water in storage. Like other TTD models, rSAS is calibrated and evaluated against environmental tracer data, and the relative influence of tracer-dependent and model-dependent error on its TTD estimates is poorly understood. The purpose of this study is to benchmark the ability of different rSAS formulations to simulate TTDs in a complex, synthetic watershed where the lumped model can be calibrated and directly compared to a virtually "true" TTD. This experimental design allows for isolation of model-dependent error from tracer-dependent error. The integrated hydrologic model ParFlow with SLIM-FAST particle tracking code is used to simulate the watershed and its true TTD. To add field intelligence, the ParFlow model is populated with over forty years of hydrometric and physiographic data from the WE-38 subwatershed of the USDA's Mahantango Creek experimental catchment in PA, USA. The

  15. Shader Lamps Virtual Patients: the physical manifestation of virtual patients.

    PubMed

    Rivera-Gutierrez, Diego; Welch, Greg; Lincoln, Peter; Whitton, Mary; Cendan, Juan; Chesnutt, David A; Fuchs, Henry; Lok, Benjamin

    2012-01-01

    We introduce the notion of Shader Lamps Virtual Patients (SLVP) - the combination of projector-based Shader Lamps Avatars and interactive virtual humans. This paradigm uses Shader Lamps Avatars technology to give a 3D physical presence to conversational virtual humans, improving their social interactivity and enabling them to share the physical space with the user. The paradigm scales naturally to multiple viewers, allowing for scenarios where an instructor and multiple students are involved in the training. We have developed a physical-virtual patient for medical students to conduct ophthalmic exams, in an interactive training experience. In this experience, the trainee practices multiple skills simultaneously, including using a surrogate optical instrument in front of a physical head, conversing with the patient about his fears, observing realistic head motion, and practicing patient safety. Here we present a prototype system and results from a preliminary formative evaluation of the system.

  16. Characterizing the inverses of block tridiagonal, block Toeplitz matrices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boffi, Nicholas M.; Hill, Judith C.; Reuter, Matthew G.

    2014-12-04

    We consider the inversion of block tridiagonal, block Toeplitz matrices and comment on the behaviour of these inverses as one moves away from the diagonal. Using matrix M bius transformations, we first present an O(1) representation (with respect to the number of block rows and block columns) for the inverse matrix and subsequently use this representation to characterize the inverse matrix. There are four symmetry-distinct cases where the blocks of the inverse matrix (i) decay to zero on both sides of the diagonal, (ii) oscillate on both sides, (iii) decay on one side and oscillate on the other and (iv)more » decay on one side and grow on the other. This characterization exposes the necessary conditions for the inverse matrix to be numerically banded and may also aid in the design of preconditioners and fast algorithms. Finally, we present numerical examples of these matrix types.« less

  17. Wavelength-scale photonic-crystal laser formed by electron-beam-induced nano-block deposition.

    PubMed

    Seo, Min-Kyo; Kang, Ju-Hyung; Kim, Myung-Ki; Ahn, Byeong-Hyeon; Kim, Ju-Young; Jeong, Kwang-Yong; Park, Hong-Gyu; Lee, Yong-Hee

    2009-04-13

    A wavelength-scale cavity is generated by printing a carbonaceous nano-block on a photonic-crystal waveguide. The nanometer-size carbonaceous block is grown at a pre-determined region by the electron-beam-induced deposition method. The wavelength-scale photonic-crystal cavity operates as a single mode laser, near 1550 nm with threshold of approximately 100 microW at room temperature. Finite-difference time-domain computations show that a high-quality-factor cavity mode is defined around the nano-block with resonant wavelength slightly longer than the dispersion-edge of the photonic-crystal waveguide. Measured near-field images exhibit photon distribution well-localized in the proximity of the printed nano-block. Linearly-polarized emission along the vertical direction is also observed.

  18. The Virtual Reference Librarian's Handbook.

    ERIC Educational Resources Information Center

    Lipow, Anne Grodzins

    This book is a practical guide to librarians and their administrators who are thinking about or in the early stages of providing virtual reference service. Part 1, "The Decision to Go Virtual," provides a context for thinking about virtual reference, including the benefits and problems, getting in the virtual frame of mind, and shopping…

  19. Virtual reality for emergency training

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Altinkemer, K.

    1995-12-31

    Virtual reality is a sequence of scenes generated by a computer as a response to the five different senses. These senses are sight, sound, taste, touch, smell. Other senses that can be used in virtual reality include balance, pheromonal, and immunological senses. Many application areas include: leisure and entertainment, medicine, architecture, engineering, manufacturing, and training. Virtual reality is especially important when it is used for emergency training and management of natural disasters including earthquakes, floods, tornados and other situations which are hard to emulate. Classical training methods for these extraordinary environments lack the realistic surroundings that virtual reality can provide.more » In order for virtual reality to be a successful training tool the design needs to include certain aspects; such as how real virtual reality should be and how much fixed cost is entailed in setting up the virtual reality trainer. There are also pricing questions regarding the price per training session on virtual reality trainer, and the appropriate training time length(s).« less

  20. Fluvial entrainment of low density peat blocks (block carbon)

    NASA Astrophysics Data System (ADS)

    Warburton, Jeff

    2014-05-01

    In many fluvial environments low density materials are transported in significant quantities and these form an important part of the stream load and /or have a distinct impact on sedimentation in these environments. However, there are significant gaps in understanding of how these materials are entrained and transported by streams and rivers. Eroding upland peatland environments in particular, frequently have fluvial systems in which large eroded peat blocks, often exceeding 1 m in length; form an important component of the stream material flux. Transport of this material is significant in determining rates of erosion but also has important impacts in terms of damage to infrastructure and carbon loss. This paper describes a field experiment designed to establish for the first time the conditions under which large peat blocks (c. > 0.1 m b axis) are initially entrained from a rough gravel bed. The field site is Trout Beck, in the North Pennines, Northern England which is an upland wandering river channel with occasional lateral and mid channel bars. Mean low flow stage is typically 0.2 m but during flood can rapidly rise, in one to two hours, to over 1.5 m. To study peat block entrainment a bespoke data acquisition system consisting of two pressure transducers, four release triggers and time lapse camera was set up. The pressure transducers provided a record of local depth and the release triggers were embedded in peat blocks to record initial motion and arranged on the rough stream bed. The time lapse camera provided verification of timing of block entrainment (during daylight hours) and also provided information on the mechanism of initial movement. Peat blocks were cut from a local source and were equidimensional, ranging in size from 0.1 to 0.7 m. The derived entrainment function is related to a critical depth of entrainment. Results demonstrate that peat blocks are entrained when the local depth approximates the height of the peat block. Blocks frequently shift

  1. Optimizing Virtual Network Functions Placement in Virtual Data Center Infrastructure Using Machine Learning

    NASA Astrophysics Data System (ADS)

    Bolodurina, I. P.; Parfenov, D. I.

    2018-01-01

    We have elaborated a neural network model of virtual network flow identification based on the statistical properties of flows circulating in the network of the data center and characteristics that describe the content of packets transmitted through network objects. This enabled us to establish the optimal set of attributes to identify virtual network functions. We have established an algorithm for optimizing the placement of virtual data functions using the data obtained in our research. Our approach uses a hybrid method of visualization using virtual machines and containers, which enables to reduce the infrastructure load and the response time in the network of the virtual data center. The algorithmic solution is based on neural networks, which enables to scale it at any number of the network function copies.

  2. Using Virtual Observatory Services in Sky View

    NASA Technical Reports Server (NTRS)

    McGlynn, Thomas A.

    2007-01-01

    For over a decade Skyview has provided astronomers and the public with easy access to survey and imaging data from all wavelength regimes. SkyView has pioneered many of the concepts that underlie the Virtual Observatory. Recently SkyView has been released as a distributable package which uses VO protocols to access image and catalog services. This chapter describes how to use the Skyview as a local service and how to customize it to access additional VO services and local data.

  3. Virtual Oscillator Controls | Grid Modernization | NREL

    Science.gov Websites

    Virtual Oscillator Controls Virtual Oscillator Controls NREL is developing virtual oscillator Santa-Barbara, and SunPower. Publications Synthesizing Virtual Oscillators To Control Islanded Inverters Synchronization of Parallel Single-Phase Inverters Using Virtual Oscillator Control, IEEE Transactions on Power

  4. Towards monitoring the englacial fracture state using virtual-reflector seismology

    NASA Astrophysics Data System (ADS)

    Lindner, F.; Weemstra, C.; Walter, F.; Hadziioannou, C.

    2018-04-01

    In seismology, coda wave interferometry (CWI) is an effective tool to monitor time-lapse changes using later arriving, multiply scattered coda waves. Typically, CWI relies on an estimate of the medium's impulse response. The latter is retrieved through simple time-averaging of receiver-receiver cross-correlations of the ambient field, i.e. seismic interferometry (SI). In general, the coda are induced by heterogeneities in the Earth. Being comparatively homogeneous, however, ice bodies such as glaciers and ice sheets exhibit little scattering. In addition, the temporal stability of the time-averaged cross-correlations suffers from temporal variations in the distribution and amplitude of the passive seismic sources. Consequently, application of CWI to ice bodies is currently limited. Nevertheless, fracturing and changes in the englacial macroscopic water content alter the bulk elastic properties of ice bodies, which can be monitored with cryoseismological measurements. To overcome the current limited applicability of CWI to ice bodies, we therefore introduce virtual-reflector seismology (VRS). VRS relies on a so-called multidimensional deconvolution (MDD) process of the time-averaged crosscorrelations. The technique results in the retrieval of a medium response that includes virtual reflections from a contour of receivers enclosing the region of interest (i.e., the region to be monitored). The virtual reflections can be interpreted as artificial coda replacing the (lacking) natural scattered coda. Hence, this artificial coda might be exploited for the purpose of CWI. From an implementation point of view, VRS is similar to SI by MDD, which, as its name suggests, also relies on a multidimensional deconvolution process. SI by MDD, however, does not generate additional virtual reflections. Advantageously, both techniques mitigate spurious coda changes associated with temporal variations in the distribution and amplitude of the passive seismic sources. In this work, we

  5. Virtual Teaming and Collaboration Technology: A Study of Influences on Virtual Project Outcomes

    ERIC Educational Resources Information Center

    Broils, Gary C.

    2014-01-01

    The purpose of this quantitative correlational study was to explore the relationships between the independent variables, contextual factors for virtual teams and collaboration technology, and the dependent variable, virtual project outcomes. The problem leading to the need for the study is a lower success rate for virtual projects compared to…

  6. Molecular dynamics coupled with a virtual system for effective conformational sampling.

    PubMed

    Hayami, Tomonori; Kasahara, Kota; Nakamura, Haruki; Higo, Junichi

    2018-07-15

    An enhanced conformational sampling method is proposed: virtual-system coupled canonical molecular dynamics (VcMD). Although VcMD enhances sampling along a reaction coordinate, this method is free from estimation of a canonical distribution function along the reaction coordinate. This method introduces a virtual system that does not necessarily obey a physical law. To enhance sampling the virtual system couples with a molecular system to be studied. Resultant snapshots produce a canonical ensemble. This method was applied to a system consisting of two short peptides in an explicit solvent. Conventional molecular dynamics simulation, which is ten times longer than VcMD, was performed along with adaptive umbrella sampling. Free-energy landscapes computed from the three simulations mutually converged well. The VcMD provided quicker association/dissociation motions of peptides than the conventional molecular dynamics did. The VcMD method is applicable to various complicated systems because of its methodological simplicity. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

  7. Impact of distributions on the archetypes and prototypes in heterogeneous nanoparticle ensembles.

    PubMed

    Fernandez, Michael; Wilson, Hugh F; Barnard, Amanda S

    2017-01-05

    The magnitude and complexity of the structural and functional data available on nanomaterials requires data analytics, statistical analysis and information technology to drive discovery. We demonstrate that multivariate statistical analysis can recognise the sets of truly significant nanostructures and their most relevant properties in heterogeneous ensembles with different probability distributions. The prototypical and archetypal nanostructures of five virtual ensembles of Si quantum dots (SiQDs) with Boltzmann, frequency, normal, Poisson and random distributions are identified using clustering and archetypal analysis, where we find that their diversity is defined by size and shape, regardless of the type of distribution. At the complex hull of the SiQD ensembles, simple configuration archetypes can efficiently describe a large number of SiQDs, whereas more complex shapes are needed to represent the average ordering of the ensembles. This approach provides a route towards the characterisation of computationally intractable virtual nanomaterial spaces, which can convert big data into smart data, and significantly reduce the workload to simulate experimentally relevant virtual samples.

  8. Effects of virtualization on a scientific application - Running a hyperspectral radiative transfer code on virtual machines.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tikotekar, Anand A; Vallee, Geoffroy R; Naughton III, Thomas J

    2008-01-01

    The topic of system-level virtualization has recently begun to receive interest for high performance computing (HPC). This is in part due to the isolation and encapsulation offered by the virtual machine. These traits enable applications to customize their environments and maintain consistent software configurations in their virtual domains. Additionally, there are mechanisms that can be used for fault tolerance like live virtual machine migration. Given these attractive benefits to virtualization, a fundamental question arises, how does this effect my scientific application? We use this as the premise for our paper and observe a real-world scientific code running on a Xenmore » virtual machine. We studied the effects of running a radiative transfer simulation, Hydrolight, on a virtual machine. We discuss our methodology and report observations regarding the usage of virtualization with this application.« less

  9. 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.

  10. Interpretations of virtual reality.

    PubMed

    Voiskounsky, Alexander

    2011-01-01

    University students were surveyed to learn what they know about virtual realities. The two studies were administered with a half-year interval in which the students (N=90, specializing either in mathematics and science, or in social science and humanities) were asked to name particular examples of virtual realities. The second, but not the first study, was administered after the participants had the chance to see the movie "Avatar" (no investigation was held into whether they really saw it). While the students in both studies widely believed that activities such as social networking and online gaming represent virtual realities, some other examples provided by the students in the two studies differ: in the second study the participants expressed a better understanding of the items related to virtual realities. At the same time, not a single participant reported particular psychological states (either regular or altered) as examples of virtual realities. Profound popularization efforts need to be done to acquaint the public, including college students, with virtual realities and let the public adequately understand how such systems work.

  11. Achievement of Virtual and Real Objects Using a Short-Term Motor Learning Protocol in People with Duchenne Muscular Dystrophy: A Crossover Randomized Controlled Trial.

    PubMed

    Massetti, Thais; Fávero, Francis Meire; Menezes, Lilian Del Ciello de; Alvarez, Mayra Priscila Boscolo; Crocetta, Tânia Brusque; Guarnieri, Regiani; Nunes, Fátima L S; Monteiro, Carlos Bandeira de Mello; Silva, Talita Dias da

    2018-04-01

    To evaluate whether people with Duchenne muscular dystrophy (DMD) practicing a task in a virtual environment could improve performance given a similar task in a real environment, as well as distinguishing whether there is transference between performing the practice in virtual environment and then a real environment and vice versa. Twenty-two people with DMD were evaluated and divided into two groups. The goal was to reach out and touch a red cube. Group A began with the real task and had to touch a real object, and Group B began with the virtual task and had to reach a virtual object using the Kinect system. ANOVA showed that all participants decreased the movement time from the first (M = 973 ms) to the last block of acquisition (M = 783 ms) in both virtual and real tasks and motor learning could be inferred by the short-term retention and transfer task (with increasing distance of the target). However, the evaluation of task performance demonstrated that the virtual task provided an inferior performance when compared to the real task in all phases of the study, and there was no effect for sequence. Both virtual and real tasks promoted improvement of performance in the acquisition phase, short-term retention, and transfer. However, there was no transference of learning between environments. In conclusion, it is recommended that the use of virtual environments for individuals with DMD needs to be considered carefully.

  12. Adaptation of a Multi-Block Structured Solver for Effective Use in a Hybrid CPU/GPU Massively Parallel Environment

    NASA Astrophysics Data System (ADS)

    Gutzwiller, David; Gontier, Mathieu; Demeulenaere, Alain

    2014-11-01

    Multi-Block structured solvers hold many advantages over their unstructured counterparts, such as a smaller memory footprint and efficient serial performance. Historically, multi-block structured solvers have not been easily adapted for use in a High Performance Computing (HPC) environment, and the recent trend towards hybrid GPU/CPU architectures has further complicated the situation. This paper will elaborate on developments and innovations applied to the NUMECA FINE/Turbo solver that have allowed near-linear scalability with real-world problems on over 250 hybrid GPU/GPU cluster nodes. Discussion will focus on the implementation of virtual partitioning and load balancing algorithms using a novel meta-block concept. This implementation is transparent to the user, allowing all pre- and post-processing steps to be performed using a simple, unpartitioned grid topology. Additional discussion will elaborate on developments that have improved parallel performance, including fully parallel I/O with the ADIOS API and the GPU porting of the computationally heavy CPUBooster convergence acceleration module. Head of HPC and Release Management, Numeca International.

  13. Integration of virtualized worker nodes in standard batch systems

    NASA Astrophysics Data System (ADS)

    Büge, Volker; Hessling, Hermann; Kemp, Yves; Kunze, Marcel; Oberst, Oliver; Quast, Günter; Scheurer, Armin; Synge, Owen

    2010-04-01

    Current experiments in HEP only use a limited number of operating system flavours. Their software might only be validated on one single OS platform. Resource providers might have other operating systems of choice for the installation of the batch infrastructure. This is especially the case if a cluster is shared with other communities, or communities that have stricter security requirements. One solution would be to statically divide the cluster into separated sub-clusters. In such a scenario, no opportunistic distribution of the load can be achieved, resulting in a poor overall utilization efficiency. Another approach is to make the batch system aware of virtualization, and to provide each community with its favoured operating system in a virtual machine. Here, the scheduler has full flexibility, resulting in a better overall efficiency of the resources. In our contribution, we present a lightweight concept for the integration of virtual worker nodes into standard batch systems. The virtual machines are started on the worker nodes just before jobs are executed there. No meta-scheduling is introduced. We demonstrate two prototype implementations, one based on the Sun Grid Engine (SGE), the other using Maui/Torque as a batch system. Both solutions support local job as well as Grid job submission. The hypervisors currently used are Xen and KVM, a port to another system is easily envisageable. To better handle different virtual machines on the physical host, the management solution VmImageManager is developed. We will present first experience from running the two prototype implementations. In a last part, we will show the potential future use of this lightweight concept when integrated into high-level (i.e. Grid) work-flows.

  14. Sense of presence and anxiety during virtual social interactions between a human and virtual humans.

    PubMed

    Morina, Nexhmedin; Brinkman, Willem-Paul; Hartanto, Dwi; Emmelkamp, Paul M G

    2014-01-01

    Virtual reality exposure therapy (VRET) has been shown to be effective in treatment of anxiety disorders. Yet, there is lack of research on the extent to which interaction between the individual and virtual humans can be successfully implanted to increase levels of anxiety for therapeutic purposes. This proof-of-concept pilot study aimed at examining levels of the sense of presence and anxiety during exposure to virtual environments involving social interaction with virtual humans and using different virtual reality displays. A non-clinical sample of 38 participants was randomly assigned to either a head-mounted display (HMD) with motion tracker and sterescopic view condition or a one-screen projection-based virtual reality display condition. Participants in both conditions engaged in free speech dialogues with virtual humans controlled by research assistants. It was hypothesized that exposure to virtual social interactions will elicit moderate levels of sense of presence and anxiety in both groups. Further it was expected that participants in the HMD condition will report higher scores of sense of presence and anxiety than participants in the one-screen projection-based display condition. Results revealed that in both conditions virtual social interactions were associated with moderate levels of sense of presence and anxiety. Additionally, participants in the HMD condition reported significantly higher levels of presence than those in the one-screen projection-based display condition (p = .001). However, contrary to the expectations neither the average level of anxiety nor the highest level of anxiety during exposure to social virtual environments differed between the groups (p = .97 and p = .75, respectively). The findings suggest that virtual social interactions can be successfully applied in VRET to enhance sense of presence and anxiety. Furthermore, our results indicate that one-screen projection-based displays can successfully activate levels of anxiety in

  15. 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…

  16. 31 CFR 594.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Blocked account; blocked property. 594.301 Section 594.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY GLOBAL TERRORISM SANCTIONS...

  17. 31 CFR 545.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Blocked account; blocked property. 545.301 Section 545.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY TALIBAN (AFGHANISTAN) SANCTIONS...

  18. 31 CFR 551.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Blocked account; blocked property. 551.301 Section 551.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY SOMALIA SANCTIONS REGULATIONS...

  19. Toward the virtual classroom

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pihlman, M.; Dirks, D.H.

    1990-01-03

    The Lawrence Livermore National Laboratory (LLNL) encourages its employees to remotely attend classes given by Stanford University, University of California at Davis, and the National Technological University (NTU). To improve the quality of education for LLNL employees, we are cooperating with Stanford University in upgrading the Stanford Instructional Television Network (SITN). A dedicated high-speed communication link (Tl) between Stanford and LLNL will be used for enhanced services such as videoconferencing, real time classnotes distribution, and electronic distribution of homework assignments. The new network will also allow students to take classes from their offices with the ability to ask the professormore » questions via an automatically dialed telephone call. As part of this upgrade, we have also proposed a new videoconferencing based classroom environment where students taking remote classes would feel as though they are attending the live class. All paperwork would be available in near real time and students may converse normally with, and see, other remote students as though they were all in the same physical location. We call this the Virtual Classroom.'' 1 ref., 6 figs.« less

  20. Virtual tryout planning in automotive industry based on simulation metamodels

    NASA Astrophysics Data System (ADS)

    Harsch, D.; Heingärtner, J.; Hortig, D.; Hora, P.

    2016-11-01

    Deep drawn sheet metal parts are increasingly designed to the feasibility limit, thus achieving a robust manufacturing is often challenging. The fluctuation of process and material properties often lead to robustness problems. Therefore, numerical simulations are used to detect the critical regions. To enhance the agreement with the real process conditions, the material data are acquired through a variety of experiments. Furthermore, the force distribution is taken into account. The simulation metamodel contains the virtual knowledge of a particular forming process, which is determined based on a series of finite element simulations with variable input parameters. Based on the metamodels, virtual process windows can be displayed for different configurations. This helps to improve the operating point as well as to adjust process settings in case the process becomes unstable. Furthermore, the time of tool tryout can be shortened due to transfer of the virtual knowledge contained in the metamodels on the optimisation of the drawbeads. This allows the tool manufacturer to focus on the essential, to save time and to recognize complex relationships.

  1. MedBlock: Efficient and Secure Medical Data Sharing Via Blockchain.

    PubMed

    Fan, Kai; Wang, Shangyang; Ren, Yanhui; Li, Hui; Yang, Yintang

    2018-06-21

    With the development of electronic information technology, electronic medical records (EMRs) have been a common way to store the patients' data in hospitals. They are stored in different hospitals' databases, even for the same patient. Therefore, it is difficult to construct a summarized EMR for one patient from multiple hospital databases due to the security and privacy concerns. Meanwhile, current EMRs systems lack a standard data management and sharing policy, making it difficult for pharmaceutical scientists to develop precise medicines based on data obtained under different policies. To solve the above problems, we proposed a blockchain-based information management system, MedBlock, to handle patients' information. In this scheme, the distributed ledger of MedBlock allows the efficient EMRs access and EMRs retrieval. The improved consensus mechanism achieves consensus of EMRs without large energy consumption and network congestion. In addition, MedBlock also exhibits high information security combining the customized access control protocols and symmetric cryptography. MedBlock can play an important role in the sensitive medical information sharing.

  2. Ultrasound-guided genicular nerve block for pain control after total knee replacement: Preliminary case series and technical note.

    PubMed

    González Sotelo, V; Maculé, F; Minguell, J; Bergé, R; Franco, C; Sala-Blanch, X

    2017-12-01

    Total knee arthroplasty (TKA) is an operation with moderate to severe postoperative pain. The Fast-Track models employ local infiltration techniques with anaesthetics at high volumes (100-150ml). We proposed a genicular nerve block with low volume of local anaesthetic. The aim of our study is to evaluate the periarticular distribution of these blocks in a fresh cadaver model and to describe the technique in a preliminary group of patients submitted to TKA. In the anatomical phase, 4 genicular nerves (superior medial, superior lateral, inferior medial and inferior lateral) were blocked with 4ml of local anaesthetic with iodinated contrast and methylene blue in each (16ml in total). It was performed on a fresh cadaver and the distribution of the injected medium was evaluated by means of a CT-scan and coronal anatomical sections on both knees. The clinical phase included 12 patients scheduled for TKA. Ultrasound-guided block of the 4 genicular nerves was performed preoperatively and their clinical efficacy evaluated by assessing pain after the reversal of the spinal block and at 12h after the block. Pain was measured using the numerical scale and the need for rescue analgesia was evaluated. A wide periarticular distribution of contrast was observed by CT-scan, which was later evaluated in the coronal sections. The distribution followed the joint capsule without entering the joint, both in the femur and in the tibia. The pain after the reversal of the subarachnoid block was 2±1, requiring rescue analgesia in 42% of the patients. At 12h, the pain according to the numerical scale was 4±1, 33% required rescue analgesia. The administration of 4ml of local anaesthetic at the level of the 4 genicular nerves of the knee produces a wide periarticular distribution. Our preliminary data in a series of 12 patients undergoing TKA seems to be clinically effective. Nevertheless, extensive case series and comparative studies with local infiltration techniques with anaesthetics are

  3. Virtual Reality Tumor Resection: The Force Pyramid Approach.

    PubMed

    Sawaya, Robin; Bugdadi, Abdulgadir; Azarnoush, Hamed; Winkler-Schwartz, Alexander; Alotaibi, Fahad E; Bajunaid, Khalid; AlZhrani, Gmaan A; Alsideiri, Ghusn; Sabbagh, Abdulrahman J; Del Maestro, Rolando F

    2018-06-01

    The force pyramid is a novel visual representation allowing spatial delineation of instrument force application during surgical procedures. In this study, the force pyramid concept is employed to create and quantify dominant hand, nondominant hand, and bimanual force pyramids during resection of virtual reality brain tumors. To address 4 questions: Do ergonomics and handedness influence force pyramid structure? What are the differences between dominant and nondominant force pyramids? What is the spatial distribution of forces applied in specific tumor quadrants? What differentiates "expert" and "novice" groups regarding their force pyramids? Using a simulated aspirator in the dominant hand and a simulated sucker in the nondominant hand, 6 neurosurgeons and 14 residents resected 8 different tumors using the CAE NeuroVR virtual reality neurosurgical simulation platform (CAE Healthcare, Montréal, Québec and the National Research Council Canada, Boucherville, Québec). Position and force data were used to create force pyramids and quantify tumor quadrant force distribution. Force distribution quantification demonstrates the critical role that handedness and ergonomics play on psychomotor performance during simulated brain tumor resections. Neurosurgeons concentrate their dominant hand forces in a defined crescent in the lower right tumor quadrant. Nondominant force pyramids showed a central peak force application in all groups. Bimanual force pyramids outlined the combined impact of each hand. Distinct force pyramid patterns were seen when tumor stiffness, border complexity, and color were altered. Force pyramids allow delineation of specific tumor regions requiring greater psychomotor ability to resect. This information can focus and improve resident technical skills training.

  4. Exploring Virtual Reality for Classroom Use: The Virtual Reality and Education Lab at East Carolina University.

    ERIC Educational Resources Information Center

    Auld, Lawrence W. S.; Pantelidis, Veronica S.

    1994-01-01

    Describes the Virtual Reality and Education Lab (VREL) established at East Carolina University to study the implications of virtual reality for elementary and secondary education. Highlights include virtual reality software evaluation; hardware evaluation; computer-based curriculum objectives which could use virtual reality; and keeping current…

  5. 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.

  6. Inputs and spatial distribution patterns of Cr in Jiaozhou Bay

    NASA Astrophysics Data System (ADS)

    Yang, Dongfang; Miao, Zhenqing; Huang, Xinmin; Wei, Linzhen; Feng, Ming

    2018-03-01

    Cr pollution in marine bays has been one of the critical environmental issues, and understanding the input and spatial distribution patterns is essential to pollution control. In according to the source strengths of the major pollution sources, the input patterns of pollutants to marine bay include slight, moderate and heavy, and the spatial distribution are corresponding to three block models respectively. This paper analyzed input patterns and distributions of Cr in Jiaozhou Bay, eastern China based on investigation on Cr in surface waters during 1979-1983. Results showed that the input strengths of Cr in Jiaozhou Bay could be classified as moderate input and slight input, and the input strengths were 32.32-112.30 μg L-1 and 4.17-19.76 μg L-1, respectively. The input patterns of Cr included two patterns of moderate input and slight input, and the horizontal distributions could be defined by means of Block Model 2 and Block Model 3, respectively. In case of moderate input pattern via overland runoff, Cr contents were decreasing from the estuaries to the bay mouth, and the distribution pattern was parallel. In case of moderate input pattern via marine current, Cr contents were decreasing from the bay mouth to the bay, and the distribution pattern was parallel to circular. The Block Models were able to reveal the transferring process of various pollutants, and were helpful to understand the distributions of pollutants in marine bay.

  7. 31 CFR 594.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Blocked account; blocked property. 594.301 Section 594.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY GLOBAL TERRORISM SANCTIONS REGULATIONS...

  8. 31 CFR 594.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Blocked account; blocked property. 594.301 Section 594.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY GLOBAL TERRORISM SANCTIONS REGULATIONS...

  9. 31 CFR 594.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Blocked account; blocked property. 594.301 Section 594.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY GLOBAL TERRORISM SANCTIONS REGULATIONS...

  10. 31 CFR 546.302 - Blocked account; blocked property.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Blocked account; blocked property. 546.302 Section 546.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DARFUR SANCTIONS REGULATIONS General...

  11. 31 CFR 593.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Blocked account; blocked property. 593.301 Section 593.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FORMER LIBERIAN REGIME OF CHARLES...

  12. 31 CFR 510.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Blocked account; blocked property. 510.301 Section 510.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY NORTH KOREA SANCTIONS REGULATIONS General...

  13. 31 CFR 547.302 - Blocked account; blocked property.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Blocked account; blocked property. 547.302 Section 547.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DEMOCRATIC REPUBLIC OF THE CONGO...

  14. Target-induced formation of neuraminidase inhibitors from in vitro virtual combinatorial libraries

    PubMed Central

    Hochgürtel, Matthias; Kroth, Heiko; Piecha, Dorothea; Hofmann, Michael W.; Nicolau, Claude; Krause, Sonja; Schaaf, Otmar; Sonnenmoser, Gabriele; Eliseev, Alexey V.

    2002-01-01

    Neuraminidase, a key enzyme responsible for influenza virus propagation, has been used as a template for selective synthesis of small subsets of its own inhibitors from theoretically highly diverse dynamic combinatorial libraries. We show that the library building blocks, aldehydes and amines, form significant amounts of the library components resulting from their coupling by reductive amination only in the presence of the enzyme. The target amplifies the best hits at least 120-fold. The dynamic libraries synthesized and screened in such an in vitro virtual mode form the components that possess high inhibitory activity, as confirmed by enzyme assays with independently synthesized individual compounds. PMID:11891312

  15. Using the spatial distribution and lithology of ballistic blocks to interpret eruption sequence and dynamics: August 6 2012 Upper Te Maari eruption, New Zealand

    NASA Astrophysics Data System (ADS)

    Breard, E. C. P.; Lube, G.; Cronin, S. J.; Fitzgerald, R.; Kennedy, B.; Scheu, B.; Montanaro, C.; White, J. D. L.; Tost, M.; Procter, J. N.; Moebis, A.

    2014-10-01

    The ballistic ejection of blocks during explosive eruptions constitutes a major hazard near active volcanoes. Fields of ballistic clasts can provide important clues towards quantifying the energy, dynamics and directionality of explosive events, but detailed datasets are rare. During the 6 August 2012 hydrothermal eruption of Upper Te Maari (Tongariro), New Zealand, three explosions occurred in rapid succession within less than 20 s. The first two produced laterally-directed pyroclastic density currents (PDC), and the final vertical explosion generated an ash plume. Each of these explosions was associated with the ejection of ballistic blocks. We present detailed maps of the resulting 5.1 km2 block impact field and the distribution of the > 2200 impact craters with diameters > 2.5 m. There are two distinct regions of high crater concentration, where crater densities reach more than six times the average background density. These occur at distances of 500-700 m east and 1000-1350 west of a 430-m-long fissure that was created during the eruption. The high-density fields are characterized by a narrow radial spread of < 45° and are located along the proximal transport direction of the pyroclastic density currents. A provenance analysis of ballistic blocks allowed us to reconstruct two different eruptive vents for the explosions. The first two laterally-directed explosions were sourced from the fissure, while the third explosion occurred through the pre-existing Upper Te Maari Crater, generating a roughly axisymmetric shower of ballistics. Stratigraphic relationships between impact craters, PDC and fall deposits suggest that the ballistic blocks were initially coupled with the rapidly expanding gas-particle mixtures that produced the PDCs. Ballistic trajectory modeling, reproducing the lateral extent and main impact density pattern of the western impact field, allows estimation of the vertical expansion angle of the second and largest explosion. The calculations show

  16. Medial approach of ultrasound-guided costoclavicular plexus block and its effects on regional perfussion.

    PubMed

    Nieuwveld, D; Mojica, V; Herrera, A E; Pomés, J; Prats, A; Sala-Blanch, X

    2017-04-01

    Ultrasound-guided infraclavicular block in the costoclavicular space located between the clavicle and the first rib, reaches the secondary trunks when they are clustered together and lateral to the axillary artery. This block is most often performed through a lateral approach, the difficulty being finding the coracoid process an obstacle and guiding the needle towards the vessels and pleura. A medial approach, meaning from inside to outside, will avoid these structures. Traditionally the assessment of a successful block is through motor or sensitive responses but a sympathetic fibre block can also be evaluated measuring the changes in humeral artery blood flow, skin temperature and/or perfusion index. To describe the medial approach of the ultrasound-guided costoclavicular block evaluating its development by motor and sensitive response and measurement of sympathetic changes. Description of the technique and administration of 20ml of contrast in a fresh cadaver model, evaluating the distribution with CT-scan and sagittal sections of the anatomic piece. Subsequently in a clinical phase, including 11 patients, we evaluated the establishment of motor, sensitive and sympathetic blocks. We evaluated the sympathetic changes reflected by humeral artery blood flow, skin temperature and distal perfusion index. In the anatomical model the block was conducted without difficulties, showing an adequate periclavicular distribution of the contrast in the CT-scan and in sagittal sections, reaching the interscalenic space as far as the secondary trunks. Successful blocks were observed in 91% of patients after 25minutes. All the parameters reflecting sympathetic block increased significantly. The humeral artery blood flow showed an increase from 108 ± 86 to 188±141ml/min (P=.05), skin temperature from 32.1±2 to 32.8±9°C (P=.03) and perfusion index from 4±3 to 9±5 (P=.003). The medial approach of the ultrasound-guided costoclavicular block is anatomically feasible, with high

  17. Model-Atmosphere Spectra of Central Stars of Planetary Nebulae - Access via the Virtual Observatory Service TheoSSA

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Reindl, N.

    2014-04-01

    In the framework of the Virtual Observatory (VO), the German Astrophysical Virtual Observatory GAVO project provides easy access to theoretical spectral energy distributions (SEDs) within the registered GAVO service TheoSSA (http://dc.g-vo.org/theossa). TheoSSA is based on the well established Tübingen NLTE Model-Atmosphere Package (TMAP) for hot, compact stars. This includes central stars of planetary nebulae. We show examples of TheoSSA in operation.

  18. 31 CFR 593.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Blocked account; blocked property. 593.301 Section 593.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FORMER LIBERIAN REGIME OF CHARLES TAYLOR...

  19. 31 CFR 593.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Blocked account; blocked property. 593.301 Section 593.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FORMER LIBERIAN REGIME OF CHARLES TAYLOR...

  20. 31 CFR 593.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Blocked account; blocked property. 593.301 Section 593.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FORMER LIBERIAN REGIME OF CHARLES TAYLOR...

  1. 31 CFR 593.301 - Blocked account; blocked property.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Blocked account; blocked property. 593.301 Section 593.301 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY FORMER LIBERIAN REGIME OF CHARLES TAYLOR...

  2. 31 CFR 547.302 - Blocked account; blocked property.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance:Treasury 3 2014-07-01 2014-07-01 false Blocked account; blocked property. 547.302 Section 547.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DEMOCRATIC REPUBLIC OF THE CONGO SANCTIONS...

  3. 31 CFR 547.302 - Blocked account; blocked property.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance:Treasury 3 2012-07-01 2012-07-01 false Blocked account; blocked property. 547.302 Section 547.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DEMOCRATIC REPUBLIC OF THE CONGO SANCTIONS...

  4. 31 CFR 547.302 - Blocked account; blocked property.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance:Treasury 3 2011-07-01 2011-07-01 false Blocked account; blocked property. 547.302 Section 547.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DEMOCRATIC REPUBLIC OF THE CONGO SANCTIONS...

  5. 31 CFR 547.302 - Blocked account; blocked property.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance:Treasury 3 2013-07-01 2013-07-01 false Blocked account; blocked property. 547.302 Section 547.302 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY DEMOCRATIC REPUBLIC OF THE CONGO SANCTIONS...

  6. Preparation and development of block copolypeptide vesicles and hydrogels for biological and medical applications.

    PubMed

    Deming, Timothy J

    2014-01-01

    There have been many recent advances in the controlled polymerization of α-amino acid-N-carboxyanhydride (NCA) monomers into well-defined block copolypeptides. Transition metal initiating systems allow block copolypeptide synthesis with excellent control over number and lengths of block segments, chain length distribution, and chain-end functionality. Using this and other methods, block copolypeptides of controlled dimensions have been prepared and their self-assembly into organized structures studied by many research groups. The ability of well-defined block copolypeptides to assemble into supramolecular copolypeptide vesicles and hydrogels has led to the development of these materials for use in biological and medical applications. These assemblies have been found to possess unique properties that are derived from the amino acid building blocks and ordered conformations of the polypeptide segments. Recent work on the incorporation of active and stimulus-responsive functionality in these materials has tremendously increased their potential for use in biological and medical studies. © 2014 Wiley Periodicals, Inc.

  7. Manuscript Architect: a Web application for scientific writing in virtual interdisciplinary groups

    PubMed Central

    Pietrobon, Ricardo; Nielsen, Karen C; Steele, Susan M; Menezes, Andreia P; Martins, Henrique; Jacobs, Danny O

    2005-01-01

    Background Although scientific writing plays a central role in the communication of clinical research findings and consumes a significant amount of time from clinical researchers, few Web applications have been designed to systematically improve the writing process. This application had as its main objective the separation of the multiple tasks associated with scientific writing into smaller components. It was also aimed at providing a mechanism where sections of the manuscript (text blocks) could be assigned to different specialists. Manuscript Architect was built using Java language in conjunction with the classic lifecycle development method. The interface was designed for simplicity and economy of movements. Manuscripts are divided into multiple text blocks that can be assigned to different co-authors by the first author. Each text block contains notes to guide co-authors regarding the central focus of each text block, previous examples, and an additional field for translation when the initial text is written in a language different from the one used by the target journal. Usability was evaluated using formal usability tests and field observations. Results The application presented excellent usability and integration with the regular writing habits of experienced researchers. Workshops were developed to train novice researchers, presenting an accelerated learning curve. The application has been used in over 20 different scientific articles and grant proposals. Conclusion The current version of Manuscript Architect has proven to be very useful in the writing of multiple scientific texts, suggesting that virtual writing by interdisciplinary groups is an effective manner of scientific writing when interdisciplinary work is required. PMID:15960855

  8. Virtual detector theory for strong-field atomic ionization

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Tian, Justin; Eberly, J. H.

    2018-04-01

    A virtual detector (VD) is an imaginary device located at a fixed position in space that extracts information from the wave packet passing through it. By recording the particle momentum and the corresponding probability current at each time, the VDs can accumulate and build the differential momentum distribution of the particle, in a way that resembles real experiments. A mathematical proof is given for the equivalence of the differential momentum distribution obtained by the VD method and by Fourier transforming the wave function. In addition to being a tool for reducing the computational load, VDs have also been found useful in interpreting the ultrafast strong-field ionization process, especially the controversial quantum tunneling process.

  9. Virtual Patients on the Semantic Web: A Proof-of-Application Study

    PubMed Central

    Dafli, Eleni; Antoniou, Panagiotis; Ioannidis, Lazaros; Dombros, Nicholas; Topps, David

    2015-01-01

    Background Virtual patients are interactive computer simulations that are increasingly used as learning activities in modern health care education, especially in teaching clinical decision making. A key challenge is how to retrieve and repurpose virtual patients as unique types of educational resources between different platforms because of the lack of standardized content-retrieving and repurposing mechanisms. Semantic Web technologies provide the capability, through structured information, for easy retrieval, reuse, repurposing, and exchange of virtual patients between different systems. Objective An attempt to address this challenge has been made through the mEducator Best Practice Network, which provisioned frameworks for the discovery, retrieval, sharing, and reuse of medical educational resources. We have extended the OpenLabyrinth virtual patient authoring and deployment platform to facilitate the repurposing and retrieval of existing virtual patient material. Methods A standalone Web distribution and Web interface, which contains an extension for the OpenLabyrinth virtual patient authoring system, was implemented. This extension was designed to semantically annotate virtual patients to facilitate intelligent searches, complex queries, and easy exchange between institutions. The OpenLabyrinth extension enables OpenLabyrinth authors to integrate and share virtual patient case metadata within the mEducator3.0 network. Evaluation included 3 successive steps: (1) expert reviews; (2) evaluation of the ability of health care professionals and medical students to create, share, and exchange virtual patients through specific scenarios in extended OpenLabyrinth (OLabX); and (3) evaluation of the repurposed learning objects that emerged from the procedure. Results We evaluated 30 repurposed virtual patient cases. The evaluation, with a total of 98 participants, demonstrated the system’s main strength: the core repurposing capacity. The extensive metadata schema

  10. Virtual patients on the semantic Web: a proof-of-application study.

    PubMed

    Dafli, Eleni; Antoniou, Panagiotis; Ioannidis, Lazaros; Dombros, Nicholas; Topps, David; Bamidis, Panagiotis D

    2015-01-22

    Virtual patients are interactive computer simulations that are increasingly used as learning activities in modern health care education, especially in teaching clinical decision making. A key challenge is how to retrieve and repurpose virtual patients as unique types of educational resources between different platforms because of the lack of standardized content-retrieving and repurposing mechanisms. Semantic Web technologies provide the capability, through structured information, for easy retrieval, reuse, repurposing, and exchange of virtual patients between different systems. An attempt to address this challenge has been made through the mEducator Best Practice Network, which provisioned frameworks for the discovery, retrieval, sharing, and reuse of medical educational resources. We have extended the OpenLabyrinth virtual patient authoring and deployment platform to facilitate the repurposing and retrieval of existing virtual patient material. A standalone Web distribution and Web interface, which contains an extension for the OpenLabyrinth virtual patient authoring system, was implemented. This extension was designed to semantically annotate virtual patients to facilitate intelligent searches, complex queries, and easy exchange between institutions. The OpenLabyrinth extension enables OpenLabyrinth authors to integrate and share virtual patient case metadata within the mEducator3.0 network. Evaluation included 3 successive steps: (1) expert reviews; (2) evaluation of the ability of health care professionals and medical students to create, share, and exchange virtual patients through specific scenarios in extended OpenLabyrinth (OLabX); and (3) evaluation of the repurposed learning objects that emerged from the procedure. We evaluated 30 repurposed virtual patient cases. The evaluation, with a total of 98 participants, demonstrated the system's main strength: the core repurposing capacity. The extensive metadata schema presentation facilitated user exploration

  11. Seamless 3D interaction for virtual tables, projection planes, and CAVEs

    NASA Astrophysics Data System (ADS)

    Encarnacao, L. M.; Bimber, Oliver; Schmalstieg, Dieter; Barton, Robert J., III

    2000-08-01

    The Virtual Table presents stereoscopic graphics to a user in a workbench-like setting. This device shares with other large- screen display technologies (such as data walls and surround- screen projection systems) the lack of human-centered unencumbered user interfaces and 3D interaction technologies. Such shortcomings present severe limitations to the application of virtual reality (VR) technology to time- critical applications as well as employment scenarios that involve heterogeneous groups of end-users without high levels of computer familiarity and expertise. Traditionally such employment scenarios are common in planning-related application areas such as mission rehearsal and command and control. For these applications, a high grade of flexibility with respect to the system requirements (display and I/O devices) as well as to the ability to seamlessly and intuitively switch between different interaction modalities and interaction are sought. Conventional VR techniques may be insufficient to meet this challenge. This paper presents novel approaches for human-centered interfaces to Virtual Environments focusing on the Virtual Table visual input device. It introduces new paradigms for 3D interaction in virtual environments (VE) for a variety of application areas based on pen-and-clipboard, mirror-in-hand, and magic-lens metaphors, and introduces new concepts for combining VR and augmented reality (AR) techniques. It finally describes approaches toward hybrid and distributed multi-user interaction environments and concludes by hypothesizing on possible use cases for defense applications.

  12. An Analysis of Hardware-Assisted Virtual Machine Based Rootkits

    DTIC Science & Technology

    2014-06-01

    certain aspects of TPM implementation just to name a few. HyperWall is an architecture proposed by Szefer and Lee to protect guest VMs from...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) The use of virtual machine (VM) technology has expanded rapidly since AMD and Intel implemented ...Intel VT-x implementations of Blue Pill to identify commonalities in the respective versions’ attack methodologies from both a functional and technical

  13. Liberating Virtual Machines from Physical Boundaries through Execution Knowledge

    DTIC Science & Technology

    2015-12-01

    trivial infrastructures such as VM distribution networks, clients need to wait for an extended period of time before launching a VM. In cloud settings...hardware support. MobiDesk [28] efficiently supports virtual desktops in mobile environments by decou- pling the user’s workload from host systems and...experiment set-up. VMs are migrated between a pair of source and destination hosts, which are connected through a backend 10 Gbps network for

  14. Varieties of virtualization

    NASA Technical Reports Server (NTRS)

    Ellis, Stephen R.

    1991-01-01

    Natural environments have a content, i.e., the objects in them; a geometry, i.e., a pattern of rules for positioning and displacing the objects; and a dynamics, i.e., a system of rules describing the effects of forces acting on the objects. Human interaction with most common natural environments has been optimized by centuries of evolution. Virtual environments created through the human-computer interface similarly have a content, geometry, and dynamics, but the arbitrary character of the computer simulation creating them does not insure that human interaction with these virtual environments will be natural. The interaction, indeed, could be supernatural but it also could be impossible. An important determinant of the comprehensibility of a virtual environment is the correspondence between the environmental frames of reference and those associated with the control of environmental objects. The effects of rotation and displacement of control frames of reference with respect to corresponding environmental references differ depending upon whether perceptual judgement or manual tracking performance is measured. The perceptual effects of frame of reference displacement may be analyzed in terms of distortions in the process of virtualizing the synthetic environment space. The effects of frame of reference displacement and rotation have been studied by asking subjects to estimate exocentric direction in a virtual space.

  15. RandomSpot: A web-based tool for systematic random sampling of virtual slides.

    PubMed

    Wright, Alexander I; Grabsch, Heike I; Treanor, Darren E

    2015-01-01

    This paper describes work presented at the Nordic Symposium on Digital Pathology 2014, Linköping, Sweden. Systematic random sampling (SRS) is a stereological tool, which provides a framework to quickly build an accurate estimation of the distribution of objects or classes within an image, whilst minimizing the number of observations required. RandomSpot is a web-based tool for SRS in stereology, which systematically places equidistant points within a given region of interest on a virtual slide. Each point can then be visually inspected by a pathologist in order to generate an unbiased sample of the distribution of classes within the tissue. Further measurements can then be derived from the distribution, such as the ratio of tumor to stroma. RandomSpot replicates the fundamental principle of traditional light microscope grid-shaped graticules, with the added benefits associated with virtual slides, such as facilitated collaboration and automated navigation between points. Once the sample points have been added to the region(s) of interest, users can download the annotations and view them locally using their virtual slide viewing software. Since its introduction, RandomSpot has been used extensively for international collaborative projects, clinical trials and independent research projects. So far, the system has been used to generate over 21,000 sample sets, and has been used to generate data for use in multiple publications, identifying significant new prognostic markers in colorectal, upper gastro-intestinal and breast cancer. Data generated using RandomSpot also has significant value for training image analysis algorithms using sample point coordinates and pathologist classifications.

  16. Global effects of local food-production crises: a virtual water perspective

    PubMed Central

    Tamea, Stefania; Laio, Francesco; Ridolfi, Luca

    2016-01-01

    By importing food and agricultural goods, countries cope with the heterogeneous global water distribution and often rely on water resources available abroad. The virtual displacement of the water used to produce such goods (known as virtual water) connects together, in a global water system, all countries participating to the international trade network. Local food-production crises, having social, economic or environmental origin, propagate in this network, modifying the virtual water trade and perturbing local and global food availability, quantified in terms of virtual water. We analyze here the possible effects of local crises by developing a new propagation model, parsimonious but grounded on data-based and statistically-verified assumptions, whose effectiveness is proved on the Argentinean crisis in 2008–09. The model serves as the basis to propose indicators of crisis impact and country vulnerability to external food-production crises, which highlight that countries with largest water resources have the highest impact on the international trade, and that not only water-scarce but also wealthy and globalized countries are among the most vulnerable to external crises. The temporal analysis reveals that global average vulnerability has increased over time and that stronger effects of crises are now found in countries with low food (and water) availability. PMID:26804492

  17. Global effects of local food-production crises: a virtual water perspective.

    PubMed

    Tamea, Stefania; Laio, Francesco; Ridolfi, Luca

    2016-01-25

    By importing food and agricultural goods, countries cope with the heterogeneous global water distribution and often rely on water resources available abroad. The virtual displacement of the water used to produce such goods (known as virtual water) connects together, in a global water system, all countries participating to the international trade network. Local food-production crises, having social, economic or environmental origin, propagate in this network, modifying the virtual water trade and perturbing local and global food availability, quantified in terms of virtual water. We analyze here the possible effects of local crises by developing a new propagation model, parsimonious but grounded on data-based and statistically-verified assumptions, whose effectiveness is proved on the Argentinean crisis in 2008-09. The model serves as the basis to propose indicators of crisis impact and country vulnerability to external food-production crises, which highlight that countries with largest water resources have the highest impact on the international trade, and that not only water-scarce but also wealthy and globalized countries are among the most vulnerable to external crises. The temporal analysis reveals that global average vulnerability has increased over time and that stronger effects of crises are now found in countries with low food (and water) availability.

  18. Global effects of local food-production crises: a virtual water perspective

    NASA Astrophysics Data System (ADS)

    Tamea, Stefania; Laio, Francesco; Ridolfi, Luca

    2016-01-01

    By importing food and agricultural goods, countries cope with the heterogeneous global water distribution and often rely on water resources available abroad. The virtual displacement of the water used to produce such goods (known as virtual water) connects together, in a global water system, all countries participating to the international trade network. Local food-production crises, having social, economic or environmental origin, propagate in this network, modifying the virtual water trade and perturbing local and global food availability, quantified in terms of virtual water. We analyze here the possible effects of local crises by developing a new propagation model, parsimonious but grounded on data-based and statistically-verified assumptions, whose effectiveness is proved on the Argentinean crisis in 2008-09. The model serves as the basis to propose indicators of crisis impact and country vulnerability to external food-production crises, which highlight that countries with largest water resources have the highest impact on the international trade, and that not only water-scarce but also wealthy and globalized countries are among the most vulnerable to external crises. The temporal analysis reveals that global average vulnerability has increased over time and that stronger effects of crises are now found in countries with low food (and water) availability.

  19. Virtual Reality-Based Center of Mass-Assisted Personalized Balance Training System

    PubMed Central

    Kumar, Deepesh; González, Alejandro; Das, Abhijit; Dutta, Anirban; Fraisse, Philippe; Hayashibe, Mitsuhiro; Lahiri, Uttama

    2018-01-01

    Poststroke hemiplegic patients often show altered weight distribution with balance disorders, increasing their risk of fall. Conventional balance training, though powerful, suffers from scarcity of trained therapists, frequent visits to clinics to get therapy, one-on-one therapy sessions, and monotony of repetitive exercise tasks. Thus, technology-assisted balance rehabilitation can be an alternative solution. Here, we chose virtual reality as a technology-based platform to develop motivating balance tasks. This platform was augmented with off-the-shelf available sensors such as Nintendo Wii balance board and Kinect to estimate one’s center of mass (CoM). The virtual reality-based CoM-assisted balance tasks (Virtual CoMBaT) was designed to be adaptive to one’s individualized weight-shifting capability quantified through CoM displacement. Participants were asked to interact with Virtual CoMBaT that offered tasks of varying challenge levels while adhering to ankle strategy for weight shifting. To facilitate the patients to use ankle strategy during weight-shifting, we designed a heel lift detection module. A usability study was carried out with 12 hemiplegic patients. Results indicate the potential of our system to contribute to improving one’s overall performance in balance-related tasks belonging to different difficulty levels. PMID:29359128

  20. Virtual Reality-Based Center of Mass-Assisted Personalized Balance Training System.

    PubMed

    Kumar, Deepesh; González, Alejandro; Das, Abhijit; Dutta, Anirban; Fraisse, Philippe; Hayashibe, Mitsuhiro; Lahiri, Uttama

    2017-01-01

    Poststroke hemiplegic patients often show altered weight distribution with balance disorders, increasing their risk of fall. Conventional balance training, though powerful, suffers from scarcity of trained therapists, frequent visits to clinics to get therapy, one-on-one therapy sessions, and monotony of repetitive exercise tasks. Thus, technology-assisted balance rehabilitation can be an alternative solution. Here, we chose virtual reality as a technology-based platform to develop motivating balance tasks. This platform was augmented with off-the-shelf available sensors such as Nintendo Wii balance board and Kinect to estimate one's center of mass (CoM). The virtual reality-based CoM-assisted balance tasks (Virtual CoMBaT) was designed to be adaptive to one's individualized weight-shifting capability quantified through CoM displacement. Participants were asked to interact with Virtual CoMBaT that offered tasks of varying challenge levels while adhering to ankle strategy for weight shifting. To facilitate the patients to use ankle strategy during weight-shifting, we designed a heel lift detection module. A usability study was carried out with 12 hemiplegic patients. Results indicate the potential of our system to contribute to improving one's overall performance in balance-related tasks belonging to different difficulty levels.

  1. Concrete Block Pavements

    DTIC Science & Technology

    1983-03-01

    concrete paving block ( Van der Vlist 1980). The concrete paving block was readily accepted as a substitute for the scarce paving brick and today has...seen in Figure 4, its growth.has been steady ( Van der Vlist 1980). 20 15 0< 0. n 10 1𔃺 978 960 1 62 63 64 65 66 67 68 6970 71 72 73 74 7678 7778 79...Figure 4. Concrete paving block production in the Netherlands ( Van der Vlist 1980) 8. The use of concrete paving block in the Netherlands developedI

  2. Airport Simulations Using Distributed Computational Resources

    NASA Technical Reports Server (NTRS)

    McDermott, William J.; Maluf, David A.; Gawdiak, Yuri; Tran, Peter; Clancy, Daniel (Technical Monitor)

    2002-01-01

    The Virtual National Airspace Simulation (VNAS) will improve the safety of Air Transportation. In 2001, using simulation and information management software running over a distributed network of super-computers, researchers at NASA Ames, Glenn, and Langley Research Centers developed a working prototype of a virtual airspace. This VNAS prototype modeled daily operations of the Atlanta airport by integrating measured operational data and simulation data on up to 2,000 flights a day. The concepts and architecture developed by NASA for this prototype are integral to the National Airspace Simulation to support the development of strategies improving aviation safety, identifying precursors to component failure.

  3. Cooperation, Coordination, and Trust in Virtual Teams: Insights from Virtual Games

    NASA Astrophysics Data System (ADS)

    Korsgaard, M. Audrey; Picot, Arnold; Wigand, Rolf T.; Welpe, Isabelle M.; Assmann, Jakob J.

    This chapter considers fundamental concepts of effective virtual teams, illustrated by research on Travian, a massively multiplayer online strategy game wherein players seek to build empires. Team inputs are the resources that enable individuals to work interdependently toward a common goal, including individual and collective capabilities, shared knowledge structures, and leadership style. Team processes, notably coordination and cooperation, transform team inputs to desired collective outcomes. Because the members of virtual teams are geographically dispersed, relying on information and communication technology, three theories are especially relevant for understanding how they can function effectively: social presence theory, media richness theory, and media synchronicity theory. Research in settings like Travian can inform our understanding of structures, processes, and performance of virtual teams. Such research could provide valuable insight into the emergence and persistence of trust and cooperation, as well as the impact of different communication media for coordination and information management in virtual organizations.

  4. Mobile access to virtual randomization for investigator-initiated trials.

    PubMed

    Deserno, Thomas M; Keszei, András P

    2017-08-01

    Background/aims Randomization is indispensable in clinical trials in order to provide unbiased treatment allocation and a valid statistical inference. Improper handling of allocation lists can be avoided using central systems, for example, human-based services. However, central systems are unaffordable for investigator-initiated trials and might be inaccessible from some places, where study subjects need allocations. We propose mobile access to virtual randomization, where the randomization lists are non-existent and the appropriate allocation is computed on demand. Methods The core of the system architecture is an electronic data capture system or a clinical trial management system, which is extended by an R interface connecting the R server using the Java R Interface. Mobile devices communicate via the representational state transfer web services. Furthermore, a simple web-based setup allows configuring the appropriate statistics by non-statisticians. Our comprehensive R script supports simple randomization, restricted randomization using a random allocation rule, block randomization, and stratified randomization for un-blinded, single-blinded, and double-blinded trials. For each trial, the electronic data capture system or the clinical trial management system stores the randomization parameters and the subject assignments. Results Apps are provided for iOS and Android and subjects are randomized using smartphones. After logging onto the system, the user selects the trial and the subject, and the allocation number and treatment arm are displayed instantaneously and stored in the core system. So far, 156 subjects have been allocated from mobile devices serving five investigator-initiated trials. Conclusion Transforming pre-printed allocation lists into virtual ones ensures the correct conduct of trials and guarantees a strictly sequential processing in all trial sites. Covering 88% of all randomization models that are used in recent trials, virtual randomization

  5. Virtual Violence.

    PubMed

    2016-08-01

    In the United States, exposure to media violence is becoming an inescapable component of children's lives. With the rise in new technologies, such as tablets and new gaming platforms, children and adolescents increasingly are exposed to what is known as "virtual violence." This form of violence is not experienced physically; rather, it is experienced in realistic ways via new technology and ever more intense and realistic games. The American Academy of Pediatrics continues to be concerned about children's exposure to virtual violence and the effect it has on their overall health and well-being. This policy statement aims to summarize the current state of scientific knowledge regarding the effects of virtual violence on children's attitudes and behaviors and to make specific recommendations for pediatricians, parents, industry, and policy makers. Copyright © 2016 by the American Academy of Pediatrics.

  6. Transversus abdominis plane block vs. wound infiltration in Caesarean section: a randomised controlled trial.

    PubMed

    Telnes, A; Skogvoll, E; Lonnée, H

    2015-04-01

    Multiple studies suggest that transversus abdominis plane (TAP) block (without intrathecal morphine) after Caesarean section (CS) reduces post-operative morphine consumption. In our study, we wanted to compare the analgesic effect of TAP block with infiltration of the wound after CS. We included 60 pregnant women scheduled for elective CS under spinal anaesthesia in a randomised, single-centre, double-blind study. Thirty patients received ultrasound-guided TAP block using 20 ml bupivacaine 0.25% with adrenaline 5 μg/ml bilaterally and 20 ml normal saline as wound infiltration (TAP group). The other 30 patients (the control group) received normal saline 20 ml bilaterally in the TAP, and 20 ml bupivacaine 0.25% with adrenaline 5 μg/ml as wound infiltration. The main outcome was cumulative morphine consumption at 48 h after surgery. In addition, continuous morphine consumption, pain scores and side effects were registered. Fifty-seven patients completed the study. Cumulative morphine consumption at 48 h (mean±standard deviation) was 41±34 mg in the TAP group and 38±27 mg in the control group (P=0.7); a difference of 3 mg (95% confidence interval -13 to 19 mg). Morphine consumption at any time up to 48 h was virtually identical in both groups. Side effects were similar, except for a higher degree of sedation in the TAP group (P=0.04). Compared with wound infiltration with local anaesthetics, TAP block did not reduce cumulative morphine consumption following CS. The TAP block was associated with more pronounced sedation. © 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  7. Shifty: A Weight-Shifting Dynamic Passive Haptic Proxy to Enhance Object Perception in Virtual Reality.

    PubMed

    Zenner, Andre; Kruger, Antonio

    2017-04-01

    We define the concept of Dynamic Passive Haptic Feedback (DPHF) for virtual reality by introducing the weight-shifting physical DPHF proxy object Shifty. This concept combines actuators known from active haptics and physical proxies known from passive haptics to construct proxies that automatically adapt their passive haptic feedback. We describe the concept behind our ungrounded weight-shifting DPHF proxy Shifty and the implementation of our prototype. We then investigate how Shifty can, by automatically changing its internal weight distribution, enhance the user's perception of virtual objects interacted with in two experiments. In a first experiment, we show that Shifty can enhance the perception of virtual objects changing in shape, especially in length and thickness. Here, Shifty was shown to increase the user's fun and perceived realism significantly, compared to an equivalent passive haptic proxy. In a second experiment, Shifty is used to pick up virtual objects of different virtual weights. The results show that Shifty enhances the perception of weight and thus the perceived realism by adapting its kinesthetic feedback to the picked-up virtual object. In the same experiment, we additionally show that specific combinations of haptic, visual and auditory feedback during the pick-up interaction help to compensate for visual-haptic mismatch perceived during the shifting process.

  8. Needs analysis for developing a virtual-reality NOTES simulator.

    PubMed

    Sankaranarayanan, Ganesh; Matthes, Kai; Nemani, Arun; Ahn, Woojin; Kato, Masayuki; Jones, Daniel B; Schwaitzberg, Steven; De, Suvranu

    2013-05-01

    INTRODUCTION AND STUDY AIM: Natural orifice translumenal endoscopic surgery (NOTES) is an emerging surgical technique that requires a cautious adoption approach to ensure patient safety. High-fidelity virtual-reality-based simulators allow development of new surgical procedures and tools and train medical personnel without risk to human patients. As part of a project funded by the National Institutes of Health, we are developing the virtual transluminal endoscopic surgery trainer (VTEST) for this purpose. The objective of this study is to conduct a structured needs analysis to identify the design parameters for such a virtual-reality-based simulator for NOTES. A 30-point questionnaire was distributed at the 2011 National Orifice Surgery Consortium for Assessment and Research meeting to obtain responses from experts. Ordinal logistic regression and the Wilcoxon rank-sum test were used for analysis. A total of 22 NOTES experts participated in the study. Cholecystectomy (CE, 68 %) followed by appendectomy (AE, 63 %) (CE vs AE, p = 0.0521) was selected as the first choice for simulation. Flexible (FL, 47 %) and hybrid (HY, 47 %) approaches were equally favorable compared with rigid (RI, 6 %) with p < 0.001 for both FL versus RI and HY versus RI. The transvaginal approach was preferred 3 to 1 to the transgastric. Most participants preferred two-channel (2C) scopes (65 %) compared with single (1C) or three (3C) or more channels with p < 0.001 for both 2C versus 1C and 2C versus 3C. The importance of force feedback and the utility of a virtual NOTES simulator in training and testing new tools for NOTES were rated very high by the participants. Our study reinforces the importance of developing a virtual NOTES simulator and clearly presents expert preferences. The results of this analysis will direct our initial development of the VTEST platform.

  9. Virtual Organizations: An Overview

    NASA Astrophysics Data System (ADS)

    Nami, Mohammad Reza

    The need to remain competitive in the open market forces companies to concentrate on their core competencies while searching for alliances when additional skills or resources are needed to fulfill business opportunities. The changing business situation of companies and customer needs have motivated researchers to introduce Virtual Organization (VO) idea. A Virtual Organization is always a form of partnership and managing partners and handling partnerships are crucial. Virtual organizations are defined as a temporary collection of enterprises that cooperate and share resources, knowledge, and competencies to better respond to business opportunities. This paper presents base concepts of virtual organizations including properties, management concepts, operational concepts, and main issues in collaboration such as security and authentication.

  10. Dynamic data distributions in Vienna Fortran

    NASA Technical Reports Server (NTRS)

    Chapman, Barbara; Mehrotra, Piyush; Moritsch, Hans; Zima, Hans

    1993-01-01

    Vienna Fortran is a machine-independent language extension of Fortran, which is based upon the Single-Program-Multiple-Data (SPMD) paradigm and allows the user to write programs for distributed-memory systems using global addresses. The language features focus mainly on the issue of distributing data across virtual processor structures. Those features of Vienna Fortran that allow the data distributions of arrays to change dynamically, depending on runtime conditions are discussed. The relevant language features are discussed, their implementation is outlined, and how they may be used in applications is described.

  11. Supporting Distributed Team Working in 3D Virtual Worlds: A Case Study in Second Life

    ERIC Educational Resources Information Center

    Minocha, Shailey; Morse, David R.

    2010-01-01

    Purpose: The purpose of this paper is to report on a study into how a three-dimensional (3D) virtual world (Second Life) can facilitate socialisation and team working among students working on a team project at a distance. This models the situation in many commercial sectors where work is increasingly being conducted across time zones and between…

  12. Tomography for two-dimensional gas temperature distribution based on TDLAS

    NASA Astrophysics Data System (ADS)

    Luo, Can; Wang, Yunchu; Xing, Fei

    2018-03-01

    Based on tunable diode laser absorption spectroscopy (TDLAS), the tomography is used to reconstruct the combustion gas temperature distribution. The effects of number of rays, number of grids, and spacing of rays on the temperature reconstruction results for parallel ray are researched. The reconstruction quality is proportional to the ray number. The quality tends to be smoother when the ray number exceeds a certain value. The best quality is achieved when η is between 0.5 and 1. A virtual ray method combined with the reconstruction algorithms is tested. It is found that virtual ray method is effective to improve the accuracy of reconstruction results, compared with the original method. The linear interpolation method and cubic spline interpolation method, are used to improve the calculation accuracy of virtual ray absorption value. According to the calculation results, cubic spline interpolation is better. Moreover, the temperature distribution of a TBCC combustion chamber is used to validate those conclusions.

  13. A novel resource sharing algorithm based on distributed construction for radiant enclosure problems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Finzell, Peter; Bryden, Kenneth M.

    This study demonstrates a novel approach to solving inverse radiant enclosure problems based on distributed construction. Specifically, the problem of determining the temperature distribution needed on the heater surfaces to achieve a desired design surface temperature profile is recast as a distributed construction problem in which a shared resource, temperature, is distributed by computational agents moving blocks. The sharing of blocks between agents enables them to achieve their desired local state, which in turn achieves the desired global state. Each agent uses the current state of their local environment and a simple set of rules to determine when to exchangemore » blocks, each block representing a discrete unit of temperature change. This algorithm is demonstrated using the established two-dimensional inverse radiation enclosure problem. The temperature profile on the heater surfaces is adjusted to achieve a desired temperature profile on the design surfaces. The resource sharing algorithm was able to determine the needed temperatures on the heater surfaces to obtain the desired temperature distribution on the design surfaces in the nine cases examined.« less

  14. A novel resource sharing algorithm based on distributed construction for radiant enclosure problems

    DOE PAGES

    Finzell, Peter; Bryden, Kenneth M.

    2017-03-06

    This study demonstrates a novel approach to solving inverse radiant enclosure problems based on distributed construction. Specifically, the problem of determining the temperature distribution needed on the heater surfaces to achieve a desired design surface temperature profile is recast as a distributed construction problem in which a shared resource, temperature, is distributed by computational agents moving blocks. The sharing of blocks between agents enables them to achieve their desired local state, which in turn achieves the desired global state. Each agent uses the current state of their local environment and a simple set of rules to determine when to exchangemore » blocks, each block representing a discrete unit of temperature change. This algorithm is demonstrated using the established two-dimensional inverse radiation enclosure problem. The temperature profile on the heater surfaces is adjusted to achieve a desired temperature profile on the design surfaces. The resource sharing algorithm was able to determine the needed temperatures on the heater surfaces to obtain the desired temperature distribution on the design surfaces in the nine cases examined.« less

  15. Gluon tomography from deeply virtual Compton scattering at small x

    DOE PAGES

    Hatta, Yoshitaka; Xiao, Bo-Wen; Yuan, Feng

    2017-06-29

    We present a full evaluation of the deeply virtual Compton scattering cross section in the dipole framework in the small-x region. The result features the cosφ and cos2φ azimuthal angular correlations, which have been missing in previous studies based on the dipole model. In particular, the cos2φ term is generated by the elliptic gluon Wigner distribution of which the measurement at the planned electron-ion collider provides important information about the gluon tomography at small x. Here, we also show the consistency with the standard collinear factorization approach based on the quark and gluon generalized parton distributions.

  16. Probabilistic motor sequence learning in a virtual reality serial reaction time task.

    PubMed

    Sense, Florian; van Rijn, Hedderik

    2018-01-01

    The serial reaction time task is widely used to study learning and memory. The task is traditionally administered by showing target positions on a computer screen and collecting responses using a button box or keyboard. By comparing response times to random or sequenced items or by using different transition probabilities, various forms of learning can be studied. However, this traditional laboratory setting limits the number of possible experimental manipulations. Here, we present a virtual reality version of the serial reaction time task and show that learning effects emerge as expected despite the novel way in which responses are collected. We also show that response times are distributed as expected. The current experiment was conducted in a blank virtual reality room to verify these basic principles. For future applications, the technology can be used to modify the virtual reality environment in any conceivable way, permitting a wide range of previously impossible experimental manipulations.

  17. Virtual odors to transmit emotions in virtual agents

    NASA Astrophysics Data System (ADS)

    Delgado-Mata, Carlos; Aylett, Ruth

    2003-04-01

    In this paper we describe an emotional-behvioral architecture. The emotional engine sits at a higher layer than the behavior system, and can alter behavior patterns, the engine is designed to simulate Emotionally-Intelligent Agents in a Virtual Environment, where each agent senses its own emotions, and other creature emotions through a virtual smell sensor; senses obstacles and other moving creatures in the environment and reacts to them. The architecture consists of an emotion engine, behavior synthesis system, a motor layer and a library of sensors.

  18. Logistics Supply of the Distributed Air Wing

    DTIC Science & Technology

    2014-09-01

    distribution is unlimited LOGISTICS SUPPLY OF THE DISTRIBUTED AIR WING Chee Siong Ong Civilian, Defence Science and Technology Agency B.Eng., Nanyang... Technological University, 2004 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MODELING, VIRTUAL...Department, for his advice on the Marine Aviation Logistics Supply Program. Finally, I am very grateful to my company, Defence Science and Technology

  19. Implementing virtual microscopy improves outcomes in a hematology morphology course.

    PubMed

    Brueggeman, Mauri S; Swinehart, Cheryl; Yue, Mary Jane; Conway-Klaassen, Janice M; Wiesner, Stephen M

    2012-01-01

    In this study, we evaluated the efficacy of virtual microscopy as the primary mode of laboratory instruction in undergraduate level clinical hematology teaching. Distance education (DE) has become a popular option for expanding education and optimizing expenses but continues to be controversial. The challenge of delivering an equitable curriculum to distant locations along with the need to preserve our slide collection directed our effort to digitize the slide sets used in our teaching laboratories. Students enrolled at two performance sites were randomly assigned to either traditional microscopy (TM) or virtual microscopy (VM) instruction. The VM group performed significantly better than the TM group. We anticipate that this approach will play a central role in the distributed delivery of hematology through distance education as new programs are initiated to address workforce shortage needs.

  20. Molecular origin of photovoltaic performance in donor- block-acceptor all-conjugated block copolymers

    DOE PAGES

    Smith, Kendall A.; Lin, Yen -Hao; Mok, Jorge W.; ...

    2015-11-03

    All-conjugated block copolymers may be an effective route to self-assembled photovoltaic devices, but we lack basic information on the relationship between molecular characteristics and photovoltaic performance. Here, we synthesize a library of poly(3-hexylthiophene) (P3HT) block poly((9,9-dialkylfluorene)-2,7-diyl-alt-[4,7-bis(alkylthiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (PFTBT) donor- block-acceptor all-conjugated block copolymers and carry out a comprehensive study of processing conditions, crystallinity, domain sizes, and side-chain structure on photovoltaic device performance. We find that all block copolymers studied exhibit an out-of-plane crystal orientation after deposition, and on thermal annealing at high temperatures the crystal orientation flips to an in-plane orientation. By varying processing conditions on polymer photovoltaic devices, we showmore » that the crystal orientation has only a modest effect (15-20%) on photovoltaic performance. The addition of side-chains to the PFTBT block is found to decrease photovoltaic power conversion efficiencies by at least an order of magnitude. Through grazing-incidence X-ray measurements we find that the addition of side-chains to the PFTBT acceptor block results in weak segregation and small (< 10 nm) block copolymer self-assembled donor and acceptor domains. This work is the most comprehensive to date on all-conjugated block copolymer systems and suggests that photovoltaic performance of block copolymers depends strongly on the miscibility of donor and acceptor blocks, which impacts donor and acceptor domain sizes and purity. Lastly, strategies for improving the device performance of block copolymer photovoltaics should seek to increase segregation between donor and acceptor polymer domains.« less