Memory Forensics: Review of Acquisition and Analysis Techniques

DTIC Science & Technology

2013-11-01

Management Overview Processes running on modern multitasking operating systems operate on an abstraction of RAM, called virtual memory [7]. In these systems...information such as user names, email addresses and passwords [7]. Analysts also use tools such as WinHex to identify headers or other suspicious data within

Comparison of two paradigms for distributed shared memory

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

Levelt, W.G.; Kaashoek, M.F.; Bal, H.E.

1990-08-01

The paper compares two paradigms for Distributed Shared Memory on loosely coupled computing systems: the shared data-object model as used in Orca, a programming language specially designed for loosely coupled computing systems and the Shared Virtual Memory model. For both paradigms the authors have implemented two systems, one using only point-to-point messages, the other using broadcasting as well. They briefly describe these two paradigms and their implementations. Then they compare their performance on four applications: the traveling salesman problem, alpha-beta search, matrix multiplication and the all pairs shortest paths problem. The measurements show that both paradigms can be used efficientlymore » for programming large-grain parallel applications. Significant speedups were obtained on all applications. The unstructured Shared Virtual Memory paradigm achieves the best absolute performance, although this is largely due to the preliminary nature of the Orca compiler used. The structured shared data-object model achieves the highest speedups and is much easier to program and to debug.« less

Forensic Analysis of Window’s(Registered) Virtual Memory Incorporating the System’s Page-File

DTIC Science & Technology

2008-12-01

Management and Budget, Paperwork Reduction Project (0704-0188) Washington DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE December...data in a meaningful way. One reason for this is how memory is managed by the operating system. Data belonging to one process can be distributed...way. One reason for this is how memory is managed by the operating system. Data belonging to one process can be distributed arbitrarily across

Interfacing laboratory instruments to multiuser, virtual memory computers

NASA Technical Reports Server (NTRS)

Generazio, Edward R.; Stang, David B.; Roth, Don J.

1989-01-01

Incentives, problems and solutions associated with interfacing laboratory equipment with multiuser, virtual memory computers are presented. The major difficulty concerns how to utilize these computers effectively in a medium sized research group. This entails optimization of hardware interconnections and software to facilitate multiple instrument control, data acquisition and processing. The architecture of the system that was devised, and associated programming and subroutines are described. An example program involving computer controlled hardware for ultrasonic scan imaging is provided to illustrate the operational features.

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.

Using VirtualGL/TurboVNC Software on the Peregrine System |

Science.gov Websites

High-Performance Computing | NREL VirtualGL/TurboVNC Software on the Peregrine System Using , allowing users to access and share large-memory visualization nodes with high-end graphics processing units may be better than just using X11 forwarding when connecting from a remote site with low bandwidth and

File System Virtual Appliances: Third-Party File System Implementations Without the Pain

DTIC Science & Technology

2008-05-01

Eifeldt. POSIX: a developer’s view of standards. USENIX ATC, pages 24–24. USENIX Association, 1997. [12] M. Eisler , P. Corbett, M. Kazar, D. S...Gingell, J. P. Moran, and W. A. Shannon. Virtual Memory Architecture in SunOS. USENIX Summer Conference, pages 81–94, 1987 . [17] D. Gupta, L. Cherkasova, R

Multiple-User, Multitasking, Virtual-Memory Computer System

NASA Technical Reports Server (NTRS)

Generazio, Edward R.; Roth, Don J.; Stang, David B.

1993-01-01

Computer system designed and programmed to serve multiple users in research laboratory. Provides for computer control and monitoring of laboratory instruments, acquisition and anlaysis of data from those instruments, and interaction with users via remote terminals. System provides fast access to shared central processing units and associated large (from megabytes to gigabytes) memories. Underlying concept of system also applicable to monitoring and control of industrial processes.

Tier identification (TID) for tiered memory characteristics

DOEpatents

Chang, Jichuan; Lim, Kevin T; Ranganathan, Parthasarathy

2014-03-25

A tier identification (TID) is to indicate a characteristic of a memory region associated with a virtual address in a tiered memory system. A thread may be serviced according to a first path based on the TID indicating a first characteristic. The thread may be serviced according to a second path based on the TID indicating a second characteristic.

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.

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.

The Virtual Shop: A new immersive virtual reality environment and scenario for the assessment of everyday memory.

PubMed

Ouellet, Émilie; Boller, Benjamin; Corriveau-Lecavalier, Nick; Cloutier, Simon; Belleville, Sylvie

2018-06-01

Assessing and predicting memory performance in everyday life is a common assignment for neuropsychologists. However, most traditional neuropsychological tasks are not conceived to capture everyday memory performance. The Virtual Shop is a fully immersive task developed to assess memory in a more ecological way than traditional neuropsychological assessments. Two studies were undertaken to assess the feasibility of the Virtual Shop and to appraise its ecological and construct validity. In study 1, 20 younger and 19 older adults completed the Virtual Shop task to evaluate its level of difficulty and the way the participants interacted with the VR material. The construct validity was examined with the contrasted-group method, by comparing the performance of younger and older adults. In study 2, 35 individuals with subjective cognitive decline completed the Virtual Shop task. Performance was correlated with an existing questionnaire evaluating everyday memory in order to appraise its ecological validity. To add further support to its construct validity, performance was correlated with traditional episodic memory and executive tasks. All participants successfully completed the Virtual Shop. The task had an appropriate level of difficulty that helped differentiate younger and older adults, supporting the feasibility and construct validity of the task. The performance on the Virtual Shop was significantly and moderately correlated with the performance on the questionnaire and on the traditional memory and executive tasks. Results support the feasibility and both the ecological and construct validity of the Virtual Shop. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Efficient operating system level virtualization techniques for cloud resources

NASA Astrophysics Data System (ADS)

Ansu, R.; Samiksha; Anju, S.; Singh, K. John

2017-11-01

Cloud computing is an advancing technology which provides the servcies of Infrastructure, Platform and Software. Virtualization and Computer utility are the keys of Cloud computing. The numbers of cloud users are increasing day by day. So it is the need of the hour to make resources available on demand to satisfy user requirements. The technique in which resources namely storage, processing power, memory and network or I/O are abstracted is known as Virtualization. For executing the operating systems various virtualization techniques are available. They are: Full System Virtualization and Para Virtualization. In Full Virtualization, the whole architecture of hardware is duplicated virtually. No modifications are required in Guest OS as the OS deals with the VM hypervisor directly. In Para Virtualization, modifications of OS is required to run in parallel with other OS. For the Guest OS to access the hardware, the host OS must provide a Virtual Machine Interface. OS virtualization has many advantages such as migrating applications transparently, consolidation of server, online maintenance of OS and providing security. This paper briefs both the virtualization techniques and discusses the issues in OS level virtualization.

Interactive Volume Exploration of Petascale Microscopy Data Streams Using a Visualization-Driven Virtual Memory Approach.

PubMed

Hadwiger, M; Beyer, J; Jeong, Won-Ki; Pfister, H

2012-12-01

This paper presents the first volume visualization system that scales to petascale volumes imaged as a continuous stream of high-resolution electron microscopy images. Our architecture scales to dense, anisotropic petascale volumes because it: (1) decouples construction of the 3D multi-resolution representation required for visualization from data acquisition, and (2) decouples sample access time during ray-casting from the size of the multi-resolution hierarchy. Our system is designed around a scalable multi-resolution virtual memory architecture that handles missing data naturally, does not pre-compute any 3D multi-resolution representation such as an octree, and can accept a constant stream of 2D image tiles from the microscopes. A novelty of our system design is that it is visualization-driven: we restrict most computations to the visible volume data. Leveraging the virtual memory architecture, missing data are detected during volume ray-casting as cache misses, which are propagated backwards for on-demand out-of-core processing. 3D blocks of volume data are only constructed from 2D microscope image tiles when they have actually been accessed during ray-casting. We extensively evaluate our system design choices with respect to scalability and performance, compare to previous best-of-breed systems, and illustrate the effectiveness of our system for real microscopy data from neuroscience.

Spatial memory: a Rosetta stone for rat and human hippocampal discourse: Theoretical comment on Goodrich-Hunsaker and Hopkins (2010).

PubMed

Sutherland, Robert J

2010-06-01

The article by Goodrich-Hunsaker and Hopkins (2010, this issue) takes up an important place among in the recent contributions on the role of the hippocampus in memory. They evaluate the effect of bilateral damage to the hippocampus on performance by human participants in a virtual 8-arm radial maze. The hippocampal damage appears to be highly selective and nearly complete. Exactly as with selective hippocampal damage in rats, the human participants showed a deficit in accurately choosing rewarded versus never-rewarded arms and a deficit in avoiding reentering recently visited arms. The results are triply significant: (1) They provide good support for the idea that the wealth of neurobiological information, from network to synapse to gene, on spatial memory in the rat may apply as a whole to the human hippocampal memory system; (2) They affirm the utility of human virtual task models of rat spatial memory tasks; (3) They support one interpretation of the dampening of the hippocampal functional MRI (fMRI) blood oxygen level-dependent (BOLD) signal during performance of the virtual radial arm maze observed by Astur et al. (2005).

Protection of Mission-Critical Applications from Untrusted Execution Environment: Resource Efficient Replication and Migration of Virtual Machines

DTIC Science & Technology

2015-09-28

the performance of log-and- replay can degrade significantly for VMs configured with multiple virtual CPUs, since the shared memory communication...whether based on checkpoint replication or log-and- replay , existing HA ap- proaches use in- memory backups. The backup VM sits in the memory of a...efficiently. 15. SUBJECT TERMS High-availability virtual machines, live migration, memory and traffic overheads, application suspension, Java

Spontaneous Recovery of Human Spatial Memory in a Virtual Water Maze

ERIC Educational Resources Information Center

Luna, David; Martínez, Héctor

2015-01-01

The occurrence of spontaneous recovery in human spatial memory was assessed using a virtual environment. In Experiment 1, spatial memory was established by training participants to locate a hidden platform in a virtual water maze using a set of four distal landmarks. In Experiment 2, after learning about the location of a hidden platform, the…

C-MOS array design techniques: SUMC multiprocessor system study

NASA Technical Reports Server (NTRS)

Clapp, W. A.; Helbig, W. A.; Merriam, A. S.

1972-01-01

The current capabilities of LSI techniques for speed and reliability, plus the possibilities of assembling large configurations of LSI logic and storage elements, have demanded the study of multiprocessors and multiprocessing techniques, problems, and potentialities. Evaluated are three previous systems studies for a space ultrareliable modular computer multiprocessing system, and a new multiprocessing system is proposed that is flexibly configured with up to four central processors, four 1/0 processors, and 16 main memory units, plus auxiliary memory and peripheral devices. This multiprocessor system features a multilevel interrupt, qualified S/360 compatibility for ground-based generation of programs, virtual memory management of a storage hierarchy through 1/0 processors, and multiport access to multiple and shared memory units.

Rambrain - a library for virtually extending physical memory

NASA Astrophysics Data System (ADS)

Imgrund, Maximilian; Arth, Alexander

2017-08-01

We introduce Rambrain, a user space library that manages memory consumption of your code. Using Rambrain you can overcommit memory over the size of physical memory present in the system. Rambrain takes care of temporarily swapping out data to disk and can handle multiples of the physical memory size present. Rambrain is thread-safe, OpenMP and MPI compatible and supports Asynchronous IO. The library was designed to require minimal changes to existing programs and to be easy to use.

Data communications in a parallel active messaging interface of a parallel computer

DOEpatents

Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

2014-09-02

Eager send data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints that specify a client, a context, and a task, including receiving an eager send data communications instruction with transfer data disposed in a send buffer characterized by a read/write send buffer memory address in a read/write virtual address space of the origin endpoint; determining for the send buffer a read-only send buffer memory address in a read-only virtual address space, the read-only virtual address space shared by both the origin endpoint and the target endpoint, with all frames of physical memory mapped to pages of virtual memory in the read-only virtual address space; and communicating by the origin endpoint to the target endpoint an eager send message header that includes the read-only send buffer memory address.

Data communications in a parallel active messaging interface of a parallel computer

DOEpatents

Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

2014-09-16

Eager send data communications in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI composed of data communications endpoints that specify a client, a context, and a task, including receiving an eager send data communications instruction with transfer data disposed in a send buffer characterized by a read/write send buffer memory address in a read/write virtual address space of the origin endpoint; determining for the send buffer a read-only send buffer memory address in a read-only virtual address space, the read-only virtual address space shared by both the origin endpoint and the target endpoint, with all frames of physical memory mapped to pages of virtual memory in the read-only virtual address space; and communicating by the origin endpoint to the target endpoint an eager send message header that includes the read-only send buffer memory address.

Modification of existing human motor memories is enabled by primary cortical processing during memory reactivation.

PubMed

Censor, Nitzan; Dimyan, Michael A; Cohen, Leonardo G

2010-09-14

One of the most challenging tasks of the brain is to constantly update the internal neural representations of existing memories. Animal studies have used invasive methods such as direct microfusion of protein inhibitors to designated brain areas, in order to study the neural mechanisms underlying modification of already existing memories after their reactivation during recall [1-4]. Because such interventions are not possible in humans, it is not known how these neural processes operate in the human brain. In a series of experiments we show here that when an existing human motor memory is reactivated during recall, modification of the memory is blocked by virtual lesion [5] of the related primary cortical human brain area. The virtual lesion was induced by noninvasive repetitive transcranial magnetic stimulation guided by a frameless stereotactic brain navigation system and each subject's brain image. The results demonstrate that primary cortical processing in the human brain interacting with pre-existing reactivated memory traces is critical for successful modification of the existing related memory. Modulation of reactivated memories by noninvasive cortical stimulation may have important implications for human memory research and have far-reaching clinical applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

Performance implications from sizing a VM on multi-core systems: A Data analytic application s view

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

Lim, Seung-Hwan; Horey, James L; Begoli, Edmon

In this paper, we present a quantitative performance analysis of data analytics applications running on multi-core virtual machines. Such environments form the core of cloud computing. In addition, data analytics applications, such as Cassandra and Hadoop, are becoming increasingly popular on cloud computing platforms. This convergence necessitates a better understanding of the performance and cost implications of such hybrid systems. For example, the very rst step in hosting applications in virtualized environments, requires the user to con gure the number of virtual processors and the size of memory. To understand performance implications of this step, we benchmarked three Yahoo Cloudmore » Serving Benchmark (YCSB) workloads in a virtualized multi-core environment. Our measurements indicate that the performance of Cassandra for YCSB workloads does not heavily depend on the processing capacity of a system, while the size of the data set is critical to performance relative to allocated memory. We also identi ed a strong relationship between the running time of workloads and various hardware events (last level cache loads, misses, and CPU migrations). From this analysis, we provide several suggestions to improve the performance of data analytics applications running on cloud computing environments.« less

Local concurrent error detection and correction in data structures using virtual backpointers

NASA Technical Reports Server (NTRS)

Li, C. C.; Chen, P. P.; Fuchs, W. K.

1987-01-01

A new technique, based on virtual backpointers, for local concurrent error detection and correction in linked data structures is presented. Two new data structures, the Virtual Double Linked List, and the B-tree with Virtual Backpointers, are described. For these structures, double errors can be detected in 0(1) time and errors detected during forward moves can be corrected in 0(1) time. The application of a concurrent auditor process to data structure error detection and correction is analyzed, and an implementation is described, to determine the effect on mean time to failure of a multi-user shared database system. The implementation utilizes a Sequent shared memory multiprocessor system operating on a shared databased of Virtual Double Linked Lists.

Local concurrent error detection and correction in data structures using virtual backpointers

NASA Technical Reports Server (NTRS)

Li, Chung-Chi Jim; Chen, Paul Peichuan; Fuchs, W. Kent

1989-01-01

A new technique, based on virtual backpointers, for local concurrent error detection and correction in linked data strutures is presented. Two new data structures, the Virtual Double Linked List, and the B-tree with Virtual Backpointers, are described. For these structures, double errors can be detected in 0(1) time and errors detected during forward moves can be corrected in 0(1) time. The application of a concurrent auditor process to data structure error detection and correction is analyzed, and an implementation is described, to determine the effect on mean time to failure of a multi-user shared database system. The implementation utilizes a Sequent shared memory multiprocessor system operating on a shared database of Virtual Double Linked Lists.

Opportunities for leveraging OS virtualization in high-end supercomputing.

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

Bridges, Patrick G.; Pedretti, Kevin Thomas Tauke

2010-11-01

This paper examines potential motivations for incorporating virtualization support in the system software stacks of high-end capability supercomputers. We advocate that this will increase the flexibility of these platforms significantly and enable new capabilities that are not possible with current fixed software stacks. Our results indicate that compute, virtual memory, and I/O virtualization overheads are low and can be further mitigated by utilizing well-known techniques such as large paging and VMM bypass. Furthermore, since the addition of virtualization support does not affect the performance of applications using the traditional native environment, there is essentially no disadvantage to its addition.

Use of immersive virtual reality to assess episodic memory: A validation study in older adults.

PubMed

Corriveau Lecavalier, Nick; Ouellet, Émilie; Boller, Benjamin; Belleville, Sylvie

2018-05-29

Virtual reality (VR) allows for the creation of ecological environments that could be used for cognitive assessment and intervention. This study comprises two parts that describe and assess an immersive VR task, the Virtual Shop, which can be used to measure episodic memory. Part 1 addresses its applicability in healthy older adults by measuring presence, motivation, and cybersickness symptoms. Part 2 addresses its construct validity by investigating correlations between performance in the VR task and on a traditional experimental memory task, and by measuring whether the VR task is sensitive to age-related memory differences. Fifty-seven older and 20 younger adults were assessed in the Virtual Shop, in which they memorised and fetched 12 familiar items. Part 1 showed high levels of presence, higher levels of motivation for the VR than for the traditional task, and negligible cybersickness symptoms. Part 2 indicates that memory performance in the VR task is positively correlated with performance on a traditional memory task for both age groups, and age-related differences were found on the VR and traditional memory tasks. Thus, the use of VR is feasible in older adults and the Virtual Shop is a valid task to assess and train episodic memory in this population.

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

PubMed

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

2018-04-01

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

Working memory in wayfinding-a dual task experiment in a virtual city.

PubMed

Meilinger, Tobias; Knauff, Markus; Bülthoff, Heinrich H

2008-06-01

This study examines the working memory systems involved in human wayfinding. In the learning phase, 24 participants learned two routes in a novel photorealistic virtual environment displayed on a 220° screen while they were disrupted by a visual, a spatial, a verbal, or-in a control group-no secondary task. In the following wayfinding phase, the participants had to find and to "virtually walk" the two routes again. During this wayfinding phase, a number of dependent measures were recorded. This research shows that encoding wayfinding knowledge interfered with the verbal and with the spatial secondary task. These interferences were even stronger than the interference of wayfinding knowledge with the visual secondary task. These findings are consistent with a dual-coding approach of wayfinding knowledge. 2008 Cognitive Science Society, Inc.

When Do Objects Become Landmarks? A VR Study of the Effect of Task Relevance on Spatial Memory

PubMed Central

Han, Xue; Byrne, Patrick; Kahana, Michael; Becker, Suzanna

2012-01-01

We investigated how objects come to serve as landmarks in spatial memory, and more specifically how they form part of an allocentric cognitive map. Participants performing a virtual driving task incidentally learned the layout of a virtual town and locations of objects in that town. They were subsequently tested on their spatial and recognition memory for the objects. To assess whether the objects were encoded allocentrically we examined pointing consistency across tested viewpoints. In three experiments, we found that spatial memory for objects at navigationally relevant locations was more consistent across tested viewpoints, particularly when participants had more limited experience of the environment. When participants’ attention was focused on the appearance of objects, the navigational relevance effect was eliminated, whereas when their attention was focused on objects’ locations, this effect was enhanced, supporting the hypothesis that when objects are processed in the service of navigation, rather than merely being viewed as objects, they engage qualitatively distinct attentional systems and are incorporated into an allocentric spatial representation. The results are consistent with evidence from the neuroimaging literature that when objects are relevant to navigation, they not only engage the ventral “object processing stream”, but also the dorsal stream and medial temporal lobe memory system classically associated with allocentric spatial memory. PMID:22586455

Using Virtual Reality to Characterize Episodic Memory Profiles in Amnestic Mild Cognitive Impairment and Alzheimer's Disease: Influence of Active and Passive Encoding

ERIC Educational Resources Information Center

Plancher, G.; Tirard, A.; Gyselinck, V.; Nicolas, S.; Piolino, P.

2012-01-01

Most neuropsychological assessments of episodic memory bear little similarity to the events that patients actually experience as memories in daily life. The first aim of this study was to use a virtual environment to characterize episodic memory profiles in an ecological fashion, which includes memory for central and perceptual details,…

The use of virtual reality in memory rehabilitation: current findings and future directions.

PubMed

Brooks, B M; Rose, F D

2003-01-01

There is considerable potential for using virtual reality (VR) in memory rehabilitation which is only just beginning to be realized. PC-based virtual environments are probably better suited for this purpose than more immersive virtual environments because they are relatively inexpensive and portable, and less frightening to patients. Those exploratory studies that have so far been performed indicate that VR involvement would be usefully directed towards improving assessments of memory impairments and in memory remediation using reorganization techniques. In memory assessment, the use of VR could provide more comprehensive, ecologically-valid, and controlled evaluations of prospective, incidental, and spatial memory in a rehabilitation setting than is possible using standardized assessment tests. The additional knowledge gained from these assessments could more effectively direct rehabilitation towards specific impairments of individual patients. In memory remediation, VR training has been found to promote procedural learning in people with memory impairments, and this learning has been found to transfer to improved real-world performance. Future research should investigate ways in which the procedural knowledge gained during VR interaction can be adapted to offset the many disabilities which result from different forms of memory impairment.

How does schema theory apply to real versus virtual memories?

PubMed

Flannery, Kathleen A; Walles, Rena

2003-04-01

Schemas are cognitive frameworks that guide memory, aide in the interpretation of events, and influence how we retrieve stored memories. The purpose of this study was to explore how schemas operate in a well-known environment and to examine whether or not schemas operate differently in real versus virtual environments. Twenty-four undergraduate students from a small liberal arts college in the northeast participated for course credit. Two identical offices (a real office and a virtual office) were created and filled with eight consistent and eight inconsistent items. Each participant explored either the real office or the virtual office for 20 seconds without any knowledge that their memory would be tested. After leaving the office, participants completed a recognition task and a short demographic questionnaire. Overall sensitivity and higher confidence in recognition memory scores was found for inconsistent compared to consistent items. Greater support for the consistency effect was observed in this study and interpreted in terms of the dynamic memory model and the schema-plus-correction model. The results also demonstrate that virtual reality paradigms may produce similar outcomes compared to the real world in terms of some memory processes, but additional design factors must be considered if the researcher's goal is to create equivalent paradigms.

The road to virtual: the Sauls Memorial Virtual Library journey.

PubMed

Waddell, Stacie; Harkness, Amy; Cohen, Mark L

2014-01-01

The Sauls Memorial Virtual Library closed its physical space in 2012. This article outlines the reasons for this change and how the library staff and hospital leadership planned and executed the enormous undertaking. Outcomes of the change and lessons learned from the process are discussed.

Cognitive training on stroke patients via virtual reality-based serious games.

PubMed

Gamito, Pedro; Oliveira, Jorge; Coelho, Carla; Morais, Diogo; Lopes, Paulo; Pacheco, José; Brito, Rodrigo; Soares, Fabio; Santos, Nuno; Barata, Ana Filipa

2017-02-01

Use of virtual reality environments in cognitive rehabilitation offers cost benefits and other advantages. In order to test the effectiveness of a virtual reality application for neuropsychological rehabilitation, a cognitive training program using virtual reality was applied to stroke patients. A virtual reality-based serious games application for cognitive training was developed, with attention and memory tasks consisting of daily life activities. Twenty stroke patients were randomly assigned to two conditions: exposure to the intervention, and waiting list control. The results showed significant improvements in attention and memory functions in the intervention group, but not in the controls. Overall findings provide further support for the use of VR cognitive training applications in neuropsychological rehabilitation. Implications for Rehabilitation Improvements in memory and attention functions following a virtual reality-based serious games intervention. Training of daily-life activities using a virtual reality application. Accessibility to training contents.

The DASH Project: An Overview

DTIC Science & Technology

1988-02-29

by memory copyin g will degrade system performance on shared-memory multiprocessors. Virtual memor y (VM) remapping, as opposed to memory copying...Bershad, G.D. Giuseppe Facchetti, Kevin Fall, G . Scott Graham, Ellen Nelson , P. Venkat Rangan, Bruno Sartirana, Shin-Yuan Tzou, Raj Vaswani, and Robert...Remote Execution in NEST", IEEE Trans. on Software Eng. 13, 8 (August 1987), 905-912. 3. G . T. Almes, A. P. Black, E. Lazowska and J. Noe, "The Eden

A Probability Model for Belady's Anomaly

ERIC Educational Resources Information Center

McMaster, Kirby; Sambasivam, Samuel E.; Anderson, Nicole

2010-01-01

In demand paging virtual memory systems, the page fault rate of a process varies with the number of memory frames allocated to the process. When an increase in the number of allocated frames leads to an increase in the number of page faults, Belady's anomaly is said to occur. In this paper, we present a probability model for Belady's anomaly. We…

Ecological validity of virtual environments to assess human navigation ability

PubMed Central

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

2015-01-01

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

Virtual Reality as an Ecologically Valid Tool for Assessing Multifaceted Episodic Memory in Children and Adolescents

ERIC Educational Resources Information Center

Picard, Laurence; Abram, Maria; Orriols, Eric; Piolino, Pascale

2017-01-01

The majority of episodic memory (EM) tests are far removed from what we experience in daily life and from the definition of this type of memory. This study examines the developmental trajectory of the main aspects of episodic memory--what, where, and when--and of feature binding in a naturalistic virtual environment. A population of 125…

Using virtual reality to characterize episodic memory profiles in amnestic mild cognitive impairment and Alzheimer's disease: influence of active and passive encoding.

PubMed

Plancher, G; Tirard, A; Gyselinck, V; Nicolas, S; Piolino, P

2012-04-01

Most neuropsychological assessments of episodic memory bear little similarity to the events that patients actually experience as memories in daily life. The first aim of this study was to use a virtual environment to characterize episodic memory profiles in an ecological fashion, which includes memory for central and perceptual details, spatiotemporal contextual elements, and binding. This study included subjects from three different populations: healthy older adults, patients with amnestic mild cognitive impairment (aMCI) and patients with early to moderate Alzheimer's disease (AD). Second, we sought to determine whether environmental factors that can affect encoding (active vs. passive exploration) influence memory performance in pathological aging. Third, we benchmarked the results of our virtual reality episodic memory test against a classical memory test and a subjective daily memory complaint scale. Here, the participants were successively immersed in two virtual environments; the first, as the driver of a virtual car (active exploration) and the second, as the passenger of that car (passive exploration). Subjects were instructed to encode all elements of the environment as well as the associated spatiotemporal contexts. Following each immersion, we assessed the patient's recall and recognition of central information (i.e., the elements of the environment), contextual information (i.e., temporal, egocentric and allocentric spatial information) and lastly, the quality of binding. We found that the AD patients' performances were inferior to that of the aMCI and even more to that of the healthy aged groups, in line with the progression of hippocampal atrophy reported in the literature. Spatial allocentric memory assessments were found to be particularly useful for distinguishing aMCI patients from healthy older adults. Active exploration yielded enhanced recall of central and allocentric spatial information, as well as binding in all groups. This led aMCI patients to achieve better performance scores on immediate temporal memory tasks. Finally, the patients' daily memory complaints were more highly correlated with the performances on the virtual test than with their performances on the classical memory test. Taken together, these results highlight specific cognitive differences found between these three populations that may provide additional insight into the early diagnosis and rehabilitation of pathological aging. In particular, neuropsychological studies would benefit to use virtual tests and a multi-component approach to assess episodic memory, and encourage active encoding of information in patients suffering from mild or severe age-related memory impairment. The beneficial effect of active encoding on episodic memory in aMCI and early to moderate AD is discussed in the context of relatively preserved frontal and motor brain functions implicated in self-referential effects and procedural abilities. Copyright © 2011 Elsevier Ltd. All rights reserved.

Direct access inter-process shared memory

DOEpatents

Brightwell, Ronald B; Pedretti, Kevin; Hudson, Trammell B

2013-10-22

A technique for directly sharing physical memory between processes executing on processor cores is described. The technique includes loading a plurality of processes into the physical memory for execution on a corresponding plurality of processor cores sharing the physical memory. An address space is mapped to each of the processes by populating a first entry in a top level virtual address table for each of the processes. The address space of each of the processes is cross-mapped into each of the processes by populating one or more subsequent entries of the top level virtual address table with the first entry in the top level virtual address table from other processes.

IPCS user's manual

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

McGoldrick, P.R.

1980-12-11

The Interprocess Communications System (IPCS) was written to provide a virtual machine upon which the Supervisory Control and Diagnostic System (SCDS) for the Mirror Fusion Test Facility (MFTF) could be built. The hardware upon which the IPCS runs consists of nine minicomputers sharing some common memory.

Hardware/software codesign for embedded RISC core

NASA Astrophysics Data System (ADS)

Liu, Peng

2001-12-01

This paper describes hardware/software codesign method of the extendible embedded RISC core VIRGO, which based on MIPS-I instruction set architecture. VIRGO is described by Verilog hardware description language that has five-stage pipeline with shared 32-bit cache/memory interface, and it is controlled by distributed control scheme. Every pipeline stage has one small controller, which controls the pipeline stage status and cooperation among the pipeline phase. Since description use high level language and structure is distributed, VIRGO core has highly extension that can meet the requirements of application. We take look at the high-definition television MPEG2 MPHL decoder chip, constructed the hardware/software codesign virtual prototyping machine that can research on VIRGO core instruction set architecture, and system on chip memory size requirements, and system on chip software, etc. We also can evaluate the system on chip design and RISC instruction set based on the virtual prototyping machine platform.

The Fluke Security Project

DTIC Science & Technology

2000-04-01

be an extension of Utah’s nascent Quarks system, oriented to closely coupled cluster environments. However, the grant did not actually begin until... Intel x86, implemented ten virtual machine monitors and servers, including a virtual memory manager, a checkpointer, a process manager, a file server...Fluke, we developed a novel hierarchical processor scheduling frame- work called CPU inheritance scheduling [5]. This is a framework for scheduling

Implementation of relational data base management systems on micro-computers

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

Huang, C.L.

1982-01-01

This dissertation describes an implementation of a Relational Data Base Management System on a microcomputer. A specific floppy disk based hardward called TERAK is being used, and high level query interface which is similar to a subset of the SEQUEL language is provided. The system contains sub-systems such as I/O, file management, virtual memory management, query system, B-tree management, scanner, command interpreter, expression compiler, garbage collection, linked list manipulation, disk space management, etc. The software has been implemented to fulfill the following goals: (1) it is highly modularized. (2) The system is physically segmented into 16 logically independent, overlayable segments,more » in a way such that a minimal amount of memory is needed at execution time. (3) Virtual memory system is simulated that provides the system with seemingly unlimited memory space. (4) A language translator is applied to recognize user requests in the query language. The code generation of this translator generates compact code for the execution of UPDATE, DELETE, and QUERY commands. (5) A complete set of basic functions needed for on-line data base manipulations is provided through the use of a friendly query interface. (6) To eliminate the dependency on the environment (both software and hardware) as much as possible, so that it would be easy to transplant the system to other computers. (7) To simulate each relation as a sequential file. It is intended to be a highly efficient, single user system suited to be used by small or medium sized organizations for, say, administrative purposes. Experiments show that quite satisfying results have indeed been achieved.« less

Design and Implementation of a Basic Cross-Compiler and Virtual Memory Management System for the TI-59 Programmable Calculator.

DTIC Science & Technology

1983-06-01

previously stated requirements to construct the framework for a software soluticn. It is during this phase of design that lany cf the most critical...the linker would have to be deferred until the compiler was formalized and ir the implementation phase of design. The second problem involved...memory liait was encountered. At this point a segmentation occurred. The memory limits were reset and the combining process continued until another

Efficient Checkpointing of Virtual Machines using Virtual Machine Introspection

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

Aderholdt, Ferrol; Han, Fang; Scott, Stephen L

Cloud Computing environments rely heavily on system-level virtualization. This is due to the inherent benefits of virtualization including fault tolerance through checkpoint/restart (C/R) mechanisms. Because clouds are the abstraction of large data centers and large data centers have a higher potential for failure, it is imperative that a C/R mechanism for such an environment provide minimal latency as well as a small checkpoint file size. Recently, there has been much research into C/R with respect to virtual machines (VM) providing excellent solutions to reduce either checkpoint latency or checkpoint file size. However, these approaches do not provide both. This papermore » presents a method of checkpointing VMs by utilizing virtual machine introspection (VMI). Through the usage of VMI, we are able to determine which pages of memory within the guest are used or free and are better able to reduce the amount of pages written to disk during a checkpoint. We have validated this work by using various benchmarks to measure the latency along with the checkpoint size. With respect to checkpoint file size, our approach results in file sizes within 24% or less of the actual used memory within the guest. Additionally, the checkpoint latency of our approach is up to 52% faster than KVM s default method.« less

Impacts of memory on a regular lattice for different population sizes with asynchronous update in spatial snowdrift game

NASA Astrophysics Data System (ADS)

Shu, Feng; Liu, Xingwen; Li, Min

2018-05-01

Memory is an important factor on the evolution of cooperation in spatial structure. For evolutionary biologists, the problem is often how cooperation acts can emerge in an evolving system. In the case of snowdrift game, it is found that memory can boost cooperation level for large cost-to-benefit ratio r, while inhibit cooperation for small r. Thus, how to enlarge the range of r for the purpose of enhancing cooperation becomes a hot issue recently. This paper addresses a new memory-based approach and its core lies in: Each agent applies the given rule to compare its own historical payoffs in a certain memory size, and take the obtained maximal one as virtual payoff. In order to get the optimal strategy, each agent randomly selects one of its neighbours to compare their virtual payoffs, which can lead to the optimal strategy. Both constant-size memory and size-varying memory are investigated by means of a scenario of asynchronous updating algorithm on regular lattices with different sizes. Simulation results show that this approach effectively enhances cooperation level in spatial structure and makes the high cooperation level simultaneously emerge for both small and large r. Moreover, it is discovered that population sizes have a significant influence on the effects of cooperation.

VIRTUAL FRAME BUFFER INTERFACE

NASA Technical Reports Server (NTRS)

Wolfe, T. L.

1994-01-01

Large image processing systems use multiple frame buffers with differing architectures and vendor supplied user interfaces. This variety of architectures and interfaces creates software development, maintenance, and portability problems for application programs. The Virtual Frame Buffer Interface program makes all frame buffers appear as a generic frame buffer with a specified set of characteristics, allowing programmers to write code which will run unmodified on all supported hardware. The Virtual Frame Buffer Interface converts generic commands to actual device commands. The virtual frame buffer consists of a definition of capabilities and FORTRAN subroutines that are called by application programs. The virtual frame buffer routines may be treated as subroutines, logical functions, or integer functions by the application program. Routines are included that allocate and manage hardware resources such as frame buffers, monitors, video switches, trackballs, tablets and joysticks; access image memory planes; and perform alphanumeric font or text generation. The subroutines for the various "real" frame buffers are in separate VAX/VMS shared libraries allowing modification, correction or enhancement of the virtual interface without affecting application programs. The Virtual Frame Buffer Interface program was developed in FORTRAN 77 for a DEC VAX 11/780 or a DEC VAX 11/750 under VMS 4.X. It supports ADAGE IK3000, DEANZA IP8500, Low Resolution RAMTEK 9460, and High Resolution RAMTEK 9460 Frame Buffers. It has a central memory requirement of approximately 150K. This program was developed in 1985.

A Virtual Radial Arm Maze for the Study of Multiple Memory Systems in a Functional Magnetic Resonance Imaging Environment

PubMed Central

Xu, Dongrong; Hao, Xuejun; Wang, Zhishun; Duan, Yunsuo; Liu, Feng; Marsh, Rachel; Yu, Shan; Peterson, Bradley S.

2015-01-01

An increasing number of functional brain imaging studies are employing computer-based virtual reality (VR) to study changes in brain activity during the performance of high-level psychological and cognitive tasks. We report the development of a VR radial arm maze that adapts for human use in a scanning environment with the same general experimental design of behavioral tasks as that has been used with remarkable effectiveness for the study of multiple memory systems in rodents. The software platform is independent of specific computer hardware and operating systems, as we aim to provide shared access to this technology by the research community. We hope that doing so will provide greater standardization of software platform and study paradigm that will reduce variability and improve the comparability of findings across studies. We report the details of the design and implementation of this platform and provide information for downloading of the system for demonstration and research applications. PMID:26366052

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.

Building a Community Memory in Communities of Practice of E-Learning: A Knowledge Engineering Approach

ERIC Educational Resources Information Center

Sarirete, Akila; Chikh, Azeddine; Noble, Elizabeth

2011-01-01

Purpose: The purpose of this paper is to define a community memory for a virtual communities of practice (CoP) based on organizational learning (OL) concept and ontologies. Design/methodology/approach: The paper focuses on applying the OL concept to virtual CoP and proposes a framework for building the CoP memory by identifying several layers of…

Master-slave system with force feedback based on dynamics of virtual model

NASA Technical Reports Server (NTRS)

Nojima, Shuji; Hashimoto, Hideki

1994-01-01

A master-slave system can extend manipulating and sensing capabilities of a human operator to a remote environment. But the master-slave system has two serious problems: one is the mechanically large impedance of the system; the other is the mechanical complexity of the slave for complex remote tasks. These two problems reduce the efficiency of the system. If the slave has local intelligence, it can help the human operator by using its good points like fast calculation and large memory. The authors suggest that the slave is a dextrous hand with many degrees of freedom able to manipulate an object of known shape. It is further suggested that the dimensions of the remote work space be shared by the human operator and the slave. The effect of the large impedance of the system can be reduced in a virtual model, a physical model constructed in a computer with physical parameters as if it were in the real world. A method to determine the damping parameter dynamically for the virtual model is proposed. Experimental results show that this virtual model is better than the virtual model with fixed damping.

New trends in logic synthesis for both digital designing and data processing

NASA Astrophysics Data System (ADS)

Borowik, Grzegorz; Łuba, Tadeusz; Poźniak, Krzysztof

2016-09-01

FPGA devices are equipped with memory-based structures. These memories act as very large logic cells where the number of inputs equals the number of address lines. At the same time, there is a huge demand in the market of Internet of Things for devices implementing virtual routers, intrusion detection systems, etc.; where such memories are crucial for realizing pattern matching circuits, IP address tables, and other. Unfortunately, existing CAD tools are not well suited to utilize capabilities that such large memory blocks offer due to the lack of appropriate synthesis procedures. This paper presents methods which are useful for memory-based implementations: minimization of the number of input variables and functional decomposition.

Is it possible to use highly realistic virtual reality in the elderly? A feasibility study with image-based rendering.

PubMed

Benoit, Michel; Guerchouche, Rachid; Petit, Pierre-David; Chapoulie, Emmanuelle; Manera, Valeria; Chaurasia, Gaurav; Drettakis, George; Robert, Philippe

2015-01-01

Virtual reality (VR) opens up a vast number of possibilities in many domains of therapy. The primary objective of the present study was to evaluate the acceptability for elderly subjects of a VR experience using the image-based rendering virtual environment (IBVE) approach and secondly to test the hypothesis that visual cues using VR may enhance the generation of autobiographical memories. Eighteen healthy volunteers (mean age 68.2 years) presenting memory complaints with a Mini-Mental State Examination score higher than 27 and no history of neuropsychiatric disease were included. Participants were asked to perform an autobiographical fluency task in four conditions. The first condition was a baseline grey screen, the second was a photograph of a well-known location in the participant's home city (FamPhoto), and the last two conditions displayed VR, ie, a familiar image-based virtual environment (FamIBVE) consisting of an image-based representation of a known landmark square in the center of the city of experimentation (Nice) and an unknown image-based virtual environment (UnknoIBVE), which was captured in a public housing neighborhood containing unrecognizable building fronts. After each of the four experimental conditions, participants filled in self-report questionnaires to assess the task acceptability (levels of emotion, motivation, security, fatigue, and familiarity). CyberSickness and Presence questionnaires were also assessed after the two VR conditions. Autobiographical memory was assessed using a verbal fluency task and quality of the recollection was assessed using the "remember/know" procedure. All subjects completed the experiment. Sense of security and fatigue were not significantly different between the conditions with and without VR. The FamPhoto condition yielded a higher emotion score than the other conditions (P<0.05). The CyberSickness questionnaire showed that participants did not experience sickness during the experiment across the VR conditions. VR stimulates autobiographical memory, as demonstrated by the increased total number of responses on the autobiographical fluency task and the increased number of conscious recollections of memories for familiar versus unknown scenes (P<0.01). The study indicates that VR using the FamIBVE system is well tolerated by the elderly. VR can also stimulate recollections of autobiographical memory and convey familiarity of a given scene, which is an essential requirement for use of VR during reminiscence therapy.

Is it possible to use highly realistic virtual reality in the elderly? A feasibility study with image-based rendering

PubMed Central

Benoit, Michel; Guerchouche, Rachid; Petit, Pierre-David; Chapoulie, Emmanuelle; Manera, Valeria; Chaurasia, Gaurav; Drettakis, George; Robert, Philippe

2015-01-01

Background Virtual reality (VR) opens up a vast number of possibilities in many domains of therapy. The primary objective of the present study was to evaluate the acceptability for elderly subjects of a VR experience using the image-based rendering virtual environment (IBVE) approach and secondly to test the hypothesis that visual cues using VR may enhance the generation of autobiographical memories. Methods Eighteen healthy volunteers (mean age 68.2 years) presenting memory complaints with a Mini-Mental State Examination score higher than 27 and no history of neuropsychiatric disease were included. Participants were asked to perform an autobiographical fluency task in four conditions. The first condition was a baseline grey screen, the second was a photograph of a well-known location in the participant’s home city (FamPhoto), and the last two conditions displayed VR, ie, a familiar image-based virtual environment (FamIBVE) consisting of an image-based representation of a known landmark square in the center of the city of experimentation (Nice) and an unknown image-based virtual environment (UnknoIBVE), which was captured in a public housing neighborhood containing unrecognizable building fronts. After each of the four experimental conditions, participants filled in self-report questionnaires to assess the task acceptability (levels of emotion, motivation, security, fatigue, and familiarity). CyberSickness and Presence questionnaires were also assessed after the two VR conditions. Autobiographical memory was assessed using a verbal fluency task and quality of the recollection was assessed using the “remember/know” procedure. Results All subjects completed the experiment. Sense of security and fatigue were not significantly different between the conditions with and without VR. The FamPhoto condition yielded a higher emotion score than the other conditions (P<0.05). The CyberSickness questionnaire showed that participants did not experience sickness during the experiment across the VR conditions. VR stimulates autobiographical memory, as demonstrated by the increased total number of responses on the autobiographical fluency task and the increased number of conscious recollections of memories for familiar versus unknown scenes (P<0.01). Conclusion The study indicates that VR using the FamIBVE system is well tolerated by the elderly. VR can also stimulate recollections of autobiographical memory and convey familiarity of a given scene, which is an essential requirement for use of VR during reminiscence therapy. PMID:25834437

An evaluation of nonclinical dissociation utilizing a virtual environment shows enhanced working memory and attention.

PubMed

Saidel-Goley, Isaac N; Albiero, Erin E; Flannery, Kathleen A

2012-02-01

Dissociation is a mental process resulting in the disruption of memory, perception, and sometimes identity. At a nonclinical level, only mild dissociative experiences occur. The nature of nonclinical dissociation is disputed in the literature, with some asserting that it is a beneficial information processing style and others positing that it is a psychopathological phenomenon. The purpose of this study was to further the understanding of nonclinical dissociation with respect to memory and attention, by including a more ecologically valid virtual reality (VR) memory task along with standard neuropsychological tasks. Forty-five undergraduate students from a small liberal arts college in the northeast participated for course credit. The participants completed a battery of tasks including two standard memory tasks, a standard attention task, and an experimental VR memory task; the VR task included immersion in a virtual apartment, followed by incidental object-location recall for objects in the virtual apartment. Support for the theoretical model portraying nonclinical dissociation as a beneficial information processing style was found in this study. Dissociation scores were positively correlated with working memory scores and attentional processing scores on the standard neuropsychological tasks. In terms of the VR task, dissociation scores were positively correlated with more false positive memories that could be the result of a tendency of nonclinical highly dissociative individuals to create more elaborative schemas. This study also demonstrates that VR paradigms add to the prediction of cognitive functioning in testing protocols using standard neuropsychological tests, while simultaneously increasing ecological validity.

The influence of action on episodic memory: a virtual reality study.

PubMed

Plancher, Gaën; Barra, Julien; Orriols, Eric; Piolino, Pascale

2013-01-01

A range of empirical findings suggest that active learning is important for memory. However, few studies have focused on the mechanisms underlying this enactment effect in episodic memory using complex environments. Research using virtual reality has yielded inconsistent results. We postulated that the effect of action depends on the degree of interaction with the environment and freedom in the planning of an itinerary. To test these hypotheses, we disentangled the interaction and planning components of action to investigate whether each enhances factual and spatial memory. Seventy-two participants (36 male and 36 female) explored a virtual town in one of three experimental conditions: (a) a passive condition where participants were immersed as passenger of the car (no interaction, no planning); (b) a planning-only condition (the subject chose the itinerary but did not drive the car); (c) an interaction-only condition (the subject drove the car but the itinerary was fixed). We found that itinerary choice and motor control both enhanced spatial memory, while factual memory was impaired by online motor control. The role of action in memory is discussed.

Out-of-Core Streamline Visualization on Large Unstructured Meshes

NASA Technical Reports Server (NTRS)

Ueng, Shyh-Kuang; Sikorski, K.; Ma, Kwan-Liu

1997-01-01

It's advantageous for computational scientists to have the capability to perform interactive visualization on their desktop workstations. For data on large unstructured meshes, this capability is not generally available. In particular, particle tracing on unstructured grids can result in a high percentage of non-contiguous memory accesses and therefore may perform very poorly with virtual memory paging schemes. The alternative of visualizing a lower resolution of the data degrades the original high-resolution calculations. This paper presents an out-of-core approach for interactive streamline construction on large unstructured tetrahedral meshes containing millions of elements. The out-of-core algorithm uses an octree to partition and restructure the raw data into subsets stored into disk files for fast data retrieval. A memory management policy tailored to the streamline calculations is used such that during the streamline construction only a very small amount of data are brought into the main memory on demand. By carefully scheduling computation and data fetching, the overhead of reading data from the disk is significantly reduced and good memory performance results. This out-of-core algorithm makes possible interactive streamline visualization of large unstructured-grid data sets on a single mid-range workstation with relatively low main-memory capacity: 5-20 megabytes. Our test results also show that this approach is much more efficient than relying on virtual memory and operating system's paging algorithms.

Programming Models for Concurrency and Real-Time

NASA Astrophysics Data System (ADS)

Vitek, Jan

Modern real-time applications are increasingly large, complex and concurrent systems which must meet stringent performance and predictability requirements. Programming those systems require fundamental advances in programming languages and runtime systems. This talk presents our work on Flexotasks, a programming model for concurrent, real-time systems inspired by stream-processing and concurrent active objects. Some of the key innovations in Flexotasks are that it support both real-time garbage collection and region-based memory with an ownership type system for static safety. Communication between tasks is performed by channels with a linear type discipline to avoid copying messages, and by a non-blocking transactional memory facility. We have evaluated our model empirically within two distinct implementations, one based on Purdue’s Ovm research virtual machine framework and the other on Websphere, IBM’s production real-time virtual machine. We have written a number of small programs, as well as a 30 KLOC avionics collision detector application. We show that Flexotasks are capable of executing periodic threads at 10 KHz with a standard deviation of 1.2us and have performance competitive with hand coded C programs.

Age effect on components of episodic memory and feature binding: A virtual reality study.

PubMed

Plancher, Gaën; Gyselinck, Valerie; Nicolas, Serge; Piolino, Pascale

2010-05-01

The aims were (1) to explore the effects of normal aging on the main aspects of episodic memory--what, where, and when,--and on feature binding in a virtual environment; (2) to explore the influence of the mode of learning, intentional versus incidental; and (3) to benchmark virtual environment findings collected with older adults against data recorded in classical neuropsychological tests. We tested a population of 82 young adults and 78 older adults without dementia (they participated in a short battery of neuropsychological tests). All the participants drove a car in an urban virtual environment composing of 9 turns and specific areas. Half of the participants were told to drive through the virtual town; the other half were asked to drive and to memorize the environment (itinerary, elements, etc.). All aspects of episodic memory were then assessed (what, where, when, and binding). The older participants had less recollection of the spatiotemporal context of events than the younger with intentional encoding (p < .001), but similar recollection with incidental encoding (except for verbal spatial aspect). The younger participants showed better binding than older ones regardless of the type of encoding (p < .001). For the older participants the virtual test was sensitive to mnesic complaints as well as general cognitive changes (p < .05 to p < .01). We view these results as an indication that virtual environments could provide helpful standard tools for assessing age effects on the main aspects of episodic memory.

Single-pass memory system evaluation for multiprogramming workloads

NASA Technical Reports Server (NTRS)

Conte, Thomas M.; Hwu, Wen-Mei W.

1990-01-01

Modern memory systems are composed of levels of cache memories, a virtual memory system, and a backing store. Varying more than a few design parameters and measuring the performance of such systems has traditionally be constrained by the high cost of simulation. Models of cache performance recently introduced reduce the cost simulation but at the expense of accuracy of performance prediction. Stack-based methods predict performance accurately using one pass over the trace for all cache sizes, but these techniques have been limited to fully-associative organizations. This paper presents a stack-based method of evaluating the performance of cache memories using a recurrence/conflict model for the miss ratio. Unlike previous work, the performance of realistic cache designs, such as direct-mapped caches, are predicted by the method. The method also includes a new approach to the problem of the effects of multiprogramming. This new technique separates the characteristics of the individual program from that of the workload. The recurrence/conflict method is shown to be practical, general, and powerful by comparing its performance to that of a popular traditional cache simulator. The authors expect that the availability of such a tool will have a large impact on future architectural studies of memory systems.

Virtual memory support for distributed computing environments using a shared data object model

NASA Astrophysics Data System (ADS)

Huang, F.; Bacon, J.; Mapp, G.

1995-12-01

Conventional storage management systems provide one interface for accessing memory segments and another for accessing secondary storage objects. This hinders application programming and affects overall system performance due to mandatory data copying and user/kernel boundary crossings, which in the microkernel case may involve context switches. Memory-mapping techniques may be used to provide programmers with a unified view of the storage system. This paper extends such techniques to support a shared data object model for distributed computing environments in which good support for coherence and synchronization is essential. The approach is based on a microkernel, typed memory objects, and integrated coherence control. A microkernel architecture is used to support multiple coherence protocols and the addition of new protocols. Memory objects are typed and applications can choose the most suitable protocols for different types of object to avoid protocol mismatch. Low-level coherence control is integrated with high-level concurrency control so that the number of messages required to maintain memory coherence is reduced and system-wide synchronization is realized without severely impacting the system performance. These features together contribute a novel approach to the support for flexible coherence under application control.

Computational memory architectures for autobiographic agents interacting in a complex virtual environment: a working model

NASA Astrophysics Data System (ADS)

Ho, Wan Ching; Dautenhahn, Kerstin; Nehaniv, Chrystopher

2008-03-01

In this paper, we discuss the concept of autobiographic agent and how memory may extend an agent's temporal horizon and increase its adaptability. These concepts are applied to an implementation of a scenario where agents are interacting in a complex virtual artificial life environment. We present computational memory architectures for autobiographic virtual agents that enable agents to retrieve meaningful information from their dynamic memories which increases their adaptation and survival in the environment. The design of the memory architectures, the agents, and the virtual environment are described in detail. Next, a series of experimental studies and their results are presented which show the adaptive advantage of autobiographic memory, i.e. from remembering significant experiences. Also, in a multi-agent scenario where agents can communicate via stories based on their autobiographic memory, it is found that new adaptive behaviours can emerge from an individual's reinterpretation of experiences received from other agents whereby higher communication frequency yields better group performance. An interface is described that visualises the memory contents of an agent. From an observer perspective, the agents' behaviours can be understood as individually structured, and temporally grounded, and, with the communication of experience, can be seen to rely on emergent mixed narrative reconstructions combining the experiences of several agents. This research leads to insights into how bottom-up story-telling and autobiographic reconstruction in autonomous, adaptive agents allow temporally grounded behaviour to emerge. The article concludes with a discussion of possible implications of this research direction for future autobiographic, narrative agents.

WriteShield: A Pseudo Thin Client for Prevention of Information Leakage

NASA Astrophysics Data System (ADS)

Kirihata, Yasuhiro; Sameshima, Yoshiki; Onoyama, Takashi; Komoda, Norihisa

While thin-client systems are diffusing as an effective security method in enterprises and organizations, there is a new approach called pseudo thin-client system. In this system, local disks of clients are write-protected and user data is forced to save on the central file server to realize the same security effect of conventional thin-client systems. Since it takes purely the software-based simple approach, it does not require the hardware enhancement of network and servers to reduce the installation cost. However there are several problems such as no write control to external media, memory depletion possibility, and lower security because of the exceptional write permission to the system processes. In this paper, we propose WriteShield, a pseudo thin-client system which solves these issues. In this system, the local disks are write-protected with volume filter driver and it has a virtual cache mechanism to extend the memory cache size for the write protection. This paper presents design and implementation details of WriteShield. Besides we describe the security analysis and simulation evaluation of paging algorithms for virtual cache mechanism and measure the disk I/O performance to verify its feasibility in the actual environment.

Interface Design Implications for Recalling the Spatial Configuration of Virtual Auditory Environments

NASA Astrophysics Data System (ADS)

McMullen, Kyla A.

Although the concept of virtual spatial audio has existed for almost twenty-five years, only in the past fifteen years has modern computing technology enabled the real-time processing needed to deliver high-precision spatial audio. Furthermore, the concept of virtually walking through an auditory environment did not exist. The applications of such an interface have numerous potential uses. Spatial audio has the potential to be used in various manners ranging from enhancing sounds delivered in virtual gaming worlds to conveying spatial locations in real-time emergency response systems. To incorporate this technology in real-world systems, various concerns should be addressed. First, to widely incorporate spatial audio into real-world systems, head-related transfer functions (HRTFs) must be inexpensively created for each user. The present study further investigated an HRTF subjective selection procedure previously developed within our research group. Users discriminated auditory cues to subjectively select their preferred HRTF from a publicly available database. Next, the issue of training to find virtual sources was addressed. Listeners participated in a localization training experiment using their selected HRTFs. The training procedure was created from the characterization of successful search strategies in prior auditory search experiments. Search accuracy significantly improved after listeners performed the training procedure. Next, in the investigation of auditory spatial memory, listeners completed three search and recall tasks with differing recall methods. Recall accuracy significantly decreased in tasks that required the storage of sound source configurations in memory. To assess the impacts of practical scenarios, the present work assessed the performance effects of: signal uncertainty, visual augmentation, and different attenuation modeling. Fortunately, source uncertainty did not affect listeners' ability to recall or identify sound sources. The present study also found that the presence of visual reference frames significantly increased recall accuracy. Additionally, the incorporation of drastic attenuation significantly improved environment recall accuracy. Through investigating the aforementioned concerns, the present study made initial footsteps guiding the design of virtual auditory environments that support spatial configuration recall.

Virtual reality-based prospective memory training program for people with acquired brain injury.

PubMed

Yip, Ben C B; Man, David W K

2013-01-01

Acquired brain injuries (ABI) may display cognitive impairments and lead to long-term disabilities including prospective memory (PM) failure. Prospective memory serves to remember to execute an intended action in the future. PM problems would be a challenge to an ABI patient's successful community reintegration. While retrospective memory (RM) has been extensively studied, treatment programs for prospective memory are rarely reported. The development of a treatment program for PM, which is considered timely, can be cost-effective and appropriate to the patient's environment. A 12-session virtual reality (VR)-based cognitive rehabilitation program was developed using everyday PM activities as training content. 37 subjects were recruited to participate in a pretest-posttest control experimental study to evaluate its treatment effectiveness. Results suggest that significantly better changes were seen in both VR-based and real-life PM outcome measures, related cognitive attributes such as frontal lobe functions and semantic fluency. VR-based training may be well accepted by ABI patients as encouraging improvement has been shown. Large-scale studies of a virtual reality-based prospective memory (VRPM) training program are indicated.

Declarative virtual water maze learning and emotional fear conditioning in primary insomnia.

PubMed

Kuhn, Marion; Hertenstein, Elisabeth; Feige, Bernd; Landmann, Nina; Spiegelhalder, Kai; Baglioni, Chiara; Hemmerling, Johanna; Durand, Diana; Frase, Lukas; Klöppel, Stefan; Riemann, Dieter; Nissen, Christoph

2018-05-02

Healthy sleep restores the brain's ability to adapt to novel input through memory formation based on activity-dependent refinements of the strength of neural transmission across synapses (synaptic plasticity). In line with this framework, patients with primary insomnia often report subjective memory impairment. However, investigations of memory performance did not produce conclusive results. The aim of this study was to further investigate memory performance in patients with primary insomnia in comparison to healthy controls, using two well-characterized learning tasks, a declarative virtual water maze task and emotional fear conditioning. Twenty patients with primary insomnia according to DSM-IV criteria (17 females, three males, 43.5 ± 13.0 years) and 20 good sleeper controls (17 females, three males, 41.7 ± 12.8 years) were investigated in a parallel-group study. All participants completed a hippocampus-dependent virtual Morris water maze task and amygdala-dependent classical fear conditioning. Patients with insomnia showed significantly delayed memory acquisition in the virtual water maze task, but no significant difference in fear acquisition compared with controls. These findings are consistent with the notion that memory processes that emerge from synaptic refinements in a hippocampal-neocortical network are particularly sensitive to chronic disruptions of sleep, while those in a basic emotional amygdala-dependent network may be more resilient. © 2018 European Sleep Research Society.

Reaching to virtual targets: The oblique effect reloaded in 3-D.

PubMed

Kaspiris-Rousellis, Christos; Siettos, Constantinos I; Evdokimidis, Ioannis; Smyrnis, Nikolaos

2017-02-20

Perceiving and reproducing direction of visual stimuli in 2-D space produces the visual oblique effect, which manifests as increased precision in the reproduction of cardinal compared to oblique directions. A second cognitive oblique effect emerges when stimulus information is degraded (such as when reproducing stimuli from memory) and manifests as a systematic distortion where reproduced directions close to the cardinal axes deviate toward the oblique, leading to space expansion at cardinal and contraction at oblique axes. We studied the oblique effect in 3-D using a virtual reality system to present a large number of stimuli, covering the surface of an imaginary half sphere, to which subjects had to reach. We used two conditions, one with no delay (no-memory condition) and one where a three-second delay intervened between stimulus presentation and movement initiation (memory condition). A visual oblique effect was observed for the reproduction of cardinal directions compared to oblique, which did not differ with memory condition. A cognitive oblique effect also emerged, which was significantly larger in the memory compared to the no-memory condition, leading to distortion of directional space with expansion near the cardinal axes and compression near the oblique axes on the hemispherical surface. This effect provides evidence that existing models of 2-D directional space categorization could be extended in the natural 3-D space. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Multiprocessor architectural study

NASA Technical Reports Server (NTRS)

Kosmala, A. L.; Stanten, S. F.; Vandever, W. H.

1972-01-01

An architectural design study was made of a multiprocessor computing system intended to meet functional and performance specifications appropriate to a manned space station application. Intermetrics, previous experience, and accumulated knowledge of the multiprocessor field is used to generate a baseline philosophy for the design of a future SUMC* multiprocessor. Interrupts are defined and the crucial questions of interrupt structure, such as processor selection and response time, are discussed. Memory hierarchy and performance is discussed extensively with particular attention to the design approach which utilizes a cache memory associated with each processor. The ability of an individual processor to approach its theoretical maximum performance is then analyzed in terms of a hit ratio. Memory management is envisioned as a virtual memory system implemented either through segmentation or paging. Addressing is discussed in terms of various register design adopted by current computers and those of advanced design.

Mineralocorticoid receptor stimulation effects on spatial memory in healthy young adults: A study using the virtual Morris Water Maze task.

PubMed

Piber, Dominique; Schultebraucks, Katharina; Mueller, Sven C; Deuter, Christian Eric; Wingenfeld, Katja; Otte, Christian

2016-12-01

Stress hormones such as cortisol are known to influence a wide range of cognitive functions, including hippocampal based spatial memory. In the brain, cortisol acts via two different receptors: the glucocorticoid (GR) and the mineralocorticoid receptor (MR). As the MR has a high density in the hippocampus, we examined the effects of pharmacological MR stimulation on spatial memory. Eighty healthy participants (40 women, 40 men, mean age=23.9years±SD=3.3) completed the virtual Morris Water Maze (vMWM) task to test spatial encoding and spatial memory retrieval after receiving 0.4mg fludrocortisone, a MR agonist, or placebo. There was no effect of MR stimulation on spatial encoding during the vMWM task. However, participants who received fludrocortisone exhibited improved spatial memory retrieval performance. There was neither a main effect of sex nor a sex-by-treatment interaction. In young healthy participants, MR stimulation improved hippocampal based spatial memory retrieval in a virtual Morris Water Maze task. Our study not only confirms the importance of MR function in spatial memory, but suggests beneficial effects of acute MR stimulation on spatial memory retrieval in humans. Copyright © 2016 Elsevier Inc. All rights reserved.

Using virtual reality to distinguish subjects with multiple- but not single-domain amnestic mild cognitive impairment from normal elderly subjects.

PubMed

Mohammadi, Alireza; Kargar, Mahmoud; Hesami, Ehsan

2018-03-01

Spatial disorientation is a hallmark of amnestic mild cognitive impairment (aMCI) and Alzheimer's disease. Our aim was to use virtual reality to determine the allocentric and egocentric memory deficits of subjects with single-domain aMCI (aMCIsd) and multiple-domain aMCI (aMCImd). For this purpose, we introduced an advanced virtual reality navigation task (VRNT) to distinguish these deficits in mild Alzheimer's disease (miAD), aMCIsd, and aMCImd. The VRNT performance of 110 subjects, including 20 with miAD, 30 with pure aMCIsd, 30 with pure aMCImd, and 30 cognitively normal controls was compared. Our newly developed VRNT consists of a virtual neighbourhood (allocentric memory) and virtual maze (egocentric memory). Verbal and visuospatial memory impairments were also examined with Rey Auditory-Verbal Learning Test and Rey-Osterrieth Complex Figure Test, respectively. We found that miAD and aMCImd subjects were impaired in both allocentric and egocentric memory, but aMCIsd subjects performed similarly to the normal controls on both tasks. The miAD, aMCImd, and aMCIsd subjects performed worse on finding the target or required more time in the virtual environment than the aMCImd, aMCIsd, and normal controls, respectively. Our findings indicated the aMCImd and miAD subjects, as well as the aMCIsd subjects, were more impaired in egocentric orientation than allocentric orientation. We concluded that VRNT can distinguish aMCImd subjects, but not aMCIsd subjects, from normal elderly subjects. The VRNT, along with the Rey Auditory-Verbal Learning Test and Rey-Osterrieth Complex Figure Test, can be used as a valid diagnostic tool for properly distinguishing different forms of aMCI. © 2018 Japanese Psychogeriatric Society.

Investigating of Memory - Colours of Intellectually Disabled Children and Virtual Game Addict Students

NASA Astrophysics Data System (ADS)

Sik Lányi, Cecília

We describe an investigation of memory colours. For this investigation Flash test software was developed. 75 observers used this test software in 4 groups: average elementary school children (aged: 8-9 years), intellectually disabled children (age: 9-15), virtual game addict university students (average age: 20) and university students who play with VR games rarely or never (average age: 20). In this pilot test we investigated the difference of memory colours of these 4 groups.

Design, Implementation, and Evaluation of a Virtual Shared Memory System in a Multi-Transputer Network.

DTIC Science & Technology

1987-12-01

Synchronization and Data Passing Mechanism ........ 50 4. System Shut Down .................................................................. 51 5...high performance, fault tolerance, and extensibility. These features are attained by synchronizing and coordinating the dis- tributed multicomputer... synchronizing all processors in the network. In a multitransputer network, processes that communicate with each other do so synchronously . This makes

Intelligent holographic databases

NASA Astrophysics Data System (ADS)

Barbastathis, George

Memory is a key component of intelligence. In the human brain, physical structure and functionality jointly provide diverse memory modalities at multiple time scales. How could we engineer artificial memories with similar faculties? In this thesis, we attack both hardware and algorithmic aspects of this problem. A good part is devoted to holographic memory architectures, because they meet high capacity and parallelism requirements. We develop and fully characterize shift multiplexing, a novel storage method that simplifies disk head design for holographic disks. We develop and optimize the design of compact refreshable holographic random access memories, showing several ways that 1 Tbit can be stored holographically in volume less than 1 m3, with surface density more than 20 times higher than conventional silicon DRAM integrated circuits. To address the issue of photorefractive volatility, we further develop the two-lambda (dual wavelength) method for shift multiplexing, and combine electrical fixing with angle multiplexing to demonstrate 1,000 multiplexed fixed holograms. Finally, we propose a noise model and an information theoretic metric to optimize the imaging system of a holographic memory, in terms of storage density and error rate. Motivated by the problem of interfacing sensors and memories to a complex system with limited computational resources, we construct a computer game of Desert Survival, built as a high-dimensional non-stationary virtual environment in a competitive setting. The efficacy of episodic learning, implemented as a reinforced Nearest Neighbor scheme, and the probability of winning against a control opponent improve significantly by concentrating the algorithmic effort to the virtual desert neighborhood that emerges as most significant at any time. The generalized computational model combines the autonomous neural network and von Neumann paradigms through a compact, dynamic central representation, which contains the most salient features of the sensory inputs, fused with relevant recollections, reminiscent of the hypothesized cognitive function of awareness. The Declarative Memory is searched both by content and address, suggesting a holographic implementation. The proposed computer architecture may lead to a novel paradigm that solves 'hard' cognitive problems at low cost.

Space and Time Partitioning with Hardware Support for Space Applications

NASA Astrophysics Data System (ADS)

Pinto, S.; Tavares, A.; Montenegro, S.

2016-08-01

Complex and critical systems like airplanes and spacecraft implement a very fast growing amount of functions. Typically, those systems were implemented with fully federated architectures, but the number and complexity of desired functions of todays systems led aerospace industry to follow another strategy. Integrated Modular Avionics (IMA) arose as an attractive approach for consolidation, by combining several applications into one single generic computing resource. Current approach goes towards higher integration provided by space and time partitioning (STP) of system virtualization. The problem is existent virtualization solutions are not ready to fully provide what the future of aerospace are demanding: performance, flexibility, safety, security while simultaneously containing Size, Weight, Power and Cost (SWaP-C).This work describes a real time hypervisor for space applications assisted by commercial off-the-shell (COTS) hardware. ARM TrustZone technology is exploited to implement a secure virtualization solution with low overhead and low memory footprint. This is demonstrated by running multiple guest partitions of RODOS operating system on a Xilinx Zynq platform.

The Science of Computing: Virtual Memory

NASA Technical Reports Server (NTRS)

Denning, Peter J.

1986-01-01

In the March-April issue, I described how a computer's storage system is organized as a hierarchy consisting of cache, main memory, and secondary memory (e.g., disk). The cache and main memory form a subsystem that functions like main memory but attains speeds approaching cache. What happens if a program and its data are too large for the main memory? This is not a frivolous question. Every generation of computer users has been frustrated by insufficient memory. A new line of computers may have sufficient storage for the computations of its predecessor, but new programs will soon exhaust its capacity. In 1960, a longrange planning committee at MIT dared to dream of a computer with 1 million words of main memory. In 1985, the Cray-2 was delivered with 256 million words. Computational physicists dream of computers with 1 billion words. Computer architects have done an outstanding job of enlarging main memories yet they have never kept up with demand. Only the shortsighted believe they can.

Application of advanced virtual reality and 3D computer assisted technologies in tele-3D-computer assisted surgery in rhinology.

PubMed

Klapan, Ivica; Vranjes, Zeljko; Prgomet, Drago; Lukinović, Juraj

2008-03-01

The real-time requirement means that the simulation should be able to follow the actions of the user that may be moving in the virtual environment. The computer system should also store in its memory a three-dimensional (3D) model of the virtual environment. In that case a real-time virtual reality system will update the 3D graphic visualization as the user moves, so that up-to-date visualization is always shown on the computer screen. Upon completion of the tele-operation, the surgeon compares the preoperative and postoperative images and models of the operative field, and studies video records of the procedure itself Using intraoperative records, animated images of the real tele-procedure performed can be designed. Virtual surgery offers the possibility of preoperative planning in rhinology. The intraoperative use of computer in real time requires development of appropriate hardware and software to connect medical instrumentarium with the computer and to operate the computer by thus connected instrumentarium and sophisticated multimedia interfaces.

Effects of Virtual Reality on the Cognitive Memory and Handgun Accuracy Development of Law Enforcement Neophytes

ERIC Educational Resources Information Center

Wright, Richard A.

2013-01-01

The purpose of this research was to investigate the effects of virtual reality training on the development of cognitive memory and handgun accuracy by law enforcement neophytes. One hundred and six academy students from 6 different academy classes were divided into two groups, experimental and control. The experimental group was exposed to virtual…

Investigating Ground Swarm Robotics Using Agent Based Simulation

DTIC Science & Technology

2006-12-01

Incorporation of virtual pheromones as a shared memory map is modeled as an additional capability that is found to enhance the robustness and reliability of the...virtual pheromones as a shared memory map is modeled as an additional capability that is found to enhance the robustness and reliability of the swarm... PHEROMONES .......................................... 42 1. Repel Friends under Inorganic SA.................................................. 45 2. Max

Analysis towards VMEM File of a Suspended Virtual Machine

NASA Astrophysics Data System (ADS)

Song, Zheng; Jin, Bo; Sun, Yongqing

With the popularity of virtual machines, forensic investigators are challenged with more complicated situations, among which discovering the evidences in virtualized environment is of significant importance. This paper mainly analyzes the file suffixed with .vmem in VMware Workstation, which stores all pseudo-physical memory into an image. The internal file structure of .vmem file is studied and disclosed. Key information about processes and threads of a suspended virtual machine is revealed. Further investigation into the Windows XP SP3 heap contents is conducted and a proof-of-concept tool is provided. Different methods to obtain forensic memory images are introduced, with both advantages and limits analyzed. We conclude with an outlook.

A three phase optimization method for precopy based VM live migration.

PubMed

Sharma, Sangeeta; Chawla, Meenu

2016-01-01

Virtual machine live migration is a method of moving virtual machine across hosts within a virtualized datacenter. It provides significant benefits for administrator to manage datacenter efficiently. It reduces service interruption by transferring the virtual machine without stopping at source. Transfer of large number of virtual machine memory pages results in long migration time as well as downtime, which also affects the overall system performance. This situation becomes unbearable when migration takes place over slower network or a long distance migration within a cloud. In this paper, precopy based virtual machine live migration method is thoroughly analyzed to trace out the issues responsible for its performance drops. In order to address these issues, this paper proposes three phase optimization (TPO) method. It works in three phases as follows: (i) reduce the transfer of memory pages in first phase, (ii) reduce the transfer of duplicate pages by classifying frequently and non-frequently updated pages, and (iii) reduce the data sent in last iteration of migration by applying the simple RLE compression technique. As a result, each phase significantly reduces total pages transferred, total migration time and downtime respectively. The proposed TPO method is evaluated using different representative workloads on a Xen virtualized environment. Experimental results show that TPO method reduces total pages transferred by 71 %, total migration time by 70 %, downtime by 3 % for higher workload, and it does not impose significant overhead as compared to traditional precopy method. Comparison of TPO method with other methods is also done for supporting and showing its effectiveness. TPO method and precopy methods are also tested at different number of iterations. The TPO method gives better performance even with less number of iterations.

Virtual Doppelgangers: Psychological Effects of Avatars Who Ignore Their Owners

NASA Astrophysics Data System (ADS)

Bailenson, Jeremy N.; Segovia, Kathryn Y.

For a decade, the Virtual Human Interaction Lab has been creating doppelgangers, virtual versions of the self, for research purposes. This chapter considers how humans may be affected by confrontation with virtual versions of themselves, on the basis of well-established psychological theories, including social cognitive theory (social learning theory), media richness theory (information richness theory), and self-perception theory. Experiments carried out in the Lab, and informed by these theories, have explored such notable topics as health communication, marketing, and false memories. The findings of one series of studies suggest that doppelgangerscan show the rewards of exercise and proper eating habits, changing people's health-related behavior as a result. Other studies showed that doppelgangers are powerful marketing agents and can be used in advertisements to create favorable brand impressions among consumers. Other research documented that children have difficulty in distinguishing between an actual memory elicited by a physical world event and a false memory elicited by mental image or doppelganger.

Sexual orientation and spatial memory.

PubMed

Cánovas, Ma Rosa; Cimadevilla, José Manuel

2011-11-01

The present study aimed at determining the influence of sexual orientation in human spatial learning and memory. Participants performed the Boxes Room, a virtual reality version of the Holeboard. In Experiment I, a reference memory task, the position of the hidden rewards remained constant during the whole experiment. In Experiment II, a working memory task, the position of rewards changed between blocks. Each block consisted of two trials: One trial for acquisition and another for retrieval. The results of Experiment I showed that heterosexual men performed better than homosexual men and heterosexual women. They found the rewarded boxes faster. Moreover, homosexual participants committed more errors than heterosexuals. Experiment II showed that working memory abilities are the same in groups of different sexual orientation. These results suggest that sexual orientation is related to spatial navigation abilities, but mostly in men, and limited to reference memory, which depends more on the function of the hippocampal system.

Sparkling Science Programs.

ERIC Educational Resources Information Center

Allen, Denise

1995-01-01

Reviews five compact disc-read only memory (CD-ROM) products and one video series that focus on science projects: (1) "Body Park" (Virtual Entertainment); (2) "The Magic School Bus Explores the Solar System" (Microsoft); (3) "The Magic School Bus Explores the Human Body" (Microsoft); (4) "Science Curriculum Assistance Program" (Demco); and (5)…

Benefits of virtual reality based cognitive rehabilitation through simulated activities of daily living: a randomized controlled trial with stroke patients.

PubMed

Faria, Ana Lúcia; Andrade, Andreia; Soares, Luísa; I Badia, Sergi Bermúdez

2016-11-02

Stroke is one of the most common causes of acquired disability, leaving numerous adults with cognitive and motor impairments, and affecting patients' capability to live independently. There is substancial evidence on post-stroke cognitive rehabilitation benefits, but its implementation is generally limited by the use of paper-and-pencil methods, insufficient personalization, and suboptimal intensity. Virtual reality tools have shown potential for improving cognitive rehabilitation by supporting carefully personalized, ecologically valid tasks through accessible technologies. Notwithstanding important progress in VR-based cognitive rehabilitation systems, specially with Activities of Daily Living (ADL's) simulations, there is still a need of more clinical trials for its validation. In this work we present a one-month randomized controlled trial with 18 stroke in and outpatients from two rehabilitation units: 9 performing a VR-based intervention and 9 performing conventional rehabilitation. The VR-based intervention involved a virtual simulation of a city - Reh@City - where memory, attention, visuo-spatial abilities and executive functions tasks are integrated in the performance of several daily routines. The intervention had levels of difficulty progression through a method of fading cues. There was a pre and post-intervention assessment in both groups with the Addenbrooke Cognitive Examination (primary outcome) and the Trail Making Test A and B, Picture Arrangement from WAIS III and Stroke Impact Scale 3.0 (secondary outcomes). A within groups analysis revealed significant improvements in global cognitive functioning, attention, memory, visuo-spatial abilities, executive functions, emotion and overall recovery in the VR group. The control group only improved in self-reported memory and social participation. A between groups analysis, showed significantly greater improvements in global cognitive functioning, attention and executive functions when comparing VR to conventional therapy. Our results suggest that cognitive rehabilitation through the Reh@City, an ecologically valid VR system for the training of ADL's, has more impact than conventional methods. This trial was not registered because it is a small sample study that evaluates the clinical validity of a prototype virtual reality system.

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…

Virtual vision system with actual flavor by olfactory display

NASA Astrophysics Data System (ADS)

Sakamoto, Kunio; Kanazawa, Fumihiro

2010-11-01

The authors have researched multimedia system and support system for nursing studies on and practices of reminiscence therapy and life review therapy. The concept of the life review is presented by Butler in 1963. The process of thinking back on one's life and communicating about one's life to another person is called life review. There is a famous episode concerning the memory. It is called as Proustian effects. This effect is mentioned on the Proust's novel as an episode that a story teller reminds his old memory when he dipped a madeleine in tea. So many scientists research why smells trigger the memory. The authors pay attention to the relation between smells and memory although the reason is not evident yet. Then we have tried to add an olfactory display to the multimedia system so that the smells become a trigger of reminding buried memories. An olfactory display is a device that delivers smells to the nose. It provides us with special effects, for example to emit smell as if you were there or to give a trigger for reminding us of memories. The authors have developed a tabletop display system connected with the olfactory display. For delivering a flavor to user's nose, the system needs to recognition and measure positions of user's face and nose. In this paper, the authors describe an olfactory display which enables to detect the nose position for an effective delivery.

Performance analysis and kernel size study of the Lynx real-time operating system

NASA Technical Reports Server (NTRS)

Liu, Yuan-Kwei; Gibson, James S.; Fernquist, Alan R.

1993-01-01

This paper analyzes the Lynx real-time operating system (LynxOS), which has been selected as the operating system for the Space Station Freedom Data Management System (DMS). The features of LynxOS are compared to other Unix-based operating system (OS). The tools for measuring the performance of LynxOS, which include a high-speed digital timer/counter board, a device driver program, and an application program, are analyzed. The timings for interrupt response, process creation and deletion, threads, semaphores, shared memory, and signals are measured. The memory size of the DMS Embedded Data Processor (EDP) is limited. Besides, virtual memory is not suitable for real-time applications because page swap timing may not be deterministic. Therefore, the DMS software, including LynxOS, has to fit in the main memory of an EDP. To reduce the LynxOS kernel size, the following steps are taken: analyzing the factors that influence the kernel size; identifying the modules of LynxOS that may not be needed in an EDP; adjusting the system parameters of LynxOS; reconfiguring the device drivers used in the LynxOS; and analyzing the symbol table. The reductions in kernel disk size, kernel memory size and total kernel size reduction from each step mentioned above are listed and analyzed.

Performance analysis of sliding window filtering of two dimensional signals based on stream data processing systems

NASA Astrophysics Data System (ADS)

Kazanskiy, Nikolay; Protsenko, Vladimir; Serafimovich, Pavel

2016-03-01

This research article contains an experiment with implementation of image filtering task in Apache Storm and IBM InfoSphere Streams stream data processing systems. The aim of presented research is to show that new technologies could be effectively used for sliding window filtering of image sequences. The analysis of execution was focused on two parameters: throughput and memory consumption. Profiling was performed on CentOS operating systems running on two virtual machines for each system. The experiment results showed that IBM InfoSphere Streams has about 1.5 to 13.5 times lower memory footprint than Apache Storm, but could be about 2.0 to 2.5 slower on a real hardware.

Handling debugger breakpoints in a shared instruction system

DOEpatents

Gooding, Thomas Michael; Shok, Richard Michael

2014-01-21

A debugger debugs processes that execute shared instructions so that a breakpoint set for one process will not cause a breakpoint to occur in the other processes. A breakpoint is set by recording the original instruction at the desired location and writing a trap instruction to the shared instructions at that location. When a process encounters the breakpoint, the process passes control to the debugger for breakpoint processing if the breakpoint was set at that location for that process. If the trap was not set at that location for that process, the cacheline containing the trap is copied to a small scratchpad memory, and the virtual memory mappings are changed to translate the virtual address of the cacheline to the scratchpad. The original instruction is then written to replace the trap instruction in the scratchpad, so that process can execute the instructions in the scatchpad thereby avoiding the trap instruction.

Key Technologies of Phone Storage Forensics Based on ARM Architecture

NASA Astrophysics Data System (ADS)

Zhang, Jianghan; Che, Shengbing

2018-03-01

Smart phones are mainly running Android, IOS and Windows Phone three mobile platform operating systems. The android smart phone has the best market shares and its processor chips are almost ARM software architecture. The chips memory address mapping mechanism of ARM software architecture is different with x86 software architecture. To forensics to android mart phone, we need to understand three key technologies: memory data acquisition, the conversion mechanism from virtual address to the physical address, and find the system’s key data. This article presents a viable solution which does not rely on the operating system API for a complete solution to these three issues.

Practice of aerobic sports is associated with better spatial memory in adults and older men.

PubMed

Sánchez-Horcajo, Rubén; Llamas-Alonso, Juan; Cimadevilla, José Manuel

2015-01-01

BACKGROUND/STUDY CONTEXT: Cognitive abilities experience diverse age-related changes. Memory complaints are common in aging. The practice of sports is known to benefit brain functioning, improving memory among other abilities. Introduction of virtual reality tasks makes it possible to easily assess cognitive functions such as spatial memory, a hippocampus-dependent cognitive ability. In this study, the authors applied a virtual reality-based task to study spatial reference memory in two groups of men, sportsmen (n=28) and sedentary (n=28), across three different age groups: 50-59, 60-69, and 70-77 years. The data showed that sportsmen outperformed sedentary participants. In addition, there was also a significant effect of the factor age. Hence, older men (70-77 years old) displayed a poorer performance in comparison with the other age groups. These results support the beneficial effect of habitual physical activity in spatial memory.

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

ERIC Educational Resources Information Center

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

2017-01-01

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

ART/Ada design project, phase 1: Project plan

NASA Technical Reports Server (NTRS)

Allen, Bradley P.

1988-01-01

The plan and schedule for Phase 1 of the Ada based ESBT Design Research Project is described. The main platform for the project is a DEC Ada compiler on VAX mini-computers and VAXstations running the Virtual Memory System (VMS) operating system. The Ada effort and lines of code are given in tabular form. A chart is given of the entire project life cycle.

Formal verification of a set of memory management units

NASA Technical Reports Server (NTRS)

Schubert, E. Thomas; Levitt, K.; Cohen, Gerald C.

1992-01-01

This document describes the verification of a set of memory management units (MMU). The verification effort demonstrates the use of hierarchical decomposition and abstract theories. The MMUs can be organized into a complexity hierarchy. Each new level in the hierarchy adds a few significant features or modifications to the lower level MMU. The units described include: (1) a page check translation look-aside module (TLM); (2) a page check TLM with supervisor line; (3) a base bounds MMU; (4) a virtual address translation MMU; and (5) a virtual address translation MMU with memory resident segment table.

Improved associative recall of binary data in volume holographic memories

NASA Astrophysics Data System (ADS)

Betzos, George A.; Laisné, Alexandre; Mitkas, Pericles A.

1999-11-01

A new technique is presented that improves the results of associative recall in a volume holographic memory system. A background is added to the normal search argument to increase the amount of optical power that is used to reconstruct the reference beams in the crystal. This is combined with post-processing of the captured image of the reference beams. The use of both the background and post-processing greatly improves the results by allowing associative recall using small arguments. In addition, the number of false hits is reduced and misses are virtually eliminated.

Executive and memory correlates of age-related differences in wayfinding performances using a virtual reality application.

PubMed

Taillade, Mathieu; Sauzéon, Hélène; Dejos, Marie; Pala, Prashant Arvind; Larrue, Florian; Wallet, Grégory; Gross, Christian; N'Kaoua, Bernard

2013-01-01

The aim of this study was to evaluate in large-scale spaces wayfinding and spatial learning difficulties for older adults in relation to the executive and memory decline associated with aging. We compared virtual reality (VR)-based wayfinding and spatial memory performances between young and older adults. Wayfinding and spatial memory performances were correlated with classical measures of executive and visuo-spatial memory functions, but also with self-reported estimates of wayfinding difficulties. We obtained a significant effect of age on wayfinding performances but not on spatial memory performances. The overall correlations showed significant correlations between the wayfinding performances and the classical measures of both executive and visuo-spatial memory, but only when the age factor was not partialled out. Also, older adults underestimated their wayfinding difficulties. A significant relationship between the wayfinding performances and self-reported wayfinding difficulty estimates is found, but only when the age effect was partialled out. These results show that, even when older adults have an equivalent spatial knowledge to young adults, they had greater difficulties with the wayfinding task, supporting an executive decline view in age-related wayfinding difficulties. However, the correlation results are in favor of both the memory and executive decline views as mediators of age-related differences in wayfinding performances. This is discussed in terms of the relationships between memory and executive functioning in wayfinding task orchestration. Our results also favor the use of objective assessments of everyday navigation difficulties in virtual applications, instead of self-reported questionnaires, since older adults showed difficulties in estimating their everyday wayfinding problems.

FORENSIC ANALYSIS OF WINDOW’S® VIRTUAL MEMORY INCORPORATING THE SYSTEM’S PAGEFILE COUNTERINTELLIGENCE THROUGH MALICIOUS CODE ANALYSIS

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

Jared Stimson

FORENSIC ANALYSIS OF WINDOW’S® VIRTUAL MEMORY INCORPORATING THE SYSTEM’S PAGEFILE Computer Forensics is concerned with the use of computer investigation and analysis techniques in order to collect evidence suitable for presentation in court. The examination of volatile memory is a relatively new but important area in computer forensics. More recently criminals are becoming more forensically aware and are now able to compromise computers without accessing the hard disk of the target computer. This means that traditional incident response practice of pulling the plug will destroy the only evidence of the crime. While some techniques are available for acquiring the contentsmore » of main memory, few exist which can analyze these data in a meaningful way. One reason for this is how memory is managed by the operating system. Data belonging to one process can be distributed arbitrarily across physical memory or the hard disk, making it very difficult to recover useful information. This report will focus on how these disparate sources of information can be combined to give a single, contiguous address space for each process. Using address translation a tool is developed to reconstruct the virtual address space of a process by combining a physical memory dump with the page-file on the hard disk. COUNTERINTELLIGENCE THROUGH MALICIOUS CODE ANALYSIS As computer network technology continues to grow so does the reliance on this technology for everyday business functionality. To appeal to customers and employees alike, businesses are seeking an increased online prescience, and to increase productivity the same businesses are computerizing their day-to-day operations. The combination of a publicly accessible interface to the businesses network, and the increase in the amount of intellectual property present on these networks presents serious risks. All of this intellectual property now faces constant attacks from a wide variety of malicious software that is intended to uncover company and government secrets. Every year billions of dollars are invested in preventing and recovering from the introduction of malicious code into a system. However, there is little research being done on leveraging these attacks for counterintelligence opportunities. With the ever-increasing number of vulnerable computers on the Internet the task of attributing these attacks to an organization or a single person is a daunting one. This thesis will demonstrate the idea of intentionally running a piece of malicious code in a secure environment in order to gain counterintelligence on an attacker.« less

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.

Impact of workstations on criticality analyses at ABB combustion engineering

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

Tarko, L.B.; Freeman, R.S.; O'Donnell, P.F.

1993-01-01

During 1991, ABB Combustion Engineering (ABB C-E) made the transition from a CDC Cyber 990 mainframe for nuclear criticality safety analyses to Hewlett Packard (HP)/Apollo workstations. The primary motivation for this change was improved economics of the workstation and maintaining state-of-the-art technology. The Cyber 990 utilized the NOS operating system with a 60-bit word size. The CPU memory size was limited to 131 100 words of directly addressable memory with an extended 250000 words available. The Apollo workstation environment at ABB consists of HP/Apollo-9000/400 series desktop units used by most application engineers, networked with HP/Apollo DN10000 platforms that use 32-bitmore » word size and function as the computer servers and network administrative CPUS, providing a virtual memory system.« less

Coordinated design of coding and modulation systems

NASA Technical Reports Server (NTRS)

Massey, J. L.

1976-01-01

Work on partial unit memory codes continued; it was shown that for a given virtual state complexity, the maximum free distance over the class of all convolutional codes is achieved within the class of unit memory codes. The effect of phase-lock loop (PLL) tracking error on coding system performance was studied by using the channel cut-off rate as the measure of quality of a modulation system. Optimum modulation signal sets for a non-white Gaussian channel considered an heuristic selection rule based on a water-filling argument. The use of error correcting codes to perform data compression by the technique of syndrome source coding was researched and a weight-and-error-locations scheme was developed that is closely related to LDSC coding.

A discrete Fourier transform for virtual memory machines

NASA Technical Reports Server (NTRS)

Galant, David C.

1992-01-01

An algebraic theory of the Discrete Fourier Transform is developed in great detail. Examination of the details of the theory leads to a computationally efficient fast Fourier transform for the use on computers with virtual memory. Such an algorithm is of great use on modern desktop machines. A FORTRAN coded version of the algorithm is given for the case when the sequence of numbers to be transformed is a power of two.

Spaceborne Processor Array

NASA Technical Reports Server (NTRS)

Chow, Edward T.; Schatzel, Donald V.; Whitaker, William D.; Sterling, Thomas

2008-01-01

A Spaceborne Processor Array in Multifunctional Structure (SPAMS) can lower the total mass of the electronic and structural overhead of spacecraft, resulting in reduced launch costs, while increasing the science return through dynamic onboard computing. SPAMS integrates the multifunctional structure (MFS) and the Gilgamesh Memory, Intelligence, and Network Device (MIND) multi-core in-memory computer architecture into a single-system super-architecture. This transforms every inch of a spacecraft into a sharable, interconnected, smart computing element to increase computing performance while simultaneously reducing mass. The MIND in-memory architecture provides a foundation for high-performance, low-power, and fault-tolerant computing. The MIND chip has an internal structure that includes memory, processing, and communication functionality. The Gilgamesh is a scalable system comprising multiple MIND chips interconnected to operate as a single, tightly coupled, parallel computer. The array of MIND components shares a global, virtual name space for program variables and tasks that are allocated at run time to the distributed physical memory and processing resources. Individual processor- memory nodes can be activated or powered down at run time to provide active power management and to configure around faults. A SPAMS system is comprised of a distributed Gilgamesh array built into MFS, interfaces into instrument and communication subsystems, a mass storage interface, and a radiation-hardened flight computer.

Out of One's Mind: A Study of Involuntary Semantic Memories

ERIC Educational Resources Information Center

Kvavilashvili, Lia; Mandler, George

2004-01-01

The study of memories that pop into one's mind without any conscious attempt to retrieve them began only recently. While there are some studies on involuntary autobiographical memories (e.g., Berntsen, 1996, 1998) research on involuntary semantic memories or mind-popping is virtually non-existent. The latter is defined as an involuntary conscious…

Virtual Reality and Special Needs

ERIC Educational Resources Information Center

Jeffs, Tara L.

2009-01-01

The use of virtual environments for special needs is as diverse as the field of Special Education itself and the individuals it serves. Individuals with special needs often face challenges with attention, language, spatial abilities, memory, higher reasoning and knowledge acquisition. Research in the use of Virtual Learning Environments (VLE)…

Application-Controlled Demand Paging for Out-of-Core Visualization

NASA Technical Reports Server (NTRS)

Cox, Michael; Ellsworth, David; Kutler, Paul (Technical Monitor)

1997-01-01

In the area of scientific visualization, input data sets are often very large. In visualization of Computational Fluid Dynamics (CFD) in particular, input data sets today can surpass 100 Gbytes, and are expected to scale with the ability of supercomputers to generate them. Some visualization tools already partition large data sets into segments, and load appropriate segments as they are needed. However, this does not remove the problem for two reasons: 1) there are data sets for which even the individual segments are too large for the largest graphics workstations, 2) many practitioners do not have access to workstations with the memory capacity required to load even a segment, especially since the state-of-the-art visualization tools tend to be developed by researchers with much more powerful machines. When the size of the data that must be accessed is larger than the size of memory, some form of virtual memory is simply required. This may be by segmentation, paging, or by paged segments. In this paper we demonstrate that complete reliance on operating system virtual memory for out-of-core visualization leads to poor performance. We then describe a paged segment system that we have implemented, and explore the principles of memory management that can be employed by the application for out-of-core visualization. We show that application control over some of these can significantly improve performance. We show that sparse traversal can be exploited by loading only those data actually required. We show also that application control over data loading can be exploited by 1) loading data from alternative storage format (in particular 3-dimensional data stored in sub-cubes), 2) controlling the page size. Both of these techniques effectively reduce the total memory required by visualization at run-time. We also describe experiments we have done on remote out-of-core visualization (when pages are read by demand from remote disk) whose results are promising.

Sex effects on spatial learning but not on spatial memory retrieval in healthy young adults.

PubMed

Piber, Dominique; Nowacki, Jan; Mueller, Sven C; Wingenfeld, Katja; Otte, Christian

2018-01-15

Sex differences have been found in spatial learning and spatial memory, with several studies indicating that males outperform females. We tested in the virtual Morris Water Maze (vMWM) task, whether sex differences in spatial cognitive processes are attributable to differences in spatial learning or spatial memory retrieval in a large student sample. We tested 90 healthy students (45 women and 45 men) with a mean age of 23.5 years (SD=3.5). Spatial learning and spatial memory retrieval were measured by using the vMWM task, during which participants had to search a virtual pool for a hidden platform, facilitated by visual cues surrounding the pool. Several learning trials assessed spatial learning, while a separate probe trial assessed spatial memory retrieval. We found a significant sex effect during spatial learning, with males showing shorter latency and shorter path length, as compared to females (all p<0.001). Yet, there was no significant sex effect in spatial memory retrieval (p=0.615). Furthermore, post-hoc analyses revealed significant sex differences in spatial search strategies (p<0.05), but no difference in the number of platform crossings (p=0.375). Our results indicate that in healthy young adults, males show faster spatial learning in a virtual environment, as compared to females. Interestingly, we found no significant sex differences during spatial memory retrieval. Our study raises the question, whether men and women use different learning strategies, which nevertheless result in equal performances of spatial memory retrieval. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Selective deficit in spatial memory strategies contrast to intact response strategies in patients with schizophrenia spectrum disorders tested in a virtual navigation task.

PubMed

Wilkins, Leanne K; Girard, Todd A; Konishi, Kyoko; King, Matthew; Herdman, Katherine A; King, Jelena; Christensen, Bruce; Bohbot, Veronique D

2013-11-01

Spatial memory is impaired among persons with schizophrenia (SCZ). However, different strategies may be used to solve most spatial memory and navigation tasks. This study investigated the hypothesis that participants with schizophrenia-spectrum disorders (SSD) would demonstrate differential impairment during acquisition and retrieval of target locations when using a hippocampal-dependent spatial strategy, but not a response strategy, which is more associated with caudate function. Healthy control (CON) and SSD participants were tested using the 4-on-8 virtual maze (4/8VM), a virtual navigation task designed to differentiate between participants' use of spatial and response strategies. Consistent with our predictions, SSD participants demonstrated a differential deficit such that those who navigated using a spatial strategy made more errors and took longer to locate targets. In contrast, SSD participants who spontaneously used a response strategy performed as well as CON participants. The differential pattern of spatial-memory impairment in SSD provides only indirect support for underlying hippocampal dysfunction. These findings emphasize the importance of considering individual strategies when investigating SSD-related memory and navigation performance. Future cognitive intervention protocols may harness SSD participants' intact ability to navigate using a response strategy and/or train the deficient ability to navigate using a spatial strategy to improve navigation and memory abilities in participants with SSD. Copyright © 2013 Wiley Periodicals, Inc.

CD8α+ DC trans-presentation of IL-15 to naïve CD8+ T cells produces antigen inexperienced T cells in the periphery with memory phenotype and function

PubMed Central

Sosinowski, Tomasz; White, Jason T.; Cross, Eric; Haluszczak, Catherine; Marrack, Philippa; Gapin, Laurent; Kedl, Ross M.

2013-01-01

Various populations of memory phenotype CD8+ T cells have been described over the last 15–20 years, all of which possess elevated effector functions relative to naïve phenotype cells. Using a technique for isolating antigen specific cells from unprimed hosts, we recently identified a new subset of cells, specific for nominal antigen, but phenotypically and functionally similar to memory cells arising as a result of homeostatic proliferation (HP). We show here that these “Virtual Memory” cells are independent of previously identified “innate memory” cells, arising as a result of their response to IL-15 trans-presentation by lymphoid tissue-resident CD8α+ DCs in the periphery. The absence of IL-15, CD8+ T cell expression of either CD122 or Eomes, or of CD8a+ DCs all lead to the loss of Virtual Memory cells in the host. Our results show that CD8+ T cell homeostatic expansion is an active process within the non-lymphopenic environment, is mediated by IL-15, and produces antigen inexperienced memory cells which retain the capacity to respond to nominal antigen with memory-like function. Preferential engagement of these “Virtual Memory” T cells into a vaccine response could dramatically enhance the rate by which immune protection develops. PMID:23355737

Data General Corporation Advanced Operating System/Virtual Storage (AOS/ VS). Revision 7.60

DTIC Science & Technology

1989-02-22

control list for each directory and data file. An access control list includes the users who can and cannot access files as well as the access...and any required data, it can -5- February 22, 1989 Final Evaluation Report Data General AOS/VS SYSTEM OVERVIEW operate asynchronously and in parallel...memory. The IOC can perform the data transfer without further interventiin from the CPU. The I/O channels interface with the processor or system

Detecting Hardware-assisted Hypervisor Rootkits within Nested Virtualized Environments

DTIC Science & Technology

2012-06-14

least the minimum required for the guest OS and click “Next”. For 64-bit Windows 7 the minimum required is 2048 MB (Figure 66). Figure 66. Memory...prompted for Memory, allocate at least the minimum required for the guest OS, for 64-bit Windows 7 the minimum required is 2048 MB (Figure 79...130 21. Within the virtual disk creation wizard, select VDI for the file type (Figure 81). Figure 81. Select File Type 22. Select Dynamically

Static Memory Deduplication for Performance Optimization in Cloud Computing.

PubMed

Jia, Gangyong; Han, Guangjie; Wang, Hao; Yang, Xuan

2017-04-27

In a cloud computing environment, the number of virtual machines (VMs) on a single physical server and the number of applications running on each VM are continuously growing. This has led to an enormous increase in the demand of memory capacity and subsequent increase in the energy consumption in the cloud. Lack of enough memory has become a major bottleneck for scalability and performance of virtualization interfaces in cloud computing. To address this problem, memory deduplication techniques which reduce memory demand through page sharing are being adopted. However, such techniques suffer from overheads in terms of number of online comparisons required for the memory deduplication. In this paper, we propose a static memory deduplication (SMD) technique which can reduce memory capacity requirement and provide performance optimization in cloud computing. The main innovation of SMD is that the process of page detection is performed offline, thus potentially reducing the performance cost, especially in terms of response time. In SMD, page comparisons are restricted to the code segment, which has the highest shared content. Our experimental results show that SMD efficiently reduces memory capacity requirement and improves performance. We demonstrate that, compared to other approaches, the cost in terms of the response time is negligible.

Static Memory Deduplication for Performance Optimization in Cloud Computing

PubMed Central

Jia, Gangyong; Han, Guangjie; Wang, Hao; Yang, Xuan

2017-01-01

In a cloud computing environment, the number of virtual machines (VMs) on a single physical server and the number of applications running on each VM are continuously growing. This has led to an enormous increase in the demand of memory capacity and subsequent increase in the energy consumption in the cloud. Lack of enough memory has become a major bottleneck for scalability and performance of virtualization interfaces in cloud computing. To address this problem, memory deduplication techniques which reduce memory demand through page sharing are being adopted. However, such techniques suffer from overheads in terms of number of online comparisons required for the memory deduplication. In this paper, we propose a static memory deduplication (SMD) technique which can reduce memory capacity requirement and provide performance optimization in cloud computing. The main innovation of SMD is that the process of page detection is performed offline, thus potentially reducing the performance cost, especially in terms of response time. In SMD, page comparisons are restricted to the code segment, which has the highest shared content. Our experimental results show that SMD efficiently reduces memory capacity requirement and improves performance. We demonstrate that, compared to other approaches, the cost in terms of the response time is negligible. PMID:28448434

Aerobic fitness relates to learning on a virtual Morris Water Task and hippocampal volume in adolescents.

PubMed

Herting, Megan M; Nagel, Bonnie J

2012-08-01

In rodents, exercise increases hippocampal neurogenesis and allows for better learning and memory performance on water maze tasks. While exercise has also been shown to be beneficial for the brain and behavior in humans, no study has examined how exercise impacts spatial learning using a directly translational water maze task, or if these relationships exist during adolescence--a developmental period which the animal literature has shown to be especially vulnerable to exercise effects. In this study, we investigated the influence of aerobic fitness on hippocampal size and subsequent learning and memory, including visuospatial memory using a human analogue of the Morris Water Task, in 34 adolescents. Results showed that higher aerobic fitness predicted better learning on the virtual Morris Water Task and larger hippocampal volumes. No relationship between virtual Morris Water Task memory recall and aerobic fitness was detected. Aerobic fitness, however, did not relate to global brain volume or verbal learning, which might suggest some specificity of the influence of aerobic fitness on the adolescent brain. This study provides a direct translational approach to the existing animal literature on exercise, as well as adds to the sparse research that exists on how aerobic exercise impacts the developing human brain and memory. Published by Elsevier B.V.

Aerobic fitness relates to learning on a virtual morris water task and hippocampal volume in adolescents

PubMed Central

Herting, Megan M.; Nagel, Bonnie J.

2012-01-01

In rodents, exercise increases hippocampal neurogenesis and allows for better learning and memory performance on water maze tasks. While exercise has also been shown to be beneficial for the brain and behavior in humans, no study has examined how exercise impacts spatial learning using a directly translational water maze task, or if these relationships exist during adolescence – a developmental period which the animal literature has shown to be especially vulnerable to exercise effects. In this study, we investigated the influence of aerobic fitness on hippocampal size and subsequent learning and memory, including visuospatial memory using a human analogue of the Morris Water Task, in 34 adolescents. Results showed that higher aerobic fitness predicted better learning on the virtual Morris Water Task and larger hippocampal volumes. No relationship between virtual Morris Water Task memory recall and aerobic fitness was detected. Aerobic fitness, however, did not relate to global brain volume, or verbal learning, which might suggest some specificity of the influence of aerobic fitness on the adolescent brain. This study provides a direct translational approach to the existing animal literature on exercise, as well as adds to the sparse research that exists on how aerobic exercise impacts the developing human brain and memory. PMID:22610054

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

Trichotomous Processes in Early Memory Development, Aging, and Neurocognitive Impairment: A Unified Theory

ERIC Educational Resources Information Center

Brainerd, C. J.; Reyna, V. F.; Howe, M. L.

2009-01-01

One of the most extensively investigated topics in the adult memory literature, dual memory processes, has had virtually no impact on the study of early memory development. The authors remove the key obstacles to such research by formulating a trichotomous theory of recall that combines the traditional dual processes of recollection and…

Inflated speedups in parallel simulations via malloc()

NASA Technical Reports Server (NTRS)

Nicol, David M.

1990-01-01

Discrete-event simulation programs make heavy use of dynamic memory allocation in order to support simulation's very dynamic space requirements. When programming in C one is likely to use the malloc() routine. However, a parallel simulation which uses the standard Unix System V malloc() implementation may achieve an overly optimistic speedup, possibly superlinear. An alternate implementation provided on some (but not all systems) can avoid the speedup anomaly, but at the price of significantly reduced available free space. This is especially severe on most parallel architectures, which tend not to support virtual memory. It is shown how a simply implemented user-constructed interface to malloc() can both avoid artificially inflated speedups, and make efficient use of the dynamic memory space. The interface simply catches blocks on the basis of their size. The problem is demonstrated empirically, and the effectiveness of the solution is shown both empirically and analytically.

The Elderly Perceived Meanings and Values of Virtual Reality Leisure Activities: A Means-End Chain Approach.

PubMed

Lin, Cheng-Shih; Jeng, Mei-Yuan; Yeh, Tsu-Ming

2018-04-03

This study uses means-end chain (MEC) techniques to examine the awareness, decision-making procedure, and personal values of the elderly with regard to virtual reality leisure activities. The results of the study show that elderly respondents value virtual reality leisure activities that are fun, safe, and easy. In terms of outcome benefits, elderly respondents value feeling physically and mentally healthy, firsthand experience, and satisfied curiosity. In value terms, elderly respondents hope that their chosen virtual reality leisure activities improve not only their relationships with others, but also their enjoyment, quality of life, and sense of belonging. The results show that, while consumers with different awarenesses of virtual reality leisure activities have different decision-making processes, they share creating "good memories" as the terminal value with the most significant effect. This presents a potential opportunity to promote virtual reality leisure activities. Relevant bodies or enterprises can seek to create good memories in consumers by developing activities that are safe and fun, promote good health, and provide good service, thereby attracting the interest of elderly consumers.

Humans and machines in space: The vision, the challenge, the payoff; AAS Goddard Memorial Symposium, 29th, Washington, DC, March 14-15, 1991

NASA Astrophysics Data System (ADS)

Johnson, Bradley; May, Gayle L.; Korn, Paula

A recent symposium produced papers in the areas of solar system exploration, man machine interfaces, cybernetics, virtual reality, telerobotics, life support systems and the scientific and technology spinoff from the NASA space program. A number of papers also addressed the social and economic impacts of the space program. For individual titles, see A95-87468 through A95-87479.

Compilation of Abstracts of Theses Submitted by Candidates for Degrees.

DTIC Science & Technology

1984-06-01

Management System for the TI - 59 Programmable Calculator Kersh, T. B. Signal Processor Interface 65 CPT, USA Simulation of the AN/SPY-lA Radar...DESIGN AND IMPLEMENTATION OF A BASIC CROSS-COMPILER AND VIRTUAL MEMORY MANAGEMENT SYSTEM FOR THE TI - 59 PROGRAMMABLE CALCULATOR Mark R. Kindl Captain...Academy, 1974 The instruction set of the TI - 59 Programmable Calculator bears a close similarity to that of an assembler. Though most of the calculator

Merlin - Massively parallel heterogeneous computing

NASA Technical Reports Server (NTRS)

Wittie, Larry; Maples, Creve

1989-01-01

Hardware and software for Merlin, a new kind of massively parallel computing system, are described. Eight computers are linked as a 300-MIPS prototype to develop system software for a larger Merlin network with 16 to 64 nodes, totaling 600 to 3000 MIPS. These working prototypes help refine a mapped reflective memory technique that offers a new, very general way of linking many types of computer to form supercomputers. Processors share data selectively and rapidly on a word-by-word basis. Fast firmware virtual circuits are reconfigured to match topological needs of individual application programs. Merlin's low-latency memory-sharing interfaces solve many problems in the design of high-performance computing systems. The Merlin prototypes are intended to run parallel programs for scientific applications and to determine hardware and software needs for a future Teraflops Merlin network.

Robust holographic storage system design.

PubMed

Watanabe, Takahiro; Watanabe, Minoru

2011-11-21

Demand is increasing daily for large data storage systems that are useful for applications in spacecraft, space satellites, and space robots, which are all exposed to radiation-rich space environment. As candidates for use in space embedded systems, holographic storage systems are promising because they can easily provided the demanded large-storage capability. Particularly, holographic storage systems, which have no rotation mechanism, are demanded because they are virtually maintenance-free. Although a holographic memory itself is an extremely robust device even in a space radiation environment, its associated lasers and drive circuit devices are vulnerable. Such vulnerabilities sometimes engendered severe problems that prevent reading of all contents of the holographic memory, which is a turn-off failure mode of a laser array. This paper therefore presents a proposal for a recovery method for the turn-off failure mode of a laser array on a holographic storage system, and describes results of an experimental demonstration. © 2011 Optical Society of America

Blade runner. Blade server and virtualization technology can help hospitals save money--but they are far from silver bullets.

PubMed

Lawrence, Daphne

2009-03-01

Blade servers and virtualization can reduce infrastructure, maintenance, heating, electric, cooling and equipment costs. Blade server technology is evolving and some elements may become obsolete. There is very little interoperability between blades. Hospitals can virtualize 40 to 60 percent of their servers, and old servers can be reused for testing. Not all applications lend themselves to virtualization--especially those with high memory requirements. CIOs should engage their vendors in virtualization discussions.

Logistics Support Analysis Techniques Guide

DTIC Science & Technology

1985-03-15

LANGUAGE (DATA RECORDS) FORTRAN CDC 6600 D&V FSD P/D A H REMA-RKS: Program n-s-ists of F PLIATIffIONS, approx 4000 line of coding , 3 Safegard, AN/FSC... FORTRAN IV -EW-RAK9-- The model consz.sts of IT--k-LIC- I-U-0NS: approximately 367 lines of SiNCGARS, PERSHING II coding . %.’. ~ LSA TASK INTERFACE...system supported by Computer’ Systems Command. The current version of LADEN is coded totally in FORTRAN 󈧕 for virtual memory operating system

Location-based prospective memory.

PubMed

O'Rear, Andrea E; Radvansky, Gabriel A

2018-02-01

This study explores location-based prospective memory. People often have to remember to do things when in a particular location, such as buying tissues the next time they are in the supermarket. For event cognition theory, location is important for structuring events. However, because event cognition has not been used to examine prospective memory, the question remains of how multiple events will influence prospective memory performance. In our experiments, people delivered messages from store to store in a virtual shopping mall as an ongoing task. The prospective tasks were to do certain activities in certain stores. For Experiment 1, each trial involved one prospective memory task to be done in a single location at one of three delays. The virtual environment and location cues were effective for prospective memory, and performance was unaffected by delay. For Experiment 2, each trial involved two prospective memory tasks, given in either one or two instruction locations, and to be done in either one or two store locations. There was improved performance when people received instructions from two locations and did both tasks in one location relative to other combinations. This demonstrates that location-based event structure influences how well people perform on prospective memory tasks.

Digital image compression for a 2f multiplexing optical setup

NASA Astrophysics Data System (ADS)

Vargas, J.; Amaya, D.; Rueda, E.

2016-07-01

In this work a virtual 2f multiplexing system was implemented in combination with digital image compression techniques and redundant information elimination. Depending on the image type to be multiplexed, a memory-usage saving of as much as 99% was obtained. The feasibility of the system was tested using three types of images, binary characters, QR codes, and grey level images. A multiplexing step was implemented digitally, while a demultiplexing step was implemented in a virtual 2f optical setup following real experimental parameters. To avoid cross-talk noise, each image was codified with a specially designed phase diffraction carrier that would allow the separation and relocation of the multiplexed images on the observation plane by simple light propagation. A description of the system is presented together with simulations that corroborate the method. The present work may allow future experimental implementations that will make use of all the parallel processing capabilities of optical systems.

The Integration of Realistic Episodic Memories Relies on Different Working Memory Processes: Evidence from Virtual Navigation.

PubMed

Plancher, Gaën; Gyselinck, Valérie; Piolino, Pascale

2018-01-01

Memory is one of the most important cognitive functions in a person's life as it is essential for recalling personal memories and performing many everyday tasks. Although a huge number of studies have been conducted in the field, only a few of them investigated memory in realistic situations, due to methodological issues. The various tools that have been developed using virtual environments (VEs) have gained popularity in cognitive psychology and neuropsychology because they enable to create naturalistic and controlled situations, and are thus particularly adapted to the study of episodic memory (EM), for which an ecological evaluation is of prime importance. EM is the conscious recollection of personal events combined with their phenomenological and spatiotemporal encoding contexts. Using an original paradigm in a VE, the objective of the present study was to characterize the construction of episodic memories. While the concept of working memory has become central in the understanding of a wide range of cognitive functions, its role in the integration of episodic memories has seldom been assessed in an ecological context. This experiment aimed at filling this gap by studying how EM is affected by concurrent tasks requiring working memory resources in a realistic situation. Participants navigated in a virtual town and had to memorize as many elements in their spatiotemporal context as they could. During learning, participants had either to perform a concurrent task meant to prevent maintenance through the phonological loop, or a task aimed at preventing maintenance through the visuospatial sketchpad, or no concurrent task. EM was assessed in a recall test performed after learning through various scores measuring the what, where and when of the memories. Results showed that, compared to the control condition with no concurrent task, the prevention of maintenance through the phonological loop had a deleterious impact only on the encoding of central elements. By contrast, the prevention of visuo-spatial maintenance interfered both with the encoding of the temporal context and with the binding. These results suggest that the integration of realistic episodic memories relies on different working memory processes that depend on the nature of the traces.

Analysis of a virtual memory model for maintaining database views

NASA Technical Reports Server (NTRS)

Kinsley, Kathryn C.; Hughes, Charles E.

1992-01-01

This paper presents an analytical model for predicting the performance of a new support strategy for database views. This strategy, called the virtual method, is compared with traditional methods for supporting views. The analytical model's predictions of improved performance by the virtual method are then validated by comparing these results with those achieved in an experimental implementation.

Exploring a novel environment improves motivation and promotes recall of words.

PubMed

Schomaker, Judith; van Bronkhorst, Marthe L V; Meeter, Martijn

2014-01-01

Active exploration of novel environments is known to increase plasticity in animals, promoting long-term potentiation in the hippocampus and enhancing memory formation. These effects can occur during as well as after exploration. In humans novelty's effects on memory have been investigated with other methods, but never in an active exploration paradigm. We therefore investigated whether active spatial exploration of a novel compared to a previously familiarized virtual environment promotes performance on an unrelated word learning task. Exploration of the novel environment enhanced recall, generally thought to be hippocampus-dependent, but not recognition, believed to rely less on the hippocampus. Recall was better for participants that gave higher presence ratings for their experience in the virtual environment. These ratings were higher for the novel compared to the familiar virtual environment, suggesting that novelty increased attention for the virtual rather than real environment; however, this did not explain the effect of novelty on recall.

Workload-Driven Design and Evaluation of Large-Scale Data-Centric Systems

DTIC Science & Technology

2012-05-09

in the batch zone in and out of a low-power state, e.g., sending a “ hibernate ” command via ssh and using Wake-on-LAN or related technologies [85]. If...parameter values for experiments with stand-alone jobs. The mapred.child.java.opts parameter sets the maximum virtual memory of the Java child pro- cesses

Hierarchical process memory: memory as an integral component of information processing

PubMed Central

Hasson, Uri; Chen, Janice; Honey, Christopher J.

2015-01-01

Models of working memory commonly focus on how information is encoded into and retrieved from storage at specific moments. However, in the majority of real-life processes, past information is used continuously to process incoming information across multiple timescales. Considering single unit, electrocorticography, and functional imaging data, we argue that (i) virtually all cortical circuits can accumulate information over time, and (ii) the timescales of accumulation vary hierarchically, from early sensory areas with short processing timescales (tens to hundreds of milliseconds) to higher-order areas with long processing timescales (many seconds to minutes). In this hierarchical systems perspective, memory is not restricted to a few localized stores, but is intrinsic to information processing that unfolds throughout the brain on multiple timescales. “The present contains nothing more than the past, and what is found in the effect was already in the cause.”Henri L Bergson PMID:25980649

A Preliminary Empirical Evaluation of Virtual Reality as a Training Tool for Visual-Spatial Tasks

DTIC Science & Technology

1993-05-01

Hillsdale, NJ: Lawrence Erlbaum Associates. Craik , F.I.M., & Lockhart , R.S. (1972). Levels of processing ; A framework for memory research. Journal of...short-term memory (Bower, 1972; Kanigel, 1981), elaborative rehearsai in short-term memory, and subsequent retrieval from long-term memory ( Craik ... Lockhart , 1972; Chase & Ericsson, 1981), ?nd the superiority of gist over verbatim recall of sentences (Bransford & Franks, 1971). Even memory for simple

Prospective memory impairment in "ecstasy" (MDMA) users.

PubMed

Rendell, Peter G; Gray, Timothy J; Henry, Julie D; Tolan, Anne

2007-11-01

Considerable research indicates that "ecstasy" users perceive their memory for future intentions (prospective memory) to be impaired. However, only one empirical study to date has directly tested how this capacity is affected by ecstasy use, and this study provided relatively limited information regarding the extent, scope, or implications of problems experienced. The present study assessed prospective performance on a laboratory measure of prospective memory that closely represents the types of prospective memory tasks that actually occur in everyday life and provides an opportunity to investigate the different sorts of prospective memory failures that occur ("Virtual Week"). Ecstasy user group (27 current users and 34 nonusers) was between participants, and prospective memory task (regular, irregular, time-check) was within participants. A measure sensitive to specific aspects of psychopathology was also administered. Ecstasy users were significantly impaired on Virtual Week, and these deficits were of a comparable magnitude irrespective of the specific prospective memory task demands. The pattern of results was unchanged after controlling for marijuana use, level of psychopathology, and sleep quality. Further, prospective memory was shown to be significantly impaired for both relatively infrequent and relatively frequent ecstasy users, although for the latter group the magnitude of this deficit was greater. Prospective memory performance is sensitive to regular and even moderate ecstasy use. Importantly, ecstasy users experience generalized difficulties with prospective memory, suggesting that these deficits are likely to have important implications for day-to-day functioning.

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

PubMed Central

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

2010-01-01

Spatial navigation is a widely employed behavior in rodent studies of neuronal circuits underlying cognition, learning and memory. In vivo microscopy combined with genetically-encoded indicators provides important new tools to study neuronal circuits, but has been technically difficult to apply during navigation. We describe methods to image the activity of hippocampal CA1 neurons with sub-cellular resolution in behaving mice. Neurons expressing the genetically encoded calcium indicator GCaMP3 were imaged through a chronic hippocampal window. Head-fixed mice performed spatial behaviors within a setup combining a virtual reality system and a custom built two-photon microscope. Populations of place cells were optically identified, and the correlation between the location of their place fields in the virtual environment and their anatomical location in the local circuit was measured. The combination of virtual reality and high-resolution functional imaging should allow for a new generation of studies to probe neuronal circuit dynamics during behavior. PMID:20890294

Aging Memory Is "Not" a Limiting Factor for Lifelong Learning

ERIC Educational Resources Information Center

Lalovic, Dejan; Gvozdenovic, Vasilije

2015-01-01

Efficient memory is one of the necessary cognitive potentials required for virtually every form of lifelong learning. In this contribution we first briefly review and summarize state of the art of knowledge on memory and related cognitive functions in normal aging. Then we critically discuss a relatively short inventory of clinical, psychometric,…

Virtual Instrument Simulator for CERES

NASA Technical Reports Server (NTRS)

Chapman, John J.

1997-01-01

A benchtop virtual instrument simulator for CERES (Clouds and the Earth's Radiant Energy System) has been built at NASA, Langley Research Center in Hampton, VA. The CERES instruments will fly on several earth orbiting platforms notably NASDA's Tropical Rainfall Measurement Mission (TRMM) and NASA's Earth Observing System (EOS) satellites. CERES measures top of the atmosphere radiative fluxes using microprocessor controlled scanning radiometers. The CERES Virtual Instrument Simulator consists of electronic circuitry identical to the flight unit's twin microprocessors and telemetry interface to the supporting spacecraft electronics and two personal computers (PC) connected to the I/O ports that control azimuth and elevation gimbals. Software consists of the unmodified TRW developed Flight Code and Ground Support Software which serves as the instrument monitor and NASA/TRW developed engineering models of the scanners. The CERES Instrument Simulator will serve as a testbed for testing of custom instrument commands intended to solve in-flight anomalies of the instruments which could arise during the CERES mission. One of the supporting computers supports the telemetry display which monitors the simulator microprocessors during the development and testing of custom instrument commands. The CERES engineering development software models have been modified to provide a virtual instrument running on a second supporting computer linked in real time to the instrument flight microprocessor control ports. The CERES Instrument Simulator will be used to verify memory uploads by the CERES Flight Operations TEAM at NASA. Plots of the virtual scanner models match the actual instrument scan plots. A high speed logic analyzer has been used to track the performance of the flight microprocessor. The concept of using an identical but non-flight qualified microprocessor and electronics ensemble linked to a virtual instrument with identical system software affords a relatively inexpensive simulation system capable of high fidelity.

Milestone Completion Report WBS 1.3.5.05 ECP/VTK-m FY17Q2 [MS-17/01] Better Dynamic Types Design SDA05-1

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

Moreland, Kenneth D.

The FY17Q2 milestone of the ECP/VTK-m project, which is the first milestone, includes the completion of design documents for the introduction of virtual methods into the VTK-m framework. Specifically, the ability from within the code of a device (e.g. GPU or Xeon Phi) to jump to a virtual method specified at run time. This change will enable us to drastically reduce the compile time and the executable code size for the VTK-m library. Our first design introduced the idea of adding virtual functions to classes that are used during algorithm execution. (Virtual methods were previously banned from the so calledmore » execution environment.) The design was straightforward. VTK-m already has the generic concepts of an “array handle” that provides a uniform interface to memory of different structures and an “array portal” that provides generic access to said memory. These array handles and portals use C++ templating to adjust them to different memory structures. This composition provides a powerful ability to adapt to data sources, but requires knowing static types. The proposed design creates a template specialization of an array portal that decorates another array handle while hiding its type. In this way we can wrap any type of static array handle and then feed it to a single compiled instance of a function. The second design focused on the mechanics of implementing virtual methods on parallel devices with a focus on CUDA. Our initial experiments on CUDA showed a very large overhead for using virtual C++ classes with virtual methods, the standard approach. Instead, we are using an alternate method provided by C that uses function pointers. With the completion of this milestone, we are able to move to the implementation of objects with virtual (like) methods. The upshot will be much faster compile times and much smaller library/executable sizes.« less

Does virtual reality have a future for the study of episodic memory in aging?

PubMed

Abichou, Kouloud; La Corte, Valentina; Piolino, Pascale

2017-03-01

Episodic memory is the memory of personally lived events located in time and space, it shapes our identity and allows us to project ourselves into the past and the future. This form of memory is vulnerable to the effects of age and its alteration, hindering the autonomy of the subjects, can predict the evolution towards neurodegenerative disorders. Hence, a better understanding of this type of memory is a priority in the field of public health. Actually, traditional neuropsychological tools are often decontextualized, using simplistic situations that did not require the mobilization of all the characteristics of episodic memory, thus they just offer a partial measure of this complex mnemonic capacity. Nowadays, the virtual reality (VR) is a tool allowing the immersion of subjects in simulations of real situations, rich in spatial and temporal naturalistic contexts. Due to its many characteristics, the VR allows to solve several limitations of the traditional tests. The purpose of this review is to expose studies that investigated episodic memory in normal and Alzheimer's disease using VR in order to address its relevance as a new tool in the future practice of neuropsychology of aging.

Feasibility of Virtual Machine and Cloud Computing Technologies for High Performance Computing

DTIC Science & Technology

2014-05-01

Hat Enterprise Linux SaaS software as a service VM virtual machine vNUMA virtual non-uniform memory access WRF weather research and forecasting...previously mentioned in Chapter I Section B1 of this paper, which is used to run the weather research and forecasting ( WRF ) model in their experiments...against a VMware virtualization solution of WRF . The experiment consisted of running WRF in a standard configuration between the D-VTM and VMware while

Operating systems. [of computers

NASA Technical Reports Server (NTRS)

Denning, P. J.; Brown, R. L.

1984-01-01

A counter operating system creates a hierarchy of levels of abstraction, so that at a given level all details concerning lower levels can be ignored. This hierarchical structure separates functions according to their complexity, characteristic time scale, and level of abstraction. The lowest levels include the system's hardware; concepts associated explicitly with the coordination of multiple tasks appear at intermediate levels, which conduct 'primitive processes'. Software semaphore is the mechanism controlling primitive processes that must be synchronized. At higher levels lie, in rising order, the access to the secondary storage devices of a particular machine, a 'virtual memory' scheme for managing the main and secondary memories, communication between processes by way of a mechanism called a 'pipe', access to external input and output devices, and a hierarchy of directories cataloguing the hardware and software objects to which access must be controlled.

Associative programming language and virtual associative access manager

NASA Technical Reports Server (NTRS)

Price, C.

1978-01-01

APL provides convenient associative data manipulation functions in a high level language. Six statements were added to PL/1 via a preprocessor: CREATE, INSERT, FIND, FOR EACH, REMOVE, and DELETE. They allow complete control of all data base operations. During execution, data base management programs perform the functions required to support the APL language. VAAM is the data base management system designed to support the APL language. APL/VAAM is used by CADANCE, an interactive graphic computer system. VAAM is designed to support heavily referenced files. Virtual memory files, which utilize the paging mechanism of the operating system, are used. VAAM supports a full network data structure. The two basic blocks in a VAAM file are entities and sets. Entities are the basic information element and correspond to PL/1 based structures defined by the user. Sets contain the relationship information and are implemented as arrays.

The Other Intelligences (Oy Vey!).

ERIC Educational Resources Information Center

Chase, Kim

1998-01-01

A middle-school teacher humorously observes seven other intelligences of students: random thinking; virtual memory void (erasing entire sections of personal memory); antigravity (balancing on two chair legs); intravacancy (achieving perfect, effortless aplomb); inter-Origami (intricate note-folding); stealth-kinesthetic (peashooting spitballs…

Mobile, Virtual Enhancements for Rehabilitation (MOVER)

DTIC Science & Technology

2013-11-28

Modeling Autobiographical Memory for Believable Agents, AIIDE, Boston, MA. 2013. From the abstract: “We present a multi-layer hierarchical...connectionist network model for simulating human autobiographical memory in believable agents. Grounded in psychological theory, this model improves on...previous attempts to model agents’ event knowledge by providing a more dynamic and nondeterministic representation of autobiographical memories .” This

Mixed-Handedness Advantages in Episodic Memory Obtained under Conditions of Intentional Learning Extend to Incidental Learning

ERIC Educational Resources Information Center

Christman, Stephen D.; Butler, Michael

2011-01-01

The existence of handedness differences in the retrieval of episodic memories is well-documented, but virtually all have been obtained under conditions of intentional learning. Two experiments are reported that extend the presence of such handedness differences to memory retrieval under conditions of incidental learning. Experiment 1 used Craik…

Directions in parallel programming: HPF, shared virtual memory and object parallelism in pC++

NASA Technical Reports Server (NTRS)

Bodin, Francois; Priol, Thierry; Mehrotra, Piyush; Gannon, Dennis

1994-01-01

Fortran and C++ are the dominant programming languages used in scientific computation. Consequently, extensions to these languages are the most popular for programming massively parallel computers. We discuss two such approaches to parallel Fortran and one approach to C++. The High Performance Fortran Forum has designed HPF with the intent of supporting data parallelism on Fortran 90 applications. HPF works by asking the user to help the compiler distribute and align the data structures with the distributed memory modules in the system. Fortran-S takes a different approach in which the data distribution is managed by the operating system and the user provides annotations to indicate parallel control regions. In the case of C++, we look at pC++ which is based on a concurrent aggregate parallel model.

Contention Modeling for Multithreaded Distributed Shared Memory Machines: The Cray XMT

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

Secchi, Simone; Tumeo, Antonino; Villa, Oreste

Distributed Shared Memory (DSM) machines are a wide class of multi-processor computing systems where a large virtually-shared address space is mapped on a network of physically distributed memories. High memory latency and network contention are two of the main factors that limit performance scaling of such architectures. Modern high-performance computing DSM systems have evolved toward exploitation of massive hardware multi-threading and fine-grained memory hashing to tolerate irregular latencies, avoid network hot-spots and enable high scaling. In order to model the performance of such large-scale machines, parallel simulation has been proved to be a promising approach to achieve good accuracy inmore » reasonable times. One of the most critical factors in solving the simulation speed-accuracy trade-off is network modeling. The Cray XMT is a massively multi-threaded supercomputing architecture that belongs to the DSM class, since it implements a globally-shared address space abstraction on top of a physically distributed memory substrate. In this paper, we discuss the development of a contention-aware network model intended to be integrated in a full-system XMT simulator. We start by measuring the effects of network contention in a 128-processor XMT machine and then investigate the trade-off that exists between simulation accuracy and speed, by comparing three network models which operate at different levels of accuracy. The comparison and model validation is performed by executing a string-matching algorithm on the full-system simulator and on the XMT, using three datasets that generate noticeably different contention patterns.« less

Virtual reality training to enhance behavior and cognitive function among children with attention-deficit/hyperactivity disorder: brief report.

PubMed

Shema-Shiratzky, Shirley; Brozgol, Marina; Cornejo-Thumm, Pablo; Geva-Dayan, Karen; Rotstein, Michael; Leitner, Yael; Hausdorff, Jeffrey M; Mirelman, Anat

2018-05-17

To examine the feasibility and efficacy of a combined motor-cognitive training using virtual reality to enhance behavior, cognitive function and dual-tasking in children with Attention-Deficit/Hyperactivity Disorder (ADHD). Fourteen non-medicated school-aged children with ADHD, received 18 training sessions during 6 weeks. Training included walking on a treadmill while negotiating virtual obstacles. Behavioral symptoms, cognition and gait were tested before and after the training and at 6-weeks follow-up. Based on parental report, there was a significant improvement in children's social problems and psychosomatic behavior after the training. Executive function and memory were improved post-training while attention was unchanged. Gait regularity significantly increased during dual-task walking. Long-term training effects were maintained in memory and executive function. Treadmill-training augmented with virtual-reality is feasible and may be an effective treatment to enhance behavior, cognitive function and dual-tasking in children with ADHD.

Virtual reality-based cognitive training for drug abusers: A randomised controlled trial.

PubMed

Man, David W K

2018-05-08

Non-pharmacological means are being developed to enhance cognitive abilities in drug abusers. This study evaluated virtual reality (VR) as an intervention tool for enhancing cognitive and vocational outcomes in 90 young ketamine users (KU) randomly assigned to a treatment group (virtual reality group, VRG; tutor-administered group, TAG) or wait-listed control group (CG). Two training programmes with similar content but different delivery modes (VR-based and manual-based) were applied using a virtual boutique as a training scenario. Outcome assessments comprised the Digit Vigilance Test, Rivermead Behavioural Memory Test, Wisconsin Cart Sorting Test, work-site test and self-efficacy pre- and post-test and during 3- and 6-month follow-ups. The VRG exhibited significant improvements in attention and improvements in memory that were maintained after 3 months. Both the VRG and TAG exhibited significantly improved vocational skills after training which were maintained during follow-up, and improved self-efficacy. VR-based cognitive training might target cognitive problems in KU.

Acute effects of alcohol on the development of intrusive memories.

PubMed

Bisby, James A; Brewin, Chris R; Leitz, Julie R; Valerie Curran, H

2009-07-01

Post-traumatic stress disorder is characterised by repeated intrusive imagery of the traumatic event. Despite alcohol's impairing effect on memory and frequent involvement in real-life trauma, virtually nothing is known of the interaction between alcohol and trauma memory. We aimed to investigate the acute alcohol effects on spontaneous memories following a trauma film as well as explicit memory for the film. Utilising an independent-group double-blind design, 48 healthy volunteers were randomly allocated to receive alcohol of 0.4 or 0.8 g/kg or a matched placebo drink. A stressful film was viewed post-drink. Skin conductance was monitored throughout and mood and dissociative symptoms were indexed. Volunteers recorded their spontaneous memories of the film daily in an online diary over the following week. Their explicit memory for both gist and details of the film was tested on day 7. Intriguingly, an inverted 'U' alcohol dose-response was observed on intrusive memories with a low dose of alcohol increasing memory intrusions while a high dose decreased intrusions. In contrast, explicit memory performance after 7 days showed a linear dose-response effect of alcohol with both recall and recognition decreasing as dose increased. These findings highlight a striking differential pattern of alcohol's effects on spontaneous memories as compared with explicit memories. Alcohol's effect on spontaneous memories may reflect a dose-dependent impairment of two separate memory systems integral to the processing of different aspects of a traumatic event.

Formal verification of an MMU and MMU cache

NASA Technical Reports Server (NTRS)

Schubert, E. T.

1991-01-01

We describe the formal verification of a hardware subsystem consisting of a memory management unit and a cache. These devices are verified independently and then shown to interact correctly when composed. The MMU authorizes memory requests and translates virtual addresses to real addresses. The cache improves performance by maintaining a LRU (least recently used) list from the memory resident segment table.

Effects of Cognitive Training with and without Aerobic Exercise on Cognitively-Demanding Everyday Activities

PubMed Central

McDaniel, Mark A.; Binder, Ellen F.; Bugg, Julie M.; Waldum, Emily R.; Dufault, Carolyn; Meyer, Amanda; Johanning, Jennifer; Zheng, Jie; Schechtman, Kenneth B.; Kudelka, Chris

2015-01-01

We investigated the potential benefits of a novel cognitive training protocol and an aerobic exercise intervention, both individually and in concert, on older adults’ performances in laboratory simulations of select real-world tasks. The cognitive training focused on a range of cognitive processes, including attentional coordination, prospective memory, and retrospective-memory retrieval, processes that are likely involved in many everyday tasks, and that decline with age. Primary outcome measures were three laboratory tasks that simulated everyday activities: Cooking Breakfast, Virtual Week, and Memory for Health Information. Two months of cognitive training improved older adults’ performance on prospective memory tasks embedded in Virtual Week. Cognitive training, either alone or in combination with six months of aerobic exercise, did not significantly improve Cooking Breakfast or Memory for Health Information. Although gains in aerobic power were comparable to previous reports, aerobic exercise did not produce improvements for the primary outcome measures. Discussion focuses on the possibility that cognitive training programs that include explicit strategy instruction and varied practice contexts may confer gains to older adults for performance on cognitively challenging everyday tasks. PMID:25244489

Dreaming of a Learning Task is Associated with Enhanced Sleep-Dependent Memory Consolidation

PubMed Central

Wamsley, Erin J.; Tucker, Matthew; Payne, Jessica D.; Benavides, Joseph; Stickgold, Robert

2010-01-01

Summary It is now well established that post-learning sleep is beneficial for human memory performance [1–5]. Meanwhile, human and animal studies demonstrate that learning-related neural activity is re-expressed during post-training non-rapid eye movement sleep (NREM) [6–9]. NREM sleep processes appear to be particularly beneficial for hippocampus-dependent forms of memory [1–3, 10]. These observations suggest that learning triggers the reactivation and reorganization of memory traces during sleep, a systems-level process that in turn enhances behavioral performance. Here, we hypothesized that dreaming about a learning experience during NREM sleep would be associated with improved performance on a hippocampus-dependent spatial memory task. Subjects (n=99) were trained on a virtual navigation task, and then retested on the same task 5 hours after initial training. Improved performance at retest was strongly associated with task-related dream imagery during an intervening afternoon nap. Task-related thoughts during wakefulness, in contrast, did not predict improved performance. These observations suggest that sleep-dependent memory consolidation in humans is facilitated by the offline reactivation of recently formed memories, and furthermore, that dream experiences reflect this memory processing. That similar effects were not seen during wakefulness suggests that these mnemonic processes are specific to the sleep state. PMID:20417102

A VLSI VAX chip set

NASA Astrophysics Data System (ADS)

Johnson, W. N.; Herrick, W. V.; Grundmann, W. J.

1984-10-01

For the first time, VLSI technology is used to compress the full functinality and comparable performance of the VAX 11/780 super-minicomputer into a 1.2 M transistor microprocessor chip set. There was no subsetting of the 304 instruction set and the 17 data types, nor reduction in hardware support for the 4 Gbyte virtual memory management architecture. The chipset supports an integral 8 kbyte memory cache, a 13.3 Mbyte/s system bus, and sophisticated multiprocessing. High performance is achieved through microcode optimizations afforded by the large control store, tightly coupled address and data caches, the use of internal and external 32 bit datapaths, the extensive aplication of both microlevel and macrolevel pipelining, and the use of specialized hardware assists.

Sptrace

NASA Technical Reports Server (NTRS)

Burleigh, Scott C.

2011-01-01

Sptrace is a general-purpose space utilization tracing system that is conceptually similar to the commercial Purify product used to detect leaks and other memory usage errors. It is designed to monitor space utilization in any sort of heap, i.e., a region of data storage on some device (nominally memory; possibly shared and possibly persistent) with a flat address space. This software can trace usage of shared and/or non-volatile storage in addition to private RAM (random access memory). Sptrace is implemented as a set of C function calls that are invoked from within the software that is being examined. The function calls fall into two broad classes: (1) functions that are embedded within the heap management software [e.g., JPL's SDR (Simple Data Recorder) and PSM (Personal Space Management) systems] to enable heap usage analysis by populating a virtual time-sequenced log of usage activity, and (2) reporting functions that are embedded within the application program whose behavior is suspect. For ease of use, these functions may be wrapped privately inside public functions offered by the heap management software. Sptrace can be used for VxWorks or RTEMS realtime systems as easily as for Linux or OS/X systems.

Hippocampus-Dependent Goal Localization by Head-Fixed Mice in Virtual Reality.

PubMed

Sato, Masaaki; Kawano, Masako; Mizuta, Kotaro; Islam, Tanvir; Lee, Min Goo; Hayashi, Yasunori

2017-01-01

The demonstration of the ability of rodents to navigate in virtual reality (VR) has made it an important behavioral paradigm for studying spatially modulated neuronal activity in these animals. However, their behavior in such simulated environments remains poorly understood. Here, we show that encoding and retrieval of goal location memory in mice head-fixed in VR depends on the postsynaptic scaffolding protein Shank2 and the dorsal hippocampus. In our newly developed virtual cued goal location task, a head-fixed mouse moves from one end of a virtual linear track to seek rewards given at a target location along the track. The mouse needs to visually recognize the target location and stay there for a short period of time to receive the reward. Transient pharmacological blockade of fast glutamatergic synaptic transmission in the dorsal hippocampus dramatically and reversibly impaired performance of this task. Encoding and updating of virtual cued goal location memory was impaired in mice deficient in the postsynaptic scaffolding protein Shank2, a mouse model of autism that exhibits impaired spatial learning in a real environment. These results highlight the crucial roles of the dorsal hippocampus and postsynaptic protein complexes in spatial learning and navigation in VR.

Hippocampus-Dependent Goal Localization by Head-Fixed Mice in Virtual Reality

PubMed Central

Kawano, Masako; Mizuta, Kotaro; Islam, Tanvir; Lee, Min Goo; Hayashi, Yasunori

2017-01-01

Abstract The demonstration of the ability of rodents to navigate in virtual reality (VR) has made it an important behavioral paradigm for studying spatially modulated neuronal activity in these animals. However, their behavior in such simulated environments remains poorly understood. Here, we show that encoding and retrieval of goal location memory in mice head-fixed in VR depends on the postsynaptic scaffolding protein Shank2 and the dorsal hippocampus. In our newly developed virtual cued goal location task, a head-fixed mouse moves from one end of a virtual linear track to seek rewards given at a target location along the track. The mouse needs to visually recognize the target location and stay there for a short period of time to receive the reward. Transient pharmacological blockade of fast glutamatergic synaptic transmission in the dorsal hippocampus dramatically and reversibly impaired performance of this task. Encoding and updating of virtual cued goal location memory was impaired in mice deficient in the postsynaptic scaffolding protein Shank2, a mouse model of autism that exhibits impaired spatial learning in a real environment. These results highlight the crucial roles of the dorsal hippocampus and postsynaptic protein complexes in spatial learning and navigation in VR. PMID:28484738

Neural correlates of reward-based spatial learning in persons with cocaine dependence.

PubMed

Tau, Gregory Z; Marsh, Rachel; Wang, Zhishun; Torres-Sanchez, Tania; Graniello, Barbara; Hao, Xuejun; Xu, Dongrong; Packard, Mark G; Duan, Yunsuo; Kangarlu, Alayar; Martinez, Diana; Peterson, Bradley S

2014-02-01

Dysfunctional learning systems are thought to be central to the pathogenesis of and impair recovery from addictions. The functioning of the brain circuits for episodic memory or learning that support goal-directed behavior has not been studied previously in persons with cocaine dependence (CD). Thirteen abstinent CD and 13 healthy participants underwent MRI scanning while performing a task that requires the use of spatial cues to navigate a virtual-reality environment and find monetary rewards, allowing the functional assessment of the brain systems for spatial learning, a form of episodic memory. Whereas both groups performed similarly on the reward-based spatial learning task, we identified disturbances in brain regions involved in learning and reward in CD participants. In particular, CD was associated with impaired functioning of medial temporal lobe (MTL), a brain region that is crucial for spatial learning (and episodic memory) with concomitant recruitment of striatum (which normally participates in stimulus-response, or habit, learning), and prefrontal cortex. CD was also associated with enhanced sensitivity of the ventral striatum to unexpected rewards but not to expected rewards earned during spatial learning. We provide evidence that spatial learning in CD is characterized by disturbances in functioning of an MTL-based system for episodic memory and a striatum-based system for stimulus-response learning and reward. We have found additional abnormalities in distributed cortical regions. Consistent with findings from animal studies, we provide the first evidence in humans describing the disruptive effects of cocaine on the coordinated functioning of multiple neural systems for learning and memory.

A fast three-dimensional gamma evaluation using a GPU utilizing texture memory for on-the-fly interpolations.

PubMed

Persoon, Lucas C G G; Podesta, Mark; van Elmpt, Wouter J C; Nijsten, Sebastiaan M J J G; Verhaegen, Frank

2011-07-01

A widely accepted method to quantify differences in dose distributions is the gamma (gamma) evaluation. Currently, almost all gamma implementations utilize the central processing unit (CPU). Recently, the graphics processing unit (GPU) has become a powerful platform for specific computing tasks. In this study, we describe the implementation of a 3D gamma evaluation using a GPU to improve calculation time. The gamma evaluation algorithm was implemented on an NVIDIA Tesla C2050 GPU using the compute unified device architecture (CUDA). First, several cubic virtual phantoms were simulated. These phantoms were tested with varying dose cube sizes and set-ups, introducing artificial dose differences. Second, to show applicability in clinical practice, five patient cases have been evaluated using the 3D dose distribution from a treatment planning system as the reference and the delivered dose determined during treatment as the comparison. A calculation time comparison between the CPU and GPU was made with varying thread-block sizes including the option of using texture or global memory. A GPU over CPU speed-up of 66 +/- 12 was achieved for the virtual phantoms. For the patient cases, a speed-up of 57 +/- 15 using the GPU was obtained. A thread-block size of 16 x 16 performed best in all cases. The use of texture memory improved the total calculation time, especially when interpolation was applied. Differences between the CPU and GPU gammas were negligible. The GPU and its features, such as texture memory, decreased the calculation time for gamma evaluations considerably without loss of accuracy.

Degrading emotional memories induced by a virtual reality paradigm.

PubMed

Cuperus, Anne A; Laken, Maarten; van den Hout, Marcel A; Engelhard, Iris M

2016-09-01

In Eye Movement and Desensitization and Reprocessing (EMDR) therapy, a dual-task approach is used: patients make horizontal eye movements while they recall aversive memories. Studies showed that this reduces memory vividness and/or emotionality. A strong explanation is provided by working memory theory, which suggests that other taxing dual-tasks are also effective. Experiment 1 tested whether a visuospatial task which was carried out while participants were blindfolded taxes working memory. Experiment 2 tested whether this task degrades negative memories induced by a virtual reality (VR) paradigm. In experiment 1, participants responded to auditory cues with or without simultaneously carrying out the visuospatial task. In experiment 2, participants recalled negative memories induced by a VR paradigm. The experimental group simultaneously carried out the visuospatial task, and a control group merely recalled the memories. Changes in self-rated memory vividness and emotionality were measured. The slowing down of reaction times due to the visuospatial task indicated that its cognitive load was greater than the load of the eye movements task in previous studies. The task also led to reductions in emotionality (but not vividness) of memories induced by the VR paradigm. Weaknesses are that only males were tested in experiment 1, and the effectiveness of the VR fear/trauma induction was not assessed with ratings of mood or intrusions in experiment 2. The results suggest that the visuospatial task may be applicable in clinical settings, and the VR paradigm may provide a useful method of inducing negative memories. Copyright © 2016 Elsevier Ltd. All rights reserved.

MnemoCity Task: Assessment of Childrens Spatial Memory Using Stereoscopy and Virtual Environments.

PubMed

Rodríguez-Andrés, David; Juan, M-Carmen; Méndez-López, Magdalena; Pérez-Hernández, Elena; Lluch, Javier

2016-01-01

This paper presents the MnemoCity task, which is a 3D application that introduces the user into a totally 3D virtual environment to evaluate spatial short-term memory. A study has been carried out to validate the MnemoCity task for the assessment of spatial short-term memory in children, by comparing the children's performance in the developed task with current approaches. A total of 160 children participated in the study. The task incorporates two types of interaction: one based on standard interaction and another one based on natural interaction involving physical movement by the user. There were no statistically significant differences in the results of the task using the two types of interaction. Furthermore, statistically significant differences were not found in relation to gender. The correlations between scores were obtained using the MnemoCity task and a traditional procedure for assessing spatial short-term memory. Those results revealed that the type of interaction used did not affect the performance of children in the MnemoCity task.

High and low schizotypal female subjects do not differ in spatial memory abilities in a virtual reality task.

PubMed

García-Montes, José Manuel; Noguera, Carmen; Alvarez, Dolores; Ruiz, Marina; Cimadevilla Redondo, José Manuel

2014-01-01

Schizotypy is a psychological construct related to schizophrenia. The exact relationship between both entities is not clear. In recent years, schizophrenia has been associated with hippocampal abnormalities and spatial memory problems. The aim of this study was to determine possible links between high schizotypy (HS) and low schizotypy (LS) and spatial abilities, using virtual reality tasks. We hypothesised that the HS group would exhibit a lower performance in spatial memory tasks than the LS group. Two groups of female students were formed according to their score on the ESQUIZO-Q-A questionnaire. HS and LS subjects were tested on two different tasks: the Boxes Room task, a spatial memory task sensitive to hippocampal alterations and a spatial recognition task. Data showed that both groups mastered both tasks. Groups differed in personality features but not in spatial performance. These results provide valuable information about the schizotypy-schizophrenia connections. Schizotypal subjects are not impaired on spatial cognition and, accordingly, the schizotypy-schizophrenia relationship is not straightforward.

Urgent Virtual Machine Eviction with Enlightened Post-Copy

DTIC Science & Technology

2015-12-01

memory is in use, almost all of which is by Memcached. MySQL : The VMs run MySQL 5.6, and the clients execute OLTPBenchmark [3] using the Twitter...workload with scale factor of 960. The VMs are each allocated 16 cores and 30 GB of memory, and MySQL is configured with a 16 GB buffer pool in memory. The...operation mix for 5 minutes as a warm-up. At the time of migration, MySQL uses approximately 17 GB of memory, and almost all of the 30 GB memory is

General-purpose interface bus for multiuser, multitasking computer system

NASA Technical Reports Server (NTRS)

Generazio, Edward R.; Roth, Don J.; Stang, David B.

1990-01-01

The architecture of a multiuser, multitasking, virtual-memory computer system intended for the use by a medium-size research group is described. There are three central processing units (CPU) in the configuration, each with 16 MB memory, and two 474 MB hard disks attached. CPU 1 is designed for data analysis and contains an array processor for fast-Fourier transformations. In addition, CPU 1 shares display images viewed with the image processor. CPU 2 is designed for image analysis and display. CPU 3 is designed for data acquisition and contains 8 GPIB channels and an analog-to-digital conversion input/output interface with 16 channels. Up to 9 users can access the third CPU simultaneously for data acquisition. Focus is placed on the optimization of hardware interfaces and software, facilitating instrument control, data acquisition, and processing.

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

PubMed Central

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

2015-01-01

The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with “moderate” hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. SIGNIFICANCE STATEMENT In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated spatial recall using a virtual environment in two groups of patients with hippocampal damage (moderate/severe) and a normal control group. The results showed that patients with severe hippocampal damage are impaired in learning and recalling allocentric spatial information. Furthermore, hippocampal volume reduction impaired allocentric navigation beyond what can be predicted by memory quotient as a widely used measure of general memory function. PMID:26490854

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

PubMed

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

2015-10-21

The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with "moderate" hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated spatial recall using a virtual environment in two groups of patients with hippocampal damage (moderate/severe) and a normal control group. The results showed that patients with severe hippocampal damage are impaired in learning and recalling allocentric spatial information. Furthermore, hippocampal volume reduction impaired allocentric navigation beyond what can be predicted by memory quotient as a widely used measure of general memory function. Copyright © 2015 Guderian et al.

GRIDVIEW: Recent Improvements in Research and Education Software for Exploring Mars Topography

NASA Technical Reports Server (NTRS)

Roark, J. H.; Masuoka, C. M.; Frey, H. V.

2004-01-01

GRIDVIEW is being developed by the GEODYNAMICS Branch at NASA's Goddard Space Flight Center and can be downloaded on the web at http://geodynamics.gsfc.nasa.gov/gridview/. The program is very mature and has been successfully used for more than four years, but is still under development as we add new features for data analysis and visualization. The software can run on any computer supported by the IDL virtual machine application supplied by RSI. The virtual machine application is currently available for recent versions of MS Windows, MacOS X, Red Hat Linux and UNIX. Minimum system memory requirement is 32 MB, however loading large data sets may require larger amounts of RAM to function adequately.

Tactical Operations Analysis Support Facility.

DTIC Science & Technology

1981-05-01

Punch/Reader 2 DMC-11AR DDCMP Micro Processor 2 DMC-11DA Network Link Line Unit 2 DL-11E Async Serial Line Interface 4 Intel IN-1670 448K Words MOS Memory...86 5.3 VIRTUAL PROCESSORS - VAX-11/750 ........................... 89 5.4 A RELATIONAL DATA MANAGEMENT SYSTEM - ORACLE...Central Processing Unit (CPU) is a 16 bit processor for high-speed, real time applications, and for large multi-user, multi- task, time shared

A lightweight sensor network management system design

USGS Publications Warehouse

Yuan, F.; Song, W.-Z.; Peterson, N.; Peng, Y.; Wang, L.; Shirazi, B.; LaHusen, R.

2008-01-01

In this paper, we propose a lightweight and transparent management framework for TinyOS sensor networks, called L-SNMS, which minimizes the overhead of management functions, including memory usage overhead, network traffic overhead, and integration overhead. We accomplish this by making L-SNMS virtually transparent to other applications hence requiring minimal integration. The proposed L-SNMS framework has been successfully tested on various sensor node platforms, including TelosB, MICAz and IMote2. ?? 2008 IEEE.

Decision Support Systems for Launch and Range Operations Using Jess

NASA Technical Reports Server (NTRS)

Thirumalainambi, Rajkumar

2007-01-01

The virtual test bed for launch and range operations developed at NASA Ames Research Center consists of various independent expert systems advising on weather effects, toxic gas dispersions and human health risk assessment during space-flight operations. An individual dedicated server supports each expert system and the master system gather information from the dedicated servers to support the launch decision-making process. Since the test bed is based on the web system, reducing network traffic and optimizing the knowledge base is critical to its success of real-time or near real-time operations. Jess, a fast rule engine and powerful scripting environment developed at Sandia National Laboratory has been adopted to build the expert systems providing robustness and scalability. Jess also supports XML representation of knowledge base with forward and backward chaining inference mechanism. Facts added - to working memory during run-time operations facilitates analyses of multiple scenarios. Knowledge base can be distributed with one inference engine performing the inference process. This paper discusses details of the knowledge base and inference engine using Jess for a launch and range virtual test bed.

Experience with V-STORE: considerations on presence in virtual environments for effective neuropsychological rehabilitation of executive functions.

PubMed

Lo Priore, Corrado; Castelnuovo, Gianluca; Liccione, Diego; Liccione, Davide

2003-06-01

The paper discusses the use of immersive virtual reality systems for the cognitive rehabilitation of dysexecutive syndrome, usually caused by prefrontal brain injuries. With respect to classical P&P and flat-screen computer rehabilitative tools, IVR systems might prove capable of evoking a more intense and compelling sense of presence, thanks to the highly naturalistic subject-environment interaction allowed. Within a constructivist framework applied to holistic rehabilitation, we suggest that this difference might enhance the ecological validity of cognitive training, partly overcoming the implicit limits of a lab setting, which seem to affect non-immersive procedures especially when applied to dysexecutive symptoms. We tested presence in a pilot study applied to a new VR-based rehabilitation tool for executive functions, V-Store; it allows patients to explore a virtual environment where they solve six series of tasks, ordered for complexity and designed to stimulate executive functions, programming, categorical abstraction, short-term memory and attention. We compared sense of presence experienced by unskilled normal subjects, randomly assigned to immersive or non-immersive (flat screen) sessions of V-Store, through four different indexes: self-report questionnaire, psychophysiological (GSR, skin conductance), neuropsychological (incidental recall memory test related to auditory information coming from the "real" environment) and count of breaks in presence (BIPs). Preliminary results show in the immersive group a significantly higher GSR response during tasks; neuropsychological data (fewer recalled elements from "reality") and less BIPs only show a congruent but yet non-significant advantage for the immersive condition; no differences were evident from the self-report questionnaire. A larger experimental group is currently under examination to evaluate significance of these data, which also might prove interesting with respect to the question of objective-subjective measures of presence.

Humans and machines in space: The vision, the challenge, the payoff; Proceedings of the 29th Goddard Memorial Symposium, Washington, Mar. 14, 15, 1991

NASA Astrophysics Data System (ADS)

Johnson, Bradley; May, Gayle L.; Korn, Paula

The present conference discusses the currently envisioned goals of human-machine systems in spacecraft environments, prospects for human exploration of the solar system, and plausible methods for meeting human needs in space. Also discussed are the problems of human-machine interaction in long-duration space flights, remote medical systems for space exploration, the use of virtual reality for planetary exploration, the alliance between U.S. Antarctic and space programs, and the economic and educational impacts of the U.S. space program.

SoCRocket: A Virtual Platform for SoC Design

NASA Astrophysics Data System (ADS)

Fossati, Luca; Schuster, Thomas; Meyer, Rolf; Berekovic, Mladen

2013-08-01

Both in the commercial and in the aerospace domain, the continuous increase of transistor density on a single die is leading towards the production of more and more complex systems on a single chip, with an increasing number of components. This brought to the introduction of the System-On-Chip (SoC) architecture, that integrates on a single circuit all the elements of a full system. This strive for efficient utilization of the available silicon has triggered several paradigm shifts in system design. Similarly to what happened in the early 1990s, when VHDL and Verilog took over from schematic design, today SystemC and Transaction Level Modeling [1] are about to further raise the design abstraction level. Such descriptions have to be accurate enough to describe the entire system throughout the phases of its development, and has to provide enough flexibility to be refined iteratively up to the point where the actual device can be produced using current process technology. Besides requiring new languages and methodologies, the complexity of current and future SoCs (SCOC3 [16] and NGMP [5] are example in the space domain) forces the SoC design process to rely on pre-designed or third party components. Components obtained from different providers, and even those designed by different teams of the same company, may be heterogeneous on several aspects: design domains, interfaces, abstraction levels, granularity, etc. Therefore, component integration is required at system level. Only by applying design re-use it is possible to successfully and timely design such complex SoCs. This transition to new languages and design methods is also motivated by the implementation with software of an increasing amount of system functionalities. Hence the need for methodologies to enable early software development and which allow the analysis of the performance of the combined Hw/Sw system, as their design and configuration cannot be performed separately. Virtual Prototyping is a key approach in this sense, enabling embedded software developers to start development earlier in the system design cycle, and cutting the dependency on the physical system hardware. In order to successfully implement the described methodologies, it is requested to have access to the a wide selection of IP-Cores (and related SystemC/TLM models) and access to the latest Electronic Design Automation (EDA, [17]) tools. On the one hand, for what concerns the European Space landscape, such IP-Cores are provided by the European Space Agency [4] and a few other suppliers (e.g Aeroflex Gaisler with GRLIB [2]). On the other hand, for what concerns the related high abstraction models and related design methodologies (partly depicted in Figure 1), the European Space Agency, through the Braunschweig Technische Universitat, has started the development of the SoCRocket Virtual Platform [8]. Together with the Virtual Platform infrastructure SoCRocket contains a library of IP-Core models. The SoCRocket library has been built around the TrapGen LEON instruction set simulator [15]. The library contains a variety of SystemC simulation models such as caches, memory management unit, AMBA interconnect, memory controller, memories, interrupt controller, timer and more. All models are TLM2.0 compliant and come in both loosely-timed and approximately timed coding styles. As later-on presented more in detail, the runtime reconfiguration, the completeness of tools and models, as well as the fact that all simulation IPs have a freely available RTL counterpart differentiates SoCRocket from other commercially available Virtual Platforms. Moreover, due to their TLM2.0 compliance the provided models are not bound to the SoCRocket environment but they can be used with alternative tools, such as Cadence Virtual Platform [3] or Synopsys Platform Architect [10]. The paper is organized as follows: Section 2 presents the architecture of SoCRocket and the related library of SystemC models. Finally Section 3 shows how SoCRocket was used to optimize the design of a LEON3-based SoC targeted to the execution of an implementation of the CCSDS standard n.123 for the lossless compression of hyperspectral images.

Real-life memory and spatial navigation in patients with focal epilepsy: ecological validity of a virtual reality supermarket task.

PubMed

Grewe, P; Lahr, D; Kohsik, A; Dyck, E; Markowitsch, H J; Bien, C G; Botsch, M; Piefke, M

2014-02-01

Ecological assessment and training of real-life cognitive functions such as visual-spatial abilities in patients with epilepsy remain challenging. Some studies have applied virtual reality (VR) paradigms, but external validity of VR programs has not sufficiently been proven. Patients with focal epilepsy (EG, n=14) accomplished an 8-day program in a VR supermarket, which consisted of learning and buying items on a shopping list. Performance of the EG was compared with that of healthy controls (HCG, n=19). A comprehensive neuropsychological examination was administered. Real-life performance was investigated in a real supermarket. Learning in the VR supermarket was significantly impaired in the EG on different VR measures. Delayed free recall of products did not differ between the EG and the HCG. Virtual reality scores were correlated with neuropsychological measures of visual-spatial cognition, subjective estimates of memory, and performance in the real supermarket. The data indicate that our VR approach allows for the assessment of real-life visual-spatial memory and cognition in patients with focal epilepsy. The multimodal, active, and complex VR paradigm may particularly enhance visual-spatial cognitive resources. Copyright © 2013 Elsevier Inc. All rights reserved.

Virtual Human Analogs to Rodent Spatial Pattern Separation and Completion Memory Tasks

ERIC Educational Resources Information Center

Paleja, Meera; Girard, Todd A.; Christensen, Bruce K.

2011-01-01

Spatial pattern separation (SPS) and spatial pattern completion (SPC) have played an increasingly important role in computational and rodent literatures as processes underlying associative memory. SPS and SPC are complementary processes, allowing the formation of unique representations and the reconstruction of complete spatial environments based…

Geometric Determinants of Human Spatial Memory

ERIC Educational Resources Information Center

Hartley, Tom; Trinkler, Iris; Burgess, Neil

2004-01-01

Geometric alterations to the boundaries of a virtual environment were used to investigate the representations underlying human spatial memory. Subjects encountered a cue object in a simple rectangular enclosure, with distant landmarks for orientation. After a brief delay, during which they were removed from the arena, subjects were returned to it…

Ecologically relevant episodic memory assessment indicates an attenuated age-related memory loss - A virtual reality study.

PubMed

Pflueger, Marlon O; Stieglitz, Rolf-Dieter; Lemoine, Patrick; Leyhe, Thomas

2018-06-07

Since the advent of imaging techniques, the role of the neuropsychological assessment has changed. Questions concerning everyday functionality became primarily important and, thus, ecologically valid neuropsychological assessments are mandatory. Virtual reality (VR) environments might provide a way of implementing immersive cognitive assessments with a higher degree of everyday-life-related cognitive demands. We report on a VR-based episodic memory examination in N = 30 young and N = 18 healthy older adults (HOA) using a kitchen scene. The test procedure was designed to be structurally comparable to clinically used California Verbal Learning Test (CVLT) in terms of repeated learning trials as well as short and long delayed recall measures. The results showed that age-related learning and performance decrements were mainly evident in the CVLT but not in the VR-memory examination. The ecologically valid VR-memory examination might provide a more accurate "age-fair" estimation of everyday-life-related memory demands in HOA than the frequently and clinically used CVLT. We concluded this from our finding of context-related automatic and effortless activations of deeply experience based encoding and retrieval strategies with regard to everyday-life-related objects in the HOA, which might not be paralleled by learning arbitrary word associations. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Eye movements, visual search and scene memory, in an immersive virtual environment.

PubMed

Kit, Dmitry; Katz, Leor; Sullivan, Brian; Snyder, Kat; Ballard, Dana; Hayhoe, Mary

2014-01-01

Visual memory has been demonstrated to play a role in both visual search and attentional prioritization in natural scenes. However, it has been studied predominantly in experimental paradigms using multiple two-dimensional images. Natural experience, however, entails prolonged immersion in a limited number of three-dimensional environments. The goal of the present experiment was to recreate circumstances comparable to natural visual experience in order to evaluate the role of scene memory in guiding eye movements in a natural environment. Subjects performed a continuous visual-search task within an immersive virtual-reality environment over three days. We found that, similar to two-dimensional contexts, viewers rapidly learn the location of objects in the environment over time, and use spatial memory to guide search. Incidental fixations did not provide obvious benefit to subsequent search, suggesting that semantic contextual cues may often be just as efficient, or that many incidentally fixated items are not held in memory in the absence of a specific task. On the third day of the experience in the environment, previous search items changed in color. These items were fixated upon with increased probability relative to control objects, suggesting that memory-guided prioritization (or Surprise) may be a robust mechanisms for attracting gaze to novel features of natural environments, in addition to task factors and simple spatial saliency.

Memory conformity and the perceived accuracy of self versus other.

PubMed

Allan, Kevin; Midjord, J Palli; Martin, Doug; Gabbert, Fiona

2012-02-01

Here, we demonstrate that the decision to conform to another person's memory involves a strategic trade-off that balances the accuracy of one's own memory against that of another person. We showed participants three household scenes, one for 30 s, one for 60 s, and one for 120 s. Half were told that they would encode each scene for half as long as their virtual partner, and half were told that they would encode each scene for twice as long as their virtual partner. On a subsequent two-alternative-forced choice (2AFC) memory test, the simulated answer of the partner (accurate, errant, or no response) was shown before participants responded. Conformity to the partner's responses was significantly enhanced for the 30-s versus the 60- and 120-s scenes. This pattern, however, was present only in the group who believed that they had encoded each scene for half as long as their partner, even though the short-duration scene had the lowest baseline 2AFC accuracy in both groups and was also subjectively rated as the least memorable by both groups. Our reliance on other people's memory is therefore dynamically and strategically adjusted according to knowledge of the conditions under which we and other people have acquired different memories.

Comparative analysis of video processing and 3D rendering for cloud video games using different virtualization technologies

NASA Astrophysics Data System (ADS)

Bada, Adedayo; Alcaraz-Calero, Jose M.; Wang, Qi; Grecos, Christos

2014-05-01

This paper describes a comprehensive empirical performance evaluation of 3D video processing employing the physical/virtual architecture implemented in a cloud environment. Different virtualization technologies, virtual video cards and various 3D benchmarks tools have been utilized in order to analyse the optimal performance in the context of 3D online gaming applications. This study highlights 3D video rendering performance under each type of hypervisors, and other factors including network I/O, disk I/O and memory usage. Comparisons of these factors under well-known virtual display technologies such as VNC, Spice and Virtual 3D adaptors reveal the strengths and weaknesses of the various hypervisors with respect to 3D video rendering and streaming.

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.

Controlling memory impairment in elderly adults using virtual reality memory training: a randomized controlled pilot study.

PubMed

Optale, Gabriele; Urgesi, Cosimo; Busato, Valentina; Marin, Silvia; Piron, Lamberto; Priftis, Konstantinos; Gamberini, Luciano; Capodieci, Salvatore; Bordin, Adalberto

2010-05-01

Memory decline is a prevalent aspect of aging but may also be the first sign of cognitive pathology. Virtual reality (VR) using immersion and interaction may provide new approaches to the treatment of memory deficits in elderly individuals. The authors implemented a VR training intervention to try to lessen cognitive decline and improve memory functions. The authors randomly assigned 36 elderly residents of a rest care facility (median age 80 years) who were impaired on the Verbal Story Recall Test either to the experimental group (EG) or the control group (CG). The EG underwent 6 months of VR memory training (VRMT) that involved auditory stimulation and VR experiences in path finding. The initial training phase lasted 3 months (3 auditory and 3 VR sessions every 2 weeks), and there was a booster training phase during the following 3 months (1 auditory and 1 VR session per week). The CG underwent equivalent face-to-face training sessions using music therapy. Both groups participated in social and creative and assisted-mobility activities. Neuropsychological and functional evaluations were performed at baseline, after the initial training phase, and after the booster training phase. The EG showed significant improvements in memory tests, especially in long-term recall with an effect size of 0.7 and in several other aspects of cognition. In contrast, the CG showed progressive decline. The authors suggest that VRMT may improve memory function in elderly adults by enhancing focused attention.

The use of ZFP lossy floating point data compression in tornado-resolving thunderstorm simulations

NASA Astrophysics Data System (ADS)

Orf, L.

2017-12-01

In the field of atmospheric science, numerical models are used to produce forecasts of weather and climate and serve as virtual laboratories for scientists studying atmospheric phenomena. In both operational and research arenas, atmospheric simulations exploiting modern supercomputing hardware can produce a tremendous amount of data. During model execution, the transfer of floating point data from memory to the file system is often a significant bottleneck where I/O can dominate wallclock time. One way to reduce the I/O footprint is to compress the floating point data, which reduces amount of data saved to the file system. In this presentation we introduce LOFS, a file system developed specifically for use in three-dimensional numerical weather models that are run on massively parallel supercomputers. LOFS utilizes the core (in-memory buffered) HDF5 driver and includes compression options including ZFP, a lossy floating point data compression algorithm. ZFP offers several mechanisms for specifying the amount of lossy compression to be applied to floating point data, including the ability to specify the maximum absolute error allowed in each compressed 3D array. We explore different maximum error tolerances in a tornado-resolving supercell thunderstorm simulation for model variables including cloud and precipitation, temperature, wind velocity and vorticity magnitude. We find that average compression ratios exceeding 20:1 in scientifically interesting regions of the simulation domain produce visually identical results to uncompressed data in visualizations and plots. Since LOFS splits the model domain across many files, compression ratios for a given error tolerance can be compared across different locations within the model domain. We find that regions of high spatial variability (which tend to be where scientifically interesting things are occurring) show the lowest compression ratios, whereas regions of the domain with little spatial variability compress extremely well. We observe that the overhead for compressing data with ZFP is low, and that compressing data in memory reduces the amount of memory overhead needed to store the virtual files before they are flushed to disk.

Managing coherence via put/get windows

DOEpatents

Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton on Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Hoenicke, Dirk [Ossining, NY; Ohmacht, Martin [Yorktown Heights, NY

2011-01-11

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an area of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.

Managing coherence via put/get windows

DOEpatents

Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton on Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Hoenicke, Dirk [Ossining, NY; Ohmacht, Martin [Yorktown Heights, NY

2012-02-21

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an area of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.

Accurately Decoding Visual Information from fMRI Data Obtained in a Realistic Virtual Environment

DTIC Science & Technology

2015-06-09

Center for Learning and Memory , The University of Texas at Austin, 100 E 24th Street, Stop C7000, Austin, TX 78712, USA afloren@utexas.edu Received: 18...information from fMRI data obtained in a realistic virtual environment. Front. Hum. Neurosci. 9:327. doi: 10.3389/fnhum.2015.00327 Accurately decoding...visual information from fMRI data obtained in a realistic virtual environment Andrew Floren 1*, Bruce Naylor 2, Risto Miikkulainen 3 and David Ress 4

Software-Controlled Caches in the VMP Multiprocessor

DTIC Science & Technology

1986-03-01

programming system level that Processors is tuned for the VMP design. In this vein, we are interested in exploring how far the software support can go to ...handled in software, analogously to the handling agement of the shared program state is familiar and of virtual memory page faults. Hardware support for...ensure good behavior, as opposed to how Each cache miss results in bus traffic. Table 2 pro- vides the bus cost for the "average" cache miss. Fig

Virtual Communities in the Law Enforcement Environment: Do These Systems Lead to Enhanced Organizational Memory

DTIC Science & Technology

2008-12-01

forwarded to other users. D. DISCUSSION BOARD Discussion boards are commonly referred to as “ forums ” and are used for asynchronous communications.31...This technology allows for open ended communications in written format. A user can start a discussion by adding a posting to a community forum ...and deployed. Some of the built in features include, forums , discussion boards, custom lists, calendar, to-do lists, wiki technology, email

Automated Virtual Machine Introspection for Host-Based Intrusion Detection

DTIC Science & Technology

2009-03-01

boxes represent the code and data sections of each process in memory with arrows representing hooks planted by malware to jump to the malware code...a useful indication of intrusion, it is also susceptible to mimicry and concurrency attacks [Pro03,Wat07]. Additionally, most research abstracts away...sequence of system calls that accomplishes his or her intent [WS02]. This “ mimicry attack” takes advantage of the fact that many HIDS discard the pa

Effect that Smell Presentation Has on an Individual in Regards to Eye Catching and Memory

NASA Astrophysics Data System (ADS)

Tomono, Akira; Kanda, Koyori; Otake, Syunya

If a person's eyes are greater attracted to the target objects by matching the smell to an important scene of a movie or commercial image, the value of the image contents will rise. In this paper, we attempt to describe the image system that can also present smells, and the reason behind the improvement, from gaze point analysis, of the presence of smell when it is matched to the image. The relationship between the eye catching property and the position of the sight object was examined using the image with the scene where someone eats three kinds of fruits. These objects were gazed at for a long time once releasing their smells. When the smell was not released, the gaze moved actively to try and receive a lot of information from the entire screen. On the other hand, when the smell was inserted, the subject was interested in the object and there was a tendency for their gaze to stay within the narrow area surrounding the image. Moreover, we investigated the effect on the memory by putting the smell on the flowers in the virtual flower shop using immersive virtual reality system (HoloStageTM). It was memorized more easily compared with a scentless case. It seems that the viewer obtains the information actively by reacting to its smell.

A robot arm simulation with a shared memory multiprocessor machine

NASA Technical Reports Server (NTRS)

Kim, Sung-Soo; Chuang, Li-Ping

1989-01-01

A parallel processing scheme for a single chain robot arm is presented for high speed computation on a shared memory multiprocessor. A recursive formulation that is derived from a virtual work form of the d'Alembert equations of motion is utilized for robot arm dynamics. A joint drive system that consists of a motor rotor and gears is included in the arm dynamics model, in order to take into account gyroscopic effects due to the spinning of the rotor. The fine grain parallelism of mechanical and control subsystem models is exploited, based on independent computation associated with bodies, joint drive systems, and controllers. Efficiency and effectiveness of the parallel scheme are demonstrated through simulations of a telerobotic manipulator arm. Two different mechanical subsystem models, i.e., with and without gyroscopic effects, are compared, to show the trade-off between efficiency and accuracy.

The attentional blink reveals serial working memory encoding: evidence from virtual and human event-related potentials.

PubMed

Craston, Patrick; Wyble, Brad; Chennu, Srivas; Bowman, Howard

2009-03-01

Observers often miss a second target (T2) if it follows an identified first target item (T1) within half a second in rapid serial visual presentation (RSVP), a finding termed the attentional blink. If two targets are presented in immediate succession, however, accuracy is excellent (Lag 1 sparing). The resource sharing hypothesis proposes a dynamic distribution of resources over a time span of up to 600 msec during the attentional blink. In contrast, the ST(2) model argues that working memory encoding is serial during the attentional blink and that, due to joint consolidation, Lag 1 is the only case where resources are shared. Experiment 1 investigates the P3 ERP component evoked by targets in RSVP. The results suggest that, in this context, P3 amplitude is an indication of bottom-up strength rather than a measure of cognitive resource allocation. Experiment 2, employing a two-target paradigm, suggests that T1 consolidation is not affected by the presentation of T2 during the attentional blink. However, if targets are presented in immediate succession (Lag 1 sparing), they are jointly encoded into working memory. We use the ST(2) model's neural network implementation, which replicates a range of behavioral results related to the attentional blink, to generate "virtual ERPs" by summing across activation traces. We compare virtual to human ERPs and show how the results suggest a serial nature of working memory encoding as implied by the ST(2) model.

Is All Motivation Good for Learning? Dissociable Influences of Approach and Avoidance Motivation in Declarative Memory

ERIC Educational Resources Information Center

Murty, Vishnu P.; LaBar, Kevin S.; Hamilton, Derek A.; Adcock, R. Alison

2011-01-01

The present study investigated the effects of approach versus avoidance motivation on declarative learning. Human participants navigated a virtual reality version of the Morris water task, a classic spatial memory paradigm, adapted to permit the experimental manipulation of motivation during learning. During this task, participants were instructed…

MnemoCity Task: Assessment of Childrens Spatial Memory Using Stereoscopy and Virtual Environments

PubMed Central

Rodríguez-Andrés, David; Méndez-López, Magdalena; Pérez-Hernández, Elena; Lluch, Javier

2016-01-01

This paper presents the MnemoCity task, which is a 3D application that introduces the user into a totally 3D virtual environment to evaluate spatial short-term memory. A study has been carried out to validate the MnemoCity task for the assessment of spatial short-term memory in children, by comparing the children’s performance in the developed task with current approaches. A total of 160 children participated in the study. The task incorporates two types of interaction: one based on standard interaction and another one based on natural interaction involving physical movement by the user. There were no statistically significant differences in the results of the task using the two types of interaction. Furthermore, statistically significant differences were not found in relation to gender. The correlations between scores were obtained using the MnemoCity task and a traditional procedure for assessing spatial short-term memory. Those results revealed that the type of interaction used did not affect the performance of children in the MnemoCity task. PMID:27579715

Shared virtual memory and generalized speedup

NASA Technical Reports Server (NTRS)

Sun, Xian-He; Zhu, Jianping

1994-01-01

Generalized speedup is defined as parallel speed over sequential speed. The generalized speedup and its relation with other existing performance metrics, such as traditional speedup, efficiency, scalability, etc., are carefully studied. In terms of the introduced asymptotic speed, it was shown that the difference between the generalized speedup and the traditional speedup lies in the definition of the efficiency of uniprocessor processing, which is a very important issue in shared virtual memory machines. A scientific application was implemented on a KSR-1 parallel computer. Experimental and theoretical results show that the generalized speedup is distinct from the traditional speedup and provides a more reasonable measurement. In the study of different speedups, various causes of superlinear speedup are also presented.

Contributions of Medial Temporal Lobe and Striatal Memory Systems to Learning and Retrieving Overlapping Spatial Memories

PubMed Central

Brown, Thackery I.; Stern, Chantal E.

2014-01-01

Many life experiences share information with other memories. In order to make decisions based on overlapping memories, we need to distinguish between experiences to determine the appropriate behavior for the current situation. Previous work suggests that the medial temporal lobe (MTL) and medial caudate interact to support the retrieval of overlapping navigational memories in different contexts. The present study used functional magnetic resonance imaging (fMRI) in humans to test the prediction that the MTL and medial caudate play complementary roles in learning novel mazes that cross paths with, and must be distinguished from, previously learned routes. During fMRI scanning, participants navigated virtual routes that were well learned from prior training while also learning new mazes. Critically, some routes learned during scanning shared hallways with those learned during pre-scan training. Overlap between mazes required participants to use contextual cues to select between alternative behaviors. Results demonstrated parahippocampal cortex activity specific for novel spatial cues that distinguish between overlapping routes. The hippocampus and medial caudate were active for learning overlapping spatial memories, and increased their activity for previously learned routes when they became context dependent. Our findings provide novel evidence that the MTL and medial caudate play complementary roles in the learning, updating, and execution of context-dependent navigational behaviors. PMID:23448868

Eye Movements, Visual Search and Scene Memory, in an Immersive Virtual Environment

PubMed Central

Sullivan, Brian; Snyder, Kat; Ballard, Dana; Hayhoe, Mary

2014-01-01

Visual memory has been demonstrated to play a role in both visual search and attentional prioritization in natural scenes. However, it has been studied predominantly in experimental paradigms using multiple two-dimensional images. Natural experience, however, entails prolonged immersion in a limited number of three-dimensional environments. The goal of the present experiment was to recreate circumstances comparable to natural visual experience in order to evaluate the role of scene memory in guiding eye movements in a natural environment. Subjects performed a continuous visual-search task within an immersive virtual-reality environment over three days. We found that, similar to two-dimensional contexts, viewers rapidly learn the location of objects in the environment over time, and use spatial memory to guide search. Incidental fixations did not provide obvious benefit to subsequent search, suggesting that semantic contextual cues may often be just as efficient, or that many incidentally fixated items are not held in memory in the absence of a specific task. On the third day of the experience in the environment, previous search items changed in color. These items were fixated upon with increased probability relative to control objects, suggesting that memory-guided prioritization (or Surprise) may be a robust mechanisms for attracting gaze to novel features of natural environments, in addition to task factors and simple spatial saliency. PMID:24759905

The effect of visual and interaction fidelity on spatial cognition in immersive virtual environments.

PubMed

Mania, Katerina; Wooldridge, Dave; Coxon, Matthew; Robinson, Andrew

2006-01-01

Accuracy of memory performance per se is an imperfect reflection of the cognitive activity (awareness states) that underlies performance in memory tasks. The aim of this research is to investigate the effect of varied visual and interaction fidelity of immersive virtual environments on memory awareness states. A between groups experiment was carried out to explore the effect of rendering quality on location-based recognition memory for objects and associated states of awareness. The experimental space, consisting of two interconnected rooms, was rendered either flat-shaded or using radiosity rendering. The computer graphics simulations were displayed on a stereo head-tracked Head Mounted Display. Participants completed a recognition memory task after exposure to the experimental space and reported one of four states of awareness following object recognition. These reflected the level of visual mental imagery involved during retrieval, the familiarity of the recollection, and also included guesses. Experimental results revealed variations in the distribution of participants' awareness states across conditions while memory performance failed to reveal any. Interestingly, results revealed a higher proportion of recollections associated with mental imagery in the flat-shaded condition. These findings comply with similar effects revealed in two earlier studies summarized here, which demonstrated that the less "naturalistic" interaction interface or interface of low interaction fidelity provoked a higher proportion of recognitions based on visual mental images.

Fractional discrete-time consensus models for single- and double-summator dynamics

NASA Astrophysics Data System (ADS)

Wyrwas, Małgorzata; Mozyrska, Dorota; Girejko, Ewa

2018-04-01

The leader-following consensus problem of fractional-order multi-agent discrete-time systems is considered. In the systems, interactions between opinions are defined like in Krause and Cucker-Smale models but the memory is included by taking the fractional-order discrete-time operator on the left-hand side of the nonlinear systems. In this paper, we investigate fractional-order models of opinions for the single- and double-summator dynamics of discrete-time by analytical methods as well as by computer simulations. The necessary and sufficient conditions for the leader-following consensus are formulated by proposing a consensus control law for tracking the virtual leader.

Sleep enhances a spatially mediated generalization of learned values

PubMed Central

Tolat, Anisha; Spiers, Hugo J.

2015-01-01

Sleep is thought to play an important role in memory consolidation. Here we tested whether sleep alters the subjective value associated with objects located in spatial clusters that were navigated to in a large-scale virtual town. We found that sleep enhances a generalization of the value of high-value objects to the value of locally clustered objects, resulting in an impaired memory for the value of high-valued objects. Our results are consistent with (a) spatial context helping to bind items together in long-term memory and serve as a basis for generalizing across memories and (b) sleep mediating memory effects on salient/reward-related items. PMID:26373834

Aspects of GPU perfomance in algorithms with random memory access

NASA Astrophysics Data System (ADS)

Kashkovsky, Alexander V.; Shershnev, Anton A.; Vashchenkov, Pavel V.

2017-10-01

The numerical code for solving the Boltzmann equation on the hybrid computational cluster using the Direct Simulation Monte Carlo (DSMC) method showed that on Tesla K40 accelerators computational performance drops dramatically with increase of percentage of occupied GPU memory. Testing revealed that memory access time increases tens of times after certain critical percentage of memory is occupied. Moreover, it seems to be the common problem of all NVidia's GPUs arising from its architecture. Few modifications of the numerical algorithm were suggested to overcome this problem. One of them, based on the splitting the memory into "virtual" blocks, resulted in 2.5 times speed up.

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

Gebis, Joseph; Oliker, Leonid; Shalf, John

The disparity between microprocessor clock frequencies and memory latency is a primary reason why many demanding applications run well below peak achievable performance. Software controlled scratchpad memories, such as the Cell local store, attempt to ameliorate this discrepancy by enabling precise control over memory movement; however, scratchpad technology confronts the programmer and compiler with an unfamiliar and difficult programming model. In this work, we present the Virtual Vector Architecture (ViVA), which combines the memory semantics of vector computers with a software-controlled scratchpad memory in order to provide a more effective and practical approach to latency hiding. ViVA requires minimal changesmore » to the core design and could thus be easily integrated with conventional processor cores. To validate our approach, we implemented ViVA on the Mambo cycle-accurate full system simulator, which was carefully calibrated to match the performance on our underlying PowerPC Apple G5 architecture. Results show that ViVA is able to deliver significant performance benefits over scalar techniques for a variety of memory access patterns as well as two important memory-bound compact kernels, corner turn and sparse matrix-vector multiplication -- achieving 2x-13x improvement compared the scalar version. Overall, our preliminary ViVA exploration points to a promising approach for improving application performance on leading microprocessors with minimal design and complexity costs, in a power efficient manner.« less

Estimating Distance in Real and Virtual Environments: Does Order Make a Difference?

PubMed Central

Ziemer, Christine J.; Plumert, Jodie M.; Cremer, James F.; Kearney, Joseph K.

2010-01-01

This investigation examined how the order in which people experience real and virtual environments influences their distance estimates. Participants made two sets of distance estimates in one of the following conditions: 1) real environment first, virtual environment second; 2) virtual environment first, real environment second; 3) real environment first, real environment second; or 4) virtual environment first, virtual environment second. In Experiment 1, participants imagined how long it would take to walk to targets in real and virtual environments. Participants’ first estimates were significantly more accurate in the real than in the virtual environment. When the second environment was the same as the first environment (real-real and virtual-virtual), participants’ second estimates were also more accurate in the real than in the virtual environment. When the second environment differed from the first environment (real-virtual and virtual-real), however, participants’ second estimates did not differ significantly across the two environments. A second experiment in which participants walked blindfolded to targets in the real environment and imagined how long it would take to walk to targets in the virtual environment replicated these results. These subtle, yet persistent order effects suggest that memory can play an important role in distance perception. PMID:19525540

Effects of enactment in episodic memory: a pilot virtual reality study with young and elderly adults.

PubMed

Jebara, Najate; Orriols, Eric; Zaoui, Mohamed; Berthoz, Alain; Piolino, Pascale

2014-01-01

None of the previous studies on aging have tested the influence of action with respect to the degree of interaction with the environment (active or passive navigation) and the source of itinerary choice (self or externally imposed), on episodic memory (EM) encoding. The aim of this pilot study was to explore the influence of these factors on feature binding (the association between what, where, and when) in EM and on the subjective sense of remembering. Navigation in a virtual city was performed by 64 young and 64 older adults in one of four modes of exploration: (1) passive condition where participants were immersed as passengers of a virtual car [no interaction, no itinerary control (IC)], (2) IC (the subject chose the itinerary, but did not drive the car), (3) low, or (4) high navigation control (the subject just moved the car on rails or drove the car with a steering-wheel and a gas pedal on a fixed itinerary, respectively). The task was to memorize as many events encountered in the virtual environment as possible along with their factual (what), spatial (where), and temporal (when) details, and then to perform immediate and delayed memory tests. An age-related decline was evidenced for immediate and delayed feature binding. Compared to passive and high navigation conditions, and regardless of age-groups, feature binding was enhanced by low navigation and IC conditions. The subjective sense of remembering was boosted by the IC in older adults. Memory performance following high navigation was specifically linked to variability in executive functions. The present findings suggest that the decision of the itinerary is beneficial to boost EM in aging, although it does not eliminate age-related deficits. Active navigation can also enhance EM when it is not too demanding for subjects' cognitive resources.

Effects of Enactment in Episodic Memory: A Pilot Virtual Reality Study with Young and Elderly Adults

PubMed Central

Jebara, Najate; Orriols, Eric; Zaoui, Mohamed; Berthoz, Alain; Piolino, Pascale

2014-01-01

None of the previous studies on aging have tested the influence of action with respect to the degree of interaction with the environment (active or passive navigation) and the source of itinerary choice (self or externally imposed), on episodic memory (EM) encoding. The aim of this pilot study was to explore the influence of these factors on feature binding (the association between what, where, and when) in EM and on the subjective sense of remembering. Navigation in a virtual city was performed by 64 young and 64 older adults in one of four modes of exploration: (1) passive condition where participants were immersed as passengers of a virtual car [no interaction, no itinerary control (IC)], (2) IC (the subject chose the itinerary, but did not drive the car), (3) low, or (4) high navigation control (the subject just moved the car on rails or drove the car with a steering-wheel and a gas pedal on a fixed itinerary, respectively). The task was to memorize as many events encountered in the virtual environment as possible along with their factual (what), spatial (where), and temporal (when) details, and then to perform immediate and delayed memory tests. An age-related decline was evidenced for immediate and delayed feature binding. Compared to passive and high navigation conditions, and regardless of age-groups, feature binding was enhanced by low navigation and IC conditions. The subjective sense of remembering was boosted by the IC in older adults. Memory performance following high navigation was specifically linked to variability in executive functions. The present findings suggest that the decision of the itinerary is beneficial to boost EM in aging, although it does not eliminate age-related deficits. Active navigation can also enhance EM when it is not too demanding for subjects’ cognitive resources. PMID:25566069

A virtual reality task based on animal research – spatial learning and memory in patients after the first episode of schizophrenia

PubMed Central

Fajnerová, Iveta; Rodriguez, Mabel; Levčík, David; Konrádová, Lucie; Mikoláš, Pavol; Brom, Cyril; Stuchlík, Aleš; Vlček, Kamil; Horáček, Jiří

2014-01-01

Objectives: Cognitive deficit is considered to be a characteristic feature of schizophrenia disorder. A similar cognitive dysfunction was demonstrated in animal models of schizophrenia. However, the poor comparability of methods used to assess cognition in animals and humans could be responsible for low predictive validity of current animal models. In order to assess spatial abilities in schizophrenia and compare our results with the data obtained in animal models, we designed a virtual analog of the Morris water maze (MWM), the virtual Four Goals Navigation (vFGN) task. Methods: Twenty-nine patients after the first psychotic episode with schizophrenia symptoms and a matched group of healthy volunteers performed the vFGN task. They were required to find and remember four hidden goal positions in an enclosed virtual arena. The task consisted of two parts. The Reference memory (RM) session with a stable goal position was designed to test spatial learning. The Delayed-matching-to-place (DMP) session presented a modified working memory protocol designed to test the ability to remember a sequence of three hidden goal positions. Results: Data obtained in the RM session show impaired spatial learning in schizophrenia patients compared to the healthy controls in pointing and navigation accuracy. The DMP session showed impaired spatial memory in schizophrenia during the recall of spatial sequence and a similar deficit in spatial bias in the probe trials. The pointing accuracy and the quadrant preference showed higher sensitivity toward the cognitive deficit than the navigation accuracy. Direct navigation to the goal was affected by sex and age of the tested subjects. The age affected spatial performance only in healthy controls. Conclusions: Despite some limitations of the study, our results correspond well with the previous studies in animal models of schizophrenia and support the decline of spatial cognition in schizophrenia, indicating the usefulness of the vFGN task in comparative research. PMID:24904329

Integration Toolkit and Methods (ITKM) Corporate Data Integration Tools (CDIT). Review of the State-of-the-Art with Respect to Integration Toolkits and Methods (ITKM)

DTIC Science & Technology

1992-06-01

system capabilities \\Jch as memory management and network communications are provided by a virtual machine-type operating environment. Various human ...thinking. The elements of this substrate include representational formality, genericity, a method of formal analysis, and augmentation of human analytical...the form of identifying: the data entity itself; its aliases (including how the data is presented th programs or human users in the form of copy

Virtual Mourning and Memory Construction on Facebook: Here Are the Terms of Use

ERIC Educational Resources Information Center

McEwen, Rhonda N.; Scheaffer, Kathleen

2013-01-01

This article investigates the online information practices of persons grieving and mourning via Facebook. It examines how, or whether, these practices and Facebook's terms of use policies have implications for the bereaved and/or the memory of the deceased. To explore these questions, we compared traditional publicly recorded asynchronous…

Fear reactivation prior to exposure therapy: does it facilitate the effects of VR exposure in a randomized clinical sample?

PubMed

Shiban, Youssef; Brütting, Johanna; Pauli, Paul; Mühlberger, Andreas

2015-03-01

The current study is the first to examine whether reactivation of fear memory prior to exposure therapy reduces relapse in a randomized clinical sample. In a standardized treatment protocol combining virtual reality and in-vivo exposure, patients underwent a fear reactivation procedure using a virtual spider 10 min prior to a virtual reality (VR) exposure (reactivation group: RG, n = 15). A control group (CG, n = 17) was exposed to a virtual plant 10 min prior to the VR exposure. Outcome measures were a VR spontaneous recovery test (SRT) and in-vivo a behavioral avoidance test assessed 24 h after VR exposure. One week later an in-vivo exposure session followed. Additionally, a follow-up using psychometric assessment was conducted six months after the first session. Both groups benefitted significantly and equally from the combined treatment, and importantly, the SRT revealed no return of fear in both groups. Furthermore, follow-up tests showed long-term treatment effects with no group differences. Due to different study components (VR treatment and in-vivo), we were not able to determine which treatment module was mainly responsible for the long-term treatment effect. Furthermore, no direct measure of memory destabilization was possible in this study. Our treatment package was highly effective in reducing phobic fear up to 6 months following treatment. Explicit fear reactivation prior to exposure was not beneficial in VR exposure treatment, possibly due to a failure to induce a memory destabilization or due to an implicit fear reactivation prior to treatment in both groups.

Simplifying and speeding the management of intra-node cache coherence

DOEpatents

Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton on Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Phillip [Cortlandt Manor, NY; Hoenicke, Dirk [Ossining, NY; Ohmacht, Martin [Yorktown Heights, NY

2012-04-17

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an area of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.

Managing coherence via put/get windows

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

Blumrich, Matthias A; Chen, Dong; Coteus, Paul W

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an areamore » of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.« less

The impact of pre-existing anxiety on affective and cognitive processing of a Virtual Reality analogue trauma.

PubMed

Schweizer, Tina; Schmitz, Julian; Plempe, Laura; Sun, Dali; Becker-Asano, Christian; Leonhart, Rainer; Tuschen-Caffier, Brunna

2017-01-01

Dysfunctional processing of traumatic events may be in particular related to high trait anxiety as a pre-traumatic risk factor for the development of post-traumatic stress disorder (PTSD). However, as this has rarely been investigated in prospective, experimental studies, we aimed to analyse the association between high trait anxiety and affective as well as cognitive processing of stress using a new prospective Virtual Reality analogue trauma paradigm to overcome limitations of retrospective or current analogue designs. Individuals with high and low trait anxiety (N = 80) were exposed to a multi-sensory Virtual Reality emergency scenario while psychophysiological stress response, emotion regulation and intrusive memories were assessed. Our results showed that high trait anxiety individuals display increased (i) subjective stress responses, (ii) emotion dysregulation and (iii) intrusive memories upon VR analogue trauma exposure. In particular, our sample of high trait anxiety individuals displayed limited access to different emotion regulation strategies as well as increased worry and rumination regarding perceived intrusive memories. Considering the complex interplay of multiple risk factors, our findings suggests that peri-traumatic affective processing seems to mediate high trait anxiety and post-traumatic intrusive memories thereby pointing out the central role of peri-traumatic processes for intrusion development. In addition, HA as a modulating pre-traumatic risk factor might further increase the risk of later dysfunctional processing of an analogue trauma by interacting with factors of affective processing during analogue trauma exposure. Implications of these findings which may contribute to a higher risk to develop PTSD are discussed.

The impact of pre-existing anxiety on affective and cognitive processing of a Virtual Reality analogue trauma

PubMed Central

Schmitz, Julian; Plempe, Laura; Sun, Dali; Becker-Asano, Christian; Leonhart, Rainer; Tuschen-Caffier, Brunna

2017-01-01

Dysfunctional processing of traumatic events may be in particular related to high trait anxiety as a pre-traumatic risk factor for the development of post-traumatic stress disorder (PTSD). However, as this has rarely been investigated in prospective, experimental studies, we aimed to analyse the association between high trait anxiety and affective as well as cognitive processing of stress using a new prospective Virtual Reality analogue trauma paradigm to overcome limitations of retrospective or current analogue designs. Individuals with high and low trait anxiety (N = 80) were exposed to a multi-sensory Virtual Reality emergency scenario while psychophysiological stress response, emotion regulation and intrusive memories were assessed. Our results showed that high trait anxiety individuals display increased (i) subjective stress responses, (ii) emotion dysregulation and (iii) intrusive memories upon VR analogue trauma exposure. In particular, our sample of high trait anxiety individuals displayed limited access to different emotion regulation strategies as well as increased worry and rumination regarding perceived intrusive memories. Considering the complex interplay of multiple risk factors, our findings suggests that peri-traumatic affective processing seems to mediate high trait anxiety and post-traumatic intrusive memories thereby pointing out the central role of peri-traumatic processes for intrusion development. In addition, HA as a modulating pre-traumatic risk factor might further increase the risk of later dysfunctional processing of an analogue trauma by interacting with factors of affective processing during analogue trauma exposure. Implications of these findings which may contribute to a higher risk to develop PTSD are discussed. PMID:29287111

Full Parallel Implementation of an All-Electron Four-Component Dirac-Kohn-Sham Program.

PubMed

Rampino, Sergio; Belpassi, Leonardo; Tarantelli, Francesco; Storchi, Loriano

2014-09-09

A full distributed-memory implementation of the Dirac-Kohn-Sham (DKS) module of the program BERTHA (Belpassi et al., Phys. Chem. Chem. Phys. 2011, 13, 12368-12394) is presented, where the self-consistent field (SCF) procedure is replicated on all the parallel processes, each process working on subsets of the global matrices. The key feature of the implementation is an efficient procedure for switching between two matrix distribution schemes, one (integral-driven) optimal for the parallel computation of the matrix elements and another (block-cyclic) optimal for the parallel linear algebra operations. This approach, making both CPU-time and memory scalable with the number of processors used, virtually overcomes at once both time and memory barriers associated with DKS calculations. Performance, portability, and numerical stability of the code are illustrated on the basis of test calculations on three gold clusters of increasing size, an organometallic compound, and a perovskite model. The calculations are performed on a Beowulf and a BlueGene/Q system.

Scalable and expressive medical terminologies.

PubMed

Mays, E; Weida, R; Dionne, R; Laker, M; White, B; Liang, C; Oles, F J

1996-01-01

The K-Rep system, based on description logic, is used to represent and reason with large and expressive controlled medical terminologies. Expressive concept descriptions incorporate semantically precise definitions composed using logical operators, together with important non-semantic information such as synonyms and codes. Examples are drawn from our experience with K-Rep in modeling the InterMed laboratory terminology and also developing a large clinical terminology now in production use at Kaiser-Permanente. System-level scalability of performance is achieved through an object-oriented database system which efficiently maps persistent memory to virtual memory. Equally important is conceptual scalability-the ability to support collaborative development, organization, and visualization of a substantial terminology as it evolves over time. K-Rep addresses this need by logically completing concept definitions and automatically classifying concepts in a taxonomy via subsumption inferences. The K-Rep system includes a general-purpose GUI environment for terminology development and browsing, a custom interface for formulary term maintenance, a C+2 application program interface, and a distributed client-server mode which provides lightweight clients with efficient run-time access to K-Rep by means of a scripting language.

Cognitive evaluation for the diagnosis of Alzheimer's disease based on Turing Test and Virtual Environments.

PubMed

Fernandez Montenegro, Juan Manuel; Argyriou, Vasileios

2017-05-01

Alzheimer's screening tests are commonly used by doctors to diagnose the patient's condition and stage as early as possible. Most of these tests are based on pen-paper interaction and do not embrace the advantages provided by new technologies. This paper proposes novel Alzheimer's screening tests based on virtual environments and game principles using new immersive technologies combined with advanced Human Computer Interaction (HCI) systems. These new tests are focused on the immersion of the patient in a virtual room, in order to mislead and deceive the patient's mind. In addition, we propose two novel variations of Turing Test proposed by Alan Turing as a method to detect dementia. As a result, four tests are introduced demonstrating the wide range of screening mechanisms that could be designed using virtual environments and game concepts. The proposed tests are focused on the evaluation of memory loss related to common objects, recent conversations and events; the diagnosis of problems in expressing and understanding language; the ability to recognize abnormalities; and to differentiate between virtual worlds and reality, or humans and machines. The proposed screening tests were evaluated and tested using both patients and healthy adults in a comparative study with state-of-the-art Alzheimer's screening tests. The results show the capacity of the new tests to distinguish healthy people from Alzheimer's patients. Copyright © 2017. Published by Elsevier Inc.

Rapid Decision Making on the Fire Ground

DTIC Science & Technology

1988-06-01

Virtually all of the longer decisions are from incidents #30--32, a pumping station fire. This was a unique case in our interviews. First, it took almost...select one. In other words, we found virtually no Instances of the standard laboratory paradigm for decision making: conscious and deliberate...Heidi L. (1985). Eyewitness Memory Enhancement in the Police Interview: Cognitive Retrieval Mnemonics Versus Hypnosis . Journal of Applied Psychology, 70

Technology and Teaching: Searching under Cups for Clues about Memory--An Online Demonstration

ERIC Educational Resources Information Center

Kahan, Todd A.; Mathis, Katherine M.

2007-01-01

An online demonstration, designed to enhance comprehension of Sternberg's (1966) short-term memory scanning task, involved rapidly searching under virtual cups for a ball. We randomly assigned students to 1 of 3 groups, all of whom read the same textbook description of Sternberg's work: A demonstration group used 3 search methods to look for balls…

The effectiveness of artificial intelligent 3-D virtual reality vocational problem-solving training in enhancing employment opportunities for people with traumatic brain injury.

PubMed

Man, David Wai Kwong; Poon, Wai Sang; Lam, Chow

2013-01-01

People with traumatic brain injury (TBI) often experience cognitive deficits in attention, memory, executive functioning and problem-solving. The purpose of the present research study was to examine the effectiveness of an artificial intelligent virtual reality (VR)-based vocational problem-solving skill training programme designed to enhance employment opportunities for people with TBI. This was a prospective randomized controlled trial (RCT) comparing the effectiveness of the above programme with that of the conventional psycho-educational approach. Forty participants with mild (n = 20) or moderate (n = 20) brain injury were randomly assigned to each training programme. Comparisons of problem-solving skills were performed with the Wisconsin Card Sorting Test, the Tower of London Test and the Vocational Cognitive Rating Scale. Improvement in selective memory processes and perception of memory function were found. Across-group comparison showed that the VR group performed more favourably than the therapist-led one in terms of objective and subjective outcome measures and better vocational outcomes. These results support the potential use of a VR-based approach in memory training in people with MCI. Further VR applications, limitations and future research are described.

A lower ratio of omega-6 to omega-3 fatty acids predicts better hippocampus-dependent spatial memory and cognitive status in older adults.

PubMed

Andruchow, Nadia D; Konishi, Kyoko; Shatenstein, Bryna; Bohbot, Véronique D

2017-10-01

Evidence from several cross-sectional studies indicates that an increase in omega-6 to omega-3 fatty acids (FAs) may negatively affect cognition in old age. The hippocampus is among the first neural structures affected by age and atrophy in this brain region is associated with cognitive decline. Therefore, we hypothesized that a lower omega-6:3 FA ratio would predict better hippocampus-dependent spatial memory, and a higher general cognitive status. Fifty-two healthy older adults completed a Food Frequency Questionnaire, the Montreal Cognitive Assessment test (MoCA; a test of global cognition) and virtual navigation tasks that assess navigational strategies and spatial memory. In this cross-sectional study, a lower ratio of omega-6 to omega-3 FA intake strongly predicted more accurate hippocampus-dependent spatial memory and faster learning on our virtual navigation tasks, as well as higher cognitive status overall. These results may help elucidate why certain dietary patterns with a lower omega-6:3 FA ratio, like the Mediterranean diet, are associated with reduced risk of cognitive decline. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Central Ghrelin Resistance Permits the Overconsolidation of Fear Memory.

PubMed

Harmatz, Elia S; Stone, Lauren; Lim, Seh Hong; Lee, Graham; McGrath, Anna; Gisabella, Barbara; Peng, Xiaoyu; Kosoy, Eliza; Yao, Junmei; Liu, Elizabeth; Machado, Nuno J; Weiner, Veronica S; Slocum, Warren; Cunha, Rodrigo A; Goosens, Ki A

2017-06-15

There are many contradictory findings about the role of the hormone ghrelin in aversive processing, with studies suggesting that ghrelin signaling can both inhibit and enhance aversion. Here, we characterize and reconcile the paradoxical role of ghrelin in the acquisition of fearful memories. We used enzyme-linked immunosorbent assay to measure endogenous acyl-ghrelin and corticosterone at time points surrounding auditory fear learning. We used pharmacological (systemic and intra-amygdala) manipulations of ghrelin signaling and examined several aversive and appetitive behaviors. We also used biotin-labeled ghrelin to visualize ghrelin binding sites in coronal brain sections of amygdala. All work was performed in rats. In unstressed rodents, endogenous peripheral acyl-ghrelin robustly inhibits fear memory consolidation through actions in the amygdala and accounts for virtually all interindividual variability in long-term fear memory strength. Higher levels of endogenous ghrelin after fear learning were associated with weaker long-term fear memories, and pharmacological agonism of the ghrelin receptor during the memory consolidation period reduced fear memory strength. These fear-inhibitory effects cannot be explained by changes in appetitive behavior. In contrast, we show that chronic stress, which increases both circulating endogenous acyl-ghrelin and fear memory formation, promotes profound loss of ghrelin binding sites in the amygdala and behavioral insensitivity to ghrelin receptor agonism. These studies provide a new link between stress, a novel type of metabolic resistance, and vulnerability to excessive fear memory formation and reveal that ghrelin can regulate negative emotionality in unstressed animals without altering appetite. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Functional cross‐hemispheric shift between object‐place paired associate memory and spatial memory in the human hippocampus

PubMed Central

Lee, Choong‐Hee; Ryu, Jungwon; Lee, Sang‐Hun; Kim, Hakjin

2016-01-01

ABSTRACT The hippocampus plays critical roles in both object‐based event memory and spatial navigation, but it is largely unknown whether the left and right hippocampi play functionally equivalent roles in these cognitive domains. To examine the hemispheric symmetry of human hippocampal functions, we used an fMRI scanner to measure BOLD activity while subjects performed tasks requiring both object‐based event memory and spatial navigation in a virtual environment. Specifically, the subjects were required to form object‐place paired associate memory after visiting four buildings containing discrete objects in a virtual plus maze. The four buildings were visually identical, and the subjects used distal visual cues (i.e., scenes) to differentiate the buildings. During testing, the subjects were required to identify one of the buildings when cued with a previously associated object, and when shifted to a random place, the subject was expected to navigate to the previously chosen building. We observed that the BOLD activity foci changed from the left hippocampus to the right hippocampus as task demand changed from identifying a previously seen object (object‐cueing period) to searching for its paired‐associate place (object‐cued place recognition period). Furthermore, the efficient retrieval of object‐place paired associate memory (object‐cued place recognition period) was correlated with the BOLD response of the left hippocampus, whereas the efficient retrieval of relatively pure spatial memory (spatial memory period) was correlated with the right hippocampal BOLD response. These findings suggest that the left and right hippocampi in humans might process qualitatively different information for remembering episodic events in space. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc. PMID:27009679

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

PubMed

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

2017-01-01

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

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

PubMed Central

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

2017-01-01

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

Realtime Compositing of Procedural Facade Textures on the Gpu

NASA Astrophysics Data System (ADS)

Krecklau, L.; Kobbelt, L.

2011-09-01

The real time rendering of complex virtual city models has become more important in the last few years for many practical applications like realistic navigation or urban planning. For maximum rendering performance, the complexity of the geometry or textures can be reduced by decreasing the resolution until the data set can fully reside on the memory of the graphics card. This typically results in a low quality of the virtual city model. Alternatively, a streaming algorithm can load the high quality data set from the hard drive. However, this approach requires a large amount of persistent storage providing several gigabytes of static data. We present a system that uses a texture atlas containing atomic tiles like windows, doors or wall patterns, and that combines those elements on-the-fly directly on the graphics card. The presented approach benefits from a sophisticated randomization approach that produces lots of different facades while the grammar description itself remains small. By using a ray casting apporach, we are able to trace through transparent windows revealing procedurally generated rooms which further contributes to the realism of the rendering. The presented method enables real time rendering of city models with a high level of detail for facades while still relying on a small memory footprint.

Hippocampal activation and memory performance in schizophrenia depend on strategy use in a virtual maze.

PubMed

Wilkins, Leanne K; Girard, Todd A; Herdman, Katherine A; Christensen, Bruce K; King, Jelena; Kiang, Michael; Bohbot, Veronique D

2017-10-30

Different strategies may be spontaneously adopted to solve most navigation tasks. These strategies are associated with dissociable brain systems. Here, we use brain-imaging and cognitive tasks to test the hypothesis that individuals living with Schizophrenia Spectrum Disorders (SSD) have selective impairment using a hippocampal-dependent spatial navigation strategy. Brain activation and memory performance were examined using functional magnetic resonance imaging (fMRI) during the 4-on-8 virtual maze (4/8VM) task, a human analog of the rodent radial-arm maze that is amenable to both response-based (egocentric or landmark-based) and spatial (allocentric, cognitive mapping) strategies to remember and navigate to target objects. SSD (schizophrenia and schizoaffective disorder) participants who adopted a spatial strategy performed more poorly on the 4/8VM task and had less hippocampal activation than healthy comparison participants using either strategy as well as SSD participants using a response strategy. This study highlights the importance of strategy use in relation to spatial cognitive functioning in SSD. Consistent with a selective-hippocampal dependent deficit in SSD, these results support the further development of protocols to train impaired hippocampal-dependent abilities or harness non-hippocampal dependent intact abilities. Copyright © 2017 Elsevier B.V. All rights reserved.

Computer Game Play Reduces Intrusive Memories of Experimental Trauma via Reconsolidation-Update Mechanisms.

PubMed

James, Ella L; Bonsall, Michael B; Hoppitt, Laura; Tunbridge, Elizabeth M; Geddes, John R; Milton, Amy L; Holmes, Emily A

2015-08-01

Memory of a traumatic event becomes consolidated within hours. Intrusive memories can then flash back repeatedly into the mind's eye and cause distress. We investigated whether reconsolidation-the process during which memories become malleable when recalled-can be blocked using a cognitive task and whether such an approach can reduce these unbidden intrusions. We predicted that reconsolidation of a reactivated visual memory of experimental trauma could be disrupted by engaging in a visuospatial task that would compete for visual working memory resources. We showed that intrusive memories were virtually abolished by playing the computer game Tetris following a memory-reactivation task 24 hr after initial exposure to experimental trauma. Furthermore, both memory reactivation and playing Tetris were required to reduce subsequent intrusions (Experiment 2), consistent with reconsolidation-update mechanisms. A simple, noninvasive cognitive-task procedure administered after emotional memory has already consolidated (i.e., > 24 hours after exposure to experimental trauma) may prevent the recurrence of intrusive memories of those emotional events. © The Author(s) 2015.

Computer Game Play Reduces Intrusive Memories of Experimental Trauma via Reconsolidation-Update Mechanisms

PubMed Central

James, Ella L.; Bonsall, Michael B.; Hoppitt, Laura; Tunbridge, Elizabeth M.; Geddes, John R.; Milton, Amy L.

2015-01-01

Memory of a traumatic event becomes consolidated within hours. Intrusive memories can then flash back repeatedly into the mind’s eye and cause distress. We investigated whether reconsolidation—the process during which memories become malleable when recalled—can be blocked using a cognitive task and whether such an approach can reduce these unbidden intrusions. We predicted that reconsolidation of a reactivated visual memory of experimental trauma could be disrupted by engaging in a visuospatial task that would compete for visual working memory resources. We showed that intrusive memories were virtually abolished by playing the computer game Tetris following a memory-reactivation task 24 hr after initial exposure to experimental trauma. Furthermore, both memory reactivation and playing Tetris were required to reduce subsequent intrusions (Experiment 2), consistent with reconsolidation-update mechanisms. A simple, noninvasive cognitive-task procedure administered after emotional memory has already consolidated (i.e., > 24 hours after exposure to experimental trauma) may prevent the recurrence of intrusive memories of those emotional events. PMID:26133572

A generalized reconstruction framework for unconventional PET systems

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

Mathews, Aswin John, E-mail: amathews@wustl.edu; Li, Ke; O’Sullivan, Joseph A.

2015-08-15

Purpose: Quantitative estimation of the radionuclide activity concentration in positron emission tomography (PET) requires precise modeling of PET physics. The authors are focused on designing unconventional PET geometries for specific applications. This work reports the creation of a generalized reconstruction framework, capable of reconstructing tomographic PET data for systems that use right cuboidal detector elements positioned at arbitrary geometry using a regular Cartesian grid of image voxels. Methods: The authors report on a variety of design choices and optimization for the creation of the generalized framework. The image reconstruction algorithm is maximum likelihood-expectation–maximization. System geometry can be specified using amore » simple script. Given the geometry, a symmetry seeking algorithm finds existing symmetry in the geometry with respect to the image grid to improve the memory usage/speed. Normalization is approached from a geometry independent perspective. The system matrix is computed using the Siddon’s algorithm and subcrystal approach. The program is parallelized through open multiprocessing and message passing interface libraries. A wide variety of systems can be modeled using the framework. This is made possible by modeling the underlying physics and data correction, while generalizing the geometry dependent features. Results: Application of the framework for three novel PET systems, each designed for a specific application, is presented to demonstrate the robustness of the framework in modeling PET systems of unconventional geometry. Three PET systems of unconventional geometry are studied. (1) Virtual-pinhole half-ring insert integrated into Biograph-40: although the insert device improves image quality over conventional whole-body scanner, the image quality varies depending on the position of the insert and the object. (2) Virtual-pinhole flat-panel insert integrated into Biograph-40: preliminary results from an investigation into a modular flat-panel insert are presented. (3) Plant PET system: a reconfigurable PET system for imaging plants, with resolution of greater than 3.3 mm, is shown. Using the automated symmetry seeking algorithm, the authors achieved a compression ratio of the storage and memory requirement by a factor of approximately 50 for the half-ring and flat-panel systems. For plant PET system, the compression ratio is approximately five. The ratio depends on the level of symmetry that exists in different geometries. Conclusions: This work brings the field closer to arbitrary geometry reconstruction. A generalized reconstruction framework can be used to validate multiple hypotheses and the effort required to investigate each system is reduced. Memory usage/speed can be improved with certain optimizations.« less

A generalized reconstruction framework for unconventional PET systems.

PubMed

Mathews, Aswin John; Li, Ke; Komarov, Sergey; Wang, Qiang; Ravindranath, Bosky; O'Sullivan, Joseph A; Tai, Yuan-Chuan

2015-08-01

Quantitative estimation of the radionuclide activity concentration in positron emission tomography (PET) requires precise modeling of PET physics. The authors are focused on designing unconventional PET geometries for specific applications. This work reports the creation of a generalized reconstruction framework, capable of reconstructing tomographic PET data for systems that use right cuboidal detector elements positioned at arbitrary geometry using a regular Cartesian grid of image voxels. The authors report on a variety of design choices and optimization for the creation of the generalized framework. The image reconstruction algorithm is maximum likelihood-expectation-maximization. System geometry can be specified using a simple script. Given the geometry, a symmetry seeking algorithm finds existing symmetry in the geometry with respect to the image grid to improve the memory usage/speed. Normalization is approached from a geometry independent perspective. The system matrix is computed using the Siddon's algorithm and subcrystal approach. The program is parallelized through open multiprocessing and message passing interface libraries. A wide variety of systems can be modeled using the framework. This is made possible by modeling the underlying physics and data correction, while generalizing the geometry dependent features. Application of the framework for three novel PET systems, each designed for a specific application, is presented to demonstrate the robustness of the framework in modeling PET systems of unconventional geometry. Three PET systems of unconventional geometry are studied. (1) Virtual-pinhole half-ring insert integrated into Biograph-40: although the insert device improves image quality over conventional whole-body scanner, the image quality varies depending on the position of the insert and the object. (2) Virtual-pinhole flat-panel insert integrated into Biograph-40: preliminary results from an investigation into a modular flat-panel insert are presented. (3) Plant PET system: a reconfigurable PET system for imaging plants, with resolution of greater than 3.3 mm, is shown. Using the automated symmetry seeking algorithm, the authors achieved a compression ratio of the storage and memory requirement by a factor of approximately 50 for the half-ring and flat-panel systems. For plant PET system, the compression ratio is approximately five. The ratio depends on the level of symmetry that exists in different geometries. This work brings the field closer to arbitrary geometry reconstruction. A generalized reconstruction framework can be used to validate multiple hypotheses and the effort required to investigate each system is reduced. Memory usage/speed can be improved with certain optimizations.

A generalized reconstruction framework for unconventional PET systems

PubMed Central

Mathews, Aswin John; Li, Ke; Komarov, Sergey; Wang, Qiang; Ravindranath, Bosky; O’Sullivan, Joseph A.; Tai, Yuan-Chuan

2015-01-01

Purpose: Quantitative estimation of the radionuclide activity concentration in positron emission tomography (PET) requires precise modeling of PET physics. The authors are focused on designing unconventional PET geometries for specific applications. This work reports the creation of a generalized reconstruction framework, capable of reconstructing tomographic PET data for systems that use right cuboidal detector elements positioned at arbitrary geometry using a regular Cartesian grid of image voxels. Methods: The authors report on a variety of design choices and optimization for the creation of the generalized framework. The image reconstruction algorithm is maximum likelihood-expectation–maximization. System geometry can be specified using a simple script. Given the geometry, a symmetry seeking algorithm finds existing symmetry in the geometry with respect to the image grid to improve the memory usage/speed. Normalization is approached from a geometry independent perspective. The system matrix is computed using the Siddon’s algorithm and subcrystal approach. The program is parallelized through open multiprocessing and message passing interface libraries. A wide variety of systems can be modeled using the framework. This is made possible by modeling the underlying physics and data correction, while generalizing the geometry dependent features. Results: Application of the framework for three novel PET systems, each designed for a specific application, is presented to demonstrate the robustness of the framework in modeling PET systems of unconventional geometry. Three PET systems of unconventional geometry are studied. (1) Virtual-pinhole half-ring insert integrated into Biograph-40: although the insert device improves image quality over conventional whole-body scanner, the image quality varies depending on the position of the insert and the object. (2) Virtual-pinhole flat-panel insert integrated into Biograph-40: preliminary results from an investigation into a modular flat-panel insert are presented. (3) Plant PET system: a reconfigurable PET system for imaging plants, with resolution of greater than 3.3 mm, is shown. Using the automated symmetry seeking algorithm, the authors achieved a compression ratio of the storage and memory requirement by a factor of approximately 50 for the half-ring and flat-panel systems. For plant PET system, the compression ratio is approximately five. The ratio depends on the level of symmetry that exists in different geometries. Conclusions: This work brings the field closer to arbitrary geometry reconstruction. A generalized reconstruction framework can be used to validate multiple hypotheses and the effort required to investigate each system is reduced. Memory usage/speed can be improved with certain optimizations. PMID:26233187

Hirarchical emotion calculation model for virtual human modellin - biomed 2010.

PubMed

Zhao, Yue; Wright, David

2010-01-01

This paper introduces a new emotion generation method for virtual human modelling. The method includes a novel hierarchical emotion structure, a group of emotion calculation equations and a simple heuristics decision making mechanism, which enables virtual humans to perform emotionally in real-time according to their internal and external factors. Emotion calculation equations used in this research were derived from psychologic emotion measurements. Virtual humans can utilise the information in virtual memory and emotion calculation equations to generate their own numerical emotion states within the hierarchical emotion structure. Those emotion states are important internal references for virtual humans to adopt appropriate behaviours and also key cues for their decision making. A simple heuristics theory is introduced and integrated into decision making process in order to make the virtual humans decision making more like a real human. A data interface which connects the emotion calculation and the decision making structure together has also been designed and simulated to test the method in Virtools environment.

Mixed-handedness advantages in episodic memory obtained under conditions of intentional learning extend to incidental learning.

PubMed

Christman, Stephen D; Butler, Michael

2011-10-01

The existence of handedness differences in the retrieval of episodic memories is well-documented, but virtually all have been obtained under conditions of intentional learning. Two experiments are reported that extend the presence of such handedness differences to memory retrieval under conditions of incidental learning. Experiment 1 used Craik and Tulving's (1975) classic levels-of-processing paradigm and obtained handedness differences under incidental and intentional conditions of deep processing, but not under conditions of shallow incidental processing. Experiment 2 looked at incidental memory for distracter items from a recognition memory task and again found a mixed-handed advantage. Results are discussed in terms of the relation between interhemispheric interaction, levels of processing, and episodic memory retrieval. Copyright © 2011 Elsevier Inc. All rights reserved.

Arctic Boreal Vulnerability Experiment (ABoVE) Science Cloud

NASA Astrophysics Data System (ADS)

Duffy, D.; Schnase, J. L.; McInerney, M.; Webster, W. P.; Sinno, S.; Thompson, J. H.; Griffith, P. C.; Hoy, E.; Carroll, M.

2014-12-01

The effects of climate change are being revealed at alarming rates in the Arctic and Boreal regions of the planet. NASA's Terrestrial Ecology Program has launched a major field campaign to study these effects over the next 5 to 8 years. The Arctic Boreal Vulnerability Experiment (ABoVE) will challenge scientists to take measurements in the field, study remote observations, and even run models to better understand the impacts of a rapidly changing climate for areas of Alaska and western Canada. The NASA Center for Climate Simulation (NCCS) at the Goddard Space Flight Center (GSFC) has partnered with the Terrestrial Ecology Program to create a science cloud designed for this field campaign - the ABoVE Science Cloud. The cloud combines traditional high performance computing with emerging technologies to create an environment specifically designed for large-scale climate analytics. The ABoVE Science Cloud utilizes (1) virtualized high-speed InfiniBand networks, (2) a combination of high-performance file systems and object storage, and (3) virtual system environments tailored for data intensive, science applications. At the center of the architecture is a large object storage environment, much like a traditional high-performance file system, that supports data proximal processing using technologies like MapReduce on a Hadoop Distributed File System (HDFS). Surrounding the storage is a cloud of high performance compute resources with many processing cores and large memory coupled to the storage through an InfiniBand network. Virtual systems can be tailored to a specific scientist and provisioned on the compute resources with extremely high-speed network connectivity to the storage and to other virtual systems. In this talk, we will present the architectural components of the science cloud and examples of how it is being used to meet the needs of the ABoVE campaign. In our experience, the science cloud approach significantly lowers the barriers and risks to organizations that require high performance computing solutions and provides the NCCS with the agility required to meet our customers' rapidly increasing and evolving requirements.

Implementation of a Landscape Lighting System to Display Images

NASA Astrophysics Data System (ADS)

Sun, Gi-Ju; Cho, Sung-Jae; Kim, Chang-Beom; Moon, Cheol-Hong

The system implemented in this study consists of a PC, MASTER, SLAVEs and MODULEs. The PC sets the various landscape lighting displays, and the image files can be sent to the MASTER through a virtual serial port connected to the USB (Universal Serial Bus). The MASTER sends a sync signal to the SLAVE. The SLAVE uses the signal received from the MASTER and the landscape lighting display pattern. The video file is saved in the NAND Flash memory and the R, G, B signals are separated using the self-made display signal and sent to the MODULE so that it can display the image.

Implementing Goal-Directed Foraging Decisions of a Simpler Nervous System in Simulation

PubMed Central

Brown, Jeffrey W.; Caetano-Anollés, Derek; Catanho, Marianne; Gribkova, Ekaterina; Ryckman, Nathaniel; Tian, Kun; Voloshin, Mikhail

2018-01-01

Economic decisions arise from evaluation of alternative actions in contexts of motivation and memory. In the predatory sea-slug Pleurobranchaea the economic decisions of foraging are found to occur by the workings of a simple, affectively controlled homeostat with learning abilities. Here, the neuronal circuit relations for approach-avoidance choice of Pleurobranchaea are expressed and tested in the foraging simulation Cyberslug. Choice is organized around appetitive state as a moment-to-moment integration of sensation, motivation (satiation/hunger), and memory. Appetitive state controls a switch for approach vs. avoidance turn responses to sensation. Sensory stimuli are separately integrated for incentive value into appetitive state, and for prey location (stimulus place) into mapping motor response. Learning interacts with satiation to regulate prey choice affectively. The virtual predator realistically reproduces the decisions of the real one in varying circumstances and satisfies optimal foraging criteria. The basic relations are open to experimental embellishment toward enhanced neural and behavioral complexity in simulation, as was the ancestral bilaterian nervous system in evolution. PMID:29503862

AIRNET: A real-time comunications network for aircraft

NASA Technical Reports Server (NTRS)

Weaver, Alfred C.; Cain, Brendan G.; Colvin, M. Alexander; Simoncic, Robert

1990-01-01

A real-time local area network was developed for use on aircraft and space vehicles. It uses token ring technology to provide high throughput, low latency, and high reliability. The system was implemented on PCs and PC/ATs operating on PCbus, and on Intel 8086/186/286/386s operating on Multibus. A standard IEEE 802.2 logical link control interface was provided to (optional) upper layer software; this permits the controls designer to utilize standard communications protocols (e.g., ISO, TCP/IP) if time permits, or to utilize a very fast link level protocol directly if speed is critical. Both unacknowledged datagram and reliable virtual circuit services are supported. A station operating an 8 MHz Intel 286 as a host can generate a sustained load of 1.8 megabits per second per station, and a 100-byte message can be delivered from the transmitter's user memory to the receiver's user memory, including all operating system and network overhead, in under 4 milliseconds.

Closed-Loop Targeted Memory Reactivation during Sleep Improves Spatial Navigation.

PubMed

Shimizu, Renee E; Connolly, Patrick M; Cellini, Nicola; Armstrong, Diana M; Hernandez, Lexus T; Estrada, Rolando; Aguilar, Mario; Weisend, Michael P; Mednick, Sara C; Simons, Stephen B

2018-01-01

Sounds associated with newly learned information that are replayed during non-rapid eye movement (NREM) sleep can improve recall in simple tasks. The mechanism for this improvement is presumed to be reactivation of the newly learned memory during sleep when consolidation takes place. We have developed an EEG-based closed-loop system to precisely deliver sensory stimulation at the time of down-state to up-state transitions during NREM sleep. Here, we demonstrate that applying this technology to participants performing a realistic navigation task in virtual reality results in a significant improvement in navigation efficiency after sleep that is accompanied by increases in the spectral power especially in the fast (12-15 Hz) sleep spindle band. Our results show promise for the application of sleep-based interventions to drive improvement in real-world tasks.

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.

Virtual reality measures in neuropsychological assessment: a meta-analytic review.

PubMed

Neguț, Alexandra; Matu, Silviu-Andrei; Sava, Florin Alin; David, Daniel

2016-02-01

Virtual reality-based assessment is a new paradigm for neuropsychological evaluation, that might provide an ecological assessment, compared to paper-and-pencil or computerized neuropsychological assessment. Previous research has focused on the use of virtual reality in neuropsychological assessment, but no meta-analysis focused on the sensitivity of virtual reality-based measures of cognitive processes in measuring cognitive processes in various populations. We found eighteen studies that compared the cognitive performance between clinical and healthy controls on virtual reality measures. Based on a random effects model, the results indicated a large effect size in favor of healthy controls (g = .95). For executive functions, memory and visuospatial analysis, subgroup analysis revealed moderate to large effect sizes, with superior performance in the case of healthy controls. Participants' mean age, type of clinical condition, type of exploration within virtual reality environments, and the presence of distractors were significant moderators. Our findings support the sensitivity of virtual reality-based measures in detecting cognitive impairment. They highlight the possibility of using virtual reality measures for neuropsychological assessment in research applications, as well as in clinical practice.

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 functions. The sensor data is processed in a distributed fashion across the network, providing a large pool of resources in real time to meet stringent latency requirements.

Ariane 5-ALF: Evolution of the Ariane 5 Data Handling System

NASA Astrophysics Data System (ADS)

Notebaert, O.; Stransky, Arnaud; Corin, Hans; Hult, Torbjorn; Bonnerot, Georges-Albert

2004-06-01

In the coming years, the Ariane 5 On-Board-Computer (OBC) will handle missions and performances enhancements together with the need for significantly reducing costs and the replacement of obsolescent components. The OBC evolution is naturally driven by these factors, but also needs to consider the SW system compliance. Indeed, it would be a major concern that the necessary change of the underlying HW should imply new development of the flight software, mission database and ground control system.The Ariane 5 SW uses ADA language, which enables verifiable definition of the interfaces and provides a standardized level of the real-time behavior. To enforce portability, it has a layered architecture that clearly separates application SW and data from the lower level software. In addition, the on-board mission data is managed thanks to the extraction of an image of the systems database located in a structured memory area (the exchange memory). Used for all interchanges between the system application software and the launcher's subsystems and peripherals, the exchange memory is the virtual view of the Ariane 5 system from the flight SW standpoint. Thanks to these early architectural and structural choices, portability on future hardware is theoretically guaranteed, whenever the exchange memory data structures and the service layer interfaces remains stable. The ALF working group has defined and manufactured a mock-up that fulfils these architectural constraints with a completely new on-board computer featuring improvements such as the microprocessor replacement as well as an advanced integrated I/O controller for access to the system data bus. Lower level SW has been prototyped on this new hardware in order to fulfill the same level of services as the current one while completely hiding the underlying HW/SW implementation to the rest of the system. Functional and performance evaluation of this platform consolidated at system level will show the potential benefits and the limits of such approach.

Acute effects of exergames on cognitive function of institutionalized older persons: a single-blinded, randomized and controlled pilot study.

PubMed

Monteiro-Junior, Renato Sobral; da Silva Figueiredo, Luiz Felipe; Maciel-Pinheiro, Paulo de Tarso; Abud, Erick Lohan Rodrigues; Braga, Ana Elisa Mendes Montalvão; Barca, Maria Lage; Engedal, Knut; Nascimento, Osvaldo José M; Deslandes, Andrea Camaz; Laks, Jerson

2017-06-01

Improvements on balance, gait and cognition are some of the benefits of exergames. Few studies have investigated the cognitive effects of exergames in institutionalized older persons. To assess the acute effect of a single session of exergames on cognition of institutionalized older persons. Nineteen institutionalized older persons were randomly allocated to Wii (WG, n = 10, 86 ± 7 year, two males) or control groups (CG, n = 9, 86 ± 5 year, one male). The WG performed six exercises with virtual reality, whereas CG performed six exercises without virtual reality. Verbal fluency test (VFT), digit span forward and digit span backward were used to evaluate semantic memory/executive function, short-term memory and work memory, respectively, before and after exergames and Δ post- to pre-session (absolute) and Δ % (relative) were calculated. Parametric (t independent test) and nonparametric (Mann-Whitney test) statistics and effect size were applied to tests for efficacy. VFT was statistically significant within WG (-3.07, df = 9, p = 0.013). We found no statistically significant differences between the two groups (p > 0.05). Effect size between groups of Δ % (median = 21 %) showed moderate effect for WG (0.63). Our data show moderate improvement of semantic memory/executive function due to exergames session. It is possible that cognitive brain areas are activated during exergames, increasing clinical response. A single session of exergames showed no significant improvement in short-term memory, working memory and semantic memory/executive function. The effect size for verbal fluency was promising, and future studies on this issue should be developed. RBR-6rytw2.

Functional magnetic resonance imaging study of external source memory and its relation to cognitive insight in non-clinical subjects.

PubMed

Buchy, Lisa; Hawco, Colin; Bodnar, Michael; Izadi, Sarah; Dell'Elce, Jennifer; Messina, Katrina; Lepage, Martin

2014-09-01

Previous research has linked cognitive insight (a measure of self-reflectiveness and self-certainty) in psychosis with neurocognitive and neuroanatomical disturbances in the fronto-hippocampal neural network. The authors' goal was to use functional magnetic resonance imaging (fMRI) to investigate the neural correlates of cognitive insight during an external source memory paradigm in non-clinical subjects. At encoding, 24 non-clinical subjects travelled through a virtual city where they came across 20 separate people, each paired with a unique object in a distinct location. fMRI data were then acquired while participants viewed images of the city, and completed source recognition memory judgments of where and with whom objects were seen, which is known to involve prefrontal cortex. Cognitive insight was assessed with the Beck Cognitive Insight Scale. External source memory was associated with neural activity in a widespread network consisting of frontal cortex, including ventrolateral prefrontal cortex (VLPFC), temporal and occipital cortices. Activation in VLPFC correlated with higher self-reflectiveness and activation in midbrain correlated with lower self-certainty during source memory attributions. Neither self-reflectiveness nor self-certainty significantly correlated with source memory accuracy. By means of virtual reality and in the context of an external source memory paradigm, the study identified a preliminary functional neural basis for cognitive insight in the VLPFC in healthy people that accords with our fronto-hippocampal theoretical model as well as recent neuroimaging data in people with psychosis. The results may facilitate the understanding of the role of neural mechanisms in psychotic disorders associated with cognitive insight distortions. © 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.

Short-term memory, executive control, and children's route learning.

PubMed

Purser, Harry R M; Farran, Emily K; Courbois, Yannick; Lemahieu, Axelle; Mellier, Daniel; Sockeel, Pascal; Blades, Mark

2012-10-01

The aim of this study was to investigate route-learning ability in 67 children aged 5 to 11years and to relate route-learning performance to the components of Baddeley's model of working memory. Children carried out tasks that included measures of verbal and visuospatial short-term memory and executive control and also measures of verbal and visuospatial long-term memory; the route-learning task was conducted using a maze in a virtual environment. In contrast to previous research, correlations were found between both visuospatial and verbal memory tasks-the Corsi task, short-term pattern span, digit span, and visuospatial long-term memory-and route-learning performance. However, further analyses indicated that these relationships were mediated by executive control demands that were common to the tasks, with long-term memory explaining additional unique variance in route learning. Copyright © 2012 Elsevier Inc. All rights reserved.

A space for mothers: grief as identity construction on memorial websites created by SIDS parents.

PubMed

Finlay, Christopher J; Krueger, Guenther

2011-01-01

In this article we conduct a textual analysis of memorial websites created by mothers who have experienced a loss due to sudden infant death syndrome (SIDS). Using an online Internet ethnographic approach, we reviewed a series of 20 sites in an attempt to analyze the motivations of the site creators as manifested in their online projects. We spent time on the sites, moving through all facets of them, following links, and experiencing them the way a visitor would encounter them. In this virtual exploration we uncovered personal narratives, community building, religious imagery, and numerous examples of social networking. We also analyzed guest books in order to understand who visits these sites and their reasons for doing so. We conclude that development of these sites are a process that helps some mothers in their grief and gives them a focus and activity that is helpful and perhaps healing. More importantly perhaps is the potential for community building and networking that this type of activity allows. As an extension of a real-world memorial such as a gravesite, a virtual mourning space provides more in the way of these types of communications. Our work suggests that memorial websites constructed by SIDS parents help in meaning and identity reconstruction after loss.

An On-Chip Learning Neuromorphic Autoencoder With Current-Mode Transposable Memory Read and Virtual Lookup Table.

PubMed

Cho, Hwasuk; Son, Hyunwoo; Seong, Kihwan; Kim, Byungsub; Park, Hong-June; Sim, Jae-Yoon

2018-02-01

This paper presents an IC implementation of on-chip learning neuromorphic autoencoder unit in a form of rate-based spiking neural network. With a current-mode signaling scheme embedded in a 500 × 500 6b SRAM-based memory, the proposed architecture achieves simultaneous processing of multiplications and accumulations. In addition, a transposable memory read for both forward and backward propagations and a virtual lookup table are also proposed to perform an unsupervised learning of restricted Boltzmann machine. The IC is fabricated using 28-nm CMOS process and is verified in a three-layer network of encoder-decoder pair for training and recovery of images with two-dimensional pixels. With a dataset of 50 digits, the IC shows a normalized root mean square error of 0.078. Measured energy efficiencies are 4.46 pJ per synaptic operation for inference and 19.26 pJ per synaptic weight update for learning, respectively. The learning performance is also estimated by simulations if the proposed hardware architecture is extended to apply to a batch training of 60 000 MNIST datasets.

Walking through doorways causes forgetting: Further explorations.

PubMed

Radvansky, Gabriel A; Krawietz, Sabine A; Tamplin, Andrea K

2011-08-01

Previous research using virtual environments has revealed a location-updating effect in which there is a decline in memory when people move from one location to another. Here we assess whether this effect reflects the influence of the experienced context, in terms of the degree of immersion of a person in an environment, as suggested by some work in spatial cognition, or by a shift in context. In Experiment 1, the degree of immersion was reduced by using smaller displays. In comparison, in Experiment 2 an actual, rather than a virtual, environment was used, to maximize immersion. Location-updating effects were observed under both of these conditions. In Experiment 3, the original encoding context was reinstated by having a person return to the original room in which objects were first encoded. However, inconsistent with an encoding specificity account, memory did not improve by reinstating this context. Finally, we did a further analysis of the results of this and previous experiments to assess the differential influence of foregrounding and retrieval interference. Overall, these data are interpreted in terms of the event horizon model of event cognition and memory.

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

NASA Astrophysics Data System (ADS)

Lokka, I.; Çöltekin, A.

2016-06-01

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

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.

A 3D character animation engine for multimodal interaction on mobile devices

NASA Astrophysics Data System (ADS)

Sandali, Enrico; Lavagetto, Fabio; Pisano, Paolo

2005-03-01

Talking virtual characters are graphical simulations of real or imaginary persons that enable natural and pleasant multimodal interaction with the user, by means of voice, eye gaze, facial expression and gestures. This paper presents an implementation of a 3D virtual character animation and rendering engine, compliant with the MPEG-4 standard, running on Symbian-based SmartPhones. Real-time animation of virtual characters on mobile devices represents a challenging task, since many limitations must be taken into account with respect to processing power, graphics capabilities, disk space and execution memory size. The proposed optimization techniques allow to overcome these issues, guaranteeing a smooth and synchronous animation of facial expressions and lip movements on mobile phones such as Sony-Ericsson's P800 and Nokia's 6600. The animation engine is specifically targeted to the development of new "Over The Air" services, based on embodied conversational agents, with applications in entertainment (interactive story tellers), navigation aid (virtual guides to web sites and mobile services), news casting (virtual newscasters) and education (interactive virtual teachers).

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

Improving Dental Experiences by Using Virtual Reality Distraction: A Simulation Study

PubMed Central

Tanja-Dijkstra, Karin; Pahl, Sabine; P. White, Mathew; Andrade, Jackie; Qian, Cheng; Bruce, Malcolm; May, Jon; Moles, David R.

2014-01-01

Dental anxiety creates significant problems for both patients and the dental profession. Some distraction interventions are already used by healthcare professionals to help patients cope with unpleasant procedures. The present study is novel because it a) builds on evidence that natural scenery is beneficial for patients, and b) uses a Virtual Reality (VR) representation of nature to distract participants. Extending previous work that has investigated pain and anxiety during treatment, c) we also consider the longer term effects in terms of more positive memories of the treatment, building on a cognitive theory of memory (Elaborated Intrusions). Participants (n = 69) took part in a simulated dental experience and were randomly assigned to one of three VR conditions (active vs. passive vs. control). In addition, participants were distinguished into high and low dentally anxious according to a median split resulting in a 3×2 between-subjects design. VR distraction in a simulated dental context affected memories a week later. The VR distraction had effects not only on concurrent experiences, such as perceived control, but longitudinally upon the vividness of memories after the dental experience had ended. Participants with higher dental anxiety (for whom the dental procedures were presumably more aversive) showed a greater reduction in memory vividness than lower dental-anxiety participants. This study thus suggests that VR distractions can be considered as a relevant intervention for cycles of care in which people’s previous experiences affect their behaviour for future events. PMID:24621518

Improving dental experiences by using virtual reality distraction: a simulation study.

PubMed

Tanja-Dijkstra, Karin; Pahl, Sabine; White, Mathew P; Andrade, Jackie; Qian, Cheng; Bruce, Malcolm; May, Jon; Moles, David R

2014-01-01

Dental anxiety creates significant problems for both patients and the dental profession. Some distraction interventions are already used by healthcare professionals to help patients cope with unpleasant procedures. The present study is novel because it a) builds on evidence that natural scenery is beneficial for patients, and b) uses a Virtual Reality (VR) representation of nature to distract participants. Extending previous work that has investigated pain and anxiety during treatment, c) we also consider the longer term effects in terms of more positive memories of the treatment, building on a cognitive theory of memory (Elaborated Intrusions). Participants (n = 69) took part in a simulated dental experience and were randomly assigned to one of three VR conditions (active vs. passive vs. control). In addition, participants were distinguished into high and low dentally anxious according to a median split resulting in a 3×2 between-subjects design. VR distraction in a simulated dental context affected memories a week later. The VR distraction had effects not only on concurrent experiences, such as perceived control, but longitudinally upon the vividness of memories after the dental experience had ended. Participants with higher dental anxiety (for whom the dental procedures were presumably more aversive) showed a greater reduction in memory vividness than lower dental-anxiety participants. This study thus suggests that VR distractions can be considered as a relevant intervention for cycles of care in which people's previous experiences affect their behaviour for future events.

An assessment of prospective memory retrieval in women with chronic fatigue syndrome using a virtual-reality environment: an initial study.

PubMed

Attree, Elizabeth A; Dancey, Christine P; Pope, Alison L

2009-08-01

People with chronic fatigue syndrome (CFS) have increased rates of depression, anxiety, and illness intrusiveness; they may also suffer from cognitive problems such as retrospective memory (RM) deficits and concentration difficulties that can stem from diminished information-processing capability. We predicted that this diminished capacity may also lead to deficits in other cognitive functions, such as prospective memory (ProM). Event-, time-, and activity-based ProM was assessed in 11 women with CFS and 12 healthy women using a computer-generated virtual environment (VE). RM was assessed using a free-recall test, and subjective assessment of both ProM and RM was assessed by questionnaire. Groups were equivalent in age and measures of IQ. People with CFS performed slightly worse than healthy controls on both the event- and time-based ProM measures, although these were not statistically significant. However, the CFS group performed significantly worse than the healthy controls on both the free recall-task and on subjective assessment of both RM and ProM. Women with CFS do have some subtle decrements in memory, particularly RM. However, it is possible that the decrements found in the present sample would be greater in real life. Further studies utilizing both healthy controls and illness controls are now needed to ascertain how sensitive the VE measure is and to inform the development of tasks in the VE that place progressively increasing demands on working memory capacity.

Enrichment of Human-Computer Interaction in Brain-Computer Interfaces via Virtual Environments

PubMed Central

Víctor Rodrigo, Mercado-García

2017-01-01

Tridimensional representations stimulate cognitive processes that are the core and foundation of human-computer interaction (HCI). Those cognitive processes take place while a user navigates and explores a virtual environment (VE) and are mainly related to spatial memory storage, attention, and perception. VEs have many distinctive features (e.g., involvement, immersion, and presence) that can significantly improve HCI in highly demanding and interactive systems such as brain-computer interfaces (BCI). BCI is as a nonmuscular communication channel that attempts to reestablish the interaction between an individual and his/her environment. Although BCI research started in the sixties, this technology is not efficient or reliable yet for everyone at any time. Over the past few years, researchers have argued that main BCI flaws could be associated with HCI issues. The evidence presented thus far shows that VEs can (1) set out working environmental conditions, (2) maximize the efficiency of BCI control panels, (3) implement navigation systems based not only on user intentions but also on user emotions, and (4) regulate user mental state to increase the differentiation between control and noncontrol modalities. PMID:29317861

Modeling the Virtual Machine Launching Overhead under Fermicloud

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

Garzoglio, Gabriele; Wu, Hao; Ren, Shangping

FermiCloud is a private cloud developed by the Fermi National Accelerator Laboratory for scientific workflows. The Cloud Bursting module of the FermiCloud enables the FermiCloud, when more computational resources are needed, to automatically launch virtual machines to available resources such as public clouds. One of the main challenges in developing the cloud bursting module is to decide when and where to launch a VM so that all resources are most effectively and efficiently utilized and the system performance is optimized. However, based on FermiCloud’s system operational data, the VM launching overhead is not a constant. It varies with physical resourcemore » (CPU, memory, I/O device) utilization at the time when a VM is launched. Hence, to make judicious decisions as to when and where a VM should be launched, a VM launch overhead reference model is needed. The paper is to develop a VM launch overhead reference model based on operational data we have obtained on FermiCloud and uses the reference model to guide the cloud bursting process.« less

Systemic Lisbon Battery: Normative Data for Memory and Attention Assessments.

PubMed

Gamito, Pedro; Morais, Diogo; Oliveira, Jorge; Ferreira Lopes, Paulo; Picareli, Luís Felipe; Matias, Marcelo; Correia, Sara; Brito, Rodrigo

2016-05-04

Memory and attention are two cognitive domains pivotal for the performance of instrumental activities of daily living (IADLs). The assessment of these functions is still widely carried out with pencil-and-paper tests, which lack ecological validity. The evaluation of cognitive and memory functions while the patients are performing IADLs should contribute to the ecological validity of the evaluation process. The objective of this study is to establish normative data from virtual reality (VR) IADLs designed to activate memory and attention functions. A total of 243 non-clinical participants carried out a paper-and-pencil Mini-Mental State Examination (MMSE) and performed 3 VR activities: art gallery visual matching task, supermarket shopping task, and memory fruit matching game. The data (execution time and errors, and money spent in the case of the supermarket activity) was automatically generated from the app. Outcomes were computed using non-parametric statistics, due to non-normality of distributions. Age, academic qualifications, and computer experience all had significant effects on most measures. Normative values for different levels of these measures were defined. Age, academic qualifications, and computer experience should be taken into account while using our VR-based platform for cognitive assessment purposes. ©Pedro Gamito, Diogo Morais, Jorge Oliveira, Paulo Ferreira Lopes, Luís Felipe Picareli, Marcelo Matias, Sara Correia, Rodrigo Brito. Originally published in JMIR Rehabilitation and Assistive Technology (http://rehab.jmir.org), 04.05.2016.

Comprehension and Memory of Spatial and Temporal Event Components

DTIC Science & Technology

2008-01-01

sitting in the leather chair listening to some music . [PROBE LAMP (filler)] He had headphones on, but Mary Agnes could still make out the lyrics. She...representation and processing of virtual spaces results in performance that is essentially identical to real spaces (e.g., Sun, Chan, & Campos , 2004) or with...that people treat virtual spaces in a manner very similar to real spaces (e.g., Sun, Chan, & Campos , 2004; Waller, Loomis, & Haun, 2004). The aim of

Neurocognitive systems related to real-world prospective memory.

PubMed

Kalpouzos, Grégoria; Eriksson, Johan; Sjölie, Daniel; Molin, Jonas; Nyberg, Lars

2010-10-08

Prospective memory (PM) denotes the ability to remember to perform actions in the future. It has been argued that standard laboratory paradigms fail to capture core aspects of PM. We combined functional MRI, virtual reality, eye-tracking and verbal reports to explore the dynamic allocation of neurocognitive processes during a naturalistic PM task where individuals performed errands in a realistic model of their residential town. Based on eye movement data and verbal reports, we modeled PM as an iterative loop of five sustained and transient phases: intention maintenance before target detection (TD), TD, intention maintenance after TD, action, and switching, the latter representing the activation of a new intention in mind. The fMRI analyses revealed continuous engagement of a top-down fronto-parietal network throughout the entire task, likely subserving goal maintenance in mind. In addition, a shift was observed from a perceptual (occipital) system while searching for places to go, to a mnemonic (temporo-parietal, fronto-hippocampal) system for remembering what actions to perform after TD. Updating of the top-down fronto-parietal network occurred at both TD and switching, the latter likely also being characterized by frontopolar activity. Taken together, these findings show how brain systems complementary interact during real-world PM, and support a more complete model of PM that can be applied to naturalistic PM tasks and that we named PROspective MEmory DYnamic (PROMEDY) model because of its dynamics on both multi-phase iteration and the interactions of distinct neurocognitive networks.

Dynamic Allocation of SPM Based on Time-Slotted Cache Conflict Graph for System Optimization

NASA Astrophysics Data System (ADS)

Wu, Jianping; Ling, Ming; Zhang, Yang; Mei, Chen; Wang, Huan

This paper proposes a novel dynamic Scratch-pad Memory allocation strategy to optimize the energy consumption of the memory sub-system. Firstly, the whole program execution process is sliced into several time slots according to the temporal dimension; thereafter, a Time-Slotted Cache Conflict Graph (TSCCG) is introduced to model the behavior of Data Cache (D-Cache) conflicts within each time slot. Then, Integer Nonlinear Programming (INP) is implemented, which can avoid time-consuming linearization process, to select the most profitable data pages. Virtual Memory System (VMS) is adopted to remap those data pages, which will cause severe Cache conflicts within a time slot, to SPM. In order to minimize the swapping overhead of dynamic SPM allocation, a novel SPM controller with a tightly coupled DMA is introduced to issue the swapping operations without CPU's intervention. Last but not the least, this paper discusses the fluctuation of system energy profit based on different MMU page size as well as the Time Slot duration quantitatively. According to our design space exploration, the proposed method can optimize all of the data segments, including global data, heap and stack data in general, and reduce the total energy consumption by 27.28% on average, up to 55.22% with a marginal performance promotion. And comparing to the conventional static CCG (Cache Conflicts Graph), our approach can obtain 24.7% energy profit on average, up to 30.5% with a sight boost in performance.

Gilgamesh: A Multithreaded Processor-In-Memory Architecture for Petaflops Computing

NASA Technical Reports Server (NTRS)

Sterling, T. L.; Zima, H. P.

2002-01-01

Processor-in-Memory (PIM) architectures avoid the von Neumann bottleneck in conventional machines by integrating high-density DRAM and CMOS logic on the same chip. Parallel systems based on this new technology are expected to provide higher scalability, adaptability, robustness, fault tolerance and lower power consumption than current MPPs or commodity clusters. In this paper we describe the design of Gilgamesh, a PIM-based massively parallel architecture, and elements of its execution model. Gilgamesh extends existing PIM capabilities by incorporating advanced mechanisms for virtualizing tasks and data and providing adaptive resource management for load balancing and latency tolerance. The Gilgamesh execution model is based on macroservers, a middleware layer which supports object-based runtime management of data and threads allowing explicit and dynamic control of locality and load balancing. The paper concludes with a discussion of related research activities and an outlook to future work.

Resting-State fMRI Activity Predicts Unsupervised Learning and Memory in an Immersive Virtual Reality Environment

PubMed Central

Wong, Chi Wah; Olafsson, Valur; Plank, Markus; Snider, Joseph; Halgren, Eric; Poizner, Howard; Liu, Thomas T.

2014-01-01

In the real world, learning often proceeds in an unsupervised manner without explicit instructions or feedback. In this study, we employed an experimental paradigm in which subjects explored an immersive virtual reality environment on each of two days. On day 1, subjects implicitly learned the location of 39 objects in an unsupervised fashion. On day 2, the locations of some of the objects were changed, and object location recall performance was assessed and found to vary across subjects. As prior work had shown that functional magnetic resonance imaging (fMRI) measures of resting-state brain activity can predict various measures of brain performance across individuals, we examined whether resting-state fMRI measures could be used to predict object location recall performance. We found a significant correlation between performance and the variability of the resting-state fMRI signal in the basal ganglia, hippocampus, amygdala, thalamus, insula, and regions in the frontal and temporal lobes, regions important for spatial exploration, learning, memory, and decision making. In addition, performance was significantly correlated with resting-state fMRI connectivity between the left caudate and the right fusiform gyrus, lateral occipital complex, and superior temporal gyrus. Given the basal ganglia's role in exploration, these findings suggest that tighter integration of the brain systems responsible for exploration and visuospatial processing may be critical for learning in a complex environment. PMID:25286145

Software Mechanisms for Multiprocessor TLB Consistency

DTIC Science & Technology

1989-12-01

thanks. Raj V aswani implemented the DASH message-passing system. Ramesh Govindan implemented part of the DASH virtual memory system. G . Scott...1 Latency (ma) 5𔃺 ---·-r··-·r···r··-T·-·-r··-·r····r····-r··-·r··- . g ~~~R=r 18 -----1·--·-r··-T·----1·--··r·---1·----1·--··r·---T·----1 16...model development. Synchronizing TLBs is similar to updating replicated data in a distributed environment. Lee and Garcia-Molina both used an M/ G /1

Future Development of Dense Ferroelectric Memories for Space Applications

NASA Technical Reports Server (NTRS)

Philpy, Stephen C.; Derbenwick, Gary F.

2001-01-01

The availability of high density, radiation tolerant, nonvolatile memories is critical for space applications. Ferroelectric memories, when fabricated with radiation hardened complementary metal oxide semiconductors (CMOS), can be manufactured and packaged to provide high density replacements for Flash memory, which is not radiation tolerant. Previous work showed ferroelectric memory cells to be resistant to single event upsets and proton irradiation, and ferroelectric storage capacitors to be resistant to neutron exposure. In addition to radiation hardness, the fast programming times, virtually unlimited endurance, and low voltage, low power operation make ferroelectric memories ideal for space missions. Previously, a commercial double level metal 64-kilobit ferroelectric memory was presented. Although the capabilities of radiation hardened wafer fabrication facilities lag behind those of the most modern commercial wafer fabrication facilities, several paths to achieving radiation tolerant, dense ferroelectric memories are emerging. Both short and long term solutions are presented in this paper. Although worldwide major semiconductor companies are introducing commercial ferroelectric memories, funding limitations must be overcome to proceed with the development of high density, radiation tolerant ferroelectric memories.

Parallel computing for probabilistic fatigue analysis

NASA Technical Reports Server (NTRS)

Sues, Robert H.; Lua, Yuan J.; Smith, Mark D.

1993-01-01

This paper presents the results of Phase I research to investigate the most effective parallel processing software strategies and hardware configurations for probabilistic structural analysis. We investigate the efficiency of both shared and distributed-memory architectures via a probabilistic fatigue life analysis problem. We also present a parallel programming approach, the virtual shared-memory paradigm, that is applicable across both types of hardware. Using this approach, problems can be solved on a variety of parallel configurations, including networks of single or multiprocessor workstations. We conclude that it is possible to effectively parallelize probabilistic fatigue analysis codes; however, special strategies will be needed to achieve large-scale parallelism to keep large number of processors busy and to treat problems with the large memory requirements encountered in practice. We also conclude that distributed-memory architecture is preferable to shared-memory for achieving large scale parallelism; however, in the future, the currently emerging hybrid-memory architectures will likely be optimal.

Study of the modifications needed for efficient operation of NASTRAN on the Control Data Corporation STAR-100 computer

NASA Technical Reports Server (NTRS)

1975-01-01

NASA structural analysis (NASTRAN) computer program is operational on three series of third generation computers. The problem and difficulties involved in adapting NASTRAN to a fourth generation computer, namely, the Control Data STAR-100, are discussed. The salient features which distinguish Control Data STAR-100 from third generation computers are hardware vector processing capability and virtual memory. A feasible method is presented for transferring NASTRAN to Control Data STAR-100 system while retaining much of the machine-independent code. Basic matrix operations are noted for optimization for vector processing.

Estimation of Transformation Temperatures in Ti-Ni-Pd Shape Memory Alloys

NASA Astrophysics Data System (ADS)

Narayana, P. L.; Kim, Seong-Woong; Hong, Jae-Keun; Reddy, N. S.; Yeom, Jong-Taek

2018-03-01

The present study focused on estimating the complex nonlinear relationship between the composition and phase transformation temperatures of Ti-Ni-Pd shape memory alloys by artificial neural networks (ANN). The ANN models were developed by using the experimental data of Ti-Ni-Pd alloys. It was found that the predictions are in good agreement with the trained and unseen test data of existing alloys. The developed model was able to simulate new virtual alloys to quantitatively estimate the effect of Ti, Ni, and Pd on transformation temperatures. The transformation temperature behavior of these virtual alloys is validated by conducting new experiments on the Ti-rich thin film that was deposited using multi target sputtering equipment. The transformation behavior of the film was measured by varying the composition with the help of aging treatment. The predicted trend of transformational temperatures was explained with the help of experimental results.

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

Ruotolo, Francesco, E-mail: francesco.ruotolo@unina2.it; Maffei, Luigi, E-mail: luigi.maffei@unina2.it; Di Gabriele, Maria, E-mail: maria.digabriele@unina2.it

Several international studies have shown that traffic noise has a negative impact on people's health and that people's annoyance does not depend only on noise energetic levels, but rather on multi-perceptual factors. The combination of virtual reality technology and audio rendering techniques allow us to experiment a new approach for environmental noise assessment that can help to investigate in advance the potential negative effects of noise associated with a specific project and that in turn can help designers to make educated decisions. In the present study, the audio–visual impact of a new motorway project on people has been assessed bymore » means of immersive virtual reality technology. In particular, participants were exposed to 3D reconstructions of an actual landscape without the projected motorway (ante operam condition), and of the same landscape with the projected motorway (post operam condition). Furthermore, individuals' reactions to noise were assessed by means of objective cognitive measures (short term verbal memory and executive functions) and subjective evaluations (noise and visual annoyance). Overall, the results showed that the introduction of a projected motorway in the environment can have immediate detrimental effects of people's well-being depending on the distance from the noise source. In particular, noise due to the new infrastructure seems to exert a negative influence on short term verbal memory and to increase both visual and noise annoyance. The theoretical and practical implications of these findings are discussed. -- Highlights: ► Impact of traffic noise on people's well-being depends on multi-perceptual factors. ► A multisensory virtual reality technology is used to simulate a projected motorway. ► Effects on short-term memory and auditory and visual subjective annoyance were found. ► The closer the distance from the motorway the stronger was the effect. ► Multisensory virtual reality methodologies can be used to study environmental impact.« less

A virtual shopping test for realistic assessment of cognitive function

PubMed Central

2013-01-01

Background Cognitive dysfunction caused by brain injury often prevents a patient from achieving a healthy and high quality of life. By now, each cognitive function is assessed precisely by neuropsychological tests. However, it is also important to provide an overall assessment of the patients’ ability in their everyday life. We have developed a Virtual Shopping Test (VST) using virtual reality technology. The objective of this study was to clarify 1) the significance of VST by comparing VST with other conventional tests, 2) the applicability of VST to brain-damaged patients, and 3) the performance of VST in relation to age differences. Methods The participants included 10 patients with brain damage, 10 age-matched healthy subjects for controls, 10 old healthy subjects, and 10 young healthy subjects. VST and neuropsychological tests/questionnaires about attention, memory and executive function were conducted on the patients, while VST and the Mini-Mental State Examination (MMSE) were conducted on the controls and healthy subjects. Within the VST, the participants were asked to buy four items in the virtual shopping mall quickly in a rational way. The score for evaluation included the number of items bought correctly, the number of times to refer to hints, the number of movements between shops, and the total time spent to complete the shopping. Results Some variables on VST correlated with the scores of conventional assessment about attention and everyday memory. The mean number of times referring to hints and the mean number of movements were significantly larger for the patients with brain damage, and the mean total time was significantly longer for the patients than for the controls. In addition, the mean total time was significantly longer for the old than for the young. Conclusions The results suggest that VST is able to evaluate the ability of attention and everyday memory in patients with brain damage. The time of VST is increased by age. PMID:23777412

A virtual shopping test for realistic assessment of cognitive function.

PubMed

Okahashi, Sayaka; Seki, Keiko; Nagano, Akinori; Luo, Zhiwei; Kojima, Maki; Futaki, Toshiko

2013-06-18

Cognitive dysfunction caused by brain injury often prevents a patient from achieving a healthy and high quality of life. By now, each cognitive function is assessed precisely by neuropsychological tests. However, it is also important to provide an overall assessment of the patients' ability in their everyday life. We have developed a Virtual Shopping Test (VST) using virtual reality technology. The objective of this study was to clarify 1) the significance of VST by comparing VST with other conventional tests, 2) the applicability of VST to brain-damaged patients, and 3) the performance of VST in relation to age differences. The participants included 10 patients with brain damage, 10 age-matched healthy subjects for controls, 10 old healthy subjects, and 10 young healthy subjects. VST and neuropsychological tests/questionnaires about attention, memory and executive function were conducted on the patients, while VST and the Mini-Mental State Examination (MMSE) were conducted on the controls and healthy subjects. Within the VST, the participants were asked to buy four items in the virtual shopping mall quickly in a rational way. The score for evaluation included the number of items bought correctly, the number of times to refer to hints, the number of movements between shops, and the total time spent to complete the shopping. Some variables on VST correlated with the scores of conventional assessment about attention and everyday memory. The mean number of times referring to hints and the mean number of movements were significantly larger for the patients with brain damage, and the mean total time was significantly longer for the patients than for the controls. In addition, the mean total time was significantly longer for the old than for the young. The results suggest that VST is able to evaluate the ability of attention and everyday memory in patients with brain damage. The time of VST is increased by age.

Improving prospective memory performance with future event simulation in traumatic brain injury patients.

PubMed

Mioni, Giovanna; Bertucci, Erica; Rosato, Antonella; Terrett, Gill; Rendell, Peter G; Zamuner, Massimo; Stablum, Franca

2017-06-01

Previous studies have shown that traumatic brain injury (TBI) patients have difficulties with prospective memory (PM). Considering that PM is closely linked to independent living it is of primary interest to develop strategies that can improve PM performance in TBI patients. This study employed Virtual Week task as a measure of PM, and we included future event simulation to boost PM performance. Study 1 evaluated the efficacy of the strategy and investigated possible practice effects. Twenty-four healthy participants performed Virtual Week in a no strategy condition, and 24 healthy participants performed it in a mixed condition (no strategy - future event simulation). In Study 2, 18 TBI patients completed the mixed condition of Virtual Week and were compared with the 24 healthy controls who undertook the mixed condition of Virtual Week in Study 1. All participants also completed a neuropsychological evaluation to characterize the groups on level of cognitive functioning. Study 1 showed that participants in the future event simulation condition outperformed participants in the no strategy condition, and these results were not attributable to practice effects. Results of Study 2 showed that TBI patients performed PM tasks less accurately than controls, but that future event simulation can substantially reduce TBI-related deficits in PM performance. The future event simulation strategy also improved the controls' PM performance. These studies showed the value of future event simulation strategy in improving PM performance in healthy participants as well as in TBI patients. TBI patients performed PM tasks less accurately than controls, confirming prospective memory impairment in these patients. Participants in the future event simulation condition out-performed participants in the no strategy condition. Future event simulation can substantially reduce TBI-related deficits in PM performance. Future event simulation strategy also improved the controls' PM performance. © 2017 The British Psychological Society.

The sensitivity of a virtual reality task to planning and prospective memory impairments: group differences and the efficacy of periodic alerts on performance.

PubMed

Sweeney, Siobhan; Kersel, Denyse; Morris, Robin G; Manly, Tom; Evans, Jonathan J

2010-04-01

Executive functions have been argued to be the most vulnerable to brain injury. In providing an analogue of everyday situations amenable to control and management virtual reality (VR) may offer better insights into planning deficits consequent upon brain injury. Here 17 participants with a non-progressive brain injury and reported executive difficulties in everyday life were asked to perform a VR task (working in a furniture storage unit) that emphasised planning, rule following and prospective memory tasks. When compared with an age and IQ-matched control group, the patients were significantly poorer in terms of their strategy, their time-based prospective memory, the overall time required and their propensity to break rules. An examination of sensitivity and specificity of the VR task to group membership (brain-injured or control) showed that, with specificity set at maximum, sensitivity was only modest (at just over 50%). A second component to the study investigated whether the patients' performance could be improved by periodic auditory alerts. Previous studies have demonstrated that such cues can improve performance on laboratory tests, executive tests and everyday prospective memory tasks. Here, no significant changes in performance were detected. Potential reasons for this finding are discussed, including symptom severity and differences in the tasks employed in previous studies.

Dynamically programmable cache

NASA Astrophysics Data System (ADS)

Nakkar, Mouna; Harding, John A.; Schwartz, David A.; Franzon, Paul D.; Conte, Thomas

1998-10-01

Reconfigurable machines have recently been used as co- processors to accelerate the execution of certain algorithms or program subroutines. The problems with the above approach include high reconfiguration time and limited partial reconfiguration. By far the most critical problems are: (1) the small on-chip memory which results in slower execution time, and (2) small FPGA areas that cannot implement large subroutines. Dynamically Programmable Cache (DPC) is a novel architecture for embedded processors which offers solutions to the above problems. To solve memory access problems, DPC processors merge reconfigurable arrays with the data cache at various cache levels to create a multi-level reconfigurable machines. As a result DPC machines have both higher data accessibility and FPGA memory bandwidth. To solve the limited FPGA resource problem, DPC processors implemented multi-context switching (Virtualization) concept. Virtualization allows implementation of large subroutines with fewer FPGA cells. Additionally, DPC processors can parallelize the execution of several operations resulting in faster execution time. In this paper, the speedup improvement for DPC machines are shown to be 5X faster than an Altera FLEX10K FPGA chip and 2X faster than a Sun Ultral SPARC station for two different algorithms (convolution and motion estimation).

Can virtual nature improve patient experiences and memories of dental treatment? A study protocol for a randomized controlled trial.

PubMed

Tanja-Dijkstra, Karin; Pahl, Sabine; White, Mathew P; Andrade, Jackie; May, Jon; Stone, Robert J; Bruce, Malcolm; Mills, Ian; Auvray, Melissa; Gabe, Rhys; Moles, David R

2014-03-22

Dental anxiety and anxiety-related avoidance of dental care create significant problems for patients and the dental profession. Distraction interventions are used in daily medical practice to help patients cope with unpleasant procedures. There is evidence that exposure to natural scenery is beneficial for patients and that the use of virtual reality (VR) distraction is more effective than other distraction interventions, such as watching television. The main aim of this randomized controlled trial is to determine whether the use of VR during dental treatment can improve the overall dental experience and recollections of treatment for patients, breaking the negative cycle of memories of anxiety leading to further anxiety, and avoidance of future dental appointments. Additionally, the aim is to test whether VR benefits dental patients with all levels of dental anxiety or whether it could be especially beneficial for patients suffering from higher levels of dental anxiety. The third aim is to test whether the content of the VR distraction can make a difference for its effectiveness by comparing two types of virtual environments, a natural environment and an urban environment. The effectiveness of VR distraction will be examined in patients 18 years or older who are scheduled to undergo dental treatment for fillings and/or extractions, with a maximum length of 30 minutes. Patients will be randomly allocated into one of three groups. The first group will be exposed to a VR of a natural environment. The second group will be exposed to a VR of an urban environment. A third group consists of patients who receive standard care (control group). Primary outcomes relate to patients' memories of the dental treatment one week after treatment: (a) remembered pain, (b) intrusive thoughts and (c) vividness of memories. Other measures of interest are the dental experience, the treatment experience and the VR experience. Current Controlled Trials ISRCTN41442806.

Parallel reduced-instruction-set-computer architecture for real-time symbolic pattern matching

NASA Astrophysics Data System (ADS)

Parson, Dale E.

1991-03-01

This report discusses ongoing work on a parallel reduced-instruction- set-computer (RISC) architecture for automatic production matching. The PRIOPS compiler takes advantage of the memoryless character of automatic processing by translating a program's collection of automatic production tests into an equivalent combinational circuit-a digital circuit without memory, whose outputs are immediate functions of its inputs. The circuit provides a highly parallel, fine-grain model of automatic matching. The compiler then maps the combinational circuit onto RISC hardware. The heart of the processor is an array of comparators capable of testing production conditions in parallel, Each comparator attaches to private memory that contains virtual circuit nodes-records of the current state of nodes and busses in the combinational circuit. All comparator memories hold identical information, allowing simultaneous update for a single changing circuit node and simultaneous retrieval of different circuit nodes by different comparators. Along with the comparator-based logic unit is a sequencer that determines the current combination of production-derived comparisons to try, based on the combined success and failure of previous combinations of comparisons. The memoryless nature of automatic matching allows the compiler to designate invariant memory addresses for virtual circuit nodes, and to generate the most effective sequences of comparison test combinations. The result is maximal utilization of parallel hardware, indicating speed increases and scalability beyond that found for course-grain, multiprocessor approaches to concurrent Rete matching. Future work will consider application of this RISC architecture to the standard (controlled) Rete algorithm, where search through memory dominates portions of matching.

Virtual Environmental Enrichment through Video Games Improves Hippocampal-Associated Memory

PubMed Central

Clemenson, Gregory D.

2015-01-01

The positive effects of environmental enrichment and their neural bases have been studied extensively in the rodent (van Praag et al., 2000). For example, simply modifying an animal's living environment to promote sensory stimulation can lead to (but is not limited to) enhancements in hippocampal cognition and neuroplasticity and can alleviate hippocampal cognitive deficits associated with neurodegenerative diseases and aging. We are interested in whether these manipulations that successfully enhance cognition (or mitigate cognitive decline) have similar influences on humans. Although there are many “enriching” aspects to daily life, we are constantly adapting to new experiences and situations within our own environment on a daily basis. Here, we hypothesize that the exploration of the vast and visually stimulating virtual environments within video games is a human correlate of environmental enrichment. We show that video gamers who specifically favor complex 3D video games performed better on a demanding recognition memory task that assesses participants' ability to discriminate highly similar lure items from repeated items. In addition, after 2 weeks of training on the 3D video game Super Mario 3D World, naive video gamers showed improved mnemonic discrimination ability and improvements on a virtual water maze task. Two control conditions (passive and training in a 2D game, Angry Birds), showed no such improvements. Furthermore, individual performance in both hippocampal-associated behaviors correlated with performance in Super Mario but not Angry Birds, suggesting that how individuals explored the virtual environment may influence hippocampal behavior. SIGNIFICANCE STATEMENT The hippocampus has long been associated with episodic memory and is commonly thought to rely on neuroplasticity to adapt to the ever-changing environment. In animals, it is well understood that exposing animals to a more stimulating environment, known as environmental enrichment, can stimulate neuroplasticity and improve hippocampal function and performance on hippocampally mediated memory tasks. Here, we suggest that the exploration of vast and visually stimulating environments within modern-day video games can act as a human correlate of environmental enrichment. Training naive video gamers in a rich 3D, but not 2D, video game, resulted in a significant improvement in hippocampus-associated cognition using several behavioral measures. Our results suggest that modern day video games may provide meaningful stimulation to the human hippocampus. PMID:26658864

Virtual Environmental Enrichment through Video Games Improves Hippocampal-Associated Memory.

PubMed

Clemenson, Gregory D; Stark, Craig E L

2015-12-09

The positive effects of environmental enrichment and their neural bases have been studied extensively in the rodent (van Praag et al., 2000). For example, simply modifying an animal's living environment to promote sensory stimulation can lead to (but is not limited to) enhancements in hippocampal cognition and neuroplasticity and can alleviate hippocampal cognitive deficits associated with neurodegenerative diseases and aging. We are interested in whether these manipulations that successfully enhance cognition (or mitigate cognitive decline) have similar influences on humans. Although there are many "enriching" aspects to daily life, we are constantly adapting to new experiences and situations within our own environment on a daily basis. Here, we hypothesize that the exploration of the vast and visually stimulating virtual environments within video games is a human correlate of environmental enrichment. We show that video gamers who specifically favor complex 3D video games performed better on a demanding recognition memory task that assesses participants' ability to discriminate highly similar lure items from repeated items. In addition, after 2 weeks of training on the 3D video game Super Mario 3D World, naive video gamers showed improved mnemonic discrimination ability and improvements on a virtual water maze task. Two control conditions (passive and training in a 2D game, Angry Birds), showed no such improvements. Furthermore, individual performance in both hippocampal-associated behaviors correlated with performance in Super Mario but not Angry Birds, suggesting that how individuals explored the virtual environment may influence hippocampal behavior. The hippocampus has long been associated with episodic memory and is commonly thought to rely on neuroplasticity to adapt to the ever-changing environment. In animals, it is well understood that exposing animals to a more stimulating environment, known as environmental enrichment, can stimulate neuroplasticity and improve hippocampal function and performance on hippocampally mediated memory tasks. Here, we suggest that the exploration of vast and visually stimulating environments within modern-day video games can act as a human correlate of environmental enrichment. Training naive video gamers in a rich 3D, but not 2D, video game, resulted in a significant improvement in hippocampus-associated cognition using several behavioral measures. Our results suggest that modern day video games may provide meaningful stimulation to the human hippocampus. Copyright © 2015 the authors 0270-6474/15/3516116-10$15.00/0.

The Elderly Perceived Meanings and Values of Virtual Reality Leisure Activities: A Means-End Chain Approach

PubMed Central

Lin, Cheng-Shih; Jeng, Mei-Yuan

2018-01-01

This study uses means-end chain (MEC) techniques to examine the awareness, decision-making procedure, and personal values of the elderly with regard to virtual reality leisure activities. The results of the study show that elderly respondents value virtual reality leisure activities that are fun, safe, and easy. In terms of outcome benefits, elderly respondents value feeling physically and mentally healthy, firsthand experience, and satisfied curiosity. In value terms, elderly respondents hope that their chosen virtual reality leisure activities improve not only their relationships with others, but also their enjoyment, quality of life, and sense of belonging. The results show that, while consumers with different awarenesses of virtual reality leisure activities have different decision-making processes, they share creating “good memories” as the terminal value with the most significant effect. This presents a potential opportunity to promote virtual reality leisure activities. Relevant bodies or enterprises can seek to create good memories in consumers by developing activities that are safe and fun, promote good health, and provide good service, thereby attracting the interest of elderly consumers. PMID:29614012

PiCO QL: A software library for runtime interactive queries on program data

NASA Astrophysics Data System (ADS)

Fragkoulis, Marios; Spinellis, Diomidis; Louridas, Panos

PiCO QL is an open source C/C++ software whose scientific scope is real-time interactive analysis of in-memory data through SQL queries. It exposes a relational view of a system's or application's data structures, which is queryable through SQL. While the application or system is executing, users can input queries through a web-based interface or issue web service requests. Queries execute on the live data structures through the respective relational views. PiCO QL makes a good candidate for ad-hoc data analysis in applications and for diagnostics in systems settings. Applications of PiCO QL include the Linux kernel, the Valgrind instrumentation framework, a GIS application, a virtual real-time observatory of stellar objects, and a source code analyser.

Spatial Navigation Impairments Among Intellectually High-Functioning Adults With Autism Spectrum Disorder: Exploring Relations With Theory of Mind, Episodic Memory, and Episodic Future Thinking

PubMed Central

2013-01-01

Research suggests that spatial navigation relies on the same neural network as episodic memory, episodic future thinking, and theory of mind (ToM). Such findings have stimulated theories (e.g., the scene construction and self-projection hypotheses) concerning possible common underlying cognitive capacities. Consistent with such theories, autism spectrum disorder (ASD) is characterized by concurrent impairments in episodic memory, episodic future thinking, and ToM. However, it is currently unclear whether spatial navigation is also impaired. Hence, ASD provides a test case for the scene construction and self-projection theories. The study of spatial navigation in ASD also provides a test of the extreme male brain theory of ASD, which predicts intact or superior navigation (purportedly a systemizing skill) performance among individuals with ASD. Thus, the aim of the current study was to establish whether spatial navigation in ASD is impaired, intact, or superior. Twenty-seven intellectually high-functioning adults with ASD and 28 sex-, age-, and IQ-matched neurotypical comparison adults completed the memory island virtual navigation task. Tests of episodic memory, episodic future thinking, and ToM were also completed. Participants with ASD showed significantly diminished performance on the memory island task, and performance was positively related to ToM and episodic memory, but not episodic future thinking. These results suggest that (contra the extreme male brain theory) individuals with ASD have impaired survey-based navigation skills—that is, difficulties generating cognitive maps of the environment—and adds weight to the idea that scene construction/self-projection are impaired in ASD. The theoretical and clinical implications of these results are discussed. PMID:24364620

Cognitive ability predicts motor learning on a virtual reality game in patients with TBI.

PubMed

O'Neil, Rochelle L; Skeel, Reid L; Ustinova, Ksenia I

2013-01-01

Virtual reality games and simulations have been utilized successfully for motor rehabilitation of individuals with traumatic brain injury (TBI). Little is known, however, how TBI-related cognitive decline affects learning of motor tasks in virtual environments. To fill this gap, we examined learning within a virtual reality game involving various reaching motions in 14 patients with TBI and 15 healthy individuals with different cognitive abilities. All participants practiced ten 90-second gaming trials to assess various aspects of motor learning. Cognitive abilities were assessed with a battery of tests including measures of memory, executive functioning, and visuospatial ability. Overall, participants with TBI showed both reduced performance and a slower learning rate in the virtual reality game compared to healthy individuals. Numerous correlations between overall performance and several of the cognitive ability domains were revealed for both the patient and control groups, with the best predictor being overall cognitive ability. The results may provide a starting point for rehabilitation programs regarding which cognitive domains interact with motor learning.

Cognitive and neural plasticity in older adults’ prospective memory following training with the Virtual Week computer game

PubMed Central

Rose, Nathan S.; Rendell, Peter G.; Hering, Alexandra; Kliegel, Matthias; Bidelman, Gavin M.; Craik, Fergus I. M.

2015-01-01

Prospective memory (PM) – the ability to remember and successfully execute our intentions and planned activities – is critical for functional independence and declines with age, yet few studies have attempted to train PM in older adults. We developed a PM training program using the Virtual Week computer game. Trained participants played the game in 12, 1-h sessions over 1 month. Measures of neuropsychological functions, lab-based PM, event-related potentials (ERPs) during performance on a lab-based PM task, instrumental activities of daily living, and real-world PM were assessed before and after training. Performance was compared to both no-contact and active (music training) control groups. PM on the Virtual Week game dramatically improved following training relative to controls, suggesting PM plasticity is preserved in older adults. Relative to control participants, training did not produce reliable transfer to laboratory-based tasks, but was associated with a reduction of an ERP component (sustained negativity over occipito-parietal cortex) associated with processing PM cues, indicative of more automatic PM retrieval. Most importantly, training produced far transfer to real-world outcomes including improvements in performance on real-world PM and activities of daily living. Real-world gains were not observed in either control group. Our findings demonstrate that short-term training with the Virtual Week game produces cognitive and neural plasticity that may result in real-world benefits to supporting functional independence in older adulthood. PMID:26578936

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

PubMed Central

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

2016-01-01

Using novel virtual cities, we investigated the influence of verbal and visual strategies on the encoding of navigation-relevant information in a large-scale virtual environment. In two experiments, participants watched videos of routes through four virtual cities and were subsequently tested on their memory for observed landmarks and on their ability to make judgments regarding the relative directions of the different landmarks along the route. In the first experiment, self-report questionnaires measuring visual and verbal cognitive styles were administered to examine correlations between cognitive styles, landmark recognition, and judgments of relative direction. Results demonstrate a tradeoff in which the verbal cognitive style is more beneficial for recognizing individual landmarks than for judging relative directions between them, whereas the visual cognitive style is more beneficial for judging relative directions than for landmark recognition. In a second experiment, we manipulated the use of verbal and visual strategies by varying task instructions given to separate groups of participants. Results confirm that a verbal strategy benefits landmark memory, whereas a visual strategy benefits judgments of relative direction. The manipulation of strategy by altering task instructions appears to trump individual differences in cognitive style. Taken together, we find that processing different details during route encoding, whether due to individual proclivities (Experiment 1) or task instructions (Experiment 2), results in benefits for different components of navigation relevant information. These findings also highlight the value of considering multiple sources of individual differences as part of spatial cognition investigations. PMID:27668486

Pictorial communication in virtual and real environments

NASA Technical Reports Server (NTRS)

Ellis, Stephen R. (Editor)

1991-01-01

Papers about the communication between human users and machines in real and synthetic environments are presented. Individual topics addressed include: pictorial communication, distortions in memory for visual displays, cartography and map displays, efficiency of graphical perception, volumetric visualization of 3D data, spatial displays to increase pilot situational awareness, teleoperation of land vehicles, computer graphics system for visualizing spacecraft in orbit, visual display aid for orbital maneuvering, multiaxis control in telemanipulation and vehicle guidance, visual enhancements in pick-and-place tasks, target axis effects under transformed visual-motor mappings, adapting to variable prismatic displacement. Also discussed are: spatial vision within egocentric and exocentric frames of reference, sensory conflict in motion sickness, interactions of form and orientation, perception of geometrical structure from congruence, prediction of three-dimensionality across continuous surfaces, effects of viewpoint in the virtual space of pictures, visual slant underestimation, spatial constraints of stereopsis in video displays, stereoscopic stance perception, paradoxical monocular stereopsis and perspective vergence. (No individual items are abstracted in this volume)

Effects of noise and working memory capacity on memory processing of speech for hearing-aid users.

PubMed

Ng, Elaine Hoi Ning; Rudner, Mary; Lunner, Thomas; Pedersen, Michael Syskind; Rönnberg, Jerker

2013-07-01

It has been shown that noise reduction algorithms can reduce the negative effects of noise on memory processing in persons with normal hearing. The objective of the present study was to investigate whether a similar effect can be obtained for persons with hearing impairment and whether such an effect is dependent on individual differences in working memory capacity. A sentence-final word identification and recall (SWIR) test was conducted in two noise backgrounds with and without noise reduction as well as in quiet. Working memory capacity was measured using a reading span (RS) test. Twenty-six experienced hearing-aid users with moderate to moderately severe sensorineural hearing loss. Noise impaired recall performance. Competing speech disrupted memory performance more than speech-shaped noise. For late list items the disruptive effect of the competing speech background was virtually cancelled out by noise reduction for persons with high working memory capacity. Noise reduction can reduce the adverse effect of noise on memory for speech for persons with good working memory capacity. We argue that the mechanism behind this is faster word identification that enhances encoding into working memory.

An automated system for assessing cognitive function in any environment

NASA Astrophysics Data System (ADS)

Wesnes, Keith A.

2005-05-01

The Cognitive Drug Research (CDR) computerized assessment system has been in use in worldwide clinical trials for over 20 years. It is a computer based system which assesses core aspects of human cognitive function including attention, information, working memory and long-term memory. It has been extensively validated and can be performed by a wide range of clinical populations including patients with various types of dementia. It is currently in worldwide use in clinical trials to evaluate new medicines, as well as a variety of programs involving the effects of age, stressors illnesses and trauma upon human cognitive function. Besides being highly sensitive to drugs which will impair or improve function, its utility has been maintained over the last two decades by constantly increasing the number of platforms upon which it can operate. Besides notebook versions, the system can be used on a wrist worn device, PDA, via tht telephone and over the internet. It is the most widely used automated cognitive function assessment system in worldwide clinical research. It has dozens of parallel forms and requires little training to use or administer. The basic development of the system wil be identified, and the huge databases (normative, patient population, drug effects) which have been built up from hundreds of clinical trials will be described. The system is available for use in virtually any environment or type of trial.

Machine Learning Feature Selection for Tuning Memory Page Swapping

DTIC Science & Technology

2013-09-01

environments we set up. 13 Figure 4.1 Updated Feature Vector List. Features we added to the kernel are anno - tated with “(MLVM...Feb. 1966. [2] P. J . Denning, “The working set model for program behavior,” Communications of the ACM, vol. 11, no. 5, pp. 323–333, May 1968. [3] L. A...8] R. W. Cart and J . L. Hennessy, “WSClock — A simple and effective algorithm for virtual memory management,” M.S. thesis, Dept. Computer Science

PANDA: A distributed multiprocessor operating system

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

Chubb, P.

1989-01-01

PANDA is a design for a distributed multiprocessor and an operating system. PANDA is designed to allow easy expansion of both hardware and software. As such, the PANDA kernel provides only message passing and memory and process management. The other features needed for the system (device drivers, secondary storage management, etc.) are provided as replaceable user tasks. The thesis presents PANDA's design and implementation, both hardware and software. PANDA uses multiple 68010 processors sharing memory on a VME bus, each such node potentially connected to others via a high speed network. The machine is completely homogeneous: there are no differencesmore » between processors that are detectable by programs running on the machine. A single two-processor node has been constructed. Each processor contains memory management circuits designed to allow processors to share page tables safely. PANDA presents a programmers' model similar to the hardware model: a job is divided into multiple tasks, each having its own address space. Within each task, multiple processes share code and data. Tasks can send messages to each other, and set up virtual circuits between themselves. Peripheral devices such as disc drives are represented within PANDA by tasks. PANDA divides secondary storage into volumes, each volume being accessed by a volume access task, or VAT. All knowledge about the way that data is stored on a disc is kept in its volume's VAT. The design is such that PANDA should provide a useful testbed for file systems and device drivers, as these can be installed without recompiling PANDA itself, and without rebooting the machine.« less

Control of gaze in natural environments: effects of rewards and costs, uncertainty and memory in target selection.

PubMed

Hayhoe, Mary M; Matthis, Jonathan Samir

2018-08-06

The development of better eye and body tracking systems, and more flexible virtual environments have allowed more systematic exploration of natural vision and contributed a number of insights. In natural visually guided behaviour, humans make continuous sequences of sensory-motor decisions to satisfy current goals, and the role of vision is to provide the relevant information in order to achieve those goals. This paper reviews the factors that control gaze in natural visually guided actions such as locomotion, including the rewards and costs associated with the immediate behavioural goals, uncertainty about the state of the world and prior knowledge of the environment. These general features of human gaze control may inform the development of artificial systems.

Recurrent Network models of sequence generation and memory

PubMed Central

Rajan, Kanaka; Harvey, Christopher D; Tank, David W

2016-01-01

SUMMARY Sequential activation of neurons is a common feature of network activity during a variety of behaviors, including working memory and decision making. Previous network models for sequences and memory emphasized specialized architectures in which a principled mechanism is pre-wired into their connectivity. Here, we demonstrate that starting from random connectivity and modifying a small fraction of connections, a largely disordered recurrent network can produce sequences and implement working memory efficiently. We use this process, called Partial In-Network training (PINning), to model and match cellular-resolution imaging data from the posterior parietal cortex during a virtual memory-guided two-alternative forced choice task [Harvey, Coen and Tank, 2012]. Analysis of the connectivity reveals that sequences propagate by the cooperation between recurrent synaptic interactions and external inputs, rather than through feedforward or asymmetric connections. Together our results suggest that neural sequences may emerge through learning from largely unstructured network architectures. PMID:26971945

Programmable Pulse Generator

NASA Technical Reports Server (NTRS)

Rhim, W. K.; Dart, J. A.

1982-01-01

New pulse generator programmed to produce pulses from several ports at different pulse lengths and intervals and virtually any combination and sequence. Unit contains a 256-word-by-16-bit memory loaded with instructions either manually or by computer. Once loaded, unit operates independently of computer.

Digital item for digital human memory--television commerce application: family tree albuming system

NASA Astrophysics Data System (ADS)

Song, Jaeil; Lee, Hyejoo; Hong, JinWoo

2004-01-01

Technical advance in creating, storing digital media in daily life enables computers to capture human life and remember it as people do. A critical point with digitizing human life is how to recall bits of experience that are associated by semantic information. This paper proposes a technique for structuring dynamic digital object based on MPEG-21 Digital Item (DI) in order to recall human"s memory and providing interactive TV service on family tree albuming system as one of its applications. DIs are a dynamically reconfigurable, uniquely identified, described by a descriptor language, logical unit for structuring relationship among multiple media resources. Digital Item Processing (DIP) provides the means to interact with DIs to remind context to user, with active properties where objects have executable properties. Each user can adapt DIs" active properties to tailor the behavior of DIs to match his/her own specific needs. DIs" technologies in Intellectual Property Management and Protection (IPMP) can be used for privacy protection. In the interaction between the social space and technological space, the internal dynamics of family life fits well sharing family albuming service via family television. Family albuming service can act as virtual communities builders for family members. As memory is shared between family members, multiple annotations (including active properties on contextual information) will be made with snowballing value.

Development of a cognitive function test using virtual reality technology: examination in healthy participants.

PubMed

Sakai, Hiromi; Nagano, Akinori; Seki, Keiko; Okahashi, Sayaka; Kojima, Maki; Luo, Zhiwei

2018-07-01

We developed a virtual reality test to assess the cognitive function of Japanese people in near-daily-life environment, namely, a virtual shopping test (VST). In this test, participants were asked to execute shopping tasks using touch panel operations in a "virtual shopping mall." We examined differences in VST performances among healthy participants of different ages and correlations between VST and screening tests, such as the Mini-Mental State Examination (MMSE) and Everyday Memory Checklist (EMC). We included 285 healthy participants between 20 and 86 years of age in seven age groups. Therefore, each VST index tended to decrease with advancing age; differences among age groups were significant. Most VST indices had a significantly negative correlation with MMSE and significantly positive correlation with EMC. VST may be useful for assessing general cognitive decline; effects of age must be considered for proper interpretation of the VST scores.

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.

Proceedings: Sisal `93

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

Feo, J.T.

1993-10-01

This report contain papers on: Programmability and performance issues; The case of an iterative partial differential equation solver; Implementing the kernal of the Australian Region Weather Prediction Model in Sisal; Even and quarter-even prime length symmetric FFTs and their Sisal Implementations; Top-down thread generation for Sisal; Overlapping communications and computations on NUMA architechtures; Compiling technique based on dataflow analysis for funtional programming language Valid; Copy elimination for true multidimensional arrays in Sisal 2.0; Increasing parallelism for an optimization that reduces copying in IF2 graphs; Caching in on Sisal; Cache performance of Sisal Vs. FORTRAN; FFT algorithms on a shared-memory multiprocessor;more » A parallel implementation of nonnumeric search problems in Sisal; Computer vision algorithms in Sisal; Compilation of Sisal for a high-performance data driven vector processor; Sisal on distributed memory machines; A virtual shared addressing system for distributed memory Sisal; Developing a high-performance FFT algorithm in Sisal for a vector supercomputer; Implementation issues for IF2 on a static data-flow architechture; and Systematic control of parallelism in array-based data-flow computation. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.« less

Interactive physically-based sound simulation

NASA Astrophysics Data System (ADS)

Raghuvanshi, Nikunj

The realization of interactive, immersive virtual worlds requires the ability to present a realistic audio experience that convincingly compliments their visual rendering. Physical simulation is a natural way to achieve such realism, enabling deeply immersive virtual worlds. However, physically-based sound simulation is very computationally expensive owing to the high-frequency, transient oscillations underlying audible sounds. The increasing computational power of desktop computers has served to reduce the gap between required and available computation, and it has become possible to bridge this gap further by using a combination of algorithmic improvements that exploit the physical, as well as perceptual properties of audible sounds. My thesis is a step in this direction. My dissertation concentrates on developing real-time techniques for both sub-problems of sound simulation: synthesis and propagation. Sound synthesis is concerned with generating the sounds produced by objects due to elastic surface vibrations upon interaction with the environment, such as collisions. I present novel techniques that exploit human auditory perception to simulate scenes with hundreds of sounding objects undergoing impact and rolling in real time. Sound propagation is the complementary problem of modeling the high-order scattering and diffraction of sound in an environment as it travels from source to listener. I discuss my work on a novel numerical acoustic simulator (ARD) that is hundred times faster and consumes ten times less memory than a high-accuracy finite-difference technique, allowing acoustic simulations on previously-intractable spaces, such as a cathedral, on a desktop computer. Lastly, I present my work on interactive sound propagation that leverages my ARD simulator to render the acoustics of arbitrary static scenes for multiple moving sources and listener in real time, while accounting for scene-dependent effects such as low-pass filtering and smooth attenuation behind obstructions, reverberation, scattering from complex geometry and sound focusing. This is enabled by a novel compact representation that takes a thousand times less memory than a direct scheme, thus reducing memory footprints to fit within available main memory. To the best of my knowledge, this is the only technique and system in existence to demonstrate auralization of physical wave-based effects in real-time on large, complex 3D scenes.

Magic cards: a new augmented-reality approach.

PubMed

Demuynck, Olivier; Menendez, José Manuel

2013-01-01

Augmented reality (AR) commonly uses markers for detection and tracking. Such multimedia applications associate each marker with a virtual 3D model stored in the memory of the camera-equipped device running the application. Application users are limited in their interactions, which require knowing how to design and program 3D objects. This generally prevents them from developing their own entertainment AR applications. The Magic Cards application solves this problem by offering an easy way to create and manage an unlimited number of virtual objects that are encoded on special markers.

Side-channel-free quantum key distribution.

PubMed

Braunstein, Samuel L; Pirandola, Stefano

2012-03-30

Quantum key distribution (QKD) offers the promise of absolutely secure communications. However, proofs of absolute security often assume perfect implementation from theory to experiment. Thus, existing systems may be prone to insidious side-channel attacks that rely on flaws in experimental implementation. Here we replace all real channels with virtual channels in a QKD protocol, making the relevant detectors and settings inside private spaces inaccessible while simultaneously acting as a Hilbert space filter to eliminate side-channel attacks. By using a quantum memory we find that we are able to bound the secret-key rate below by the entanglement-distillation rate computed over the distributed states.

Trichotomous processes in early memory development, aging, and neurocognitive impairment: a unified theory.

PubMed

Brainerd, C J; Reyna, V F; Howe, M L

2009-10-01

One of the most extensively investigated topics in the adult memory literature, dual memory processes, has had virtually no impact on the study of early memory development. The authors remove the key obstacles to such research by formulating a trichotomous theory of recall that combines the traditional dual processes of recollection and familiarity with a reconstruction process. The theory is then embedded in a hidden Markov model that measures all 3 processes with low-burden tasks that are appropriate for even young children. These techniques are applied to a large corpus of developmental studies of recall, yielding stable findings about the emergence of dual memory processes between childhood and young adulthood and generating tests of many theoretical predictions. The techniques are extended to the study of healthy aging and to the memory sequelae of common forms of neurocognitive impairment, resulting in a theoretical framework that is unified over 4 major domains of memory research: early development, mainstream adult research, aging, and neurocognitive impairment. The techniques are also extended to recognition, creating a unified dual process framework for recall and recognition.

Choice-specific sequences in parietal cortex during a virtual-navigation decision task

PubMed Central

Harvey, Christopher D.; Coen, Philip; Tank, David W.

2012-01-01

The posterior parietal cortex (PPC) plays an important role in many cognitive behaviors; however, the neural circuit dynamics underlying PPC function are not well understood. Here we optically imaged the spatial and temporal activity patterns of neuronal populations in mice performing a PPC-dependent task that combined a perceptual decision and memory-guided navigation in a virtual environment. Individual neurons had transient activation staggered relative to one another in time, forming a sequence of neuronal activation spanning the entire length of a task trial. Distinct sequences of neurons were triggered on trials with opposite behavioral choices and defined divergent, choice-specific trajectories through a state space of neuronal population activity. Cells participating in the different sequences and at distinct time points in the task were anatomically intermixed over microcircuit length scales (< 100 micrometers). During working memory decision tasks the PPC may therefore perform computations through sequence-based circuit dynamics, rather than long-lived stable states, implemented using anatomically intermingled microcircuits. PMID:22419153

Stereopsis, Visuospatial Ability, and Virtual Reality in Anatomy Learning

PubMed Central

Vorstenbosch, Marc; Kooloos, Jan

2017-01-01

A new wave of virtual reality headsets has become available. A potential benefit for the study of human anatomy is the reintroduction of stereopsis and absolute size. We report a randomized controlled trial to assess the contribution of stereopsis to anatomy learning, for students of different visuospatial ability. Sixty-three participants engaged in a one-hour session including a study phase and posttest. One group studied 3D models of the anatomy of the deep neck in full stereoptic virtual reality; one group studied those structures in virtual reality without stereoptic depth. The control group experienced an unrelated virtual reality environment. A post hoc questionnaire explored cognitive load and problem solving strategies of the participants. We found no effect of condition on learning. Visuospatial ability however did impact correct answers at F(1) = 5.63 and p = .02. No evidence was found for an impact of cognitive load on performance. Possibly, participants were able to solve the posttest items based on visuospatial information contained in the test items themselves. Additionally, the virtual anatomy may have been complex enough to discourage memory based strategies. It is important to control the amount of visuospatial information present in test items. PMID:28656109

Virtual Reality Exposure Training for Musicians: Its Effect on Performance Anxiety and Quality.

PubMed

Bissonnette, Josiane; Dubé, Francis; Provencher, Martin D; Moreno Sala, Maria T

2015-09-01

Music performance anxiety affects numerous musicians, with many of them reporting impairment of performance due to this problem. This exploratory study investigated the effects of virtual reality exposure training on students with music performance anxiety. Seventeen music students were randomly assigned to a control group (n=8) or a virtual training group (n=9). Participants were asked to play a musical piece by memory in two separate recitals within a 3-week interval. Anxiety was then measured with the Personal Report of Confidence as a Performer Scale and the S-Anxiety scale from the State-Trait Anxiety Inventory (STAI-Y). Between pre- and post-tests, the virtual training group took part in virtual reality exposure training consisting of six 1-hour long sessions of virtual exposure. The results indicate a significant decrease in performance anxiety for musicians in the treatment group for those with a high level of state anxiety, for those with a high level of trait anxiety, for women, and for musicians with high immersive tendencies. Finally, between the pre- and post-tests, we observed a significant increase in performance quality for the experimental group, but not for the control group.

Stereopsis, Visuospatial Ability, and Virtual Reality in Anatomy Learning.

PubMed

Luursema, Jan-Maarten; Vorstenbosch, Marc; Kooloos, Jan

2017-01-01

A new wave of virtual reality headsets has become available. A potential benefit for the study of human anatomy is the reintroduction of stereopsis and absolute size. We report a randomized controlled trial to assess the contribution of stereopsis to anatomy learning, for students of different visuospatial ability. Sixty-three participants engaged in a one-hour session including a study phase and posttest. One group studied 3D models of the anatomy of the deep neck in full stereoptic virtual reality; one group studied those structures in virtual reality without stereoptic depth. The control group experienced an unrelated virtual reality environment. A post hoc questionnaire explored cognitive load and problem solving strategies of the participants. We found no effect of condition on learning. Visuospatial ability however did impact correct answers at F (1) = 5.63 and p = .02. No evidence was found for an impact of cognitive load on performance. Possibly, participants were able to solve the posttest items based on visuospatial information contained in the test items themselves. Additionally, the virtual anatomy may have been complex enough to discourage memory based strategies. It is important to control the amount of visuospatial information present in test items.

Positive and negative emotional contexts unevenly predict episodic memory.

PubMed

Martínez-Galindo, Joyce Graciela; Cansino, Selene

2015-09-15

The aim of this study was to investigate whether the recognition of faces with neutral expressions differs when they are encoded under different emotional contexts (positive, negative or non-emotional). The effects of the emotional valence context on the subsequent memory effect (SME) and the autonomic responses were also examined. Twenty-eight participants performed a betting-game task in which the faces of their virtual opponents were presented in each trial. The probability of winning or losing was manipulated to generate positive or negative contexts, respectively. Additionally, the participants performed the same task without betting as a non-emotional condition. After the encoding phase, an old/new paradigm was performed for the faces of the virtual opponents. The recognition was superior for the faces encoded in the positive contexts than for the faces encoded in the non-emotional contexts. The skin conductance response amplitude was equivalent for both of the emotional contexts. The N170 and P300 components at occipital sites and the frontal slow wave manifested SMEs that were modulated by positive contexts; neither negative nor non-emotional contexts influenced these effects. The behavioral and neurophysiological data demonstrated that positive contexts are stronger predictors of episodic memory than negative or non-emotional contexts. Copyright © 2015 Elsevier B.V. All rights reserved.

A virtual reality system for neurobehavioral and functional MRI studies.

PubMed

Baumann, Stephen; Neff, Chris; Fetzick, Scott; Stangl, Gregg; Basler, Lee; Vereneck, Ray; Schneider, Walter

2003-06-01

We are developing a VR system of integrated software and hardware for scientific research and clinical application. The system is sufficiently flexible and broad-based in appeal that neurobehavioral researchers from a variety of disciplines might be interested in using it for basic research and clinical studies. The system runs on a standard Windows-based personal computer with a high-performance graphics card. Options allow a head-mounted display, dataglove, simultaneous physiological monitoring or use within neuroimaging machines such as magnetic resonance imaging (MRI) scanners. Currently, the software consists of a virtual world of nearly a dozen interconnected environments that the subject can freely navigate. Additional environments can be built and easily added to the application. A startup interface provides menus for selecting characters and objects that a researcher might want to put at specific locations within the simulation. Interactivity is provided for many typical objects such as doors, chairs and money. There are more than 50 characters in the world, most of them animated or interactive. All movements and actions of the subject within the world are tracked and recorded to an Excel spreadsheet for data analysis. Overlay maps are available as navigational aids. Concurrent physiological data can be acquired on up to 16 channels. The system provides synchronization of the VR simulation with physiological recordings and functional MR images. A spatial navigation memory task was performed with the integrated VR/fMRI system, and some pilot data is presented that shows robust activation in multiple cortical areas appropriate to the task.

Assessing the Driver’s Current Level of Working Memory Load with High Density Functional Near-infrared Spectroscopy: A Realistic Driving Simulator Study

PubMed Central

Unni, Anirudh; Ihme, Klas; Jipp, Meike; Rieger, Jochem W.

2017-01-01

Cognitive overload or underload results in a decrease in human performance which may result in fatal incidents while driving. We envision that driver assistive systems which adapt their functionality to the driver’s cognitive state could be a promising approach to reduce road accidents due to human errors. This research attempts to predict variations of cognitive working memory load levels in a natural driving scenario with multiple parallel tasks and to reveal predictive brain areas. We used a modified version of the n-back task to induce five different working memory load levels (from 0-back up to 4-back) forcing the participants to continuously update, memorize, and recall the previous ‘n’ speed sequences and adjust their speed accordingly while they drove for approximately 60 min on a highway with concurrent traffic in a virtual reality driving simulator. We measured brain activation using multichannel whole head, high density functional near-infrared spectroscopy (fNIRS) and predicted working memory load level from the fNIRS data by combining multivariate lasso regression and cross-validation. This allowed us to predict variations in working memory load in a continuous time-resolved manner with mean Pearson correlations between induced and predicted working memory load over 15 participants of 0.61 [standard error (SE) 0.04] and a maximum of 0.8. Restricting the analysis to prefrontal sensors placed over the forehead reduced the mean correlation to 0.38 (SE 0.04), indicating additional information gained through whole head coverage. Moreover, working memory load predictions derived from peripheral heart rate parameters achieved much lower correlations (mean 0.21, SE 0.1). Importantly, whole head fNIRS sampling revealed increasing brain activation in bilateral inferior frontal and bilateral temporo-occipital brain areas with increasing working memory load levels suggesting that these areas are specifically involved in workload-related processing. PMID:28424602

Assessing the Driver's Current Level of Working Memory Load with High Density Functional Near-infrared Spectroscopy: A Realistic Driving Simulator Study.

PubMed

Unni, Anirudh; Ihme, Klas; Jipp, Meike; Rieger, Jochem W

2017-01-01

Cognitive overload or underload results in a decrease in human performance which may result in fatal incidents while driving. We envision that driver assistive systems which adapt their functionality to the driver's cognitive state could be a promising approach to reduce road accidents due to human errors. This research attempts to predict variations of cognitive working memory load levels in a natural driving scenario with multiple parallel tasks and to reveal predictive brain areas. We used a modified version of the n-back task to induce five different working memory load levels (from 0-back up to 4-back) forcing the participants to continuously update, memorize, and recall the previous 'n' speed sequences and adjust their speed accordingly while they drove for approximately 60 min on a highway with concurrent traffic in a virtual reality driving simulator. We measured brain activation using multichannel whole head, high density functional near-infrared spectroscopy (fNIRS) and predicted working memory load level from the fNIRS data by combining multivariate lasso regression and cross-validation. This allowed us to predict variations in working memory load in a continuous time-resolved manner with mean Pearson correlations between induced and predicted working memory load over 15 participants of 0.61 [standard error (SE) 0.04] and a maximum of 0.8. Restricting the analysis to prefrontal sensors placed over the forehead reduced the mean correlation to 0.38 (SE 0.04), indicating additional information gained through whole head coverage. Moreover, working memory load predictions derived from peripheral heart rate parameters achieved much lower correlations (mean 0.21, SE 0.1). Importantly, whole head fNIRS sampling revealed increasing brain activation in bilateral inferior frontal and bilateral temporo-occipital brain areas with increasing working memory load levels suggesting that these areas are specifically involved in workload-related processing.

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

PubMed

Zhong, Jimmy Y; Moffat, Scott D

2016-01-01

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

Final Scientific/Technical Report for "Enabling Exascale Hardware and Software Design through Scalable System Virtualization"

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

Dinda, Peter August

2015-03-17

This report describes the activities, findings, and products of the Northwestern University component of the "Enabling Exascale Hardware and Software Design through Scalable System Virtualization" project. The purpose of this project has been to extend the state of the art of systems software for high-end computing (HEC) platforms, and to use systems software to better enable the evaluation of potential future HEC platforms, for example exascale platforms. Such platforms, and their systems software, have the goal of providing scientific computation at new scales, thus enabling new research in the physical sciences and engineering. Over time, the innovations in systems softwaremore » for such platforms also become applicable to more widely used computing clusters, data centers, and clouds. This was a five-institution project, centered on the Palacios virtual machine monitor (VMM) systems software, a project begun at Northwestern, and originally developed in a previous collaboration between Northwestern University and the University of New Mexico. In this project, Northwestern (including via our subcontract to the University of Pittsburgh) contributed to the continued development of Palacios, along with other team members. We took the leadership role in (1) continued extension of support for emerging Intel and AMD hardware, (2) integration and performance enhancement of overlay networking, (3) connectivity with architectural simulation, (4) binary translation, and (5) support for modern Non-Uniform Memory Access (NUMA) hosts and guests. We also took a supporting role in support for specialized hardware for I/O virtualization, profiling, configurability, and integration with configuration tools. The efforts we led (1-5) were largely successful and executed as expected, with code and papers resulting from them. The project demonstrated the feasibility of a virtualization layer for HEC computing, similar to such layers for cloud or datacenter computing. For effort (3), although a prototype connecting Palacios with the GEM5 architectural simulator was demonstrated, our conclusion was that such a platform was less useful for design space exploration than anticipated due to inherent complexity of the connection between the instruction set architecture level and the microarchitectural level. For effort (4), we found that a code injection approach proved to be more fruitful. The results of our efforts are publicly available in the open source Palacios codebase and published papers, all of which are available from the project web site, v3vee.org. Palacios is currently one of the two codebases (the other being Sandia’s Kitten lightweight kernel) that underlies the node operating system for the DOE Hobbes Project, one of two projects tasked with building a systems software prototype for the national exascale computing effort.« less

PROspective MEmory Training to improve HEart failUre Self-care (PROMETHEUS): study protocol for a randomised controlled trial.

PubMed

Cameron, Jan; Rendell, Peter G; Ski, Chantal F; Kure, Christina E; McLennan, Skye N; Rose, Nathan S; Prior, David L; Thompson, David R

2015-04-29

Cognitive impairment is seen in up to three quarters of heart failure (HF) patients and has a significant negative impact on patients' health outcomes. Prospective memory, which is defined as memory to carry out future intentions, is important for functional independence in older adults and involves application of multiple cognitive processes that are often impaired in HF patients. The objective of this study is to examine the effects of prospective memory training on patients' engagement in HF self-care and health outcomes, carer strain and quality of life. The proposed study is a randomised, controlled trial in which 200 patients diagnosed with HF, and their carers will be recruited from 3 major hospitals across Melbourne. Eligible patients with HF will be randomised to receive either: 1) The Virtual Week Training Program - a computerised prospective memory (PM) training program (intervention) or 2) non-adaptive computer-based word puzzles (active control). HF patients' baseline cognitive function will be compared to a healthy control group (n = 60) living independently in the community. Patients will undergo a comprehensive assessment of PM, neuropsychological functioning, self-care, physical, and emotional functioning. Assessments will take place at baseline, 4 weeks and 12 months following intervention. Carers will complete measures assessing quality of life, strain, perceived control in the management of the patients' HF symptoms, and ratings of the patients' level of engagement in HF self-care behaviours. If the Virtual Week Training Program is effective in improving: 1) prospective memory; 2) self-care behaviours, and 3) wellbeing in HF patients, this study will enhance our understanding of impaired cognitive processes in HF and potentially is a mechanism to reduce healthcare costs. Australian New Zealand Clinical Trials Registry #366376; 27 May 2014. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=366376&isClinicalTrial=False .

Impact of Spatial and Verbal Short-Term Memory Load on Auditory Spatial Attention Gradients.

PubMed

Golob, Edward J; Winston, Jenna; Mock, Jeffrey R

2017-01-01

Short-term memory load can impair attentional control, but prior work shows that the extent of the effect ranges from being very general to very specific. One factor for the mixed results may be reliance on point estimates of memory load effects on attention. Here we used auditory attention gradients as an analog measure to map-out the impact of short-term memory load over space. Verbal or spatial information was maintained during an auditory spatial attention task and compared to no-load. Stimuli were presented from five virtual locations in the frontal azimuth plane, and subjects focused on the midline. Reaction times progressively increased for lateral stimuli, indicating an attention gradient. Spatial load further slowed responses at lateral locations, particularly in the left hemispace, but had little effect at midline. Verbal memory load had no (Experiment 1), or a minimal (Experiment 2) influence on reaction times. Spatial and verbal load increased switch costs between memory encoding and attention tasks relative to the no load condition. The findings show that short-term memory influences the distribution of auditory attention over space; and that the specific pattern depends on the type of information in short-term memory.

Impact of Spatial and Verbal Short-Term Memory Load on Auditory Spatial Attention Gradients

PubMed Central

Golob, Edward J.; Winston, Jenna; Mock, Jeffrey R.

2017-01-01

Short-term memory load can impair attentional control, but prior work shows that the extent of the effect ranges from being very general to very specific. One factor for the mixed results may be reliance on point estimates of memory load effects on attention. Here we used auditory attention gradients as an analog measure to map-out the impact of short-term memory load over space. Verbal or spatial information was maintained during an auditory spatial attention task and compared to no-load. Stimuli were presented from five virtual locations in the frontal azimuth plane, and subjects focused on the midline. Reaction times progressively increased for lateral stimuli, indicating an attention gradient. Spatial load further slowed responses at lateral locations, particularly in the left hemispace, but had little effect at midline. Verbal memory load had no (Experiment 1), or a minimal (Experiment 2) influence on reaction times. Spatial and verbal load increased switch costs between memory encoding and attention tasks relative to the no load condition. The findings show that short-term memory influences the distribution of auditory attention over space; and that the specific pattern depends on the type of information in short-term memory. PMID:29218024

Cognitive control of familiarity: directed forgetting reduces proactive interference in working memory.

PubMed

Festini, Sara B; Reuter-Lorenz, Patricia A

2014-03-01

Proactive interference (PI) occurs when previously learned information interferes with new learning. In a working memory task, PI induces longer response times and more errors to recent negative probes than to new probes, presumably because the recent probe's familiarity invites a "yes" response. Warnings, longer intertrial intervals, and the increased contextual salience of the probes can reduce but not eliminate PI, suggesting that cognitive control over PI is limited. Here we tested whether control exerted in the form of intentional forgetting performed during working memory can reduce the magnitude of PI. In two experiments, participants performed a working memory task with directed-forgetting instructions and the occasional presentation of recent probes. Surprise long-term memory testing indicated better memory for to-be-remembered than for to-be-forgotten items, documenting the classic directed-forgetting effect. Critically, in working memory, PI was virtually eliminated for recent probes from prior to-be-forgotten lists, as compared to recent probes from prior to-be-remembered lists. Thus cognitive control, when executed via directed forgetting, can reduce the adverse and otherwise persistent interference from familiarity, an effect that we attribute to attenuated memory representations of the to-be-forgotten items.

Spatial memory enhances the evacuation efficiency of virtual pedestrians under poor visibility condition

NASA Astrophysics Data System (ADS)

Ma, Yi; Lee, Eric Wai Ming; Shi, Meng; Kwok Kit Yuen, Richard

2018-03-01

Spatial memory is a critical navigation support tool for disoriented evacuees during evacuation under adverse environmental conditions such as dark or smoky conditions. Owing to the complexity of memory, it is challenging to understand the effect of spatial memory on pedestrian evacuation quantitatively. In this study, we propose a simple method to quantitatively represent the evacueeʼs spatial memory about the emergency exit, model the evacuation of pedestrians under the guidance of the spatial memory, and investigate the effect of the evacueeʼs spatial memory on the evacuation from theoretical and physical perspectives. The result shows that (i) a good memory can significantly assist the evacuation of pedestrians under poor visibility conditions, and the evacuation can always succeed when the degree of the memory exceeds a threshold (\\varphi > 0.5); (ii) the effect of memory is superior to that of “follow-the-crowd” under the same environmental conditions; (iii) in the case of multiple exits, the difference in the degree of the memory between evacuees has a significant effect (the greater the difference, the faster the evacuation) for the evacuation under poor visibility conditions. Our study provides a new quantitative insight into the effect of spatial memory on crowd evacuation under poor visibility conditions. Project supported by the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant No. 11203615).

An imperialist competitive algorithm for virtual machine placement in cloud computing

NASA Astrophysics Data System (ADS)

Jamali, Shahram; Malektaji, Sepideh; Analoui, Morteza

2017-05-01

Cloud computing, the recently emerged revolution in IT industry, is empowered by virtualisation technology. In this paradigm, the user's applications run over some virtual machines (VMs). The process of selecting proper physical machines to host these virtual machines is called virtual machine placement. It plays an important role on resource utilisation and power efficiency of cloud computing environment. In this paper, we propose an imperialist competitive-based algorithm for the virtual machine placement problem called ICA-VMPLC. The base optimisation algorithm is chosen to be ICA because of its ease in neighbourhood movement, good convergence rate and suitable terminology. The proposed algorithm investigates search space in a unique manner to efficiently obtain optimal placement solution that simultaneously minimises power consumption and total resource wastage. Its final solution performance is compared with several existing methods such as grouping genetic and ant colony-based algorithms as well as bin packing heuristic. The simulation results show that the proposed method is superior to other tested algorithms in terms of power consumption, resource wastage, CPU usage efficiency and memory usage efficiency.

Developing infrared array controller with software real time operating system

NASA Astrophysics Data System (ADS)

Sako, Shigeyuki; Miyata, Takashi; Nakamura, Tomohiko; Motohara, Kentaro; Uchimoto, Yuka Katsuno; Onaka, Takashi; Kataza, Hirokazu

2008-07-01

Real-time capabilities are required for a controller of a large format array to reduce a dead-time attributed by readout and data transfer. The real-time processing has been achieved by dedicated processors including DSP, CPLD, and FPGA devices. However, the dedicated processors have problems with memory resources, inflexibility, and high cost. Meanwhile, a recent PC has sufficient resources of CPUs and memories to control the infrared array and to process a large amount of frame data in real-time. In this study, we have developed an infrared array controller with a software real-time operating system (RTOS) instead of the dedicated processors. A Linux PC equipped with a RTAI extension and a dual-core CPU is used as a main computer, and one of the CPU cores is allocated to the real-time processing. A digital I/O board with DMA functions is used for an I/O interface. The signal-processing cores are integrated in the OS kernel as a real-time driver module, which is composed of two virtual devices of the clock processor and the frame processor tasks. The array controller with the RTOS realizes complicated operations easily, flexibly, and at a low cost.

Almeria spatial memory recognition test (ASMRT): Gender differences emerged in a new passive spatial task.

PubMed

Tascón, Laura; García-Moreno, Luis Miguel; Cimadevilla, Jose Manuel

2017-06-09

Many different human spatial memory tasks were developed in the last two decades. Virtual reality based tasks make possible developing different scenarios and situations to assess spatial orientation but sometimes these tasks are complex for specific populations like children and older-adults. A new spatial task with a very limited technological requirement was developed in this study. It demanded the use of spatial memory for an accurate solution. It also proved to be sensitive to gender differences, with men outperforming women under high specific difficulty levels. Thanks to its simplicity it could be applied as a screening test and is easy to combine with EEG and fMRI studies. Copyright © 2017 Elsevier B.V. All rights reserved.

High density associative memory

NASA Technical Reports Server (NTRS)

Moopenn, Alexander W. (Inventor); Thakoor, Anilkumar P. (Inventor); Daud, Taher (Inventor); Lambe, John J. (Inventor)

1989-01-01

A multi-layered, thin-film, digital memory having associative recall. There is a first memory matrix and a second memory matrix. Each memory matrix comprises, a first layer comprising a plurality of electrically separated row conductors; a second layer comprising a plurality of electrically separated column conductors intersecting but electrically separated from the row conductors; and, a plurality of resistance elements electrically connected between the row condutors and the column conductors at respective intersections of the row conductors and the column conductors, each resistance element comprising, in series, a first resistor of sufficiently high ohmage to conduct a sensible element current therethrough with virtually no heat-generating power consumption when a low voltage as employed in thin-film applications is applied thereacross and a second resistor of sufficiently high ohmage to conduct no sensible current therethrough when a low voltage as employed in thin-film applications is applied thereacross, the second resistor having the quality of breaking down to create a short therethrough upon the application of a breakdown level voltage across the first and second resistors.

Can false memory for critical lures occur without conscious awareness of list words?

PubMed

Sadler, Daniel D; Sodmont, Sharon M; Keefer, Lucas A

2018-02-01

We examined whether the DRM false memory effect can occur when list words are presented below the perceptual identification threshold. In four experiments, subjects showed robust veridical memory for studied words and false memory for critical lures when masked list words were presented at exposure durations of 43 ms per word. Shortening the exposure duration to 29 ms virtually eliminated veridical recognition of studied words and completely eliminated false recognition of critical lures. Subjective visibility ratings in Experiments 3a and 3b support the assumption that words presented at 29 ms were subliminal for most participants, but were occasionally experienced with partial awareness by participants with higher perceptual awareness. Our results indicate that a false memory effect does not occur in the absence of conscious awareness of list words, but it does occur when word stimuli are presented at an intermediate level of visibility. Copyright © 2017 Elsevier Inc. All rights reserved.

An event map of memory space in the hippocampus

PubMed Central

Deuker, Lorena; Bellmund, Jacob LS; Navarro Schröder, Tobias; Doeller, Christian F

2016-01-01

The hippocampus has long been implicated in both episodic and spatial memory, however these mnemonic functions have been traditionally investigated in separate research strands. Theoretical accounts and rodent data suggest a common mechanism for spatial and episodic memory in the hippocampus by providing an abstract and flexible representation of the external world. Here, we monitor the de novo formation of such a representation of space and time in humans using fMRI. After learning spatio-temporal trajectories in a large-scale virtual city, subject-specific neural similarity in the hippocampus scaled with the remembered proximity of events in space and time. Crucially, the structure of the entire spatio-temporal network was reflected in neural patterns. Our results provide evidence for a common coding mechanism underlying spatial and temporal aspects of episodic memory in the hippocampus and shed new light on its role in interleaving multiple episodes in a neural event map of memory space. DOI: http://dx.doi.org/10.7554/eLife.16534.001 PMID:27710766

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

PubMed Central

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

2011-01-01

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

Evidence for an Evolutionarily Conserved Memory Coding Scheme in the Mammalian Hippocampus

PubMed Central

Thome, Alexander; Lisanby, Sarah H.; McNaughton, Bruce L.

2017-01-01

Decades of research identify the hippocampal formation as central to memory storage and recall. Events are stored via distributed population codes, the parameters of which (e.g., sparsity and overlap) determine both storage capacity and fidelity. However, it remains unclear whether the parameters governing information storage are similar between species. Because episodic memories are rooted in the space in which they are experienced, the hippocampal response to navigation is often used as a proxy to study memory. Critically, recent studies in rodents that mimic the conditions typical of navigation studies in humans and nonhuman primates (i.e., virtual reality) show that reduced sensory input alters hippocampal representations of space. The goal of this study was to quantify this effect and determine whether there are commonalities in information storage across species. Using functional molecular imaging, we observe that navigation in virtual environments elicits activity in fewer CA1 neurons relative to real-world conditions. Conversely, comparable neuronal activity is observed in hippocampus region CA3 and the dentate gyrus under both conditions. Surprisingly, we also find evidence that the absolute number of neurons used to represent an experience is relatively stable between nonhuman primates and rodents. We propose that this convergence reflects an optimal ensemble size for episodic memories. SIGNIFICANCE STATEMENT One primary factor constraining memory capacity is the sparsity of the engram, the proportion of neurons that encode a single experience. Investigating sparsity in humans is hampered by the lack of single-cell resolution and differences in behavioral protocols. Sparsity can be quantified in freely moving rodents, but extrapolating these data to humans assumes that information storage is comparable across species and is robust to restraint-induced reduction in sensory input. Here, we test these assumptions and show that species differences in brain size build memory capacity without altering the structure of the data being stored. Furthermore, sparsity in most of the hippocampus is resilient to reduced sensory information. This information is vital to integrating animal data with human imaging navigation studies. PMID:28174334

A cortical substrate for the long-term memory of saccadic eye movements calibration.

PubMed

Pélisson, Denis; Habchi, Ouazna; Panouillères, Muriel T N; Hernoux, Charles; Farnè, Alessandro

2018-06-19

How movements are continuously adapted to physiological and environmental changes is a fundamental question in systems neuroscience. While many studies have elucidated the mechanisms which underlie short-term sensorimotor adaptation (∼10-30 min), how these motor memories are maintained over longer-term (>3-5 days) -and thanks to which neural systems-is virtually unknown. Here, we examine in healthy human participants whether the temporo-parietal junction (TPJ) is causally involved in the induction and/or the retention of saccadic eye movements' adaptation. Single-pulse transcranial magnetic stimulation (spTMS) was applied while subjects performed a ∼15min size-decrease adaptation task of leftward reactive saccades. A TMS pulse was delivered over the TPJ in the right hemisphere (rTPJ) in each trial either 30, 60, 90 or 120 msec (in 4 separate adaptation sessions) after the saccade onset. In two control groups of subjects, the same adaptation procedure was achieved either alone (No-TMS) or combined with spTMS applied over the vertex (SHAM-TMS). While the timing of spTMS over the rTPJ did not significantly affect the speed and immediate after-effect of adaptation, we found that the amount of adaptation retention measured 10 days later was markedly larger (42%) than in both the No-TMS (21%) and the SHAM-TMS (11%) control groups. These results demonstrate for the first time that the cerebral cortex is causally involved in maintaining long-term oculomotor memories. Copyright © 2018. Published by Elsevier Inc.

ViPAR: a software platform for the Virtual Pooling and Analysis of Research Data.

PubMed

Carter, Kim W; Francis, Richard W; Carter, K W; Francis, R W; Bresnahan, M; Gissler, M; Grønborg, T K; Gross, R; Gunnes, N; Hammond, G; Hornig, M; Hultman, C M; Huttunen, J; Langridge, A; Leonard, H; Newman, S; Parner, E T; Petersson, G; Reichenberg, A; Sandin, S; Schendel, D E; Schalkwyk, L; Sourander, A; Steadman, C; Stoltenberg, C; Suominen, A; Surén, P; Susser, E; Sylvester Vethanayagam, A; Yusof, Z

2016-04-01

Research studies exploring the determinants of disease require sufficient statistical power to detect meaningful effects. Sample size is often increased through centralized pooling of disparately located datasets, though ethical, privacy and data ownership issues can often hamper this process. Methods that facilitate the sharing of research data that are sympathetic with these issues and which allow flexible and detailed statistical analyses are therefore in critical need. We have created a software platform for the Virtual Pooling and Analysis of Research data (ViPAR), which employs free and open source methods to provide researchers with a web-based platform to analyse datasets housed in disparate locations. Database federation permits controlled access to remotely located datasets from a central location. The Secure Shell protocol allows data to be securely exchanged between devices over an insecure network. ViPAR combines these free technologies into a solution that facilitates 'virtual pooling' where data can be temporarily pooled into computer memory and made available for analysis without the need for permanent central storage. Within the ViPAR infrastructure, remote sites manage their own harmonized research dataset in a database hosted at their site, while a central server hosts the data federation component and a secure analysis portal. When an analysis is initiated, requested data are retrieved from each remote site and virtually pooled at the central site. The data are then analysed by statistical software and, on completion, results of the analysis are returned to the user and the virtually pooled data are removed from memory. ViPAR is a secure, flexible and powerful analysis platform built on open source technology that is currently in use by large international consortia, and is made publicly available at [http://bioinformatics.childhealthresearch.org.au/software/vipar/]. © The Author 2015. Published by Oxford University Press on behalf of the International Epidemiological Association.

An IPv6 routing lookup algorithm using weight-balanced tree based on prefix value for virtual router

NASA Astrophysics Data System (ADS)

Chen, Lingjiang; Zhou, Shuguang; Zhang, Qiaoduo; Li, Fenghua

2016-10-01

Virtual router enables the coexistence of different networks on the same physical facility and has lately attracted a great deal of attention from researchers. As the number of IPv6 addresses is rapidly increasing in virtual routers, designing an efficient IPv6 routing lookup algorithm is of great importance. In this paper, we present an IPv6 lookup algorithm called weight-balanced tree (WBT). WBT merges Forwarding Information Bases (FIBs) of virtual routers into one spanning tree, and compresses the space cost. WBT's average time complexity and the worst case time complexity of lookup and update process are both O(logN) and space complexity is O(cN) where N is the size of routing table and c is a constant. Experiments show that WBT helps reduce more than 80% Static Random Access Memory (SRAM) cost in comparison to those separation schemes. WBT also achieves the least average search depth comparing with other homogeneous algorithms.

Human sex differences in solving a virtual navigation problem.

PubMed

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

2016-07-15

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

Eyewitness Memory in Face-to-Face and Immersive Avatar-to-Avatar Contexts.

PubMed

Taylor, Donna A; Dando, Coral J

2018-01-01

Technological advances offer possibilities for innovation in the way eyewitness testimony is elicited. Typically, this occurs face-to-face. We investigated whether a virtual environment, where interviewer and eyewitness communicate as avatars, might confer advantages by attenuating the social and situational demands of a face-to-face interview, releasing more cognitive resources for invoking episodic retrieval mode. In conditions of intentional encoding, eyewitnesses were interviewed 48 h later, either face-to-face or in a virtual environment ( N = 38). Participants in the virtual environment significantly outperformed those interviewed face-to-face on all episodic performance measures - improved correct reporting reduced errors, and increased accuracy. Participants reported finding it easier to admit not remembering event information to the avatar, and finding the avatar easier to talk to. These novel findings, and our pattern of retrieval results indicates the potential of avatar-to-avatar communication in virtual environments, and provide impetus for further research investigating eyewitness cognition in contemporary retrieval contexts.

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.

Sleep Enhances Knowledge of Routes and Regions in Spatial Environments

ERIC Educational Resources Information Center

Noack, Hannes; Schick, Wiebke; Mallot, Hanspeter; Born, Jan

2017-01-01

Sleep is thought to preferentially consolidate hippocampus-dependent memory, and as such, spatial navigation. Here, we investigated the effects of sleep on route knowledge and explicit and implicit semantic regions in a virtual environment. Sleep, compared with wakefulness, improved route knowledge and also enhanced awareness of the semantic…

Unpacking Intuition

PubMed Central

Seligman, Martin E.P.; Kahana, Michael

2009-01-01

Can intuition be taught? The way in which faces are recognized, the structure of natural classes, and the architecture of intuition may all be instances of the same process. The conjecture that intuition is a species of recognition memory implies that human intuitive decision making can be enormously enhanced by virtual simulation. PMID:20300491

A Journey through Public History on the Web.

ERIC Educational Resources Information Center

Borg, Brent

2002-01-01

Provides an annotated list of Web sites that include, but not limited to, the American Family Immigration History Center, Harry S. Truman Presidential Museum and Library, National Council for Public History, National Park Service, U.S. Holocaust Memorial Museum, and the Women of the West Virtual Museum. (CMK)

From Real Challenges to Virtual Reality: Realizing Your Collection through Digital Partnership

ERIC Educational Resources Information Center

Johnson, Jennifer; Mandity, Edward

2010-01-01

In fall 2008, a collaborative partnership was formed between the libraries of two Indiana universities--Marian College's (now Marian University) Mother Theresa Hackelmeier Memorial Library, and the University Library at Indiana University-Purdue University Indianapolis (IUPUI). The authors discuss the digital nature of this collaboration, which…

Sleep enhances exposure therapy.

PubMed

Kleim, B; Wilhelm, F H; Temp, L; Margraf, J; Wiederhold, B K; Rasch, B

2014-05-01

Sleep benefits memory consolidation. Here, we tested the beneficial effect of sleep on memory consolidation following exposure psychotherapy of phobic anxiety. A total of 40 individuals afflicted with spider phobia according to DSM-IV underwent a one-session virtual reality exposure treatment and either slept for 90 min or stayed awake afterwards. Sleep following exposure therapy compared with wakefulness led to better reductions in self-reported fear (p = 0.045, d = 0.47) and catastrophic spider-related cognitions (p = 0.026, d = 0.53) during approaching a live spider, both tested after 1 week. Both reductions were associated with greater percentages of stage 2 sleep. Our results indicate that sleep following successful psychotherapy, such as exposure therapy, improves therapeutic effectiveness, possibly by strengthening new non-fearful memory traces established during therapy. These findings offer an important non-invasive alternative to recent attempts to facilitate therapeutic memory extinction and consolidation processes with pharmacological or behavioral interventions.

Optimization of memory use of fragment extension-based protein-ligand docking with an original fast minimum cost flow algorithm.

PubMed

Yanagisawa, Keisuke; Komine, Shunta; Kubota, Rikuto; Ohue, Masahito; Akiyama, Yutaka

2018-06-01

The need to accelerate large-scale protein-ligand docking in virtual screening against a huge compound database led researchers to propose a strategy that entails memorizing the evaluation result of the partial structure of a compound and reusing it to evaluate other compounds. However, the previous method required frequent disk accesses, resulting in insufficient acceleration. Thus, more efficient memory usage can be expected to lead to further acceleration, and optimal memory usage could be achieved by solving the minimum cost flow problem. In this research, we propose a fast algorithm for the minimum cost flow problem utilizing the characteristics of the graph generated for this problem as constraints. The proposed algorithm, which optimized memory usage, was approximately seven times faster compared to existing minimum cost flow algorithms. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Are visual cues helpful for virtual spatial navigation and spatial memory in patients with mild cognitive impairment or Alzheimer's disease?

PubMed

Cogné, Mélanie; Auriacombe, Sophie; Vasa, Louise; Tison, François; Klinger, Evelyne; Sauzéon, Hélène; Joseph, Pierre-Alain; N Kaoua, Bernard

2018-05-01

To evaluate whether visual cues are helpful for virtual spatial navigation and memory in Alzheimer's disease (AD) and patients with mild cognitive impairment (MCI). 20 patients with AD, 18 patients with MCI and 20 age-matched healthy controls (HC) were included. Participants had to actively reproduce a path that included 5 intersections with one landmark at each intersection that they had seen previously during a learning phase. Three cueing conditions for navigation were offered: salient landmarks, directional arrows and a map. A path without additional visual stimuli served as control condition. Navigation time and number of trajectory mistakes were recorded. With the presence of directional arrows, no significant difference was found between groups concerning the number of trajectory mistakes and navigation time. The number of trajectory mistakes did not differ significantly between patients with AD and patients with MCI on the path with arrows, the path with salient landmarks and the path with a map. There were significant correlations between the number of trajectory mistakes under the arrow condition and executive tests, and between the number of trajectory mistakes under the salient landmark condition and memory tests. Visual cueing such as directional arrows and salient landmarks appears helpful for spatial navigation and memory tasks in patients with AD and patients with MCI. This study opens new research avenues for neuro-rehabilitation, such as the use of augmented reality in real-life settings to support the navigational capabilities of patients with MCI and patients with AD. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A Virtual Week study of prospective memory function in autism spectrum disorders.

PubMed

Henry, Julie D; Terrett, Gill; Altgassen, Mareike; Raponi-Saunders, Sandra; Ballhausen, Nicola; Schnitzspahn, Katharina M; Rendell, Peter G

2014-11-01

Prospective memory (PM) refers to the implementation of delayed intentions, a cognitive ability that plays a critical role in daily life because of its involvement in goal-directed behavior and consequently the development and maintenance of independence. Emerging evidence indicates that PM may be disrupted in autism spectrum disorders (ASDs), potentially contributing to the functional difficulties that characterize this group. However, the degree, nature, and specificity of ASD-related impairment remains poorly understood. In the current study, children between 8 and 12 years of age who were diagnosed with ASDs (n=30) were compared with typically developing children (n=30) on a child-appropriate version of the Virtual Week board game. This measure provides an opportunity to investigate the different sorts of PM failures that occur. The ASD group showed significant PM impairment on measures of time-based (but not event-based) prospective remembering. However, only a subtle difference emerged between regular and irregular PM tasks, and group differences were consistent across these tasks. Because regular and irregular tasks differentially load retrospective memory, these data imply that the PM difficulties seen in ASDs may primarily reflect a monitoring deficit and not an encoding and memory storage deficit. PM performance was poorer under conditions of high ongoing task absorption, but the magnitude of this effect did not vary as a function of group. In both groups, time-based (but not event-based) PM difficulties were associated with functional outcomes in daily life, but only an inconsistent association with executive control emerged. Copyright © 2014 Elsevier Inc. All rights reserved.

Virtual Network Configuration Management System for Data Center Operations and Management

NASA Astrophysics Data System (ADS)

Okita, Hideki; Yoshizawa, Masahiro; Uehara, Keitaro; Mizuno, Kazuhiko; Tarui, Toshiaki; Naono, Ken

Virtualization technologies are widely deployed in data centers to improve system utilization. However, they increase the workload for operators, who have to manage the structure of virtual networks in data centers. A virtual-network management system which automates the integration of the configurations of the virtual networks is provided. The proposed system collects the configurations from server virtualization platforms and VLAN-supported switches, and integrates these configurations according to a newly developed XML-based management information model for virtual-network configurations. Preliminary evaluations show that the proposed system helps operators by reducing the time to acquire the configurations from devices and correct the inconsistency of operators' configuration management database by about 40 percent. Further, they also show that the proposed system has excellent scalability; the system takes less than 20 minutes to acquire the virtual-network configurations from a large scale network that includes 300 virtual machines. These results imply that the proposed system is effective for improving the configuration management process for virtual networks in data centers.

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

PubMed Central

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

2016-01-01

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

Development and Feasibility of a Virtual Reality Task for the Cognitive Assessment of Older Adults: The ECO-VR.

PubMed

Oliveira, Camila R; Lopes Filho, Brandel José P; Sugarman, Michael A; Esteves, Cristiane S; Lima, Margarida Maria B M P; Moret-Tatay, Carmen; Irigaray, Tatiana Q; Argimon, Irani Iracema L

2016-12-13

Cognitive assessment with virtual reality (VR) may have superior ecological validity for older adults compared to traditional pencil-and-paper cognitive assessment. However, few studies have reported the development of VR tasks. The aim of this study was to present the development, feasibility, content validity, and preliminary evidence of construct validity of an ecological task of cognitive assessment for older adults in VR (ECO-VR). The tasks were prepared based on theoretical and clinical backgrounds. We had 29 non-expert judges identify virtual visual stimuli and three-dimensional scenarios, and five expert judges assisted with content analysis and developing instructions. Finally, six older persons participated in three pilot studies and thirty older persons participated in the preliminary study to identify construct validity evidence. Data were analyzed by descriptive statistics and partial correlation. Target stimuli and three-dimensional scenarios were judged adequate and the content analysis demonstrated that ECO-VR evaluates temporo-spatial orientation, memory, language and executive functioning. We made significant changes to the instructions after the pilot studies to increase comprehensibility and reduce the completion time. The total score of ECO-VR was positively correlated mainly with performance in executive function (r = .172, p < .05) and memory tests (r = .488, p ≤ .01). The ECO-VR demonstrated feasibility for cognitive assessment in older adults, as well as content and construct validity evidences.

Predicting Remembering: Judgments of Prospective Memory After Traumatic Brain Injury.

PubMed

O'Brien, Katy H; Kennedy, Mary R T

2018-06-19

Adults with traumatic brain injuries (TBIs) often struggle with prospective memory (PM), the ability to remember to complete tasks in the future, such as taking medicines on a schedule. Metamemory judgments (or how well we think we will do at remembering) are linked to strategy use and are critical for managing demands of daily living. The current project used an Internet-based virtual reality tool to assess metamemory judgments of PM following TBI. Eighteen adults with moderate to severe TBI and 20 healthy controls (HCs) played Tying the String, a virtual reality game with PM items embedded across the course of a virtual work week. Participants studied PM items and made two judgments of learning about the likelihood of recognizing the CUE, that is, when the task should be done, and of recalling the TASK, that is, what needed to be done. Participants with TBI adjusted their metamemory expectations downward, but not enough to account for poorer recall performance. Absolute difference scores of metamemory accuracy showed that healthy adults were underconfident across PM components, whereas adults with TBI were markedly overconfident about their ability to recall TASKs. Adults with TBI appear to have a general knowledge that PM tasks will be difficult but are poor monitors of actual levels of success. Because metamemory monitoring is linked to strategy use, future work should examine using this link to direct PM intervention approaches.

Generative Recurrent Networks for De Novo Drug Design.

PubMed

Gupta, Anvita; Müller, Alex T; Huisman, Berend J H; Fuchs, Jens A; Schneider, Petra; Schneider, Gisbert

2018-01-01

Generative artificial intelligence models present a fresh approach to chemogenomics and de novo drug design, as they provide researchers with the ability to narrow down their search of the chemical space and focus on regions of interest. We present a method for molecular de novo design that utilizes generative recurrent neural networks (RNN) containing long short-term memory (LSTM) cells. This computational model captured the syntax of molecular representation in terms of SMILES strings with close to perfect accuracy. The learned pattern probabilities can be used for de novo SMILES generation. This molecular design concept eliminates the need for virtual compound library enumeration. By employing transfer learning, we fine-tuned the RNN's predictions for specific molecular targets. This approach enables virtual compound design without requiring secondary or external activity prediction, which could introduce error or unwanted bias. The results obtained advocate this generative RNN-LSTM system for high-impact use cases, such as low-data drug discovery, fragment based molecular design, and hit-to-lead optimization for diverse drug targets. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Recollection-dependent memory for event duration in large-scale spatial navigation

PubMed Central

Barense, Morgan D.

2017-01-01

Time and space represent two key aspects of episodic memories, forming the spatiotemporal context of events in a sequence. Little is known, however, about how temporal information, such as the duration and the order of particular events, are encoded into memory, and if it matters whether the memory representation is based on recollection or familiarity. To investigate this issue, we used a real world virtual reality navigation paradigm where periods of navigation were interspersed with pauses of different durations. Crucially, participants were able to reliably distinguish the durations of events that were subjectively “reexperienced” (i.e., recollected), but not of those that were familiar. This effect was not found in temporal order (ordinal) judgments. We also show that the active experience of the passage of time (holding down a key while waiting) moderately enhanced duration memory accuracy. Memory for event duration, therefore, appears to rely on the hippocampally supported ability to recollect or reexperience an event enabling the reinstatement of both its duration and its spatial context, to distinguish it from other events in a sequence. In contrast, ordinal memory appears to rely on familiarity and recollection to a similar extent. PMID:28202714

Multi-channel spatialization systems for audio signals

NASA Technical Reports Server (NTRS)

Begault, Durand R. (Inventor)

1993-01-01

Synthetic head related transfer functions (HRTF's) for imposing reprogrammable spatial cues to a plurality of audio input signals included, for example, in multiple narrow-band audio communications signals received simultaneously are generated and stored in interchangeable programmable read only memories (PROM's) which store both head related transfer function impulse response data and source positional information for a plurality of desired virtual source locations. The analog inputs of the audio signals are filtered and converted to digital signals from which synthetic head related transfer functions are generated in the form of linear phase finite impulse response filters. The outputs of the impulse response filters are subsequently reconverted to analog signals, filtered, mixed, and fed to a pair of headphones.

Multi-channel spatialization system for audio signals

NASA Technical Reports Server (NTRS)

Begault, Durand R. (Inventor)

1995-01-01

Synthetic head related transfer functions (HRTF's) for imposing reprogramable spatial cues to a plurality of audio input signals included, for example, in multiple narrow-band audio communications signals received simultaneously are generated and stored in interchangeable programmable read only memories (PROM's) which store both head related transfer function impulse response data and source positional information for a plurality of desired virtual source locations. The analog inputs of the audio signals are filtered and converted to digital signals from which synthetic head related transfer functions are generated in the form of linear phase finite impulse response filters. The outputs of the impulse response filters are subsequently reconverted to analog signals, filtered, mixed and fed to a pair of headphones.

The Impact of Ocean Observations in Seasonal Climate Prediction

NASA Technical Reports Server (NTRS)

Rienecker, Michele; Keppenne, Christian; Kovach, Robin; Marshak, Jelena

2010-01-01

The ocean provides the most significant memory for the climate system. Hence, a critical element in climate forecasting with coupled models is the initialization of the ocean with states from an ocean data assimilation system. Remotely-sensed ocean surface fields (e.g., sea surface topography, SST, winds) are now available for extensive periods and have been used to constrain ocean models to provide a record of climate variations. Since the ocean is virtually opaque to electromagnetic radiation, the assimilation of these satellite data is essential to extracting the maximum information content. More recently, the Argo drifters have provided unprecedented sampling of the subsurface temperature and salinity. Although the duration of this observation set has been too short to provide solid statistical evidence of its impact, there are indications that Argo improves the forecast skill of coupled systems. This presentation will address the impact these different observations have had on seasonal climate predictions with the GMAO's coupled model.

Resilient and Robust High Performance Computing Platforms for Scientific Computing Integrity

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

Jin, Yier

As technology advances, computer systems are subject to increasingly sophisticated cyber-attacks that compromise both their security and integrity. High performance computing platforms used in commercial and scientific applications involving sensitive, or even classified data, are frequently targeted by powerful adversaries. This situation is made worse by a lack of fundamental security solutions that both perform efficiently and are effective at preventing threats. Current security solutions fail to address the threat landscape and ensure the integrity of sensitive data. As challenges rise, both private and public sectors will require robust technologies to protect its computing infrastructure. The research outcomes from thismore » project try to address all these challenges. For example, we present LAZARUS, a novel technique to harden kernel Address Space Layout Randomization (KASLR) against paging-based side-channel attacks. In particular, our scheme allows for fine-grained protection of the virtual memory mappings that implement the randomization. We demonstrate the effectiveness of our approach by hardening a recent Linux kernel with LAZARUS, mitigating all of the previously presented side-channel attacks on KASLR. Our extensive evaluation shows that LAZARUS incurs only 0.943% overhead for standard benchmarks, and is therefore highly practical. We also introduced HA2lloc, a hardware-assisted allocator that is capable of leveraging an extended memory management unit to detect memory errors in the heap. We also perform testing using HA2lloc in a simulation environment and find that the approach is capable of preventing common memory vulnerabilities.« less

Deficits in episodic memory and mental time travel in patients with post-traumatic stress disorder.

PubMed

Zlomuzica, Armin; Woud, Marcella L; Machulska, Alla; Kleimt, Katharina; Dietrich, Lisa; Wolf, Oliver T; Assion, Hans-Joerg; Huston, Joseph P; De Souza Silva, Maria A; Dere, Ekrem; Margraf, Jürgen

2018-04-20

Post-traumatic stress disorder (PTSD) is characterized by impairments in mnestic functions, especially in the domain of episodic memory. These alterations might affect different aspects of episodic memory functioning. Here we tested PTSD patients and healthy controls (matched for age, sex and education) in a newly developed virtual reality episodic memory test (VR-EMT), a test for mental time travel, episodic future thinking, and prospective memory (M3xT). In a cross-validation experiment, their performance was further evaluated in the Rivermead Behavioral Memory Test (RBMT). PTSD patients demonstrated impairments in episodic memory formation and mental time travel and showed difficulties in utilizing information from episodic memory to solve problems. Diminished attention and concentration in PTSD did not account for performance deficits in these tasks but higher levels of negative arousal were found in PTSD patients. Furthermore, performance in the VR-EMT and RBMT in PTSD patients correlated negatively with self-reported measures of stress and depression. Our results suggest that deficits in episodic memory formation and mental time travel in PTSD lead to difficulties in utilizing the content of episodic memories for solving problems in the present or to plan future behavior. Clinical implications of these findings and suggestions for cognitive-behavioral treatment of PTSD are discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

Owning an overweight or underweight body: distinguishing the physical, experienced and virtual body.

PubMed

Piryankova, Ivelina V; Wong, Hong Yu; Linkenauger, Sally A; Stinson, Catherine; Longo, Matthew R; Bülthoff, Heinrich H; Mohler, Betty J

2014-01-01

Our bodies are the most intimately familiar objects we encounter in our perceptual environment. Virtual reality provides a unique method to allow us to experience having a very different body from our own, thereby providing a valuable method to explore the plasticity of body representation. In this paper, we show that women can experience ownership over a whole virtual body that is considerably smaller or larger than their physical body. In order to gain a better understanding of the mechanisms underlying body ownership, we use an embodiment questionnaire, and introduce two new behavioral response measures: an affordance estimation task (indirect measure of body size) and a body size estimation task (direct measure of body size). Interestingly, after viewing the virtual body from first person perspective, both the affordance and the body size estimation tasks indicate a change in the perception of the size of the participant's experienced body. The change is biased by the size of the virtual body (overweight or underweight). Another novel aspect of our study is that we distinguish between the physical, experienced and virtual bodies, by asking participants to provide affordance and body size estimations for each of the three bodies separately. This methodological point is important for virtual reality experiments investigating body ownership of a virtual body, because it offers a better understanding of which cues (e.g. visual, proprioceptive, memory, or a combination thereof) influence body perception, and whether the impact of these cues can vary between different setups.

Owning an Overweight or Underweight Body: Distinguishing the Physical, Experienced and Virtual Body

PubMed Central

Piryankova, Ivelina V.; Wong, Hong Yu; Linkenauger, Sally A.; Stinson, Catherine; Longo, Matthew R.; Bülthoff, Heinrich H.; Mohler, Betty J.

2014-01-01

Our bodies are the most intimately familiar objects we encounter in our perceptual environment. Virtual reality provides a unique method to allow us to experience having a very different body from our own, thereby providing a valuable method to explore the plasticity of body representation. In this paper, we show that women can experience ownership over a whole virtual body that is considerably smaller or larger than their physical body. In order to gain a better understanding of the mechanisms underlying body ownership, we use an embodiment questionnaire, and introduce two new behavioral response measures: an affordance estimation task (indirect measure of body size) and a body size estimation task (direct measure of body size). Interestingly, after viewing the virtual body from first person perspective, both the affordance and the body size estimation tasks indicate a change in the perception of the size of the participant's experienced body. The change is biased by the size of the virtual body (overweight or underweight). Another novel aspect of our study is that we distinguish between the physical, experienced and virtual bodies, by asking participants to provide affordance and body size estimations for each of the three bodies separately. This methodological point is important for virtual reality experiments investigating body ownership of a virtual body, because it offers a better understanding of which cues (e.g. visual, proprioceptive, memory, or a combination thereof) influence body perception, and whether the impact of these cues can vary between different setups. PMID:25083784

Navigational strategies underlying phototaxis in larval zebrafish.

PubMed

Chen, Xiuye; Engert, Florian

2014-01-01

Understanding how the brain transforms sensory input into complex behavior is a fundamental question in systems neuroscience. Using larval zebrafish, we study the temporal component of phototaxis, which is defined as orientation decisions based on comparisons of light intensity at successive moments in time. We developed a novel "Virtual Circle" assay where whole-field illumination is abruptly turned off when the fish swims out of a virtually defined circular border, and turned on again when it returns into the circle. The animal receives no direct spatial cues and experiences only whole-field temporal light changes. Remarkably, the fish spends most of its time within the invisible virtual border. Behavioral analyses of swim bouts in relation to light transitions were used to develop four discrete temporal algorithms that transform the binary visual input (uniform light/uniform darkness) into the observed spatial behavior. In these algorithms, the turning angle is dependent on the behavioral history immediately preceding individual turning events. Computer simulations show that the algorithms recapture most of the swim statistics of real fish. We discovered that turning properties in larval zebrafish are distinctly modulated by temporal step functions in light intensity in combination with the specific motor history preceding these turns. Several aspects of the behavior suggest memory usage of up to 10 swim bouts (~10 sec). Thus, we show that a complex behavior like spatial navigation can emerge from a small number of relatively simple behavioral algorithms.

CD4+ virtual memory: Antigen-inexperienced T cells reside in the naïve, regulatory, and memory T cell compartments at similar frequencies, implications for autoimmunity.

PubMed

Marusina, Alina I; Ono, Yoko; Merleev, Alexander A; Shimoda, Michiko; Ogawa, Hiromi; Wang, Elizabeth A; Kondo, Kayo; Olney, Laura; Luxardi, Guillaume; Miyamura, Yoshinori; Yilma, Tilahun D; Villalobos, Itzel Bustos; Bergstrom, Jennifer W; Kronenberg, Daniel G; Soulika, Athena M; Adamopoulos, Iannis E; Maverakis, Emanual

2017-02-01

It is widely accepted that central and effector memory CD4 + T cells originate from naïve T cells after they have encountered their cognate antigen in the setting of appropriate co-stimulation. However, if this were true the diversity of T cell receptor (TCR) sequences within the naïve T cell compartment should be far greater than that of the memory T cell compartment, which is not supported by TCR sequencing data. Here we demonstrate that aged mice with far fewer naïve T cells, respond to the model antigen, hen eggwhite lysozyme (HEL), by utilizing the same TCR sequence as their younger counterparts. CD4 + T cell repertoire analysis of highly purified T cell populations from naive animals revealed that the HEL-specific clones displayed effector and central "memory" cell surface phenotypes even prior to having encountered their cognate antigen. Furthermore, HEL-inexperienced CD4 + T cells were found to reside within the naïve, regulatory, central memory, and effector memory T cell populations at similar frequencies and the majority of the CD4 + T cells within the regulatory and memory populations were unexpanded. These findings support a new paradigm for CD4 + T cell maturation in which a specific clone can undergo a differentiation process to exhibit a "memory" or regulatory phenotype without having undergone a clonal expansion event. It also demonstrates that a foreign-specific T cell is just as likely to reside within the regulatory T cell compartment as it would the naïve compartment, arguing against the specificity of the regulatory T cell compartment being skewed towards self-reactive T cell clones. Finally, we demonstrate that the same set of foreign and autoreactive CD4 + T cell clones are repetitively generated throughout adulthood. The latter observation argues against T cell-depleting strategies or autologous stem cell transplantation as therapies for autoimmunity-as the immune system has the ability to regenerate pathogenic clones. Published by Elsevier Ltd.

A Low-cost System for Generating Near-realistic Virtual Actors

NASA Astrophysics Data System (ADS)

Afifi, Mahmoud; Hussain, Khaled F.; Ibrahim, Hosny M.; Omar, Nagwa M.

2015-06-01

Generating virtual actors is one of the most challenging fields in computer graphics. The reconstruction of a realistic virtual actor has been paid attention by the academic research and the film industry to generate human-like virtual actors. Many movies were acted by human-like virtual actors, where the audience cannot distinguish between real and virtual actors. The synthesis of realistic virtual actors is considered a complex process. Many techniques are used to generate a realistic virtual actor; however they usually require expensive hardware equipment. In this paper, a low-cost system that generates near-realistic virtual actors is presented. The facial features of the real actor are blended with a virtual head that is attached to the actor's body. Comparing with other techniques that generate virtual actors, the proposed system is considered a low-cost system that requires only one camera that records the scene without using any expensive hardware equipment. The results of our system show that the system generates good near-realistic virtual actors that can be used on many applications.

On the flexibility of social source memory: a test of the emotional incongruity hypothesis.

PubMed

Bell, Raoul; Buchner, Axel; Kroneisen, Meike; Giang, Trang

2012-11-01

A popular hypothesis in evolutionary psychology posits that reciprocal altruism is supported by a cognitive module that helps cooperative individuals to detect and remember cheaters. Consistent with this hypothesis, a source memory advantage for faces of cheaters (better memory for the cheating context in which these faces were encountered) was observed in previous studies. Here, we examined whether positive or negative expectancies would influence source memory for cheaters and cooperators. A cooperation task with virtual opponents was used in Experiments 1 and 2. Source memory for the emotionally incongruent information was enhanced relative to the congruent information: In Experiment 1, source memory was best for cheaters with likable faces and for cooperators with unlikable faces; in Experiment 2, source memory was better for smiling cheater faces than for smiling cooperator faces, and descriptively better for angry cooperator faces than for angry cheater faces. Experiments 3 and 4 showed that the emotional incongruity effect generalizes to 3rd-party reputational information (descriptions of cheating and trustworthy behavior). The results are inconsistent with the assumption of a highly specific cheater detection module. Focusing on expectancy-incongruent information may represent a more efficient, general, and hence more adaptive memory strategy for remembering exchange-relevant information than focusing only on cheaters.

Getting to the Root of Fine Motor Skill Performance in Dentistry: Brain Activity During Dental Tasks in a Virtual Reality Haptic Simulation

PubMed Central

Bridges, Susan M; Zhu, Frank; Leung, W Keung; Burrow, Michael F; Poolton, Jamie; Masters, Rich SW

2017-01-01

Background There is little evidence considering the relationship between movement-specific reinvestment (a dimension of personality which refers to the propensity for individuals to consciously monitor and control their movements) and working memory during motor skill performance. Functional near-infrared spectroscopy (fNIRS) measuring oxyhemoglobin demands in the frontal cortex during performance of virtual reality (VR) psychomotor tasks can be used to examine this research gap. Objective The aim of this study was to determine the potential relationship between the propensity to reinvest and blood flow to the dorsolateral prefrontal cortices of the brain. A secondary aim was to determine the propensity to reinvest and performance during 2 dental tasks carried out using haptic VR simulators. Methods We used fNIRS to assess oxygen demands in 24 undergraduate dental students during 2 dental tasks (clinical, nonclinical) on a VR haptic simulator. We used the Movement-Specific Reinvestment Scale questionnaire to assess the students’ propensity to reinvest. Results Students with a high propensity for movement-specific reinvestment displayed significantly greater oxyhemoglobin demands in an area associated with working memory during the nonclinical task (Spearman correlation, rs=.49, P=.03). Conclusions This small-scale study suggests that neurophysiological differences are evident between high and low reinvesters during a dental VR task in terms of oxyhemoglobin demands in an area associated with working memory. PMID:29233801

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.

Speeding up local correlation methods

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

Kats, Daniel

2014-12-28

We present two techniques that can substantially speed up the local correlation methods. The first one allows one to avoid the expensive transformation of the electron-repulsion integrals from atomic orbitals to virtual space. The second one introduces an algorithm for the residual equations in the local perturbative treatment that, in contrast to the standard scheme, does not require holding the amplitudes or residuals in memory. It is shown that even an interpreter-based implementation of the proposed algorithm in the context of local MP2 method is faster and requires less memory than the highly optimized variants of conventional algorithms.

Fast Response Shape Memory Effect Titanium Nickel (TiNi) Foam Torque Tubes

NASA Technical Reports Server (NTRS)

Jardine, Peter

2014-01-01

Shape Change Technologies has developed a process to manufacture net-shaped TiNi foam torque tubes that demonstrate the shape memory effect. The torque tubes dramatically reduce response time by a factor of 10. This Phase II project matured the actuator technology by rigorously characterizing the process to optimize the quality of the TiNi and developing a set of metrics to provide ISO 9002 quality assurance. A laboratory virtual instrument engineering workbench (LabVIEW'TM')-based, real-time control of the torsional actuators was developed. These actuators were developed with The Boeing Company for aerospace applications.

Potential of minicomputer/array-processor system for nonlinear finite-element analysis

NASA Technical Reports Server (NTRS)

Strohkorb, G. A.; Noor, A. K.

1983-01-01

The potential of using a minicomputer/array-processor system for the efficient solution of large-scale, nonlinear, finite-element problems is studied. A Prime 750 is used as the host computer, and a software simulator residing on the Prime is employed to assess the performance of the Floating Point Systems AP-120B array processor. Major hardware characteristics of the system such as virtual memory and parallel and pipeline processing are reviewed, and the interplay between various hardware components is examined. Effective use of the minicomputer/array-processor system for nonlinear analysis requires the following: (1) proper selection of the computational procedure and the capability to vectorize the numerical algorithms; (2) reduction of input-output operations; and (3) overlapping host and array-processor operations. A detailed discussion is given of techniques to accomplish each of these tasks. Two benchmark problems with 1715 and 3230 degrees of freedom, respectively, are selected to measure the anticipated gain in speed obtained by using the proposed algorithms on the array processor.

The impact of positive, negative and neutral stimuli in a virtual reality cognitive-motor rehabilitation task: a pilot study with stroke patients.

PubMed

Cameirão, Mónica S; Faria, Ana Lúcia; Paulino, Teresa; Alves, Júlio; Bermúdez I Badia, Sergi

2016-08-09

Virtual Reality (VR) based methods for stroke rehabilitation have mainly focused on motor rehabilitation, but there is increasing interest in integrating motor and cognitive training to increase similarity to real-world settings. Unfortunately, more research is needed for the definition of which type of content should be used in the design of these tools. One possibility is the use of emotional stimuli, which are known to enhance attentional processes. According to the Socioemotional Selectivity Theory, as people age, the emotional salience arises for positive and neutral, but not for negative stimuli. For this study we developed a cognitive-motor VR task involving attention and short-term memory, and we investigated the impact of using emotional images of varying valence. The task consisted of finding a target image, shown for only two seconds, among fourteen neutral distractors, and selecting it through arm movements. After performing the VR task, a recall task took place and the patients had to identify the target images among a valence-matched number of distractors. Ten stroke patients participated in a within-subjects experiment with three conditions based on the valence of the images: positive, negative and neutral. Eye movements were recorded during VR task performance with an eye tracking system. Our results show decreased attention for negative stimuli in the VR task performance when compared to neutral stimuli. The recall task shows significantly more wrongly identified images (false memories) for negative stimuli than for neutral. Regression and correlation analyses with the Montreal Cognitive Assessment and the Geriatric Depression Scale revealed differential effects of cognitive function and depressive symptomatology in the encoding and recall of positive, negative and neutral images. Further, eye movement data shows reduced search patterns for wrongly selected stimuli containing emotional content. The results of this study suggest that it is feasible to use emotional content in a VR based cognitive-motor task for attention and memory training after stroke. Stroke survivors showed less attention towards negative information, exhibiting reduced visual search patterns and more false memories. We have also shown that the use of emotional stimuli in a VR task can provide additional information regarding patient's mood and cognitive status.

Parts, Cavities, and Object Representation in Infancy

ERIC Educational Resources Information Center

Hayden, Angela; Bhatt, Ramesh S.; Kangas, Ashley; Zieber, Nicole

2011-01-01

Part representation is not only critical to object perception but also plays a key role in a number of basic visual cognition functions, such as figure-ground segregation, allocation of attention, and memory for shapes. Yet, virtually nothing is known about the development of part representation. If parts are fundamental components of object shape…

Is It Always Me First? Effects of Self-Tagging on Third-Person Perspective-Taking

ERIC Educational Resources Information Center

Mattan, Bradley; Quinn, Kimberly A.; Apperly, Ian A.; Sui, Jie; Rotshtein, Pia

2015-01-01

Self-relevant information is associated with facilitation of perceptual and memory processes. In 2 experiments, participants verified the number of dots within a virtual room that were visible to a given perspective, corresponding to participants' own first-person perspectives or the third-person perspectives for self- and other-associated…

Task Demands Control Acquisition and Storage of Visual Information

ERIC Educational Resources Information Center

Droll, Jason A.; Hayhoe, Mary M.; Triesch, Jochen; Sullivan, Brian T.

2005-01-01

Attention and working memory limitations set strict limits on visual representations, yet researchers have little appreciation of how these limits constrain the acquisition of information in ongoing visually guided behavior. Subjects performed a brick sorting task in a virtual environment. A change was made to 1 of the features of the brick being…

Intrusion Detection and Forensics for Self-Defending Wireless Networks

DTIC Science & Technology

2012-12-01

ICNP), Nov. 2007. 5. Yao Zhao, Yan Chen, Bo Li, and Qian Zhang, Hop ID: A Virtual Coordinate based Routing for Sparse Mobile Ad Hoc Networks, in...Liu, Hongbo Zhao, Kai Chen and Yan Chen, " DISCO : Memory Efficient and Accurate Flow Statistics for Network Measurement", in the Proc. of IEEE ICDCS

Age-Related Decline in Primary CD8+ T Cell Responses Is Associated with the Development of Senescence in Virtual Memory CD8+ T Cells.

PubMed

Quinn, Kylie M; Fox, Annette; Harland, Kim L; Russ, Brendan E; Li, Jasmine; Nguyen, Thi H O; Loh, Liyen; Olshanksy, Moshe; Naeem, Haroon; Tsyganov, Kirill; Wiede, Florian; Webster, Rosela; Blyth, Chantelle; Sng, Xavier Y X; Tiganis, Tony; Powell, David; Doherty, Peter C; Turner, Stephen J; Kedzierska, Katherine; La Gruta, Nicole L

2018-06-19

Age-associated decreases in primary CD8 + T cell responses occur, in part, due to direct effects on naive CD8 + T cells to reduce intrinsic functionality, but the precise nature of this defect remains undefined. Aging also causes accumulation of antigen-naive but semi-differentiated "virtual memory" (T VM ) cells, but their contribution to age-related functional decline is unclear. Here, we show that T VM cells are poorly proliferative in aged mice and humans, despite being highly proliferative in young individuals, while conventional naive T cells (T N cells) retain proliferative capacity in both aged mice and humans. Adoptive transfer experiments in mice illustrated that naive CD8 T cells can acquire a proliferative defect imposed by the aged environment but age-related proliferative dysfunction could not be rescued by a young environment. Molecular analyses demonstrate that aged T VM cells exhibit a profile consistent with senescence, marking an observation of senescence in an antigenically naive T cell population. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Assessing the mental frame syncing in the elderly: a virtual reality protocol.

PubMed

Serino, Silvia; Cipresso, Pietro; Gaggioli, Andrea; Riva, Giuseppe

2014-01-01

Decline in spatial memory in the elderly is often underestimated, and it is crucial to fully investigate the cognitive underpinnings of early spatial impairment. A virtual reality-based procedure was developed to assess deficit in the "mental frame syncing", namely the cognitive ability that allows an effective orientation by synchronizing the allocentric view-point independent representation with the allocentric view-point dependent representation. A pilot study was carried out to evaluate abilities in the mental frame syncing in a sample of 16 elderly participants. Preliminary results indicated that the general cognitive functioning was associated with the ability in the synchronization between these two allocentric references frames.

Blood leakage detection during dialysis therapy based on fog computing with array photocell sensors and heteroassociative memory model

PubMed Central

Wu, Jian-Xing; Huang, Ping-Tzan; Li, Chien-Ming

2018-01-01

Blood leakage and blood loss are serious life-threatening complications occurring during dialysis therapy. These events have been of concerns to both healthcare givers and patients. More than 40% of adult blood volume can be lost in just a few minutes, resulting in morbidities and mortality. The authors intend to propose the design of a warning tool for the detection of blood leakage/blood loss during dialysis therapy based on fog computing with an array of photocell sensors and heteroassociative memory (HAM) model. Photocell sensors are arranged in an array on a flexible substrate to detect blood leakage via the resistance changes with illumination in the visible spectrum of 500–700 nm. The HAM model is implemented to design a virtual alarm unit using electricity changes in an embedded system. The proposed warning tool can indicate the risk level in both end-sensing units and remote monitor devices via a wireless network and fog/cloud computing. The animal experimental results (pig blood) will demonstrate the feasibility. PMID:29515815

Blood leakage detection during dialysis therapy based on fog computing with array photocell sensors and heteroassociative memory model.

PubMed

Wu, Jian-Xing; Huang, Ping-Tzan; Lin, Chia-Hung; Li, Chien-Ming

2018-02-01

Blood leakage and blood loss are serious life-threatening complications occurring during dialysis therapy. These events have been of concerns to both healthcare givers and patients. More than 40% of adult blood volume can be lost in just a few minutes, resulting in morbidities and mortality. The authors intend to propose the design of a warning tool for the detection of blood leakage/blood loss during dialysis therapy based on fog computing with an array of photocell sensors and heteroassociative memory (HAM) model. Photocell sensors are arranged in an array on a flexible substrate to detect blood leakage via the resistance changes with illumination in the visible spectrum of 500-700 nm. The HAM model is implemented to design a virtual alarm unit using electricity changes in an embedded system. The proposed warning tool can indicate the risk level in both end-sensing units and remote monitor devices via a wireless network and fog/cloud computing. The animal experimental results (pig blood) will demonstrate the feasibility.

Research in Parallel Algorithms and Software for Computational Aerosciences

NASA Technical Reports Server (NTRS)

Domel, Neal D.

1996-01-01

Phase I is complete for the development of a Computational Fluid Dynamics parallel code with automatic grid generation and adaptation for the Euler analysis of flow over complex geometries. SPLITFLOW, an unstructured Cartesian grid code developed at Lockheed Martin Tactical Aircraft Systems, has been modified for a distributed memory/massively parallel computing environment. The parallel code is operational on an SGI network, Cray J90 and C90 vector machines, SGI Power Challenge, and Cray T3D and IBM SP2 massively parallel machines. Parallel Virtual Machine (PVM) is the message passing protocol for portability to various architectures. A domain decomposition technique was developed which enforces dynamic load balancing to improve solution speed and memory requirements. A host/node algorithm distributes the tasks. The solver parallelizes very well, and scales with the number of processors. Partially parallelized and non-parallelized tasks consume most of the wall clock time in a very fine grain environment. Timing comparisons on a Cray C90 demonstrate that Parallel SPLITFLOW runs 2.4 times faster on 8 processors than its non-parallel counterpart autotasked over 8 processors.

Research in Parallel Algorithms and Software for Computational Aerosciences

NASA Technical Reports Server (NTRS)

Domel, Neal D.

1996-01-01

Phase 1 is complete for the development of a computational fluid dynamics CFD) parallel code with automatic grid generation and adaptation for the Euler analysis of flow over complex geometries. SPLITFLOW, an unstructured Cartesian grid code developed at Lockheed Martin Tactical Aircraft Systems, has been modified for a distributed memory/massively parallel computing environment. The parallel code is operational on an SGI network, Cray J90 and C90 vector machines, SGI Power Challenge, and Cray T3D and IBM SP2 massively parallel machines. Parallel Virtual Machine (PVM) is the message passing protocol for portability to various architectures. A domain decomposition technique was developed which enforces dynamic load balancing to improve solution speed and memory requirements. A host/node algorithm distributes the tasks. The solver parallelizes very well, and scales with the number of processors. Partially parallelized and non-parallelized tasks consume most of the wall clock time in a very fine grain environment. Timing comparisons on a Cray C90 demonstrate that Parallel SPLITFLOW runs 2.4 times faster on 8 processors than its non-parallel counterpart autotasked over 8 processors.

Development of a virtual reality training system for endoscope-assisted submandibular gland removal.

PubMed

Miki, Takehiro; Iwai, Toshinori; Kotani, Kazunori; Dang, Jianwu; Sawada, Hideyuki; Miyake, Minoru

2016-11-01

Endoscope-assisted surgery has widely been adopted as a basic surgical procedure, with various training systems using virtual reality developed for this procedure. In the present study, a basic training system comprising virtual reality for the removal of submandibular glands under endoscope assistance was developed. The efficacy of the training system was verified in novice oral surgeons. A virtual reality training system was developed using existing haptic devices. Virtual reality models were constructed from computed tomography data to ensure anatomical accuracy. Novice oral surgeons were trained using the developed virtual reality training system. The developed virtual reality training system included models of the submandibular gland and surrounding connective tissues and blood vessels entering the submandibular gland. Cutting or abrasion of the connective tissue and manipulations, such as elevation of blood vessels, were reproduced by the virtual reality system. A training program using the developed system was devised. Novice oral surgeons were trained in accordance with the devised training program. Our virtual reality training system for endoscope-assisted removal of the submandibular gland is effective in the training of novice oral surgeons in endoscope-assisted surgery. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Training, transfer, and retention of three-dimensional spatial memory in virtual environments

NASA Technical Reports Server (NTRS)

Richards, Jason T.; Oman, Charles M.; Shebilske, Wayne L.; Beall, Andrew C.; Liu, Andrew; Natapoff, Alan

2002-01-01

Human orientation requires one to remember and visualize spatial arrangements of landmarks from different perspectives. Astronauts have reported difficulties remembering relationships between environmental landmarks when imagined in arbitrary 3D orientations. The present study investigated the effects of strategy training on humans' 1) ability to infer their orientation from landmarks presented ahead and below, 2) performance when subsequently learning a different array, and 3) retention of configurational knowledge over time. On the first experiment day, 24 subjects were tested in a virtual cubic chamber in which a picture of an animal was drawn on each wall. Through trial-by-trial exposures, they had to memorize the spatial relationships among the six pictures around them and learn to predict the direction to a specific picture when facing any view direction, and in any roll orientation. Half of the subjects ("strategy group") were taught methods for remembering picture groupings, while the remainder received no such training ("control group"). After learning one picture array, the procedure was repeated in a second. Accuracy (% correct) and response time learning curves were measured. Performance for the second array and configurational memory of both arrays were also retested 1, 7, and 30 days later. Results showed that subjects "learned how to learn" this generic 3D spatial memory task regardless of their relative orientation to the environment, that ability and configurational knowledge was retained for at least a month, that figure rotation ability and field independence correlate with performance, and that teaching subjects specific strategies in advance significantly improves performance. Training astronauts to perform a similar generic 3D spatial memory task, and suggesting strategies in advance, may help them orient in three dimensions.

Petabyte mass memory system using the Newell Opticel(TM)

NASA Technical Reports Server (NTRS)

Newell, Chester W.

1994-01-01

A random access system is proposed for digital storage and retrieval of up to a Petabyte of user data. The system is comprised of stacked memory modules using laser heads writing to an optical medium, in a new shirt-pocket-sized optical storage device called the Opticel. The Opticel described is a completely sealed 'black box' in which an optical medium is accelerated and driven at very high rates to accommodate the desired transfer rates, yet in such a manner that wear is virtually eliminated. It essentially emulates a disk, but with storage area up to several orders of magnitude higher. Access time to the first bit can range from a few milliseconds to a fraction of a second, with time to the last bit within a fraction of a second to a few seconds. The actual times are dependent on the capacity of each Opticel, which ranges from 72 Gigabytes to 1.25 Terabytes. Data transfer rate is limited strictly by the head and electronics, and is 15 Megabits per second in the first version. Independent parallel write/read access to each Opticel is provided using dedicated drives and heads. A Petabyte based on the present Opticel and drive design would occupy 120 cubic feet on a footprint of 45 square feet; with further development, it could occupy as little as 9 cubic feet.

Retrograde amnesia in patients with diencephalic, temporal lobe or frontal lesions.

PubMed

Kopelman, M D; Stanhope, N; Kingsley, D

1999-07-01

Patients with focal diencephalic, temporal lobe, or frontal lobe lesions were examined on various measures of remote memory. Korsakoff patients showed a severe impairment with a characteristic 'temporal gradient', whereas two patients with focal diencephalic damage (and anterograde amnesia) were virtually unimpaired on remote memory measures. Patients with frontal lobe pathology were severely impaired in the recall of autobiographical incidents and famous news events. Patients with temporal lobe pathology showed severe impairment but a relatively 'flat' temporal gradient, largely attributable to herpes encephalitis patients. From recognition and cued recall tasks, it is argued that there is an important retrieval component to the remote memory deficit across all the lesion groups. In general, the pattern of performance by the frontal lobe and temporal lobe groups was closely similar, and there was no evidence of any major access/storage difference between them. However, laterality comparisons across these groups indicated that the right temporal and frontal lobe regions may make a greater contribution to the retrieval of past episodic (incident and event) memories, whereas the left temporal region is more closely involved in the lexical-semantic labelling of remote memories.

Acquired amnesia in childhood: a single case study.

PubMed

Vicari, Stefano; Menghini, Deny; Di Paola, Margherita; Serra, Laura; Donfrancesco, Alberto; Fidani, Paola; Milano, Giuseppe Maria; Carlesimo, Giovanni Augusto

2007-03-02

We report the case of C.L., an 8-year-old child who, following the surgical removal of an ependymoma from the left cerebral ventricle at the age of 4 years, developed significant difficulties in retaining day-to-day events and information. A thorough neuropsychological analysis documented in C.L. a severe anterograde amnesic syndrome, characterised by normal short-term memory, but poor performance on episodic long-term memory tests. In particular, C.L. demonstrated virtually no ability to recollect new verbal information several minutes after the presentation. As for semantic memory, C.L. demonstrated general semantic competencies, which, depending on the test, ranged from the level of a 6-year-old girl to a level corresponding to her actual chronological age. Finding a patient who, despite being severely impaired in the ability to recollect new episodic memories, still demonstrates at least partially preserved abilities to acquire new semantic knowledge suggests that neural circuits implicated in the memorisation of autobiographical events and factual information do not overlap completely. This case is examined in the light of growing literature concerned with the dissociation between episodic and semantic memory in childhood amnesia.

Getting with the times: a narrative review of the literature on group decision making in virtual environments and implications for promotions committees.

PubMed

Acai, Anita; Sonnadara, Ranil R; O'Neill, Thomas A

2018-06-01

Concerns around the time and administrative burden of trainee promotion processes have been reported, making virtual meetings an attractive option for promotions committees in undergraduate and postgraduate medicine. However, whether such meetings can uphold the integrity of decision-making processes has yet to be explored. This narrative review aimed to summarize the literature on decision making in virtual teams, discuss ways to improve the effectiveness of virtual teams, and explore their implications for practice. In August 2017, the Web of Science platform was searched with the terms 'decision making' AND 'virtual teams' for articles published within the last 20 years. The search yielded 336 articles, which was narrowed down to a final set of 188 articles. A subset of these, subjectively deemed to be of high-quality and relevant to the work of promotions committees, was included in this review. Virtual team functioning was explored with respect to team composition and development, idea generation and selection, group memory, and communication. While virtual teams were found to potentially offer a number of key benefits over face-to-face meetings including convenience and scheduling flexibility, inclusion of members at remote sites, and enhanced idea generation and external storage, these benefits must be carefully weighed against potential challenges involving planning and coordination, integration of perspectives, and relational conflict among members, all of which can potentially reduce decision-making quality. Avenues to address these issues and maximize the outcomes of virtual promotions meetings are offered in light of the evidence.

Computer network defense system

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

Urias, Vincent; Stout, William M. S.; Loverro, Caleb

A method and apparatus for protecting virtual machines. A computer system creates a copy of a group of the virtual machines in an operating network in a deception network to form a group of cloned virtual machines in the deception network when the group of the virtual machines is accessed by an adversary. The computer system creates an emulation of components from the operating network in the deception network. The components are accessible by the group of the cloned virtual machines as if the group of the cloned virtual machines was in the operating network. The computer system moves networkmore » connections for the group of the virtual machines in the operating network used by the adversary from the group of the virtual machines in the operating network to the group of the cloned virtual machines, enabling protecting the group of the virtual machines from actions performed by the adversary.« less

Tethered Forth system for FPGA applications

NASA Astrophysics Data System (ADS)

Goździkowski, Paweł; Zabołotny, Wojciech M.

2013-10-01

This paper presents the tethered Forth system dedicated for testing and debugging of FPGA based electronic systems. Use of the Forth language allows to interactively develop and run complex testing or debugging routines. The solution is based on a small, 16-bit soft core CPU, used to implement the Forth Virtual Machine. Thanks to the use of the tethered Forth model it is possible to minimize usage of the internal RAM memory in the FPGA. The function of the intelligent terminal, which is an essential part of the tethered Forth system, may be fulfilled by the standard PC computer or by the smartphone. System is implemented in Python (the software for intelligent terminal), and in VHDL (the IP core for FPGA), so it can be easily ported to different hardware platforms. The connection between the terminal and FPGA may be established and disconnected many times without disturbing the state of the FPGA based system. The presented system has been verified in the hardware, and may be used as a tool for debugging, testing and even implementing of control algorithms for FPGA based systems.

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

PubMed

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

2001-01-01

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

Co-Curate: Working with Schools and Communities to Add Value to Open Collections

ERIC Educational Resources Information Center

Cotterill, Simon; Hudson, Martyn; Lloyd, Katherine; Outterside, James; Peterson, John; Coburn, John; Thomas, Ulrike; Tiplady, Lucy; Robinson, Phil; Heslop, Phil

2016-01-01

Co-Curate North East is a cross-disciplinary initiative involving Newcastle University and partner organisations, working with schools and community groups in the North East of England. Co-curation builds on the concept of the "ecomuseum" model for heritage based around a virtual territory, social memory and participative input from the…

Virtual Parts Engineering Research Center

DTIC Science & Technology

2010-05-20

engineering 10 materials. High strength alloys , composites (polymer composites and metallic composites), and the like cannot merely be replaced by...ceramics, smart materials, shape memory alloys , super plastic materials and nano- structured materials may be more appropriate substitutes in a reverse...molding process using thermosetting Bakelite. For remanufacturing the part in small quantities, machining has been identified as the most economical

Sleep Enhances a Spatially Mediated Generalization of Learned Values

ERIC Educational Resources Information Center

Javadi, Amir-Homayoun; Tolat, Anisha; Spiers, Hugo J.

2015-01-01

Sleep is thought to play an important role in memory consolidation. Here we tested whether sleep alters the subjective value associated with objects located in spatial clusters that were navigated to in a large-scale virtual town. We found that sleep enhances a generalization of the value of high-value objects to the value of locally clustered…

Comparable Rest-related Promotion of Spatial Memory Consolidation in Younger and Older Adults

PubMed Central

Craig, Michael; Wolbers, Thomas; Harris, Mathew A.; Hauff, Patrick; Della Sala, Sergio; Dewar, Michaela

2017-01-01

Flexible spatial navigation depends on cognitive mapping, a function that declines with increasing age. In young adults, a brief period of post-navigation rest promotes the consolidation/integration of spatial memories into accurate cognitive maps. We examined (1) whether rest promotes spatial memory consolidation/integration in older adults and (2) whether the magnitude of the rest benefit changes with increasing age. Young and older adults learned a route through a virtual environment, followed by a 10min delay comprising either wakeful rest or a perceptual task, and a subsequent cognitive mapping task, requiring the pointing to landmarks from different locations. Pointing accuracy was lower in the older than younger adults. However, there was a comparable rest-related enhancement in pointing accuracy in the two age groups. Together our findings suggest that (i) the age-related decline in cognitive mapping cannot be explained by increased consolidation interference in older adults, and (ii) as we grow older rest continues to support the consolidation/integration of spatial memories. PMID:27689512

[The Role of Distinctiveness of Stimulus in Memory Distrust as a Function of Repeated Checking].

PubMed

Demirsöz, Talat; Ayvaşık, H Belgin

2017-01-01

Recent literature proposes that repeated checking increases familiarity with the material, making recollections less vivid and detailed and promoting distrust in memory. The aim of the current study is to investigate the possible underlying mechanisms of low confidence in memory. The Padua Inventory-Washington State University Revision (PI-WSUR) was applied in a cohort of university students. Among the students who completed the PI-WSUR, 84 participants were selected and assigned to low Obsessive-Compulsive Symptomatology (OCS) group or high OCS group according to their PI-WSUR scores. An interactive computer animation was developed to test repeated checking behavior. Participants were randomly assigned to two experimental conditions: "Feedback condition" and "no feedback condition". The participants were all asked to carry out checking rituals on a virtual gas ring. However, half of the participants were given feedback indicating that checking activity was successful and complete and half of the participants were not. While there was no significant difference in terms of memory accuracy, memory detail and memory vividness between feedback condition and no feedback condition, there was a significant difference in terms of memory confidence between two experimental groups. Results are discussed in the light of a different explanation offering that the level of distinctiveness of recollections plays crucial role in memory distrust rather than the explanation of low confidence hypothesis.

Head-mounted active noise control system with virtual sensing technique

NASA Astrophysics Data System (ADS)

Miyazaki, Nobuhiro; Kajikawa, Yoshinobu

2015-03-01

In this paper, we apply a virtual sensing technique to a head-mounted active noise control (ANC) system we have already proposed. The proposed ANC system can reduce narrowband noise while improving the noise reduction ability at the desired locations. A head-mounted ANC system based on an adaptive feedback structure can reduce noise with periodicity or narrowband components. However, since quiet zones are formed only at the locations of error microphones, an adequate noise reduction cannot be achieved at the locations where error microphones cannot be placed such as near the eardrums. A solution to this problem is to apply a virtual sensing technique. A virtual sensing ANC system can achieve higher noise reduction at the desired locations by measuring the system models from physical sensors to virtual sensors, which will be used in the online operation of the virtual sensing ANC algorithm. Hence, we attempt to achieve the maximum noise reduction near the eardrums by applying the virtual sensing technique to the head-mounted ANC system. However, it is impossible to place the microphone near the eardrums. Therefore, the system models from physical sensors to virtual sensors are estimated using the Head And Torso Simulator (HATS) instead of human ears. Some simulation, experimental, and subjective assessment results demonstrate that the head-mounted ANC system with virtual sensing is superior to that without virtual sensing in terms of the noise reduction ability at the desired locations.

The Construct of Attention in Schizophrenia

PubMed Central

Luck, Steven J.; Gold, James M.

2008-01-01

Schizophrenia is widely thought to involve deficits of attention. However, the term attention can be defined so broadly that impaired performance on virtually any task could be construed as evidence for a deficit in attention, and this has slowed cumulative progress in understanding attention deficits in schizophrenia. To address this problem, we divide the general concept of attention into two distinct constructs: input selection, the selection of task-relevant inputs for further processing; and rule selection, the selective activation of task-appropriate rules. These constructs are closely tied to working memory, because input selection mechanisms are used to control the transfer of information into working memory and because working memory stores the rules used by rule selection mechanisms. These constructs are also closely tied to executive function, because executive systems are used to guide input selection and because rule selection is itself at key aspect of executive function. Within the domain of input selection, it is important to distinguish between the control of selection—the processes that guide attention to task-relevant inputs—and the implementation of selection—the processes that enhance the processing of the relevant inputs and suppress the irrelevant inputs. Current evidence suggests that schizophrenia involves a significant impairment in the control of selection but little or no impairment in the implementation of selection. Consequently, the CNTRICS participants agreed by consensus that attentional control should be a priority target for measurement and treatment research in schizophrenia. PMID:18374901

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.

Graphene as a platform for novel nanoelectronic devices

NASA Astrophysics Data System (ADS)

Standley, Brian

Graphene's superlative electrical and mechanical properties, combined with its compatibility with existing planar silicon-based technology, make it an attractive platform for novel nanoelectronic devices. The development of two such devices is reported--a nonvolatile memory element exploiting the nanoscale graphene edge and a field-effect transistor using graphene for both the conducting channel and, in oxidized form, the gate dielectric. These experiments were enabled by custom software written to fully utilize both instrument-based and computer-based data acquisition hardware and provide a simple measurement automation system. Graphene break junctions were studied and found to exhibit switching behavior in response to an electric field. This switching allows the devices to act as nonvolatile memory elements which have demonstrated thousands of writing cycles and long retention times. A model for device operation is proposed based on the formation and breaking of carbon-atom chains that bridge the junctions. Information storage was demonstrated using the concept of rank coding, in which information is stored in the relative conductance of multiple graphene switches in a memory cell. The high mobility and two dimensional nature of graphene make it an attractive material for field-effect transistors. Another ultrathin layered materialmd graphene's insulating analogue, graphite oxidemd was studied as an alternative to bulk gate dielectric materials such as Al2O3 or HfO 2. Transistors were fabricated comprising single or bilayer graphene channels, graphite oxide gate insulators, and metal top-gates. Electron transport measurements reveal minimal leakage through the graphite oxide at room temperature. Its breakdown electric field was found to be comparable to SiO2, typically ˜1-3 x 108 V/m, while its dielectric constant is slightly higher, kappa ≈ 4.3. As nanoelectronics experiments and their associated instrumentation continue to grow in complexity the need for powerful data acquisition software has only increased. This role has traditionally been filled by semiconductor parameter analyzers or desktop computers running LabVIEW. Mezurit 2 represents a hybrid approach, providing basic virtual instruments which can be controlled in concert through a comprehensive scripting interface. Each virtual instrument's model of operation is described and an architectural overview is provided.

Efficient Generation and Selection of Virtual Populations in Quantitative Systems Pharmacology Models.

PubMed

Allen, R J; Rieger, T R; Musante, C J

2016-03-01

Quantitative systems pharmacology models mechanistically describe a biological system and the effect of drug treatment on system behavior. Because these models rarely are identifiable from the available data, the uncertainty in physiological parameters may be sampled to create alternative parameterizations of the model, sometimes termed "virtual patients." In order to reproduce the statistics of a clinical population, virtual patients are often weighted to form a virtual population that reflects the baseline characteristics of the clinical cohort. Here we introduce a novel technique to efficiently generate virtual patients and, from this ensemble, demonstrate how to select a virtual population that matches the observed data without the need for weighting. This approach improves confidence in model predictions by mitigating the risk that spurious virtual patients become overrepresented in virtual populations.

Navigational strategies underlying phototaxis in larval zebrafish

PubMed Central

Chen, Xiuye; Engert, Florian

2014-01-01

Understanding how the brain transforms sensory input into complex behavior is a fundamental question in systems neuroscience. Using larval zebrafish, we study the temporal component of phototaxis, which is defined as orientation decisions based on comparisons of light intensity at successive moments in time. We developed a novel “Virtual Circle” assay where whole-field illumination is abruptly turned off when the fish swims out of a virtually defined circular border, and turned on again when it returns into the circle. The animal receives no direct spatial cues and experiences only whole-field temporal light changes. Remarkably, the fish spends most of its time within the invisible virtual border. Behavioral analyses of swim bouts in relation to light transitions were used to develop four discrete temporal algorithms that transform the binary visual input (uniform light/uniform darkness) into the observed spatial behavior. In these algorithms, the turning angle is dependent on the behavioral history immediately preceding individual turning events. Computer simulations show that the algorithms recapture most of the swim statistics of real fish. We discovered that turning properties in larval zebrafish are distinctly modulated by temporal step functions in light intensity in combination with the specific motor history preceding these turns. Several aspects of the behavior suggest memory usage of up to 10 swim bouts (~10 sec). Thus, we show that a complex behavior like spatial navigation can emerge from a small number of relatively simple behavioral algorithms. PMID:24723859

Decision Making and Cognitive Behavioral Flexibility in a OCD Sample: a Study in a Virtual Environment.

PubMed

la Paglia, Filippo; la Cascia, Caterina; Rizzo, Rosalinda; Riva, Giuseppe; la Barbera, Daniele

2015-01-01

Neuropsychological disorders are common in Obsessive-Compulsive Disorder (OCD) patients. Executive functions, verbal fluency and verbal memory, shifting attention from one aspect of stimuli to others, mental flexibility, engaging in executive planning and decision making, are the most involved cognitive domains. We focus on two aspects of neuropsychological function: decision making and cognitive behavioral flexibility, assessed through a virtual version of the Multiple Errand Test (V-MET), developed using the NeuroVR software. Thirty OCD patients were compared with thirty matched control subjects. The results showed the presence of difficulties in OCD patients with tasks where the goal is not clear, the information is incomplete or the parameters are ill-defined.

Development and application of General Purpose Data Acquisition Shell (GPDAS) at advanced photon source

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

Chung, Youngjoo; Kim, Keeman.

1991-01-01

An operating system shell GPDAS (General Purpose Data Acquisition Shell) on MS-DOS-based microcomputers has been developed to provide flexibility in data acquisition and device control for magnet measurements at the Advanced Photon Source. GPDAS is both a command interpreter and an integrated script-based programming environment. It also incorporates the MS-DOS shell to make use of the existing utility programs for file manipulation and data analysis. Features include: alias definition, virtual memory, windows, graphics, data and procedure backup, background operation, script programming language, and script level debugging. Data acquisition system devices can be controlled through IEEE488 board, multifunction I/O board, digitalmore » I/O board and Gespac crate via Euro G-64 bus. GPDAS is now being used for diagnostics R D and accelerator physics studies as well as for magnet measurements. Their hardware configurations will also be discussed. 3 refs., 3 figs.« less

Fast Time-Dependent Density Functional Theory Calculations of the X-ray Absorption Spectroscopy of Large Systems.

PubMed

Besley, Nicholas A

2016-10-11

The computational cost of calculations of K-edge X-ray absorption spectra using time-dependent density functional (TDDFT) within the Tamm-Dancoff approximation is significantly reduced through the introduction of a severe integral screening procedure that includes only integrals that involve the core s basis function of the absorbing atom(s) coupled with a reduced quality numerical quadrature for integrals associated with the exchange and correlation functionals. The memory required for the calculations is reduced through construction of the TDDFT matrix within the absorbing core orbitals excitation space and exploiting further truncation of the virtual orbital space. The resulting method, denoted fTDDFTs, leads to much faster calculations and makes the study of large systems tractable. The capability of the method is demonstrated through calculations of the X-ray absorption spectra at the carbon K-edge of chlorophyll a, C 60 and C 70 .

Context-aware distributed cloud computing using CloudScheduler

NASA Astrophysics Data System (ADS)

Seuster, R.; Leavett-Brown, CR; Casteels, K.; Driemel, C.; Paterson, M.; Ring, D.; Sobie, RJ; Taylor, RP; Weldon, J.

2017-10-01

The distributed cloud using the CloudScheduler VM provisioning service is one of the longest running systems for HEP workloads. It has run millions of jobs for ATLAS and Belle II over the past few years using private and commercial clouds around the world. Our goal is to scale the distributed cloud to the 10,000-core level, with the ability to run any type of application (low I/O, high I/O and high memory) on any cloud. To achieve this goal, we have been implementing changes that utilize context-aware computing designs that are currently employed in the mobile communication industry. Context-awareness makes use of real-time and archived data to respond to user or system requirements. In our distributed cloud, we have many opportunistic clouds with no local HEP services, software or storage repositories. A context-aware design significantly improves the reliability and performance of our system by locating the nearest location of the required services. We describe how we are collecting and managing contextual information from our workload management systems, the clouds, the virtual machines and our services. This information is used not only to monitor the system but also to carry out automated corrective actions. We are incrementally adding new alerting and response services to our distributed cloud. This will enable us to scale the number of clouds and virtual machines. Further, a context-aware design will enable us to run analysis or high I/O application on opportunistic clouds. We envisage an open-source HTTP data federation (for example, the DynaFed system at CERN) as a service that would provide us access to existing storage elements used by the HEP experiments.

D Modeling for the Knowledge of Architectural Heritage and Virtual Reconstruction of its Historical Memory

NASA Astrophysics Data System (ADS)

Campi, M.; di Luggo, A.; Scandurra, S.

2017-02-01

The object of this paper is one of the most ancient palaces of Naples, Palazzo Penne, a fourteenth-century residential building located on a small high ground which originally was in the outer fringe of the built up area in a privileged position enabling to enjoy the landscape and gulf beauty. This building, which today is in the heart of the historical center, was the subject of an extensive analysis and documentary research, as well as of metric laser scanner survey carried out by the group researchers working at the Interdepartmental Centre of Research Urban Eco of the University of Naples Federico II. Starting from scan to bim systems the creation of a parametric model of the current state of the building is completed, by bringing the point cloud elements back to objects to which historical and construction data can be associated. Moreover starting from acquired data, the 3D model shows the reconstructive hypothesis of the original structure and the virtual reconstruction of the building based on traces found on-site and on the comparison with coeval creations allowing to properly hypothesize the design of point features.

Fast software-based volume rendering using multimedia instructions on PC platforms and its application to virtual endoscopy

NASA Astrophysics Data System (ADS)

Mori, Kensaku; Suenaga, Yasuhito; Toriwaki, Jun-ichiro

2003-05-01

This paper describes a software-based fast volume rendering (VolR) method on a PC platform by using multimedia instructions, such as SIMD instructions, which are currently available in PCs' CPUs. This method achieves fast rendering speed through highly optimizing software rather than an improved rendering algorithm. In volume rendering using a ray casting method, the system requires fast execution of the following processes: (a) interpolation of voxel or color values at sample points, (b) computation of normal vectors (gray-level gradient vectors), (c) calculation of shaded values obtained by dot-products of normal vectors and light source direction vectors, (d) memory access to a huge area, and (e) efficient ray skipping at translucent regions. The proposed software implements these fundamental processes in volume rending by using special instruction sets for multimedia processing. The proposed software can generate virtual endoscopic images of a 3-D volume of 512x512x489 voxel size by volume rendering with perspective projection, specular reflection, and on-the-fly normal vector computation on a conventional PC without any special hardware at thirteen frames per second. Semi-translucent display is also possible.

Acute effects of alcohol on intrusive memory development and viewpoint dependence in spatial memory support a dual representation model.

PubMed

Bisby, James A; King, John A; Brewin, Chris R; Burgess, Neil; Curran, H Valerie

2010-08-01

A dual representation model of intrusive memory proposes that personally experienced events give rise to two types of representation: an image-based, egocentric representation based on sensory-perceptual features; and a more abstract, allocentric representation that incorporates spatiotemporal context. The model proposes that intrusions reflect involuntary reactivation of egocentric representations in the absence of a corresponding allocentric representation. We tested the model by investigating the effect of alcohol on intrusive memories and, concurrently, on egocentric and allocentric spatial memory. With a double-blind independent group design participants were administered alcohol (.4 or .8 g/kg) or placebo. A virtual environment was used to present objects and test recognition memory from the same viewpoint as presentation (tapping egocentric memory) or a shifted viewpoint (tapping allocentric memory). Participants were also exposed to a trauma video and required to detail intrusive memories for 7 days, after which explicit memory was assessed. There was a selective impairment of shifted-view recognition after the low dose of alcohol, whereas the high dose induced a global impairment in same-view and shifted-view conditions. Alcohol showed a dose-dependent inverted "U"-shaped effect on intrusions, with only the low dose increasing the number of intrusions, replicating previous work. When same-view recognition was intact, decrements in shifted-view recognition were associated with increases in intrusions. The differential effect of alcohol on intrusive memories and on same/shifted-view recognition support a dual representation model in which intrusions might reflect an imbalance between two types of memory representation. These findings highlight important clinical implications, given alcohol's involvement in real-life trauma. Copyright 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Efficient Generation and Selection of Virtual Populations in Quantitative Systems Pharmacology Models

PubMed Central

Rieger, TR; Musante, CJ

2016-01-01

Quantitative systems pharmacology models mechanistically describe a biological system and the effect of drug treatment on system behavior. Because these models rarely are identifiable from the available data, the uncertainty in physiological parameters may be sampled to create alternative parameterizations of the model, sometimes termed “virtual patients.” In order to reproduce the statistics of a clinical population, virtual patients are often weighted to form a virtual population that reflects the baseline characteristics of the clinical cohort. Here we introduce a novel technique to efficiently generate virtual patients and, from this ensemble, demonstrate how to select a virtual population that matches the observed data without the need for weighting. This approach improves confidence in model predictions by mitigating the risk that spurious virtual patients become overrepresented in virtual populations. PMID:27069777

Improving prospective memory in persons with Parkinson disease: A randomized controlled trial

PubMed Central

Foster, Erin R.; McDaniel, Mark A.; Rendell, Peter G.

2017-01-01

Background Prospective memory is essential for productive and independent living and necessary for compliance with prescribed health behaviors. Parkinson disease (PD) can cause prospective memory deficits that are associated with activity limitations and reduced quality of life. Forming implementation intentions is an encoding strategy that may improve prospective memory in this population. Objective To determine the effect of implementation intentions on prospective memory performance in PD. Methods This was a laboratory-based randomized controlled trial. Participants with mild to moderate PD without dementia (N = 62) performed a computerized prospective memory test (Virtual Week) under standard instructions. One week later they were randomly allocated to perform it again while using either implementation intentions or a rehearsal encoding strategy. Results Prospective memory performance was better with the use of both strategies relative to standard instructions. This effect was larger for tasks with event-based compared to time-based cues. In addition, implementation intentions resulted in a larger effect than rehearsal for the non-repeated tasks. Conclusions Strategies that support full encoding of prospective memory cues and actions can improve prospective memory performance among people with PD, particularly for tasks with cues that are readily available in the environment. Implementation intentions may be more effective than rehearsal for non-repeated tasks, but this finding warrants verification. Future work should address transfer of strategy use from the laboratory to everyday life. Targeted strategies to manage prospective memory impairment could improve function and quality of life and significantly impact clinical care for people with PD. (NCT01469741) PMID:28176547

Your Family Land: Legacy or Memory? An Introduction to the Family Land Protection Process

Treesearch

USDA Forest Service, Northeastern Area, State and Private Forestry

2008-01-01

If you have this perspective, protecting your land from development is a task you certainly can accomplish. Virtually every situation is workable and every problem can be solved. It does require some planning and decisionmaking; however, so the sooner you start the better. Experience has shown that the number one obstacle to the protection of family land...

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

ERIC Educational Resources Information Center

von Stulpnagel, Rul; Steffens, Melanie C.

2012-01-01

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

High-gamma activity in the human hippocampus and parahippocampus during inter-trial rest periods of a virtual navigation task.

PubMed

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

2018-05-19

In rodents, hippocampal cell assemblies formed during learning of a navigation task are observed to re-emerge during resting (offline) periods, accompanied by high-frequency oscillations (HFOs). This phenomenon is believed to reflect mechanisms for strengthening newly-formed memory traces. Using magnetoencephalography recordings and a beamforming source location algorithm (synthetic aperture magnetometry), we investigated high-gamma (80-140 Hz) oscillations in the hippocampal region in 18 human participants during inter-trial rest periods in a virtual navigation task. We found right hippocampal gamma oscillations mirrored the pattern of theta power in the same region during navigation, varying as a function of environmental novelty. Gamma power during inter-trial rest periods was positively correlated with theta power during navigation in the first task set when the environment was new and predicted greater performance improvement in the subsequent task set two where the environment became familiar. These findings provide evidence for human hippocampal reactivation accompanied by high-gamma activities immediately after learning and establish a link between hippocampal high-gamma activities and subsequent memory performance. Copyright © 2018 Elsevier Inc. All rights reserved.

Sex differences in a virtual water maze: an eye tracking and pupillometry study.

PubMed

Mueller, Sven C; Jackson, Carl P T; Skelton, Ron W

2008-11-21

Sex differences in human spatial navigation are well known. However, the exact strategies that males and females employ in order to navigate successfully around the environment are unclear. While some researchers propose that males prefer environment-centred (allocentric) and females prefer self-centred (egocentric) navigation, these findings have proved difficult to replicate. In the present study we examined eye movements and physiological measures of memory (pupillometry) in order to compare visual scanning of spatial orientation using a human virtual analogue of the Morris Water Maze task. Twelve women and twelve men (average age=24 years) were trained on a visible platform and had to locate an invisible platform over a series of trials. On all but the first trial, participants' eye movements were recorded for 3s and they were asked to orient themselves in the environment. While the behavioural data replicated previous findings of improved spatial performance for males relative to females, distinct sex differences in eye movements were found. Males tended to explore consistently more space early on while females demonstrated initially longer fixation durations and increases in pupil diameter usually associated with memory processing. The eye movement data provides novel insight into differences in navigational strategies between the sexes.

Reconstituted Three-Dimensional Interactive Imaging

NASA Technical Reports Server (NTRS)

Hamilton, Joseph; Foley, Theodore; Duncavage, Thomas; Mayes, Terrence

2010-01-01

A method combines two-dimensional images, enhancing the images as well as rendering a 3D, enhanced, interactive computer image or visual model. Any advanced compiler can be used in conjunction with any graphics library package for this method, which is intended to take digitized images and virtually stack them so that they can be interactively viewed as a set of slices. This innovation can take multiple image sources (film or digital) and create a "transparent" image with higher densities in the image being less transparent. The images are then stacked such that an apparent 3D object is created in virtual space for interactive review of the set of images. This innovation can be used with any application where 3D images are taken as slices of a larger object. These could include machines, materials for inspection, geological objects, or human scanning. Illuminous values were stacked into planes with different transparency levels of tissues. These transparency levels can use multiple energy levels, such as density of CT scans or radioactive density. A desktop computer with enough video memory to produce the image is capable of this work. The memory changes with the size and resolution of the desired images to be stacked and viewed.

Virtual Treatment of Basilar Aneurysms Using Shape Memory Polymer Foam

PubMed Central

Ortega, J.M.; Hartman, J.; Rodriguez, J.N.; Maitland, D.J.

2013-01-01

Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present within the pre-treatment aneurysms. An estimation of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The Newtonian viscosity model and the porous media model capture similar qualitative trends, though both yield a smaller volume of thrombus within the SMP foam. PMID:23329002

Virtual Treatment of Basilar Aneurysms Using Shape Memory Polymer Foam

NASA Astrophysics Data System (ADS)

Ortega, J. M.; Hartman, J.; Rodriguez, J. N.; Maitland, D. J.

2012-11-01

Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present prior to treatment. A prediction of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The two modeling approaches capture similar qualitative trends for the initial locations of thrombus within the SMP foam.

System-Level Virtualization for High Performance Computing

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

Vallee, Geoffroy R; Naughton, III, Thomas J; Engelmann, Christian

2008-01-01

System-level virtualization has been a research topic since the 70's but regained popularity during the past few years because of the availability of efficient solution such as Xen and the implementation of hardware support in commodity processors (e.g. Intel-VT, AMD-V). However, a majority of system-level virtualization projects is guided by the server consolidation market. As a result, current virtualization solutions appear to not be suitable for high performance computing (HPC) which is typically based on large-scale systems. On another hand there is significant interest in exploiting virtual machines (VMs) within HPC for a number of other reasons. By virtualizing themore » machine, one is able to run a variety of operating systems and environments as needed by the applications. Virtualization allows users to isolate workloads, improving security and reliability. It is also possible to support non-native environments and/or legacy operating environments through virtualization. In addition, it is possible to balance work loads, use migration techniques to relocate applications from failing machines, and isolate fault systems for repair. This document presents the challenges for the implementation of a system-level virtualization solution for HPC. It also presents a brief survey of the different approaches and techniques to address these challenges.« less

Novel virtual reality system integrating online self-face viewing and mirror visual feedback for stroke rehabilitation: rationale and feasibility.

PubMed

Shiri, Shimon; Feintuch, Uri; Lorber-Haddad, Adi; Moreh, Elior; Twito, Dvora; Tuchner-Arieli, Maya; Meiner, Zeev

2012-01-01

To introduce the rationale of a novel virtual reality system based on self-face viewing and mirror visual feedback, and to examine its feasibility as a rehabilitation tool for poststroke patients. A novel motion capture virtual reality system integrating online self-face viewing and mirror visual feedback has been developed for stroke rehabilitation.The system allows the replacement of the impaired arm by a virtual arm. Upon making small movements of the paretic arm, patients view themselves virtually performing healthy full-range movements. A sample of 6 patients in the acute poststroke phase received the virtual reality treatment concomitantly with conservative rehabilitation treatment. Feasibility was assessed during 10 sessions for each participant. All participants succeeded in operating the system, demonstrating its feasibility in terms of adherence and improvement in task performance. Patients' performance within the virtual environment and a set of clinical-functional measures recorded before the virtual reality treatment, at 1 week, and after 3 months indicated neurological status and general functioning improvement. These preliminary results indicate that this newly developed virtual reality system is safe and feasible. Future randomized controlled studies are required to assess whether this system has beneficial effects in terms of enhancing upper limb function and quality of life in poststroke patients.

Memory-based snowdrift game on a square lattice

NASA Astrophysics Data System (ADS)

Shu, Feng; Liu, Xingwen; Fang, Kai; Chen, Hao

2018-04-01

Spatial reciprocity is an effective way widely accepted to facilitate cooperation. In the case of snowdrift game, some researches showed that spatial reciprocity inhibits cooperation for a very wide range of cost-to-benefit ratio r. However, some other researches found that based on the spatial reciprocity, a wider range of r is helpful to achieve a high cooperation level. Thus, how to enlarge the range of r for the purpose of promoting cooperation becomes a hot topic recently. This paper proposes a new memory-based method, in which each individual compares with its own previous payoffs to find out the maximal one as virtual payoff and then randomly compares with one of its neighbours to obtain the optimal strategy according to the given updating rules. It shows the positive effect of spatial reciprocity in the context of memory. Specifically, in this situation, not only the lower ratio can appear a high cooperation level, but also the larger ratio r can emerge a high cooperation level. That is, an expected cooperation level can be achieved simultaneously for small and large r. Furthermore, the scenarios of both constant-size memory and size-varying memory are investigated. An interesting phenomenon is discovered that the cooperation level drops down gradually as the memory size increases.

Ghrelin modulates encoding-related brain function without enhancing memory formation in humans.

PubMed

Kunath, N; Müller, N C J; Tonon, M; Konrad, B N; Pawlowski, M; Kopczak, A; Elbau, I; Uhr, M; Kühn, S; Repantis, D; Ohla, K; Müller, T D; Fernández, G; Tschöp, M; Czisch, M; Steiger, A; Dresler, M

2016-11-15

Ghrelin regulates energy homeostasis in various species and enhances memory in rodent models. In humans, the role of ghrelin in cognitive processes has yet to be characterized. Here we show in a double-blind randomized crossover design that acute administration of ghrelin alters encoding-related brain activity, however does not enhance memory formation in humans. Twenty-one healthy young male participants had to memorize food- and non-food-related words presented on a background of a virtual navigational route while undergoing fMRI recordings. After acute ghrelin administration, we observed decreased post-encoding resting state fMRI connectivity between the caudate nucleus and the insula, amygdala, and orbitofrontal cortex. In addition, brain activity related to subsequent memory performance was modulated by ghrelin. On the next day, however, no differences were found in free word recall or cued location-word association recall between conditions; and ghrelin's effects on brain activity or functional connectivity were unrelated to memory performance. Further, ghrelin had no effect on a cognitive test battery comprising tests for working memory, fluid reasoning, creativity, mental speed, and attention. In conclusion, in contrast to studies with animal models, we did not find any evidence for the potential of ghrelin acting as a short-term cognitive enhancer in humans. Copyright © 2016 Elsevier Inc. All rights reserved.

Overview of the land analysis system (LAS)

USGS Publications Warehouse

Quirk, Bruce K.; Olseson, Lyndon R.

1987-01-01

The Land Analysis System (LAS) is a fully integrated digital analysis system designed to support remote sensing, image processing, and geographic information systems research. LAS is being developed through a cooperative effort between the National Aeronautics and Space Administration Goddard Space Flight Center and the U. S. Geological Survey Earth Resources Observation Systems (EROS) Data Center. LAS has over 275 analysis modules capable to performing input and output, radiometric correction, geometric registration, signal processing, logical operations, data transformation, classification, spatial analysis, nominal filtering, conversion between raster and vector data types, and display manipulation of image and ancillary data. LAS is currently implant using the Transportable Applications Executive (TAE). While TAE was designed primarily to be transportable, it still provides the necessary components for a standard user interface, terminal handling, input and output services, display management, and intersystem communications. With TAE the analyst uses the same interface to the processing modules regardless of the host computer or operating system. LAS was originally implemented at EROS on a Digital Equipment Corporation computer system under the Virtual Memorial System operating system with DeAnza displays and is presently being converted to run on a Gould Power Node and Sun workstation under the Berkeley System Distribution UNIX operating system.

Facilitating role of 3D multimodal visualization and learning rehearsal in memory recall.

PubMed

Do, Phuong T; Moreland, John R

2014-04-01

The present study investigated the influence of 3D multimodal visualization and learning rehearsal on memory recall. Participants (N = 175 college students ranging from 21 to 25 years) were assigned to different training conditions and rehearsal processes to learn a list of 14 terms associated with construction of a wood-frame house. They then completed a memory test determining their cognitive ability to free recall the definitions of the 14 studied terms immediately after training and rehearsal. The audiovisual modality training condition was associated with the highest accuracy, and the visual- and auditory-modality conditions with lower accuracy rates. The no-training condition indicated little learning acquisition. A statistically significant increase in performance accuracy for the audiovisual condition as a function of rehearsal suggested the relative importance of rehearsal strategies in 3D observational learning. Findings revealed the potential application of integrating virtual reality and cognitive sciences to enhance learning and teaching effectiveness.

Effects of cue types on sex differences in human spatial memory.

PubMed

Chai, Xiaoqian J; Jacobs, Lucia F

2010-04-02

We examined the effects of cue types on human spatial memory in 3D virtual environments adapted from classical animal and human tasks. Two classes of cues of different functions were investigated: those that provide directional information, and those that provide positional information. Adding a directional cue (geographical slant) to the spatial delayed-match-to-sample task improved performance in males but not in females. When the slant directional cue was removed in a hidden-target location task, male performance was impaired but female performance was unaffected. The removal of positional cues, on the other hand, impaired female performance but not male performance. These results are consistent with results from laboratory rodents and thus support the hypothesis that sex differences in spatial memory arise from the dissociation between a preferential reliance on directional cues in males and on positional cues in females. Copyright 2009 Elsevier B.V. All rights reserved.

[Method of file sorting for mini- and microcomputers].

PubMed

Chau, N; Legras, B; Benamghar, L; Martin, J

1983-05-01

The authors describe a new sorting method of files which belongs to the class of direct-addressing sorting methods. It makes use of a variant of the classical technique of 'virtual memory'. It is particularly well suited to mini- and micro-computers which have a small core memory (32 K words, for example) and are fitted with a direct-access peripheral device, such as a disc unit. When the file to be sorted is medium-sized (some thousand records), the running of the program essentially occurs inside the core memory and consequently, the method becomes very fast. This is very important because most medical files handled in our laboratory are in this category. However, the method is also suitable for big computers and large files; its implementation is easy. It does not require any magnetic tape unit, and it seems to us to be one of the fastest methods available.

Novel interactive virtual showcase based on 3D multitouch technology

NASA Astrophysics Data System (ADS)

Yang, Tao; Liu, Yue; Lu, You; Wang, Yongtian

2009-11-01

A new interactive virtual showcase is proposed in this paper. With the help of virtual reality technology, the user of the proposed system can watch the virtual objects floating in the air from all four sides and interact with the virtual objects by touching the four surfaces of the virtual showcase. Unlike traditional multitouch system, this system cannot only realize multi-touch on a plane to implement 2D translation, 2D scaling, and 2D rotation of the objects; it can also realize the 3D interaction of the virtual objects by recognizing and analyzing the multi-touch that can be simultaneously captured from the four planes. Experimental results show the potential of the proposed system to be applied in the exhibition of historical relics and other precious goods.

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.

The impact of sleep on true and false memory across long delays.

PubMed

Pardilla-Delgado, Enmanuelle; Payne, Jessica D

2017-01-01

While the influence of sleep on memory has a long history, sleep's role in the formation of false memories is less clear. Moreover, virtually nothing is known about the development of false memories beyond delays of about 12h. Here, for the first time, we assess post-sleep development of true and false memories across longer delay intervals of 24 and 48h. Although technically a false memory, remembering information that is related to the theme, or gist, of an experience can be considered an adaptive process. Some evidence suggests that sleep, compared to a wake period, increases both true and gist-based false memories in the Deese-Roediger-McDermott (DRM) task, but not all studies have returned this result, and most studies cannot rule out the possibility that sleep is merely protecting the information from interference, as opposed to actively aiding its consolidation. Here, to equate amount of time spent awake and asleep across groups, we assess how the positioning of sleep relative to memory encoding impacts retention across longer delays of 24 and 48h. Participants encoded 16 DRM lists in the morning (WAKE 1st Groups) or evening (SLEEP 1st Groups), and were tested either 24 or 48h later at the same time of day. Results demonstrate that true memory is better when participants sleep soon after learning. Sleeping first also increased false memory, but only in low performers. Importantly, and similar to previous studies, we found a negative correlation between slow-wave sleep (SWS) and false memory, suggesting that SWS may be detrimental for semantic/gist processing. Copyright © 2016 Elsevier Inc. All rights reserved.

Normal aging affects movement execution but not visual motion working memory and decision-making delay during cue-dependent memory-based smooth-pursuit.

PubMed

Fukushima, Kikuro; Barnes, Graham R; Ito, Norie; Olley, Peter M; Warabi, Tateo

2014-07-01

Aging affects virtually all functions including sensory/motor and cognitive activities. While retinal image motion is the primary input for smooth-pursuit, its efficiency/accuracy depends on cognitive processes. Elderly subjects exhibit gain decrease during initial and steady-state pursuit, but reports on latencies are conflicting. Using a cue-dependent memory-based smooth-pursuit task, we identified important extra-retinal mechanisms for initial pursuit in young adults including cue information priming and extra-retinal drive components (Ito et al. in Exp Brain Res 229:23-35, 2013). We examined aging effects on parameters for smooth-pursuit using the same tasks. Elderly subjects were tested during three task conditions as previously described: memory-based pursuit, simple ramp-pursuit just to follow motion of a single spot, and popping-out of the correct spot during memory-based pursuit to enhance retinal image motion. Simple ramp-pursuit was used as a task that did not require visual motion working memory. To clarify aging effects, we then compared the results with the previous young subject data. During memory-based pursuit, elderly subjects exhibited normal working memory of cue information. Most movement-parameters including pursuit latencies differed significantly between memory-based pursuit and simple ramp-pursuit and also between young and elderly subjects. Popping-out of the correct spot motion was ineffective for enhancing initial pursuit in elderly subjects. However, the latency difference between memory-based pursuit and simple ramp-pursuit in individual subjects, which includes decision-making delay in the memory task, was similar between the two groups. Our results suggest that smooth-pursuit latencies depend on task conditions and that, although the extra-retinal mechanisms were functional for initial pursuit in elderly subjects, they were less effective.

Disambiguating past events: Accurate source memory for time and context depends on different retrieval processes.

PubMed

Persson, Bjorn M; Ainge, James A; O'Connor, Akira R

2016-07-01

Current animal models of episodic memory are usually based on demonstrating integrated memory for what happened, where it happened, and when an event took place. These models aim to capture the testable features of the definition of human episodic memory which stresses the temporal component of the memory as a unique piece of source information that allows us to disambiguate one memory from another. Recently though, it has been suggested that a more accurate model of human episodic memory would include contextual rather than temporal source information, as humans' memory for time is relatively poor. Here, two experiments were carried out investigating human memory for temporal and contextual source information, along with the underlying dual process retrieval processes, using an immersive virtual environment paired with a 'Remember-Know' memory task. Experiment 1 (n=28) showed that contextual information could only be retrieved accurately using recollection, while temporal information could be retrieved using either recollection or familiarity. Experiment 2 (n=24), which used a more difficult task, resulting in reduced item recognition rates and therefore less potential for contamination by ceiling effects, replicated the pattern of results from Experiment 1. Dual process theory predicts that it should only be possible to retrieve source context from an event using recollection, and our results are consistent with this prediction. That temporal information can be retrieved using familiarity alone suggests that it may be incorrect to view temporal context as analogous to other typically used source contexts. This latter finding supports the alternative proposal that time since presentation may simply be reflected in the strength of memory trace at retrieval - a measure ideally suited to trace strength interrogation using familiarity, as is typically conceptualised within the dual process framework. Copyright © 2016 Elsevier Inc. All rights reserved.

VLSI Design of Trusted Virtual Sensors.

PubMed

Martínez-Rodríguez, Macarena C; Prada-Delgado, Miguel A; Brox, Piedad; Baturone, Iluminada

2018-01-25

This work presents a Very Large Scale Integration (VLSI) design of trusted virtual sensors providing a minimum unitary cost and very good figures of size, speed and power consumption. The sensed variable is estimated by a virtual sensor based on a configurable and programmable PieceWise-Affine hyper-Rectangular (PWAR) model. An algorithm is presented to find the best values of the programmable parameters given a set of (empirical or simulated) input-output data. The VLSI design of the trusted virtual sensor uses the fast authenticated encryption algorithm, AEGIS, to ensure the integrity of the provided virtual measurement and to encrypt it, and a Physical Unclonable Function (PUF) based on a Static Random Access Memory (SRAM) to ensure the integrity of the sensor itself. Implementation results of a prototype designed in a 90-nm Complementary Metal Oxide Semiconductor (CMOS) technology show that the active silicon area of the trusted virtual sensor is 0.86 mm 2 and its power consumption when trusted sensing at 50 MHz is 7.12 mW. The maximum operation frequency is 85 MHz, which allows response times lower than 0.25 μ s. As application example, the designed prototype was programmed to estimate the yaw rate in a vehicle, obtaining root mean square errors lower than 1.1%. Experimental results of the employed PUF show the robustness of the trusted sensing against aging and variations of the operation conditions, namely, temperature and power supply voltage (final value as well as ramp-up time).

VLSI Design of Trusted Virtual Sensors

PubMed Central

2018-01-01

This work presents a Very Large Scale Integration (VLSI) design of trusted virtual sensors providing a minimum unitary cost and very good figures of size, speed and power consumption. The sensed variable is estimated by a virtual sensor based on a configurable and programmable PieceWise-Affine hyper-Rectangular (PWAR) model. An algorithm is presented to find the best values of the programmable parameters given a set of (empirical or simulated) input-output data. The VLSI design of the trusted virtual sensor uses the fast authenticated encryption algorithm, AEGIS, to ensure the integrity of the provided virtual measurement and to encrypt it, and a Physical Unclonable Function (PUF) based on a Static Random Access Memory (SRAM) to ensure the integrity of the sensor itself. Implementation results of a prototype designed in a 90-nm Complementary Metal Oxide Semiconductor (CMOS) technology show that the active silicon area of the trusted virtual sensor is 0.86 mm2 and its power consumption when trusted sensing at 50 MHz is 7.12 mW. The maximum operation frequency is 85 MHz, which allows response times lower than 0.25 μs. As application example, the designed prototype was programmed to estimate the yaw rate in a vehicle, obtaining root mean square errors lower than 1.1%. Experimental results of the employed PUF show the robustness of the trusted sensing against aging and variations of the operation conditions, namely, temperature and power supply voltage (final value as well as ramp-up time). PMID:29370141

Free Energy and Virtual Reality in Neuroscience and Psychoanalysis: A Complexity Theory of Dreaming and Mental Disorder.

PubMed

Hopkins, Jim

2016-01-01

The main concepts of the free energy (FE) neuroscience developed by Karl Friston and colleagues parallel those of Freud's Project for a Scientific Psychology. In Hobson et al. (2014) these include an innate virtual reality generator that produces the fictive prior beliefs that Freud described as the primary process. This enables Friston's account to encompass a unified treatment-a complexity theory-of the role of virtual reality in both dreaming and mental disorder. In both accounts the brain operates to minimize FE aroused by sensory impingements-including interoceptive impingements that report compliance with biological imperatives-and constructs a representation/model of the causes of impingement that enables this minimization. In Friston's account (variational) FE equals complexity minus accuracy, and is minimized by increasing accuracy and decreasing complexity. Roughly the brain (or model) increases accuracy together with complexity in waking. This is mediated by consciousness-creating active inference-by which it explains sensory impingements in terms of perceptual experiences of their causes. In sleep it reduces complexity by processes that include both synaptic pruning and consciousness/virtual reality/dreaming in REM. The consciousness-creating active inference that effects complexity-reduction in REM dreaming must operate on FE-arousing data distinct from sensory impingement. The most relevant source is remembered arousals of emotion, both recent and remote, as processed in SWS and REM on "active systems" accounts of memory consolidation/reconsolidation. Freud describes these remembered arousals as condensed in the dreamwork for use in the conscious contents of dreams, and similar condensation can be seen in symptoms. Complexity partly reflects emotional conflict and trauma. This indicates that dreams and symptoms are both produced to reduce complexity in the form of potentially adverse (traumatic or conflicting) arousals of amygdala-related emotions. Mental disorder is thus caused by computational complexity together with mechanisms like synaptic pruning that have evolved for complexity-reduction; and important features of disorder can be understood in these terms. Details of the consilience among Freudian, systems consolidation, and complexity-reduction accounts appear clearly in the analysis of a single fragment of a dream, indicating also how complexity reduction proceeds by a process resembling Bayesian model selection.

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.

Methods and systems relating to an augmented virtuality environment

DOEpatents

Nielsen, Curtis W; Anderson, Matthew O; McKay, Mark D; Wadsworth, Derek C; Boyce, Jodie R; Hruska, Ryan C; Koudelka, John A; Whetten, Jonathan; Bruemmer, David J

2014-05-20

Systems and methods relating to an augmented virtuality system are disclosed. A method of operating an augmented virtuality system may comprise displaying imagery of a real-world environment in an operating picture. The method may further include displaying a plurality of virtual icons in the operating picture representing at least some assets of a plurality of assets positioned in the real-world environment. Additionally, the method may include displaying at least one virtual item in the operating picture representing data sensed by one or more of the assets of the plurality of assets and remotely controlling at least one asset of the plurality of assets by interacting with a virtual icon associated with the at least one asset.

[Chronic atrophic gastritis: endoscopic and histological concordances, associated injuries and application of virtual chromoendoscopy].

PubMed

Liu Bejarano, Humberto

2011-01-01

Due to the poor agreement between endoscopy and histology, the gastric biopsy continues being the gold standard for the diagnosis of atrophic chronic gastritis. The Virtual chromoendoscopy system allows better observation of the gastric mucosa. Evaluate the agreement between the Kimura-Takemoto ´s endoscopic system classification and the histological system of OLGA (Operative for Link Assessment Gastritis), as well as to evaluate the application of the virtual chromoendoscopy. A prospective and longitudinal study of cohorts, 138 patients was include, using endoscopic system of atrophy by Kimura and Takemoto (K-T), with conventional optical and with the use of seventh filter of virtual chromoendoscopy ,then comparing with the histological findings of the OLGA pathology system, also were determinated injuries associated with respect to stage OLGA. The kappa index of agreement between conventional endoscopy and the system OLGA was 0.859 and with the system of virtual chromoendoscopy was 0.822, the preneoplasic and neoplastic gastric lesions were associate to stages III and IV of atrophy. The endoscopic and histological correlation with both systems isvery good, with or without the use of virtual chromoendoscopy. chronic atrophic gastritis, virtual chromoendoscopy, olga system, , kimuratakemoto system.

Network-Capable Application Process and Wireless Intelligent Sensors for ISHM

NASA Technical Reports Server (NTRS)

Figueroa, Fernando; Morris, Jon; Turowski, Mark; Wang, Ray

2011-01-01

Intelligent sensor technology and systems are increasingly becoming attractive means to serve as frameworks for intelligent rocket test facilities with embedded intelligent sensor elements, distributed data acquisition elements, and onboard data acquisition elements. Networked intelligent processors enable users and systems integrators to automatically configure their measurement automation systems for analog sensors. NASA and leading sensor vendors are working together to apply the IEEE 1451 standard for adding plug-and-play capabilities for wireless analog transducers through the use of a Transducer Electronic Data Sheet (TEDS) in order to simplify sensor setup, use, and maintenance, to automatically obtain calibration data, and to eliminate manual data entry and error. A TEDS contains the critical information needed by an instrument or measurement system to identify, characterize, interface, and properly use the signal from an analog sensor. A TEDS is deployed for a sensor in one of two ways. First, the TEDS can reside in embedded, nonvolatile memory (typically flash memory) within the intelligent processor. Second, a virtual TEDS can exist as a separate file, downloadable from the Internet. This concept of virtual TEDS extends the benefits of the standardized TEDS to legacy sensors and applications where the embedded memory is not available. An HTML-based user interface provides a visual tool to interface with those distributed sensors that a TEDS is associated with, to automate the sensor management process. Implementing and deploying the IEEE 1451.1-based Network-Capable Application Process (NCAP) can achieve support for intelligent process in Integrated Systems Health Management (ISHM) for the purpose of monitoring, detection of anomalies, diagnosis of causes of anomalies, prediction of future anomalies, mitigation to maintain operability, and integrated awareness of system health by the operator. It can also support local data collection and storage. This invention enables wide-area sensing and employs numerous globally distributed sensing devices that observe the physical world through the existing sensor network. This innovation enables distributed storage, distributed processing, distributed intelligence, and the availability of DiaK (Data, Information, and Knowledge) to any element as needed. It also enables the simultaneous execution of multiple processes, and represents models that contribute to the determination of the condition and health of each element in the system. The NCAP (intelligent process) can configure data-collection and filtering processes in reaction to sensed data, allowing it to decide when and how to adapt collection and processing with regard to sophisticated analysis of data derived from multiple sensors. The user will be able to view the sensing device network as a single unit that supports a high-level query language. Each query would be able to operate over data collected from across the global sensor network just as a search query encompasses millions of Web pages. The sensor web can preserve ubiquitous information access between the querier and the queried data. Pervasive monitoring of the physical world raises significant data and privacy concerns. This innovation enables different authorities to control portions of the sensing infrastructure, and sensor service authors may wish to compose services across authority boundaries.

Effect of the adapted Virtual Reality cognitive training program among Chinese older adults with chronic schizophrenia: a pilot study.

PubMed

Chan, Christopher L F; Ngai, Elena K Y; Leung, Paul K H; Wong, Stephen

2010-06-01

To examine the effect of the adapted virtual reality cognitive training program in older adults with chronic schizophrenia. Older adults with chronic schizophrenia were recruited from a long-stay care setting and were randomly assigned into intervention (n = 12) and control group (n = 15). The intervention group received 10-session of VR program that consisted of 2 VR activities using IREX. The control group attended the usual programs in the setting. After the 10-session intervention, older adults with chronic schizophrenia preformed significantly better than control in overall cognitive function (p .000), and in two cognitive subscales: repetition (p .001) and memory (p .040). These participants engaged in the VR activities volitionally. No problem of cybersickness was observed. The results of the current study indicate that engaging in the adapted virtual reality cognitive training program offers the potential for significant gains in cognitive function of the older adults with chronic schizophrenia.

A VM-shared desktop virtualization system based on OpenStack

NASA Astrophysics Data System (ADS)

Liu, Xi; Zhu, Mingfa; Xiao, Limin; Jiang, Yuanjie

2018-04-01

With the increasing popularity of cloud computing, desktop virtualization is rising in recent years as a branch of virtualization technology. However, existing desktop virtualization systems are mostly designed as a one-to-one mode, which one VM can only be accessed by one user. Meanwhile, previous desktop virtualization systems perform weakly in terms of response time and cost saving. This paper proposes a novel VM-Shared desktop virtualization system based on OpenStack platform. The paper modified the connecting process and the display data transmission process of the remote display protocol SPICE to support VM-Shared function. On the other hand, we propose a server-push display mode to improve user interactive experience. The experimental results show that our system performs well in response time and achieves a low CPU consumption.

A modular, programmable measurement system for physiological and spaceflight applications

NASA Technical Reports Server (NTRS)

Hines, John W.; Ricks, Robert D.; Miles, Christopher J.

1993-01-01

The NASA-Ames Sensors 2000! Program has developed a small, compact, modular, programmable, sensor signal conditioning and measurement system, initially targeted for Life Sciences Spaceflight Programs. The system consists of a twelve-slot, multi-layer, distributed function backplane, a digital microcontroller/memory subsystem, conditioned and isolated power supplies, and six application-specific, physiological signal conditioners. Each signal condition is capable of being programmed for gains, offsets, calibration and operate modes, and, in some cases, selectable outputs and functional modes. Presently, the system has the capability for measuring ECG, EMG, EEG, Temperature, Respiration, Pressure, Force, and Acceleration parameters, in physiological ranges. The measurement system makes heavy use of surface-mount packaging technology, resulting in plug in modules sized 125x55 mm. The complete 12-slot system is contained within a volume of 220x150x70mm. The system's capabilities extend well beyond the specific objectives of NASA programs. Indeed, the potential commercial uses of the technology are virtually limitless. In addition to applications in medical and biomedical sensing, the system might also be used in process control situations, in clinical or research environments, in general instrumentation systems, factory processing, or any other applications where high quality measurements are required.

A modular, programmable measurement system for physiological and spaceflight applications

NASA Astrophysics Data System (ADS)

Hines, John W.; Ricks, Robert D.; Miles, Christopher J.

1993-02-01

The NASA-Ames Sensors 2000] Program has developed a small, compact, modular, programmable, sensor signal conditioning and measurement system, initially targeted for Life Sciences Spaceflight Programs. The system consists of a twelve-slot, multi-layer, distributed function backplane, a digital microcontroller/memory subsystem, conditioned and isolated power supplies, and six application-specific, physiological signal conditioners. Each signal condition is capable of being programmed for gains, offsets, calibration and operate modes, and, in some cases, selectable outputs and functional modes. Presently, the system has the capability for measuring ECG, EMG, EEG, Temperature, Respiration, Pressure, Force, and Acceleration parameters, in physiological ranges. The measurement system makes heavy use of surface-mount packaging technology, resulting in plug in modules sized 125x55 mm. The complete 12-slot system is contained within a volume of 220x150x70mm. The system's capabilities extend well beyond the specific objectives of NASA programs. Indeed, the potential commercial uses of the technology are virtually limitless. In addition to applications in medical and biomedical sensing, the system might also be used in process control situations, in clinical or research environments, in general instrumentation systems, factory processing, or any other applications where high quality measurements are required.

Evaluation Metrics for the Paragon XP/S-15

NASA Technical Reports Server (NTRS)

Traversat, Bernard; McNab, David; Nitzberg, Bill; Fineberg, Sam; Blaylock, Bruce T. (Technical Monitor)

1993-01-01

On February 17th 1993, the Numerical Aerodynamic Simulation (NAS) facility located at the NASA Ames Research Center installed a 224 node Intel Paragon XP/S-15 system. After its installation, the Paragon was found to be in a very immature state and was unable to support a NAS users' workload, composed of a wide range of development and production activities. As a first step towards addressing this problem, we implemented a set of metrics to objectively monitor the system as operating system and hardware upgrades were installed. The metrics were designed to measure four aspects of the system that we consider essential to support our workload: availability, utilization, functionality, and performance. This report presents the metrics collected from February 1993 to August 1993. Since its installation, the Paragon availability has improved from a low of 15% uptime to a high of 80%, while its utilization has remained low. Functionality and performance have improved from merely running one of the NAS Parallel Benchmarks to running all of them faster (between 1 and 2 times) than on the iPSC/860. In spite of the progress accomplished, fundamental limitations of the Paragon operating system are restricting the Paragon from supporting the NAS workload. The maximum operating system message passing (NORMA IPC) bandwidth was measured at 11 Mbytes/s, well below the peak hardware bandwidth (175 Mbytes/s), limiting overall virtual memory and Unix services (i.e. Disk and HiPPI I/O) performance. The high NX application message passing latency (184 microns), three times than on the iPSC/860, was found to significantly degrade performance of applications relying on small message sizes. The amount of memory available for an application was found to be approximately 10 Mbytes per node, indicating that the OS is taking more space than anticipated (6 Mbytes per node).

An Audio Architecture Integrating Sound and Live Voice for Virtual Environments

DTIC Science & Technology

2002-09-01

implementation of a virtual environment. As real world training locations become scarce and training budgets are trimmed, training system developers ...look more and more towards virtual environments as the answer. Virtual environments provide training system developers with several key benefits

LVC interaction within a mixed-reality training system

NASA Astrophysics Data System (ADS)

Pollock, Brice; Winer, Eliot; Gilbert, Stephen; de la Cruz, Julio

2012-03-01

The United States military is increasingly pursuing advanced live, virtual, and constructive (LVC) training systems for reduced cost, greater training flexibility, and decreased training times. Combining the advantages of realistic training environments and virtual worlds, mixed reality LVC training systems can enable live and virtual trainee interaction as if co-located. However, LVC interaction in these systems often requires constructing immersive environments, developing hardware for live-virtual interaction, tracking in occluded environments, and an architecture that supports real-time transfer of entity information across many systems. This paper discusses a system that overcomes these challenges to empower LVC interaction in a reconfigurable, mixed reality environment. This system was developed and tested in an immersive, reconfigurable, and mixed reality LVC training system for the dismounted warfighter at ISU, known as the Veldt, to overcome LVC interaction challenges and as a test bed for cuttingedge technology to meet future U.S. Army battlefield requirements. Trainees interact physically in the Veldt and virtually through commercial and developed game engines. Evaluation involving military trained personnel found this system to be effective, immersive, and useful for developing the critical decision-making skills necessary for the battlefield. Procedural terrain modeling, model-matching database techniques, and a central communication server process all live and virtual entity data from system components to create a cohesive virtual world across all distributed simulators and game engines in real-time. This system achieves rare LVC interaction within multiple physical and virtual immersive environments for training in real-time across many distributed systems.

Which way and how far? Tracking of translation and rotation information for human path integration.

PubMed

Chrastil, Elizabeth R; Sherrill, Katherine R; Hasselmo, Michael E; Stern, Chantal E

2016-10-01

Path integration, the constant updating of the navigator's knowledge of position and orientation during movement, requires both visuospatial knowledge and memory. This study aimed to develop a systems-level understanding of human path integration by examining the basic building blocks of path integration in humans. To achieve this goal, we used functional imaging to examine the neural mechanisms that support the tracking and memory of translational and rotational components of human path integration. Critically, and in contrast to previous studies, we examined movement in translation and rotation tasks with no defined end-point or goal. Navigators accumulated translational and rotational information during virtual self-motion. Activity in hippocampus, retrosplenial cortex (RSC), and parahippocampal cortex (PHC) increased during both translation and rotation encoding, suggesting that these regions track self-motion information during path integration. These results address current questions regarding distance coding in the human brain. By implementing a modified delayed match to sample paradigm, we also examined the encoding and maintenance of path integration signals in working memory. Hippocampus, PHC, and RSC were recruited during successful encoding and maintenance of path integration information, with RSC selective for tasks that required processing heading rotation changes. These data indicate distinct working memory mechanisms for translation and rotation, which are essential for updating neural representations of current location. The results provide evidence that hippocampus, PHC, and RSC flexibly track task-relevant translation and rotation signals for path integration and could form the hub of a more distributed network supporting spatial navigation. Hum Brain Mapp 37:3636-3655, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Software platform virtualization in chemistry research and university teaching

PubMed Central

2009-01-01

Background Modern chemistry laboratories operate with a wide range of software applications under different operating systems, such as Windows, LINUX or Mac OS X. Instead of installing software on different computers it is possible to install those applications on a single computer using Virtual Machine software. Software platform virtualization allows a single guest operating system to execute multiple other operating systems on the same computer. We apply and discuss the use of virtual machines in chemistry research and teaching laboratories. Results Virtual machines are commonly used for cheminformatics software development and testing. Benchmarking multiple chemistry software packages we have confirmed that the computational speed penalty for using virtual machines is low and around 5% to 10%. Software virtualization in a teaching environment allows faster deployment and easy use of commercial and open source software in hands-on computer teaching labs. Conclusion Software virtualization in chemistry, mass spectrometry and cheminformatics is needed for software testing and development of software for different operating systems. In order to obtain maximum performance the virtualization software should be multi-core enabled and allow the use of multiprocessor configurations in the virtual machine environment. Server consolidation, by running multiple tasks and operating systems on a single physical machine, can lead to lower maintenance and hardware costs especially in small research labs. The use of virtual machines can prevent software virus infections and security breaches when used as a sandbox system for internet access and software testing. Complex software setups can be created with virtual machines and are easily deployed later to multiple computers for hands-on teaching classes. We discuss the popularity of bioinformatics compared to cheminformatics as well as the missing cheminformatics education at universities worldwide. PMID:20150997

Software platform virtualization in chemistry research and university teaching.

PubMed

Kind, Tobias; Leamy, Tim; Leary, Julie A; Fiehn, Oliver

2009-11-16

Modern chemistry laboratories operate with a wide range of software applications under different operating systems, such as Windows, LINUX or Mac OS X. Instead of installing software on different computers it is possible to install those applications on a single computer using Virtual Machine software. Software platform virtualization allows a single guest operating system to execute multiple other operating systems on the same computer. We apply and discuss the use of virtual machines in chemistry research and teaching laboratories. Virtual machines are commonly used for cheminformatics software development and testing. Benchmarking multiple chemistry software packages we have confirmed that the computational speed penalty for using virtual machines is low and around 5% to 10%. Software virtualization in a teaching environment allows faster deployment and easy use of commercial and open source software in hands-on computer teaching labs. Software virtualization in chemistry, mass spectrometry and cheminformatics is needed for software testing and development of software for different operating systems. In order to obtain maximum performance the virtualization software should be multi-core enabled and allow the use of multiprocessor configurations in the virtual machine environment. Server consolidation, by running multiple tasks and operating systems on a single physical machine, can lead to lower maintenance and hardware costs especially in small research labs. The use of virtual machines can prevent software virus infections and security breaches when used as a sandbox system for internet access and software testing. Complex software setups can be created with virtual machines and are easily deployed later to multiple computers for hands-on teaching classes. We discuss the popularity of bioinformatics compared to cheminformatics as well as the missing cheminformatics education at universities worldwide.

A Study of Multi-Representation of Geometry Problem Solving with Virtual Manipulatives and Whiteboard System

ERIC Educational Resources Information Center

Hwang, Wu-Yuin; Su, Jia-Han; Huang, Yueh-Min; Dong, Jian-Jie

2009-01-01

In this paper, the development of an innovative Virtual Manipulatives and Whiteboard (VMW) system is described. The VMW system allowed users to manipulate virtual objects in 3D space and find clues to solve geometry problems. To assist with multi-representation transformation, translucent multimedia whiteboards were used to provide a virtual 3D…

Getting to the Root of Fine Motor Skill Performance in Dentistry: Brain Activity During Dental Tasks in a Virtual Reality Haptic Simulation.

PubMed

Perry, Suzanne; Bridges, Susan M; Zhu, Frank; Leung, W Keung; Burrow, Michael F; Poolton, Jamie; Masters, Rich Sw

2017-12-12

There is little evidence considering the relationship between movement-specific reinvestment (a dimension of personality which refers to the propensity for individuals to consciously monitor and control their movements) and working memory during motor skill performance. Functional near-infrared spectroscopy (fNIRS) measuring oxyhemoglobin demands in the frontal cortex during performance of virtual reality (VR) psychomotor tasks can be used to examine this research gap. The aim of this study was to determine the potential relationship between the propensity to reinvest and blood flow to the dorsolateral prefrontal cortices of the brain. A secondary aim was to determine the propensity to reinvest and performance during 2 dental tasks carried out using haptic VR simulators. We used fNIRS to assess oxygen demands in 24 undergraduate dental students during 2 dental tasks (clinical, nonclinical) on a VR haptic simulator. We used the Movement-Specific Reinvestment Scale questionnaire to assess the students' propensity to reinvest. Students with a high propensity for movement-specific reinvestment displayed significantly greater oxyhemoglobin demands in an area associated with working memory during the nonclinical task (Spearman correlation, r s =.49, P=.03). This small-scale study suggests that neurophysiological differences are evident between high and low reinvesters during a dental VR task in terms of oxyhemoglobin demands in an area associated with working memory. ©Suzanne Perry, Susan M Bridges, Frank Zhu, W Keung Leung, Michael F Burrow, Jamie Poolton, Rich SW Masters. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 12.12.2017.

Recovering from "amnesia" brought about by radiation. Verification of the "Over the air" (OTA) application software update mechanism On-Board Solar Orbiter's Energetic Particle Detector

NASA Astrophysics Data System (ADS)

Da Silva, Antonio; Sánchez Prieto, Sebastián; Rodriguez Polo, Oscar; Parra Espada, Pablo

Computer memories are not supposed to forget, but they do. Because of the proximity of the Sun, from the Solar Orbiter boot software perspective, it is mandatory to look out for permanent memory errors resulting from (SEL) latch-up failures in application binaries stored in EEPROM and its SDRAM deployment areas. In this situation, the last line in defense established by FDIR mechanisms is the capability of the boot software to provide an accurate report of the memories’ damages and to perform an application software update, that avoid the harmed locations by flashing EEPROM with a new binary. This paper describes the OTA EEPROM firmware update procedure verification of the boot software that will run in the Instrument Control Unit (ICU) of the Energetic Particle Detector (EPD) on-board Solar Orbiter. Since the maximum number of rewrites on real EEPROM is limited and permanent memory faults cannot be friendly emulated in real hardware, the verification has been accomplished by the use of a LEON2 Virtual Platform (Leon2ViP) with fault injection capabilities and real SpaceWire interfaces developed by the Space Research Group (SRG) of the University of Alcalá. This way it is possible to run the exact same target binary software as if was run on the real ICU platform. Furthermore, the use of this virtual hardware-in-the-loop (VHIL) approach makes it possible to communicate with Electrical Ground Support Equipment (EGSE) through real SpaceWire interfaces in an agile, controlled and deterministic environment.

Allocentric information is used for memory-guided reaching in depth: A virtual reality study.

PubMed

Klinghammer, Mathias; Schütz, Immo; Blohm, Gunnar; Fiehler, Katja

2016-12-01

Previous research has demonstrated that humans use allocentric information when reaching to remembered visual targets, but most of the studies are limited to 2D space. Here, we study allocentric coding of memorized reach targets in 3D virtual reality. In particular, we investigated the use of allocentric information for memory-guided reaching in depth and the role of binocular and monocular (object size) depth cues for coding object locations in 3D space. To this end, we presented a scene with objects on a table which were located at different distances from the observer and served as reach targets or allocentric cues. After free visual exploration of this scene and a short delay the scene reappeared, but with one object missing (=reach target). In addition, the remaining objects were shifted horizontally or in depth. When objects were shifted in depth, we also independently manipulated object size by either magnifying or reducing their size. After the scene vanished, participants reached to the remembered target location on the blank table. Reaching endpoints deviated systematically in the direction of object shifts, similar to our previous results from 2D presentations. This deviation was stronger for object shifts in depth than in the horizontal plane and independent of observer-target-distance. Reaching endpoints systematically varied with changes in object size. Our results suggest that allocentric information is used for coding targets for memory-guided reaching in depth. Thereby, retinal disparity and vergence as well as object size provide important binocular and monocular depth cues. Copyright © 2016 Elsevier Ltd. All rights reserved.

"Shape function + memory mechanism"-based hysteresis modeling of magnetorheological fluid actuators

NASA Astrophysics Data System (ADS)

Qian, Li-Jun; Chen, Peng; Cai, Fei-Long; Bai, Xian-Xu

2018-03-01

A hysteresis model based on "shape function + memory mechanism" is presented and its feasibility is verified through modeling the hysteresis behavior of a magnetorheological (MR) damper. A hysteresis phenomenon in resistor-capacitor (RC) circuit is first presented and analyzed. In the hysteresis model, the "memory mechanism" originating from the charging and discharging processes of the RC circuit is constructed by adopting a virtual displacement variable and updating laws for the reference points. The "shape function" is achieved and generalized from analytical solutions of the simple semi-linear Duhem model. Using the approach, the memory mechanism reveals the essence of specific Duhem model and the general shape function provides a direct and clear means to fit the hysteresis loop. In the frame of the structure of a "Restructured phenomenological model", the original hysteresis operator, i.e., the Bouc-Wen operator, is replaced with the new hysteresis operator. The comparative work with the Bouc-Wen operator based model demonstrates superior performances of high computational efficiency and comparable accuracy of the new hysteresis operator-based model.

An Innovative Framework for Delivering Psychotherapy to Patients With Treatment-Resistant Posttraumatic Stress Disorder: Rationale for Interactive Motion-Assisted Therapy.

PubMed

van Gelderen, Marieke J; Nijdam, Mirjam J; Vermetten, Eric

2018-01-01

Despite an array of evidence-based psychological treatments for patients with a posttraumatic stress disorder (PTSD), a majority of patients do not fully benefit from the potential of these therapies. In veterans with PTSD, up to two-thirds retain their diagnosis after psychotherapy and often their disorder is treatment-resistant, which calls for improvement of therapeutic approaches for this population. One of the factors hypothesized to underlie low response in PTSD treatment is high behavioral and cognitive avoidance to traumatic reminders. In the current paper we explore if a combination of personalized virtual reality, multi-sensory input, and walking during exposure can enhance treatment engagement, overcome avoidance, and thereby optimize treatment effectiveness. Virtual reality holds potential to increase presence and in-session attention and to facilitate memory retrieval. Multi-sensory input such as pictures and music can personalize this experience. Evidence for the positive effect of physical activity on fear extinction and associative thinking, as well as embodied cognition theories, provide a rationale for decreased avoidance by literally approaching cues of the traumatic memories. A dual-attention task further facilitates new learning and reconsolidation. These strategies have been combined in an innovative framework for trauma-focused psychotherapy, named Multi-modular Motion-assisted Memory Desensitization and Reconsolidation (3MDR). In this innovative treatment the therapeutic setting is changed from the face-to-face sedentary position to a side-by-side activating context in which patients walk toward trauma-related images in a virtual environment. The framework of 3MDR has been designed as a boost for patients with treatment-resistant PTSD, which is illustrated by three case examples. The intervention is discussed in context of other advancements in treatment for treatment-resistant PTSD. Novel elements of this approach are activation, personalization and empowerment. While developed for veterans with PTSD who do not optimally respond to standardized treatments, this innovative framework holds potential to also be used for other patient populations and earlier stages of treatment for patients with PTSD.

An Innovative Framework for Delivering Psychotherapy to Patients With Treatment-Resistant Posttraumatic Stress Disorder: Rationale for Interactive Motion-Assisted Therapy

PubMed Central

van Gelderen, Marieke J.; Nijdam, Mirjam J.; Vermetten, Eric

2018-01-01

Despite an array of evidence-based psychological treatments for patients with a posttraumatic stress disorder (PTSD), a majority of patients do not fully benefit from the potential of these therapies. In veterans with PTSD, up to two-thirds retain their diagnosis after psychotherapy and often their disorder is treatment-resistant, which calls for improvement of therapeutic approaches for this population. One of the factors hypothesized to underlie low response in PTSD treatment is high behavioral and cognitive avoidance to traumatic reminders. In the current paper we explore if a combination of personalized virtual reality, multi-sensory input, and walking during exposure can enhance treatment engagement, overcome avoidance, and thereby optimize treatment effectiveness. Virtual reality holds potential to increase presence and in-session attention and to facilitate memory retrieval. Multi-sensory input such as pictures and music can personalize this experience. Evidence for the positive effect of physical activity on fear extinction and associative thinking, as well as embodied cognition theories, provide a rationale for decreased avoidance by literally approaching cues of the traumatic memories. A dual-attention task further facilitates new learning and reconsolidation. These strategies have been combined in an innovative framework for trauma-focused psychotherapy, named Multi-modular Motion-assisted Memory Desensitization and Reconsolidation (3MDR). In this innovative treatment the therapeutic setting is changed from the face-to-face sedentary position to a side-by-side activating context in which patients walk toward trauma-related images in a virtual environment. The framework of 3MDR has been designed as a boost for patients with treatment-resistant PTSD, which is illustrated by three case examples. The intervention is discussed in context of other advancements in treatment for treatment-resistant PTSD. Novel elements of this approach are activation, personalization and empowerment. While developed for veterans with PTSD who do not optimally respond to standardized treatments, this innovative framework holds potential to also be used for other patient populations and earlier stages of treatment for patients with PTSD. PMID:29780334

Instrumentation to Aid in Steel Bridge Fabrication : Bridge Virtual Assembly System

DOT National Transportation Integrated Search

2018-05-01

This pool funded project developed a BRIDGE VIRTUAL ASSEMBLY SYSTEM (BRIDGE VAS) that improves manufacturing processes and enhances quality control for steel bridge fabrication. The system replaces conventional match-drilling with virtual assembly me...

Goal-Directed Movement Enhances Body Representation Updating

PubMed Central

Wen, Wen; Muramatsu, Katsutoshi; Hamasaki, Shunsuke; An, Qi; Yamakawa, Hiroshi; Tamura, Yusuke; Yamashita, Atsushi; Asama, Hajime

2016-01-01

Body representation refers to perception, memory, and cognition related to the body and is updated continuously by sensory input. The present study examined the influence of goals on body representation updating with two experiments of the rubber hand paradigm. In the experiments, participants moved their hidden left hands forward and backward either in response to instruction to touch a virtual object or without any specific goal, while a virtual left hand was presented 250 mm above the real hand and moved in synchrony with the real hand. Participants then provided information concerning the perceived heights of their real left hands and rated their sense of agency and ownership of the virtual hand. Results of Experiment 1 showed that when participants moved their hands with the goal of touching a virtual object and received feedback indicating goal attainment, the perceived positions of their real hands shifted more toward that of the virtual hand relative to that in the condition without a goal, indicating that their body representations underwent greater modification. Furthermore, results of Experiment 2 showed that the effect of goal-directed movement occurred in the active condition, in which participants moved their own hands, but did not occur in the passive condition, in which participants’ hands were moved by the experimenter. Therefore, we concluded that the sense of agency probably contributed to the updating of body representation involving goal-directed movement. PMID:27445766

Integration of the virtual 3D model of a control system with the virtual controller

NASA Astrophysics Data System (ADS)

Herbuś, K.; Ociepka, P.

2015-11-01

Nowadays the design process includes simulation analysis of different components of a constructed object. It involves the need for integration of different virtual object to simulate the whole investigated technical system. The paper presents the issues related to the integration of a virtual 3D model of a chosen control system of with a virtual controller. The goal of integration is to verify the operation of an adopted object of in accordance with the established control program. The object of the simulation work is the drive system of a tunneling machine for trenchless work. In the first stage of work was created an interactive visualization of functioning of the 3D virtual model of a tunneling machine. For this purpose, the software of the VR (Virtual Reality) class was applied. In the elaborated interactive application were created adequate procedures allowing controlling the drive system of a translatory motion, a rotary motion and the drive system of a manipulator. Additionally was created the procedure of turning on and off the output crushing head, mounted on the last element of the manipulator. In the elaborated interactive application have been established procedures for receiving input data from external software, on the basis of the dynamic data exchange (DDE), which allow controlling actuators of particular control systems of the considered machine. In the next stage of work, the program on a virtual driver, in the ladder diagram (LD) language, was created. The control program was developed on the basis of the adopted work cycle of the tunneling machine. The element integrating the virtual model of the tunneling machine for trenchless work with the virtual controller is the application written in a high level language (Visual Basic). In the developed application was created procedures responsible for collecting data from the running, in a simulation mode, virtual controller and transferring them to the interactive application, in which is verified the operation of the adopted research object. The carried out work allowed foot the integration of the virtual model of the control system of the tunneling machine with the virtual controller, enabling the verification of its operation.

Virtual fringe projection system with nonparallel illumination based on iteration

NASA Astrophysics Data System (ADS)

Zhou, Duo; Wang, Zhangying; Gao, Nan; Zhang, Zonghua; Jiang, Xiangqian

2017-06-01

Fringe projection profilometry has been widely applied in many fields. To set up an ideal measuring system, a virtual fringe projection technique has been studied to assist in the design of hardware configurations. However, existing virtual fringe projection systems use parallel illumination and have a fixed optical framework. This paper presents a virtual fringe projection system with nonparallel illumination. Using an iterative method to calculate intersection points between rays and reference planes or object surfaces, the proposed system can simulate projected fringe patterns and captured images. A new explicit calibration method has been presented to validate the precision of the system. Simulated results indicate that the proposed iterative method outperforms previous systems. Our virtual system can be applied to error analysis, algorithm optimization, and help operators to find ideal system parameter settings for actual measurements.

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.

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.

Cognitive Virtualization: Combining Cognitive Models and Virtual Environments

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

Tuan Q. Tran; David I. Gertman; Donald D. Dudenhoeffer

2007-08-01

3D manikins are often used in visualizations to model human activity in complex settings. Manikins assist in developing understanding of human actions, movements and routines in a variety of different environments representing new conceptual designs. One such environment is a nuclear power plant control room, here they have the potential to be used to simulate more precise ergonomic assessments of human work stations. Next generation control rooms will pose numerous challenges for system designers. The manikin modeling approach by itself, however, may be insufficient for dealing with the desired technical advancements and challenges of next generation automated systems. Uncertainty regardingmore » effective staffing levels; and the potential for negative human performance consequences in the presence of advanced automated systems (e.g., reduced vigilance, poor situation awareness, mistrust or blind faith in automation, higher information load and increased complexity) call for further research. Baseline assessment of novel control room equipment(s) and configurations needs to be conducted. These design uncertainties can be reduced through complementary analysis that merges ergonomic manikin models with models of higher cognitive functions, such as attention, memory, decision-making, and problem-solving. This paper will discuss recent advancements in merging a theoretical-driven cognitive modeling framework within a 3D visualization modeling tool to evaluate of next generation control room human factors and ergonomic assessment. Though this discussion primary focuses on control room design, the application for such a merger between 3D visualization and cognitive modeling can be extended to various areas of focus such as training and scenario planning.« less

Tinnitus: pathology of synaptic plasticity at the cellular and system levels

PubMed Central

Guitton, Matthieu J.

2012-01-01

Despite being more and more common, and having a high impact on the quality of life of sufferers, tinnitus does not yet have a cure. This has been mostly the result of limited knowledge of the biological mechanisms underlying this adverse pathology. However, the last decade has witnessed tremendous progress in our understanding on the pathophysiology of tinnitus. Animal models have demonstrated that tinnitus is a pathology of neural plasticity, and has two main components: a molecular, peripheral component related to the initiation phase of tinnitus; and a system-level, central component-related to the long-term maintenance of tinnitus. Using the most recent experimental data and the molecular/system dichotomy as a framework, we describe here the biological basis of tinnitus. We then discuss these mechanisms from an evolutionary perspective, highlighting similarities with memory. Finally, we consider how these discoveries can translate into therapies, and we suggest operative strategies to design new and effective combined therapeutic solutions using both pharmacological (local and systemic) and behavioral tools (e.g., using tele-medicine and virtual reality settings). PMID:22408611

Final Project Report. Scalable fault tolerance runtime technology for petascale computers

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

Krishnamoorthy, Sriram; Sadayappan, P

With the massive number of components comprising the forthcoming petascale computer systems, hardware failures will be routinely encountered during execution of large-scale applications. Due to the multidisciplinary, multiresolution, and multiscale nature of scientific problems that drive the demand for high end systems, applications place increasingly differing demands on the system resources: disk, network, memory, and CPU. In addition to MPI, future applications are expected to use advanced programming models such as those developed under the DARPA HPCS program as well as existing global address space programming models such as Global Arrays, UPC, and Co-Array Fortran. While there has been amore » considerable amount of work in fault tolerant MPI with a number of strategies and extensions for fault tolerance proposed, virtually none of advanced models proposed for emerging petascale systems is currently fault aware. To achieve fault tolerance, development of underlying runtime and OS technologies able to scale to petascale level is needed. This project has evaluated range of runtime techniques for fault tolerance for advanced programming models.« less

Using smartphone technology to deliver a virtual pedestrian environment: usability and validation.

PubMed

Schwebel, David C; Severson, Joan; He, Yefei

2017-09-01

Various programs effectively teach children to cross streets more safely, but all are labor- and cost-intensive. Recent developments in mobile phone technology offer opportunity to deliver virtual reality pedestrian environments to mobile smartphone platforms. Such an environment may offer a cost- and labor-effective strategy to teach children to cross streets safely. This study evaluated usability, feasibility, and validity of a smartphone-based virtual pedestrian environment. A total of 68 adults completed 12 virtual crossings within each of two virtual pedestrian environments, one delivered by smartphone and the other a semi-immersive kiosk virtual environment. Participants completed self-report measures of perceived realism and simulator sickness experienced in each virtual environment, plus self-reported demographic and personality characteristics. All participants followed system instructions and used the smartphone-based virtual environment without difficulty. No significant simulator sickness was reported or observed. Users rated the smartphone virtual environment as highly realistic. Convergent validity was detected, with many aspects of pedestrian behavior in the smartphone-based virtual environment matching behavior in the kiosk virtual environment. Anticipated correlations between personality and kiosk virtual reality pedestrian behavior emerged for the smartphone-based system. A smartphone-based virtual environment can be usable and valid. Future research should develop and evaluate such a training system.

Scaling view by the Virtual Nature Systems

NASA Astrophysics Data System (ADS)

Klenov, Valeriy

2010-05-01

The Actual Nature Systems (ANS) continually are under spatial-temporal governing external influences from other systems (Meteorology and Geophysics). This influences provide own spatial temporal patterns on the Earth Nature Systems, which reforms these influences by own manner and scales. These at last three systems belong to the Open Non Equilibrium Nature Systems (ONES). The Geophysics and Meteorology Systems are both governing for the ANS on the Earth. They provide as continual energetic pressure and impacts, and direct Extremes from the both systems to the ANS on Earth surface (earthquakes, storms, and others). The Geodynamics of the ANS is under mixing of influence for both systems, on their scales and on dynamics of their spatial-temporal structures, and by own ANS properties, as the ONES. To select influences of external systems on the Earth systems always is among major tasks of the Geomorphology. Mixing of the Systems scales and dynamics provide specific properties for the memory of Earth system. The memory of the ANS has practical value for their multi-purpose management. The knowledge of these properties is the key for research spatial-temporal GeoDynamics and Trends of Earth Nature Systems. Selection of the influences in time and space requires for special tool, requires elaboration and action of the Virtual Nature Systems (VNS), which are enliven computer doubles for analysis Geodynamics of the ANS. The Experience on the VNS enables to assess influence of each and both external factors on the ANS. It is source of knowledge for regional tectonic and climate oscillations, trends, and threats. Research by the VNS for spatial-temporal dynamics and structures of stochastic regimes of governing systems and processes results in stochastic GeoDynamics of environmental processes, in forming of false trends and blanks in natural records. This ‘wild dance' of 2D stochastic patterns and their interaction each other and generates acting structures of river nets, and of river basins, in multi-layer, multi-scale, and multi-driven structures of surface processes. It results in the Information Loss Law for observed memory of the VNS (and of external drivers) which gradually cut off own Past and distort own history. This view on the GeoDynamics appeared after long time field measurements thousand of terrace levels, hundreds of terrace ranks, and many terrace complexes in river basins of all scales - for the purpose to recognize their deforming by climatic and tectonic spatial-temporal influences. The method for following up of terrace levels along valleys was used in the Geomorphology and Geology for a long time, by linking fragments of level to ‘cycles'. It gradually linked them by heights above riverbed. The understanding of this logical mistake was happened (as insight) during observing from upstream a valley. All fragmental levels downstream were good visible, without chances for their correlation ‘by height' or ‘by number'. Instead of link of fragments, this explains process of river valleys' stochastic GeoDynamics by properties of the ONES (I. Prigogine et al., 1984) to generate oscillations. Is only first view, but later it turned to simple mechanic of Information Loss Law action in the GeoInformatics for Nature Systems (Klenov, 1980, et al.). The Information Loss distorts and destroys natural records (sources for data on the Past exogenous and endogenous rivers). This simple equation was received by multiple measures of terrace rank, and other natural records. It explains origin of false trend in natural records, destroys most own history by stochastic dynamics of the ONES. It prevents to restore of nature records as a memory of the Past. Non-disturbed is only small time between the Past and the Future, which looks like a peak between two non-linear losses. The history of Past (of the ANS, and of external drivers) are destroyed by the ANS. The Future becomes none determined due unknown 2D data of future external influences. However, the effect is the reliable Outstripping Monitoring for impending disasters and of other processes with satisfactory exactness. It was proved by direct validations (by use observed records). The conclusions are as follows: The ILL is mechanics for dissipation the Past and indeterminism the Future of the Nature. Moving back along the VNS' Phase Trajectory changes a view on natural records, and is chance to restore history of the ANS and its external drivers.

System-Level Virtualization Research at Oak Ridge National Laboratory

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

Scott, Stephen L; Vallee, Geoffroy R; Naughton, III, Thomas J

2010-01-01

System-level virtualization is today enjoying a rebirth as a technique to effectively share what were then considered large computing resources to subsequently fade from the spotlight as individual workstations gained in popularity with a one machine - one user approach. One reason for this resurgence is that the simple workstation has grown in capability to rival that of anything available in the past. Thus, computing centers are again looking at the price/performance benefit of sharing that single computing box via server consolidation. However, industry is only concentrating on the benefits of using virtualization for server consolidation (enterprise computing) whereas ourmore » interest is in leveraging virtualization to advance high-performance computing (HPC). While these two interests may appear to be orthogonal, one consolidating multiple applications and users on a single machine while the other requires all the power from many machines to be dedicated solely to its purpose, we propose that virtualization does provide attractive capabilities that may be exploited to the benefit of HPC interests. This does raise the two fundamental questions of: is the concept of virtualization (a machine sharing technology) really suitable for HPC and if so, how does one go about leveraging these virtualization capabilities for the benefit of HPC. To address these questions, this document presents ongoing studies on the usage of system-level virtualization in a HPC context. These studies include an analysis of the benefits of system-level virtualization for HPC, a presentation of research efforts based on virtualization for system availability, and a presentation of research efforts for the management of virtual systems. The basis for this document was material presented by Stephen L. Scott at the Collaborative and Grid Computing Technologies meeting held in Cancun, Mexico on April 12-14, 2007.« less

Memory and visual search in naturalistic 2D and 3D environments

PubMed Central

Li, Chia-Ling; Aivar, M. Pilar; Kit, Dmitry M.; Tong, Matthew H.; Hayhoe, Mary M.

2016-01-01

The role of memory in guiding attention allocation in daily behaviors is not well understood. In experiments with two-dimensional (2D) images, there is mixed evidence about the importance of memory. Because the stimulus context in laboratory experiments and daily behaviors differs extensively, we investigated the role of memory in visual search, in both two-dimensional (2D) and three-dimensional (3D) environments. A 3D immersive virtual apartment composed of two rooms was created, and a parallel 2D visual search experiment composed of snapshots from the 3D environment was developed. Eye movements were tracked in both experiments. Repeated searches for geometric objects were performed to assess the role of spatial memory. Subsequently, subjects searched for realistic context objects to test for incidental learning. Our results show that subjects learned the room-target associations in 3D but less so in 2D. Gaze was increasingly restricted to relevant regions of the room with experience in both settings. Search for local contextual objects, however, was not facilitated by early experience. Incidental fixations to context objects do not necessarily benefit search performance. Together, these results demonstrate that memory for global aspects of the environment guides search by restricting allocation of attention to likely regions, whereas task relevance determines what is learned from the active search experience. Behaviors in 2D and 3D environments are comparable, although there is greater use of memory in 3D. PMID:27299769

Sources of interference in item and associative recognition memory.

PubMed

Osth, Adam F; Dennis, Simon

2015-04-01

A powerful theoretical framework for exploring recognition memory is the global matching framework, in which a cue's memory strength reflects the similarity of the retrieval cues being matched against the contents of memory simultaneously. Contributions at retrieval can be categorized as matches and mismatches to the item and context cues, including the self match (match on item and context), item noise (match on context, mismatch on item), context noise (match on item, mismatch on context), and background noise (mismatch on item and context). We present a model that directly parameterizes the matches and mismatches to the item and context cues, which enables estimation of the magnitude of each interference contribution (item noise, context noise, and background noise). The model was fit within a hierarchical Bayesian framework to 10 recognition memory datasets that use manipulations of strength, list length, list strength, word frequency, study-test delay, and stimulus class in item and associative recognition. Estimates of the model parameters revealed at most a small contribution of item noise that varies by stimulus class, with virtually no item noise for single words and scenes. Despite the unpopularity of background noise in recognition memory models, background noise estimates dominated at retrieval across nearly all stimulus classes with the exception of high frequency words, which exhibited equivalent levels of context noise and background noise. These parameter estimates suggest that the majority of interference in recognition memory stems from experiences acquired before the learning episode. (c) 2015 APA, all rights reserved).

System and method for memory allocation in a multiclass memory system

DOEpatents

Loh, Gabriel; Meswani, Mitesh; Ignatowski, Michael; Nutter, Mark

2016-06-28

A system for memory allocation in a multiclass memory system includes a processor coupleable to a plurality of memories sharing a unified memory address space, and a library store to store a library of software functions. The processor identifies a type of a data structure in response to a memory allocation function call to the library for allocating memory to the data structure. Using the library, the processor allocates portions of the data structure among multiple memories of the multiclass memory system based on the type of the data structure.

Diminishing returns: the influence of experience and environment on time-memory extinction in honey bee foragers.

PubMed

Moore, Darrell; Van Nest, Byron N; Seier, Edith

2011-06-01

Classical experiments demonstrated that honey bee foragers trained to collect food at virtually any time of day will return to that food source on subsequent days with a remarkable degree of temporal accuracy. This versatile time-memory, based on an endogenous circadian clock, presumably enables foragers to schedule their reconnaissance flights to best take advantage of the daily rhythms of nectar and pollen availability in different species of flowers. It is commonly believed that the time-memory rapidly extinguishes if not reinforced daily, thus enabling foragers to switch quickly from relatively poor sources to more productive ones. On the other hand, it is also commonly thought that extinction of the time-memory is slow enough to permit foragers to 'remember' the food source over a day or two of bad weather. What exactly is the time-course of time-memory extinction? In a series of field experiments, we determined that the level of food-anticipatory activity (FAA) directed at a food source is not rapidly extinguished and, furthermore, the time-course of extinction is dependent upon the amount of experience accumulated by the forager at that source. We also found that FAA is prolonged in response to inclement weather, indicating that time-memory extinction is not a simple decay function but is responsive to environmental changes. These results provide insights into the adaptability of FAA under natural conditions.

User Guide: How to Use and Operate Virtual Reality Equipment in the Systems Assessment and Usability Laboratory (SAUL) for Conducting Demonstrations

DTIC Science & Technology

2017-08-01

ARL-TN-0839 ● AUG 2017 US Army Research Laboratory User Guide: How to Use and Operate Virtual Reality Equipment in the Systems...ARL-TN-0839 ● AUG 2017 US Army Research Laboratory User Guide: How to Use and Operate Virtual Reality Equipment in the Systems...September 2017 4. TITLE AND SUBTITLE User Guide: How to Use and Operate Virtual Reality Equipment in the Systems Assessment and Usability Laboratory

Virtual reality in surgical training.

PubMed

Lange, T; Indelicato, D J; Rosen, J M

2000-01-01

Virtual reality in surgery and, more specifically, in surgical training, faces a number of challenges in the future. These challenges are building realistic models of the human body, creating interface tools to view, hear, touch, feel, and manipulate these human body models, and integrating virtual reality systems into medical education and treatment. A final system would encompass simulators specifically for surgery, performance machines, telemedicine, and telesurgery. Each of these areas will need significant improvement for virtual reality to impact medicine successfully in the next century. This article gives an overview of, and the challenges faced by, current systems in the fast-changing field of virtual reality technology, and provides a set of specific milestones for a truly realistic virtual human body.

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 between Western Australia and UNM. We successfully demonstrated the ability to fully immerse participants in a distributed virtual environment independent of distance for collaborative team interaction in medical simulation designed for education and training. The ability to make mistakes in a safe environment is well received by students and has a positive impact on their understanding, as well as memory of the principles involved in correcting those mistakes. Bringing people together as virtual teams for interactive experiential learning and collaborative training, independent of distance, provides a platform for distributed "just-in-time" training, performance assessment and credentialing. Further validation is necessary to determine the potential value of the distributed VRE in knowledge transfer, improved future performance and should entail training participants to competence in using these tools.

A framework for interactive visual analysis of heterogeneous marine data in an integrated problem solving environment

NASA Astrophysics Data System (ADS)

Liu, Shuai; Chen, Ge; Yao, Shifeng; Tian, Fenglin; Liu, Wei

2017-07-01

This paper presents a novel integrated marine visualization framework which focuses on processing, analyzing the multi-dimension spatiotemporal marine data in one workflow. Effective marine data visualization is needed in terms of extracting useful patterns, recognizing changes, and understanding physical processes in oceanography researches. However, the multi-source, multi-format, multi-dimension characteristics of marine data pose a challenge for interactive and feasible (timely) marine data analysis and visualization in one workflow. And, global multi-resolution virtual terrain environment is also needed to give oceanographers and the public a real geographic background reference and to help them to identify the geographical variation of ocean phenomena. This paper introduces a data integration and processing method to efficiently visualize and analyze the heterogeneous marine data. Based on the data we processed, several GPU-based visualization methods are explored to interactively demonstrate marine data. GPU-tessellated global terrain rendering using ETOPO1 data is realized and the video memory usage is controlled to ensure high efficiency. A modified ray-casting algorithm for the uneven multi-section Argo volume data is also presented and the transfer function is designed to analyze the 3D structure of ocean phenomena. Based on the framework we designed, an integrated visualization system is realized. The effectiveness and efficiency of the framework is demonstrated. This system is expected to make a significant contribution to the demonstration and understanding of marine physical process in a virtual global environment.

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.

Education about Hallucinations Using an Internet Virtual Reality System: A Qualitative Survey

ERIC Educational Resources Information Center

Yellowlees, Peter M.; Cook, James N.

2006-01-01

Objective: The authors evaluate an Internet virtual reality technology as an education tool about the hallucinations of psychosis. Method: This is a pilot project using Second Life, an Internet-based virtual reality system, in which a virtual reality environment was constructed to simulate the auditory and visual hallucinations of two patients…

Olfactory Stimuli Increase Presence in Virtual Environments

PubMed Central

Munyan, Benson G.; Neer, Sandra M.; Beidel, Deborah C.; Jentsch, Florian

2016-01-01

Background Exposure therapy (EXP) is the most empirically supported treatment for anxiety and trauma-related disorders. EXP consists of repeated exposure to a feared object or situation in the absence of the feared outcome in order to extinguish associated anxiety. Key to the success of EXP is the need to present the feared object/event/situation in as much detail and utilizing as many sensory modalities as possible, in order to augment the sense of presence during exposure sessions. Various technologies used to augment the exposure therapy process by presenting multi-sensory cues (e.g., sights, smells, sounds). Studies have shown that scents can elicit emotionally charged memories, but no prior research has examined the effect of olfactory stimuli upon the patient’s sense of presence during simulated exposure tasks. Methods 60 adult participants navigated a mildly anxiety-producing virtual environment (VE) similar to those used in the treatment of anxiety disorders. Participants had no autobiographical memory associated with the VE. State anxiety, Presence ratings, and electrodermal (EDA) activity were collected throughout the experiment. Results Utilizing a Bonferroni corrected Linear Mixed Model, our results showed statistically significant relationships between olfactory stimuli and presence as assessed by both the Igroup Presence Questionnaire (IPQ: R2 = 0.85, (F(3,52) = 6.625, p = 0.0007) and a single item visual-analogue scale (R2 = 0.85, (F(3,52) = 5.382, p = 0.0027). State anxiety was unaffected by the presence or absence of olfactory cues. EDA was unaffected by experimental condition. Conclusion Olfactory stimuli increase presence in virtual environments that approximate those typical in exposure therapy, but did not increase EDA. Additionally, once administered, the removal of scents resulted in a disproportionate decrease in presence. Implications for incorporating the use of scents to increase the efficacy of exposure therapy is discussed. PMID:27310253

Feasibility and safety of virtual-reality-based early neurocognitive stimulation in critically ill patients.

PubMed

Turon, Marc; Fernandez-Gonzalo, Sol; Jodar, Mercè; Gomà, Gemma; Montanya, Jaume; Hernando, David; Bailón, Raquel; de Haro, Candelaria; Gomez-Simon, Victor; Lopez-Aguilar, Josefina; Magrans, Rudys; Martinez-Perez, Melcior; Oliva, Joan Carles; Blanch, Lluís

2017-12-01

Growing evidence suggests that critical illness often results in significant long-term neurocognitive impairments in one-third of survivors. Although these neurocognitive impairments are long-lasting and devastating for survivors, rehabilitation rarely occurs during or after critical illness. Our aim is to describe an early neurocognitive stimulation intervention based on virtual reality for patients who are critically ill and to present the results of a proof-of-concept study testing the feasibility, safety, and suitability of this intervention. Twenty critically ill adult patients undergoing or having undergone mechanical ventilation for ≥24 h received daily 20-min neurocognitive stimulation sessions when awake and alert during their ICU stay. The difficulty of the exercises included in the sessions progressively increased over successive sessions. Physiological data were recorded before, during, and after each session. Safety was assessed through heart rate, peripheral oxygen saturation, and respiratory rate. Heart rate variability analysis, an indirect measure of autonomic activity sensitive to cognitive demands, was used to assess the efficacy of the exercises in stimulating attention and working memory. Patients successfully completed the sessions on most days. No sessions were stopped early for safety concerns, and no adverse events occurred. Heart rate variability analysis showed that the exercises stimulated attention and working memory. Critically ill patients considered the sessions enjoyable and relaxing without being overly fatiguing. The results in this proof-of-concept study suggest that a virtual-reality-based neurocognitive intervention is feasible, safe, and tolerable, stimulating cognitive functions and satisfying critically ill patients. Future studies will evaluate the impact of interventions on neurocognitive outcomes. Trial registration Clinical trials.gov identifier: NCT02078206.

Evaluation of Domain-Specific Collaboration Interfaces for Team Command and Control Tasks

DTIC Science & Technology

2012-05-01

Technologies 1.1.1. Virtual Whiteboard Cognitive theories relating the utilization, storage, and retrieval of verbal and spatial information, such as...AE Spatial emergent SE Auditory linguistic AL Spatial positional SP Facial figural FF Spatial quantitative SQ Facial motive FM Tactile figural...driven by the auditory linguistic (AL), short-term memory (STM), spatial attentive (SA), visual temporal (VT), and vocal process (V) subscales. 0

Computer-Aided Fabrication of Integrated Circuits

DTIC Science & Technology

1989-09-30

baseline CMOS process. One result of this effort was the identification of several residual bugs in the PATRAN graphics processor . The vendor promises...virtual memory. The internal Nubus architecture uses a 32-bit LISP processor running at 10 megahertz (100 ns clock period). An ethernet controller is...For different patterns, we need different masks for the photo step, and for dif- ferent micro -structures of the wafers, we need different etching

Cue-dependent memory-based smooth-pursuit in normal human subjects: importance of extra-retinal mechanisms for initial pursuit.

PubMed

Ito, Norie; Barnes, Graham R; Fukushima, Junko; Fukushima, Kikuro; Warabi, Tateo

2013-08-01

Using a cue-dependent memory-based smooth-pursuit task previously applied to monkeys, we examined the effects of visual motion-memory on smooth-pursuit eye movements in normal human subjects and compared the results with those of the trained monkeys. These results were also compared with those during simple ramp-pursuit that did not require visual motion-memory. During memory-based pursuit, all subjects exhibited virtually no errors in either pursuit-direction or go/no-go selection. Tracking eye movements of humans and monkeys were similar in the two tasks, but tracking eye movements were different between the two tasks; latencies of the pursuit and corrective saccades were prolonged, initial pursuit eye velocity and acceleration were lower, peak velocities were lower, and time to reach peak velocities lengthened during memory-based pursuit. These characteristics were similar to anticipatory pursuit initiated by extra-retinal components during the initial extinction task of Barnes and Collins (J Neurophysiol 100:1135-1146, 2008b). We suggest that the differences between the two tasks reflect differences between the contribution of extra-retinal and retinal components. This interpretation is supported by two further studies: (1) during popping out of the correct spot to enhance retinal image-motion inputs during memory-based pursuit, pursuit eye velocities approached those during simple ramp-pursuit, and (2) during initial blanking of spot motion during memory-based pursuit, pursuit components appeared in the correct direction. Our results showed the importance of extra-retinal mechanisms for initial pursuit during memory-based pursuit, which include priming effects and extra-retinal drive components. Comparison with monkey studies on neuronal responses and model analysis suggested possible pathways for the extra-retinal mechanisms.

Virtual reality: past, present and future.

PubMed

Gobbetti, E; Scateni, R

1998-01-01

This report provides a short survey of the field of virtual reality, highlighting application domains, technological requirements, and currently available solutions. The report is organized as follows: section 1 presents the background and motivation of virtual environment research and identifies typical application domain, section 2 discusses the characteristics a virtual reality system must have in order to exploit the perceptual and spatial skills of users, section 3 surveys current input/output devices for virtual reality, section 4 surveys current software approaches to support the creation of virtual reality systems, and section 5 summarizes the report.

Nonvolatile Memory Materials for Neuromorphic Intelligent Machines.

PubMed

Jeong, Doo Seok; Hwang, Cheol Seong

2018-04-18

Recent progress in deep learning extends the capability of artificial intelligence to various practical tasks, making the deep neural network (DNN) an extremely versatile hypothesis. While such DNN is virtually built on contemporary data centers of the von Neumann architecture, physical (in part) DNN of non-von Neumann architecture, also known as neuromorphic computing, can remarkably improve learning and inference efficiency. Particularly, resistance-based nonvolatile random access memory (NVRAM) highlights its handy and efficient application to the multiply-accumulate (MAC) operation in an analog manner. Here, an overview is given of the available types of resistance-based NVRAMs and their technological maturity from the material- and device-points of view. Examples within the strategy are subsequently addressed in comparison with their benchmarks (virtual DNN in deep learning). A spiking neural network (SNN) is another type of neural network that is more biologically plausible than the DNN. The successful incorporation of resistance-based NVRAM in SNN-based neuromorphic computing offers an efficient solution to the MAC operation and spike timing-based learning in nature. This strategy is exemplified from a material perspective. Intelligent machines are categorized according to their architecture and learning type. Also, the functionality and usefulness of NVRAM-based neuromorphic computing are addressed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Joint Attention, Social-Cognition, and Recognition Memory in Adults

PubMed Central

Kim, Kwanguk; Mundy, Peter

2012-01-01

The early emerging capacity for Joint Attention (JA), or socially coordinated visual attention, is thought to be integral to the development of social-cognition in childhood. Recent studies have also begun to suggest that JA affects adult cognition as well, but methodological limitations hamper research on this topic. To address this issue we developed a novel virtual reality paradigm that integrates eye-tracking and virtual avatar technology to measure two types of JA in adults, Initiating Joint Attention (IJA) and Responding to Joint Attention (RJA). Distinguishing these types of JA in research is important because they are thought to reflect unique, as well as common constellations of processes involved in human social-cognition and social learning. We tested the validity of the differentiation of IJA and RJA in our paradigm in two studies of picture recognition memory in undergraduate students. Study 1 indicated that young adults correctly identified more pictures they had previously viewed in an IJA condition (67%) than in a RJA (58%) condition, η2 = 0.57. Study 2 controlled for IJA and RJA stimulus viewing time differences, and replicated the findings of Study 1. The implications of these results for the validity of the paradigm and research on the affects of JA on adult social-cognition are discussed. PMID:22712011

Architecture Adaptive Computing Environment

NASA Technical Reports Server (NTRS)

Dorband, John E.

2006-01-01

Architecture Adaptive Computing Environment (aCe) is a software system that includes a language, compiler, and run-time library for parallel computing. aCe was developed to enable programmers to write programs, more easily than was previously possible, for a variety of parallel computing architectures. Heretofore, it has been perceived to be difficult to write parallel programs for parallel computers and more difficult to port the programs to different parallel computing architectures. In contrast, aCe is supportable on all high-performance computing architectures. Currently, it is supported on LINUX clusters. aCe uses parallel programming constructs that facilitate writing of parallel programs. Such constructs were used in single-instruction/multiple-data (SIMD) programming languages of the 1980s, including Parallel Pascal, Parallel Forth, C*, *LISP, and MasPar MPL. In aCe, these constructs are extended and implemented for both SIMD and multiple- instruction/multiple-data (MIMD) architectures. Two new constructs incorporated in aCe are those of (1) scalar and virtual variables and (2) pre-computed paths. The scalar-and-virtual-variables construct increases flexibility in optimizing memory utilization in various architectures. The pre-computed-paths construct enables the compiler to pre-compute part of a communication operation once, rather than computing it every time the communication operation is performed.

Event memory and moving in a well-known environment.

PubMed

Tamplin, Andrea K; Krawietz, Sabine A; Radvansky, Gabriel A; Copeland, David E

2013-11-01

Research in narrative comprehension has repeatedly shown that when people read about characters moving in well-known environments, the accessibility of object information follows a spatial gradient. That is, the accessibility of objects is best when they are in the same room as the protagonist, and it becomes worse the farther away they are see, e.g., Morrow, Greenspan, & Bower, (Journal of Memory and Language, 26, 165-187, 1987). In the present study, we assessed this finding using an interactive environment in which we had people memorize a map and navigate a virtual simulation of the area. During navigation, people were probed with pairs of object names and indicated whether both objects were in the same room. In contrast to the narrative studies described above, several experiments showed no evidence of a clear spatial gradient. Instead, memory for objects in currently occupied locations (e.g., the location room) was more accessible, especially after a small delay, but no clear decline was evident in the accessibility of information in memory with increased distance. Also, memory for objects along the pathway of movement (i.e., rooms that a person only passed through) showed a transitory suppression effect that was present immediately after movement, but attenuated over time. These results were interpreted in light of the event horizon model of event cognition.

Decoding individual episodic memory traces in the human hippocampus.

PubMed

Chadwick, Martin J; Hassabis, Demis; Weiskopf, Nikolaus; Maguire, Eleanor A

2010-03-23

In recent years, multivariate pattern analyses have been performed on functional magnetic resonance imaging (fMRI) data, permitting prediction of mental states from local patterns of blood oxygen-level-dependent (BOLD) signal across voxels. We previously demonstrated that it is possible to predict the position of individuals in a virtual-reality environment from the pattern of activity across voxels in the hippocampus. Although this shows that spatial memories can be decoded, substantially more challenging, and arguably only possible to investigate in humans, is whether it is feasible to predict which complex everyday experience, or episodic memory, a person is recalling. Here we document for the first time that traces of individual rich episodic memories are detectable and distinguishable solely from the pattern of fMRI BOLD signals across voxels in the human hippocampus. In so doing, we uncovered a possible functional topography in the hippocampus, with preferential episodic processing by some hippocampal regions over others. Moreover, our results imply that the neuronal traces of episodic memories are stable (and thus predictable) even over many re-activations. Finally, our data provide further evidence for functional differentiation within the medial temporal lobe, in that we show the hippocampus contains significantly more episodic information than adjacent structures. 2010 Elsevier Ltd. All rights reserved.

Simulation-based mentalizing generates a "proxy" self-reference effect in memory.

PubMed

Allan, Kevin; Morson, Suzannah; Dixon, Susan; Martin, Douglas; Cunningham, Sheila J

2017-06-01

The self-reference effect (SRE) in memory is thought to depend on specialized mechanisms that enhance memory for self-relevant information. We investigated whether these mechanisms can be engaged "by proxy" when we simulate other people, by asking participants to interact with two virtual partners: one similar and one dissimilar to self. Participants viewed pairs of objects and picked one for themselves, for their similar partner, or their dissimilar partner. A surprise memory test followed that required participants to identify which object of each pair was chosen, and for whom. Finally, participants were shown both partners' object pairs again, and asked to indicate their personal preference. Four key findings were observed. Overlap between participants' own choice and those made for their partner was significantly higher for the similar than the dissimilar partner, revealing participants' use of their own preferences to simulate the similar partner. Recollection of chosen objects was significantly higher for self than for both partners and, critically, was significantly higher for similar than dissimilar partners. Source confusion between self and the similar partner was also higher. These findings suggest that self-reference by proxy enhances memory for non-self-relevant material, and we consider the theoretical implications for functional interpretation of the SRE.

Absence of verbal recall or memory for symptom acquisition in fear and trauma exposure: a conceptual case for fear conditioning and learned nonuse in assessment and treatment.

PubMed

Seifert, A Ronald

2012-01-01

Absence of memory or verbal recall for symptom acquisition in fear and trauma exposure, as well as absence of successful coping behavior for life events, is associated with a number of diagnoses, including traumatic brain injury, posttraumatic stress disorder, pain, and anxiety. The difficulty with diagnosis and treatment planning based on the absence of recall, memory, and successful coping behavior is threefold: (1) these assessments do not distinguish between disruption of behavior and lack of capacity, (2) the absence of verbal recall and memory complicates cognitive-based treatment, and (3) a confounding issue is the same absent behavior can be observed at different times and contexts. While memory of the specific details of the initial traumatic event(s) may not be available to verbal report, the existence of time- and context-dependent relationships for the initial as well as subsequent experiences is arguable. The absence of memory or lack of verbal recall does not rule out measurable physiological bodily responses for the initial trauma(s), nor does it help to establish the effects of subsequent experiences for symptom expression. Also, the absence of memory must include the prospect of fear-based learning that does not require or involve the cortex. It is posited that the literatures of fear conditioning and learned nonuse provide complementary illustrations of how the time and context of the initial trauma(s) and subsequent experiences affect behavior, which is not dependent on the effected individual being able to provide a memory-based verbal report. The replicated clinical application demonstrates that, without scientific demonstration, neither neuroanatomy nor verbal report can be assumed sufficient to predict overt behavior or physiologic responses. For example, while commonly assumed to be predictively so, autonomic nervous system innervation is insufficient to define the unique stimulus- and context-dependent physiological responses of an individual. By recording simultaneous physiological responses to the controlled presentation of a context-dependent stimulus, the unique relationships of physiology and overt behaviors for the individual can be demonstrated. Using this process also allows more complex virtual reality or other in vivo stimulus assessments to be incorporated for the development of individually tailored assessments and therapeutic plans. Thus, with or without memory or verbal recall, the use of multiple time- and context-specific simultaneous physiological measures and overt behavior can guide clinical effort as well as serve to objectively assess the ongoing treatment and its outcome.