Science.gov

Sample records for remote memory access

  1. Remote direct memory access

    DOEpatents

    Archer, Charles J.; Blocksome, Michael A.

    2012-12-11

    Methods, parallel computers, and computer program products are disclosed for remote direct memory access. Embodiments include transmitting, from an origin DMA engine on an origin compute node to a plurality target DMA engines on target compute nodes, a request to send message, the request to send message specifying a data to be transferred from the origin DMA engine to data storage on each target compute node; receiving, by each target DMA engine on each target compute node, the request to send message; preparing, by each target DMA engine, to store data according to the data storage reference and the data length, including assigning a base storage address for the data storage reference; sending, by one or more of the target DMA engines, an acknowledgment message acknowledging that all the target DMA engines are prepared to receive a data transmission from the origin DMA engine; receiving, by the origin DMA engine, the acknowledgement message from the one or more of the target DMA engines; and transferring, by the origin DMA engine, data to data storage on each of the target compute nodes according to the data storage reference using a single direct put operation.

  2. Remote direct memory access over datagrams

    DOEpatents

    Grant, Ryan Eric; Rashti, Mohammad Javad; Balaji, Pavan; Afsahi, Ahmad

    2014-12-02

    A communication stack for providing remote direct memory access (RDMA) over a datagram network is disclosed. The communication stack has a user level interface configured to accept datagram related input and communicate with an RDMA enabled network interface card (NIC) via an NIC driver. The communication stack also has an RDMA protocol layer configured to supply one or more data transfer primitives for the datagram related input of the user level. The communication stack further has a direct data placement (DDP) layer configured to transfer the datagram related input from a user storage to a transport layer based on the one or more data transfer primitives by way of a lower layer protocol (LLP) over the datagram network.

  3. Scaling Linear Algebra Kernels using Remote Memory Access

    SciTech Connect

    Krishnan, Manoj Kumar; Lewis, Robert R.; Vishnu, Abhinav

    2010-09-13

    This paper describes the scalability of linear algebra kernels based on remote memory access approach. The current approach differs from the other linear algebra algorithms by the explicit use of shared memory and remote memory access (RMA) communication rather than message passing. It is suitable for clusters and scalable shared memory systems. The experimental results on large scale systems (Linux-Infiniband cluster, Cray XT) demonstrate consistent performance advantages over ScaLAPACK suite, the leading implementation of parallel linear algebra algorithms used today. For example, on a Cray XT4 for a matrix size of 102400, our RMA-based matrix multiplication achieved over 55 teraflops while ScaLAPACK’s pdgemm measured close to 42 teraflops on 10000 processes.

  4. Administering an epoch initiated for remote memory access

    SciTech Connect

    Blocksome, Michael A; Miller, Douglas R

    2014-03-18

    Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

  5. Administering an epoch initiated for remote memory access

    DOEpatents

    Blocksome, Michael A; Miller, Douglas R

    2012-10-23

    Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

  6. Administering an epoch initiated for remote memory access

    DOEpatents

    Blocksome, Michael A.; Miller, Douglas R.

    2013-01-01

    Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

  7. Performance Evaluation of Remote Memory Access (RMA) Programming on Shared Memory Parallel Computers

    NASA Technical Reports Server (NTRS)

    Jin, Hao-Qiang; Jost, Gabriele; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    The purpose of this study is to evaluate the feasibility of remote memory access (RMA) programming on shared memory parallel computers. We discuss different RMA based implementations of selected CFD application benchmark kernels and compare them to corresponding message passing based codes. For the message-passing implementation we use MPI point-to-point and global communication routines. For the RMA based approach we consider two different libraries supporting this programming model. One is a shared memory parallelization library (SMPlib) developed at NASA Ames, the other is the MPI-2 extensions to the MPI Standard. We give timing comparisons for the different implementation strategies and discuss the performance.

  8. Remote Memory Access Protocol Target Node Intellectual Property

    NASA Technical Reports Server (NTRS)

    Haddad, Omar

    2013-01-01

    The MagnetoSpheric Multiscale (MMS) mission had a requirement to use the Remote Memory Access Protocol (RMAP) over its SpaceWire network. At the time, no known intellectual property (IP) cores were available for purchase. Additionally, MMS preferred to implement the RMAP functionality with control over the low-level details of the design. For example, not all the RMAP standard functionality was needed, and it was desired to implement only the portions of the RMAP protocol that were needed. RMAP functionality had been previously implemented in commercial off-the-shelf (COTS) products, but the IP core was not available for purchase. The RMAP Target IP core is a VHDL (VHSIC Hardware Description Language description of a digital logic design suitable for implementation in an FPGA (field-programmable gate array) or ASIC (application-specific integrated circuit) that parses SpaceWire packets that conform to the RMAP standard. The RMAP packet protocol allows a network host to access and control a target device using address mapping. This capability allows SpaceWire devices to be managed in a standardized way that simplifies the hardware design of the device, as well as the development of the software that controls the device. The RMAP Target IP core has some features that are unique and not specified in the RMAP standard. One such feature is the ability to automatically abort transactions if the back-end logic does not respond to read/write requests within a predefined time. When a request times out, the RMAP Target IP core automatically retracts the request and returns a command response with an appropriate status in the response packet s header. Another such feature is the ability to control the SpaceWire node or router using RMAP transactions in the extended address range. This allows the SpaceWire network host to manage the SpaceWire network elements using RMAP packets, which reduces the number of protocols that the network host needs to support.

  9. Symmetric Data Objects and Remote Memory Access Communication for Fortran 95-Applications.

    SciTech Connect

    Nieplocha, Jarek; Baxter, Douglas J.; Tipparaju, Vinod; Rasmussen, Craig; Numrich, Robert W.

    2005-08-01

    Symmetric data objects have been introduced by Cray Inc. in context of SHMEM remote memory access communication on Cray T3D/E systems and later adopted by SGI for their Origin servers. Symmetric data objects greatly simplify parallel programming by allowing to reference remote instance of a data structure by specifying address of the local counterpart. The current paper describes how symmetric data objects and remote memory access communication could be implemented in Fortran-95 without requiring specialized hardware or compiler support. NAS Multi-Grid parallel benchmark was used as an application example and demonstrated competitive performance to the standard MPI implementation

  10. Optimizing NEURON Simulation Environment Using Remote Memory Access with Recursive Doubling on Distributed Memory Systems.

    PubMed

    Shehzad, Danish; Bozkuş, Zeki

    2016-01-01

    Increase in complexity of neuronal network models escalated the efforts to make NEURON simulation environment efficient. The computational neuroscientists divided the equations into subnets amongst multiple processors for achieving better hardware performance. On parallel machines for neuronal networks, interprocessor spikes exchange consumes large section of overall simulation time. In NEURON for communication between processors Message Passing Interface (MPI) is used. MPI_Allgather collective is exercised for spikes exchange after each interval across distributed memory systems. The increase in number of processors though results in achieving concurrency and better performance but it inversely affects MPI_Allgather which increases communication time between processors. This necessitates improving communication methodology to decrease the spikes exchange time over distributed memory systems. This work has improved MPI_Allgather method using Remote Memory Access (RMA) by moving two-sided communication to one-sided communication, and use of recursive doubling mechanism facilitates achieving efficient communication between the processors in precise steps. This approach enhanced communication concurrency and has improved overall runtime making NEURON more efficient for simulation of large neuronal network models. PMID:27413363

  11. Optimizing NEURON Simulation Environment Using Remote Memory Access with Recursive Doubling on Distributed Memory Systems

    PubMed Central

    Bozkuş, Zeki

    2016-01-01

    Increase in complexity of neuronal network models escalated the efforts to make NEURON simulation environment efficient. The computational neuroscientists divided the equations into subnets amongst multiple processors for achieving better hardware performance. On parallel machines for neuronal networks, interprocessor spikes exchange consumes large section of overall simulation time. In NEURON for communication between processors Message Passing Interface (MPI) is used. MPI_Allgather collective is exercised for spikes exchange after each interval across distributed memory systems. The increase in number of processors though results in achieving concurrency and better performance but it inversely affects MPI_Allgather which increases communication time between processors. This necessitates improving communication methodology to decrease the spikes exchange time over distributed memory systems. This work has improved MPI_Allgather method using Remote Memory Access (RMA) by moving two-sided communication to one-sided communication, and use of recursive doubling mechanism facilitates achieving efficient communication between the processors in precise steps. This approach enhanced communication concurrency and has improved overall runtime making NEURON more efficient for simulation of large neuronal network models. PMID:27413363

  12. Evaluation of Remote Memory Access Communication on the Cray XT3

    SciTech Connect

    Kot, Andriy; Tipparaju, Vinod; Nieplocha, Jarek; Bruggencate, Monika T.; Chrisochoides, Nikos

    2007-03-26

    This paper evaluates remote memory access (RMA) communication capabilities and performance on the Cray XT3. We discuss properties of the network hardware and Portals networking software layer and corresponding implementation issues for SHMEM and ARMCI portable RMA interfaces. The performance of these interfaces is studied and compared to MPI performance

  13. Analyzing the Energy and Power Consumption of Remote Memory Accesses in the OpenSHMEM Model

    SciTech Connect

    Jana, Siddhartha; Hernandez, Oscar R; Poole, Stephen W; Hsu, Chung-Hsing; Chapman, Barbara

    2014-01-01

    PGAS models like OpenSHMEM provide interfaces to explicitly initiate one-sided remote memory accesses among processes. In addition, the model also provides synchronizing barriers to ensure a consistent view of the distributed memory at different phases of an application. The incorrect use of such interfaces affects the scalability achievable while using a parallel programming model. This study aims at understanding the effects of these constructs on the energy and power consumption behavior of OpenSHMEM applications. Our experiments show that cost incurred in terms of the total energy and power consumed depends on multiple factors across the software and hardware stack. We conclude that there is a significant impact on the power consumed by the CPU and DRAM due to multiple factors including the design of the data transfer patterns within an application, the design of the communication protocols within a middleware, the architectural constraints laid by the interconnect solutions, and also the levels of memory hierarchy within a compute node. This work motivates treating energy and power consumption as important factors while designing compute solutions for current and future distributed systems.

  14. Towards scalable parellelism in Monte Carlo particle transport codes using remote memory access

    SciTech Connect

    Romano, Paul K; Brown, Forrest B; Forget, Benoit

    2010-01-01

    One forthcoming challenge in the area of high-performance computing is having the ability to run large-scale problems while coping with less memory per compute node. In this work, they investigate a novel data decomposition method that would allow Monte Carlo transport calculations to be performed on systems with limited memory per compute node. In this method, each compute node remotely retrieves a small set of geometry and cross-section data as needed and remotely accumulates local tallies when crossing the boundary of the local spatial domain. initial results demonstrate that while the method does allow large problems to be run in a memory-limited environment, achieving scalability may be difficult due to inefficiencies in the current implementation of RMA operations.

  15. Demystifying Remote Access

    ERIC Educational Resources Information Center

    Howe, Grant

    2009-01-01

    With money tight, more and more districts are considering remote access as a way to reduce expenses and budget information technology costs more effectively. Remote access allows staff members to work with a hosted software application from any school campus without being tied to a specific physical location. Each school can access critical…

  16. Computer memory access technique

    NASA Technical Reports Server (NTRS)

    Zottarelli, L. J.

    1967-01-01

    Computer memory access commutator and steering gate configuration produces bipolar current pulses while still employing only the diodes and magnetic cores of the classic commutator, thereby appreciably reducing the complexity of the memory assembly.

  17. Aggregate Remote Memory Copy Interface

    Energy Science and Technology Software Center (ESTSC)

    2006-02-23

    The purpose of the Aggregate Remote Memory Copy (ARMCI) library is to provide a general- purpose, efficient, and Widely portable remote memory access (RMA) operations (one-sided communication) optimized for Contiguous and noncontiguous (strided, scatter/gather, I/O vector) data transfers. In addition, ARMCI includes a set of atomic and mutual exclusion operations. The development ARMCI is driven by the need to support the global-addres space communication model in context of distributed regular or irregular distributed data structures,more » communication libraries, and compilers. ARMCI is a standalone system that could be used to support user-level libraries and applications that use MPI or PVM.« less

  18. Remote access thyroid surgery

    PubMed Central

    Bhatia, Parisha; Mohamed, Hossam Eldin; Kadi, Abida; Walvekar, Rohan R.

    2015-01-01

    Robot assisted thyroid surgery has been the latest advance in the evolution of thyroid surgery after endoscopy assisted procedures. The advantage of a superior field vision and technical advancements of robotic technology have permitted novel remote access (trans-axillary and retro-auricular) surgical approaches. Interestingly, several remote access surgical ports using robot surgical system and endoscopic technique have been customized to avoid the social stigma of a visible scar. Current literature has displayed their various advantages in terms of post-operative outcomes; however, the associated financial burden and also additional training and expertise necessary hinder its widespread adoption into endocrine surgery practices. These approaches offer excellent cosmesis, with a shorter learning curve and reduce discomfort to surgeons operating ergonomically through a robotic console. This review aims to provide details of various remote access techniques that are being offered for thyroid resection. Though these have been reported to be safe and feasible approaches for thyroid surgery, further evaluation for their efficacy still remains. PMID:26425450

  19. Remote access astronomy

    NASA Astrophysics Data System (ADS)

    Beare, Richard; Bowdley, David; Newsam, Andrew; Roche, Paul

    2003-05-01

    There is still nothing to beat the excitement and fulfilment that you can get from observing celestial bodies on a clear dark night, in a remote location away from the seemingly ever increasing light pollution from cities. However, it is also the specific requirements for good observing that can sometimes prevent teachers from offering this opportunity to their students. Compromises for a town-based school or college might be to view only bright objects such as planets, or stars of magnitude 4 or brighter because of light pollution, but you would still require a knowledgeable teacher or astronomer and equipment to take outside with the students. Remote access astronomy using robotic telescopes can partly provide a solution to these problems and also opens up the doors to exciting projects that may otherwise be inaccessible to schools and colleges.

  20. Remote Data Access with IDL

    NASA Technical Reports Server (NTRS)

    Galloy, Michael

    2013-01-01

    A tool based on IDL (Interactive Data Language) and DAP (Data Access Protocol) has been developed for user-friendly remote data access. A difficulty for many NASA researchers using IDL is that often the data to analyze are located remotely and are too large to transfer for local analysis. Researchers have developed a protocol for accessing remote data, DAP, which is used for both SOHO and STEREO data sets. Server-side side analysis via IDL routine is available through DAP.

  1. Atomic memory access hardware implementations

    SciTech Connect

    Ahn, Jung Ho; Erez, Mattan; Dally, William J

    2015-02-17

    Atomic memory access requests are handled using a variety of systems and methods. According to one example method, a data-processing circuit having an address-request generator that issues requests to a common memory implements a method of processing the requests using a memory-access intervention circuit coupled between the generator and the common memory. The method identifies a current atomic-memory access request from a plurality of memory access requests. A data set is stored that corresponds to the current atomic-memory access request in a data storage circuit within the intervention circuit. It is determined whether the current atomic-memory access request corresponds to at least one previously-stored atomic-memory access request. In response to determining correspondence, the current request is implemented by retrieving data from the common memory. The data is modified in response to the current request and at least one other access request in the memory-access intervention circuit.

  2. Is random access memory random?

    NASA Technical Reports Server (NTRS)

    Denning, P. J.

    1986-01-01

    Most software is contructed on the assumption that the programs and data are stored in random access memory (RAM). Physical limitations on the relative speeds of processor and memory elements lead to a variety of memory organizations that match processor addressing rate with memory service rate. These include interleaved and cached memory. A very high fraction of a processor's address requests can be satified from the cache without reference to the main memory. The cache requests information from main memory in blocks that can be transferred at the full memory speed. Programmers who organize algorithms for locality can realize the highest performance from these computers.

  3. Ferroelectric random access memories.

    PubMed

    Ishiwara, Hiroshi

    2012-10-01

    Ferroelectric random access memory (FeRAM) is a nonvolatile memory, in which data are stored using hysteretic P-E (polarization vs. electric field) characteristics in a ferroelectric film. In this review, history and characteristics of FeRAMs are first introduced. It is described that there are two types of FeRAMs, capacitor-type and FET-type, and that only the capacitor-type FeRAM is now commercially available. In chapter 2, properties of ferroelectric films are discussed from a viewpoint of FeRAM application, in which particular attention is paid to those of Pb(Zr,Ti)O3, SrBi2Ta2O9, and BiFeO3. Then, cell structures and operation principle of the capacitor-type FeRAMs are discussed in chapter 3. It is described that the stacked technology of ferroelectric capacitors and development of new materials with large remanent polarization are important for fabricating high-density memories. Finally, in chapter 4, the optimized gate structure in ferroelectric-gate field-effect transistors is discussed and experimental results showing excellent data retention characteristics are presented. PMID:23421123

  4. REMEM: REmote MEMory as Checkpointing Storage

    SciTech Connect

    Jin, Hui; Sun, Xian-He; Chen, Yong; Ke, Tao

    2010-01-01

    Checkpointing is a widely used mechanism for supporting fault tolerance, but notorious in its high-cost disk access. The idea of memory-based checkpointing has been extensively studied in research but made little success in practice due to its complexity and potential reliability concerns. In this study we present the design and implementation of REMEM, a REmote MEMory checkpointing system to extend the checkpointing storage from disk to remote memory. A unique feature of REMEM is that it can be integrated into existing disk-based checkpointing systems seamlessly. A user can flexibly switch between REMEM and disk as checkpointing storage to balance the efficiency and reliability. The implementation of REMEM on Open MPI is also introduced. The experimental results confirm that REMEM and the proposed adaptive checkpointing storage selection are promising in both performance, reliability and scalability.

  5. Preparing for the New Remote Access.

    ERIC Educational Resources Information Center

    Taylor, William E.

    1997-01-01

    Integrated remote access servers support many different types of access. Remote access has been integrated as a strategic tool as application developers build remote access capabilities into their software. Discusses demands of using remote access as a strategic component and management matters. (AEF)

  6. Remote Access Astronomy

    ERIC Educational Resources Information Center

    Beare, Richard; Bowdley, David; Newsam, Andrew; Roche, Paul

    2003-01-01

    There is still nothing to beat the excitement and fulfilment that you can get from observing celestial bodies on a clear dark night, in a remote location away from the seemingly ever increasing light pollution from cities. However, it is also the specific requirements for good observing that can sometimes prevent teachers from offering this…

  7. Nonvolatile random access memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor)

    1994-01-01

    A nonvolatile magnetic random access memory can be achieved by an array of magnet-Hall effect (M-H) elements. The storage function is realized with a rectangular thin-film ferromagnetic material having an in-plane, uniaxial anisotropy and inplane bipolar remanent magnetization states. The thin-film magnetic element is magnetized by a local applied field, whose direction is used to form either a 0 or 1 state. The element remains in the 0 or 1 state until a switching field is applied to change its state. The stored information is detcted by a Hall-effect sensor which senses the fringing field from the magnetic storage element. The circuit design for addressing each cell includes transistor switches for providing a current of selected polarity to store a binary digit through a separate conductor overlying the magnetic element of the cell. To read out a stored binary digit, transistor switches are employed to provide a current through a row of Hall-effect sensors connected in series and enabling a differential voltage amplifier connected to all Hall-effect sensors of a column in series. To avoid read-out voltage errors due to shunt currents through resistive loads of the Hall-effect sensors of other cells in the same column, at least one transistor switch is provided between every pair of adjacent cells in every row which are not turned on except in the row of the selected cell.

  8. Garnet Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.

    1995-01-01

    Random-access memory (RAM) devices of proposed type exploit magneto-optical properties of magnetic garnets exhibiting perpendicular anisotropy. Magnetic writing and optical readout used. Provides nonvolatile storage and resists damage by ionizing radiation. Because of basic architecture and pinout requirements, most likely useful as small-capacity memory devices.

  9. Plated wire random access memories

    NASA Technical Reports Server (NTRS)

    Gouldin, L. D.

    1975-01-01

    A program was conducted to construct 4096-work by 18-bit random access, NDRO-plated wire memory units. The memory units were subjected to comprehensive functional and environmental tests at the end-item level to verify comformance with the specified requirements. A technical description of the unit is given, along with acceptance test data sheets.

  10. Remotely Accessible Management System (RAMS).

    ERIC Educational Resources Information Center

    Wood, Rex

    Oakland Schools, an Intermediate School District for Administration, operates a Remotely Accessible Management System (RAMS). RAMS is composed of over 100 computer programs, each of which performs procedures on the files of the 28 local school districts comprising the constituency of Oakland Schools. This regional service agency covers 900 square…

  11. Memory availability and referential access

    PubMed Central

    Johns, Clinton L.; Gordon, Peter C.; Long, Debra L.; Swaab, Tamara Y.

    2013-01-01

    Most theories of coreference specify linguistic factors that modulate antecedent accessibility in memory; however, whether non-linguistic factors also affect coreferential access is unknown. Here we examined the impact of a non-linguistic generation task (letter transposition) on the repeated-name penalty, a processing difficulty observed when coreferential repeated names refer to syntactically prominent (and thus more accessible) antecedents. In Experiment 1, generation improved online (event-related potentials) and offline (recognition memory) accessibility of names in word lists. In Experiment 2, we manipulated generation and syntactic prominence of antecedent names in sentences; both improved online and offline accessibility, but only syntactic prominence elicited a repeated-name penalty. Our results have three important implications: first, the form of a referential expression interacts with an antecedent’s status in the discourse model during coreference; second, availability in memory and referential accessibility are separable; and finally, theories of coreference must better integrate known properties of the human memory system. PMID:24443621

  12. Runtime and Programming Support for Memory Adaptation in Scientific Applications via Local Disk and Remote Memory

    SciTech Connect

    Mills, Richard T; Yue, Chuan; Andreas, Stathopoulos; Nikolopoulos, Dimitrios S

    2007-01-01

    The ever increasing memory demands of many scientific applications and the complexity of today's shared computational resources still require the occasional use of virtual memory, network memory, or even out-of-core implementations, with well known drawbacks in performance and usability. In Mills et al. (Adapting to memory pressure from within scientific applications on multiprogrammed COWS. In: International Parallel and Distributed Processing Symposium, IPDPS, Santa Fe, NM, 2004), we introduced a basic framework for a runtime, user-level library, MMlib, in which DRAM is treated as a dynamic size cache for large memory objects residing on local disk. Application developers can specify and access these objects through MMlib, enabling their application to execute optimally under variable memory availability, using as much DRAM as fluctuating memory levels will allow. In this paper, we first extend our earlier MMlib prototype from a proof of concept to a usable, robust, and flexible library. We present a general framework that enables fully customizable memory malleability in a wide variety of scientific applications. We provide several necessary enhancements to the environment sensing capabilities of MMlib, and introduce a remote memory capability, based on MPI communication of cached memory blocks between 'compute nodes' and designated memory servers. The increasing speed of interconnection networks makes a remote memory approach attractive, especially at the large granularity present in large scientific applications. We show experimental results from three important scientific applications that require the general MMlib framework. The memory-adaptive versions perform nearly optimally under constant memory pressure and execute harmoniously with other applications competing for memory, without thrashing the memory system. Under constant memory pressure, we observe execution time improvements of factors between three and

  13. Dynamic computing random access memory

    NASA Astrophysics Data System (ADS)

    Traversa, F. L.; Bonani, F.; Pershin, Y. V.; Di Ventra, M.

    2014-07-01

    The present von Neumann computing paradigm involves a significant amount of information transfer between a central processing unit and memory, with concomitant limitations in the actual execution speed. However, it has been recently argued that a different form of computation, dubbed memcomputing (Di Ventra and Pershin 2013 Nat. Phys. 9 200-2) and inspired by the operation of our brain, can resolve the intrinsic limitations of present day architectures by allowing for computing and storing of information on the same physical platform. Here we show a simple and practical realization of memcomputing that utilizes easy-to-build memcapacitive systems. We name this architecture dynamic computing random access memory (DCRAM). We show that DCRAM provides massively-parallel and polymorphic digital logic, namely it allows for different logic operations with the same architecture, by varying only the control signals. In addition, by taking into account realistic parameters, its energy expenditures can be as low as a few fJ per operation. DCRAM is fully compatible with CMOS technology, can be realized with current fabrication facilities, and therefore can really serve as an alternative to the present computing technology.

  14. Dynamic computing random access memory.

    PubMed

    Traversa, F L; Bonani, F; Pershin, Y V; Di Ventra, M

    2014-07-18

    The present von Neumann computing paradigm involves a significant amount of information transfer between a central processing unit and memory, with concomitant limitations in the actual execution speed. However, it has been recently argued that a different form of computation, dubbed memcomputing (Di Ventra and Pershin 2013 Nat. Phys. 9 200-2) and inspired by the operation of our brain, can resolve the intrinsic limitations of present day architectures by allowing for computing and storing of information on the same physical platform. Here we show a simple and practical realization of memcomputing that utilizes easy-to-build memcapacitive systems. We name this architecture dynamic computing random access memory (DCRAM). We show that DCRAM provides massively-parallel and polymorphic digital logic, namely it allows for different logic operations with the same architecture, by varying only the control signals. In addition, by taking into account realistic parameters, its energy expenditures can be as low as a few fJ per operation. DCRAM is fully compatible with CMOS technology, can be realized with current fabrication facilities, and therefore can really serve as an alternative to the present computing technology. PMID:24972387

  15. Memory access in shared virtual memory

    SciTech Connect

    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.

  16. Memory access in shared virtual memory

    SciTech Connect

    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.

  17. Remote Access Laboratories in Australia and Europe

    ERIC Educational Resources Information Center

    Ku, H.; Ahfock, T.; Yusaf, T.

    2011-01-01

    Remote access laboratories (RALs) were first developed in 1994 in Australia and Switzerland. The main purposes of developing them are to enable students to do their experiments at their own pace, time and locations and to enable students and teaching staff to get access to facilities beyond their institutions. Currently, most of the experiments…

  18. Magnetic Analog Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.; Wu, Jiin-Chuan; Stadler, Henry L.

    1991-01-01

    Proposed integrated, solid-state, analog random-access memory base on principle of magnetic writing and magnetoresistive reading. Current in writing conductor magnetizes storage layer. Remanent magnetization in storage layer penetrates readout layer and detected by magnetoresistive effect or Hall effect. Memory cells are part of integrated circuit including associated reading and writing transistors. Intended to provide high storage density and rapid access, nonvolatile, consumes little power, and relatively invulnerable to ionizing radiation.

  19. Access to Service: Rural and Remote Communities.

    ERIC Educational Resources Information Center

    Knight, Robert

    This paper discusses public library services to remote communities in Australia, focusing on New South Wales (NSW). The first section presents background on the public library network in NSW, including statistics, descriptors/characteristics of public libraries, and funding to establish public Internet access. The second section addresses regional…

  20. A Simple Solution to Providing Remote Access to CD-ROM.

    ERIC Educational Resources Information Center

    Garnham, Carla T.; Brodie, Kent

    1990-01-01

    A pilot project at the Medical College of Wisconsin illustrates how even small computing organizations with limited financial and staff resources can provide remote access to CD-ROM (Compact Disc-Read-Only-Memory) databases, and that providing such convenient access to a vast array of useful information can greatly benefit faculty and students.…

  1. Remote Preparation of an Atomic Quantum Memory

    SciTech Connect

    Rosenfeld, Wenjamin; Berner, Stefan; Volz, Juergen; Weber, Markus; Weinfurter, Harald

    2007-02-02

    Storage and distribution of quantum information are key elements of quantum information processing and future quantum communication networks. Here, using atom-photon entanglement as the main physical resource, we experimentally demonstrate the preparation of a distant atomic quantum memory. Applying a quantum teleportation protocol on a locally prepared state of a photonic qubit, we realized this so-called remote state preparation on a single, optically trapped {sup 87}Rb atom. We evaluated the performance of this scheme by the full tomography of the prepared atomic state, reaching an average fidelity of 82%.

  2. Low latency memory access and synchronization

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Hoenicke, Dirk; Ohmacht, Martin; Steinmacher-Burow, Burkhard D.; Takken, Todd E.; Vranas, Pavlos M.

    2007-02-06

    A low latency memory system access is provided in association with a weakly-ordered multiprocessor system. Each processor in the multiprocessor shares resources, and each shared resource has an associated lock within a locking device that provides support for synchronization between the multiple processors in the multiprocessor and the orderly sharing of the resources. A processor only has permission to access a resource when it owns the lock associated with that resource, and an attempt by a processor to own a lock requires only a single load operation, rather than a traditional atomic load followed by store, such that the processor only performs a read operation and the hardware locking device performs a subsequent write operation rather than the processor. A simple prefetching for non-contiguous data structures is also disclosed. A memory line is redefined so that in addition to the normal physical memory data, every line includes a pointer that is large enough to point to any other line in the memory, wherein the pointers to determine which memory line to prefetch rather than some other predictive algorithm. This enables hardware to effectively prefetch memory access patterns that are non-contiguous, but repetitive.

  3. Low latency memory access and synchronization

    DOEpatents

    Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Hoenicke, Dirk; Ohmacht, Martin; Steinmacher-Burow, Burkhard D.; Takken, Todd E. , Vranas; Pavlos M.

    2010-10-19

    A low latency memory system access is provided in association with a weakly-ordered multiprocessor system. Bach processor in the multiprocessor shares resources, and each shared resource has an associated lock within a locking device that provides support for synchronization between the multiple processors in the multiprocessor and the orderly sharing of the resources. A processor only has permission to access a resource when it owns the lock associated with that resource, and an attempt by a processor to own a lock requires only a single load operation, rather than a traditional atomic load followed by store, such that the processor only performs a read operation and the hardware locking device performs a subsequent write operation rather than the processor. A simple prefetching for non-contiguous data structures is also disclosed. A memory line is redefined so that in addition to the normal physical memory data, every line includes a pointer that is large enough to point to any other line in the memory, wherein the pointers to determine which memory line to prefetch rather than some other predictive algorithm. This enables hardware to effectively prefetch memory access patterns that are non-contiguous, but repetitive.

  4. Neural mechanism underlying autobiographical memory modulated by remoteness and emotion

    NASA Astrophysics Data System (ADS)

    Ge, Ruiyang; Fu, Yan; Wang, DaHua; Yao, Li; Long, Zhiying

    2012-03-01

    Autobiographical memory is the ability to recollect past events from one's own life. Both emotional tone and memory remoteness can influence autobiographical memory retrieval along the time axis of one's life. Although numerous studies have been performed to investigate brain regions involved in retrieving processes of autobiographical memory, the effect of emotional tone and memory age on autobiographical memory retrieval remains to be clarified. Moreover, whether the involvement of hippocampus in consolidation of autobiographical events is time dependent or independent has been controversial. In this study, we investigated the effect of memory remoteness (factor1: recent and remote) and emotional valence (factor2: positive and negative) on neural correlates underlying autobiographical memory by using functional magnetic resonance imaging (fMRI) technique. Although all four conditions activated some common regions known as "core" regions in autobiographical memory retrieval, there are some other regions showing significantly different activation for recent versus remote and positive versus negative memories. In particular, we found that bilateral hippocampal regions were activated in the four conditions regardless of memory remoteness and emotional valence. Thus, our study confirmed some findings of previous studies and provided further evidence to support the multi-trace theory which believes that the role of hippocampus involved in autobiographical memory retrieval is time-independent and permanent in memory consolidation.

  5. Non-volatile magnetic random access memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R. (Inventor); Stadler, Henry L. (Inventor); Wu, Jiin-Chuan (Inventor)

    1994-01-01

    Improvements are made in a non-volatile magnetic random access memory. Such a memory is comprised of an array of unit cells, each having a Hall-effect sensor and a thin-film magnetic element made of material having an in-plane, uniaxial anisotropy and in-plane, bipolar remanent magnetization states. The Hall-effect sensor is made more sensitive by using a 1 m thick molecular beam epitaxy grown InAs layer on a silicon substrate by employing a GaAs/AlGaAs/InAlAs superlattice buffering layer. One improvement avoids current shunting problems of matrix architecture. Another improvement reduces the required magnetizing current for the micromagnets. Another improvement relates to the use of GaAs technology wherein high electron-mobility GaAs MESFETs provide faster switching times. Still another improvement relates to a method for configuring the invention as a three-dimensional random access memory.

  6. Remote access laboratories in Australia and Europe

    NASA Astrophysics Data System (ADS)

    Ku, H.; Ahfock, T.; Yusaf, T.

    2011-06-01

    Remote access laboratories (RALs) were first developed in 1994 in Australia and Switzerland. The main purposes of developing them are to enable students to do their experiments at their own pace, time and locations and to enable students and teaching staff to get access to facilities beyond their institutions. Currently, most of the experiments carried out through RALs in Australia are heavily biased towards electrical, electronic and computer engineering disciplines. However, the experiments carried out through RALs in Europe had more variety, in addition to the traditional electrical, electronic and computer engineering disciplines, there were experiments in mechanical and mechatronic disciplines. It was found that RALs are now being developed aggressively in Australia and Europe and it can be argued that RALs will develop further and faster in the future with improving Internet technology. The rising costs of real experimental equipment will also speed up their development because by making the equipment remotely accessible, the cost can be shared by more universities or institutions and this will improve their cost-effectiveness. Their development would be particularly rapid in large countries with small populations such as Australia, Canada and Russia, because of the scale of economy. Reusability of software, interoperability in software implementation, computer supported collaborative learning and convergence with learning management systems are the required development of future RALs.

  7. An integrated solution for remote data access

    NASA Astrophysics Data System (ADS)

    Sapunenko, Vladimir; D'Urso, Domenico; dell'Agnello, Luca; Vagnoni, Vincenzo; Duranti, Matteo

    2015-12-01

    Data management constitutes one of the major challenges that a geographically- distributed e-Infrastructure has to face, especially when remote data access is involved. We discuss an integrated solution which enables transparent and efficient access to on-line and near-line data through high latency networks. The solution is based on the joint use of the General Parallel File System (GPFS) and of the Tivoli Storage Manager (TSM). Both products, developed by IBM, are well known and extensively used in the HEP computing community. Owing to a new feature introduced in GPFS 3.5, so-called Active File Management (AFM), the definition of a single, geographically-distributed namespace, characterised by automated data flow management between different locations, becomes possible. As a practical example, we present the implementation of AFM-based remote data access between two data centres located in Bologna and Rome, demonstrating the validity of the solution for the use case of the AMS experiment, an astro-particle experiment supported by the INFN CNAF data centre with the large disk space requirements (more than 1.5 PB).

  8. Stability of Recent and Remote Contextual Fear Memory

    ERIC Educational Resources Information Center

    Frankland, Paul W.; Ding, Hoi-Ki; Takahashi, Eiki; Suzuki, Akinobu; Kida, Satoshi; Silva, Alcino J.

    2006-01-01

    Following initial encoding, memories undergo a prolonged period of reorganization. While such reorganization may occur in many different memory systems, its purpose is not clear. Previously, we have shown that recall of recent contextual fear memories engages the dorsal hippocampus (dHPC). In contrast, recall of remote contextual fear memories…

  9. Remoteness and Access to Learning Opportunities in the Pacific Region.

    ERIC Educational Resources Information Center

    Pacific Region Educational Lab., Honolulu, HI.

    The Remoteness and Access to Learning Opportunities in the Pacific Region Study was carried out to investigate whether access to learning opportunities (ALO) is related to the remoteness and isolation of many schools in the Pacific region. The study also profiles the conditions of remote and isolated schools and the ALO for Pacific students. Seven…

  10. A Web-Based Remote Access Laboratory Using SCADA

    ERIC Educational Resources Information Center

    Aydogmus, Z.; Aydogmus, O.

    2009-01-01

    The Internet provides an opportunity for students to access laboratories from outside the campus. This paper presents a Web-based remote access real-time laboratory using SCADA (supervisory control and data acquisition) control. The control of an induction motor is used as an example to demonstrate the effectiveness of this remote laboratory,…

  11. Remotely accessible laboratory for MEMS testing

    NASA Astrophysics Data System (ADS)

    Sivakumar, Ganapathy; Mulsow, Matthew; Melinger, Aaron; Lacouture, Shelby; Dallas, Tim E.

    2010-02-01

    We report on the construction of a remotely accessible and interactive laboratory for testing microdevices (aka: MicroElectroMechancial Systems - MEMS). Enabling expanded utilization of microdevices for research, commercial, and educational purposes is very important for driving the creation of future MEMS devices and applications. Unfortunately, the relatively high costs associated with MEMS devices and testing infrastructure makes widespread access to the world of MEMS difficult. The creation of a virtual lab to control and actuate MEMS devices over the internet helps spread knowledge to a larger audience. A host laboratory has been established that contains a digital microscope, microdevices, controllers, and computers that can be logged into through the internet. The overall layout of the tele-operated MEMS laboratory system can be divided into two major parts: the server side and the client side. The server-side is present at Texas Tech University, and hosts a server machine that runs the Linux operating system and is used for interfacing the MEMS lab with the outside world via internet. The controls from the clients are transferred to the lab side through the server interface. The server interacts with the electronics required to drive the MEMS devices using a range of National Instruments hardware and LabView Virtual Instruments. An optical microscope (100 ×) with a CCD video camera is used to capture images of the operating MEMS. The server broadcasts the live video stream over the internet to the clients through the website. When the button is pressed on the website, the MEMS device responds and the video stream shows the movement in close to real time.

  12. Education Access: National Inquiry into Rural and Remote Education.

    ERIC Educational Resources Information Center

    Balsamo, Fabienne

    This report examines limits on access to education in Australia. Accessibility must be available without discrimination because of physical or economic limitations. Chapters are devoted to nine different types of limited accessibility, affecting: children with disabilities, especially in remote areas without alternative local schools; children…

  13. Parallel Optical Random Access Memory (PORAM)

    NASA Technical Reports Server (NTRS)

    Alphonse, G. A.

    1989-01-01

    It is shown that the need to minimize component count, power and size, and to maximize packing density require a parallel optical random access memory to be designed in a two-level hierarchy: a modular level and an interconnect level. Three module designs are proposed, in the order of research and development requirements. The first uses state-of-the-art components, including individually addressed laser diode arrays, acousto-optic (AO) deflectors and magneto-optic (MO) storage medium, aimed at moderate size, moderate power, and high packing density. The next design level uses an electron-trapping (ET) medium to reduce optical power requirements. The third design uses a beam-steering grating surface emitter (GSE) array to reduce size further and minimize the number of components.

  14. Direct memory access transfer completion notification

    DOEpatents

    Chen, Dong; Giampapa, Mark E.; Heidelberger, Philip; Kumar, Sameer; Parker, Jeffrey J.; Steinmacher-Burow, Burkhard D.; Vranas, Pavlos

    2010-07-27

    Methods, compute nodes, and computer program products are provided for direct memory access (`DMA`) transfer completion notification. Embodiments include determining, by an origin DMA engine on an origin compute node, whether a data descriptor for an application message to be sent to a target compute node is currently in an injection first-in-first-out (`FIFO`) buffer in dependence upon a sequence number previously associated with the data descriptor, the total number of descriptors currently in the injection FIFO buffer, and the current sequence number for the newest data descriptor stored in the injection FIFO buffer; and notifying a processor core on the origin DMA engine that the message has been sent if the data descriptor for the message is not currently in the injection FIFO buffer.

  15. Conductance Quantization in Resistive Random Access Memory.

    PubMed

    Li, Yang; Long, Shibing; Liu, Yang; Hu, Chen; Teng, Jiao; Liu, Qi; Lv, Hangbing; Suñé, Jordi; Liu, Ming

    2015-12-01

    The intrinsic scaling-down ability, simple metal-insulator-metal (MIM) sandwich structure, excellent performances, and complementary metal-oxide-semiconductor (CMOS) technology-compatible fabrication processes make resistive random access memory (RRAM) one of the most promising candidates for the next-generation memory. The RRAM device also exhibits rich electrical, thermal, magnetic, and optical effects, in close correlation with the abundant resistive switching (RS) materials, metal-oxide interface, and multiple RS mechanisms including the formation/rupture of nanoscale to atomic-sized conductive filament (CF) incorporated in RS layer. Conductance quantization effect has been observed in the atomic-sized CF in RRAM, which provides a good opportunity to deeply investigate the RS mechanism in mesoscopic dimension. In this review paper, the operating principles of RRAM are introduced first, followed by the summarization of the basic conductance quantization phenomenon in RRAM and the related RS mechanisms, device structures, and material system. Then, we discuss the theory and modeling of quantum transport in RRAM. Finally, we present the opportunities and challenges in quantized RRAM devices and our views on the future prospects. PMID:26501832

  16. Conductance Quantization in Resistive Random Access Memory

    NASA Astrophysics Data System (ADS)

    Li, Yang; Long, Shibing; Liu, Yang; Hu, Chen; Teng, Jiao; Liu, Qi; Lv, Hangbing; Suñé, Jordi; Liu, Ming

    2015-10-01

    The intrinsic scaling-down ability, simple metal-insulator-metal (MIM) sandwich structure, excellent performances, and complementary metal-oxide-semiconductor (CMOS) technology-compatible fabrication processes make resistive random access memory (RRAM) one of the most promising candidates for the next-generation memory. The RRAM device also exhibits rich electrical, thermal, magnetic, and optical effects, in close correlation with the abundant resistive switching (RS) materials, metal-oxide interface, and multiple RS mechanisms including the formation/rupture of nanoscale to atomic-sized conductive filament (CF) incorporated in RS layer. Conductance quantization effect has been observed in the atomic-sized CF in RRAM, which provides a good opportunity to deeply investigate the RS mechanism in mesoscopic dimension. In this review paper, the operating principles of RRAM are introduced first, followed by the summarization of the basic conductance quantization phenomenon in RRAM and the related RS mechanisms, device structures, and material system. Then, we discuss the theory and modeling of quantum transport in RRAM. Finally, we present the opportunities and challenges in quantized RRAM devices and our views on the future prospects.

  17. CameraCast: flexible access to remote video sensors

    NASA Astrophysics Data System (ADS)

    Kong, Jiantao; Ganev, Ivan; Schwan, Karsten; Widener, Patrick

    2007-01-01

    New applications like remote surveillance and online environmental or traffic monitoring are making it increasingly important to provide flexible and protected access to remote video sensor devices. Current systems use application-level codes like web-based solutions to provide such access. This requires adherence to user-level APIs provided by such services, access to remote video information through given application-specific service and server topologies, and that the data being captured and distributed is manipulated by third party service codes. CameraCast is a simple, easily used system-level solution to remote video access. It provides a logical device API so that an application can identically operate on local vs. remote video sensor devices, using its own service and server topologies. In addition, the application can take advantage of API enhancements to protect remote video information, using a capability-based model for differential data protection that offers fine grain control over the information made available to specific codes or machines, thereby limiting their ability to violate privacy or security constraints. Experimental evaluations of CameraCast show that the performance of accessing remote video information approximates that of accesses to local devices, given sufficient networking resources. High performance is also attained when protection restrictions are enforced, due to an efficient kernel-level realization of differential data protection.

  18. 76 FR 55417 - In the Matter of Certain Dynamic Random Access Memory and Nand Flash Memory Devices and Products...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... COMMISSION In the Matter of Certain Dynamic Random Access Memory and Nand Flash Memory Devices and Products... States after importation of certain dynamic random access memory and NAND flash memory devices and... the sale within the United States after importation of certain dynamic random access memory and...

  19. Generation-based memory synchronization in a multiprocessor system with weakly consistent memory accesses

    DOEpatents

    Ohmacht, Martin

    2014-09-09

    In a multiprocessor system, a central memory synchronization module coordinates memory synchronization requests responsive to memory access requests in flight, a generation counter, and a reclaim pointer. The central module communicates via point-to-point communication. The module includes a global OR reduce tree for each memory access requesting device, for detecting memory access requests in flight. An interface unit is implemented associated with each processor requesting synchronization. The interface unit includes multiple generation completion detectors. The generation count and reclaim pointer do not pass one another.

  20. Extinction Partially Reverts Structural Changes Associated with Remote Fear Memory

    ERIC Educational Resources Information Center

    Vetere, Gisella; Restivo, Leonardo; Novembre, Giovanni; Aceti, Massimiliano; Lumaca, Massimo; Ammassari-Teule, Martine

    2011-01-01

    Structural synaptic changes occur in medial prefrontal cortex circuits during remote memory formation. Whether extinction reverts or further reshapes these circuits is, however, unknown. Here we show that the number and the size of spines were enhanced in anterior cingulate (aCC) and infralimbic (ILC) cortices 36 d following contextual fear…

  1. Remote semantic memory is impoverished in hippocampal amnesia.

    PubMed

    Klooster, Nathaniel B; Duff, Melissa C

    2015-12-01

    The necessity of the hippocampus for acquiring new semantic concepts is a topic of considerable debate. However, it is generally accepted that any role the hippocampus plays in semantic memory is time limited and that previously acquired information becomes independent of the hippocampus over time. This view, along with intact naming and word-definition matching performance in amnesia, has led to the notion that remote semantic memory is intact in patients with hippocampal amnesia. Motivated by perspectives of word learning as a protracted process where additional features and senses of a word are added over time, and by recent discoveries about the time course of hippocampal contributions to on-line relational processing, reconsolidation, and the flexible integration of information, we revisit the notion that remote semantic memory is intact in amnesia. Using measures of semantic richness and vocabulary depth from psycholinguistics and first and second language-learning studies, we examined how much information is associated with previously acquired, highly familiar words in a group of patients with bilateral hippocampal damage and amnesia. Relative to healthy demographically matched comparison participants and a group of brain-damaged comparison participants, the patients with hippocampal amnesia performed significantly worse on both productive and receptive measures of vocabulary depth and semantic richness. These findings suggest that remote semantic memory is impoverished in patients with hippocampal amnesia and that the hippocampus may play a role in the maintenance and updating of semantic memory beyond its initial acquisition. PMID:26474741

  2. Remotely Accessed Vehicle Traffic Management System

    NASA Astrophysics Data System (ADS)

    Al-Alawi, Raida

    2010-06-01

    The ever increasing number of vehicles in most metropolitan cities around the world and the limitation in altering the transportation infrastructure, led to serious traffic congestion and an increase in the travelling time. In this work we exploit the emergence of novel technologies such as the internet, to design an intelligent Traffic Management System (TMS) that can remotely monitor and control a network of traffic light controllers located at different sites. The system is based on utilizing Embedded Web Servers (EWS) technology to design a web-based TMS. The EWS located at each intersection uses IP technology for communicating remotely with a Central Traffic Management Unit (CTMU) located at the traffic department authority. Friendly GUI software installed at the CTMU will be able to monitor the sequence of operation of the traffic lights and the presence of traffic at each intersection as well as remotely controlling the operation of the signals. The system has been validated by constructing a prototype that resembles the real application.

  3. BCH codes for large IC random-access memory systems

    NASA Technical Reports Server (NTRS)

    Lin, S.; Costello, D. J., Jr.

    1983-01-01

    In this report some shortened BCH codes for possible applications to large IC random-access memory systems are presented. These codes are given by their parity-check matrices. Encoding and decoding of these codes are discussed.

  4. Radiation Effects of Commercial Resistive Random Access Memories

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; LaBel, Kenneth; Berg, Melanie; Wilcox, Edward; Kim, Hak; Phan, Anthony; Figueiredo, Marco; Buchner, Stephen; Khachatrian, Ani; Roche, Nicolas

    2014-01-01

    We present results for the single-event effect response of commercial production-level resistive random access memories. We found that the resistive memory arrays are immune to heavy ion-induced upsets. However, the devices were susceptible to single-event functional interrupts, due to upsets from the control circuits. The intrinsic radiation tolerant nature of resistive memory makes the technology an attractive consideration for future space applications.

  5. The Dynamics of Access to Groups in Working Memory

    ERIC Educational Resources Information Center

    Farrell, Simon; Lelievre, Anna

    2012-01-01

    The finding that participants leave a pause between groups when attempting serial recall of temporally grouped lists has been taken to indicate access to a hierarchical representation of the list in working memory. An alternative explanation is that the dynamics of serial recall solely reflect output (rather than memorial) processes, with the…

  6. Remote I/O : fast access to distant storage.

    SciTech Connect

    Foster, I.; Kohr, D., Jr.; Krishnaiyer, R.; Mogill, J.

    1997-12-17

    As high-speed networks make it easier to use distributed resources, it becomes increasingly common that applications and their data are not colocated. Users have traditionally addressed this problem by manually staging data to and from remote computers. We argue instead for a new remote I/O paradigm in which programs use familiar parallel I/O interfaces to access remote file systems. In addition to simplifying remote execution, remote I/O can improve performance relative to staging by overlapping computation and data transfer or by reducing communication requirements. However, remote I/O also introduces new technical challenges in the areas of portability, performance, and integration with distributed computing systems. We propose techniques designed to address these challenges and describe a remote I/O library called RIO that we have developed to evaluate the effectiveness of these techniques. RIO addresses issues of portability by adopting the quasi-standard MPI-IO interface and by defining a RIO device and RIO server within the ADIO abstract I/O device architecture. It addresses performance issues by providing traditional I/O optimizations such as asynchronous operations and through implementation techniques such as buffering and message forwarding to off load communication overheads. RIO uses the Nexus communication library to obtain access to configuration and security mechanisms provided by the Globus wide area computing tool kit. Microbenchmarks and application experiments demonstrate that our techniques achieve acceptable performance in most situations and can improve turnaround time relative to staging.

  7. 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.

  8. Memory for recently accessed visual attributes.

    PubMed

    Jiang, Yuhong V; Shupe, Joshua M; Swallow, Khena M; Tan, Deborah H

    2016-08-01

    Recent reports have suggested that the attended features of an item may be rapidly forgotten once they are no longer relevant for an ongoing task (attribute amnesia). This finding relies on a surprise memory procedure that places high demands on declarative memory. We used intertrial priming to examine whether the representation of an item's identity is lost completely once it becomes task irrelevant. If so, then the identity of a target on one trial should not influence performance on the next trial. In 3 experiments, we replicated the finding that a target's identity is poorly recognized in a surprise memory test. However, we also observed location and identity repetition priming across consecutive trials. These data suggest that, although explicit recognition on a surprise memory test may be impaired, some information about a particular target's identity can be retained after it is no longer needed for a task. (PsycINFO Database Record PMID:26844575

  9. Integrated semiconductor-magnetic random access memory system

    NASA Technical Reports Server (NTRS)

    Katti, Romney R. (Inventor); Blaes, Brent R. (Inventor)

    2001-01-01

    The present disclosure describes a non-volatile magnetic random access memory (RAM) system having a semiconductor control circuit and a magnetic array element. The integrated magnetic RAM system uses CMOS control circuit to read and write data magnetoresistively. The system provides a fast access, non-volatile, radiation hard, high density RAM for high speed computing.

  10. Reversible Hippocampal Lesions Disrupt Water Maze Performance during Both Recent and Remote Memory Tests

    ERIC Educational Resources Information Center

    Broadbent, Nicola J.; Squire, Larry R.; Clark, Robert E.

    2006-01-01

    Conventional lesion methods have shown that damage to the rodent hippocampus can impair previously acquired spatial memory in tasks such as the water maze. In contrast, work with reversible lesion methods using a different spatial task has found remote memory to be spared. To determine whether the finding of spared remote spatial memory depends on…

  11. Quantum teleportation between remote atomic-ensemble quantum memories

    PubMed Central

    Bao, Xiao-Hui; Xu, Xiao-Fan; Li, Che-Ming; Yuan, Zhen-Sheng; Lu, Chao-Yang; Pan, Jian-Wei

    2012-01-01

    Quantum teleportation and quantum memory are two crucial elements for large-scale quantum networks. With the help of prior distributed entanglement as a “quantum channel,” quantum teleportation provides an intriguing means to faithfully transfer quantum states among distant locations without actual transmission of the physical carriers [Bennett CH, et al. (1993) Phys Rev Lett 70(13):1895–1899]. Quantum memory enables controlled storage and retrieval of fast-flying photonic quantum bits with stationary matter systems, which is essential to achieve the scalability required for large-scale quantum networks. Combining these two capabilities, here we realize quantum teleportation between two remote atomic-ensemble quantum memory nodes, each composed of ∼108 rubidium atoms and connected by a 150-m optical fiber. The spin wave state of one atomic ensemble is mapped to a propagating photon and subjected to Bell state measurements with another single photon that is entangled with the spin wave state of the other ensemble. Two-photon detection events herald the success of teleportation with an average fidelity of 88(7)%. Besides its fundamental interest as a teleportation between two remote macroscopic objects, our technique may be useful for quantum information transfer between different nodes in quantum networks and distributed quantum computing. PMID:23144222

  12. Quantum teleportation between remote atomic-ensemble quantum memories.

    PubMed

    Bao, Xiao-Hui; Xu, Xiao-Fan; Li, Che-Ming; Yuan, Zhen-Sheng; Lu, Chao-Yang; Pan, Jian-Wei

    2012-12-11

    Quantum teleportation and quantum memory are two crucial elements for large-scale quantum networks. With the help of prior distributed entanglement as a "quantum channel," quantum teleportation provides an intriguing means to faithfully transfer quantum states among distant locations without actual transmission of the physical carriers [Bennett CH, et al. (1993) Phys Rev Lett 70(13):1895-1899]. Quantum memory enables controlled storage and retrieval of fast-flying photonic quantum bits with stationary matter systems, which is essential to achieve the scalability required for large-scale quantum networks. Combining these two capabilities, here we realize quantum teleportation between two remote atomic-ensemble quantum memory nodes, each composed of ∼10(8) rubidium atoms and connected by a 150-m optical fiber. The spin wave state of one atomic ensemble is mapped to a propagating photon and subjected to Bell state measurements with another single photon that is entangled with the spin wave state of the other ensemble. Two-photon detection events herald the success of teleportation with an average fidelity of 88(7)%. Besides its fundamental interest as a teleportation between two remote macroscopic objects, our technique may be useful for quantum information transfer between different nodes in quantum networks and distributed quantum computing. PMID:23144222

  13. Remote access for NAS: Supercomputing in a university environment

    NASA Technical Reports Server (NTRS)

    Johnson, G.; Olson, B.; Swisshelm, J.; Pryor, D.; Ziebarth, J.

    1986-01-01

    The experiment was designed to assist the Numerical Aerodynamic Simulation (NAS) Project Office in the testing and evaluation of long haul communications for remote users. The objectives of this work were to: (1) use foreign workstations to remotely access the NAS system; (2) provide NAS with a link to a large university-based computing facility which can serve as a model for a regional node of the Long-Haul Communications Subsystem (LHCS); and (3) provide a tail circuit to the University of Colorado a Boulder thereby simulating the complete communications path from NAS through a regional node to an end-user.

  14. A Cerebellar-model Associative Memory as a Generalized Random-access Memory

    NASA Technical Reports Server (NTRS)

    Kanerva, Pentti

    1989-01-01

    A versatile neural-net model is explained in terms familiar to computer scientists and engineers. It is called the sparse distributed memory, and it is a random-access memory for very long words (for patterns with thousands of bits). Its potential utility is the result of several factors: (1) a large pattern representing an object or a scene or a moment can encode a large amount of information about what it represents; (2) this information can serve as an address to the memory, and it can also serve as data; (3) the memory is noise tolerant--the information need not be exact; (4) the memory can be made arbitrarily large and hence an arbitrary amount of information can be stored in it; and (5) the architecture is inherently parallel, allowing large memories to be fast. Such memories can become important components of future computers.

  15. Enabling Remote Access to Fieldwork: Gaining Insight into the Pedagogic Effectiveness of "Direct" and "Remote" Field Activities

    ERIC Educational Resources Information Center

    Stokes, Alison; Collins, Trevor; Maskall, John; Lea, John; Lunt, Paul; Davies, Sarah

    2012-01-01

    This study considers the pedagogical effectiveness of remote access to fieldwork locations. Forty-one students from across the GEES disciplines (geography, earth and environmental sciences) undertook a fieldwork exercise, supported by two lecturers. Twenty students accessed the field site directly and the remainder accessed the site remotely using…

  16. 75 FR 14467 - In the Matter of: Certain Dynamic Random Access Memory Semiconductors and Products Containing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-25

    ... COMMISSION In the Matter of: Certain Dynamic Random Access Memory Semiconductors and Products Containing Same... random access memory semiconductors and products containing same, including memory modules, by reason of... after importation of certain dynamic random access memory semiconductors or products containing the...

  17. Effects of Sleep Deprivation and Aging on Long-Term and Remote Memory in Mice

    ERIC Educational Resources Information Center

    Vecsey, Christopher G.; Park, Alan J.; Khatib, Nora; Abel, Ted

    2015-01-01

    Sleep deprivation (SD) following hippocampus-dependent learning in young mice impairs memory when tested the following day. Here, we examined the effects of SD on remote memory in both young and aged mice. In young mice, we found that memory is still impaired 1 mo after training. SD also impaired memory in aged mice 1 d after training, but, by a…

  18. Secure Remote Access Issues in a Control Center Environment

    NASA Technical Reports Server (NTRS)

    Pitts, Lee; McNair, Ann R. (Technical Monitor)

    2002-01-01

    The ISS finally reached an operational state and exists for local and remote users. Onboard payload systems are managed by the Huntsville Operations Support Center (HOSC). Users access HOSC systems by internet protocols in support of daily operations, preflight simulation, and test. In support of this diverse user community, a modem security architecture has been implemented. The architecture has evolved over time from an isolated but open system to a system which supports local and remote access to the ISS over broad geographic regions. This has been accomplished through the use of an evolved security strategy, PKI, and custom design. Through this paper, descriptions of the migration process and the lessons learned are presented. This will include product decision criteria, rationale, and the use of commodity products in the end architecture. This paper will also stress the need for interoperability of various products and the effects of seemingly insignificant details.

  19. Direct memory access transfer completion notification

    DOEpatents

    Archer, Charles J.; Blocksome, Michael A.; Parker, Jeffrey J.

    2011-02-15

    DMA transfer completion notification includes: inserting, by an origin DMA engine on an origin node in an injection first-in-first-out (`FIFO`) buffer, a data descriptor for an application message to be transferred to a target node on behalf of an application on the origin node; inserting, by the origin DMA engine, a completion notification descriptor in the injection FIFO buffer after the data descriptor for the message, the completion notification descriptor specifying a packet header for a completion notification packet; transferring, by the origin DMA engine to the target node, the message in dependence upon the data descriptor; sending, by the origin DMA engine, the completion notification packet to a local reception FIFO buffer using a local memory FIFO transfer operation; and notifying, by the origin DMA engine, the application that transfer of the message is complete in response to receiving the completion notification packet in the local reception FIFO buffer.

  20. Magnetic Random Access Memory (MRAM) Device Development

    SciTech Connect

    Cerjan, C; Law, B P

    2000-01-18

    The recent discovery of materials that have anomalous magneto-resistive properties has generated renewed commercial interest in metal-based fast memory storage as an alternative to the currently used semiconductor-based devices. One particularly promising ternary alloy, fabricated at LLNL, appeared to have exceptional field response. This proposal extended the investigation of this class of materials by examining the scaling properties of test structures made from this material that could definitively verify the preliminary observations of high field sensitivity. Although the expected scaling was observed, technical issues, such as excessive oxidation, prevented a definitive assessment of the effect. Despite the difficulties encountered, several test structures demonstrated superior performance in a ''spin-valve'' configuration that might have applications for very high density recording heads.

  1. Direct memory access transfer completion notification

    DOEpatents

    Archer, Charles J. , Blocksome; Michael A. , Parker; Jeffrey J.

    2011-02-15

    Methods, systems, and products are disclosed for DMA transfer completion notification that include: inserting, by an origin DMA on an origin node in an origin injection FIFO, a data descriptor for an application message; inserting, by the origin DMA, a reflection descriptor in the origin injection FIFO, the reflection descriptor specifying a remote get operation for injecting a completion notification descriptor in a reflection injection FIFO on a reflection node; transferring, by the origin DMA to a target node, the message in dependence upon the data descriptor; in response to completing the message transfer, transferring, by the origin DMA to the reflection node, the completion notification descriptor in dependence upon the reflection descriptor; receiving, by the origin DMA from the reflection node, a completion packet; and notifying, by the origin DMA in response to receiving the completion packet, the origin node's processing core that the message transfer is complete.

  2. Access Analysis-Based Tight Localization of Abstract Memories

    NASA Astrophysics Data System (ADS)

    Oh, Hakjoo; Brutschy, Lucas; Yi, Kwangkeun

    On-the-fly localization of abstract memory states is vital for economical abstract interpretation of imperative programs. Such localization is sometimes called "abstract garbage collection" or "framing". In this article we present a new memory localization technique that is more effective than the conventional reachability-based approach. Our technique is based on a key observation that collecting the reachable memory parts is too conservative and the accessed parts are usually tiny subsets of the reachable. Our technique first estimates, by an efficient pre-analysis, the set of locations that will be accessed during the analysis of each code block. Then the main analysis uses the access-set results to trim the memory entries before analyzing code blocks. In experiments with an industrial-strength global C static analyzer, the technique is applied right before analyzing each procedure's body and reduces the average analysis time and memory by 92.1% and 71.2%, respectively, without sacrificing the analysis precision. Localizing more frequently such as at loop bodies and basic blocks as well as procedure bodies, the generalized localization additionally reduces analysis time by an average of 31.8%.

  3. Remoteness modulates the effects of emotional valence on the neural network of autobiographical memory in older females.

    PubMed

    Gong, Xianmin; Fu, Yan; Wang, Dahua; Franz, Elizabeth; Long, Zhiying

    2014-01-01

    To better understand the effects of emotional valence on autobiographical memory (AM), the present study compared behavioral performance and neural activation in positive and negative AMs at different levels of remoteness (the time-interval between encoding and retrieving) in a sample of Chinese older females. The behavioral results revealed that older females held a positivity bias in emotional AM in the form of an obvious trend of higher level of vividness when retrieving positive AMs compared with negative AMs. At the neural level, a de-lateralized neural network, covering the core AM system and the affect processing system, was found to be associated with emotional AM. Within the network, increased activation of a prefrontal cortex/anterior cingulate cortex (PFC/ACC) control system was found when processing negative recent AMs compared with positive recent AMs; increased activation of the somatosensory area was found with positive remote AMs compared with negative remote AMs. On the basis of these results, we suggest that the positivity bias of the older adults in recent AMs may be due to the use of an emotion regulation or control system (involving PFC/ACC) against negative AMs; in contrast, for remote AMs, the positivity bias may be due to better access to the positive remote memory details than the negative remote memory details. PMID:25486718

  4. Remoteness modulates the effects of emotional valence on the neural network of autobiographical memory in older females.

    PubMed

    Gong, Xianmin; Fu, Yan; Wang, Dahua; Franz, Elizabeth; Long, Zhiying

    2014-01-01

    To better understand the effects of emotional valence on autobiographical memory (AM), the present study compared behavioral performance and neural activation in positive and negative AMs at different levels of remoteness (the time-interval between encoding and retrieving) in a sample of Chinese older females. The behavioral results revealed that older females held a positivity bias in emotional AM in the form of an obvious trend of higher level of vividness when retrieving positive AMs compared with negative AMs. At the neural level, a de-lateralized neural network, covering the core AM system and the affect processing system, was found to be associated with emotional AM. Within the network, increased activation of a prefrontal cortex/anterior cingulate cortex (PFC/ACC) control system was found when processing negative recent AMs compared with positive recent AMs; increased activation of the somatosensory area was found with positive remote AMs compared with negative remote AMs. On the basis of these results, we suggest that the positivity bias of the older adults in recent AMs may be due to the use of an emotion regulation or control system (involving PFC/ACC) against negative AMs; in contrast, for remote AMs, the positivity bias may be due to better access to the positive remote memory details than the negative remote memory details. PMID:25508849

  5. Quantifying Locality in the Memory Access Patterns of HPCApplications

    SciTech Connect

    Weinberg, Jonathan; Snavely, Allan; McCracken, Michael O.; Strohmaier, Erich

    2005-07-25

    Several benchmarks for measuring memory performance of HPC systems along dimensions of spatial and temporal memory locality have recently been proposed. However, little is understood about the relationships of these benchmarks to real applications and to each other. In this paper, we propose a methodology for producing architecture-neutral characterizations of the spatial and temporal locality exhibited by the memory access patterns of applications. We demonstrate that the results track intuitive notions of spatial and temporal locality on several synthetic and application benchmarks. We employ the methodology to analyze the memory performance components of the HPC Challenge Benchmarks, the Apex-MAP benchmark, and their relationships to each other and other benchmarks and applications. We show that this analysis can be used to both increase understanding of the benchmarks and enhance their usefulness by mapping them, along with applications, to a 2-D space along axes of spatial and temporal locality.

  6. Real-time Data Access From Remote Observatories

    NASA Astrophysics Data System (ADS)

    Detrick, D. L.; Lutz, L. F.; Etter, J. E.; Rosenberg, T. J.; Weatherwax, A. T.

    2006-12-01

    Real-time access to solar-terrestrial data is becoming increasingly important, not only because it is now possible to acquire and access data rapidly via the internet, but also because of the need for timely publication of real-time data for analysis and modeling efforts. Currently, engineering-scaled summary data are available routinely on a daily basis from many observatories, but only when the observatories have continuous, or at least daily network access. Increasingly, the upgrading of remote data acquisition hardware makes it possible to provide data in real-time, and it is becoming normal to expect timely access to data products. The NSF- supported PENGUIn/AGO constellation of autonomous Antarctic research observatories has provided real-time data since December, 2002, when Iridium satellite modems were installed at three sites. The Iridium telecommunications links are maintained continuously, transferring data between the remote observatories and a U.S.-based data acquisition site. The time-limiting factor with this scenario is now the delay in completing a data record before transmission, which can be as short as minutes depending on the sampling rate. The single-channel data throughput of the current systems is 20-MB/day (megabytes per day), but planned installations will be capable of operating with multiple modem channels. The data records are currently posted immediately to a web site accessible by anonymous FTP client software, for use by the instruments' principal investigators, and survey plots of selected signals are published daily. The web publication facilities are being upgraded, in order to allow other interested researchers rapid access to engineering-scaled data products, in several common formats, as well as providing interactive plotting capabilities. The web site will provide access to data from other collaborating observatories (including South Pole and McMurdo Stations), as well as ancillary data accessible from public sites (e.g., Kp

  7. Kokkos: Enabling manycore performance portability through polymorphic memory access patterns

    SciTech Connect

    Carter Edwards, H.; Trott, Christian R.; Sunderland, Daniel

    2014-07-22

    The manycore revolution can be characterized by increasing thread counts, decreasing memory per thread, and diversity of continually evolving manycore architectures. High performance computing (HPC) applications and libraries must exploit increasingly finer levels of parallelism within their codes to sustain scalability on these devices. We found that a major obstacle to performance portability is the diverse and conflicting set of constraints on memory access patterns across devices. Contemporary portable programming models address manycore parallelism (e.g., OpenMP, OpenACC, OpenCL) but fail to address memory access patterns. The Kokkos C++ library enables applications and domain libraries to achieve performance portability on diverse manycore architectures by unifying abstractions for both fine-grain data parallelism and memory access patterns. In this paper we describe Kokkos’ abstractions, summarize its application programmer interface (API), present performance results for unit-test kernels and mini-applications, and outline an incremental strategy for migrating legacy C++ codes to Kokkos. Furthermore, the Kokkos library is under active research and development to incorporate capabilities from new generations of manycore architectures, and to address a growing list of applications and domain libraries.

  8. Kokkos: Enabling manycore performance portability through polymorphic memory access patterns

    DOE PAGESBeta

    Carter Edwards, H.; Trott, Christian R.; Sunderland, Daniel

    2014-07-22

    The manycore revolution can be characterized by increasing thread counts, decreasing memory per thread, and diversity of continually evolving manycore architectures. High performance computing (HPC) applications and libraries must exploit increasingly finer levels of parallelism within their codes to sustain scalability on these devices. We found that a major obstacle to performance portability is the diverse and conflicting set of constraints on memory access patterns across devices. Contemporary portable programming models address manycore parallelism (e.g., OpenMP, OpenACC, OpenCL) but fail to address memory access patterns. The Kokkos C++ library enables applications and domain libraries to achieve performance portability on diversemore » manycore architectures by unifying abstractions for both fine-grain data parallelism and memory access patterns. In this paper we describe Kokkos’ abstractions, summarize its application programmer interface (API), present performance results for unit-test kernels and mini-applications, and outline an incremental strategy for migrating legacy C++ codes to Kokkos. Furthermore, the Kokkos library is under active research and development to incorporate capabilities from new generations of manycore architectures, and to address a growing list of applications and domain libraries.« less

  9. Resistive random access memory utilizing ferritin protein with Pt nanoparticles

    NASA Astrophysics Data System (ADS)

    Uenuma, Mutsunori; Kawano, Kentaro; Zheng, Bin; Okamoto, Naofumi; Horita, Masahiro; Yoshii, Shigeo; Yamashita, Ichiro; Uraoka, Yukiharu

    2011-05-01

    This study reports controlled single conductive paths found in resistive random access memory (ReRAM) formed by embedding Pt nanoparticles (Pt NPs) in NiO film. Homogeneous Pt NPs produced and placed by ferritin protein produce electric field convergence which leads to controlled conductive path formation. The ReRAM with Pt NPs shows stable switching behavior. A Pt NP density decrease results in an increase of OFF state resistance and decrease of forming voltage, whereas ON resistance was independent of the Pt NP density, which indicates that a single metal NP in a memory cell will achieve low power and stable operation.

  10. Integrated, nonvolatile, high-speed analog random access memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R. (Inventor); Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor)

    1994-01-01

    This invention provides an integrated, non-volatile, high-speed random access memory. A magnetically switchable ferromagnetic or ferrimagnetic layer is sandwiched between an electrical conductor which provides the ability to magnetize the magnetically switchable layer and a magneto resistive or Hall effect material which allows sensing the magnetic field which emanates from the magnetization of the magnetically switchable layer. By using this integrated three-layer form, the writing process, which is controlled by the conductor, is separated from the storage medium in the magnetic layer and from the readback process which is controlled by the magnetoresistive layer. A circuit for implementing the memory in CMOS or the like is disclosed.

  11. Magnet/Hall-Effect Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan; Stadler, Henry L.; Katti, Romney R.

    1991-01-01

    In proposed magnet/Hall-effect random-access memory (MHRAM), bits of data stored magnetically in Perm-alloy (or equivalent)-film memory elements and read out by using Hall-effect sensors to detect magnetization. Value of each bit represented by polarity of magnetization. Retains data for indefinite time or until data rewritten. Speed of Hall-effect sensors in MHRAM results in readout times of about 100 nanoseconds. Other characteristics include high immunity to ionizing radiation and storage densities of order 10(Sup6)bits/cm(Sup 2) or more.

  12. Paging memory from random access memory to backing storage in a parallel computer

    DOEpatents

    Archer, Charles J; Blocksome, Michael A; Inglett, Todd A; Ratterman, Joseph D; Smith, Brian E

    2013-05-21

    Paging memory from random access memory (`RAM`) to backing storage in a parallel computer that includes a plurality of compute nodes, including: executing a data processing application on a virtual machine operating system in a virtual machine on a first compute node; providing, by a second compute node, backing storage for the contents of RAM on the first compute node; and swapping, by the virtual machine operating system in the virtual machine on the first compute node, a page of memory from RAM on the first compute node to the backing storage on the second compute node.

  13. Establishing a Secure Data Center with Remote Access: Preprint

    SciTech Connect

    Gonder, J.; Burton, E.; Murakami, E.

    2012-04-01

    Access to existing travel data is critical for many analysis efforts that lack the time or resources to support detailed data collection. High-resolution data sets provide particular value, but also present a challenge for preserving the anonymity of the original survey participants. To address this dilemma of providing data access while preserving privacy, the National Renewable Energy Laboratory and the U.S. Department of Transportation have launched the Transportation Secure Data Center (TSDC). TSDC data sets include those from regional travel surveys and studies that increasingly use global positioning system devices. Data provided by different collecting agencies varies with respect to formatting, elements included and level of processing conducted in support of the original purpose. The TSDC relies on a number of geospatial and other analysis tools to ensure data quality and to generate useful information outputs. TSDC users can access the processed data in two different ways. The first is by downloading summary results and second-by-second vehicle speed profiles (with latitude/longitude information removed) from a publicly-accessible website. The second method involves applying for a remote connection account to a controlled-access environment where spatial analysis can be conducted, but raw data cannot be removed.

  14. Effects of sleep deprivation and aging on long-term and remote memory in mice

    PubMed Central

    Vecsey, Christopher G.; Park, Alan J.; Khatib, Nora

    2015-01-01

    Sleep deprivation (SD) following hippocampus-dependent learning in young mice impairs memory when tested the following day. Here, we examined the effects of SD on remote memory in both young and aged mice. In young mice, we found that memory is still impaired 1 mo after training. SD also impaired memory in aged mice 1 d after training, but, by a month after training, sleep-deprived and control aged animals performed similarly, primarily due to remote memory decay in the control aged animals. Gene expression analysis supported the finding that SD has similar effects on the hippocampus in young and aged mice. PMID:25776037

  15. 76 FR 73676 - Certain Dynamic Random Access Memory Devices, and Products Containing Same; Receipt of Complaint...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-29

    ... COMMISSION Certain Dynamic Random Access Memory Devices, and Products Containing Same; Receipt of Complaint... complaint entitled In Re Certain Dynamic Random Access Memory Devices, and Products Containing Same, DN 2859... within the United States after importation of certain dynamic random access memory devices, and...

  16. 76 FR 80964 - Certain Dynamic Random Access Memory Devices, and Products Containing Same; Institution of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ... COMMISSION Certain Dynamic Random Access Memory Devices, and Products Containing Same; Institution of... States after importation of certain dynamic random access memory devices, and products containing same by... dynamic random access memory devices, and products containing same that infringe one or more of claims...

  17. Remote Access to Wireless Communications Systems Laboratory--New Technology Approach

    ERIC Educational Resources Information Center

    Kafadarova, Nadezhda; Sotirov, Sotir; Milev, Mihail

    2012-01-01

    Technology nowadays enables the remote access to laboratory equipment and instruments via Internet. This is especially useful in engineering education, where students can conduct laboratory experiment remotely. Such remote laboratory access can enable students to use expensive laboratory equipment, which is not usually available to students. In…

  18. Method and device for maximizing memory system bandwidth by accessing data in a dynamically determined order

    NASA Technical Reports Server (NTRS)

    Wulf, William A. (Inventor); McKee, Sally A. (Inventor); Klenke, Robert (Inventor); Schwab, Andrew J. (Inventor); Moyer, Stephen A. (Inventor); Aylor, James (Inventor); Hitchcock, Charles Young (Inventor)

    2000-01-01

    A data processing system is disclosed which comprises a data processor and memory control device for controlling the access of information from the memory. The memory control device includes temporary storage and decision ability for determining what order to execute the memory accesses. The compiler detects the requirements of the data processor and selects the data to stream to the memory control device which determines a memory access order. The order in which to access said information is selected based on the location of information stored in the memory. The information is repeatedly accessed from memory and stored in the temporary storage until all streamed information is accessed. The information is stored until required by the data processor. The selection of the order in which to access information maximizes bandwidth and decreases the retrieval time.

  19. Nonvolatile GaAs Random-Access Memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.; Stadler, Henry L.; Wu, Jiin-Chuan

    1994-01-01

    Proposed random-access integrated-circuit electronic memory offers nonvolatile magnetic storage. Bits stored magnetically and read out with Hall-effect sensors. Advantages include short reading and writing times and high degree of immunity to both single-event upsets and permanent damage by ionizing radiation. Use of same basic material for both transistors and sensors simplifies fabrication process, with consequent benefits in increased yield and reduced cost.

  20. If memory serves, will language? Later verbal accessibility of early memories.

    PubMed

    Bauer, P J; Kroupina, M G; Schwade, J A; Dropik, P L; Wewerka, S S

    1998-01-01

    Of major interest to those concerned with early mnemonic process and function is the question of whether early memories likely encoded without the benefit of language later are accessible to verbal report. In the context of a controlled laboratory study, we examined this question in children who were 16 and 20 months at the time of exposure to specific target events and who subsequently were tested for their memories of the events after a delay of either 6 or 12 months (at 22-32 months) and then again at 3 years. At the first delayed-recall test, children evidenced memory both nonverbally and verbally. Nonverbal mnemonic expression was related to age at the time of test; verbal mnemonic expression was related to verbal fluency at the time of test. At the second delayed-recall test, children evidenced continued accessibility of their early memories. Verbal mnemonic expression was related to previous mnemonic expression, both nonverbal and verbal, each of which contributed unique variance. The relevance of these findings on memory for controlled laboratory events for issues of memory for traumatic experiences is discussed. PMID:9886220

  1. Remotely Accessible Testbed for Software Defined Radio Development

    NASA Technical Reports Server (NTRS)

    Lux, James P.; Lang, Minh; Peters, Kenneth J.; Taylor, Gregory H.

    2012-01-01

    Previous development testbeds have assumed that the developer was physically present in front of the hardware being used. No provision for remote operation of basic functions (power on/off or reset) was made, because the developer/operator was sitting in front of the hardware, and could just push the button manually. In this innovation, a completely remotely accessible testbed has been created, with all diagnostic equipment and tools set up for remote access, and using standardized interfaces so that failed equipment can be quickly replaced. In this testbed, over 95% of the operating hours were used for testing without the developer being physically present. The testbed includes a pair of personal computers, one running Linux and one running Windows. A variety of peripherals is connected via Ethernet and USB (universal serial bus) interfaces. A private internal Ethernet is used to connect to test instruments and other devices, so that the sole connection to the outside world is via the two PCs. An important design consideration was that all of the instruments and interfaces used stable, long-lived industry standards, such as Ethernet, USB, and GPIB (general purpose interface bus). There are no plug-in cards for the two PCs, so there are no problems with finding replacement computers with matching interfaces, device drivers, and installation. The only thing unique to the two PCs is the locally developed software, which is not specific to computer or operating system version. If a device (including one of the computers) were to fail or become unavailable (e.g., a test instrument needed to be recalibrated), replacing it is a straightforward process with a standard, off-the-shelf device.

  2. Transient News Events Test: feasibility in assessment of post-temporal lobectomy remote memory deficits.

    PubMed

    Leeman, Beth A; Macklin, Eric A; Schomer, Donald L; O'Connor, Margaret G

    2009-09-01

    Although anterograde memory deficits are well documented in patients with epilepsy, the extent to which remote memory deficits occur is less clear. This is due in part to a lack of reliable methods for assessment. The present study examined the feasibility of using the Transient News Events Test (TNET) to assess remote memory in subjects status post anterior temporal lobectomy (ATL) for the treatment of refractory seizures. Results indicated significantly poorer performance of the patient group compared to healthy controls. The decrement in performance within the patient group was evident only for items from more recent time periods. Reasons for an apparent stability of the most remote memories with ATL and implications regarding hippocampal function are reviewed. In conclusion, the TNET provides a feasible method for assessment of remote memory function in patients with epilepsy, with decrements in performance noted in comparison to a healthy control group in this retrospective study. PMID:19643674

  3. Vortex-Core Reversal Dynamics: Towards Vortex Random Access Memory

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Koog

    2011-03-01

    An energy-efficient, ultrahigh-density, ultrafast, and nonvolatile solid-state universal memory is a long-held dream in the field of information-storage technology. The magnetic random access memory (MRAM) along with a spin-transfer-torque switching mechanism is a strong candidate-means of realizing that dream, given its nonvolatility, infinite endurance, and fast random access. Magnetic vortices in patterned soft magnetic dots promise ground-breaking applications in information-storage devices, owing to the very stable twofold ground states of either their upward or downward core magnetization orientation and plausible core switching by in-plane alternating magnetic fields or spin-polarized currents. However, two technologically most important but very challenging issues --- low-power recording and reliable selection of each memory cell with already existing cross-point architectures --- have not yet been resolved for the basic operations in information storage, that is, writing (recording) and readout. Here, we experimentally demonstrate a magnetic vortex random access memory (VRAM) in the basic cross-point architecture. This unique VRAM offers reliable cell selection and low-power-consumption control of switching of out-of-plane core magnetizations using specially designed rotating magnetic fields generated by two orthogonal and unipolar Gaussian-pulse currents along with optimized pulse width and time delay. Our achievement of a new device based on a new material, that is, a medium composed of patterned vortex-state disks, together with the new physics on ultrafast vortex-core switching dynamics, can stimulate further fruitful research on MRAMs that are based on vortex-state dot arrays.

  4. On the resilience of remote traumatic memories against exposure therapy-mediated attenuation.

    PubMed

    Tsai, Li-Huei; Gräff, Johannes

    2014-08-01

    How to attenuate traumatic memories has long been the focus of intensive research efforts, as traumatic memories are extremely persistent and heavily impinge on the quality of life. Despite the fact that traumatic memories are often not readily amenable to immediate intervention, surprisingly few studies have investigated treatment options for remote traumata in animal models. The few that have unanimously concluded that exposure therapy-based approaches, the most successful behavioral intervention for the attenuation of recent forms of traumata in humans, fail to effectively reduce remote fear memories. Here, we provide an overview of these animal studies with an emphasis on why remote traumatic memories might be refractory to behavioral interventions: A lack of neuroplasticity in brain areas relevant for learning and memory emerges as a common denominator of such resilience. We then outline the findings of a recent study in mice showing that by combining exposure therapy-like approaches with small molecule inhibitors of histone deacetylases (HDACis), even remote memories can be persistently attenuated. This pharmacological intervention reinstated neuroplasticity to levels comparable to those found upon successful attenuation of recent memories. Thus, HDACis-or any other agent capable of heightening neuroplasticity-in conjunction with exposure therapy-based treatments might constitute a promising approach to overcome remote traumata. PMID:25027989

  5. On the resilience of remote traumatic memories against exposure therapy-mediated attenuation

    PubMed Central

    Tsai, Li-Huei; Gräff, Johannes

    2014-01-01

    How to attenuate traumatic memories has long been the focus of intensive research efforts, as traumatic memories are extremely persistent and heavily impinge on the quality of life. Despite the fact that traumatic memories are often not readily amenable to immediate intervention, surprisingly few studies have investigated treatment options for remote traumata in animal models. The few that have unanimously concluded that exposure therapy-based approaches, the most successful behavioral intervention for the attenuation of recent forms of traumata in humans, fail to effectively reduce remote fear memories. Here, we provide an overview of these animal studies with an emphasis on why remote traumatic memories might be refractory to behavioral interventions: A lack of neuroplasticity in brain areas relevant for learning and memory emerges as a common denominator of such resilience. We then outline the findings of a recent study in mice showing that by combining exposure therapy-like approaches with small molecule inhibitors of histone deacetylases (HDACis), even remote memories can be persistently attenuated. This pharmacological intervention reinstated neuroplasticity to levels comparable to those found upon successful attenuation of recent memories. Thus, HDACis—or any other agent capable of heightening neuroplasticity—in conjunction with exposure therapy-based treatments might constitute a promising approach to overcome remote traumata. PMID:25027989

  6. Complex dynamics of semantic memory access in reading.

    PubMed

    Baggio, Giosué; Fonseca, André

    2012-02-01

    Understanding a word in context relies on a cascade of perceptual and conceptual processes, starting with modality-specific input decoding, and leading to the unification of the word's meaning into a discourse model. One critical cognitive event, turning a sensory stimulus into a meaningful linguistic sign, is the access of a semantic representation from memory. Little is known about the changes that activating a word's meaning brings about in cortical dynamics. We recorded the electroencephalogram (EEG) while participants read sentences that could contain a contextually unexpected word, such as 'cold' in 'In July it is very cold outside'. We reconstructed trajectories in phase space from single-trial EEG time series, and we applied three nonlinear measures of predictability and complexity to each side of the semantic access boundary, estimated as the onset time of the N400 effect evoked by critical words. Relative to controls, unexpected words were associated with larger prediction errors preceding the onset of the N400. Accessing the meaning of such words produced a phase transition to lower entropy states, in which cortical processing becomes more predictable and more regular. Our study sheds new light on the dynamics of information flow through interfaces between sensory and memory systems during language processing. PMID:21715401

  7. Brain region-specific activity patterns after recent or remote memory retrieval of auditory conditioned fear.

    PubMed

    Kwon, Jeong-Tae; Jhang, Jinho; Kim, Hyung-Su; Lee, Sujin; Han, Jin-Hee

    2012-01-01

    Memory is thought to be sparsely encoded throughout multiple brain regions forming unique memory trace. Although evidence has established that the amygdala is a key brain site for memory storage and retrieval of auditory conditioned fear memory, it remains elusive whether the auditory brain regions may be involved in fear memory storage or retrieval. To investigate this possibility, we systematically imaged the brain activity patterns in the lateral amygdala, MGm/PIN, and AuV/TeA using activity-dependent induction of immediate early gene zif268 after recent and remote memory retrieval of auditory conditioned fear. Consistent with the critical role of the amygdala in fear memory, the zif268 activity in the lateral amygdala was significantly increased after both recent and remote memory retrieval. Interesting, however, the density of zif268 (+) neurons in both MGm/PIN and AuV/TeA, particularly in layers IV and VI, was increased only after remote but not recent fear memory retrieval compared to control groups. Further analysis of zif268 signals in AuV/TeA revealed that conditioned tone induced stronger zif268 induction compared to familiar tone in each individual zif268 (+) neuron after recent memory retrieval. Taken together, our results support that the lateral amygdala is a key brain site for permanent fear memory storage and suggest that MGm/PIN and AuV/TeA might play a role for remote memory storage or retrieval of auditory conditioned fear, or, alternatively, that these auditory brain regions might have a different way of processing for familiar or conditioned tone information at recent and remote time phases. PMID:22993170

  8. Remote Semantic Memory for Public Figures in HIV Infection, Alcoholism, and their Comorbidity

    PubMed Central

    Fama, Rosemary; Rosenbloom, Margaret J.; Sassoon, Stephanie A.; Thompson, Megan A.; Pfefferbaum, Adolf; Sullivan, Edith V.

    2010-01-01

    Background Impairments in component processes of working and episodic memory mark both HIV infection and chronic alcoholism, with compounded deficits often observed in individuals comorbid for these conditions. Remote semantic memory processes, however, have only seldom been studied in these diagnostic groups. Examination of remote semantic memory could provide insight into the underlying processes associated with storage and retrieval of learned information over extended time periods while elucidating spared and impaired cognitive functions in these clinical groups. Methods We examined component processes of remote semantic memory in HIV infection and chronic alcoholism in 4 subject groups (HIV, ALC, HIV+ALC, and age matched healthy adults) using a modified version of the Presidents Test. Free recall, recognition, and sequencing of presidential candidates and election dates were assessed. In addition, component processes of working, episodic, and semantic memory were assessed with ancillary cognitive tests. Results The comorbid group (HIV+ALC) was significantly impaired on sequencing of remote semantic information compared with age matched healthy adults. Free recall of remote semantic information was also modestly impaired in the HIV+ALC group, but normal performance for recognition of this information was observed. Few differences were observed between the single diagnosis groups (HIV, ALC) and healthy adults, although examination of the component processes underlying remote semantic memory scores elicited differences between the HIV and ALC groups. Selective remote memory processes were related to lifetime alcohol consumption in the ALC group and to viral load and depression level in the HIV group. Hepatitis C diagnosis was associated with lower remote semantic memory scores in all three clinical groups. Education level did not account for group differences reported. Conclusions This study provides behavioral support for the existence of adverse effects

  9. Resistive random access memory enabled by carbon nanotube crossbar electrodes.

    PubMed

    Tsai, Cheng-Lin; Xiong, Feng; Pop, Eric; Shim, Moonsub

    2013-06-25

    We use single-walled carbon nanotube (CNT) crossbar electrodes to probe sub-5 nm memory domains of thin AlOx films. Both metallic and semiconducting CNTs effectively switch AlOx bits between memory states with high and low resistance. The low-resistance state scales linearly with CNT series resistance down to ∼10 MΩ, at which point the ON-state resistance of the AlOx filament becomes the limiting factor. Dependence of switching behavior on the number of cross-points suggests a single channel to dominate the overall characteristics in multi-crossbar devices. We demonstrate ON/OFF ratios up to 5 × 10(5) and programming currents of 1 to 100 nA with few-volt set/reset voltages. Remarkably low reset currents enable a switching power of 10-100 nW and estimated switching energy as low as 0.1-10 fJ per bit. These results are essential for understanding the ultimate scaling limits of resistive random access memory at single-nanometer bit dimensions. PMID:23705675

  10. Efficient Memory Access with NumPy Global Arrays using Local Memory Access

    SciTech Connect

    Daily, Jeffrey A.; Berghofer, Dan C.

    2013-08-03

    This paper discusses the work completed working with Global Arrays of data on distributed multi-computer systems and improving their performance. The tasks completed were done at Pacific Northwest National Laboratory in the Science Undergrad Laboratory Internship program in the summer of 2013 for the Data Intensive Computing Group in the Fundamental and Computational Sciences DIrectorate. This work was done on the Global Arrays Toolkit developed by this group. This toolkit is an interface for programmers to more easily create arrays of data on networks of computers. This is useful because scientific computation is often done on large amounts of data sometimes so large that individual computers cannot hold all of it. This data is held in array form and can best be processed on supercomputers which often consist of a network of individual computers doing their computation in parallel. One major challenge for this sort of programming is that operations on arrays on multiple computers is very complex and an interface is needed so that these arrays seem like they are on a single computer. This is what global arrays does. The work done here is to use more efficient operations on that data that requires less copying of data to be completed. This saves a lot of time because copying data on many different computers is time intensive. The way this challenge was solved is when data to be operated on with binary operations are on the same computer, they are not copied when they are accessed. When they are on separate computers, only one set is copied when accessed. This saves time because of less copying done although more data access operations were done.

  11. Putting a Medical Library Online: Phase III--Remote Access to CD-ROMs.

    ERIC Educational Resources Information Center

    Kittle, Paul

    1989-01-01

    Describes the implementation of a project that provides dial-up access to MEDLINE on remote optical data disk (CD-ROM) using software that enables callers to use programs like Wordstar, Lotus, and dBase. Highlights include networking CD-ROM databases, hardware considerations, advantages and disadvantages of remote access, and future plans. A…

  12. Protocols and Strategies for Optimizing Performance of Remote Memory Operations on Clusters

    SciTech Connect

    Nieplocha, Jaroslaw; Tipparaju, Vinod; Saify, Amina; Panda, Dhabaleswar

    2002-04-15

    The paper describes software architecture for supporting remote memory operations on clusters equipped with high-performance networks such as Myrinet and Giganet/Emulex cLAN. It presents protocols and strategies that bridge the gap between user-level API requirements and low-level network-specific interfaces such as GM and VIA. In particular, the issues of memory registration, management of network resources and memory consumption on the host, are discussed and solved to achieve an efficient implementation.

  13. Optimizing Synchronization Operations for Remote Memory Communication Systems

    SciTech Connect

    Buntinas, Darius; Saify, Amina; Panda, Dhabaleswar K.; Nieplocha, Jarek; Bob Werner

    2003-04-22

    Synchronization operations, such as fence and locking, are used in many parallel operations accessing shared memory. However, a process which is blocked waiting for a fence operation to complete, or for a lock to be acquired, cannot perform useful computation. It is therefore critical that these operations be implemented as efficiently as possible to reduce the time a process waits idle. These operations also impact the scalability of the overall system. As system sizes get larger, the number of processes potentially requesting a lock increases. In this paper we describe the design and implementation of an optimized operation which combines a global fence operation and a barrier synchronization operation. We also describe our implementation of an optimized lock algorithm. The optimizations have been incorporated into the ARMCI communication library. The global fence and barrier operation gives a factor of improvement of up to 9 over the current implementation in a 16 node system, while the optimized lock implementation gives up to 1.25 factor of improvement. These optimizations allow for more efficient and scalable applications

  14. Becoming a better person: temporal remoteness biases autobiographical memories for moral events

    PubMed Central

    Escobedo, Jessica R.; Adolphs, Ralph

    2010-01-01

    Our autobiographical self depends on the differential recollection of our personal past, notably including memories of morally laden events. While both emotion and temporal recency are well known to influence memory, very little is known about how we remember moral events, and in particular about the distribution in time of memories for events that were blameworthy or praiseworthy. To investigate this issue in detail, we collected a novel database of 758 confidential, autobiographical narratives for personal moral events from 100 well-characterized healthy adults. Negatively valenced moral memories were significantly more remote than positively valenced memories, both as measured by the valence of the cue word that evoked the memory as well as by the content of the memory itself. The effect was independent of chronological age, ethnicity, gender, or personality, arguing for a general emotional bias in how we construct our moral autobiography. PMID:20677868

  15. Spin-Hall-assisted magnetic random access memory

    SciTech Connect

    Brink, A. van den Swagten, H. J. M.; Koopmans, B.; Cosemans, S.; Manfrini, M.; Van Roy, W.; Min, T.; Cornelissen, S.; Vaysset, A.; Departement elektrotechniek , KU Leuven, Kasteelpark Arenberg 10, B-3001 Heverlee

    2014-01-06

    We propose a write scheme for perpendicular spin-transfer torque magnetoresistive random-access memory that significantly reduces the required tunnel current density and write energy. A sub-nanosecond in-plane polarized spin current pulse is generated using the spin-Hall effect, disturbing the stable magnetic state. Subsequent switching using out-of-plane polarized spin current becomes highly efficient. Through evaluation of the Landau-Lifshitz-Gilbert equation, we quantitatively assess the viability of this write scheme for a wide range of system parameters. A typical example shows an eight-fold reduction in tunnel current density, corresponding to a fifty-fold reduction in write energy, while maintaining a 1 ns write time.

  16. Materials selection for oxide-based resistive random access memories

    SciTech Connect

    Guo, Yuzheng; Robertson, John

    2014-12-01

    The energies of atomic processes in resistive random access memories (RRAMs) are calculated for four typical oxides, HfO{sub 2}, TiO{sub 2}, Ta{sub 2}O{sub 5}, and Al{sub 2}O{sub 3}, to define a materials selection process. O vacancies have the lowest defect formation energy in the O-poor limit and dominate the processes. A band diagram defines the operating Fermi energy and O chemical potential range. It is shown how the scavenger metal can be used to vary the O vacancy formation energy, via controlling the O chemical potential, and the mean Fermi energy. The high endurance of Ta{sub 2}O{sub 5} RRAM is related to its more stable amorphous phase and the adaptive lattice rearrangements of its O vacancy.

  17. Complementary resistive switching behavior for conductive bridge random access memory

    NASA Astrophysics Data System (ADS)

    Zheng, Hao-Xuan; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Shih, Chih-Cheng; Zhang, Rui; Chen, Kai-Huang; Wang, Ming-Hui; Zheng, Jin-Cheng; Lo, Ikai; Wu, Cheng-Hsien; Tseng, Yi-Ting; Sze, Simon M.

    2016-06-01

    In this study, a structure of Pt/Cu18Si12O70/TiN has been investigated. By co-sputtering the Cu and SiO2 targets in the switching layer, we can measure the operation mechanism of complementary resistive switching (CRS). This differs from conventional conductive bridge random access memory (CBRAM) that tends to use Cu electrodes rather than Cu18Si12O70. By changing the voltage and compliance current, we can control device operating characteristics. Because Cu distributes differently in the device depending on this setting, the operating end can be located at either the top or bottom electrode. Device current–voltage (I–V) curves are used to demonstrate that the CRS in the CBRAM device is a double-electrode operation.

  18. Taxing Working Memory during Retrieval of Emotional Memories Does Not Reduce Memory Accessibility When Cued with Reminders

    PubMed Central

    van Schie, Kevin; Engelhard, Iris M.; van den Hout, Marcel A.

    2015-01-01

    Earlier studies have shown that when individuals recall an emotional memory while simultaneously doing a demanding dual-task [e.g., playing Tetris, mental arithmetic, making eye movements (EM)], this reduces self-reported vividness and emotionality of the memory. These effects have been found up to 1 week later, but have largely been confined to self-report ratings. This study examined whether this dual-tasking intervention reduces memory performance (i.e., accessibility of emotional memories). Undergraduates (N = 60) studied word-image pairs and rated the retrieved image on vividness and emotionality when cued with the word. Then they viewed the cues and recalled the images with or without making EM. Finally, they re-rated the images on vividness and emotionality. Additionally, fragments from images from all conditions were presented and participants identified which fragment was paired earlier with which cue. Findings showed no effect of the dual-task manipulation on self-reported ratings and latency responses. Several possible explanations for the lack of effects are discussed, but the cued recall procedure in our experiment seems to explain the absence of effects best. The study demonstrates boundaries to the effects of the “dual-tasking” procedure. PMID:25729370

  19. Dissociation of the Role of Infralimbic Cortex in Learning and Consolidation of Extinction of Recent and Remote Aversion Memory.

    PubMed

    Awad, Walaa; Ferreira, Guillaume; Maroun, Mouna

    2015-10-01

    Medial prefrontal circuits have been reported to undergo a major reorganization over time and gradually take a more important role for remote emotional memories such as contextual fear memory or food aversion memory. The medial prefrontal cortex, and specifically its ventral subregion, the infralimbic cortex (IL), was also reported to be critical for recent memory extinction of contextual fear conditioning and conditioned odor aversion. However, its exact role in the extinction of remotely acquired information is still not clear. Using postretrieval blockade of protein synthesis or inactivation of the IL, we showed that the IL is similarly required for extinction consolidation of recent and remote fear memory. However, in odor aversion memory, the IL was only involved in extinction consolidation of recent, but not remote, memory. In contrast, only remote retrieval of aversion memory induced c-Fos activation in the IL and preretrieval inactivation of the IL with lidocaine impaired subsequent extinction of remote but not recent memory, indicating IL is necessary for extinction learning of remote aversion memory. In contrast to the effects in odor aversion, our data show that the involvement of the IL in the consolidation of fear extinction does not depend on the memory age. More importantly, our data indicate that the IL is implicated in the extinction of fear and nonfear-based associations and suggest dissociation in the engagement of the IL in the learning and consolidation of food aversion extinction over time. PMID:25872918

  20. Accessibility versus Accuracy in Retrieving Spatial Memory: Evidence for Suboptimal Assumed Headings

    ERIC Educational Resources Information Center

    Yerramsetti, Ashok; Marchette, Steven A.; Shelton, Amy L.

    2013-01-01

    Orientation dependence in spatial memory has often been interpreted in terms of accessibility: Object locations are encoded relative to a reference orientation that affords the most accurate access to spatial memory. An open question, however, is whether people naturally use this "preferred" orientation whenever recalling the space. We…

  1. 75 FR 44989 - In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-30

    ... December 10, 2008, based on a complaint filed by Rambus, Inc. of Los Altos, California (``Rambus''). 73 FR... COMMISSION In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory... chips having synchronous dynamic random access memory controllers and product containing the same...

  2. The Cost of Accessing an Object's Feature Stored in Visual Working Memory

    PubMed Central

    Woodman, Geoffrey F.; Vecera, Shaun P.

    2010-01-01

    The effects of accessing or retrieving information held in working memory are poorly understood compared to what we know about the nature of information storage in this limited-capacity memory system. Previous studies of object-based attention have often relied upon memory-demanding tasks, and this work could indicate that accessing a piece of information in visual working memory may have deleterious effects upon the other representations being maintained. In the present study, we tested the hypothesis that accessing a feature of an object represented in visual working memory degrades the representations of the other stored objects’ features. Our findings support this hypothesis and point to important new questions about the nature of effects resulting from accessing information stored in visual working memory. PMID:21221413

  3. Brain structural, functional, and cognitive correlates of recent versus remote autobiographical memories in amnestic Mild Cognitive Impairment

    PubMed Central

    Tomadesso, Clémence; Perrotin, Audrey; Mutlu, Justine; Mézenge, Florence; Landeau, Brigitte; Egret, Stéphanie; de la Sayette, Vincent; Jonin, Pierre-Yves; Eustache, Francis; Desgranges, Béatrice; Chételat, Gaël

    2015-01-01

    Deficits in autobiographical memory appear earlier for recent than for remote life periods over the course of Alzheimer's disease (AD). The present study aims to further our understanding of this graded effect by investigating the cognitive and neural substrates of recent versus remote autobiographical memories in patients with amnestic Mild Cognitive Impairment (aMCI) thanks to an autobiographical fluency task. 20 aMCI patients and 25 Healthy elderly Controls (HC) underwent neuropsychological tests assessing remote (20-to-30 years old) and recent (the ten last years) autobiographical memory as well as episodic and semantic memory, executive function and global cognition. All patients also had a structural MRI and an FDG-PET scan. Correlations were assessed between each autobiographical memory score and the other tests as well as grey matter volume and metabolism. Within the aMCI, performances for the remote period correlated with personal semantic memory and episodic memory retrieval whereas performances for the recent period only correlated with episodic memory retrieval. Neuroimaging analyses revealed significant correlations between performances for the remote period and temporal pole and temporo-parietal cortex volumes and anterior cingulate gyrus metabolism, while performances for the recent period correlated with hippocampal volume and posterior cingulate, medial prefrontal and hippocampus metabolism. The brain regions related with the retrieval of events from the recent period showed greater atrophy/hypometabolism in aMCI patients compared to HC than those involved in remote memories. Recall of recent memories essentially relies on episodic memory processes and brain network while remote memories also involve other processes such as semantic memory. This is consistent with the semanticization of memories with time and may explain the better resistance of remote memory in AD. PMID:26106572

  4. Working memory capacity and retrieval limitations from long-term memory: an examination of differences in accessibility.

    PubMed

    Unsworth, Nash; Spillers, Gregory J; Brewer, Gene A

    2012-01-01

    In two experiments, the locus of individual differences in working memory capacity and long-term memory recall was examined. Participants performed categorical cued and free recall tasks, and individual differences in the dynamics of recall were interpreted in terms of a hierarchical-search framework. The results from this study are in accordance with recent theorizing suggesting a strong relation between working memory capacity and retrieval from long-term memory. Furthermore, the results also indicate that individual differences in categorical recall are partially due to differences in accessibility. In terms of accessibility of target information, two important factors drive the difference between high- and low-working-memory-capacity participants. Low-working-memory-capacity participants fail to utilize appropriate retrieval strategies to access cues, and they also have difficulty resolving cue overload. Thus, when low-working-memory-capacity participants were given specific cues that activated a smaller set of potential targets, their recall performance was the same as that of high-working-memory-capacity participants. PMID:22800472

  5. Remote Dial-In Patron Access to CD-ROM LANs.

    ERIC Educational Resources Information Center

    McQueen, Howard

    1990-01-01

    Examines technical and support issues that impact on libraries' decisions to provide patrons with remote communication access to CD-ROM local area networks. Areas discussed include licensing costs for CD-ROM, remote control communications software, dedicated hardware, system maintenance, computer security, and the provision of quality, user…

  6. Mapping virtual addresses to different physical addresses for value disambiguation for thread memory access requests

    DOEpatents

    Gala, Alan; Ohmacht, Martin

    2014-09-02

    A multiprocessor system includes nodes. Each node includes a data path that includes a core, a TLB, and a first level cache implementing disambiguation. The system also includes at least one second level cache and a main memory. For thread memory access requests, the core uses an address associated with an instruction format of the core. The first level cache uses an address format related to the size of the main memory plus an offset corresponding to hardware thread meta data. The second level cache uses a physical main memory address plus software thread meta data to store the memory access request. The second level cache accesses the main memory using the physical address with neither the offset nor the thread meta data after resolving speculation. In short, this system includes mapping of a virtual address to a different physical addresses for value disambiguation for different threads.

  7. Viable chemical approach for patterning nanoscale magnetoresistive random access memory

    SciTech Connect

    Kim, Taeseung; Kim, Younghee; Chen, Jack Kun-Chieh; Chang, Jane P.

    2015-03-15

    A reactive ion etching process with alternating Cl{sub 2} and H{sub 2} exposures has been shown to chemically etch CoFe film that is an integral component in magnetoresistive random access memory (MRAM). Starting with systematic thermodynamic calculations assessing various chemistries and reaction pathways leading to the highest possible vapor pressure of the etch products reactions, the potential chemical combinations were verified by etch rate investigation and surface chemistry analysis in plasma treated CoFe films. An ∼20% enhancement in etch rate was observed with the alternating use of Cl{sub 2} and H{sub 2} plasmas, in comparison with the use of only Cl{sub 2} plasma. This chemical combination was effective in removing metal chloride layers, thus maintaining the desired magnetic properties of the CoFe films. Scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy showed visually and spectroscopically that the metal chloride layers generated by Cl{sub 2} plasma were eliminated with H{sub 2} plasma to yield a clean etch profile. This work suggests that the selected chemistries can be used to etch magnetic metal alloys with a smooth etch profile and this general strategy can be applied to design chemically based etch processes to enable the fabrication of highly integrated nanoscale MRAM devices.

  8. Radiation dosimetry using three-dimensional optical random access memories

    NASA Technical Reports Server (NTRS)

    Moscovitch, M.; Phillips, G. W.

    2001-01-01

    Three-dimensional optical random access memories (3D ORAMs) are a new generation of high-density data storage devices. Binary information is stored and retrieved via a light induced reversible transformation of an ensemble of bistable photochromic molecules embedded in a polymer matrix. This paper describes the application of 3D ORAM materials to radiation dosimetry. It is shown both theoretically and experimentally, that ionizing radiation in the form of heavy charged particles is capable of changing the information originally stored on the ORAM material. The magnitude and spatial distribution of these changes are used as a measure of the absorbed dose, particle type and energy. The effects of exposure on 3D ORAM materials have been investigated for a variety of particle types and energies, including protons, alpha particles and 12C ions. The exposed materials are observed to fluoresce when exposed to laser light. The intensity and the depth of the fluorescence is dependent on the type and energy of the particle to which the materials were exposed. It is shown that these effects can be modeled using Monte Carlo calculations. The model provides a better understanding of the properties of these materials. which should prove useful for developing systems for charged particle and neutron dosimetry/detector applications. c2001 Published by Elsevier Science B.V.

  9. Performance Issues Related to Web Service Usage for Remote Data Access

    SciTech Connect

    Pais, V. F.; Stancalie, V.; Mihailescu, F. A.; Totolici, M. C.

    2008-04-07

    Web services are starting to be widely used in applications for remotely accessing data. This is of special interest for research based on small and medium scale fusion devices, since scientists participating remotely to experiments are accessing large amounts of data over the Internet. Recent tests were conducted to see how the new network traffic, generated by the use of web services, can be integrated in the existing infrastructure and what would be the impact over existing applications, especially those used in a remote participation scenario.

  10. Predicting fluctuations in widespread interest: memory decay and goal-related memory accessibility in internet search trends.

    PubMed

    Masicampo, E J; Ambady, Nalini

    2014-02-01

    Memory and interest respond in similar ways to people's shifting needs and motivations. We therefore tested whether memory and interest might produce similar, observable patterns in people's responses over time. Specifically, the present studies examined whether fluctuations in widespread interest (as measured by Internet search trends) resemble two well-established memory patterns: memory decay and goal-related memory accessibility. We examined national and international events (e.g., Nobel Prize selections, holidays) that produced spikes in widespread interest in certain people and foods. When the events that triggered widespread interest were incidental (e.g., the death of a celebrity), widespread interest conformed to memory decay patterns: It rose quickly, fell slowly according to a power function, and was higher after the event than before it. When the events that triggered widespread interest were goal related (e.g., political elections), widespread interest conformed to patterns of goal-related memory accessibility: It rose slowly, fell quickly according to a sigmoid function, and was lower after the event than before it. Fluctuations in widespread interest over time are thus similar to standard memory patterns observed at the individual level due perhaps to common mechanisms and functions. PMID:23127417

  11. Adult Age Differences in Accessing and Retrieving Information from Long-Term Memory.

    ERIC Educational Resources Information Center

    Petros, Thomas V.; And Others

    1983-01-01

    Investigated adult age differences in accessing and retrieving information from long-term memory. Results showed that older adults (N=26) were slower than younger adults (N=35) at feature extraction, lexical access, and accessing category information. The age deficit was proportionally greater when retrieval of category information was required.…

  12. Differential effects of dorsal hippocampal inactivation on expression of recent and remote drug and fear memory.

    PubMed

    Raybuck, J D; Lattal, K M

    2014-05-21

    Drugs of abuse generate strong drug-context associations, which can evoke powerful drug cravings that are linked to reinstatement in animal models and to relapse in humans. Work in learning and memory has demonstrated that contextual memories become more distributed over time, shifting from dependence on the hippocampus for retrieval to dependence on cortical structures. Implications for such changes in the structure of memory retrieval to addiction are unknown. Thus, to determine if the passage of time alters the substrates of conditioned place preference (CPP) memory retrieval, we investigated the effects of inactivation of the dorsal hippocampus (DH) with the GABA-A receptor agonist muscimol on expression of recent or remote CPP. We compared these effects with the same manipulation on expression of contextual fear conditioning. DH inactivation produced similar deficits in expression of both recent and remote CPP, but blocked expression of recent but not remote contextual fear memory. We describe the implications of these findings for mechanisms underlying long-term storage of contextual information. PMID:24686177

  13. Quantifying Access to Services in Remote and Rural Australia.

    ERIC Educational Resources Information Center

    Griffith, Dennis

    Each year commonwealth, state, and territory governments allocate millions of dollars to alleviate differing kinds of disadvantages among local communities in Australia. This paper is concerned with the allocation of resources to remote and rural areas by the Commonwealth Government on a national basis. Current formulas and resource allocation…

  14. Remote Student Access to Education via Satellite Delivery.

    ERIC Educational Resources Information Center

    Boylan, Colin; Wallace, Andrew; Richmond, Wayne

    2000-01-01

    In response to the expense and unreliability of radio and telephone communications, the New South Wales (Australia) Department of Education and Training undertook a trial of satellite technology to deliver interactive lessons to elementary students in remote areas. The Gilat satellite system developed in Israel is described, including equipment,…

  15. Healthcare Access and Health Beliefs of the Indigenous Peoples in Remote Amazonian Peru

    PubMed Central

    Brierley, Charlotte K.; Suarez, Nicolas; Arora, Gitanjli; Graham, Devon

    2014-01-01

    Little is published about the health issues of traditional communities in the remote Peruvian Amazon. This study assessed healthcare access, health perceptions, and beliefs of the indigenous population along the Ampiyacu and Yaguasyacu rivers in north-eastern Peru. One hundred and seventy-nine adult inhabitants of 10 remote settlements attending health clinics were interviewed during a medical services trip in April 2012. Demographics, health status, access to healthcare, health education, sanitation, alcohol use, and smoke exposure were recorded. Our findings indicate that poverty, household overcrowding, and poor sanitation remain commonplace in this group. Furthermore, there are poor levels of health education and on-going barriers to accessing healthcare. Healthcare access and health education remain poor in the remote Peruvian Amazon. This combined with poverty and its sequelae render this population vulnerable to disease. PMID:24277789

  16. Healthcare access and health beliefs of the indigenous peoples in remote Amazonian Peru.

    PubMed

    Brierley, Charlotte K; Suarez, Nicolas; Arora, Gitanjli; Graham, Devon

    2014-01-01

    Little is published about the health issues of traditional communities in the remote Peruvian Amazon. This study assessed healthcare access, health perceptions, and beliefs of the indigenous population along the Ampiyacu and Yaguasyacu rivers in north-eastern Peru. One hundred and seventy-nine adult inhabitants of 10 remote settlements attending health clinics were interviewed during a medical services trip in April 2012. Demographics, health status, access to healthcare, health education, sanitation, alcohol use, and smoke exposure were recorded. Our findings indicate that poverty, household overcrowding, and poor sanitation remain commonplace in this group. Furthermore, there are poor levels of health education and on-going barriers to accessing healthcare. Healthcare access and health education remain poor in the remote Peruvian Amazon. This combined with poverty and its sequelae render this population vulnerable to disease. PMID:24277789

  17. RAPID: A random access picture digitizer, display, and memory system

    NASA Technical Reports Server (NTRS)

    Yakimovsky, Y.; Rayfield, M.; Eskenazi, R.

    1976-01-01

    RAPID is a system capable of providing convenient digital analysis of video data in real-time. It has two modes of operation. The first allows for continuous digitization of an EIA RS-170 video signal. Each frame in the video signal is digitized and written in 1/30 of a second into RAPID's internal memory. The second mode leaves the content of the internal memory independent of the current input video. In both modes of operation the image contained in the memory is used to generate an EIA RS-170 composite video output signal representing the digitized image in the memory so that it can be displayed on a monitor.

  18. Proposal for Fermilab remote access via ISDN (Ver. 1.0)

    SciTech Connect

    Lidinsky, W.P.; Martin, D.E.

    1993-07-02

    Currently, most users at remote sites connect to the Fermilab network via dial-up over analog modems using a dumb terminal or a personal computer emulating a dumb terminal. This level of connectivity is suitable for accessing a single, character-based application. The power of personal computers that are becoming ubiquitous is under-utilized. National HEPnet Management (NHM) has been monitoring and experimenting with remote access via the integrated services digital network (ISDN) for over two years. Members of NHM felt that basic rate ISDN had the potential for providing excellent remote access capability. Initially ISDN was not able to achieve this, but recently the situation has improved. The authors feel that ISDN can now provide, at a remote site such as a user`s home, a computing environment very similar to that which is available at Fermilab. Such an environment can include direct LAN access, windowing systems, graphics, networked file systems, and demanding software applications. This paper proposes using ethernet bridging over ISDN for remote connectivity. With ISDN remote bridging, a remote Macintosh, PC, X-terminal, workstation, or other computer will be transparently connected to the Fermilab LAN. Except for a slight speed difference, the remote machine should function just as if it were on the LAN at Fermilab, with all network services-file sharing, printer sharing, X-windows, etc. - fully available. There are two additional reasons for exploring technologies such as ISDN. First, by mid-decade environmental legislation such as the Federal Clean Air Act of 1990 and Illinois Senate Bill 2177 will likely force increased remote-worker arrangements. Second, recent pilot programs and studies have shown that for many types of work there may be a substantial cost benefits to supporting work away from the site.

  19. Development of Curie point switching for thin film, random access, memory device

    NASA Technical Reports Server (NTRS)

    Lewicki, G. W.; Tchernev, D. I.

    1967-01-01

    Managanese bismuthide films are used in the development of a random access memory device of high packing density and nondestructive readout capability. Memory entry is by Curie point switching using a laser beam. Readout is accomplished by microoptical or micromagnetic scanning.

  20. Control of Access to Memory: The Use of Task Interference as a Behavioral Probe

    ERIC Educational Resources Information Center

    Loft, Shayne; Humphreys, Michael S.; Whitney, Susannah J.

    2008-01-01

    Directed forgetting and prospective memory methods were combined to examine differences in the control of memory access. Between studying two lists of target words, participants were either instructed to forget the first list, or to continue remembering the first list. After study participants performed a lexical decision task with an additional…

  1. Efficient teleportation between remote single-atom quantum memories.

    PubMed

    Nölleke, Christian; Neuzner, Andreas; Reiserer, Andreas; Hahn, Carolin; Rempe, Gerhard; Ritter, Stephan

    2013-04-01

    We demonstrate teleportation of quantum bits between two single atoms in distant laboratories. Using a time-resolved photonic Bell-state measurement, we achieve a teleportation fidelity of (88.0 ± 1.5)%, largely determined by our entanglement fidelity. The low photon collection efficiency in free space is overcome by trapping each atom in an optical cavity. The resulting success probability of 0.1% is almost 5 orders of magnitude larger than in previous experiments with remote material qubits. It is mainly limited by photon propagation and detection losses and can be enhanced with a cavity-based deterministic Bell-state measurement. PMID:25166964

  2. Analysis of Solar Census Remote Solar Access Value Calculation Methodology

    SciTech Connect

    Nangle, J.; Dean, J.; Van Geet, O.

    2015-03-01

    The costs of photovoltaic (PV) system hardware (PV panels, inverters, racking, etc.) have fallen dramatically over the past few years. Nonhardware (soft) costs, however, have failed to keep pace with the decrease in hardware costs, and soft costs have become a major driver of U.S. PV system prices. Upfront or 'sunken' customer acquisition costs make up a portion of an installation's soft costs and can be addressed through software solutions that aim to streamline sales and system design aspects of customer acquisition. One of the key soft costs associated with sales and system design is collecting information on solar access for a particular site. Solar access, reported in solar access values (SAVs), is a measurement of the available clear sky over a site and is used to characterize the impacts of local shading objects. Historically, onsite shading studies have been required to characterize the SAV of the proposed array and determine the potential energy production of a photovoltaic system.

  3. Remote semantic memory in patients with Korsakoff's syndrome and herpes encephalitis.

    PubMed

    Kopelman, Michael D; Bright, Peter; Fulker, Helena; Hinton, Nicola; Morrison, Amy; Verfaellie, Mieke

    2009-03-01

    Performance of patients with Korsakoff's syndrome and herpes encephalitis was compared on a retrograde amnesia (RA) test, asking subjects to recall and recognize the definitions of words that had come into the language at different time periods. Performance was also compared on a related test in which participants were asked to produce the words to definitions they were given in free recall and cued recall versions. It was hypothesized that, if the temporal gradient in remote memory results from a shift of information from episodic to semantic memory, then there should be a temporal gradient on these tasks, possibly steeper (i.e., greater relative sparing of early memories) in the patients in the Korsakoff group than in the herpes encephalitis group, who have widespread temporal lobe damage. Furthermore, in comparing semantic and episodic remote memory tests, consolidation theory would predict uniform temporal gradients across such tasks, whereas multiple trace theory would predict a differential pattern. The results showed that patients with Korsakoff's syndrome and patients with herpes encephalitis were significantly impaired across all time periods on the vocabulary tests, with only minimal evidence of temporal gradients, relative to healthy participants, and there was no evidence of a differential pattern of impairment between the two patient groups. Comparison with performance on measures of episodic retrograde amnesia, in which there was a differential pattern of temporal gradient, suggests that the relative preservation of early episodic remote memories in patients with Korsakoff's syndrome does not result from an episodic-to-semantic shift in the quality with which memories are stored. These findings are discussed in relation to existing theories of RA and to the patients' underlying patterns of neuropathology. PMID:19254087

  4. Centralized Library and Learning Resources: A Remote Access Demonstration Project.

    ERIC Educational Resources Information Center

    Shamel, Cynthia L.

    2001-01-01

    Describes a program instituted by a consortium of San Diego County (California) community colleges that provided distance learners with access to library reference services. States that the program included telephone, e-mail, and real time chat service and used an off-site, contract librarian. Reports on variable results. (Contains 8 references.)…

  5. Scaling constraints in nanoelectronic random-access memories.

    PubMed

    Amsinck, Christian J; Di Spigna, Neil H; Nackashi, David P; Franzon, Paul D

    2005-10-01

    Nanoelectronic molecular and magnetic tunnel junction (MTJ) MRAM crossbar memory systems have the potential to present significant area advantages (4 to 6F(2)) compared to CMOS-based systems. The scalability of these conductivity-switched RAM arrays is examined by establishing criteria for correct functionality based on the readout margin. Using a combined circuit theoretical modelling and simulation approach, the impact of both the device and interconnect architecture on the scalability of a conductivity-state memory system is quantified. This establishes criteria showing the conditions and on/off ratios for the large-scale integration of molecular devices, guiding molecular device design. With 10% readout margin on the resistive load, a memory device needs to have an on/off ratio of at least 7 to be integrated into a 64 x 64 array, while an on/off ratio of 43 is necessary to scale the memory to 512 x 512. PMID:20818005

  6. The structured memory access architecture: An implementation and performance-evaluation

    SciTech Connect

    Cyr, J.B.

    1986-08-01

    The Structured Memory Access (SMS) architecture implementation presented in this thesis is formulated with the intention of alleviating two well-known inefficiencies that exist in current scalar computer architectures: address generation overhead and memory bandwidth utilization. Furthermore, the SMA architecture introduces an additional level of parallelism which is not present in current pipelined supercomputers, namely, overlapped execution of the access process and execute process on two distinct special-purpose, asynchronously-coupled processors. Each processor executes a separate instruction stream to perform its specific task which, together, are functionally equivalent in a conventional program. Our simulation results show that, for typical numerical programs, the access processor (MAP) is capable of achieving slip, i.e., running sufficiently ahead of the execute processor (CP) so that operand fetch requests for data items required by the CP are issued early enough and rapidly enough for the CP rarely to experience any memory access wait time. In this manner the SMA tolerates long memory access time, albeit high bandwidth, paths to memory without sacrificing performance. Speedups relative to the Cray-1 in scalar mode often exceed two, due to dual processing and reductions in memory wait time. 17 refs., 11 figs., 3 tabs.

  7. Integration of lead zirconium titanate thin films for high density ferroelectric random access memory

    NASA Astrophysics Data System (ADS)

    Kim, Kinam; Lee, Sungyung

    2006-09-01

    Interests are being focused on types of nonvolatile memories such as ferroelectric random access memory (FRAM), phase change random access memory, or magnetoresistance random access memory due to their distinct memory properties such as excellent write performance which conventional nonvolatile memories do not possess. Among these types of nonvolatile memories, FRAM whose cell structure and operation are almost identical to dynamic random access memory (DRAM) can ideally realize cell size and speed of DRAM. Thus FRAM is the most appropriate candidate for future universal memory where all memory functions are performed with a single chip solution. Due to the poor ferroelectric properties of downscaled ultrathin lead zirconium titanate (PZT) capacitors as well as technical issues such as hydrogen and plasma related degradation arising from embedding ferroelectric metal-insulator-metal capacitors into conventional complementary metal oxide semiconductor processes, current FRAM still falls far below its ideally attainable cell size and performance. In this paper, based upon PZT capacitor, current mass-productive one pass transistor and one storage capacitor (1T1C), capacitor over bit line (COB) cell technologies are introduced upon which cell size of 0.937μm2 at 250nm minimum feature size technology node has been realized. And then, most recent 1T1C, COB cell technologies are discussed from which cell size of 0.27μm2 at 150nm minimum feature size technology node has been realized, and finally future three dimensional capacitor technologies for the FRAM with cell size of less than 0.08μm2 beyond 100nm minimum feature size technology node are suggested.

  8. Remote access and operation of telescopes by the scientific users

    NASA Astrophysics Data System (ADS)

    Edwards, P. G.; Amy, S.; Brodrick, D.; Carretti, E.; Hoyle, S.; Indermuehle, B.; McConnell, D.; Mader, S.; Mirtschin, P.; Preisig, B.; Smith, M.; Stevens, J.; Wark, R.; Wieringa, M.; Wu, X.

    2014-08-01

    The Australia Telescope National Facility operates three radio telescopes: the Parkes 64m Telescope, the Australia Telescope Compact Array (ATCA), and the Mopra 22m Telescope. Scientific operation of all these is conducted by members of the investigating teams rather than by professional operators. All three can now be accessed and controlled from any location served by the internet, the telescopes themselves being unattended for part or all of the time. Here we describe the rationale, advantages, and means of implementing this operational model.

  9. High speed magneto-resistive random access memory

    NASA Technical Reports Server (NTRS)

    Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor)

    1992-01-01

    A high speed read MRAM memory element is configured from a sandwich of magnetizable, ferromagnetic film surrounding a magneto-resistive film which may be ferromagnetic or not. One outer ferromagnetic film has a higher coercive force than the other and therefore remains magnetized in one sense while the other may be switched in sense by a switching magnetic field. The magneto-resistive film is therefore sensitive to the amplitude of the resultant field between the outer ferromagnetic films and may be constructed of a high resistivity, high magneto-resistive material capable of higher sensing currents. This permits higher read voltages and therefore faster read operations. Alternate embodiments with perpendicular anisotropy, and in-plane anisotropy are shown, including an embodiment which uses high permeability guides to direct the closing flux path through the magneto-resistive material. High density, high speed, radiation hard, memory matrices may be constructed from these memory elements.

  10. Dynamic Optical Gratings Accessed by Reversible Shape Memory.

    PubMed

    Tippets, Cary A; Li, Qiaoxi; Fu, Yulan; Donev, Eugenii U; Zhou, Jing; Turner, Sara A; Jackson, Anne-Martine S; Ashby, Valerie Sheares; Sheiko, Sergei S; Lopez, Rene

    2015-07-01

    Shape memory polymers (SMPs) have been shown to accurately replicate photonic structures that produce tunable optical responses, but in practice, these responses are limited by the irreversibility of conventional shape memory processes. Here, we report the intensity modulation of a diffraction grating utilizing two-way reversible shape changes. Reversible shifting of the grating height was accomplished through partial melting and recrystallization of semicrystalline poly(octylene adipate). The concurrent variations of the grating shape and diffraction intensity were monitored via atomic force microscopy and first order diffraction measurements, respectively. A maximum reversibility of the diffraction intensity of 36% was repeatable over multiple cycles. To that end, the reversible shape memory process is shown to broaden the functionality of SMP-based optical devices. PMID:26081101

  11. Coupling Prefix Caching and Collective Downloads for Remote Data Access

    SciTech Connect

    Ma, Xiaosong; Vazhkudai, Sudharshan S; Freeh, Vincent W; Simon, Tyler A; Yang, Tao; Scott, Stephen L

    2006-01-01

    Scientific datasets are typically archived at mass storage systems or data centers close to supercomputers/instruments. Endusers of these datasets, however, usually perform parts of their workflows at their local computers. In such cases, client-side caching can offer significant gains by reducing the cost of widearea data movement. Scientific data caches, however, traditionally cache entire datasets, which may not be necessary. In this paper, we propose a novel combination of prefix caching and collective download. Prefix caching allows the bootstrapping of dataset downloads by caching only a prefix of the dataset, while collective download facilitates efficient parallel patching of the missing suffix from an external data source. To estimate the optimal prefix size, we further present an analytical model that considers both the initial download overhead and the downloading speed. We implemented our proposed approach in the FreeLoader distributed cache prototype. Experimental results (using multiple scientific data repositories and data transfer tools, as well as a real-world scientific dataset access trace) demonstrate that prefix caching and collective download can be implemented efficiently, our model can select an appropriate prefix size, and the cache hit rate can be improved significantly without hurting the local access rate of cached datasets.

  12. Remote access to crystallography beamlines at SSRL: novel tools for training, education and collaboration

    PubMed Central

    Smith, Clyde A.; Card, Graeme L.; Cohen, Aina E.; Doukov, Tzanko I.; Eriksson, Thomas; Gonzalez, Ana M.; McPhillips, Scott E.; Dunten, Pete W.; Mathews, Irimpan I.; Song, Jinhu; Soltis, S. Michael

    2010-01-01

    For the past five years, the Structural Molecular Biology group at the Stanford Synchrotron Radiation Lightsource (SSRL) has provided general users of the facility with fully remote access to the macromolecular crystallography beamlines. This was made possible by implementing fully automated beamlines with a flexible control system and an intuitive user interface, and by the development of the robust and efficient Stanford automated mounting robotic sample-changing system. The ability to control a synchrotron beamline remotely from the comfort of the home laboratory has set a new paradigm for the collection of high-quality X-ray diffraction data and has fostered new collaborative research, whereby a number of remote users from different institutions can be connected at the same time to the SSRL beamlines. The use of remote access has revolutionized the way in which scientists interact with synchrotron beamlines and collect diffraction data, and has also triggered a shift in the way crystallography students are introduced to synchrotron data collection and trained in the best methods for collecting high-quality data. SSRL provides expert crystallographic and engineering staff, state-of-the-art crystallography beamlines, and a number of accessible tools to facilitate data collection and in-house remote training, and encourages the use of these facilities for education, training, outreach and collaborative research. PMID:22184477

  13. Hybrid Flexible Resistive Random Access Memory-Gated Transistor for Novel Nonvolatile Data Storage.

    PubMed

    Han, Su-Ting; Zhou, Ye; Chen, Bo; Wang, Chundong; Zhou, Li; Yan, Yan; Zhuang, Jiaqing; Sun, Qijun; Zhang, Hua; Roy, V A L

    2016-01-20

    Here, a single-device demonstration of novel hybrid architecture is reported to achieve programmable transistor nodes which have analogies to flash memory by incorporating a resistive switching random access memory (RRAM) device as a resistive switch gate for field effect transistor (FET) on a flexible substrate. A high performance flexible RRAM with a three-layered structure is fabricated by utilizing solution-processed MoS2 nanosheets sandwiched between poly(methyl methacrylate) polymer layers. Gate coupling with the pentacene-based transistor can be controlled by the RRAM memory state to produce a nonprogrammed state (inactive) and a programmed state (active) with a well-defined memory window. Compared to the reference flash memory device based on the MoS2 floating gate, the hybrid device presents robust access speed and retention ability. Furthermore, the hybrid RRAM-gated FET is used to build an integrated logic circuit and a wide logic window in inverter logic is achieved. The controllable, well-defined memory window, long retention time, and fast access speed of this novel hybrid device may open up new possibilities of realizing fully functional nonvolatile memory for high-performance flexible electronics. PMID:26578160

  14. Access when and where They Want It: Using EZproxy to Serve Our Remote Users

    ERIC Educational Resources Information Center

    Lawrence, Peg

    2009-01-01

    In these days of distance learners, virtual libraries, and electronic information, no library can be without some way of providing remote access to affiliated users, whether they are distance students, online students, or local students and faculty members working from home. Libraries subscribe to any number of electronic resources and journals,…

  15. Universal Access to Preschool Education: Approaches to Integrating Preschool with School in Rural and Remote Communities

    ERIC Educational Resources Information Center

    Dockett, Sue; Perry, Bob

    2014-01-01

    In 2012, the government of South Australia responded to Federal agreements aimed at universal access to preschool education for children in the year before starting formal schooling by introducing a trial designed to "integrate" preschool children into first year of school programmes in rural and remote areas of the state. This paper…

  16. Asymmetrical access to color and location in visual working memory.

    PubMed

    Rajsic, Jason; Wilson, Daryl E

    2014-10-01

    Models of visual working memory (VWM) have benefitted greatly from the use of the delayed-matching paradigm. However, in this task, the ability to recall a probed feature is confounded with the ability to maintain the proper binding between the feature that is to be reported and the feature (typically location) that is used to cue a particular item for report. Given that location is typically used as a cue-feature, we used the delayed-estimation paradigm to compare memory for location to memory for color, rotating which feature was used as a cue and which was reported. Our results revealed several novel findings: 1) the likelihood of reporting a probed object's feature was superior when reporting location with a color cue than when reporting color with a location cue; 2) location report errors were composed entirely of swap errors, with little to no random location reports; and 3) both colour and location reports greatly benefitted from the presence of nonprobed items at test. This last finding suggests that it is uncertainty over the bindings between locations and colors at memory retrieval that drive swap errors, not at encoding. We interpret our findings as consistent with a representational architecture that nests remembered object features within remembered locations. PMID:25190322

  17. Involvement of the Anterior Cingulate Cortex in Formation, Consolidation, and Reconsolidation of Recent and Remote Contextual Fear Memory

    ERIC Educational Resources Information Center

    Einarsson, Einar O.; Nader, Karim

    2012-01-01

    It has been suggested that memories become more stable and less susceptible to the disruption of reconsolidation over weeks after learning. Here, we test this by targeting the anterior cingulate cortex (ACC) and test its involvement in the formation, consolidation, and reconsolidation of recent and remote contextual fear memory. We found that…

  18. Remote access to ACNUC nucleotide and protein sequence databases at PBIL.

    PubMed

    Gouy, Manolo; Delmotte, Stéphane

    2008-04-01

    The ACNUC biological sequence database system provides powerful and fast query and extraction capabilities to a variety of nucleotide and protein sequence databases. The collection of ACNUC databases served by the Pôle Bio-Informatique Lyonnais includes the EMBL, GenBank, RefSeq and UniProt nucleotide and protein sequence databases and a series of other sequence databases that support comparative genomics analyses: HOVERGEN and HOGENOM containing families of homologous protein-coding genes from vertebrate and prokaryotic genomes, respectively; Ensembl and Genome Reviews for analyses of prokaryotic and of selected eukaryotic genomes. This report describes the main features of the ACNUC system and the access to ACNUC databases from any internet-connected computer. Such access was made possible by the definition of a remote ACNUC access protocol and the implementation of Application Programming Interfaces between the C, Python and R languages and this communication protocol. Two retrieval programs for ACNUC databases, Query_win, with a graphical user interface and raa_query, with a command line interface, are also described. Altogether, these bioinformatics tools provide users with either ready-to-use means of querying remote sequence databases through a variety of selection criteria, or a simple way to endow application programs with an extensive access to these databases. Remote access to ACNUC databases is open to all and fully documented (http://pbil.univ-lyon1.fr/databases/acnuc/acnuc.html). PMID:17825976

  19. Chronic ethanol consumption impairs spatial remote memory in rats but does not affect cortical cholinergic parameters.

    PubMed

    Pereira, S R; Menezes, G A; Franco, G C; Costa, A E; Ribeiro, A M

    1998-06-01

    We have studied learning, memory and cortical cholinergic parameters after oral administration of 20% v/v ethanol solution to male Fisher rats for 6 months. A group of rats were trained to behave efficiently in an eight-arm radial maze and after that split into two subgroups submitted to ethanol or control treatment. Ethanol-treated rats had more difficulty in relearning the same task 1 year later, compared to ethanol-untreated rats (control). Differences in working memory performance were found, but only in the first 10 training sessions. Another group of rats, which had not been pretrained, was also split into two subgroups submitted to ethanol or control treatment. After that, these rats were trained in the radial maze task for the first time. No significant difference was found between the reference memory performance of the untreated subgroup and the treated one. These two subgroups did not significantly differ in their working memory performance either. Moreover, there were no significant differences between treated and control subjects in the following biochemical brain cortical parameters: in vitro acetylcholinesterase (AChE) activity, and stimulated acetylcholine (ACh) release. This work presents an experimental design that allows assessment of remote memory performance after ethanol chronic consumption and shows that the experimental subject is able to retain the behaviors learned 1 year before. It was concluded that chronic ethanol treatment may cause retrograde amnesia, which does not seem to be linked with a cortical cholinergic deficit. PMID:9632211

  20. Histone H2A.Z subunit exchange controls consolidation of recent and remote memory.

    PubMed

    Zovkic, Iva B; Paulukaitis, Brynna S; Day, Jeremy J; Etikala, Deepa M; Sweatt, J David

    2014-11-27

    Memory formation is a multi-stage process that initially requires cellular consolidation in the hippocampus, after which memories are downloaded to the cortex for maintenance, in a process termed systems consolidation. Epigenetic mechanisms regulate both types of consolidation, but histone variant exchange, in which canonical histones are replaced with their variant counterparts, is an entire branch of epigenetics that has received limited attention in the brain and has never, to our knowledge, been studied in relation to cognitive function. Here we show that histone H2A.Z, a variant of histone H2A, is actively exchanged in response to fear conditioning in the hippocampus and the cortex, where it mediates gene expression and restrains the formation of recent and remote memory. Our data provide evidence for H2A.Z involvement in cognitive function and specifically implicate H2A.Z as a negative regulator of hippocampal consolidation and systems consolidation, probably through downstream effects on gene expression. Moreover, alterations in H2A.Z binding at later stages of systems consolidation suggest that this histone has the capacity to mediate stable molecular modifications required for memory retention. Overall, our data introduce histone variant exchange as a novel mechanism contributing to the molecular basis of cognitive function and implicate H2A.Z as a potential therapeutic target for memory disorders. PMID:25219850

  1. Phase-change Random Access Memory: A Scalable Technology

    SciTech Connect

    Raoux, S.; Burr, G; Breitwisch, M; Rettner, C; Chen, Y; Shelby, R; Salinga, M; Krebs, D; Chen, S; Lung, H

    2008-01-01

    Nonvolatile RAM using resistance contrast in phase-change materials [or phase-change RAM (PCRAM)] is a promising technology for future storage-class memory. However, such a technology can succeed only if it can scale smaller in size, given the increasingly tiny memory cells that are projected for future technology nodes (i.e., generations). We first discuss the critical aspects that may affect the scaling of PCRAM, including materials properties, power consumption during programming and read operations, thermal cross-talk between memory cells, and failure mechanisms. We then discuss experiments that directly address the scaling properties of the phase-change materials themselves, including studies of phase transitions in both nanoparticles and ultrathin films as a function of particle size and film thickness. This work in materials directly motivated the successful creation of a series of prototype PCRAM devices, which have been fabricated and tested at phase-change material cross-sections with extremely small dimensions as low as 3 nm x 20 nm. These device measurements provide a clear demonstration of the excellent scaling potential offered by this technology, and they are also consistent with the scaling behavior predicted by extensive device simulations. Finally, we discuss issues of device integration and cell design, manufacturability, and reliability.

  2. Evaluating existing access opportunities for disabled persons at remote shoreline recreation sites

    SciTech Connect

    Bley, M.R.; Kearns, M.T.

    1995-12-31

    Draft guidelines for providing outdoor recreation access opportunities for disabled persons have been recommended by the Recreation Access Advisory Committee and in the Universal Access to Outdoor Recreation: A Design Guide. The Federal Energy Regulatory Commission requires applicants for new hydropower licenses to consider access opportunities for disabled persons at existing hydropower projects. A process for evaluating existing access opportunities for disabled persons at remote shoreline recreation sites at hydropower projects is described. The process includes five steps: (1) preparing a preliminary map of existing recreation sites; (2) data collection in the field; (3) evaluating compliance of existing facilities; (4) feasibility of enhancing existing facilities; and (5) designing enhancements. The process will be refined when final standards and processes are approved by the appropriate agencies and organizations.

  3. Optical interconnection network for parallel access to multi-rank memory in future computing systems.

    PubMed

    Wang, Kang; Gu, Huaxi; Yang, Yintang; Wang, Kun

    2015-08-10

    With the number of cores increasing, there is an emerging need for a high-bandwidth low-latency interconnection network, serving core-to-memory communication. In this paper, aiming at the goal of simultaneous access to multi-rank memory, we propose an optical interconnection network for core-to-memory communication. In the proposed network, the wavelength usage is delicately arranged so that cores can communicate with different ranks at the same time and broadcast for flow control can be achieved. A distributed memory controller architecture that works in a pipeline mode is also designed for efficient optical communication and transaction address processes. The scaling method and wavelength assignment for the proposed network are investigated. Compared with traditional electronic bus-based core-to-memory communication, the simulation results based on the PARSEC benchmark show that the bandwidth enhancement and latency reduction are apparent. PMID:26367901

  4. Spin-transfer torque magnetoresistive random-access memory technologies for normally off computing (invited)

    SciTech Connect

    Ando, K. Yuasa, S.; Fujita, S.; Ito, J.; Yoda, H.; Suzuki, Y.; Nakatani, Y.; Miyazaki, T.

    2014-05-07

    Most parts of present computer systems are made of volatile devices, and the power to supply them to avoid information loss causes huge energy losses. We can eliminate this meaningless energy loss by utilizing the non-volatile function of advanced spin-transfer torque magnetoresistive random-access memory (STT-MRAM) technology and create a new type of computer, i.e., normally off computers. Critical tasks to achieve normally off computers are implementations of STT-MRAM technologies in the main memory and low-level cache memories. STT-MRAM technology for applications to the main memory has been successfully developed by using perpendicular STT-MRAMs, and faster STT-MRAM technologies for applications to the cache memory are now being developed. The present status of STT-MRAMs and challenges that remain for normally off computers are discussed.

  5. A packetised remote visual access data system for space station interactive payload operations.

    PubMed

    Carvell, R P

    1987-09-01

    Potential users of the pressurised Columbus elements, (the Attached Pressurised Module and the Man-Tended Free Flyer), were consulted in order to establish the requirements necessary to achieve effective and efficient remote interactive payload operations. These are briefly described and clearly indicate that the key to such operations is a versatile remote visual access (video) system which is well-tuned to the requirements of the users in both the on-board and ground segments. A packetised remote visual access data system is proposed which accommodates these requirements and offers a very flexible operational environment. It incorporates a scheme for optimising users' remote visual access to their experiments. Methods of implementing the necessary multiplexing and compression aspects of the system are discussed. A scheme for centralized on-board monitoring, which is complicated by the wide range of video sources required by the users, is outlined and aspects of the ground segment, in particular the problem is link delays, are considered. PMID:11542957

  6. Accessing and Utilizing Remote Sensing Data for Vectorborne Infectious Diseases Surveillance and Modeling

    NASA Technical Reports Server (NTRS)

    Kiang, Richard; Adimi, Farida; Kempler, Steven

    2008-01-01

    Background: The transmission of vectorborne infectious diseases is often influenced by environmental, meteorological and climatic parameters, because the vector life cycle depends on these factors. For example, the geophysical parameters relevant to malaria transmission include precipitation, surface temperature, humidity, elevation, and vegetation type. Because these parameters are routinely measured by satellites, remote sensing is an important technological tool for predicting, preventing, and containing a number of vectorborne infectious diseases, such as malaria, dengue, West Nile virus, etc. Methods: A variety of NASA remote sensing data can be used for modeling vectorborne infectious disease transmission. We will discuss both the well known and less known remote sensing data, including Landsat, AVHRR (Advanced Very High Resolution Radiometer), MODIS (Moderate Resolution Imaging Spectroradiometer), TRMM (Tropical Rainfall Measuring Mission), ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), EO-1 (Earth Observing One) ALI (Advanced Land Imager), and SIESIP (Seasonal to Interannual Earth Science Information Partner) dataset. Giovanni is a Web-based application developed by the NASA Goddard Earth Sciences Data and Information Services Center. It provides a simple and intuitive way to visualize, analyze, and access vast amounts of Earth science remote sensing data. After remote sensing data is obtained, a variety of techniques, including generalized linear models and artificial intelligence oriented methods, t 3 can be used to model the dependency of disease transmission on these parameters. Results: The processes of accessing, visualizing and utilizing precipitation data using Giovanni, and acquiring other data at additional websites are illustrated. Malaria incidence time series for some parts of Thailand and Indonesia are used to demonstrate that malaria incidences are reasonably well modeled with generalized linear models and artificial

  7. Prenatal Stress Produces Persistence of Remote Memory and Disrupts Functional Connectivity in the Hippocampal-Prefrontal Cortex Axis.

    PubMed

    Negrón-Oyarzo, Ignacio; Neira, David; Espinosa, Nelson; Fuentealba, Pablo; Aboitiz, Francisco

    2015-09-01

    Prenatal stress is a risk factor for the development of neuropsychiatric disorders, many of which are commonly characterized by an increased persistence of aversive remote memory. Here, we addressed the effect of prenatal stress on both memory consolidation and functional connectivity in the hippocampal-prefrontal cortex axis, a dynamical interplay that is critical for mnemonic processing. Pregnant mice of the C57BL6 strain were subjected to restraint stressed during the last week of pregnancy, and male offspring were behaviorally tested at adulthood for recent and remote spatial memory performance in the Barnes Maze test under an aversive context. Prenatal stress did not affect the acquisition or recall of recent memory. In contrast, it produced the persistence of remote spatial memory. Memory persistence was not associated with alterations in major network rhythms, such as hippocampal sharp-wave ripples (SWRs) or neocortical spindles. Instead, it was associated with a large decrease in the basal discharge activity of identified principal neurons in the medial prefrontal cortex (mPFC) as measured in urethane anesthetized mice. Furthermore, functional connectivity was disrupted, as the temporal coupling between neuronal discharge in the mPFC and hippocampal SWRs was decreased by prenatal stress. These results could be relevant to understand the biological basis of the persistence of aversive remote memories in stress-related disorders. PMID:24860018

  8. Knowledge Accessibility, Achievement Goals, and Memory Strategy Maintenance

    ERIC Educational Resources Information Center

    Escribe, Christian; Huet, Nathalie

    2005-01-01

    Background: An important aim of educational psychology is to account for the difficulties in cognitive strategy maintenance. Possible explanations may be found in developmental studies concerning the interdependence of knowledge accessibility and strategy use, and in current achievement goal models which assume that individuals with a learning…

  9. Program partitioning for NUMA multiprocessor computer systems. [Nonuniform memory access

    SciTech Connect

    Wolski, R.M.; Feo, J.T. )

    1993-11-01

    Program partitioning and scheduling are essential steps in programming non-shared-memory computer systems. Partitioning is the separation of program operations into sequential tasks, and scheduling is the assignment of tasks to processors. To be effective, automatic methods require an accurate representation of the model of computation and the target architecture. Current partitioning methods assume today's most prevalent models -- macro dataflow and a homogeneous/two-level multicomputer system. Based on communication channels, neither model represents well the emerging class of NUMA multiprocessor computer systems consisting of hierarchical read/write memories. Consequently, the partitions generated by extant methods do not execute well on these systems. In this paper, the authors extend the conventional graph representation of the macro-dataflow model to enable mapping heuristics to consider the complex communication options supported by NUMA architectures. They describe two such heuristics. Simulated execution times of program graphs show that the model and heuristics generate higher quality program mappings than current methods for NUMA architectures.

  10. Electrical Evaluation of RCA MWS5501D Random Access Memory, Volume 2, Appendix a

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    The electrical characterization and qualification test results are presented for the RCA MWS5001D random access memory. The tests included functional tests, AC and DC parametric tests, AC parametric worst-case pattern selection test, determination of worst-case transition for setup and hold times, and a series of schmoo plots. The address access time, address readout time, the data hold time, and the data setup time are some of the results surveyed.

  11. Remote light energy harvesting and actuation using shape memory alloy—piezoelectric hybrid transducer

    NASA Astrophysics Data System (ADS)

    Avirovik, Dragan; Kumar, Ashok; Bodnar, Robert J.; Priya, Shashank

    2013-05-01

    Shape memory alloys (SMAs) exhibit a memory effect which causes the alloy to return to its original shape when heated beyond the transformation temperature. In this study, we show that SMA can be heated remotely by laser and the resulting deformation can be converted into electricity through a piezoelectric bimorph. In addition, the laser actuated SMA deformation can also be used to provide controlled actuation. We provide experimental results demonstrating both the power harvesting and actuation behavior as a function of laser pulse rate. SMA used in this study exhibited higher absorption in the ultraviolet region which progressively decreased as the absorption wavelength increased. Raman analysis revealed TiO2 formation on the surface of SMA, whose concentration increased irreversibly with temperature. Negligible changes in the surface oxidation were detected in the working temperature range (<150 °C).

  12. Quantifying Access Disadvantage and Gathering Information in Rural and Remote Localities: The Griffith Service Access Frame.

    ERIC Educational Resources Information Center

    Griffith, Dennis A.

    2003-01-01

    A purely geographic classification is not the best way to measure rural disadvantage in Australia. A service access model is described that incorporates the following elements: population center size; distance, time, and cost of travel to the service center; and a measure of the economic capacity of residents to overcome the cost of travel.…

  13. Remote access to neurosurgical ICU physiological data using the World Wide Web.

    PubMed

    Nenov, V; Klopp, J

    1996-01-01

    There is a significant demand by physicians and clinical researchers for remote access to continuously acquired physiological patient data. Until recently such access was technically unfeasible. However, with the recent development of Internet-based World Wide Web (WWW) client/server applications and underlying communication protocols, there is now a real possibility for the development of cost-effective, platform independent solutions to this problem. We have devised a way using existing WWW tools and minimal startup costs to provide access to current as well as previously acquired physiological patient data. Physicians and clinical researchers can obtain access to these data through personal computers located in the office, at home or even through portable computers while traveling to conferences or while on vacation. PMID:10163756

  14. Increasing Access and Usability of Remote Sensing Data: The NASA Protected Area Archive

    NASA Technical Reports Server (NTRS)

    Geller, Gary N.

    2004-01-01

    Although remote sensing data are now widely available, much of it at low or no-cost, many managers of protected conservation areas do not have the expertise or tools to view or analyze it. Thus access to it by the protected area management community is effectively blocked. The Protected Area Archive will increase access to remote sensing data by creating collections of satellite images of protected areas and packaging them with simple-to-use visualization and analytical tools. The user can easily locate the area and image of interest on a map, then display, roam, and zoom the image. A set of simple tools will be provided so the user can explore the data and employ it to assist in management and monitoring of their area. The 'Phase 1 ' version requires only a Windows-based computer and basic computer skills, and may be of particular help to protected area managers in developing countries.

  15. Remotely amplified combined ring-tree dense access network architecture using reflective RSOA-based ONU

    NASA Astrophysics Data System (ADS)

    Lazaro, Jose A.; Bock, Carlos; Polo, Victor; Martinez, Reynaldo I.; Prat, Josep

    2007-06-01

    A highly scalable access architecture achieving high density and featuring resiliency, centralized light-generation control, remote amplification, and colorless optical network unit with reflective semiconductor optical amplifier (RSOA) for upstream modulation is presented and experimentally demonstrated. It is based on a user-single-fiber completely passive outside plant and provides broadband connections to >1000 users distributed along large distances. It is believed to represent an intermediate step toward metro-access convergence and offers flexible configurations covering high- and low-density population areas.

  16. Making Physical Activity Accessible to Older Adults with Memory Loss: A Feasibility Study

    ERIC Educational Resources Information Center

    Logsdon, Rebecca G.; McCurry, Susan M.; Pike, Kenneth C.; Teri, Linda

    2009-01-01

    Purpose: For individuals with mild cognitive impairment (MCI), memory loss may prevent successful engagement in exercise, a key factor in preventing additional disability. The Resources and Activities for Life Long Independence (RALLI) program uses behavioral principles to make exercise more accessible for these individuals. Exercises are broken…

  17. 77 FR 26789 - Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... violation of section 337 in the infringement of certain patents. 73 FR 75131. The principal respondent was... order. 75 FR 44989-90 (July 30, 2010). The Commission also issued cease and desist orders against those... COMMISSION Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers...

  18. 76 FR 2336 - Dynamic Random Access Memory Semiconductors From the Republic of Korea: Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-13

    ...On September 14, 2010, the Department of Commerce published in the Federal Register its preliminary results of administrative review of the countervailing duty order on dynamic random access memory semiconductors from the Republic of Korea for the period January 1, 2008, through August 10, 2008. We provided interested parties with an opportunity to comment on the preliminary results. Our......

  19. Robotic observatories. A handbook of remote-access personal-computer astronomy.

    NASA Astrophysics Data System (ADS)

    Genet, R. M.; Hayes, D. S.; Epand, D. H.; Boyd, L. J.; Keller, D. F.

    Contents: 1. Astronomy while you sleep. 2. Remote-access automatic telescopes. 3. The next step. 4. Automatic telescopes in space. 5. An automatic observatory system. 6. Automatic telescopes. 7. Telescope control. 8. Instruments for automatic telescopes. 9. CCD cameras. 10. Automatic observatories. 11. Manual telescope control. 12. Automatic telescope instruction set (ATIS). 13. Automatic telescope control. 14. Differential photometry file generator. 15. Differential photometry data reduction. 16. Quality-control photometry.

  20. Fencing direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2013-09-03

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to segments of shared random access memory through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and a segment of shared memory; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  1. Fencing direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A; Mamidala, Amith R

    2014-02-11

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to segments of shared random access memory through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and a segment of shared memory; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  2. 75 FR 20564 - Dynamic Random Access Memory Semiconductors from the Republic of Korea: Extension of Time Limit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... Antidumping and Countervailing Duty Administrative Reviews and Requests for Revocation in Part, 74 FR 48224... International Trade Administration Dynamic Random Access Memory Semiconductors from the Republic of Korea... administrative review of the countervailing duty order on dynamic random access memory semiconductors from...

  3. 75 FR 44283 - In the Matter of Certain Dynamic Random Access Memory Semiconductors and Products Containing Same...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-28

    ... America Corp. of Milpitas, California (collectively ``complainants''). 75 FR 14467-68 (March 25, 2010... COMMISSION In the Matter of Certain Dynamic Random Access Memory Semiconductors and Products Containing Same... within the United States after importation of certain dynamic random access memory semiconductors...

  4. Shared direct memory access on the Explorer 2-LX

    NASA Technical Reports Server (NTRS)

    Musgrave, Jeffrey L.

    1990-01-01

    Advances in Expert System technology and Artificial Intelligence have provided a framework for applying automated Intelligence to the solution of problems which were generally perceived as intractable using more classical approaches. As a result, hybrid architectures and parallel processing capability have become more common in computing environments. The Texas Instruments Explorer II-LX is an example of a machine which combines a symbolic processing environment, and a computationally oriented environment in a single chassis for integrated problem solutions. This user's manual is an attempt to make these capabilities more accessible to a wider range of engineers and programmers with problems well suited to solution in such an environment.

  5. Remote Use of CD-ROM.

    ERIC Educational Resources Information Center

    Fitzwater, Diana; And Others

    1991-01-01

    Describes the use of a telecommunications program called "PC Anywhere" to afford users remote access to compact disc ready-only-memory (CD-ROM) systems. Describes hardware requirements and benefits to libraries and users. (DMM)

  6. Functional neuroanatomy of remote episodic, semantic and spatial memory: a unified account based on multiple trace theory

    PubMed Central

    Moscovitch, Morris; Rosenbaum, R Shayna; Gilboa, Asaf; Addis, Donna Rose; Westmacott, Robyn; Grady, Cheryl; McAndrews, Mary Pat; Levine, Brian; Black, Sandra; Winocur, Gordon; Nadel, Lynn

    2005-01-01

    We review lesion and neuroimaging evidence on the role of the hippocampus, and other structures, in retention and retrieval of recent and remote memories. We examine episodic, semantic and spatial memory, and show that important distinctions exist among different types of these memories and the structures that mediate them. We argue that retention and retrieval of detailed, vivid autobiographical memories depend on the hippocampal system no matter how long ago they were acquired. Semantic memories, on the other hand, benefit from hippocampal contribution for some time before they can be retrieved independently of the hippocampus. Even semantic memories, however, can have episodic elements associated with them that continue to depend on the hippocampus. Likewise, we distinguish between experientially detailed spatial memories (akin to episodic memory) and more schematic memories (akin to semantic memory) that are sufficient for navigation but not for re-experiencing the environment in which they were acquired. Like their episodic and semantic counterparts, the former type of spatial memory is dependent on the hippocampus no matter how long ago it was acquired, whereas the latter can survive independently of the hippocampus and is represented in extra-hippocampal structures. In short, the evidence reviewed suggests strongly that the function of the hippocampus (and possibly that of related limbic structures) is to help encode, retain, and retrieve experiences, no matter how long ago the events comprising the experience occurred, and no matter whether the memories are episodic or spatial. We conclude that the evidence favours a multiple trace theory (MTT) of memory over two other models: (1) traditional consolidation models which posit that the hippocampus is a time-limited memory structure for all forms of memory; and (2) versions of cognitive map theory which posit that the hippocampus is needed for representing all forms of allocentric space in memory. PMID

  7. Primary health care accessibility challenges in remote indigenous communities in Canada's North

    PubMed Central

    Oosterveer, Tim Michiel; Kue Young, T.

    2015-01-01

    Background Despite many improvements, health disparities between indigenous and non-indigenous populations in Canada's North persist. While a strong primary health care (PHC) system improves the health of a population, the majority of indigenous communities are very remote, and their access to PHC services is likely reduced. Understanding the challenges in accessing PHC services in these communities is necessary to improve the health of the population. Objective The objective of the study was to document and analyze the challenges in accessing PHC services by indigenous people in remote communities in Canada's Northwest Territories (NWT) from the perspectives of users and providers of PHC services. Methods Using explorative, qualitative methods, our study involved 14 semi-structured interviews with PHC service providers (SPs) and service users (SUs) in 5 communities across the NWT which varied according to population, remoteness, ethnic composition and health care resources. The interview guide was developed after key informant consultations. Results Both SPs and SUs understood the constraints in providing equitable access to PHC services in remote communities. The provision of emergency care was found to be particularly challenging, because of the lack of qualified staff in the community and the dependence on aeromedical evacuations. Wider dissemination of first aid skills among community members was seen to cover some gaps and also increase self-confidence. For non-emergency care, the need to travel outside the community was generally disliked. All recognized the need for more preventive services which were often postponed or delayed because of the overwhelming demand for acute care. As long as services were provided in a community, the satisfaction was high among SUs. SPs appreciated the orientation they received and the ability to build rapport with the community. Conclusions Northern SUs and SPs generally acknowledge the health consequences of living in remote

  8. Fast-earth: A global image caching architecture for fast access to remote-sensing data

    NASA Astrophysics Data System (ADS)

    Talbot, B. G.; Talbot, L. M.

    We introduce Fast-Earth, a novel server architecture that enables rapid access to remote sensing data. Fast-Earth subdivides a WGS-84 model of the earth into small 400 × 400 meter regions with fixed locations, called plats. The resulting 3,187,932,913 indexed plats are accessed with a rapid look-up algorithm. Whereas many traditional databases store large original images as a series by collection time, requiring long searches and slow access times for user queries, the Fast-Earth architecture enables rapid access. We have prototyped a system in conjunction with a Fast-Responder mobile app to demonstrate and evaluate the concepts. We found that new data could be indexed rapidly in about 10 minutes/terabyte, high-resolution images could be chipped in less than a second, and 250 kB image chips could be delivered over a 3G network in about 3 seconds. The prototype server implemented on a very small computer could handle 100 users, but the concept is scalable. Fast-Earth enables dramatic advances in rapid dissemination of remote sensing data for mobile platforms as well as desktop enterprises.

  9. Grey and White Matter Correlates of Recent and Remote Autobiographical Memory Retrieval – Insights from the Dementias

    PubMed Central

    Irish, Muireann; Hornberger, Michael; El Wahsh, Shadi; Lam, Bonnie Y. K.; Lah, Suncica; Miller, Laurie; Hsieh, Sharpley; Hodges, John R.; Piguet, Olivier

    2014-01-01

    The capacity to remember self-referential past events relies on the integrity of a distributed neural network. Controversy exists, however, regarding the involvement of specific brain structures for the retrieval of recently experienced versus more distant events. Here, we explored how characteristic patterns of atrophy in neurodegenerative disorders differentially disrupt remote versus recent autobiographical memory. Eleven behavioural-variant frontotemporal dementia, 10 semantic dementia, 15 Alzheimer's disease patients and 14 healthy older Controls completed the Autobiographical Interview. All patient groups displayed significant remote memory impairments relative to Controls. Similarly, recent period retrieval was significantly compromised in behavioural-variant frontotemporal dementia and Alzheimer's disease, yet semantic dementia patients scored in line with Controls. Voxel-based morphometry and diffusion tensor imaging analyses, for all participants combined, were conducted to investigate grey and white matter correlates of remote and recent autobiographical memory retrieval. Neural correlates common to both recent and remote time periods were identified, including the hippocampus, medial prefrontal, and frontopolar cortices, and the forceps minor and left hippocampal portion of the cingulum bundle. Regions exclusively implicated in each time period were also identified. The integrity of the anterior temporal cortices was related to the retrieval of remote memories, whereas the posterior cingulate cortex emerged as a structure significantly associated with recent autobiographical memory retrieval. This study represents the first investigation of the grey and white matter correlates of remote and recent autobiographical memory retrieval in neurodegenerative disorders. Our findings demonstrate the importance of core brain structures, including the medial prefrontal cortex and hippocampus, irrespective of time period, and point towards the contribution of

  10. Medial temporal and neocortical contributions to remote memory for semantic narratives: evidence from amnesia.

    PubMed

    Verfaellie, Mieke; Bousquet, Kathryn; Keane, Margaret M

    2014-08-01

    Studies of remote memory for semantic facts and concepts suggest that hippocampal lesions lead to a temporally graded impairment that extends no more than ten years prior to the onset of amnesia. Such findings have led to the notion that once consolidated, semantic memories are represented neocortically and are no longer dependent on the hippocampus. Here, we examined the fate of well-established semantic narratives following medial temporal lobe (MTL) lesions. Seven amnesic patients, five with lesions restricted to the MTL and two with lesions extending into lateral temporal cortex (MTL+), were asked to recount fairy tales and bible stories that they rated as familiar. Narratives were scored for number and type of details, number of main thematic elements, and order in which the main thematic elements were recounted. In comparison to controls, patients with MTL lesions produced fewer details, but the number and order of main thematic elements generated was intact. By contrast, patients with MTL+ lesions showed a pervasive impairment, affecting not only the generation of details, but also the generation and ordering of main steps. These findings challenge the notion that, once consolidated, semantic memories are no longer dependent on the hippocampus for retrieval. Possible hippocampal contributions to the retrieval of detailed semantic narratives are discussed. PMID:24953960

  11. Medial Temporal and Neocortical Contributions to Remote Memory for Semantic Narratives: Evidence from Amnesia

    PubMed Central

    Verfaellie, Mieke; Bousquet, Kathryn; Keane, Margaret M.

    2014-01-01

    Studies of remote memory for semantic facts and concepts suggest that hippocampal lesions lead to a temporally graded impairment that extends no more than ten years prior to the onset of amnesia. Such findings have led to the notion that once consolidated, semantic memories are represented neocortically and are no longer dependent on the hippocampus. Here, we examined the fate of well-established semantic narratives following medial temporal lobe (MTL) lesions. Seven amnesic patients, five with lesions restricted to the MTL and two with lesions extending into lateral temporal cortex (MTL+), were asked to recount fairy tales and bible stories that they rated as familiar. Narratives were scored for number and type of details, number of main thematic elements, and order in which the main thematic elements were recounted. In comparison to controls, patients with MTL lesions produced fewer details, but the number and order of main thematic elements generated was intact. By contrast, patients with MTL+ lesions showed a pervasive impairment, affecting not only the generation of details, but also the generation and ordering of main steps. These findings challenge the notion that, once consolidated, semantic memories are no longer dependent on the hippocampus for retrieval. Possible hippocampal contributions to the retrieval of detailed semantic narratives are discussed. PMID:24953960

  12. Academic and Non-Profit Accessibility to Commercial Remote Sensing Software

    NASA Astrophysics Data System (ADS)

    O'Connor, A. S.; Farr, B.

    2013-12-01

    Remote Sensing as a topic of teaching and research at the university and college level continues to increase. As more data is made freely available and software becomes easier to use, more and more academic and non-profits institutions are turning to remote sensing to solve their tough and large spatial scale problems. Exelis Visual Information Solutions (VIS) has been supporting teaching and research endeavors for over 30 years with a special emphasis over the last 5 years with scientifically proven software and accessible training materials. The Exelis VIS academic program extends to US and Canadian 2 year and 4 year colleges and universities with tools for analyzing aerial and satellite multispectral and hyperspectral imagery, airborne LiDAR and Synthetic Aperture Radar. The Exelis VIS academic programs, using the ENVI Platform, enables labs and classrooms to be outfitted with software and makes software accessible to students. The ENVI software provides students hands on experience with remote sensing software, an easy teaching platform for professors and allows researchers scientifically vetted software they can trust. Training materials are provided at no additional cost and can either serve as a basis for course curriculum development or self paced learning. Non-profit organizations like The Nature Conservancy (TNC) and CGIAR have deployed ENVI and IDL enterprise wide licensing allowing researchers all over the world to have cost effective access COTS software for their research. Exelis VIS has also contributed licenses to the NASA DEVELOP program. Exelis VIS is committed to supporting the academic and NGO community with affordable enterprise licensing, access to training materials, and technical expertise to help researchers tackle today's Earth and Planetary science big data challenges.

  13. Optical Shared Memory Computing and Multiple Access Protocols for Photonic Networks

    NASA Astrophysics Data System (ADS)

    Li, Kuang-Yu.

    In this research we investigate potential applications of optics in massively parallel computer systems, especially focusing on design issues in three-dimensional optical data storage and free-space photonic networks. An optical implementation of a shared memory uses a single photorefractive crystal and can realize the set of memory modules in a digital shared memory computer. A complete instruction set consists of R sc EAD, W sc RITE, S sc ELECTIVE E sc RASE, and R sc EFRESH, which can be applied to any memory module independent of (and in parallel with) instructions to the other memory modules. In addition, a memory module can execute a sequence of R sc EAD operations simultaneously with the execution of a W sc RITE operation to accommodate differences in optical recording and readout times common to optical volume storage media. An experimental shared memory system is demonstrated and its projected performance is analyzed. A multiplexing technique is presented to significantly reduce both grating- and beam-degeneracy crosstalk in volume holographic systems, by incorporating space, angle, and wavelength as the multiplexing parameters. In this approach, each hologram, which results from the interference between a single input node and an object array, partially overlaps with the other holograms in its neighborhood. This technique can offer improved interconnection density, optical throughput, signal fidelity, and space-bandwidth product utilization. Design principles and numerical simulation results are presented. A free-space photonic cellular hypercube parallel computer, with emphasis on the design of a collisionless multiple access protocol, is presented. This design incorporates wavelength-, space-, and time-multiplexing to achieve multiple access, wavelength reuse, dense connectivity, collisionless communications, and a simple control mechanism. Analytic models based on semi-Markov processes are employed to analyze this protocol. The performance of the

  14. Effects of erbium doping of indium tin oxide electrode in resistive random access memory

    NASA Astrophysics Data System (ADS)

    Chen, Po-Hsun; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Lin, Chih-Yang; Jin, Fu-Yuan; Chen, Min-Chen; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2016-03-01

    Identical insulators and bottom electrodes were fabricated and capped by an indium tin oxide (ITO) film, either undoped or doped with erbium (Er), as a top electrode. This distinctive top electrode dramatically altered the resistive random access memory (RRAM) characteristics, for example, lowering the operation current and enlarging the memory window. In addition, the RESET voltage increased, whereas the SET voltage remained almost the same. A conduction model of Er-doped ITO is proposed through current-voltage (I-V) measurement and current fitting to explain the resistance switching mechanism of Er-doped ITO RRAM and is confirmed by material analysis and reliability tests.

  15. Multilevel Cell Storage and Resistance Variability in Resistive Random Access Memory

    NASA Astrophysics Data System (ADS)

    Pantelis, D. I.; Karakizis, P. N.; Dragatogiannis, D. A.; Charitidis, C. A.

    2016-06-01

    Multilevel per cell (MLC) storage in resistive random access memory (ReRAM) is attractive in achieving high-density and low-cost memory and will be required in future. In this chapter, MLC storage and resistance variability and reliability of multilevel in ReRAM are discussed. Different MLC operation schemes with their physical mechanisms and a comprehensive analysis of resistance variability have been provided. Various factors that can induce variability and their effect on the resistance margin between the multiple resistance levels are assessed. The reliability characteristics and the impact on MLC storage have also been assessed.

  16. A new laterally conductive bridge random access memory by fully CMOS logic compatible process

    NASA Astrophysics Data System (ADS)

    Hsieh, Min-Che; Chin, Yung-Wen; Lin, Yu-Cheng; Chih, Yu-Der; Tsai, Kan-Hsueh; Tsai, Ming-Jinn; King, Ya-Chin; Lin, Chrong Jung

    2014-01-01

    This paper proposes a novel laterally conductive bridge random access memory (L-CBRAM) module using a fully CMOS logic compatible process. A contact buffer layer between the poly-Si and contact plug enables the lateral Ti-based atomic layer to provide on/off resistance ratio via bipolar operations. The proposed device reached more than 100 pulse cycles with an on/off ratio over 10 and very stable data retention under high temperature operations. These results make this Ti-based L-CBRAM cell a promising solution for advanced embedded multi-time programmable (MTP) memory applications.

  17. A role for adult hippocampal neurogenesis at multiple time scales: A study of recent and remote memory in humans.

    PubMed

    Déry, Nicolas; Goldstein, Aaron; Becker, Suzanna

    2015-08-01

    Adult hippocampal neurogenesis (AHN) is downregulated by numerous lifestyle factors including chronic stress. While the functional significance of AHN remains elusive, computational models and empirical evidence implicate immature neurons in minimizing interference between similar memories-a process termed pattern separation. The role of neurogenesis in remote memory is less clear. Some have proposed that neurogenesis promotes the clearance of old memories from the hippocampus, while others have proposed that neurogenesis promotes long-term retention of memories within the hippocampus. We used a modified version of the behavioral pattern separation task originally described by Kirwan and Stark (2007). In this task, some objects are repeated across trials, some are similar lures and the rest are novel. Participants are asked to classify each object as old, new, or similar. The correct classification of lures as similar may tax pattern separation processes in the hippocampus and AHN. To investigate the potential role of AHN in remote memory, we introduced a 2-week delay between the presentation and recognition of certain stimuli. As in previous studies, we found that those with higher depression scores made significantly more errors at identifying lures as similar when presentation and recognition were separated by a brief delay. When presentation and recognition trials were separated by a longer delay, the correct classification of lures dropped to chance levels for all groups, but now lower stress and depression scores were associated with superior identification of exact repetitions. Our data suggest a role for AHN in the stabilization of remote memories. PMID:26076341

  18. On-line scalable image access for medical remote collaborative meetings

    NASA Astrophysics Data System (ADS)

    Tarando, Sebastian R.; Lucidarme, Olivier; Grenier, Philippe; Fetita, Catalin

    2015-03-01

    The increasing need of remote medical investigation services in the framework of collaborative multidisciplinary meetings (e.g. cancer follow-up) raises the challenge of on-line remote access of (large amount of) radiologic data in a limited period of time. This paper proposes a scalable compression framework of DICOM images providing low-latency display through low speed networks. The developed approach relies on useless information removal from images (i.e. not related with the patient body) and the exploitation of the JPEG2000 standard to achieve progressive quality encoding and access of the data. This mechanism also allows the efficient exploitation of any idle times (corresponding to on-line visual image analysis) to download the remaining data at lossless quality in a way transparent to the user, thus minimizing the perceived latency. The experiments performed in comparison with exchanging uncompressed or JPEGlossless compressed DICOM data, showed the benefit of the proposed approach for collaborative on-line remote diagnosis and follow-up services.

  19. VisPortal: Increasing Scientific Productivity by Simplifying Access to and Use of Remote Computational Resources

    SciTech Connect

    Siegerist, Cristina; Shalf, John; Bethel, E. Wes

    2004-01-01

    Our goal is to simplify and streamline the process of using remotely located visual data analysis software tools. This discussion presents an example of an easy-to-use interface that mediates access to and use of diverse and powerful visual data analysis resources. The interface is presented via a standard web browser, which is ubiquitous and a part of every researchers work environment. Through the web interface, a few mouse clicks are all that is needed to take advantage of powerful, remotely located software resources. The VisPortal project is the software that provides diverse services to remotely located users through their web browser. Using standard Globus-grid middleware and off-the-shelf web automation, the VisPortal hides the underlying complexity of resource selection and distributed application management. The portal automates complex workflows that would otherwise require a substantial amount of manual effort on the part of the researcher. With a few mouse clicks, a researcher can quickly perform complex tasks like creating MPEG movies, scheduling file transfers, launching components of a distributed application, and accessing specialized resources.

  20. A mobile agent approach to access and represent remote spatial information in LBS

    NASA Astrophysics Data System (ADS)

    Fang, Zhixiang; Li, Qingquan; Luo, Zhi; Geng, Xuexian

    2005-10-01

    The mobile computing based Location based Service (LBS) technology has been increasingly grown in the past decade; however there still exist some important constraints that complicate work with a mobile spatial information system. The limited resources in the mobile computing terminals would restrict some features that are available on the traditional computing technology. This paper will explores the use of a cooperative, distributed multi-agent systems (Java Agent Development Framework, JADE) to improve the efficiency of accessing and represent remote spatial information in mobile terminals and fixed terminal which support Java runtime environment (JRE), because that JADE system has following features: distributed agent platform, graphical user interface to manage several agents and agent containers form remote host, supporting to execution of multiple, parallel and concurrent agent activities via behavior model, FIPA-compliant platform including AMS (Agent Management System), DF (Directory Facilitator) and ACC (Agent Communication Channel), Efficient transport of ACL messages inside same agent system, library of FIPA interaction protocols ready to be used, FIPA-compliant naming service and supporting for application-defined content languages and ontology. An agile and flexible agent based approach for accessing and representing remote spatial information is proposed in this paper, mobile agent system architecture in LBS is presented, and a prototype system is given to shown that JADE makes this approach feasible and effective.

  1. Large Capacity of Conscious Access for Incidental Memories in Natural Scenes.

    PubMed

    Kaunitz, Lisandro N; Rowe, Elise G; Tsuchiya, Naotsugu

    2016-09-01

    When searching a crowd, people can detect a target face only by direct fixation and attention. Once the target is found, it is consciously experienced and remembered, but what is the perceptual fate of the fixated nontarget faces? Whereas introspection suggests that one may remember nontargets, previous studies have proposed that almost no memory should be retained. Using a gaze-contingent paradigm, we asked subjects to visually search for a target face within a crowded natural scene and then tested their memory for nontarget faces, as well as their confidence in those memories. Subjects remembered up to seven fixated, nontarget faces with more than 70% accuracy. Memory accuracy was correlated with trial-by-trial confidence ratings, which implies that the memory was consciously maintained and accessed. When the search scene was inverted, no more than three nontarget faces were remembered. These findings imply that incidental memory for faces, such as those recalled by eyewitnesses, is more reliable than is usually assumed. PMID:27507869

  2. Redefining nondiscriminatory access to remote sensing imagery and its impact on global transparency

    NASA Astrophysics Data System (ADS)

    Aten, Michelle L.

    2003-04-01

    Global transparency is founded on the Open Skies philosophy and its precept of non-discriminatory access. Global transparency implies that anyone can have anytime, anyplace access to a wide-array of remotely sensed imagery. The custom of non-discriminatory access requires that datasets of interest must be affordable, usable, and obtainable in a timely fashion devoid of political, economic or technical obstacles. Thus, an assessment of the correlation between the availability of satellite imagery and changes in governmental policies, pricing fluctuations of data, and advances in technology is critical to assessing the viability of global transparency. The Open Skies philosophy was originally proposed at the 1955 Geneva Summit to advocate mutually beneficial aerial reconnaissance missions over the USSR and the US as a verification tool for arms control and non-proliferation agreements. However, due to Cold War tensions, this philosophy and the custom of non-discriminatory were not widely adopted in the civilian remote sensing community until the commissioning of the Landsat Program in 1972. Since this time, commercial high-resolution satellites have drastically changed the circumstances on which the fundamental tenets of this philosophy are based. Since the successful launch of the first of this satellite class, the IKONOS satellite, high-resolution imagery is now available to non-US governments and an unlimited set of non-state actors. As more advanced capabilities are added to the growing assortment of remote sensing satellites, the reality of global transparency will rapidly evolve. This assessment includes an overview of historical precedents and a brief explanation of relevant US policy decisions that define non-discriminatory access with respect to US government and US based corporate assets. It also presents the dynamics of the political, economic, and technical barriers that may dictate or influence the remote sensing community's access to satellite data. In

  3. Remote collaboration and data access at the DIII-D National Fusion Facility

    SciTech Connect

    Schissel, D.P.

    1998-09-01

    As the number of on-site and remote collaborators has increased, the demands on the DIII-D National Program`s computational infrastructure has become more severe. The Director of the DIII-D Program recognized the increased importance of computers in carrying out the DIII-D mission and in late 1997 formed the Data Analysis Programming Group. Utilizing both software and hardware improvements, this new group has been charged with increasing the DIII-D data analysis throughput and data retrieval rate. Understanding the importance of the remote collaborators, this group has developed a long term plan that will allow for fast 24 hour data access (7x24) with complete documentation and a set of data viewing and analysis tools that can be run either on the collaborators` or DIII-D`s computer systems. This paper presents the group`s long term plan and progress to date.

  4. Role of adult neurogenesis in hippocampus-dependent memory, contextual fear extinction and remote contextual memory: new insights from ERK5 MAP kinase.

    PubMed

    Pan, Yung-Wei; Storm, Daniel R; Xia, Zhengui

    2013-10-01

    Adult neurogenesis occurs in two discrete regions of the adult mammalian brain, the subgranular zone (SGZ) of the dentate gyrus (DG) and the subventricular zone (SVZ) along the lateral ventricles. Signaling mechanisms regulating adult neurogenesis in the SGZ are currently an active area of investigation. Adult-born neurons in the DG functionally integrate into the hippocampal circuitry and form functional synapses, suggesting a role for these neurons in hippocampus-dependent memory formation. Although results from earlier behavioral studies addressing this issue were inconsistent, recent advances in conditional gene targeting technology, viral injection and optogenetic approaches have provided convincing evidence supporting a role for adult-born neurons in the more challenging forms of hippocampus-dependent learning and memory. Here, we briefly summarize these recent studies with a focus on extra signal-regulated kinase (ERK) 5, a MAP kinase whose expression in the adult brain is restricted to the neurogenic regions including the SGZ and SVZ. We review evidence identifying ERK5 as a novel endogenous signaling pathway that regulates the pro-neural transcription factor Neurogenin 2, is activated by neurotrophins and is critical for adult neurogenesis. We discuss studies demonstrating that specific deletion of ERK5 in the adult neurogenic regions impairs several forms of hippocampus-dependent memory formation in mice. These include contextual fear memory extinction, the establishment and maintenance of remote contextual fear memory, and several other challenging forms of hippocampus-dependent memory formation including 48h memory for novel object recognition, contextual fear memory established by a weak foot shock, pattern separation, and reversal of spatial learning and memory. We also briefly discuss current evidence that increasing adult neurogenesis, by small molecules or genetic manipulation, improves memory formation and long-term memory. PMID:23871742

  5. Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

    NASA Astrophysics Data System (ADS)

    Zheng, Qi-Wen; Yu, Xue-Feng; Cui, Jiang-Wei; Guo, Qi; Ren, Di-Yuan; Cong, Zhong-Chao; Zhou, Hang

    2014-10-01

    Pattern imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ΔSNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device.

  6. Design of Unstructured Adaptive (UA) NAS Parallel Benchmark Featuring Irregular, Dynamic Memory Accesses

    NASA Technical Reports Server (NTRS)

    Feng, Hui-Yu; VanderWijngaart, Rob; Biswas, Rupak; Biegel, Bryan (Technical Monitor)

    2001-01-01

    We describe the design of a new method for the measurement of the performance of modern computer systems when solving scientific problems featuring irregular, dynamic memory accesses. The method involves the solution of a stylized heat transfer problem on an unstructured, adaptive grid. A Spectral Element Method (SEM) with an adaptive, nonconforming mesh is selected to discretize the transport equation. The relatively high order of the SEM lowers the fraction of wall clock time spent on inter-processor communication, which eases the load balancing task and allows us to concentrate on the memory accesses. The benchmark is designed to be three-dimensional. Parallelization and load balance issues of a reference implementation will be described in detail in future reports.

  7. Dramatic reduction of read disturb through pulse width control in spin torque random access memory

    NASA Astrophysics Data System (ADS)

    Wang, Zihui; Wang, Xiaobin; Gan, Huadong; Jung, Dongha; Satoh, Kimihiro; Lin, Tsann; Zhou, Yuchen; Zhang, Jing; Huai, Yiming; Chang, Yao-Jen; Wu, Te-ho

    2013-09-01

    Magnetizations dynamic effect in low current read disturb region is studied both experimentally and theoretically. Dramatic read error rate reduction through read pulse width control is theoretically predicted and experimentally observed. The strong dependence of read error rate upon pulse width contrasts conventional energy barrier approach and can only be obtained considering detailed magnetization dynamics at long time thermal magnetization reversal region. Our study provides a design possibility for ultra-fast low current spin torque random access memory.

  8. Electrical Evaluation of RCA MWS5001D Random Access Memory, Volume 5, Appendix D

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    The electrical characterization and qualification test results are presented for the RCA MWS 5001D random access memory. The tests included functional tests, AC and DC parametric tests, AC parametric worst-case pattern selection test, determination of worst-case transition for setup and hold times, and a series of schmoo plots. Average input high current, worst case input high current, output low current, and data setup time are some of the results presented.

  9. Electrical Evaluation of RCA MWS5001D Random Access Memory, Volume 4, Appendix C

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    The electrical characterization and qualification test results are presented for the RCA MWS5001D random access memory. The tests included functional tests, AC and DC parametric tests, AC parametric worst-case pattern selection test, determination of worst-case transition for setup and hold times, and a series of schmoo plots. Statistical analysis data is supplied along with write pulse width, read cycle time, write cycle time, and chip enable time data.

  10. Vibroacoustic Payload Environment Prediction System (VAPEPS): VAPEPS management center remote access guide

    NASA Technical Reports Server (NTRS)

    Fernandez, J. P.; Mills, D.

    1991-01-01

    A Vibroacoustic Payload Environment Prediction System (VAPEPS) Management Center was established at the JPL. The center utilizes the VAPEPS software package to manage a data base of Space Shuttle and expendable launch vehicle payload flight and ground test data. Remote terminal access over telephone lines to the computer system, where the program resides, was established to provide the payload community a convenient means of querying the global VAPEPS data base. This guide describes the functions of the VAPEPS Management Center and contains instructions for utilizing the resources of the center.

  11. Vibroacoustic payload environment prediction system (VAPEPS): Data base management center remote access guide

    NASA Technical Reports Server (NTRS)

    Thomas, V. C.

    1986-01-01

    A Vibroacoustic Data Base Management Center has been established at the Jet Propulsion Laboratory (JPL). The center utilizes the Vibroacoustic Payload Environment Prediction System (VAPEPS) software package to manage a data base of shuttle and expendable launch vehicle flight and ground test data. Remote terminal access over telephone lines to a dedicated VAPEPS computer system has been established to provide the payload community a convenient means of querying the global VAPEPS data base. This guide describes the functions of the JPL Data Base Management Center and contains instructions for utilizing the resources of the center.

  12. Immigration, language proficiency, and autobiographical memories: Lifespan distribution and second-language access.

    PubMed

    Esposito, Alena G; Baker-Ward, Lynne

    2016-08-01

    This investigation examined two controversies in the autobiographical literature: how cross-language immigration affects the distribution of autobiographical memories across the lifespan and under what circumstances language-dependent recall is observed. Both Spanish/English bilingual immigrants and English monolingual non-immigrants participated in a cue word study, with the bilingual sample taking part in a within-subject language manipulation. The expected bump in the number of memories from early life was observed for non-immigrants but not immigrants, who reported more memories for events surrounding immigration. Aspects of the methodology addressed possible reasons for past discrepant findings. Language-dependent recall was influenced by second-language proficiency. Results were interpreted as evidence that bilinguals with high second-language proficiency, in contrast to those with lower second-language proficiency, access a single conceptual store through either language. The final multi-level model predicting language-dependent recall, including second-language proficiency, age of immigration, internal language, and cue word language, explained ¾ of the between-person variance and (1)/5 of the within-person variance. We arrive at two conclusions. First, major life transitions influence the distribution of memories. Second, concept representation across multiple languages follows a developmental model. In addition, the results underscore the importance of considering language experience in research involving memory reports. PMID:26274061

  13. Ge2Sb2Te5 Confined Structures and Integration of 64 Mb Phase-Change Random Access Memory

    NASA Astrophysics Data System (ADS)

    Yeung, Fai; Ahn, Su-Jin; Hwang, Young-Nam; Jeong, Chang-Wook; Song, Yoon-Jong; Lee, Su-Youn; Lee, Se-Ho; Ryoo, Kyung-Chang; Park, Jae-Hyun; Shin, Jae-Min; Jeong, Won-Cheol; Kim, Young-Tae; Koh, Gwan-Hyeob; Jeong, Gi-Tae; Jeong, Hong-Sik; Kim, Kinam

    2005-04-01

    Phase-change random access memory is considered a potential challenger for conventional memories, such as dynamic random access memory and flash memory due to its numerous advantages. Nevertheless, high reset current is the ultimate problem in developing high-density phase-change random access memory (PRAM). We focus on the adoption of Ge2Sb2Te5 confined structures to achieve lower reset currents. By changing from a normal to a GST confined structure, the reset current drops to as low as 0.8 mA. Eventually, our integrated 64 Mb PRAM based on 0.18 μm CMOS technology offers a large sensing margin: Rreset ˜200 kΩ and Rset ˜2 kΩ, as well as reasonable reliability: an endurance of 1.0× 109 cycles and a retention time of 2 years at 85°C.

  14. Towards a Low-Cost Remote Memory Attestation for the Smart Grid

    PubMed Central

    Yang, Xinyu; He, Xiaofei; Yu, Wei; Lin, Jie; Li, Rui; Yang, Qingyu; Song, Houbing

    2015-01-01

    In the smart grid, measurement devices may be compromised by adversaries, and their operations could be disrupted by attacks. A number of schemes to efficiently and accurately detect these compromised devices remotely have been proposed. Nonetheless, most of the existing schemes detecting compromised devices depend on the incremental response time in the attestation process, which are sensitive to data transmission delay and lead to high computation and network overhead. To address the issue, in this paper, we propose a low-cost remote memory attestation scheme (LRMA), which can efficiently and accurately detect compromised smart meters considering real-time network delay and achieve low computation and network overhead. In LRMA, the impact of real-time network delay on detecting compromised nodes can be eliminated via investigating the time differences reported from relay nodes. Furthermore, the attestation frequency in LRMA is dynamically adjusted with the compromised probability of each node, and then, the total number of attestations could be reduced while low computation and network overhead can be achieved. Through a combination of extensive theoretical analysis and evaluations, our data demonstrate that our proposed scheme can achieve better detection capacity and lower computation and network overhead in comparison to existing schemes. PMID:26307998

  15. Towards a Low-Cost Remote Memory Attestation for the Smart Grid.

    PubMed

    Yang, Xinyu; He, Xiaofei; Yu, Wei; Lin, Jie; Li, Rui; Yang, Qingyu; Song, Houbing

    2015-01-01

    In the smart grid, measurement devices may be compromised by adversaries, and their operations could be disrupted by attacks. A number of schemes to efficiently and accurately detect these compromised devices remotely have been proposed. Nonetheless, most of the existing schemes detecting compromised devices depend on the incremental response time in the attestation process, which are sensitive to data transmission delay and lead to high computation and network overhead. To address the issue, in this paper, we propose a low-cost remote memory attestation scheme (LRMA), which can efficiently and accurately detect compromised smart meters considering real-time network delay and achieve low computation and network overhead. In LRMA, the impact of real-time network delay on detecting compromised nodes can be eliminated via investigating the time differences reported from relay nodes. Furthermore, the attestation frequency in LRMA is dynamically adjusted with the compromised probability of each node, and then, the total number of attestations could be reduced while low computation and network overhead can be achieved. Through a combination of extensive theoretical analysis and evaluations, our data demonstrate that our proposed scheme can achieve better detection capacity and lower computation and network overhead in comparison to existing schemes. PMID:26307998

  16. Remote access to an interferometric fringes stabilization active system via RENATA

    NASA Astrophysics Data System (ADS)

    Espitia-Gómez, Javier; Ángel-Toro, Luciano

    2013-11-01

    The Advanced Technology National Network (RENATA, for its acronym in Spanish) is a Colombian, collaborative work tool, linked to other networks worldwide, in which take participation researchers, teachers and students, by sharing laboratory resources located in different universities, institutes and research centers throughout the country. In the Universidad EAFIT (Medellín, Colombia) it has been designed an interferometric fringes stabilization active system, which can be accessed remotely via the RENATA network. A Mach-Zehnder interferometer was implemented, with independent piezoelectric actuators in each arm, with which the lengths of optical path of light that goes over in each of them can be modified. Using these actuators, one can simultaneously perturb the system and compensate the phase differences caused by that perturbation. This allows us to experiment with different disturbs, and analyze the system response to each one of them. This can be made from any location worldwide, and especially from those regions in which optical and optoelectronic components required for the implementation of the interferometer or for the stabilization system are not available. The device can also be used as a platform in order to conduct diverse experiments, involving optical and controlling aspects, constituting with this in a pedagogic tool. For the future, it can be predicted that remote access to available applications would be possible, as well as modifications of the implemented code in labVIEW™, so that researchers and teachers can adapt and improve their functionalities or develop new applications, based on the collaborative work.

  17. Comprehension of Linguistic Dependencies: Speed-Accuracy Tradeoff Evidence for Direct-Access Retrieval From Memory

    PubMed Central

    Foraker, Stephani; McElree, Brian

    2012-01-01

    Comprehenders can rapidly and efficiently interpret expressions with various types of non-adjacent dependencies. In the sentence The boy that the teacher warned fell, boy is readily interpreted as the subject of the verb fall despite the fact that a relative clause, that the teacher warned, intervenes between the two dependent elements. We review research investigating three memory operations proposed for resolving this and other types of non-adjacent dependencies: serial search retrieval, in which the dependent constituent is recovered by a search process through representations in memory, direct-access retrieval in which the dependent constituent is recovered directly by retrieval cue operations without search, and active maintenance of the dependent constituent in focal attention. Studies using speed-accuracy tradeoff methodology to examine the full timecourse of interpreting a wide range of non-adjacent dependencies indicate that comprehenders retrieve dependent constituents with a direct-access operation, consistent with the claim that representations formed during comprehension are accessed with a cue-driven, content-addressable retrieval process. The observed timecourse profiles are inconsistent with a broad class of models based on several search operations for retrieval. The profiles are also inconsistent with active maintenance of a constituent while concurrently processing subsequent material, and suggest that, with few exceptions, direct-access retrieval is required to process non-adjacent dependencies. PMID:22448181

  18. Daily Access to Sucrose Impairs Aspects of Spatial Memory Tasks Reliant on Pattern Separation and Neural Proliferation in Rats

    ERIC Educational Resources Information Center

    Reichelt, Amy C.; Morris, Margaret J.; Westbrook, Reginald Frederick

    2016-01-01

    High sugar diets reduce hippocampal neurogenesis, which is required for minimizing interference between memories, a process that involves "pattern separation." We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects…

  19. Encoding and Retrieval Processes Involved in the Access of Source Information in the Absence of Item Memory

    ERIC Educational Resources Information Center

    Ball, B. Hunter; DeWitt, Michael R.; Knight, Justin B.; Hicks, Jason L.

    2014-01-01

    The current study sought to examine the relative contributions of encoding and retrieval processes in accessing contextual information in the absence of item memory using an extralist cuing procedure in which the retrieval cues used to query memory for contextual information were "related" to the target item but never actually studied.…

  20. Personal Memories for Remote Historical Events: Accuracy and Clarity of Flashbulb Memories Related to World War II

    ERIC Educational Resources Information Center

    Berntsen, Dorthe; Thomsen, Dorthe K.

    2005-01-01

    One hundred forty-five Danes between 72 and 89 years of age were asked for their memories of their reception of the news of the Danish occupation (April 1940) and liberation (May 1945) and for their most negative and most positive personal memories from World War II. Almost all reported memories for the invasion and liberation. Their answers to…

  1. Fingerprint authentication via joint transform correlator and its application in remote access control of a 3D microscopic system

    NASA Astrophysics Data System (ADS)

    He, Wenqi; Lai, Hongji; Wang, Meng; Liu, Zeyi; Yin, Yongkai; Peng, Xiang

    2014-05-01

    We present a fingerprint authentication scheme based on the optical joint transform correlator (JTC) and further describe its application to the remote access control of a Network-based Remote Laboratory (NRL). It is built to share a 3D microscopy system of our realistic laboratory in Shenzhen University with the remote co-researchers in Stuttgart University. In this article, we would like to focus on the involved security issues, mainly on the verification of various remote visitors to our NRL. By making use of the JTC-based optical pattern recognition technique as well as the Personal Identification Number (PIN), we are able to achieve the aim of authentication and access control for any remote visitors. Note that only the authorized remote visitors could be guided to the Virtual Network Computer (VNC), a cross-platform software, which allows the remote visitor to access the desktop applications and visually manipulate the instruments of our NRL through the internet. Specifically to say, when a remote visitor attempts to access to our NRL, a PIN is mandatory required in advance, which is followed by fingerprint capturing and verification. Only if both the PIN and the fingerprint are correct, can one be regarded as an authorized visitor, and then he/she would get the authority to visit our NRL by the VNC. It is also worth noting that the aforementioned "two-step verification" strategy could be further applied to verify the identity levels of various remote visitors, and therefore realize the purpose of diversified visitor management.

  2. Interleaved synchronous bus access protocol for a shared memory multi-processor system

    SciTech Connect

    Moore, W.T.

    1989-01-10

    A method is described for providing asynchronous processors with inter-processor communication and access to several memory modules over a common bus which includes a first bus and a second bus, comprising: providing clock pulses on the common bus, each pulse having a period; asserting a request signal and placing priority signal on the common bus; polling the processors during the first period to determine whether the processors request access to the common bus and to determine which one processor has priority; sending a destination address from the one processor to a destination during a second period, the destination being chosen from the processors and the several memory modules; performing one of reading input data between the destination and the processor; multiplexing priority and reading input data signals on the first bus, and multiplexing address and writing output data signals on the second bus; generating poll inhibit signals prior to each reading input data signal and prior to each memory address signal preceding a writing output data operation; and queuing the input data in a first-in-first-out manner for each of the processors when the input data indicates an interprocessor interrupt.

  3. Brain Region-Specific Activity Patterns after Recent or Remote Memory Retrieval of Auditory Conditioned Fear

    ERIC Educational Resources Information Center

    Kwon, Jeong-Tae; Jhang, Jinho; Kim, Hyung-Su; Lee, Sujin; Han, Jin-Hee

    2012-01-01

    Memory is thought to be sparsely encoded throughout multiple brain regions forming unique memory trace. Although evidence has established that the amygdala is a key brain site for memory storage and retrieval of auditory conditioned fear memory, it remains elusive whether the auditory brain regions may be involved in fear memory storage or…

  4. Low-power resistive random access memory by confining the formation of conducting filaments

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Jen; Shen, Tzu-Hsien; Lee, Lan-Hsuan; Wen, Cheng-Yen; Lee, Si-Chen

    2016-06-01

    Owing to their small physical size and low power consumption, resistive random access memory (RRAM) devices are potential for future memory and logic applications in microelectronics. In this study, a new resistive switching material structure, TiOx/silver nanoparticles/TiOx/AlTiOx, fabricated between the fluorine-doped tin oxide bottom electrode and the indium tin oxide top electrode is demonstrated. The device exhibits excellent memory performances, such as low operation voltage (<±1 V), low operation power, small variation in resistance, reliable data retention, and a large memory window. The current-voltage measurement shows that the conducting mechanism in the device at the high resistance state is via electron hopping between oxygen vacancies in the resistive switching material. When the device is switched to the low resistance state, conducting filaments are formed in the resistive switching material as a result of accumulation of oxygen vacancies. The bottom AlTiOx layer in the device structure limits the formation of conducting filaments; therefore, the current and power consumption of device operation are significantly reduced.

  5. A secure WDM ring access network employing silicon micro-ring based remote node

    NASA Astrophysics Data System (ADS)

    Sung, Jiun-Yu; Chow, Chi-Wai; Yeh, Chien-Hung; Xu, Ke; Hsu, Chin-Wei; Su, Hong-Quan; Tsang, Hon-Ki

    2014-08-01

    A secure and scalable wavelength-division-multiplexing (WDM) ring-based access network is proposed and demonstrated using proof-of-concept experiments. In the remote node (RN), wavelength hopping for specific optical networking unit (ONU) is deployed by using silicon micro-ring resonators (SMR). Using silicon-based devices could be cost-effective for the cost-sensitive access network. Hence the optical physical layer security is introduced. The issues of denial of service (DOS) attacks, eavesdropping and masquerading can be made more difficult in the proposed WDM ring-based access network. Besides, the SMRs with different dropped wavelengths can be cascaded, such that the signals pass through the preceding SMRs can be dropped by a succeeding SMR. This can increase the scalability of the RN for supporting more ONUs for future upgrade. Here, error-free 10 Gb/s downlink and 1.25 Gb/s uplink transmission are demonstrated to show the feasibility of the proposed network.

  6. Ratioless full-complementary 12-transistor static random access memory for ultra low supply voltage operation

    NASA Astrophysics Data System (ADS)

    Kondo, Takahiro; Yamamoto, Hiromasa; Hoketsu, Satoko; Imi, Hitoshi; Okamura, Hitoshi; Nakamura, Kazuyuki

    2015-04-01

    In this study, a ratioless full-complementary 12-transistor static random access memory (SRAM) was developed and measured to evaluate its operation under an ultra low supply voltage range. The ratioless SRAM design concept enables a memory cell design that is free from the consideration of the static noise margin (SNM). Furthermore, it enables a SRAM function without the restriction of transistor parameter (W/L) settings and the dependence on the variability of device characteristics. The test chips that include both conventional 6-transistor SRAM cells and the ratioless full-complementary 12-transistor SRAM cells were developed by a 180 nm CMOS process to compare their stable operations under an ultralow supply voltage condition. The measured results show that the ratioless full-complementary 12-transistor SRAM has superior immunity to device variability, and its inherent operating ability at the supply voltage of 0.22 V was experimentally confirmed.

  7. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature

    PubMed Central

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-01-01

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch−2, ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns. PMID:22109527

  8. Extremely small test cell structure for resistive random access memory element with removable bottom electrode

    SciTech Connect

    Koh, Sang-Gyu; Kishida, Satoru; Kinoshita, Kentaro

    2014-02-24

    We established a method of preparing an extremely small memory cell by fabricating a resistive random access memory (ReRAM) structure on the tip of a cantilever of an atomic force microscope. This structure has the high robustness against the drift of the cantilever, and the effective cell size was estimated to be less than 10 nm in diameter due to the electric field concentration at the tip of the cantilever, which was confirmed using electric field simulation. The proposed structure, which has a removable bottom electrode, enables not only the preparation of a tiny ReRAM structure but also the performance of unique experiments, by making the most of its high robustness against the drift of the cantilever.

  9. Bipolar resistive switching characteristics in tantalum nitride-based resistive random access memory devices

    SciTech Connect

    Kim, Myung Ju; Jeon, Dong Su; Park, Ju Hyun; Kim, Tae Geun

    2015-05-18

    This paper reports the bipolar resistive switching characteristics of TaN{sub x}-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from −0.82 V to −0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>10{sup 5 }s) and pulse-switching endurance (>10{sup 6} cycles) properties. These results indicate that TaN{sub x}-based ReRAM devices have a potential for future nonvolatile memory devices.

  10. Self-assembled tin dioxide for forming-free resistive random-access memory application

    NASA Astrophysics Data System (ADS)

    Hong, Ying-Jhan; Wang, Tsang-Hsuan; Wei, Shih-Yuan; Chang, Pin; Yew, Tri-Rung

    2016-06-01

    A novel resistive switching structure, tin-doped indium oxide (ITO)/SnO2‑ x (defined as SnO2 with oxygen vacancies)/SnS was demonstrated with a set voltage of 0.38 V, a reset voltage of ‑0.15 V, a ratio of high resistance to low resistance of 544, and forming-free and nonlinear current–voltage (I–V) characteristics. The interface of the ITO and the self-assembled SnO2‑ x contributed to the resistive switching behavior. This device showed great potential for resistive random access memory (RRAM) application and solving the sneak path problem in cross-bar memory arrays. Furthermore, a nanostructured resistive switching device was demonstrated successfully.

  11. The effect of ultraviolet irradiation on data retention characteristics of resistive random access memory

    NASA Astrophysics Data System (ADS)

    Kinoshita, Kentaro; Kimura, Kouhei; Ohmi, Koutoku; Kishida, Satoru

    It is getting more and more serious to generate soft-errors by cosmic radiation, with increasing the density of memory devices. Therefore, the irradiation resistance of resistance random access memory (ReRAM) to cosmic radiation has to be elucidated for practical use. In this paper, we investigated the data retention characteristics against ultraviolet irradiation to ReRAM with Pt/NiO/ITO structure. Soft-errors were confirmed to be caused by ultraviolet irradiation in both low and high resistance states. The analysis of irradiation frequency dependence of data retention characteristics suggested that electronic excitation by the irradiation caused the errors. Based on a statistically estimated soft-error rate, the errors were suggested to be caused by aggregation and dispersion of oxygen vacancies due to the generation of electron-hole pairs and valence change by the ultraviolet irradiation.

  12. Gate controllable resistive random access memory devices using reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Hazra, Preetam; Resmi, A. N.; Jinesh, K. B.

    2016-04-01

    The biggest challenge in the resistive random access memory (ReRAM) technology is that the basic operational parameters, such as the set and reset voltages, the current on-off ratios (hence the power), and their operational speeds, strongly depend on the active and electrode materials and their processing methods. Therefore, for its actual technological implementations, the unification of the operational parameters of the ReRAM devices appears to be a difficult task. In this letter, we show that by fabricating a resistive memory device in a thin film transistor configuration and thus applying an external gate bias, we can control the switching voltage very accurately. Taking partially reduced graphene oxide, the gate controllable switching is demonstrated, and the possible mechanisms are discussed.

  13. Peripheral orthopaedic surgery down-regulates hippocampal brain-derived neurotrophic factor and impairs remote memory in mouse.

    PubMed

    Fidalgo, A R; Cibelli, M; White, J P M; Nagy, I; Noormohamed, F; Benzonana, L; Maze, M; Ma, D

    2011-09-01

    Peripheral orthopaedic surgery induces a profound inflammatory response. This includes a substantial increase in cytokines and, especially, in the level of interleukin (IL)-1β in the hippocampus, which has been shown to impair hippocampal-dependent memory in mice. We have employed two tests of contextual remote memory to demonstrate that the inflammatory response to surgical insult in mice also results in impairment of remote memory associated with prefrontal cortex (PFC). We have also found that, under the conditions presented in the social interaction test, peripheral orthopaedic surgery does not increase anxiety-like behaviour in our animal model. Although such surgery induces an increase in the level of IL-1β in the hippocampus, it fails to do so in the PFC. Peripheral orthopaedic surgery also results in a reduction in the level of hippocampal brain-derived neurotrophic factor (BDNF) and this may contribute, in part, to the memory impairment found after such surgery. Our data suggest that a reduction in the level of hippocampal BDNF and an increase in the level of hippocampal IL-1β following surgery may affect the transference of fear memory in the mouse brain. PMID:21699962

  14. Non-volatile, high density, high speed, Micromagnet-Hall effect Random Access Memory (MHRAM)

    NASA Technical Reports Server (NTRS)

    Wu, Jiin C.; Katti, Romney R.; Stadler, Henry L.

    1991-01-01

    The micromagnetic Hall effect random access memory (MHRAM) has the potential of replacing ROMs, EPROMs, EEPROMs, and SRAMs because of its ability to achieve non-volatility, radiation hardness, high density, and fast access times, simultaneously. Information is stored magnetically in small magnetic elements (micromagnets), allowing unlimited data retention time, unlimited numbers of rewrite cycles, and inherent radiation hardness and SEU immunity, making the MHRAM suitable for ground based as well as spaceflight applications. The MHRAM device design is not affected by areal property fluctuations in the micromagnet, so high operating margins and high yield can be achieved in large scale integrated circuit (IC) fabrication. The MHRAM has short access times (less than 100 nsec). Write access time is short because on-chip transistors are used to gate current quickly, and magnetization reversal in the micromagnet can occur in a matter of a few nanoseconds. Read access time is short because the high electron mobility sensor (InAs or InSb) produces a large signal voltage in response to the fringing magnetic field from the micromagnet. High storage density is achieved since a unit cell consists only of two transistors and one micromagnet Hall effect element. By comparison, a DRAM unit cell has one transistor and one capacitor, and a SRAM unit cell has six transistors.

  15. Using the Remote Access Protocol for usability evaluation in X Windows

    SciTech Connect

    Edwards, T.; Bauer, K.; Allen, H.

    1996-12-31

    The automatic evaluation of graphical user interfaces can help reduce development costs in the creation of new designs or modification of existing designs. Several standards for the X Window System have been proposed or implemented that could greatly reduce the time spent evaluating GUIs. We implemented a User Interface Testbed (UseIT) based on the proposed Remote Access Protocol (RAP) standard. UseIT was created to automatically record an end user`s interaction with a Motif GUI application without modification or re-linking of existing code. The recorded interaction could then be replayed or displayed visually for interpretation by a human factors specialist. The end goal was to recreate the GUI and automatically recommend design changes based upon the interactions.

  16. Hydrogen induced redox mechanism in amorphous carbon resistive random access memory

    PubMed Central

    2014-01-01

    We investigated the bipolar resistive switching characteristics of the resistive random access memory (RRAM) device with amorphous carbon layer. Applying a forming voltage, the amorphous carbon layer was carbonized to form a conjugation double bond conductive filament. We proposed a hydrogen redox model to clarify the resistive switch mechanism of high/low resistance states (HRS/LRS) in carbon RRAM. The electrical conduction mechanism of LRS is attributed to conductive sp2 carbon filament with conjugation double bonds by dehydrogenation, while the electrical conduction of HRS resulted from the formation of insulating sp3-type carbon filament through hydrogenation process. PMID:24475979

  17. A stochastic simulation method for the assessment of resistive random access memory retention reliability

    SciTech Connect

    Berco, Dan Tseng, Tseung-Yuen

    2015-12-21

    This study presents an evaluation method for resistive random access memory retention reliability based on the Metropolis Monte Carlo algorithm and Gibbs free energy. The method, which does not rely on a time evolution, provides an extremely efficient way to compare the relative retention properties of metal-insulator-metal structures. It requires a small number of iterations and may be used for statistical analysis. The presented approach is used to compare the relative robustness of a single layer ZrO{sub 2} device with a double layer ZnO/ZrO{sub 2} one, and obtain results which are in good agreement with experimental data.

  18. One electron-controlled multiple-valued dynamic random-access-memory

    NASA Astrophysics Data System (ADS)

    Kye, H. W.; Song, B. N.; Lee, S. E.; Kim, J. S.; Shin, S. J.; Choi, J. B.; Yu, Y.-S.; Takahashi, Y.

    2016-02-01

    We propose a new architecture for a dynamic random-access-memory (DRAM) capable of storing multiple values by using a single-electron transistor (SET). The gate of a SET is designed to be connected to a plurality of DRAM unit cells that are arrayed at intersections of word lines and bitlines. In this SET-DRAM hybrid scheme, the multiple switching characteristics of SET enables multiple value data stored in a DRAM unit cell, and this increases the storage functionality of the device. Moreover, since refreshing data requires only a small amount of SET driving current, this enables device operating with low standby power consumption.

  19. Conductive Filament Expansion in TaOx Bipolar Resistive Random Access Memory during Pulse Cycling

    NASA Astrophysics Data System (ADS)

    Ninomiya, Takeki; Katayama, Koji; Muraoka, Shunsaku; Yasuhara, Ryutaro; Mikawa, Takumi; Wei, Zhiqiang

    2013-11-01

    The post-cycling data retention of filamentary operated resistive random access memory (ReRAM) can be improved by minimizing conductive filament expansion during pulse cycling. We find that filament size gradually grows with increasing pulse cycles due to oxygen diffusion from the region surrounding each filament. To achieve long term use of ReRAM while suppressing filament expansion, the key is to control both electric power and pulse width input during switching. We minimize CF expansion based on this concept and demonstrate long data retention even after 106 pulse switchings under optimized reset conditions.

  20. Spin-transfer-torque efficiency enhanced by edge-damage of perpendicular magnetic random access memories

    SciTech Connect

    Song, Kyungmi; Lee, Kyung-Jin

    2015-08-07

    We numerically investigate the effect of magnetic and electrical damages at the edge of a perpendicular magnetic random access memory (MRAM) cell on the spin-transfer-torque (STT) efficiency that is defined by the ratio of thermal stability factor to switching current. We find that the switching mode of an edge-damaged cell is different from that of an undamaged cell, which results in a sizable reduction in the switching current. Together with a marginal reduction of the thermal stability factor of an edge-damaged cell, this feature makes the STT efficiency large. Our results suggest that a precise edge control is viable for the optimization of STT-MRAM.

  1. Complementary resistive switching behavior induced by varying forming current compliance in resistance random access memory

    NASA Astrophysics Data System (ADS)

    Tseng, Yi-Ting; Tsai, Tsung-Ming; Chang, Ting-Chang; Shih, Chih-Cheng; Chang, Kuan-Chang; Zhang, Rui; Chen, Kai-Huang; Chen, Jung-Hui; Li, Yu-Chiuan; Lin, Chih-Yang; Hung, Ya-Chi; Syu, Yong-En; Zheng, Jin-Cheng; Sze, Simon M.

    2015-05-01

    In this study of resistance random access memory in a resistive switching film, the breakdown degree was controlled by varying forming current compliance. A SiOx layer was introduced into the ZnO layer of the structure to induce both typical bipolar resistive switching (RS) and complementary resistive switching (CRS). In addition, the SiOx layer-generated vacuum spaces in typical bipolar RS can be verified by electrical characteristics. Changing forming current compliance strikingly modifies the oxygen storage capacity of the inserted SiOx layer. CRS can be achieved, therefore, by tuning the oxygen ion storage behavior made possible by the SiOx layer.

  2. Microstructural Characterization in Reliability Measurement of Phase Change Random Access Memory

    NASA Astrophysics Data System (ADS)

    Bae, Junsoo; Hwang, Kyuman; Park, Kwangho; Jeon, Seongbu; Kang, Dae-hwan; Park, Soonoh; Ahn, Juhyeon; Kim, Seoksik; Jeong, Gitae; Chung, Chilhee

    2011-04-01

    The cell failures after cycling endurance in phase-change random access memory (PRAM) have been classified into three groups, which have been analyzed by transmission electron microscopy (TEM). Both stuck reset of the set state (D0) and stuck set of the reset state (D1) are due to a void created inside GeSbTe (GST) film or thereby lowering density of GST film. The decrease of the both set and reset resistances that leads to the tails from the reset distribution are induced from the Sb increase with cycles.

  3. Optical and electronic error correction schemes for highly parallel access memories

    NASA Astrophysics Data System (ADS)

    Neifeld, Mark A.; Hayes, Jerry D.

    1993-11-01

    We have fabricated and tested an optically addressed, parallel electronic Reed-Solomon decoder for use with parallel access optical memories. A comparison with various serial implementations has demonstrated that for many instances of code block size and error correction capability, the parallel approach is superior from the perspectives of VLSI layout area and decoding latency. The demonstrated Reed-Solomon parallel pipeline decoder operates on 60 bit input words and has been demonstrated at a clock rate of 5 MHz yielding a demonstrated data rate of 300 Mbps.

  4. Random access memory immune to single event upset using a T-resistor

    DOEpatents

    Ochoa, Jr., Agustin

    1989-01-01

    In a random access memory cell, a resistance "T" decoupling network in each leg of the cell reduces random errors caused by the interaction of energetic ions with the semiconductor material forming the cell. The cell comprises two parallel legs each containing a series pair of complementary MOS transistors having a common gate connected to the node between the transistors of the opposite leg. The decoupling network in each leg is formed by a series pair of resistors between the transistors together with a third resistor interconnecting the junction between the pair of resistors and the gate of the transistor pair forming the opposite leg of the cell.

  5. A random access memory immune to single event upset using a T-Resistor

    DOEpatents

    Ochoa, A. Jr.

    1987-10-28

    In a random access memory cell, a resistance ''T'' decoupling network in each leg of the cell reduces random errors caused by the interaction of energetic ions with the semiconductor material forming the cell. The cell comprises two parallel legs each containing a series pair of complementary MOS transistors having a common gate connected to the node between the transistors of the opposite leg. The decoupling network in each leg is formed by a series pair of resistors between the transistors together with a third resistor interconnecting the junction between the pair of resistors and the gate of the transistor pair forming the opposite leg of the cell. 4 figs.

  6. Analysis and modeling of resistive switching mechanisms oriented to resistive random-access memory

    NASA Astrophysics Data System (ADS)

    Huang, Da; Wu, Jun-Jie; Tang, Yu-Hua

    2013-03-01

    With the progress of the semiconductor industry, the resistive random-access memory (RAM) has drawn increasing attention. The discovery of the memristor has brought much attention to this study. Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms. We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models. Finally, simulations are presented. We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms, which are applied to explain their resistive switchings.

  7. Hydrogen doping in HfO2 resistance change random access memory

    NASA Astrophysics Data System (ADS)

    Duncan, D.; Magyari-Köpe, B.; Nishi, Y.

    2016-01-01

    The structures and energies of hydrogen-doped monoclinic hafnium dioxide were calculated using density-functional theory. The electronic interactions are described within the LDA + U formalism, where on-site Coulomb corrections are applied to the 5d orbital electrons of Hf atoms and 2p orbital electrons of the O atoms. The effects of charge state, defect-defect interactions, and hydrogenation are investigated and compared with experiment. It is found that hydrogenation of HfO2 resistance-change random access memory devices energetically stabilizes the formation of oxygen vacancies and conductive vacancy filaments through multiple mechanisms, leading to improved switching characteristic and device yield.

  8. A stochastic simulation method for the assessment of resistive random access memory retention reliability

    NASA Astrophysics Data System (ADS)

    Berco, Dan; Tseng, Tseung-Yuen

    2015-12-01

    This study presents an evaluation method for resistive random access memory retention reliability based on the Metropolis Monte Carlo algorithm and Gibbs free energy. The method, which does not rely on a time evolution, provides an extremely efficient way to compare the relative retention properties of metal-insulator-metal structures. It requires a small number of iterations and may be used for statistical analysis. The presented approach is used to compare the relative robustness of a single layer ZrO2 device with a double layer ZnO/ZrO2 one, and obtain results which are in good agreement with experimental data.

  9. TiO2 thin film based transparent flexible resistive switching random access memory

    NASA Astrophysics Data System (ADS)

    Pham, Kim Ngoc; Dung Hoang, Van; Tran, Cao Vinh; Thang Phan, Bach

    2016-03-01

    In our work we have fabricated TiO2 based resistive switching devices both on transparent substrates (ITO, IGZO/glass) and transparent flexible substrate (ITO/PET). All devices demonstrate the reproducibility of forming free bipolar resistive switching with high transparency in the visible light range (∼80% at the wavelength of 550 nm). Particularly, transparent and flexible device exhibits stable resistive switching performance at the initial state (flat) and even after bending state up to 500 times with curvature radius of 10% compared to flat state. The achieved characteristics of resistive switching of TiO2 thin films seem to be promising for transparent flexible random access memory.

  10. AquaUsers: Improving access to remotely sensed data for non-specialists

    NASA Astrophysics Data System (ADS)

    Clements, Oliver; Walker, Peter; Calton, Ben; Miller, Peter

    2015-04-01

    In recent years more and more complex remotely sensed data have been made available to the public by national and international agencies. These data are also reprocessed by different organisations to produce secondary products that are of specific need to a community. For instance the production of chlorophyll concentration maps from ocean colour data provided by NASA for the marine community. Providing access to such data has normally been focused on simply making the data available with appropriate metadata so that domain specialists can make use of it. One area that has seen significant investment, both of time and money, has been in the production of web based data portals. Primarily these have focused on spatial data. By providing a web map visualisation users are able to quickly assess both spatial coverage and data values. Data portal improvements have been possible thanks to advancements in back end data servers such as Thredds and ncWMS as well as improvements in front-end libraries for data visualisation including OpenLayers and D3. Data portals that make use of these technological advancements have aimed at improving the access and use of data by trained scientific domain specialists. There is now a push to improve access to these systems by non-scientific domain specialists through several European Commission funded projects, including OPEC and AquaUsers. These projects have improved upon an open source web GIS portal created by Plymouth Marine Laboratory [https://github.com/pmlrsg/GISportal]. We will present the latest version of our GIS portal, discuss the designs steps taken to achieve the latest build and share user stories as to how non-domain specialists are now able to utilise the system and get benefits from remotely sensed data. A first version was produced and disseminated to end users for feedback. At this stage the end users included government advisors, fish farmers and scientific groups with no specific GIS training or knowledge. This

  11. Development of Nereid-UI: A Remotely Operated Underwater Vehicle for Oceanographic Access Under Ice

    NASA Astrophysics Data System (ADS)

    Whitcomb, L. L.; Bowen, A.; Yoerger, D. R.; German, C. R.; Kinsey, J. C.; Mayer, L. A.; Jakuba, M.; Gomez-Ibanez, D.; Taylor, C. L.; Machado, C.; Howland, J. C.; Kaiser, C. L.; Heintz, M.

    2012-12-01

    The Woods Hole Oceanographic Institution and collaborators from the Johns Hopkins University and the University of New Hampshire are developing a remotely-controlled underwater robotic vehicle to provide the Polar Research Community with a capability to be tele-operated under ice under direct real-time human supervision. The Nereid Under-Ice (Nereid-UI) vehicle, Figure 1, will enable exploration and detailed examination of biological and physical environments at glacial ice-tongues and ice-shelf margins through the use of HD video in addition to acoustic, chemical, and biological sensors, Table 1. We anticipate propulsion system optimization that will enable us to attain distances up to 20 km from an ice-edge boundary, as dictated by the current maximum tether length. The goal of the Nereid-UI system is to provide scientific access to under-ice and ice-margin environments that is presently impractical or infeasible. The project design phase is underway, with incremental field testing planned in 2014. We welcome input from the Polar Science Community on how best to serve your scientific objectives. The Nereid-UI vehicle will employ technology developed during the Nereus HROV project including lightweight expendable tethers and tolerance of communications failures. Performance goals include: 1. Extreme horizontal and vertical mobility - access to under-ice crevasses and glacier grounding- lines, close inspection and mapping. 2. Real-time exploration under direct human control. 3. Response to features of interest by altering sensing modality and trajectory as desired 4. Access to the calving front 5. Access to the under-ice boundary layer 6. Future manipulation, sample retrieval, and instrument emplacement capability Supported by NSF OPP under ANT-1126311, James Family Foundation, George Frederick Jewett Foundation East, and the Woods Hole Oceanographic Institution Fig. 1: Nereid-UI Concept of Operations. Table 1: Nereid-UI Specifications;

  12. Positive alcohol expectancies and drinking behavior: the influence of expectancy strength and memory accessibility.

    PubMed

    Palfai, T; Wood, M D

    2001-03-01

    College student drinkers (N = 314) participated in a health survey in which they (a) completed an alcohol-related memory association task (expectancy accessibility measure), (b) rated their positive expectancies about alcohol use (expectancy strength measure), and (c) reported their level of alcohol involvement. Hierarchical regression analyses showed that both expectancy accessibility and expectancy strength predicted frequency of alcohol use and alcohol-related problems. Moreover, moderational analyses showed that the association between expectancy strength and frequency of alcohol use was greater for those who generated more alcohol responses on the expectancy association task. These findings suggest that the outcome association measure and Likert scale ratings of expectancies may assess distinct properties of expectancy representations, which may have independent and interactive effects on different aspects of drinking behavior. PMID:11255940

  13. Economic Insights into Providing Access to Improved Groundwater Sources in Remote, Low-Resource Areas

    NASA Astrophysics Data System (ADS)

    Abramson, A.; Lazarovitch, N.; Adar, E.

    2013-12-01

    Groundwater is often the most or only feasible drinking water source in remote, low-resource areas. Yet the economics of its development have not been systematically outlined. We applied CBARWI (Cost-Benefit Analysis for Remote Water Improvements), a recently developed Decision Support System, to investigate the economic, physical and management factors related to the costs and benefits of non-networked groundwater supply in remote areas. Synthetic profiles of community water services (n = 17,962), defined across 14 parameters' values and ranges relevant to remote areas, were imputed into the decision framework, and the parameter effects on economic outcomes were investigated through regression analysis (Table 1). Several approaches were included for financing the improvements, after Abramson et al, 2011: willingness-to -pay (WTP), -borrow (WTB) and -work (WTW) in community irrigation (';water-for-work'). We found that low-cost groundwater development approaches are almost 7 times more cost-effective than conventional boreholes fitted with handpumps. The costs of electric, submersible borehole pumps are comparable only when providing expanded water supplies, and off-grid communities pay significantly more for such expansions. In our model, new source construction is less cost-effective than improvement of existing wells, but necessary for expanding access to isolated households. The financing approach significantly impacts the feasibility of demand-driven cost recovery; in our investigation, benefit exceeds cost in 16, 32 and 48% of water service configurations financed by WTP, WTB and WTW, respectively. Regressions of total cost (R2 = 0.723) and net benefit under WTW (R2 = 0.829) along with analysis of output distributions indicate that parameters determining the profitability of irrigation are different from those determining costs and other measures of net benefit. These findings suggest that the cost-benefit outcomes associated with groundwater-based water

  14. Temperature dependence of resistive switching behaviors in resistive random access memory based on graphene oxide film

    NASA Astrophysics Data System (ADS)

    Yi, Mingdong; Cao, Yong; Ling, Haifeng; Du, Zhuzhu; Wang, Laiyuan; Yang, Tao; Fan, Quli; Xie, Linghai; Huang, Wei

    2014-05-01

    We reported resistive switching behaviors in the resistive random access memory (RRAM) devices based on the different annealing temperatures of graphene oxide (GO) film as active layers. It was found that the resistive switching characteristics of an indium tin oxide (ITO)/GO/Ag structure have a strong dependence on the annealing temperature of GO film. When the annealing temperature of the GO film was 20 °C, the devices showed typical write-once-read-many-times (WORM) type memory behaviors, which have good memory performance with a higher ON/OFF current ratio (˜104), the higher the high resistance state (HRS)/low resistance state (LRS) ratio (˜105) and stable retention characteristics (>103 s) under lower programming voltage (-1 V and -0.5 V). With the increasing annealing temperature of GO film, the resistive switching behavior of RRAM devices gradually weakened and eventually disappeared. This phenomenon could be understood by the different energy level distributions of the charge traps in GO film, and the different charge injection ability from the Ag electrode to GO film, which is caused by the different annealing temperatures of the GO film.

  15. Temperature dependence of resistive switching behaviors in resistive random access memory based on graphene oxide film.

    PubMed

    Yi, Mingdong; Cao, Yong; Ling, Haifeng; Du, Zhuzhu; Wang, Laiyuan; Yang, Tao; Fan, Quli; Xie, Linghai; Huang, Wei

    2014-05-01

    We reported resistive switching behaviors in the resistive random access memory (RRAM) devices based on the different annealing temperatures of graphene oxide (GO) film as active layers. It was found that the resistive switching characteristics of an indium tin oxide (ITO)/GO/Ag structure have a strong dependence on the annealing temperature of GO film. When the annealing temperature of the GO film was 20 °C, the devices showed typical write-once-read-many-times (WORM) type memory behaviors, which have good memory performance with a higher ON/OFF current ratio (∼10(4)), the higher the high resistance state (HRS)/low resistance state (LRS) ratio (∼10(5)) and stable retention characteristics (>10(3) s) under lower programming voltage (-1 V and -0.5 V). With the increasing annealing temperature of GO film, the resistive switching behavior of RRAM devices gradually weakened and eventually disappeared. This phenomenon could be understood by the different energy level distributions of the charge traps in GO film, and the different charge injection ability from the Ag electrode to GO film, which is caused by the different annealing temperatures of the GO film. PMID:24739543

  16. Access to artemisinin combination therapy for malaria in remote areas of Cambodia

    PubMed Central

    Yeung, Shunmay; Van Damme, Wim; Socheat, Doung; White, Nicholas J; Mills, Anne

    2008-01-01

    Background Malaria-endemic countries are switching antimalarial drug policy to artemisinin combination therapies (ACTs) and the global community are considering the setting up of a global subsidy mechanism in order to make them accessible and affordable. However, specific interventions may be needed to reach remote at-risk communities and to ensure that they are used appropriately. This analysis documents the coverage with ACTs versus artemisinin monotherapies, and the effectiveness of malaria outreach teams (MOTs) and Village Malaria Workers (VMWs) in increasing access to appropriate diagnosis and treatment with ACTs in Cambodia, the first country to switch national antimalarial drug policy to an ACT of artesunate and mefloquine (A+M) in 2000. Methods A cross-sectional survey was carried out in three different types of intervention area: with VMWs, MOTs and no specific interventions. Individuals with a history of fever in the last three weeks were included in the study and completed a questionnaire on their treatment seeking and drug usage behaviour. Blood was taken for a rapid diagnostic test (RDT) and data on the household socio-economic status were also obtained. Results In areas without specific interventions, only 17% (42/251) of respondents received a biological diagnosis, 8% (17/206) of respondents who received modern drug did so from a public health facility, and only 8% of them (17/210) received A+M. Worryingly, 78% (102/131) of all artemisinin use in these areas was as a monotherapy. However, both the VMW scheme and MOT scheme significantly increased the likelihood of being seen by a trained provider (Adjusted Odds Ratios (AOR) of 148 and 4 respectively) and of receiving A+M (AORs of 2.7 and 7.7 respectively). Conclusion The coverage rates of appropriate diagnosis and treatment of malaria were disappointingly low and the use of artemisinin monotherapy alarmingly high. This reflects the fragmented nature of Cambodia's health system in remote areas and the

  17. Chronic Disease Patients’ Experiences With Accessing Health Care in Rural and Remote Areas

    PubMed Central

    Brundisini, F; Giacomini, M; DeJean, D; Vanstone, M; Winsor, S; Smith, A

    2013-01-01

    Background Rurality can contribute to the vulnerability of people with chronic diseases. Qualitative research can identify a wide range of health care access issues faced by patients living in a remote or rural setting. Objective To systematically review and synthesize qualitative research on the advantages and disadvantages rural patients with chronic diseases face when accessing both rural and distant care. Data Sources This report synthesizes 12 primary qualitative studies on the topic of access to health care for rural patients with chronic disease. Included studies were published between 2002 and 2012 and followed adult patients in North America, Europe, Australia, and New Zealand. Review Methods Qualitative meta-synthesis was used to integrate findings across primary research studies. Results Three major themes were identified: geography, availability of health care professionals, and rural culture. First, geographic distance from services poses access barriers, worsened by transportation problems or weather conditions. Community supports and rurally located services can help overcome these challenges. Second, the limited availability of health care professionals (coupled with low education or lack of peer support) increases the feeling of vulnerability. When care is available locally, patients appreciate long-term relationships with individual clinicians and care personalized by familiarity with the patient as a person. Finally, patients may feel culturally marginalized in the urban health care context, especially if health literacy is low. A culture of self-reliance and community belonging in rural areas may incline patients to do without distant care and may mitigate feelings of vulnerability. Limitations Qualitative research findings are not intended to generalize directly to populations, although meta-synthesis across a number of qualitative studies builds an increasingly robust understanding that is more likely to be transferable. Selected studies

  18. Increasing access to terrestrial ecology and remote sensing (MODIS) data through Web services and visualization tools

    NASA Astrophysics Data System (ADS)

    Santhana Vannan, S.; Cook, R. B.; Wei, Y.

    2012-12-01

    In recent years user access to data and information is increasingly handled through tools, services, and applications. Standards-based services have facilitated this development. These service-based methods to access data has boosted the use of data and in increasingly complex ways. The Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) has taken the approach of service-based access to data and visualization for distribution and visualization of its terrestrial ecology data, including MODIS (Moderate Resolution Imaging Spectroradiometer) remote sensing data products. The MODIS data products are highly useful for field research. The spectral, spatial and temporal characteristics of MODIS products have made them an important data source for analyzing key science questions relating to Earth system processes at multiple spatial and temporal scales. However, MODIS data volume and the complexity in data format make it less usable in some cases. To solve this usability issue, the ORNL DAAC has developed a system that prepares and distributes subsets of selected MODIS land products in a scale and format useful for field researchers. Web and Web service tools provide MODIS subsets in comma-delimited text format and in GIS compatible GeoTIFF format. Users can download and visualize MODIS subsets for a set of pre-defined locations, order MODIS subsets for any land location or automate the process of subset extraction using a SOAP-based Web service. The MODIS tools and services can be extended to support the large volume of data that would be produced by the various decadal survey missions. http://daac.ornl.gov/MODIS . The ORNL DAAC has also created a Web-based Spatial Data Access Tool (SDAT) that enables users to browse, visualize, and download a wide variety of geospatial data in various user-selected spatial/temporal extents, formats, and projections. SDAT is based on Open Geospatial Consortium (OGC) Web service standards that allows users to

  19. On-Line Remote Catalog Access and Circulation Control System. Part I: Functional Specifications. Part II: User's Manual.

    ERIC Educational Resources Information Center

    International Business Machines Corp., Gaithersburg, MD. Data Processing Div.

    The Ohio State University Libraries On-line Remote Catalog Access and Circulation Control System (LCS) began on-line operations with the conversion of one department library in November 1970. By December all 26 libraries had been converted to the automated system and LCS was fully operational one month ahead of schedule. LCS is designed as a…

  20. Assessing the Engagement, Learning, and Overall Experience of Students Operating an Atomic Absorption Spectrophotometer with Remote Access Technology

    ERIC Educational Resources Information Center

    Erasmus, Daniel J.; Brewer, Sharon E.; Cinel, Bruno

    2015-01-01

    The use of internet-based technologies in the teaching of laboratories has emerged as a promising education tool. This study evaluated the effectiveness of using remote access technology to operate an atomic absorption spectrophotometer in analyzing the iron content in a crude myoglobin extract. Sixty-two students were surveyed on their level of…

  1. Low power switching of Si-doped Ta2O5 resistive random access memory for high density memory application

    NASA Astrophysics Data System (ADS)

    Kim, Beom Yong; Jeung Lee, Kee; Ock Chung, Su; Gil Kim, Soo; Ko, Young Seok; Kim, Hyeong Soo

    2016-04-01

    We report, for the first time, the resistive switching properties of Si-doped Ta2O5 grown by atomic layer deposition (ALD). The reduced switching current, improved on/off current ratio, and excellent endurance property are demonstrated in the Si-doped Ta2O5 resistive random access memory (ReRAM) devices of 50 nm tech node. The switching mechanism for the Si-doped Ta2O5 resistor is discussed. Si dopants enable switching layer to have conformal distribution of oxygen vacancy and easily form conductive filament. This leads to higher on/off current ratio at even low operation current of 5-10 µA. Finally, one selector-one resistor (1S1R) ReRAM was developed for large cell array application. For the optimized 1S1R stack, 0.2 µA of off current and 5.0 of on/off current ratio were successfully achieved at 10 µA of low operation current.

  2. Synergistic effects of total ionizing dose on single event upset sensitivity in static random access memory under proton irradiation

    NASA Astrophysics Data System (ADS)

    Xiao, Yao; Guo, Hong-Xia; Zhang, Feng-Qi; Zhao, Wen; Wang, Yan-Ping; Zhang, Ke-Ying; Ding, Li-Li; Fan, Xue; Luo, Yin-Hong; Wang, Yuan-Ming

    2014-11-01

    Synergistic effects of the total ionizing dose (TID) on the single event upset (SEU) sensitivity in static random access memories (SRAMs) were studied by using protons. The total dose was cumulated with high flux protons during the TID exposure, and the SEU cross section was tested with low flux protons at several cumulated dose steps. Because of the radiation-induced off-state leakage current increase of the CMOS transistors, the noise margin became asymmetric and the memory imprint effect was observed.

  3. Daily access to sucrose impairs aspects of spatial memory tasks reliant on pattern separation and neural proliferation in rats.

    PubMed

    Reichelt, Amy C; Morris, Margaret J; Westbrook, Reginald Frederick

    2016-07-01

    High sugar diets reduce hippocampal neurogenesis, which is required for minimizing interference between memories, a process that involves "pattern separation." We provided rats with 2 h daily access to a sucrose solution for 28 d and assessed their performance on a spatial memory task. Sucrose consuming rats discriminated between objects in novel and familiar locations when there was a large spatial separation between the objects, but not when the separation was smaller. Neuroproliferation markers in the dentate gyrus of the sucrose-consuming rats were reduced relative to controls. Thus, sucrose consumption impaired aspects of spatial memory and reduced hippocampal neuroproliferation. PMID:27317199

  4. Subthreshold-swing-adjustable tunneling-field-effect-transistor-based random-access memory for nonvolatile operation

    NASA Astrophysics Data System (ADS)

    Huh, In; Cheon, Woo Young; Choi, Woo Young

    2016-04-01

    A subthreshold-swing-adjustable tunneling-field-effect-transistor-based random-access memory (SAT RAM) has been proposed and fabricated for low-power nonvolatile memory applications. The proposed SAT RAM cell demonstrates adjustable subthreshold swing (SS) depending on stored information: small SS in the erase state ("1" state) and large SS in the program state ("0" state). Thus, SAT RAM cells can achieve low read voltage (Vread) with a large memory window in addition to the effective suppression of ambipolar behavior. These unique features of the SAT RAM are originated from the locally stored charge, which modulates the tunneling barrier width (Wtun) of the source-to-channel tunneling junction.

  5. Dual operation characteristics of resistance random access memory in indium-gallium-zinc-oxide thin film transistors

    SciTech Connect

    Yang, Jyun-Bao; Chen, Yu-Ting; Chu, Ann-Kuo; Chang, Ting-Chang; Huang, Jheng-Jie; Chen, Yu-Chun; Tseng, Hsueh-Chih; Sze, Simon M.

    2014-04-14

    In this study, indium-gallium-zinc-oxide thin film transistors can be operated either as transistors or resistance random access memory devices. Before the forming process, current-voltage curve transfer characteristics are observed, and resistance switching characteristics are measured after a forming process. These resistance switching characteristics exhibit two behaviors, and are dominated by different mechanisms. The mode 1 resistance switching behavior is due to oxygen vacancies, while mode 2 is dominated by the formation of an oxygen-rich layer. Furthermore, an easy approach is proposed to reduce power consumption when using these resistance random access memory devices with the amorphous indium-gallium-zinc-oxide thin film transistor.

  6. Data Access Services that Make Remote Sensing Data Easier to Use

    NASA Technical Reports Server (NTRS)

    Lynnes, Christopher

    2010-01-01

    This slide presentation reviews some of the processes that NASA uses to make the remote sensing data easy to use over the World Wide Web. This work involves much research into data formats, geolocation structures and quality indicators, often to be followed by coding a preprocessing program. Only then are the data usable within the analysis tool of choice. The Goddard Earth Sciences Data and Information Services Center is deploying a variety of data access services that are designed to dramatically shorten the time consumed in the data preparation step. On-the-fly conversion to the standard network Common Data Form (netCDF) format with Climate-Forecast (CF) conventions imposes a standard coordinate system framework that makes data instantly readable through several tools, such as the Integrated Data Viewer, Gridded Analysis and Display System, Panoply and Ferret. A similar benefit is achieved by serving data through the Open Source Project for a Network Data Access Protocol (OPeNDAP), which also provides subsetting. The Data Quality Screening Service goes a step further in filtering out data points based on quality control flags, based on science team recommendations or user-specified criteria. Further still is the Giovanni online analysis system which goes beyond handling formatting and quality to provide visualization and basic statistics of the data. This general approach of automating the preparation steps has the important added benefit of enabling use of the data by non-human users (i.e., computer programs), which often make sub-optimal use of the available data due to the need to hard-code data preparation on the client side.

  7. Data Access Services that Make Remote Sensing Data Easier to Use (Invited)

    NASA Astrophysics Data System (ADS)

    Lynnes, C.

    2010-12-01

    The tall pole for exploiting remote sensing data is often preparing data for use. Typically, this involves much research into data formats, geolocation structures and quality indicators, often to be followed by coding a preprocessing program. Only then are the data usable within the analysis tool of choice. The Goddard Earth Sciences Data and Information Services Center is deploying a variety of data access services that are designed to dramatically shorten the time consumed in the data preparation step. On-the-fly conversion to the standard network Common Data Form (netCDF) format with Climate-Forecast (CF) conventions imposes a standard coordinate system framework that makes data instantly readable through several tools, such as the Integrated Data Viewer, Gridded Analysis and Display System, Panoply and Ferret. A similar benefit is achieved by serving data through the Open Source Project for a Network Data Access Protocol (OPeNDAP), which also provides subsetting. The Data Quality Screening Service goes a step further in filtering out data points based on quality control flags, based on science team recommendations or user-specified criteria. Further still is the Giovanni online analysis system which goes beyond handling formatting and quality to provide visualization and basic statistics of the data. This general approach of automating the preparation steps has the important added benefit of enabling use of the data by non-human users (i.e., computer programs), which often make sub-optimal use of the available data due to the need to hard-code data preparation on the client side.

  8. Enhancing Access to Land Remote Sensing Data through Mainstream Social Media Channels

    NASA Astrophysics Data System (ADS)

    Sohre, T.; Maiersperger, T.

    2011-12-01

    Social media tools are changing the way that people discover information, communicate, and collaborate. Government agencies supporting the Land Remote Sensing user community have begun taking advantage of standard social media tools and capabilities. National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) data centers have started providing outreach utilizing services including Facebook, Twitter, and YouTube videos. Really Simple Syndication (RSS) Feeds have become more standard means of sharing information, and a DataCasting tool was created as a NASA Technology Infusion effort to make RSS-based technology for accessing Earth Science information available. The United States Geological Survey (USGS) has also started using social media to allow the community access to news feeds and real-time earthquake alerts; listen to podcasts; get updates on new USGS publications, videos, and photographs; and more. Twitter feeds have been implemented in 2011 for the USGS Land Cover and Landsat user communities. In early 2011, the NASA Land Processes Distributed Active Archive Center (LP DAAC) user working group suggested the investigation of concepts for creating and distributing "bundles" of data, which would aggregate theme-based data sets from multiple sources. The LP DAAC is planning to explore the use of standard social bookmarking tools to support community developed bundles through the use of tools such as Delicious, Digg, or StumbleUpon. This concept would allow science users to organize and discover common links to data resources based on community developed tags, or a folksonomy. There are challenges that will need to be addressed such as maintaining the quality of tags but a social bookmarking system may have advantages over traditional search engines or formal ontologies for identifying and labeling various data sets relevant to a theme. As classification is done by the community of scientists who understand the data, the tagged data sets

  9. False Operation of Static Random Access Memory Cells under Alternating Current Power Supply Voltage Variation

    NASA Astrophysics Data System (ADS)

    Sawada, Takuya; Takata, Hidehiro; Nii, Koji; Nagata, Makoto

    2013-04-01

    Static random access memory (SRAM) cores exhibit susceptibility against power supply voltage variation. False operation is investigated among SRAM cells under sinusoidal voltage variation on power lines introduced by direct RF power injection. A standard SRAM core of 16 kbyte in a 90 nm 1.5 V technology is diagnosed with built-in self test and on-die noise monitor techniques. The sensitivity of bit error rate is shown to be high against the frequency of injected voltage variation, while it is not greatly influenced by the difference in frequency and phase against SRAM clocking. It is also observed that the distribution of false bits is substantially random in a cell array.

  10. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current

    PubMed Central

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J.; Jiang, Yong

    2015-01-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excellent switching features which are originated in the formation of Cu filaments under external voltage. Therefore it provides the possibility of reducing power consumption and accelerating the commercialization of resistive switching devices. PMID:25982101

  11. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current

    NASA Astrophysics Data System (ADS)

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J.; Jiang, Yong

    2015-05-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excellent switching features which are originated in the formation of Cu filaments under external voltage. Therefore it provides the possibility of reducing power consumption and accelerating the commercialization of resistive switching devices.

  12. Joule heating effect in nonpolar and bipolar resistive random access memory

    NASA Astrophysics Data System (ADS)

    Uenuma, Mutsunori; Ishikawa, Yasuaki; Uraoka, Yukiharu

    2015-08-01

    The position of the conductive filament (CF) and the heating behaviour during a switching process in nonpolar and bipolar resistive random access memories (ReRAMs) were evaluated using thermal analysis. The position of the CF was clearly observed from Joule heating at the surface of the electrode on the CF. The position of the CF did not change during the switching cycle, except in the case of an unstable CF. In the nonpolar ReRAM, spike-shaped temperature increments were observed during both the forming and the set processes because of the overshoot current. However, the behaviour of the temperature increment in the bipolar ReRAM was virtually consistent with the profile of the electrical power.

  13. Simulation study on heat conduction of a nanoscale phase-change random access memory cell.

    PubMed

    Kim, Junho; Song, Ki-Bong

    2006-11-01

    We have investigated heat transfer characteristics of a nano-scale phase-change random access memory (PRAM) cell using finite element method (FEM) simulation. Our PRAM cell is based on ternary chalcogenide alloy, Ge2Sb2Te5 (GST), which is used as a recording layer. For contact area of 100 x 100 nm2, simulations of crystallization and amorphization processes were carried out. Physical quantities such as electric conductivity, thermal conductivity, and specific heat were treated as temperature-dependent parameters. Through many simulations, it is concluded that one can reduce set current by decreasing both electric conductivities of amorphous GST and crystalline GST, and in addition to these conditions by decreasing electric conductivity of molten GST one can also reduce reset current significantly. PMID:17252792

  14. Characteristics and mechanism study of cerium oxide based random access memories

    SciTech Connect

    Hsieh, Cheng-Chih; Roy, Anupam; Rai, Amritesh; Chang, Yao-Feng; Banerjee, Sanjay K.

    2015-04-27

    In this work, low operating voltage and high resistance ratio of different resistance states of binary transition metal oxide based resistive random access memories (RRAMs) are demonstrated. Binary transition metal oxides with high dielectric constant have been explored for RRAM application for years. However, CeO{sub x} is considered as a relatively new material to other dielectrics. Since research on CeO{sub x} based RRAM is still at preliminary stage, fundamental characteristics of RRAM such as scalability and mechanism studies need to be done before moving further. Here, we show very high operation window and low switching voltage of CeO{sub x} RRAMs and also compare electrical performance of Al/CeO{sub x}/Au system between different thin film deposition methods and discuss characteristics and resistive switching mechanism.

  15. Novel Capacitor Structure Using Sidewall Spacer for Highly Reliable Ferroelectric Random Access Memory Device

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-Ho; Park, Jung-Hoon; Song, Yoon-Jong; Jang, Nak-Won; Joo, Heung-Jin; Kang, Seung-Kuk; Joo, Seok-Ho; Lee, Sung-Young; Kim, Kinam

    2004-04-01

    Since ferroelectric capacitors prepared by 1-mask etching are degraded after the etching, we systematically investigated the origin of the degradation. It was found that the major degradation originates from the formation of the nonstoichiometric and amorphorized Pb(ZrxTi1-x)O3 (PZT) layer on the sidewall of the PZT film during etching of the bottom electrode (BE). Therefore, to eliminate the undesired etch-damaged layer, we developed a novel etching technology using a ferroelectric (FE) sidewall spacer, which results in the enhancement of the remnant polarization after completing the capacitor etching process. Using the novel FE sidewall spacer, the sensing margin of bit-line-developed voltage was improved to 400 mV, which can guarantee highy reliable high-density ferroelectric random access memory (FRAM) devices.

  16. Electrical Characterization of the RCA CDP1822SD Random Access Memory, Volume 1, Appendix a

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    Electrical characteristization tests were performed on 35 RCA CDP1822SD, 256-by-4-bit, CMOS, random access memories. The tests included three functional tests, AC and DC parametric tests, a series of schmoo plots, rise/fall time screening, and a data retention test. All tests were performed on an automated IC test system with temperatures controlled by a thermal airstream unit. All the functional tests, the data retention test, and the AC and DC parametric tests were performed at ambient temperatures of 25 C, -20 C, -55 C, 85 C, and 125 C. The schmoo plots were performed at ambient temperatures of 25 C, -55 C, and 125 C. The data retention test was performed at 25 C. Five devices failed one or more functional tests and four of these devices failed to meet the expected limits of a number of AC parametric tests. Some of the schmoo plots indicated a small degree of interaction between parameters.

  17. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    NASA Astrophysics Data System (ADS)

    Khan, Asif; Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-06-01

    A spintronic device, called the "strain assisted spin transfer torque (STT) random access memory (RAM)," is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  18. Microstructural transitions in resistive random access memory composed of molybdenum oxide with copper during switching cycles.

    PubMed

    Arita, Masashi; Ohno, Yuuki; Murakami, Yosuke; Takamizawa, Keisuke; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

    2016-08-21

    The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process. PMID:27456192

  19. New Approach on Logic Application of Ferroelectric Random Access Memory Technology

    NASA Astrophysics Data System (ADS)

    Takayama, Masao; Koyama, Shinzo; Nozawa, Hiroshi

    2002-11-01

    In this paper, a new approach is described to solve some problems that occur when ferroelectric random access memory (FeRAM) is applied to logic circuits, particularly RSA cryptography. Application of a programmable switch device to RSA-based cryptography processing circuits was explored. RSA-based cryptography processing circuits have been designed as code conversion circuits. The capacity of the code conversion programmable AND gate and FeRAM and the translation rate have been investigated as a function of bit length. As a result, a problem of huge capacity at the practical bit length can be predicted theoretically. To solve this problem, we propose a new scheme for circuits and a new algorithm of logic operation using the binomial theorem.

  20. Understanding Electrical Conduction States in WO3 Thin Films Applied for Resistive Random-Access Memory

    NASA Astrophysics Data System (ADS)

    Ta, Thi Kieu Hanh; Pham, Kim Ngoc; Dao, Thi Bang Tam; Tran, Dai Lam; Phan, Bach Thang

    2016-05-01

    The electrical conduction and associated resistance switching mechanism of top electrode/WO3/bottom electrode devices [top electrode (TE): Ag, Ti; bottom electrode (BE): Pt, fluorine-doped tin oxide] have been investigated. The direction of switching and switching ability depended on both the top and bottom electrode material. Multiple electrical conduction mechanisms control the leakage current of such switching devices, including trap-controlled space-charge, ballistic, Ohmic, and Fowler-Nordheim tunneling effects. The transition between electrical conduction states is also linked to the switching (SET-RESET) process. This is the first report of ballistic conduction in research into resistive random-access memory. The associated resistive switching mechanisms are also discussed.

  1. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current.

    PubMed

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J; Jiang, Yong

    2015-01-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excellent switching features which are originated in the formation of Cu filaments under external voltage. Therefore it provides the possibility of reducing power consumption and accelerating the commercialization of resistive switching devices. PMID:25982101

  2. Improvement of Resistive Random Access Memory Device Performance via Embedding of Low-K Dielectric Layer.

    PubMed

    Jang, Sung Hwan; Ryu, Ju Tae; Jung, Hyun Soo; Kim, Tae Whan

    2016-02-01

    The switching mechanisms of resistive random access memories (ReRAMs) were strongly related to the formation and rupture of conduction filaments (CFs) in the transition metal oxide (TMO) layer. The novel method approached to enhance the electrical characteristics of ReRAMs by introducing of the local insertion of the low-k dielectric layer inside the TMO layer. Simulation results showed that the insertion of the low-k dielectric layer in the TMO layer reduced the switching volume and the generation of CFs. The large variation of resistive switching properties was caused by the stochastic characteristics of the CFs, which was involved in switching by generation and rupture. The electrical characteristics of the novel ReRAMs exhibited a low reset current of below 20 microA, the high uniformity of the resistive switching, and the narrow variation of the resistance for the high resistance state. PMID:27433626

  3. Atomistic study of dynamics for metallic filament growth in conductive-bridge random access memory.

    PubMed

    Qin, Shengjun; Liu, Zhan; Zhang, Guo; Zhang, Jinyu; Sun, Yaping; Wu, Huaqiang; Qian, He; Yu, Zhiping

    2015-04-14

    The growth dynamics for metallic filaments in conductive-bridge resistive-switching random access memory (CBRAM) are studied using the kinetic Monte Carlo (KMC) method. The physical process at the atomistic level is revealed in explaining the experimental observation that filament growth can originate at either the cathode or the anode. The statistical nature of the filament growth is best shown by the random topography of dendrite-like conductive paths obtained. Critical material properties, such as charged-particle mobility in the switching layer of a solid electrolyte or a dielectric, are mapped to KMC model parameters through activation energy, etc. The accuracy of the simulator is established by the good agreement between the simulated forming time and the measured data. PMID:25750983

  4. Voltage induced magnetostrictive switching of nanomagnets: Strain assisted strain transfer torque random access memory

    SciTech Connect

    Khan, Asif Nikonov, Dmitri E.; Manipatruni, Sasikanth; Ghani, Tahir; Young, Ian A.

    2014-06-30

    A spintronic device, called the “strain assisted spin transfer torque (STT) random access memory (RAM),” is proposed by combining the magnetostriction effect and the spin transfer torque effect which can result in a dramatic improvement in the energy dissipation relative to a conventional STT-RAM. Magnetization switching in the device which is a piezoelectric-ferromagnetic heterostructure via the combined magnetostriction and STT effect is simulated by solving the Landau-Lifshitz-Gilbert equation incorporating the influence of thermal noise. The simulations show that, in such a device, each of these two mechanisms (magnetostriction and spin transfer torque) provides in a 90° rotation of the magnetization leading a deterministic 180° switching with a critical current significantly smaller than that required for spin torque alone. Such a scheme is an attractive option for writing magnetic RAM cells.

  5. Conductive-bridging random access memory: challenges and opportunity for 3D architecture.

    PubMed

    Jana, Debanjan; Roy, Sourav; Panja, Rajeswar; Dutta, Mrinmoy; Rahaman, Sheikh Ziaur; Mahapatra, Rajat; Maikap, Siddheswar

    2015-01-01

    The performances of conductive-bridging random access memory (CBRAM) have been reviewed for different switching materials such as chalcogenides, oxides, and bilayers in different structures. The structure consists of an inert electrode and one oxidized electrode of copper (Cu) or silver (Ag). The switching mechanism is the formation/dissolution of a metallic filament in the switching materials under external bias. However, the growth dynamics of the metallic filament in different switching materials are still debated. All CBRAM devices are switching under an operation current of 0.1 μA to 1 mA, and an operation voltage of ±2 V is also needed. The device can reach a low current of 5 pA; however, current compliance-dependent reliability is a challenging issue. Although a chalcogenide-based material has opportunity to have better endurance as compared to an oxide-based material, data retention and integration with the complementary metal-oxide-semiconductor (CMOS) process are also issues. Devices with bilayer switching materials show better resistive switching characteristics as compared to those with a single switching layer, especially a program/erase endurance of >10(5) cycles with a high speed of few nanoseconds. Multi-level cell operation is possible, but the stability of the high resistance state is also an important reliability concern. These devices show a good data retention of >10(5) s at >85°C. However, more study is needed to achieve a 10-year guarantee of data retention for non-volatile memory application. The crossbar memory is benefited for high density with low power operation. Some CBRAM devices as a chip have been reported for proto-typical production. This review shows that operation current should be optimized for few microamperes with a maintaining speed of few nanoseconds, which will have challenges and also opportunities for three-dimensional (3D) architecture. PMID:25977660

  6. Metal oxide resistive random access memory based synaptic devices for brain-inspired computing

    NASA Astrophysics Data System (ADS)

    Gao, Bin; Kang, Jinfeng; Zhou, Zheng; Chen, Zhe; Huang, Peng; Liu, Lifeng; Liu, Xiaoyan

    2016-04-01

    The traditional Boolean computing paradigm based on the von Neumann architecture is facing great challenges for future information technology applications such as big data, the Internet of Things (IoT), and wearable devices, due to the limited processing capability issues such as binary data storage and computing, non-parallel data processing, and the buses requirement between memory units and logic units. The brain-inspired neuromorphic computing paradigm is believed to be one of the promising solutions for realizing more complex functions with a lower cost. To perform such brain-inspired computing with a low cost and low power consumption, novel devices for use as electronic synapses are needed. Metal oxide resistive random access memory (ReRAM) devices have emerged as the leading candidate for electronic synapses. This paper comprehensively addresses the recent work on the design and optimization of metal oxide ReRAM-based synaptic devices. A performance enhancement methodology and optimized operation scheme to achieve analog resistive switching and low-energy training behavior are provided. A three-dimensional vertical synapse network architecture is proposed for high-density integration and low-cost fabrication. The impacts of the ReRAM synaptic device features on the performances of neuromorphic systems are also discussed on the basis of a constructed neuromorphic visual system with a pattern recognition function. Possible solutions to achieve the high recognition accuracy and efficiency of neuromorphic systems are presented.

  7. Ultrafast switching in nanoscale phase-change random access memory with superlattice-like structures.

    PubMed

    Loke, Desmond; Shi, Luping; Wang, Weijie; Zhao, Rong; Yang, Hongxin; Ng, Lung-Tat; Lim, Kian-Guan; Chong, Tow-Chong; Yeo, Yee-Chia

    2011-06-24

    Phase-change random access memory cells with superlattice-like (SLL) GeTe/Sb(2)Te(3) were demonstrated to have excellent scaling performance in terms of switching speed and operating voltage. In this study, the correlations between the cell size, switching speed and operating voltage of the SLL cells were identified and investigated. We found that small SLL cells can achieve faster switching speed and lower operating voltage compared to the large SLL cells. Fast amorphization and crystallization of 300 ps and 1 ns were achieved in the 40 nm SLL cells, respectively, both significantly faster than those observed in the Ge(2)Sb(2)Te(5) (GST) cells of the same cell size. 40 nm SLL cells were found to switch with low amorphization voltage of 0.9 V when pulse-widths of 5 ns were employed, which is much lower than the 1.6 V required by the GST cells of the same cell size. These effects can be attributed to the fast heterogeneous crystallization, low thermal conductivity and high resistivity of the SLL structures. Nanoscale PCRAM with SLL structure promises applications in high speed and low power memory devices. PMID:21572204

  8. Does the mismatch negativity operate on a consciously accessible memory trace?

    PubMed

    Dykstra, Andrew R; Gutschalk, Alexander

    2015-11-01

    The extent to which the contents of short-term memory are consciously accessible is a fundamental question of cognitive science. In audition, short-term memory is often studied via the mismatch negativity (MMN), a change-related component of the auditory evoked response that is elicited by violations of otherwise regular stimulus sequences. The prevailing functional view of the MMN is that it operates on preattentive and even preconscious stimulus representations. We directly examined the preconscious notion of the MMN using informational masking and magnetoencephalography. Spectrally isolated and otherwise suprathreshold auditory oddball sequences were occasionally random rendered inaudible by embedding them in random multitone masker "clouds." Despite identical stimulation/task contexts and a clear representation of all stimuli in auditory cortex, MMN was only observed when the preceding regularity (that is, the standard stream) was consciously perceived. The results call into question the preconscious interpretation of MMN and raise the possibility that it might index partial awareness in the absence of overt behavior. PMID:26702432

  9. Does the mismatch negativity operate on a consciously accessible memory trace?

    PubMed Central

    Dykstra, Andrew R.; Gutschalk, Alexander

    2015-01-01

    The extent to which the contents of short-term memory are consciously accessible is a fundamental question of cognitive science. In audition, short-term memory is often studied via the mismatch negativity (MMN), a change-related component of the auditory evoked response that is elicited by violations of otherwise regular stimulus sequences. The prevailing functional view of the MMN is that it operates on preattentive and even preconscious stimulus representations. We directly examined the preconscious notion of the MMN using informational masking and magnetoencephalography. Spectrally isolated and otherwise suprathreshold auditory oddball sequences were occasionally random rendered inaudible by embedding them in random multitone masker “clouds.” Despite identical stimulation/task contexts and a clear representation of all stimuli in auditory cortex, MMN was only observed when the preceding regularity (that is, the standard stream) was consciously perceived. The results call into question the preconscious interpretation of MMN and raise the possibility that it might index partial awareness in the absence of overt behavior. PMID:26702432

  10. Influence of ultraviolet irradiation on data retention characteristics in resistive random access memory

    NASA Astrophysics Data System (ADS)

    Kimura, K.; Ohmi, K.; Kishida, S.; Kinoshita, K.

    2016-03-01

    With increasing density of memory devices, the issue of generating soft errors by cosmic rays is becoming more and more serious. Therefore, the irradiation resistance of resistance random access memory (ReRAM) to cosmic radiation has to be elucidated for practical use. In this paper, we investigated the data retention characteristics of ReRAM against ultraviolet irradiation with a Pt/NiO/ITO structure. Soft errors were confirmed to be caused by ultraviolet irradiation in both low- and high-resistance states. An analysis of the wavelength dependence of light irradiation on data retention characteristics suggested that electronic excitation from the valence to the conduction band and to the energy level generated due to the introduction of oxygen vacancies caused the errors. Based on a statistically estimated soft error rates, the errors were suggested to be caused by the cohesion and dispersion of oxygen vacancies owing to the generation of electron-hole pairs and valence changes by the ultraviolet irradiation.

  11. Microstructural transitions in resistive random access memory composed of molybdenum oxide with copper during switching cycles

    NASA Astrophysics Data System (ADS)

    Arita, Masashi; Ohno, Yuuki; Murakami, Yosuke; Takamizawa, Keisuke; Tsurumaki-Fukuchi, Atsushi; Takahashi, Yasuo

    2016-08-01

    The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process.The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02602h

  12. Context controls access to working and reference memory in the pigeon (Columba livia).

    PubMed

    Roberts, William A; Macpherson, Krista; Strang, Caroline

    2016-01-01

    The interaction between working and reference memory systems was examined under conditions in which salient contextual cues were presented during memory retrieval. Ambient colored lights (red or green) bathed the operant chamber during the presentation of comparison stimuli in delayed matching-to-sample training (working memory) and during the presentation of the comparison stimuli as S+ and S- cues in discrimination training (reference memory). Strong competition between memory systems appeared when the same contextual cue appeared during working and reference memory training. When different contextual cues were used, however, working memory was completely protected from reference memory interference. PMID:26781056

  13. Remote information service access system based on a client-server-service model

    DOEpatents

    Konrad, Allan M.

    1999-01-01

    A local host computing system, a remote host computing system as connected by a network, and service functionalities: a human interface service functionality, a starter service functionality, and a desired utility service functionality, and a Client-Server-Service (CSS) model is imposed on each service functionality. In one embodiment, this results in nine logical components and three physical components (a local host, a remote host, and an intervening network), where two of the logical components are integrated into one Remote Object Client component, and that Remote Object Client component and the other seven logical components are deployed among the local host and remote host in a manner which eases compatibility and upgrade problems, and provides an illusion to a user that a desired utility service supported on a remote host resides locally on the user's local host, thereby providing ease of use and minimal software maintenance for users of that remote service.

  14. Remote information service access system based on a client-server-service model

    DOEpatents

    Konrad, A.M.

    1997-12-09

    A local host computing system, a remote host computing system as connected by a network, and service functionalities: a human interface service functionality, a starter service functionality, and a desired utility service functionality, and a Client-Server-Service (CSS) model is imposed on each service functionality. In one embodiment, this results in nine logical components and three physical components (a local host, a remote host, and an intervening network), where two of the logical components are integrated into one Remote Object Client component, and that Remote Object Client component and the other seven logical components are deployed among the local host and remote host in a manner which eases compatibility and upgrade problems, and provides an illusion to a user that a desired utility service supported on a remote host resides locally on the user`s local host, thereby providing ease of use and minimal software maintenance for users of that remote service. 16 figs.

  15. Remote information service access system based on a client-server-service model

    DOEpatents

    Konrad, Allan M.

    1997-01-01

    A local host computing system, a remote host computing system as connected by a network, and service functionalities: a human interface service functionality, a starter service functionality, and a desired utility service functionality, and a Client-Server-Service (CSS) model is imposed on each service functionality. In one embodiment, this results in nine logical components and three physical components (a local host, a remote host, and an intervening network), where two of the logical components are integrated into one Remote Object Client component, and that Remote Object Client component and the other seven logical components are deployed among the local host and remote host in a manner which eases compatibility and upgrade problems, and provides an illusion to a user that a desired utility service supported on a remote host resides locally on the user's local host, thereby providing ease of use and minimal software maintenance for users of that remote service.

  16. Remote information service access system based on a client-server-service model

    DOEpatents

    Konrad, Allan M.

    1996-01-01

    A local host computing system, a remote host computing system as connected by a network, and service functionalities: a human interface service functionality, a starter service functionality, and a desired utility service functionality, and a Client-Server-Service (CSS) model is imposed on each service functionality. In one embodiment, this results in nine logical components and three physical components (a local host, a remote host, and an intervening network), where two of the logical components are integrated into one Remote Object Client component, and that Remote Object Client component and the other seven logical components are deployed among the local host and remote host in a manner which eases compatibility and upgrade problems, and provides an illusion to a user that a desired utility service supported on a remote host resides locally on the user's local host, thereby providing ease of use and minimal software maintenance for users of that remote service.

  17. Remote information service access system based on a client-server-service model

    DOEpatents

    Konrad, A.M.

    1996-08-06

    A local host computing system, a remote host computing system as connected by a network, and service functionalities: a human interface service functionality, a starter service functionality, and a desired utility service functionality, and a Client-Server-Service (CSS) model is imposed on each service functionality. In one embodiment, this results in nine logical components and three physical components (a local host, a remote host, and an intervening network), where two of the logical components are integrated into one Remote Object Client component, and that Remote Object Client component and the other seven logical components are deployed among the local host and remote host in a manner which eases compatibility and upgrade problems, and provides an illusion to a user that a desired utility service supported on a remote host resides locally on the user`s local host, thereby providing ease of use and minimal software maintenance for users of that remote service. 16 figs.

  18. Memory.

    ERIC Educational Resources Information Center

    McKean, Kevin

    1983-01-01

    Discusses current research (including that involving amnesiacs and snails) into the nature of the memory process, differentiating between and providing examples of "fact" memory and "skill" memory. Suggests that three brain parts (thalamus, fornix, mammilary body) are involved in the memory process. (JN)

  19. Evaluation of Data Retention Characteristics for Ferroelectric Random Access Memories (FRAMs)

    NASA Technical Reports Server (NTRS)

    Sharma, Ashok K.; Teverovsky, Alexander

    2001-01-01

    Data retention and fatigue characteristics of 64 Kb lead zirconate titanate (PZT)-based Ferroelectric Random Access Memories (FRAMs) microcircuits manufactured by Ramtron were examined over temperature range from -85 C to +310 C for ceramic packaged parts and from -85 C to +175 C for plastic parts, during retention periods up to several thousand hours. Intrinsic failures, which were caused by a thermal degradation of the ferroelectric cells, occurred in ceramic parts after tens or hundreds hours of aging at temperatures above 200 C. The activation energy of the retention test failures was 1.05 eV and the extrapolated mean-time-to-failure (MTTF) at room temperature was estimated to be more than 280 years. Multiple write-read cycling (up to 3x10(exp 7)) during the fatigue testing of plastic and ceramic parts did not result in any parametric or functional failures. However, operational currents linearly decreased with the logarithm of number of cycles thus indicating fatigue process in PZT films. Plastic parts, that had more recent date code as compared to ceramic parts, appeared to be using die with improved process technology and showed significantly smaller changes in operational currents and data access times.

  20. Short-term calorie restriction enhances adult hippocampal neurogenesis and remote fear memory in a Ghsr-dependent manner

    PubMed Central

    Hornsby, Amanda K.E.; Redhead, Yushi T.; Rees, Daniel J.; Ratcliff, Michael S.G.; Reichenbach, Alex; Wells, Timothy; Francis, Lewis; Amstalden, Katia; Andrews, Zane B.; Davies, Jeffrey S.

    2016-01-01

    The beneficial effects of calorie restriction (CR) have been described at both organismal and cellular levels in multiple organs. However, our understanding of the causal mediators of such hormesis is poorly understood, particularly in the context of higher brain function. Here, we show that the receptor for the orexigenic hormone acyl-ghrelin, the growth hormone secretagogue receptor (Ghsr), is enriched in the neurogenic niche of the hippocampal dentate gyrus (DG). Acute elevation of acyl-ghrelin levels by injection or by overnight CR, increased DG levels of the neurogenic transcription factor, Egr-1. Two weeks of CR increased the subsequent number of mature newborn neurons in the DG of adult wild-type but not Ghsr−/− mice. CR wild-type mice also showed improved remote contextual fear memory. Our findings suggest that Ghsr mediates the beneficial effects of CR on enhancing adult hippocampal neurogenesis and memory. PMID:26460782

  1. Three-Year-Old Children Can Access Their Own Memory to Guide Responses on a Visual Matching Task

    ERIC Educational Resources Information Center

    Balcomb, Frances K.; Gerken, LouAnn

    2008-01-01

    Many models of learning rely on accessing internal knowledge states. Yet, although infants and young children are recognized to be proficient learners, the ability to act on metacognitive information is not thought to develop until early school years. In the experiments reported here, 3.5-year-olds demonstrated memory-monitoring skills by…

  2. Old-new ERP effects and remote memories: the late parietal effect is absent as recollection fails whereas the early mid-frontal effect persists as familiarity is retained

    PubMed Central

    Tsivilis, Dimitris; Allan, Kevin; Roberts, Jenna; Williams, Nicola; Downes, John Joseph; El-Deredy, Wael

    2015-01-01

    Understanding the electrophysiological correlates of recognition memory processes has been a focus of research in recent years. This study investigated the effects of retention interval on recognition memory by comparing memory for objects encoded four weeks (remote) or 5 min (recent) before testing. In Experiment 1, event related potentials (ERPs) were acquired while participants performed a yes-no recognition memory task involving remote, recent and novel objects. Relative to correctly rejected new items, remote and recent hits showed an attenuated frontal negativity from 300–500 ms post-stimulus. This effect, also known as the FN400, has been previously associated with familiarity memory. Recent and remote recognition ERPs did not differ from each other at this time-window. By contrast, recent but not remote recognition showed increased parietal positivity from around 500 ms post-stimulus. This late parietal effect (LPE), which is considered a correlate of recollection-related processes, also discriminated between recent and remote memories. A second, behavioral experiment confirmed that remote memories unlike recent memories were based almost exclusively on familiarity. These findings support the idea that the FN400 and LPE are indices of familiarity and recollection memory, respectively and show that remote and recent memories are functionally and anatomically distinct. PMID:26528163

  3. Recall of Remote Episodic Memories Can Appear Deficient because of a Gist-Based Retrieval Orientation

    ERIC Educational Resources Information Center

    Rudoy, John D.; Weintraub, Sandra; Paller, Ken A.

    2009-01-01

    Determining whether patients with amnesia can succeed in remembering their distant past has pivotal implications for theories of memory storage. However, various factors influence recall. We speculated that some patients with anterograde amnesia adopt a gist-based retrieval orientation for memories from all time periods, thereby exaggerating…

  4. Extinction after Retrieval: Effects on the Associative and Nonassociative Components of Remote Contextual Fear Memory

    ERIC Educational Resources Information Center

    Costanzi, Marco; Cannas, Sara; Saraulli, Daniele; Rossi-Arnaud, Clelia; Cestari, Vincenzo

    2011-01-01

    Long-lasting memories of adverse experiences are essential for individuals' survival but are also involved, in the form of recurrent recollections of the traumatic experience, in the aetiology of anxiety diseases (e.g., post-traumatic stress disorder [PTSD]). Extinction-based erasure of fear memories has long been pursued as a behavioral way to…

  5. Tuning resistance states by thickness control in an electroforming-free nanometallic complementary resistance random access memory

    NASA Astrophysics Data System (ADS)

    Yang, Xiang; Lu, Yang; Lee, Jongho; Chen, I.-Wei

    2016-01-01

    Tuning low resistance state is crucial for resistance random access memory (RRAM) that aims to achieve optimal read margin and design flexibility. By back-to-back stacking two nanometallic bipolar RRAMs with different thickness into a complementary structure, we have found that its low resistance can be reliably tuned over several orders of magnitude. Such high tunability originates from the exponential thickness dependence of the high resistance state of nanometallic RRAM, in which electron wave localization in a random network gives rise to the unique scaling behavior. The complementary nanometallic RRAM provides electroforming-free, multi-resistance-state, sub-100 ns switching capability with advantageous characteristics for memory arrays.

  6. Performance improvement of gadolinium oxide resistive random access memory treated by hydrogen plasma immersion ion implantation

    SciTech Connect

    Wang, Jer-Chyi Hsu, Chih-Hsien; Ye, Yu-Ren; Ai, Chi-Fong; Tsai, Wen-Fa

    2014-03-15

    Characteristics improvement of gadolinium oxide (Gd{sub x}O{sub y}) resistive random access memories (RRAMs) treated by hydrogen plasma immersion ion implantation (PIII) was investigated. With the hydrogen PIII treatment, the Gd{sub x}O{sub y} RRAMs exhibited low set/reset voltages and a high resistance ratio, which were attributed to the enhanced movement of oxygen ions within the Gd{sub x}O{sub y} films and the increased Schottky barrier height at Pt/Gd{sub x}O{sub y} interface, respectively. The resistive switching mechanism of Gd{sub x}O{sub y} RRAMs was dominated by Schottky emission, as proved by the area dependence of the resistance in the low resistance state. After the hydrogen PIII treatment, a retention time of more than 10{sup 4} s was achieved at an elevated measurement temperature. In addition, a stable cycling endurance with the resistance ratio of more than three orders of magnitude of the Gd{sub x}O{sub y} RRAMs can be obtained.

  7. Switching methods in magnetic random access memory for low power applications

    NASA Astrophysics Data System (ADS)

    Guchang, Han; Jiancheng, Huang; Cheow Hin, Sim; Tran, Michael; Sze Ter, Lim

    2015-06-01

    Effect of saturation magnetization (Ms) of the free layer (FL) on the switching current is analyzed for spin transfer torque (STT) magnetic random access memory (MRAM). For in-plane FL, critical switching current (Ic0) decreases as Ms decreases. However, reduction in Ms also results in a low thermal stability factor (Δ), which must be compensated through increasing shape anisotropy, thus limiting scalability. For perpendicular FL, Ic0 reduction by using low-Ms materials is actually at the expense of data retention. To save energy consumed by STT current, two electric field (EF) controlled switching methods are proposed. Our simulation results show that elliptical FL can be switched by an EF pulse with a suitable width. However, it is difficult to implement this type of switching in real MRAM devices due to the distribution of the required switching pulse widths. A reliable switching method is to use an Oersted field guided switching. Our simulation and experimental results show that the bi-directional magnetization switching could be realized by an EF with an external field as low as  ±5 Oe if the offset field could be removed.

  8. Solution-processed carbon nanotube thin-film complementary static random access memory

    NASA Astrophysics Data System (ADS)

    Geier, Michael L.; McMorrow, Julian J.; Xu, Weichao; Zhu, Jian; Kim, Chris H.; Marks, Tobin J.; Hersam, Mark C.

    2015-11-01

    Over the past two decades, extensive research on single-walled carbon nanotubes (SWCNTs) has elucidated their many extraordinary properties, making them one of the most promising candidates for solution-processable, high-performance integrated circuits. In particular, advances in the enrichment of high-purity semiconducting SWCNTs have enabled recent circuit demonstrations including synchronous digital logic, flexible electronics and high-frequency applications. However, due to the stringent requirements of the transistors used in complementary metal-oxide-semiconductor (CMOS) logic as well as the absence of sufficiently stable and spatially homogeneous SWCNT thin-film transistors, the development of large-scale SWCNT CMOS integrated circuits has been limited in both complexity and functionality. Here, we demonstrate the stable and uniform electronic performance of complementary p-type and n-type SWCNT thin-film transistors by controlling adsorbed atmospheric dopants and incorporating robust encapsulation layers. Based on these complementary SWCNT thin-film transistors, we simulate, design and fabricate arrays of low-power static random access memory circuits, achieving large-scale integration for the first time based on solution-processed semiconductors.

  9. Electrical Evaluation of RCA MWS5001D Random Access Memory, Volume 1

    NASA Technical Reports Server (NTRS)

    Klute, A.

    1979-01-01

    Electrical characterization and qualification tests were performed on the RCA MWS5001D, 1024 by 1-bit, CMOS, random access memory. Characterization tests were performed on five devices. The tests included functional tests, AC parametric worst case pattern selection test, determination of worst-case transition for setup and hold times and a series of schmoo plots. The qualification tests were performed on 32 devices and included a 2000 hour burn in with electrical tests performed at 0 hours and after 168, 1000, and 2000 hours of burn in. The tests performed included functional tests and AC and DC parametric tests. All of the tests in the characterization phase, with the exception of the worst-case transition test, were performed at ambient temperatures of 25, -55 and 125 C. The worst-case transition test was performed at 25 C. The preburn in electrical tests were performed at 25, -55, and 125 C. All burn in endpoint tests were performed at 25, -40, -55, 85, and 125 C.

  10. Single-crystalline CuO nanowires for resistive random access memory applications

    SciTech Connect

    Hong, Yi-Siang; Chen, Jui-Yuan; Huang, Chun-Wei; Chiu, Chung-Hua; Huang, Yu-Ting; Huang, Ting Kai; He, Ruo Shiuan; Wu, Wen-Wei

    2015-04-27

    Recently, the mechanism of resistive random access memory (RRAM) has been partly clarified and determined to be controlled by the forming and erasing of conducting filaments (CF). However, the size of the CF may restrict the application and development as devices are scaled down. In this work, we synthesized CuO nanowires (NW) (∼150 nm in diameter) to fabricate a CuO NW RRAM nanodevice that was much smaller than the filament (∼2 μm) observed in a bulk CuO RRAM device in a previous study. HRTEM indicated that the Cu{sub 2}O phase was generated after operation, which demonstrated that the filament could be minimize to as small as 3.8 nm when the device is scaled down. In addition, energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS) show the resistive switching of the dielectric layer resulted from the aggregated oxygen vacancies, which also match with the I-V fitting results. Those results not only verify the switching mechanism of CuO RRAM but also show RRAM has the potential to shrink in size, which will be beneficial to the practical application of RRAM devices.

  11. Solution-processed carbon nanotube thin-film complementary static random access memory.

    PubMed

    Geier, Michael L; McMorrow, Julian J; Xu, Weichao; Zhu, Jian; Kim, Chris H; Marks, Tobin J; Hersam, Mark C

    2015-11-01

    Over the past two decades, extensive research on single-walled carbon nanotubes (SWCNTs) has elucidated their many extraordinary properties, making them one of the most promising candidates for solution-processable, high-performance integrated circuits. In particular, advances in the enrichment of high-purity semiconducting SWCNTs have enabled recent circuit demonstrations including synchronous digital logic, flexible electronics and high-frequency applications. However, due to the stringent requirements of the transistors used in complementary metal-oxide-semiconductor (CMOS) logic as well as the absence of sufficiently stable and spatially homogeneous SWCNT thin-film transistors, the development of large-scale SWCNT CMOS integrated circuits has been limited in both complexity and functionality. Here, we demonstrate the stable and uniform electronic performance of complementary p-type and n-type SWCNT thin-film transistors by controlling adsorbed atmospheric dopants and incorporating robust encapsulation layers. Based on these complementary SWCNT thin-film transistors, we simulate, design and fabricate arrays of low-power static random access memory circuits, achieving large-scale integration for the first time based on solution-processed semiconductors. PMID:26344184

  12. High uniformity and improved nonlinearity by embedding nanocrystals in selector-less resistive random access memory.

    PubMed

    Banerjee, Writam; Lu, Nianduan; Li, Ling; Sun, Pengxiao; Liu, Qi; Lv, Hangbing; Long, Shibing; Liu, Ming

    2014-12-10

    The sneak path problem is one of the major hindrances for the application of high density 3D crossbar resistive random access memory (RRAM). For the selector-less RRAM devices, nonlinear (NL) current-voltage (I-V) characteristics are an alternative approach to minimize the sneak paths. In this work we have demonstrated metallic IrOx nanocrystal (IrOx-NC) based selector-less crossbar RRAM devices in an IrOx/AlOx/IrOx-NC/AlOx/W structure with very reliable hysteresis resistive switching of >10 000 cycles, stable multiple levels, and high temperature (HT) data retention. Moreover, an improvement in the NL behavior has been reported as compared to a pure high-κ AlOx RRAM. The origin of the NL nature has been discussed using the hopping model and Luittenger's 1D metal theory. The nonlinearity can be further improved by structure engineering and will improve the sensing margin of the devices, which is rewarding for crossbar array integration. PMID:25491764

  13. Flexible conductive-bridging random-access-memory cell vertically stacked with top Ag electrode, PEO, PVK, and bottom Pt electrode.

    PubMed

    Seung, Hyun-Min; Kwon, Kyoung-Cheol; Lee, Gon-Sub; Park, Jea-Gun

    2014-10-31

    Flexible conductive-bridging random-access-memory (RAM) cells were fabricated with a cross-bar memory cell stacked with a top Ag electrode, conductive polymer (poly(n-vinylcarbazole): PVK), electrolyte (polyethylene oxide: PEO), bottom Pt electrode, and flexible substrate (polyethersulfone: PES), exhibiting the bipolar switching behavior of resistive random access memory (ReRAM). The cell also exhibited bending-fatigue-free nonvolatile memory characteristics: i.e., a set voltage of 1.0 V, a reset voltage of -1.6 V, retention time of >1 × 10(5) s with a memory margin of 9.2 × 10(5), program/erase endurance cycles of >10(2) with a memory margin of 8.4 × 10(5), and bending-fatigue-free cycles of ∼1 × 10(3) with a memory margin (I(on)/I(off)) of 3.3 × 10(5). PMID:25297517

  14. Accessing, Utilizing and Visualizing NASA Remote Sensing Data for Malaria Modeling and Surveillance

    NASA Technical Reports Server (NTRS)

    Kiang, Richard K.; Adimi, Farida; Kempler, Steven

    2007-01-01

    This poster presentation reviews the use of NASA remote sensing data that can be used to extract environmental information for modeling malaria transmission. The authors discuss the remote sensing data from Landsat, Advanced Very High Resolution Radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), Tropical Rainfall Measuring Mission (TRMM), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Earth Observing One (EO-1), Advanced Land Imager (ALI) and Seasonal to Interannual Earth Science Information Partner (SIESIP) dataset.

  15. Use of the Remote Access Virtual Environment Network (RAVEN) for coordinated IVA-EVA astronaut training and evaluation.

    PubMed

    Cater, J P; Huffman, S D

    1995-01-01

    This paper presents a unique virtual reality training and assessment tool developed under a NASA grant, "Research in Human Factors Aspects of Enhanced Virtual Environments for Extravehicular Activity (EVA) Training and Simulation." The Remote Access Virtual Environment Network (RAVEN) was created to train and evaluate the verbal, mental and physical coordination required between the intravehicular (IVA) astronaut operating the Remote Manipulator System (RMS) arm and the EVA astronaut standing in foot restraints on the end of the RMS. The RAVEN system currently allows the EVA astronaut to approach the Hubble Space Telescope (HST) under control of the IVA astronaut and grasp, remove, and replace the Wide Field Planetary Camera drawer from its location in the HST. Two viewpoints, one stereoscopic and one monoscopic, were created all linked by Ethernet, that provided the two trainees with the appropriate training environments. PMID:11539288

  16. An amorphous titanium dioxide metal insulator metal selector device for resistive random access memory crossbar arrays with tunable voltage margin

    NASA Astrophysics Data System (ADS)

    Cortese, Simone; Khiat, Ali; Carta, Daniela; Light, Mark E.; Prodromakis, Themistoklis

    2016-01-01

    Resistive random access memory (ReRAM) crossbar arrays have become one of the most promising candidates for next-generation non volatile memories. To become a mature technology, the sneak path current issue must be solved without compromising all the advantages that crossbars offer in terms of electrical performances and fabrication complexity. Here, we present a highly integrable access device based on nickel and sub-stoichiometric amorphous titanium dioxide (TiO2-x), in a metal insulator metal crossbar structure. The high voltage margin of 3 V, amongst the highest reported for monolayer selector devices, and the good current density of 104 A/cm2 make it suitable to sustain ReRAM read and write operations, effectively tackling sneak currents in crossbars without compromising fabrication complexity in a 1 Selector 1 Resistor (1S1R) architecture. Furthermore, the voltage margin is found to be tunable by an annealing step without affecting the device's characteristics.

  17. The formation of recent and remote memory is associated with time-dependent formation of dendritic spines in the hippocampus and anterior cingulate cortex.

    PubMed

    Restivo, Leonardo; Vetere, Gisella; Bontempi, Bruno; Ammassari-Teule, Martine

    2009-06-24

    Although hippocampal-cortical interactions are crucial for the formation of enduring declarative memories, synaptic events that govern long-term memory storage remain mostly unclear. We present evidence that neuronal structural changes, i.e., dendritic spine growth, develop sequentially in the hippocampus and anterior cingulate cortex (aCC) during the formation of recent and remote contextual fear memory. We found that mice placed in a conditioning chamber for one 7 min conditioning session and exposed to five footshocks (duration, 2 s; intensity, 0.7 mA; interstimulus interval, 60 s) delivered through the grid floor exhibited robust fear response when returned to the experimental context 24 h or 36 d after the conditioning. We then observed that their fear response at the recent, but not the remote, time point was associated with an increase in spine density on hippocampal neurons, whereas an inverse temporal pattern of spine density changes occurred on aCC neurons. At each time point, hippocampal or aCC structural alterations were achieved even in the absence of recent or remote memory tests, thus suggesting that they were not driven by retrieval processes. Furthermore, ibotenic lesions of the hippocampus impaired remote memory and prevented dendritic spine growth on aCC neurons when they were performed immediately after the conditioning, whereas they were ineffective when performed 24 d later. These findings reveal that gradual structural changes modifying connectivity in hippocampal-cortical networks underlie the formation and expression of remote memory, and that the hippocampus plays a crucial but time-limited role in driving structural plasticity in the cortex. PMID:19553460

  18. Encoding and retrieval processes involved in the access of source information in the absence of item memory.

    PubMed

    Ball, B Hunter; DeWitt, Michael R; Knight, Justin B; Hicks, Jason L

    2014-09-01

    The current study sought to examine the relative contributions of encoding and retrieval processes in accessing contextual information in the absence of item memory using an extralist cuing procedure in which the retrieval cues used to query memory for contextual information were related to the target item but never actually studied. In Experiments 1 and 2, participants studied 1 category member (e.g., onion) from a variety of different categories and at test were presented with an unstudied category label (e.g., vegetable) to probe memory for item and source information. In Experiments 3 and 4, 1 member of unidirectional (e.g., credit or card) or bidirectional (e.g., salt or pepper) associates was studied, whereas the other unstudied member served as a test probe. When recall failed, source information was accessible only when items were processed deeply during encoding (Experiments 1 and 2) and when there was strong forward associative strength between the retrieval cue and target (Experiments 3 and 4). These findings suggest that a retrieval probe diagnostic of semantically related item information reinstantiates information bound in memory during encoding that results in reactivation of associated contextual information, contingent upon sufficient learning of the item itself and the association between the item and its context information. PMID:24933700

  19. Chemical state of Ag in Conducting Bridge Random Access Memory cells: a depth resolved X-ray Absorption Spectroscopy investigation.

    NASA Astrophysics Data System (ADS)

    d'Acapito, F.; Souchier, E.; Noe, P.; Blaise, P.; Bernard, M.; Jousseaume, V.

    2016-05-01

    Conducting Bridge Random Access Memories (CBRAM) are a promising substitute for FLASH technology but problems with limited retention of the low resistance ON state still hamper their massive deployment. Depth resolved X-ray Absorption Spectroscopy has been used to describe the chemical state of the atoms of the active electrode (in this case Ag) and to reveal the role of Sb as stabilizer of the metallic state.

  20. ViSA: a neurodynamic model for visuo-spatial working memory, attentional blink, and conscious access.

    PubMed

    Simione, Luca; Raffone, Antonino; Wolters, Gezinus; Salmas, Paola; Nakatani, Chie; Belardinelli, Marta Olivetti; van Leeuwen, Cees

    2012-10-01

    Two separate lines of study have clarified the role of selectivity in conscious access to visual information. Both involve presenting multiple targets and distracters: one simultaneously in a spatially distributed fashion, the other sequentially at a single location. To understand their findings in a unified framework, we propose a neurodynamic model for Visual Selection and Awareness (ViSA). ViSA supports the view that neural representations for conscious access and visuo-spatial working memory are globally distributed and are based on recurrent interactions between perceptual and access control processors. Its flexible global workspace mechanisms enable a unitary account of a broad range of effects: It accounts for the limited storage capacity of visuo-spatial working memory, attentional cueing, and efficient selection with multi-object displays, as well as for the attentional blink and associated sparing and masking effects. In particular, the speed of consolidation for storage in visuo-spatial working memory in ViSA is not fixed but depends adaptively on the input and recurrent signaling. Slowing down of consolidation due to weak bottom-up and recurrent input as a result of brief presentation and masking leads to the attentional blink. Thus, ViSA goes beyond earlier 2-stage and neuronal global workspace accounts of conscious processing limitations. PMID:22823385

  1. Integrated Web-Based Access to and use of Satellite Remote Sensing Data for Improved Decision Making in Hydrologic Applications

    NASA Astrophysics Data System (ADS)

    Teng, W.; Chiu, L.; Kempler, S.; Liu, Z.; Nadeau, D.; Rui, H.

    2006-12-01

    Using NASA satellite remote sensing data from multiple sources for hydrologic applications can be a daunting task and requires a detailed understanding of the data's internal structure and physical implementation. Gaining this understanding and applying it to data reduction is a time-consuming task that must be undertaken before the core investigation can begin. In order to facilitate such investigations, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) has developed the GES-DISC Interactive Online Visualization ANd aNalysis Infrastructure or "Giovanni," which supports a family of Web interfaces (instances) that allow users to perform interactive visualization and analysis online without downloading any data. Two such Giovanni instances are particularly relevant to hydrologic applications: the Tropical Rainfall Measuring Mission (TRMM) Online Visualization and Analysis System (TOVAS) and the Agricultural Online Visualization and Analysis System (AOVAS), both highly popular and widely used for a variety of applications, including those related to several NASA Applications of National Priority, such as Agricultural Efficiency, Disaster Management, Ecological Forecasting, Homeland Security, and Public Health. Dynamic, context- sensitive Web services provided by TOVAS and AOVAS enable users to seamlessly access NASA data from within, and deeply integrate the data into, their local client environments. One example is between TOVAS and Florida International University's TerraFly, a Web-enabled system that serves a broad segment of the research and applications community, by facilitating access to various textual, remotely sensed, and vector data. Another example is between AOVAS and the U.S. Department of Agriculture Foreign Agricultural Service (USDA FAS)'s Crop Explorer, the primary decision support tool used by FAS to monitor the production, supply, and demand of agricultural commodities worldwide. AOVAS is also part of GES DISC

  2. Physical and chemical mechanisms in oxide-based resistance random access memory

    NASA Astrophysics Data System (ADS)

    Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Zhang, Rui; Hung, Ya-Chi; Syu, Yong-En; Chang, Yao-Feng; Chen, Min-Chen; Chu, Tian-Jian; Chen, Hsin-Lu; Pan, Chih-Hung; Shih, Chih-Cheng; Zheng, Jin-Cheng; Sze, Simon M.

    2015-03-01

    In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

  3. Physical and chemical mechanisms in oxide-based resistance random access memory.

    PubMed

    Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Zhang, Rui; Hung, Ya-Chi; Syu, Yong-En; Chang, Yao-Feng; Chen, Min-Chen; Chu, Tian-Jian; Chen, Hsin-Lu; Pan, Chih-Hung; Shih, Chih-Cheng; Zheng, Jin-Cheng; Sze, Simon M

    2015-01-01

    In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications. PMID:25873842

  4. Current Development Status and Future Challenges of Ferroelectric Random Access Memory Technologies

    NASA Astrophysics Data System (ADS)

    Lee, Sungyung; Kim, Kinam

    2006-04-01

    For ferroelectric random access memory (FRAM) to be beneficial in future mobile devices, high-density FRAM with nm scaled cell should be developed. We have succeeded in scaling further the cell size of one-pass transistor and one-storage capacitor (1T1C) FRAM down to 0.27 μm2 at 150 nm technology node. Owing to new SrRuO3 (SRO) electrode technology along with ultrathin PbZrTiO3 (PZT) using metal organic chemical vapor deposition (MOCVD) technology, two-dimensional (2-D) metal-insulator-metal (MIM) ferroelectric capacitor was successfully scaled down vertically to 200 nm. By the application of a new double hard mask capacitor etching technology, 0.11-μm2-area 200-nm-thick 2-D PZT capacitor was successfully isolated with 180 nm spacing. As a result, a high remanent polarization of 40 μC/cm2 was obtained at 1.6 V on a 0.11 μm2 ferroelectric storage capacitor of the 0.27 μm2 cell 1T1C FRAM. Great advances in three-dimensional (3-D) ferroelectric capacitor, which is essential for 6-8 F2 cell 1T1C FRAM at nm scaled technology node, have been made by introducing a new atomic layer deposition (ALD) method for 3-D electrode and a novel MOCVD PZT deposition for 3-D PZT. As a result, for the first time, robust hysteresis was obtained from a 3-D PZT capacitor.

  5. Retrosplenial Cortex Is Required for the Retrieval of Remote Memory for Auditory Cues

    ERIC Educational Resources Information Center

    Todd, Travis P.; Mehlman, Max L.; Keene, Christopher S.; DeAngeli, Nicole E.; Bucci, David J.

    2016-01-01

    The retrosplenial cortex (RSC) has a well-established role in contextual and spatial learning and memory, consistent with its known connectivity with visuo-spatial association areas. In contrast, RSC appears to have little involvement with delay fear conditioning to an auditory cue. However, all previous studies have examined the contribution of…

  6. Neurogenesis Interferes with the Retrieval of Remote Memories: Forgetting in Neurocomputational Terms

    ERIC Educational Resources Information Center

    Weisz, Victoria I.; Argibay, Pablo F.

    2012-01-01

    In contrast to models and theories that relate adult neurogenesis with the processes of learning and memory, almost no solid hypotheses have been formulated that involve a possible neurocomputational influence of adult neurogenesis on forgetting. Based on data from a previous study that implemented a simple but complete model of the main…

  7. Remote Spatial Memory and the Hippocampus: Effect of Early and Extensive Training in the Radial Maze

    ERIC Educational Resources Information Center

    Ramos, Juan M. J.

    2009-01-01

    In a previous study we showed a temporally graded retrograde amnesia after hippocampal lesions when rats learned a spatial reference memory task in which two types of signals simultaneously indicated the goal arm (shape of the experimental room and extramaze landmarks). To investigate the effect that the navigational demands of the task have on…

  8. Accessibility

    MedlinePlus

    ... www.nlm.nih.gov/medlineplus/accessibility.html MedlinePlus Accessibility To use the sharing features on this page, ... Subscribe to RSS Follow us Disclaimers Copyright Privacy Accessibility Quality Guidelines Viewers & Players MedlinePlus Connect for EHRs ...

  9. Conditional forebrain deletion of the L-type calcium channel Ca V 1.2 disrupts remote spatial memories in mice.

    PubMed

    White, Jessica A; McKinney, Brandon C; John, Manorama C; Powers, Patricia A; Kamp, Timothy J; Murphy, Geoffrey G

    2008-01-01

    To determine whether L-type voltage-gated calcium channels (L-VGCCs) are required for remote memory consolidation, we generated conditional knockout mice in which the L-VGCC isoform Ca(V)1.2 was postnatally deleted in the hippocampus and cortex. In the Morris water maze, both Ca(V)1.2 conditional knockout mice (Ca(V)1.2(cKO)) and control littermates displayed a marked decrease in escape latencies and performed equally well on probe trials administered during training. In distinct contrast to their performance during training, Ca(V)1.2(cKO) mice exhibited significant impairments in spatial memory when examined 30 d after training, suggesting that Ca(V)1.2 plays a critical role in consolidation of remote spatial memories. PMID:18174367

  10. E-Learning in Engineering Education: Design of a Collaborative Advanced Remote Access Laboratory

    ERIC Educational Resources Information Center

    Chandra A. P., Jagadeesh; Samuel, R. D. Sudhaker

    2010-01-01

    Attaining excellence in technical education is a worthy challenge to any life goal. Distance learning opportunities make these goals easier to reach with added quality. Distance learning in engineering education is possible only through successful implementations of remote laboratories in a learning-by-doing environment. This paper presents one…

  11. Remote access to very large image repositories, a high performance computing perspective

    NASA Technical Reports Server (NTRS)

    Plesea, Lucian

    2005-01-01

    The main challenges of using the increasingly large repositories of remote imagery data can be summarized in one word: efficiency. In this paper, a number of concrete problems and the chosen solutions are described, based on the construction of a 5TB global Landsat 7 mosaic.

  12. Language, Culture and Access to Mathematics: A Case of One Remote Aboriginal Community

    ERIC Educational Resources Information Center

    Jorgensen, Robyn

    2015-01-01

    For many students, coming to learn mathematics is as much about the pedagogical relay through which concepts are conveyed as it is about the mathematics per se. This relay comprises social, cultural and linguistic norms as well as the mathematical discourse. In this study, I outline the practices of one remote school and how the teaching practices…

  13. U.S. EPA High-Field NMR Facility with Remote Accessibility

    EPA Science Inventory

    EPA’s High-Field Nuclear Magnetic Resonance Research Facility housed in Athens, GA has two Varian 600 MHz NMR spectrometers used for conducting sophisticated experiments in environmental science. Off-site users can ship their samples and perform their NMR experiments remotely fr...

  14. Contexts and Control Operations Used in Accessing List-Specific, Generalized, and Semantic Memories

    ERIC Educational Resources Information Center

    Humphreys, Michael S.; Murray, Krista L.; Maguire, Angela M.

    2009-01-01

    The human ability to focus memory retrieval operations on a particular list, episode or memory structure has not been fully appreciated or documented. In Experiment 1-3, we make it increasingly difficult for participants to switch between a less recent list (multiple study opportunities), and a more recent list (single study opportunity). Task…

  15. Speed and Accuracy of Accessing Information in Working Memory: An Individual Differences Investigation of Focus Switching

    ERIC Educational Resources Information Center

    Unsworth, Nash; Engle, Randall W.

    2008-01-01

    Three experiments examined the nature of individual differences in switching the focus of attention in working memory. Participants performed 3 versions of a continuous counting task that required successive updating and switching between counts. Across all 3 experiments, individual differences in working memory span and fluid intelligence were…

  16. Retrieval practice enhances the accessibility but not the quality of memory.

    PubMed

    Sutterer, David W; Awh, Edward

    2016-06-01

    Numerous studies have demonstrated that retrieval from long-term memory (LTM) can enhance subsequent memory performance, a phenomenon labeled the retrieval practice effect. However, the almost exclusive reliance on categorical stimuli in this literature leaves open a basic question about the nature of this improvement in memory performance. It has not yet been determined whether retrieval practice improves the probability of successful memory retrieval or the quality of the retrieved representation. To answer this question, we conducted three experiments using a mixture modeling approach (Zhang & Luck, 2008) that provides a measure of both the probability of recall and the quality of the recalled memories. Subjects attempted to memorize the color of 400 unique shapes. After every 10 images were presented, subjects either recalled the last 10 colors (the retrieval practice condition) by clicking on a color wheel with each shape as a retrieval cue or they participated in a control condition that involved no further presentations (Experiment 1) or restudy of the 10 shape/color associations (Experiments 2 and 3). Performance in a subsequent delayed recall test revealed a robust retrieval practice effect. Subjects recalled a significantly higher proportion of items that they had previously retrieved relative to items that were untested or that they had restudied. Interestingly, retrieval practice did not elicit any improvement in the precision of the retrieved memories. The same empirical pattern also was observed following delays of greater than 24 hours. Thus, retrieval practice increases the probability of successful memory retrieval but does not improve memory quality. PMID:26404635

  17. The Effect of Retrieval Cues on Visual Preferences and Memory in Infancy: Evidence for a Four-Phase Attention Function.

    ERIC Educational Resources Information Center

    Bahrick, Lorraine E.; Hernandez-Reif, Maria; Pickens, Jeffrey N.

    1997-01-01

    Tested hypothesis from Bahrick and Pickens' infant attention model that retrieval cues increase memory accessibility and shift visual preferences toward greater novelty to resemble recent memories. Found that after retention intervals associated with remote or intermediate memory, previous familiarity preferences shifted to null or novelty…

  18. An SEU (single event upset) tolerant memory cell derived from fundamental studies of SEU mechanisms in SRAM (static random access memories)

    SciTech Connect

    Weaver, H.T.; Axness, C.L.; McBrayer, J.D.; Browning, J.S.; Fu, J.S.; Ochoa, A. Jr.; Koga, R.

    1987-01-01

    A new single event upset (SEU) hardening concept, an LRAM cell, is demonstrated theoretically and experimentally. As basis for the LRAM idea, techniques were developed to measure time constants for ion induced voltage transients in conventional static random access memories, SRAM. Time constants of 0.8 and 6.0 nsec were measured for transients following strikes at the n- and p-channel drains, respectively - primary areas of SEU sensitivity. These data are the first transient time measurements on full memory chips and the large difference is fundamental to the LRAM concept. Decoupling resistors in the LRAM are used only to protect against the short transient; longer persisting pulses are blocked by a voltage divider, a basically new concept for SEU protection. In such a design, smaller resistors provide SEU tolerance, allowing higher performance, hardened memories. Test structures of the new design exhibit SEU tolerance with resistors 5-to-10 times smaller than currently used in SRAM. Our advanced transport-plus-circuit numerical simulations of the SEU process predicted this result and account for the LRAM experiments, as well as a variety of experiments on conventional SRAM. 16 refs., 6 figs., 1 tab.

  19. Remediating Viking Origins: Genetic Code as Archival Memory of the Remote Past

    PubMed Central

    King, Turi; Brown, Steven D

    2013-01-01

    This article introduces some early data from the Leverhulme Trust-funded research programme, ‘The Impact of the Diasporas on the Making of Britain: evidence, memories, inventions’. One of the interdisciplinary foci of the programme, which incorporates insights from genetics, history, archaeology, linguistics and social psychology, is to investigate how genetic evidence of ancestry is incorporated into identity narratives. In particular, we investigate how ‘applied genetic history’ shapes individual and familial narratives, which are then situated within macro-narratives of the nation and collective memories of immigration and indigenism. It is argued that the construction of genetic evidence as a ‘gold standard’ about ‘where you really come from’ involves a remediation of cultural and archival memory, in the construction of a ‘usable past’. This article is based on initial questionnaire data from a preliminary study of those attending DNA collection sessions in northern England. It presents some early indicators of the perceived importance of being of Viking descent among participants, notes some emerging patterns and considers the implications for contemporary debates on migration, belonging and local and national identity. PMID:24179286

  20. Remediating Viking Origins: Genetic Code as Archival Memory of the Remote Past.

    PubMed

    Scully, Marc; King, Turi; Brown, Steven D

    2013-10-01

    This article introduces some early data from the Leverhulme Trust-funded research programme, 'The Impact of the Diasporas on the Making of Britain: evidence, memories, inventions'. One of the interdisciplinary foci of the programme, which incorporates insights from genetics, history, archaeology, linguistics and social psychology, is to investigate how genetic evidence of ancestry is incorporated into identity narratives. In particular, we investigate how 'applied genetic history' shapes individual and familial narratives, which are then situated within macro-narratives of the nation and collective memories of immigration and indigenism. It is argued that the construction of genetic evidence as a 'gold standard' about 'where you really come from' involves a remediation of cultural and archival memory, in the construction of a 'usable past'. This article is based on initial questionnaire data from a preliminary study of those attending DNA collection sessions in northern England. It presents some early indicators of the perceived importance of being of Viking descent among participants, notes some emerging patterns and considers the implications for contemporary debates on migration, belonging and local and national identity. PMID:24179286

  1. Web-based interactive access, analysis and comparison of remotely sensed and in situ measured temperature data

    NASA Astrophysics Data System (ADS)

    Eberle, Jonas; Urban, Marcel; Hüttich, Christian; Schmullius, Christiane

    2014-05-01

    Numerous datasets providing temperature information from meteorological stations or remote sensing satellites are available. However, the challenging issue is to search in the archives and process the time series information for further analysis. These steps can be automated for each individual product, if the pre-conditions are complied, e.g. data access through web services (HTTP, FTP) or legal rights to redistribute the datasets. Therefore a python-based package was developed to provide data access and data processing tools for MODIS Land Surface Temperature (LST) data, which is provided by NASA Land Processed Distributed Active Archive Center (LPDAAC), as well as the Global Surface Summary of the Day (GSOD) and the Global Historical Climatology Network (GHCN) daily datasets provided by NOAA National Climatic Data Center (NCDC). The package to access and process the information is available as web services used by an interactive web portal for simple data access and analysis. Tools for time series analysis were linked to the system, e.g. time series plotting, decomposition, aggregation (monthly, seasonal, etc.), trend analyses, and breakpoint detection. Especially for temperature data a plot was integrated for the comparison of two temperature datasets based on the work by Urban et al. (2013). As a first result, a kernel density plot compares daily MODIS LST from satellites Aqua and Terra with daily means from GSOD and GHCN datasets. Without any data download and data processing, the users can analyze different time series datasets in an easy-to-use web portal. As a first use case, we built up this complimentary system with remotely sensed MODIS data and in situ measurements from meteorological stations for Siberia within the Siberian Earth System Science Cluster (www.sibessc.uni-jena.de). References: Urban, Marcel; Eberle, Jonas; Hüttich, Christian; Schmullius, Christiane; Herold, Martin. 2013. "Comparison of Satellite-Derived Land Surface Temperature and Air

  2. CMOS Interface Circuits for Spin Tunneling Junction Based Magnetic Random Access Memories

    SciTech Connect

    Ganesh Saripalli

    2002-12-31

    Magneto resistive memories (MRAM) are non-volatile memories which use magnetic instead of electrical structures to store data. These memories, apart from being non-volatile, offer a possibility to achieve densities better than DRAMs and speeds faster than SRAMs. MRAMs could potentially replace all computer memory RAM technologies in use today, leading to future applications like instan-on computers and longer battery life for pervasive devices. Such rapid development was made possible due to the recent discovery of large magnetoresistance in Spin tunneling junction devices. Spin tunneling junctions (STJ) are composite structures consisting of a thin insulating layer sandwiched between two magnetic layers. This thesis research is targeted towards these spin tunneling junction based Magnetic memories. In any memory, some kind of an interface circuit is needed to read the logic states. In this thesis, four such circuits are proposed and designed for Magnetic memories (MRAM). These circuits interface to the Spin tunneling junctions and act as sense amplifiers to read their magnetic states. The physical structure and functional characteristics of these circuits are discussed in this thesis. Mismatch effects on the circuits and proper design techniques are also presented. To demonstrate the functionality of these interface structures, test circuits were designed and fabricated in TSMC 0.35{micro} CMOS process. Also circuits to characterize the process mismatches were fabricated and tested. These results were then used in Matlab programs to aid in design process and to predict interface circuit's yields.

  3. Oxide Defect Engineering Methods for Valence Change (VCM) Resistive Random Access Memories

    NASA Astrophysics Data System (ADS)

    Capulong, Jihan O.

    Electrical switching requirements for resistive random access memory (ReRAM) devices are multifaceted, based on device application. Thus, it is important to obtain an understanding of these switching properties and how they relate to the oxygen vacancy concentration and oxygen vacancy defects. Oxygen vacancy defects in the switching oxide of valence-change-based ReRAM (VCM ReRAM) play a significant role in device switching properties. Oxygen vacancies facilitate resistive switching as they form the conductive filament that changes the resistance state of the device. This dissertation will present two methods of modulating the defect concentration in VCM ReRAM composed of Pt/HfOx/Ti stack: 1) rapid thermal annealing (RTA) in Ar using different temperatures, and 2) doping using ion implantation under different dose levels. Metrology techniques such as x-ray diffractometry (XRD), x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy were utilized to characterize the HfOx switching oxide, which provided insight on the material properties and oxygen vacancy concentration in the oxide that was used to explain the changes in the electrical properties of the ReRAM devices. The resulting impact on the resistive switching characteristics of the devices, such as the forming voltage, set and reset threshold voltages, ON and OFF resistances, resistance ratio, and switching dispersion or uniformity were explored and summarized. Annealing in Ar showed significant impact on the forming voltage, with as much as 45% (from 22V to 12 V) of improvement, as the annealing temperature was increased. However, drawbacks of a higher oxide leakage and worse switching uniformity were seen with increasing annealing temperature. Meanwhile, doping the oxide by ion implantation showed significant effects on the resistive switching characteristics. Ta doping modulated the following switching properties with increasing dose: a) the reduction of the forming voltage, and Vset

  4. Effect of embedded metal nanocrystals on the resistive switching characteristics in NiN-based resistive random access memory cells

    SciTech Connect

    Yun, Min Ju; Kim, Hee-Dong; Man Hong, Seok; Hyun Park, Ju; Su Jeon, Dong; Geun Kim, Tae

    2014-03-07

    The metal nanocrystals (NCs) embedded-NiN-based resistive random access memory cells are demonstrated using several metal NCs (i.e., Pt, Ni, and Ti) with different physical parameters in order to investigate the metal NC's dependence on resistive switching (RS) characteristics. First, depending on the electronegativity of metal, the size of metal NCs is determined and this affects the operating current of memory cells. If metal NCs with high electronegativity are incorporated, the size of the NCs is reduced; hence, the operating current is reduced owing to the reduced density of the electric field around the metal NCs. Second, the potential wells are formed by the difference of work function between the metal NCs and active layer, and the barrier height of the potential wells affects the level of operating voltage as well as the conduction mechanism of metal NCs embedded memory cells. Therefore, by understanding these correlations between the active layer and embedded metal NCs, we can optimize the RS properties of metal NCs embedded memory cells as well as predict their conduction mechanisms.

  5. Set statistics in conductive bridge random access memory device with Cu/HfO{sub 2}/Pt structure

    SciTech Connect

    Zhang, Meiyun; Long, Shibing Wang, Guoming; Xu, Xiaoxin; Li, Yang; Liu, Qi; Lv, Hangbing; Liu, Ming; Lian, Xiaojuan; Miranda, Enrique; Suñé, Jordi

    2014-11-10

    The switching parameter variation of resistive switching memory is one of the most important challenges in its application. In this letter, we have studied the set statistics of conductive bridge random access memory with a Cu/HfO{sub 2}/Pt structure. The experimental distributions of the set parameters in several off resistance ranges are shown to nicely fit a Weibull model. The Weibull slopes of the set voltage and current increase and decrease logarithmically with off resistance, respectively. This experimental behavior is perfectly captured by a Monte Carlo simulator based on the cell-based set voltage statistics model and the Quantum Point Contact electron transport model. Our work provides indications for the improvement of the switching uniformity.

  6. Analysis of coherent activity between retrosplenial cortex, hippocampus, thalamus, and anterior cingulate cortex during retrieval of recent and remote context fear memory.

    PubMed

    Corcoran, Kevin A; Frick, Brendan J; Radulovic, Jelena; Kay, Leslie M

    2016-01-01

    Memory for contextual fear conditioning relies upon the retrosplenial cortex (RSC) regardless of how long ago conditioning occurred, whereas areas connected to the RSC, such as the dorsal hippocampus (DH) and anterior cingulate cortex (ACC) appear to play time-limited roles. To better understand whether these brain regions functionally interact during memory processing and how the passage of time affects these interactions, we simultaneously recorded local field potentials (LFPs) from these three regions as well as anterior dorsal thalamus (ADT), which provides one of the strongest inputs to RSC, and measured coherence of oscillatory activity within the theta (4-12Hz) and gamma (30-80Hz) frequency bands. We identified changes of theta coherence related to encoding, retrieval, and extinction of context fear, whereas changes in gamma coherence were restricted to fear extinction. Specifically, exposure to a novel context and retrieval of recently acquired fear conditioning memory were associated with increased theta coherence between RSC and all three other structures. In contrast, RSC-DH and RSC-ADT theta coherence were decreased in mice that successfully retrieved, relative to mice that failed to retrieve, remote memory. Greater RSC-ADT theta and gamma coherence were observed during recent, compared to remote, extinction of freezing responses. Thus, the degree of coherence between RSC and connected brain areas may predict and contribute to context memory retrieval and retrieval-related phenomena such as fear extinction. Importantly, although theta coherence in this circuit increases during memory encoding and retrieval of recent memory, failure to decrease RSC-DH theta coherence might be linked to retrieval deficit in the long term, and possibly contribute to aberrant memory processing characteristic of neuropsychiatric disorders. PMID:26691782

  7. Device modeling of ferroelectric memory field-effect transistor for the application of ferroelectric random access memory.

    PubMed

    Lue, Hang-Ting; Wu, Chien-Jang; Tseng, Tseung-Yuen

    2003-01-01

    An improved theoretical analysis on the electrical characteristics of ferroelectric memory field-effect transistor (FeMFET) is given. First, we propose a new analytical expression for the polarization versus electric field (P-E) for the ferroelectric material. It is determined by one parameter and explicitly includes both the saturated and nonsaturated hysteresis loops. Using this expression, we then examine the operational properties for two practical devices such as the metal-ferroelectric-insulator-semiconductor field-effect transistor (MFIS-FET) and metal-ferroelectric-metal-insulator-semiconductor field-effect transistor (MFMIS-FET) as well. A double integral also has been used, in order to include the possible effects due to the nonuniform field and charge distribution along the channel of the device, to calculate the drain current of FeMFET. By using the relevant material parameters close to the (Bi, La)4Ti3O12 (BLT) system, accurate analyses on the capacitors and FeMFET's at various applied biases are made. We also address the issues of depolarization field and retention time about such a device. PMID:12578132

  8. Acute administration of nicotine into the higher order auditory Te2 cortex specifically decreases the fear-related charge of remote emotional memories

    PubMed Central

    Cambiaghi, Marco; Grosso, Anna; Renna, Annamaria; Concina, Giulia; Sacchetti, Benedetto

    2015-01-01

    Nicotine elicits several behavioural effects on mood as well as on stress and anxiety processes. Recently, it was found that the higher order components of the sensory cortex, such as the secondary auditory cortex Te2, are essential for the long-term storage of remote fear memories. Therefore, in the present study, we examined the effects of acute nicotine injection into the higher order auditory cortex Te2, on the remote emotional memories of either threat or incentive experiences in rats. We found that intra-Te2 nicotine injection decreased the fear-evoked responses to a tone previously paired with footshock. This effect was cue- and dose-specific and was not due to any interference with auditory stimuli processing, innate anxiety and fear processes, or with motor responses. Nicotine acts acutely in the presence of threat stimuli but it did not determine the permanent degradation of the fear-memory trace, since memories tested one week after nicotine injection were unaffected. Remarkably, nicotine did not affect the memory of a similar tone that was paired to incentive stimuli. We conclude from our results that nicotine, when acting acutely in the auditory cortex, relieves the fear charge embedded by learned stimuli. PMID:26319210

  9. Remote Access to Earth Science Data by Content, Space and Time

    NASA Technical Reports Server (NTRS)

    Dobinson, E.; Raskin, G.

    1998-01-01

    This demo presents the combination on an http-based client/server application that facilitates internet access to Earth science data coupled with a Java applet GUI that allows the user to graphically select data based on spatial and temporal coverage plots and scientific parameters.

  10. Training of Library Personnel in Remote Areas (The ACCESS Videotape Project). Final Report, and Study Guide.

    ERIC Educational Resources Information Center

    Katz, Ruth M.; John, Jane

    The ACCESS video tape series was designed as continuing education for librarians working in public libraries in rural areas of the Rocky Mountain and Plains states. Twelve documentary style and four panel shows were produced. A study guide supplemented the video material and included program outlines and further discussion suggestions. All tapes…

  11. Stream specificity and asymmetries in feature binding and content-addressable access in visual encoding and memory.

    PubMed

    Huynh, Duong L; Tripathy, Srimant P; Bedell, Harold E; Ögmen, Haluk

    2015-01-01

    Human memory is content addressable-i.e., contents of the memory can be accessed using partial information about the bound features of a stored item. In this study, we used a cross-feature cuing technique to examine how the human visual system encodes, binds, and retains information about multiple stimulus features within a set of moving objects. We sought to characterize the roles of three different features (position, color, and direction of motion, the latter two of which are processed preferentially within the ventral and dorsal visual streams, respectively) in the construction and maintenance of object representations. We investigated the extent to which these features are bound together across the following processing stages: during stimulus encoding, sensory (iconic) memory, and visual short-term memory. Whereas all features examined here can serve as cues for addressing content, their effectiveness shows asymmetries and varies according to cue-report pairings and the stage of information processing and storage. Position-based indexing theories predict that position should be more effective as a cue compared to other features. While we found a privileged role for position as a cue at the stimulus-encoding stage, position was not the privileged cue at the sensory and visual short-term memory stages. Instead, the pattern that emerged from our findings is one that mirrors the parallel processing streams in the visual system. This stream-specific binding and cuing effectiveness manifests itself in all three stages of information processing examined here. Finally, we find that the Leaky Flask model proposed in our previous study is applicable to all three features. PMID:26382005

  12. Asymmetric dual-gate-structured one-transistor dynamic random access memory cells for retention characteristics improvement

    NASA Astrophysics Data System (ADS)

    Kim, Hyungjin; Lee, Jong-Ho; Park, Byung-Gook

    2016-08-01

    One of the major concerns of one-transistor dynamic random access memory (1T-DRAM) is poor retention time. In this letter, a 1T-DRAM cell with two separated asymmetric gates was fabricated and evaluated to improve sensing margin and retention characteristics. It was observed that significantly enhanced sensing margin and retention time over 1 s were obtained using a negatively biased second gate and trapped electrons in the nitride layer because of increased hole capacity in the floating body. These findings indicate that the proposed device could serve as a promising candidate for overcoming retention issues of 1T-DRAM cells.

  13. Suppression of relaxation effect in HfO2 resistive random access memory array by improved program operations

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Wu, Huaqiang; Gao, Bin; Dai, Lingjun; Deng, Ning; Sekar, Deepak; Lu, Zhichao; Kellam, Mark; Bronner, Gary; Qian, He

    2016-05-01

    As a postprograming resistance shift, the relaxation effect could be a major issue for resistive random access memory (RRAM) applications. To understand the physical mechanisms of the relaxation effect, temperature-related ion and charge movements are analyzed using the incremental-step-pulse program (ISPP) and repeat-cycle program (RCP). Pre-electron detrapping (PED) operation is found to minimize the amount of interfacial trapped charges and thus to greatly reduce the resistance relaxation effect. Our experimental results demonstrate the improved data retention and tight distribution of RRAM arrays as a result of the above optimized program operations.

  14. High-Performance Pattern Placement Metrology on Dynamic Random Access Memory Layers of 0.25 μm Technology

    NASA Astrophysics Data System (ADS)

    Trube, Jutta; Huber, Hans-Ludwig; Bangert, Carola Bläsing-; Rinn, Klaus; Röth, Klaus-Dieter

    1993-12-01

    Pattern placement metrology is a key function in the evaluation of new manufacturing technology and processes. For future dynamic random access memory (DRAM) generations, ground rules of less than 0.25 μm must be achieved. This paper presents the results of an investigation of the Leitz LMS 2020 laser metrology system from Leica for pattern placement metrology for different layers of DRAM and X-ray mask fabrication processes. The results demonstrate clearly that the new Leitz LMS 2020 tool is well suited for pattern placement control of typical CMOS process wafers and X-ray masks with 30 nm accuracy.

  15. The Hico Image Processing System: A Web-Accessible Hyperspectral Remote Sensing Toolbox

    NASA Astrophysics Data System (ADS)

    Harris, A. T., III; Goodman, J.; Justice, B.

    2014-12-01

    As the quantity of Earth-observation data increases, the use-case for hosting analytical tools in geospatial data centers becomes increasingly attractive. To address this need, HySpeed Computing and Exelis VIS have developed the HICO Image Processing System, a prototype cloud computing system that provides online, on-demand, scalable remote sensing image processing capabilities. The system provides a mechanism for delivering sophisticated image processing analytics and data visualization tools into the hands of a global user community, who will only need a browser and internet connection to perform analysis. Functionality of the HICO Image Processing System is demonstrated using imagery from the Hyperspectral Imager for the Coastal Ocean (HICO), an imaging spectrometer located on the International Space Station (ISS) that is optimized for acquisition of aquatic targets. Example applications include a collection of coastal remote sensing algorithms that are directed at deriving critical information on water and habitat characteristics of our vulnerable coastal environment. The project leverages the ENVI Services Engine as the framework for all image processing tasks, and can readily accommodate the rapid integration of new algorithms, datasets and processing tools.

  16. Opportunities and Barriers to Rural, Remote and First Nation Health Services Research in Canada: Comparing Access to Administrative Claims Data in Manitoba and British Columbia.

    PubMed

    Lavoie, Josée G; Wong, Sabrina; Katz, Alan; Sinclair, Stephanie

    2016-08-01

    Access to geographically disaggregated data is essential for the pursuit of meaningful rural, remote and First Nation health services research. This paper explores the opportunities and challenges associated with undertaking administrative claims data research in the context of two different models of administrative data management: the Manitoba and British Columbia models. We argue that two conditions must be in place to support rural, remote and First Nation health services research: (1) pathways to data access that reconcile the need to protect privacy with the imperative to conduct analyses on disaggregated data; and (2) a trust-based relationship with data providers. PMID:27585026

  17. Memories.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    1998-01-01

    This theme issue of the journal "Exploring" covers the topic of "memories" and describes an exhibition at San Francisco's Exploratorium that ran from May 22, 1998 through January 1999 and that contained over 40 hands-on exhibits, demonstrations, artworks, images, sounds, smells, and tastes that demonstrated and depicted the biological,…

  18. ECOMS-UDG. A User-friendly Data access Gateway to seasonal forecast datasets allowing R-based remote data access, visualization-validation, bias correction and downscaling

    NASA Astrophysics Data System (ADS)

    Santiago Cofiño, Antonio; Gutiérrez, José Manuel; Fernández, Jesús; Bedia, Joaquín; Vega, Manuel; Herrera, Sixto; Frías, María Dolores; Iturbide, Maialen; Magariño, Maria Eugenia; Manzanas, Rodrigo

    2016-04-01

    Seasonal forecasting data from state-or-the-art forecasting systems (e.g. NCEP/CFSv2 or ECMWF/System4) can be obtained directly from the data providers, but the resulting formats, aggregations and vocabularies may not be homogeneous across datasets, requiring some post processing. Moreover, different data policies hold for the various datasets - which are freely available only in some cases - and therefore data access may not be straightforward. Thus, obtaining seasonal climate forecast data is typically a time consuming task. The ECOMS-UDG (User Data Gateway for the ECOMS initiative) has been developed building in the ​User Data Gateway (UDG, http://meteo.unican.es/udg-wiki) in order to facilitate seasonal (re)forecast data access to end users. The required variables have been downloaded from data providers and stored locally in a THREDDS data server implementing fine-grained user authorization. Thus, users can efficiently retrieve the subsets that best suits their particular research aims (typically surface variables for certain regions, periods and/or ensemble members) from a large volume of information. Moreover, an interface layer developed in R allows remote data exploration, access (including homogenization, collocation and sub-setting) and the integration of ECOMS-UDG with a number of R packages developed in the framework of ECOMS for forecast visualization, validation, bias correction and downscaling. This unique framework oriented to climate services allows users from different sectors to easily access seasonal forecasting data (typically surface variables), calibrating and/or downscaling (using upper air information from large scale predictors) this data at local level and validating the different results (using observations). The documentation delivered with the packages includes worked examples showing that the whole visualization, bias correction and/or downscaling tasks requires only a few lines of code and are fully reproducible and adaptable to

  19. Twenty years of Landsat data accessible through the national satellite land remote sensing data archive

    USGS Publications Warehouse

    Larsen, Dana M.

    1993-01-01

    The EROS Data Center has managed to National Satellite Land Remote Sensing Data Archive's (NSLRSDA) Landsat data since 1972. The NSLRSDA includes Landsat MSS data from 1972 through 1991 and T M data from 1982 through 1993. In response to many requests from multi-disciplined users for an enhanced insight into the availability and volume of Landsat data over specific worldwide land areas, numerous world plots and corresponding statical overviews have been prepared. These presentations include information related to image quality, cloud cover, various types of data overage (i.e. regions, countries, path, rows), acquisition station coverage areas, various archive media formats (i.e. wide band video tapes, computer compatible tapes, high density tapes, etc.) and acquisition time periods (i.e. years, seasons). Plans are to publish this information in a paper sample booklet at the Pecora 12 Symposium, in a USGS circular and on a Landsat CD-ROM; the data will be also be incorporated into GLIS.

  20. The Aviation Careers Accessibility Program (ACAP) at Florida Memorial College. Final Report.

    ERIC Educational Resources Information Center

    Florida Memorial Coll., Miami.

    This project, referred to as the Aviation Careers Accessibility Program (ACAP) established a model program for inner-city minority high school students that would allow them information and accessibility to careers and opportunities in the aviation industry. The project featured two program components: an academic year component during and a 5- or…

  1. Realization of a reversible switching in TaO{sub 2} polymorphs via Peierls distortion for resistance random access memory

    SciTech Connect

    Zhu, Linggang; Sun, Zhimei; Zhou, Jian; Guo, Zhonglu

    2015-03-02

    Transition-metal-oxide based resistance random access memory (RRAM) is a promising candidate for next-generation universal non-volatile memories. Searching and designing appropriate materials used in the memories becomes an urgent task. Here, a structure with the TaO{sub 2} formula was predicted using evolutionary algorithms in combination with first-principles calculations. This triclinic structure (T-TaO{sub 2}) is both energetically and dynamically more favorable than the commonly believed rutile structure (R-TaO{sub 2}). The metal-insulator transition (MIT) between metallic R-TaO{sub 2} and T-TaO{sub 2} (band gap: 1.0 eV) is via a Peierls distortion, which makes TaO{sub 2} a potential candidate for RRAM. The energy barrier for the reversible phase transition is 0.19 eV/atom and 0.23 eV/atom, respectively, suggesting low power consumption for the resistance switch. The present findings about the MIT as the resistance-switch mechanism in Ta-O system will stimulate experimental work to fabricate tantalum oxides based RRAM.

  2. Magnetoelectric assisted 180° magnetization switching for electric field addressable writing in magnetoresistive random-access memory.

    PubMed

    Wang, Zhiguang; Zhang, Yue; Wang, Yaojin; Li, Yanxi; Luo, Haosu; Li, Jiefang; Viehland, Dwight

    2014-08-26

    Magnetization-based memories, e.g., hard drive and magnetoresistive random-access memory (MRAM), use bistable magnetic domains in patterned nanomagnets for information recording. Electric field (E) tunable magnetic anisotropy can lower the energy barrier between two distinct magnetic states, promising reduced power consumption and increased recording density. However, integration of magnetoelectric heterostructure into MRAM is a highly challenging task owing to the particular architecture requirements of each component. Here, we show an epitaxial growth of self-assembled CoFe2O4 nanostripes with bistable in-plane magnetizations on Pb(Mg,Nb)O3-PbTiO3 (PMN-PT) substrates, where the magnetic switching can be triggered by E-induced elastic strain effect. An unprecedented magnetic coercive field change of up to 600 Oe was observed with increasing E. A near 180° magnetization rotation can be activated by E in the vicinity of the magnetic coercive field. These findings might help to solve the 1/2-selection problem in traditional MRAM by providing reduced magnetic coercive field in E field selected memory cells. PMID:25093903

  3. Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications (invited)

    NASA Astrophysics Data System (ADS)

    Thomas, Luc; Jan, Guenole; Zhu, Jian; Liu, Huanlong; Lee, Yuan-Jen; Le, Son; Tong, Ru-Ying; Pi, Keyu; Wang, Yu-Jen; Shen, Dongna; He, Renren; Haq, Jesmin; Teng, Jeffrey; Lam, Vinh; Huang, Kenlin; Zhong, Tom; Torng, Terry; Wang, Po-Kang

    2014-05-01

    Magnetic random access memories based on the spin transfer torque phenomenon (STT-MRAMs) have become one of the leading candidates for next generation memory applications. Among the many attractive features of this technology are its potential for high speed and endurance, read signal margin, low power consumption, scalability, and non-volatility. In this paper, we discuss our recent results on perpendicular STT-MRAM stack designs that show STT efficiency higher than 5 kBT/μA, energy barriers higher than 100 kBT at room temperature for sub-40 nm diameter devices, and tunnel magnetoresistance higher than 150%. We use both single device data and results from 8 Mb array to demonstrate data retention sufficient for automotive applications. Moreover, we also demonstrate for the first time thermal stability up to 400 °C exceeding the requirement of Si CMOS back-end processing, thus opening the realm of non-volatile embedded memory to STT-MRAM technology.

  4. The role of the local chemical environment of Ag on the resistive switching mechanism of conductive bridging random access memories.

    PubMed

    Souchier, E; D'Acapito, F; Noé, P; Blaise, P; Bernard, M; Jousseaume, V

    2015-10-01

    Conductive bridging random access memories (CBRAMs) are one of the most promising emerging technologies for the next generation of non-volatile memory. However, the lack of understanding of the switching mechanism at the nanoscale level prevents successful transfer to industry. In this paper, Ag/GeSx/W CBRAM devices are analyzed using depth selective X-ray Absorption Spectroscopy before and after switching. The study of the local environment around Ag atoms in such devices reveals that Ag is in two very distinct environments with short Ag-S bonds due to Ag dissolved in the GeSx matrix, and longer Ag-Ag bonds related to an Ag metallic phase. These experiments allow the conclusion that the switching process involves the formation of metallic Ag nano-filaments initiated at the Ag electrode. All these experimental features are well supported by ab initio molecular dynamics simulations showing that Ag favorably bonds to S atoms, and permit the proposal of a model at the microscopic level that can explain the instability of the conductive state in these Ag-GeSx CBRAM devices. Finally, the principle of the nondestructive method described here can be extended to other types of resistive memory concepts. PMID:26312954

  5. Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications (invited)

    SciTech Connect

    Thomas, Luc Jan, Guenole; Zhu, Jian; Liu, Huanlong; Lee, Yuan-Jen; Le, Son; Tong, Ru-Ying; Pi, Keyu; Wang, Yu-Jen; Shen, Dongna; He, Renren; Haq, Jesmin; Teng, Jeffrey; Lam, Vinh; Huang, Kenlin; Zhong, Tom; Torng, Terry; Wang, Po-Kang

    2014-05-07

    Magnetic random access memories based on the spin transfer torque phenomenon (STT-MRAMs) have become one of the leading candidates for next generation memory applications. Among the many attractive features of this technology are its potential for high speed and endurance, read signal margin, low power consumption, scalability, and non-volatility. In this paper, we discuss our recent results on perpendicular STT-MRAM stack designs that show STT efficiency higher than 5 k{sub B}T/μA, energy barriers higher than 100 k{sub B}T at room temperature for sub-40 nm diameter devices, and tunnel magnetoresistance higher than 150%. We use both single device data and results from 8 Mb array to demonstrate data retention sufficient for automotive applications. Moreover, we also demonstrate for the first time thermal stability up to 400 °C exceeding the requirement of Si CMOS back-end processing, thus opening the realm of non-volatile embedded memory to STT-MRAM technology.

  6. Realization of a reversible switching in TaO2 polymorphs via Peierls distortion for resistance random access memory

    NASA Astrophysics Data System (ADS)

    Zhu, Linggang; Zhou, Jian; Guo, Zhonglu; Sun, Zhimei

    2015-03-01

    Transition-metal-oxide based resistance random access memory (RRAM) is a promising candidate for next-generation universal non-volatile memories. Searching and designing appropriate materials used in the memories becomes an urgent task. Here, a structure with the TaO2 formula was predicted using evolutionary algorithms in combination with first-principles calculations. This triclinic structure (T-TaO2) is both energetically and dynamically more favorable than the commonly believed rutile structure (R-TaO2). The metal-insulator transition (MIT) between metallic R-TaO2 and T-TaO2 (band gap: 1.0 eV) is via a Peierls distortion, which makes TaO2 a potential candidate for RRAM. The energy barrier for the reversible phase transition is 0.19 eV/atom and 0.23 eV/atom, respectively, suggesting low power consumption for the resistance switch. The present findings about the MIT as the resistance-switch mechanism in Ta-O system will stimulate experimental work to fabricate tantalum oxides based RRAM.

  7. In situ observation of nickel as an oxidizable electrode material for the solid-electrolyte-based resistive random access memory

    SciTech Connect

    Sun, Jun; Wu, Xing; Xu, Feng; Xu, Tao; Sun, Litao; Liu, Qi; Xie, Hongwei; Long, Shibing; Lv, Hangbing; Li, Yingtao; Liu, Ming

    2013-02-04

    In this letter, we dynamically investigate the resistive switching characteristics and physical mechanism of the Ni/ZrO{sub 2}/Pt device. The device shows stable bipolar resistive switching behaviors after forming process, which is similar to the Ag/ZrO{sub 2}/Pt and Cu/ZrO{sub 2}/Pt devices. Using in situ transmission electron microscopy, we observe in real time that several conductive filaments are formed across the ZrO{sub 2} layer between Ni and Pt electrodes after forming. Energy-dispersive X-ray spectroscopy results confirm that Ni is the main composition of the conductive filaments. The ON-state resistance increases with increasing temperature, exhibiting the feature of metallic conduction. In addition, the calculated resistance temperature coefficient is equal to that of the 10-30 nm diameter Ni nanowire, further indicating that the nanoscale Ni conductive bridge is the physical origin of the observed conductive filaments. The resistive switching characteristics and the conductive filament's component of Ni/ZrO{sub 2}/Pt device are consistent with the characteristics of the typical solid-electrolyte-based resistive random access memory. Therefore, aside from Cu and Ag, Ni can also be used as an oxidizable electrode material for resistive random access memory applications.

  8. [Co/Ni]-CoFeB hybrid free layer stack materials for high density magnetic random access memory applications

    NASA Astrophysics Data System (ADS)

    Liu, E.; Swerts, J.; Couet, S.; Mertens, S.; Tomczak, Y.; Lin, T.; Spampinato, V.; Franquet, A.; Van Elshocht, S.; Kar, G.; Furnemont, A.; De Boeck, J.

    2016-03-01

    Alternative free layer materials with high perpendicular anisotropy are researched to provide spin-transfer-torque magnetic random access memory stacks' sufficient thermal stability at critical dimensions of 20 nm and below. We demonstrate a high tunnel magetoresistance (TMR) MgO-based magnetic tunnel junction stack with a hybrid free layer design made of a [Co/Ni] multilayer and CoFeB. The seed material on which the [Co/Ni] multilayer is deposited determines its switching characteristics. When deposited on a Pt seed layer, soft magnetic switching behavior with high squareness is obtained. When deposited on a NiCr seed, the perpendicular anisotropy remains high, but the squareness is low and coercivity exceeds 1000 Oe. Interdiffusion of the seed material with the [Co/Ni] multilayers is found to be responsible for the different switching characteristics. In optimized stacks, a TMR of 165% and low resistance-area (RA) product of 7.0 Ω μm2 are attained for free layers with an effective perpendicular magnetic anisotropy energy of 1.25 erg/cm2, which suggests that the hybrid free layer materials may be a viable candidate for high density magnetic random access memory applications.

  9. Hyperlink Format, Categorization Abilities and Memory Span as Contributors to Deaf Users Hypertext Access

    ERIC Educational Resources Information Center

    Farjardo, Inmaculada; Arfe, Barbara; Benedetti, Patrizia; Altoe, Gianmarco

    2008-01-01

    Sixty deaf and hearing students were asked to search for goods in a Hypertext Supermarket with either graphical or textual links of high typicality, frequency, and familiarity. Additionally, they performed a picture and word categorization task and two working memory span tasks (spatial and verbal). Results showed that deaf students were faster in…

  10. Respecting Relations: Memory Access and Antecedent Retrieval in Incremental Sentence Processing

    ERIC Educational Resources Information Center

    Kush, Dave W.

    2013-01-01

    This dissertation uses the processing of anaphoric relations to probe how linguistic information is encoded in and retrieved from memory during real-time sentence comprehension. More specifically, the dissertation attempts to resolve a tension between the demands of a linguistic processor implemented in a general-purpose cognitive architecture and…

  11. Remote Internet access to advanced analytical facilities: a new approach with Web-based services.

    PubMed

    Sherry, N; Qin, J; Fuller, M Suominen; Xie, Y; Mola, O; Bauer, M; McIntyre, N S; Maxwell, D; Liu, D; Matias, E; Armstrong, C

    2012-09-01

    Over the past decade, the increasing availability of the World Wide Web has held out the possibility that the efficiency of scientific measurements could be enhanced in cases where experiments were being conducted at distant facilities. Examples of early successes have included X-ray diffraction (XRD) experimental measurements of protein crystal structures at synchrotrons and access to scanning electron microscopy (SEM) and NMR facilities by users from institutions that do not possess such advanced capabilities. Experimental control, visual contact, and receipt of results has used some form of X forwarding and/or VNC (virtual network computing) software that transfers the screen image of a server at the experimental site to that of the users' home site. A more recent development is a web services platform called Science Studio that provides teams of scientists with secure links to experiments at one or more advanced research facilities. The software provides a widely distributed team with a set of controls and screens to operate, observe, and record essential parts of the experiment. As well, Science Studio provides high speed network access to computing resources to process the large data sets that are often involved in complex experiments. The simple web browser and the rapid transfer of experimental data to a processing site allow efficient use of the facility and assist decision making during the acquisition of the experimental results. The software provides users with a comprehensive overview and record of all parts of the experimental process. A prototype network is described involving X-ray beamlines at two different synchrotrons and an SEM facility. An online parallel processing facility has been developed that analyzes the data in near-real time using stream processing. Science Studio and can be expanded to include many other analytical applications, providing teams of users with rapid access to processed results along with the means for detailed

  12. Performance of a Frequency-Hopped Real-Time Remote Control System in a Multiple Access Scenario

    NASA Astrophysics Data System (ADS)

    Cervantes, Frank

    A recent trend is observed in the context of the radio-controlled aircrafts and automobiles within the hobby grade category and Unmanned Aerial Vehicles (UAV) applications moving to the well-known Industrial, Scientific and Medical (ISM) band. Based on this technological fact, the present thesis evaluates an individual user performance by featuring a multiple-user scenario where several point-to-point co-located real-time Remote Control (RC) applications operate using Frequency Hopping Spread Spectrum (FHSS) as a medium access technique in order to handle interference efficiently. Commercial-off-the-shelf wireless transceivers ready to operate in the ISM band are considered as the operational platform supporting the above-mentioned applications. The impact of channel impairments and of different critical system engineering issues, such as working with real clock oscillators and variable packet duty cycle, are considered. Based on the previous, simulation results allowed us to evaluate the range of variation for those parameters for an acceptable system performance under Multiple Access (MA) environments.

  13. Cost-effective, transfer-free, flexible resistive random access memory using laser-scribed reduced graphene oxide patterning technology.

    PubMed

    Tian, He; Chen, Hong-Yu; Ren, Tian-Ling; Li, Cheng; Xue, Qing-Tang; Mohammad, Mohammad Ali; Wu, Can; Yang, Yi; Wong, H-S Philip

    2014-06-11

    Laser scribing is an attractive reduced graphene oxide (rGO) growth and patterning technology because the process is low-cost, time-efficient, transfer-free, and flexible. Various laser-scribed rGO (LSG) components such as capacitors, gas sensors, and strain sensors have been demonstrated. However, obstacles remain toward practical application of the technology where all the components of a system are fabricated using laser scribing. Memory components, if developed, will substantially broaden the application space of low-cost, flexible electronic systems. For the first time, a low-cost approach to fabricate resistive random access memory (ReRAM) using laser-scribed rGO as the bottom electrode is experimentally demonstrated. The one-step laser scribing technology allows transfer-free rGO synthesis directly on flexible substrates or non-flat substrates. Using this time-efficient laser-scribing technology, the patterning of a memory-array area up to 100 cm(2) can be completed in 25 min. Without requiring the photoresist coating for lithography, the surface of patterned rGO remains as clean as its pristine state. Ag/HfOx/LSG ReRAM using laser-scribing technology is fabricated in this work. Comprehensive electrical characteristics are presented including forming-free behavior, stable switching, reasonable reliability performance and potential for 2-bit storage per memory cell. The results suggest that laser-scribing technology can potentially produce more cost-effective and time-effective rGO-based circuits and systems for practical applications. PMID:24801736

  14. Integration of Radiation-Hard Magnetic Random Access Memory with CMOS ICs

    SciTech Connect

    Cerjan, C.J.; Sigmon, T.W.

    2000-02-15

    The research undertaken in this LDRD-funded project addressed the joint development of magnetic material-based nonvolatile, radiation-hard memory cells with Sandia National Laboratory. Specifically, the goal of this project was to demonstrate the intrinsic radiation-hardness of Giant Magneto-Resistive (GMR) materials by depositing representative alloy combinations upon radiation-hardened silicon-based integrated circuits. All of the stated goals of the project were achieved successfully. The necessary films were successfully deposited upon typical integrated circuits; the materials retained their magnetic field response at the highest radiation doses; and a patterning approach was developed that did not degrade the as-fabricated properties of the underlying circuitry. These results establish the feasibility of building radiation-hard magnetic memory cells.

  15. Remote-access slit-scanning confocal microscope for in vivo tumor diagnosis

    NASA Astrophysics Data System (ADS)

    Sabharwal, Yashvinder Singh

    Microscopic fluorescence imaging of thick biological tissue has been successfully demonstrated with a fiber- based, slit-scanning, confocal microscope. The system developed under this research consists of an illumination arm, a fiber-optic imaging system, and a detection arm. The illumination arm is an anamorphic optical system that converts a circular, laser beam into a cylindrical beam forming a line image at the proximal face of the fiber- optic relay. This relay system is comprised of a fiber- optic imaging bundle, a miniature objective lens, and a miniature hydraulic positioning mechanism. It delivers illumination to a remote sample and simultaneously collects the fluorescence from the sample. The miniature objective lens and positioning mechanism were specially designed and fabricated for this system, allowing for high resolution imaging and optical sectioning in-vivo. The detection arm relays the fluorescence image at the proximal face of the fiber-optic relay with magnification onto a two-dimensional CCD. Characterization of the system has demonstrated a lateral resolution of three microns. The axial resolution when imaging a point object is 10 microns. When imaging a planar object, the axial resolution is 25 microns. Images are acquired at a rate of 2-4 frames per second and the imaging performance has been evaluated with different biological models including animal peritoneal tissue and human prostate tissue in-vitro. In-vivo images of human skin and rat peritoneum have also been acquired to demonstrate that patient motion does not adversely affect the performance of the system. These in-vitro and in vivo images demonstrate the capability of the system to resolve cell nuclear morphology, to visualize cell density and organization, and to image at selected depths below the tissue surface.

  16. On EMDR: eye movements during retrieval reduce subjective vividness and objective memory accessibility during future recall.

    PubMed

    van den Hout, Marcel A; Bartelski, Nicola; Engelhard, Iris M

    2013-01-01

    In eye movement desensitization and reprocessing (EMDR), a treatment for post-traumatic stress disorder (PTSD), patients make eye movements (EM) during trauma recall. Earlier experimental studies found that EM during recall reduces memory vividness during future recalls, and this was taken as laboratory support for the underlying mechanism of EMDR. However, reduced vividness was assessed with self-reports that may be affected by demand characteristics. We tested whether recall+EM also reduces memory vividness on a behavioural reaction time (RT) task. Undergraduates (N=32) encoded two pictures, recalled them, and rated their vividness. In the EM group, one of the pictures was recalled again while making EM. In the no-EM group one of the pictures was recalled without EM. Then fragments from both the recalled and non-recalled pictures, and new fragments were presented and participants rated whether these were (or were not) seen before. Both pictures were rated again for vividness. In the EM group, self-rated vividness of the recalled+EM picture decreased, relative to the non-recalled picture. In the no-EM group there was no difference between the recalled versus non-recalled picture. The RT task showed the same pattern. Reduction of memory vividness due to recall+EM is also evident from non-self-report data. PMID:22765837

  17. An energy-efficient SIMD DSP with multiple VLIW configurations and an advanced memory access unit for LTE-A modem LSIs

    NASA Astrophysics Data System (ADS)

    Tomono, Mitsuru; Ito, Makiko; Nomura, Yoshitaka; Mouri, Makoto; Hirose, Yoshio

    2015-12-01

    Energy efficiency is the most important factor in the design of wireless modem LSIs for mobile handset systems. We have developed an energy-efficient SIMD DSP for LTE-A modem LSIs. Our DSP has mainly two hardware features in order to reduce energy consumption. The first one is multiple VLIW configurations to minimize accesses to instruction memories. The second one is an advanced memory access unit to realize complex memory accesses required for wireless baseband processing. With these features, performance of our DSP is about 1.7 times faster than a base DSP on average for standard LTE-A Libraries. Our DSP achieves about 20% improvement in energy efficiency compared to a base DSP for LTE-A modem LSIs.

  18. An Account of Performance in Accessing Information Stored in Long-Term Memory. A Fixed-Links Model Approach

    ERIC Educational Resources Information Center

    Altmeyer, Michael; Schweizer, Karl; Reiss, Siegbert; Ren, Xuezhu; Schreiner, Michael

    2013-01-01

    Performance in working memory and short-term memory tasks was employed for predicting performance in a long-term memory task in order to find out about the underlying processes. The types of memory were represented by versions of the Posner Task, the Backward Counting Task and the Sternberg Task serving as measures of long-term memory, working…

  19. Intro and Recent Advances: Remote Data Access via OPeNDAP Web Services

    NASA Technical Reports Server (NTRS)

    Fulker, David

    2016-01-01

    During the upcoming Summer 2016 meeting of the ESIP Federation (July 19-22), OpenDAP will hold a Developers and Users Workshop. While a broad set of topics will be covered, a key focus is capitalizing on recent EOSDIS-sponsored advances in Hyrax, OPeNDAPs own software for server-side realization of the DAP2 and DAP4 protocols. These Hyrax advances are as important to data users as to data providers, and the workshop will include hands-on experiences of value to both. Specifically, a balanced set of presentations and hands-on tutorials will address advances in1.server installation,2.server configuration,3.Hyrax aggregation capabilities,4.support for data-access from clients that are HTTP-based, JSON-based or OGC-compliant (especially WCS and WMS),5.support for DAP4,6.use and extension of server-side computational capabilities, and7.several performance-affecting matters. Topics 2 through 7 will be relevant to data consumers, data providers and notably, due to the open-source nature of all OPeNDAP software to developers wishing to extend Hyrax, to build compatible clients and servers, and/or to employ Hyrax as middleware that enables interoperability across a variety of end-user and source-data contexts. A session for contributed talks will elaborate the topics listed above and embrace additional ones.

  20. Virtual Mission Operations of Remote Sensors With Rapid Access To and From Space

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Stewart, Dave; Walke, Jon; Dikeman, Larry; Sage, Steven; Miller, Eric; Northam, James; Jackson, Chris; Taylor, John; Lynch, Scott; Heberle, Jay

    2010-01-01

    This paper describes network-centric operations, where a virtual mission operations center autonomously receives sensor triggers, and schedules space and ground assets using Internet-based technologies and service-oriented architectures. For proof-of-concept purposes, sensor triggers are received from the United States Geological Survey (USGS) to determine targets for space-based sensors. The Surrey Satellite Technology Limited (SSTL) Disaster Monitoring Constellation satellite, the United Kingdom Disaster Monitoring Constellation (UK-DMC), is used as the space-based sensor. The UK-DMC s availability is determined via machine-to-machine communications using SSTL s mission planning system. Access to/from the UK-DMC for tasking and sensor data is via SSTL s and Universal Space Network s (USN) ground assets. The availability and scheduling of USN s assets can also be performed autonomously via machine-to-machine communications. All communication, both on the ground and between ground and space, uses open Internet standards.

  1. Performance and characteristics of double layer porous silicon oxide resistance random access memory

    NASA Astrophysics Data System (ADS)

    Tsai, Tsung-Ming; Chang, Kuan-Chang; Zhang, Rui; Chang, Ting-Chang; Lou, J. C.; Chen, Jung-Hui; Young, Tai-Fa; Tseng, Bae-Heng; Shih, Chih-Cheng; Pan, Yin-Chih; Chen, Min-Chen; Pan, Jhih-Hong; Syu, Yong-En; Sze, Simon M.

    2013-06-01

    A bilayer resistive switching memory device with an inserted porous silicon oxide layer is investigated in this letter. Compared with single Zr:SiOx layer structure, Zr:SiOx/porous SiOx structure outperforms from various aspects, including low operating voltages, tighter distributions of set voltage, higher stability of both low resistance state and high resistance state, and satisfactory endurance characteristics. Electric field simulation by comsolTM Multiphysics is applied, which corroborates that intensive electric field around the pore in porous SiOx layer guides the conduction of electrons. The constraint of conduction path leads to better stabilization and prominent performance of bilayer resistive switching devices.

  2. An analog random access memory in the AVLSI-RA process for an interpolating pad chamber

    SciTech Connect

    Britton, C.L. Jr.; Wittenberg, A.L.; Read, K.F.; Clonts, L.G.; Kennedy, E.J.; Smith, R.S.; Swann, B.K.; Musser, J.A.

    1995-12-01

    An analog memory for an interpolating pad chamber has been designed at Oak Ridge National Laboratory and fabricated by Harris Semiconductor in the AVLSI-RA CMOS process. The goal was to develop a rad-hard analog pipeline that would deliver approximately 9-b performance, a readout settling time of 500 ns following read enable, an input and output dynamic range of {+-} 2.25 V, a corrected rms pedestal of approximately 5 mV or less, and a power dissipation of less than 10 mW/channel. The pre- and post-radiation measurements to 5 MRad are presented.

  3. Utilizing Remote Real-Time Videoconferencing to Expand Access to Cancer Genetic Services in Community Practices: A Multicenter Feasibility Study

    PubMed Central

    Patrick-Miller, Linda; Harris, Diana; Stevens, Evelyn; Egleston, Brian; Smith, Kyle; Mueller, Rebecca; Brandt, Amanda; Stopfer, Jill; Rauch, Shea; Forman, Andrea; Kim, Rebecca; Fetzer, Dominique; Fleisher, Linda; Daly, Mary; Domchek, Susan

    2016-01-01

    Background Videoconferencing has been used to expand medical services to low-access populations and could increase access to genetic services at community sites where in-person visits with genetic providers are not available. Objective To evaluate the feasibility of, patient feedback of, and cognitive and affective responses to remote two-way videoconferencing (RVC) telegenetic services at multiple sociodemographically diverse community practices without access to genetic providers. Methods Patients at 3 community sites in 2 US states outside the host center completed RVC pretest (visit 1, V1) and post-test (visit 2, V2) genetic counseling for cancer susceptibility. Surveys evaluated patient experiences, knowledge, satisfaction with telegenetic and cancer genetics services, anxiety, depression, and cancer worry. Results A total of 82 out of 100 (82.0%) approached patients consented to RVC services. A total of 61 out of 82 patients (74%) completed pretest counseling and 41 out of 61 (67%) proceeded with testing and post-test counseling. A total of 4 out of 41 (10%) mutation carriers were identified: BRCA2, MSH2, and PMS2. Patients reported many advantages (eg, lower travel burden and convenience) and few disadvantages to RVC telegenetic services. Most patients reported feeling comfortable with the video camera—post-V1: 52/57 (91%); post-V2: 39/41 (95%)—and that their privacy was respected—post-V1: 56/57 (98%); post-V2: 40/41 (98%); however, some reported concerns that RVC might increase the risk of a confidentiality breach of their health information—post-V1: 14/57 (25%); post-V2: 12/41 (29%). While the majority of patients reported having no trouble seeing or hearing the genetic counselor—post-V1: 47/57 (82%); post-V2: 39/41 (95%)—51 out of 98 (52%) patients reported technical difficulties. Nonetheless, all patients reported being satisfied with genetic services. Compared to baseline, knowledge increased significantly after pretest counseling (+1

  4. 75 FR 16507 - In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ..., California (``Rambus''). 73 FR 75131-2. The complaint, as amended and supplemented, alleges violations of... Commission's action. See Presidential Memorandum of July 21, 2005, 70 FR 43251 (July 26, 2005). During this... COMMISSION In the Matter of Certain Semiconductor Chips Having Synchronous Dynamic Random Access...

  5. Access to Attitude-Relevant Information in Memory as a Determinant of Attitude-Behavior Consistency.

    ERIC Educational Resources Information Center

    Kallgren, Carl A.; Wood, Wendy

    Recent reserach has attempted to determine systematically how attitudes influence behavior. This research examined whether access to attitude-relevant beliefs and prior experiences would mediate the relation between attitudes and behavior. Subjects were 49 college students with a mean age of 27 who did not live with their parents or in…

  6. Improving Memory after Interruption: Exploiting Soft Constraints and Manipulating Information Access Cost

    ERIC Educational Resources Information Center

    Morgan, Phillip L.; Patrick, John; Waldron, Samuel M.; King, Sophia L.; Patrick, Tanya

    2009-01-01

    Forgetting what one was doing prior to interruption is an everyday problem. The recent soft constraints hypothesis (Gray, Sims, Fu, & Schoelles, 2006) emphasizes the strategic adaptation of information processing strategy to the task environment. It predicts that increasing information access cost (IAC: the time, and physical and mental effort…

  7. A Symptom-Focused Hypnotic Approach to Accessing and Processing Previously Repressed/Dissociated Memories.

    ERIC Educational Resources Information Center

    Ratican, Kathleen L.

    1996-01-01

    The kinesthetic track back technique accesses the origins of current symptoms and may uncover previously repressed/dissociated material, if such material exists in the client's unconscious mind, is relevant to the symptoms, and is ready to be processed consciously. Case examples are given to illustrate proper use of this technique. (LSR)

  8. Fencing network direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2015-07-07

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to a deterministic data communications network through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and the deterministic data communications network; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  9. Fencing network direct memory access data transfers in a parallel active messaging interface of a parallel computer

    DOEpatents

    Blocksome, Michael A.; Mamidala, Amith R.

    2015-07-14

    Fencing direct memory access (`DMA`) data transfers in a parallel active messaging interface (`PAMI`) of a parallel computer, the PAMI including data communications endpoints, each endpoint including specifications of a client, a context, and a task, the endpoints coupled for data communications through the PAMI and through DMA controllers operatively coupled to a deterministic data communications network through which the DMA controllers deliver data communications deterministically, including initiating execution through the PAMI of an ordered sequence of active DMA instructions for DMA data transfers between two endpoints, effecting deterministic DMA data transfers through a DMA controller and the deterministic data communications network; and executing through the PAMI, with no FENCE accounting for DMA data transfers, an active FENCE instruction, the FENCE instruction completing execution only after completion of all DMA instructions initiated prior to execution of the FENCE instruction for DMA data transfers between the two endpoints.

  10. Reducing operation current of Ni-doped silicon oxide resistance random access memory by supercritical CO2 fluid treatment

    NASA Astrophysics Data System (ADS)

    Chang, Kuan-Chang; Tsai, Tsung-Ming; Chang, Ting-Chang; Syu, Yong-En; Wang, Chia-C.; Chuang, Siang-Lan; Li, Cheng-Hua; Gan, Der-Shin; Sze, Simon M.

    2011-12-01

    In the study, we reduced the operation current of resistance random access memory (RRAM) by supercritical CO2 (SCCO2) fluids treatment. The power consumption and joule heating degradation of RRAM device can be improved greatly by SCCO2 treatment. The defect of nickel-doped silicon oxide (Ni:SiOx) was passivated effectively by the supercritical fluid technology. The current conduction of high resistant state in post-treated Ni:SiOx film was transferred to Schottky emission from Frenkel-Pool due to the passivation effect. Additionally, we can demonstrate the passivation mechanism of SCCO2 for Ni:SiOx by material analyses of x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.

  11. Robust Two-Dimensional Stack Capacitor Technologies for 64 Mbit One-Transistor-One-Capacitor Ferroelectric Random Access Memory

    NASA Astrophysics Data System (ADS)

    Jung, Ju-Young; Joo, Heung-Jin; Park, Jung-Hoon; Kang, Seung-Kuk; Kim, Hwi-San; Choi, Do-Yeon; Kim, Jai-Hyun; Lee, Eun-Sun; Hong, Young-Ki; Kim, Hyun-Ho; Jung, Dong-Jin; Kang, Young-Min; Lee, Sung-Yung; Jeong, Hong-Sik; Kim, Kinam

    2007-04-01

    It is very important to develop capacitor module technologies such as robust Pb(ZrxTi1-x)O3 (PZT) film technology at nm scaled PZT thickness and damage minimized ferroelectric capacitor etching technology are crucial for the success of high density one-transistor-one-capacitor (1T1C) ferroelectric random access memory (FRAM). We resolved this issue from the change of the capacitor etching system and optimization of the PZT/SrRuO3 (SRO) deposition process. As a result, we realized a highly reliable sensing window for 64 Mbit 1T1C FRAM that were realized by novel technologies such as robust MOCVD PZT deposition technologies, optimized SRO electrode and damage minimized ferroelectric capacitor etching technologies.

  12. Glprof: A Gprof inspired, Callgraph-oriented Per-Object Disseminating Memory Access Multi-Cache Profiler

    SciTech Connect

    Janjusic, Tommy; Kartsaklis, Christos

    2015-01-01

    Application analysis is facilitated through a number of program profiling tools. The tools vary in their complexity, ease of deployment, design, and profiling detail. Specifically, understand- ing, analyzing, and optimizing is of particular importance for scientific applications where minor changes in code paths and data-structure layout can have profound effects. Understanding how intricate data-structures are accessed and how a given memory system responds is a complex task. In this paper we describe a trace profiling tool, Glprof, specifically aimed to lessen the burden of the programmer to pin-point heavily involved data-structures during an application's run-time, and understand data-structure run-time usage. Moreover, we showcase the tool's modularity using additional cache simulation components. We elaborate on the tool's design, and features. Finally we demonstrate the application of our tool in the context of Spec bench- marks using the Glprof profiler and two concurrently running cache simulators, PPC440 and AMD Interlagos.

  13. Oxide thickness dependence of resistive switching characteristics for Ni/HfOx/Pt resistive random access memory device

    NASA Astrophysics Data System (ADS)

    Ito, Daisuke; Hamada, Yoshihumi; Otsuka, Shintaro; Shimizu, Tomohiro; Shingubara, Shoso

    2015-06-01

    The switching process of the conductive filament formed in Ni/HfOx/Pt resistive random access memory (ReRAM) devices were studied. We evaluated the oxide thickness dependence and temperature dependence of voltage for the Forming, Set and Reset operations for HfOx layers whose thickness are between 3.3 and 6.5 nm. The resistance of conductive filaments showed typical metallic behavior, which suggests Ni filament formation in the HfOx layer. There is a clear dependence of switching voltages for the Set and Reset processes on oxide thickness, which implies that the formation and rupture of conductive filaments occur in the entire thickness range of the HfOx layer. This finding differs from that of a previous study by Yang, which suggests the existence of a constant-thickness switching region. It is suggested that the thickness of the switching region in HfOx may be larger than 6.5 nm.

  14. Guideline model for the bias-scheme-dependent power consumption of a resistive random access memory crossbar array

    NASA Astrophysics Data System (ADS)

    Sun, Wookyung; Choi, Sujin; Lim, Hyein; Shin, Hyungsoon

    2016-04-01

    The 1/2 and 1/3 bias schemes are commonly used to select a cell in a resistive random access memory (ReRAM) crossbar array. The 1/3 bias scheme is advantageous in terms of its write margin but typically requires a higher power consumption than the 1/2 bias scheme. The power consumption of ReRAM can vary according to the nonlinearity of the selector device. In this paper, we propose a power guideline model that suggests selector nonlinearity requirements to guarantee a lower power consumption for the 1/3 bias scheme than for the 1/2 bias scheme. Therefore, the selector nonlinearity requirements for the low power consumption of the 1/3 bias scheme can be immediately obtained using this guideline model without simulation.

  15. Temperature induced complementary switching in titanium oxide resistive random access memory

    NASA Astrophysics Data System (ADS)

    Panda, D.; Simanjuntak, F. M.; Tseng, T.-Y.

    2016-07-01

    On the way towards high memory density and computer performance, a considerable development in energy efficiency represents the foremost aspiration in future information technology. Complementary resistive switch consists of two antiserial resistive switching memory (RRAM) elements and allows for the construction of large passive crossbar arrays by solving the sneak path problem in combination with a drastic reduction of the power consumption. Here we present a titanium oxide based complementary RRAM (CRRAM) device with Pt top and TiN bottom electrode. A subsequent post metal annealing at 400°C induces CRRAM. Forming voltage of 4.3 V is required for this device to initiate switching process. The same device also exhibiting bipolar switching at lower compliance current, Ic <50 μA. The CRRAM device have high reliabilities. Formation of intermediate titanium oxi-nitride layer is confirmed from the cross-sectional HRTEM analysis. The origin of complementary switching mechanism have been discussed with AES, HRTEM analysis and schematic diagram. This paper provides valuable data along with analysis on the origin of CRRAM for the application in nanoscale devices.

  16. Impact of adolescent sucrose access on cognitive control, recognition memory, and parvalbumin immunoreactivity

    PubMed Central

    Killcross, Simon; Hambly, Luke D.; Morris, Margaret J.; Westbrook, R. Fred

    2015-01-01

    In this study we sought to determine the effect of daily sucrose consumption in young rats on their subsequent performance in tasks that involve the prefrontal cortex and hippocampus. High levels of sugar consumption have been associated with the development of obesity, however less is known about how sugar consumption influences behavioral control and high-order cognitive processes. Of particular concern is the fact that sugar intake is greatest in adolescence, an important neurodevelopmental period. We provided sucrose to rats when they were progressing through puberty and adolescence. Cognitive performance was assessed in adulthood on a task related to executive function, a rodent analog of the Stroop task. We found that sucrose-exposed rats failed to show context-appropriate responding during incongruent stimulus compounds presented at test, indicative of impairments in prefrontal cortex function. Sucrose exposed rats also showed deficits in an on object-in-place recognition memory task, indicating that both prefrontal and hippocampal function was impaired. Analysis of brains showed a reduction in expression of parvalbumin-immunoreactive GABAergic interneurons in the hippocampus and prefrontal cortex, indicating that sucrose consumption during adolescence induced long-term pathology, potentially underpinning the cognitive deficits observed. These results suggest that consumption of high levels of sugar-sweetened beverages by adolescents may also impair neurocognitive functions affecting decision-making and memory, potentially rendering them at risk for developing mental health disorders. PMID:25776039

  17. The structure-sensitivity of memory access: evidence from Mandarin Chinese

    PubMed Central

    Dillon, Brian; Chow, Wing-Yee; Wagers, Matthew; Guo, Taomei; Liu, Fengqin; Phillips, Colin

    2014-01-01

    The present study examined the processing of the Mandarin Chinese long-distance reflexive ziji to evaluate the role that syntactic structure plays in the memory retrieval operations that support sentence comprehension. Using the multiple-response speed-accuracy tradeoff (MR-SAT) paradigm, we measured the speed with which comprehenders retrieve an antecedent for ziji. Our experimental materials contrasted sentences where ziji's antecedent was in the local clause with sentences where ziji's antecedent was in a distant clause. Time course results from MR-SAT suggest that ziji dependencies with syntactically distant antecedents are slower to process than syntactically local dependencies. To aid in interpreting the SAT data, we present a formal model of the antecedent retrieval process, and derive quantitative predictions about the time course of antecedent retrieval. The modeling results support the Local Search hypothesis: during syntactic retrieval, comprehenders initially limit memory search to the local syntactic domain. We argue that Local Search hypothesis has important implications for theories of locality effects in sentence comprehension. In particular, our results suggest that not all locality effects may be reduced to the effects of temporal decay and retrieval interference. PMID:25309486

  18. Brain potentials reflect access to visual and emotional memories for faces.

    PubMed

    Bobes, Maria A; Quiñonez, Ileana; Perez, Jhoanna; Leon, Inmaculada; Valdés-Sosa, Mitchell

    2007-05-01

    Familiar faces convey different types of information, unlocking memories related to social-emotional significance. Here, the availability over time of different types of memory was evaluated using the time-course of P3 event related potentials. Two oddball paradigms were employed, both using unfamiliar faces as standards. The infrequent targets were, respectively, artificially-learned faces (devoid of social-emotional content) and faces of acquaintances. Although in both tasks targets were detected accurately, the corresponding time-course and scalp distribution of the P3 responses differed. Artificially-learned and acquaintance faces both elicited a P3b, maximal over centro-parietal sites, and a latency of 500ms. Faces of acquaintances elicited an additional component, an early P3 maximal over frontal sites: with a latency of 350ms. This suggests that visual familiarity can only trigger the overt recognition processes leading to the slower P3b, whereas emotional-social information can also elicit fast and automatic assessments (indexed by the frontal-P3) crucial for successful social interactions. PMID:17350154

  19. ERP evidence for hemispheric asymmetries in exemplar-specific explicit memory access.

    PubMed

    Küper, Kristina; Zimmer, Hubert D

    2015-11-01

    The right cerebral hemisphere (RH) appears to be more effective in representing visual objects as distinct exemplars than the left hemisphere (LH) which is presumably biased towards coding objects at the level of abstract prototypes. As of yet, relatively little is known about the role that asymmetries in exemplar-specificity play at the level of explicit memory retrieval. In the present study, we addressed this issue by examining hemispheric asymmetries in the putative event-related potential (ERP) correlates of familiarity (FN400) and recollection (LPC). In an incidental study phase, pictures of familiar objects were presented centrally. At test, participants performed a memory inclusion task on identical repetitions and different exemplars of study items as well as new items which were presented in only one visual hemifield using the divided visual field technique. With respect to familiarity, we observed exemplar-specific FN400 old/new effects that were more pronounced for identical repetitions than different exemplars, irrespective of the hemisphere governing initial stimulus processing. In contrast, LPC old/new effects were subject to some hemispheric asymmetries indicating that exemplar-specific recollection was more extensive in the RH than in the LH. This further corroborates the idea that hemispheric asymmetries should not be generalized but need to be distinguished not only in different domains but also at different levels of processing. PMID:26279112

  20. Thin Co/Ni-based bottom pinned spin-transfer torque magnetic random access memory stacks with high annealing tolerance

    NASA Astrophysics Data System (ADS)

    Tomczak, Y.; Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Liu, E.; Sankaran, K.; Pourtois, G.; Kim, W.; Souriau, L.; Van Elshocht, S.; Kar, G.; Furnemont, A.

    2016-01-01

    Spin-transfer torque magnetic random access memory (STT-MRAM) is considered as a replacement for next generation embedded and stand-alone memory applications. One of the main challenges in the STT-MRAM stack development is the compatibility of the stack with CMOS process flows in which thermal budgets up to 400 °C are applied. In this letter, we report on a perpendicularly magnetized MgO-based tunnel junction (p-MTJ) on a thin Co/Ni perpendicular synthetic antiferromagnetic layer with high annealing tolerance. Tunnel magneto resistance (TMR) loss after annealing occurs when the reference layer loses its perpendicular magnetic anisotropy due to reduction of the CoFeB/MgO interfacial anisotropy. A stable Co/Ni based p-MTJ stack with TMR values of 130% at resistance-area products of 9 Ω μm2 after 400 °C anneal is achieved via moment control of the Co/Ta/CoFeB reference layer. Thinning of the CoFeB polarizing layer down to 0.8 nm is the key enabler to achieve 400 °C compatibility with limited TMR loss. Thinning the Co below 0.6 nm leads to a loss of the antiferromagnetic interlayer exchange coupling strength through Ru. Insight into the thickness and moment engineering of the reference layer is displayed to obtain the best magnetic properties and high thermal stability for thin Co/Ni SAF-based STT-MRAM stacks.

  1. Evolution of conductive filament and its impact on reliability issues in oxide-electrolyte based resistive random access memory

    PubMed Central

    Lv, Hangbing; Xu, Xiaoxin; Liu, Hongtao; Liu, Ruoyu; Liu, Qi; Banerjee, Writam; Sun, Haitao; Long, Shibing; Li, Ling; Liu, Ming

    2015-01-01

    The electrochemical metallization cell, also referred to as conductive bridge random access memory, is considered to be a promising candidate or complementary component to the traditional charge based memory. As such, it is receiving additional focus to accelerate the commercialization process. To create a successful mass product, reliability issues must first be rigorously solved. In-depth understanding of the failure behavior of the ECM is essential for performance optimization. Here, we reveal the degradation of high resistance state behaves as the majority cases of the endurance failure of the HfO2 electrolyte based ECM cell. High resolution transmission electron microscopy was used to characterize the change in filament nature after repetitive switching cycles. The result showed that Cu accumulation inside the filament played a dominant role in switching failure, which was further supported by measuring the retention of cycle dependent high resistance state and low resistance state. The clarified physical picture of filament evolution provides a basic understanding of the mechanisms of endurance and retention failure, and the relationship between them. Based on these results, applicable approaches for performance optimization can be implicatively developed, ranging from material tailoring to structure engineering and algorithm design. PMID:25586207

  2. Evolution of conductive filament and its impact on reliability issues in oxide-electrolyte based resistive random access memory.

    PubMed

    Lv, Hangbing; Xu, Xiaoxin; Liu, Hongtao; Liu, Ruoyu; Liu, Qi; Banerjee, Writam; Sun, Haitao; Long, Shibing; Li, Ling; Liu, Ming

    2015-01-01

    The electrochemical metallization cell, also referred to as conductive bridge random access memory, is considered to be a promising candidate or complementary component to the traditional charge based memory. As such, it is receiving additional focus to accelerate the commercialization process. To create a successful mass product, reliability issues must first be rigorously solved. In-depth understanding of the failure behavior of the ECM is essential for performance optimization. Here, we reveal the degradation of high resistance state behaves as the majority cases of the endurance failure of the HfO2 electrolyte based ECM cell. High resolution transmission electron microscopy was used to characterize the change in filament nature after repetitive switching cycles. The result showed that Cu accumulation inside the filament played a dominant role in switching failure, which was further supported by measuring the retention of cycle dependent high resistance state and low resistance state. The clarified physical picture of filament evolution provides a basic understanding of the mechanisms of endurance and retention failure, and the relationship between them. Based on these results, applicable approaches for performance optimization can be implicatively developed, ranging from material tailoring to structure engineering and algorithm design. PMID:25586207

  3. The time course of systems consolidation of spatial memory from recent to remote retention: A comparison of the Immediate Early Genes Zif268, c-Fos and Arc.

    PubMed

    Barry, Daniel N; Coogan, Andrew N; Commins, Sean

    2016-02-01

    Systems consolidation is a process involving the stabilisation of memory traces in the neocortex over time. The medial prefrontal cortex becomes increasingly important during the retrieval of older memories, however the timescale of its involvement is unclear, and the contribution of other neocortical brain regions to remote memory have received little attention. The Immediate Early Genes (IEGs) Zif268, c-Fos and Arc have been utilised as markers of neural activity during spatial memory retrieval, however the lack of a direct comparison between them hinders the interpretation of results. To address these questions, we examined the expression of Zif268, Arc and c-Fos protein in the medial prefrontal cortex, as well as the hippocampus, and the entorhinal, perirhinal, retrosplenial and parietal cortices of male Wistar rats following a probe trial of the Morris water maze either one day, seven days, 14 days or 30 days after acquisition. Activity of the medial prefrontal cortex during retrieval, as measured by all three IEGs, increased in correspondence with the age of the memory, reaching significance between 14 and 30 days. Similar increases in c-Fos and Arc were observed over the course of consolidation in other neocortical and parahippocampal areas, however this pattern was not observed with Zif268. Activity of the hippocampus remained largely unchanged across retention intervals. These findings suggest that systems consolidation of spatial memory takes at least two weeks, are consistent with an ongoing role for the hippocampus in the retrieval of spatial memory, and suggest that c-Fos and Arc may be a more sensitive measure of neural activity in response to behavioural tasks than Zif268. PMID:26748021

  4. Coupling of remote alternating-access transport mechanisms for protons and substrates in the multidrug efflux pump AcrB

    PubMed Central

    Eicher, Thomas; Seeger, Markus A; Anselmi, Claudio; Zhou, Wenchang; Brandstätter, Lorenz; Verrey, François; Diederichs, Kay; Faraldo-Gómez, José D; Pos, Klaas M

    2014-01-01

    Membrane transporters of the RND superfamily confer multidrug resistance to pathogenic bacteria, and are essential for cholesterol metabolism and embryonic development in humans. We use high-resolution X-ray crystallography and computational methods to delineate the mechanism of the homotrimeric RND-type proton/drug antiporter AcrB, the active component of the major efflux system AcrAB-TolC in Escherichia coli, and one most complex and intriguing membrane transporters known to date. Analysis of wildtype AcrB and four functionally-inactive variants reveals an unprecedented mechanism that involves two remote alternating-access conformational cycles within each protomer, namely one for protons in the transmembrane region and another for drugs in the periplasmic domain, 50 Å apart. Each of these cycles entails two distinct types of collective motions of two structural repeats, coupled by flanking α-helices that project from the membrane. Moreover, we rationalize how the cross-talk among protomers across the trimerization interface might lead to a more kinetically efficient efflux system. DOI: http://dx.doi.org/10.7554/eLife.03145.001 PMID:25248080

  5. High performance of graphene oxide-doped silicon oxide-based resistance random access memory

    PubMed Central

    2013-01-01

    In this letter, a double active layer (Zr:SiO x /C:SiO x ) resistive switching memory device with outstanding performance is presented. Through current fitting, hopping conduction mechanism is found in both high-resistance state (HRS) and low-resistance state (LRS) of double active layer RRAM devices. By analyzing Raman and FTIR spectra, we observed that graphene oxide exists in C:SiO x layer. Compared with single Zr:SiO x layer structure, Zr:SiO x /C:SiO x structure has superior performance, including low operating current, improved uniformity in both set and reset processes, and satisfactory endurance characteristics, all of which are attributed to the double-layer structure and the existence of graphene oxide flakes formed by the sputter process. PMID:24261454

  6. The role of the inserted layer in resistive random access memory device

    NASA Astrophysics Data System (ADS)

    Zhang, Dainan; Ma, Guokun; Zhang, Huaiwu; Tang, Xiaoli; Zhong, Zhiyong; Jie, Li; Su, Hua

    2016-07-01

    NiO resistive switching devices were fabricated by reactive DC magnetron sputtering at room temperature containing different inserted layers. From measurements, we demonstrated the filaments were made up by metal Co rather than the oxygen defect or other metal. A current jumping phenomenon in the SET process was observed, evidencing that the filament generating procedure was changed due to the inserted layers. In this process, we demonstrate the current jumping appeared in higher voltage region when the position of inserted layer was close to the bottom electrode. The I–V curves shifted to the positive direction as the thickness of inserted layer increasing. With the change of the number of inserted layers, SET voltages varied while the RESET voltage kept stable. According to the electrochemical metallization memory mechanism, detailed explanations on all the phenomena were addressed. This discovery is supposed of great potentials in the use of designing multi-layer RRAM devices.

  7. High performance of graphene oxide-doped silicon oxide-based resistance random access memory.

    PubMed

    Zhang, Rui; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Chen, Kai-Huang; Lou, Jen-Chung; Chen, Jung-Hui; Young, Tai-Fa; Shih, Chih-Cheng; Yang, Ya-Liang; Pan, Yin-Chih; Chu, Tian-Jian; Huang, Syuan-Yong; Pan, Chih-Hung; Su, Yu-Ting; Syu, Yong-En; Sze, Simon M

    2013-01-01

    In this letter, a double active layer (Zr:SiOx/C:SiOx) resistive switching memory device with outstanding performance is presented. Through current fitting, hopping conduction mechanism is found in both high-resistance state (HRS) and low-resistance state (LRS) of double active layer RRAM devices. By analyzing Raman and FTIR spectra, we observed that graphene oxide exists in C:SiOx layer. Compared with single Zr:SiOx layer structure, Zr:SiOx/C:SiOx structure has superior performance, including low operating current, improved uniformity in both set and reset processes, and satisfactory endurance characteristics, all of which are attributed to the double-layer structure and the existence of graphene oxide flakes formed by the sputter process. PMID:24261454

  8. Access to long-term optical memories using photon echoes retrieved from semiconductor spins

    NASA Astrophysics Data System (ADS)

    Langer, L.; Poltavtsev, S. V.; Yugova, I. A.; Salewski, M.; Yakovlev, D. R.; Karczewski, G.; Wojtowicz, T.; Akimov, I. A.; Bayer, M.

    2014-11-01

    The ability to store optical information is important for both classical and quantum communication. Achieving this in a comprehensive manner (converting the optical field into material excitation, storing this excitation, and releasing it after a controllable time delay) is greatly complicated by the many, often conflicting, properties of the material. More specifically, optical resonances in semiconductor quantum structures with high oscillator strength are inevitably characterized by short excitation lifetimes (and, therefore, short optical memory). Here, we present a new experimental approach to stimulated photon echoes by transferring the information contained in the optical field into a spin system, where it is decoupled from the optical vacuum field and may persist much longer. We demonstrate this for an n-doped CdTe/(Cd,Mg)Te quantum well, the storage time of which could be increased by more than three orders of magnitude, from the picosecond range up to tens of nanoseconds.

  9. Distribution of nanoscale nuclei in the amorphous dome of a phase change random access memory

    SciTech Connect

    Lee, Bong-Sub Darmawikarta, Kristof; Abelson, John R.; Raoux, Simone; Shih, Yen-Hao; Zhu, Yu

    2014-02-17

    The nanoscale crystal nuclei in an amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} bit in a phase change memory device were evaluated by fluctuation transmission electron microscopy. The quench time in the device (∼10 ns) afforded more and larger nuclei in the melt-quenched state than in the as-deposited state. However, nuclei were even more numerous and larger in a test structure with a longer quench time (∼100 ns), verifying the prediction of nucleation theory that slower cooling produces more nuclei. It also demonstrates that the thermal design of devices will strongly influence the population of nuclei, and thus the speed and data retention characteristics.

  10. Programming distributed memory architectures using Kali

    NASA Technical Reports Server (NTRS)

    Mehrotra, Piyush; Vanrosendale, John

    1990-01-01

    Programming nonshared memory systems is more difficult than programming shared memory systems, in part because of the relatively low level of current programming environments for such machines. A new programming environment is presented, Kali, which provides a global name space and allows direct access to remote data values. In order to retain efficiency, Kali provides a system on annotations, allowing the user to control those aspects of the program critical to performance, such as data distribution and load balancing. The primitives and constructs provided by the language is described, and some of the issues raised in translating a Kali program for execution on distributed memory systems are also discussed.

  11. Highly reliable switching via phase transition using hydrogen peroxide in homogeneous and multi-layered GaZnO(x)-based resistive random access memory devices.

    PubMed

    Park, Sung Pyo; Yoon, Doo Hyun; Tak, Young Jun; Lee, Heesoo; Kim, Hyun Jae

    2015-06-01

    Here, we propose an effective method for improving the resistive switching characteristics of solution-processed gallium-doped zinc oxide (GaZnO(x)) resistive random access memory (RRAM) devices using hydrogen peroxide. Our results imply that solution processed GaZnO(x) RRAM devices could be one of the candidates for the development of low cost RRAM. PMID:25947353

  12. Robust Three-Metallization Back End of Line Process for 0.18 μm Embedded Ferroelectric Random Access Memory

    NASA Astrophysics Data System (ADS)

    Kang, Seung-Kuk; Rhie, Hyoung-Seub; Kim, Hyun-Ho; Koo, Bon-Jae; Joo, Heung-Jin; Park, Jung-Hun; Kang, Young-Min; Choi, Do-Hyun; Lee, Sung-Young; Jeong, Hong-Sik; Kim, Kinam

    2005-04-01

    We developed ferroelectric random access memory (FRAM)-embedded smartcards in which FRAM replaces electrically erasable PROM (EEPROM) and static random access memory (SRAM) to improve the read/write cycle time and endurance of data memories during operation, in which the main time delay retardation observed in EEPROM embedded smartcards occurs because of slow data update time. EEPROM-embedded smartcards have EEPROM, ROM, and SRAM. To utilize FRAM-embedded smartcards, we should integrate submicron ferroelectric capacitors into embedded logic complementary metal oxide semiconductor (CMOS) without the degradation of the ferroelectric properties. We resolved this process issue from the viewpoint of the back end of line (BEOL) process. As a result, we realized a highly reliable sensing window for FRAM-embedded smartcards that were realized by novel integration schemes such as tungsten and barrier metal (BM) technology, multilevel encapsulating (EBL) layer scheme and optimized intermetallic dielectrics (IMD) technology.

  13. A case study of the Secure Anonymous Information Linkage (SAIL) Gateway: A privacy-protecting remote access system for health-related research and evaluation☆

    PubMed Central

    Jones, Kerina H.; Ford, David V.; Jones, Chris; Dsilva, Rohan; Thompson, Simon; Brooks, Caroline J.; Heaven, Martin L.; Thayer, Daniel S.; McNerney, Cynthia L.; Lyons, Ronan A.

    2014-01-01

    With the current expansion of data linkage research, the challenge is to find the balance between preserving the privacy of person-level data whilst making these data accessible for use to their full potential. We describe a privacy-protecting safe haven and secure remote access system, referred to as the Secure Anonymised Information Linkage (SAIL) Gateway. The Gateway provides data users with a familiar Windows interface and their usual toolsets to access approved anonymously-linked datasets for research and evaluation. We outline the principles and operating model of the Gateway, the features provided to users within the secure environment, and how we are approaching the challenges of making data safely accessible to increasing numbers of research users. The Gateway represents a powerful analytical environment and has been designed to be scalable and adaptable to meet the needs of the rapidly growing data linkage community. PMID:24440148

  14. Distinct Effects of Memory Retrieval and Articulatory Preparation when Learning and Accessing New Word Forms

    PubMed Central

    Nora, Anni; Renvall, Hanna; Kim, Jeong-Young; Service, Elisabet; Salmelin, Riitta

    2015-01-01

    Temporal and frontal activations have been implicated in learning of novel word forms, but their specific roles remain poorly understood. The present magnetoencephalography (MEG) study examines the roles of these areas in processing newly-established word form representations. The cortical effects related to acquiring new phonological word forms during incidental learning were localized. Participants listened to and repeated back new word form stimuli that adhered to native phonology (Finnish pseudowords) or were foreign (Korean words), with a subset of the stimuli recurring four times. Subsequently, a modified 1-back task and a recognition task addressed whether the activations modulated by learning were related to planning for overt articulation, while parametrically added noise probed reliance on developing memory representations during effortful perception. Learning resulted in decreased left superior temporal and increased bilateral frontal premotor activation for familiar compared to new items. The left temporal learning effect persisted in all tasks and was strongest when stimuli were embedded in intermediate noise. In the noisy conditions, native phonotactics evoked overall enhanced left temporal activation. In contrast, the frontal learning effects were present only in conditions requiring overt repetition and were more pronounced for the foreign language. The results indicate a functional dissociation between temporal and frontal activations in learning new phonological word forms: the left superior temporal responses reflect activation of newly-established word-form representations, also during degraded sensory input, whereas the frontal premotor effects are related to planning for articulation and are not preserved in noise. PMID:25961571

  15. INTOR critical issue D: maintainability. Tritium containment and personnel access vs remote maintenance, Chapter VI of the US INTOR report for Phase Two A, Part 2

    SciTech Connect

    Spampinato, P.T.; Finn, P.A.; Gohar, Y.; Yang, S.T.; Stasko, R.R.; Morrison, C.; Russell, S.; Shaw, G.; Bussell, G.T.; Watts, R.

    1984-01-01

    The purpose of this study is to compare the benefits and costs associated with personnel access mmaintenance procedures compared to those of all-remote maintenance procedures. The INTOR Phase Two A, Part I configuration was used to make this comparison. For both approaches, capital and operating costs were considered to first order, maintenance equipment requirements were investigated, maintenance requirements common to both approaches and unique to each were identified, tritium handling requirements were outlined, and maintenance scenarios and device downtime were developed for both. In addition, estimates of person-rem exposure were made for the personnel access approach.

  16. Integration of SrBi2Ta2O9 thin films for high density ferroelectric random access memory

    NASA Astrophysics Data System (ADS)

    Wouters, D. J.; Maes, D.; Goux, L.; Lisoni, J. G.; Paraschiv, V.; Johnson, J. A.; Schwitters, M.; Everaert, J.-L.; Boullart, W.; Schaekers, M.; Willegems, M.; Vander Meeren, H.; Haspeslagh, L.; Artoni, C.; Caputa, C.; Casella, P.; Corallo, G.; Russo, G.; Zambrano, R.; Monchoix, H.; Vecchio, G.; Van Autryve, L.

    2006-09-01

    Ferroelectric random access memory (FeRAM) is an attractive candidate technology for embedded nonvolatile memory, especially in applications where low power and high program speed are important. Market introduction of high-density FeRAM is, however, lagging behind standard complementary metal-oxide semiconductor (CMOS) because of the difficult integration technology. This paper discusses the major integration issues for high-density FeRAM, based on SrBi2Ta2O9 (strontium bismuth tantalate or SBT), in relation to the fabrication of our stacked cell structure. We have worked in the previous years on the development of SBT-FeRAM integration technology, based on a so-called pseudo-three-dimensional (3D) cell, with a capacitor that can be scaled from quasi two-dimensional towards a true three-dimensional capacitor where the sidewalls will importantly contribute to the signal. In the first phase of our integration development, we integrated our FeRAM cell in a 0.35μm CMOS technology. In a second phase, then, possibility of scaling of our cell is demonstrated in 0.18μm technology. The excellent electrical and reliability properties of the small integrated ferroelectric capacitors prove the feasibility of the technology, while the verification of the potential 3D effect confirms the basic scaling potential of our concept beyond that of the single-mask capacitor. The paper outlines the different material and technological challenges, and working solutions are demonstrated. While some issues are specific to our own cell, many are applicable to different stacked FeRAM cell concepts, or will become more general concerns when more developments are moving into 3D structures.

  17. Recent versus Remote: Flashbulb Memory for 9/11 and Self-Selected Events from the Reminiscence Bump

    ERIC Educational Resources Information Center

    Denver, Jenny Y.; Lane, Sean M.; Cherry, Katie E.

    2010-01-01

    In two related studies, we examined flashbulb memories acquired from different points in the lifespan in younger and older adults. When asked to remember flashbulb memories from their lives, older adults were most likely to recall events from the reminiscence bump (Study 1A). In Study 1B, younger and older adults recalled 9/11 and a personal…

  18. A 0.5-V Six-Transistor Static Random Access Memory with Ferroelectric-Gate Field Effect Transistors

    NASA Astrophysics Data System (ADS)

    Tanakamaru, Shuhei; Hatanaka, Teruyoshi; Yajima, Ryoji; Miyaji, Kousuke; Takahashi, Mitsue; Sakai, Shigeki; Takeuchi, Ken

    2010-12-01

    A 0.5 V six-transistor static random access memory (6T-SRAM) with ferroelectric-gate field-effect-transistors (Fe-FETs) is proposed and experimentally demonstrated for the first time. During the read and the hold, the threshold voltage (VTH) of Fe-FETs automatically changes to increase the static noise margin (SNM) by 60%. During the stand-by, the VTH of the proposed SRAM cell increases to decrease the leakage current by 42%. In case of the read, the VTH of the read transistor decreases and increases the cell read current to achieve the fast read. During the write, the VTH of the SRAM cell dynamically changes and assist the cell data to flip, realizing a write assist function. The enlarged SNM realizes the VDD reduction by 0.11 V, which decreases the active power by 32%. The proposed SRAM layout is the same as the conventional 6T-SRAM and there is no area penalty.

  19. Resistance switching behavior of ZnO resistive random access memory with a reduced graphene oxide capping layer

    NASA Astrophysics Data System (ADS)

    Lin, Cheng-Li; Chang, Wei-Yi; Huang, Yen-Lun; Juan, Pi-Chun; Wang, Tse-Wen; Hung, Ke-Yu; Hsieh, Cheng-Yu; Kang, Tsung-Kuei; Shi, Jen-Bin

    2015-04-01

    In this work, we investigate the characteristics of ZnO resistive random access memory (RRAM) with a reduced graphene oxide (rGO) capping layer and the polarity effect of the SET/RESET bias on the RRAM. The rGO film insertion enhances the stability of the current-voltage (I-V) switching curve and the superior resistance ratio (˜105) of high-resistance state (HRS) to low-resistance state (LRS). Using the appropriate polarity of the SET/RESET bias applied to the rGO-capped ZnO RRAM enables the oxygen ions to move mainly at the interface of the rGO and ZnO films, resulting in the best performance. Presumably, the rGO film acts as an oxygen reservoir and enhances the easy in and out motion of the oxygen ions from the rGO film. The rGO film also prevents the interaction of oxygen ions and the Al electrode, resulting in excellent performance. In a pulse endurance test, the rGO-capped ZnO RRAM reveals superior endurance of up to 108 cycles over that of the ZnO RRAM without rGO insertion (106 cycles).

  20. Effects of different dopants on switching behavior of HfO2-based resistive random access memory

    NASA Astrophysics Data System (ADS)

    Deng, Ning; Pang, Hua; Wu, Wei

    2014-10-01

    In this study the effects of doping atoms (Al, Cu, and N) with different electro-negativities and ionic radii on resistive switching of HfO2-based resistive random access memory (RRAM) are systematically investigated. The results show that forming voltages and set voltages of Al/Cu-doped devices are reduced. Among all devices, Cu-doped device shows the narrowest device-to-device distributions of set voltage and low resistance. The effects of different dopants on switching behavior are explained with deferent types of CFs formed in HfO2 depending on dopants: oxygen vacancy (Vo) filaments for Al-doped HfO2 devices, hybrid filaments composed of oxygen vacancies and Cu atoms for Cu-doped HfO2 devices, and nitrogen/oxygen vacancy filaments for N-doped HfO2 devices. The results suggest that a metal dopant with a larger electro-negativity than host metal atom offers the best comprehensive performance.

  1. Cu impurity in insulators and in metal-insulator-metal structures: Implications for resistance-switching random access memories

    SciTech Connect

    Pandey, Sumeet C. Meade, Roy; Sandhu, Gurtej S.

    2015-02-07

    We present numerical results from atomistic simulations of Cu in SiO{sub 2} and Al{sub 2}O{sub 3}, with an emphasis on the thermodynamic, kinetic, and electronic properties. The calculated properties of Cu impurity at various concentrations (9.91 × 10{sup 20 }cm{sup −3} and 3.41 × 10{sup 22 }cm{sup −3}) in bulk oxides are presented. The metal-insulator interfaces result in up to a ∼4 eV reduction in the formation energies relative to the crystalline bulk. Additionally, the importance of Cu-Cu interaction in lowering the chemical potential is introduced. These concepts are then discussed in the context of formation and stability of localized conductive paths in resistance-switching Random Access Memories (RRAM-M). The electronic density of states and non-equilibrium transmission through these localized paths are studied, confirming conduction by showing three orders of magnitude increase in the electron transmission. The dynamic behavior of the conductive paths is investigated with atomistic drift-diffusion calculations. Finally, the paper concludes with a molecular dynamics simulation of a RRAM-M cell that attempts to combine the aforementioned phenomena in one self-consistent model.

  2. Low leakage ZrO2 based capacitors for sub 20 nm dynamic random access memory technology nodes

    NASA Astrophysics Data System (ADS)

    Pešić, Milan; Knebel, Steve; Geyer, Maximilian; Schmelzer, Sebastian; Böttger, Ulrich; Kolomiiets, Nadiia; Afanas'ev, Valeri V.; Cho, Kyuho; Jung, Changhwa; Chang, Jaewan; Lim, Hanjin; Mikolajick, Thomas; Schroeder, Uwe

    2016-02-01

    During dynamic random access memory (DRAM) capacitor scaling, a lot of effort was put searching for new material stacks to overcome the scaling limitations of the current material stack, such as leakage and sufficient capacitance. In this study, very promising results for a SrTiO3 based capacitor with a record low capacitance equivalent thickness value of 0.2 nm at target leakage current are presented. Due to the material properties of SrTiO3 films (high vacancy concentration and low band gap), which are leading to an increased leakage current, a physical thickness of at least 8 nm is required at target leakage specifications. However, this physical thickness would not fit into an 18 nm DRAM structure. Therefore, two different new approaches to develop a new ZrO2 based DRAM capacitor stack by changing the inter-layer material from Al2O3 to SrO and the exchange of the top electrode material from TiN to Pt are presented. A combination of these two approaches leads to a capacitance equivalent thickness value of 0.47 nm. Most importantly, the physical thickness of <5 nm for the dielectric stack is in accordance with the target specifications. Detailed evaluation of the leakage current characteristics leads to a capacitor model which allows the prediction of the electrical behavior with thickness scaling.

  3. Switching characteristics in Cu:SiO2 by chemical soak methods for resistive random access memory (ReRAM)

    NASA Astrophysics Data System (ADS)

    Chin, Fun-Tat; Lin, Yu-Hsien; Yang, Wen-Luh; Liao, Chin-Hsuan; Lin, Li-Min; Hsiao, Yu-Ping; Chao, Tien-Sheng

    2015-01-01

    A limited copper (Cu)-source Cu:SiO2 switching layer composed of various Cu concentrations was fabricated using a chemical soaking (CS) technique. The switching layer was then studied for developing applications in resistive random access memory (ReRAM) devices. Observing the resistive switching mechanism exhibited by all the samples suggested that Cu conductive filaments formed and ruptured during the set/reset process. The experimental results indicated that the endurance property failure that occurred was related to the joule heating effect. Moreover, the endurance switching cycle increased as the Cu concentration decreased. In high-temperature tests, the samples demonstrated that the operating (set/reset) voltages decreased as the temperature increased, and an Arrhenius plot was used to calculate the activation energy of the set/reset process. In addition, the samples demonstrated stable data retention properties when baked at 85 °C, but the samples with low Cu concentrations exhibited short retention times in the low-resistance state (LRS) during 125 °C tests. Therefore, Cu concentration is a crucial factor in the trade-off between the endurance and retention properties; furthermore, the Cu concentration can be easily modulated using this CS technique.

  4. A Characterization of Endurance in 64 Mbit Ferroelectric Random Access Memory by Analyzing the Space Charge Concentration

    NASA Astrophysics Data System (ADS)

    Lee, Eun Sun; Jung, Dong Jin; Kang, Young Min; Kim, Hyun Ho; Hong, Young Ki; Park, Jung Hoon; Kuk Kang, Seung; Kim, Jae Hyun; San Kim, Hee; Jung, Won Woong; Ahn, Woo Song; Jung, Ju Young; Kang, Jin Young; Choi, Do Yeon; Goh, Han Kyung; Kim, Song Yi; Lee, Sang Young; Jeong, Hong Sik

    2008-04-01

    Space charge concentration due to fatigue cycles was examined with an adequate modeling in order to expect read/write endurance of a 64 Mbit one-transistor and one-capacitor (1T1C) ferroelectric random access memory (FRAM). For monitoring the change in space charge concentration according to fatigue cycles, we assumed that our ferroelectric capacitor is governed by a partially depleted Schottky conduction model. With this, the space charge concentration at the each decade of the fatigue cycles was calculated by measuring the current-voltage characteristics. The space charge concentration at the initial stage was evaluated into 1.95 ×1020 and 2.16 ×1020/cm3 after the 1011 cycles. The concentration of 2.29 ×1020/cm3 was expected at the fatigue cycles of 1016 through a linear regression of the concentration plot against fatigue cycles. Accordingly, it could be said that our ferroelectric capacitor has few problems of endurance up to the 1016 cycles considering the concentration of ˜1020 and the film thickness of 80 nm. Other empirical data obtained in the capacitor level after full integration are supporting this expectation as well.

  5. Switching characteristics for ferroelectric random access memory based on RC model in poly(vinylidene fluoride-trifluoroethylene) ultrathin films

    NASA Astrophysics Data System (ADS)

    Liu, ChangLi; Wang, XueJun; Zhang, XiuLi; Du, XiaoLi; Xu, HaiSheng

    2016-05-01

    The switching characteristic of the poly(vinylidene fluoride-trifluoroethlene) (P(VDF-TrFE)) films have been studied at different ranges of applied electric field. It is suggest that the increase of the switching speed upon nucleation protocol and the deceleration of switching could be related to the presence of a non-ferroelectric layer. Remarkably, a capacitor and resistor (RC) links model plays significant roles in the polarization switching dynamics of the thin films. For P(VDF-TrFE) ultrathin films with electroactive interlayer, it is found that the switching dynamic characteristics are strongly affected by the contributions of resistor and non-ferroelectric (non-FE) interface factors. A corresponding experiment is designed using poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic) (PEDOT-PSSH) as interlayer with different proton concentrations, and the testing results show that the robust switching is determined by the proton concentration in interlayer and lower leakage current in circuit to reliable applications of such polymer films. These findings provide a new feasible method to enhance the polarization switching for the ferroelectric random access memory.

  6. Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance

    NASA Astrophysics Data System (ADS)

    Dawson, J. A.; Guo, Y.; Robertson, J.

    2015-09-01

    Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour.

  7. Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance

    SciTech Connect

    Dawson, J. A. Guo, Y.; Robertson, J.

    2015-09-21

    Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour.

  8. Vividness of Visual Imagery and Incidental Recall of Verbal Cues, When Phenomenological Availability Reflects Long-Term Memory Accessibility

    PubMed Central

    D’Angiulli, Amedeo; Runge, Matthew; Faulkner, Andrew; Zakizadeh, Jila; Chan, Aldrich; Morcos, Selvana

    2013-01-01

    The relationship between vivid visual mental images and unexpected recall (incidental recall) was replicated, refined, and extended. In Experiment 1, participants were asked to generate mental images from imagery-evoking verbal cues (controlled on several verbal properties) and then, on a trial-by-trial basis, rate the vividness of their images; 30 min later, participants were surprised with a task requiring free recall of the cues. Higher vividness ratings predicted better incidental recall of the cues than individual differences (whose effect was modest). Distributional analysis of image latencies through ex-Gaussian modeling showed an inverse relation between vividness and latency. However, recall was unrelated to image latency. The follow-up Experiment 2 showed that the processes underlying trial-by-trial vividness ratings are unrelated to the Vividness of Visual Imagery Questionnaire (VVIQ), as further supported by a meta-analysis of a randomly selected sample of relevant literature. The present findings suggest that vividness may act as an index of availability of long-term sensory traces, playing a non-epiphenomenal role in facilitating the access of those memories. PMID:23382719

  9. Calculation of energy-barrier lowering by incoherent switching in spin-transfer torque magnetoresistive random-access memory

    SciTech Connect

    Munira, Kamaram; Visscher, P. B.

    2015-05-07

    To make a useful spin-transfer torque magnetoresistive random-access memory (STT-MRAM) device, it is necessary to be able to calculate switching rates, which determine the error rates of the device. In a single-macrospin model, one can use a Fokker-Planck equation to obtain a low-current thermally activated rate ∝exp(−E{sub eff}/k{sub B}T). Here, the effective energy barrier E{sub eff} scales with the single-macrospin energy barrier KV, where K is the effective anisotropy energy density and V the volume. A long-standing paradox in this field is that the actual energy barrier appears to be much smaller than this. It has been suggested that incoherent motions may lower the barrier, but this has proved difficult to quantify. In the present paper, we show that the coherent precession has a magnetostatic instability, which allows quantitative estimation of the energy barrier and may resolve the paradox.

  10. Finding Oxygen Reservoir by Using Extremely Small Test Cell Structure for Resistive Random Access Memory with Replaceable Bottom Electrode

    PubMed Central

    Kinoshita, Kentaro; Koh, Sang-Gyu; Moriyama, Takumi; Kishida, Satoru

    2015-01-01

    Although the presence of an oxygen reservoir (OR) is assumed in many models that explain resistive switching of resistive random access memory (ReRAM) with electrode/metal oxide (MO)/electrode structures, the location of OR is not clear. We have previously reported a method, which involved the use of an AFM cantilever, for preparing an extremely small ReRAM cell that has a removable bottom electrode (BE). In this study, we used this cell structure to specify the location of OR. Because an anode is often assumed to work as OR, we investigated the effect of changing anodes without changing the MO layer and the cathode on the occurrence of reset. It was found that the reset occurred independently of the catalytic ability and Gibbs free energy (ΔG) of the anode. Our proposed structure enabled to determine that the reset was caused by repairing oxygen vacancies of which a filament consists due to the migration of oxygen ions from the surrounding area when high ΔG anode metal is used, whereas by oxidizing the anode due to the migration of oxygen ions from the MO layer when low ΔG anode metal is used, suggesting the location of OR depends on ΔG of the anode. PMID:26689682

  11. Finding Oxygen Reservoir by Using Extremely Small Test Cell Structure for Resistive Random Access Memory with Replaceable Bottom Electrode.

    PubMed

    Kinoshita, Kentaro; Koh, Sang-Gyu; Moriyama, Takumi; Kishida, Satoru

    2015-01-01

    Although the presence of an oxygen reservoir (OR) is assumed in many models that explain resistive switching of resistive random access memory (ReRAM) with electrode/metal oxide (MO)/electrode structures, the location of OR is not clear. We have previously reported a method, which involved the use of an AFM cantilever, for preparing an extremely small ReRAM cell that has a removable bottom electrode (BE). In this study, we used this cell structure to specify the location of OR. Because an anode is often assumed to work as OR, we investigated the effect of changing anodes without changing the MO layer and the cathode on the occurrence of reset. It was found that the reset occurred independently of the catalytic ability and Gibbs free energy (ΔG) of the anode. Our proposed structure enabled to determine that the reset was caused by repairing oxygen vacancies of which a filament consists due to the migration of oxygen ions from the surrounding area when high ΔG anode metal is used, whereas by oxidizing the anode due to the migration of oxygen ions from the MO layer when low ΔG anode metal is used, suggesting the location of OR depends on ΔG of the anode. PMID:26689682

  12. Finding Oxygen Reservoir by Using Extremely Small Test Cell Structure for Resistive Random Access Memory with Replaceable Bottom Electrode

    NASA Astrophysics Data System (ADS)

    Kinoshita, Kentaro; Koh, Sang-Gyu; Moriyama, Takumi; Kishida, Satoru

    2015-12-01

    Although the presence of an oxygen reservoir (OR) is assumed in many models that explain resistive switching of resistive random access memory (ReRAM) with electrode/metal oxide (MO)/electrode structures, the location of OR is not clear. We have previously reported a method, which involved the use of an AFM cantilever, for preparing an extremely small ReRAM cell that has a removable bottom electrode (BE). In this study, we used this cell structure to specify the location of OR. Because an anode is often assumed to work as OR, we investigated the effect of changing anodes without changing the MO layer and the cathode on the occurrence of reset. It was found that the reset occurred independently of the catalytic ability and Gibbs free energy (ΔG) of the anode. Our proposed structure enabled to determine that the reset was caused by repairing oxygen vacancies of which a filament consists due to the migration of oxygen ions from the surrounding area when high ΔG anode metal is used, whereas by oxidizing the anode due to the migration of oxygen ions from the MO layer when low ΔG anode metal is used, suggesting the location of OR depends on ΔG of the anode.

  13. Design and Fabrication of Nereid-UI: A Remotely Operated Underwater Vehicle for Oceanographic Access Under Ice

    NASA Astrophysics Data System (ADS)

    Whitcomb, L. L.; Bowen, A. D.; Yoerger, D.; German, C. R.; Kinsey, J. C.; Mayer, L. A.; Jakuba, M. V.; Gomez-Ibanez, D.; Taylor, C. L.; Machado, C.; Howland, J. C.; Kaiser, C. L.; Heintz, M.; Pontbriand, C.; Suman, S.; O'hara, L.

    2013-12-01

    The Woods Hole Oceanographic Institution and collaborators from the Johns Hopkins University and the University of New Hampshire are developing for the Polar Science Community a remotely-controlled underwater robotic vehicle capable of being tele-operated under ice under remote real-time human supervision. The Nereid Under-Ice (Nereid-UI) vehicle will enable exploration and detailed examination of biological and physical environments at glacial ice-tongues and ice-shelf margins, delivering high-definition video in addition to survey data from on board acoustic, chemical, and biological sensors. Preliminary propulsion system testing indicates the vehicle will be able to attain standoff distances of up to 20 km from an ice-edge boundary, as dictated by the current maximum tether length. The goal of the Nereid-UI system is to provide scientific access to under-ice and ice-margin environments that is presently impractical or infeasible. FIBER-OPTIC TETHER: The heart of the Nereid-UI system is its expendable fiber optic telemetry system. The telemetry system utilizes many of the same components pioneered for the full-ocean depth capable HROV Nereus vehicle, with the addition of continuous fiber status monitoring, and new float-pack and depressor designs that enable single-body deployment. POWER SYSTEM: Nereid-UI is powered by a pressure-tolerant lithium-ion battery system composed of 30 Ah prismatic pouch cells, arranged on a 90 volt bus and capable of delivering 15 kW. The cells are contained in modules of 8 cells, and groups of 9 modules are housed together in oil-filled plastic boxes. The power distribution system uses pressure tolerant components extensively, each of which have been individually qualified to 10 kpsi and operation between -20 C and 40 C. THRUSTERS: Nereid-UI will employ eight identical WHOI-designed thrusters, each with a frameless motor, oil-filled and individually compensated, and designed for low-speed (500 rpm max) direct drive. We expect an end

  14. Total ionizing dose effect of γ-ray radiation on the switching characteristics and filament stability of HfOx resistive random access memory

    SciTech Connect

    Fang, Runchen; Yu, Shimeng; Gonzalez Velo, Yago; Chen, Wenhao; Holbert, Keith E.; Kozicki, Michael N.; Barnaby, Hugh

    2014-05-05

    The total ionizing dose (TID) effect of gamma-ray (γ-ray) irradiation on HfOx based resistive random access memory was investigated by electrical and material characterizations. The memory states can sustain TID level ∼5.2 Mrad (HfO{sub 2}) without significant change in the functionality or the switching characteristics under pulse cycling. However, the stability of the filament is weakened after irradiation as memory states are more vulnerable to flipping under the electrical stress. X-ray photoelectron spectroscopy was performed to ascertain the physical mechanism of the stability degradation, which is attributed to the Hf-O bond breaking by the high-energy γ-ray exposure.

  15. Resistive Switching Behavior in Organic-Inorganic Hybrid CH3 NH3 PbI3-x Clx Perovskite for Resistive Random Access Memory Devices.

    PubMed

    Yoo, Eun Ji; Lyu, Miaoqiang; Yun, Jung-Ho; Kang, Chi Jung; Choi, Young Jin; Wang, Lianzhou

    2015-10-28

    The CH3 NH3 PbI3- x Clx organic-inorganic hybrid perovskite material demonstrates remarkable resistive switching behavior, which can be applicable in resistive random access memory devices. The simply designed Au/CH3 NH3 PbI3- x Clx /FTO structure is fabricated by a low-temperature, solution-processable method, which exhibits remarkable bipolar resistive switching and nonvolatile properties. PMID:26331363

  16. Late Enrichment Maintains Accurate Recent and Remote Spatial Memory Only in Aged Rats That Were Unimpaired When Middle Aged

    ERIC Educational Resources Information Center

    Fuchs, Fanny; Herbeaux, Karine; Aufrere, Noémie; Kelche, Christian; Mathis, Chantal; Barbelivien, Alexandra; Majchrzak, Monique

    2016-01-01

    Exposure of rodents to a stimulating environment has beneficial effects on some cognitive functions that are impaired during physiological aging, and especially spatial reference memory. The present study investigated whether environmental enrichment rescues these functions in already declining subjects and/or protects them from subsequent…

  17. You Can't Get There from Here: Issues in Remote Access to Electronic Journals for a Health Sciences Library.

    ERIC Educational Resources Information Center

    Krieb, Dennis

    1999-01-01

    Discusses experiences of the Saint Louis University's Health Sciences Center Library in providing access to electronic journals to a dispersed constituency. Topics include IP (institutional password) filtering, how publishers and aggregators establish access control, credential-based authentication, and proxy servers. (Author/LRW)

  18. Memory protection

    NASA Technical Reports Server (NTRS)

    Denning, Peter J.

    1988-01-01

    Accidental overwriting of files or of memory regions belonging to other programs, browsing of personal files by superusers, Trojan horses, and viruses are examples of breakdowns in workstations and personal computers that would be significantly reduced by memory protection. Memory protection is the capability of an operating system and supporting hardware to delimit segments of memory, to control whether segments can be read from or written into, and to confine accesses of a program to its segments alone. The absence of memory protection in many operating systems today is the result of a bias toward a narrow definition of performance as maximum instruction-execution rate. A broader definition, including the time to get the job done, makes clear that cost of recovery from memory interference errors reduces expected performance. The mechanisms of memory protection are well understood, powerful, efficient, and elegant. They add to performance in the broad sense without reducing instruction execution rate.

  19. Implementation of nitrogen-doped titanium-tungsten tunable heater in phase change random access memory and its effects on device performance

    SciTech Connect

    Tan, Chun Chia; Zhao, Rong Chong, Tow Chong; Shi, Luping

    2014-10-13

    Nitrogen-doped titanium-tungsten (N-TiW) was proposed as a tunable heater in Phase Change Random Access Memory (PCRAM). By tuning N-TiW's material properties through doping, the heater can be tailored to optimize the access speed and programming current of PCRAM. Experiments reveal that N-TiW's resistivity increases and thermal conductivity decreases with increasing nitrogen-doping ratio, and N-TiW devices displayed (∼33% to ∼55%) reduced programming currents. However, there is a tradeoff between the current and speed for heater-based PCRAM. Analysis of devices with different N-TiW heaters shows that N-TiW doping levels could be optimized to enable low RESET currents and fast access speeds.

  20. Health, Healthcare Access, and Use of Traditional Versus Modern Medicine in Remote Peruvian Amazon Communities: A Descriptive Study of Knowledge, Attitudes, and Practices

    PubMed Central

    Williamson, Jonathan; Ramirez, Ronald; Wingfield, Tom

    2015-01-01

    There is an urgent need for healthcare research, funding, and infrastructure in the Peruvian Amazon. We performed a descriptive study of health, health knowledge and practice, and healthcare access of 13 remote communities of the Manatí and Amazon Rivers in northeastern Peru. Eighty-five adults attending a medical boat service were interviewed to collect data on socioeconomic position, health, diagnosed illnesses, pain, healthcare access, and traditional versus modern medicine use. In this setting, poverty and gender inequality were prevalent, and healthcare access was limited by long distances to the health post and long waiting times. There was a high burden of reported pain (mainly head and musculoskeletal) and chronic non-communicable diseases, such as hypertension (19%). Nearly all participants felt that they did not completely understand their diagnosed illnesses and wanted to know more. Participants preferred modern over traditional medicine, predominantly because of mistrust or lack of belief in traditional medicine. Our findings provide novel evidence concerning transitional health beliefs, hidden pain, and chronic non-communicable disease prevalence in marginalized communities of the Peruvian Amazon. Healthcare provision was limited by a breach between health education, knowledge, and access. Additional participatory research with similar rural populations is required to inform regional healthcare policy and decision-making. PMID:25688165

  1. Health, healthcare access, and use of traditional versus modern medicine in remote Peruvian Amazon communities: a descriptive study of knowledge, attitudes, and practices.

    PubMed

    Williamson, Jonathan; Ramirez, Ronald; Wingfield, Tom

    2015-04-01

    There is an urgent need for healthcare research, funding, and infrastructure in the Peruvian Amazon. We performed a descriptive study of health, health knowledge and practice, and healthcare access of 13 remote communities of the Manatí and Amazon Rivers in northeastern Peru. Eighty-five adults attending a medical boat service were interviewed to collect data on socioeconomic position, health, diagnosed illnesses, pain, healthcare access, and traditional versus modern medicine use. In this setting, poverty and gender inequality were prevalent, and healthcare access was limited by long distances to the health post and long waiting times. There was a high burden of reported pain (mainly head and musculoskeletal) and chronic non-communicable diseases, such as hypertension (19%). Nearly all participants felt that they did not completely understand their diagnosed illnesses and wanted to know more. Participants preferred modern over traditional medicine, predominantly because of mistrust or lack of belief in traditional medicine. Our findings provide novel evidence concerning transitional health beliefs, hidden pain, and chronic non-communicable disease prevalence in marginalized communities of the Peruvian Amazon. Healthcare provision was limited by a breach between health education, knowledge, and access. Additional participatory research with similar rural populations is required to inform regional healthcare policy and decision-making. PMID:25688165

  2. Detrimental effect of interfacial Dzyaloshinskii-Moriya interaction on perpendicular spin-transfer-torque magnetic random access memory

    SciTech Connect

    Jang, Peong-Hwa; Lee, Seo-Won E-mail: kj-lee@korea.ac.kr; Song, Kyungmi; Lee, Seung-Jae; Lee, Kyung-Jin E-mail: kj-lee@korea.ac.kr

    2015-11-16

    Interfacial Dzyaloshinskii-Moriya interaction in ferromagnet/heavy metal bilayers is recently of considerable interest as it offers an efficient control of domain walls and the stabilization of magnetic skyrmions. However, its effect on the performance of perpendicular spin transfer torque memory has not been explored yet. We show based on numerical studies that the interfacial Dzyaloshinskii-Moriya interaction decreases the thermal energy barrier while increases the switching current. As high thermal energy barrier as well as low switching current is required for the commercialization of spin torque memory, our results suggest that the interfacial Dzyaloshinskii-Moriya interaction should be minimized for spin torque memory applications.

  3. A simple device unit consisting of all NiO storage and switch elements for multilevel terabit nonvolatile random access memory.

    PubMed

    Lee, Myoung-Jae; Ahn, Seung-Eon; Lee, Chang Bum; Kim, Chang-Jung; Jeon, Sanghun; Chung, U-In; Yoo, In-Kyeong; Park, Gyeong-Su; Han, Seungwu; Hwang, In Rok; Park, Bae-Ho

    2011-11-01

    Present charge-based silicon memories are unlikely to reach terabit densities because of scaling limits. As the feature size of memory shrinks to just tens of nanometers, there is insufficient volume available to store charge. Also, process temperatures higher than 800 °C make silicon incompatible with three-dimensional (3D) stacking structures. Here we present a device unit consisting of all NiO storage and switch elements for multilevel terabit nonvolatile random access memory using resistance switching. It is demonstrated that NiO films are scalable to around 30 nm and compatible with multilevel cell technology. The device unit can be a building block for 3D stacking structure because of its simple structure and constituent, high performance, and process temperature lower than 300 °C. Memory resistance switching of NiO storage element is accompanied by an increase in density of grain boundary while threshold resistance switching of NiO switch element is controlled by current flowing through NiO film. PMID:21988144

  4. Quantifying data retention of perpendicular spin-transfer-torque magnetic random access memory chips using an effective thermal stability factor method

    SciTech Connect

    Thomas, Luc Jan, Guenole; Le, Son; Wang, Po-Kang

    2015-04-20

    The thermal stability of perpendicular Spin-Transfer-Torque Magnetic Random Access Memory (STT-MRAM) devices is investigated at chip level. Experimental data are analyzed in the framework of the Néel-Brown model including distributions of the thermal stability factor Δ. We show that in the low error rate regime important for applications, the effect of distributions of Δ can be described by a single quantity, the effective thermal stability factor Δ{sub eff}, which encompasses both the median and the standard deviation of the distributions. Data retention of memory chips can be assessed accurately by measuring Δ{sub eff} as a function of device diameter and temperature. We apply this method to show that 54 nm devices based on our perpendicular STT-MRAM design meet our 10 year data retention target up to 120 °C.

  5. Experimental evidence of the quantum point contact theory in the conduction mechanism of bipolar HfO2-based resistive random access memories

    NASA Astrophysics Data System (ADS)

    Prócel, L. M.; Trojman, L.; Moreno, J.; Crupi, F.; Maccaronio, V.; Degraeve, R.; Goux, L.; Simoen, E.

    2013-08-01

    The quantum point contact (QPC) model for dielectric breakdown is used to explain the electron transport mechanism in HfO2-based resistive random access memories (ReRAM) with TiN(30 nm)HfO2(5 nm)Hf(10 nm)TiN(30 nm) stacks. Based on experimental I-V characteristics of bipolar HfO2-based ReRAM, we extracted QPC model parameters related to the conduction mechanism in several devices in order to make a statistical study. In addition, we investigated the temperature effect on the conduction mechanism and compared it with the QPC model. Based on these experimental results, we show that the QPC model agrees well with the conduction behavior of HfO2-based ReRAM memory cells.

  6. Investigation of thermal stability and reliability of HfO2 based resistive random access memory devices with cross-bar structure

    NASA Astrophysics Data System (ADS)

    Chand, Umesh; Huang, Kuan-Chang; Huang, Chun-Yang; Ho, Chia-Hua; Lin, Chen-Hsi; Tseng, Tseung-Yuen

    2015-05-01

    The effect of the annealing treatment of a HfO2 resistive switching layer and the memory performance of a HfO2-based resistive random access memory (cross-bar structure) device were investigated. Oxygen is released from HfO2 resistive switching layers during vacuum annealing, leading to unstable resistive switching properties. This oxygen release problem can be suppressed by inserting an Al2O3 thin film, which has a lower Gibbs free energy, between the HfO2 layer and top electrode to form a Ti/Al2O3/HfO2/TiN structure. This device structure exhibited good reliability after high temperature vacuum annealing and post metal annealing (PMA) treatments. Moreover, the endurance and retention properties of the device were also improved after the PMA treatment.

  7. Reducing operation voltages by introducing a low-k switching layer in indium–tin-oxide-based resistance random access memory

    NASA Astrophysics Data System (ADS)

    Jin, Fu-Yuan; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Lin, Chih-Yang; Chen, Po-Hsun; Chen, Min-Chen; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2016-06-01

    In this letter, we inserted a low dielectric constant (low-k) or high dielectric constant (high-k) material as a switching layer in indium–tin-oxide-based resistive random-access memory. After measuring the two samples, we found that the low-k material device has very low operating voltages (‑80 and 110 mV for SET and RESET operations, respectively). Current fitting results were then used with the COMSOL software package to simulate electric field distribution in the layers. After combining the electrical measurement results with simulations, a conduction model was proposed to explain resistance switching behaviors in the two structures.

  8. Bit Distribution and Reliability of High Density 1.5 V Ferroelectric Random Access Memory Embedded with 130 nm, 5 lm Copper Complementary Metal Oxide Semiconductor Logic

    NASA Astrophysics Data System (ADS)

    Udayakumar, K. R.; Boku, K.; Remack, K. A.; Rodriguez, J.; Summerfelt, S. R.; Celii, F. G.; Aggarwal, S.; Martin, J. S.; Hall, L.; Matz, L.; Rathsack, B.; McAdams, H.; Moise, T. S.

    2006-04-01

    High density embedded ferroelectric random access memory (FRAM), operable at 1.5 V, has been fabricated within a 130 nm, 5 lm Cu/fluorosilicate glass (FSG) logic process. To evaluate FRAM extendability to future process nodes, we have measured the bit distribution and reliability properties of arrays with varying individual capacitor areas ranging from 0.40 μm2 (130 nm node) to 0.15 μm2 (˜65 nm node). Wide signal margins, stable retention (≫10 years at 85 °C), and high endurance read/write cycling (≫1012 cycles) have been demonstrated, suggesting that reliable, high density FRAM can be realized.

  9. Mechanism of power consumption inhibitive multi-layer Zn:SiO2/SiO2 structure resistance random access memory

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Tsai, Tsung-Ming; Chang, Ting-Chang; Chang, Kuan-Chang; Chen, Kai-Huang; Lou, Jen-Chung; Young, Tai-Fa; Chen, Jung-Hui; Huang, Syuan-Yong; Chen, Min-Chen; Shih, Chih-Cheng; Chen, Hsin-Lu; Pan, Jhih-Hong; Tung, Cheng-Wei; Syu, Yong-En; Sze, Simon M.

    2013-12-01

    In this paper, multi-layer Zn:SiO2/SiO2 structure is introduced to reduce the operation power consumption of resistive random access memory (RRAM) device by modifying the filament formation process. And the configuration of multi-layer Zn:SiO2/SiO2 structure is confirmed and demonstrated by auger electron spectrum. Material analysis together with conduction current fitting is applied to qualitatively evaluate the carrier conduction mechanism on both low resistance state and high resistance state. Finally, single layer and multilayer conduction models are proposed, respectively, to clarify the corresponding conduction characteristics of two types of RRAM devices.

  10. Mechanism of power consumption inhibitive multi-layer Zn:SiO{sub 2}/SiO{sub 2} structure resistance random access memory

    SciTech Connect

    Zhang, Rui; Lou, Jen-Chung; Tsai, Tsung-Ming E-mail: tcchang@mail.phys.nsysu.edu.tw; Chang, Kuan-Chang; Huang, Syuan-Yong; Shih, Chih-Cheng; Pan, Jhih-Hong; Tung, Cheng-Wei; Chang, Ting-Chang E-mail: tcchang@mail.phys.nsysu.edu.tw; Chen, Kai-Huang; Young, Tai-Fa; Chen, Hsin-Lu; Chen, Jung-Hui; Chen, Min-Chen; Syu, Yong-En; Sze, Simon M.

    2013-12-21

    In this paper, multi-layer Zn:SiO{sub 2}/SiO{sub 2} structure is introduced to reduce the operation power consumption of resistive random access memory (RRAM) device by modifying the filament formation process. And the configuration of multi-layer Zn:SiO{sub 2}/SiO{sub 2} structure is confirmed and demonstrated by auger electron spectrum. Material analysis together with conduction current fitting is applied to qualitatively evaluate the carrier conduction mechanism on both low resistance state and high resistance state. Finally, single layer and multilayer conduction models are proposed, respectively, to clarify the corresponding conduction characteristics of two types of RRAM devices.

  11. 39% access time improvement, 11% energy reduction, 32 kbit 1-read/1-write 2-port static random-access memory using two-stage read boost and write-boost after read sensing scheme

    NASA Astrophysics Data System (ADS)

    Yamamoto, Yasue; Moriwaki, Shinichi; Kawasumi, Atsushi; Miyano, Shinji; Shinohara, Hirofumi

    2016-04-01

    We propose novel circuit techniques for 1 clock (1CLK) 1 read/1 write (1R/1W) 2-port static random-access memories (SRAMs) to improve read access time (tAC) and write margins at low voltages. Two-stage read boost (TSR-BST) and write word line boost (WWL-BST) after the read sensing schemes have been proposed. TSR-BST reduces the worst read bit line (RBL) delay by 61% and RBL amplitude by 10% at V DD = 0.5 V, which improves tAC by 39% and reduces energy dissipation by 11% at V DD = 0.55 V. WWL-BST after read sensing scheme improves minimum operating voltage (V min) by 140 mV. A 32 kbit 1CLK 1R/1W 2-port SRAM with TSR-BST and WWL-BST has been developed using a 40 nm CMOS.

  12. Volcanic eruptions, hazardous ash clouds and visualization tools for accessing real-time infrared remote sensing data

    NASA Astrophysics Data System (ADS)

    Webley, P.; Dehn, J.; Dean, K. G.; Macfarlane, S.

    2010-12-01

    Volcanic eruptions are a global hazard, affecting local infrastructure, impacting airports and hindering the aviation community, as seen in Europe during Spring 2010 from the Eyjafjallajokull eruption in Iceland. Here, we show how remote sensing data is used through web-based interfaces for monitoring volcanic activity, both ground based thermal signals and airborne ash clouds. These ‘web tools’, http://avo.images.alaska.edu/, provide timely availability of polar orbiting and geostationary data from US National Aeronautics and Space Administration, National Oceanic and Atmosphere Administration and Japanese Meteorological Agency satellites for the North Pacific (NOPAC) region. This data is used operationally by the Alaska Volcano Observatory (AVO) for monitoring volcanic activity, especially at remote volcanoes and generates ‘alarms’ of any detected volcanic activity and ash clouds. The webtools allow the remote sensing team of AVO to easily perform their twice daily monitoring shifts. The web tools also assist the National Weather Service, Alaska and Kamchatkan Volcanic Emergency Response Team, Russia in their operational duties. Users are able to detect ash clouds, measure the distance from the source, area and signal strength. Within the web tools, there are 40 x 40 km datasets centered on each volcano and a searchable database of all acquired data from 1993 until present with the ability to produce time series data per volcano. Additionally, a data center illustrates the acquired data across the NOPAC within the last 48 hours, http://avo.images.alaska.edu/tools/datacenter/. We will illustrate new visualization tools allowing users to display the satellite imagery within Google Earth/Maps, and ArcGIS Explorer both as static maps and time-animated imagery. We will show these tools in real-time as well as examples of past large volcanic eruptions. In the future, we will develop the tools to produce real-time ash retrievals, run volcanic ash dispersion

  13. RTDB: A memory resident real-time object database

    SciTech Connect

    Jerzy M. Nogiec; Eugene Desavouret

    2003-06-04

    RTDB is a fast, memory-resident object database with built-in support for distribution. It constitutes an attractive alternative for architecting real-time solutions with multiple, possibly distributed, processes or agents sharing data. RTDB offers both direct and navigational access to stored objects, with local and remote random access by object identifiers, and immediate direct access via object indices. The database supports transparent access to objects stored in multiple collaborating dispersed databases and includes a built-in cache mechanism that allows for keeping local copies of remote objects, with specifiable invalidation deadlines. Additional features of RTDB include a trigger mechanism on objects that allows for issuing events or activating handlers when objects are accessed or modified and a very fast, attribute based search/query mechanism. The overall architecture and application of RTDB in a control and monitoring system is presented.

  14. Abnormal social behavior, hyperactivity, impaired remote spatial memory, and increased D1-mediated dopaminergic signaling in neuronal nitric oxide synthase knockout mice

    PubMed Central

    Tanda, Koichi; Nishi, Akinori; Matsuo, Naoki; Nakanishi, Kazuo; Yamasaki, Nobuyuki; Sugimoto, Tohru; Toyama, Keiko; Takao, Keizo; Miyakawa, Tsuyoshi

    2009-01-01

    Background Neuronal nitric oxide synthase (nNOS) is involved in the regulation of a diverse population of intracellular messenger systems in the brain. In humans, abnormal NOS/nitric oxide metabolism is suggested to contribute to the pathogenesis and pathophysiology of some neuropsychiatric disorders, such as schizophrenia and bipolar disorder. Mice with targeted disruption of the nNOS gene exhibit abnormal behaviors. Here, we subjected nNOS knockout (KO) mice to a battery of behavioral tests to further investigate the role of nNOS in neuropsychiatric functions. We also examined the role of nNOS in dopamine/DARPP-32 signaling in striatal slices from nNOS KO mice and the effects of the administration of a dopamine D1 receptor agonist on behavior in nNOS KO mice. Results nNOS KO mice showed hyperlocomotor activity in a novel environment, increased social interaction in their home cage, decreased depression-related behavior, and impaired spatial memory retention. In striatal slices from nNOS KO mice, the effects of a dopamine D1 receptor agonist, SKF81297, on the phosphorylation of DARPP-32 and AMPA receptor subunit GluR1 at protein kinase A sites were enhanced. Consistent with the biochemical results, intraperitoneal injection of a low dose of SKF81297 significantly decreased prepulse inhibition in nNOS KO mice, but not in wild-type mice. Conclusion These findings indicate that nNOS KO upregulates dopamine D1 receptor signaling, and induces abnormal social behavior, hyperactivity and impaired remote spatial memory. nNOS KO mice may serve as a unique animal model of psychiatric disorders. PMID:19538708

  15. Remote Sensing Information Gateway: A free application and web service for fast, convenient, interoperable access to large repositories of atmospheric data

    NASA Astrophysics Data System (ADS)

    Plessel, T.; Szykman, J.; Freeman, M.

    2012-12-01

    EPA's Remote Sensing Information Gateway (RSIG) is a widely used free applet and web service for quickly and easily retrieving, visualizing and saving user-specified subsets of atmospheric data - by variable, geographic domain and time range. Petabytes of available data include thousands of variables from a set of NASA and NOAA satellites, aircraft, ground stations and EPA air-quality models. The RSIG applet is used by atmospheric researchers and uses the rsigserver web service to obtain data and images. The rsigserver web service is compliant with the Open Geospatial Consortium Web Coverage Service (OGC-WCS) standard to facilitate data discovery and interoperability. Since rsigserver is publicly accessible, it can be (and is) used by other applications. This presentation describes the architecture and technical implementation details of this successful system with an emphasis on achieving convenience, high-performance, data integrity and security.

  16. SiO2 doped Ge2Sb2Te5 thin films with high thermal efficiency for applications in phase change random access memory.

    PubMed

    Ryu, Seung Wook; Lyeo, Ho-Ki; Lee, Jong Ho; Ahn, Young Bae; Kim, Gun Hwan; Kim, Choon Hwan; Kim, Soo Gil; Lee, Se-Ho; Kim, Ka Young; Kim, Jong Hyeop; Kim, Won; Hwang, Cheol Seong; Kim, Hyeong Joon

    2011-06-24

    This study examined the various physical, structural and electrical properties of SiO(2) doped Ge(2)Sb(2)Te(5) (SGST) films for phase change random access memory applications. Interestingly, SGST had a layered structure (LS) resulting from the inhomogeneous distribution of SiO(2) after annealing. The physical parameters able to affect the reset current of phase change memory (I(res)) were predicted from the Joule heating and heat conservation equations. When SiO(2) was doped into GST, thermal conductivity largely decreased by ∼ 55%. The influence of SiO(2)-doping on I(res) was examined using the test phase change memory cell. I(res) was reduced by ∼ 45%. An electro-thermal simulation showed that the reduced thermal conductivity contributes to the improvement of cell efficiency as well as the reduction of I(res), while the increased dynamic resistance contributes only to the latter. The formation and presence of the LS thermal conductivity in the set state test cell after repeated switching was confirmed. PMID:21572208

  17. a-SiNx:H-based ultra-low power resistive random access memory with tunable Si dangling bond conduction paths

    PubMed Central

    Jiang, Xiaofan; Ma, Zhongyuan; Xu, Jun; Chen, Kunji; Xu, Ling; Li, Wei; Huang, Xinfan; Feng, Duan

    2015-01-01

    The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p+-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I–V ) curves combined with the temperature dependence of the I–V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole–Frenkel (P–F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM. PMID:26508086

  18. a-SiNx:H-based ultra-low power resistive random access memory with tunable Si dangling bond conduction paths.

    PubMed

    Jiang, Xiaofan; Ma, Zhongyuan; Xu, Jun; Chen, Kunji; Xu, Ling; Li, Wei; Huang, Xinfan; Feng, Duan

    2015-01-01

    The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p(+)-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I-V) curves combined with the temperature dependence of the I-V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole-Frenkel (P-F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM. PMID:26508086

  19. a-SiNx:H-based ultra-low power resistive random access memory with tunable Si dangling bond conduction paths

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaofan; Ma, Zhongyuan; Xu, Jun; Chen, Kunji; Xu, Ling; Li, Wei; Huang, Xinfan; Feng, Duan

    2015-10-01

    The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p+-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I-V ) curves combined with the temperature dependence of the I-V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole-Frenkel (P-F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM.

  20. Accessing Epstein-Barr Virus-Specific T-Cell Memory with Peptide-Loaded Dendritic Cells

    PubMed Central

    Redchenko, I. V.; Rickinson, A. B.

    1999-01-01

    The conventional means of studying Epstein-Barr virus (EBV)-induced cytotoxic T-lymphocyte (CTL) memory, by in vitro stimulation with the latently infected autologous lymphoblastoid cell line (LCL), has important limitations. First, it gives no information on memory to lytic cycle antigens; second, it preferentially amplifies the dominant components of latent antigen-specific memory at the expense of key subdominant reactivities. Here we describe an alternative approach, based on in vitro stimulation with epitope peptide-loaded dendritic cells (DCs), which allows one to probe the CTL repertoire for any individual reactivity of choice; this method proved significantly more efficient than stimulation with peptide alone. Using this approach we first show that reactivities to the immunodominant and subdominant lytic cycle epitopes identified by T cells during primary EBV infection are regularly detectable in the CTL memory of virus carriers; this implies that in such carriers chronic virus replication remains under direct T-cell control. We further show that subdominant latent cycle reactivities to epitopes in the latent membrane protein LMP2, though rarely undetectable in LCL-stimulated populations, can be reactivated by DC stimulation and selectively expanded as polyclonal CTL lines; the adoptive transfer of such preparations may be of value in targeting certain EBV-positive malignancies. PMID:9847337

  1. Loss of Object Recognition Memory Produced by Extended Access to Methamphetamine Self-Administration is Reversed by Positive Allosteric Modulation of Metabotropic Glutamate Receptor 5

    PubMed Central

    Reichel, Carmela M; Schwendt, Marek; McGinty, Jacqueline F; Olive, M Foster; See, Ronald E

    2011-01-01

    Chronic methamphetamine (meth) abuse can lead to persisting cognitive deficits. Here, we utilized a long-access meth self-administration (SA) protocol to assess recognition memory and metabotropic glutamate receptor (mGluR) expression, and the possible reversal of cognitive impairments with the mGluR5 allosteric modulator, 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl) benzamide (CDPPB). Male, Long-Evans rats self-administered i.v. meth (0.02 mg/infusion) on an FR1 schedule of reinforcement or received yoked-saline infusions. After seven daily 1-h sessions, rats were switched to 6-h daily sessions for 14 days, and then underwent drug abstinence. Rats were tested for object recognition memory at 1 week after meth SA at 90 min and 24 h retention intervals. In a separate experiment, rats underwent the same protocol, but received either vehicle or CDPPB (30 mg/kg) after familiarization. Rats were killed on day 8 or 14 post-SA and brain tissue was obtained. Meth intake escalated over the extended access period. Additionally, meth-experienced rats showed deficits in both short- and long-term recognition memory, demonstrated by a lack of novel object exploration. The deficit at 90 min was reversed by CDPPB treatment. On day 8, meth intake during SA negatively correlated with mGluR expression in the perirhinal and prefrontal cortex, and mGluR5 receptor expression was decreased 14 days after discontinuation of meth. This effect was specific to mGluR5 levels in the perirhinal cortex, as no differences were identified in the hippocampus or in mGluR2/3 receptors. These results from a clinically-relevant animal model of addiction suggest that mGluR5 receptor modulation may be a potential treatment of cognitive dysfunction in meth addiction. PMID:21150906

  2. Examining Our Instrumented World for Greater Understanding; N.E.S.O. Provides Access to NASA Remote Sensing Data That Describes Our World and How It Is Changing.

    NASA Astrophysics Data System (ADS)

    Henderson, M. A.

    2014-12-01

    NASA Earth and Space Observations (NESO) is an interactive map and measurements tool that fosters active sharing and discussion among dispersed learners and educators in both formal and informal settings. NESO provides access to timely and relevant remote sensing data which will enable novice or non-technical users to pursue a scientific inquiry process to reach conclusions about our changing world as scientists might do. Participants in this session will gain a working knowledge of how to ask questions of NASA data using the functionality and interactivity of our tool across three platforms; a webpage, an iPad app, and NOAA's Science on a Sphere(SOS). We will access data to create animations and time series over entire missions and allow the user to generate specific statistics and graphs.The name NESO is derived from the web tool NEO which provided the original functionality, and Earth Science data sets. The tool has been enhanced and expanded to include Space Science data sets such as planetary, lunar, and all-sky maps, and we are continuing to expand the data catalog. Our future work includes a support web page for educators and other users with samples of analysis and lesson plans. The next phase of tool development will include layering capability, floating point data handling, and an additional server mode to drive other display technologies such as high resolution flat panel systems.

  3. TOPICAL REVIEW Nanoscale memory devices

    NASA Astrophysics Data System (ADS)

    Chung, Andy; Deen, Jamal; Lee, Jeong-Soo; Meyyappan, M.

    2010-10-01

    This article reviews the current status and future prospects for the use of nanomaterials and devices in memory technology. First, the status and continuing scaling trends of the flash memory are discussed. Then, a detailed discussion on technologies trying to replace flash in the near-term is provided. This includes phase change random access memory, Fe random access memory and magnetic random access memory. The long-term nanotechnology prospects for memory devices include carbon-nanotube-based memory, molecular electronics and memristors based on resistive materials such as TiO2.

  4. Preliminary Polar Sea Trials of Nereid-UI: A Remotely Operated Underwater Vehicle for Oceanographic Access Under Ice

    NASA Astrophysics Data System (ADS)

    Whitcomb, L. L.; Jakuba, M.; German, C. R.; Bowen, A.; Yoerger, D.; Kinsey, J. C.; Mayer, L.; McFarland, C.; Suman, S.; Bailey, J.; Judge, C.; Elliott, S.; Gomez-Ibanez, D.; Taylor, C. L.; Machado, C.; Howland, J. C.; Kaiser, C.; Heintz, M.; Pontbriand, C.; O'Hara, L.; McDonald, G.; Boetius, A.

    2014-12-01

    We report the development and deployment of a remotely-controlled underwater robotic vehicle capable of being teleoperated under ice under real-time human supervision. The Nereid Under-Ice (Nereid-UI or NUI) vehicle enables exploration and detailed examination of biological and physical environments including the ice-ocean interface in marginal ice zones, in the water column of ice-covered seas, at glacial ice-tongues, and ice-shelf margins, delivering realtime high definition video in addition to survey data from on board acoustic, optical, chemical, and biological sensors. The vehicle employs a novel lightweight fiber-optic tether that will enable it to be deployed from a ship to attain standoff distances of up to 20 km from an ice-edge boundary. We conducted NUI's first under-ice deployments during the July 2014 F/V Polarstern PS86 expedition at 86° N 6 W° in the Arctic Ocean - near the Aurora hydrothermal vent site on the Gakkel Ridge approximately 200 km NE of Greenland. We conducted 4 dives to evaluate and develop NUI's overall functioning and its individual engineered subsystems. On each dive, dead-reckoning (Ice-locked Doppler sonar and north-seeking gyrocompass) complemented by acoustic ranging provided navigation, supporting closed-loop control of heading, depth, and XY position relative to the ice. Science operations included multibeam transects of under-ice topography, precision vertical profiles for the bio-sensor suite and IR/radiance sensor suite, IR/radiance/multibeam transects at constant depth interlaced with vertical profiles and upward-looking digital still-camera surveys of the ice, including areas rich with algal material. The fiber-optic tether remained intact throughout most of all 4 dives. Consistent with the NUI concept of operations, in 3 of 4 dives the fiber-optic tether eventually failed, and the vehicle was then commanded acoustically in a series of short-duration maneuvers to return to Polarstern for recovery. These preliminary

  5. Ease of Access to List Items in Short-Term Memory Depends on the Order of the Recognition Probes

    ERIC Educational Resources Information Center

    Lange, Elke B.; Cerella, John; Verhaeghen, Paul

    2011-01-01

    We report data from 4 experiments using a recognition design with multiple probes to be matched to specific study positions. Items could be accessed rapidly, independent of set size, when the test order matched the study order (forward condition). When the order of testing was random, backward, or in a prelearned irregular sequence (reordered…

  6. ViSA: A Neurodynamic Model for Visuo-Spatial Working Memory, Attentional Blink, and Conscious Access

    ERIC Educational Resources Information Center

    Simione, Luca; Raffone, Antonino; Wolters, Gezinus; Salmas, Paola; Nakatani, Chie; Belardinelli, Marta Olivetti; van Leeuwen, Cees

    2012-01-01

    Two separate lines of study have clarified the role of selectivity in conscious access to visual information. Both involve presenting multiple targets and distracters: one "simultaneously" in a spatially distributed fashion, the other "sequentially" at a single location. To understand their findings in a unified framework, we propose a…

  7. Detailed analysis of minimum operation voltage of extraordinarily unstable cells in fully depleted silicon-on-buried-oxide six-transistor static random access memory

    NASA Astrophysics Data System (ADS)

    Mizutani, Tomoko; Yamamoto, Yoshiki; Makiyama, Hideki; Yamashita, Tomohiro; Oda, Hidekazu; Kamohara, Shiro; Sugii, Nobuyuki; Hiramoto, Toshiro

    2015-04-01

    The minimum operation voltage (Vmin) of very unstable cells in silicon-on-thin-buried-oxide (SOTB) six-transistor (6T) static random access memory (SRAM) is analyzed in detail. It is found that the worst cell in 16k SRAM is very unstable and the stability characteristics of the worst cell correspond to approximately 6σ from those of the median cell. It is also found that extraordinarily unstable cells are much more sensitive to VTH change than median cells and that the static noise margin (SNM) and Vmin well correlate only in extraordinarily unstable cells. A simple VTH model for evaluating Vmin is developed and validated by Vmin measured in extraordinarily unstable cells.

  8. Closed-form analytical model of static noise margin for ultra-low voltage eight-transistor tunnel FET static random access memory

    NASA Astrophysics Data System (ADS)

    Fuketa, Hiroshi; O'uchi, Shin-ichi; Fukuda, Koichi; Mori, Takahiro; Morita, Yukinori; Masahara, Meishoku; Matsukawa, Takashi

    2016-04-01

    Variations of eight-transistor (8T) tunnel FET (TFET) static random access memory (SRAM) cells at ultra-low supply voltage (V DD) of 0.3 V are discussed. A closed-form analytical model for the static noise margin (SNM) of the TFET SRAM cells is proposed to clarify the dependence of SNM on device parameters and is verified by simulations. The SNM variations caused by process variations are investigated using the proposed model, and we show a requirement for the threshold voltage (V TH) variation in the TFET SRAM design, which indicates that the V TH variation must be reduced as the subthreshold swing becomes steeper. In addition, a feasibility of the TFET SRAM cells operating at V DD = 0.3 V in two different process technologies is evaluated using the proposed model.

  9. Self-compliance Pt/HfO2/Ti/Si one-diode-one-resistor resistive random access memory device and its low temperature characteristics

    NASA Astrophysics Data System (ADS)

    Lu, Chao; Yu, Jue; Chi, Xiao-Wei; Lin, Guang-Yang; Lan, Xiao-Ling; Huang, Wei; Wang, Jian-Yuan; Xu, Jian-Fang; Wang, Chen; Li, Cheng; Chen, Song-Yan; Liu, Chunli; Lai, Hong-Kai

    2016-04-01

    A bipolar one-diode-one-resistor (1D1R) device with a Pt/HfO2/Ti/n-Si(001) structure was demonstrated. The 1D1R resistive random access memory (RRAM) device consists of a Ti/n-Si(001) diode and a Pt/HfO2/Ti resistive switching cell. By using the Ti layer as the shared electrode for both the diode and the resistive switching cell, the 1D1R device exhibits the property of stable self-compliance and the characteristic of robust resistive switching with high uniformity. The high/low resistance ratio reaches 103. The electrical RESET/SET curve does not deteriorate after 68 loops. Low-temperature studies show that the 1D1R RRAM device has a critical working temperature of 250 K, and at temperatures below 250 K, the device fails to switch its resistances.

  10. Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory

    NASA Astrophysics Data System (ADS)

    Popovici, M.; Swerts, J.; Redolfi, A.; Kaczer, B.; Aoulaiche, M.; Radu, I.; Clima, S.; Everaert, J.-L.; Van Elshocht, S.; Jurczak, M.

    2014-02-01

    Improved metal-insulator-metal capacitor (MIMCAP) stacks with strontium titanate (STO) as dielectric sandwiched between Ru as top and bottom electrode are shown. The Ru/STO/Ru stack demonstrates clearly its potential to reach sub-20 nm technology nodes for dynamic random access memory. Downscaling of the equivalent oxide thickness, leakage current density (Jg) of the MIMCAPs, and physical thickness of the STO have been realized by control of the Sr/Ti ratio and grain size using a heterogeneous TiO2/STO based nanolaminate stack deposition and a two-step crystallization anneal. Replacement of TiN with Ru as both top and bottom electrodes reduces the amount of electrically active defects and is essential to achieve a low leakage current in the MIM capacitor.

  11. Evaluation and Control of Break-Even Time of Nonvolatile Static Random Access Memory Based on Spin-Transistor Architecture with Spin-Transfer-Torque Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Shuto, Yusuke; Yamamoto, Shuu'ichirou; Sugahara, Satoshi

    2012-04-01

    The energy performance of a nonvolatile static random access memory (NV-SRAM) cell for power gating applications was quantitatively analyzed for the first time using the performance index of break-even time (BET). The NV-SRAM cell is based on spin-transistor architecture using ordinary metal-oxide-semiconductor field-effect transistors (MOSFETs) and spin-transfer-torque magnetic tunnel junctions (STT-MTJs), whose circuit representation of spin-transistor is referred to as a pseudo-spin-MOSFET (PS-MOSFET). The cell is configured with a standard six-transistor SRAM cell and two PS-MOSFETs. The NV-SRAM cell basically has a short BET of submicroseconds. Although the write (store) operation to the STT-MTJs causes an increase in the BET, it can be successfully reduced by the proposed power-aware bias-control for the PS-MOSFETs.

  12. Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory

    SciTech Connect

    Popovici, M. Swerts, J.; Redolfi, A.; Kaczer, B.; Aoulaiche, M.; Radu, I.; Clima, S.; Everaert, J.-L.; Van Elshocht, S.; Jurczak, M.

    2014-02-24

    Improved metal-insulator-metal capacitor (MIMCAP) stacks with strontium titanate (STO) as dielectric sandwiched between Ru as top and bottom electrode are shown. The Ru/STO/Ru stack demonstrates clearly its potential to reach sub-20 nm technology nodes for dynamic random access memory. Downscaling of the equivalent oxide thickness, leakage current density (J{sub g}) of the MIMCAPs, and physical thickness of the STO have been realized by control of the Sr/Ti ratio and grain size using a heterogeneous TiO{sub 2}/STO based nanolaminate stack deposition and a two-step crystallization anneal. Replacement of TiN with Ru as both top and bottom electrodes reduces the amount of electrically active defects and is essential to achieve a low leakage current in the MIM capacitor.

  13. Evaluation of in-plane local stress distribution in stacked IC chip using dynamic random access memory cell array for highly reliable three-dimensional IC

    NASA Astrophysics Data System (ADS)

    Tanikawa, Seiya; Kino, Hisashi; Fukushima, Takafumi; Koyanagi, Mitsumasa; Tanaka, Tetsu

    2016-04-01

    As three-dimensional (3D) ICs have many advantages, IC performances can be enhanced without scaling down of transistor size. However, 3D IC has mechanical stresses inside Si substrates owing to its 3D stacking structure, which induces negative effects on transistor performances such as carrier mobility changes. One of the mechanical stresses is local bending stress due to organic adhesive shrinkage among stacked IC chips. In this paper, we have proposed an evaluation method for in-plane local stress distribution in the stacked IC chips using retention time modulation of a dynamic random access memory (DRAM) cell array. We fabricated a test structure composed of a DRAM chip bonded on a Si interposer with dummy Cu/Sn microbumps. As a result, we clarified that the DRAM cell array can precisely evaluate the in-plane local stress distribution in the stacked IC chips.

  14. The reason for the increased threshold switching voltage of SiO2 doped Ge2Sb2Te5 thin films for phase change random access memory

    NASA Astrophysics Data System (ADS)

    Ryu, Seung Wook; Lee, Jong Ho; Ahn, Young Bae; Kim, Choon Hwan; Yang, Bong Seob; Kim, Gun Hwan; Kim, Soo Gil; Lee, Se-Ho; Hwang, Cheol Seong; Kim, Hyeong Joon

    2009-09-01

    This study examined the threshold switching voltage (VT) of 150 nm thick SiO2 doped Ge2Sb2Te5 (SGST) films for phase change random access memory applications. The VT of the SGST films increased from ˜0.9 V (for GST) to ˜1.5 V with increasing SiO2 content. The optical band gap and Urbach edge of the SGST films were similar regardless of the SiO2 concentration. The dielectric constant decreased by ˜37% and the electrical resistivity increased by ˜19%. The increase in VT of SGST films is associated with an effective increase in electric field and the decreased generation rate caused by impact ionization.

  15. Phase transformation behaviors of SiO2 doped Ge2Sb2Te5 films for application in phase change random access memory

    NASA Astrophysics Data System (ADS)

    Ryu, Seung Wook; Oh, Jin Ho; Lee, Jong Ho; Choi, Byung Joon; Kim, Won; Hong, Suk Kyoung; Hwang, Cheol Seong; Kim, Hyeong Joon

    2008-04-01

    The improvement in the phase change characteristics of Ge2Sb2Te5 (GST) films for phase change random access memory applications was investigated by doping the GST films with SiO2 using cosputtering at room temperature. As the sputtering power of SiO2 increased from 0to150W, the activation energy for crystallization increased from 2.1±0.2to3.1±0.15eV. SiO2 inhibited the crystallization of the amorphous GST films, which improved the long term stability of the metastable amorphous phase. The melting point decreased with increasing concentration of SiO2, which reduced the power consumption as well as the reset current.

  16. Multi-step resistive switching behavior of Li-doped ZnO resistance random access memory device controlled by compliance current

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Cheng; Tang, Jian-Fu; Su, Hsiu-Hsien; Hong, Cheng-Shong; Huang, Chih-Yu; Chu, Sheng-Yuan

    2016-06-01

    The multi-step resistive switching (RS) behavior of a unipolar Pt/Li0.06Zn0.94O/Pt resistive random access memory (RRAM) device is investigated. It is found that the RRAM device exhibits normal, 2-, 3-, and 4-step RESET behaviors under different compliance currents. The transport mechanism within the device is investigated by means of current-voltage curves, in-situ transmission electron microscopy, and electrochemical impedance spectroscopy. It is shown that the ion transport mechanism is dominated by Ohmic behavior under low electric fields and the Poole-Frenkel emission effect (normal RS behavior) or Li+ ion diffusion (2-, 3-, and 4-step RESET behaviors) under high electric fields.

  17. Correlative transmission electron microscopy and electrical properties study of switchable phase-change random access memory line cells

    SciTech Connect

    Oosthoek, J. L. M.; Kooi, B. J.; Voogt, F. C.; Attenborough, K.; Verheijen, M. A.; Hurkx, G. A. M.; Gravesteijn, D. J.

    2015-02-14

    Phase-change memory line cells, where the active material has a thickness of 15 nm, were prepared for transmission electron microscopy (TEM) observation such that they still could be switched and characterized electrically after the preparation. The result of these observations in comparison with detailed electrical characterization showed (i) normal behavior for relatively long amorphous marks, resulting in a hyperbolic dependence between SET resistance and SET current, indicating a switching mechanism based on initially long and thin nanoscale crystalline filaments which thicken gradually, and (ii) anomalous behavior, which holds for relatively short amorphous marks, where initially directly a massive crystalline filament is formed that consumes most of the width of the amorphous mark only leaving minor residual amorphous regions at its edges. The present results demonstrate that even in (purposely) thick TEM samples, the TEM sample preparation hampers the probability to observe normal behavior and it can be debated whether it is possible to produce electrically switchable TEM specimen in which the memory cells behave the same as in their original bulk embedded state.

  18. 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.

  19. Chronic restricted access to 10% sucrose solution in adolescent and young adult rats impairs spatial memory and alters sensitivity to outcome devaluation.

    PubMed

    Kendig, Michael D; Boakes, Robert A; Rooney, Kieron B; Corbit, Laura H

    2013-08-15

    Although increasing consumption of sugar drinks is recognized as a significant public health concern, little is known about (a) the cognitive effects resulting from sucrose consumption; and (b) whether the long-term effects of sucrose consumption are more pronounced for adolescents. This experiment directly compared performance on a task of spatial learning and memory (the Morris Water Maze) and sensitivity to outcome devaluation following 28 days of 2-h/day access to a 10% sucrose solution in adolescent and young-adult Wistar rats. Sucrose groups developed elevated fasting blood glucose levels after the diet intervention, despite drawing <15% of calories from sucrose and gaining no more weight than controls. In subsequent behavioral testing, sucrose groups were impaired on the Morris Water Maze, with some residual deficits in spatial memory observed more than 6 weeks after the end of sucrose exposure. Further, results from outcome devaluation testing indicated that in the older cohort of rats, those fed sucrose showed reduced sensitivity to devaluation of the outcome, suggestive of differences in instrumental learning following sucrose exposure. Data provide strong evidence that sucrose consumption can induce deficits in spatial cognition and reward-oriented behavior at levels that resemble patterns of sugar drink consumption in young people, and which can remain long after exposure. PMID:23954407

  20. Basic Performance of a Logic Intellectual Property Compatible Embedded Dynamic Random Access Memory with Cylinder Capacitors in Low-k/Cu Back End on the Line Layers

    NASA Astrophysics Data System (ADS)

    Kume, Ippei; Inoue, Naoya; Hijioka, Ken'ichiro; Kawahara, Jun; Takeda, Kouichi; Furutake, Naoya; Shirai, Hiroki; Kazama, Kenya; Kuwabara, Shin'ichi; Watarai, Msasatoshi; Sakoh, Takashi; Takahashi, Takafumi; Ogura, Takashi; Taiji, Toshiji; Kasama, Yoshiko; Sakamoto, Misato; Hane, Masami; Hayashi, Yoshihiro

    2012-02-01

    We have confirmed the basic performance of a new logic intellectual property (IP) compatible (LIC) embedded dynamic random access memory (eDRAM) with cylinder capacitors in the low-k/Cu back end on the line (BEOL) layers. The LIC-eDRAM reduces the contact (CT) height, or essentially the RC delays due to the parasitic component to the contact. By circuit simulation, a 28-nm-node LIC-eDRAM with the reduced CT height controls the logic delay with Δτd < 5% to that of 28-nm-node standard complementary metal oxide semiconductor (CMOS) logics, enabling us ensure the logic IP compatibility. This was confirmed also by a 40-nm-node LIC-eDRAM test-chip fabricated. The 40-nm-node inverter delays in the test-chip were controlled actually within Δτd < 5%, referred to those of a pure-CMOS logic LSI. Meanwhile the retention time of the DRAM macro was in the range of milliseconds, which has no difference to that of a conventional eDRAM with a capacitor-on-bitline (COB) structure. The LIC-eDRAM is one type of BEOL memory on standard CMOS devices, and is sustainable for widening eDRAM applications combined with a variety of leading-edge CMOS logic IPs, especially beyond 28-nm-nodes.

  1. The role of internal structure in the anomalous switching dynamics of metal-oxide/polymer resistive random access memories

    NASA Astrophysics Data System (ADS)

    Rocha, Paulo R. F.; Kiazadeh, Asal; De Leeuw, Dago M.; Meskers, Stefan C. J.; Verbakel, Frank; Taylor, David M.; Gomes, Henrique L.

    2013-04-01

    The dynamic response of a non-volatile, bistable resistive memory fabricated in the form of Al2O3/polymer diodes has been probed in both the off- and on-state using triangular and step voltage profiles. The results provide insight into the wide spread in switching times reported in the literature and explain an apparently anomalous behaviour of the on-state, namely the disappearance of the negative differential resistance region at high voltage scan rates which is commonly attributed to a "dead time" phenomenon. The off-state response follows closely the predictions based on a classical, two-layer capacitor description of the device. As voltage scan rates increase, the model predicts that the fraction of the applied voltage, Vox, appearing across the oxide decreases. Device responses to step voltages in both the off- and on-state show that switching events are characterized by a delay time. Coupling such delays to the lower values of Vox attained during fast scan rates, the anomalous observation in the on-state that, device currents decrease with increasing voltage scan rate, is readily explained. Assuming that a critical current is required to turn off a conducting channel in the oxide, a tentative model is suggested to explain the shift in the onset of negative differential resistance to lower voltages as the voltage scan rate increases. The findings also suggest that the fundamental limitations on the speed of operation of a bilayer resistive memory are the time- and voltage-dependences of the switch-on mechanism and not the switch-off process.

  2. Retracing Memories

    ERIC Educational Resources Information Center

    Harrison, David L.

    2005-01-01

    There are plenty of paths to poetry but few are as accessible as retracing ones own memories. When students are asked to write about something they remember, they are given them the gift of choosing from events that are important enough to recall. They remember because what happened was funny or scary or embarrassing or heartbreaking or silly.…

  3. GRACES: Gemini remote access to CFHT ESPaDOnS spectrograph through the longest astronomical fiber ever made: experimental phase completed

    NASA Astrophysics Data System (ADS)

    Chene, André-Nicolas; Padzer, John; Barrick, Gregory; Anthony, Andre; Benedict, Tom; Duncan, Dave; Gigoux, Pedro; Kleinman, Scot; Malo, Lison; Martioli, Eder; Moutou, Claire; Placco, Vinicius; Reshetovand, Vladimir; Rhee, Jaehyon; Roth, Katherine; Schiavon, Ricardo; Tollestrup, Eric V.; Vermeulen, Tom A.; White, John; Wooff, Robert

    2014-07-01

    The Gemini Remote Access to CFHT ESPaDONS Spectrograph has achieved first light of its experimental phase in May 2014. It successfully collected light from the Gemini North telescope and sent it through two 270 m optical fibers to the the ESPaDOnS spectrograph at CFHT to deliver high-resolution spectroscopy across the optical region. The fibers gave an average focal ratio degradation of 14% on sky, and a maximum transmittance of 85% at 800nm. GRACES achieved delivering spectra with a resolution power of R = 40,000 and R = 66,000 between 400 and 1,000 nm. It has a ~8% throughput and is sensitive to target fainter than 21st mag in 1 hour. The average acquisition time of a target is around 10 min. This project is a great example of a productive collaboration between two observatories on Maunakea that was successful due to the reciprocal involvement of the Gemini, CFHT, and NRC Herzberg teams, and all the staff involved closely or indirectly.

  4. Magnetic bubble domain memories

    NASA Technical Reports Server (NTRS)

    Ypma, J. E.

    1974-01-01

    Some attractive features of Bubble Domain Memory and its relation to existing technologies are discussed. Two promising applications are block access mass memory and tape recorder replacement. The required chip capabilities for these uses are listed, and the specifications for a block access mass memory designed to fit between core and HPT disk are presented. A feasibility model for a tape recorder replacement is introduced.

  5. Supporting shared data structures on distributed memory architectures

    NASA Technical Reports Server (NTRS)

    Koelbel, Charles; Mehrotra, Piyush; Vanrosendale, John

    1990-01-01

    Programming nonshared memory systems is more difficult than programming shared memory systems, since there is no support for shared data structures. Current programming languages for distributed memory architectures force the user to decompose all data structures into separate pieces, with each piece owned by one of the processors in the machine, and with all communication explicitly specified by low-level message-passing primitives. A new programming environment is presented for distributed memory architectures, providing a global name space and allowing direct access to remote parts of data values. The analysis and program transformations required to implement this environment are described, and the efficiency of the resulting code on the NCUBE/7 and IPSC/2 hypercubes are described.

  6. Retention modeling for ultra-thin density of Cu-based conductive bridge random access memory (CBRAM)

    NASA Astrophysics Data System (ADS)

    Aga, Fekadu Gochole; Woo, Jiyong; Lee, Sangheon; Song, Jeonghwan; Park, Jaesung; Park, Jaehyuk; Lim, Seokjae; Sung, Changhyuck; Hwang, Hyunsang

    2016-02-01

    We investigate the effect of Cu concentration On-state resistance retention characteristics of W/Cu/Ti/HfO2/Pt memory cell. The development of RRAM device for application depends on the understanding of the failure mechanism and the key parameters for device optimization. In this study, we develop analytical expression for cations (Cu+) diffusion model using Gaussian distribution for detailed analysis of data retention time at high temperature. It is found that the improvement of data retention time depends not only on the conductive filament (CF) size but also on Cu atoms concentration density in the CF. Based on the simulation result, better data retention time is observed for electron wave function associated with Cu+ overlap and an extended state formation. This can be verified by analytical calculation of Cu atom defects inside the filament, based on Cu+ diffusion model. The importance of Cu diffusion for the device reliability and the corresponding local temperature of the filament were analyzed by COMSOL Multiphysics simulation.

  7. Over-the-horizon, connected home/office (OCHO): situation management of environmental, medical, and security conditions at remote premises via broadband wireless access

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2010-04-01

    Broadband wireless access standards, together with advances in the development of commercial sensing and actuator devices, enable the feasibility of a consumer service for a multi-sensor system that monitors the conditions within a residence or office: the environment/infrastructure, patient-occupant health, and physical security. The proposed service is a broadband reimplementation and combination of existing services to allow on-demand reports on and management of the conditions by remote subscribers. The flow of on-demand reports to subscribers and to specialists contracted to mitigate out-of-tolerance conditions is the foreground process. Service subscribers for an over-the-horizon connected home/office (OCHO) monitoring system are the occupant of the premises and agencies, contracted by the service provider, to mitigate or resolve any observed out-of-tolerance condition(s) at the premises. Collectively, these parties are the foreground users of the OCHO system; the implemented wireless standards allow the foreground users to be mobile as they request situation reports on demand from the subsystems on remote conditions that comprise OCHO via wireless devices. An OCHO subscriber, i.e., a foreground user, may select the level of detail found in on-demand reports, i.e., the amount of information displayed in the report of monitored conditions at the premises. This is one context of system operations. While foreground reports are sent only periodically to subscribers, the information generated by the monitored conditions at the premises is continuous and is transferred to a background configuration of servers on which databases reside. These databases are each used, generally, in non-real time, for the assessment and management of situations defined by attributes like those being monitored in the foreground by OCHO. This is the second context of system operations. Context awareness and management of conditions at the premises by a second group of analysts and

  8. Reproducible resistive switching in nonstoichiometric nickel oxide films grown by rf reactive sputtering for resistive random access memory applications

    SciTech Connect

    Park, Jae-Wan; Park, Jong-Wan; Kim, Dal-Young; Lee, Jeon-Kook

    2005-09-15

    Ni{sub 1-{delta}}O binary oxide films were deposited on Pt/Ti/SiO{sub 2}/Si substrates by radio-frequency reactive magnetron sputtering. The NiO-based metal-oxide-metal structures were fabricated for measurement of electrical properties. The electrical properties of the Pt/Ni{sub 1-{delta}}O/Pt structure as a function of growth temperature were investigated. The growth temperature was varied from room temperature to 400 deg. C. From all samples, negative resistance phenomenon and nonvolatile memory switching behavior were observed. The ratios between the high-resistance state (OFF state) and the low-resistance state (ON state) were larger than. 10{sup 2}. As the growth temperature was increased, both SET and RESET voltages increased due to the decrease of defects in nickel oxide films. On the basis of x-ray diffraction patterns, we confirmed that the defects in Ni{sub 1-{delta}}O film decreased with increasing the growth temperature due to sufficient diffusion and redistribution of adatoms. X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy analysis revealed that the nickel oxide films were Ni deficient and that Ni had three different Ni bond states caused by various defects in nickel oxide films. In order to investigate the influence of the upper limit of SET current (i.e., Compliance SET current), the compliance SET current was varied from 1 to 50 mA. This result showed that the ON-state current and the RESET voltage were strongly dependent on the magnitude of the compliance SET current. As the compliance SET current was increased, both the ON-state current and the RESET voltage increased due to the increase of the conducting path. The results suggest that the resistance switching behavior is related to the formation and fracture of the conducting path which is composed of defects in the nickel oxide film.

  9. Memory consolidation.

    PubMed

    Squire, Larry R; Genzel, Lisa; Wixted, John T; Morris, Richard G

    2015-08-01

    Conscious memory for a new experience is initially dependent on information stored in both the hippocampus and neocortex. Systems consolidation is the process by which the hippocampus guides the reorganization of the information stored in the neocortex such that it eventually becomes independent of the hippocampus. Early evidence for systems consolidation was provided by studies of retrograde amnesia, which found that damage to the hippocampus-impaired memories formed in the recent past, but typically spared memories formed in the more remote past. Systems consolidation has been found to occur for both episodic and semantic memories and for both spatial and nonspatial memories, although empirical inconsistencies and theoretical disagreements remain about these issues. Recent work has begun to characterize the neural mechanisms that underlie the dialogue between the hippocampus and neocortex (e.g., "neural replay," which occurs during sharp wave ripple activity). New work has also identified variables, such as the amount of preexisting knowledge, that affect the rate of consolidation. The increasing use of molecular genetic tools (e.g., optogenetics) can be expected to further improve understanding of the neural mechanisms underlying consolidation. PMID:26238360

  10. Residual Clamping Force and Dynamic Random Access Memory Data Retention Improved by Gate Tungsten Etch Dechucking Condition in a Bipolar Electrostatic Chuck

    NASA Astrophysics Data System (ADS)

    Lee, Chung-Yuan; Lai, Chao-Sung; Yang, Chia-Ming; Wang, David HL; Lin, Betty; Lee, Siimon; Huang, Chi-Hung; Wei, Chen Chang

    2012-08-01

    It was found that the residual clamping force of bipolar electrostatic chucks created by the residual charge between a wafer and an electrode would not only cause a wafer sticking problem but also degrade dynamic random access memory (DRAM) data retention performance. The residual clamping force and data retention fail bit count (FBC) of DRAM showed strong correlations to the gate tungsten etch dechucking process condition. Wafer sticking only degraded DRAM cell retention performance, and did not influence any in-line measurement or electrical parameters. Electrical characterization analysis of the FBC proved that the retention loss was mainly due to junction leakage rather than gate-induced-drain-leakage current. A new approach was proposed to suppress this leakage by introducing N2 gas instead of O2 to supply more plasma charges for neutralizing the wafer surface residual charges. The wafer shift dynamic alignment (DA) offset and retention FBC could be reduced by 50 and 40%, respectively. Poor data retention was suspected because of the compressive stress caused by wafer sticking DA shift resulting in a high electric field at the junction and an increase in junction leakage at the storage node.

  11. Sustained Resistive Switching in a Single Cu:7,7,8,8-tetracyanoquinodimethane Nanowire: A Promising Material for Resistive Random Access Memory

    NASA Astrophysics Data System (ADS)

    Basori, Rabaya; Kumar, Manoranjan; Raychaudhuri, Arup K.

    2016-06-01

    We report a new type of sustained and reversible unipolar resistive switching in a nanowire device made from a single strand of Cu:7,7,8,8-tetracyanoquinodimethane (Cu:TCNQ) nanowire (diameter <100 nm) that shows high ON/OFF ratio (~103), low threshold voltage of switching (~3.5 V) and large cycling endurance (>103). This indicates a promising material for high density resistive random access memory (ReRAM) device integration. Switching is observed in Cu:TCNQ single nanowire devices with two different electrode configuration: symmetric (C-Pt/Cu:TCNQ/C-Pt) and asymmetric (Cu/Cu:TCNQ/C-Pt), where contacts connecting the nanowire play an important role. This report also developed a method of separating out the electrode and material contributions in switching using metal-semiconductor-metal (MSM) device model along with a direct 4-probe resistivity measurement of the nanowire in the OFF as well as ON state. The device model was followed by a phenomenological model of current transport through the nanowire device which shows that lowering of potential barrier at the contacts likely occur due to formation of Cu filaments in the interface between nanowire and contact electrodes. We obtain quantitative agreement of numerically analyzed results with the experimental switching data.

  12. Power- and Low-Resistance-State-Dependent, Bipolar Reset-Switching Transitions in SiN-Based Resistive Random-Access Memory.

    PubMed

    Kim, Sungjun; Park, Byung-Gook

    2016-12-01

    A study on the bipolar-resistive switching of an Ni/SiN/Si-based resistive random-access memory (RRAM) device shows that the influences of the reset power and the resistance value of the low-resistance state (LRS) on the reset-switching transitions are strong. For a low LRS with a large conducting path, the sharp reset switching, which requires a high reset power (>7 mW), was observed, whereas for a high LRS with small multiple-conducting paths, the step-by-step reset switching with a low reset power (<7 mW) was observed. The attainment of higher nonlinear current-voltage (I-V) characteristics in terms of the step-by-step reset switching is due to the steep current-increased region of the trap-controlled space charge-limited current (SCLC) model. A multilevel cell (MLC) operation, for which the reset stop voltage (V STOP) is used in the DC sweep mode and an incremental amplitude is used in the pulse mode for the step-by-step reset switching, is demonstrated here. The results of the present study suggest that well-controlled conducting paths in a SiN-based RRAM device, which are not too strong and not too weak, offer considerable potential for the realization of low-power and high-density crossbar-array applications. PMID:27518231

  13. Correlation of anomalous write error rates and ferromagnetic resonance spectrum in spin-transfer-torque-magnetic-random-access-memory devices containing in-plane free layers

    SciTech Connect

    Evarts, Eric R.; Rippard, William H.; Pufall, Matthew R.; Heindl, Ranko

    2014-05-26

    In a small fraction of magnetic-tunnel-junction-based magnetic random-access memory devices with in-plane free layers, the write-error rates (WERs) are higher than expected on the basis of the macrospin or quasi-uniform magnetization reversal models. In devices with increased WERs, the product of effective resistance and area, tunneling magnetoresistance, and coercivity do not deviate from typical device properties. However, the field-swept, spin-torque, ferromagnetic resonance (FS-ST-FMR) spectra with an applied DC bias current deviate significantly for such devices. With a DC bias of 300 mV (producing 9.9 × 10{sup 6} A/cm{sup 2}) or greater, these anomalous devices show an increase in the fraction of the power present in FS-ST-FMR modes corresponding to higher-order excitations of the free-layer magnetization. As much as 70% of the power is contained in higher-order modes compared to ≈20% in typical devices. Additionally, a shift in the uniform-mode resonant field that is correlated with the magnitude of the WER anomaly is detected at DC biases greater than 300 mV. These differences in the anomalous devices indicate a change in the micromagnetic resonant mode structure at high applied bias.

  14. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition.

    PubMed

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-01-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption. PMID:27312225

  15. Investigation of Cr0.06(Sb4Te)0.94 alloy for high-speed and high-data-retention phase change random access memory applications

    NASA Astrophysics Data System (ADS)

    Li, Le; Song, Sannian; Zhang, Zhonghua; Song, Zhitang; Cheng, Yan; Lv, Shilong; Wu, Liangcai; Liu, Bo; Feng, Songlin

    2015-08-01

    The effects of Cr doping on the structural and electrical properties of Cr x (Sb4Te)1- x materials have been investigated in order to solve the contradiction between thermal stability and fast crystallization speed of Sb4Te alloys. Cr0.06(Sb4Te)0.94 alloy is considered to be a potential candidate for phase change random access memory (PCM), as evidenced by a higher crystallization temperature (204 °C), a better data retention ability (137.6 °C for 10 years), a lower melting point (558 °C), a lower energy consumption, and a faster switching speed in comparison with those of Ge2Sb2Te5. A reversible switching between set and reset states can be realized by an electric pulse as short as 5 ns for Cr0.06(Sb4Te)0.94-based PCM cell. In addition, Cr0.06(Sb4Te)0.94 shows good endurance up to 1.1 × 104 cycles with a resistance ratio of about two orders of magnitude.

  16. Highly Reliable 0.15 μm/14 F2 Cell Ferroelectric Random Access Memory Capacitor Using SrRuO3 Buffer Layer

    NASA Astrophysics Data System (ADS)

    Heo, Jang‑Eun; Bae, Byoung‑Jae; Yoo, Dong‑Chul; Nam, Sang‑Don; Lim, Ji‑Eun; Im, Dong‑Hyun; Joo, Suk‑Ho; Jung, Yong‑Ju; Choi, Suk‑Hun; Park, Soon‑Oh; Kim, Hee‑Seok; Chung, U‑In; Moon, Joo‑Tae

    2006-04-01

    We investigated a novel technique of modifying the interface between a Pb(ZrxTi1-x)O3 (PZT) thin film and electrodes for high density 64 Mbit ferroelectric random access memory (FRAM) device. Using a SrRuO3 buffer layer, we successfully developed highly reliable 0.15 μm/14 F2 cell FRAM capacitors with 75-nm-thick polycrystalline PZT thin films. The SrRuO3 buffer layer greatly enhanced ferroelectric characteristics due to the decrease in interfacial defect density. In PZT capacitors with a total thickness of 180 nm for whole capacitor stack, a remnant polarization of approximately 42 μC/cm2 was measured with a 1.4 V operation. In addition, an opposite state remnant polarization loss of less than 15% was observed after baking at 150 °C for 100 h. In particular, we found that the SrRuO3 buffer layer also played a key role in inhibiting the diffusion of Pb and O from the PZT thin films.

  17. Integration and Electrical Properties of Novel Ferroelectric Capacitors for 0.25 μm 1 Transistor 1 Capacitor Ferroelectric Random Access Memory (1T1C FRAM)

    NASA Astrophysics Data System (ADS)

    Song, Y. J.; Jang, N. W.; Jung, D. J.; Kim, H. H.; Joo, H. J.; Lee, S. Y.; Lee, K. M.; Joo, S. H.; Park, S. O.; Kim, Kinam

    2002-04-01

    Since the space margin between capacitors has been greatly reduced in 32 Mb high-density ferroelectric random access memory (FRAM) with a 0.25 μm design rule, considering the limitation of current etching technology, the stack height of ferroelectric capacitors should be minimized for stable node separation. In this paper, novel capacitors with a total thickness of 4000 Å were prepared using a seeding layer, low temperature processing, and optimal top electrode annealing. The 1000 Å Pb(Zr1-xTix)O3 (PZT) films showed excellent structural and ferroelectric properties such as strong (111) orientation and large remanent polarization of 40 μC/cm2. The low stack capacitors were then implemented into 0.6 μm and prototype 0.25 μm FRAM. Compared to a conventional capacitor stack, the ferroelectric capacitors exhibited adequate sensing margin of 250 fC, thus giving rise to a fully working die of 4 Mb FRAM. Therefore, it was clearly demonstrated that the novel capacitors can enable the realization of a high-density 32 Mb FRAM device with a 0.25 μm design rule.

  18. Plasma-Assisted Dry Etching of Ferroelectric Capacitor Modules and Application to a 32M Ferroelectric Random Access Memory Devices with Submicron Feature Sizes

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Woo; Joo, Suk-Ho; Cho, Sung Lae; Son, Yoon-Ho; Lee, Kyu-Mann; Nam, Sang-Don; Park, Kun-Sang; Lee, Yong-Tak; Seo, Jung-Suk; Kim, Young-Dae; An, Hyeong-Geun; Kim, Hyoung-Joon; Jung, Yong-Ju; Heo, Jang-Eun; Lee, Moon-Sook; Park, Soon-Oh; Chung, U-In; Moon, Joo-Tae

    2002-11-01

    In the manufacturing of a 32M ferroelectric random access memory (FRAM) device on the basis of 0.25 design rule (D/R), one of the most difficult processes is to pattern a submicron capacitor module while retaining good ferroelectric properties. In this paper, we report the ferroelectric property of patterned submicron capacitor modules with a stack height of 380 nm, where the 100 nm-thick Pb(Zr, Ti)O3 (PZT) films were prepared by the sol-gel method. After patterning, overall sidewall slope was approximately 70° and cell-to-cell node separation was made to be 80 nm to prevent possible twin-bit failure in the device. Finally, several heat treatment conditions were investigated to retain the ferroelectric property of the patterned capacitor. It was found that rapid thermal processing (RTP) treatment yields better properties than conventional furnace annealing. This result is directly related to the near-surface chemistry of the PZT films, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The resultant switching polarization value of the submicron capacitor was approximately 30 μC/cm2 measured at 3 V.

  19. Material insights of HfO2-based integrated 1-transistor-1-resistor resistive random access memory devices processed by batch atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Niu, Gang; Kim, Hee-Dong; Roelofs, Robin; Perez, Eduardo; Schubert, Markus Andreas; Zaumseil, Peter; Costina, Ioan; Wenger, Christian

    2016-06-01

    With the continuous scaling of resistive random access memory (RRAM) devices, in-depth understanding of the physical mechanism and the material issues, particularly by directly studying integrated cells, become more and more important to further improve the device performances. In this work, HfO2-based integrated 1-transistor-1-resistor (1T1R) RRAM devices were processed in a standard 0.25 μm complementary-metal-oxide-semiconductor (CMOS) process line, using a batch atomic layer deposition (ALD) tool, which is particularly designed for mass production. We demonstrate a systematic study on TiN/Ti/HfO2/TiN/Si RRAM devices to correlate key material factors (nano-crystallites and carbon impurities) with the filament type resistive switching (RS) behaviours. The augmentation of the nano-crystallites density in the film increases the forming voltage of devices and its variation. Carbon residues in HfO2 films turn out to be an even more significant factor strongly impacting the RS behaviour. A relatively higher deposition temperature of 300 °C dramatically reduces the residual carbon concentration, thus leading to enhanced RS performances of devices, including lower power consumption, better endurance and higher reliability. Such thorough understanding on physical mechanism of RS and the correlation between material and device performances will facilitate the realization of high density and reliable embedded RRAM devices with low power consumption.

  20. Sustained Resistive Switching in a Single Cu:7,7,8,8-tetracyanoquinodimethane Nanowire: A Promising Material for Resistive Random Access Memory.

    PubMed

    Basori, Rabaya; Kumar, Manoranjan; Raychaudhuri, Arup K

    2016-01-01

    We report a new type of sustained and reversible unipolar resistive switching in a nanowire device made from a single strand of Cu:7,7,8,8-tetracyanoquinodimethane (Cu:TCNQ) nanowire (diameter <100 nm) that shows high ON/OFF ratio (~10(3)), low threshold voltage of switching (~3.5 V) and large cycling endurance (>10(3)). This indicates a promising material for high density resistive random access memory (ReRAM) device integration. Switching is observed in Cu:TCNQ single nanowire devices with two different electrode configuration: symmetric (C-Pt/Cu:TCNQ/C-Pt) and asymmetric (Cu/Cu:TCNQ/C-Pt), where contacts connecting the nanowire play an important role. This report also developed a method of separating out the electrode and material contributions in switching using metal-semiconductor-metal (MSM) device model along with a direct 4-probe resistivity measurement of the nanowire in the OFF as well as ON state. The device model was followed by a phenomenological model of current transport through the nanowire device which shows that lowering of potential barrier at the contacts likely occur due to formation of Cu filaments in the interface between nanowire and contact electrodes. We obtain quantitative agreement of numerically analyzed results with the experimental switching data. PMID:27245099