Capacity for patterns and sequences in Kanerva's SDM as compared to other associative memory models

NASA Technical Reports Server (NTRS)

Keeler, James D.

1987-01-01

The information capacity of Kanerva's Sparse Distributed Memory (SDM) and Hopfield-type neural networks is investigated. Under the approximations used, it is shown that the total information stored in these systems is proportional to the number connections in the network. The proportionality constant is the same for the SDM and Hopfield-type models independent of the particular model, or the order of the model. The approximations are checked numerically. This same analysis can be used to show that the SDM can store sequences of spatiotemporal patterns, and the addition of time-delayed connections allows the retrieval of context dependent temporal patterns. A minor modification of the SDM can be used to store correlated patterns.

Parallel State Space Construction for a Model Checking Based on Maximality Semantics

NASA Astrophysics Data System (ADS)

El Abidine Bouneb, Zine; Saīdouni, Djamel Eddine

2009-03-01

The main limiting factor of the model checker integrated in the concurrency verification environment FOCOVE [1, 2], which use the maximality based labeled transition system (noted MLTS) as a true concurrency model[3, 4], is currently the amount of available physical memory. Many techniques have been developed to reduce the size of a state space. An interesting technique among them is the alpha equivalence reduction. Distributed memory execution environment offers yet another choice. The main contribution of the paper is to show that the parallel state space construction algorithm proposed in [5], which is based on interleaving semantics using LTS as semantic model, may be adapted easily to the distributed implementation of the alpha equivalence reduction for the maximality based labeled transition systems.

Diabetes: Unique to Older Adults

MedlinePlus

... quickly. The earlier depression is treated, the better. Memory Loss Problems with memory and brain function can be more common in ... provider may do some tests to check for memory loss. Be sure to let your provider know ...

Consistency Checking in Hypothesis Generation,

DTIC Science & Technology

1979-07-01

In a semantic network model of memory (Col l ins and Loftu s , 1975) , concepts are repr~~ented as nodes inter connected by re lational pathw ays...fornia 90007 Defense Dooinentation Center: C~ neron Stat ion , Bldg . 5 Dr. Kenneth I lain~ondAlexandria , Vi rg ir& a 22314 (i~ c>r ;) Institt~to of

Formal verification of a set of memory management units

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Molecular dynamics of conformational substates for a simplified protein model

NASA Astrophysics Data System (ADS)

Grubmüller, Helmut; Tavan, Paul

1994-09-01

Extended molecular dynamics simulations covering a total of 0.232 μs have been carried out on a simplified protein model. Despite its simplified structure, that model exhibits properties similar to those of more realistic protein models. In particular, the model was found to undergo transitions between conformational substates at a time scale of several hundred picoseconds. The computed trajectories turned out to be sufficiently long as to permit a statistical analysis of that conformational dynamics. To check whether effective descriptions neglecting memory effects can reproduce the observed conformational dynamics, two stochastic models were studied. A one-dimensional Langevin effective potential model derived by elimination of subpicosecond dynamical processes could not describe the observed conformational transition rates. In contrast, a simple Markov model describing the transitions between but neglecting dynamical processes within conformational substates reproduced the observed distribution of first passage times. These findings suggest, that protein dynamics generally does not exhibit memory effects at time scales above a few hundred picoseconds, but confirms the existence of memory effects at a picosecond time scale.

Prospective Memory in HIV-associated Neurocognitive Disorders (HAND): The Neuropsychological Dynamics of Time Monitoring

PubMed Central

Doyle, Katie L.; Loft, Shayne; Morgan, Erin E.; Weber, Erica; Cushman, Clint; Johnston, Elaine; Grant, Igor; Woods, Steven Paul

2013-01-01

Strategic monitoring during a delay interval is theorized to be an essential feature of time-based prospective memory (TB PM), the cognitive architecture of which is thought to rely heavily on frontostriatal systems and executive functions. This hypothesis was examined in 55 individuals with HIV-associated neurocognitive disorders (HAND) and 108 seronegative comparison participants who were administered the Memory for Intentions Screening Test (MIST), during which time monitoring (clock checking) behavior was measured. Results revealed a significant interaction between HAND group and the frequency of clock checking, in which individuals with HAND monitored checked the clock significantly less often than the comparison group across the TB PM retention intervals of the MIST. Subsequent analyses in the HAND sample revealed that the frequency of clocking checking was positively related to overall TB performance, as well as to standard clinical measures of retrospective memory and verbal fluency. These findings add support to a growing body of research elucidating TB PM’s reliance on strategic monitoring processes dependent upon intact frontostriatal systems. HIV-associated TB strategic time monitoring deficits may manifest in poorer functioning outcomes, including medication non-adherence and dependence in activities of daily living. Future research is needed to further delineate the cognitive mechanisms underlying strategic time monitoring in order to advise rehabilitation strategies for reducing HAND related TB PM deficits. PMID:23465043

Algebraic model checking for Boolean gene regulatory networks.

PubMed

Tran, Quoc-Nam

2011-01-01

We present a computational method in which modular and Groebner bases (GB) computation in Boolean rings are used for solving problems in Boolean gene regulatory networks (BN). In contrast to other known algebraic approaches, the degree of intermediate polynomials during the calculation of Groebner bases using our method will never grow resulting in a significant improvement in running time and memory space consumption. We also show how calculation in temporal logic for model checking can be done by means of our direct and efficient Groebner basis computation in Boolean rings. We present our experimental results in finding attractors and control strategies of Boolean networks to illustrate our theoretical arguments. The results are promising. Our algebraic approach is more efficient than the state-of-the-art model checker NuSMV on BNs. More importantly, our approach finds all solutions for the BN problems.

Energy reduction through voltage scaling and lightweight checking

NASA Astrophysics Data System (ADS)

Kadric, Edin

As the semiconductor roadmap reaches smaller feature sizes and the end of Dennard Scaling, design goals change, and managing the power envelope often dominates delay minimization. Voltage scaling remains a powerful tool to reduce energy. We find that it results in about 60% geomean energy reduction on top of other common low-energy optimizations with 22nm CMOS technology. However, when voltage is reduced, it becomes easier for noise and particle strikes to upset a node, potentially causing Silent Data Corruption (SDC). The 60% energy reduction, therefore, comes with a significant drop in reliability. Duplication with checking and triple-modular redundancy are traditional approaches used to combat transient errors, but spending 2--3x the energy for redundant computation can diminish or reverse the benefits of voltage scaling. As an alternative, we explore the opportunity to use checking operations that are cheaper than the base computation they are guarding. We devise a classification system for applications and their lightweight checking characteristics. In particular, we identify and evaluate the effectiveness of lightweight checks in a broad set of common tasks in scientific computing and signal processing. We find that the lightweight checks cost only a fraction of the base computation (0-25%) and allow us to recover the reliability losses from voltage scaling. Overall, we show about 50% net energy reduction without compromising reliability compared to operation at the nominal voltage. We use FPGAs (Field-Programmable Gate Arrays) in our work, although the same ideas can be applied to different systems. On top of voltage scaling, we explore other common low-energy techniques for FPGAs: transmission gates, gate boosting, power gating, low-leakage (high-Vth) processes, and dual-V dd architectures. We do not scale voltage for memories, so lower voltages help us reduce logic and interconnect energy, but not memory energy. At lower voltages, memories become dominant, and we get diminishing returns from continuing to scale voltage. To ensure that memories do not become a bottleneck, we also design an energy-robust FPGA memory architecture, which attempts to minimize communication energy due to mismatches between application and architecture. We do this alongside application parallelism tuning. We show our techniques on a wide range of applications, including a large real-time system used for Wide-Area Motion Imaging (WAMI).

Protecting quantum memories using coherent parity check codes

NASA Astrophysics Data System (ADS)

Roffe, Joschka; Headley, David; Chancellor, Nicholas; Horsman, Dominic; Kendon, Viv

2018-07-01

Coherent parity check (CPC) codes are a new framework for the construction of quantum error correction codes that encode multiple qubits per logical block. CPC codes have a canonical structure involving successive rounds of bit and phase parity checks, supplemented by cross-checks to fix the code distance. In this paper, we provide a detailed introduction to CPC codes using conventional quantum circuit notation. We demonstrate the implementation of a CPC code on real hardware, by designing a [[4, 2, 2

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.

Understanding Memory Loss | NIH MedlinePlus the Magazine

MedlinePlus

... urine. She or he also checks your memory, problem solving, counting, and language skills. The doctor also may suggest a brain scan to show the normal and problem areas in the brain. Once the cause of ...

Low-density parity-check codes for volume holographic memory systems.

PubMed

Pishro-Nik, Hossein; Rahnavard, Nazanin; Ha, Jeongseok; Fekri, Faramarz; Adibi, Ali

2003-02-10

We investigate the application of low-density parity-check (LDPC) codes in volume holographic memory (VHM) systems. We show that a carefully designed irregular LDPC code has a very good performance in VHM systems. We optimize high-rate LDPC codes for the nonuniform error pattern in holographic memories to reduce the bit error rate extensively. The prior knowledge of noise distribution is used for designing as well as decoding the LDPC codes. We show that these codes have a superior performance to that of Reed-Solomon (RS) codes and regular LDPC counterparts. Our simulation shows that we can increase the maximum storage capacity of holographic memories by more than 50 percent if we use irregular LDPC codes with soft-decision decoding instead of conventionally employed RS codes with hard-decision decoding. The performance of these LDPC codes is close to the information theoretic capacity.

Principles of continuous quality improvement applied to intravenous therapy.

PubMed

Dunavin, M K; Lane, C; Parker, P E

1994-01-01

Documentation of the application of the principles of continuous quality improvement (CQI) to the health care setting is crucial for understanding the transition from traditional management models to CQI models. A CQI project was designed and implemented by the IV Therapy Department at Lawrence Memorial Hospital to test the application of these principles to intravenous therapy and as a learning tool for the entire organization. Through a prototype inventory project, significant savings in cost and time were demonstrated using check sheets, flow diagrams, control charts, and other statistical tools, as well as using the Plan-Do-Check-Act cycle. As a result, a primary goal, increased time for direct patient care, was achieved. Eight hours per week in nursing time was saved, relationships between two work areas were improved, and $6,000 in personnel costs, storage space, and inventory were saved.

A generalized memory test algorithm

NASA Technical Reports Server (NTRS)

Milner, E. J.

1982-01-01

A general algorithm for testing digital computer memory is presented. The test checks that (1) every bit can be cleared and set in each memory work, and (2) bits are not erroneously cleared and/or set elsewhere in memory at the same time. The algorithm can be applied to any size memory block and any size memory word. It is concise and efficient, requiring the very few cycles through memory. For example, a test of 16-bit-word-size memory requries only 384 cycles through memory. Approximately 15 seconds were required to test a 32K block of such memory, using a microcomputer having a cycle time of 133 nanoseconds.

Comparative Effect of Memory and Cognitive Strategies Training on EFL Intermediate Learners' Vocabulary Learning

ERIC Educational Resources Information Center

Banisaeid, Maryam

2013-01-01

The present study was conducted to compare the effect of memory and cognitive strategies training on vocabulary learning of intermediate proficiency group of Iranian learners of English as a foreign language. It is to check how memory and cognitive strategies training affect word learning of EFL intermediate learners (N = 60) who were homogenized…

Aligning observed and modelled behaviour based on workflow decomposition

NASA Astrophysics Data System (ADS)

Wang, Lu; Du, YuYue; Liu, Wei

2017-09-01

When business processes are mostly supported by information systems, the availability of event logs generated from these systems, as well as the requirement of appropriate process models are increasing. Business processes can be discovered, monitored and enhanced by extracting process-related information. However, some events cannot be correctly identified because of the explosion of the amount of event logs. Therefore, a new process mining technique is proposed based on a workflow decomposition method in this paper. Petri nets (PNs) are used to describe business processes, and then conformance checking of event logs and process models is investigated. A decomposition approach is proposed to divide large process models and event logs into several separate parts that can be analysed independently; while an alignment approach based on a state equation method in PN theory enhances the performance of conformance checking. Both approaches are implemented in programmable read-only memory (ProM). The correctness and effectiveness of the proposed methods are illustrated through experiments.

14 CFR 121.315 - Cockpit check procedure.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Cockpit check procedure. 121.315 Section 121.315 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED... emergencies. The procedures must be designed so that a flight crewmember will not need to rely upon his memory...

Teuchos C++ memory management classes, idioms, and related topics, the complete reference : a comprehensive strategy for safe and efficient memory management in C++ for high performance computing.

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

Bartlett, Roscoe Ainsworth

2010-05-01

The ubiquitous use of raw pointers in higher-level code is the primary cause of all memory usage problems and memory leaks in C++ programs. This paper describes what might be considered a radical approach to the problem which is to encapsulate the use of all raw pointers and all raw calls to new and delete in higher-level C++ code. Instead, a set of cooperating template classes developed in the Trilinos package Teuchos are used to encapsulate every use of raw C++ pointers in every use case where it appears in high-level code. Included in the set of memory management classesmore » is the typical reference-counted smart pointer class similar to boost::shared ptr (and therefore C++0x std::shared ptr). However, what is missing in boost and the new standard library are non-reference counted classes for remaining use cases where raw C++ pointers would need to be used. These classes have a debug build mode where nearly all programmer errors are caught and gracefully reported at runtime. The default optimized build mode strips all runtime checks and allows the code to perform as efficiently as raw C++ pointers with reasonable usage. Also included is a novel approach for dealing with the circular references problem that imparts little extra overhead and is almost completely invisible to most of the code (unlike the boost and therefore C++0x approach). Rather than being a radical approach, encapsulating all raw C++ pointers is simply the logical progression of a trend in the C++ development and standards community that started with std::auto ptr and is continued (but not finished) with std::shared ptr in C++0x. Using the Teuchos reference-counted memory management classes allows one to remove unnecessary constraints in the use of objects by removing arbitrary lifetime ordering constraints which are a type of unnecessary coupling [23]. The code one writes with these classes will be more likely to be correct on first writing, will be less likely to contain silent (but deadly) memory usage errors, and will be much more robust to later refactoring and maintenance. The level of debug-mode runtime checking provided by the Teuchos memory management classes is stronger in many respects than what is provided by memory checking tools like Valgrind and Purify while being much less expensive. However, tools like Valgrind and Purify perform a number of types of checks (like usage of uninitialized memory) that makes these tools very valuable and therefore complement the Teuchos memory management debug-mode runtime checking. The Teuchos memory management classes and idioms largely address the technical issues in resolving the fragile built-in C++ memory management model (with the exception of circular references which has no easy solution but can be managed as discussed). All that remains is to teach these classes and idioms and expand their usage in C++ codes. The long-term viability of C++ as a usable and productive language depends on it. Otherwise, if C++ is no safer than C, then is the greater complexity of C++ worth what one gets as extra features? Given that C is smaller and easier to learn than C++ and since most programmers don't know object-orientation (or templates or X, Y, and Z features of C++) all that well anyway, then what really are most programmers getting extra out of C++ that would outweigh the extra complexity of C++ over C? C++ zealots will argue this point but the reality is that C++ popularity has peaked and is becoming less popular while the popularity of C has remained fairly stable over the last decade22. Idioms like are advocated in this paper can help to avert this trend but it will require wide community buy-in and a change in the way C++ is taught in order to have the greatest impact. To make these programs more secure, compiler vendors or static analysis tools (e.g. klocwork23) could implement a preprocessor-like language similar to OpenMP24 that would allow the programmer to declare (in comments) that certain blocks of code should be ''pointer-free'' or allow smaller blocks to be 'pointers allowed'. This would significantly improve the robustness of code that uses the memory management classes described here.« less

Cache directory look-up re-use as conflict check mechanism for speculative memory requests

DOEpatents

Ohmacht, Martin

2013-09-10

In a cache memory, energy and other efficiencies can be realized by saving a result of a cache directory lookup for sequential accesses to a same memory address. Where the cache is a point of coherence for speculative execution in a multiprocessor system, with directory lookups serving as the point of conflict detection, such saving becomes particularly advantageous.

ERP to chess stimuli reveal expert-novice differences in the amplitudes of N2 and P3 components.

PubMed

Wright, Michael J; Gobet, Fernand; Chassy, Philippe; Ramchandani, Payal Nanik

2013-10-01

ERP experiments were conducted to analyze the underlying neural events when chess players make simple judgments of a board position. Fourteen expert players and 14 age-matched novices viewed, for each of four tasks, 128 unique positions on a mini (4 × 4) chess board each presented for 0.5 s. The tasks were to respond: (a) if white king was in check, (b) if black knight was present, (c) if white king was not in check, and (d) if no black knight was present. Experts showed an enhanced N2 with check targets and a larger P3 with knight targets, relative to novices. Expert-novice differences in posterior N2 began as early as 240 ms on check-related searches. Results were consistent with the view that prolonged N2 components reflect matching of current perceptual input to memory, and thus are sensitive to experts' superior pattern recognition and memory retrieval of chunks. Copyright © 2013 Society for Psychophysiological Research.

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

NASA Technical Reports Server (NTRS)

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

1981-01-01

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

Taming the Viper: Software Upgrade for VFAUser and Viper

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

DORIN,RANDALL T.; MOSER III,JOHN C.

2000-08-08

This report describes the procedure and properties of the software upgrade for the Vibration Performance Recorder. The upgrade will check the 20 memory cards for proper read/write operation. The upgrade was successfully installed and uploaded into the Viper and the field laptop. The memory checking routine must run overnight to complete the test, although the laptop need only be connected to the Viper unit until the downloading routine is finished. The routine has limited ability to recognize incomplete or corrupt header and footer files. The routine requires 400 Megabytes of free hard disk space. There is one minor technical flawmore » detailed in the conclusion.« less

Patterns of hippocampal-neocortical interactions in the retrieval of episodic autobiographical memories across the entire life-span of aged adults

PubMed Central

Viard, Armelle; Lebreton, Karine; Chételat, Gaël; Desgranges, Béatrice; Landeau, Brigitte; Young, Alan; De La Sayette, Vincent; Eustache, Francis; Piolino, Pascale

2010-01-01

We previously demonstrated that Episodic Autobiographical Memories (EAMs) rely on a network of brain regions comprising the medial temporal lobe (MTL) and distributed neocortical regions regardless of their remoteness. The findings supported the model of memory consolidation which proposes a permanent role of MTL during EAM retrieval (Multiple-Trace Theory or MTT) rather than a temporary role (standard model). Our present aim was to expand the results by examining the interactions between the MTL and neocortical regions (or MTL-neocortical links) during EAM retrieval with varying retention intervals. We used an experimental paradigm specially designed to engage aged participants in the recollection of EAMs, extracted from five different time-periods, covering their whole life-span, in order to examine correlations between activation in the MTL and neocortical regions. The nature of the memories was checked at debriefing by means of behavioral measures to control the degree of episodicity and properties of memories. Targeted correlational analyses carried out on the MTL, frontal, lateral temporal and posterior regions revealed strong links between the MTL and neocortex during the retrieval of both recent and remote EAMs, challenging the standard model of memory consolidation and supporting MTT instead. Further confirmation was given by results showing that activation in the left and right hippocampi significantly correlated during the retrieval of both recent and remote memories. Correlations among extra-MTL neocortical regions also emerged for all time-periods, confirming the critical role of the prefrontal, temporal (lateral temporal cortex and temporal pole), precuneus and posterior cingulate regions in EAM retrieval. Overall, this paper emphasizes the role of a bilateral network of MTL and neocortical areas whose activation correlate during the recollection of rich phenomenological recent and remote EAMs. PMID:19338022

Maintenance Training Simulators Prime Item Development Specification. Model Specification and Handbook.

DTIC Science & Technology

1985-04-01

and equipment whose operation can be verified with a visual or aural check. The sequence of outputs shall be cyclic, with provisions to stop the...private memory. The decision to provide spare, expansion capability, or a combination of both shall be based on life cycle cost (to the best extent...Computational System should be determined in conjunction with a computer expert (if possible). In any event, it is best to postpone completing - this

The importance of age-related differences in prospective memory: Evidence from diffusion model analyses.

PubMed

Ball, B Hunter; Aschenbrenner, Andrew J

2017-06-09

Event-based prospective memory (PM) refers to relying on environmental cues to trigger retrieval of a deferred action plan from long-term memory. Considerable research has demonstrated PM declines with increased age. Despite efforts to better characterize the attentional processes that underlie these decrements, the majority of research has relied on measures of central tendency to inform theoretical accounts of PM that may not entirely capture the underlying dynamics involved in allocating attention to intention-relevant information. The purpose of the current study was to examine the utility of the diffusion model to better understand the cognitive processes underlying age-related differences in PM. Results showed that emphasizing the importance of the PM intention increased cue detection selectively for older adults. Standard cost analyses revealed that PM importance increased mean response times and accuracy, but not differentially for young and older adults. Consistent with this finding, diffusion model analyses demonstrated that PM importance increased response caution as evidenced by increased boundary separation. However, the selective benefit in cue detection for older adults may reflect peripheral target-checking processes as indicated by changes in nondecision time. These findings highlight the use of modeling techniques to better characterize the processes underlying the relations among aging, attention, and PM.

Resistive switching near electrode interfaces: Estimations by a current model

NASA Astrophysics Data System (ADS)

Schroeder, Herbert; Zurhelle, Alexander; Stemmer, Stefanie; Marchewka, Astrid; Waser, Rainer

2013-02-01

The growing resistive switching database is accompanied by many detailed mechanisms which often are pure hypotheses. Some of these suggested models can be verified by checking their predictions with the benchmarks of future memory cells. The valence change memory model assumes that the different resistances in ON and OFF states are made by changing the defect density profiles in a sheet near one working electrode during switching. The resulting different READ current densities in ON and OFF states were calculated by using an appropriate simulation model with variation of several important defect and material parameters of the metal/insulator (oxide)/metal thin film stack such as defect density and its profile change in density and thickness, height of the interface barrier, dielectric permittivity, applied voltage. The results were compared to the benchmarks and some memory windows of the varied parameters can be defined: The required ON state READ current density of 105 A/cm2 can only be achieved for barriers smaller than 0.7 eV and defect densities larger than 3 × 1020 cm-3. The required current ratio between ON and OFF states of at least 10 requests defect density reduction of approximately an order of magnitude in a sheet of several nanometers near the working electrode.

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

Lee, Seyong; Vetter, Jeffrey S

Computer architecture experts expect that non-volatile memory (NVM) hierarchies will play a more significant role in future systems including mobile, enterprise, and HPC architectures. With this expectation in mind, we present NVL-C: a novel programming system that facilitates the efficient and correct programming of NVM main memory systems. The NVL-C programming abstraction extends C with a small set of intuitive language features that target NVM main memory, and can be combined directly with traditional C memory model features for DRAM. We have designed these new features to enable compiler analyses and run-time checks that can improve performance and guard againstmore » a number of subtle programming errors, which, when left uncorrected, can corrupt NVM-stored data. Moreover, to enable recovery of data across application or system failures, these NVL-C features include a flexible directive for specifying NVM transactions. So that our implementation might be extended to other compiler front ends and languages, the majority of our compiler analyses are implemented in an extended version of LLVM's intermediate representation (LLVM IR). We evaluate NVL-C on a number of applications to show its flexibility, performance, and correctness.« less

A Shared Memory Algorithm and Proof for the Alternative Construct in CSP (Communicating Sequential Processes).

DTIC Science & Technology

1987-08-25

Department Of Computer Science University Of Utah Salt Lake City, UT 84112 August 25, 1987 C IO ,c Acessin Tor i Ifl G I . DTIC ?T3 0 ummouned 0C0 Juxtil t...generated for each instance of an alternative operation. One procedure merits special attention. CheckAndCommit(AltListr, g ): INTEGER is called by process P...in figure 2. CheckAndCommit uses a procedure CheckGuard(AltListr, g ): INTEGER that scans th, remote alternative list AltList7 looking for a matching

Towards a Compositional SPIN

NASA Technical Reports Server (NTRS)

Pasareanu, Corina S.; Giannakopoulou, Dimitra

2006-01-01

This paper discusses our initial experience with introducing automated assume-guarantee verification based on learning in the SPIN tool. We believe that compositional verification techniques such as assume-guarantee reasoning could complement the state-reduction techniques that SPIN already supports, thus increasing the size of systems that SPIN can handle. We present a "light-weight" approach to evaluating the benefits of learning-based assume-guarantee reasoning in the context of SPIN: we turn our previous implementation of learning for the LTSA tool into a main program that externally invokes SPIN to provide the model checking-related answers. Despite its performance overheads (which mandate a future implementation within SPIN itself), this approach provides accurate information about the savings in memory. We have experimented with several versions of learning-based assume guarantee reasoning, including a novel heuristic introduced here for generating component assumptions when their environment is unavailable. We illustrate the benefits of learning-based assume-guarantee reasoning in SPIN through the example of a resource arbiter for a spacecraft. Keywords: assume-guarantee reasoning, model checking, learning.

Formal Verification of Safety Properties for Aerospace Systems Through Algorithms Based on Exhaustive State-Space Exploration

NASA Technical Reports Server (NTRS)

Ciardo, Gianfranco

2004-01-01

The Runway Safety Monitor (RSM) designed by Lockheed Martin is part of NASA's effort to reduce aviation accidents. We developed a Petri net model of the RSM protocol and used the model checking functions of our tool SMART to investigate a number of safety properties in RSM. To mitigate the impact of state-space explosion, we built a highly discretized model of the system, obtained by partitioning the monitored runway zone into a grid of smaller volumes and by considering scenarios involving only two aircraft. The model also assumes that there are no communication failures, such as bad input from radar or lack of incoming data, thus it relies on a consistent view of reality by all participants. In spite of these simplifications, we were able to expose potential problems in the RSM conceptual design. Our findings were forwarded to the design engineers, who undertook corrective action. Additionally, the results stress the efficiency attained by the new model checking algorithms implemented in SMART, and demonstrate their applicability to real-world systems. Attempts to verify RSM with NuSMV and SPIN have failed due to excessive memory consumption.

Nonverbal memory and organizational dysfunctions are related with distinct symptom dimensions in obsessive-compulsive disorder.

PubMed

Jang, Joon Hwan; Kim, Hee Sun; Ha, Tae Hyon; Shin, Na Young; Kang, Do-Hyung; Choi, Jung-Seok; Ha, Kyooseob; Kwon, Jun Soo

2010-12-30

Recent acceptance that obsessive-compulsive disorder (OCD) represents a heterogeneous phenomenon has underscored the need for dimensional approaches to this disorder. However little is known about the relation between neuropsychological functions and symptom dimensions. The purpose of this study was to identify the cognitive deficits correlated with specific symptom dimensions. Thirteen categories in the Yale-Brown Obsessive Compulsive Scale symptom checklist from 144 patients with OCD were analyzed by principal component analysis. Correlations between identified symptom dimensions and neuropsychological functioning, measured by the Boston Qualitative Scoring System, were analyzed. Five factors or dimensions were identified: contamination/cleaning, hoarding, symmetry/ordering, obsessions/checking, and repeating/counting. Dysfunctions in nonverbal memory and organizational strategies were related to the symmetry/ordering dimension and the obsessions/checking dimension, respectively. The results of the present study support a transculturally stable symptom structure for OCD. They also suggest the possibility that nonverbal memory dysfunction and organizational impairment are mediated by distinct obsessive-compulsive dimensions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Virtex-5QV Self Scrubber

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

Wojahn, Christopher K.

2015-10-20

This HDL code (hereafter referred to as "software") implements circuitry in Xilinx Virtex-5QV Field Programmable Gate Array (FPGA) hardware. This software allows the device to self-check the consistency of its own configuration memory for radiation-induced errors. The software then provides the capability to correct any single-bit errors detected in the memory using the device's inherent circuitry, or reload corrupted memory frames when larger errors occur that cannot be corrected with the device's built-in error correction and detection scheme.

Wavelet-based associative memory

NASA Astrophysics Data System (ADS)

Jones, Katharine J.

2004-04-01

Faces provide important characteristics of a person"s identification. In security checks, face recognition still remains the method in continuous use despite other approaches (i.e. fingerprints, voice recognition, pupil contraction, DNA scanners). With an associative memory, the output data is recalled directly using the input data. This can be achieved with a Nonlinear Holographic Associative Memory (NHAM). This approach can also distinguish between strongly correlated images and images that are partially or totally enclosed by others. Adaptive wavelet lifting has been used for Content-Based Image Retrieval. In this paper, adaptive wavelet lifting will be applied to face recognition to achieve an associative memory.

Conditional load and store in a shared memory

DOEpatents

Blumrich, Matthias A; Ohmacht, Martin

2015-02-03

A method, system and computer program product for implementing load-reserve and store-conditional instructions in a multi-processor computing system. The computing system includes a multitude of processor units and a shared memory cache, and each of the processor units has access to the memory cache. In one embodiment, the method comprises providing the memory cache with a series of reservation registers, and storing in these registers addresses reserved in the memory cache for the processor units as a result of issuing load-reserve requests. In this embodiment, when one of the processor units makes a request to store data in the memory cache using a store-conditional request, the reservation registers are checked to determine if an address in the memory cache is reserved for that processor unit. If an address in the memory cache is reserved for that processor, the data are stored at this address.

A cache-aided multiprocessor rollback recovery scheme

NASA Technical Reports Server (NTRS)

Wu, Kun-Lung; Fuchs, W. Kent

1989-01-01

This paper demonstrates how previous uniprocessor cache-aided recovery schemes can be applied to multiprocessor architectures, for recovering from transient processor failures, utilizing private caches and a global shared memory. As with cache-aided uniprocessor recovery, the multiprocessor cache-aided recovery scheme of this paper can be easily integrated into standard bus-based snoopy cache coherence protocols. A consistent shared memory state is maintained without the necessity of global check-pointing.

Sleep Deprivation and Time-Based Prospective Memory.

PubMed

Esposito, Maria José; Occhionero, Miranda; Cicogna, PierCarla

2015-11-01

To evaluate the effect of sleep deprivation on time-based prospective memory performance, that is, realizing delayed intentions at an appropriate time in the future (e.g., to take a medicine in 30 minutes). Between-subjects experimental design. The experimental group underwent 24 h of total sleep deprivation, and the control group had a regular sleep-wake cycle. Participants were tested at 08:00. Laboratory. Fifty healthy young adults (mean age 22 ± 2.1, 31 female). 24 h of total sleep deprivation. Participants were monitored by wrist actigraphy for 3 days before the experimental session. The following cognitive tasks were administered: one time-based prospective memory task and 3 reasoning tasks as ongoing activity. Objective and subjective vigilance was assessed by the psychomotor vigilance task and a visual analog scale, respectively. To measure the time-based prospective memory task we assessed compliance and clock checking behavior (time monitoring). Sleep deprivation negatively affected time-based prospective memory compliance (P < 0.001), objective vigilance (mean RT: P < 0.001; slowest 10% RT: P < 0.001; lapses: P < 0.005), and subjective vigilance (P < 0.0001). Performance on reasoning tasks and time monitoring behavior did not differ between groups. The results highlight the potential dangerous effects of total sleep deprivation on human behavior, particularly the ability to perform an intended action after a few minutes. Sleep deprivation strongly compromises time-based prospective memory compliance but does not affect time check frequency. Sleep deprivation may impair the mechanism that allows the integration of information related to time monitoring with the prospective intention. © 2015 Associated Professional Sleep Societies, LLC.

Programmable stream prefetch with resource optimization

DOEpatents

Boyle, Peter; Christ, Norman; Gara, Alan; Mawhinney, Robert; Ohmacht, Martin; Sugavanam, Krishnan

2013-01-08

A stream prefetch engine performs data retrieval in a parallel computing system. The engine receives a load request from at least one processor. The engine evaluates whether a first memory address requested in the load request is present and valid in a table. The engine checks whether there exists valid data corresponding to the first memory address in an array if the first memory address is present and valid in the table. The engine increments a prefetching depth of a first stream that the first memory address belongs to and fetching a cache line associated with the first memory address from the at least one cache memory device if there is not yet valid data corresponding to the first memory address in the array. The engine determines whether prefetching of additional data is needed for the first stream within its prefetching depth. The engine prefetches the additional data if the prefetching is needed.

Meeting the memory challenges of brain-scale network simulation.

PubMed

Kunkel, Susanne; Potjans, Tobias C; Eppler, Jochen M; Plesser, Hans Ekkehard; Morrison, Abigail; Diesmann, Markus

2011-01-01

The development of high-performance simulation software is crucial for studying the brain connectome. Using connectome data to generate neurocomputational models requires software capable of coping with models on a variety of scales: from the microscale, investigating plasticity, and dynamics of circuits in local networks, to the macroscale, investigating the interactions between distinct brain regions. Prior to any serious dynamical investigation, the first task of network simulations is to check the consistency of data integrated in the connectome and constrain ranges for yet unknown parameters. Thanks to distributed computing techniques, it is possible today to routinely simulate local cortical networks of around 10(5) neurons with up to 10(9) synapses on clusters and multi-processor shared-memory machines. However, brain-scale networks are orders of magnitude larger than such local networks, in terms of numbers of neurons and synapses as well as in terms of computational load. Such networks have been investigated in individual studies, but the underlying simulation technologies have neither been described in sufficient detail to be reproducible nor made publicly available. Here, we discover that as the network model sizes approach the regime of meso- and macroscale simulations, memory consumption on individual compute nodes becomes a critical bottleneck. This is especially relevant on modern supercomputers such as the Blue Gene/P architecture where the available working memory per CPU core is rather limited. We develop a simple linear model to analyze the memory consumption of the constituent components of neuronal simulators as a function of network size and the number of cores used. This approach has multiple benefits. The model enables identification of key contributing components to memory saturation and prediction of the effects of potential improvements to code before any implementation takes place. As a consequence, development cycles can be shorter and less expensive. Applying the model to our freely available Neural Simulation Tool (NEST), we identify the software components dominant at different scales, and develop general strategies for reducing the memory consumption, in particular by using data structures that exploit the sparseness of the local representation of the network. We show that these adaptations enable our simulation software to scale up to the order of 10,000 processors and beyond. As memory consumption issues are likely to be relevant for any software dealing with complex connectome data on such architectures, our approach and our findings should be useful for researchers developing novel neuroinformatics solutions to the challenges posed by the connectome project.

When to use the emergency room - adult

MedlinePlus

... what you should do. Your provider or health insurance company may also offer a nurse telephone advice hotline. ... choices are. Check the website of your health insurance company. Put these telephone numbers in the memory of ...

ACS Science Data Buffer Check/Self-Tests for CS Buffer RAM and MIE RAM

NASA Astrophysics Data System (ADS)

Balzano, V.

2001-07-01

The ACS Science Buffer RAM is checked for bit flips during SAA passages. This is followed by a Control Section {CS} self-test consisting of writing/reading a specified bit pattern from each memory location in Buffer RAM and a similar test for MIE RAM. The MIE must be placed in BOOT mode for its self-test. The CS Buffer RAM self-test as well as the bit flip tests are all done with the CS in Operate.

COS Side 2 Science Data Buffer Check/Self-Tests for CS Buffer RAM and DIB RAM

NASA Astrophysics Data System (ADS)

Bacinski, John

2013-10-01

The COS Science Buffer RAM is checked for bit flips during SAA passages. This is followed by a Control Section {CS} self-test consisting of writing/reading a specified bit pattern from each memory location in Buffer RAM and a similar test for DIB RAM. The DIB must be placed in BOOT mode for its self-test. The CS Buffer RAM self-test as well as the bit flip tests are all done with the CS in Operate.

ACS Science Data Buffer Check/Self-Tests for CS Buffer RAM and MIE RAM

NASA Astrophysics Data System (ADS)

Welty, Alan

2005-07-01

The ACS Science Buffer RAM is checked for bit flips during SAA passages. Thisis followed by a Control Section {CS} self-test consisting of writing/reading a specified bit pattern from each memory location in Buffer RAM and a similar test for MIE RAM. The MIE must be placed in BOOT mode for its self-test. The CS Buffer RAM self-test as well as the bit flip tests are all done with the CS in Operate.

Monitoring Blood Sugar: The Importance of Checking Blood Sugar Levels

MedlinePlus

... more portable sizes. Other features may include memory storage and the ability to record other information like ... for ketones , chemicals that show up in the urine (pee) and blood after the body breaks down ...

Buckling analysis of SMA bonded sandwich structure – using FEM

NASA Astrophysics Data System (ADS)

Katariya, Pankaj V.; Das, Arijit; Panda, Subrata K.

2018-03-01

Thermal buckling strength of smart sandwich composite structure (bonded with shape memory alloy; SMA) examined numerically via a higher-order finite element model in association with marching technique. The excess geometrical distortion of the structure under the elevated environment modeled through Green’s strain function whereas the material nonlinearity counted with the help of marching method. The system responses are computed numerically by solving the generalized eigenvalue equations via a customized MATLAB code. The comprehensive behaviour of the current finite element solutions (minimum buckling load parameter) is established by solving the adequate number of numerical examples including the given input parameter. The current numerical model is extended further to check the influence of various structural parameter of the sandwich panel on the buckling temperature including the SMA effect and reported in details.

Crosstalk eliminating and low-density parity-check codes for photochromic dual-wavelength storage

NASA Astrophysics Data System (ADS)

Wang, Meicong; Xiong, Jianping; Jian, Jiqi; Jia, Huibo

2005-01-01

Multi-wavelength storage is an approach to increase the memory density with the problem of crosstalk to be deal with. We apply Low Density Parity Check (LDPC) codes as error-correcting codes in photochromic dual-wavelength optical storage based on the investigation of LDPC codes in optical data storage. A proper method is applied to reduce the crosstalk and simulation results show that this operation is useful to improve Bit Error Rate (BER) performance. At the same time we can conclude that LDPC codes outperform RS codes in crosstalk channel.

COS Science Data Buffer Check/Self-Tests for CS Buffer RAM and DIB RAM

NASA Astrophysics Data System (ADS)

Welty, Alan

2009-07-01

The COS Science Buffer RAM is checked for bit flips during SAA passages. This is followed by a Control Section {CS} self-test consisting of writing/reading a specified bit pattern from each memory location in Buffer RAM and a similar test for DIB RAM. The DIB must be placed in BOOT mode for its self-test. The CS Buffer RAM self-test as well as the bit flip tests are all done with the CS in Operate.Supports Activity COS-03

A Shared Memory Algorithm and Proof for the Generalized Alternative Construct in CSP (Communicating Sequential Processes)

DTIC Science & Technology

1987-06-01

shared variables. This will be discussed later. One procedure merits special attention. CheckAndCommit(m, g ,): INTEGER is called by process P, (I...denotes the local process) to check that "valid" communications can take place between P, using guard g , and Pm (m denotes the remote process). If so, P...local guard gi. By matching we mean gj contains an 1/O operation with P. By compatible we mean g , and gj do not both contain input (output) commands

Stateless and stateful implementations of faithful execution

DOEpatents

Pierson, Lyndon G; Witzke, Edward L; Tarman, Thomas D; Robertson, Perry J; Eldridge, John M; Campbell, Philip L

2014-12-16

A faithful execution system includes system memory, a target processor, and protection engine. The system memory stores a ciphertext including value fields and integrity fields. The value fields each include an encrypted executable instruction and the integrity fields each include an encrypted integrity value for determining whether a corresponding one of the value fields has been modified. The target processor executes plaintext instructions decoded from the ciphertext while the protection engine is coupled between the system memory and the target processor. The protection engine includes logic to retrieve the ciphertext from the system memory, decrypt the value fields into the plaintext instructions, perform an integrity check based on the integrity fields to determine whether any of the corresponding value fields have been modified, and provide the plaintext instructions to the target processor for execution.

Use of memory strategies among younger and older adults: Results from objective and subjective measures.

PubMed

Fabricio, Aline Teixeira; Yassuda, Mônica Sanches

2011-01-01

Memory plays a fundamental role in the identity of people and in human life, as it enables us to interpret our surroundings and make decisions. It is known that the aging process can be accompanied by cognitive decline in some memory sub systems. However, the use of memory strategies can help encoding and retrieval of new information. The aim of this study was to identify and compare, using objective and subjective measures, which recall strategies are used spontaneously by young and older adults. Twenty-six first-year college students, and thirty-three seniors enrolled at the Third Age University of the same campus, completed a visual memory test including 18 black and white pictures, memorized a short story, and completed an open question about memory strategies, a memory check list to indicate strategies used, and a memory self-efficacy scale. The Bousfield categorization measure was also calculated from the recall protocol. Young adults demonstrated better performance than the older adults on the memory tasks, and were also more confident. Both groups reported using similar strategies. Young and older adults seem to tackle memory tasks in similar ways but young adults outperform seniors.

A wavelet-based evaluation of time-varying long memory of equity markets: A paradigm in crisis

NASA Astrophysics Data System (ADS)

Tan, Pei P.; Chin, Cheong W.; Galagedera, Don U. A.

2014-09-01

This study, using wavelet-based method investigates the dynamics of long memory in the returns and volatility of equity markets. In the sample of five developed and five emerging markets we find that the daily return series from January 1988 to June 2013 may be considered as a mix of weak long memory and mean-reverting processes. In the case of volatility in the returns, there is evidence of long memory, which is stronger in emerging markets than in developed markets. We find that although the long memory parameter may vary during crisis periods (1997 Asian financial crisis, 2001 US recession and 2008 subprime crisis) the direction of change may not be consistent across all equity markets. The degree of return predictability is likely to diminish during crisis periods. Robustness of the results is checked with de-trended fluctuation analysis approach.

Eye movements provide insights into the conscious use of context in prospective memory.

PubMed

Bowden, Vanessa K; Smith, Rebekah E; Loft, Shayne

2017-07-01

Prior research examining the impact of context on prospective memory (PM) has produced mixed results. Our study aimed to determine whether providing progressive context information could increase PM accuracy and reduce costs to ongoing tasks. Seventy-two participants made ongoing true/false judgements for simple sentences while maintaining a PM intention to respond differently to four memorised words. The context condition were informed of the trial numbers where PM targets could appear, and eye-tracking recorded trial number fixation frequency. The context condition showed reduced costs during irrelevant contexts, increased costs during relevant contexts, and had better PM accuracy compared to a standard condition that was not provided with context. The context condition also made an increasing number of trial number fixations leading up to relevant contexts, indicating the conscious use of context. Furthermore, this trial number checking was beneficial to PM, with participants who checked more frequently having better PM accuracy. Copyright © 2017 Elsevier Inc. All rights reserved.

Stability analysis for stochastic BAM nonlinear neural network with delays

NASA Astrophysics Data System (ADS)

Lv, Z. W.; Shu, H. S.; Wei, G. L.

2008-02-01

In this paper, stochastic bidirectional associative memory neural networks with constant or time-varying delays is considered. Based on a Lyapunov-Krasovskii functional and the stochastic stability analysis theory, we derive several sufficient conditions in order to guarantee the global asymptotically stable in the mean square. Our investigation shows that the stochastic bidirectional associative memory neural networks are globally asymptotically stable in the mean square if there are solutions to some linear matrix inequalities(LMIs). Hence, the global asymptotic stability of the stochastic bidirectional associative memory neural networks can be easily checked by the Matlab LMI toolbox. A numerical example is given to demonstrate the usefulness of the proposed global asymptotic stability criteria.

Characterizing Effects of Nitric Oxide Sterilization on tert-Butyl Acrylate Shape Memory Polymers

NASA Astrophysics Data System (ADS)

Phillippi, Ben

As research into the potential uses of shape memory polymers (SMPs) as implantable medical devices continues to grow and expand, so does the need for an accurate and reliable sterilization mechanism. The ability of an SMP to precisely undergo a programmed shape change will define its ability to accomplish a therapeutic task. To ensure proper execution of the in vivo shape change, the sterilization process must not negatively affect the shape memory behavior of the material. To address this need, this thesis investigates the effectiveness of a benchtop nitric oxide (NOx) sterilization process and the extent to which the process affects the shape memory behavior of a well-studied tert-Butyl Acrylate (tBA) SMP. Quantifying the effects on shape memory behavior was performed using a two-tiered analysis. A two-tiered study design was used to determine if the sterilization process induced any premature shape recovery and to identify any effects that NOx has on the overall shape memory behavior of the foams. Determining the effectiveness of the NOx system--specially, whether the treated samples are more sterile/less contaminated than untreated--was also performed with a two-tiered analysis. In this case, the two-tiered analysis was employed to have a secondary check for contamination. To elaborate, all of the samples that were deemed not contaminated from the initial test were put through a second sterility test to check for contamination a second time. The results of these tests indicated the NOx system is an effective sterilization mechanism and the current protocol does not negatively impact the shape memory behavior of the tBA SMP. The samples held their compressed shape throughout the entirety of the sterilization process. Additionally, there were no observable impacts on the shape memory behavior induced by NOx. Lastly, the treated samples demonstrated lower contamination than the untreated. This thesis demonstrates the effectiveness of NOx as a laboratory scale sterilization mechanism for heat triggered shape memory polymers. The shape memory analysis indicated that the magnitude of the length changes induced by NOx is small enough that it does not make a statistically significant impact on the shape memory behavior of the foams. Additionally, there were no observable effects on the shape memory behavior induced by NOx. The results further indicated the NOx system is effective at sterilizing porous scaffolds, as none of the sterilized samples showed contamination. Testing methods proved to be effective because the initial sterility test was able to identify all of the contaminated samples and preliminary results indicated that NOx sterilization improves the sterility of the foams.

Single-trial evaluative conditioning can be moderated by instructed forgetting.

PubMed

Gast, Anne; Kattner, Florian

2016-09-01

Evaluative conditioning (EC) is a change in the valence of a conditioned stimulus (CS) due to previous pairing with an affective unconditioned stimulus (US). Several previous studies indicate that EC is related to memory of the CS-US pairs. Previous studies, however, typically cannot distinguish between the influence of CS-US knowledge during measurement and during encoding. In addition, by measuring rather than manipulating memory, they do not test the causal effect of memory on EC. The present study employed a "directed forgetting" procedure to the EC paradigm instructing participants to either forget or remember certain CS-US pairs. We found that EC effects after single learning trials were stronger for to-be-remembered than for to-be-forgotten pairs. Manipulation checks showed that the forgetting manipulation also successfully modulated memory for the target pairs and reduced both retroactive and proactive interference on memory for other pairs. Item-based analyses further demonstrated that the size of EC depended on CS-US memory. The results suggest that EC relies on available memory during measurement of the EC effect.

Playing chess unconsciously.

PubMed

Kiesel, Andrea; Kunde, Wilfried; Pohl, Carsten; Berner, Michael P; Hoffmann, Joachim

2009-01-01

Expertise in a certain stimulus domain enhances perceptual capabilities. In the present article, the authors investigate whether expertise improves perceptual processing to an extent that allows complex visual stimuli to bias behavior unconsciously. Expert chess players judged whether a target chess configuration entailed a checking configuration. These displays were preceded by masked prime configurations that either represented a checking or a nonchecking configuration. Chess experts, but not novice chess players, revealed a subliminal response priming effect, that is, faster responding when prime and target displays were congruent (both checking or both nonchecking) rather than incongruent. Priming generalized to displays that were not used as targets, ruling out simple repetition priming effects. Thus, chess experts were able to judge unconsciously presented chess configurations as checking or nonchecking. A 2nd experiment demonstrated that experts' priming does not occur for simpler but uncommon chess configurations. The authors conclude that long-term practice prompts the acquisition of visual memories of chess configurations with integrated form-location conjunctions. These perceptual chunks enable complex visual processing outside of conscious awareness.

Scopolamine impairs memory recall in Octopus vulgaris.

PubMed

Fiorito, G; Agnisola, C; d'Addio, M; Valanzano, A; Calamandrei, G

1998-09-04

The involvement of the central cholinergic system in predatory performance, and on the recall of individual and observational memory in Octopus vulgaris was studied by treating the animals with the muscarinic antagonist scopolamine (2 mg/kg). The absence of the effects of the injection of scopolamine on blood circulation was also checked. Scopolamine did not affect the ability of octopuses to prey on live crabs. However, it interfered significantly with memory recall. In fact, the ability to solve the jar problem was impaired within the first hour after injection (short-term effects) and was only partially recovered after 24 h (long-term). Moreover, both individual and observational learning of a visual discrimination were significantly reduced at the short- and long-term testing. These results support a role of the cholinergic system in the processes of memory recall of O. vulgaris.

A MATLAB/Simulink based GUI for the CERES Simulator

NASA Technical Reports Server (NTRS)

Valencia, Luis H.

1995-01-01

The Clouds and The Earth's Radiant Energy System (CERES) simulator will allow flight operational familiarity with the CERES instrument prior to launch. It will provide a CERES instrument simulation facility for NASA Langley Research Center. NASA Goddard Space Flight Center and TRW. One of the objectives of building this simulator would be for use as a testbed for functionality checking of atypical memory uploads and for anomaly investigation. For instance, instrument malfunction due to memory damage requires troubleshooting on a simulator to determine the nature of the problem and to find a solution.

Involvement of the anterior cingulate cortex in time-based prospective memory task monitoring: An EEG analysis of brain sources using Independent Component and Measure Projection Analysis

PubMed Central

Burgos, Pablo; Kilborn, Kerry; Evans, Jonathan J.

2017-01-01

Objective Time-based prospective memory (PM), remembering to do something at a particular moment in the future, is considered to depend upon self-initiated strategic monitoring, involving a retrieval mode (sustained maintenance of the intention) plus target checking (intermittent time checks). The present experiment was designed to explore what brain regions and brain activity are associated with these components of strategic monitoring in time-based PM tasks. Method 24 participants were asked to reset a clock every four minutes, while performing a foreground ongoing word categorisation task. EEG activity was recorded and data were decomposed into source-resolved activity using Independent Component Analysis. Common brain regions across participants, associated with retrieval mode and target checking, were found using Measure Projection Analysis. Results Participants decreased their performance on the ongoing task when concurrently performed with the time-based PM task, reflecting an active retrieval mode that relied on withdrawal of limited resources from the ongoing task. Brain activity, with its source in or near the anterior cingulate cortex (ACC), showed changes associated with an active retrieval mode including greater negative ERP deflections, decreased theta synchronization, and increased alpha suppression for events locked to the ongoing task while maintaining a time-based intention. Activity in the ACC was also associated with time-checks and found consistently across participants; however, we did not find an association with time perception processing per se. Conclusion The involvement of the ACC in both aspects of time-based PM monitoring may be related to different functions that have been attributed to it: strategic control of attention during the retrieval mode (distributing attentional resources between the ongoing task and the time-based task) and anticipatory/decision making processing associated with clock-checks. PMID:28863146

Single event upset vulnerability of selected 4K and 16K CMOS static RAM's

NASA Technical Reports Server (NTRS)

Kolasinski, W. A.; Koga, R.; Blake, J. B.; Brucker, G.; Pandya, P.; Petersen, E.; Price, W.

1982-01-01

Upset thresholds for bulk CMOS and CMOS/SOS RAMS were deduced after bombardment of the devices with 140 MeV Kr, 160 MeV Ar, and 33 MeV O beams in a cyclotron. The trials were performed to test prototype devices intended for space applications, to relate feature size to the critical upset charge, and to check the validity of computer simulation models. The tests were run on 4 and 1 K memory cells with 6 transistors, in either hardened or unhardened configurations. The upset cross sections were calculated to determine the critical charge for upset from the soft errors observed in the irradiated cells. Computer simulations of the critical charge were found to deviate from the experimentally observed variation of the critical charge as the square of the feature size. Modeled values of series resistors decoupling the inverter pairs of memory cells showed that above some minimum resistance value a small increase in resistance produces a large increase in the critical charge, which the experimental data showed to be of questionable validity unless the value is made dependent on the maximum allowed read-write time.

Fast maximum likelihood estimation using continuous-time neural point process models.

PubMed

Lepage, Kyle Q; MacDonald, Christopher J

2015-06-01

A recent report estimates that the number of simultaneously recorded neurons is growing exponentially. A commonly employed statistical paradigm using discrete-time point process models of neural activity involves the computation of a maximum-likelihood estimate. The time to computate this estimate, per neuron, is proportional to the number of bins in a finely spaced discretization of time. By using continuous-time models of neural activity and the optimally efficient Gaussian quadrature, memory requirements and computation times are dramatically decreased in the commonly encountered situation where the number of parameters p is much less than the number of time-bins n. In this regime, with q equal to the quadrature order, memory requirements are decreased from O(np) to O(qp), and the number of floating-point operations are decreased from O(np(2)) to O(qp(2)). Accuracy of the proposed estimates is assessed based upon physiological consideration, error bounds, and mathematical results describing the relation between numerical integration error and numerical error affecting both parameter estimates and the observed Fisher information. A check is provided which is used to adapt the order of numerical integration. The procedure is verified in simulation and for hippocampal recordings. It is found that in 95 % of hippocampal recordings a q of 60 yields numerical error negligible with respect to parameter estimate standard error. Statistical inference using the proposed methodology is a fast and convenient alternative to statistical inference performed using a discrete-time point process model of neural activity. It enables the employment of the statistical methodology available with discrete-time inference, but is faster, uses less memory, and avoids any error due to discretization.

Factors that influence the generation of autobiographical memory conjunction errors

PubMed Central

Devitt, Aleea L.; Monk-Fromont, Edwin; Schacter, Daniel L.; Addis, Donna Rose

2015-01-01

The constructive nature of memory is generally adaptive, allowing us to efficiently store, process and learn from life events, and simulate future scenarios to prepare ourselves for what may come. However, the cost of a flexibly constructive memory system is the occasional conjunction error, whereby the components of an event are authentic, but the combination of those components is false. Using a novel recombination paradigm, it was demonstrated that details from one autobiographical memory may be incorrectly incorporated into another, forming autobiographical memory conjunction errors that elude typical reality monitoring checks. The factors that contribute to the creation of these conjunction errors were examined across two experiments. Conjunction errors were more likely to occur when the corresponding details were partially rather than fully recombined, likely due to increased plausibility and ease of simulation of partially recombined scenarios. Brief periods of imagination increased conjunction error rates, in line with the imagination inflation effect. Subjective ratings suggest that this inflation is due to similarity of phenomenological experience between conjunction and authentic memories, consistent with a source monitoring perspective. Moreover, objective scoring of memory content indicates that increased perceptual detail may be particularly important for the formation of autobiographical memory conjunction errors. PMID:25611492

Statistical Anomalies of Bitflips in SRAMs to Discriminate SBUs From MCUs

NASA Astrophysics Data System (ADS)

Clemente, Juan Antonio; Franco, Francisco J.; Villa, Francesca; Baylac, Maud; Rey, Solenne; Mecha, Hortensia; Agapito, Juan A.; Puchner, Helmut; Hubert, Guillaume; Velazco, Raoul

2016-08-01

Recently, the occurrence of multiple events in static tests has been investigated by checking the statistical distribution of the difference between the addresses of the words containing bitflips. That method has been successfully applied to Field Programmable Gate Arrays (FPGAs) and the original authors indicate that it is also valid for SRAMs. This paper presents a modified methodology that is based on checking the XORed addresses with bitflips, rather than on the difference. Irradiation tests on CMOS 130 & 90 nm SRAMs with 14-MeV neutrons have been performed to validate this methodology. Results in high-altitude environments are also presented and cross-checked with theoretical predictions. In addition, this methodology has also been used to detect modifications in the organization of said memories. Theoretical predictions have been validated with actual data provided by the manufacturer.

Aerospace Ground Equipment for model 4080 sequence programmer. A standard computer terminal is adapted to provide convenient operator to device interface

NASA Technical Reports Server (NTRS)

Nissley, L. E.

1979-01-01

The Aerospace Ground Equipment (AGE) provides an interface between a human operator and a complete spaceborne sequence timing device with a memory storage program. The AGE provides a means for composing, editing, syntax checking, and storing timing device programs. The AGE is implemented with a standard Hewlett-Packard 2649A terminal system and a minimum of special hardware. The terminal's dual tape interface is used to store timing device programs and to read in special AGE operating system software. To compose a new program for the timing device the keyboard is used to fill in a form displayed on the screen.

Selectively Distracted: Divided Attention and Memory for Important Information.

PubMed

Middlebrooks, Catherine D; Kerr, Tyson; Castel, Alan D

2017-08-01

Distractions and multitasking are generally detrimental to learning and memory. Nevertheless, people often study while listening to music, sitting in noisy coffee shops, or intermittently checking their e-mail. The current experiments examined how distractions and divided attention influence one's ability to selectively remember valuable information. Participants studied lists of words that ranged in value from 1 to 10 points while completing a digit-detection task, while listening to music, or without distractions. Though participants recalled fewer words following digit detection than in the other conditions, there were no significant differences between conditions in terms of selectively remembering the most valuable words. Similar results were obtained across a variety of divided-attention tasks that stressed attention and working memory to different degrees, which suggests that people may compensate for divided-attention costs by selectively attending to the most valuable items and that factors that worsen memory do not necessarily impair the ability to selectively remember important information.

Effects of 45-day -6° head-down bed rest on the time-based prospective memory

NASA Astrophysics Data System (ADS)

Chen, SiYi; Zhou, RenLai; Xiu, LiChao; Chen, ShanGuang; Chen, XiaoPing; Tan, Cheng

2013-03-01

The research explored the effects of 45-day -6° head-down bed rest (HDBR) simulation of microgravity on the time-based prospective memory (PM) with 16 males. The time-based prospective memory task was performed on the 2nd day before HDBR, on the 11th, 20th, 32nd, and 40th days during HDBR, and on the 8th day after HDBR, and subjects' anxiety and depression feelings were recorded simultaneously using Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI). The results demonstrated that it showed decreased accuracy of PM responses and frequency of clock checks during and after bed rest; long term bed rest did not induce significant emotional changes. The deficit of prospective memory performance induced by long term HDBR may result from a lack of aerobic physical activity or changes in the prefrontal cortex, but it remains to be determined.

Enhanced recognition memory in grapheme-color synaesthesia for different categories of visual stimuli

PubMed Central

Ward, Jamie; Hovard, Peter; Jones, Alicia; Rothen, Nicolas

2013-01-01

Memory has been shown to be enhanced in grapheme-color synaesthesia, and this enhancement extends to certain visual stimuli (that don't induce synaesthesia) as well as stimuli comprised of graphemes (which do). Previous studies have used a variety of testing procedures to assess memory in synaesthesia (e.g., free recall, recognition, associative learning) making it hard to know the extent to which memory benefits are attributable to the stimulus properties themselves, the testing method, participant strategies, or some combination of these factors. In the first experiment, we use the same testing procedure (recognition memory) for a variety of stimuli (written words, non-words, scenes, and fractals) and also check which memorization strategies were used. We demonstrate that grapheme-color synaesthetes show enhanced memory across all these stimuli, but this is not found for a non-visual type of synaesthesia (lexical-gustatory). In the second experiment, the memory advantage for scenes is explored further by manipulating the properties of the old and new images (changing color, orientation, or object presence). Again, grapheme-color synaesthetes show a memory advantage for scenes across all manipulations. Although recognition memory is generally enhanced in this study, the largest effects were found for abstract visual images (fractals) and scenes for which color can be used to discriminate old/new status. PMID:24187542

Enhanced recognition memory in grapheme-color synaesthesia for different categories of visual stimuli.

PubMed

Ward, Jamie; Hovard, Peter; Jones, Alicia; Rothen, Nicolas

2013-01-01

Memory has been shown to be enhanced in grapheme-color synaesthesia, and this enhancement extends to certain visual stimuli (that don't induce synaesthesia) as well as stimuli comprised of graphemes (which do). Previous studies have used a variety of testing procedures to assess memory in synaesthesia (e.g., free recall, recognition, associative learning) making it hard to know the extent to which memory benefits are attributable to the stimulus properties themselves, the testing method, participant strategies, or some combination of these factors. In the first experiment, we use the same testing procedure (recognition memory) for a variety of stimuli (written words, non-words, scenes, and fractals) and also check which memorization strategies were used. We demonstrate that grapheme-color synaesthetes show enhanced memory across all these stimuli, but this is not found for a non-visual type of synaesthesia (lexical-gustatory). In the second experiment, the memory advantage for scenes is explored further by manipulating the properties of the old and new images (changing color, orientation, or object presence). Again, grapheme-color synaesthetes show a memory advantage for scenes across all manipulations. Although recognition memory is generally enhanced in this study, the largest effects were found for abstract visual images (fractals) and scenes for which color can be used to discriminate old/new status.

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

PubMed

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

2007-11-01

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

Addressing Dynamic Issues of Program Model Checking

NASA Technical Reports Server (NTRS)

Lerda, Flavio; Visser, Willem

2001-01-01

Model checking real programs has recently become an active research area. Programs however exhibit two characteristics that make model checking difficult: the complexity of their state and the dynamic nature of many programs. Here we address both these issues within the context of the Java PathFinder (JPF) model checker. Firstly, we will show how the state of a Java program can be encoded efficiently and how this encoding can be exploited to improve model checking. Next we show how to use symmetry reductions to alleviate some of the problems introduced by the dynamic nature of Java programs. Lastly, we show how distributed model checking of a dynamic program can be achieved, and furthermore, how dynamic partitions of the state space can improve model checking. We support all our findings with results from applying these techniques within the JPF model checker.

False memories and confabulation.

PubMed

Johnson, M K; Raye, C L

1998-04-01

Memory distortions range from the benign (thinking you mailed a check that you only thought about mailing), to the serious (confusing what you heard after a crime with what you actually saw), to the fantastic (claiming you piloted a spaceship). We review theoretical ideas and empirical evidence about the source monitoring processes underlying both true and false memories. Neuropsychological studies show that certain forms of brain damage (such as combined frontal and medial-temporal lesions) might result in profound source confusions, called confabulations. Neuroimaging techniques provide new evidence regarding more specific links between underlying brain mechanisms and the normal cognitive processes involved in evaluating memories. One hypothesis is that the right prefrontal cortex (PFC) subserves heuristic judgments based on easily assessed qualities (such as familiarity or perceptual detail) and the left PFC (or the right and left PFC together) subserves more systematic judgments requiring more careful analysis of memorial qualities or retrieval and evaluation of additional supporting or disconfirming information. Such heuristic and systematic processes can be disrupted not only by brain damage but also, for example, by hypnosis, social demands and motivational factors, suggesting caution in the methods used by `memory exploring' professions (therapists, police officers, lawyers, etc.) in order to avoid inducing false memories.

Global asymptotic stability analysis of bidirectional associative memory neural networks with time delays.

PubMed

Arik, Sabri

2005-05-01

This paper presents a sufficient condition for the existence, uniqueness and global asymptotic stability of the equilibrium point for bidirectional associative memory (BAM) neural networks with distributed time delays. The results impose constraint conditions on the network parameters of neural system independently of the delay parameter, and they are applicable to all continuous nonmonotonic neuron activation functions. It is shown that in some special cases of the results, the stability criteria can be easily checked. Some examples are also given to compare the results with the previous results derived in the literature.

Thin Rechargeable Batteries for CMOS SRAM Memory Protection

NASA Technical Reports Server (NTRS)

Crouse, Dennis N.

1993-01-01

New rechargeable battery technology is described and compared with classical primary battery back-up of SRAM PC cards. Thin solid polymer electrolyte cells with the thickness of TSOP memory components (1 mm nominal, 1.1 mm max) and capacities of 14 mAh/sq cm can replace coin cells. The SRAM PC cards with permanently installed rechargeable cells and optional electrochromic low battery voltage indicators will free the periodic PC card user from having to 'feed' their PC cards with coin cells and will allow a quick visual check of stored cards for their battery voltage status.

Block-Level Added Redundancy Explicit Authentication for Parallelized Encryption and Integrity Checking of Processor-Memory Transactions

NASA Astrophysics Data System (ADS)

Elbaz, Reouven; Torres, Lionel; Sassatelli, Gilles; Guillemin, Pierre; Bardouillet, Michel; Martinez, Albert

The bus between the System on Chip (SoC) and the external memory is one of the weakest points of computer systems: an adversary can easily probe this bus in order to read private data (data confidentiality concern) or to inject data (data integrity concern). The conventional way to protect data against such attacks and to ensure data confidentiality and integrity is to implement two dedicated engines: one performing data encryption and another data authentication. This approach, while secure, prevents parallelizability of the underlying computations. In this paper, we introduce the concept of Block-Level Added Redundancy Explicit Authentication (BL-AREA) and we describe a Parallelized Encryption and Integrity Checking Engine (PE-ICE) based on this concept. BL-AREA and PE-ICE have been designed to provide an effective solution to ensure both security services while allowing for full parallelization on processor read and write operations and optimizing the hardware resources. Compared to standard encryption which ensures only confidentiality, we show that PE-ICE additionally guarantees code and data integrity for less than 4% of run-time performance overhead.

Verifying Multi-Agent Systems via Unbounded Model Checking

NASA Technical Reports Server (NTRS)

Kacprzak, M.; Lomuscio, A.; Lasica, T.; Penczek, W.; Szreter, M.

2004-01-01

We present an approach to the problem of verification of epistemic properties in multi-agent systems by means of symbolic model checking. In particular, it is shown how to extend the technique of unbounded model checking from a purely temporal setting to a temporal-epistemic one. In order to achieve this, we base our discussion on interpreted systems semantics, a popular semantics used in multi-agent systems literature. We give details of the technique and show how it can be applied to the well known train, gate and controller problem. Keywords: model checking, unbounded model checking, multi-agent systems

Toward improved design of check dam systems: A case study in the Loess Plateau, China

NASA Astrophysics Data System (ADS)

Pal, Debasish; Galelli, Stefano; Tang, Honglei; Ran, Qihua

2018-04-01

Check dams are one of the most common strategies for controlling sediment transport in erosion prone areas, along with soil and water conservation measures. However, existing mathematical models that simulate sediment production and delivery are often unable to simulate how the storage capacity of check dams varies with time. To explicitly account for this process-and to support the design of check dam systems-we developed a modelling framework consisting of two components, namely (1) the spatially distributed Soil Erosion and Sediment Delivery Model (WaTEM/SEDEM), and (2) a network-based model of check dam storage dynamics. The two models are run sequentially, with the second model receiving the initial sediment input to check dams from WaTEM/SEDEM. The framework is first applied to Shejiagou catchment, a 4.26 km2 area located in the Loess Plateau, China, where we study the effect of the existing check dam system on sediment dynamics. Results show that the deployment of check dams altered significantly the sediment delivery ratio of the catchment. Furthermore, the network-based model reveals a large variability in the life expectancy of check dams and abrupt changes in their filling rates. The application of the framework to six alternative check dam deployment scenarios is then used to illustrate its usefulness for planning purposes, and to derive some insights on the effect of key decision variables, such as the number, size, and site location of check dams. Simulation results suggest that better performance-in terms of life expectancy and sediment delivery ratio-could have been achieved with an alternative deployment strategy.

Implementing Model-Check for Employee and Management Satisfaction

NASA Technical Reports Server (NTRS)

Jones, Corey; LaPha, Steven

2013-01-01

This presentation will discuss methods to which ModelCheck can be implemented to not only improve model quality, but also satisfy both employees and management through different sets of quality checks. This approach allows a standard set of modeling practices to be upheld throughout a company, with minimal interaction required by the end user. The presenter will demonstrate how to create multiple ModelCheck standards, preventing users from evading the system, and how it can improve the quality of drawings and models.

Symbolic LTL Compilation for Model Checking: Extended Abstract

NASA Technical Reports Server (NTRS)

Rozier, Kristin Y.; Vardi, Moshe Y.

2007-01-01

In Linear Temporal Logic (LTL) model checking, we check LTL formulas representing desired behaviors against a formal model of the system designed to exhibit these behaviors. To accomplish this task, the LTL formulas must be translated into automata [21]. We focus on LTL compilation by investigating LTL satisfiability checking via a reduction to model checking. Having shown that symbolic LTL compilation algorithms are superior to explicit automata construction algorithms for this task [16], we concentrate here on seeking a better symbolic algorithm.We present experimental data comparing algorithmic variations such as normal forms, encoding methods, and variable ordering and examine their effects on performance metrics including processing time and scalability. Safety critical systems, such as air traffic control, life support systems, hazardous environment controls, and automotive control systems, pervade our daily lives, yet testing and simulation alone cannot adequately verify their reliability [3]. Model checking is a promising approach to formal verification for safety critical systems which involves creating a formal mathematical model of the system and translating desired safety properties into a formal specification for this model. The complement of the specification is then checked against the system model. When the model does not satisfy the specification, model-checking tools accompany this negative answer with a counterexample, which points to an inconsistency between the system and the desired behaviors and aids debugging efforts.

The Birth Memories and Recall Questionnaire (BirthMARQ): development and evaluation

PubMed Central

2014-01-01

Background Childbirth is a challenging and emotive experience that is accompanied by strong positive and/or negative emotions. Memories of birth may be associated with how women cognitively process birth events postpartum and potentially their adaptation to parenthood. Characteristics of memories for birth may also be associated with postnatal psychological wellbeing. This paper reports the development and evaluation of a questionnaire to measure characteristics of memories of childbirth and to examine the relationship between memories for birth and mental health. Methods The Birth Memories and Recall Questionnaire (BirthMARQ) was developed by generating items from literature reviews and general measures of memory characteristics to cover dimensions relevant to childbirth. Fifty nine items were administered to 523 women in the first year after childbirth (M = 23.7 weeks) as part of an online study of childbirth. Validity of the final scale was checked by examining differences between women with and without probable depression and PTSD. Results Principal components analysis identified 23 items representing six aspects of memory accounting for 64% of the variance. These were: Emotional memory, Centrality of memory to identity, Coherence, Reliving, Involuntary recall, and Sensory memory. Reliability was good (M alpha = .80). Women with probable depression or PTSD reported more emotional memory, centrality of memories and involuntary recall. Women with probable depression also reported more reliving, and those with probable PTSD reported less coherence and sensory memory. Conclusion The results suggest the BirthMARQ is a coherent and valid measure of the characteristics of memory for childbirth which may be important in postnatal mood and psychopathology. While further testing of its reliability and validity is needed, it is a measure capable of becoming a valuable tool for examining memory characteristics in the important context of childbirth. PMID:24950589

The Birth Memories and Recall Questionnaire (BirthMARQ): development and evaluation.

PubMed

Foley, Suzanne; Crawley, Rosalind; Wilkie, Stephanie; Ayers, Susan

2014-06-20

Childbirth is a challenging and emotive experience that is accompanied by strong positive and/or negative emotions. Memories of birth may be associated with how women cognitively process birth events postpartum and potentially their adaptation to parenthood. Characteristics of memories for birth may also be associated with postnatal psychological wellbeing. This paper reports the development and evaluation of a questionnaire to measure characteristics of memories of childbirth and to examine the relationship between memories for birth and mental health. The Birth Memories and Recall Questionnaire (BirthMARQ) was developed by generating items from literature reviews and general measures of memory characteristics to cover dimensions relevant to childbirth. Fifty nine items were administered to 523 women in the first year after childbirth (M = 23.7 weeks) as part of an online study of childbirth. Validity of the final scale was checked by examining differences between women with and without probable depression and PTSD. Principal components analysis identified 23 items representing six aspects of memory accounting for 64% of the variance. These were: Emotional memory, Centrality of memory to identity, Coherence, Reliving, Involuntary recall, and Sensory memory. Reliability was good (M alpha = .80). Women with probable depression or PTSD reported more emotional memory, centrality of memories and involuntary recall. Women with probable depression also reported more reliving, and those with probable PTSD reported less coherence and sensory memory. The results suggest the BirthMARQ is a coherent and valid measure of the characteristics of memory for childbirth which may be important in postnatal mood and psychopathology. While further testing of its reliability and validity is needed, it is a measure capable of becoming a valuable tool for examining memory characteristics in the important context of childbirth.

Finding Feasible Abstract Counter-Examples

NASA Technical Reports Server (NTRS)

Pasareanu, Corina S.; Dwyer, Matthew B.; Visser, Willem; Clancy, Daniel (Technical Monitor)

2002-01-01

A strength of model checking is its ability to automate the detection of subtle system errors and produce traces that exhibit those errors. Given the high computational cost of model checking most researchers advocate the use of aggressive property-preserving abstractions. Unfortunately, the more aggressively a system is abstracted the more infeasible behavior it will have. Thus, while abstraction enables efficient model checking it also threatens the usefulness of model checking as a defect detection tool, since it may be difficult to determine whether a counter-example is feasible and hence worth developer time to analyze. We have explored several strategies for addressing this problem by extending an explicit-state model checker, Java PathFinder (JPF), to search for and analyze counter-examples in the presence of abstractions. We demonstrate that these techniques effectively preserve the defect detection ability of model checking in the presence of aggressive abstraction by applying them to check properties of several abstracted multi-threaded Java programs. These new capabilities are not specific to JPF and can be easily adapted to other model checking frameworks; we describe how this was done for the Bandera toolset.

12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

Code of Federal Regulations, 2014 CFR

2014-01-01

... processing regions)]. If you make the deposit in person to one of our employees, funds from the following... in different states or check processing regions)]. If you make the deposit in person to one of our...] Substitute Checks and Your Rights What Is a Substitute Check? To make check processing faster, federal law...

Increasing dimension of structures by 4D printing shape memory polymers via fused deposition modeling

NASA Astrophysics Data System (ADS)

Hu, G. F.; Damanpack, A. R.; Bodaghi, M.; Liao, W. H.

2017-12-01

The main objective of this paper is to introduce a 4D printing method to program shape memory polymers (SMPs) during fabrication process. Fused deposition modeling (FDM) as a filament-based printing method is employed to program SMPs during depositing the material. This method is implemented to fabricate complicated polymeric structures by self-bending features without need of any post-programming. Experiments are conducted to demonstrate feasibility of one-dimensional (1D)-to 2D and 2D-to-3D self-bending. It is shown that 3D printed plate structures can transform into masonry-inspired 3D curved shell structures by simply heating. Good reliability of SMP programming during printing process is also demonstrated. A 3D macroscopic constitutive model is established to simulate thermo-mechanical features of the printed SMPs. Governing equations are also derived to simulate programming mechanism during printing process and shape change of self-bending structures. In this respect, a finite element formulation is developed considering von-Kármán geometric nonlinearity and solved by implementing iterative Newton-Raphson scheme. The accuracy of the computational approach is checked with experimental results. It is demonstrated that the theoretical model is able to replicate the main characteristics observed in the experiments. This research is likely to advance the state of the art FDM 4D printing, and provide pertinent results and computational tool that are instrumental in design of smart materials and structures with self-bending features.

Neuroanatomical correlates of encoding in episodic memory: levels of processing effect.

PubMed Central

Kapur, S; Craik, F I; Tulving, E; Wilson, A A; Houle, S; Brown, G M

1994-01-01

Cognitive studies of memory processes demonstrate that memory for stimuli is a function of how they are encoded; stimuli processed semantically are better remembered than those processed in a perceptual or shallow fashion. This study investigates the neural correlates of this cognitive phenomenon. Twelve subjects performed two different cognitive tasks on a series of visually presented nouns. In one task, subjects detected the presence or absence of the letter a; in the other, subjects categorized each noun as living or nonliving. Positron emission tomography (PET) scans using 15O-labeled water were obtained during both tasks. Subjects showed substantially better recognition memory for nouns seen in the living/nonliving task, compared to nouns seen in the a-checking task. Comparison of the PET images between the two cognitive tasks revealed a significant activation in the left inferior prefrontal cortex (Brodmann's areas 45, 46, 47, and 10) in the semantic task as compared to the perceptual task. We propose that memory processes are subserved by a wide neurocognitive network and that encoding processes involve preferential activation of the structures in the left inferior prefrontal cortex. PMID:8134340

Neuroanatomical correlates of encoding in episodic memory: levels of processing effect.

PubMed

Kapur, S; Craik, F I; Tulving, E; Wilson, A A; Houle, S; Brown, G M

1994-03-15

Cognitive studies of memory processes demonstrate that memory for stimuli is a function of how they are encoded; stimuli processed semantically are better remembered than those processed in a perceptual or shallow fashion. This study investigates the neural correlates of this cognitive phenomenon. Twelve subjects performed two different cognitive tasks on a series of visually presented nouns. In one task, subjects detected the presence or absence of the letter a; in the other, subjects categorized each noun as living or nonliving. Positron emission tomography (PET) scans using 15O-labeled water were obtained during both tasks. Subjects showed substantially better recognition memory for nouns seen in the living/nonliving task, compared to nouns seen in the a-checking task. Comparison of the PET images between the two cognitive tasks revealed a significant activation in the left inferior prefrontal cortex (Brodmann's areas 45, 46, 47, and 10) in the semantic task as compared to the perceptual task. We propose that memory processes are subserved by a wide neurocognitive network and that encoding processes involve preferential activation of the structures in the left inferior prefrontal cortex.

Factors that influence the generation of autobiographical memory conjunction errors.

PubMed

Devitt, Aleea L; Monk-Fromont, Edwin; Schacter, Daniel L; Addis, Donna Rose

2016-01-01

The constructive nature of memory is generally adaptive, allowing us to efficiently store, process and learn from life events, and simulate future scenarios to prepare ourselves for what may come. However, the cost of a flexibly constructive memory system is the occasional conjunction error, whereby the components of an event are authentic, but the combination of those components is false. Using a novel recombination paradigm, it was demonstrated that details from one autobiographical memory (AM) may be incorrectly incorporated into another, forming AM conjunction errors that elude typical reality monitoring checks. The factors that contribute to the creation of these conjunction errors were examined across two experiments. Conjunction errors were more likely to occur when the corresponding details were partially rather than fully recombined, likely due to increased plausibility and ease of simulation of partially recombined scenarios. Brief periods of imagination increased conjunction error rates, in line with the imagination inflation effect. Subjective ratings suggest that this inflation is due to similarity of phenomenological experience between conjunction and authentic memories, consistent with a source monitoring perspective. Moreover, objective scoring of memory content indicates that increased perceptual detail may be particularly important for the formation of AM conjunction errors.

Kernel optimization for short-range molecular dynamics

NASA Astrophysics Data System (ADS)

Hu, Changjun; Wang, Xianmeng; Li, Jianjiang; He, Xinfu; Li, Shigang; Feng, Yangde; Yang, Shaofeng; Bai, He

2017-02-01

To optimize short-range force computations in Molecular Dynamics (MD) simulations, multi-threading and SIMD optimizations are presented in this paper. With respect to multi-threading optimization, a Partition-and-Separate-Calculation (PSC) method is designed to avoid write conflicts caused by using Newton's third law. Serial bottlenecks are eliminated with no additional memory usage. The method is implemented by using the OpenMP model. Furthermore, the PSC method is employed on Intel Xeon Phi coprocessors in both native and offload models. We also evaluate the performance of the PSC method under different thread affinities on the MIC architecture. In the SIMD execution, we explain the performance influence in the PSC method, considering the "if-clause" of the cutoff radius check. The experiment results show that our PSC method is relatively more efficient compared to some traditional methods. In double precision, our 256-bit SIMD implementation is about 3 times faster than the scalar version.

Finite-density effects in the Fredrickson-Andersen and Kob-Andersen kinetically-constrained models

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

Teomy, Eial, E-mail: eialteom@post.tau.ac.il; Shokef, Yair, E-mail: shokef@tau.ac.il

2014-08-14

We calculate the corrections to the thermodynamic limit of the critical density for jamming in the Kob-Andersen and Fredrickson-Andersen kinetically-constrained models, and find them to be finite-density corrections, and not finite-size corrections. We do this by introducing a new numerical algorithm, which requires negligible computer memory since contrary to alternative approaches, it generates at each point only the necessary data. The algorithm starts from a single unfrozen site and at each step randomly generates the neighbors of the unfrozen region and checks whether they are frozen or not. Our results correspond to systems of size greater than 10{sup 7} ×more » 10{sup 7}, much larger than any simulated before, and are consistent with the rigorous bounds on the asymptotic corrections. We also find that the average number of sites that seed a critical droplet is greater than 1.« less

Health Hazard Evaluation Report HETA 84-145-1604, Porter Memorial Hospital, Valparaiso, Indiana. [Anesthetic gases and ethylene oxide

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

Behrens, V.; Burroughs, G.E.; Crandall, M.

1985-07-01

Environmental and breathing-zone samples were analyzed for nitrous oxide, halogenated anesthetic gases, and ethylene-oxide at Porter Memorial Hospital, Valparaiso, Indiana in April, 1984. The evaluation was requested by the Indiana Occupational Safety and Health Administration to investigate the exposure of operating room personnel to anesthetic gases and central supply employees to ethylene-oxide. The authors conclude that some of the operating room personnel are overexposed to halogenated anesthetic gases and nitrous-oxide. Recommendations include performing better maintenance of the anesthesia equipment, improving the work practices of the anesthesiologists, and periodically checking the ethylene-oxide sterilizer system for leaks.

Application of conditional moment tests to model checking for generalized linear models.

PubMed

Pan, Wei

2002-06-01

Generalized linear models (GLMs) are increasingly being used in daily data analysis. However, model checking for GLMs with correlated discrete response data remains difficult. In this paper, through a case study on marginal logistic regression using a real data set, we illustrate the flexibility and effectiveness of using conditional moment tests (CMTs), along with other graphical methods, to do model checking for generalized estimation equation (GEE) analyses. Although CMTs provide an array of powerful diagnostic tests for model checking, they were originally proposed in the econometrics literature and, to our knowledge, have never been applied to GEE analyses. CMTs cover many existing tests, including the (generalized) score test for an omitted covariate, as special cases. In summary, we believe that CMTs provide a class of useful model checking tools.

Take the Reins on Model Quality with ModelCHECK and Gatekeeper

NASA Technical Reports Server (NTRS)

Jones, Corey

2012-01-01

Model quality and consistency has been an issue for us due to the diverse experience level and imaginative modeling techniques of our users. Fortunately, setting up ModelCHECK and Gatekeeper to enforce our best practices has helped greatly, but it wasn't easy. There were many challenges associated with setting up ModelCHECK and Gatekeeper including: limited documentation, restrictions within ModelCHECK, and resistance from end users. However, we consider ours a success story. In this presentation we will describe how we overcame these obstacles and present some of the details of how we configured them to work for us.

Model checking for linear temporal logic: An efficient implementation

NASA Technical Reports Server (NTRS)

Sherman, Rivi; Pnueli, Amir

1990-01-01

This report provides evidence to support the claim that model checking for linear temporal logic (LTL) is practically efficient. Two implementations of a linear temporal logic model checker is described. One is based on transforming the model checking problem into a satisfiability problem; the other checks an LTL formula for a finite model by computing the cross-product of the finite state transition graph of the program with a structure containing all possible models for the property. An experiment was done with a set of mutual exclusion algorithms and tested safety and liveness under fairness for these algorithms.

Cache directory lookup reader set encoding for partial cache line speculation support

DOEpatents

Gara, Alan; Ohmacht, Martin

2014-10-21

In a multiprocessor system, with conflict checking implemented in a directory lookup of a shared cache memory, a reader set encoding permits dynamic recordation of read accesses. The reader set encoding includes an indication of a portion of a line read, for instance by indicating boundaries of read accesses. Different encodings may apply to different types of speculative execution.

Long-Term Effects of a Parent-Based Language Intervention on Language Outcomes and Working Memory for Late-Talking Toddlers

ERIC Educational Resources Information Center

Buschmann, Anke; Multhauf, Bettina; Hasselhorn, Marcus; Pietz, Joachim

2015-01-01

A randomized control intervention study was conducted to evaluate the effects of the highly structured Heidelberg Parent-Based Language Intervention (HPLI). The outcomes of 43 children (n = 23 intervention, n = 20 control) who had been identified as late talkers during routine developmental check-ups carried out in pediatric practices at the age…

12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

Code of Federal Regulations, 2010 CFR

2010-01-01

... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy Disclosure and Notices C Appendix C to Part 229 Banks and... OF FUNDS AND COLLECTION OF CHECKS (REGULATION CC) Pt. 229, App. C Appendix C to Part 229—Model...

Evaluating the accuracy of technicians and pharmacists in checking unit dose medication cassettes.

PubMed

Ambrose, Peter J; Saya, Frank G; Lovett, Larry T; Tan, Sandy; Adams, Dale W; Shane, Rita

2002-06-15

The accuracy rates of board-registered pharmacy technicians and pharmacists in checking unit dose medication cassettes in the inpatient setting at two separate institutions were examined. Cedars-Sinai Medical Center and Long Beach Memorial Medical Center, both in Los Angeles county, petitioned the California State Board of Pharmacy to approve a waiver of the California Code of Regulations to conduct an experimental program to compare the accuracy of unit dose medication cassettes checked by pharmacists with that of cassettes checked by trained, certified pharmacy technicians. The study consisted of three parts: assessing pharmacist baseline checking accuracy (Phase I), developing a technician-training program and certifying technicians who completed the didactic and practical training (Phase II), and evaluating the accuracy of certified technicians checking unit dose medication cassettes as a daily function (Phase III). Twenty-nine pharmacists and 41 technicians (3 of whom were pharmacy interns) participated in the study. Of the technicians, all 41 successfully completed the didactic and practical training, 39 successfully completed the audits and became certified checkers, and 2 (including 1 of the interns) did not complete the certification audits because they were reassigned to another work area or had resigned. In Phase II, the observed accuracy rate and its lower confidence limit exceeded the predetermined minimum requirement of 99.8% for a certified checker. The mean accuracy rates for technicians were identical at the two institutions (p = 1.0). The difference in mean accuracy rates between pharmacists (99.52%; 95% confidence interval [CI] 99.44-99.58%) and technicians, (99.89%; 95% CI 99.87-99.90%) was significant (p < 0.0001). Inpatient technicians who had been trained and certified in a closely supervised program that incorporated quality assurance mechanisms could safely and accurately check unit dose medication cassettes filled by other technicians.

Certifying Domain-Specific Policies

NASA Technical Reports Server (NTRS)

Lowry, Michael; Pressburger, Thomas; Rosu, Grigore; Koga, Dennis (Technical Monitor)

2001-01-01

Proof-checking code for compliance to safety policies potentially enables a product-oriented approach to certain aspects of software certification. To date, previous research has focused on generic, low-level programming-language properties such as memory type safety. In this paper we consider proof-checking higher-level domain -specific properties for compliance to safety policies. The paper first describes a framework related to abstract interpretation in which compliance to a class of certification policies can be efficiently calculated Membership equational logic is shown to provide a rich logic for carrying out such calculations, including partiality, for certification. The architecture for a domain-specific certifier is described, followed by an implemented case study. The case study considers consistency of abstract variable attributes in code that performs geometric calculations in Aerospace systems.

The influence of social anxiety on the body checking behaviors of female college students.

PubMed

White, Emily K; Warren, Cortney S

2014-09-01

Social anxiety and eating pathology frequently co-occur. However, there is limited research examining the relationship between anxiety and body checking, aside from one study in which social physique anxiety partially mediated the relationship between body checking cognitions and body checking behavior (Haase, Mountford, & Waller, 2007). In an independent sample of 567 college women, we tested the fit of Haase and colleagues' foundational model but did not find evidence of mediation. Thus we tested the fit of an expanded path model that included eating pathology and clinical impairment. In the best-fitting path model (CFI=.991; RMSEA=.083) eating pathology and social physique anxiety positively predicted body checking, and body checking positively predicted clinical impairment. Therefore, women who endorse social physique anxiety may be more likely to engage in body checking behaviors and experience impaired psychosocial functioning. Published by Elsevier Ltd.

Heap/stack guard pages using a wakeup unit

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

Gooding, Thomas M; Satterfield, David L; Steinmacher-Burow, Burkhard

A method and system for providing a memory access check on a processor including the steps of detecting accesses to a memory device including level-1 cache using a wakeup unit. The method includes invalidating level-1 cache ranges corresponding to a guard page, and configuring a plurality of wakeup address compare (WAC) registers to allow access to selected WAC registers. The method selects one of the plurality of WAC registers, and sets up a WAC register related to the guard page. The method configures the wakeup unit to interrupt on access of the selected WAC register. The method detects access ofmore » the memory device using the wakeup unit when a guard page is violated. The method generates an interrupt to the core using the wakeup unit, and determines the source of the interrupt. The method detects the activated WAC registers assigned to the violated guard page, and initiates a response.« less

Entanglement distillation for quantum communication network with atomic-ensemble memories.

PubMed

Li, Tao; Yang, Guo-Jian; Deng, Fu-Guo

2014-10-06

Atomic ensembles are effective memory nodes for quantum communication network due to the long coherence time and the collective enhancement effect for the nonlinear interaction between an ensemble and a photon. Here we investigate the possibility of achieving the entanglement distillation for nonlocal atomic ensembles by the input-output process of a single photon as a result of cavity quantum electrodynamics. We give an optimal entanglement concentration protocol (ECP) for two-atomic-ensemble systems in a partially entangled pure state with known parameters and an efficient ECP for the systems in an unknown partially entangled pure state with a nondestructive parity-check detector (PCD). For the systems in a mixed entangled state, we introduce an entanglement purification protocol with PCDs. These entanglement distillation protocols have high fidelity and efficiency with current experimental techniques, and they are useful for quantum communication network with atomic-ensemble memories.

12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

Code of Federal Regulations, 2012 CFR

2012-01-01

... in different states or check processing regions)]. If you make the deposit in person to one of our... processing regions)]. If you make the deposit in person to one of our employees, funds from the following... Your Rights What Is a Substitute Check? To make check processing faster, federal law permits banks to...

12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

Code of Federal Regulations, 2011 CFR

2011-01-01

... in different states or check processing regions)]. If you make the deposit in person to one of our... processing regions)]. If you make the deposit in person to one of our employees, funds from the following... Your Rights What Is a Substitute Check? To make check processing faster, federal law permits banks to...

12 CFR Appendix C to Part 229 - Model Availability Policy Disclosures, Clauses, and Notices; Model Substitute Check Policy...

Code of Federal Regulations, 2013 CFR

2013-01-01

... in different states or check processing regions)]. If you make the deposit in person to one of our... processing regions)]. If you make the deposit in person to one of our employees, funds from the following... Your Rights What Is a Substitute Check? To make check processing faster, federal law permits banks to...

Determination of MLC model parameters for Monaco using commercial diode arrays.

PubMed

Kinsella, Paul; Shields, Laura; McCavana, Patrick; McClean, Brendan; Langan, Brian

2016-07-08

Multileaf collimators (MLCs) need to be characterized accurately in treatment planning systems to facilitate accurate intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). The aim of this study was to examine the use of MapCHECK 2 and ArcCHECK diode arrays for optimizing MLC parameters in Monaco X-ray voxel Monte Carlo (XVMC) dose calculation algorithm. A series of radiation test beams designed to evaluate MLC model parameters were delivered to MapCHECK 2, ArcCHECK, and EBT3 Gafchromic film for comparison. Initial comparison of the calculated and ArcCHECK-measured dose distributions revealed it was unclear how to change the MLC parameters to gain agreement. This ambiguity arose due to an insufficient sampling of the test field dose distributions and unexpected discrepancies in the open parts of some test fields. Consequently, the XVMC MLC parameters were optimized based on MapCHECK 2 measurements. Gafchromic EBT3 film was used to verify the accuracy of MapCHECK 2 measured dose distributions. It was found that adjustment of the MLC parameters from their default values resulted in improved global gamma analysis pass rates for MapCHECK 2 measurements versus calculated dose. The lowest pass rate of any MLC-modulated test beam improved from 68.5% to 93.5% with 3% and 2 mm gamma criteria. Given the close agreement of the optimized model to both MapCHECK 2 and film, the optimized model was used as a benchmark to highlight the relatively large discrepancies in some of the test field dose distributions found with ArcCHECK. Comparison between the optimized model-calculated dose and ArcCHECK-measured dose resulted in global gamma pass rates which ranged from 70.0%-97.9% for gamma criteria of 3% and 2 mm. The simple square fields yielded high pass rates. The lower gamma pass rates were attributed to the ArcCHECK overestimating the dose in-field for the rectangular test fields whose long axis was parallel to the long axis of the ArcCHECK. Considering ArcCHECK measurement issues and the lower gamma pass rates for the MLC-modulated test beams, it was concluded that MapCHECK 2 was a more suitable detector than ArcCHECK for the optimization process. © 2016 The Authors

Propel: Tools and Methods for Practical Source Code Model Checking

NASA Technical Reports Server (NTRS)

Mansouri-Samani, Massoud; Mehlitz, Peter; Markosian, Lawrence; OMalley, Owen; Martin, Dale; Moore, Lantz; Penix, John; Visser, Willem

2003-01-01

The work reported here is an overview and snapshot of a project to develop practical model checking tools for in-the-loop verification of NASA s mission-critical, multithreaded programs in Java and C++. Our strategy is to develop and evaluate both a design concept that enables the application of model checking technology to C++ and Java, and a model checking toolset for C++ and Java. The design concept and the associated model checking toolset is called Propel. It builds upon the Java PathFinder (JPF) tool, an explicit state model checker for Java applications developed by the Automated Software Engineering group at NASA Ames Research Center. The design concept that we are developing is Design for Verification (D4V). This is an adaption of existing best design practices that has the desired side-effect of enhancing verifiability by improving modularity and decreasing accidental complexity. D4V, we believe, enhances the applicability of a variety of V&V approaches; we are developing the concept in the context of model checking. The model checking toolset, Propel, is based on extending JPF to handle C++. Our principal tasks in developing the toolset are to build a translator from C++ to Java, productize JPF, and evaluate the toolset in the context of D4V. Through all these tasks we are testing Propel capabilities on customer applications.

Study of memory effects in international market indices

NASA Astrophysics Data System (ADS)

Mariani, M. C.; Florescu, I.; Beccar Varela, M. P.; Ncheuguim, E.

2010-04-01

Long term memory effects in stock market indices that represent internationally diversified stocks are analyzed in this paper and the results are compared with the S&P 500 index. The Hurst exponent and the Detrended fluctuation analysis (DFA) technique are the tools used for this analysis. The financial time-series data of these indices are tested with the Normalized Truncated Levy Flight to check whether the evolution of these indices is explained by the TLF. Some features that seem to be specific for international indices are discovered and briefly discussed. In particular, a potential investor seems to be faced with new investment opportunities in emerging markets during and especially after a crisis.

KSC-05PD-0562

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. In the Vehicle Assembly Building at NASAs Kennedy Space Center, workers check the digital still camera they will mount in the External Tank (ET) umbilical well on the aft end of Space Shuttle Discovery. The camera is being used to obtain and downlink high-resolution images of the disconnect point on the ET following the tank's separation from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

Authenticating cache

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

Smith, Tyler Barratt; Urrea, Jorge Mario

2012-06-01

The aim of the Authenticating Cache architecture is to ensure that machine instructions in a Read Only Memory (ROM) are legitimate from the time the ROM image is signed (immediately after compilation) to the time they are placed in the cache for the processor to consume. The proposed architecture allows the detection of ROM image modifications during distribution or when it is loaded into memory. It also ensures that modified instructions will not execute in the processor-as the cache will not be loaded with a page that fails an integrity check. The authenticity of the instruction stream can also bemore » verified in this architecture. The combination of integrity and authenticity assurance greatly improves the security profile of a system.« less

Does neuropsychological performance in OCD relate to different symptoms? A meta-analysis comparing the symmetry and obsessing dimensions.

PubMed

Bragdon, Laura B; Gibb, Brandon E; Coles, Meredith E

2018-06-19

Investigations of neuropsychological functioning in obsessive-compulsive disorder (OCD) have produced mixed results for deficits in executive functioning (EF), attention, and memory. One potential explanation for varied findings may relate to the heterogeneity of symptom presentations, and different clinical or neurobiological characteristics may underlie these different symptoms. We investigated differences in neuropsychological functioning between two symptoms groups, obsessing/checking (O/C) and symmetry/ordering (S/O), based on data suggesting an association with different motivations: harm avoidance and incompleteness, respectively. Ten studies (with 628 patients) were included and each investigation assessed at least one of 14 neuropsychological domains. The S/O domain demonstrated small, negative correlations with overall neuropsychological functioning, performance in EF, memory, visuospatial ability, cognitive flexibility, and verbal working memory. O/C symptoms demonstrated small, negative correlations with memory and verbal memory performance. A comparison of functioning between symptom groups identified large effect sizes showing that the S/O dimension was more strongly related to poorer neuropsychological performance overall, and in the domains of attention, visuospatial ability, and the subdomain of verbal working memory. Findings support existing evidence suggesting that different OCD symptoms, and their associated core motivations, relate to unique patterns of neuropsychological functioning, and, potentially dysfunction in different neural circuits. © 2018 Wiley Periodicals, Inc.

Self-Referential Tags in the Discourse of People with Alzheimer's Disease

ERIC Educational Resources Information Center

Asp, Elissa; Song, Xiaowei; Rockwood, Kenneth

2006-01-01

In a study of the discourse of 100 people with Alzheimer's disease treated for 12 months with donepezil, we observed that, as a group, they used a form of tag, described here as a self-referential tag (SRT), 14 times more frequently than did caregivers. Patients use SRTs to check propositions dependent on episodic memory as in I haven't seen the…

An Assessment of Modafinil for Vestibular and Aviation-Related Effects

DTIC Science & Technology

2005-10-01

Charlton and Cory Welch for editing and checking references; Ms. Anne Marie Michel for sheparding the urine through the analysis process . Lastly we wish to...superior performance during the sleep deprivation on the following tasks: reaction time task, mathematical processing , memory search, spatial... processing , unstable tracking, and grammatical reasoning. Baranski, Cian, Esquivie, Pigeau, and Raphel (1998) administered a cognitive test battery during a

Program Model Checking as a New Trend

NASA Technical Reports Server (NTRS)

Havelund, Klaus; Visser, Willem; Clancy, Daniel (Technical Monitor)

2002-01-01

This paper introduces a special section of STTT (International Journal on Software Tools for Technology Transfer) containing a selection of papers that were presented at the 7th International SPIN workshop, Stanford, August 30 - September 1, 2000. The workshop was named SPIN Model Checking and Software Verification, with an emphasis on model checking of programs. The paper outlines the motivation for stressing software verification, rather than only design and model verification, by presenting the work done in the Automated Software Engineering group at NASA Ames Research Center within the last 5 years. This includes work in software model checking, testing like technologies and static analysis.

UTP and Temporal Logic Model Checking

NASA Astrophysics Data System (ADS)

Anderson, Hugh; Ciobanu, Gabriel; Freitas, Leo

In this paper we give an additional perspective to the formal verification of programs through temporal logic model checking, which uses Hoare and He Unifying Theories of Programming (UTP). Our perspective emphasizes the use of UTP designs, an alphabetised relational calculus expressed as a pre/post condition pair of relations, to verify state or temporal assertions about programs. The temporal model checking relation is derived from a satisfaction relation between the model and its properties. The contribution of this paper is that it shows a UTP perspective to temporal logic model checking. The approach includes the notion of efficiency found in traditional model checkers, which reduced a state explosion problem through the use of efficient data structures

75 FR 28480 - Airworthiness Directives; Airbus Model A300 Series Airplanes; Model A300 B4-600, B4-600R, F4-600R...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

... pressurise the hydraulic reservoirs, due to leakage of the Crissair reservoir air pressurisation check valves. * * * The leakage of the check valves was caused by an incorrect spring material. The affected Crissair check valves * * * were then replaced with improved check valves P/N [part number] 2S2794-1 * * *. More...

Assessment of check-dam groundwater recharge with water-balance calculations

NASA Astrophysics Data System (ADS)

Djuma, Hakan; Bruggeman, Adriana; Camera, Corrado; Eliades, Marinos

2017-04-01

Studies on the enhancement of groundwater recharge by check-dams in arid and semi-arid environments mainly focus on deriving water infiltration rates from the check-dam ponding areas. This is usually achieved by applying simple water balance models, more advanced models (e.g., two dimensional groundwater models) and field tests (e.g., infiltrometer test or soil pit tests). Recharge behind the check-dam can be affected by the built-up of sediment as a result of erosion in the upstream watershed area. This natural process can increase the uncertainty in the estimates of the recharged water volume, especially for water balance calculations. Few water balance field studies of individual check-dams have been presented in the literature and none of them presented associated uncertainties of their estimates. The objectives of this study are i) to assess the effect of a check-dam on groundwater recharge from an ephemeral river; and ii) to assess annual sedimentation at the check-dam during a 4-year period. The study was conducted on a check-dam in the semi-arid island of Cyprus. Field campaigns were carried out to measure water flow, water depth and check-dam topography in order to establish check-dam water height, volume, evaporation, outflow and recharge relations. Topographic surveys were repeated at the end of consecutive hydrological years to estimate the sediment built up in the reservoir area of the check dam. Also, sediment samples were collected from the check-dam reservoir area for bulk-density analyses. To quantify the groundwater recharge, a water balance model was applied at two locations: at the check-dam and corresponding reservoir area, and at a 4-km stretch of the river bed without check-dam. Results showed that a check-dam with a storage capacity of 25,000 m3 was able to recharge to the aquifer, in four years, a total of 12 million m3 out of the 42 million m3 of measured (or modelled) streamflow. Recharge from the analyzed 4-km long river section without check-dam was estimated to be 1 million m3. Upper and lower limits of prediction intervals were computed to assess the uncertainties of the results. The model was rerun with these values and resulted in recharge values of 0.4 m3 as lower and 38 million m3 as upper limit. The sediment survey in the check-dam reservoir area showed that the reservoir area was filled with 2,000 to 3,000 tons of sediment after one rainfall season. This amount of sediment corresponds to 0.2 to 2 t h-1 y-1 sediment yield at the watershed level and reduces the check-dam storage capacity by approximately 10%. Results indicate that check-dams are valuable structures for increasing groundwater resources, but special attention should be given to soil erosion occurring in the upstream area and the resulting sediment built-up in the check-dam reservoir area. This study has received funding from the EU FP7 RECARE Project (GA 603498)

Efficient model checking of network authentication protocol based on SPIN

NASA Astrophysics Data System (ADS)

Tan, Zhi-hua; Zhang, Da-fang; Miao, Li; Zhao, Dan

2013-03-01

Model checking is a very useful technique for verifying the network authentication protocols. In order to improve the efficiency of modeling and verification on the protocols with the model checking technology, this paper first proposes a universal formalization description method of the protocol. Combined with the model checker SPIN, the method can expediently verify the properties of the protocol. By some modeling simplified strategies, this paper can model several protocols efficiently, and reduce the states space of the model. Compared with the previous literature, this paper achieves higher degree of automation, and better efficiency of verification. Finally based on the method described in the paper, we model and verify the Privacy and Key Management (PKM) authentication protocol. The experimental results show that the method of model checking is effective, which is useful for the other authentication protocols.

How "implicit" are implicit color effects in memory?

PubMed

Zimmer, Hubert D; Steiner, Astrid; Ecker, Ullrich K H

2002-01-01

Processing colored pictures of objects results in a preference to choose the former color for a specific object in a subsequent color choice test (Wippich & Mecklenbräuker, 1998). We tested whether this implicit memory effect is independent of performances in episodic color recollection (recognition). In the study phase of Experiment 1, the color of line drawings was either named or its appropriateness was judged. We found only weak implicit memory effects for categorical color information. In Experiment 2, silhouettes were colored by subjects during the study phase. Performances in both the implicit and the explicit test were good. Selections of "old" colors in the implicit test, though, were almost completely confined to items for which the color was also remembered explicitly. In Experiment 3, we applied the opposition technique in order to check whether we could find any implicit effects regarding items for which no explicit color recollection was possible. This was not the case. We therefore draw the conclusion that implicit color preference effects are not independent of explicit recollection, and that they are probably based on the same episodic memory traces that are used in explicit tests.

An Integrated Environment for Efficient Formal Design and Verification

NASA Technical Reports Server (NTRS)

1998-01-01

The general goal of this project was to improve the practicality of formal methods by combining techniques from model checking and theorem proving. At the time the project was proposed, the model checking and theorem proving communities were applying different tools to similar problems, but there was not much cross-fertilization. This project involved a group from SRI that had substantial experience in the development and application of theorem-proving technology, and a group at Stanford that specialized in model checking techniques. Now, over five years after the proposal was submitted, there are many research groups working on combining theorem-proving and model checking techniques, and much more communication between the model checking and theorem proving research communities. This project contributed significantly to this research trend. The research work under this project covered a variety of topics: new theory and algorithms; prototype tools; verification methodology; and applications to problems in particular domains.

A voice-actuated wind tunnel model leak checking system

NASA Technical Reports Server (NTRS)

Larson, William E.

1989-01-01

A computer program has been developed that improves the efficiency of wind tunnel model leak checking. The program uses a voice recognition unit to relay a technician's commands to the computer. The computer, after receiving a command, can respond to the technician via a voice response unit. Information about the model pressure orifice being checked is displayed on a gas-plasma terminal. On command, the program records up to 30 seconds of pressure data. After the recording is complete, the raw data and a straight line fit of the data are plotted on the terminal. This allows the technician to make a decision on the integrity of the orifice being checked. All results of the leak check program are stored in a database file that can be listed on the line printer for record keeping purposes or displayed on the terminal to help the technician find unchecked orifices. This program allows one technician to check a model for leaks instead of the two or three previously required.

Use of posterior predictive checks as an inferential tool for investigating individual heterogeneity in animal population vital rates

PubMed Central

Chambert, Thierry; Rotella, Jay J; Higgs, Megan D

2014-01-01

The investigation of individual heterogeneity in vital rates has recently received growing attention among population ecologists. Individual heterogeneity in wild animal populations has been accounted for and quantified by including individually varying effects in models for mark–recapture data, but the real need for underlying individual effects to account for observed levels of individual variation has recently been questioned by the work of Tuljapurkar et al. (Ecology Letters, 12, 93, 2009) on dynamic heterogeneity. Model-selection approaches based on information criteria or Bayes factors have been used to address this question. Here, we suggest that, in addition to model-selection, model-checking methods can provide additional important insights to tackle this issue, as they allow one to evaluate a model's misfit in terms of ecologically meaningful measures. Specifically, we propose the use of posterior predictive checks to explicitly assess discrepancies between a model and the data, and we explain how to incorporate model checking into the inferential process used to assess the practical implications of ignoring individual heterogeneity. Posterior predictive checking is a straightforward and flexible approach for performing model checks in a Bayesian framework that is based on comparisons of observed data to model-generated replications of the data, where parameter uncertainty is incorporated through use of the posterior distribution. If discrepancy measures are chosen carefully and are relevant to the scientific context, posterior predictive checks can provide important information allowing for more efficient model refinement. We illustrate this approach using analyses of vital rates with long-term mark–recapture data for Weddell seals and emphasize its utility for identifying shortfalls or successes of a model at representing a biological process or pattern of interest. We show how posterior predictive checks can be used to strengthen inferences in ecological studies. We demonstrate the application of this method on analyses dealing with the question of individual reproductive heterogeneity in a population of Antarctic pinnipeds. PMID:24834335

A Novel Method to Verify Multilevel Computational Models of Biological Systems Using Multiscale Spatio-Temporal Meta Model Checking

PubMed Central

Gilbert, David

2016-01-01

Insights gained from multilevel computational models of biological systems can be translated into real-life applications only if the model correctness has been verified first. One of the most frequently employed in silico techniques for computational model verification is model checking. Traditional model checking approaches only consider the evolution of numeric values, such as concentrations, over time and are appropriate for computational models of small scale systems (e.g. intracellular networks). However for gaining a systems level understanding of how biological organisms function it is essential to consider more complex large scale biological systems (e.g. organs). Verifying computational models of such systems requires capturing both how numeric values and properties of (emergent) spatial structures (e.g. area of multicellular population) change over time and across multiple levels of organization, which are not considered by existing model checking approaches. To address this limitation we have developed a novel approximate probabilistic multiscale spatio-temporal meta model checking methodology for verifying multilevel computational models relative to specifications describing the desired/expected system behaviour. The methodology is generic and supports computational models encoded using various high-level modelling formalisms because it is defined relative to time series data and not the models used to generate it. In addition, the methodology can be automatically adapted to case study specific types of spatial structures and properties using the spatio-temporal meta model checking concept. To automate the computational model verification process we have implemented the model checking approach in the software tool Mule (http://mule.modelchecking.org). Its applicability is illustrated against four systems biology computational models previously published in the literature encoding the rat cardiovascular system dynamics, the uterine contractions of labour, the Xenopus laevis cell cycle and the acute inflammation of the gut and lung. Our methodology and software will enable computational biologists to efficiently develop reliable multilevel computational models of biological systems. PMID:27187178

A Novel Method to Verify Multilevel Computational Models of Biological Systems Using Multiscale Spatio-Temporal Meta Model Checking.

PubMed

Pârvu, Ovidiu; Gilbert, David

2016-01-01

Insights gained from multilevel computational models of biological systems can be translated into real-life applications only if the model correctness has been verified first. One of the most frequently employed in silico techniques for computational model verification is model checking. Traditional model checking approaches only consider the evolution of numeric values, such as concentrations, over time and are appropriate for computational models of small scale systems (e.g. intracellular networks). However for gaining a systems level understanding of how biological organisms function it is essential to consider more complex large scale biological systems (e.g. organs). Verifying computational models of such systems requires capturing both how numeric values and properties of (emergent) spatial structures (e.g. area of multicellular population) change over time and across multiple levels of organization, which are not considered by existing model checking approaches. To address this limitation we have developed a novel approximate probabilistic multiscale spatio-temporal meta model checking methodology for verifying multilevel computational models relative to specifications describing the desired/expected system behaviour. The methodology is generic and supports computational models encoded using various high-level modelling formalisms because it is defined relative to time series data and not the models used to generate it. In addition, the methodology can be automatically adapted to case study specific types of spatial structures and properties using the spatio-temporal meta model checking concept. To automate the computational model verification process we have implemented the model checking approach in the software tool Mule (http://mule.modelchecking.org). Its applicability is illustrated against four systems biology computational models previously published in the literature encoding the rat cardiovascular system dynamics, the uterine contractions of labour, the Xenopus laevis cell cycle and the acute inflammation of the gut and lung. Our methodology and software will enable computational biologists to efficiently develop reliable multilevel computational models of biological systems.

Model Checking Temporal Logic Formulas Using Sticker Automata

PubMed Central

Feng, Changwei; Wu, Huanmei

2017-01-01

As an important complex problem, the temporal logic model checking problem is still far from being fully resolved under the circumstance of DNA computing, especially Computation Tree Logic (CTL), Interval Temporal Logic (ITL), and Projection Temporal Logic (PTL), because there is still a lack of approaches for DNA model checking. To address this challenge, a model checking method is proposed for checking the basic formulas in the above three temporal logic types with DNA molecules. First, one-type single-stranded DNA molecules are employed to encode the Finite State Automaton (FSA) model of the given basic formula so that a sticker automaton is obtained. On the other hand, other single-stranded DNA molecules are employed to encode the given system model so that the input strings of the sticker automaton are obtained. Next, a series of biochemical reactions are conducted between the above two types of single-stranded DNA molecules. It can then be decided whether the system satisfies the formula or not. As a result, we have developed a DNA-based approach for checking all the basic formulas of CTL, ITL, and PTL. The simulated results demonstrate the effectiveness of the new method. PMID:29119114

Foundations of the Bandera Abstraction Tools

NASA Technical Reports Server (NTRS)

Hatcliff, John; Dwyer, Matthew B.; Pasareanu, Corina S.; Robby

2003-01-01

Current research is demonstrating that model-checking and other forms of automated finite-state verification can be effective for checking properties of software systems. Due to the exponential costs associated with model-checking, multiple forms of abstraction are often necessary to obtain system models that are tractable for automated checking. The Bandera Tool Set provides multiple forms of automated support for compiling concurrent Java software systems to models that can be supplied to several different model-checking tools. In this paper, we describe the foundations of Bandera's data abstraction mechanism which is used to reduce the cardinality (and the program's state-space) of data domains in software to be model-checked. From a technical standpoint, the form of data abstraction used in Bandera is simple, and it is based on classical presentations of abstract interpretation. We describe the mechanisms that Bandera provides for declaring abstractions, for attaching abstractions to programs, and for generating abstracted programs and properties. The contributions of this work are the design and implementation of various forms of tool support required for effective application of data abstraction to software components written in a programming language like Java which has a rich set of linguistic features.

Full implementation of a distributed hydrological model based on check dam trapped sediment volumes

NASA Astrophysics Data System (ADS)

Bussi, Gianbattista; Francés, Félix

2014-05-01

Lack of hydrometeorological data is one of the most compelling limitations to the implementation of distributed environmental models. Mediterranean catchments, in particular, are characterised by high spatial variability of meteorological phenomena and soil characteristics, which may prevents from transferring model calibrations from a fully gauged catchment to a totally o partially ungauged one. For this reason, new sources of data are required in order to extend the use of distributed models to non-monitored or low-monitored areas. An important source of information regarding the hydrological and sediment cycle is represented by sediment deposits accumulated at the bottom of reservoirs. Since the 60s, reservoir sedimentation volumes were used as proxy data for the estimation of inter-annual total sediment yield rates, or, in more recent years, as a reference measure of the sediment transport for sediment model calibration and validation. Nevertheless, the possibility of using such data for constraining the calibration of a hydrological model has not been exhaustively investigated so far. In this study, the use of nine check dam reservoir sedimentation volumes for hydrological and sedimentological model calibration and spatio-temporal validation was examined. Check dams are common structures in Mediterranean areas, and are a potential source of spatially distributed information regarding both hydrological and sediment cycle. In this case-study, the TETIS hydrological and sediment model was implemented in a medium-size Mediterranean catchment (Rambla del Poyo, Spain) by taking advantage of sediment deposits accumulated behind the check dams located in the catchment headwaters. Reservoir trap efficiency was taken into account by coupling the TETIS model with a pond trap efficiency model. The model was calibrated by adjusting some of its parameters in order to reproduce the total sediment volume accumulated behind a check dam. Then, the model was spatially validated by obtaining the simulated sedimentation volume at the other eight check dams and comparing it to the observed sedimentation volumes. Lastly, the simulated water discharge at the catchment outlet was compared with observed water discharge records in order to check the hydrological sub-model behaviour. Model results provided highly valuable information concerning the spatial distribution of soil erosion and sediment transport. Spatial validation of the sediment sub-model provided very good results at seven check dams out of nine. This study shows that check dams can be a useful tool also for constraining hydrological model calibration, as model results agree with water discharge observations. In fact, the hydrological model validation at a downstream water flow gauge obtained a Nash-Sutcliffe efficiency of 0.8. This technique is applicable to all catchments with presence of check dams, and only requires rainfall and temperature data and soil characteristics maps.

Robust stability for stochastic bidirectional associative memory neural networks with time delays

NASA Astrophysics Data System (ADS)

Shu, H. S.; Lv, Z. W.; Wei, G. L.

2008-02-01

In this paper, the asymptotic stability is considered for a class of uncertain stochastic bidirectional associative memory neural networks with time delays and parameter uncertainties. The delays are time-invariant and the uncertainties are norm-bounded that enter into all network parameters. The aim of this paper is to establish easily verifiable conditions under which the delayed neural network is robustly asymptotically stable in the mean square for all admissible parameter uncertainties. By employing a Lyapunov-Krasovskii functional and conducting the stochastic analysis, a linear matrix inequality matrix inequality (LMI) approach is developed to derive the stability criteria. The proposed criteria can be easily checked by the Matlab LMI toolbox. A numerical example is given to demonstrate the usefulness of the proposed criteria.

Interactive communication channel

NASA Astrophysics Data System (ADS)

Chan, R. H.; Mann, M. R.; Ciarrocchi, J. A.

1985-10-01

Discussed is an interactive communications channel (ICC) for providing a digital computer with high-performance multi-channel interfaces. Sixteen full duplex channels can be serviced in the ICC with the sequence or scan pattern being programmable and dependent upon the number or channels and their speed. A channel buffer system is used for line interface, and character exchange. The channel buffer system is on a byte basis. The ICC performs frame start and frame end functions, bit stripping and bit stuffing. Data is stored in a memory in block format (256 bytes maximum) by a program control and the ICC maintains byte address information and a block byte count. Data exchange with a memory is made by cycle steals. Error detection is also provided for using a cyclic redundancy check technique.

A self-consistency check for unitary propagation of Hawking quanta

NASA Astrophysics Data System (ADS)

Baker, Daniel; Kodwani, Darsh; Pen, Ue-Li; Yang, I.-Sheng

2017-11-01

The black hole information paradox presumes that quantum field theory in curved space-time can provide unitary propagation from a near-horizon mode to an asymptotic Hawking quantum. Instead of invoking conjectural quantum-gravity effects to modify such an assumption, we propose a self-consistency check. We establish an analogy to Feynman’s analysis of a double-slit experiment. Feynman showed that unitary propagation of the interfering particles, namely ignoring the entanglement with the double-slit, becomes an arbitrarily reliable assumption when the screen upon which the interference pattern is projected is infinitely far away. We argue for an analogous self-consistency check for quantum field theory in curved space-time. We apply it to the propagation of Hawking quanta and test whether ignoring the entanglement with the geometry also becomes arbitrarily reliable in the limit of a large black hole. We present curious results to suggest a negative answer, and we discuss how this loss of naive unitarity in QFT might be related to a solution of the paradox based on the soft-hair-memory effect.

Towards Symbolic Model Checking for Multi-Agent Systems via OBDDs

NASA Technical Reports Server (NTRS)

Raimondi, Franco; Lomunscio, Alessio

2004-01-01

We present an algorithm for model checking temporal-epistemic properties of multi-agent systems, expressed in the formalism of interpreted systems. We first introduce a technique for the translation of interpreted systems into boolean formulae, and then present a model-checking algorithm based on this translation. The algorithm is based on OBDD's, as they offer a compact and efficient representation for boolean formulae.

Hebb, pandemonium and catastrophic hypermnesia: the hippocampus as a suppressor of inappropriate associations.

PubMed

McNaughton, Neil; Wickens, Jeff

2003-01-01

The hippocampus has been proposed as a key component of a "behavioural inhibition system". We explore the implications of this idea for the nature of associative memory--i.e. learning that is distinct from the moulding of response sequences by error correction and reinforcement. It leads to the view that all associative memory depends on purely Hebbian mechanisms. Memories involve acquisition of new goals not the strengthening of new stimulus-response links. Critically, memories will consist of affectively positive and affectively negative associations as well "purely cognitive" information. The hippocampus is seen as a supervisor that is normally "just checking" information about current available goals. When one available goal is pre-eminent there is no hippocampal output and the goal controls the response system. When two or more goals are similarly and highly primed there is conflict. This is detected by the hippocampus which sends output that increases the valence of affectively negative perceptions and so resolves the conflict by suppressing more aversive goals. Such conflict resolution occurs with innate as well as acquired goals and is fundamentally non-memorial. But, in memory paradigms, it can often act to suppress interference on the current trial and, through Hebbian association of the increase in negative affect, decrease the probability of interference on later trials and during consolidation. Both memory-driven and innate behaviour is made hippocampal-dependent by innate and acquired conflicting tendencies and not the class of stimulus presented.

A Role for Memory in Prospective Timing informs Timing in Prospective Memory

PubMed Central

Waldum, Emily R; Sahakyan, Lili

2014-01-01

Time-based prospective memory (TBPM) tasks require the estimation of time in passing – known as prospective timing. Prospective timing is said to depend on an attentionally-driven internal clock mechanism, and is thought to be unaffected by memory for interval information (for reviews see, Block, Hancock, & Zakay, 2010; Block & Zakay, 1997). A prospective timing task that required a verbal estimate following the entire interval (Experiment 1) and a TBPM task that required production of a target response during the interval (Experiment 2) were used to test an alternative view that episodic memory does influence prospective timing. In both experiments, participants performed an ongoing lexical decision task of fixed duration while a varying number of songs were played in the background. Experiment 1 results revealed that verbal time estimates became longer the more songs participants remembered from the interval, suggesting that memory for interval information influences prospective time estimates. In Experiment 2, participants who were asked to perform the TBPM task without the aid of an external clock made their target responses earlier as the number of songs increased, indicating that prospective estimates of elapsed time increased as more songs were experienced. For participants who had access to a clock, changes in clock-checking coincided with the occurrence of song boundaries, indicating that participants used both song information and clock information to estimate time. Finally, ongoing task performance and verbal reports in both experiments further substantiate a role for episodic memory in prospective timing. PMID:22984950

Compositional schedulability analysis of real-time actor-based systems.

PubMed

Jaghoori, Mohammad Mahdi; de Boer, Frank; Longuet, Delphine; Chothia, Tom; Sirjani, Marjan

2017-01-01

We present an extension of the actor model with real-time, including deadlines associated with messages, and explicit application-level scheduling policies, e.g.,"earliest deadline first" which can be associated with individual actors. Schedulability analysis in this setting amounts to checking whether, given a scheduling policy for each actor, every task is processed within its designated deadline. To check schedulability, we introduce a compositional automata-theoretic approach, based on maximal use of model checking combined with testing. Behavioral interfaces define what an actor expects from the environment, and the deadlines for messages given these assumptions. We use model checking to verify that actors match their behavioral interfaces. We extend timed automata refinement with the notion of deadlines and use it to define compatibility of actor environments with the behavioral interfaces. Model checking of compatibility is computationally hard, so we propose a special testing process. We show that the analyses are decidable and automate the process using the Uppaal model checker.

Best bang for your buck: GPU nodes for GROMACS biomolecular simulations

PubMed Central

Páll, Szilárd; Fechner, Martin; Esztermann, Ansgar; de Groot, Bert L.; Grubmüller, Helmut

2015-01-01

The molecular dynamics simulation package GROMACS runs efficiently on a wide variety of hardware from commodity workstations to high performance computing clusters. Hardware features are well‐exploited with a combination of single instruction multiple data, multithreading, and message passing interface (MPI)‐based single program multiple data/multiple program multiple data parallelism while graphics processing units (GPUs) can be used as accelerators to compute interactions off‐loaded from the CPU. Here, we evaluate which hardware produces trajectories with GROMACS 4.6 or 5.0 in the most economical way. We have assembled and benchmarked compute nodes with various CPU/GPU combinations to identify optimal compositions in terms of raw trajectory production rate, performance‐to‐price ratio, energy efficiency, and several other criteria. Although hardware prices are naturally subject to trends and fluctuations, general tendencies are clearly visible. Adding any type of GPU significantly boosts a node's simulation performance. For inexpensive consumer‐class GPUs this improvement equally reflects in the performance‐to‐price ratio. Although memory issues in consumer‐class GPUs could pass unnoticed as these cards do not support error checking and correction memory, unreliable GPUs can be sorted out with memory checking tools. Apart from the obvious determinants for cost‐efficiency like hardware expenses and raw performance, the energy consumption of a node is a major cost factor. Over the typical hardware lifetime until replacement of a few years, the costs for electrical power and cooling can become larger than the costs of the hardware itself. Taking that into account, nodes with a well‐balanced ratio of CPU and consumer‐class GPU resources produce the maximum amount of GROMACS trajectory over their lifetime. © 2015 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. PMID:26238484

Best bang for your buck: GPU nodes for GROMACS biomolecular simulations.

PubMed

Kutzner, Carsten; Páll, Szilárd; Fechner, Martin; Esztermann, Ansgar; de Groot, Bert L; Grubmüller, Helmut

2015-10-05

The molecular dynamics simulation package GROMACS runs efficiently on a wide variety of hardware from commodity workstations to high performance computing clusters. Hardware features are well-exploited with a combination of single instruction multiple data, multithreading, and message passing interface (MPI)-based single program multiple data/multiple program multiple data parallelism while graphics processing units (GPUs) can be used as accelerators to compute interactions off-loaded from the CPU. Here, we evaluate which hardware produces trajectories with GROMACS 4.6 or 5.0 in the most economical way. We have assembled and benchmarked compute nodes with various CPU/GPU combinations to identify optimal compositions in terms of raw trajectory production rate, performance-to-price ratio, energy efficiency, and several other criteria. Although hardware prices are naturally subject to trends and fluctuations, general tendencies are clearly visible. Adding any type of GPU significantly boosts a node's simulation performance. For inexpensive consumer-class GPUs this improvement equally reflects in the performance-to-price ratio. Although memory issues in consumer-class GPUs could pass unnoticed as these cards do not support error checking and correction memory, unreliable GPUs can be sorted out with memory checking tools. Apart from the obvious determinants for cost-efficiency like hardware expenses and raw performance, the energy consumption of a node is a major cost factor. Over the typical hardware lifetime until replacement of a few years, the costs for electrical power and cooling can become larger than the costs of the hardware itself. Taking that into account, nodes with a well-balanced ratio of CPU and consumer-class GPU resources produce the maximum amount of GROMACS trajectory over their lifetime. © 2015 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.

ANSYS duplicate finite-element checker routine

NASA Technical Reports Server (NTRS)

Ortega, R.

1995-01-01

An ANSYS finite-element code routine to check for duplicated elements within the volume of a three-dimensional (3D) finite-element mesh was developed. The routine developed is used for checking floating elements within a mesh, identically duplicated elements, and intersecting elements with a common face. A space shuttle main engine alternate turbopump development high pressure oxidizer turbopump finite-element model check using the developed subroutine is discussed. Finally, recommendations are provided for duplicate element checking of 3D finite-element models.

Fault-Tolerant VLSI Design Assessments for Advanced Avionics Department. Literature Review. Phase 1

DTIC Science & Technology

1982-02-05

negative sense. Another facet of the literature review is to acquaint the researchers with the immense literature base for electronic technology applicable ...Riley, "Special Report: Semiconductor Memories are Tested Over Data-Storage Application ", Electronics, vol. 46, August 19. G. Luecke, J. P. Mize and W...Design and Evaluation of Self-Checking Systems", Report Submitted to the Mathematical and Information Science Division of the Office of Naval

Pharmacist and Technician Perceptions of Tech-Check-Tech in Community Pharmacy Practice Settings.

PubMed

Frost, Timothy P; Adams, Alex J

2018-04-01

Tech-check-tech (TCT) is a practice model in which pharmacy technicians with advanced training can perform final verification of prescriptions that have been previously reviewed for appropriateness by a pharmacist. Few states have adopted TCT in part because of the common view that this model is controversial among members of the profession. This article aims to summarize the existing research on pharmacist and technician perceptions of community pharmacy-based TCT. A literature review was conducted using MEDLINE (January 1990 to August 2016) and Google Scholar (January 1990 to August 2016) using the terms "tech* and check," "tech-check-tech," "checking technician," and "accuracy checking tech*." Of the 7 studies identified we found general agreement among both pharmacists and technicians that TCT in community pharmacy settings can be safely performed. This agreement persisted in studies of theoretical TCT models and in studies assessing participants in actual community-based TCT models. Pharmacists who had previously worked with a checking technician were generally more favorable toward TCT. Both pharmacists and technicians in community pharmacy settings generally perceived TCT to be safe, in both theoretical surveys and in surveys following actual TCT demonstration projects. These perceptions of safety align well with the actual outcomes achieved from community pharmacy TCT studies.

Exploiting heat treatment effects on SMAs macro and microscopic properties in developing fire protection devices

NASA Astrophysics Data System (ADS)

Burlacu, L.; Cimpoeşu, N.; Bujoreanu, L. G.; Lohan, N. M.

2017-08-01

Ni-Ti shape memory alloys (SMAs) are intelligent alloys which demonstrate unique properties, such as shape memory effect, two-way shape memory effect, super-elasticity and vibration damping which, accompanied by good processability, excellent corrosion resistance and biocompatibility as well as fair wear resistance and cyclic stability, enabled the development of important industrial applications (such as sensors, actuators, fasteners, couplings and valves), medical applications (such as stents, bone implants, orthodontic archwires, minimal invasive surgical equipment) as well as environmental health and safety devices (anti-seismic dampers, fire safety devices). The phase transitions in Ni-Ti SMAs are strongly influenced by processing methods, chemical compositions and thermomechanical history. This paper presents a study of the effects of heat treatment on the mechanical and thermal properties of commercial Ni-Ti shape memory alloy (SMA). The experimental work involved subjecting a SMA rod to heat-treatment consisting in heating up to 500°C, 10 minutes-maintaining and water quenching. Mechanical properties were highlighted by microhardness tests while thermal characteristics were emphasized by differential scanning calorimetry (DSC). The presence of chemical composition fluctuations was checked by X-ray energy dispersive spectroscopy performed with an EDAX Bruker analyzer.

Reduced memory specificity predicts the acquisition of problem solving skills in psychoeducation.

PubMed

Van Daele, Tom; Van den Bergh, Omer; Van Audenhove, Chantal; Raes, Filip; Hermans, Dirk

2013-03-01

Research has shown that overgeneral autobiographical memory (OGM) is a valid predictor for the course of depression. It is not known, however, whether OGM also moderates information uptake and consolidation in a psychoeducation program to prevent stress, anxiety and depression. The present study was designed to investigate whether the Autobiographical Memory Test (AMT; Williams, & Broadbent, 1986) is a valid predictor for the actual unfolding of skills learned through psychoeducation. The questionnaire included primarily the AMT and the Stress Anxiety Depression Means-Ends Problem Solving Questionnaire (SAD-MEPS). It was filled in prior to and after the psychoeducational course by 23 participants. Correlations were calculated for the AMT at baseline and the differences between the pre and post measurements on the SAD-MEPS. Significant correlations were observed between the number of specific responses and the changes in the number of relevant means (r = .49, p < .01). The sample size was rather small, but several checks were able to reduce the chance of spurious findings. These findings may have important implications for the guidance to and the setup of psychoeducational interventions. Suggestions include screening and memory specificity training prior to course commencement. Copyright © 2011 Elsevier Ltd. All rights reserved.

Model Checking the Remote Agent Planner

NASA Technical Reports Server (NTRS)

Khatib, Lina; Muscettola, Nicola; Havelund, Klaus; Norvig, Peter (Technical Monitor)

2001-01-01

This work tackles the problem of using Model Checking for the purpose of verifying the HSTS (Scheduling Testbed System) planning system. HSTS is the planner and scheduler of the remote agent autonomous control system deployed in Deep Space One (DS1). Model Checking allows for the verification of domain models as well as planning entries. We have chosen the real-time model checker UPPAAL for this work. We start by motivating our work in the introduction. Then we give a brief description of HSTS and UPPAAL. After that, we give a sketch for the mapping of HSTS models into UPPAAL and we present samples of plan model properties one may want to verify.

Random Testing and Model Checking: Building a Common Framework for Nondeterministic Exploration

NASA Technical Reports Server (NTRS)

Groce, Alex; Joshi, Rajeev

2008-01-01

Two popular forms of dynamic analysis, random testing and explicit-state software model checking, are perhaps best viewed as search strategies for exploring the state spaces introduced by nondeterminism in program inputs. We present an approach that enables this nondeterminism to be expressed in the SPIN model checker's PROMELA language, and then lets users generate either model checkers or random testers from a single harness for a tested C program. Our approach makes it easy to compare model checking and random testing for models with precisely the same input ranges and probabilities and allows us to mix random testing with model checking's exhaustive exploration of non-determinism. The PROMELA language, as intended in its design, serves as a convenient notation for expressing nondeterminism and mixing random choices with nondeterministic choices. We present and discuss a comparison of random testing and model checking. The results derive from using our framework to test a C program with an effectively infinite state space, a module in JPL's next Mars rover mission. More generally, we show how the ability of the SPIN model checker to call C code can be used to extend SPIN's features, and hope to inspire others to use the same methods to implement dynamic analyses that can make use of efficient state storage, matching, and backtracking.

Nonlinear integral equations for the sausage model

NASA Astrophysics Data System (ADS)

Ahn, Changrim; Balog, Janos; Ravanini, Francesco

2017-08-01

The sausage model, first proposed by Fateev, Onofri, and Zamolodchikov, is a deformation of the O(3) sigma model preserving integrability. The target space is deformed from the sphere to ‘sausage’ shape by a deformation parameter ν. This model is defined by a factorizable S-matrix which is obtained by deforming that of the O(3) sigma model by a parameter λ. Clues for the deformed sigma model are provided by various UV and IR information through the thermodynamic Bethe ansatz (TBA) analysis based on the S-matrix. Application of TBA to the sausage model is, however, limited to the case of 1/λ integer where the coupled integral equations can be truncated to a finite number. In this paper, we propose a finite set of nonlinear integral equations (NLIEs), which are applicable to generic value of λ. Our derivation is based on T-Q relations extracted from the truncated TBA equations. For a consistency check, we compute next-leading order corrections of the vacuum energy and extract the S-matrix information in the IR limit. We also solved the NLIE both analytically and numerically in the UV limit to get the effective central charge and compared with that of the zero-mode dynamics to obtain exact relation between ν and λ. Dedicated to the memory of Petr Petrovich Kulish.

CheckMATE 2: From the model to the limit

NASA Astrophysics Data System (ADS)

Dercks, Daniel; Desai, Nishita; Kim, Jong Soo; Rolbiecki, Krzysztof; Tattersall, Jamie; Weber, Torsten

2017-12-01

We present the latest developments to the CheckMATE program that allows models of new physics to be easily tested against the recent LHC data. To achieve this goal, the core of CheckMATE now contains over 60 LHC analyses of which 12 are from the 13 TeV run. The main new feature is that CheckMATE 2 now integrates the Monte Carlo event generation via MadGraph5_aMC@NLO and Pythia 8. This allows users to go directly from a SLHA file or UFO model to the result of whether a model is allowed or not. In addition, the integration of the event generation leads to a significant increase in the speed of the program. Many other improvements have also been made, including the possibility to now combine signal regions to give a total likelihood for a model.

Coverage Metrics for Model Checking

NASA Technical Reports Server (NTRS)

Penix, John; Visser, Willem; Norvig, Peter (Technical Monitor)

2001-01-01

When using model checking to verify programs in practice, it is not usually possible to achieve complete coverage of the system. In this position paper we describe ongoing research within the Automated Software Engineering group at NASA Ames on the use of test coverage metrics to measure partial coverage and provide heuristic guidance for program model checking. We are specifically interested in applying and developing coverage metrics for concurrent programs that might be used to support certification of next generation avionics software.

Clomp

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

Gylenhaal, J.; Bronevetsky, G.

2007-05-25

CLOMP is the C version of the Livermore OpenMP benchmark deeloped to measure OpenMP overheads and other performance impacts due to threading (like NUMA memory layouts, memory contention, cache effects, etc.) in order to influence future system design. Current best-in-class implementations of OpenMP have overheads at least ten times larger than is required by many of our applications for effective use of OpenMP. This benchmark shows the significant negative performance impact of these relatively large overheads and of other thread effects. The CLOMP benchmark highly configurable to allow a variety of problem sizes and threading effects to be studied andmore » it carefully checks its results to catch many common threading errors. This benchmark is expected to be included as part of the Sequoia Benchmark suite for the Sequoia procurement.« less

Non-binary LDPC-coded modulation for high-speed optical metro networks with backpropagation

NASA Astrophysics Data System (ADS)

Arabaci, Murat; Djordjevic, Ivan B.; Saunders, Ross; Marcoccia, Roberto M.

2010-01-01

To simultaneously mitigate the linear and nonlinear channel impairments in high-speed optical communications, we propose the use of non-binary low-density-parity-check-coded modulation in combination with a coarse backpropagation method. By employing backpropagation, we reduce the memory in the channel and in return obtain significant reductions in the complexity of the channel equalizer which is exponentially proportional to the channel memory. We then compensate for the remaining channel distortions using forward error correction based on non-binary LDPC codes. We propose non-binary-LDPC-coded modulation scheme because, compared to bit-interleaved binary-LDPC-coded modulation scheme employing turbo equalization, the proposed scheme lowers the computational complexity and latency of the overall system while providing impressively larger coding gains.

KSC-04PD-1810

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser prepare to conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttles Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04PD-1811

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttles Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04pd1811

NASA Image and Video Library

2004-09-17

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttle’s Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04pd1810

NASA Image and Video Library

2004-09-17

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser prepare to conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttle’s Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

Pay attention to your manipulation checks! Reward impact on cardiac reactivity is moderated by task context.

PubMed

Richter, Michael

2010-05-01

Two experiments assessed the moderating impact of task context on the relationship between reward and cardiovascular response. Randomly assigned to the cells of a 2 (task context: reward vs. demand) x 2 (reward value: low vs. high) between-persons design, participants performed either a memory task with an unclear performance standard (Experiment 1) or a visual scanning task with an unfixed performance standard (Experiment 2). Before performing the task--where participants could earn either a low or a high reward--participants responded to questions about either task reward or task demand. In accordance with the theoretical predictions derived from Wright's (1996) integrative model, reactivity of pre-ejection period increased with reward value if participants had rated aspects of task reward before performing the task. If they had rated task demand, pre-ejection period did not differ as a function of reward. Copyright 2010 Elsevier B.V. All rights reserved.

Posterior Predictive Model Checking in Bayesian Networks

ERIC Educational Resources Information Center

Crawford, Aaron

2014-01-01

This simulation study compared the utility of various discrepancy measures within a posterior predictive model checking (PPMC) framework for detecting different types of data-model misfit in multidimensional Bayesian network (BN) models. The investigated conditions were motivated by an applied research program utilizing an operational complex…

Analyzing the cost of screening selectee and non-selectee baggage.

PubMed

Virta, Julie L; Jacobson, Sheldon H; Kobza, John E

2003-10-01

Determining how to effectively operate security devices is as important to overall system performance as developing more sensitive security devices. In light of recent federal mandates for 100% screening of all checked baggage, this research studies the trade-offs between screening only selectee checked baggage and screening both selectee and non-selectee checked baggage for a single baggage screening security device deployed at an airport. This trade-off is represented using a cost model that incorporates the cost of the baggage screening security device, the volume of checked baggage processed through the device, and the outcomes that occur when the device is used. The cost model captures the cost of deploying, maintaining, and operating a single baggage screening security device over a one-year period. The study concludes that as excess baggage screening capacity is used to screen non-selectee checked bags, the expected annual cost increases, the expected annual cost per checked bag screened decreases, and the expected annual cost per expected number of threats detected in the checked bags screened increases. These results indicate that the marginal increase in security per dollar spent is significantly lower when non-selectee checked bags are screened than when only selectee checked bags are screened.

40 CFR 86.327-79 - Quench checks; NOX analyzer.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Quench checks; NOX analyzer. (a) Perform the reaction chamber quench check for each model of high vacuum reaction chamber analyzer prior to initial use. (b) Perform the reaction chamber quench check for each new analyzer that has an ambient pressure or “soft vacuum” reaction chamber prior to initial use. Additionally...

40 CFR 86.327-79 - Quench checks; NOX analyzer.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Quench checks; NOX analyzer. (a) Perform the reaction chamber quench check for each model of high vacuum reaction chamber analyzer prior to initial use. (b) Perform the reaction chamber quench check for each new analyzer that has an ambient pressure or “soft vacuum” reaction chamber prior to initial use. Additionally...

Verification using Satisfiability Checking, Predicate Abstraction, and Craig Interpolation

DTIC Science & Technology

2008-09-01

297, 2007. 4.10.1 196 [48] Roberto Bruttomesso, Alessandro Cimatti, Anders Franzen, Alberto Grig- gio, Ziyad Hanna, Alexander Nadel, Amit Palti, and...using SAT based conflict analysis. In Formal Methods in Computer Aided Design, pages 33–51, 2002. 1.1, 7 [54] Alessandro Cimatti, Alberto Griggio, and...and D. Vroon. Automatic memory reductions for RTL-level verification. In ICCAD, 2006. 1.2.4, 6.2, 7 [108] Joao P. Marques-Silva and Karem A. Sakallah

To What Extent Does Children's Spelling Improve as a Result of Learning Words with the Look, Say, Cover, Write, Check, Fix Strategy Compared with Phonological Spelling Strategies?

ERIC Educational Resources Information Center

Dymock, Susan; Nicholson, Tom

2017-01-01

The ubiquitous weekly spelling test assumes that words are best learned by memorisation and testing but is this the best way? This study compared two well-known approaches to spelling instruction, the rule based and visual memory approaches. A group of 55 seven-year-olds in two Year 3 classrooms was taught spelling in small groups for three…

Phase Two Feasibility Study for Software Safety Requirements Analysis Using Model Checking

NASA Technical Reports Server (NTRS)

Turgeon, Gregory; Price, Petra

2010-01-01

A feasibility study was performed on a representative aerospace system to determine the following: (1) the benefits and limitations to using SCADE , a commercially available tool for model checking, in comparison to using a proprietary tool that was studied previously [1] and (2) metrics for performing the model checking and for assessing the findings. This study was performed independently of the development task by a group unfamiliar with the system, providing a fresh, external perspective free from development bias.

MPST Software: grl_pef_check

NASA Technical Reports Server (NTRS)

Call, Jared A.; Kwok, John H.; Fisher, Forest W.

2013-01-01

This innovation is a tool used to verify and validate spacecraft sequences at the predicted events file (PEF) level for the GRAIL (Gravity Recovery and Interior Laboratory, see http://www.nasa. gov/mission_pages/grail/main/index. html) mission as part of the Multi-Mission Planning and Sequencing Team (MPST) operations process to reduce the possibility for errors. This tool is used to catch any sequence related errors or issues immediately after the seqgen modeling to streamline downstream processes. This script verifies and validates the seqgen modeling for the GRAIL MPST process. A PEF is provided as input, and dozens of checks are performed on it to verify and validate the command products including command content, command ordering, flight-rule violations, modeling boundary consistency, resource limits, and ground commanding consistency. By performing as many checks as early in the process as possible, grl_pef_check streamlines the MPST task of generating GRAIL command and modeled products on an aggressive schedule. By enumerating each check being performed, and clearly stating the criteria and assumptions made at each step, grl_pef_check can be used as a manual checklist as well as an automated tool. This helper script was written with a focus on enabling the user with the information they need in order to evaluate a sequence quickly and efficiently, while still keeping them informed and active in the overall sequencing process. grl_pef_check verifies and validates the modeling and sequence content prior to investing any more effort into the build. There are dozens of various items in the modeling run that need to be checked, which is a time-consuming and errorprone task. Currently, no software exists that provides this functionality. Compared to a manual process, this script reduces human error and saves considerable man-hours by automating and streamlining the mission planning and sequencing task for the GRAIL mission.

Practical Formal Verification of Diagnosability of Large Models via Symbolic Model Checking

NASA Technical Reports Server (NTRS)

Cavada, Roberto; Pecheur, Charles

2003-01-01

This document reports on the activities carried out during a four-week visit of Roberto Cavada at the NASA Ames Research Center. The main goal was to test the practical applicability of the framework proposed, where a diagnosability problem is reduced to a Symbolic Model Checking problem. Section 2 contains a brief explanation of major techniques currently used in Symbolic Model Checking, and how these techniques can be tuned in order to obtain good performances when using Model Checking tools. Diagnosability is performed on large and structured models of real plants. Section 3 describes how these plants are modeled, and how models can be simplified to improve the performance of Symbolic Model Checkers. Section 4 reports scalability results. Three test cases are briefly presented, and several parameters and techniques have been applied on those test cases in order to produce comparison tables. Furthermore, comparison between several Model Checkers is reported. Section 5 summarizes the application of diagnosability verification to a real application. Several properties have been tested, and results have been highlighted. Finally, section 6 draws some conclusions, and outlines future lines of research.

Non-equilibrium dog-flea model

NASA Astrophysics Data System (ADS)

Ackerson, Bruce J.

2017-11-01

We develop the open dog-flea model to serve as a check of proposed non-equilibrium theories of statistical mechanics. The model is developed in detail. Then it is applied to four recent models for non-equilibrium statistical mechanics. Comparison of the dog-flea solution with these different models allows checking claims and giving a concrete example of the theoretical models.

Functional independence within the self-memory system: new insights from two cases of developmental amnesia.

PubMed

Picard, Laurence; Mayor-Dubois, Claire; Maeder, Philippe; Kalenzaga, Sandrine; Abram, Maria; Duval, Céline; Eustache, Francis; Roulet-Perez, Eliane; Piolino, Pascale

2013-06-01

Neuropsychological and neuroimaging data suggest that the self-memory system can be fractionated into three functionally independent systems processing personal information at several levels of abstraction, including episodic memories of one's life (episodic autobiographical memory, EAM), semantic knowledge of facts about one's life (semantic autobiographical memory, SAM), and semantic knowledge of one's personality [conceptual self, (CS)]. Through the study of two developmental amnesic patients suffering of neonatal brain injuries, we explored how the different facets of the self-memory system develop when growing up with bilateral hippocampal atrophy. Neuropsychological evaluations showed that both of them suffered from dramatic episodic learning disability with no sense of recollection (Remember/Know procedure), whereas their semantic abilities differed, being completely preserved (Valentine) or not (Jocelyn). Magnetic resonance imaging, including quantitative volumetric measurements of the hippocampus and adjacent (entorhinal, perirhinal, and temporopolar) cortex, showed severe bilateral atrophy of the hippocampus in both patients, with additional atrophy of adjacent cortex in Jocelyn. Exploration of EAM and SAM according to lifetime periods covering the entire lifespan (TEMPAu task, Piolino et al., 2009) showed that both patients had marked impairments in EAM, as they lacked specificity, details and sense of recollection, whereas SAM was completely normal in Valentine, but impaired in Jocelyn. Finally, measures of patients' CS (Tennessee Self-Concept Scale, Fitts and Warren, 1996), checked by their mothers, were generally within normal range, but both patients showed a more positive self-concept than healthy controls. These two new cases support a modular account of the medial-temporal lobe with episodic memory and recollection depending on the hippocampus, and semantic memory and familiarity on adjacent cortices. Furthermore, they highlight developmental episodic and semantic functional independence within the self-memory system suggesting that SAM and CS may be acquired without episodic memories. Copyright © 2012 Elsevier Ltd. All rights reserved.

Abstraction and Assume-Guarantee Reasoning for Automated Software Verification

NASA Technical Reports Server (NTRS)

Chaki, S.; Clarke, E.; Giannakopoulou, D.; Pasareanu, C. S.

2004-01-01

Compositional verification and abstraction are the key techniques to address the state explosion problem associated with model checking of concurrent software. A promising compositional approach is to prove properties of a system by checking properties of its components in an assume-guarantee style. This article proposes a framework for performing abstraction and assume-guarantee reasoning of concurrent C code in an incremental and fully automated fashion. The framework uses predicate abstraction to extract and refine finite state models of software and it uses an automata learning algorithm to incrementally construct assumptions for the compositional verification of the abstract models. The framework can be instantiated with different assume-guarantee rules. We have implemented our approach in the COMFORT reasoning framework and we show how COMFORT out-performs several previous software model checking approaches when checking safety properties of non-trivial concurrent programs.

Incremental checking of Master Data Management model based on contextual graphs

NASA Astrophysics Data System (ADS)

Lamolle, Myriam; Menet, Ludovic; Le Duc, Chan

2015-10-01

The validation of models is a crucial step in distributed heterogeneous systems. In this paper, an incremental validation method is proposed in the scope of a Model Driven Engineering (MDE) approach, which is used to develop a Master Data Management (MDM) field represented by XML Schema models. The MDE approach presented in this paper is based on the definition of an abstraction layer using UML class diagrams. The validation method aims to minimise the model errors and to optimisethe process of model checking. Therefore, the notion of validation contexts is introduced allowing the verification of data model views. Description logics specify constraints that the models have to check. An experimentation of the approach is presented through an application developed in ArgoUML IDE.

Model Checking - My 27-Year Quest to Overcome the State Explosion Problem

NASA Technical Reports Server (NTRS)

Clarke, Ed

2009-01-01

Model Checking is an automatic verification technique for state-transition systems that are finite=state or that have finite-state abstractions. In the early 1980 s in a series of joint papers with my graduate students E.A. Emerson and A.P. Sistla, we proposed that Model Checking could be used for verifying concurrent systems and gave algorithms for this purpose. At roughly the same time, Joseph Sifakis and his student J.P. Queille at the University of Grenoble independently developed a similar technique. Model Checking has been used successfully to reason about computer hardware and communication protocols and is beginning to be used for verifying computer software. Specifications are written in temporal logic, which is particularly valuable for expressing concurrency properties. An intelligent, exhaustive search is used to determine if the specification is true or not. If the specification is not true, the Model Checker will produce a counterexample execution trace that shows why the specification does not hold. This feature is extremely useful for finding obscure errors in complex systems. The main disadvantage of Model Checking is the state-explosion problem, which can occur if the system under verification has many processes or complex data structures. Although the state-explosion problem is inevitable in worst case, over the past 27 years considerable progress has been made on the problem for certain classes of state-transition systems that occur often in practice. In this talk, I will describe what Model Checking is, how it works, and the main techniques that have been developed for combating the state explosion problem.

A Multidimensional Item Response Model: Constrained Latent Class Analysis Using the Gibbs Sampler and Posterior Predictive Checks.

ERIC Educational Resources Information Center

Hoijtink, Herbert; Molenaar, Ivo W.

1997-01-01

This paper shows that a certain class of constrained latent class models may be interpreted as a special case of nonparametric multidimensional item response models. Parameters of this latent class model are estimated using an application of the Gibbs sampler, and model fit is investigated using posterior predictive checks. (SLD)

Global exponential stability of BAM neural networks with time-varying delays: The discrete-time case

NASA Astrophysics Data System (ADS)

Raja, R.; Marshal Anthoni, S.

2011-02-01

This paper deals with the problem of stability analysis for a class of discrete-time bidirectional associative memory (BAM) neural networks with time-varying delays. By employing the Lyapunov functional and linear matrix inequality (LMI) approach, a new sufficient conditions is proposed for the global exponential stability of discrete-time BAM neural networks. The proposed LMI based results can be easily checked by LMI control toolbox. Moreover, an example is also provided to demonstrate the effectiveness of the proposed method.

Passivity analysis for uncertain BAM neural networks with time delays and reaction-diffusions

NASA Astrophysics Data System (ADS)

Zhou, Jianping; Xu, Shengyuan; Shen, Hao; Zhang, Baoyong

2013-08-01

This article deals with the problem of passivity analysis for delayed reaction-diffusion bidirectional associative memory (BAM) neural networks with weight uncertainties. By using a new integral inequality, we first present a passivity condition for the nominal networks, and then extend the result to the case with linear fractional weight uncertainties. The proposed conditions are expressed in terms of linear matrix inequalities, and thus can be checked easily. Examples are provided to demonstrate the effectiveness of the proposed results.

Authenticating Secure Tokens Using Slow Memory Access

DTIC Science & Technology

1999-01-01

Cryptology— CRYPTO ’97 Proceedings, Springer- Verlag, 1997, pp. 513–525. [CP93] D . Chaum and T. Pederson, “Wallet Databases with Observers,” Advances in...96 Proceedings, Springer-Verlag, 1996, pp. 1–15. [BDL97] D . Boneh, R.A. Demillo, R.J. Lip- ton, “On the Importance of Check- ing Cryptographic...Protocols for Faults,” Advances in Cryptology—EUROCRYPT ’97 Proceedings, Springer-Verlag, 1997, pp. 37–51. [BGW98] M. Briceno, I. Goldberg, D . Wagner

Construct validity and reliability of the Single Checking Administration of Medications Scale.

PubMed

O'Connell, Beverly; Hawkins, Mary; Ockerby, Cherene

2013-06-01

Research indicates that single checking of medications is as safe as double checking; however, many nurses are averse to independently checking medications. To assist with the introduction and use of single checking, a measure of nurses' attitudes, the thirteen-item Single Checking Administration of Medications Scale (SCAMS) was developed. We examined the psychometric properties of the SCAMS. Secondary analyses were conducted on data collected from 503 nurses across a large Australian health-care service. Analyses using exploratory and confirmatory factor analyses supported by structural equation modelling resulted in a valid twelve-item SCAMS containing two reliable subscales, the nine-item Attitudes towards single checking and three-item Advantages of single checking subscales. The SCAMS is recommended as a valid and reliable measure for monitoring nurses' attitudes to single checking prior to introducing single checking medications and after its implementation. © 2013 Wiley Publishing Asia Pty Ltd.

Simulation-based model checking approach to cell fate specification during Caenorhabditis elegans vulval development by hybrid functional Petri net with extension.

PubMed

Li, Chen; Nagasaki, Masao; Ueno, Kazuko; Miyano, Satoru

2009-04-27

Model checking approaches were applied to biological pathway validations around 2003. Recently, Fisher et al. have proved the importance of model checking approach by inferring new regulation of signaling crosstalk in C. elegans and confirming the regulation with biological experiments. They took a discrete and state-based approach to explore all possible states of the system underlying vulval precursor cell (VPC) fate specification for desired properties. However, since both discrete and continuous features appear to be an indispensable part of biological processes, it is more appropriate to use quantitative models to capture the dynamics of biological systems. Our key motivation of this paper is to establish a quantitative methodology to model and analyze in silico models incorporating the use of model checking approach. A novel method of modeling and simulating biological systems with the use of model checking approach is proposed based on hybrid functional Petri net with extension (HFPNe) as the framework dealing with both discrete and continuous events. Firstly, we construct a quantitative VPC fate model with 1761 components by using HFPNe. Secondly, we employ two major biological fate determination rules - Rule I and Rule II - to VPC fate model. We then conduct 10,000 simulations for each of 48 sets of different genotypes, investigate variations of cell fate patterns under each genotype, and validate the two rules by comparing three simulation targets consisting of fate patterns obtained from in silico and in vivo experiments. In particular, an evaluation was successfully done by using our VPC fate model to investigate one target derived from biological experiments involving hybrid lineage observations. However, the understandings of hybrid lineages are hard to make on a discrete model because the hybrid lineage occurs when the system comes close to certain thresholds as discussed by Sternberg and Horvitz in 1986. Our simulation results suggest that: Rule I that cannot be applied with qualitative based model checking, is more reasonable than Rule II owing to the high coverage of predicted fate patterns (except for the genotype of lin-15ko; lin-12ko double mutants). More insights are also suggested. The quantitative simulation-based model checking approach is a useful means to provide us valuable biological insights and better understandings of biological systems and observation data that may be hard to capture with the qualitative one.

The Priority Inversion Problem and Real-Time Symbolic Model Checking

DTIC Science & Technology

1993-04-23

real time systems unpredictable in subtle ways. This makes it more difficult to implement and debug such systems. Our work discusses this problem and presents one possible solution. The solution is formalized and verified using temporal logic model checking techniques. In order to perform the verification, the BDD-based symbolic model checking algorithm given in previous works was extended to handle real-time properties using the bounded until operator. We believe that this algorithm, which is based on discrete time, is able to handle many real-time properties

Design of Installing Check Dam Using RAMMS Model in Seorak National Park of South Korea

NASA Astrophysics Data System (ADS)

Jun, K.; Tak, W.; JUN, B. H.; Lee, H. J.; KIM, S. D.

2016-12-01

Design of Installing Check Dam Using RAMMS Model in Seorak National Park of South Korea Kye-Won Jun*, Won-Jun Tak*, Byong-Hee Jun**, Ho-Jin Lee***, Soung-Doug Kim* *Graduate School of Disaster Prevention, Kangwon National University, 346 Joogang-ro, Samcheok-si, Gangwon-do, Korea **School of Fire and Disaster Protection, Kangwon National University, 346 Joogang-ro, Samcheok-si, Gangwon-do, Korea ***School of Civil Engineering, Chungbuk National University, 1 Chungdae-ro, Seowon-gu, Cheongju, Korea Abstract As more than 64% of the land in South Korea is mountainous area, so many regions in South Korea are exposed to the danger of landslide and debris flow. So it is important to understand the behavior of debris flow in mountainous terrains, the various methods and models are being presented and developed based on the mathematical concept. The purpose of this study is to investigate the regions that experienced the debris flow due to typhoon called Ewiniar and to perform numerical modeling to design and layout of the Check dam for reducing the damage by the debris flow. For the performance of numerical modeling, on-site measurement of the research area was conducted including: topographic investigation, research on bridges in the downstream, and precision LiDAR 3D scanning for composed basic data of numerical modeling. The numerical simulation of this study was performed using RAMMS (Rapid Mass Movements Simulation) model for the analysis of the debris flow. This model applied to the conditions of the Check dam which was installed in the upstream, midstream, and downstream. Considering the reduction effect of debris flow, the expansion of debris flow, and the influence on the bridges in the downstream, proper location of the Check dam was designated. The result of present numerical model showed that when the Check dam was installed in the downstream section, 50 m above the bridge, the reduction effect of the debris flow was higher compared to when the Check dam were installed in other sections. Key words: Debris flow, LiDAR, Check dam, RAMMSAcknowledgementsThis research was supported by a grant [MPSS-NH-2014-74] through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government

Model building strategy for logistic regression: purposeful selection.

PubMed

Zhang, Zhongheng

2016-03-01

Logistic regression is one of the most commonly used models to account for confounders in medical literature. The article introduces how to perform purposeful selection model building strategy with R. I stress on the use of likelihood ratio test to see whether deleting a variable will have significant impact on model fit. A deleted variable should also be checked for whether it is an important adjustment of remaining covariates. Interaction should be checked to disentangle complex relationship between covariates and their synergistic effect on response variable. Model should be checked for the goodness-of-fit (GOF). In other words, how the fitted model reflects the real data. Hosmer-Lemeshow GOF test is the most widely used for logistic regression model.

HiVy automated translation of stateflow designs for model checking verification

NASA Technical Reports Server (NTRS)

Pingree, Paula

2003-01-01

tool set enables model checking of finite state machines designs. This is acheived by translating state-chart specifications into the input language of the Spin model checker. An abstract syntax of hierarchical sequential automata (HSA) is provided as an intermediate format tool set.

Model Checking Real Time Java Using Java PathFinder

NASA Technical Reports Server (NTRS)

Lindstrom, Gary; Mehlitz, Peter C.; Visser, Willem

2005-01-01

The Real Time Specification for Java (RTSJ) is an augmentation of Java for real time applications of various degrees of hardness. The central features of RTSJ are real time threads; user defined schedulers; asynchronous events, handlers, and control transfers; a priority inheritance based default scheduler; non-heap memory areas such as immortal and scoped, and non-heap real time threads whose execution is not impeded by garbage collection. The Robust Software Systems group at NASA Ames Research Center has JAVA PATHFINDER (JPF) under development, a Java model checker. JPF at its core is a state exploring JVM which can examine alternative paths in a Java program (e.g., via backtracking) by trying all nondeterministic choices, including thread scheduling order. This paper describes our implementation of an RTSJ profile (subset) in JPF, including requirements, design decisions, and current implementation status. Two examples are analyzed: jobs on a multiprogramming operating system, and a complex resource contention example involving autonomous vehicles crossing an intersection. The utility of JPF in finding logic and timing errors is illustrated, and the remaining challenges in supporting all of RTSJ are assessed.

A fast semi-discrete Kansa method to solve the two-dimensional spatiotemporal fractional diffusion equation

NASA Astrophysics Data System (ADS)

Sun, HongGuang; Liu, Xiaoting; Zhang, Yong; Pang, Guofei; Garrard, Rhiannon

2017-09-01

Fractional-order diffusion equations (FDEs) extend classical diffusion equations by quantifying anomalous diffusion frequently observed in heterogeneous media. Real-world diffusion can be multi-dimensional, requiring efficient numerical solvers that can handle long-term memory embedded in mass transport. To address this challenge, a semi-discrete Kansa method is developed to approximate the two-dimensional spatiotemporal FDE, where the Kansa approach first discretizes the FDE, then the Gauss-Jacobi quadrature rule solves the corresponding matrix, and finally the Mittag-Leffler function provides an analytical solution for the resultant time-fractional ordinary differential equation. Numerical experiments are then conducted to check how the accuracy and convergence rate of the numerical solution are affected by the distribution mode and number of spatial discretization nodes. Applications further show that the numerical method can efficiently solve two-dimensional spatiotemporal FDE models with either a continuous or discrete mixing measure. Hence this study provides an efficient and fast computational method for modeling super-diffusive, sub-diffusive, and mixed diffusive processes in large, two-dimensional domains with irregular shapes.

Petri Net and Probabilistic Model Checking Based Approach for the Modelling, Simulation and Verification of Internet Worm Propagation

PubMed Central

Razzaq, Misbah; Ahmad, Jamil

2015-01-01

Internet worms are analogous to biological viruses since they can infect a host and have the ability to propagate through a chosen medium. To prevent the spread of a worm or to grasp how to regulate a prevailing worm, compartmental models are commonly used as a means to examine and understand the patterns and mechanisms of a worm spread. However, one of the greatest challenge is to produce methods to verify and validate the behavioural properties of a compartmental model. This is why in this study we suggest a framework based on Petri Nets and Model Checking through which we can meticulously examine and validate these models. We investigate Susceptible-Exposed-Infectious-Recovered (SEIR) model and propose a new model Susceptible-Exposed-Infectious-Recovered-Delayed-Quarantined (Susceptible/Recovered) (SEIDQR(S/I)) along with hybrid quarantine strategy, which is then constructed and analysed using Stochastic Petri Nets and Continuous Time Markov Chain. The analysis shows that the hybrid quarantine strategy is extremely effective in reducing the risk of propagating the worm. Through Model Checking, we gained insight into the functionality of compartmental models. Model Checking results validate simulation ones well, which fully support the proposed framework. PMID:26713449

Petri Net and Probabilistic Model Checking Based Approach for the Modelling, Simulation and Verification of Internet Worm Propagation.

PubMed

Razzaq, Misbah; Ahmad, Jamil

2015-01-01

Internet worms are analogous to biological viruses since they can infect a host and have the ability to propagate through a chosen medium. To prevent the spread of a worm or to grasp how to regulate a prevailing worm, compartmental models are commonly used as a means to examine and understand the patterns and mechanisms of a worm spread. However, one of the greatest challenge is to produce methods to verify and validate the behavioural properties of a compartmental model. This is why in this study we suggest a framework based on Petri Nets and Model Checking through which we can meticulously examine and validate these models. We investigate Susceptible-Exposed-Infectious-Recovered (SEIR) model and propose a new model Susceptible-Exposed-Infectious-Recovered-Delayed-Quarantined (Susceptible/Recovered) (SEIDQR(S/I)) along with hybrid quarantine strategy, which is then constructed and analysed using Stochastic Petri Nets and Continuous Time Markov Chain. The analysis shows that the hybrid quarantine strategy is extremely effective in reducing the risk of propagating the worm. Through Model Checking, we gained insight into the functionality of compartmental models. Model Checking results validate simulation ones well, which fully support the proposed framework.

A dual-trace model for visual sensory memory.

PubMed

Cappiello, Marcus; Zhang, Weiwei

2016-11-01

Visual sensory memory refers to a transient memory lingering briefly after the stimulus offset. Although previous literature suggests that visual sensory memory is supported by a fine-grained trace for continuous representation and a coarse-grained trace of categorical information, simultaneous separation and assessment of these traces can be difficult without a quantitative model. The present study used a continuous estimation procedure to test a novel mathematical model of the dual-trace hypothesis of visual sensory memory according to which visual sensory memory could be modeled as a mixture of 2 von Mises (2VM) distributions differing in standard deviation. When visual sensory memory and working memory (WM) for colors were distinguished using different experimental manipulations in the first 3 experiments, the 2VM model outperformed Zhang and Luck (2008) standard mixture model (SM) representing a mixture of a single memory trace and random guesses, even though SM outperformed 2VM for WM. Experiment 4 generalized 2VM's advantages of fitting visual sensory memory data over SM from color to orientation. Furthermore, a single trace model and 4 other alternative models were ruled out, suggesting the necessity and sufficiency of dual traces for visual sensory memory. Together these results support the dual-trace model of visual sensory memory and provide a preliminary inquiry into the nature of information loss from visual sensory memory to WM. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

BrainCheck - a very brief tool to detect incipient cognitive decline: optimized case-finding combining patient- and informant-based data.

PubMed

Ehrensperger, Michael M; Taylor, Kirsten I; Berres, Manfred; Foldi, Nancy S; Dellenbach, Myriam; Bopp, Irene; Gold, Gabriel; von Gunten, Armin; Inglin, Daniel; Müri, René; Rüegger, Brigitte; Kressig, Reto W; Monsch, Andreas U

2014-01-01

Optimal identification of subtle cognitive impairment in the primary care setting requires a very brief tool combining (a) patients' subjective impairments, (b) cognitive testing, and (c) information from informants. The present study developed a new, very quick and easily administered case-finding tool combining these assessments ('BrainCheck') and tested the feasibility and validity of this instrument in two independent studies. We developed a case-finding tool comprised of patient-directed (a) questions about memory and depression and (b) clock drawing, and (c) the informant-directed 7-item version of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Feasibility study: 52 general practitioners rated the feasibility and acceptance of the patient-directed tool. Validation study: An independent group of 288 Memory Clinic patients (mean ± SD age = 76.6 ± 7.9, education = 12.0 ± 2.6; 53.8% female) with diagnoses of mild cognitive impairment (n = 80), probable Alzheimer's disease (n = 185), or major depression (n = 23) and 126 demographically matched, cognitively healthy volunteer participants (age = 75.2 ± 8.8, education = 12.5 ± 2.7; 40% female) partook. All patient and healthy control participants were administered the patient-directed tool, and informants of 113 patient and 70 healthy control participants completed the very short IQCODE. Feasibility study: General practitioners rated the patient-directed tool as highly feasible and acceptable. Validation study: A Classification and Regression Tree analysis generated an algorithm to categorize patient-directed data which resulted in a correct classification rate (CCR) of 81.2% (sensitivity = 83.0%, specificity = 79.4%). Critically, the CCR of the combined patient- and informant-directed instruments (BrainCheck) reached nearly 90% (that is 89.4%; sensitivity = 97.4%, specificity = 81.6%). A new and very brief instrument for general practitioners, 'BrainCheck', combined three sources of information deemed critical for effective case-finding (that is, patients' subject impairments, cognitive testing, informant information) and resulted in a nearly 90% CCR. Thus, it provides a very efficient and valid tool to aid general practitioners in deciding whether patients with suspected cognitive impairments should be further evaluated or not ('watchful waiting').

Immediate Effects of Body Checking Behaviour on Negative and Positive Emotions in Women with Eating Disorders: An Ecological Momentary Assessment Approach.

PubMed

Kraus, Nicole; Lindenberg, Julia; Zeeck, Almut; Kosfelder, Joachim; Vocks, Silja

2015-09-01

Cognitive-behavioural models of eating disorders state that body checking arises in response to negative emotions in order to reduce the aversive emotional state and is therefore negatively reinforced. This study empirically tests this assumption. For a seven-day period, women with eating disorders (n = 26) and healthy controls (n = 29) were provided with a handheld computer for assessing occurring body checking strategies as well as negative and positive emotions. Serving as control condition, randomized computer-emitted acoustic signals prompted reports on body checking and emotions. There was no difference in the intensity of negative emotions before body checking and in control situations across groups. However, from pre- to post-body checking, an increase in negative emotions was found. This effect was more pronounced in women with eating disorders compared with healthy controls. Results are contradictory to the assumptions of the cognitive-behavioural model, as body checking does not seem to reduce negative emotions. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.

Attention, Working Memory, and Long-Term Memory in Multimedia Learning: An Integrated Perspective Based on Process Models of Working Memory

ERIC Educational Resources Information Center

Schweppe, Judith; Rummer, Ralf

2014-01-01

Cognitive models of multimedia learning such as the Cognitive Theory of Multimedia Learning (Mayer 2009) or the Cognitive Load Theory (Sweller 1999) are based on different cognitive models of working memory (e.g., Baddeley 1986) and long-term memory. The current paper describes a working memory model that has recently gained popularity in basic…

Shape memory polymeric composites sensing by optic fibre Bragg gratings: A very first approach

NASA Astrophysics Data System (ADS)

Quadrini, Fabrizio; Santo, Loredana; Ciminello, Monica; Concilio, Antonio; Volponi, Ruggero; Spena, Paola

2016-05-01

Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, spanning from self-repairing of structures to self-deploying of antennas, solar sails, or functional devices (e.g. for grabbing small space debris). In all these cases, it may be essential to have information about their configuration at different stages of shape recovery. In this study, the strain history of a prepreg carbon fibre system, cured with a shape memory polymer (SMP) interlayer, is monitored through a Fibre Bragg Grating (FBG), a fibre optic sensor device. SMPC has been manufactured by using traditional technologies for aerospace. After manufacturing cylindrical shape samples, an external fibre optic system is added to the composite structure; this system is especially suited for high temperatures which are necessary for SMP recovery and composite softening. Sensor functionality is checked before and after each strain history path. Optic fibre arrangement is optimized to avoid unwanted breakings whereas strains are limited by fibre collapsing, i.e. within nominal 2% of deformation. Dynamic information about shape recovery gives fundamental insights about strain evolution during time as well as its spatial distribution.

Model Diagnostics for Bayesian Networks

ERIC Educational Resources Information Center

Sinharay, Sandip

2006-01-01

Bayesian networks are frequently used in educational assessments primarily for learning about students' knowledge and skills. There is a lack of works on assessing fit of Bayesian networks. This article employs the posterior predictive model checking method, a popular Bayesian model checking tool, to assess fit of simple Bayesian networks. A…

The role of objective cognitive dysfunction in subjective cognitive complaints after stroke.

PubMed

van Rijsbergen, M W A; Mark, R E; Kop, W J; de Kort, P L M; Sitskoorn, M M

2017-03-01

Objective cognitive performance (OCP) is often impaired in patients post-stroke but the consequences of OCP for patient-reported subjective cognitive complaints (SCC) are poorly understood. We performed a detailed analysis on the association between post-stroke OCP and SCC. Assessments of OCP and SCC were obtained in 208 patients 3 months after stroke. OCP was evaluated using conventional and ecologically valid neuropsychological tests. Levels of SCC were measured using the CheckList for Cognitive and Emotional (CLCE) consequences following stroke inventory. Multivariate hierarchical regression analyses were used to evaluate the association of OCP with CLCE scores adjusting for age, sex and intelligence quotient. Analyses were performed to examine the global extent of OCP dysfunction (based on the total number of impaired neuropsychological tests, i.e. objective cognitive impairment index) and for each OCP test separately using the raw neuropsychological (sub)test scores. The objective cognitive impairment index for global OCP was positively correlated with the CLCE score (Spearman's rho = 0.22, P = 0.003), which remained significant in multivariate adjusted models (β = 0.25, P = 0.01). Results for the separate neuropsychological tests indicated that only one task (the ecologically valid Rivermead Behavioural Memory Test) was independently associated with the CLCE in multivariate adjusted models (β = -0.34, P < 0.001). Objective neuropsychological test performance, as measured by the global dysfunction index or an ecologically valid memory task, was associated with SCC. These data suggest that cumulative deficits in multiple cognitive domains contribute to subjectively experienced poor cognitive abilities in daily life in patients post-stroke. © 2016 EAN.

Perceptual impairment in face identification with poor sleep

PubMed Central

Beattie, Louise; Walsh, Darragh; McLaren, Jessica; Biello, Stephany M.

2016-01-01

Previous studies have shown impaired memory for faces following restricted sleep. However, it is not known whether lack of sleep impairs performance on face identification tasks that do not rely on recognition memory, despite these tasks being more prevalent in security and forensic professions—for example, in photo-ID checks at national borders. Here we tested whether poor sleep affects accuracy on a standard test of face-matching ability that does not place demands on memory: the Glasgow Face-Matching Task (GFMT). In Experiment 1, participants who reported sleep disturbance consistent with insomnia disorder show impaired accuracy on the GFMT when compared with participants reporting normal sleep behaviour. In Experiment 2, we then used a sleep diary method to compare GFMT accuracy in a control group to participants reporting poor sleep on three consecutive nights—and again found lower accuracy scores in the short sleep group. In both experiments, reduced face-matching accuracy in those with poorer sleep was not associated with lower confidence in their decisions, carrying implications for occupational settings where identification errors made with high confidence can have serious outcomes. These results suggest that sleep-related impairments in face memory reflect difficulties in perceptual encoding of identity, and point towards metacognitive impairment in face matching following poor sleep. PMID:27853547

Memory reconsolidation may be disrupted by a distractor stimulus presented during reactivation

PubMed Central

Crestani, Ana Paula; Zacouteguy Boos, Flávia; Haubrich, Josué; Ordoñez Sierra, Rodrigo; Santana, Fabiana; Molina, Johanna Marcela Duran; Cassini, Lindsey de Freitas; Alvares, Lucas de Oliveira; Quillfeldt, Jorge Alberto

2015-01-01

Memories can be destabilized by the reexposure to the training context, and may reconsolidate into a modified engram. Reconsolidation relies on some particular molecular mechanisms involving LVGCCs and GluN2B-containing NMDARs. In this study we investigate the interference caused by the presence of a distractor - a brief, unanticipated stimulus that impair a fear memory expression - during the reactivation session, and tested the hypothesis that this disruptive effect relies on a reconsolidation process. Rats previously trained in the contextual fear conditioning (CFC) were reactivated in the presence or absence of a distractor stimulus. In the test, groups reactivated in the original context with distractor displayed a reduction of the freezing response lasting up to 20 days. To check for the involvement of destabilization / reconsolidation mechanisms, we studied the effect of systemic nimodipine (a L-VGCC blocker) or intra-CA1 ifenprodil (a selective GluN2B/NMDAR antagonist) infused right before the reactivation session. Both treatments were able to prevent the disruptive effect of distraction. Ifenprodil results also bolstered the case for hippocampus as the putative brain structure hosting this phenomenon. Our results provide some evidence in support of a behavioral, non-invasive procedure that was able to disrupt an aversive memory in a long-lasting way. PMID:26328547

Age-related differences in time-based prospective memory: The role of time estimation in the clock monitoring strategy.

PubMed

Vanneste, Sandrine; Baudouin, Alexia; Bouazzaoui, Badiâa; Taconnat, Laurence

2016-07-01

Time-based prospective memory (TBPM) is required when it is necessary to remember to perform an action at a specific future point in time. This type of memory has been found to be particularly sensitive to ageing, probably because it requires a self-initiated response at a specific time. In this study, we sought to examine the involvement of temporal processes in the time monitoring strategy, which has been demonstrated to be a decisive factor in TBPM efficiency. We compared the performance of young and older adults in a TBPM task in which they had to press a response button every minute while categorising words. The design allowed participants to monitor time by checking a clock whenever they decided. Participants also completed a classic time-production task and several executive tasks assessing inhibition, updating and shifting processes. Our results confirm an age-related lack of accuracy in prospective memory performance, which seems to be related to a deficient strategic use of time monitoring. This could in turn be partially explained by age-related temporal deficits, as evidenced in the duration production task. These findings suggest that studies designed to investigate the age effect in TBPM tasks should consider the contribution of temporal mechanisms.

Distributed shared memory for roaming large volumes.

PubMed

Castanié, Laurent; Mion, Christophe; Cavin, Xavier; Lévy, Bruno

2006-01-01

We present a cluster-based volume rendering system for roaming very large volumes. This system allows to move a gigabyte-sized probe inside a total volume of several tens or hundreds of gigabytes in real-time. While the size of the probe is limited by the total amount of texture memory on the cluster, the size of the total data set has no theoretical limit. The cluster is used as a distributed graphics processing unit that both aggregates graphics power and graphics memory. A hardware-accelerated volume renderer runs in parallel on the cluster nodes and the final image compositing is implemented using a pipelined sort-last rendering algorithm. Meanwhile, volume bricking and volume paging allow efficient data caching. On each rendering node, a distributed hierarchical cache system implements a global software-based distributed shared memory on the cluster. In case of a cache miss, this system first checks page residency on the other cluster nodes instead of directly accessing local disks. Using two Gigabit Ethernet network interfaces per node, we accelerate data fetching by a factor of 4 compared to directly accessing local disks. The system also implements asynchronous disk access and texture loading, which makes it possible to overlap data loading, volume slicing and rendering for optimal volume roaming.

The dopamine D2/D3 receptor agonist quinpirole increases checking-like behaviour in an operant observing response task with uncertain reinforcement: A novel possible model of OCD?

PubMed Central

Eagle, Dawn M.; Noschang, Cristie; d’Angelo, Laure-Sophie Camilla; Noble, Christie A.; Day, Jacob O.; Dongelmans, Marie Louise; Theobald, David E.; Mar, Adam C.; Urcelay, Gonzalo P.; Morein-Zamir, Sharon; Robbins, Trevor W.

2014-01-01

Excessive checking is a common, debilitating symptom of obsessive-compulsive disorder (OCD). In an established rodent model of OCD checking behaviour, quinpirole (dopamine D2/3-receptor agonist) increased checking in open-field tests, indicating dopaminergic modulation of checking-like behaviours. We designed a novel operant paradigm for rats (observing response task (ORT)) to further examine cognitive processes underpinning checking behaviour and clarify how and why checking develops. We investigated i) how quinpirole increases checking, ii) dependence of these effects on D2/3 receptor function (following treatment with D2/3 receptor antagonist sulpiride) and iii) effects of reward uncertainty. In the ORT, rats pressed an ‘observing’ lever for information about the location of an ‘active’ lever that provided food reinforcement. High- and low-checkers (defined from baseline observing) received quinpirole (0.5 mg/kg, 10 treatments) or vehicle. Parametric task manipulations assessed observing/checking under increasing task demands relating to reinforcement uncertainty (variable response requirement and active-lever location switching). Treatment with sulpiride further probed the pharmacological basis of long-term behavioural changes. Quinpirole selectively increased checking, both functional observing lever presses (OLPs) and non-functional extra OLPs (EOLPs). The increase in OLPs and EOLPs was long-lasting, without further quinpirole administration. Quinpirole did not affect the immediate ability to use information from checking. Vehicle and quinpirole-treated rats (VEH and QNP respectively) were selectively sensitive to different forms of uncertainty. Sulpiride reduced non-functional EOLPs in QNP rats but had no effect on functional OLPs. These data have implications for treatment of compulsive checking in OCD, particularly for serotonin-reuptake-inhibitor treatment-refractory cases, where supplementation with dopamine receptor antagonists may be beneficial. PMID:24406720

A novel SMAC mimetic APG-1387 exhibits dual antitumor effect on HBV-positive hepatocellular carcinoma with high expression of cIAP2 by inducing apoptosis and enhancing innate anti-tumor immunity.

PubMed

Pan, Wentao; Luo, Qiuyun; Yan, Xianglei; Yuan, Luping; Yi, Hanjie; Zhang, Lin; Li, Baoxia; Zhang, Yuxin; Sun, Jian; Qiu, Miao-Zhen; Yang, Da-Jun

2018-04-18

Check point inhibitor anti-PD1 antibody produced some efficacy in Hepatocellular Carcinoma (HCC) patients previously treated with sorafenib. Unfortunately, HCC patients with hepatitis B virus (HBV) infection did not respond as well as uninfected patients. Previously, Second mitochondria-derived activator of caspases (SMAC) mimetics-the antagonist for inhibitor of apoptosis proteins (IAPs) can rapidly reduce serum hepatitis B virus DNA in animal model. APG-1387 is a novel SMAC-mimetic, small molecule inhibitor targeting inhibitor of apoptosis proteins (IAPs). In our study, firstly, we found that HCC patients with copy number alteration of cIAP1, cIAP2, and XIAP had a dismal prognosis. Then, we discovered that APG-1387 alone could induce apoptosis of PLC/PRF/5 which was HBV positive both in-vitro and in-vivo. Furthermore, we found that APG-1387 significantly up-regulated the expression of calreticulin and HLA-DR in PLC/PRF/5 via activating non-classic NF-κB pathway. Also, compared to vehicle group, APG-1387 increased NK cell counts by 5 folds in PLC/PRF/5 xenograft model. In-vitro, APG-1387 positively regulated T cells by reducing Treg differentiation and down-regulating PD1 expression in CD4 T cell. Moreover, APG-1387 had no impact on memory T cells. Consequently, our results suggest that APG1387 could be a good candidate to combine with anti-PD1 antibody treatment to overcome low responds of check point inhibitors in HBV positive HCC. Copyright © 2018 Elsevier Inc. All rights reserved.

Order-memory and association-memory.

PubMed

Caplan, Jeremy B

2015-09-01

Two highly studied memory functions are memory for associations (items presented in pairs, such as SALT-PEPPER) and memory for order (a list of items whose order matters, such as a telephone number). Order- and association-memory are at the root of many forms of behaviour, from wayfinding, to language, to remembering people's names. Most researchers have investigated memory for order separately from memory for associations. Exceptions to this, associative-chaining models build an ordered list from associations between pairs of items, quite literally understanding association- and order-memory together. Alternatively, positional-coding models have been used to explain order-memory as a completely distinct function from association-memory. Both classes of model have found empirical support and both have faced serious challenges. I argue that models that combine both associative chaining and positional coding are needed. One such hybrid model, which relies on brain-activity rhythms, is promising, but remains to be tested rigourously. I consider two relatively understudied memory behaviours that demand a combination of order- and association-information: memory for the order of items within associations (is it William James or James William?) and judgments of relative order (who left the party earlier, Hermann or William?). Findings from these underexplored procedures are already difficult to reconcile with existing association-memory and order-memory models. Further work with such intermediate experimental paradigms has the potential to provide powerful findings to constrain and guide models into the future, with the aim of explaining a large range of memory functions, encompassing both association- and order-memory. (c) 2015 APA, all rights reserved).

Effect of rat parental morphine exposure on passive avoidance memory and morphine conditioned place preference in male offspring.

PubMed

Akbarabadi, Ardeshir; Niknamfar, Saba; Vousooghi, Nasim; Sadat-Shirazi, Mitra-Sadat; Toolee, Heidar; Zarrindast, Mohammad-Reza

2018-02-01

Drug addiction is a chronic disorder resulted from complex interaction of genetic, environmental, and developmental factors. Epigenetic mechanisms play an important role in the development and maintenance of addiction and also memory formation in the brain. We have examined passive avoidance memory and morphine conditioned place preference (CPP) in the offspring of male and/or female rats with a history of adulthood morphine consumption. Adult male and female animals received chronic oral morphine for 21days and then were maintained drug free for 10days. After that, they were let to mate with either an abstinent or control rat. Male offspring's memory was evaluated by step through test. Besides, rewarding effects of morphine were checked with CCP paradigm. Offspring of abstinent animals showed significant memory impairment compared to the control group which was more prominent in the offspring of abstinent females. Conditioning results showed that administration of a high dose of morphine (10mg/kg) that could significantly induce CPP in control rats, was not able to induce similar results in the offspring of morphine abstinent parents; and CPP was much more prominent when it was induced in the offspring of morphine exposed females compared to the progeny of morphine exposed males. It is concluded that parental morphine consumption in adulthood even before mating has destructive effects on memory state of the male offspring and also leads to tolerance to the rewarding effects of morphine. These effects are greater when the morphine consumer parent is the female one. Copyright © 2017 Elsevier Inc. All rights reserved.

Proceedings of the Second NASA Formal Methods Symposium

NASA Technical Reports Server (NTRS)

Munoz, Cesar (Editor)

2010-01-01

This publication contains the proceedings of the Second NASA Formal Methods Symposium sponsored by the National Aeronautics and Space Administration and held in Washington D.C. April 13-15, 2010. Topics covered include: Decision Engines for Software Analysis using Satisfiability Modulo Theories Solvers; Verification and Validation of Flight-Critical Systems; Formal Methods at Intel -- An Overview; Automatic Review of Abstract State Machines by Meta Property Verification; Hardware-independent Proofs of Numerical Programs; Slice-based Formal Specification Measures -- Mapping Coupling and Cohesion Measures to Formal Z; How Formal Methods Impels Discovery: A Short History of an Air Traffic Management Project; A Machine-Checked Proof of A State-Space Construction Algorithm; Automated Assume-Guarantee Reasoning for Omega-Regular Systems and Specifications; Modeling Regular Replacement for String Constraint Solving; Using Integer Clocks to Verify the Timing-Sync Sensor Network Protocol; Can Regulatory Bodies Expect Efficient Help from Formal Methods?; Synthesis of Greedy Algorithms Using Dominance Relations; A New Method for Incremental Testing of Finite State Machines; Verification of Faulty Message Passing Systems with Continuous State Space in PVS; Phase Two Feasibility Study for Software Safety Requirements Analysis Using Model Checking; A Prototype Embedding of Bluespec System Verilog in the PVS Theorem Prover; SimCheck: An Expressive Type System for Simulink; Coverage Metrics for Requirements-Based Testing: Evaluation of Effectiveness; Software Model Checking of ARINC-653 Flight Code with MCP; Evaluation of a Guideline by Formal Modelling of Cruise Control System in Event-B; Formal Verification of Large Software Systems; Symbolic Computation of Strongly Connected Components Using Saturation; Towards the Formal Verification of a Distributed Real-Time Automotive System; Slicing AADL Specifications for Model Checking; Model Checking with Edge-valued Decision Diagrams; and Data-flow based Model Analysis.

A New Conceptualization of Human Visual Sensory-Memory.

PubMed

Öğmen, Haluk; Herzog, Michael H

2016-01-01

Memory is an essential component of cognition and disorders of memory have significant individual and societal costs. The Atkinson-Shiffrin "modal model" forms the foundation of our understanding of human memory. It consists of three stores: Sensory Memory (SM), whose visual component is called iconic memory, Short-Term Memory (STM; also called working memory, WM), and Long-Term Memory (LTM). Since its inception, shortcomings of all three components of the modal model have been identified. While the theories of STM and LTM underwent significant modifications to address these shortcomings, models of the iconic memory remained largely unchanged: A high capacity but rapidly decaying store whose contents are encoded in retinotopic coordinates, i.e., according to how the stimulus is projected on the retina. The fundamental shortcoming of iconic memory models is that, because contents are encoded in retinotopic coordinates, the iconic memory cannot hold any useful information under normal viewing conditions when objects or the subject are in motion. Hence, half-century after its formulation, it remains an unresolved problem whether and how the first stage of the modal model serves any useful function and how subsequent stages of the modal model receive inputs from the environment. Here, we propose a new conceptualization of human visual sensory memory by introducing an additional component whose reference-frame consists of motion-grouping based coordinates rather than retinotopic coordinates. We review data supporting this new model and discuss how it offers solutions to the paradoxes of the traditional model of sensory memory.

Proceedings of the First NASA Formal Methods Symposium

NASA Technical Reports Server (NTRS)

Denney, Ewen (Editor); Giannakopoulou, Dimitra (Editor); Pasareanu, Corina S. (Editor)

2009-01-01

Topics covered include: Model Checking - My 27-Year Quest to Overcome the State Explosion Problem; Applying Formal Methods to NASA Projects: Transition from Research to Practice; TLA+: Whence, Wherefore, and Whither; Formal Methods Applications in Air Transportation; Theorem Proving in Intel Hardware Design; Building a Formal Model of a Human-Interactive System: Insights into the Integration of Formal Methods and Human Factors Engineering; Model Checking for Autonomic Systems Specified with ASSL; A Game-Theoretic Approach to Branching Time Abstract-Check-Refine Process; Software Model Checking Without Source Code; Generalized Abstract Symbolic Summaries; A Comparative Study of Randomized Constraint Solvers for Random-Symbolic Testing; Component-Oriented Behavior Extraction for Autonomic System Design; Automated Verification of Design Patterns with LePUS3; A Module Language for Typing by Contracts; From Goal-Oriented Requirements to Event-B Specifications; Introduction of Virtualization Technology to Multi-Process Model Checking; Comparing Techniques for Certified Static Analysis; Towards a Framework for Generating Tests to Satisfy Complex Code Coverage in Java Pathfinder; jFuzz: A Concolic Whitebox Fuzzer for Java; Machine-Checkable Timed CSP; Stochastic Formal Correctness of Numerical Algorithms; Deductive Verification of Cryptographic Software; Coloured Petri Net Refinement Specification and Correctness Proof with Coq; Modeling Guidelines for Code Generation in the Railway Signaling Context; Tactical Synthesis Of Efficient Global Search Algorithms; Towards Co-Engineering Communicating Autonomous Cyber-Physical Systems; and Formal Methods for Automated Diagnosis of Autosub 6000.

Model analysis of check dam impacts on long-term sediment and water budgets in southeast Arizona, USA

USGS Publications Warehouse

Norman, Laura M.; Niraula, Rewati

2016-01-01

The objective of this study was to evaluate the effect of check dam infrastructure on soil and water conservation at the catchment scale using the Soil and Water Assessment Tool (SWAT). This paired watershed study includes a watershed treated with over 2000 check dams and a Control watershed which has none, in the West Turkey Creek watershed, Southeast Arizona, USA. SWAT was calibrated for streamflow using discharge documented during the summer of 2013 at the Control site. Model results depict the necessity to eliminate lateral flow from SWAT models of aridland environments, the urgency to standardize geospatial soils data, and the care for which modelers must document altering parameters when presenting findings. Performance was assessed using the percent bias (PBIAS), with values of ±2.34%. The calibrated model was then used to examine the impacts of check dams at the Treated watershed. Approximately 630 tons of sediment is estimated to be stored behind check dams in the Treated watershed over the 3-year simulation, increasing water quality for fish habitat. A minimum precipitation event of 15 mm was necessary to instigate the detachment of soil, sediments, or rock from the study area, which occurred 2% of the time. The resulting watershed model is useful as a predictive framework and decision-support tool to consider long-term impacts of restoration and potential for future restoration.

A simplified computational memory model from information processing.

PubMed

Zhang, Lanhua; Zhang, Dongsheng; Deng, Yuqin; Ding, Xiaoqian; Wang, Yan; Tang, Yiyuan; Sun, Baoliang

2016-11-23

This paper is intended to propose a computational model for memory from the view of information processing. The model, called simplified memory information retrieval network (SMIRN), is a bi-modular hierarchical functional memory network by abstracting memory function and simulating memory information processing. At first meta-memory is defined to express the neuron or brain cortices based on the biology and graph theories, and we develop an intra-modular network with the modeling algorithm by mapping the node and edge, and then the bi-modular network is delineated with intra-modular and inter-modular. At last a polynomial retrieval algorithm is introduced. In this paper we simulate the memory phenomena and functions of memorization and strengthening by information processing algorithms. The theoretical analysis and the simulation results show that the model is in accordance with the memory phenomena from information processing view.

A New Conceptualization of Human Visual Sensory-Memory

PubMed Central

Öğmen, Haluk; Herzog, Michael H.

2016-01-01

Memory is an essential component of cognition and disorders of memory have significant individual and societal costs. The Atkinson–Shiffrin “modal model” forms the foundation of our understanding of human memory. It consists of three stores: Sensory Memory (SM), whose visual component is called iconic memory, Short-Term Memory (STM; also called working memory, WM), and Long-Term Memory (LTM). Since its inception, shortcomings of all three components of the modal model have been identified. While the theories of STM and LTM underwent significant modifications to address these shortcomings, models of the iconic memory remained largely unchanged: A high capacity but rapidly decaying store whose contents are encoded in retinotopic coordinates, i.e., according to how the stimulus is projected on the retina. The fundamental shortcoming of iconic memory models is that, because contents are encoded in retinotopic coordinates, the iconic memory cannot hold any useful information under normal viewing conditions when objects or the subject are in motion. Hence, half-century after its formulation, it remains an unresolved problem whether and how the first stage of the modal model serves any useful function and how subsequent stages of the modal model receive inputs from the environment. Here, we propose a new conceptualization of human visual sensory memory by introducing an additional component whose reference-frame consists of motion-grouping based coordinates rather than retinotopic coordinates. We review data supporting this new model and discuss how it offers solutions to the paradoxes of the traditional model of sensory memory. PMID:27375519

A Temporal Ratio Model of Memory

ERIC Educational Resources Information Center

Brown, Gordon D. A.; Neath, Ian; Chater, Nick

2007-01-01

A model of memory retrieval is described. The model embodies four main claims: (a) temporal memory--traces of items are represented in memory partly in terms of their temporal distance from the present; (b) scale-similarity--similar mechanisms govern retrieval from memory over many different timescales; (c) local distinctiveness--performance on a…

The reduction of adult neurogenesis in depression impairs the retrieval of new as well as remote episodic memory

PubMed Central

Fang, Jing; Demic, Selver; Cheng, Sen

2018-01-01

Major depressive disorder (MDD) is associated with an impairment of episodic memory, but the mechanisms underlying this deficit remain unclear. Animal models of MDD find impaired adult neurogenesis (AN) in the dentate gyrus (DG), and AN in DG has been suggested to play a critical role in reducing the interference between overlapping memories through pattern separation. Here, we study the effect of reduced AN in MDD on the accuracy of episodic memory using computational modeling. We focus on how memory is affected when periods with a normal rate of AN (asymptomatic states) alternate with periods with a low rate (depressive episodes), which has never been studied before. Also, unlike previous models of adult neurogenesis, which consider memories as static patterns, we model episodic memory as sequences of neural activity patterns. In our model, AN adds additional random components to the memory patterns, which results in the decorrelation of similar patterns. Consistent with previous studies, higher rates of AN lead to higher memory accuracy in our model, which implies that memories stored in the depressive state are impaired. Intriguingly, our model makes the novel prediction that memories stored in an earlier asymptomatic state are also impaired by a later depressive episode. This retrograde effect exacerbates with increased duration of the depressive episode. Finally, pattern separation at the sensory processing stage does not improve, but rather worsens, the accuracy of episodic memory retrieval, suggesting an explanation for why AN is found in brain areas serving memory rather than sensory function. In conclusion, while cognitive retrieval biases might contribute to episodic memory deficits in MDD, our model suggests a mechanistic explanation that affects all episodic memories, regardless of emotional relevance. PMID:29879169

The reduction of adult neurogenesis in depression impairs the retrieval of new as well as remote episodic memory.

PubMed

Fang, Jing; Demic, Selver; Cheng, Sen

2018-01-01

Major depressive disorder (MDD) is associated with an impairment of episodic memory, but the mechanisms underlying this deficit remain unclear. Animal models of MDD find impaired adult neurogenesis (AN) in the dentate gyrus (DG), and AN in DG has been suggested to play a critical role in reducing the interference between overlapping memories through pattern separation. Here, we study the effect of reduced AN in MDD on the accuracy of episodic memory using computational modeling. We focus on how memory is affected when periods with a normal rate of AN (asymptomatic states) alternate with periods with a low rate (depressive episodes), which has never been studied before. Also, unlike previous models of adult neurogenesis, which consider memories as static patterns, we model episodic memory as sequences of neural activity patterns. In our model, AN adds additional random components to the memory patterns, which results in the decorrelation of similar patterns. Consistent with previous studies, higher rates of AN lead to higher memory accuracy in our model, which implies that memories stored in the depressive state are impaired. Intriguingly, our model makes the novel prediction that memories stored in an earlier asymptomatic state are also impaired by a later depressive episode. This retrograde effect exacerbates with increased duration of the depressive episode. Finally, pattern separation at the sensory processing stage does not improve, but rather worsens, the accuracy of episodic memory retrieval, suggesting an explanation for why AN is found in brain areas serving memory rather than sensory function. In conclusion, while cognitive retrieval biases might contribute to episodic memory deficits in MDD, our model suggests a mechanistic explanation that affects all episodic memories, regardless of emotional relevance.

New Results in Software Model Checking and Analysis

NASA Technical Reports Server (NTRS)

Pasareanu, Corina S.

2010-01-01

This introductory article surveys new techniques, supported by automated tools, for the analysis of software to ensure reliability and safety. Special focus is on model checking techniques. The article also introduces the five papers that are enclosed in this special journal volume.

Contrasting single and multi-component working-memory systems in dual tasking.

PubMed

Nijboer, Menno; Borst, Jelmer; van Rijn, Hedderik; Taatgen, Niels

2016-05-01

Working memory can be a major source of interference in dual tasking. However, there is no consensus on whether this interference is the result of a single working memory bottleneck, or of interactions between different working memory components that together form a complete working-memory system. We report a behavioral and an fMRI dataset in which working memory requirements are manipulated during multitasking. We show that a computational cognitive model that assumes a distributed version of working memory accounts for both behavioral and neuroimaging data better than a model that takes a more centralized approach. The model's working memory consists of an attentional focus, declarative memory, and a subvocalized rehearsal mechanism. Thus, the data and model favor an account where working memory interference in dual tasking is the result of interactions between different resources that together form a working-memory system. Copyright © 2016 Elsevier Inc. All rights reserved.

Error correcting code with chip kill capability and power saving enhancement

DOEpatents

Gara, Alan G [Mount Kisco, NY; Chen, Dong [Croton On Husdon, NY; Coteus, Paul W [Yorktown Heights, NY; Flynn, William T [Rochester, MN; Marcella, James A [Rochester, MN; Takken, Todd [Brewster, NY; Trager, Barry M [Yorktown Heights, NY; Winograd, Shmuel [Scarsdale, NY

2011-08-30

A method and system are disclosed for detecting memory chip failure in a computer memory system. The method comprises the steps of accessing user data from a set of user data chips, and testing the user data for errors using data from a set of system data chips. This testing is done by generating a sequence of check symbols from the user data, grouping the user data into a sequence of data symbols, and computing a specified sequence of syndromes. If all the syndromes are zero, the user data has no errors. If one of the syndromes is non-zero, then a set of discriminator expressions are computed, and used to determine whether a single or double symbol error has occurred. In the preferred embodiment, less than two full system data chips are used for testing and correcting the user data.

Reformulation of time-convolutionless mode-coupling theory near the glass transition

NASA Astrophysics Data System (ADS)

Tokuyama, Michio

2017-10-01

The time-convolutionless mode-coupling theory (TMCT) recently proposed is reformulated under the condition that one of two approximations, which have been used to formulate the original TMCT in addition to the MCT approximations done on a derivation of nonlinear memory function in terms of the intermediate-scattering function, is not employed because it causes unphysical results for intermediate times. The improved TMCT equation is then derived consistently under another approximation. It is first checked that the ergodic to non-ergodic transition obtained by a new equation is exactly the same as that obtained by an old one because the long-time dynamics of both equations coincides with each other. However, it is emphasized that a difference between them appears in the intermediate-time dynamics of physical quantities. Such a difference is explored numerically in the dynamics of a non-Gaussian parameter by employing the Percus-Yevick static structure factor to calculate the nonlinear memory function.

Query Language for Location-Based Services: A Model Checking Approach

NASA Astrophysics Data System (ADS)

Hoareau, Christian; Satoh, Ichiro

We present a model checking approach to the rationale, implementation, and applications of a query language for location-based services. Such query mechanisms are necessary so that users, objects, and/or services can effectively benefit from the location-awareness of their surrounding environment. The underlying data model is founded on a symbolic model of space organized in a tree structure. Once extended to a semantic model for modal logic, we regard location query processing as a model checking problem, and thus define location queries as hybrid logicbased formulas. Our approach is unique to existing research because it explores the connection between location models and query processing in ubiquitous computing systems, relies on a sound theoretical basis, and provides modal logic-based query mechanisms for expressive searches over a decentralized data structure. A prototype implementation is also presented and will be discussed.

A simplified computational memory model from information processing

PubMed Central

Zhang, Lanhua; Zhang, Dongsheng; Deng, Yuqin; Ding, Xiaoqian; Wang, Yan; Tang, Yiyuan; Sun, Baoliang

2016-01-01

This paper is intended to propose a computational model for memory from the view of information processing. The model, called simplified memory information retrieval network (SMIRN), is a bi-modular hierarchical functional memory network by abstracting memory function and simulating memory information processing. At first meta-memory is defined to express the neuron or brain cortices based on the biology and graph theories, and we develop an intra-modular network with the modeling algorithm by mapping the node and edge, and then the bi-modular network is delineated with intra-modular and inter-modular. At last a polynomial retrieval algorithm is introduced. In this paper we simulate the memory phenomena and functions of memorization and strengthening by information processing algorithms. The theoretical analysis and the simulation results show that the model is in accordance with the memory phenomena from information processing view. PMID:27876847

Abstraction Techniques for Parameterized Verification

DTIC Science & Technology

2006-11-01

approach for applying model checking to unbounded systems is to extract finite state models from them using conservative abstraction techniques. Prop...36 2.5.1 Multiple Reference Processes . . . . . . . . . . . . . . . . . . . 36 2.5.2 Adding Monitor Processes...model checking to complex pieces of code like device drivers depends on the use of abstraction methods. An abstraction method extracts a small finite

The Automation of Nowcast Model Assessment Processes

DTIC Science & Technology

2016-09-01

that will automate real-time WRE-N model simulations, collect and quality control check weather observations for assimilation and verification, and...domains centered near White Sands Missile Range, New Mexico, where the Meteorological Sensor Array (MSA) will be located. The MSA will provide...observations and performing quality -control checks for the pre-forecast data assimilation period. 2. Run the WRE-N model to generate model forecast data

Effects of Working Memory Capacity and Domain Knowledge on Recall for Grocery Prices.

PubMed

Bermingham, Douglas; Gardner, Michael K; Woltz, Dan J

2016-01-01

Hambrick and Engle (2002) proposed 3 models of how domain knowledge and working memory capacity may work together to influence episodic memory: a "rich-get-richer" model, a "building blocks" model, and a "compensatory" model. Their results supported the rich-get-richer model, although later work by Hambrick and Oswald (2005) found support for a building blocks model. We investigated the effects of domain knowledge and working memory on recall of studied grocery prices. Working memory was measured with 3 simple span tasks. A contrast of realistic versus fictitious foods in the episodic memory task served as our manipulation of domain knowledge, because participants could not have domain knowledge of fictitious food prices. There was a strong effect for domain knowledge (realistic food-price pairs were easier to remember) and a moderate effect for working memory capacity (higher working memory capacity produced better recall). Furthermore, the interaction between domain knowledge and working memory produced a small but significant interaction in 1 measure of price recall. This supported the compensatory model and stands in contrast to previous research.

Elements of episodic-like memory in animal models.

PubMed

Crystal, Jonathon D

2009-03-01

Representations of unique events from one's past constitute the content of episodic memories. A number of studies with non-human animals have revealed that animals remember specific episodes from their past (referred to as episodic-like memory). The development of animal models of memory holds enormous potential for gaining insight into the biological bases of human memory. Specifically, given the extensive knowledge of the rodent brain, the development of rodent models of episodic memory would open new opportunities to explore the neuroanatomical, neurochemical, neurophysiological, and molecular mechanisms of memory. Development of such animal models holds enormous potential for studying functional changes in episodic memory in animal models of Alzheimer's disease, amnesia, and other human memory pathologies. This article reviews several approaches that have been used to assess episodic-like memory in animals. The approaches reviewed include the discrimination of what, where, and when in a radial arm maze, dissociation of recollection and familiarity, object recognition, binding, unexpected questions, and anticipation of a reproductive state. The diversity of approaches may promote the development of converging lines of evidence on the difficult problem of assessing episodic-like memory in animals.

Temporal Precedence Checking for Switched Models and its Application to a Parallel Landing Protocol

NASA Technical Reports Server (NTRS)

Duggirala, Parasara Sridhar; Wang, Le; Mitra, Sayan; Viswanathan, Mahesh; Munoz, Cesar A.

2014-01-01

This paper presents an algorithm for checking temporal precedence properties of nonlinear switched systems. This class of properties subsume bounded safety and capture requirements about visiting a sequence of predicates within given time intervals. The algorithm handles nonlinear predicates that arise from dynamics-based predictions used in alerting protocols for state-of-the-art transportation systems. It is sound and complete for nonlinear switch systems that robustly satisfy the given property. The algorithm is implemented in the Compare Execute Check Engine (C2E2) using validated simulations. As a case study, a simplified model of an alerting system for closely spaced parallel runways is considered. The proposed approach is applied to this model to check safety properties of the alerting logic for different operating conditions such as initial velocities, bank angles, aircraft longitudinal separation, and runway separation.

Modeling individual differences in working memory performance: a source activation account

PubMed Central

Daily, Larry Z.; Lovett, Marsha C.; Reder, Lynne M.

2008-01-01

Working memory resources are needed for processing and maintenance of information during cognitive tasks. Many models have been developed to capture the effects of limited working memory resources on performance. However, most of these models do not account for the finding that different individuals show different sensitivities to working memory demands, and none of the models predicts individual subjects' patterns of performance. We propose a computational model that accounts for differences in working memory capacity in terms of a quantity called source activation, which is used to maintain goal-relevant information in an available state. We apply this model to capture the working memory effects of individual subjects at a fine level of detail across two experiments. This, we argue, strengthens the interpretation of source activation as working memory capacity. PMID:19079561

The method of a joint intraday security check system based on cloud computing

NASA Astrophysics Data System (ADS)

Dong, Wei; Feng, Changyou; Zhou, Caiqi; Cai, Zhi; Dan, Xu; Dai, Sai; Zhang, Chuancheng

2017-01-01

The intraday security check is the core application in the dispatching control system. The existing security check calculation only uses the dispatch center’s local model and data as the functional margin. This paper introduces the design of all-grid intraday joint security check system based on cloud computing and its implementation. To reduce the effect of subarea bad data on the all-grid security check, a new power flow algorithm basing on comparison and adjustment with inter-provincial tie-line plan is presented. And the numerical example illustrated the effectiveness and feasibility of the proposed method.

76 FR 35344 - Airworthiness Directives; Costruzioni Aeronautiche Tecnam srl Model P2006T Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-17

... retraction/extension ground checks performed on the P2006T, a loose Seeger ring was found on the nose landing... specified products. The MCAI states: During Landing Gear retraction/extension ground checks performed on the... airworthiness information (MCAI) states: During Landing Gear retraction/extension ground checks performed on the...

An interactive NASTRAN preprocessor. [graphic display of undeformed structure using CDC 6000 series computer

NASA Technical Reports Server (NTRS)

Smith, W. W.

1973-01-01

A Langley Research Center version of NASTRAN Level 15.1.0 designed to provide the analyst with an added tool for debugging massive NASTRAN input data is described. The program checks all NASTRAN input data cards and displays on a CRT the graphic representation of the undeformed structure. In addition, the program permits the display and alteration of input data and allows reexecution without physically resubmitting the job. Core requirements on the CDC 6000 computer are approximately 77,000 octal words of central memory.

Structural Integrity Recording System (SIRS) for U.S. Army AH-1G helicopters

DTIC Science & Technology

1981-03-01

location was detected during the diagnostic check of the recorder’s data storage memory. BATTERY Denotes that the recorder’s battery power supply is...Condition- ing Board 074032D30019 50.6592 19,740 Power Supply CS/TlS/165/x 16.6667 60,000 Filter RF6125 0.0560 17,857,143 *Termination Assembly 074032C30011...whatsoever; and the fact that the Government may have formulated, furnished, or in any way supplied the said drawings, specifications, or other date is

Decoding memory features from hippocampal spiking activities using sparse classification models.

PubMed

Dong Song; Hampson, Robert E; Robinson, Brian S; Marmarelis, Vasilis Z; Deadwyler, Sam A; Berger, Theodore W

2016-08-01

To understand how memory information is encoded in the hippocampus, we build classification models to decode memory features from hippocampal CA3 and CA1 spatio-temporal patterns of spikes recorded from epilepsy patients performing a memory-dependent delayed match-to-sample task. The classification model consists of a set of B-spline basis functions for extracting memory features from the spike patterns, and a sparse logistic regression classifier for generating binary categorical output of memory features. Results show that classification models can extract significant amount of memory information with respects to types of memory tasks and categories of sample images used in the task, despite the high level of variability in prediction accuracy due to the small sample size. These results support the hypothesis that memories are encoded in the hippocampal activities and have important implication to the development of hippocampal memory prostheses.

Time Constraints and Resource Sharing in Adults' Working Memory Spans

ERIC Educational Resources Information Center

Barrouillet, Pierre; Bernardin, Sophie; Camos, Valerie

2004-01-01

This article presents a new model that accounts for working memory spans in adults, the time-based resource-sharing model. The model assumes that both components (i.e., processing and maintenance) of the main working memory tasks require attention and that memory traces decay as soon as attention is switched away. Because memory retrievals are…

Categorical Working Memory Representations are used in Delayed Estimation of Continuous Colors

PubMed Central

Hardman, Kyle O; Vergauwe, Evie; Ricker, Timothy J

2016-01-01

In the last decade, major strides have been made in understanding visual working memory through mathematical modeling of color production responses. In the delayed color estimation task (Wilken & Ma, 2004), participants are given a set of colored squares to remember and a few seconds later asked to reproduce those colors by clicking on a color wheel. The degree of error in these responses is characterized with mathematical models that estimate working memory precision and the proportion of items remembered by participants. A standard mathematical model of color memory assumes that items maintained in memory are remembered through memory for precise details about the particular studied shade of color. We contend that this model is incomplete in its present form because no mechanism is provided for remembering the coarse category of a studied color. In the present work we remedy this omission and present a model of visual working memory that includes both continuous and categorical memory representations. In two experiments we show that our new model outperforms this standard modeling approach, which demonstrates that categorical representations should be accounted for by mathematical models of visual working memory. PMID:27797548

Categorical working memory representations are used in delayed estimation of continuous colors.

PubMed

Hardman, Kyle O; Vergauwe, Evie; Ricker, Timothy J

2017-01-01

In the last decade, major strides have been made in understanding visual working memory through mathematical modeling of color production responses. In the delayed color estimation task (Wilken & Ma, 2004), participants are given a set of colored squares to remember, and a few seconds later asked to reproduce those colors by clicking on a color wheel. The degree of error in these responses is characterized with mathematical models that estimate working memory precision and the proportion of items remembered by participants. A standard mathematical model of color memory assumes that items maintained in memory are remembered through memory for precise details about the particular studied shade of color. We contend that this model is incomplete in its present form because no mechanism is provided for remembering the coarse category of a studied color. In the present work, we remedy this omission and present a model of visual working memory that includes both continuous and categorical memory representations. In 2 experiments, we show that our new model outperforms this standard modeling approach, which demonstrates that categorical representations should be accounted for by mathematical models of visual working memory. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Sediment trapping efficiency of adjustable check dam in laboratory and field experiment

NASA Astrophysics Data System (ADS)

Wang, Chiang; Chen, Su-Chin; Lu, Sheng-Jui

2014-05-01

Check dam has been constructed at mountain area to block debris flow, but has been filled after several events and lose its function of trapping. For the reason, the main facilities of our research is the adjustable steel slit check dam, which with the advantages of fast building, easy to remove or adjust it function. When we can remove transverse beams to drain sediments off and keep the channel continuity. We constructed adjustable steel slit check dam on the Landow torrent, Huisun Experiment Forest station as the prototype to compare with model in laboratory. In laboratory experiments, the Froude number similarity was used to design the dam model. The main comparisons focused on types of sediment trapping and removing, sediment discharge, and trapping rate of slit check dam. In different types of removing transverse beam showed different kind of sediment removal and differences on rate of sediment removing, removing rate, and particle size distribution. The sediment discharge in check dam with beams is about 40%~80% of check dam without beams. Furthermore, the spacing of beams is considerable factor to the sediment discharge. In field experiment, this research uses time-lapse photography to record the adjustable steel slit check dam on the Landow torrent. The typhoon Soulik made rainfall amounts of 600 mm in eight hours and induced debris flow in Landow torrent. Image data of time-lapse photography demonstrated that after several sediment transport event the adjustable steel slit check dam was buried by debris flow. The result of lab and field experiments: (1)Adjustable check dam could trap boulders and stop woody debris flow and flush out fine sediment to supply the need of downstream river. (2)The efficiency of sediment trapping in adjustable check dam with transverse beams was significantly improved. (3)The check dam without transverse beams can remove the sediment and keep the ecosystem continuity.

The dopamine D2/D3 receptor agonist quinpirole increases checking-like behaviour in an operant observing response task with uncertain reinforcement: a novel possible model of OCD.

PubMed

Eagle, Dawn M; Noschang, Cristie; d'Angelo, Laure-Sophie Camilla; Noble, Christie A; Day, Jacob O; Dongelmans, Marie Louise; Theobald, David E; Mar, Adam C; Urcelay, Gonzalo P; Morein-Zamir, Sharon; Robbins, Trevor W

2014-05-01

Excessive checking is a common, debilitating symptom of obsessive-compulsive disorder (OCD). In an established rodent model of OCD checking behaviour, quinpirole (dopamine D2/3-receptor agonist) increased checking in open-field tests, indicating dopaminergic modulation of checking-like behaviours. We designed a novel operant paradigm for rats (observing response task (ORT)) to further examine cognitive processes underpinning checking behaviour and clarify how and why checking develops. We investigated i) how quinpirole increases checking, ii) dependence of these effects on D2/3 receptor function (following treatment with D2/3 receptor antagonist sulpiride) and iii) effects of reward uncertainty. In the ORT, rats pressed an 'observing' lever for information about the location of an 'active' lever that provided food reinforcement. High- and low-checkers (defined from baseline observing) received quinpirole (0.5mg/kg, 10 treatments) or vehicle. Parametric task manipulations assessed observing/checking under increasing task demands relating to reinforcement uncertainty (variable response requirement and active-lever location switching). Treatment with sulpiride further probed the pharmacological basis of long-term behavioural changes. Quinpirole selectively increased checking, both functional observing lever presses (OLPs) and non-functional extra OLPs (EOLPs). The increase in OLPs and EOLPs was long-lasting, without further quinpirole administration. Quinpirole did not affect the immediate ability to use information from checking. Vehicle and quinpirole-treated rats (VEH and QNP respectively) were selectively sensitive to different forms of uncertainty. Sulpiride reduced non-functional EOLPs in QNP rats but had no effect on functional OLPs. These data have implications for treatment of compulsive checking in OCD, particularly for serotonin-reuptake-inhibitor treatment-refractory cases, where supplementation with dopamine receptor antagonists may be beneficial. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Cometary spliting - a source for the Jupiter family?

NASA Astrophysics Data System (ADS)

Pittich, E. M.; Rickman, H.

1994-01-01

The quest for the origin of the Jupiter family of comets includes investigating the possibility that a large fraction of this population originates from past splitting events. In particular, one suggested scenario, albeit less attractive on physical grounds, maintains that a giant comet breakup is a major source of short-period comets. By simulating such events and integrating the motions of the fictitious fragments in an accurate solar system model for the typical lifetime of Jupiter family comets, it is possible to check whether the outcome may or may not be compatible with the observed orbital distribution. In this paper we present such integrations for a few typical progenitor orbits and analyze the ensuing thermalization process with particular attention to the Tisserand parameters. It is found that the sets of fragments lose their memory of a common origin very rapidly so that, in general terms, it is difficult to use the random appearance of the observed orbital distribution as evidence against the giant comet splitting hypothesis.

Identification of task demands and usability issues in police use of mobile computing terminals.

PubMed

Zahabi, Maryam; Kaber, David

2018-01-01

Crash reports from various states in the U.S. have shown high numbers of emergency vehicle crashes, especially in law enforcement situations. This study identified the perceived importance and frequency of police mobile computing terminal (MCT) tasks, quantified the demands of different tasks using a cognitive performance modeling methodology, identified usability violations of current MCT interface designs, and formulated design recommendations for an enhanced interface. Results revealed that "access call notes", "plate number check" and "find location on map" are the most important and frequently performed tasks for officers. "Reading plate information" was also found to be the most visually and cognitively demanding task-method. Usability principles of "using simple and natural dialog" and "minimizing user memory load" were violated by the current MCT interface design. The enhanced design showed potential for reducing cognitive demands and task completion time. Findings should be further validated using a driving simulation study. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sleep on your memory traces: How sleep effects can be explained by Act-In, a functional memory model.

PubMed

Cherdieu, Mélaine; Versace, Rémy; Rey, Amandine E; Vallet, Guillaume T; Mazza, Stéphanie

2018-06-01

Numerous studies have explored the effect of sleep on memory. It is well known that a period of sleep, compared to a similar period of wakefulness, protects memories from interference, improves performance, and might also reorganize memory traces in a way that encourages creativity and rule extraction. It is assumed that these benefits come from the reactivation of brain networks, mainly involving the hippocampal structure, as well as from their synchronization with neocortical networks during sleep, thereby underpinning sleep-dependent memory consolidation and reorganization. However, this memory reorganization is difficult to explain within classical memory models. The present paper aims to describe whether the influence of sleep on memory could be explained using a multiple trace memory model that is consistent with the concept of embodied cognition: the Act-In (activation-integration) memory model. We propose an original approach to the results observed in sleep research on the basis of two simple mechanisms, namely activation and integration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Attempting to model dissociations of memory.

PubMed

Reber, Paul J.

2002-05-01

Kinder and Shanks report simulations aimed at describing a single-system model of the dissociation between declarative and non-declarative memory. This model attempts to capture both Artificial Grammar Learning (AGL) and recognition memory with a single underlying representation. However, the model fails to reflect an essential feature of recognition memory - that it occurs after a single exposure - and the simulations may instead describe a potentially interesting property of over-training non-declarative memory.

Models for Total-Dose Radiation Effects in Non-Volatile Memory

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

Campbell, Philip Montgomery; Wix, Steven D.

The objective of this work is to develop models to predict radiation effects in non- volatile memory: flash memory and ferroelectric RAM. In flash memory experiments have found that the internal high-voltage generators (charge pumps) are the most sensitive to radiation damage. Models are presented for radiation effects in charge pumps that demonstrate the experimental results. Floating gate models are developed for the memory cell in two types of flash memory devices by Intel and Samsung. These models utilize Fowler-Nordheim tunneling and hot electron injection to charge and erase the floating gate. Erase times are calculated from the models andmore » compared with experimental results for different radiation doses. FRAM is less sensitive to radiation than flash memory, but measurements show that above 100 Krad FRAM suffers from a large increase in leakage current. A model for this effect is developed which compares closely with the measurements.« less

Development of the Ubiquitous Spaced Retrieval-Based Memory Advancement and Rehabilitation Training Program

PubMed Central

Han, Ji Won; Oh, Kyusoo; Yoo, Sooyoung; Kim, Eunhye; Ahn, Ki-Hwan; Son, Yeon-Joo; Kim, Tae Hui; Chi, Yeon Kyung

2014-01-01

Objective The Ubiquitous Spaced Retrieval-based Memory Advancement and Rehabilitation Training (USMART) program was developed by transforming the spaced retrieval-based memory training which consisted of 24 face-to-face sessions into a self-administered program with an iPAD app. The objective of this study was to evaluate the feasibility and efficacy of USMART in elderly subjects with mild cognitive impairment (MCI). Methods Feasibility was evaluated by checking the satisfaction of the participants with a 5-point Likert scale. The efficacy of the program on cognitive functions was evaluated by the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Assessment Battery before and after USMART. Results Among the 10 participants, 7 completed both pre- and post-USMART assessments. The overall satisfaction score was 8.0±1.0 out of 10. The mean Word List Memory Test (WLMT) scores significantly increased after USMART training after adjusting for age, educational levels, baseline Mini-Mental Status Examination scores, and the number of training sessions (pre-USMART, 16.0±4.1; post-USMART, 17.9±4.5; p=0.014, RM-ANOVA). The magnitude of the improvements in the WLMT scores significantly correlated with the number of training sessions during 4 weeks (r=0.793; p=0.033). Conclusion USMART was effective in improving memory and was well tolerated by most participants with MCI, suggesting that it may be a convenient and cost-effective alternative for the cognitive rehabilitation of elderly subjects with cognitive impairments. Further studies with large numbers of participants are necessary to examine the relationship between the number of training sessions and the improvements in memory function. PMID:24605124

Implications of the Declarative/Procedural Model for Improving Second Language Learning: The Role of Memory Enhancement Techniques

ERIC Educational Resources Information Center

Ullman, Michael T.; Lovelett, Jarrett T.

2018-01-01

The declarative/procedural (DP) model posits that the learning, storage, and use of language critically depend on two learning and memory systems in the brain: declarative memory and procedural memory. Thus, on the basis of independent research on the memory systems, the model can generate specific and often novel predictions for language. Till…

Reliability of Memories Protected by Multibit Error Correction Codes Against MBUs

NASA Astrophysics Data System (ADS)

Ming, Zhu; Yi, Xiao Li; Chang, Liu; Wei, Zhang Jian

2011-02-01

As technology scales, more and more memory cells can be placed in a die. Therefore, the probability that a single event induces multiple bit upsets (MBUs) in adjacent memory cells gets greater. Generally, multibit error correction codes (MECCs) are effective approaches to mitigate MBUs in memories. In order to evaluate the robustness of protected memories, reliability models have been widely studied nowadays. Instead of irradiation experiments, the models can be used to quickly evaluate the reliability of memories in the early design. To build an accurate model, some situations should be considered. Firstly, when MBUs are presented in memories, the errors induced by several events may overlap each other, which is more frequent than single event upset (SEU) case. Furthermore, radiation experiments show that the probability of MBUs strongly depends on angles of the radiation event. However, reliability models which consider the overlap of multiple bit errors and angles of radiation event have not been proposed in the present literature. In this paper, a more accurate model of memories with MECCs is presented. Both the overlap of multiple bit errors and angles of event are considered in the model, which produces a more precise analysis in the calculation of mean time to failure (MTTF) for memory systems under MBUs. In addition, memories with scrubbing and nonscrubbing are analyzed in the proposed model. Finally, we evaluate the reliability of memories under MBUs in Matlab. The simulation results verify the validity of the proposed model.

Short-Term Memory and Aphasia: From Theory to Treatment.

PubMed

Minkina, Irene; Rosenberg, Samantha; Kalinyak-Fliszar, Michelene; Martin, Nadine

2017-02-01

This article reviews existing research on the interactions between verbal short-term memory and language processing impairments in aphasia. Theoretical models of short-term memory are reviewed, starting with a model assuming a separation between short-term memory and language, and progressing to models that view verbal short-term memory as a cognitive requirement of language processing. The review highlights a verbal short-term memory model derived from an interactive activation model of word retrieval. This model holds that verbal short-term memory encompasses the temporary activation of linguistic knowledge (e.g., semantic, lexical, and phonological features) during language production and comprehension tasks. Empirical evidence supporting this model, which views short-term memory in the context of the processes it subserves, is outlined. Studies that use a classic measure of verbal short-term memory (i.e., number of words/digits correctly recalled in immediate serial recall) as well as those that use more intricate measures (e.g., serial position effects in immediate serial recall) are discussed. Treatment research that uses verbal short-term memory tasks in an attempt to improve language processing is then summarized, with a particular focus on word retrieval. A discussion of the limitations of current research and possible future directions concludes the review. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Short-Term Memory and Aphasia: From Theory to Treatment

PubMed Central

Minkina, Irene; Rosenberg, Samantha; Kalinyak-Fliszar, Michelene; Martin, Nadine

2018-01-01

This article reviews existing research on the interactions between verbal short-term memory and language processing impairments in aphasia. Theoretical models of short-term memory are reviewed, starting with a model assuming a separation between short-term memory and language, and progressing to models that view verbal short-term memory as a cognitive requirement of language processing. The review highlights a verbal short-term memory model derived from an interactive activation model of word retrieval. This model holds that verbal short-term memory encompasses the temporary activation of linguistic knowledge (e.g., semantic, lexical, and phonological features) during language production and comprehension tasks. Empirical evidence supporting this model, which views short-term memory in the context of the processes it subserves, is outlined. Studies that use a classic measure of verbal short-term memory (i.e., number of words/digits correctly recalled in immediate serial recall) as well as those that use more intricate measures (e.g., serial position effects in immediate serial recall) are discussed. Treatment research that uses verbal short-term memory tasks in an attempt to improve language processing is then summarized, with a particular focus on word retrieval. A discussion of the limitations of current research and possible future directions concludes the review. PMID:28201834

A model of memory impairment in schizophrenia: cognitive and clinical factors associated with memory efficiency and memory errors.

PubMed

Brébion, Gildas; Bressan, Rodrigo A; Ohlsen, Ruth I; David, Anthony S

2013-12-01

Memory impairments in patients with schizophrenia have been associated with various cognitive and clinical factors. Hallucinations have been more specifically associated with errors stemming from source monitoring failure. We conducted a broad investigation of verbal memory and visual memory as well as source memory functioning in a sample of patients with schizophrenia. Various memory measures were tallied, and we studied their associations with processing speed, working memory span, and positive, negative, and depressive symptoms. Superficial and deep memory processes were differentially associated with processing speed, working memory span, avolition, depression, and attention disorders. Auditory/verbal and visual hallucinations were differentially associated with specific types of source memory error. We integrated all the results into a revised version of a previously published model of memory functioning in schizophrenia. The model describes the factors that affect memory efficiency, as well as the cognitive underpinnings of hallucinations within the source monitoring framework. © 2013.

A general model for memory interference in a multiprocessor system with memory hierarchy

NASA Technical Reports Server (NTRS)

Taha, Badie A.; Standley, Hilda M.

1989-01-01

The problem of memory interference in a multiprocessor system with a hierarchy of shared buses and memories is addressed. The behavior of the processors is represented by a sequence of memory requests with each followed by a determined amount of processing time. A statistical queuing network model for determining the extent of memory interference in multiprocessor systems with clusters of memory hierarchies is presented. The performance of the system is measured by the expected number of busy memory clusters. The results of the analytic model are compared with simulation results, and the correlation between them is found to be very high.

An experimental method to verify soil conservation by check dams on the Loess Plateau, China.

PubMed

Xu, X Z; Zhang, H W; Wang, G Q; Chen, S C; Dang, W Q

2009-12-01

A successful experiment with a physical model requires necessary conditions of similarity. This study presents an experimental method with a semi-scale physical model. The model is used to monitor and verify soil conservation by check dams in a small watershed on the Loess Plateau of China. During experiments, the model-prototype ratio of geomorphic variables was kept constant under each rainfall event. Consequently, experimental data are available for verification of soil erosion processes in the field and for predicting soil loss in a model watershed with check dams. Thus, it can predict the amount of soil loss in a catchment. This study also mentions four criteria: similarities of watershed geometry, grain size and bare land, Froude number (Fr) for rainfall event, and soil erosion in downscaled models. The efficacy of the proposed method was confirmed using these criteria in two different downscaled model experiments. The B-Model, a large scale model, simulates watershed prototype. The two small scale models, D(a) and D(b), have different erosion rates, but are the same size. These two models simulate hydraulic processes in the B-Model. Experiment results show that while soil loss in the small scale models was converted by multiplying the soil loss scale number, it was very close to that of the B-Model. Obviously, with a semi-scale physical model, experiments are available to verify and predict soil loss in a small watershed area with check dam system on the Loess Plateau, China.

Using visual lateralization to model learning and memory in zebrafish larvae

PubMed Central

Andersson, Madelene Åberg; Ek, Fredrik; Olsson, Roger

2015-01-01

Impaired learning and memory are common symptoms of neurodegenerative and neuropsychiatric diseases. Present, there are several behavioural test employed to assess cognitive functions in animal models, including the frequently used novel object recognition (NOR) test. However, although atypical functional brain lateralization has been associated with neuropsychiatric conditions, spanning from schizophrenia to autism, few animal models are available to study this phenomenon in learning and memory deficits. Here we present a visual lateralization NOR model (VLNOR) in zebrafish larvae as an assay that combines brain lateralization and NOR. In zebrafish larvae, learning and memory are generally assessed by habituation, sensitization, or conditioning paradigms, which are all representatives of nondeclarative memory. The VLNOR is the first model for zebrafish larvae that studies a memory similar to the declarative memory described for mammals. We demonstrate that VLNOR can be used to study memory formation, storage, and recall of novel objects, both short and long term, in 10-day-old zebrafish. Furthermore we show that the VLNOR model can be used to study chemical modulation of memory formation and maintenance using dizocilpine (MK-801), a frequently used non-competitive antagonist of the NMDA receptor, used to test putative antipsychotics in animal models. PMID:25727677

Cerebellar models of associative memory: Three papers from IEEE COMPCON spring 1989

NASA Technical Reports Server (NTRS)

Raugh, Michael R. (Editor)

1989-01-01

Three papers are presented on the following topics: (1) a cerebellar-model associative memory as a generalized random-access memory; (2) theories of the cerebellum - two early models of associative memory; and (3) intelligent network management and functional cerebellum synthesis.

75 FR 27406 - Airworthiness Directives; Bombardier, Inc. Model BD-100-1A10 (Challenger 300) Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-17

... BD- 100 Time Limits/Maintenance Checks. The actions described in this service information are... Challenger 300 BD-100 Time Limits/Maintenance Checks. (1) For the new tasks identified in Bombardier TR 5-2... Requirements,'' in Part 2 of Chapter 5 of Bombardier Challenger 300 BD-100 Time Limits/ Maintenance Checks...

75 FR 66655 - Airworthiness Directives; PILATUS Aircraft Ltd. Model PC-7 Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-29

... December 3, 2010 (the effective date of this AD), check the airplane maintenance records to determine if... of the airplane. Do this check following paragraph 3.A. of Pilatus Aircraft Ltd. PC-7 Service... maintenance records check required in paragraph (f)(1) of this AD or it is unclear whether or not the left and...

77 FR 20520 - Airworthiness Directives; Bombardier, Inc. Model BD-100-1A10 (Challenger 300) Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-05

... Bombardier Challenger 300 BD-100 Time Limits/Maintenance Checks Manual. For this task, the initial compliance..., of Part 2, of the Bombardier Challenger 300 BD-100 Time Limits/Maintenance Checks Manual, the general.../Maintenance Checks Manual, provided that the relevant information in the general revision is identical to that...

Latent change models of adult cognition: are changes in processing speed and working memory associated with changes in episodic memory?

PubMed

Hertzog, Christopher; Dixon, Roger A; Hultsch, David F; MacDonald, Stuart W S

2003-12-01

The authors used 6-year longitudinal data from the Victoria Longitudinal Study (VLS) to investigate individual differences in amount of episodic memory change. Latent change models revealed reliable individual differences in cognitive change. Changes in episodic memory were significantly correlated with changes in other cognitive variables, including speed and working memory. A structural equation model for the latent change scores showed that changes in speed and working memory predicted changes in episodic memory, as expected by processing resource theory. However, these effects were best modeled as being mediated by changes in induction and fact retrieval. Dissociations were detected between cross-sectional ability correlations and longitudinal changes. Shuffling the tasks used to define the Working Memory latent variable altered patterns of change correlations.

Metamorphological awareness and EFL students' memory, retention, and retrieval of English adjectival lexicons.

PubMed

Zhang, Lawrence Jun

2002-12-01

Research has shown that foreign or second language learners' metalinguistic awareness has important effects on their acquisition of the target language. Important among a multitude of the concerns are problems these learners encounter when they have to process the morphological features of individual words, particularly in the acquisition of literacy skills. Nevertheless, for students who learn English as a foreign or second language for academic purposes, one of the biggest challenges in their advanced study is how they can effectively remember, retain, and retrieve the colossal number of newly learnt English vocabulary, including adjectival lexicons, to enhance their academic success. Results from the present report on the effects of metamorphological awareness of 65 adult Chinese EFL learners' memory, retention, and retrieval of adjectival lexicons show that, although the subjects in the two groups did not differ significantly in their performance on a pretest designed to check their lexical knowledge and no sex difference was observed, statistically significant differences were found between the two groups in both conditions (immediate and delayed retrievals) on a posttest. The experimental group and women predominantly performed better in the memory-retention-retrieval tasks assigned to them. Implications for educational research and practices are also discussed.

Reactive Oxygen Species in the Regulation of Synaptic Plasticity and Memory

PubMed Central

Klann, Eric

2011-01-01

Abstract The brain is a metabolically active organ exhibiting high oxygen consumption and robust production of reactive oxygen species (ROS). The large amounts of ROS are kept in check by an elaborate network of antioxidants, which sometimes fail and lead to neuronal oxidative stress. Thus, ROS are typically categorized as neurotoxic molecules and typically exert their detrimental effects via oxidation of essential macromolecules such as enzymes and cytoskeletal proteins. Most importantly, excessive ROS are associated with decreased performance in cognitive function. However, at physiological concentrations, ROS are involved in functional changes necessary for synaptic plasticity and hence, for normal cognitive function. The fine line of role reversal of ROS from good molecules to bad molecules is far from being fully understood. This review focuses on identifying the multiple sources of ROS in the mammalian nervous system and on presenting evidence for the critical and essential role of ROS in synaptic plasticity and memory. The review also shows that the inability to restrain either age- or pathology-related increases in ROS levels leads to opposite, detrimental effects that are involved in impairments in synaptic plasticity and memory function. Antioxid. Redox Signal. 14, 2013–2054. PMID:20649473

Working Memory in the Classroom: An Inside Look at the Central Executive.

PubMed

Barker, Lauren A

2016-01-01

This article provides a review of working memory and its application to educational settings. A discussion of the varying definitions of working memory is presented. Special attention is given to the various multidisciplinary professionals who work with students with working memory deficits, and their unique understanding of the construct. Definitions and theories of working memory are briefly summarized and provide the foundation for understanding practical applications of working memory to assessment and intervention. Although definitions and models of working memory abound, there is limited consensus regarding universally accepted definitions and models. Current research indicates that developing new models of working memory may be an appropriate paradigm shift at this time. The integration of individual practitioner's knowledge regarding academic achievement, working memory and processing speed could provide a foundation for the future development of new working memory models. Future directions for research should aim to explain how tasks and behaviors are supported by the substrates of the cortico-striatal and the cerebro-cerebellar systems. Translation of neurobiological information into educational contexts will be helpful to inform all practitioners' knowledge of working memory constructs. It will also allow for universally accepted definitions and models of working memory to arise and facilitate more effective collaboration between disciplines working in educational setting.

User Preference-Based Dual-Memory Neural Model With Memory Consolidation Approach.

PubMed

Nasir, Jauwairia; Yoo, Yong-Ho; Kim, Deok-Hwa; Kim, Jong-Hwan; Nasir, Jauwairia; Yong-Ho Yoo; Deok-Hwa Kim; Jong-Hwan Kim; Nasir, Jauwairia; Yoo, Yong-Ho; Kim, Deok-Hwa; Kim, Jong-Hwan

2018-06-01

Memory modeling has been a popular topic of research for improving the performance of autonomous agents in cognition related problems. Apart from learning distinct experiences correctly, significant or recurring experiences are expected to be learned better and be retrieved easier. In order to achieve this objective, this paper proposes a user preference-based dual-memory adaptive resonance theory network model, which makes use of a user preference to encode memories with various strengths and to learn and forget at various rates. Over a period of time, memories undergo a consolidation-like process at a rate proportional to the user preference at the time of encoding and the frequency of recall of a particular memory. Consolidated memories are easier to recall and are more stable. This dual-memory neural model generates distinct episodic memories and a flexible semantic-like memory component. This leads to an enhanced retrieval mechanism of experiences through two routes. The simulation results are presented to evaluate the proposed memory model based on various kinds of cues over a number of trials. The experimental results on Mybot are also presented. The results verify that not only are distinct experiences learned correctly but also that experiences associated with higher user preference and recall frequency are consolidated earlier. Thus, these experiences are recalled more easily relative to the unconsolidated experiences.

"I share, therefore I am": personality traits, life satisfaction, and Facebook check-ins.

PubMed

Wang, Shaojung Sharon

2013-12-01

This study explored whether agreeableness, extraversion, and openness function to influence self-disclosure behavior, which in turn impacts the intensity of checking in on Facebook. A complete path from extraversion to Facebook check-in through self-disclosure and sharing was found. The indirect effect from sharing to check-in intensity through life satisfaction was particularly salient. The central component of check-in is for users to disclose a specific location selectively that has implications on demonstrating their social lives, lifestyles, and tastes, enabling a selective and optimized self-image. Implications on the hyperpersonal model and warranting principle are discussed.

Model-Driven Study of Visual Memory

DTIC Science & Technology

2004-12-01

dimensional stimuli (synthetic human faces ) afford important insights into episodic recognition memory. The results were well accommodated by a summed...the unusual properties of the z-transformed ROCS. 15. SUBJECT TERMS Memory, visual memory, computational model, human memory, faces , identity 16...3 Accomplishments/New Findings 3 Work on Objective One: Recognition Memory for Synthetic Faces . 3 Experim ent 1

A Game-Theoretic Approach to Branching Time Abstract-Check-Refine Process

NASA Technical Reports Server (NTRS)

Wang, Yi; Tamai, Tetsuo

2009-01-01

Since the complexity of software systems continues to grow, most engineers face two serious problems: the state space explosion problem and the problem of how to debug systems. In this paper, we propose a game-theoretic approach to full branching time model checking on three-valued semantics. The three-valued models and logics provide successful abstraction that overcomes the state space explosion problem. The game style model checking that generates counter-examples can guide refinement or identify validated formulas, which solves the system debugging problem. Furthermore, output of our game style method will give significant information to engineers in detecting where errors have occurred and what the causes of the errors are.

Efficient Translation of LTL Formulae into Buchi Automata

NASA Technical Reports Server (NTRS)

Giannakopoulou, Dimitra; Lerda, Flavio

2001-01-01

Model checking is a fully automated technique for checking that a system satisfies a set of required properties. With explicit-state model checkers, properties are typically defined in linear-time temporal logic (LTL), and are translated into B chi automata in order to be checked. This report presents how we have combined and improved existing techniques to obtain an efficient LTL to B chi automata translator. In particular, we optimize the core of existing tableau-based approaches to generate significantly smaller automata. Our approach has been implemented and is being released as part of the Java PathFinder software (JPF), an explicit state model checker under development at the NASA Ames Research Center.

Forgetfulness can help you win games.

PubMed

Burridge, James; Gao, Yu; Mao, Yong

2015-09-01

We present a simple game model where agents with different memory lengths compete for finite resources. We show by simulation and analytically that an instability exists at a critical memory length, and as a result, different memory lengths can compete and coexist in a dynamical equilibrium. Our analytical formulation makes a connection to statistical urn models, and we show that temperature is mirrored by the agent's memory. Our simple model of memory may be incorporated into other game models with implications that we briefly discuss.

Concrete Model Checking with Abstract Matching and Refinement

NASA Technical Reports Server (NTRS)

Pasareanu Corina S.; Peianek Radek; Visser, Willem

2005-01-01

We propose an abstraction-based model checking method which relies on refinement of an under-approximation of the feasible behaviors of the system under analysis. The method preserves errors to safety properties, since all analyzed behaviors are feasible by definition. The method does not require an abstract transition relation to he generated, but instead executes the concrete transitions while storing abstract versions of the concrete states, as specified by a set of abstraction predicates. For each explored transition. the method checks, with the help of a theorem prover, whether there is any loss of precision introduced by abstraction. The results of these checks are used to decide termination or to refine the abstraction, by generating new abstraction predicates. If the (possibly infinite) concrete system under analysis has a finite bisimulation quotient, then the method is guaranteed to eventually explore an equivalent finite bisimilar structure. We illustrate the application of the approach for checking concurrent programs. We also show how a lightweight variant can be used for efficient software testing.

Logic Model Checking of Unintended Acceleration Claims in Toyota Vehicles

NASA Technical Reports Server (NTRS)

Gamble, Ed

2012-01-01

Part of the US Department of Transportation investigation of Toyota sudden unintended acceleration (SUA) involved analysis of the throttle control software, JPL Laboratory for Reliable Software applied several techniques including static analysis and logic model checking, to the software; A handful of logic models were build, Some weaknesses were identified; however, no cause for SUA was found; The full NASA report includes numerous other analyses

Logic Model Checking of Unintended Acceleration Claims in the 2005 Toyota Camry Electronic Throttle Control System

NASA Technical Reports Server (NTRS)

Gamble, Ed; Holzmann, Gerard

2011-01-01

Part of the US DOT investigation of Toyota SUA involved analysis of the throttle control software. JPL LaRS applied several techniques, including static analysis and logic model checking, to the software. A handful of logic models were built. Some weaknesses were identified; however, no cause for SUA was found. The full NASA report includes numerous other analyses

Conceptual design and feasibility evaluation model of a 10 to the 8th power bit oligatomic mass memory. Volume 2: Feasibility evaluation model

NASA Technical Reports Server (NTRS)

Horst, R. L.; Nordstrom, M. J.

1972-01-01

The partially populated oligatomic mass memory feasibility model is described and evaluated. A system was desired to verify the feasibility of the oligatomic (mirror) memory approach as applicable to large scale solid state mass memories.

Oscillations in Spurious States of the Associative Memory Model with Synaptic Depression

NASA Astrophysics Data System (ADS)

Murata, Shin; Otsubo, Yosuke; Nagata, Kenji; Okada, Masato

2014-12-01

The associative memory model is a typical neural network model that can store discretely distributed fixed-point attractors as memory patterns. When the network stores the memory patterns extensively, however, the model has other attractors besides the memory patterns. These attractors are called spurious memories. Both spurious states and memory states are in equilibrium, so there is little difference between their dynamics. Recent physiological experiments have shown that the short-term dynamic synapse called synaptic depression decreases its efficacy of transmission to postsynaptic neurons according to the activities of presynaptic neurons. Previous studies revealed that synaptic depression destabilizes the memory states when the number of memory patterns is finite. However, it is very difficult to study the dynamical properties of the spurious states if the number of memory patterns is proportional to the number of neurons. We investigate the effect of synaptic depression on spurious states by Monte Carlo simulation. The results demonstrate that synaptic depression does not affect the memory states but mainly destabilizes the spurious states and induces periodic oscillations.

Model selection and assessment for multi­-species occupancy models

USGS Publications Warehouse

Broms, Kristin M.; Hooten, Mevin B.; Fitzpatrick, Ryan M.

2016-01-01

While multi-species occupancy models (MSOMs) are emerging as a popular method for analyzing biodiversity data, formal checking and validation approaches for this class of models have lagged behind. Concurrent with the rise in application of MSOMs among ecologists, a quiet regime shift is occurring in Bayesian statistics where predictive model comparison approaches are experiencing a resurgence. Unlike single-species occupancy models that use integrated likelihoods, MSOMs are usually couched in a Bayesian framework and contain multiple levels. Standard model checking and selection methods are often unreliable in this setting and there is only limited guidance in the ecological literature for this class of models. We examined several different contemporary Bayesian hierarchical approaches for checking and validating MSOMs and applied these methods to a freshwater aquatic study system in Colorado, USA, to better understand the diversity and distributions of plains fishes. Our findings indicated distinct differences among model selection approaches, with cross-validation techniques performing the best in terms of prediction.

Comparison of the Effects of High-Energy Photon Beam Irradiation (10 and 18 MV) on 2 Types of Implantable Cardioverter-Defibrillators

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

Hashii, Haruko, E-mail: haruko@pmrc.tsukuba.ac.jp; Hashimoto, Takayuki; Okawa, Ayako

2013-03-01

Purpose: Radiation therapy for cancer may be required for patients with implantable cardiac devices. However, the influence of secondary neutrons or scattered irradiation from high-energy photons (≥10 MV) on implantable cardioverter-defibrillators (ICDs) is unclear. This study was performed to examine this issue in 2 ICD models. Methods and Materials: ICDs were positioned around a water phantom under conditions simulating clinical radiation therapy. The ICDs were not irradiated directly. A control ICD was positioned 140 cm from the irradiation isocenter. Fractional irradiation was performed with 18-MV and 10-MV photon beams to give cumulative in-field doses of 600 Gy and 1600 Gy,more » respectively. Errors were checked after each fraction. Soft errors were defined as severe (change to safety back-up mode), moderate (memory interference, no changes in device parameters), and minor (slight memory change, undetectable by computer). Results: Hard errors were not observed. For the older ICD model, the incidences of severe, moderate, and minor soft errors at 18 MV were 0.75, 0.5, and 0.83/50 Gy at the isocenter. The corresponding data for 10 MV were 0.094, 0.063, and 0 /50 Gy. For the newer ICD model at 18 MV, these data were 0.083, 2.3, and 5.8 /50 Gy. Moderate and minor errors occurred at 18 MV in control ICDs placed 140 cm from the isocenter. The error incidences were 0, 1, and 0 /600 Gy at the isocenter for the newer model, and 0, 1, and 6 /600Gy for the older model. At 10 MV, no errors occurred in control ICDs. Conclusions: ICD errors occurred more frequently at 18 MV irradiation, which suggests that the errors were mainly caused by secondary neutrons. Soft errors of ICDs were observed with high energy photon beams, but most were not critical in the newer model. These errors may occur even when the device is far from the irradiation field.« less

On Productive Knowledge and Levels of Questions.

ERIC Educational Resources Information Center

Andre, Thomas

A model is proposed for memory that stresses a distinction between episodic memory for encoded personal experience and semantic memory for abstractors and generalizations. Basically, the model holds that questions influence the nature of memory representations formed during instruction, and that memory representation controls the way in which…

Computational Model-Based Prediction of Human Episodic Memory Performance Based on Eye Movements

NASA Astrophysics Data System (ADS)

Sato, Naoyuki; Yamaguchi, Yoko

Subjects' episodic memory performance is not simply reflected by eye movements. We use a ‘theta phase coding’ model of the hippocampus to predict subjects' memory performance from their eye movements. Results demonstrate the ability of the model to predict subjects' memory performance. These studies provide a novel approach to computational modeling in the human-machine interface.

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A Bayesian Model of the Memory Colour Effect.

PubMed

Witzel, Christoph; Olkkonen, Maria; Gegenfurtner, Karl R

2018-01-01

According to the memory colour effect, the colour of a colour-diagnostic object is not perceived independently of the object itself. Instead, it has been shown through an achromatic adjustment method that colour-diagnostic objects still appear slightly in their typical colour, even when they are colourimetrically grey. Bayesian models provide a promising approach to capture the effect of prior knowledge on colour perception and to link these effects to more general effects of cue integration. Here, we model memory colour effects using prior knowledge about typical colours as priors for the grey adjustments in a Bayesian model. This simple model does not involve any fitting of free parameters. The Bayesian model roughly captured the magnitude of the measured memory colour effect for photographs of objects. To some extent, the model predicted observed differences in memory colour effects across objects. The model could not account for the differences in memory colour effects across different levels of realism in the object images. The Bayesian model provides a particularly simple account of memory colour effects, capturing some of the multiple sources of variation of these effects.

A Bayesian Model of the Memory Colour Effect

PubMed Central

Olkkonen, Maria; Gegenfurtner, Karl R.

2018-01-01

According to the memory colour effect, the colour of a colour-diagnostic object is not perceived independently of the object itself. Instead, it has been shown through an achromatic adjustment method that colour-diagnostic objects still appear slightly in their typical colour, even when they are colourimetrically grey. Bayesian models provide a promising approach to capture the effect of prior knowledge on colour perception and to link these effects to more general effects of cue integration. Here, we model memory colour effects using prior knowledge about typical colours as priors for the grey adjustments in a Bayesian model. This simple model does not involve any fitting of free parameters. The Bayesian model roughly captured the magnitude of the measured memory colour effect for photographs of objects. To some extent, the model predicted observed differences in memory colour effects across objects. The model could not account for the differences in memory colour effects across different levels of realism in the object images. The Bayesian model provides a particularly simple account of memory colour effects, capturing some of the multiple sources of variation of these effects. PMID:29760874

The AIP Model of EMDR Therapy and Pathogenic Memories

PubMed Central

Hase, Michael; Balmaceda, Ute M.; Ostacoli, Luca; Liebermann, Peter; Hofmann, Arne

2017-01-01

Eye Movement Desensitization and Reprocessing (EMDR) therapy has been widely recognized as an efficacious treatment for post-traumatic stress disorder (PTSD). In the last years more insight has been gained regarding the efficacy of EMDR therapy in a broad field of mental disorders beyond PTSD. The cornerstone of EMDR therapy is its unique model of pathogenesis and change: the adaptive information processing (AIP) model. The AIP model developed by F. Shapiro has found support and differentiation in recent studies on the importance of memories in the pathogenesis of a range of mental disorders beside PTSD. However, theoretical publications or research on the application of the AIP model are still rare. The increasing acceptance of ideas that relate the origin of many mental disorders to the formation and consolidation of implicit dysfunctional memory lead to formation of the theory of pathogenic memories. Within the theory of pathogenic memories these implicit dysfunctional memories are considered to form basis of a variety of mental disorders. The theory of pathogenic memories seems compatible to the AIP model of EMDR therapy, which offers strategies to effectively access and transmute these memories leading to amelioration or resolution of symptoms. Merging the AIP model with the theory of pathogenic memories may initiate research. In consequence, patients suffering from such memory-based disorders may be earlier diagnosed and treated more effectively. PMID:28983265

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2010-07-13

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A Mathematical Model for the Hippocampus: Towards the Understanding of Episodic Memory and Imagination

NASA Astrophysics Data System (ADS)

Tsuda, I.; Yamaguti, Y.; Kuroda, S.; Fukushima, Y.; Tsukada, M.

How does the brain encode episode? Based on the fact that the hippocampus is responsible for the formation of episodic memory, we have proposed a mathematical model for the hippocampus. Because episodic memory includes a time series of events, an underlying dynamics for the formation of episodic memory is considered to employ an association of memories. David Marr correctly pointed out in his theory of archecortex for a simple memory that the hippocampal CA3 is responsible for the formation of associative memories. However, a conventional mathematical model of associative memory simply guarantees a single association of memory unless a rule for an order of successive association of memories is given. The recent clinical studies in Maguire's group for the patients with the hippocampal lesion show that the patients cannot make a new story, because of the lack of ability of imagining new things. Both episodic memory and imagining things include various common characteristics: imagery, the sense of now, retrieval of semantic information, and narrative structures. Taking into account these findings, we propose a mathematical model of the hippocampus in order to understand the common mechanism of episodic memory and imagination.

A bio-inspired memory model for structural health monitoring

NASA Astrophysics Data System (ADS)

Zheng, Wei; Zhu, Yong

2009-04-01

Long-term structural health monitoring (SHM) systems need intelligent management of the monitoring data. By analogy with the way the human brain processes memories, we present a bio-inspired memory model (BIMM) that does not require prior knowledge of the structure parameters. The model contains three time-domain areas: a sensory memory area, a short-term memory area and a long-term memory area. First, the initial parameters of the structural state are specified to establish safety criteria. Then the large amount of monitoring data that falls within the safety limits is filtered while the data outside the safety limits are captured instantly in the sensory memory area. Second, disturbance signals are distinguished from danger signals in the short-term memory area. Finally, the stable data of the structural balance state are preserved in the long-term memory area. A strategy for priority scheduling via fuzzy c-means for the proposed model is then introduced. An experiment on bridge tower deformation demonstrates that the proposed model can be applied for real-time acquisition, limited-space storage and intelligent mining of the monitoring data in a long-term SHM system.

Chemical Memory Reactions Induced Bursting Dynamics in Gene Expression

PubMed Central

Tian, Tianhai

2013-01-01

Memory is a ubiquitous phenomenon in biological systems in which the present system state is not entirely determined by the current conditions but also depends on the time evolutionary path of the system. Specifically, many memorial phenomena are characterized by chemical memory reactions that may fire under particular system conditions. These conditional chemical reactions contradict to the extant stochastic approaches for modeling chemical kinetics and have increasingly posed significant challenges to mathematical modeling and computer simulation. To tackle the challenge, I proposed a novel theory consisting of the memory chemical master equations and memory stochastic simulation algorithm. A stochastic model for single-gene expression was proposed to illustrate the key function of memory reactions in inducing bursting dynamics of gene expression that has been observed in experiments recently. The importance of memory reactions has been further validated by the stochastic model of the p53-MDM2 core module. Simulations showed that memory reactions is a major mechanism for realizing both sustained oscillations of p53 protein numbers in single cells and damped oscillations over a population of cells. These successful applications of the memory modeling framework suggested that this innovative theory is an effective and powerful tool to study memory process and conditional chemical reactions in a wide range of complex biological systems. PMID:23349679

Chemical memory reactions induced bursting dynamics in gene expression.

PubMed

Tian, Tianhai

2013-01-01

Memory is a ubiquitous phenomenon in biological systems in which the present system state is not entirely determined by the current conditions but also depends on the time evolutionary path of the system. Specifically, many memorial phenomena are characterized by chemical memory reactions that may fire under particular system conditions. These conditional chemical reactions contradict to the extant stochastic approaches for modeling chemical kinetics and have increasingly posed significant challenges to mathematical modeling and computer simulation. To tackle the challenge, I proposed a novel theory consisting of the memory chemical master equations and memory stochastic simulation algorithm. A stochastic model for single-gene expression was proposed to illustrate the key function of memory reactions in inducing bursting dynamics of gene expression that has been observed in experiments recently. The importance of memory reactions has been further validated by the stochastic model of the p53-MDM2 core module. Simulations showed that memory reactions is a major mechanism for realizing both sustained oscillations of p53 protein numbers in single cells and damped oscillations over a population of cells. These successful applications of the memory modeling framework suggested that this innovative theory is an effective and powerful tool to study memory process and conditional chemical reactions in a wide range of complex biological systems.

[Anterograde declarative memory and its models].

PubMed

Barbeau, E-J; Puel, M; Pariente, J

2010-01-01

Patient H.M.'s recent death provides the opportunity to highlight the importance of his contribution to a better understanding of the anterograde amnesic syndrome. The thorough study of this patient over five decades largely contributed to shape the unitary model of declarative memory. This model holds that declarative memory is a single system that cannot be fractionated into subcomponents. As a system, it depends mainly on medial temporal lobes structures. The objective of this review is to present the main characteristics of different modular models that have been proposed as alternatives to the unitary model. It is also an opportunity to present different patients, who, although less famous than H.M., helped make signification contribution to the field of memory. The characteristics of the five main modular models are presented, including the most recent one (the perceptual-mnemonic model). The differences as well as how these models converge are highlighted. Different possibilities that could help reconcile unitary and modular approaches are considered. Although modular models differ significantly in many aspects, all converge to the notion that memory for single items and semantic memory could be dissociated from memory for complex material and context-rich episodes. In addition, these models converge concerning the involvement of critical brain structures for these stages: Item and semantic memory, as well as familiarity, are thought to largely depend on anterior subhippocampal areas, while relational, context-rich memory and recollective experiences are thought to largely depend on the hippocampal formation. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

The Neuroanatomical, Neurophysiological and Psychological Basis of Memory: Current Models and Their Origins

PubMed Central

Camina, Eduardo; Güell, Francisco

2017-01-01

This review aims to classify and clarify, from a neuroanatomical, neurophysiological, and psychological perspective, different memory models that are currently widespread in the literature as well as to describe their origins. We believe it is important to consider previous developments without which one cannot adequately understand the kinds of models that are now current in the scientific literature. This article intends to provide a comprehensive and rigorous overview for understanding and ordering the latest scientific advances related to this subject. The main forms of memory presented include sensory memory, short-term memory, and long-term memory. Information from the world around us is first stored by sensory memory, thus enabling the storage and future use of such information. Short-term memory (or memory) refers to information processed in a short period of time. Long-term memory allows us to store information for long periods of time, including information that can be retrieved consciously (explicit memory) or unconsciously (implicit memory). PMID:28713278

The Neuroanatomical, Neurophysiological and Psychological Basis of Memory: Current Models and Their Origins.

PubMed

Camina, Eduardo; Güell, Francisco

2017-01-01

This review aims to classify and clarify, from a neuroanatomical, neurophysiological, and psychological perspective, different memory models that are currently widespread in the literature as well as to describe their origins. We believe it is important to consider previous developments without which one cannot adequately understand the kinds of models that are now current in the scientific literature. This article intends to provide a comprehensive and rigorous overview for understanding and ordering the latest scientific advances related to this subject. The main forms of memory presented include sensory memory, short-term memory, and long-term memory. Information from the world around us is first stored by sensory memory, thus enabling the storage and future use of such information. Short-term memory (or memory) refers to information processed in a short period of time. Long-term memory allows us to store information for long periods of time, including information that can be retrieved consciously (explicit memory) or unconsciously (implicit memory).

Failure of self-consistency in the discrete resource model of visual working memory.

PubMed

Bays, Paul M

2018-06-03

The discrete resource model of working memory proposes that each individual has a fixed upper limit on the number of items they can store at one time, due to division of memory into a few independent "slots". According to this model, responses on short-term memory tasks consist of a mixture of noisy recall (when the tested item is in memory) and random guessing (when the item is not in memory). This provides two opportunities to estimate capacity for each observer: first, based on their frequency of random guesses, and second, based on the set size at which the variability of stored items reaches a plateau. The discrete resource model makes the simple prediction that these two estimates will coincide. Data from eight published visual working memory experiments provide strong evidence against such a correspondence. These results present a challenge for discrete models of working memory that impose a fixed capacity limit. Copyright © 2018 The Author. Published by Elsevier Inc. All rights reserved.

Remembering the Past and Imagining the Future: A Neural Model of Spatial Memory and Imagery

ERIC Educational Resources Information Center

Byrne, Patrick; Becker, Suzanna; Burgess, Neil

2007-01-01

The authors model the neural mechanisms underlying spatial cognition, integrating neuronal systems and behavioral data, and address the relationships between long-term memory, short-term memory, and imagery, and between egocentric and allocentric and visual and ideothetic representations. Long-term spatial memory is modeled as attractor dynamics…

A Formal Model of Capacity Limits in Working Memory

ERIC Educational Resources Information Center

Oberauer, Klaus; Kliegl, Reinhold

2006-01-01

A mathematical model of working-memory capacity limits is proposed on the key assumption of mutual interference between items in working memory. Interference is assumed to arise from overwriting of features shared by these items. The model was fit to time-accuracy data of memory-updating tasks from four experiments using nonlinear mixed effect…

Foreign Language Methods and an Information Processing Model of Memory.

ERIC Educational Resources Information Center

Willebrand, Julia

The major approaches to language teaching (audiolingual method, generative grammar, Community Language Learning and Silent Way) are investigated to discover whether or not they are compatible in structure with an information-processing model of memory (IPM). The model of memory used was described by Roberta Klatzky in "Human Memory:…

A Multinomial Model of Event-Based Prospective Memory

ERIC Educational Resources Information Center

Smith, Rebekah E.; Bayen, Ute J.

2004-01-01

Prospective memory is remembering to perform an action in the future. The authors introduce the 1st formal model of event-based prospective memory, namely, a multinomial model that includes 2 separate parameters related to prospective memory processes. The 1st measures preparatory attentional processes, and the 2nd measures retrospective memory…

The Effects of Emotion on Episodic Memory for TV Commercials.

ERIC Educational Resources Information Center

Thorson, Esther; Friestad, Marian

Based on the associational nature of memory, the distinction between episodic and semantic memory, and the notion of memory strength, a model was developed of the role of emotion in the memory of television commercials. The model generated the following hypotheses: (1) emotional commercials will more likely be recalled than nonemotional…

Working memory, situation models, and synesthesia

DOE PAGES

Radvansky, Gabriel A.; Gibson, Bradley S.; McNerney, M. Windy

2013-03-04

Research on language comprehension suggests a strong relationship between working memory span measures and language comprehension. However, there is also evidence that this relationship weakens at higher levels of comprehension, such as the situation model level. The current study explored this relationship by comparing 10 grapheme–color synesthetes who have additional color experiences when they read words that begin with different letters and 48 normal controls on a number of tests of complex working memory capacity and processing at the situation model level. On all tests of working memory capacity, the synesthetes outperformed the controls. Importantly, there was no carryover benefitmore » for the synesthetes for processing at the situation model level. This reinforces the idea that although some aspects of language comprehension are related to working memory span scores, this applies less directly to situation model levels. As a result, this suggests that theories of working memory must take into account this limitation, and the working memory processes that are involved in situation model construction and processing must be derived.« less

Working memory, situation models, and synesthesia

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

Radvansky, Gabriel A.; Gibson, Bradley S.; McNerney, M. Windy

Research on language comprehension suggests a strong relationship between working memory span measures and language comprehension. However, there is also evidence that this relationship weakens at higher levels of comprehension, such as the situation model level. The current study explored this relationship by comparing 10 grapheme–color synesthetes who have additional color experiences when they read words that begin with different letters and 48 normal controls on a number of tests of complex working memory capacity and processing at the situation model level. On all tests of working memory capacity, the synesthetes outperformed the controls. Importantly, there was no carryover benefitmore » for the synesthetes for processing at the situation model level. This reinforces the idea that although some aspects of language comprehension are related to working memory span scores, this applies less directly to situation model levels. As a result, this suggests that theories of working memory must take into account this limitation, and the working memory processes that are involved in situation model construction and processing must be derived.« less

Memory complaints in epilepsy: An examination of the role of mood and illness perceptions.

PubMed

Tinson, Deborah; Crockford, Christopher; Gharooni, Sara; Russell, Helen; Zoeller, Sophie; Leavy, Yvonne; Lloyd, Rachel; Duncan, Susan

2018-03-01

The study examined the role of mood and illness perceptions in explaining the variance in the memory complaints of patients with epilepsy. Forty-four patients from an outpatient tertiary care center and 43 volunteer controls completed a formal assessment of memory and a verbal fluency test, as well as validated self-report questionnaires on memory complaints, mood, and illness perceptions. In hierarchical multiple regression analyses, objective memory test performance and verbal fluency did not contribute significantly to the variance in memory complaints for either patients or controls. In patients, illness perceptions and mood were highly correlated. Illness perceptions correlated more highly with memory complaints than mood and were therefore added to the multiple regression analysis. This accounted for an additional 25% of the variance, after controlling for objective memory test performance and verbal fluency, and the model was significant (model B). In order to compare with other studies, mood was added to a second model, instead of illness perceptions. This accounted for an additional 24% of the variance, which was again significant (model C). In controls, low mood accounted for 11% of the variance in memory complaints (model C2). A measure of illness perceptions was more highly correlated with the memory complaints of patients with epilepsy than with a measure of mood. In a hierarchical multiple regression model, illness perceptions accounted for 25% of the variance in memory complaints. Illness perceptions could provide useful information in a clinical investigation into the self-reported memory complaints of patients with epilepsy, alongside the assessment of mood and formal memory testing. Copyright © 2017 Elsevier Inc. All rights reserved.

Checking Dimensionality in Item Response Models with Principal Component Analysis on Standardized Residuals

ERIC Educational Resources Information Center

Chou, Yeh-Tai; Wang, Wen-Chung

2010-01-01

Dimensionality is an important assumption in item response theory (IRT). Principal component analysis on standardized residuals has been used to check dimensionality, especially under the family of Rasch models. It has been suggested that an eigenvalue greater than 1.5 for the first eigenvalue signifies a violation of unidimensionality when there…

Stress analysis of 27% scale model of AH-64 main rotor hub

NASA Technical Reports Server (NTRS)

Hodges, R. V.

1985-01-01

Stress analysis of an AH-64 27% scale model rotor hub was performed. Component loads and stresses were calculated based upon blade root loads and motions. The static and fatigue analysis indicates positive margins of safety in all components checked. Using the format developed here, the hub can be stress checked for future application.

Synaptic tagging, evaluation of memories, and the distal reward problem.

PubMed

Päpper, Marc; Kempter, Richard; Leibold, Christian

2011-01-01

Long-term synaptic plasticity exhibits distinct phases. The synaptic tagging hypothesis suggests an early phase in which synapses are prepared, or "tagged," for protein capture, and a late phase in which those proteins are integrated into the synapses to achieve memory consolidation. The synapse specificity of the tags is consistent with conventional neural network models of associative memory. Memory consolidation through protein synthesis, however, is neuron specific, and its functional role in those models has not been assessed. Here, using a theoretical network model, we test the tagging hypothesis on its potential to prolong memory lifetimes in an online-learning paradigm. We find that protein synthesis, though not synapse specific, prolongs memory lifetimes if it is used to evaluate memory items on a cellular level. In our model we assume that only "important" memory items evoke protein synthesis such that these become more stable than "unimportant" items, which do not evoke protein synthesis. The network model comprises an equilibrium distribution of synaptic states that is very susceptible to the storage of new items: Most synapses are in a state in which they are plastic and can be changed easily, whereas only those synapses that are essential for the retrieval of the important memory items are in the stable late phase. The model can solve the distal reward problem, where the initial exposure of a memory item and its evaluation are temporally separated. Synaptic tagging hence provides a viable mechanism to consolidate and evaluate memories on a synaptic basis.

Global Neural Pattern Similarity as a Common Basis for Categorization and Recognition Memory

PubMed Central

Xue, Gui; Love, Bradley C.; Preston, Alison R.; Poldrack, Russell A.

2014-01-01

Familiarity, or memory strength, is a central construct in models of cognition. In previous categorization and long-term memory research, correlations have been found between psychological measures of memory strength and activation in the medial temporal lobes (MTLs), which suggests a common neural locus for memory strength. However, activation alone is insufficient for determining whether the same mechanisms underlie neural function across domains. Guided by mathematical models of categorization and long-term memory, we develop a theory and a method to test whether memory strength arises from the global similarity among neural representations. In human subjects, we find significant correlations between global similarity among activation patterns in the MTLs and both subsequent memory confidence in a recognition memory task and model-based measures of memory strength in a category learning task. Our work bridges formal cognitive theories and neuroscientific models by illustrating that the same global similarity computations underlie processing in multiple cognitive domains. Moreover, by establishing a link between neural similarity and psychological memory strength, our findings suggest that there may be an isomorphism between psychological and neural representational spaces that can be exploited to test cognitive theories at both the neural and behavioral levels. PMID:24872552

Activation and Binding in Verbal Working Memory: A Dual-Process Model for the Recognition of Nonwords

ERIC Educational Resources Information Center

Oberauer, Klauss; Lange, Elke B.

2009-01-01

The article presents a mathematical model of short-term recognition based on dual-process models and the three-component theory of working memory [Oberauer, K. (2002). Access to information in working memory: Exploring the focus of attention. "Journal of Experimental Psychology: Learning, Memory, and Cognition, 28", 411-421]. Familiarity arises…

Do alcohol compliance checks decrease underage sales at neighboring establishments?

PubMed

Erickson, Darin J; Smolenski, Derek J; Toomey, Traci L; Carlin, Bradley P; Wagenaar, Alexander C

2013-11-01

Underage alcohol compliance checks conducted by law enforcement agencies can reduce the likelihood of illegal alcohol sales at checked alcohol establishments, and theory suggests that an alcohol establishment that is checked may warn nearby establishments that compliance checks are being conducted in the area. In this study, we examined whether the effects of compliance checks diffuse to neighboring establishments. We used data from the Complying with the Minimum Drinking Age trial, which included more than 2,000 compliance checks conducted at more than 900 alcohol establishments. The primary outcome was the sale of alcohol to a pseudo-underage buyer without the need for age identification. A multilevel logistic regression was used to model the effect of a compliance check at each establishment as well as the effect of compliance checks at neighboring establishments within 500 m (stratified into four equal-radius concentric rings), after buyer, license, establishment, and community-level variables were controlled for. We observed a decrease in the likelihood of establishments selling alcohol to underage youth after they had been checked by law enforcement, but these effects quickly decayed over time. Establishments that had a close neighbor (within 125 m) checked in the past 90 days were also less likely to sell alcohol to young-appearing buyers. The spatial effect of compliance checks on other establishments decayed rapidly with increasing distance. Results confirm the hypothesis that the effects of police compliance checks do spill over to neighboring establishments. These findings have implications for the development of an optimal schedule of police compliance checks.

A new model for CD8+ T cell memory inflation based upon a recombinant adenoviral vector1

PubMed Central

Bolinger, Beatrice; Sims, Stuart; O’Hara, Geraldine; de Lara, Catherine; Tchilian, Elma; Firner, Sonja; Engeler, Daniel; Ludewig, Burkhard; Klenerman, Paul

2013-01-01

CD8+ T cell memory inflation, first described in murine cytomegalovirus (MCMV) infection, is characterized by the accumulation of high-frequency, functional antigen-specific CD8+ T cell pools with an effector-memory phenotype and enrichment in peripheral organs. Although persistence of antigen is considered essential, the rules underpinning memory inflation are still unclear. The MCMV model is, however, complicated by the virus’s low-level persistence, and stochastic reactivation. We developed a new model of memory inflation based upon a βgal-recombinant adenovirus vector (Ad-LacZ). After i.v. administration in C57BL/6 mice we observe marked memory inflation in the βgal96 epitope, while a second epitope, βgal497, undergoes classical memory formation. The inflationary T cell responses show kinetics, distribution, phenotype and functions similar to those seen in MCMV and are reproduced using alternative routes of administration. Memory inflation in this model is dependent on MHC Class II. As in MCMV, only the inflating epitope showed immunoproteasome-independence. These data define a new model for memory inflation, which is fully replication-independent, internally controlled and reproduces the key immunologic features of the CD8+ T cell response. This model provides insight into the mechanisms responsible for memory inflation, and since it is based on a vaccine vector, also is relevant to novel T cell-inducing vaccines in humans. PMID:23509359

Observational analysis on inflammatory reaction to talc pleurodesis: Small and large animal model series review

PubMed Central

Vannucci, Jacopo; Bellezza, Guido; Matricardi, Alberto; Moretti, Giulia; Bufalari, Antonello; Cagini, Lucio; Puma, Francesco; Daddi, Niccolò

2018-01-01

Talc pleurodesis has been associated with pleuropulmonary damage, particularly long-term damage due to its inert nature. The present model series review aimed to assess the safety of this procedure by examining inflammatory stimulus, biocompatibility and tissue reaction following talc pleurodesis. Talc slurry was performed in rabbits: 200 mg/kg checked at postoperative day 14 (five models), 200 mg/kg checked at postoperative day 28 (five models), 40 mg/kg, checked at postoperative day 14 (five models), 40 mg/kg checked at postoperative day 28 (five models). Talc poudrage was performed in pigs: 55 mg/kg checked at postoperative day 60 (18 models). Tissue inspection and data collection followed the surgical pathology approach currently used in clinical practice. As this was an observational study, no statistical analysis was performed. Regarding the rabbit model (Oryctolagus cunicoli), the extent of adhesions ranged between 0 and 30%, and between 0 and 10% following 14 and 28 days, respectively. No intraparenchymal granuloma was observed whereas, pleural granulomas were extensively encountered following both talc dosages, with more evidence of visceral pleura granulomas following 200 mg/kg compared with 40 mg/kg. Severe florid inflammation was observed in 2/10 cases following 40 mg/kg. Parathymic, pericardium granulomas and mediastinal lymphadenopathy were evidenced at 28 days. At 60 days, from rare adhesions to extended pleurodesis were observed in the pig model (Sus Scrofa domesticus). Pleural granulomas were ubiquitous on visceral and parietal pleurae. Severe spotted inflammation among the adhesions were recorded in 15/18 pigs. Intraparenchymal granulomas were observed in 9/18 lungs. Talc produced unpredictable pleurodesis in both animal models with enduring pleural inflammation whether it was performed via slurry or poudrage. Furthermore, talc appeared to have triggered extended pleural damage, intraparenchymal nodules (porcine poudrage) and mediastinal migration (rabbit slurry). PMID:29403549

Generalized memory associativity in a network model for the neuroses

NASA Astrophysics Data System (ADS)

Wedemann, Roseli S.; Donangelo, Raul; de Carvalho, Luís A. V.

2009-03-01

We review concepts introduced in earlier work, where a neural network mechanism describes some mental processes in neurotic pathology and psychoanalytic working-through, as associative memory functioning, according to the findings of Freud. We developed a complex network model, where modules corresponding to sensorial and symbolic memories interact, representing unconscious and conscious mental processes. The model illustrates Freud's idea that consciousness is related to symbolic and linguistic memory activity in the brain. We have introduced a generalization of the Boltzmann machine to model memory associativity. Model behavior is illustrated with simulations and some of its properties are analyzed with methods from statistical mechanics.

Goal-Driven Autonomy and Robust Architecture for Long-Duration Missions (Year 1: 1 July 2013 - 31 July 2014)

DTIC Science & Technology

2014-09-30

Mental Domain = Ω Goal Management goal change goal input World =Ψ Memory Mission & Goals( ) World Model (-Ψ) Episodic Memory Semantic Memory ...Activations Trace Meta-Level Control Introspective Monitoring Memory Reasoning Trace ( ) Strategies Episodic Memory Metaknowledge Self Model...it is from incorrect or missing memory associations (i.e., indices). Similarly, correct information may exist in the input stream, but may not be

Long-term memory and volatility clustering in high-frequency price changes

NASA Astrophysics Data System (ADS)

oh, Gabjin; Kim, Seunghwan; Eom, Cheoljun

2008-02-01

We studied the long-term memory in diverse stock market indices and foreign exchange rates using Detrended Fluctuation Analysis (DFA). For all high-frequency market data studied, no significant long-term memory property was detected in the return series, while a strong long-term memory property was found in the volatility time series. The possible causes of the long-term memory property were investigated using the return data filtered by the AR(1) model, reflecting the short-term memory property, the GARCH(1,1) model, reflecting the volatility clustering property, and the FIGARCH model, reflecting the long-term memory property of the volatility time series. The memory effect in the AR(1) filtered return and volatility time series remained unchanged, while the long-term memory property diminished significantly in the volatility series of the GARCH(1,1) filtered data. Notably, there is no long-term memory property, when we eliminate the long-term memory property of volatility by the FIGARCH model. For all data used, although the Hurst exponents of the volatility time series changed considerably over time, those of the time series with the volatility clustering effect removed diminish significantly. Our results imply that the long-term memory property of the volatility time series can be attributed to the volatility clustering observed in the financial time series.

Analyzing Phylogenetic Trees with Timed and Probabilistic Model Checking: The Lactose Persistence Case Study.

PubMed

Requeno, José Ignacio; Colom, José Manuel

2014-12-01

Model checking is a generic verification technique that allows the phylogeneticist to focus on models and specifications instead of on implementation issues. Phylogenetic trees are considered as transition systems over which we interrogate phylogenetic questions written as formulas of temporal logic. Nonetheless, standard logics become insufficient for certain practices of phylogenetic analysis since they do not allow the inclusion of explicit time and probabilities. The aim of this paper is to extend the application of model checking techniques beyond qualitative phylogenetic properties and adapt the existing logical extensions and tools to the field of phylogeny. The introduction of time and probabilities in phylogenetic specifications is motivated by the study of a real example: the analysis of the ratio of lactose intolerance in some populations and the date of appearance of this phenotype.

Analyzing phylogenetic trees with timed and probabilistic model checking: the lactose persistence case study.

PubMed

Requeno, José Ignacio; Colom, José Manuel

2014-10-23

Model checking is a generic verification technique that allows the phylogeneticist to focus on models and specifications instead of on implementation issues. Phylogenetic trees are considered as transition systems over which we interrogate phylogenetic questions written as formulas of temporal logic. Nonetheless, standard logics become insufficient for certain practices of phylogenetic analysis since they do not allow the inclusion of explicit time and probabilities. The aim of this paper is to extend the application of model checking techniques beyond qualitative phylogenetic properties and adapt the existing logical extensions and tools to the field of phylogeny. The introduction of time and probabilities in phylogenetic specifications is motivated by the study of a real example: the analysis of the ratio of lactose intolerance in some populations and the date of appearance of this phenotype.

Model Checking for Verification of Interactive Health IT Systems

PubMed Central

Butler, Keith A.; Mercer, Eric; Bahrami, Ali; Tao, Cui

2015-01-01

Rigorous methods for design and verification of health IT systems have lagged far behind their proliferation. The inherent technical complexity of healthcare, combined with the added complexity of health information technology makes their resulting behavior unpredictable and introduces serious risk. We propose to mitigate this risk by formalizing the relationship between HIT and the conceptual work that increasingly typifies modern care. We introduce new techniques for modeling clinical workflows and the conceptual products within them that allow established, powerful modeling checking technology to be applied to interactive health IT systems. The new capability can evaluate the workflows of a new HIT system performed by clinicians and computers to improve safety and reliability. We demonstrate the method on a patient contact system to demonstrate model checking is effective for interactive systems and that much of it can be automated. PMID:26958166

Combining Distributed and Shared Memory Models: Approach and Evolution of the Global Arrays Toolkit

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

Nieplocha, Jarek; Harrison, Robert J.; Kumar, Mukul

2002-07-29

Both shared memory and distributed memory models have advantages and shortcomings. Shared memory model is much easier to use but it ignores data locality/placement. Given the hierarchical nature of the memory subsystems in the modern computers this characteristic might have a negative impact on performance and scalability. Various techniques, such as code restructuring to increase data reuse and introducing blocking in data accesses, can address the problem and yield performance competitive with message passing[Singh], however at the cost of compromising the ease of use feature. Distributed memory models such as message passing or one-sided communication offer performance and scalability butmore » they compromise the ease-of-use. In this context, the message-passing model is sometimes referred to as?assembly programming for the scientific computing?. The Global Arrays toolkit[GA1, GA2] attempts to offer the best features of both models. It implements a shared-memory programming model in which data locality is managed explicitly by the programmer. This management is achieved by explicit calls to functions that transfer data between a global address space (a distributed array) and local storage. In this respect, the GA model has similarities to the distributed shared-memory models that provide an explicit acquire/release protocol. However, the GA model acknowledges that remote data is slower to access than local data and allows data locality to be explicitly specified and hence managed. The GA model exposes to the programmer the hierarchical memory of modern high-performance computer systems, and by recognizing the communication overhead for remote data transfer, it promotes data reuse and locality of reference. This paper describes the characteristics of the Global Arrays programming model, capabilities of the toolkit, and discusses its evolution.« less

Global exponential stability analysis on impulsive BAM neural networks with distributed delays

NASA Astrophysics Data System (ADS)

Li, Yao-Tang; Yang, Chang-Bo

2006-12-01

Using M-matrix and topological degree tool, sufficient conditions are obtained for the existence, uniqueness and global exponential stability of the equilibrium point of bidirectional associative memory (BAM) neural networks with distributed delays and subjected to impulsive state displacements at fixed instants of time by constructing a suitable Lyapunov functional. The results remove the usual assumptions that the boundedness, monotonicity, and differentiability of the activation functions. It is shown that in some cases, the stability criteria can be easily checked. Finally, an illustrative example is given to show the effectiveness of the presented criteria.

Performance issues for iterative solvers in device simulation

NASA Technical Reports Server (NTRS)

Fan, Qing; Forsyth, P. A.; Mcmacken, J. R. F.; Tang, Wei-Pai

1994-01-01

Due to memory limitations, iterative methods have become the method of choice for large scale semiconductor device simulation. However, it is well known that these methods still suffer from reliability problems. The linear systems which appear in numerical simulation of semiconductor devices are notoriously ill-conditioned. In order to produce robust algorithms for practical problems, careful attention must be given to many implementation issues. This paper concentrates on strategies for developing robust preconditioners. In addition, effective data structures and convergence check issues are also discussed. These algorithms are compared with a standard direct sparse matrix solver on a variety of problems.

Sensor Authentication: Embedded Processor Code

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

Svoboda, John

2012-09-25

Described is the c code running on the embedded Microchip 32bit PIC32MX575F256H located on the INL developed noise analysis circuit board. The code performs the following functions: Controls the noise analysis circuit board preamplifier voltage gains of 1, 10, 100, 000 Initializes the analog to digital conversion hardware, input channel selection, Fast Fourier Transform (FFT) function, USB communications interface, and internal memory allocations Initiates high resolution 4096 point 200 kHz data acquisition Computes complex 2048 point FFT and FFT magnitude. Services Host command set Transfers raw data to Host Transfers FFT result to host Communication error checking

Formation of model-free motor memories during motor adaptation depends on perturbation schedule.

PubMed

Orban de Xivry, Jean-Jacques; Lefèvre, Philippe

2015-04-01

Motor adaptation to an external perturbation relies on several mechanisms such as model-based, model-free, strategic, or repetition-dependent learning. Depending on the experimental conditions, each of these mechanisms has more or less weight in the final adaptation state. Here we focused on the conditions that lead to the formation of a model-free motor memory (Huang VS, Haith AM, Mazzoni P, Krakauer JW. Neuron 70: 787-801, 2011), i.e., a memory that does not depend on an internal model or on the size or direction of the errors experienced during the learning. The formation of such model-free motor memory was hypothesized to depend on the schedule of the perturbation (Orban de Xivry JJ, Ahmadi-Pajouh MA, Harran MD, Salimpour Y, Shadmehr R. J Neurophysiol 109: 124-136, 2013). Here we built on this observation by directly testing the nature of the motor memory after abrupt or gradual introduction of a visuomotor rotation, in an experimental paradigm where the presence of model-free motor memory can be identified (Huang VS, Haith AM, Mazzoni P, Krakauer JW. Neuron 70: 787-801, 2011). We found that relearning was faster after abrupt than gradual perturbation, which suggests that model-free learning is reduced during gradual adaptation to a visuomotor rotation. In addition, the presence of savings after abrupt introduction of the perturbation but gradual extinction of the motor memory suggests that unexpected errors are necessary to induce a model-free motor memory. Overall, these data support the hypothesis that different perturbation schedules do not lead to a more or less stabilized motor memory but to distinct motor memories with different attributes and neural representations. Copyright © 2015 the American Physiological Society.

Formation of model-free motor memories during motor adaptation depends on perturbation schedule

PubMed Central

Lefèvre, Philippe

2015-01-01

Motor adaptation to an external perturbation relies on several mechanisms such as model-based, model-free, strategic, or repetition-dependent learning. Depending on the experimental conditions, each of these mechanisms has more or less weight in the final adaptation state. Here we focused on the conditions that lead to the formation of a model-free motor memory (Huang VS, Haith AM, Mazzoni P, Krakauer JW. Neuron 70: 787–801, 2011), i.e., a memory that does not depend on an internal model or on the size or direction of the errors experienced during the learning. The formation of such model-free motor memory was hypothesized to depend on the schedule of the perturbation (Orban de Xivry JJ, Ahmadi-Pajouh MA, Harran MD, Salimpour Y, Shadmehr R. J Neurophysiol 109: 124–136, 2013). Here we built on this observation by directly testing the nature of the motor memory after abrupt or gradual introduction of a visuomotor rotation, in an experimental paradigm where the presence of model-free motor memory can be identified (Huang VS, Haith AM, Mazzoni P, Krakauer JW. Neuron 70: 787–801, 2011). We found that relearning was faster after abrupt than gradual perturbation, which suggests that model-free learning is reduced during gradual adaptation to a visuomotor rotation. In addition, the presence of savings after abrupt introduction of the perturbation but gradual extinction of the motor memory suggests that unexpected errors are necessary to induce a model-free motor memory. Overall, these data support the hypothesis that different perturbation schedules do not lead to a more or less stabilized motor memory but to distinct motor memories with different attributes and neural representations. PMID:25673736

A Framework for Cognitive Interventions Targeting Everyday Memory Performance and Memory Self-efficacy

PubMed Central

McDougall, Graham J.

2009-01-01

The human brain has the potential for self-renewal through adult neurogenesis, which is the birth of new neurons. Neural plasticity implies that the nervous system can change and grow. This understanding has created new possibilities for cognitive enhancement and rehabilitation. However, as individuals age, they have decreased confidence, or memory self-efficacy, which is directly related to their everyday memory performance. In this article, a developmental account of studies about memory self-efficacy and nonpharmacologic cognitive intervention models is presented and a cognitive intervention model, called the cognitive behavioral model of everyday memory, is proposed. PMID:19065089

Retrieval-induced NMDA receptor-dependent Arc expression in two models of cocaine-cue memory.

PubMed

Alaghband, Yasaman; O'Dell, Steven J; Azarnia, Siavash; Khalaj, Anna J; Guzowski, John F; Marshall, John F

2014-12-01

The association of environmental cues with drugs of abuse results in persistent drug-cue memories. These memories contribute significantly to relapse among addicts. While conditioned place preference (CPP) is a well-established paradigm frequently used to examine the modulation of drug-cue memories, very few studies have used the non-preference-based model conditioned activity (CA) for this purpose. Here, we used both experimental approaches to investigate the neural substrates of cocaine-cue memories. First, we directly compared, in a consistent setting, the involvement of cortical and subcortical brain regions in cocaine-cue memory retrieval by quantifying activity-regulated cytoskeletal-associated (Arc) protein expression in both the CPP and CA models. Second, because NMDA receptor activation is required for Arc expression, we investigated the NMDA receptor dependency of memory persistence using the CA model. In both the CPP and CA models, drug-paired animals showed significant increases in Arc immunoreactivity in regions of the frontal cortex and amygdala compared to unpaired controls. Additionally, administration of a NMDA receptor antagonist (MK-801 or memantine) immediately after cocaine-CA memory reactivation impaired the subsequent conditioned locomotion associated with the cocaine-paired environment. The enhanced Arc expression evident in a subset of corticolimbic regions after retrieval of a cocaine-context memory, observed in both the CPP and CA paradigms, likely signifies that these regions: (i) are activated during retrieval of these memories irrespective of preference-based decisions, and (ii) undergo neuroplasticity in order to update information about cues previously associated with cocaine. This study also establishes the involvement of NMDA receptors in maintaining memories established using the CA model, a characteristic previously demonstrated using CPP. Overall, these results demonstrate the utility of the CA model for studies of cocaine-context memory and suggest the involvement of an NMDA receptor-dependent Arc induction pathway in drug-cue memory interference. Copyright © 2014 Elsevier Inc. All rights reserved.

Modeling soil moisture memory in savanna ecosystems

NASA Astrophysics Data System (ADS)

Gou, S.; Miller, G. R.

2011-12-01

Antecedent soil conditions create an ecosystem's "memory" of past rainfall events. Such soil moisture memory effects may be observed over a range of timescales, from daily to yearly, and lead to feedbacks between hydrological and ecosystem processes. In this study, we modeled the soil moisture memory effect on savanna ecosystems in California, Arizona, and Africa, using a system dynamics model created to simulate the ecohydrological processes at the plot-scale. The model was carefully calibrated using soil moisture and evapotranspiration data collected at three study sites. The model was then used to simulate scenarios with various initial soil moisture conditions and antecedent precipitation regimes, in order to study the soil moisture memory effects on the evapotranspiration of understory and overstory species. Based on the model results, soil texture and antecedent precipitation regime impact the redistribution of water within soil layers, potentially causing deeper soil layers to influence the ecosystem for a longer time. Of all the study areas modeled, soil moisture memory of California savanna ecosystem site is replenished and dries out most rapidly. Thus soil moisture memory could not maintain the high rate evapotranspiration for more than a few days without incoming rainfall event. On the contrary, soil moisture memory of Arizona savanna ecosystem site lasts the longest time. The plants with different root depths respond to different memory effects; shallow-rooted species mainly respond to the soil moisture memory in the shallow soil. The growing season of grass is largely depended on the soil moisture memory of the top 25cm soil layer. Grass transpiration is sensitive to the antecedent precipitation events within daily to weekly timescale. Deep-rooted plants have different responses since these species can access to the deeper soil moisture memory with longer time duration Soil moisture memory does not have obvious impacts on the phenology of woody plants, as these can maintain transpiration for a longer time even through the top soil layer dries out.

Retrieval-induced NMDA receptor-dependent Arc expression in two models of cocaine-cue memory

PubMed Central

Alaghband, Yasaman; O'Dell, Steven J.; Azarnia, Siavash; Khalaj, Anna J.; Guzowski, John F.; Marshall, John F.

2014-01-01

The association of environmental cues with drugs of abuse results in persistent drug-cue memories. These memories contribute significantly to relapse among addicts. While conditioned place preference (CPP) is a well-established paradigm frequently used to examine the modulation of drug-cue memories, very few studies have used the non-preference-based model conditioned activity (CA) for this purpose. Here, we used both experimental approaches to investigate the neural substrates of cocaine-cue memories. First, we directly compared, in a consistent setting, the involvement of cortical and subcortical brain regions in cocaine-cue memory retrieval by quantifying activity-regulated cytoskeletal associated gene (Arc) protein expression in both the CPP and CA models. Second, because NMDA receptor activation is required for Arc expression, we investigated the NMDA receptor dependency of memory persistence using the CA model. In both the CPP and CA models, drug-paired animals showed significant increases in Arc immunoreactivity in regions of the frontal cortex and amygdala compared to unpaired controls. Additionally, administration of a NMDA receptor antagonist (MK-801 or memantine) immediately after cocaine-CA memory reactivation impaired the subsequent conditioned locomotion associated with the cocaine-paired environment. The enhanced Arc expression evident in a subset of corticolimbic regions after retrieval of a cocaine-context memory, observed in both the CPP and CA paradigms, likely signifies that these regions: (i) are activated during retrieval of these memories irrespective of preference-based decisions, and (ii) undergo neuroplasticity in order to update information about cues previously associated with cocaine. This study also establishes the involvement of NMDA receptors in maintaining memories established using the CA model, a characteristic previously demonstrated using CPP. Overall, these results demonstrate the utility of the CA model for studies of cocaine-context memory and suggest the involvement of an NMDA receptor-dependent Arc induction pathway in drug-cue memory interference. PMID:25225165

GRIM-Filter: Fast seed location filtering in DNA read mapping using processing-in-memory technologies.

PubMed

Kim, Jeremie S; Senol Cali, Damla; Xin, Hongyi; Lee, Donghyuk; Ghose, Saugata; Alser, Mohammed; Hassan, Hasan; Ergin, Oguz; Alkan, Can; Mutlu, Onur

2018-05-09

Seed location filtering is critical in DNA read mapping, a process where billions of DNA fragments (reads) sampled from a donor are mapped onto a reference genome to identify genomic variants of the donor. State-of-the-art read mappers 1) quickly generate possible mapping locations for seeds (i.e., smaller segments) within each read, 2) extract reference sequences at each of the mapping locations, and 3) check similarity between each read and its associated reference sequences with a computationally-expensive algorithm (i.e., sequence alignment) to determine the origin of the read. A seed location filter comes into play before alignment, discarding seed locations that alignment would deem a poor match. The ideal seed location filter would discard all poor match locations prior to alignment such that there is no wasted computation on unnecessary alignments. We propose a novel seed location filtering algorithm, GRIM-Filter, optimized to exploit 3D-stacked memory systems that integrate computation within a logic layer stacked under memory layers, to perform processing-in-memory (PIM). GRIM-Filter quickly filters seed locations by 1) introducing a new representation of coarse-grained segments of the reference genome, and 2) using massively-parallel in-memory operations to identify read presence within each coarse-grained segment. Our evaluations show that for a sequence alignment error tolerance of 0.05, GRIM-Filter 1) reduces the false negative rate of filtering by 5.59x-6.41x, and 2) provides an end-to-end read mapper speedup of 1.81x-3.65x, compared to a state-of-the-art read mapper employing the best previous seed location filtering algorithm. GRIM-Filter exploits 3D-stacked memory, which enables the efficient use of processing-in-memory, to overcome the memory bandwidth bottleneck in seed location filtering. We show that GRIM-Filter significantly improves the performance of a state-of-the-art read mapper. GRIM-Filter is a universal seed location filter that can be applied to any read mapper. We hope that our results provide inspiration for new works to design other bioinformatics algorithms that take advantage of emerging technologies and new processing paradigms, such as processing-in-memory using 3D-stacked memory devices.

Modeling of SONOS Memory Cell Erase Cycle

NASA Technical Reports Server (NTRS)

Phillips, Thomas A.; MacLeod, Todd C.; Ho, Fat H.

2011-01-01

Utilization of Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) nonvolatile semiconductor memories as a flash memory has many advantages. These electrically erasable programmable read-only memories (EEPROMs) utilize low programming voltages, have a high erase/write cycle lifetime, are radiation hardened, and are compatible with high-density scaled CMOS for low power, portable electronics. In this paper, the SONOS memory cell erase cycle was investigated using a nonquasi-static (NQS) MOSFET model. Comparisons were made between the model predictions and experimental data.

Verification and Planning Based on Coinductive Logic Programming

NASA Technical Reports Server (NTRS)

Bansal, Ajay; Min, Richard; Simon, Luke; Mallya, Ajay; Gupta, Gopal

2008-01-01

Coinduction is a powerful technique for reasoning about unfounded sets, unbounded structures, infinite automata, and interactive computations [6]. Where induction corresponds to least fixed point's semantics, coinduction corresponds to greatest fixed point semantics. Recently coinduction has been incorporated into logic programming and an elegant operational semantics developed for it [11, 12]. This operational semantics is the greatest fix point counterpart of SLD resolution (SLD resolution imparts operational semantics to least fix point based computations) and is termed co- SLD resolution. In co-SLD resolution, a predicate goal p( t) succeeds if it unifies with one of its ancestor calls. In addition, rational infinite terms are allowed as arguments of predicates. Infinite terms are represented as solutions to unification equations and the occurs check is omitted during the unification process. Coinductive Logic Programming (Co-LP) and Co-SLD resolution can be used to elegantly perform model checking and planning. A combined SLD and Co-SLD resolution based LP system forms the common basis for planning, scheduling, verification, model checking, and constraint solving [9, 4]. This is achieved by amalgamating SLD resolution, co-SLD resolution, and constraint logic programming [13] in a single logic programming system. Given that parallelism in logic programs can be implicitly exploited [8], complex, compute-intensive applications (planning, scheduling, model checking, etc.) can be executed in parallel on multi-core machines. Parallel execution can result in speed-ups as well as in larger instances of the problems being solved. In the remainder we elaborate on (i) how planning can be elegantly and efficiently performed under real-time constraints, (ii) how real-time systems can be elegantly and efficiently model- checked, as well as (iii) how hybrid systems can be verified in a combined system with both co-SLD and SLD resolution. Implementations of co-SLD resolution as well as preliminary implementations of the planning and verification applications have been developed [4]. Co-LP and Model Checking: The vast majority of properties that are to be verified can be classified into safety properties and liveness properties. It is well known within model checking that safety properties can be verified by reachability analysis, i.e, if a counter-example to the property exists, it can be finitely determined by enumerating all the reachable states of the Kripke structure.

Concept of dynamic memory in economics

NASA Astrophysics Data System (ADS)

Tarasova, Valentina V.; Tarasov, Vasily E.

2018-02-01

In this paper we discuss a concept of dynamic memory and an application of fractional calculus to describe the dynamic memory. The concept of memory is considered from the standpoint of economic models in the framework of continuous time approach based on fractional calculus. We also describe some general restrictions that can be imposed on the structure and properties of dynamic memory. These restrictions include the following three principles: (a) the principle of fading memory; (b) the principle of memory homogeneity on time (the principle of non-aging memory); (c) the principle of memory reversibility (the principle of memory recovery). Examples of different memory functions are suggested by using the fractional calculus. To illustrate an application of the concept of dynamic memory in economics we consider a generalization of the Harrod-Domar model, where the power-law memory is taken into account.

Prospective memory: A comparative perspective

PubMed Central

Crystal, Jonathon D.; Wilson, A. George

2014-01-01

Prospective memory consists of forming a representation of a future action, temporarily storing that representation in memory, and retrieving it at a future time point. Here we review the recent development of animal models of prospective memory. We review experiments using rats that focus on the development of time-based and event-based prospective memory. Next, we review a number of prospective-memory approaches that have been used with a variety of non-human primates. Finally, we review selected approaches from the human literature on prospective memory to identify targets for development of animal models of prospective memory. PMID:25101562

A model for memory systems based on processing modes rather than consciousness.

PubMed

Henke, Katharina

2010-07-01

Prominent models of human long-term memory distinguish between memory systems on the basis of whether learning and retrieval occur consciously or unconsciously. Episodic memory formation requires the rapid encoding of associations between different aspects of an event which, according to these models, depends on the hippocampus and on consciousness. However, recent evidence indicates that the hippocampus mediates rapid associative learning with and without consciousness in humans and animals, for long-term and short-term retention. Consciousness seems to be a poor criterion for differentiating between declarative (or explicit) and non declarative (or implicit) types of memory. A new model is therefore required in which memory systems are distinguished based on the processing operations involved rather than by consciousness.

Thermodynamic Model of Spatial Memory

NASA Astrophysics Data System (ADS)

Kaufman, Miron; Allen, P.

1998-03-01

We develop and test a thermodynamic model of spatial memory. Our model is an application of statistical thermodynamics to cognitive science. It is related to applications of the statistical mechanics framework in parallel distributed processes research. Our macroscopic model allows us to evaluate an entropy associated with spatial memory tasks. We find that older adults exhibit higher levels of entropy than younger adults. Thurstone's Law of Categorical Judgment, according to which the discriminal processes along the psychological continuum produced by presentations of a single stimulus are normally distributed, is explained by using a Hooke spring model of spatial memory. We have also analyzed a nonlinear modification of the ideal spring model of spatial memory. This work is supported by NIH/NIA grant AG09282-06.

The awakening of the attention: Evidence for a link between the monitoring of mind wandering and prospective goals.

PubMed

Seli, Paul; Smilek, Daniel; Ralph, Brandon C W; Schacter, Daniel L

2018-03-01

Across 2 independent samples, we examined the relation between individual differences in rates of self-caught mind wandering and individual differences in temporal monitoring of an unrelated response goal. Rates of self-caught mind wandering were assessed during a commonly used sustained-attention task, and temporal goal monitoring was indexed during a well-established prospective-memory task. The results from both samples showed a positive relation between rates of self-caught mind wandering during the sustained-attention task and rates of checking a clock to monitor the amount of time remaining before a response was required in the prospective-memory task. This relation held even when controlling for overall propensity to mind-wander (indexed by intermittent thought probes) and levels of motivation (indexed by subjective reports). These results suggest the possibility that there is a common monitoring system that monitors the contents of consciousness and the progress of ongoing goals and tasks. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Construct and concurrent validity of the Cambridge neuropsychological automated tests in Portuguese older adults without neuropsychiatric diagnoses and with Alzheimer's disease dementia.

PubMed

Matos Gonçalves, Marta; Pinho, Maria Salomé; Simões, Mário R

2018-03-01

We aimed to analyze the construct and concurrent validity of the Rapid Visual Information Processing (RVP), Paired Associates Learning (PAL), Reaction Time (RTI), and Spatial Working Memory (SWM) tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB®). Inclusion criteria were checked in a first session. The CANTAB and additional pencil-and-paper tests were administered within 1 week. The participants (aged 69-96 years) were 137 Portuguese adults without neuropsychiatric diagnoses and 37 adults with mild-to-moderate Alzheimer's disease dementia. Comparisons were made between the CANTAB tests and between these tests and the Rey Complex Figure Test (RCFT), Verbal Fluency (VF) test, and some Wechsler Memory Scale-III and Wechsler Adult Intelligence Scale-III subtests. Most intra-test correlations were stronger than the CANTAB inter-test correlations. The RVP correlated more with VF animals (.44), the PAL with RCFT immediate recall (-.52), the RTI with RVP mean latency (.42), and the SWM with Spatial Span backward (-.39).

Bayesian model checking: A comparison of tests

NASA Astrophysics Data System (ADS)

Lucy, L. B.

2018-06-01

Two procedures for checking Bayesian models are compared using a simple test problem based on the local Hubble expansion. Over four orders of magnitude, p-values derived from a global goodness-of-fit criterion for posterior probability density functions agree closely with posterior predictive p-values. The former can therefore serve as an effective proxy for the difficult-to-calculate posterior predictive p-values.

Secure open cloud in data transmission using reference pattern and identity with enhanced remote privacy checking

NASA Astrophysics Data System (ADS)

Vijay Singh, Ran; Agilandeeswari, L.

2017-11-01

To handle the large amount of client’s data in open cloud lots of security issues need to be address. Client’s privacy should not be known to other group members without data owner’s valid permission. Sometime clients are fended to have accessing with open cloud servers due to some restrictions. To overcome the security issues and these restrictions related to storing, data sharing in an inter domain network and privacy checking, we propose a model in this paper which is based on an identity based cryptography in data transmission and intermediate entity which have client’s reference with identity that will take control handling of data transmission in an open cloud environment and an extended remote privacy checking technique which will work at admin side. On behalf of data owner’s authority this proposed model will give best options to have secure cryptography in data transmission and remote privacy checking either as private or public or instructed. The hardness of Computational Diffie-Hellman assumption algorithm for key exchange makes this proposed model more secure than existing models which are being used for public cloud environment.

An extended continuum model considering optimal velocity change with memory and numerical tests

NASA Astrophysics Data System (ADS)

Qingtao, Zhai; Hongxia, Ge; Rongjun, Cheng

2018-01-01

In this paper, an extended continuum model of traffic flow is proposed with the consideration of optimal velocity changes with memory. The new model's stability condition and KdV-Burgers equation considering the optimal velocities change with memory are deduced through linear stability theory and nonlinear analysis, respectively. Numerical simulation is carried out to study the extended continuum model, which explores how optimal velocity changes with memory affected velocity, density and energy consumption. Numerical results show that when considering the effects of optimal velocity changes with memory, the traffic jams can be suppressed efficiently. Both the memory step and sensitivity parameters of optimal velocity changes with memory will enhance the stability of traffic flow efficiently. Furthermore, numerical results demonstrates that the effect of optimal velocity changes with memory can avoid the disadvantage of historical information, which increases the stability of traffic flow on road, and so it improve the traffic flow stability and minimize cars' energy consumptions.

Spot-checks to measure general hygiene practice.

PubMed

Sonego, Ina L; Mosler, Hans-Joachim

2016-01-01

A variety of hygiene behaviors are fundamental to the prevention of diarrhea. We used spot-checks in a survey of 761 households in Burundi to examine whether something we could call general hygiene practice is responsible for more specific hygiene behaviors, ranging from handwashing to sweeping the floor. Using structural equation modeling, we showed that clusters of hygiene behavior, such as primary caregivers' cleanliness and household cleanliness, explained the spot-check findings well. Within our model, general hygiene practice as overall concept explained the more specific clusters of hygiene behavior well. Furthermore, the higher general hygiene practice, the more likely children were to be categorized healthy (r = 0.46). General hygiene practice was correlated with commitment to hygiene (r = 0.52), indicating a strong association to psychosocial determinants. The results show that different hygiene behaviors co-occur regularly. Using spot-checks, the general hygiene practice of a household can be rated quickly and easily.

Latent constructs model explaining the attachment-linked variation in autobiographical remembering.

PubMed

Öner, Sezin; Gülgöz, Sami

2016-01-01

In the current study, we proposed a latent constructs model to characterise the qualitative aspects of autobiographical remembering and investigated the structural relations in the model that may vary across individuals. Primarily, we focused on the memories of romantic relationships and argued that attachment anxiety and avoidance would be reflected in the ways that individuals encode, rehearse, or remember autobiographical memories in close relationships. Participants reported two positive and two negative relationship-specific memories and rated the characteristics for each memory. As predicted, the basic memory model yielded appropriate fit, indicating that event characteristics (EC) predicted the frequency of rehearsal (RC) and phenomenology at retrieval (PC). When attachment variables were integrated, the model showed that rehearsal mediated the link between anxiety and PC, especially for negative memories. On the other hand, for avoidance EC was the key factor mediating the link between avoidance and RC, as well as PC. Findings were discussed with respect to autobiographical memory functions emphasising a systematically, integrated framework.

Global neural pattern similarity as a common basis for categorization and recognition memory.

PubMed

Davis, Tyler; Xue, Gui; Love, Bradley C; Preston, Alison R; Poldrack, Russell A

2014-05-28

Familiarity, or memory strength, is a central construct in models of cognition. In previous categorization and long-term memory research, correlations have been found between psychological measures of memory strength and activation in the medial temporal lobes (MTLs), which suggests a common neural locus for memory strength. However, activation alone is insufficient for determining whether the same mechanisms underlie neural function across domains. Guided by mathematical models of categorization and long-term memory, we develop a theory and a method to test whether memory strength arises from the global similarity among neural representations. In human subjects, we find significant correlations between global similarity among activation patterns in the MTLs and both subsequent memory confidence in a recognition memory task and model-based measures of memory strength in a category learning task. Our work bridges formal cognitive theories and neuroscientific models by illustrating that the same global similarity computations underlie processing in multiple cognitive domains. Moreover, by establishing a link between neural similarity and psychological memory strength, our findings suggest that there may be an isomorphism between psychological and neural representational spaces that can be exploited to test cognitive theories at both the neural and behavioral levels. Copyright © 2014 the authors 0270-6474/14/347472-13$15.00/0.

The role of visual imagery in the retention of information from sentences.

PubMed

Drose, G S; Allen, G L

1994-01-01

We conducted two experiments to evaluate a multiple-code model for sentence memory that posits both propositional and visual representational systems. Both sentences involved recognition memory. The results of Experiment 1 indicated that subjects' recognition memory for concrete sentences was superior to their recognition memory for abstract sentences. Instructions to use visual imagery to enhance recognition performance yielded no effects. Experiment 2 tested the prediction that interference by a visual task would differentially affect recognition memory for concrete sentences. Results showed the interference task to have had a detrimental effect on recognition memory for both concrete and abstract sentences. Overall, the evidence provided partial support for both a multiple-code model and a semantic integration model of sentence memory.

Modelling memory colour region for preference colour reproduction

NASA Astrophysics Data System (ADS)

Zeng, Huanzhao; Luo, Ronnier

2010-01-01

Colour preference adjustment is an essential step for colour image enhancement and perceptual gamut mapping. In colour reproduction for pictorial images, properly shifting colours away from their colorimetric originals may produce more preferred colour reproduction result. Memory colours, as a portion of the colour regions for colour preference adjustment, are especially important for preference colour reproduction. Identifying memory colours or modelling the memory colour region is a basic step to study preferred memory colour enhancement. In this study, we first created gamut for each memory colour region represented as a convex hull, and then used the convex hull to guide mathematical modelling to formulate the colour region for colour enhancement.

Performance Evaluation and Improvement of Ferroelectric Field-Effect Transistor Memory

NASA Astrophysics Data System (ADS)

Yu, Hyung Suk

Flash memory is reaching scaling limitations rapidly due to reduction of charge in floating gates, charge leakage and capacitive coupling between cells which cause threshold voltage fluctuations, short retention times, and interference. Many new memory technologies are being considered as alternatives to flash memory in an effort to overcome these limitations. Ferroelectric Field-Effect Transistor (FeFET) is one of the main emerging candidates because of its structural similarity to conventional FETs and fast switching speed. Nevertheless, the performance of FeFETs have not been systematically compared and analyzed against other competing technologies. In this work, we first benchmark the intrinsic performance of FeFETs and other memories by simulations in order to identify the strengths and weaknesses of FeFETs. To simulate realistic memory applications, we compare memories on an array structure. For the comparisons, we construct an accurate delay model and verify it by benchmarking against exact HSPICE simulations. Second, we propose an accurate model for FeFET memory window since the existing model has limitations. The existing model assumes symmetric operation voltages but it is not valid for the practical asymmetric operation voltages. In this modeling, we consider practical operation voltages and device dimensions. Also, we investigate realistic changes of memory window over time and retention time of FeFETs. Last, to improve memory window and subthreshold swing, we suggest nonplanar junctionless structures for FeFETs. Using the suggested structures, we study the dimensional dependences of crucial parameters like memory window and subthreshold swing and also analyze key interference mechanisms.

A Hamiltonian driven quantum-like model for overdistribution in episodic memory recollection.

NASA Astrophysics Data System (ADS)

Broekaert, Jan B.; Busemeyer, Jerome R.

2017-06-01

While people famously forget genuine memories over time, they also tend to mistakenly over-recall equivalent memories concerning a given event. The memory phenomenon is known by the name of episodic overdistribution and occurs both in memories of disjunctions and partitions of mutually exclusive events and has been tested, modeled and documented in the literature. The total classical probability of recalling exclusive sub-events most often exceeds the probability of recalling the composed event, i.e. a subadditive total. We present a Hamiltonian driven propagation for the Quantum Episodic Memory model developed by Brainerd (et al., 2015) for the episodic memory overdistribution in the experimental immediate item false memory paradigm (Brainerd and Reyna, 2008, 2010, 2015). Following the Hamiltonian method of Busemeyer and Bruza (2012) our model adds time-evolution of the perceived memory state through the stages of the experimental process based on psychologically interpretable parameters - γ_c for recollection capability of cues, κ_p for bias or description-dependence by probes and β for the average gist component in the memory state at start. With seven parameters the Hamiltonian model shows good accuracy of predictions both in the EOD-disjunction and in the EOD-subadditivity paradigm. We noticed either an outspoken preponderance of the gist over verbatim trace, or the opposite, in the initial memory state when β is real. Only for complex β a mix of both traces is present in the initial state for the EOD-subadditivity paradigm.

Ising formulation of associative memory models and quantum annealing recall

NASA Astrophysics Data System (ADS)

Santra, Siddhartha; Shehab, Omar; Balu, Radhakrishnan

2017-12-01

Associative memory models, in theoretical neuro- and computer sciences, can generally store at most a linear number of memories. Recalling memories in these models can be understood as retrieval of the energy minimizing configuration of classical Ising spins, closest in Hamming distance to an imperfect input memory, where the energy landscape is determined by the set of stored memories. We present an Ising formulation for associative memory models and consider the problem of memory recall using quantum annealing. We show that allowing for input-dependent energy landscapes allows storage of up to an exponential number of memories (in terms of the number of neurons). Further, we show how quantum annealing may naturally be used for recall tasks in such input-dependent energy landscapes, although the recall time may increase with the number of stored memories. Theoretically, we obtain the radius of attractor basins R (N ) and the capacity C (N ) of such a scheme and their tradeoffs. Our calculations establish that for randomly chosen memories the capacity of our model using the Hebbian learning rule as a function of problem size can be expressed as C (N ) =O (eC1N) , C1≥0 , and succeeds on randomly chosen memory sets with a probability of (1 -e-C2N) , C2≥0 with C1+C2=(0.5-f ) 2/(1 -f ) , where f =R (N )/N , 0 ≤f ≤0.5 , is the radius of attraction in terms of the Hamming distance of an input probe from a stored memory as a fraction of the problem size. We demonstrate the application of this scheme on a programmable quantum annealing device, the D-wave processor.

Memory mechanisms supporting syntactic comprehension.

PubMed

Caplan, David; Waters, Gloria

2013-04-01

Efforts to characterize the memory system that supports sentence comprehension have historically drawn extensively on short-term memory as a source of mechanisms that might apply to sentences. The focus of these efforts has changed significantly in the past decade. As a result of changes in models of short-term working memory (ST-WM) and developments in models of sentence comprehension, the effort to relate entire components of an ST-WM system, such as those in the model developed by Baddeley (Nature Reviews Neuroscience 4: 829-839, 2003) to sentence comprehension has largely been replaced by an effort to relate more specific mechanisms found in modern models of ST-WM to memory processes that support one aspect of sentence comprehension--the assignment of syntactic structure (parsing) and its use in determining sentence meaning (interpretation) during sentence comprehension. In this article, we present the historical background to recent studies of the memory mechanisms that support parsing and interpretation and review recent research into this relation. We argue that the results of this research do not converge on a set of mechanisms derived from ST-WM that apply to parsing and interpretation. We argue that the memory mechanisms supporting parsing and interpretation have features that characterize another memory system that has been postulated to account for skilled performance-long-term working memory. We propose a model of the relation of different aspects of parsing and interpretation to ST-WM and long-term working memory.

The role of cognitive reserve and memory self-efficacy in compensatory strategy use: A structural equation approach.

PubMed

Simon, Christa; Schmitter-Edgecombe, Maureen

2016-08-01

The use of compensatory strategies plays an important role in the ability of older adults to adapt to late-life memory changes. Even with the benefits associated with compensatory strategy use, little research has explored specific mechanisms associated with memory performance and compensatory strategies. Rather than an individual's objective memory performance directly predicting their use of compensatory strategies, it is possible that some other variables are indirectly influencing that relationship. The purpose of this study was to: (a) examine the moderating effects of cognitive reserve (CR) and (b) evaluate the potential mediating effects of memory self-efficacy on the relationship between objective memory performance and compensatory strategy use. Two structural equation models (SEM) were used to evaluate CR (latent moderator model) and memory self-efficacy (mediator model) in a sample of 155 community-dwelling older adults over the age of 55. The latent variable moderator model indicated that CR was not substantiated as a moderator variable in this sample (p = .861). However, memory self-efficacy significantly mediated the association between objective memory performance and compensatory strategy use (β = .22, 95% confidence interval, CI [.002, .437]). More specifically, better objective memory was associated with lower compensatory strategy use because of its relation to higher memory self-efficacy. These findings provide initial support for an explanatory framework of the relation between objective memory and compensatory strategy use in a healthy older adult population by identifying the importance of an individual's memory perceptions.

XMI2USE: A Tool for Transforming XMI to USE Specifications

NASA Astrophysics Data System (ADS)

Sun, Wuliang; Song, Eunjee; Grabow, Paul C.; Simmonds, Devon M.

The UML-based Specification Environment (USE) tool supports syntactic analysis, type checking, consistency checking, and dynamic validation of invariants and pre-/post conditions specified in the Object Constraint Language (OCL). Due to its animation and analysis power, it is useful when checking critical non-functional properties such as security policies. However, the USE tool requires one to specify (i.e., "write") a model using its own textual language and does not allow one to import any model specification files created by other UML modeling tools. Hence, to make the best use of existing UML tools, we often create a model with OCL constraints using a modeling tool such as the IBM Rational Software Architect (RSA) and then use the USE tool for model validation. This approach, however, requires a manual transformation between the specifications of two different tool formats, which is error-prone and diminishes the benefit of automated model-level validations. In this paper, we describe our own implementation of a specification transformation engine that is based on the Model Driven Architecture (MDA) framework and currently supports automatic tool-level transformations from RSA to USE.

Analytical network process based optimum cluster head selection in wireless sensor network.

PubMed

Farman, Haleem; Javed, Huma; Jan, Bilal; Ahmad, Jamil; Ali, Shaukat; Khalil, Falak Naz; Khan, Murad

2017-01-01

Wireless Sensor Networks (WSNs) are becoming ubiquitous in everyday life due to their applications in weather forecasting, surveillance, implantable sensors for health monitoring and other plethora of applications. WSN is equipped with hundreds and thousands of small sensor nodes. As the size of a sensor node decreases, critical issues such as limited energy, computation time and limited memory become even more highlighted. In such a case, network lifetime mainly depends on efficient use of available resources. Organizing nearby nodes into clusters make it convenient to efficiently manage each cluster as well as the overall network. In this paper, we extend our previous work of grid-based hybrid network deployment approach, in which merge and split technique has been proposed to construct network topology. Constructing topology through our proposed technique, in this paper we have used analytical network process (ANP) model for cluster head selection in WSN. Five distinct parameters: distance from nodes (DistNode), residual energy level (REL), distance from centroid (DistCent), number of times the node has been selected as cluster head (TCH) and merged node (MN) are considered for CH selection. The problem of CH selection based on these parameters is tackled as a multi criteria decision system, for which ANP method is used for optimum cluster head selection. Main contribution of this work is to check the applicability of ANP model for cluster head selection in WSN. In addition, sensitivity analysis is carried out to check the stability of alternatives (available candidate nodes) and their ranking for different scenarios. The simulation results show that the proposed method outperforms existing energy efficient clustering protocols in terms of optimum CH selection and minimizing CH reselection process that results in extending overall network lifetime. This paper analyzes that ANP method used for CH selection with better understanding of the dependencies of different components involved in the evaluation process.

Analytical network process based optimum cluster head selection in wireless sensor network

PubMed Central

Javed, Huma; Jan, Bilal; Ahmad, Jamil; Ali, Shaukat; Khalil, Falak Naz; Khan, Murad

2017-01-01

Wireless Sensor Networks (WSNs) are becoming ubiquitous in everyday life due to their applications in weather forecasting, surveillance, implantable sensors for health monitoring and other plethora of applications. WSN is equipped with hundreds and thousands of small sensor nodes. As the size of a sensor node decreases, critical issues such as limited energy, computation time and limited memory become even more highlighted. In such a case, network lifetime mainly depends on efficient use of available resources. Organizing nearby nodes into clusters make it convenient to efficiently manage each cluster as well as the overall network. In this paper, we extend our previous work of grid-based hybrid network deployment approach, in which merge and split technique has been proposed to construct network topology. Constructing topology through our proposed technique, in this paper we have used analytical network process (ANP) model for cluster head selection in WSN. Five distinct parameters: distance from nodes (DistNode), residual energy level (REL), distance from centroid (DistCent), number of times the node has been selected as cluster head (TCH) and merged node (MN) are considered for CH selection. The problem of CH selection based on these parameters is tackled as a multi criteria decision system, for which ANP method is used for optimum cluster head selection. Main contribution of this work is to check the applicability of ANP model for cluster head selection in WSN. In addition, sensitivity analysis is carried out to check the stability of alternatives (available candidate nodes) and their ranking for different scenarios. The simulation results show that the proposed method outperforms existing energy efficient clustering protocols in terms of optimum CH selection and minimizing CH reselection process that results in extending overall network lifetime. This paper analyzes that ANP method used for CH selection with better understanding of the dependencies of different components involved in the evaluation process. PMID:28719616

The Generalized Quantum Episodic Memory Model.

PubMed

Trueblood, Jennifer S; Hemmer, Pernille

2017-11-01

Recent evidence suggests that experienced events are often mapped to too many episodic states, including those that are logically or experimentally incompatible with one another. For example, episodic over-distribution patterns show that the probability of accepting an item under different mutually exclusive conditions violates the disjunction rule. A related example, called subadditivity, occurs when the probability of accepting an item under mutually exclusive and exhaustive instruction conditions sums to a number >1. Both the over-distribution effect and subadditivity have been widely observed in item and source-memory paradigms. These phenomena are difficult to explain using standard memory frameworks, such as signal-detection theory. A dual-trace model called the over-distribution (OD) model (Brainerd & Reyna, 2008) can explain the episodic over-distribution effect, but not subadditivity. Our goal is to develop a model that can explain both effects. In this paper, we propose the Generalized Quantum Episodic Memory (GQEM) model, which extends the Quantum Episodic Memory (QEM) model developed by Brainerd, Wang, and Reyna (2013). We test GQEM by comparing it to the OD model using data from a novel item-memory experiment and a previously published source-memory experiment (Kellen, Singmann, & Klauer, 2014) examining the over-distribution effect. Using the best-fit parameters from the over-distribution experiments, we conclude by showing that the GQEM model can also account for subadditivity. Overall these results add to a growing body of evidence suggesting that quantum probability theory is a valuable tool in modeling recognition memory. Copyright © 2016 Cognitive Science Society, Inc.

Evaluation of properties over phylogenetic trees using stochastic logics.

PubMed

Requeno, José Ignacio; Colom, José Manuel

2016-06-14

Model checking has been recently introduced as an integrated framework for extracting information of the phylogenetic trees using temporal logics as a querying language, an extension of modal logics that imposes restrictions of a boolean formula along a path of events. The phylogenetic tree is considered a transition system modeling the evolution as a sequence of genomic mutations (we understand mutation as different ways that DNA can be changed), while this kind of logics are suitable for traversing it in a strict and exhaustive way. Given a biological property that we desire to inspect over the phylogeny, the verifier returns true if the specification is satisfied or a counterexample that falsifies it. However, this approach has been only considered over qualitative aspects of the phylogeny. In this paper, we repair the limitations of the previous framework for including and handling quantitative information such as explicit time or probability. To this end, we apply current probabilistic continuous-time extensions of model checking to phylogenetics. We reinterpret a catalog of qualitative properties in a numerical way, and we also present new properties that couldn't be analyzed before. For instance, we obtain the likelihood of a tree topology according to a mutation model. As case of study, we analyze several phylogenies in order to obtain the maximum likelihood with the model checking tool PRISM. In addition, we have adapted the software for optimizing the computation of maximum likelihoods. We have shown that probabilistic model checking is a competitive framework for describing and analyzing quantitative properties over phylogenetic trees. This formalism adds soundness and readability to the definition of models and specifications. Besides, the existence of model checking tools hides the underlying technology, omitting the extension, upgrade, debugging and maintenance of a software tool to the biologists. A set of benchmarks justify the feasibility of our approach.

How Fuzzy-Trace Theory Predicts True and False Memories for Words, Sentences, and Narratives

PubMed Central

Reyna, Valerie F.; Corbin, Jonathan C.; Weldon, Rebecca B.; Brainerd, Charles J.

2016-01-01

Fuzzy-trace theory posits independent verbatim and gist memory processes, a distinction that has implications for such applied topics as eyewitness testimony. This distinction between precise, literal verbatim memory and meaning-based, intuitive gist accounts for memory paradoxes including dissociations between true and false memory, false memories outlasting true memories, and developmental increases in false memory. We provide an overview of fuzzy-trace theory, and, using mathematical modeling, also present results demonstrating verbatim and gist memory in true and false recognition of narrative sentences and inferences. Results supported fuzzy-trace theory's dual-process view of memory: verbatim memory was relied on to reject meaning-consistent, but unpresented, sentences (via recollection rejection). However, verbatim memory was often not retrieved, and gist memory supported acceptance of these sentences (via similarity judgment and phantom recollection). Thus, mathematical models of words can be extended to explain memory for complex stimuli, such as narratives, the kind of memory interrogated in law. PMID:27042402

Memory-induced nonlinear dynamics of excitation in cardiac diseases.

PubMed

Landaw, Julian; Qu, Zhilin

2018-04-01

Excitable cells, such as cardiac myocytes, exhibit short-term memory, i.e., the state of the cell depends on its history of excitation. Memory can originate from slow recovery of membrane ion channels or from accumulation of intracellular ion concentrations, such as calcium ion or sodium ion concentration accumulation. Here we examine the effects of memory on excitation dynamics in cardiac myocytes under two diseased conditions, early repolarization and reduced repolarization reserve, each with memory from two different sources: slow recovery of a potassium ion channel and slow accumulation of the intracellular calcium ion concentration. We first carry out computer simulations of action potential models described by differential equations to demonstrate complex excitation dynamics, such as chaos. We then develop iterated map models that incorporate memory, which accurately capture the complex excitation dynamics and bifurcations of the action potential models. Finally, we carry out theoretical analyses of the iterated map models to reveal the underlying mechanisms of memory-induced nonlinear dynamics. Our study demonstrates that the memory effect can be unmasked or greatly exacerbated under certain diseased conditions, which promotes complex excitation dynamics, such as chaos. The iterated map models reveal that memory converts a monotonic iterated map function into a nonmonotonic one to promote the bifurcations leading to high periodicity and chaos.

Memory-induced nonlinear dynamics of excitation in cardiac diseases

NASA Astrophysics Data System (ADS)

Landaw, Julian; Qu, Zhilin

2018-04-01

Excitable cells, such as cardiac myocytes, exhibit short-term memory, i.e., the state of the cell depends on its history of excitation. Memory can originate from slow recovery of membrane ion channels or from accumulation of intracellular ion concentrations, such as calcium ion or sodium ion concentration accumulation. Here we examine the effects of memory on excitation dynamics in cardiac myocytes under two diseased conditions, early repolarization and reduced repolarization reserve, each with memory from two different sources: slow recovery of a potassium ion channel and slow accumulation of the intracellular calcium ion concentration. We first carry out computer simulations of action potential models described by differential equations to demonstrate complex excitation dynamics, such as chaos. We then develop iterated map models that incorporate memory, which accurately capture the complex excitation dynamics and bifurcations of the action potential models. Finally, we carry out theoretical analyses of the iterated map models to reveal the underlying mechanisms of memory-induced nonlinear dynamics. Our study demonstrates that the memory effect can be unmasked or greatly exacerbated under certain diseased conditions, which promotes complex excitation dynamics, such as chaos. The iterated map models reveal that memory converts a monotonic iterated map function into a nonmonotonic one to promote the bifurcations leading to high periodicity and chaos.

Cholinergic modulation of cognitive processing: insights drawn from computational models

PubMed Central

Newman, Ehren L.; Gupta, Kishan; Climer, Jason R.; Monaghan, Caitlin K.; Hasselmo, Michael E.

2012-01-01

Acetylcholine plays an important role in cognitive function, as shown by pharmacological manipulations that impact working memory, attention, episodic memory, and spatial memory function. Acetylcholine also shows striking modulatory influences on the cellular physiology of hippocampal and cortical neurons. Modeling of neural circuits provides a framework for understanding how the cognitive functions may arise from the influence of acetylcholine on neural and network dynamics. We review the influences of cholinergic manipulations on behavioral performance in working memory, attention, episodic memory, and spatial memory tasks, the physiological effects of acetylcholine on neural and circuit dynamics, and the computational models that provide insight into the functional relationships between the physiology and behavior. Specifically, we discuss the important role of acetylcholine in governing mechanisms of active maintenance in working memory tasks and in regulating network dynamics important for effective processing of stimuli in attention and episodic memory tasks. We also propose that theta rhythm plays a crucial role as an intermediary between the physiological influences of acetylcholine and behavior in episodic and spatial memory tasks. We conclude with a synthesis of the existing modeling work and highlight future directions that are likely to be rewarding given the existing state of the literature for both empiricists and modelers. PMID:22707936

Real-Time Reconfigurable Adaptive Speech Recognition Command and Control Apparatus and Method

NASA Technical Reports Server (NTRS)

Salazar, George A. (Inventor); Haynes, Dena S. (Inventor); Sommers, Marc J. (Inventor)

1998-01-01

An adaptive speech recognition and control system and method for controlling various mechanisms and systems in response to spoken instructions and in which spoken commands are effective to direct the system into appropriate memory nodes, and to respective appropriate memory templates corresponding to the voiced command is discussed. Spoken commands from any of a group of operators for which the system is trained may be identified, and voice templates are updated as required in response to changes in pronunciation and voice characteristics over time of any of the operators for which the system is trained. Provisions are made for both near-real-time retraining of the system with respect to individual terms which are determined not be positively identified, and for an overall system training and updating process in which recognition of each command and vocabulary term is checked, and in which the memory templates are retrained if necessary for respective commands or vocabulary terms with respect to an operator currently using the system. In one embodiment, the system includes input circuitry connected to a microphone and including signal processing and control sections for sensing the level of vocabulary recognition over a given period and, if recognition performance falls below a given level, processing audio-derived signals for enhancing recognition performance of the system.

Intrusive imagery in severe health anxiety: Prevalence, nature and links with memories and maintenance cycles

PubMed Central

Muse, Kate; McManus, Freda; Hackmann, Ann; Williams, Matthew; Williams, Mark

2010-01-01

Increased understanding of the nature and role of intrusive imagery has contributed to the development of effective treatment protocols for some anxiety disorders. However, intrusive imagery in severe health anxiety (hypochondriasis) has been comparatively neglected. Hence, the current study investigates the prevalence, nature and content of intrusive imagery in 55 patients who met DSM-IV-TR (APA, 2000) criteria for the diagnosis of hypochondriasis. A semi-structured interview was used to assess the prevalence, nature and possible role of intrusive imagery in this disorder. Over 78% of participants reported experiencing recurrent, distressing intrusive images, the majority (72%) of which either were a memory of an earlier event or were strongly associated with a memory. The images tended to be future orientated, and were reliably categorised into four themes: i) being told ‘the bad news’ that you have a serious/life threatening-illness (6.9%), ii) suffering from a serious or life-threatening illness (34.5%), iii) death and dying due to illness (22.4%) and iv) impact of own death or serious illness on loved ones (36.2%). Participants reported responding to experiencing intrusive images by engaging in avoidance, checking, reassurance seeking, distraction and rumination. Potential treatment implications and links to maintenance cycles are considered. PMID:20627270

Evident cognitive impairments in seemingly recovered patients after midazolam-based light sedation during diagnostic endoscopy.

PubMed

Hsu, Yen-Hsuan; Lin, Feng-Sheng; Yang, Chi-Cheng; Lin, Chih-Peng; Hua, Mau-Sun; Sun, Wei-Zen

2015-06-01

Midazolam is a widely used sedative agent during colonoscopy, with cognitive toxicity. However, the potential cognitive hazard of midazolam-based light sedation has not been sufficiently examined. We aimed to examine the cognitive safety and vulnerability profile under midazolam light sedation, with a particular focus on individual variations. We conducted a prospective case-controlled study in an academic hospital. In total, 30 patients undergoing sedative colonoscopy as part of a health check-up were recruited. Neuropsychological testing on the full cognitive spectrum was evaluated at 15 minutes and 120 minutes after low-dose midazolam administration. The modified reliable change index (RCI) was used for intrapersonal comparisons and controlling for practice effects. Midazolam affected psychomotor speed (48%), memory (40%), learning (32%), working memory (17%), and sustained attention (11%), while sparing orientation and the fluency aspect of executive function at the acute stage. Residual memory (10%) and learning (10%) impairments at 2 hours after administration were evidenced in some patients. The three object recall and digit symbol coding tests can serve as useful screening tools. Midazolam-based light sedation induced selective cognitive impairments and prolonged cognitive impairments occurred in patients with advanced age. A longer observation time and further screening were recommended for patients due to their at risk state. Copyright © 2013. Published by Elsevier B.V.

An interference model of visual working memory.

PubMed

Oberauer, Klaus; Lin, Hsuan-Yu

2017-01-01

The article introduces an interference model of working memory for information in a continuous similarity space, such as the features of visual objects. The model incorporates the following assumptions: (a) Probability of retrieval is determined by the relative activation of each retrieval candidate at the time of retrieval; (b) activation comes from 3 sources in memory: cue-based retrieval using context cues, context-independent memory for relevant contents, and noise; (c) 1 memory object and its context can be held in the focus of attention, where it is represented with higher precision, and partly shielded against interference. The model was fit to data from 4 continuous-reproduction experiments testing working memory for colors or orientations. The experiments involved variations of set size, kind of context cues, precueing, and retro-cueing of the to-be-tested item. The interference model fit the data better than 2 competing models, the Slot-Averaging model and the Variable-Precision resource model. The interference model also fared well in comparison to several new models incorporating alternative theoretical assumptions. The experiments confirm 3 novel predictions of the interference model: (a) Nontargets intrude in recall to the extent that they are close to the target in context space; (b) similarity between target and nontarget features improves recall, and (c) precueing-but not retro-cueing-the target substantially reduces the set-size effect. The success of the interference model shows that working memory for continuous visual information works according to the same principles as working memory for more discrete (e.g., verbal) contents. Data and model codes are available at https://osf.io/wgqd5/. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

GPUs benchmarking in subpixel image registration algorithm

NASA Astrophysics Data System (ADS)

Sanz-Sabater, Martin; Picazo-Bueno, Jose Angel; Micó, Vicente; Ferrerira, Carlos; Granero, Luis; Garcia, Javier

2015-05-01

Image registration techniques are used among different scientific fields, like medical imaging or optical metrology. The straightest way to calculate shifting between two images is using the cross correlation, taking the highest value of this correlation image. Shifting resolution is given in whole pixels which cannot be enough for certain applications. Better results can be achieved interpolating both images, as much as the desired resolution we want to get, and applying the same technique described before, but the memory needed by the system is significantly higher. To avoid memory consuming we are implementing a subpixel shifting method based on FFT. With the original images, subpixel shifting can be achieved multiplying its discrete Fourier transform by a linear phase with different slopes. This method is high time consuming method because checking a concrete shifting means new calculations. The algorithm, highly parallelizable, is very suitable for high performance computing systems. GPU (Graphics Processing Unit) accelerated computing became very popular more than ten years ago because they have hundreds of computational cores in a reasonable cheap card. In our case, we are going to register the shifting between two images, doing the first approach by FFT based correlation, and later doing the subpixel approach using the technique described before. We consider it as `brute force' method. So we will present a benchmark of the algorithm consisting on a first approach (pixel resolution) and then do subpixel resolution approaching, decreasing the shifting step in every loop achieving a high resolution in few steps. This program will be executed in three different computers. At the end, we will present the results of the computation, with different kind of CPUs and GPUs, checking the accuracy of the method, and the time consumed in each computer, discussing the advantages, disadvantages of the use of GPUs.

Differentiating the Differentiation Models: A Comparison of the Retrieving Effectively from Memory Model (REM) and the Subjective Likelihood Model (SLiM)

ERIC Educational Resources Information Center

Criss, Amy H.; McClelland, James L.

2006-01-01

The subjective likelihood model [SLiM; McClelland, J. L., & Chappell, M. (1998). Familiarity breeds differentiation: a subjective-likelihood approach to the effects of experience in recognition memory. "Psychological Review," 105(4), 734-760.] and the retrieving effectively from memory model [REM; Shiffrin, R. M., & Steyvers, M. (1997). A model…

Model Checking Verification and Validation at JPL and the NASA Fairmont IV and V Facility

NASA Technical Reports Server (NTRS)

Schneider, Frank; Easterbrook, Steve; Callahan, Jack; Montgomery, Todd

1999-01-01

We show how a technology transfer effort was carried out. The successful use of model checking on a pilot JPL flight project demonstrates the usefulness and the efficacy of the approach. The pilot project was used to model a complex spacecraft controller. Software design and implementation validation were carried out successfully. To suggest future applications we also show how the implementation validation step can be automated. The effort was followed by the formal introduction of the modeling technique as a part of the JPL Quality Assurance process.

Memory consolidation from seconds to weeks: a three-stage neural network model with autonomous reinstatement dynamics

PubMed Central

Fiebig, Florian; Lansner, Anders

2014-01-01

Declarative long-term memories are not created in an instant. Gradual stabilization and temporally shifting dependence of acquired declarative memories in different brain regions—called systems consolidation—can be tracked in time by lesion experiments. The observation of temporally graded retrograde amnesia (RA) following hippocampal lesions points to a gradual transfer of memory from hippocampus to neocortical long-term memory. Spontaneous reactivations of hippocampal memories, as observed in place cell reactivations during slow-wave-sleep, are supposed to drive neocortical reinstatements and facilitate this process. We propose a functional neural network implementation of these ideas and furthermore suggest an extended three-state framework that includes the prefrontal cortex (PFC). It bridges the temporal chasm between working memory percepts on the scale of seconds and consolidated long-term memory on the scale of weeks or months. We show that our three-stage model can autonomously produce the necessary stochastic reactivation dynamics for successful episodic memory consolidation. The resulting learning system is shown to exhibit classical memory effects seen in experimental studies, such as retrograde and anterograde amnesia (AA) after simulated hippocampal lesioning; furthermore the model reproduces peculiar biological findings on memory modulation, such as retrograde facilitation of memory after suppressed acquisition of new long-term memories—similar to the effects of benzodiazepines on memory. PMID:25071536

Philosophy and the practice of Bayesian statistics

PubMed Central

Gelman, Andrew; Shalizi, Cosma Rohilla

2015-01-01

A substantial school in the philosophy of science identifies Bayesian inference with inductive inference and even rationality as such, and seems to be strengthened by the rise and practical success of Bayesian statistics. We argue that the most successful forms of Bayesian statistics do not actually support that particular philosophy but rather accord much better with sophisticated forms of hypothetico-deductivism. We examine the actual role played by prior distributions in Bayesian models, and the crucial aspects of model checking and model revision, which fall outside the scope of Bayesian confirmation theory. We draw on the literature on the consistency of Bayesian updating and also on our experience of applied work in social science. Clarity about these matters should benefit not just philosophy of science, but also statistical practice. At best, the inductivist view has encouraged researchers to fit and compare models without checking them; at worst, theorists have actively discouraged practitioners from performing model checking because it does not fit into their framework. PMID:22364575

Philosophy and the practice of Bayesian statistics.

PubMed

Gelman, Andrew; Shalizi, Cosma Rohilla

2013-02-01

A substantial school in the philosophy of science identifies Bayesian inference with inductive inference and even rationality as such, and seems to be strengthened by the rise and practical success of Bayesian statistics. We argue that the most successful forms of Bayesian statistics do not actually support that particular philosophy but rather accord much better with sophisticated forms of hypothetico-deductivism. We examine the actual role played by prior distributions in Bayesian models, and the crucial aspects of model checking and model revision, which fall outside the scope of Bayesian confirmation theory. We draw on the literature on the consistency of Bayesian updating and also on our experience of applied work in social science. Clarity about these matters should benefit not just philosophy of science, but also statistical practice. At best, the inductivist view has encouraged researchers to fit and compare models without checking them; at worst, theorists have actively discouraged practitioners from performing model checking because it does not fit into their framework. © 2012 The British Psychological Society.

A Model-Driven Approach for Telecommunications Network Services Definition

NASA Astrophysics Data System (ADS)

Chiprianov, Vanea; Kermarrec, Yvon; Alff, Patrick D.

Present day Telecommunications market imposes a short concept-to-market time for service providers. To reduce it, we propose a computer-aided, model-driven, service-specific tool, with support for collaborative work and for checking properties on models. We started by defining a prototype of the Meta-model (MM) of the service domain. Using this prototype, we defined a simple graphical modeling language specific for service designers. We are currently enlarging the MM of the domain using model transformations from Network Abstractions Layers (NALs). In the future, we will investigate approaches to ensure the support for collaborative work and for checking properties on models.

Through the Immune Looking Glass: A Model for Brain Memory Strategies

PubMed Central

Sánchez-Ramón, Silvia; Faure, Florence

2016-01-01

The immune system (IS) and the central nervous system (CNS) are complex cognitive networks involved in defining the identity (self) of the individual through recognition and memory processes that enable one to anticipate responses to stimuli. Brain memory has traditionally been classified as either implicit or explicit on psychological and anatomical grounds, with reminiscences of the evolutionarily-based innate-adaptive IS responses. Beyond the multineuronal networks of the CNS, we propose a theoretical model of brain memory integrating the CNS as a whole. This is achieved by analogical reasoning between the operational rules of recognition and memory processes in both systems, coupled to an evolutionary analysis. In this new model, the hippocampus is no longer specifically ascribed to explicit memory but rather it both becomes part of the innate (implicit) memory system and tightly controls the explicit memory system. Alike the antigen presenting cells for the IS, the hippocampus would integrate transient and pseudo-specific (i.e., danger-fear) memories and would drive the formation of long-term and highly specific or explicit memories (i.e., the taste of the Proust’s madeleine cake) by the more complex and recent, evolutionarily speaking, neocortex. Experimental and clinical evidence is provided to support the model. We believe that the singularity of this model’s approximation could help to gain a better understanding of the mechanisms operating in brain memory strategies from a large-scale network perspective. PMID:26869886

Memory Effects on Movement Behavior in Animal Foraging

PubMed Central

Bracis, Chloe; Gurarie, Eliezer; Van Moorter, Bram; Goodwin, R. Andrew

2015-01-01

An individual’s choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems. PMID:26288228

The role of memory in the relationship between attention toward thin-ideal media and body dissatisfaction.

PubMed

Jiang, Michelle Y W; Vartanian, Lenny R

2016-03-01

This study examined the causal relationship between attention and memory bias toward thin-body images, and the indirect effect of attending to thin-body images on women's body dissatisfaction via memory. In a 2 (restrained vs. unrestrained eaters) × 2 (long vs. short exposure) quasi-experimental design, female participants (n = 90) were shown images of thin models for either 7 s or 150 ms, and then completed a measure of body dissatisfaction and a recognition test to assess their memory for the images. Both restrained and unrestrained eaters in the long exposure condition had better recognition memory for images of thin models than did those in the short exposure condition. Better recognition memory for images of thin models was associated with lower body dissatisfaction. Finally, exposure duration to images of thin models had an indirect effect on body dissatisfaction through recognition memory. These findings suggest that memory for body-related information may be more critical in influencing women's body image than merely the exposure itself, and that targeting memory bias might enhance the effectiveness of cognitive bias modification programs.

Memory Effects on Movement Behavior in Animal Foraging.

PubMed

Bracis, Chloe; Gurarie, Eliezer; Van Moorter, Bram; Goodwin, R Andrew

2015-01-01

An individual's choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.

Acute effects of alcohol on intrusive memory development and viewpoint dependence in spatial memory support a dual representation model.

PubMed

Bisby, James A; King, John A; Brewin, Chris R; Burgess, Neil; Curran, H Valerie

2010-08-01

A dual representation model of intrusive memory proposes that personally experienced events give rise to two types of representation: an image-based, egocentric representation based on sensory-perceptual features; and a more abstract, allocentric representation that incorporates spatiotemporal context. The model proposes that intrusions reflect involuntary reactivation of egocentric representations in the absence of a corresponding allocentric representation. We tested the model by investigating the effect of alcohol on intrusive memories and, concurrently, on egocentric and allocentric spatial memory. With a double-blind independent group design participants were administered alcohol (.4 or .8 g/kg) or placebo. A virtual environment was used to present objects and test recognition memory from the same viewpoint as presentation (tapping egocentric memory) or a shifted viewpoint (tapping allocentric memory). Participants were also exposed to a trauma video and required to detail intrusive memories for 7 days, after which explicit memory was assessed. There was a selective impairment of shifted-view recognition after the low dose of alcohol, whereas the high dose induced a global impairment in same-view and shifted-view conditions. Alcohol showed a dose-dependent inverted "U"-shaped effect on intrusions, with only the low dose increasing the number of intrusions, replicating previous work. When same-view recognition was intact, decrements in shifted-view recognition were associated with increases in intrusions. The differential effect of alcohol on intrusive memories and on same/shifted-view recognition support a dual representation model in which intrusions might reflect an imbalance between two types of memory representation. These findings highlight important clinical implications, given alcohol's involvement in real-life trauma. Copyright 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Using State Merging and State Pruning to Address the Path Explosion Problem Faced by Symbolic Execution

DTIC Science & Technology

2014-06-19

urgent and compelling. Recent efforts in this area automate program analysis techniques using model checking and symbolic execution [2, 5–7]. These...bounded model checking tool for x86 binary programs developed at the Air Force Institute of Technology (AFIT). Jiseki creates a bit-vector logic model based...assume there are n different paths through the function foo . The program could potentially call the function foo a bound number of times, resulting in n

`Unlearning' has a stabilizing effect in collective memories

NASA Astrophysics Data System (ADS)

Hopfield, J. J.; Feinstein, D. I.; Palmer, R. G.

1983-07-01

Crick and Mitchison1 have presented a hypothesis for the functional role of dream sleep involving an `unlearning' process. We have independently carried out mathematical and computer modelling of learning and `unlearning' in a collective neural network of 30-1,000 neurones. The model network has a content-addressable memory or `associative memory' which allows it to learn and store many memories. A particular memory can be evoked in its entirety when the network is stimulated by any adequate-sized subpart of the information of that memory2. But different memories of the same size are not equally easy to recall. Also, when memories are learned, spurious memories are also created and can also be evoked. Applying an `unlearning' process, similar to the learning processes but with a reversed sign and starting from a noise input, enhances the performance of the network in accessing real memories and in minimizing spurious ones. Although our model was not motivated by higher nervous function, our system displays behaviours which are strikingly parallel to those needed for the hypothesized role of `unlearning' in rapid eye movement (REM) sleep.

Memory as the "whole brain work": a large-scale model based on "oscillations in super-synergy".

PubMed

Başar, Erol

2005-01-01

According to recent trends, memory depends on several brain structures working in concert across many levels of neural organization; "memory is a constant work-in progress." The proposition of a brain theory based on super-synergy in neural populations is most pertinent for the understanding of this constant work in progress. This report introduces a new model on memory basing on the processes of EEG oscillations and Brain Dynamics. This model is shaped by the following conceptual and experimental steps: 1. The machineries of super-synergy in the whole brain are responsible for formation of sensory-cognitive percepts. 2. The expression "dynamic memory" is used for memory processes that evoke relevant changes in alpha, gamma, theta and delta activities. The concerted action of distributed multiple oscillatory processes provides a major key for understanding of distributed memory. It comprehends also the phyletic memory and reflexes. 3. The evolving memory, which incorporates reciprocal actions or reverberations in the APLR alliance and during working memory processes, is especially emphasized. 4. A new model related to "hierarchy of memories as a continuum" is introduced. 5. The notions of "longer activated memory" and "persistent memory" are proposed instead of long-term memory. 6. The new analysis to recognize faces emphasizes the importance of EEG oscillations in neurophysiology and Gestalt analysis. 7. The proposed basic framework called "Memory in the Whole Brain Work" emphasizes that memory and all brain functions are inseparable and are acting as a "whole" in the whole brain. 8. The role of genetic factors is fundamental in living system settings and oscillations and accordingly in memory, according to recent publications. 9. A link from the "whole brain" to "whole body," and incorporation of vegetative and neurological system, is proposed, EEG oscillations and ultraslow oscillations being a control parameter.

Sequence memory based on coherent spin-interaction neural networks.

PubMed

Xia, Min; Wong, W K; Wang, Zhijie

2014-12-01

Sequence information processing, for instance, the sequence memory, plays an important role on many functions of brain. In the workings of the human brain, the steady-state period is alterable. However, in the existing sequence memory models using heteroassociations, the steady-state period cannot be changed in the sequence recall. In this work, a novel neural network model for sequence memory with controllable steady-state period based on coherent spininteraction is proposed. In the proposed model, neurons fire collectively in a phase-coherent manner, which lets a neuron group respond differently to different patterns and also lets different neuron groups respond differently to one pattern. The simulation results demonstrating the performance of the sequence memory are presented. By introducing a new coherent spin-interaction sequence memory model, the steady-state period can be controlled by dimension parameters and the overlap between the input pattern and the stored patterns. The sequence storage capacity is enlarged by coherent spin interaction compared with the existing sequence memory models. Furthermore, the sequence storage capacity has an exponential relationship to the dimension of the neural network.

Competitive Trace Theory: A Role for the Hippocampus in Contextual Interference during Retrieval.

PubMed

Yassa, Michael A; Reagh, Zachariah M

2013-01-01

Much controversy exists regarding the role of the hippocampus in retrieval. The two dominant and competing accounts have been the Standard Model of Systems Consolidation (SMSC) and Multiple Trace Theory (MTT), which specifically make opposing predictions as to the necessity of the hippocampus for retrieval of remote memories. Under SMSC, memories eventually become independent of the hippocampus as they become more reliant on cortical connectivity, and thus the hippocampus is not required for retrieval of remote memories, only recent ones. MTT on the other hand claims that the hippocampus is always required no matter the age of the memory. We argue that this dissociation may be too simplistic, and a continuum model may be better suited to address the role of the hippocampus in retrieval of remote memories. Such a model is presented here with the main function of the hippocampus during retrieval being "recontextualization," or the reconstruction of memory using overlapping traces. As memories get older, they are decontextualized due to competition among partially overlapping traces and become more semantic and reliant on neocortical storage. In this framework dubbed the Competitive Trace Theory (CTT), consolidation events that lead to the strengthening of memories enhance conceptual knowledge (semantic memory) at the expense of contextual details (episodic memory). As a result, remote memories are more likely to have a stronger semantic representation. At the same time, remote memories are also more likely to include illusory details. The CTT is a novel candidate model that may provide some resolution to the memory consolidation debate.

Competitive Trace Theory: A Role for the Hippocampus in Contextual Interference during Retrieval

PubMed Central

Yassa, Michael A.; Reagh, Zachariah M.

2013-01-01

Much controversy exists regarding the role of the hippocampus in retrieval. The two dominant and competing accounts have been the Standard Model of Systems Consolidation (SMSC) and Multiple Trace Theory (MTT), which specifically make opposing predictions as to the necessity of the hippocampus for retrieval of remote memories. Under SMSC, memories eventually become independent of the hippocampus as they become more reliant on cortical connectivity, and thus the hippocampus is not required for retrieval of remote memories, only recent ones. MTT on the other hand claims that the hippocampus is always required no matter the age of the memory. We argue that this dissociation may be too simplistic, and a continuum model may be better suited to address the role of the hippocampus in retrieval of remote memories. Such a model is presented here with the main function of the hippocampus during retrieval being “recontextualization,” or the reconstruction of memory using overlapping traces. As memories get older, they are decontextualized due to competition among partially overlapping traces and become more semantic and reliant on neocortical storage. In this framework dubbed the Competitive Trace Theory (CTT), consolidation events that lead to the strengthening of memories enhance conceptual knowledge (semantic memory) at the expense of contextual details (episodic memory). As a result, remote memories are more likely to have a stronger semantic representation. At the same time, remote memories are also more likely to include illusory details. The CTT is a novel candidate model that may provide some resolution to the memory consolidation debate. PMID:23964216

Mobile, Virtual Enhancements for Rehabilitation (MOVER)

DTIC Science & Technology

2013-11-28

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

Testing Signal-Detection Models of Yes/No and Two-Alternative Forced-Choice Recognition Memory

ERIC Educational Resources Information Center

Jang, Yoonhee; Wixted, John T.; Huber, David E.

2009-01-01

The current study compared 3 models of recognition memory in their ability to generalize across yes/no and 2-alternative forced-choice (2AFC) testing. The unequal-variance signal-detection model assumes a continuous memory strength process. The dual-process signal-detection model adds a thresholdlike recollection process to a continuous…

Statistical Mechanics Model of the Speed - Accuracy Tradeoff in Spatial and Lexical Memory

NASA Astrophysics Data System (ADS)

Kaufman, Miron; Allen, Philip

2000-03-01

The molar neural network model of P. Allen, M. Kaufman, A. F. Smith, R. E. Popper, Psychology and Aging 13, 501 (1998) and Experimental Aging Research, 24, 307 (1998) is extended to incorporate reaction times. In our model the entropy associated with a particular task determines the reaction time. We use this molar neural model to directly analyze experimental data on episodic (spatial) memory and semantic (lexical) memory tasks. In particular we are interested in the effect of aging on the two types of memory. We find that there is no difference in performance levels for lexical memory tasks between younger and older adults. In the case spatial memory tasks we find that aging has a detrimental effect on the performance level. This work is supported by NIH/NIA grant AG09282-06.

Recognition and source memory as multivariate decision processes.

PubMed

Banks, W P

2000-07-01

Recognition memory, source memory, and exclusion performance are three important domains of study in memory, each with its own findings, it specific theoretical developments, and its separate research literature. It is proposed here that results from all three domains can be treated with a single analytic model. This article shows how to generate a comprehensive memory representation based on multidimensional signal detection theory and how to make predictions for each of these paradigms using decision axes drawn through the space. The detection model is simpler than the comparable multinomial model, it is more easily generalizable, and it does not make threshold assumptions. An experiment using the same memory set for all three tasks demonstrates the analysis and tests the model. The results show that some seemingly complex relations between the paradigms derive from an underlying simplicity of structure.

Why some colors appear more memorable than others: A model combining categories and particulars in color working memory.

PubMed

Bae, Gi-Yeul; Olkkonen, Maria; Allred, Sarah R; Flombaum, Jonathan I

2015-08-01

Categorization with basic color terms is an intuitive and universal aspect of color perception. Yet research on visual working memory capacity has largely assumed that only continuous estimates within color space are relevant to memory. As a result, the influence of color categories on working memory remains unknown. We propose a dual content model of color representation in which color matches to objects that are either present (perception) or absent (memory) integrate category representations along with estimates of specific values on a continuous scale ("particulars"). We develop and test the model through 4 experiments. In a first experiment pair, participants reproduce a color target, both with and without a delay, using a recently influential estimation paradigm. In a second experiment pair, we use standard methods in color perception to identify boundary and focal colors in the stimulus set. The main results are that responses drawn from working memory are significantly biased away from category boundaries and toward category centers. Importantly, the same pattern of results is present without a memory delay. The proposed dual content model parsimoniously explains these results, and it should replace prevailing single content models in studies of visual working memory. More broadly, the model and the results demonstrate how the main consequence of visual working memory maintenance is the amplification of category related biases and stimulus-specific variability that originate in perception. (c) 2015 APA, all rights reserved).

Apoptosis in the homeostasis of the immune system and in human immune mediated diseases.

PubMed

Giovannetti, A; Pierdominici, M; Di Iorio, A; Cianci, R; Murdaca, G; Puppo, F; Pandolfi, F; Paganelli, R

2008-01-01

The immune system has evolved sophisticated mechanisms controlling the development of responses to dangerous antigens while avoiding unnecessary attacks to innocuous, commensal or self antigens. The risk of autoimmunity is continuously checked and balanced against the risk of succumbing to exogenous infectious agents. It is therefore of paramount importance to understand the molecular events linking the breakdown of tolerance and the development of immunodeficiency. Apoptotic mechanisms are used to regulate the development of thymocytes, the shaping of T cell repertoire, its selection and the coordinate events leading to immune responses in the periphery. Moreover, they are at the heart of the homeostatic controls restoring T cell numbers and establishing T cell memory. T lymphocytes shift continuously from survival to death signals to ensure immune responsiveness without incurring in autoimmune damage. In this review we shall consider some key facts on the relationship of lymphopenia to autoreactivity, the mechanisms controlling positive and negative selection in the thymus, the role of apoptosis in selected primary immunodeficiency states and in systemic and organ-specific autoimmunity, with examples from human diseases and their animal models.

Robert Hooke's model of memory.

PubMed

Hintzman, Douglas L

2003-03-01

In 1682 the scientist and inventor Robert Hooke read a lecture to the Royal Society of London, in which he described a mechanistic model of human memory. Yet few psychologists today seem to have heard of Hooke's memory model. The lecture addressed questions of encoding, memory capacity, repetition, retrieval, and forgetting--some of these in a surprisingly modern way. Hooke's model shares several characteristics with the theory of Richard Semon, which came more than 200 years later, but it is more complete. Among the model's interesting properties are that (1) it allows for attention and other top-down influences on encoding; (2) it uses resonance to implement parallel, cue-dependent retrieval; (3) it explains memory for recency; (4) it offers a single-system account of repetition priming; and (5) the power law of forgetting can be derived from the model's assumptions in a straightforward way.

Ghosts in the machine: memory interference from the previous trial.

PubMed

Papadimitriou, Charalampos; Ferdoash, Afreen; Snyder, Lawrence H

2015-01-15

Previous memoranda can interfere with the memorization or storage of new information, a concept known as proactive interference. Studies of proactive interference typically use categorical memoranda and match-to-sample tasks with categorical measures such as the proportion of correct to incorrect responses. In this study we instead train five macaques in a spatial memory task with continuous memoranda and responses, allowing us to more finely probe working memory circuits. We first ask whether the memoranda from the previous trial result in proactive interference in an oculomotor delayed response task. We then characterize the spatial and temporal profile of this interference and ask whether this profile can be predicted by an attractor network model of working memory. We find that memory in the current trial shows a bias toward the location of the memorandum of the previous trial. The magnitude of this bias increases with the duration of the memory period within which it is measured. Our simulations using standard attractor network models of working memory show that these models easily replicate the spatial profile of the bias. However, unlike the behavioral findings, these attractor models show an increase in bias with the duration of the previous rather than the current memory period. To model a bias that increases with current trial duration we posit two separate memory stores, a rapidly decaying visual store that resists proactive interference effects and a sustained memory store that is susceptible to proactive interference. Copyright © 2015 the American Physiological Society.

Ghosts in the machine: memory interference from the previous trial

PubMed Central

Ferdoash, Afreen; Snyder, Lawrence H.

2014-01-01

Previous memoranda can interfere with the memorization or storage of new information, a concept known as proactive interference. Studies of proactive interference typically use categorical memoranda and match-to-sample tasks with categorical measures such as the proportion of correct to incorrect responses. In this study we instead train five macaques in a spatial memory task with continuous memoranda and responses, allowing us to more finely probe working memory circuits. We first ask whether the memoranda from the previous trial result in proactive interference in an oculomotor delayed response task. We then characterize the spatial and temporal profile of this interference and ask whether this profile can be predicted by an attractor network model of working memory. We find that memory in the current trial shows a bias toward the location of the memorandum of the previous trial. The magnitude of this bias increases with the duration of the memory period within which it is measured. Our simulations using standard attractor network models of working memory show that these models easily replicate the spatial profile of the bias. However, unlike the behavioral findings, these attractor models show an increase in bias with the duration of the previous rather than the current memory period. To model a bias that increases with current trial duration we posit two separate memory stores, a rapidly decaying visual store that resists proactive interference effects and a sustained memory store that is susceptible to proactive interference. PMID:25376781

BAIAP2 is related to emotional modulation of human memory strength.

PubMed

Luksys, Gediminas; Ackermann, Sandra; Coynel, David; Fastenrath, Matthias; Gschwind, Leo; Heck, Angela; Rasch, Bjoern; Spalek, Klara; Vogler, Christian; Papassotiropoulos, Andreas; de Quervain, Dominique

2014-01-01

Memory performance is the result of many distinct mental processes, such as memory encoding, forgetting, and modulation of memory strength by emotional arousal. These processes, which are subserved by partly distinct molecular profiles, are not always amenable to direct observation. Therefore, computational models can be used to make inferences about specific mental processes and to study their genetic underpinnings. Here we combined a computational model-based analysis of memory-related processes with high density genetic information derived from a genome-wide study in healthy young adults. After identifying the best-fitting model for a verbal memory task and estimating the best-fitting individual cognitive parameters, we found a common variant in the gene encoding the brain-specific angiogenesis inhibitor 1-associated protein 2 (BAIAP2) that was related to the model parameter reflecting modulation of verbal memory strength by negative valence. We also observed an association between the same genetic variant and a similar emotional modulation phenotype in a different population performing a picture memory task. Furthermore, using functional neuroimaging we found robust genotype-dependent differences in activity of the parahippocampal cortex that were specifically related to successful memory encoding of negative versus neutral information. Finally, we analyzed cortical gene expression data of 193 deceased subjects and detected significant BAIAP2 genotype-dependent differences in BAIAP2 mRNA levels. Our findings suggest that model-based dissociation of specific cognitive parameters can improve the understanding of genetic underpinnings of human learning and memory.

Memory mechanisms supporting syntactic comprehension

PubMed Central

Waters, Gloria

2013-01-01

Efforts to characterize the memory system that supports sentence comprehension have historically drawn extensively on short-term memory as a source of mechanisms that might apply to sentences. The focus of these efforts has changed significantly in the past decade. As a result of changes in models of short-term working memory (ST-WM) and developments in models of sentence comprehension, the effort to relate entire components of an ST-WM system, such as those in the model developed by Baddeley (Nature Reviews Neuroscience 4: 829–839, 2003) to sentence comprehension has largely been replaced by an effort to relate more specific mechanisms found in modern models of ST-WM to memory processes that support one aspect of sentence comprehension—the assignment of syntactic structure (parsing) and its use in determining sentence meaning (interpretation) during sentence comprehension. In this article, we present the historical background to recent studies of the memory mechanisms that support parsing and interpretation and review recent research into this relation. We argue that the results of this research do not converge on a set of mechanisms derived from ST-WM that apply to parsing and interpretation. We argue that the memory mechanisms supporting parsing and interpretation have features that characterize another memory system that has been postulated to account for skilled performance—long-term working memory. We propose a model of the relation of different aspects of parsing and interpretation to ST-WM and long-term working memory. PMID:23319178

The Infobiotics Workbench: an integrated in silico modelling platform for Systems and Synthetic Biology.

PubMed

Blakes, Jonathan; Twycross, Jamie; Romero-Campero, Francisco Jose; Krasnogor, Natalio

2011-12-01

The Infobiotics Workbench is an integrated software suite incorporating model specification, simulation, parameter optimization and model checking for Systems and Synthetic Biology. A modular model specification allows for straightforward creation of large-scale models containing many compartments and reactions. Models are simulated either using stochastic simulation or numerical integration, and visualized in time and space. Model parameters and structure can be optimized with evolutionary algorithms, and model properties calculated using probabilistic model checking. Source code and binaries for Linux, Mac and Windows are available at http://www.infobiotics.org/infobiotics-workbench/; released under the GNU General Public License (GPL) version 3. Natalio.Krasnogor@nottingham.ac.uk.

Modeling of Sonos Memory Cell Erase Cycle

NASA Technical Reports Server (NTRS)

Phillips, Thomas A.; MacLeond, Todd C.; Ho, Fat D.

2010-01-01

Silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile semiconductor memories (NVSMS) have many advantages. These memories are electrically erasable programmable read-only memories (EEPROMs). They utilize low programming voltages, endure extended erase/write cycles, are inherently resistant to radiation, and are compatible with high-density scaled CMOS for low power, portable electronics. The SONOS memory cell erase cycle was investigated using a nonquasi-static (NQS) MOSFET model. The SONOS floating gate charge and voltage, tunneling current, threshold voltage, and drain current were characterized during an erase cycle. Comparisons were made between the model predictions and experimental device data.

Changing Behavior by Memory Aids: A Social Psychological Model of Prospective Memory and Habit Development Tested with Dynamic Field Data

ERIC Educational Resources Information Center

Tobias, Robert

2009-01-01

This article presents a social psychological model of prospective memory and habit development. The model is based on relevant research literature, and its dynamics were investigated by computer simulations. Time-series data from a behavior-change campaign in Cuba were used for calibration and validation of the model. The model scored well in…

Content-Addressable Memory Storage by Neural Networks: A General Model and Global Liapunov Method,

DTIC Science & Technology

1988-03-01

point ex- ists. Liapunov functions were also described for Volterra -Lotka systems whose off-diagonal terms are relatively small (Kilmer, 1972...field, bidirectional associative memory, Volterra -Lotka, Gilpin-Ayala, and Eigen- Schuster models. The Cohen-Grossberg model thus defines a general...masking field, bidirectional associative memory. Volterra -Lotka, Gilpin-Ayala. and Eigen-Schuster models. The Cohen-Grossberg model thus defines a

Spatial working memory capacity predicts bias in estimates of location.

PubMed

Crawford, L Elizabeth; Landy, David; Salthouse, Timothy A

2016-09-01

Spatial memory research has attributed systematic bias in location estimates to a combination of a noisy memory trace with a prior structure that people impose on the space. Little is known about intraindividual stability and interindividual variation in these patterns of bias. In the current work, we align recent empirical and theoretical work on working memory capacity limits and spatial memory bias to generate the prediction that those with lower working memory capacity will show greater bias in memory of the location of a single item. Reanalyzing data from a large study of cognitive aging, we find support for this prediction. Fitting separate models to individuals' data revealed a surprising variety of strategies. Some were consistent with Bayesian models of spatial category use, however roughly half of participants biased estimates outward in a way not predicted by current models and others seemed to combine these strategies. These analyses highlight the importance of studying individuals when developing general models of cognition. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Spatial Working Memory Capacity Predicts Bias in Estimates of Location

PubMed Central

Crawford, L. Elizabeth; Landy, David H.; Salthouse, Timothy A.

2016-01-01

Spatial memory research has attributed systematic bias in location estimates to a combination of a noisy memory trace with a prior structure that people impose on the space. Little is known about intra-individual stability and inter-individual variation in these patterns of bias. In the current work we align recent empirical and theoretical work on working memory capacity limits and spatial memory bias to generate the prediction that those with lower working memory capacity will show greater bias in memory of the location of a single item. Reanalyzing data from a large study of cognitive aging, we find support for this prediction. Fitting separate models to individuals’ data revealed a surprising variety of strategies. Some were consistent with Bayesian models of spatial category use, however roughly half of participants biased estimates outward in a way not predicted by current models and others seemed to combine these strategies. These analyses highlight the importance of studying individuals when developing general models of cognition. PMID:26900708

A Memory-Based Model of Hick's Law

ERIC Educational Resources Information Center

Schneider, Darryl W.; Anderson, John R.

2011-01-01

We propose and evaluate a memory-based model of Hick's law, the approximately linear increase in choice reaction time with the logarithm of set size (the number of stimulus-response alternatives). According to the model, Hick's law reflects a combination of associative interference during retrieval from declarative memory and occasional savings…

A multiprocessor computer simulation model employing a feedback scheduler/allocator for memory space and bandwidth matching and TMR processing

NASA Technical Reports Server (NTRS)

Bradley, D. B.; Irwin, J. D.

1974-01-01

A computer simulation model for a multiprocessor computer is developed that is useful for studying the problem of matching multiprocessor's memory space, memory bandwidth and numbers and speeds of processors with aggregate job set characteristics. The model assumes an input work load of a set of recurrent jobs. The model includes a feedback scheduler/allocator which attempts to improve system performance through higher memory bandwidth utilization by matching individual job requirements for space and bandwidth with space availability and estimates of bandwidth availability at the times of memory allocation. The simulation model includes provisions for specifying precedence relations among the jobs in a job set, and provisions for specifying precedence execution of TMR (Triple Modular Redundant and SIMPLEX (non redundant) jobs.

A Single-System Model Predicts Recognition Memory and Repetition Priming in Amnesia

PubMed Central

Kessels, Roy P.C.; Wester, Arie J.; Shanks, David R.

2014-01-01

We challenge the claim that there are distinct neural systems for explicit and implicit memory by demonstrating that a formal single-system model predicts the pattern of recognition memory (explicit) and repetition priming (implicit) in amnesia. In the current investigation, human participants with amnesia categorized pictures of objects at study and then, at test, identified fragmented versions of studied (old) and nonstudied (new) objects (providing a measure of priming), and made a recognition memory judgment (old vs new) for each object. Numerous results in the amnesic patients were predicted in advance by the single-system model, as follows: (1) deficits in recognition memory and priming were evident relative to a control group; (2) items judged as old were identified at greater levels of fragmentation than items judged new, regardless of whether the items were actually old or new; and (3) the magnitude of the priming effect (the identification advantage for old vs new items) overall was greater than that of items judged new. Model evidence measures also favored the single-system model over two formal multiple-systems models. The findings support the single-system model, which explains the pattern of recognition and priming in amnesia primarily as a reduction in the strength of a single dimension of memory strength, rather than a selective explicit memory system deficit. PMID:25122896

Tower of London test: a comparison between conventional statistic approach and modelling based on artificial neural network in differentiating fronto-temporal dementia from Alzheimer's disease.

PubMed

Franceschi, Massimo; Caffarra, Paolo; Savarè, Rita; Cerutti, Renata; Grossi, Enzo

2011-01-01

The early differentiation of Alzheimer's disease (AD) from frontotemporal dementia (FTD) may be difficult. The Tower of London (ToL), thought to assess executive functions such as planning and visuo-spatial working memory, could help in this purpose. Twentytwo Dementia Centers consecutively recruited patients with early FTD or AD. ToL performances of these groups were analyzed using both the conventional statistical approaches and the Artificial Neural Networks (ANNs) modelling. Ninety-four non aphasic FTD and 160 AD patients were recruited. ToL Accuracy Score (AS) significantly (p < 0.05) differentiated FTD from AD patients. However, the discriminant validity of AS checked by ROC curve analysis, yielded no significant results in terms of sensitivity and specificity (AUC 0.63). The performances of the 12 Success Subscores (SS) together with age, gender and schooling years were entered into advanced ANNs developed by Semeion Institute. The best ANNs were selected and submitted to ROC curves. The non-linear model was able to discriminate FTD from AD with an average AUC for 7 independent trials of 0.82. The use of hidden information contained in the different items of ToL and the non linear processing of the data through ANNs allows a high discrimination between FTD and AD in individual patients.

Parallel Software Model Checking

DTIC Science & Technology

2015-01-08

checker. This project will explore this strategy to parallelize the generalized PDR algorithm for software model checking. It belongs to TF1 due to its ... focus on formal verification . Generalized PDR. Generalized Property Driven Rechability (GPDR) i is an algorithm for solving HORN-SMT reachability...subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 08

Stochastic Game Analysis and Latency Awareness for Self-Adaptation

DTIC Science & Technology

2014-01-01

this paper, we introduce a formal analysis technique based on model checking of stochastic multiplayer games (SMGs) that enables us to quantify the...Additional Key Words and Phrases: Proactive adaptation, Stochastic multiplayer games , Latency 1. INTRODUCTION When planning how to adapt, self-adaptive...contribution of this paper is twofold: (1) A novel analysis technique based on model checking of stochastic multiplayer games (SMGs) that enables us to

Probabilistic Priority Message Checking Modeling Based on Controller Area Networks

NASA Astrophysics Data System (ADS)

Lin, Cheng-Min

Although the probabilistic model checking tool called PRISM has been applied in many communication systems, such as wireless local area network, Bluetooth, and ZigBee, the technique is not used in a controller area network (CAN). In this paper, we use PRISM to model the mechanism of priority messages for CAN because the mechanism has allowed CAN to become the leader in serial communication for automobile and industry control. Through modeling CAN, it is easy to analyze the characteristic of CAN for further improving the security and efficiency of automobiles. The Markov chain model helps us to model the behaviour of priority messages.

Reversible Shape Memory Polymers and Composites: Synthesis, Modeling and Design

DTIC Science & Technology

2013-03-01

Polymer; and (iii) Development of a Shape Memory Assisted Self - Healing Polymer. Page 3 of 19 Mather/FA9550-09-1-0195 IV(i) Modeling and Model...0195 IV(iii) Development of a Shape Memory Assisted Self - Healing Polymer Erika D. Rodriguez, X. Luo, and P.T. Mather, “Linear and Crosslinked...Poly (ε- Caprolactone) Polymers for Shape Memory Assisted Self - Healing (SMASH),” ACS Applied Materials and Interfaces 3 152-161 (2011). Self

A Probabilistic Model of Visual Working Memory: Incorporating Higher Order Regularities into Working Memory Capacity Estimates

ERIC Educational Resources Information Center

Brady, Timothy F.; Tenenbaum, Joshua B.

2013-01-01

When remembering a real-world scene, people encode both detailed information about specific objects and higher order information like the overall gist of the scene. However, formal models of change detection, like those used to estimate visual working memory capacity, assume observers encode only a simple memory representation that includes no…

Investigating the Contribution of Procedural and Declarative Memory to the Acquisition of Past Tense Morphology: Evidence from Finnish

ERIC Educational Resources Information Center

Kidd, Evan; Kirjavainen, Minna

2011-01-01

The present paper reports on a study that investigated the role of procedural and declarative memory in the acquisition of Finnish past tense morphology. Two competing models were tested. Ullman's (2004) declarative/procedural model predicts that procedural memory supports the acquisition of regular morphology, whereas declarative memory supports…

Working Memory and Strategy Use Contribute to Gender Differences in Spatial Ability

ERIC Educational Resources Information Center

Wang, Lu; Carr, Martha

2014-01-01

In this review, a new model that is grounded in information-processing theory is proposed to account for gender differences in spatial ability. The proposed model assumes that the relative strength of working memory, as expressed by the ratio of visuospatial working memory to verbal working memory, influences the type of strategies used on spatial…

The Source of Adult Age Differences in Event-Based Prospective Memory: A Multinomial Modeling Approach

ERIC Educational Resources Information Center

Smith, Rebekah E.; Bayen, Ute J.

2006-01-01

Event-based prospective memory involves remembering to perform an action in response to a particular future event. Normal younger and older adults performed event-based prospective memory tasks in 2 experiments. The authors applied a formal multinomial processing tree model of prospective memory (Smith & Bayen, 2004) to disentangle age differences…

Dynamic intersectoral models with power-law memory

NASA Astrophysics Data System (ADS)

Tarasova, Valentina V.; Tarasov, Vasily E.

2018-01-01

Intersectoral dynamic models with power-law memory are proposed. The equations of open and closed intersectoral models, in which the memory effects are described by the Caputo derivatives of non-integer orders, are derived. We suggest solutions of these equations, which have the form of linear combinations of the Mittag-Leffler functions and which are characterized by different effective growth rates. Examples of intersectoral dynamics with power-law memory are suggested for two sectoral cases. We formulate two principles of intersectoral dynamics with memory: the principle of changing of technological growth rates and the principle of domination change. It has been shown that in the input-output economic dynamics the effects of fading memory can change the economic growth rate and dominant behavior of economic sectors.

Autobiographical memory development from an attachment perspective: the special role of negative events.

PubMed

Chae, Yoojin; Goodman, Gail S; Edelstein, Robin S

2011-01-01

The authors propose a novel model of autobiographical memory development that features the fundamental role of attachment orientations and negative life events. In the model, it is proposed that early autobiographical memory derives in part from the need to express and remember negative experiences, a need that has adaptive value, and that attachment orientations create individual differences in children's recollections of negative experiences. Specifically, the role of attachment in the processing of negative information is discussed in regard to the mnemonic stages of encoding, storage, and retrieval. This model sheds light on several areas of contradictory data in the memory development literature, such as concerning earliest memories and children's and adults' memory/suggestibility for stressful events.

Can the hippocampus tell time? The temporo-septal engram shift model.

PubMed

Lytton, W W; Lipton, P

1999-08-02

An essential feature of episodic memory, the type of memory dependent on hippocampus, is that individual memories belong to particular moments in time. Recent PET studies suggest that memory encoding and recall occur at different locations in human hippocampus. Coupled with other attributes of hippocampus, this suggested to us that the septo-temporal hippocampal axis may play an important role in time perception. We propose a temporo-septal engram shift model of hippocampal memory. The model posits that memories gradually move along the hippocampus from a temporal encoding site to ever more septal sites from which they are recalled. We propose that the sense of time is encoded by the location of the engram along the temporo-septal axis.

Competing Cues: Older Adults Rely on Knowledge in the Face of Fluency

PubMed Central

Brashier, Nadia M.; Umanath, Sharda; Cabeza, Roberto; Marsh, Elizabeth J.

2017-01-01

Consumers regularly encounter repeated false claims in political and marketing campaigns, but very little empirical work addresses their impact among older adults. Repeated statements feel easier to process, and thus more truthful, than new ones (i.e., illusory truth). When judging truth, older adults’ accumulated general knowledge may offset this perception of fluency. In two experiments, participants read statements that contradicted information stored in memory; a post-experimental knowledge check confirmed what individual participants knew. Unlike young adults, older adults exhibited illusory truth only when they lacked knowledge about claims. This interaction between knowledge and fluency extends dual-process theories of aging. PMID:28333505

Molecular mechanisms underlying alcohol-drinking behaviours

PubMed Central

Ron, Dorit; Barak, Segev

2016-01-01

The main characteristic of alcohol use disorder is the consumption of large quantities of alcohol despite the negative consequences. The transition from the moderate use of alcohol to excessive, uncontrolled alcohol consumption results from neuroadaptations that cause aberrant motivational learning and memory processes. Here, we examine studies that have combined molecular and behavioural approaches in rodents to elucidate the molecular mechanisms that keep the social intake of alcohol in check, which we term ‘stop pathways’, and the neuroadaptations that underlie the transition from moderate to uncontrolled, excessive alcohol intake, which we term ‘go pathways’. We also discuss post-transcriptional, genetic and epigenetic alterations that underlie both types of pathways. PMID:27444358

Local rollback for fault-tolerance in parallel computing systems

DOEpatents

Blumrich, Matthias A [Yorktown Heights, NY; Chen, Dong [Yorktown Heights, NY; Gara, Alan [Yorktown Heights, NY; Giampapa, Mark E [Yorktown Heights, NY; Heidelberger, Philip [Yorktown Heights, NY; Ohmacht, Martin [Yorktown Heights, NY; Steinmacher-Burow, Burkhard [Boeblingen, DE; Sugavanam, Krishnan [Yorktown Heights, NY

2012-01-24

A control logic device performs a local rollback in a parallel super computing system. The super computing system includes at least one cache memory device. The control logic device determines a local rollback interval. The control logic device runs at least one instruction in the local rollback interval. The control logic device evaluates whether an unrecoverable condition occurs while running the at least one instruction during the local rollback interval. The control logic device checks whether an error occurs during the local rollback. The control logic device restarts the local rollback interval if the error occurs and the unrecoverable condition does not occur during the local rollback interval.

Modeling age differences in effects of pair repetition and proactive interference using a single parameter.

PubMed

Stephens, Joseph D W; Overman, Amy A

2018-02-01

In this article, we apply the REM model (Shiffrin & Steyvers, 1997) to age differences in associative memory. Using Criss and Shiffrin's (2005) associative version of REM, we show that in a task with pairs repeated across 2 study lists, older adults' reduced benefit of pair repetition can be produced by a general reduction in the diagnosticity of information stored in memory. This reduction can be modeled similarly well by reducing the overall distinctiveness of memory features, or by reducing the accuracy of memory encoding. We report a new experiment in which pairs are repeated across 3 study lists and extend the model accordingly. Finally, we extend the model to previously reported data using the same task paradigm, in which the use of a high-association strategy introduced proactive interference effects in young adults but not older adults. Reducing the diagnosticity of information in memory also reduces the proactive interference effect. Taken together, the modeling and empirical results reported here are consistent with the claim that some age differences that appear to be specific to associative information can be produced via general degradation of information stored in memory. The REM model provides a useful framework for examining age differences in memory as well as harmonizing seemingly conflicting prior modeling approaches for the associative deficit. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

An improved car-following model considering headway changes with memory

NASA Astrophysics Data System (ADS)

Yu, Shaowei; Shi, Zhongke

2015-03-01

To describe car-following behaviors in complex situations better, increase roadway traffic mobility and minimize cars' fuel consumptions, the linkage between headway changes with memory and car-following behaviors was explored with the field car-following data by using the gray correlation analysis method, and then an improved car-following model considering headway changes with memory on a single lane was proposed based on the full velocity difference model. Some numerical simulations were carried out by employing the improved car-following model to explore how headway changes with memory affected each car's velocity, acceleration, headway and fuel consumptions. The research results show that headway changes with memory have significant effects on car-following behaviors and fuel consumptions and that considering headway changes with memory in designing the adaptive cruise control strategy can improve the traffic flow stability and minimize cars' fuel consumptions.

Working memory and intraindividual variability as neurocognitive indicators in ADHD: examining competing model predictions.

PubMed

Kofler, Michael J; Alderson, R Matt; Raiker, Joseph S; Bolden, Jennifer; Sarver, Dustin E; Rapport, Mark D

2014-05-01

The current study examined competing predictions of the default mode, cognitive neuroenergetic, and functional working memory models of attention-deficit/hyperactivity disorder (ADHD) regarding the relation between neurocognitive impairments in working memory and intraindividual variability. Twenty-two children with ADHD and 15 typically developing children were assessed on multiple tasks measuring intraindividual reaction time (RT) variability (ex-Gaussian: tau, sigma) and central executive (CE) working memory. Latent factor scores based on multiple, counterbalanced tasks were created for each construct of interest (CE, tau, sigma) to reflect reliable variance associated with each construct and remove task-specific, test-retest, and random error. Bias-corrected, bootstrapped mediation analyses revealed that CE working memory accounted for 88% to 100% of ADHD-related RT variability across models, and between-group differences in RT variability were no longer detectable after accounting for the mediating role of CE working memory. In contrast, RT variability accounted for 10% to 29% of between-group differences in CE working memory, and large magnitude CE working memory deficits remained after accounting for this partial mediation. Statistical comparison of effect size estimates across models suggests directionality of effects, such that the mediation effects of CE working memory on RT variability were significantly greater than the mediation effects of RT variability on CE working memory. The current findings question the role of RT variability as a primary neurocognitive indicator in ADHD and suggest that ADHD-related RT variability may be secondary to underlying deficits in CE working memory.

Why are you telling me that? A conceptual model of the social function of autobiographical memory.

PubMed

Alea, Nicole; Bluck, Susan

2003-03-01

In an effort to stimulate and guide empirical work within a functional framework, this paper provides a conceptual model of the social functions of autobiographical memory (AM) across the lifespan. The model delineates the processes and variables involved when AMs are shared to serve social functions. Components of the model include: lifespan contextual influences, the qualitative characteristics of memory (emotionality and level of detail recalled), the speaker's characteristics (age, gender, and personality), the familiarity and similarity of the listener to the speaker, the level of responsiveness during the memory-sharing process, and the nature of the social relationship in which the memory sharing occurs (valence and length of the relationship). These components are shown to influence the type of social function served and/or, the extent to which social functions are served. Directions for future empirical work to substantiate the model and hypotheses derived from the model are provided.

Measuring memory with the order of fractional derivative

NASA Astrophysics Data System (ADS)

Du, Maolin; Wang, Zaihua; Hu, Haiyan

2013-12-01

Fractional derivative has a history as long as that of classical calculus, but it is much less popular than it should be. What is the physical meaning of fractional derivative? This is still an open problem. In modeling various memory phenomena, we observe that a memory process usually consists of two stages. One is short with permanent retention, and the other is governed by a simple model of fractional derivative. With the numerical least square method, we show that the fractional model perfectly fits the test data of memory phenomena in different disciplines, not only in mechanics, but also in biology and psychology. Based on this model, we find that a physical meaning of the fractional order is an index of memory.

Analysis of Memory Formation during General Anesthesia (Propofol/Remifentanil) for Elective Surgery Using the Process-dissociation Procedure.

PubMed

Hadzidiakos, Daniel; Horn, Nadja; Degener, Roland; Buchner, Axel; Rehberg, Benno

2009-08-01

There have been reports of memory formation during general anesthesia. The process-dissociation procedure has been used to determine if these are controlled (explicit/conscious) or automatic (implicit/unconscious) memories. This study used the process-dissociation procedure with the original measurement model and one which corrected for guessing to determine if more accurate results were obtained in this setting. A total of 160 patients scheduled for elective surgery were enrolled. Memory for words presented during propofol and remifentanil general anesthesia was tested postoperatively by using a word-stem completion task in a process-dissociation procedure. To assign possible memory effects to different levels of anesthetic depth, the authors measured depth of anesthesia using the BIS XP monitor (Aspect Medical Systems, Norwood, MA). Word-stem completion performance showed no evidence of memory for intraoperatively presented words. Nevertheless, an evaluation of these data using the original measurement model for process-dissociation data suggested an evidence of controlled (C = 0.05; 95% confidence interval [CI] 0.02-0.08) and automatic (A = 0.11; 95% CI 0.09-0.12) memory processes (P < 0.01). However, when the data were evaluated with an extended measurement model taking base rates into account adequately, no evidence for controlled (C = 0.00; 95% CI -0.04 to 0.04) or automatic (A = 0.00; 95% CI -0.02 to 0.02) memory processes was obtained. The authors report and discuss parallel findings for published data sets that were generated by using the process-dissociation procedure. Patients had no memories for auditory information presented during propofol/remifentanil anesthesia after midazolam premedication. The use of the process-dissociation procedure with the original measurement model erroneously detected memories, whereas the extended model, corrected for guessing, correctly revealed no memory.

MOM: A meteorological data checking expert system in CLIPS

NASA Technical Reports Server (NTRS)

Odonnell, Richard

1990-01-01

Meteorologists have long faced the problem of verifying the data they use. Experience shows that there is a sizable number of errors in the data reported by meteorological observers. This is unacceptable for computer forecast models, which depend on accurate data for accurate results. Most errors that occur in meteorological data are obvious to the meteorologist, but time constraints prevent hand-checking. For this reason, it is necessary to have a 'front end' to the computer model to ensure the accuracy of input. Various approaches to automatic data quality control have been developed by several groups. MOM is a rule-based system implemented in CLIPS and utilizing 'consistency checks' and 'range checks'. The system is generic in the sense that it knows some meteorological principles, regardless of specific station characteristics. Specific constraints kept as CLIPS facts in a separate file provide for system flexibility. Preliminary results show that the expert system has detected some inconsistencies not noticed by a local expert.

Learning Assumptions for Compositional Verification

NASA Technical Reports Server (NTRS)

Cobleigh, Jamieson M.; Giannakopoulou, Dimitra; Pasareanu, Corina; Clancy, Daniel (Technical Monitor)

2002-01-01

Compositional verification is a promising approach to addressing the state explosion problem associated with model checking. One compositional technique advocates proving properties of a system by checking properties of its components in an assume-guarantee style. However, the application of this technique is difficult because it involves non-trivial human input. This paper presents a novel framework for performing assume-guarantee reasoning in an incremental and fully automated fashion. To check a component against a property, our approach generates assumptions that the environment needs to satisfy for the property to hold. These assumptions are then discharged on the rest of the system. Assumptions are computed by a learning algorithm. They are initially approximate, but become gradually more precise by means of counterexamples obtained by model checking the component and its environment, alternately. This iterative process may at any stage conclude that the property is either true or false in the system. We have implemented our approach in the LTSA tool and applied it to the analysis of a NASA system.

The New ISD: Applying Cognitive Strategies to Instructional Design.

ERIC Educational Resources Information Center

Clark, Ruth Colvin

2002-01-01

Discusses cognitive models of instruction that can help develop new models of Instructional Systems Design (ISD) that include cognitive task analysis to identify mental models; constructive assumptions of learning; working memory and long-term memory; retrieval of new knowledge and skills from long-term memory; and support of metacognitive skills.…

Modeling Confidence and Response Time in Recognition Memory

ERIC Educational Resources Information Center

Ratcliff, Roger; Starns, Jeffrey J.

2009-01-01

A new model for confidence judgments in recognition memory is presented. In the model, the match between a single test item and memory produces a distribution of evidence, with better matches corresponding to distributions with higher means. On this match dimension, confidence criteria are placed, and the areas between the criteria under the…

Neural circuit basis of visuo-spatial working memory precision: a computational and behavioral study.

PubMed

Almeida, Rita; Barbosa, João; Compte, Albert

2015-09-01

The amount of information that can be retained in working memory (WM) is limited. Limitations of WM capacity have been the subject of intense research, especially in trying to specify algorithmic models for WM. Comparatively, neural circuit perspectives have barely been used to test WM limitations in behavioral experiments. Here we used a neuronal microcircuit model for visuo-spatial WM (vsWM) to investigate memory of several items. The model assumes that there is a topographic organization of the circuit responsible for spatial memory retention. This assumption leads to specific predictions, which we tested in behavioral experiments. According to the model, nearby locations should be recalled with a bias, as if the two memory traces showed attraction or repulsion during the delay period depending on distance. Another prediction is that the previously reported loss of memory precision for an increasing number of memory items (memory load) should vanish when the distances between items are controlled for. Both predictions were confirmed experimentally. Taken together, our findings provide support for a topographic neural circuit organization of vsWM, they suggest that interference between similar memories underlies some WM limitations, and they put forward a circuit-based explanation that reconciles previous conflicting results on the dependence of WM precision with load. Copyright © 2015 the American Physiological Society.

Age effects on explicit and implicit memory

PubMed Central

Ward, Emma V.; Berry, Christopher J.; Shanks, David R.

2013-01-01

It is well-documented that explicit memory (e.g., recognition) declines with age. In contrast, many argue that implicit memory (e.g., priming) is preserved in healthy aging. For example, priming on tasks such as perceptual identification is often not statistically different in groups of young and older adults. Such observations are commonly taken as evidence for distinct explicit and implicit learning/memory systems. In this article we discuss several lines of evidence that challenge this view. We describe how patterns of differential age-related decline may arise from differences in the ways in which the two forms of memory are commonly measured, and review recent research suggesting that under improved measurement methods, implicit memory is not age-invariant. Formal computational models are of considerable utility in revealing the nature of underlying systems. We report the results of applying single and multiple-systems models to data on age effects in implicit and explicit memory. Model comparison clearly favors the single-system view. Implications for the memory systems debate are discussed. PMID:24065942

Identification of Nascent Memory CD8 T Cells and Modeling of Their Ontogeny.

PubMed

Crauste, Fabien; Mafille, Julien; Boucinha, Lilia; Djebali, Sophia; Gandrillon, Olivier; Marvel, Jacqueline; Arpin, Christophe

2017-03-22

Primary immune responses generate short-term effectors and long-term protective memory cells. The delineation of the genealogy linking naive, effector, and memory cells has been complicated by the lack of phenotypes discriminating effector from memory differentiation stages. Using transcriptomics and phenotypic analyses, we identify Bcl2 and Mki67 as a marker combination that enables the tracking of nascent memory cells within the effector phase. We then use a formal approach based on mathematical models describing the dynamics of population size evolution to test potential progeny links and demonstrate that most cells follow a linear naive→early effector→late effector→memory pathway. Moreover, our mathematical model allows long-term prediction of memory cell numbers from a few early experimental measurements. Our work thus provides a phenotypic means to identify effector and memory cells, as well as a mathematical framework to investigate their genealogy and to predict the outcome of immunization regimens in terms of memory cell numbers generated. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Multiple Memory Systems Are Unnecessary to Account for Infant Memory Development: An Ecological Model

PubMed Central

Rovee-Collier, Carolyn; Cuevas, Kimberly

2009-01-01

How the memory of adults evolves from the memory abilities of infants is a central problem in cognitive development. The popular solution holds that the multiple memory systems of adults mature at different rates during infancy. The early-maturing system (implicit or nondeclarative memory) functions automatically from birth, whereas the late-maturing system (explicit or declarative memory) functions intentionally, with awareness, from late in the first year. Data are presented from research on deferred imitation, sensory preconditioning, potentiation, and context for which this solution cannot account and present an alternative model that eschews the need for multiple memory systems. The ecological model of infant memory development (N. E. Spear, 1984) holds that members of all species are perfectly adapted to their niche at each point in ontogeny and exhibit effective, evolutionarily selected solutions to whatever challenges each new niche poses. Because adults and infants occupy different niches, what they perceive, learn, and remember about the same event differs, but their raw capacity to learn and remember does not. PMID:19209999

Model-checking techniques based on cumulative residuals.

PubMed

Lin, D Y; Wei, L J; Ying, Z

2002-03-01

Residuals have long been used for graphical and numerical examinations of the adequacy of regression models. Conventional residual analysis based on the plots of raw residuals or their smoothed curves is highly subjective, whereas most numerical goodness-of-fit tests provide little information about the nature of model misspecification. In this paper, we develop objective and informative model-checking techniques by taking the cumulative sums of residuals over certain coordinates (e.g., covariates or fitted values) or by considering some related aggregates of residuals, such as moving sums and moving averages. For a variety of statistical models and data structures, including generalized linear models with independent or dependent observations, the distributions of these stochastic processes tinder the assumed model can be approximated by the distributions of certain zero-mean Gaussian processes whose realizations can be easily generated by computer simulation. Each observed process can then be compared, both graphically and numerically, with a number of realizations from the Gaussian process. Such comparisons enable one to assess objectively whether a trend seen in a residual plot reflects model misspecification or natural variation. The proposed techniques are particularly useful in checking the functional form of a covariate and the link function. Illustrations with several medical studies are provided.

Parameter discovery in stochastic biological models using simulated annealing and statistical model checking.

PubMed

Hussain, Faraz; Jha, Sumit K; Jha, Susmit; Langmead, Christopher J

2014-01-01

Stochastic models are increasingly used to study the behaviour of biochemical systems. While the structure of such models is often readily available from first principles, unknown quantitative features of the model are incorporated into the model as parameters. Algorithmic discovery of parameter values from experimentally observed facts remains a challenge for the computational systems biology community. We present a new parameter discovery algorithm that uses simulated annealing, sequential hypothesis testing, and statistical model checking to learn the parameters in a stochastic model. We apply our technique to a model of glucose and insulin metabolism used for in-silico validation of artificial pancreata and demonstrate its effectiveness by developing parallel CUDA-based implementation for parameter synthesis in this model.

A critical evaluation of monkey models of amnesia and dementia.

PubMed

Ridley, R M; Baker, H F

1991-01-01

In this review we consider various models of amnesia and dementia in monkeys and examine the validity of such models. In Section 2 we describe the various types of memory tests (tasks) available for use with monkeys and discuss the extent to which these tasks assess different facets of memory according to present theories of human memory. We argue that the rules which govern correct task performance are best regarded as a form of semantic rather than procedural memory, and that when information about stimulus attributes or reward associations is stored long-term then that knowledge is semantic. The demonstration of episodic memory in monkeys is problematic and the term recognition memory has been used too loosely. In particular, it is difficult to dissociate episodic memory for stimulus events from the use of semantic memory for the rule of the task, since dysfunction of either can produce impairment on performance of the same task. Tasks can also be divided into those which assess memory for stimulus-reward associations (evaluative memory) and those which tax stimulus-response associations including spatial and conditional responding (non-evaluative memory). This dissociation cuts across the distinction between semantic and episodic memory. In Section 3 we examine the usefulness of the classification of tasks described in Section 2 in clarifying our understanding of the contribution of the temporal lobes and the cholinergic system to memory. We conclude that evaluative and non-evaluative memory are mediated by separate parallel systems involving the amygdala and hippocampus, respectively.

Dynamic interactions between visual working memory and saccade target selection

PubMed Central

Schneegans, Sebastian; Spencer, John P.; Schöner, Gregor; Hwang, Seongmin; Hollingworth, Andrew

2014-01-01

Recent psychophysical experiments have shown that working memory for visual surface features interacts with saccadic motor planning, even in tasks where the saccade target is unambiguously specified by spatial cues. Specifically, a match between a memorized color and the color of either the designated target or a distractor stimulus influences saccade target selection, saccade amplitudes, and latencies in a systematic fashion. To elucidate these effects, we present a dynamic neural field model in combination with new experimental data. The model captures the neural processes underlying visual perception, working memory, and saccade planning relevant to the psychophysical experiment. It consists of a low-level visual sensory representation that interacts with two separate pathways: a spatial pathway implementing spatial attention and saccade generation, and a surface feature pathway implementing color working memory and feature attention. Due to bidirectional coupling between visual working memory and feature attention in the model, the working memory content can indirectly exert an effect on perceptual processing in the low-level sensory representation. This in turn biases saccadic movement planning in the spatial pathway, allowing the model to quantitatively reproduce the observed interaction effects. The continuous coupling between representations in the model also implies that modulation should be bidirectional, and model simulations provide specific predictions for complementary effects of saccade target selection on visual working memory. These predictions were empirically confirmed in a new experiment: Memory for a sample color was biased toward the color of a task-irrelevant saccade target object, demonstrating the bidirectional coupling between visual working memory and perceptual processing. PMID:25228628

Properties of a memory network in psychology

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

Wedemann, Roseli S.; Donangelo, Raul; Carvalho, Luis A. V. de

We have previously described neurotic psychopathology and psychoanalytic working-through by an associative memory mechanism, based on a neural network model, where memory was modelled by a Boltzmann machine (BM). Since brain neural topology is selectively structured, we simulated known microscopic mechanisms that control synaptic properties, showing that the network self-organizes to a hierarchical, clustered structure. Here, we show some statistical mechanical properties of the complex networks which result from this self-organization. They indicate that a generalization of the BM may be necessary to model memory.

Properties of a memory network in psychology

NASA Astrophysics Data System (ADS)

Wedemann, Roseli S.; Donangelo, Raul; de Carvalho, Luís A. V.

2007-12-01

We have previously described neurotic psychopathology and psychoanalytic working-through by an associative memory mechanism, based on a neural network model, where memory was modelled by a Boltzmann machine (BM). Since brain neural topology is selectively structured, we simulated known microscopic mechanisms that control synaptic properties, showing that the network self-organizes to a hierarchical, clustered structure. Here, we show some statistical mechanical properties of the complex networks which result from this self-organization. They indicate that a generalization of the BM may be necessary to model memory.

A direct comparison of popular models of normal memory loss and Alzheimer's disease in samples of African Americans, Mexican Americans, and refugees and immigrants from the former Soviet Union.

PubMed

Schrauf, Robert W; Iris, Madelyn

2011-04-01

To understand how people differentiate normal memory loss from Alzheimer's disease (AD) by investigating cultural models of these conditions. Ethnographic interviews followed by a survey. Cultural consensus analysis was used to test for the presence of group models, derive the "culturally correct" set of beliefs, and compare models of normal memory loss and AD. Chicago, Illinois. One hundred eight individuals from local neighborhoods: African Americans, Mexican Americans, and refugees and immigrants from the former Soviet Union. Participants responded to yes-or-no questions about the nature and causes of normal memory loss and AD and provided information on ethnicity, age, sex, acculturation, and experience with AD. Groups held a common model of AD as a brain-based disease reflecting irreversible cognitive decline. Higher levels of acculturation predicted greater knowledge of AD. Russian speakers favored biological over psychological models of the disease. Groups also held a common model of normal memory loss, including the important belief that "normal" forgetting involves eventual recall of the forgotten material. Popular models of memory loss and AD confirm that patients and clinicians are speaking the same "language" in their discussions of memory loss and AD. Nevertheless, the presence of coherent models of memory loss and AD, and the unequal distribution of that knowledge across groups, suggests that clinicians should include wider circles of patients' families and friends in their consultations. These results frame knowledge as distributed across social groups rather than simply the possession of individual minds. © 2011, Copyright the Authors. Journal compilation © 2011, The American Geriatrics Society.

Spatial memory tasks in rodents: what do they model?

PubMed

Morellini, Fabio

2013-10-01

The analysis of spatial learning and memory in rodents is commonly used to investigate the mechanisms underlying certain forms of human cognition and to model their dysfunction in neuropsychiatric and neurodegenerative diseases. Proper interpretation of rodent behavior in terms of spatial memory and as a model of human cognitive functions is only possible if various navigation strategies and factors controlling the performance of the animal in a spatial task are taken into consideration. The aim of this review is to describe the experimental approaches that are being used for the study of spatial memory in rats and mice and the way that they can be interpreted in terms of general memory functions. After an introduction to the classification of memory into various categories and respective underlying neuroanatomical substrates, I explain the concept of spatial memory and its measurement in rats and mice by analysis of their navigation strategies. Subsequently, I describe the most common paradigms for spatial memory assessment with specific focus on methodological issues relevant for the correct interpretation of the results in terms of cognitive function. Finally, I present recent advances in the use of spatial memory tasks to investigate episodic-like memory in mice.

Some Surprising Findings on the Involvement of the Parietal Lobe in Human Memory

PubMed Central

Olson, Ingrid R.; Berryhill, Marian

2009-01-01

The posterior parietal lobe is known to play some role in a far-flung list of mental processes: linking vision to action (saccadic eye movements, reaching, grasping), attending to visual space, numerical calculation, and mental rotation. Here we review findings from humans and monkeys that illuminate an untraditional function of this region: memory. Our review draws on neuroimaging findings that have repeatedly identified parietal lobe activations associated with short-term or working memory and episodic memory. We also discuss recent neuropsychological findings showing that individuals with parietal lobe damage exhibit both working memory and long-term memory deficits. These deficits are not ubiquitous; they are only evident under certain retrieval demands. Our review elaborates on these findings and evaluates various theories about the mechanistic role of the posterior parietal lobe in memory. The available data point towards the conclusion that the posterior parietal lobe plays an important role in memory retrieval irrespective of elapsed time. The two models that are best supported by existing data are the Attention to Memory Model and the Subjective Memory Model. We conclude by formalizing several open questions that are intended to encourage future research. PMID:18848635

Dissociation of item and source memory in rhesus monkeys.

PubMed

Basile, Benjamin M; Hampton, Robert R

2017-09-01

Source memory, or memory for the context in which a memory was formed, is a defining characteristic of human episodic memory and source memory errors are a debilitating symptom of memory dysfunction. Evidence for source memory in nonhuman primates is sparse despite considerable evidence for other types of sophisticated memory and the practical need for good models of episodic memory in nonhuman primates. A previous study showed that rhesus monkeys confused the identity of a monkey they saw with a monkey they heard, but only after an extended memory delay. This suggests that they initially remembered the source - visual or auditory - of the information but forgot the source as time passed. Here, we present a monkey model of source memory that is based on this previous study. In each trial, monkeys studied two images, one that they simply viewed and touched and the other that they classified as a bird, fish, flower, or person. In a subsequent memory test, they were required to select the image from one source but avoid the other. With training, monkeys learned to suppress responding to images from the to-be-avoided source. After longer memory intervals, monkeys continued to show reliable item memory, discriminating studied images from distractors, but made many source memory errors. Monkeys discriminated source based on study method, not study order, providing preliminary evidence that our manipulation of retention interval caused errors due to source forgetting instead of source confusion. Finally, some monkeys learned to select remembered images from either source on cue, showing that they did indeed remember both items and both sources. This paradigm potentially provides a new model to study a critical aspect of episodic memory in nonhuman primates. Copyright © 2017 Elsevier B.V. All rights reserved.

Resonator memories and optical novelty filters

NASA Astrophysics Data System (ADS)

Anderson, Dana Z.; Erle, Marie C.

Optical resonators having holographic elements are potential candidates for storing information that can be accessed through content addressable or associative recall. Closely related to the resonator memory is the optical novelty filter, which can detect the differences between a test object and a set of reference objects. We discuss implementations of these devices using continuous optical media such as photorefractive materials. The discussion is framed in the context of neural network models. There are both formal and qualitative similarities between the resonator memory and optical novelty filter and network models. Mode competition arises in the theory of the resonator memory, much as it does in some network models. We show that the role of the phenomena of "daydreaming" in the real-time programmable optical resonator is very much akin to the role of "unlearning" in neural network memories. The theory of programming the real-time memory for a single mode is given in detail. This leads to a discussion of the optical novelty filter. Experimental results for the resonator memory, the real-time programmable memory, and the optical tracking novelty filter are reviewed. We also point to several issues that need to be addressed in order to implement more formal models of neural networks.

Resonator Memories And Optical Novelty Filters

NASA Astrophysics Data System (ADS)

Anderson, Dana Z.; Erie, Marie C.

1987-05-01

Optical resonators having holographic elements are potential candidates for storing information that can be accessed through content-addressable or associative recall. Closely related to the resonator memory is the optical novelty filter, which can detect the differences between a test object and a set of reference objects. We discuss implementations of these devices using continuous optical media such as photorefractive ma-terials. The discussion is framed in the context of neural network models. There are both formal and qualitative similarities between the resonator memory and optical novelty filter and network models. Mode competition arises in the theory of the resonator memory, much as it does in some network models. We show that the role of the phenomena of "daydream-ing" in the real-time programmable optical resonator is very much akin to the role of "unlearning" in neural network memories. The theory of programming the real-time memory for a single mode is given in detail. This leads to a discussion of the optical novelty filter. Experimental results for the resonator memory, the real-time programmable memory, and the optical tracking novelty filter are reviewed. We also point to several issues that need to be addressed in order to implement more formal models of neural networks.

Constitutive modeling of glassy shape memory polymers

NASA Astrophysics Data System (ADS)

Khanolkar, Mahesh

The aim of this research is to develop constitutive models for non-linear materials. Here, issues related for developing constitutive model for glassy shape memory polymers are addressed in detail. Shape memory polymers are novel material that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. The temporary shape is stable and return to the original shape is triggered by a suitable mechanism such heating the polymer above a transition temperature. Glassy shape memory polymers are called glassy because the temporary shape is fixed by the formation of a glassy solid, while return to the original shape is due to the melting of this glassy phase. The constitutive model has been developed to capture the thermo-mechanical behavior of glassy shape memory polymers using elements of nonlinear mechanics and polymer physics. The key feature of this framework is that a body can exist stress free in numerous natural configurations, the underlying natural configuration of the body changing during the process, with the response of the body being elastic from these evolving natural configurations. The aim of this research is to formulate a constitutive model for glassy shape memory polymers (GSMP) which takes in to account the fact that the stress-strain response depends on thermal expansion of polymers. The model developed is for the original amorphous phase, the temporary glassy phase and transition between these phases. The glass transition process has been modeled using a framework that was developed recently for studying crystallization in polymers and is based on the theory of multiple natural configurations. Using the same frame work, the melting of the glassy phase to capture the return of the polymer to its original shape is also modeled. The effect of nanoreinforcement on the response of shape memory polymers (GSMP) is studied and a model is developed. In addition to modeling and solving boundary value problems for GSMP's, problems of importance for CSMP, specifically a shape memory cycle (Torsion of a Cylinder) is solved using the developed crystallizable shape memory polymer model. To solve complex boundary value problems in realistic geometries a user material subroutine (UMAT) for GSMP model has been developed for use in conjunction with the commercial finite element software ABAQUS. The accuracy of the UMAT has been verified by testing it against problems for which the results are known.

Multiple memory systems as substrates for multiple decision systems

PubMed Central

Doll, Bradley B.; Shohamy, Daphna; Daw, Nathaniel D.

2014-01-01

It has recently become widely appreciated that value-based decision making is supported by multiple computational strategies. In particular, animal and human behavior in learning tasks appears to include habitual responses described by prominent model-free reinforcement learning (RL) theories, but also more deliberative or goal-directed actions that can be characterized by a different class of theories, model-based RL. The latter theories evaluate actions by using a representation of the contingencies of the task (as with a learned map of a spatial maze), called an “internal model.” Given the evidence of behavioral and neural dissociations between these approaches, they are often characterized as dissociable learning systems, though they likely interact and share common mechanisms. In many respects, this division parallels a longstanding dissociation in cognitive neuroscience between multiple memory systems, describing, at the broadest level, separate systems for declarative and procedural learning. Procedural learning has notable parallels with model-free RL: both involve learning of habits and both are known to depend on parts of the striatum. Declarative memory, by contrast, supports memory for single events or episodes and depends on the hippocampus. The hippocampus is thought to support declarative memory by encoding temporal and spatial relations among stimuli and thus is often referred to as a relational memory system. Such relational encoding is likely to play an important role in learning an internal model, the representation that is central to model-based RL. Thus, insofar as the memory systems represent more general-purpose cognitive mechanisms that might subserve performance on many sorts of tasks including decision making, these parallels raise the question whether the multiple decision systems are served by multiple memory systems, such that one dissociation is grounded in the other. Here we investigated the relationship between model-based RL and relational memory by comparing individual differences across behavioral tasks designed to measure either capacity. Human subjects performed two tasks, a learning and generalization task (acquired equivalence) which involves relational encoding and depends on the hippocampus; and a sequential RL task that could be solved by either a model-based or model-free strategy. We assessed the correlation between subjects’ use of flexible, relational memory, as measured by generalization in the acquired equivalence task, and their differential reliance on either RL strategy in the decision task. We observed a significant positive relationship between generalization and model-based, but not model-free, choice strategies. These results are consistent with the hypothesis that model-based RL, like acquired equivalence, relies on a more general-purpose relational memory system. PMID:24846190

The Role of Short-Term Memory in Operator Workload

DTIC Science & Technology

1988-04-01

Craik , F.I. and Lockhart , R.S., 1972, Levels of processing : A framework for memory research...examples of postcategorical selction models. Precategorical Selection Models Sperling’s Model. Unlike Craik and Lockhart’s levels -of- processing model...subdivided to contain a primary memory unit and a mechanism for the direction of conscious attention. Levels -of- Processing . Craik and Lockhart’s levels

Fast associative memory + slow neural circuitry = the computational model of the brain.

NASA Astrophysics Data System (ADS)

Berkovich, Simon; Berkovich, Efraim; Lapir, Gennady

1997-08-01

We propose a computational model of the brain based on a fast associative memory and relatively slow neural processors. In this model, processing time is expensive but memory access is not, and therefore most algorithmic tasks would be accomplished by using large look-up tables as opposed to calculating. The essential feature of an associative memory in this context (characteristic for a holographic type memory) is that it works without an explicit mechanism for resolution of multiple responses. As a result, the slow neuronal processing elements, overwhelmed by the flow of information, operate as a set of templates for ranking of the retrieved information. This structure addresses the primary controversy in the brain architecture: distributed organization of memory vs. localization of processing centers. This computational model offers an intriguing explanation of many of the paradoxical features in the brain architecture, such as integration of sensors (through DMA mechanism), subliminal perception, universality of software, interrupts, fault-tolerance, certain bizarre possibilities for rapid arithmetics etc. In conventional computer science the presented type of a computational model did not attract attention as it goes against the technological grain by using a working memory faster than processing elements.

Generalized Symbolic Execution for Model Checking and Testing

NASA Technical Reports Server (NTRS)

Khurshid, Sarfraz; Pasareanu, Corina; Visser, Willem; Kofmeyer, David (Technical Monitor)

2003-01-01

Modern software systems, which often are concurrent and manipulate complex data structures must be extremely reliable. We present a novel framework based on symbolic execution, for automated checking of such systems. We provide a two-fold generalization of traditional symbolic execution based approaches: one, we define a program instrumentation, which enables standard model checkers to perform symbolic execution; two, we give a novel symbolic execution algorithm that handles dynamically allocated structures (e.g., lists and trees), method preconditions (e.g., acyclicity of lists), data (e.g., integers and strings) and concurrency. The program instrumentation enables a model checker to automatically explore program heap configurations (using a systematic treatment of aliasing) and manipulate logical formulae on program data values (using a decision procedure). We illustrate two applications of our framework: checking correctness of multi-threaded programs that take inputs from unbounded domains with complex structure and generation of non-isomorphic test inputs that satisfy a testing criterion. Our implementation for Java uses the Java PathFinder model checker.

Model Checking Degrees of Belief in a System of Agents

NASA Technical Reports Server (NTRS)

Raimondi, Franco; Primero, Giuseppe; Rungta, Neha

2014-01-01

Reasoning about degrees of belief has been investigated in the past by a number of authors and has a number of practical applications in real life. In this paper we present a unified framework to model and verify degrees of belief in a system of agents. In particular, we describe an extension of the temporal-epistemic logic CTLK and we introduce a semantics based on interpreted systems for this extension. In this way, degrees of beliefs do not need to be provided externally, but can be derived automatically from the possible executions of the system, thereby providing a computationally grounded formalism. We leverage the semantics to (a) construct a model checking algorithm, (b) investigate its complexity, (c) provide a Java implementation of the model checking algorithm, and (d) evaluate our approach using the standard benchmark of the dining cryptographers. Finally, we provide a detailed case study: using our framework and our implementation, we assess and verify the situational awareness of the pilot of Air France 447 flying in off-nominal conditions.

Comparing single- and dual-process models of memory development.

PubMed

Hayes, Brett K; Dunn, John C; Joubert, Amy; Taylor, Robert

2017-11-01

This experiment examined single-process and dual-process accounts of the development of visual recognition memory. The participants, 6-7-year-olds, 9-10-year-olds and adults, were presented with a list of pictures which they encoded under shallow or deep conditions. They then made recognition and confidence judgments about a list containing old and new items. We replicated the main trends reported by Ghetti and Angelini () in that recognition hit rates increased from 6 to 9 years of age, with larger age changes following deep than shallow encoding. Formal versions of the dual-process high threshold signal detection model and several single-process models (equal variance signal detection, unequal variance signal detection, mixture signal detection) were fit to the developmental data. The unequal variance and mixture signal detection models gave a better account of the data than either of the other models. A state-trace analysis found evidence for only one underlying memory process across the age range tested. These results suggest that single-process memory models based on memory strength are a viable alternative to dual-process models for explaining memory development. © 2016 John Wiley & Sons Ltd.

Two Unipolar Terminal-Attractor-Based Associative Memories

NASA Technical Reports Server (NTRS)

Liu, Hua-Kuang; Wu, Chwan-Hwa

1995-01-01

Two unipolar mathematical models of electronic neural network functioning as terminal-attractor-based associative memory (TABAM) developed. Models comprise sets of equations describing interactions between time-varying inputs and outputs of neural-network memory, regarded as dynamical system. Simplifies design and operation of optoelectronic processor to implement TABAM performing associative recall of images. TABAM concept described in "Optoelectronic Terminal-Attractor-Based Associative Memory" (NPO-18790). Experimental optoelectronic apparatus that performed associative recall of binary images described in "Optoelectronic Inner-Product Neural Associative Memory" (NPO-18491).

SONOS Nonvolatile Memory Cell Programming Characteristics

NASA Technical Reports Server (NTRS)

MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

2010-01-01

Silicon-oxide-nitride-oxide-silicon (SONOS) nonvolatile memory is gaining favor over conventional EEPROM FLASH memory technology. This paper characterizes the SONOS write operation using a nonquasi-static MOSFET model. This includes floating gate charge and voltage characteristics as well as tunneling current, voltage threshold and drain current characterization. The characterization of the SONOS memory cell predicted by the model closely agrees with experimental data obtained from actual SONOS memory cells. The tunnel current, drain current, threshold voltage and read drain current all closely agreed with empirical data.

Working memory load modulation of parieto-frontal connections: evidence from dynamic causal modeling

PubMed Central

Ma, Liangsuo; Steinberg, Joel L.; Hasan, Khader M.; Narayana, Ponnada A.; Kramer, Larry A.; Moeller, F. Gerard

2011-01-01

Previous neuroimaging studies have shown that working memory load has marked effects on regional neural activation. However, the mechanism through which working memory load modulates brain connectivity is still unclear. In this study, this issue was addressed using dynamic causal modeling (DCM) based on functional magnetic resonance imaging (fMRI) data. Eighteen normal healthy subjects were scanned while they performed a working memory task with variable memory load, as parameterized by two levels of memory delay and three levels of digit load (number of digits presented in each visual stimulus). Eight regions of interest, i.e., bilateral middle frontal gyrus (MFG), anterior cingulate cortex (ACC), inferior frontal cortex (IFC), and posterior parietal cortex (PPC), were chosen for DCM analyses. Analysis of the behavioral data during the fMRI scan revealed that accuracy decreased as digit load increased. Bayesian inference on model structure indicated that a bilinear DCM in which memory delay was the driving input to bilateral PPC and in which digit load modulated several parieto-frontal connections was the optimal model. Analysis of model parameters showed that higher digit load enhanced connection from L PPC to L IFC, and lower digit load inhibited connection from R PPC to L ACC. These findings suggest that working memory load modulates brain connectivity in a parieto-frontal network, and may reflect altered neuronal processes, e.g., information processing or error monitoring, with the change in working memory load. PMID:21692148

Cooperative Data Sharing: Simple Support for Clusters of SMP Nodes

NASA Technical Reports Server (NTRS)

DiNucci, David C.; Balley, David H. (Technical Monitor)

1997-01-01

Libraries like PVM and MPI send typed messages to allow for heterogeneous cluster computing. Lower-level libraries, such as GAM, provide more efficient access to communication by removing the need to copy messages between the interface and user space in some cases. still lower-level interfaces, such as UNET, get right down to the hardware level to provide maximum performance. However, these are all still interfaces for passing messages from one process to another, and have limited utility in a shared-memory environment, due primarily to the fact that message passing is just another term for copying. This drawback is made more pertinent by today's hybrid architectures (e.g. clusters of SMPs), where it is difficult to know beforehand whether two communicating processes will share memory. As a result, even portable language tools (like HPF compilers) must either map all interprocess communication, into message passing with the accompanying performance degradation in shared memory environments, or they must check each communication at run-time and implement the shared-memory case separately for efficiency. Cooperative Data Sharing (CDS) is a single user-level API which abstracts all communication between processes into the sharing and access coordination of memory regions, in a model which might be described as "distributed shared messages" or "large-grain distributed shared memory". As a result, the user programs to a simple latency-tolerant abstract communication specification which can be mapped efficiently to either a shared-memory or message-passing based run-time system, depending upon the available architecture. Unlike some distributed shared memory interfaces, the user still has complete control over the assignment of data to processors, the forwarding of data to its next likely destination, and the queuing of data until it is needed, so even the relatively high latency present in clusters can be accomodated. CDS does not require special use of an MMU, which can add overhead to some DSM systems, and does not require an SPMD programming model. unlike some message-passing interfaces, CDS allows the user to implement efficient demand-driven applications where processes must "fight" over data, and does not perform copying if processes share memory and do not attempt concurrent writes. CDS also supports heterogeneous computing, dynamic process creation, handlers, and a very simple thread-arbitration mechanism. Additional support for array subsections is currently being considered. The CDS1 API, which forms the kernel of CDS, is built primarily upon only 2 communication primitives, one process initiation primitive, and some data translation (and marshalling) routines, memory allocation routines, and priority control routines. The entire current collection of 28 routines provides enough functionality to implement most (or all) of MPI 1 and 2, which has a much larger interface consisting of hundreds of routines. still, the API is small enough to consider integrating into standard os interfaces for handling inter-process communication in a network-independent way. This approach would also help to solve many of the problems plaguing other higher-level standards such as MPI and PVM which must, in some cases, "play OS" to adequately address progress and process control issues. The CDS2 API, a higher level of interface roughly equivalent in functionality to MPI and to be built entirely upon CDS1, is still being designed. It is intended to add support for the equivalent of communicators, reduction and other collective operations, process topologies, additional support for process creation, and some automatic memory management. CDS2 will not exactly match MPI, because the copy-free semantics of communication from CDS1 will be supported. CDS2 application programs will be free to carefully also use CDS1. CDS1 has been implemented on networks of workstations running unmodified Unix-based operating systems, using UDP/IP and vendor-supplied high- performance locks. Although its inter-node performance is currently unimpressive due to rudimentary implementation technique, it even now outperforms highly-optimized MPI implementation on intra-node communication due to its support for non-copy communication. The similarity of the CDS1 architecture to that of other projects such as UNET and TRAP suggests that the inter-node performance can be increased significantly to surpass MPI or PVM, and it may be possible to migrate some of its functionality to communication controllers.

Cognitive and behavioral evaluation of nutritional interventions in rodent models of brain aging and dementia

PubMed Central

Wahl, Devin; Coogan, Sean CP; Solon-Biet, Samantha M; de Cabo, Rafael; Haran, James B; Raubenheimer, David; Cogger, Victoria C; Mattson, Mark P; Simpson, Stephen J; Le Couteur, David G

2017-01-01

Evaluation of behavior and cognition in rodent models underpins mechanistic and interventional studies of brain aging and neurodegenerative diseases, especially dementia. Commonly used tests include Morris water maze, Barnes maze, object recognition, fear conditioning, radial arm water maze, and Y maze. Each of these tests reflects some aspects of human memory including episodic memory, recognition memory, semantic memory, spatial memory, and emotional memory. Although most interventional studies in rodent models of dementia have focused on pharmacological agents, there are an increasing number of studies that have evaluated nutritional interventions including caloric restriction, intermittent fasting, and manipulation of macronutrients. Dietary interventions have been shown to influence various cognitive and behavioral tests in rodents indicating that nutrition can influence brain aging and possibly neurodegeneration. PMID:28932108

Superdiffusion in a non-Markovian random walk model with a Gaussian memory profile

NASA Astrophysics Data System (ADS)

Borges, G. M.; Ferreira, A. S.; da Silva, M. A. A.; Cressoni, J. C.; Viswanathan, G. M.; Mariz, A. M.

2012-09-01

Most superdiffusive Non-Markovian random walk models assume that correlations are maintained at all time scales, e.g., fractional Brownian motion, Lévy walks, the Elephant walk and Alzheimer walk models. In the latter two models the random walker can always "remember" the initial times near t = 0. Assuming jump size distributions with finite variance, the question naturally arises: is superdiffusion possible if the walker is unable to recall the initial times? We give a conclusive answer to this general question, by studying a non-Markovian model in which the walker's memory of the past is weighted by a Gaussian centered at time t/2, at which time the walker had one half the present age, and with a standard deviation σt which grows linearly as the walker ages. For large widths we find that the model behaves similarly to the Elephant model, but for small widths this Gaussian memory profile model behaves like the Alzheimer walk model. We also report that the phenomenon of amnestically induced persistence, known to occur in the Alzheimer walk model, arises in the Gaussian memory profile model. We conclude that memory of the initial times is not a necessary condition for generating (log-periodic) superdiffusion. We show that the phenomenon of amnestically induced persistence extends to the case of a Gaussian memory profile.

On climate prediction: how much can we expect from climate memory?

NASA Astrophysics Data System (ADS)

Yuan, Naiming; Huang, Yan; Duan, Jianping; Zhu, Congwen; Xoplaki, Elena; Luterbacher, Jürg

2018-03-01

Slowing variability in climate system is an important source of climate predictability. However, it is still challenging for current dynamical models to fully capture the variability as well as its impacts on future climate. In this study, instead of simulating the internal multi-scale oscillations in dynamical models, we discussed the effects of internal variability in terms of climate memory. By decomposing climate state x(t) at a certain time point t into memory part M(t) and non-memory part ɛ (t) , climate memory effects from the past 30 years on climate prediction are quantified. For variables with strong climate memory, high variance (over 20% ) in x(t) is explained by the memory part M(t), and the effects of climate memory are non-negligible for most climate variables, but the precipitation. Regarding of multi-steps climate prediction, a power law decay of the explained variance was found, indicating long-lasting climate memory effects. The explained variances by climate memory can remain to be higher than 10% for more than 10 time steps. Accordingly, past climate conditions can affect both short (monthly) and long-term (interannual, decadal, or even multidecadal) climate predictions. With the memory part M(t) precisely calculated from Fractional Integral Statistical Model, one only needs to focus on the non-memory part ɛ (t) , which is an important quantity that determines climate predictive skills.

Strategies To Enhance Memory Based on Brain-Research.

ERIC Educational Resources Information Center

Banikowski, Alison K.; Mehring, Teresa A.

1999-01-01

This article reviews the literature on three aspects of memory: (1) an information processing model of memory (including the sensory register, attention, short-term memory, and long-term memory); (2) instructional strategies designed to enhance memory (which stress gaining students' attention and active involvement); and (3) reasons why…

Test and Evaluation Report of the IVAC (Trademark) Vital Check Monitor Model 4000AEE

DTIC Science & Technology

1992-02-01

AD-A248 834 111111 jIf+l l’ l USAARL Report No. 92-14 Test and Evaluation Report of the IVAC® Vital Check Monitor DTI ~cModel 4000AEE f ELECTE APR17...does not constitute an official Department of the Army endorsement or approval of the use ot such commercial items. Reviewed: DENNIS F . SHANAHAN LTC, MC...to 12.4 GHz) was scanned for emissions. The IVACO Model 4000AEE was operated with both ac and battery power. 2.10.3.2 The radiated susceptibility

Automated Verification of Specifications with Typestates and Access Permissions

NASA Technical Reports Server (NTRS)

Siminiceanu, Radu I.; Catano, Nestor

2011-01-01

We propose an approach to formally verify Plural specifications based on access permissions and typestates, by model-checking automatically generated abstract state-machines. Our exhaustive approach captures all the possible behaviors of abstract concurrent programs implementing the specification. We describe the formal methodology employed by our technique and provide an example as proof of concept for the state-machine construction rules. The implementation of a fully automated algorithm to generate and verify models, currently underway, provides model checking support for the Plural tool, which currently supports only program verification via data flow analysis (DFA).

Working memory capacity and overgeneral autobiographical memory in young and older adults.

PubMed

Ros, Laura; Latorre, José Miguel; Serrano, Juan Pedro

2010-01-01

The objectives of this study are to compare the Autobiographical Memory Test (AMT) performance of two healthy samples of younger and older adults and to analyse the relationship between overgeneral memory (OGM) and working memory executive processes (WMEP) using a structural equation modelling with latent variables. The AMT and sustained attention, short-term memory and working memory tasks were administered to a group of young adults (N = 50) and a group of older adults (N = 46). On the AMT, the older adults recalled a greater number of categorical memories (p = .000) and fewer specific memories (p = .000) than the young adults, confirming that OGM occurs in the normal population and increases with age. WMEP was measured by reading span and a working memory with sustained attention load task. Structural equation modelling reflects that WMEP shows a strong relationship with OGM: lower scores on WMEP reflect an OGM phenomenon characterized by higher categorical and lower specific memories.

A Neural Network Model of Retrieval-Induced Forgetting

ERIC Educational Resources Information Center

Norman, Kenneth A.; Newman, Ehren L.; Detre, Greg

2007-01-01

Retrieval-induced forgetting (RIF) refers to the finding that retrieving a memory can impair subsequent recall of related memories. Here, the authors present a new model of how the brain gives rise to RIF in both semantic and episodic memory. The core of the model is a recently developed neural network learning algorithm that leverages regular…

Optical Associative Memory Model With Threshold Modification Using Complementary Vector

NASA Astrophysics Data System (ADS)

Bian, Shaoping; Xu, Kebin; Hong, Jing

1989-02-01

A new criterion to evaluate the similarity between two vectors in associative memory is presented. According to it, an experimental research about optical associative memory model with threshold modification using complementary vector is carried out. This model is capable of eliminating the posibility to recall erroneously. Therefore the accuracy of reading out is improved.

A Revised Model of Short-Term Memory and Long-Term Learning of Verbal Sequences

ERIC Educational Resources Information Center

Burgess, Neil; Hitch, Graham J.

2006-01-01

The interaction between short- and long-term memory is studied within a model in which phonemic and (temporal) contextual information have separate influences on immediate verbal serial recall via connections with short- and long-term plasticity [Burgess, N., & Hitch, G.J. (1999). Memory for serial order: a network model of the phonological loop…

The memory state heuristic: A formal model based on repeated recognition judgments.

PubMed

Castela, Marta; Erdfelder, Edgar

2017-02-01

The recognition heuristic (RH) theory predicts that, in comparative judgment tasks, if one object is recognized and the other is not, the recognized one is chosen. The memory-state heuristic (MSH) extends the RH by assuming that choices are not affected by recognition judgments per se, but by the memory states underlying these judgments (i.e., recognition certainty, uncertainty, or rejection certainty). Specifically, the larger the discrepancy between memory states, the larger the probability of choosing the object in the higher state. The typical RH paradigm does not allow estimation of the underlying memory states because it is unknown whether the objects were previously experienced or not. Therefore, we extended the paradigm by repeating the recognition task twice. In line with high threshold models of recognition, we assumed that inconsistent recognition judgments result from uncertainty whereas consistent judgments most likely result from memory certainty. In Experiment 1, we fitted 2 nested multinomial models to the data: an MSH model that formalizes the relation between memory states and binary choices explicitly and an approximate model that ignores the (unlikely) possibility of consistent guesses. Both models provided converging results. As predicted, reliance on recognition increased with the discrepancy in the underlying memory states. In Experiment 2, we replicated these results and found support for choice consistency predictions of the MSH. Additionally, recognition and choice latencies were in agreement with the MSH in both experiments. Finally, we validated critical parameters of our MSH model through a cross-validation method and a third experiment. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Using chaotic artificial neural networks to model memory in the brain

NASA Astrophysics Data System (ADS)

Aram, Zainab; Jafari, Sajad; Ma, Jun; Sprott, Julien C.; Zendehrouh, Sareh; Pham, Viet-Thanh

2017-03-01

In the current study, a novel model for human memory is proposed based on the chaotic dynamics of artificial neural networks. This new model explains a biological fact about memory which is not yet explained by any other model: There are theories that the brain normally works in a chaotic mode, while during attention it shows ordered behavior. This model uses the periodic windows observed in a previously proposed model for the brain to store and then recollect the information.

Testing episodic memory in animals: a new approach.

PubMed

Griffiths, D P; Clayton, N S

2001-08-01

Episodic memory involves the encoding and storage of memories concerned with unique personal experiences and their subsequent recall, and it has long been the subject of intensive investigation in humans. According to Tulving's classical definition, episodic memory "receives and stores information about temporally dated episodes or events and temporal-spatial relations among these events." Thus, episodic memory provides information about the 'what' and 'when' of events ('temporally dated experiences') and about 'where' they happened ('temporal-spatial relations'). The storage and subsequent recall of this episodic information was thought to be beyond the memory capabilities of nonhuman animals. Although there are many laboratory procedures for investigating memory for discrete past episodes, until recently there were no previous studies that fully satisfied the criteria of Tulving's definition: they can all be explained in much simpler terms than episodic memory. However, current studies of memory for cache sites in food-storing jays provide an ethologically valid model for testing episodic-like memory in animals, thereby bridging the gap between human and animal studies memory. There is now a pressing need to adapt these experimental tests of episodic memory for other animals. Given the potential power of transgenic and knock-out procedures for investigating the genetic and molecular bases of learning and memory in laboratory rodents, not to mention the wealth of knowledge about the neuroanatomy and neurophysiology of the rodent hippocampus (a brain area heavily implicated in episodic memory), an obvious next step is to develop a rodent model of episodic-like memory based on the food-storing bird paradigm. The development of a rodent model system could make an important contribution to our understanding of the neural, molecular, and behavioral mechanisms of mammalian episodic memory.

Utilisation of preventative health check-ups in the UK: findings from individual-level repeated cross-sectional data from 1992 to 2008

PubMed Central

Labeit, Alexander; Peinemann, Frank; Baker, Richard

2013-01-01

Objectives To analyse and compare the determinants of screening uptake for different National Health Service (NHS) health check-ups in the UK. Design Individual-level analysis of repeated cross-sectional surveys with balanced panel data. Setting The UK. Participants Individuals taking part in the British Household Panel Survey (BHPS), 1992–2008. Outcome measure Uptake of NHS health check-ups for cervical cancer screening, breast cancer screening, blood pressure checks, cholesterol tests, dental screening and eyesight tests. Methods Dynamic panel data models (random effects panel probit with initial conditions). Results Having had a health check-up 1 year before, and previously in accordance with the recommended schedule, was associated with higher uptake of health check-ups. Individuals who visited a general practitioner (GP) had a significantly higher uptake in 5 of the 6 health check-ups. Uptake was highest in the recommended age group for breast and cervical cancer screening. For all health check-ups, age had a non-linear relationship. Lower self-rated health status was associated with increased uptake of blood pressure checks and cholesterol tests; smoking was associated with decreased uptake of 4 health check-ups. The effects of socioeconomic variables differed for the different health check-ups. Ethnicity did not have a significant influence on any health check-up. Permanent household income had an influence only on eyesight tests and dental screening. Conclusions Common determinants for having health check-ups are age, screening history and a GP visit. Policy interventions to increase uptake should consider the central role of the GP in promoting screening examinations and in preserving a high level of uptake. Possible economic barriers to access for prevention exist for dental screening and eyesight tests, and could be a target for policy intervention. Trial registration This observational study was not registered. PMID:24366576

Personal semantics: at the crossroads of semantic and episodic memory.

PubMed

Renoult, Louis; Davidson, Patrick S R; Palombo, Daniela J; Moscovitch, Morris; Levine, Brian

2012-11-01

Declarative memory is usually described as consisting of two systems: semantic and episodic memory. Between these two poles, however, may lie a third entity: personal semantics (PS). PS concerns knowledge of one's past. Although typically assumed to be an aspect of semantic memory, it is essentially absent from existing models of knowledge. Furthermore, like episodic memory (EM), PS is idiosyncratically personal (i.e., not culturally-shared). We show that, depending on how it is operationalized, the neural correlates of PS can look more similar to semantic memory, more similar to EM, or dissimilar to both. We consider three different perspectives to better integrate PS into existing models of declarative memory and suggest experimental strategies for disentangling PS from semantic and episodic memory. Copyright © 2012 Elsevier Ltd. All rights reserved.

How can machine-learning methods assist in virtual screening for hyperuricemia? A healthcare machine-learning approach.

PubMed

Ichikawa, Daisuke; Saito, Toki; Ujita, Waka; Oyama, Hiroshi

2016-12-01

Our purpose was to develop a new machine-learning approach (a virtual health check-up) toward identification of those at high risk of hyperuricemia. Applying the system to general health check-ups is expected to reduce medical costs compared with administering an additional test. Data were collected during annual health check-ups performed in Japan between 2011 and 2013 (inclusive). We prepared training and test datasets from the health check-up data to build prediction models; these were composed of 43,524 and 17,789 persons, respectively. Gradient-boosting decision tree (GBDT), random forest (RF), and logistic regression (LR) approaches were trained using the training dataset and were then used to predict hyperuricemia in the test dataset. Undersampling was applied to build the prediction models to deal with the imbalanced class dataset. The results showed that the RF and GBDT approaches afforded the best performances in terms of sensitivity and specificity, respectively. The area under the curve (AUC) values of the models, which reflected the total discriminative ability of the classification, were 0.796 [95% confidence interval (CI): 0.766-0.825] for the GBDT, 0.784 [95% CI: 0.752-0.815] for the RF, and 0.785 [95% CI: 0.752-0.819] for the LR approaches. No significant differences were observed between pairs of each approach. Small changes occurred in the AUCs after applying undersampling to build the models. We developed a virtual health check-up that predicted the development of hyperuricemia using machine-learning methods. The GBDT, RF, and LR methods had similar predictive capability. Undersampling did not remarkably improve predictive power. Copyright © 2016 Elsevier Inc. All rights reserved.

Reopen parameter regions in two-Higgs doublet models

NASA Astrophysics Data System (ADS)

Staub, Florian

2018-01-01

The stability of the electroweak potential is a very important constraint for models of new physics. At the moment, it is standard for Two-Higgs doublet models (THDM), singlet or triplet extensions of the standard model to perform these checks at tree-level. However, these models are often studied in the presence of very large couplings. Therefore, it can be expected that radiative corrections to the potential are important. We study these effects at the example of the THDM type-II and find that loop corrections can revive more than 50% of the phenomenological viable points which are ruled out by the tree-level vacuum stability checks. Similar effects are expected for other extension of the standard model.

The Role of Life-Space, Social Activity, and Depression on the Subjective Memory Complaints of Community-Dwelling Filipino Elderly: A Structural Equation Model

ERIC Educational Resources Information Center

de Guzman, Allan B.; Lagdaan, Lovely France M.; Lagoy, Marie Lauren V.

2015-01-01

Subjective memory complaints are one of the major concerns of the elderly and remain a challenging area in gerontology. There are previous studies that identify different factors affecting subjective memory complaints. However, an extended model that correlates life-space on subjective memory complaints remains a blank spot. The objective of this…

No Evidence for a Fixed Object Limit in Working Memory: Spatial Ensemble Representations Inflate Estimates of Working Memory Capacity for Complex Objects

ERIC Educational Resources Information Center

Brady, Timothy F.; Alvarez, George A.

2015-01-01

A central question for models of visual working memory is whether the number of objects people can remember depends on object complexity. Some influential "slot" models of working memory capacity suggest that people always represent 3-4 objects and that only the fidelity with which these objects are represented is affected by object…

Histone Deacetylase Inhibition Induces Odor Preference Memory Extension and Maintains Enhanced AMPA Receptor Expression in the Rat Pup Model

ERIC Educational Resources Information Center

Bhattacharya, Sriya; Mukherjee, Bandhan; Doré, Jules J. E.; Yuan, Qi; Harley, Carolyn W.; McLean, John H.

2017-01-01

Histone deacetylase (HDAC) plays a role in synaptic plasticity and long-term memory formation. We hypothesized that trichostatin-A (TSA), an HDAC inhibitor, would promote long-term odor preference memory and maintain enhanced GluA1 receptor levels that have been hypothesized to support memory. We used an early odor preference learning model in…

Working memory for braille is shaped by experience.

PubMed

Cohen, Henri; Scherzer, Peter; Viau, Robert; Voss, Patrice; Lepore, Franco

2011-03-01

Tactile working memory was found to be more developed in completely blind (congenital and acquired) than in semi-sighted subjects, indicating that experience plays a crucial role in shaping working memory. A model of working memory, adapted from the classical model proposed by Baddeley and Hitch1 and Baddeley2 is presented where the connection strengths of a highly cross-modal network are altered through experience.

The contribution of attentional lapses to individual differences in visual working memory capacity.

PubMed

Adam, Kirsten C S; Mance, Irida; Fukuda, Keisuke; Vogel, Edward K

2015-08-01

Attentional control and working memory capacity are important cognitive abilities that substantially vary between individuals. Although much is known about how attentional control and working memory capacity relate to each other and to constructs like fluid intelligence, little is known about how trial-by-trial fluctuations in attentional engagement impact trial-by-trial working memory performance. Here, we employ a novel whole-report memory task that allowed us to distinguish between varying levels of attentional engagement in humans performing a working memory task. By characterizing low-performance trials, we can distinguish between models in which working memory performance failures are caused by either (1) complete lapses of attention or (2) variations in attentional control. We found that performance failures increase with set-size and strongly predict working memory capacity. Performance variability was best modeled by an attentional control model of attention, not a lapse model. We examined neural signatures of performance failures by measuring EEG activity while participants performed the whole-report task. The number of items correctly recalled in the memory task was predicted by frontal theta power, with decreased frontal theta power associated with poor performance on the task. In addition, we found that poor performance was not explained by failures of sensory encoding; the P1/N1 response and ocular artifact rates were equivalent for high- and low-performance trials. In all, we propose that attentional lapses alone cannot explain individual differences in working memory performance. Instead, we find that graded fluctuations in attentional control better explain the trial-by-trial differences in working memory that we observe.

Memory in a fractional-order cardiomyocyte model alters properties of alternans and spontaneous activity

NASA Astrophysics Data System (ADS)

Comlekoglu, T.; Weinberg, S. H.

2017-09-01

Cardiac memory is the dependence of electrical activity on the prior history of one or more system state variables, including transmembrane potential (Vm), ionic current gating, and ion concentrations. While prior work has represented memory either phenomenologically or with biophysical detail, in this study, we consider an intermediate approach of a minimal three-variable cardiomyocyte model, modified with fractional-order dynamics, i.e., a differential equation of order between 0 and 1, to account for history-dependence. Memory is represented via both capacitive memory, due to fractional-order Vm dynamics, that arises due to non-ideal behavior of membrane capacitance; and ionic current gating memory, due to fractional-order gating variable dynamics, that arises due to gating history-dependence. We perform simulations for varying Vm and gating variable fractional-orders and pacing cycle length and measure action potential duration (APD) and incidence of alternans, loss of capture, and spontaneous activity. In the absence of ionic current gating memory, we find that capacitive memory, i.e., decreased Vm fractional-order, typically shortens APD, suppresses alternans, and decreases the minimum cycle length (MCL) for loss of capture. However, in the presence of ionic current gating memory, capacitive memory can prolong APD, promote alternans, and increase MCL. Further, we find that reduced Vm fractional order (typically less than 0.75) can drive phase 4 depolarizations that promote spontaneous activity. Collectively, our results demonstrate that memory reproduced by a fractional-order model can play a role in alternans formation and pacemaking, and in general, can greatly increase the range of electrophysiological characteristics exhibited by a minimal model.

The Contribution of Attentional Lapses to Individual Differences in Visual Working Memory Capacity

PubMed Central

Adam, Kirsten C. S.; Mance, Irida; Fukuda, Keisuke; Vogel, Edward K.

2015-01-01

Attentional control and working memory capacity are important cognitive abilities that substantially vary between individuals. Although much is known about how attentional control and working memory capacity relate to each other and to constructs like fluid intelligence, little is known about how trial-by-trial fluctuations in attentional engagement impact trial-by-trial working memory performance. Here, we employ a novel whole-report memory task that allowed us to distinguish between varying levels of attentional engagement in humans performing a working memory task. By characterizing low-performance trials, we can distinguish between models in which working memory performance failures are caused by either (1) complete lapses of attention or (2) variations in attentional control. We found that performance failures increase with set-size and strongly predict working memory capacity. Performance variability was best modeled by an attentional control model of attention, not a lapse model. We examined neural signatures of performance failures by measuring EEG activity while participants performed the whole-report task. The number of items correctly recalled in the memory task was predicted by frontal theta power, with decreased frontal theta power associated with poor performance on the task. In addition, we found that poor performance was not explained by failures of sensory encoding; the P1/N1 response and ocular artifact rates were equivalent for high- and low-performance trials. In all, we propose that attentional lapses alone cannot explain individual differences in working memory performance. Instead, we find that graded fluctuations in attentional control better explain the trial-by-trial differences in working memory that we observe. PMID:25811710

Toxin-Induced Experimental Models of Learning and Memory Impairment

PubMed Central

More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug

2016-01-01

Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson’s disease dementia and Alzheimer’s disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders. PMID:27598124

Toxin-Induced Experimental Models of Learning and Memory Impairment.

PubMed

More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug

2016-09-01

Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson's disease dementia and Alzheimer's disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders.

A Comparative Study of the Effects of the Neurocognitive-Based Model and the Conventional Model on Learner Attention, Working Memory and Mood

ERIC Educational Resources Information Center

Srikoon, Sanit; Bunterm, Tassanee; Nethanomsak, Teerachai; Ngang, Tang Keow

2017-01-01

Purpose: The attention, working memory, and mood of learners are the most important abilities in the learning process. This study was concerned with the comparison of contextualized attention, working memory, and mood through a neurocognitive-based model (5P) and a conventional model (5E). It sought to examine the significant change in attention,…

Verification of Compartmental Epidemiological Models using Metamorphic Testing, Model Checking and Visual Analytics

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

Ramanathan, Arvind; Steed, Chad A; Pullum, Laura L

Compartmental models in epidemiology are widely used as a means to model disease spread mechanisms and understand how one can best control the disease in case an outbreak of a widespread epidemic occurs. However, a significant challenge within the community is in the development of approaches that can be used to rigorously verify and validate these models. In this paper, we present an approach to rigorously examine and verify the behavioral properties of compartmen- tal epidemiological models under several common modeling scenarios including birth/death rates and multi-host/pathogen species. Using metamorphic testing, a novel visualization tool and model checking, we buildmore » a workflow that provides insights into the functionality of compartmental epidemiological models. Our initial results indicate that metamorphic testing can be used to verify the implementation of these models and provide insights into special conditions where these mathematical models may fail. The visualization front-end allows the end-user to scan through a variety of parameters commonly used in these models to elucidate the conditions under which an epidemic can occur. Further, specifying these models using a process algebra allows one to automatically construct behavioral properties that can be rigorously verified using model checking. Taken together, our approach allows for detecting implementation errors as well as handling conditions under which compartmental epidemiological models may fail to provide insights into disease spread dynamics.« less

The construction of meaning.

PubMed

Kintsch, Walter; Mangalath, Praful

2011-04-01

We argue that word meanings are not stored in a mental lexicon but are generated in the context of working memory from long-term memory traces that record our experience with words. Current statistical models of semantics, such as latent semantic analysis and the Topic model, describe what is stored in long-term memory. The CI-2 model describes how this information is used to construct sentence meanings. This model is a dual-memory model, in that it distinguishes between a gist level and an explicit level. It also incorporates syntactic information about how words are used, derived from dependency grammar. The construction of meaning is conceptualized as feature sampling from the explicit memory traces, with the constraint that the sampling must be contextually relevant both semantically and syntactically. Semantic relevance is achieved by sampling topically relevant features; local syntactic constraints as expressed by dependency relations ensure syntactic relevance. Copyright © 2010 Cognitive Science Society, Inc.

Overlapping parietal activity in memory and perception: evidence for the attention to memory model.

PubMed

Cabeza, Roberto; Mazuz, Yonatan S; Stokes, Jared; Kragel, James E; Woldorff, Marty G; Ciaramelli, Elisa; Olson, Ingrid R; Moscovitch, Morris

2011-11-01

The specific role of different parietal regions to episodic retrieval is a topic of intense debate. According to the Attention to Memory (AtoM) model, dorsal parietal cortex (DPC) mediates top-down attention processes guided by retrieval goals, whereas ventral parietal cortex (VPC) mediates bottom-up attention processes captured by the retrieval output or the retrieval cue. This model also hypothesizes that the attentional functions of DPC and VPC are similar for memory and perception. To investigate this last hypothesis, we scanned participants with event-related fMRI whereas they performed memory and perception tasks, each comprising an orienting phase (top-down attention) and a detection phase (bottom-up attention). The study yielded two main findings. First, consistent with the AtoM model, orienting-related activity for memory and perception overlapped in DPC, whereas detection-related activity for memory and perception overlapped in VPC. The DPC overlap was greater in the left intraparietal sulcus, and the VPC overlap in the left TPJ. Around overlapping areas, there were differences in the spatial distribution of memory and perception activations, which were consistent with trends reported in the literature. Second, both DPC and VPC showed stronger connectivity with medial-temporal lobe during the memory task and with visual cortex during the perception task. These findings suggest that, during memory tasks, some parietal regions mediate similar attentional control processes to those involved in perception tasks (orienting in DPC vs. detection in VPC), although on different types of information (mnemonic vs. sensory).

10 CFR 35.2642 - Records of periodic spot-checks for teletherapy units.

Code of Federal Regulations, 2010 CFR

2010-01-01

....2642 Section 35.2642 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records... must include— (1) The date of the spot-check; (2) The manufacturer's name, model number, and serial... device; (6) The determined accuracy of each distance measuring and localization device; (7) The...

10 CFR 35.2642 - Records of periodic spot-checks for teletherapy units.

Code of Federal Regulations, 2011 CFR

2011-01-01

....2642 Section 35.2642 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Records... must include— (1) The date of the spot-check; (2) The manufacturer's name, model number, and serial... device; (6) The determined accuracy of each distance measuring and localization device; (7) The...

12 CFR Appendix A to Part 205 - Model Disclosure Clauses and Forms

Code of Federal Regulations, 2010 CFR

2010-01-01

... your checking account using information from your check to: (i) Pay for purchases. (ii) Pay bills. (3... disclose information to third parties about your account or the transfers you make: (i) Where it is...) Disclosure by government agencies of information about obtaining account balances and account histories...

Using computer models to design gully erosion control structures for humid northern Ethiopia

USDA-ARS?s Scientific Manuscript database

Classic gully erosion control measures such as check dams have been unsuccessful in halting gully formation and growth in the humid northern Ethiopian highlands. Gullies are typically formed in vertisols and flow often bypasses the check dams as elevated groundwater tables make gully banks unstable....

Posterior Predictive Checks for Conditional Independence between Response Time and Accuracy

ERIC Educational Resources Information Center

Bolsinova, Maria; Tijmstra, Jesper

2016-01-01

Conditional independence (CI) between response time and response accuracy is a fundamental assumption of many joint models for time and accuracy used in educational measurement. In this study, posterior predictive checks (PPCs) are proposed for testing this assumption. These PPCs are based on three discrepancy measures reflecting different…

Building Program Verifiers from Compilers and Theorem Provers

DTIC Science & Technology

2015-05-14

Checking with SMT UFO • LLVM-based front-end (partially reused in SeaHorn) • Combines Abstract Interpretation with Interpolation-Based Model Checking • (no...assertions Counter-examples are long Hard to determine (from main) what is relevant Assertion Main 35 Building Verifiers from Comp and SMT Gurfinkel, 2015

Leveling up the analysis of the reminiscence bump in autobiographical memory: A new approach based on multilevel multinomial models.

PubMed

Zimprich, Daniel; Wolf, Tabea

2018-06-20

In many studies of autobiographical memory, participants are asked to generate more than one autobiographical memory. The resulting data then have a hierarchical or multilevel structure, in the sense that the autobiographical memories (Level 1) generated by the same person (Level 2) tend to be more similar. Transferred to an analysis of the reminiscence bump in autobiographical memory, at Level 1 the prediction of whether an autobiographical memory will fall within the reminiscence bump is based on the characteristics of that memory. At Level 2, the prediction of whether an individual will report more autobiographical memories that fall in the reminiscence bump is based on the characteristics of the individual. We suggest a multilevel multinomial model that allows for analyzing whether an autobiographical memory falls in the reminiscence bump at both levels of analysis simultaneously. The data come from 100 older participants who reported up to 33 autobiographical memories. Our results showed that about 12% of the total variance was between persons (Level 2). Moreover, at Level 1, memories of first-time experiences were more likely to fall in the reminiscence bump than were emotionally more positive memories. At Level 2, persons who reported more emotionally positive memories tended to report fewer memories from the life period after the reminiscence bump. In addition, cross-level interactions showed that the effects at Level 1 partly depended on the Level 2 effects. We discuss possible extensions of the model we present and the meaning of our findings for two prominent explanatory approaches to the reminiscence bump, as well as future directions.

Developing a hippocampal neural prosthetic to facilitate human memory encoding and recall.

PubMed

Hampson, Robert E; Song, Dong; Robinson, Brian S; Fetterhoff, Dustin; Dakos, Alexander S; Roeder, Brent M; She, Xiwei; Wicks, Robert T; Witcher, Mark R; Couture, Daniel E; Laxton, Adrian W; Munger-Clary, Heidi; Popli, Gautam; Sollman, Myriam J; Whitlow, Christopher T; Marmarelis, Vasilis Z; Berger, Theodore W; Deadwyler, Sam A

2018-06-01

We demonstrate here the first successful implementation in humans of a proof-of-concept system for restoring and improving memory function via facilitation of memory encoding using the patient's own hippocampal spatiotemporal neural codes for memory. Memory in humans is subject to disruption by drugs, disease and brain injury, yet previous attempts to restore or rescue memory function in humans typically involved only nonspecific, modulation of brain areas and neural systems related to memory retrieval. We have constructed a model of processes by which the hippocampus encodes memory items via spatiotemporal firing of neural ensembles that underlie the successful encoding of short-term memory. A nonlinear multi-input, multi-output (MIMO) model of hippocampal CA3 and CA1 neural firing is computed that predicts activation patterns of CA1 neurons during the encoding (sample) phase of a delayed match-to-sample (DMS) human short-term memory task. MIMO model-derived electrical stimulation delivered to the same CA1 locations during the sample phase of DMS trials facilitated short-term/working memory by 37% during the task. Longer term memory retention was also tested in the same human subjects with a delayed recognition (DR) task that utilized images from the DMS task, along with images that were not from the task. Across the subjects, the stimulated trials exhibited significant improvement (35%) in both short-term and long-term retention of visual information. These results demonstrate the facilitation of memory encoding which is an important feature for the construction of an implantable neural prosthetic to improve human memory.

Developing a hippocampal neural prosthetic to facilitate human memory encoding and recall

NASA Astrophysics Data System (ADS)

Hampson, Robert E.; Song, Dong; Robinson, Brian S.; Fetterhoff, Dustin; Dakos, Alexander S.; Roeder, Brent M.; She, Xiwei; Wicks, Robert T.; Witcher, Mark R.; Couture, Daniel E.; Laxton, Adrian W.; Munger-Clary, Heidi; Popli, Gautam; Sollman, Myriam J.; Whitlow, Christopher T.; Marmarelis, Vasilis Z.; Berger, Theodore W.; Deadwyler, Sam A.

2018-06-01

Objective. We demonstrate here the first successful implementation in humans of a proof-of-concept system for restoring and improving memory function via facilitation of memory encoding using the patient’s own hippocampal spatiotemporal neural codes for memory. Memory in humans is subject to disruption by drugs, disease and brain injury, yet previous attempts to restore or rescue memory function in humans typically involved only nonspecific, modulation of brain areas and neural systems related to memory retrieval. Approach. We have constructed a model of processes by which the hippocampus encodes memory items via spatiotemporal firing of neural ensembles that underlie the successful encoding of short-term memory. A nonlinear multi-input, multi-output (MIMO) model of hippocampal CA3 and CA1 neural firing is computed that predicts activation patterns of CA1 neurons during the encoding (sample) phase of a delayed match-to-sample (DMS) human short-term memory task. Main results. MIMO model-derived electrical stimulation delivered to the same CA1 locations during the sample phase of DMS trials facilitated short-term/working memory by 37% during the task. Longer term memory retention was also tested in the same human subjects with a delayed recognition (DR) task that utilized images from the DMS task, along with images that were not from the task. Across the subjects, the stimulated trials exhibited significant improvement (35%) in both short-term and long-term retention of visual information. Significance. These results demonstrate the facilitation of memory encoding which is an important feature for the construction of an implantable neural prosthetic to improve human memory.

A simplified conjoint recognition paradigm for the measurement of gist and verbatim memory.

PubMed

Stahl, Christoph; Klauer, Karl Christoph

2008-05-01

The distinction between verbatim and gist memory traces has furthered the understanding of numerous phenomena in various fields, such as false memory research, research on reasoning and decision making, and cognitive development. To measure verbatim and gist memory empirically, an experimental paradigm and multinomial measurement model has been proposed but rarely applied. In the present article, a simplified conjoint recognition paradigm and multinomial model is introduced and validated as a measurement tool for the separate assessment of verbatim and gist memory processes. A Bayesian metacognitive framework is applied to validate guessing processes. Extensions of the model toward incorporating the processes of phantom recollection and erroneous recollection rejection are discussed.

Statistical prediction with Kanerva's sparse distributed memory

NASA Technical Reports Server (NTRS)

Rogers, David

1989-01-01

A new viewpoint of the processing performed by Kanerva's sparse distributed memory (SDM) is presented. In conditions of near- or over-capacity, where the associative-memory behavior of the model breaks down, the processing performed by the model can be interpreted as that of a statistical predictor. Mathematical results are presented which serve as the framework for a new statistical viewpoint of sparse distributed memory and for which the standard formulation of SDM is a special case. This viewpoint suggests possible enhancements to the SDM model, including a procedure for improving the predictiveness of the system based on Holland's work with genetic algorithms, and a method for improving the capacity of SDM even when used as an associative memory.

Performance analysis and comparison of a minimum interconnections direct storage model with traditional neural bidirectional memories.

PubMed

Bhatti, A Aziz

2009-12-01

This study proposes an efficient and improved model of a direct storage bidirectional memory, improved bidirectional associative memory (IBAM), and emphasises the use of nanotechnology for efficient implementation of such large-scale neural network structures at a considerable lower cost reduced complexity, and less area required for implementation. This memory model directly stores the X and Y associated sets of M bipolar binary vectors in the form of (MxN(x)) and (MxN(y)) memory matrices, requires O(N) or about 30% of interconnections with weight strength ranging between +/-1, and is computationally very efficient as compared to sequential, intraconnected and other bidirectional associative memory (BAM) models of outer-product type that require O(N(2)) complex interconnections with weight strength ranging between +/-M. It is shown that it is functionally equivalent to and possesses all attributes of a BAM of outer-product type, and yet it is simple and robust in structure, very large scale integration (VLSI), optical and nanotechnology realisable, modular and expandable neural network bidirectional associative memory model in which the addition or deletion of a pair of vectors does not require changes in the strength of interconnections of the entire memory matrix. The analysis of retrieval process, signal-to-noise ratio, storage capacity and stability of the proposed model as well as of the traditional BAM has been carried out. Constraints on and characteristics of unipolar and bipolar binaries for improved storage and retrieval are discussed. The simulation results show that it has log(e) N times higher storage capacity, superior performance, faster convergence and retrieval time, when compared to traditional sequential and intraconnected bidirectional memories.

NAAG Peptidase Inhibitors Act via mGluR3: Animal Models of Memory, Alzheimer's, and Ethanol Intoxication.

PubMed

Olszewski, Rafal T; Janczura, Karolina J; Bzdega, Tomasz; Der, Elise K; Venzor, Faustino; O'Rourke, Brennen; Hark, Timothy J; Craddock, Kirsten E; Balasubramanian, Shankar; Moussa, Charbel; Neale, Joseph H

2017-09-01

Glutamate carboxypeptidase II (GCPII) inactivates the peptide neurotransmitter N-acetylaspartylglutamate (NAAG) following synaptic release. Inhibitors of GCPII increase extracellular NAAG levels and are efficacious in animal models of clinical disorders via NAAG activation of a group II metabotropic glutamate receptor. mGluR2 and mGluR3 knock-out (ko) mice were used to test the hypothesis that mGluR3 mediates the activity of GCPII inhibitors ZJ43 and 2-PMPA in animal models of memory and memory loss. Short- (1.5 h) and long- (24 h) term novel object recognition tests were used to assess memory. Treatment with ZJ43 or 2-PMPA prior to acquisition trials increased long-term memory in mGluR2, but not mGluR3, ko mice. Nine month-old triple transgenic Alzheimer's disease model mice exhibited impaired short-term novel object recognition memory that was rescued by treatment with a NAAG peptidase inhibitor. NAAG peptidase inhibitors and the group II mGluR agonist, LY354740, reversed the short-term memory deficit induced by acute ethanol administration in wild type mice. 2-PMPA also moderated the effect of ethanol on short-term memory in mGluR2 ko mice but failed to do so in mGluR3 ko mice. LY354740 and ZJ43 blocked ethanol-induced motor activation. Both GCPII inhibitors and LY354740 also significantly moderated the loss of motor coordination induced by 2.1 g/kg ethanol treatment. These data support the conclusion that inhibitors of glutamate carboxypeptidase II are efficacious in object recognition models of normal memory and memory deficits via an mGluR3 mediated process, actions that could have widespread clinical applications.

Self-defining memories, scripts, and the life story: narrative identity in personality and psychotherapy.

PubMed

Singer, Jefferson A; Blagov, Pavel; Berry, Meredith; Oost, Kathryn M

2013-12-01

An integrative model of narrative identity builds on a dual memory system that draws on episodic memory and a long-term self to generate autobiographical memories. Autobiographical memories related to critical goals in a lifetime period lead to life-story memories, which in turn become self-defining memories when linked to an individual's enduring concerns. Self-defining memories that share repetitive emotion-outcome sequences yield narrative scripts, abstracted templates that filter cognitive-affective processing. The life story is the individual's overarching narrative that provides unity and purpose over the life course. Healthy narrative identity combines memory specificity with adaptive meaning-making to achieve insight and well-being, as demonstrated through a literature review of personality and clinical research, as well as new findings from our own research program. A clinical case study drawing on this narrative identity model is also presented with implications for treatment and research. © 2012 Wiley Periodicals, Inc.

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.