Results for memory  
Title: A High Performance Decimal Matrix Code Architecture for Improved Reliable Memory
Abstract:

Protection codes are necessary to shield memory cells, to maintain good quality level of reliability. But, we don’t find any optimized error detection and correction methods. Therefore, in this paper, we present a high performance Decimal Matrix Code to assure the reliability of memory. This protection code utilizes decimal procedure to detect errors, so that more errors were detected and corrected up to 32. Transient multiple cell upsets (MCUs) are major problems in the reliability of memories exposed to radiation environment. To prevent cell upsets from causing data corruption, more complex error correction codes (ECCs) are widely used to protect memory, but they would require higher delay so an efficient ERT (encoder-reuse technique) is proposed to reduce the area overhead of extra circuits, it utilize DMC encoder itself to be part of the decoder.


Sources: Omics Online
Keywords: Error correction codes (ECCs),multiple cells upsets (MCUs),memory.,
Title: A model for long memory conditional heteroscedasticity
Abstract:
For a particular conditionally heteroscedastic nonlinear (ARCH) process for which the conditional variance of the observable sequence rt is the square of an inhomogeneous linear combination of rs, s 2, r' has long memory autocorrelation and normalized partial sums of ri converge to fractional Brownian motion.

Sources: Mendeley
Keywords: long-memory,
Title: Long memory volatility in Chinese stock markets
Abstract:
In this study, the long memory property in the volatility of Chinese stock markets is examined. For this purpose, we applied two semi-parametric tests (GPH and LW) and the FIGARCH model, to four Chinese market indices: Shanghai A, Shanghai B, Shenzhen A and Shenzhen B. From the results of our analysis, we can conclude that the volatility of Chinese stock markets exhibits long memory features, and that the assumption of non-normality provides better specifications regarding long memory volatility processes.

Sources: Mendeley
Keywords: long-memory,
Title: Long memory of rivers from spatial aggregation
Abstract:
Long memory is a hydrological property that can lead to prolonged droughts or the temporal clustering of extreme floods in a river. Analyses of 28 long (up to 145 years), continuous instrumental runoff series from six European, American, and African rivers reveal that this effect increases downstream. Simulations reproduce the increase qualitatively and show that a river network aggregates short-memory precipitation and converts it into long-memory runoff. In view of projected changes in climate and the hydrological cycle, these findings show that decadal-scale variations in drought or flood risk can be predicted for individual rivers, with higher predictability downstream. Spatial aggregation may also explain the emergence of long memory in other networks, such as the brain or those formed by computers.

Sources: Mendeley
Keywords: long-memory,
Title: Long memory and persistence in aggregate output
Abstract:
We examine persistence in U.S. aggregate output by estimating fractionally integrated ARIMA models. These models provide better low-frequency approximations to the Wold representation than previous stochastic specifications, and earlier results on the importance of a permanent component emerge as special cases. We find evidence of long memory, which induces persistence, though this long memory need not be associated with a unit root. Our point estimates indicate that macroeconomic shocks, while persistent, are distinctly less persistent than many earlier studies suggest; however, confidence intervals associated with the long-run response are quite wide.

Sources: Mendeley
Keywords: long-memory,
Title: Long-Memory Processes
Abstract:
Long-memory processes are known to play an important part in many areas of science and technology, including physics, geophysics, hydrology, telecommunications, economics, finance, climatology, and network engineering. In the last 20 years enormous progress has been made in understanding the probabilistic foundations and statistical principles of such processes. This book provides a timely and comprehensive review, including a thorough discussion of mathematical and probabilistic foundations and statistical methods, emphasizing their practical motivation and mathematical justification. Proofs of the main theorems are provided and data examples illustrate practical aspects. This book will be a valuable resource for researchers and graduate students in statistics, mathematics, econometrics and other quantitative areas, as well as for practitioners and applied researchers who need to analyze data in which long memory, power laws, self-similar scaling or fractal properties are relevant.

Sources: Mendeley
Keywords: long-memory,
Title: Differential Effects of Binge Drinking on Learning and Memory in Emerging Adults
Abstract:

Alterations in memory function due to alcohol exposure have been observed in both animal models and human populations. The human literature on neurocognitive consequences of binge alcohol use in emerging adults has not systematically investigated its potential negative impacts on visuospatial memory. For instance, these impacts have not yet been assessed using a human analogue of the Morris Water Maze Task (WMT), a key memory measure in the animal literature. Accordingly, this study compared performance between emerging adult binge drinkers (BD, n=22) and age- and sex-matched light drinkers (LD, n=29) using the Morris WMT, as well as verbal memory using the California Verbal Learning Test (CVLT). Emerging adult BD demonstrated worse performance on verbal learning and memory relative to LD. However, no significant group differences were observed on spatial learning and memory. Furthermore, no sex differences or interactions with drinking status were observed on either memory domain. These data suggest that in emerging adults who are at a heightened risk for alcohol abuse disorders, but who do not yet meet diagnostic criteria, verbal learning is uniquely impacted by the neurotoxic effects of binge drinking, whereas spatial learning is relatively spared between bouts of intoxication.


Sources: Omics Online
Keywords: Emerging adulthood,Binge drinking,Spatial memory,Verbal memory,WMT,CVLT,
Title: Prospective memory and divided attention
Abstract:
In three experiments, we manipulated the processing demands of a concurrent task to test the hypothesis that an event-based prospective memory task satisfies a criterion of automaticity proposed by Hasher and Zacks (1979). As in the previous studies, a prospective memory task (pressing a key whenever a target word was presented) was embedded within a short-term memory task (remembering seven words). In addition, participants performed a concurrent memory task which varied in difficulty. Participants repeated either 0 to 6 randomly generated digits or a single word. In all three experiments, short-term memory performance was influenced by the concurrent memory load. Prospective performance, in contrast, was not affected by the memory load even though an attempt was made to increase the difficulty of the prospective task by manipulating the specificity of the target instructions (Experiment 2) and the number of target words (Experiments 2 and 3). The results are discussed within the framework of automatic processing.

Sources: Mendeley
Keywords: memory,
Title: How Dreams And Memory May Be Related
Abstract:
I present a theory of dreams and long term memory structure that proposes that both entities are closely related. It is based on a variation of Freud's dream theory: (1) I re-label Freud's "Unconscious" the Long Term Memory Structure (LTMS), (2) I propose that dreams are ever present excitational responses to perturbations of perceptions and thought, during waking life as well as sleep, which only become conscious when the executive function of waking life ceases, and (3) I reinterpret Freuds Dream Work as describing the pre-dream Storage Transformation of perceptions and thought into the LTMS. I make one further conjecture: Memories are stored in the LTMS according to what is already in the LTMS. The observables of Freud's theory remain the same. The new theory is also consistent with recent experimental findings and suggests a partial basis for personality: the selection process of the Storage Transformation.

Sources: Mendeley
Keywords: memory,
Title: Time series aggregation, disaggregation and long memory
Abstract:
We study the aggregation/disaggregation problem of random parameter AR(1) processes and its relation to the long memory phenomenon. We give a characterization of a subclass of aggregated processes which can be obtained from simpler, "elementary", cases. In particular cases of the mixture densities, the structure (moving average representation) of the aggregated process is investigated.

Sources: Mendeley
Keywords: long-memory,
Title: Prospective Memory and Divided Attention
Abstract:
In 3 experiments, the authors manipulated the processing demands of a concurrent task to test the hypothesis that an event-based prospective memory task satisfies a criterion of automaticity proposed by L. Hasher and R. T. Zacks (1979). As in the previous studies, a prospective memory task (pressing a key whenever a target word was presented) was embedded within a short-term memory task (remembering 7 words). In addition, participants performed a concurrent memory task which varied in difficulty. Participants repeated either 0 to 6 randomly generated digits or a single word. A total of 221 university students participated in the experiments. In all 3 experiments, short-term memory performance was influenced by the concurrent memory load. Prospective performance, in contrast, was not affected by the memory load even though an attempt was made to increase the difficulty of the prospective task by manipulating the specificity of the target instructions (Exp 2) and the number of target words (Exps 2 and 3). Results are discussed within the framework of automatic processing. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Sources: Mendeley
Keywords: memory,
Title: Techniques for Fast Shared Memory Switches
Abstract:
Shared memory is commonly used to build output queued (OQ) switches. An OQ switch is known to maximize throughput, minimize delay and can offer QoS guarantees. However it is generally believed that high capacity switches cannot be built from shared memory switches because the requirements on the memory size, memory bandwidth and memory access time increase linearly with the line rate R and the number of ports N . In this paper, we ask the following question: Is it possible to build a high- speed shared memory switch in which the individual memories (in this case, DRAMs) operate at slower than the line rate? We show that this is indeed possible i.e. a shared memory switch with a spe- cific “conflict free DRAM memory management algorithm” (CFD- MMA) can emulate a first-come-first-served OQ switch if each memory operates at a rate of approximately 3NR ⁄ k , where k is the number of DRAMs used in parallel. We also show that the switch can support qualities of service, if the memories operate at a rate of 4NR ⁄ k . To enable this, we introduce a small fixed sized co-ordination buffer of size Nk and prove that the shared memory switch can emulate a OQ switch supporting QoS within a relative delay bound of Nk time slots.

Sources: Mendeley
Keywords: memory,
Title: Varieties of long memory models
Abstract:
Long memory is defined as a series having a slowly declining correlogram or, equivalently, an infinite spectrum at zero frequency. Fractional integrated processes have such properties but here it is pointed out that a number of other processes can also be long memory, including generalized fractionally integrated models arising from aggregation, time-changing coefficient models, and possibly nonlinear models. It seems that there are many classes of processes that deserve further study. The relevance of long memory is illustrated using absolute returns from a daily stock market index.

Sources: Mendeley
Keywords: long-memory,
Title: A coded shared atomic memory algorithm for message passing architectures
Abstract:
AbstractThis paper considers the communication and storage costs of emulating atomic (linearizable) multi-writer multi-reader shared memory in distributed message-passing systems. The paper contains three main contributions: (1) we present an atomic shared-memory emulation algorithm that we call Coded Atomic Storage (CAS). This algorithm uses erasure coding methods. In a storage system with N servers that is resilient to f server failures, we show that the communication cost of CAS is $$\frac{N}{N-2f}$$NN-2f. The storage cost of CAS is unbounded. (2) We present a modification of the CAS algorithm known as CAS with garbage collection (CASGC). The CASGC algorithm is parameterized by an integer $$\delta $$δ and has a bounded storage cost. We show that the CASGC algorithm satisfies atomicity. In every execution of CASGC where the number of server failures is no bigger than f, we show that every write operation invoked at a non-failing client terminates. We also show that in an execution of CASGC with parameter $$\delta $$δ where the number of server failures is no bigger than f,  a read operation terminates provided that the number of write operations that are concurrent with the read is no bigger than $$\delta $$δ. We explicitly characterize the storage cost of CASGC, and show that it has the same communication cost as CAS. (3) We describe an algorithm known as the Communication Cost Optimal Atomic Storage (CCOAS) algorithm that achieves a smaller communication cost than CAS and CASGC. In particular, CCOAS incurs read and write communication costs of $$\frac{N}{N-f}$$NN-f measured in terms of number of object values. We also discuss drawbacks of CCOAS as compared with CAS and CASGC.

Sources: Springer
Keywords: memory,registered,readers,
Title: Epistemological Problems of Memory
Abstract:
That most of our knowledge is in memory at any particular time is agiven. What is perhaps surprising, however, is the degree to whicheven our current conscious knowledge typically depends on memory. Forexample, you look at the sky and come to believe that the sunset isbeautiful. This is a newly formed belief about an event currentlytaking place. Nevertheless, its justification is no doubt dependenton other beliefs that you hold. For example, if you didn't at leasttacitly believe that you were looking west or that it is evening andnot morning, the belief wouldn't be justified (I assume that thephenomenology of sunsets and sunrises is indistinguishable). Now I amnot, however, supposing that all knowledge of the external world isinferential. Your belief that the sky is red might well beepistemically basic. Nor am I insisting that your sunset belief ispsychologically inferential. My only claim here is that manyrelatively simple beliefs we form about the external world typicallydepend for their justification on background beliefs; and backgroundbeliefs are memory beliefs., Memory-images and imagination-images do not differ in theirintrinsic qualities, so far as we can discover. They differ by thefact that the images that constitute memories, unlike those thatconstitute imagination, are accompanied by a feeling of belief whichmay be expressed in the words “this happened.” The mereoccurrence of images, without this feeling of belief constitutesimagination; it is the element of belief that is distinctive inmemory. [Russell 1921, pages 175-176], According to vulgar apprehension, memory is an immediate knowledgeof something past. Our author [i.e., Hume] does not admit that thereis any such knowledge in the human mind. He maintains that memory isnothing but a present idea or impression. But, in defining what hetakes memory to be, he takes for granted that kind of memory which herejects. For can we find by experience, that an impression, after itsfirst appearance to the mind, makes a second, and a third, withdifferent degrees of strength and vivacity, if we have not so distincta remembrance of its first appearance, as enables us to know it, uponits second and third, notwithstanding that, in the interval, it hasundergone a very considerable change. , The object of memory…must be something that ispast…What now is, cannot be an object of memory; neither canthat which is past and gone be an object of perception or ofconsciousness.

Sources: Mendeley
Keywords: memory,
Title: The role of alpha oscillations in deriving and maintaining spatial relations in working memory
Abstract:
AbstractPrevious research has demonstrated distinct neural correlates for maintenance of abstract, relational versus concrete, sensory information in working memory (WM). Storage of spatial relations in WM results in suppression of posterior sensory regions, which suggests that sensory information is task-irrelevant when relational representations are maintained in WM. However, the neural mechanisms by which abstract representations are derived from sensory information remain unclear. Here, using electroencephalography, we investigated the role of alpha oscillations in deriving spatial relations from a sensory stimulus and maintaining them in WM. Participants encoded two locations into WM, then after an initial maintenance period, a cue indicated whether to convert the spatial information to another sensory representation or to a relational representation. Results revealed that alpha power increased over posterior electrodes when sensory information was converted to a relational representation, but not when the information was converted to another sensory representation. Further, alpha phase synchrony between posterior and frontal regions increased for relational compared to sensory trials during the maintenance period. These results demonstrate that maintaining spatial relations and locations in WM rely on distinct neural oscillatory patterns.

Sources: Springer
Keywords: memory controller,synchrony,
Title: Occasional structural breaks and long memory
Abstract:
This paper shows that a linear process with breaks can mimic autocorrelations and other properties of I(d) processes, where d can be a fraction. Simulation results show that S&P 500 absolute stock returns are more likely to show the "long memory" property because of the presence of breaks in the series rather than an 1(d) process.

Sources: Mendeley
Keywords: long-memory,
Title: Dissociation of Cross-Sectional Trajectories for Verbal and Visuo-Spatial Working Memory Development in Rubinstein-Taybi Syndrome
Abstract:
AbstractWorking memory (WM) impairments might amplify behavioural difference in genetic syndromes. Murine models of Rubinstein–Taybi syndrome (RTS) evidence memory impairments but there is limited research on memory in RTS. Individuals with RTS and typically developing children completed WM tasks, with participants with RTS completing an IQ assessment and parents/carers completing the Vineland Adaptive Behavior Scales. A cross-sectional trajectory analysis was conducted. There were significant WM span deficits in RTS relative to mental age. Verbal WM span was positively associated with mental age; however, this was not observed for visuo-spatial span. There is a dissociation between WM domains in RTS. Individuals may have difficulties with tasks relying on WM span, above difficulties predicted by overall ability.

Sources: Springer
Keywords: short- and long-term memory.,short stature,
Title: Long Memory and Periodicity in Intraday Volatility
Abstract:
Intraday return volatility is characterized by the contemporaneous presence of periodicity and long memory. This article proposes two new parameterizations of the intraday volatility process that account for both features: the Fractionally Integrated Periodic EGARCH and the Seasonal Fractional Integrated Periodic EGARCH. The analysis of hourly E-mini S&P 500 futures returns shows that the volatility is characterized by a statistically significant long-range dependence coupled with a periodic leverage effect, with negative return shocks having a larger effect on volatility during the US trading period. Long memory estimates obtained with nonperiodic long memory models are greater than those obtained with FI-PEGARCH and SFI-PEGARCH models. A simulation experiment shows that the long memory component can be strongly biased when periodic patterns are not properly modelled at the intraday level. An out-of-sample forecasting comparison with alternative models shows that a constrained version of the FI-PEGARCH provides superior forecasts.

Sources: Mendeley
Keywords: long-memory,
Title: Intermittency, long-memory and financial returns
Abstract:
There is now a vast literature supporting the empirical stylized fact that the volatility of financial returns, as measured either by the absolute values or the squares of the returns series, exhibits long-memory and has correlations which remain positive for long lags and decay slowly to zero, and an associated stylized fact that the marginal distribution of the returns has heavy tails. There is also evidence to suggest that the returns display 'intermittency', often called 'volatility clustering', and the relatively benign periods of market activity are often interrupted by the occurrence of violent market movements. Reference may be made to Greene and Fielitz (1977), Akgirav and Booth (1988), Ding, Granger and Engle (1993), Kokoszka and Taqqu (1996), Podobnik et al. (2000), Mittnik and Rachev (2000), Kirman and Teyssiere (2002), Cont (2001), among others, and which are just a few among hundreds of publications in this area. At the same time, it is also recognised that the standard ARCH and GARCH models, introduced originally to describe the dependence structure of the volatility, exhibit short range dependence and thus do not capture the long-memory property of the returns, though they do imply volatility clustering and a heavy-tailed marginal distribution. Consequently, several different modifications of the basic ARCH specification have been introduced so as to incorporate the slow decay of correlations, see Baillie et al. (1996), for a review. Many of these modifications are, however, rather ad-hoc and a mathematical theory behind some is not fully developed as yet and indeed a few appear in fact not to exhibit long memory, at least asymptotically, see Giraitis, Kokoszka and Leipus (2000). In this chapter, we consider a new and an entirely different approach to modelling phenomena exhibiting long-memory, intermittency and heavy-tailed marginal distributions, namely by chaotic intermittency maps. This class of maps has witnessed much development in recent years and it marks an important emerging branch of the subject area of Dynamical Systems Theory. It should also be stressed that the idea of using deterministic maps as a candidate class of non-linear, non-stochastic models for Economic time series has an established pedigree by now and their use has previously been considered by several different authors; see, for example, Brock and Hommes (1997). For the purpose of the present discussion, three principal properties of these maps are relevant and which qualify them as a plausible class of models for financial returns. First, unlike some of the standard chaotic maps, for example, the Logistic, Tent and Bernoulli shift maps, the intermittency maps display long memory and have correlations decaying at a sub-exponential rate, meaning at a polynomial rate or even slower. Secondly, the invariant density of these maps can display 'Pareto' tails and thus go down to zero at a polynomial rate. Thirdly, as their name implies, these maps display intermittency and generate time series, called the orbit of the map, which display intermittent chaos, meaning the orbit of the map alternates between laminar and chaotic regions. A brief outline of the main theoretical properties of these maps is given in Section 2; for a more detailed discussion, reference may also be made to Bhansali, Holland and Kokoszka (2004). A further motivation for considering the use of intermittency maps for modelling financial data comes from the work of Mondragon (1999), who has successfully applied a sub-class of intermittency maps for modelling the internet traffic, which is a related yet different example of phenomena exhibiting long-memory and heavy-tailed marginal distributions, see, for example, Park and Willinger (2000). The generic characteristic features of intermittency maps described above are, however, asymptotic and apply, for example, as the lag, u, of the correlation function tends to infinity. Moreover, the bounds on the correlations have been developed for some Holder continuous function of the map time series, wt, say, and it is as yet not known precisely for which functions this bound would actually hold in practice. In Section 3, therefore, we present results of a simulation study aimed at investigating the empirical behaviour of the estimated correlations for three different categories of intermittency maps, namely the Polynomial, Logarithmic and Cusp maps, and for a range of different parameter values defining these maps. In addition, we examine the behaviour of the estimated invariant density for these three categories of maps and also that of the partial correlations and the associated 'linear Gaussian' statistics but when these are computed from a simulated realization of the map. The invariant distribution of the Polynomial and Logarithmic intermittency maps is concentrated on a compact interval, [0, 1]. On the other hand, however, the absolute returns on financial time series could in principle take values over the entire non-negative real line, ℝ+. In Section 4, we accordingly consider transformations, h(wt), which have distributions defined over [0,∞) and investigate empirically the correlation structure and related properties of the transformed series by a simulation study. Currently, there are very few theoretical results on the modelling of absolute returns as they are difficult to treat analytically, see, however, Granger and Ding (1996). The paper concludes in Section 5, where we examine the modelling potential of the intermittency maps for absolute returns and present concluding remarks for direction of future research. © Springer Berlin Heidelberg 2007.

Sources: Mendeley
Keywords: long-memory,