Anomalous volatility scaling in high frequency financial data

NASA Astrophysics Data System (ADS)

Nava, Noemi; Di Matteo, T.; Aste, Tomaso

2016-04-01

Volatility of intra-day stock market indices computed at various time horizons exhibits a scaling behaviour that differs from what would be expected from fractional Brownian motion (fBm). We investigate this anomalous scaling by using empirical mode decomposition (EMD), a method which separates time series into a set of cyclical components at different time-scales. By applying the EMD to fBm, we retrieve a scaling law that relates the variance of the components to a power law of the oscillating period. In contrast, when analysing 22 different stock market indices, we observe deviations from the fBm and Brownian motion scaling behaviour. We discuss and quantify these deviations, associating them to the characteristics of financial markets, with larger deviations corresponding to less developed markets.

Time to dry 2-, 30, and 40inch S4S southern pine at 240°F, as related to board width

Treesearch

Peter Koch

1973-01-01

With 80°F wet-bulb depression and air cross-circulated at 1,000 fbm, southern pine in 2-, 3-, and 4-inch thicknesses attained 10 percent moisture content in 22.4, 35.6, and 45.3 hours. In 3- and 4-inch thicknesses, 4-inch-wide lumber required less time to dry than that 8 or 12 inches wide. Surface checks were absent or moderate in all thicknesses and widths. End-...

Structural and temporal requirements of Wnt/PCP protein Vangl2 function for convergence and extension movements and facial branchiomotor neuron migration in zebrafish.

PubMed

Pan, Xiufang; Sittaramane, Vinoth; Gurung, Suman; Chandrasekhar, Anand

2014-02-01

Van gogh-like 2 (Vangl2), a core component of the Wnt/planar cell polarity (PCP) signaling pathway, is a four-pass transmembrane protein with N-terminal and C-terminal domains located in the cytosol, and is structurally conserved from flies to mammals. In vertebrates, Vangl2 plays an essential role in convergence and extension (CE) movements during gastrulation and in facial branchiomotor (FBM) neuron migration in the hindbrain. However, the roles of specific Vangl2 domains, of membrane association, and of specific extracellular and intracellular motifs have not been examined, especially in the context of FBM neuron migration. Through heat shock-inducible expression of various Vangl2 transgenes, we found that membrane associated functions of the N-terminal and C-terminal domains of Vangl2 are involved in regulating FBM neuron migration. Importantly, through temperature shift experiments, we found that the critical period for Vangl2 function coincides with the initial stages of FBM neuron migration out of rhombomere 4. Intriguingly, we have also uncovered a putative nuclear localization motif in the C-terminal domain that may play a role in regulating CE movements. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Statistical physics approaches to financial fluctuations

NASA Astrophysics Data System (ADS)

Wang, Fengzhong

2009-12-01

Complex systems attract many researchers from various scientific fields. Financial markets are one of these widely studied complex systems. Statistical physics, which was originally developed to study large systems, provides novel ideas and powerful methods to analyze financial markets. The study of financial fluctuations characterizes market behavior, and helps to better understand the underlying market mechanism. Our study focuses on volatility, a fundamental quantity to characterize financial fluctuations. We examine equity data of the entire U.S. stock market during 2001 and 2002. To analyze the volatility time series, we develop a new approach, called return interval analysis, which examines the time intervals between two successive volatilities exceeding a given value threshold. We find that the return interval distribution displays scaling over a wide range of thresholds. This scaling is valid for a range of time windows, from one minute up to one day. Moreover, our results are similar for commodities, interest rates, currencies, and for stocks of different countries. Further analysis shows some systematic deviations from a scaling law, which we can attribute to nonlinear correlations in the volatility time series. We also find a memory effect in return intervals for different time scales, which is related to the long-term correlations in the volatility. To further characterize the mechanism of price movement, we simulate the volatility time series using two different models, fractionally integrated generalized autoregressive conditional heteroscedasticity (FIGARCH) and fractional Brownian motion (fBm), and test these models with the return interval analysis. We find that both models can mimic time memory but only fBm shows scaling in the return interval distribution. In addition, we examine the volatility of daily opening to closing and of closing to opening. We find that each volatility distribution has a power law tail. Using the detrended fluctuation analysis (DFA) method, we show long-term auto-correlations in these volatility time series. We also analyze return, the actual price changes of stocks, and find that the returns over the two sessions are often anti-correlated.

Depressive symptoms, body composition and bone mass in young adults: a prospective cohort study.

PubMed

Zhu, K; Allen, K; Mountain, J; Lye, S; Pennell, C; Walsh, J P

2017-04-01

An association between depression and obesity is well recognised, but longitudinal studies of depressive symptoms in adolescents as a predictor of body composition are lacking. We examined depressive symptoms at age 14, 17 and 20 years as predictors of lean, fat and bone mass at age 20 years in a birth cohort. In 1161 participants (569 females) in the Western Australia Pregnancy Cohort (Raine) Study, depressive symptoms were assessed using the Beck Depression Inventory for Youth at age 14 and 17 years, and the Depression, Anxiety and Stress Scale 21 at age 20 years. Participants were further classified into two trajectories using latent class analysis: no/transient and persistent/recurrent depression. At age 20 years, lean body mass (LBM), fat body mass (FBM) and total body bone mass were measured by dual-energy X-ray absorptiometry. In females, accounting for age and lifestyle factors, depression scores at age 14 and 20 years were positively associated with body weight, body mass index (BMI), FBM and % FBM (r=0.110-0.184, P<0.05) but negatively correlated with % LBM (r=-0.120, P<0.05) at age 20 years. Females in the persistent/recurrent depression trajectory (n=99) had significantly higher body weight (+5.1 kg), BMI (+1.8 kg m -2 ), FBM (+3.9 kg) and % FBM (+2.2%) and significantly lower % LBM (-2.2%) at age 20 years than those with no/transient depression (n=470; all P<0.05). In males, depression scores at age 17 and 20 years were negatively associated with LBM but not weight or BMI, and depression trajectory was not a predictor of body composition at age 20 years. Depression scores and trajectories did not predict bone mass in either males or females. Depressive symptoms and persistent/recurrent depression in adolescence are predictors of greater adiposity at age 20 years in females, but not males, but do not predict bone mass in either gender.

Statistical properties of the anomalous scaling exponent estimator based on time-averaged mean-square displacement

NASA Astrophysics Data System (ADS)

Sikora, Grzegorz; Teuerle, Marek; Wyłomańska, Agnieszka; Grebenkov, Denis

2017-08-01

The most common way of estimating the anomalous scaling exponent from single-particle trajectories consists of a linear fit of the dependence of the time-averaged mean-square displacement on the lag time at the log-log scale. We investigate the statistical properties of this estimator in the case of fractional Brownian motion (FBM). We determine the mean value, the variance, and the distribution of the estimator. Our theoretical results are confirmed by Monte Carlo simulations. In the limit of long trajectories, the estimator is shown to be asymptotically unbiased, consistent, and with vanishing variance. These properties ensure an accurate estimation of the scaling exponent even from a single (long enough) trajectory. As a consequence, we prove that the usual way to estimate the diffusion exponent of FBM is correct from the statistical point of view. Moreover, the knowledge of the estimator distribution is the first step toward new statistical tests of FBM and toward a more reliable interpretation of the experimental histograms of scaling exponents in microbiology.

Feature-Based Morphometry: Discovering Group-related Anatomical Patterns

PubMed Central

Toews, Matthew; Wells, William; Collins, D. Louis; Arbel, Tal

2015-01-01

This paper presents feature-based morphometry (FBM), a new, fully data-driven technique for discovering patterns of group-related anatomical structure in volumetric imagery. In contrast to most morphometry methods which assume one-to-one correspondence between subjects, FBM explicitly aims to identify distinctive anatomical patterns that may only be present in subsets of subjects, due to disease or anatomical variability. The image is modeled as a collage of generic, localized image features that need not be present in all subjects. Scale-space theory is applied to analyze image features at the characteristic scale of underlying anatomical structures, instead of at arbitrary scales such as global or voxel-level. A probabilistic model describes features in terms of their appearance, geometry, and relationship to subject groups, and is automatically learned from a set of subject images and group labels. Features resulting from learning correspond to group-related anatomical structures that can potentially be used as image biomarkers of disease or as a basis for computer-aided diagnosis. The relationship between features and groups is quantified by the likelihood of feature occurrence within a specific group vs. the rest of the population, and feature significance is quantified in terms of the false discovery rate. Experiments validate FBM clinically in the analysis of normal (NC) and Alzheimer's (AD) brain images using the freely available OASIS database. FBM automatically identifies known structural differences between NC and AD subjects in a fully data-driven fashion, and an equal error classification rate of 0.80 is achieved for subjects aged 60-80 years exhibiting mild AD (CDR=1). PMID:19853047

Predictions for the top-quark forward-backward asymmetry at high invariant pair mass using the principle of maximum conformality

DOE PAGES

Wang, Sheng -Quan; Wu, Xing -Gang; Si, Zong -Guo; ...

2016-01-07

In this study, the D0 collaboration at FermiLab has recently measured the top-quark pair forward-backward asymmetry inmore » $$\\bar{p}p$$ → $$t\\bar{t}$$X reactions as a function of the $$t\\bar{t}$$ invariant mass M $$t\\bar{t}$$. The D0 result for A FB(M $$t\\bar{t}$$ > 650 GeV) is smaller than A FB(M $$t\\bar{t}$$) obtained for small values of M $$t\\bar{t}$$, which may indicate an “increasing-decreasing” behavior for A FB(M $$t\\bar{t}$$ > M cut). This behavior is not explained using conventional renormalization scale setting, or even by a next-to-next-to-leading order (N 2LO) QCD calculation—one predicts a monotonically increasing behavior. In the conventional scale-setting method, one simply guesses a single renormalization scale μr for the argument of the QCD running coupling and then varies it over an arbitrary range. However, the conventional method has inherent difficulties.« less

Change in lean body mass is a major determinant of change in areal bone mineral density of the proximal femur: a 12-year observational study.

PubMed

Liu-Ambrose, T; Kravetsky, L; Bailey, D; Sherar, L; Mundt, C; Baxter-Jones, A; Khan, K M; McKay, H A

2006-09-01

Our objective was to assess the contribution of lean body mass (LBM) and fat body mass (FBM) to areal bone mineral density (aBMD) in women during the years surrounding menopause. We used a 12-year observational design. Participants included 75 Caucasian women who were premenopausal, 53 of whom were available for follow-up. There were two measurement periods: baseline and 12-year follow-up. At both measurement periods, bone mineral content and aBMD of the proximal femur, posterior-anterior lumbar spine, and total body was assessed using dual-energy X-ray absorptiometry (DXA). LBM and FBM were derived from the total-body scans. General health, including current menopausal status, hormone replace therapy use, medication use, and physical activity, was assessed by questionnaires. At the end of the study, 44% of the women were postmenopausal. After controlling for baseline aBMD, current menopausal status, and current hormone replacement therapy, we found that change in LBM was independently associated with change in aBMD of the proximal femur (P = 0.001). The cross-sectional analyses also indicated that LBM was a significant determinant of aBMD of all three DXA-scanned sites at both baseline and follow-up. These novel longitudinal data highlight the important contribution of LBM to the maintenance of proximal femur bone mass at a key time in women's life span, the years surrounding menopause.

Using low-risk factors to generate non-integrated human induced pluripotent stem cells from urine-derived cells.

PubMed

Wang, Linli; Chen, Yuehua; Guan, Chunyan; Zhao, Zhiju; Li, Qiang; Yang, Jianguo; Mo, Jian; Wang, Bin; Wu, Wei; Yang, Xiaohui; Song, Libing; Li, Jun

2017-11-02

Because the lack of an induced pluripotent stem cell (iPSC) induction system with optimal safety and efficiency limits the application of these cells, development of such a system is important. To create such an induction system, we screened a variety of reprogrammed plasmid combinations and multiple compounds and then verified the system's feasibility using urine cells from different individuals. We also compared large-scale iPSC chromosomal variations and expression of genes associated with genomic stability between this system and the traditional episomal system using karyotype and quantitative reverse transcription polymerase chain reaction analyses. We developed a high-efficiency episomal system, the 6F/BM1-4C system, lacking tumorigenic factors for human urine-derived cell (hUC) reprogramming. This system includes six low-risk factors (6F), Oct4, Glis1, Klf4, Sox2, L-Myc, and the miR-302 cluster. Transfected hUCs were treated with four compounds (4C), inhibitor of lysine-demethylase1, methyl ethyl ketone, glycogen synthase kinase 3 beta, and histone deacetylase, within a short time period. Comparative analysis revealed significantly decreased chromosomal variation in iPSCs and significantly increased Sirt1 expression compared with iPSCs induced using the traditional episomal system. The 6F/BM1-4C system effectively induces reprogramming of urine cells in samples obtained from different individuals. iPSCs induced using the 6F/BM1-4C system are more stable at the cytogenetic level and have potential value for clinical application.

Ensemble Solute Transport in 2-D Operator-Stable Random Fields

NASA Astrophysics Data System (ADS)

Monnig, N. D.; Benson, D. A.

2006-12-01

The heterogeneous velocity field that exists at many scales in an aquifer will typically cause a dissolved solute plume to grow at a rate faster than Fick's Law predicts. Some statistical model must be adopted to account for the aquifer structure that engenders the velocity heterogeneity. A fractional Brownian motion (fBm) model has been shown to create the long-range correlation that can produce continually faster-than-Fickian plume growth. Previous fBm models have assumed isotropic scaling (defined here by a scalar Hurst coefficient). Motivated by field measurements of aquifer hydraulic conductivity, recent techniques were developed to construct random fields with anisotropic scaling with a self-similarity parameter that is defined by a matrix. The growth of ensemble plumes is analyzed for transport through 2-D "operator- stable" fBm hydraulic conductivity (K) fields. Both the longitudinal and transverse Hurst coefficients are important to both plume growth rates and the timing and duration of breakthrough. Smaller Hurst coefficients in the transverse direction lead to more "continuity" or stratification in the direction of transport. The result is continually faster-than-Fickian growth rates, highly non-Gaussian ensemble plumes, and a longer tail early in the breakthrough curve. Contrary to some analytic stochastic theories for monofractal K fields, the plume growth rate never exceeds Mercado's [1967] purely stratified aquifer growth rate of plume apparent dispersivity proportional to mean distance. Apparent super-Mercado growth must be the result of other factors, such as larger plumes corresponding to either a larger initial plume size or greater variance of the ln(K) field.

Interlaboratory variability in the quantification of new generation antiepileptic drugs based on external quality assessment data.

PubMed

Williams, John; Bialer, Meir; Johannessen, Svein I; Krämer, Günther; Levy, René; Mattson, Richard H; Perucca, Emilio; Patsalos, Philip N; Wilson, John F

2003-01-01

To assess interlaboratory variability in the determination of serum levels of new antiepileptic drugs (AEDs). Lyophilised serum samples containing clinically relevant concentrations of felbamate (FBM), gabapentin (GBP), lamotrigine (LTG), the monohydroxy derivative of oxcarbazepine (OCBZ; MHD), tiagabine (TGB), topiramate (TPM), and vigabatrin (VGB) were distributed monthly among 70 laboratories participating in the international Heathcontrol External Quality Assessment Scheme (EQAS). Assay results returned over a 15-month period were evaluated for precision and accuracy. The most frequently measured compound was LTG (65), followed by MHD (39), GBP (19), TPM (18), VGB (15), FBM (16), and TGB (8). High-performance liquid chromatography was the most commonly used assay technique for all drugs except for TPM, for which two thirds of laboratories used a commercial immunoassay. For all assay methods combined, precision was <11% for MHD, FBM, TPM, and LTG, close to 15% for GBP and VGB, and as high as 54% for TGB (p < 0.001). Mean accuracy values were <10% for all drugs other than TGB, for which measured values were on average 13.9% higher than spiked values, with a high variability around the mean (45%). No differences in precision and accuracy were found between methods, except for TPM, for which gas chromatography showed poorer accuracy compared with immunoassay and gas chromatography-mass spectrometry. With the notable exception of TGB, interlaboratory variability in the determination of new AEDs was comparable to that reported with older-generation agents. Poor assay performance is related more to individual operators than to the intrinsic characteristics of the method applied. Participation in an EQAS scheme is recommended to ensure adequate control of assay variability in therapeutic drug monitoring.

On the relationship between the Hurst exponent, the ratio of the mean square successive difference to the variance, and the number of turning points

NASA Astrophysics Data System (ADS)

Tarnopolski, Mariusz

2016-11-01

The long range dependence of the fractional Brownian motion (fBm), fractional Gaussian noise (fGn), and differentiated fGn (DfGn) is described by the Hurst exponent H. Considering the realizations of these three processes as time series, they might be described by their statistical features, such as half of the ratio of the mean square successive difference to the variance, A, and the number of turning points, T. This paper investigates the relationships between A and H, and between T and H. It is found numerically that the formulae A(H) = aebH in case of fBm, and A(H) = a + bHc for fGn and DfGn, describe well the A(H) relationship. When T(H) is considered, no simple formula is found, and it is empirically found that among polynomials, the fourth and second order description applies best. The most relevant finding is that when plotted in the space of (A , T) , the three process types form separate branches. Hence, it is examined whether A and T may serve as Hurst exponent indicators. Some real world data (stock market indices, sunspot numbers, chaotic time series) are analyzed for this purpose, and it is found that the H's estimated using the H(A) relations (expressed as inverted A(H) functions) are consistent with the H's extracted with the well known wavelet approach. This allows to efficiently estimate the Hurst exponent based on fast and easy to compute A and T, given that the process type: fBm, fGn or DfGn, is correctly classified beforehand. Finally, it is suggested that the A(H) relation for fGn and DfGn might be an exact (shifted) 3 / 2 power-law.

Dynamic variability of the heading-flowering stages of single rice in China based on field observations and NDVI estimations.

PubMed

Zhang, Zhao; Song, Xiao; Chen, Yi; Wang, Pin; Wei, Xing; Tao, Fulu

2015-05-01

Although many studies have indicated the consistent impact of warming on the natural ecosystem (e.g., an early flowering and prolonged growing period), our knowledge of the impacts on agricultural systems is still poorly understood. In this study, spatiotemporal variability of the heading-flowering stages of single rice was detected and compared at three different scales using field-based methods (FBMs) and satellite-based methods (SBMs). The heading-flowering stages from 2000 to 2009 with a spatial resolution of 1 km were extracted from the SPOT/VGT NDVI time series data using the Savizky-Golay filtering method in the areas in China dominated by single rice of Northeast China (NE), the middle-lower Yangtze River Valley (YZ), the Sichuan Basin (SC), and the Yunnan-Guizhou Plateau (YG). We found that approximately 52.6 and 76.3 % of the estimated heading-flowering stages by a SBM were within ±5 and ±10 days estimation error (a root mean square error (RMSE) of 8.76 days) when compared with those determined by a FBM. Both the FBM data and the SBM data had indicated a similar spatial pattern, with the earliest annual average heading-flowering stages in SC, followed by YG, NE, and YZ, which were inconsistent with the patterns reported in natural ecosystems. Moreover, diverse temporal trends were also detected in the four regions due to different climate conditions and agronomic factors such as cultivar shifts. Nevertheless, there were no significant differences (p > 0.05) between the FBM and the SBM in both the regional average value of the phenological stages and the trends, implying the consistency and rationality of the SBM at three scales.

COMBINED SEWER OVERFLOW - BALANCING FLOW FOR CSO ABATEMENT

EPA Science Inventory

Instead of using conventional storage units, e.g., reinforced concrete tanks and lined earthen basins, which are relatively expensive and require a lot of urban land area, the in-receiving water flow balance method (FBM) facilities use the receiving water body itself for storage ...

Statistical model with two order parameters for ductile and soft fiber bundles in nanoscience and biomaterials.

PubMed

Rinaldi, Antonio

2011-04-01

Traditional fiber bundles models (FBMs) have been an effective tool to understand brittle heterogeneous systems. However, fiber bundles in modern nano- and bioapplications demand a new generation of FBM capturing more complex deformation processes in addition to damage. In the context of loose bundle systems and with reference to time-independent plasticity and soft biomaterials, we formulate a generalized statistical model for ductile fracture and nonlinear elastic problems capable of handling more simultaneous deformation mechanisms by means of two order parameters (as opposed to one). As the first rational FBM for coupled damage problems, it may be the cornerstone for advanced statistical models of heterogeneous systems in nanoscience and materials design, especially to explore hierarchical and bio-inspired concepts in the arena of nanobiotechnology. Applicative examples are provided for illustrative purposes at last, discussing issues in inverse analysis (i.e., nonlinear elastic polymer fiber and ductile Cu submicron bars arrays) and direct design (i.e., strength prediction).

Attitude changes during and after long submarine missions.

PubMed

Weybrew, B B; Molish, H B

1979-01-01

To assess the kind and degree of attitude changes occurring during a 2-month submerged mission, two enlisted crews of one fleet ballistic missile submarine (FBM) (n = 101 each) were administered the Submarine Attitude Questionnaire before and after two 55-day submerged missions interspersed with a rehabilitation period of the same duration. Results showed that time-in-service and pay grade bore a U-shaped relationship to positive attitudes toward the service. During submergence, most attitudes became negative and then reversed polarity during rehabilitation. However, there were no cumulative effects upon attitudes during successive missions. Attitudes pertaining to the realities of the mission (for example, boredom, hazardous aspects) became more negative but recovered faster. On the other hand, attitude changes related to long-range expectancies in terms of goal achievement of the crew members were less likely to recover. Several possible explanations for these attitude changes are discussed in the context of the mission of the FBM submarine. Suggestions for preventing or alleviating untoward attitude changes during long submarine missions are also presented.

The length of time necessary to break even after converting to digital mammography.

PubMed

Hiatt, M D; Carr, J J; Manning, R L

2000-01-01

The cost differences between film-based mammography (FBM) and digital mammography (DM) were estimated after discussions with hospital personnel and industry representatives. Human resource costs were not included. The fixed cost of FBM per machine was estimated to be $50,000 and the variable cost $4.60 per examination. The fixed cost of DM per machine was estimated to be $102,000 and the variable cost $0.10 per examination. The total number of examinations required to break even was therefore 11,556. At a rate of 15 examinations per machine per day and with 251 working days per year, it would take 3.1 years to break even. In the first year after the break-even point had been attained, $16,943 would be saved for every 3765 examinations performed. Extrapolating to the USA as a whole, in which 23 million mammographic examinations are performed each year, suggests that the annual savings from going filmless would be more than $103 million.

IN VIVO ASSESSMENT OF THE SOLUBILITY OF TOOTH ENAMEL DURING AN FBM PATROL

DTIC Science & Technology

The solubility of dental enamel is a prime factor in the dental decay process. Conditions which may influence the enamel solubility and the degree of...normal variation of this factor are therefore of interest to the Navy Dental Corps. Enamel solubility was determined in a group of volunteers from

Chromosomal locus tracking with proper accounting of static and dynamic errors

PubMed Central

Backlund, Mikael P.; Joyner, Ryan; Moerner, W. E.

2015-01-01

The mean-squared displacement (MSD) and velocity autocorrelation (VAC) of tracked single particles or molecules are ubiquitous metrics for extracting parameters that describe the object’s motion, but they are both corrupted by experimental errors that hinder the quantitative extraction of underlying parameters. For the simple case of pure Brownian motion, the effects of localization error due to photon statistics (“static error”) and motion blur due to finite exposure time (“dynamic error”) on the MSD and VAC are already routinely treated. However, particles moving through complex environments such as cells, nuclei, or polymers often exhibit anomalous diffusion, for which the effects of these errors are less often sufficiently treated. We present data from tracked chromosomal loci in yeast that demonstrate the necessity of properly accounting for both static and dynamic error in the context of an anomalous diffusion that is consistent with a fractional Brownian motion (FBM). We compare these data to analytical forms of the expected values of the MSD and VAC for a general FBM in the presence of these errors. PMID:26172745

The pricing of credit default swaps under a generalized mixed fractional Brownian motion

NASA Astrophysics Data System (ADS)

He, Xinjiang; Chen, Wenting

2014-06-01

In this paper, we consider the pricing of the CDS (credit default swap) under a GMFBM (generalized mixed fractional Brownian motion) model. As the name suggests, the GMFBM model is indeed a generalization of all the FBM (fractional Brownian motion) models used in the literature, and is proved to be able to effectively capture the long-range dependence of the stock returns. To develop the pricing mechanics of the CDS, we firstly derive a sufficient condition for the market modeled under the GMFBM to be arbitrage free. Then under the risk-neutral assumption, the CDS is fairly priced by investigating the two legs of the cash flow involved. The price we obtained involves elementary functions only, and can be easily implemented for practical purpose. Finally, based on numerical experiments, we analyze quantitatively the impacts of different parameters on the prices of the CDS. Interestingly, in comparison with all the other FBM models documented in the literature, the results produced from the GMFBM model are in a better agreement with those calculated from the classical Black-Scholes model.

A New Method for Non-destructive Measurement of Biomass, Growth Rates, Vertical Biomass Distribution and Dry Matter Content Based on Digital Image Analysis

PubMed Central

Tackenberg, Oliver

2007-01-01

Background and Aims Biomass is an important trait in functional ecology and growth analysis. The typical methods for measuring biomass are destructive. Thus, they do not allow the development of individual plants to be followed and they require many individuals to be cultivated for repeated measurements. Non-destructive methods do not have these limitations. Here, a non-destructive method based on digital image analysis is presented, addressing not only above-ground fresh biomass (FBM) and oven-dried biomass (DBM), but also vertical biomass distribution as well as dry matter content (DMC) and growth rates. Methods Scaled digital images of the plants silhouettes were taken for 582 individuals of 27 grass species (Poaceae). Above-ground biomass and DMC were measured using destructive methods. With image analysis software Zeiss KS 300, the projected area and the proportion of greenish pixels were calculated, and generalized linear models (GLMs) were developed with destructively measured parameters as dependent variables and parameters derived from image analysis as independent variables. A bootstrap analysis was performed to assess the number of individuals required for re-calibration of the models. Key Results The results of the developed models showed no systematic errors compared with traditionally measured values and explained most of their variance (R2 ≥ 0·85 for all models). The presented models can be directly applied to herbaceous grasses without further calibration. Applying the models to other growth forms might require a re-calibration which can be based on only 10–20 individuals for FBM or DMC and on 40–50 individuals for DBM. Conclusions The methods presented are time and cost effective compared with traditional methods, especially if development or growth rates are to be measured repeatedly. Hence, they offer an alternative way of determining biomass, especially as they are non-destructive and address not only FBM and DBM, but also vertical biomass distribution and DMC. PMID:17353204

Impact of malnutrition on gastrointestinal disorders and gross motor abilities in children with cerebral palsy.

PubMed

Campanozzi, Angelo; Capano, Guglielmo; Miele, Erasmo; Romano, Alfonso; Scuccimarra, Goffredo; Del Giudice, Ennio; Strisciuglio, Caterina; Militerni, Roberto; Staiano, Annamaria

2007-01-01

Children with cerebral palsy (CP) often demonstrate abnormal feeding behaviours, leading to reduced food consumption and malnutrition. Moreover, most of them present with gastrointestinal disorders, such as gastroesophageal reflux disease (GERD) and/or chronic constipation (CC), and poor motor function rehabilitation. The aim of our study was to assess the possible relationship between malnutrition and gastrointestinal problems and to evaluate the role of nutrition on their gross motor abilities in a population of children with CP and mental retardation. Twenty-one consecutive children (10 boys; mean age: 5.8+/-4.7 years; range: 1-14 years) with CP and severe mental retardation. Nutritional assessment included the measurement of body mass index (BMI=W/H2), fat body mass (FBM) and fat free mass (FFM). Children with symptoms suggesting GERD underwent prolonged 24h intraesophageal pH monitoring and/or upper GI endoscopy with biopsies before and after a 6 months of pharmaceutical (omeprazole) and nutritional (20% increment of daily caloric intake) treatments. The motor function was evaluated by "The Gross Motor Function Measure" (GMFM) before and after the 6 months on nutritional rehabilitation. BMI for age was or=25 degrees percentile, five of nine (55.5%) patients had persistent GERD when they were taken off the medication. Malnutrition and gastrointestinal disorders are very common in children with cerebral palsy. Improved nutritional status, particularly fat free mass gain, appears to have an impact on motor function in children with CP.

Reorganizing Freshman Business Mathematics II: Authentic Assessment in Mathematics through Professional Memos

ERIC Educational Resources Information Center

Green, Kris; Emerson, Allen

2008-01-01

The first part of this two-part paper [see EJ787497] described the development of a new freshman business mathematics (FBM) course at our college. In this paper, we discuss our assessment tool, the business memo, as a venue for students to apply mathematical skills, via mathematical modelling, to realistic business problems. These memos have…

Reorganizing Freshman Business Mathematics I: Background and Philosophy

ERIC Educational Resources Information Center

Green, Kris; Emerson, Allen

2008-01-01

This article is the first of the two-part discussion of the development of a new Freshman Business Mathematics (FBM) course at our college. Part I of the article describes the background and history behind the course, and provides a theoretical framework for the design of the course. This design involves students in learning and applying…

Wood used in pallets manufactured in the United States, 1982

Treesearch

D. B. McKeever; D. R. McCurdy; F. H. Kung; J. T. Ewers

This paper reports results of a cooperative study by the USDA Forest Service, Southern Illinois University at Carbondale, and Tuskegee Institute. The study was designed to provide statistically reliable information on national and regional use of wood in pallets, by species and pallet type. An estimated 17 fbm of wood was required to produce a finished pallet; the...

A Case Study on Mathematics Anxiety for Mathematics of Finance Course

ERIC Educational Resources Information Center

Abidin, Rabiatul Alawiyah Zainal; Alwi, Fatimah; Jaafar, Noor Faiza M.

2010-01-01

The DIIA (Diploma in Investment Analysis) students from the FBM (Faculty of Business Management) were required to undertake several MOF (Mathematic of Finance) courses. The passing rates for all of the MOF courses were good except for one course. There are many factors for this low passing rate phenomenon for this particular MOF course. One of the…

Concentration of floating biogenic material in convergence zones

NASA Astrophysics Data System (ADS)

Dandonneau, Yves; Menkes, Christophe; Duteil, Olaf; Gorgues, Thomas

Some organisms that live just below the sea surface (the neuston) are known more as a matter of curiosity than as critical players in biogeochemical cycles. The hypothesis of this work is that their existence implies that they receive some food from an upward flux of organic matter. The behaviour of these organisms and of the associated organic matter, hereafter mentioned as floating biogenic material (FBM) is explored using a global physical-biogeochemical coupled model, in which its generation is fixed to 1% of primary production, and decay rate is of the order of 1 month. The model shows that the distribution of FBM should depart rapidly from that of primary production, and be more sensitive to circulation patterns than to the distribution of primary production. It is trapped in convergence areas, where it reaches concentrations larger by a factor 10 than in divergences, thus enhancing and inverting the contrast between high and low primary productivity areas. Attention is called on the need to better understand the biogeochemical processes in the first meter of the ocean, as they may impact the distribution of food for fishes, as well as the conditions for air-sea exchange and for the interpretation of sea color.

Memory-induced acceleration and slowdown of barrier crossing

NASA Astrophysics Data System (ADS)

Kappler, Julian; Daldrop, Jan O.; Brünig, Florian N.; Boehle, Moritz D.; Netz, Roland R.

2018-01-01

We study the mean first-passage time τMFP for the barrier crossing of a single massive particle with non-Markovian memory by Langevin simulations in one dimension. In the Markovian limit of short memory time τΓ, the expected Kramers turnover between the overdamped (high-friction) and the inertial (low-friction) limits is recovered. Compared to the Markovian case, we find barrier crossing to be accelerated for intermediate memory time, while for long memory time, barrier crossing is slowed down and τMFP increases with τΓ as a power law τM F P˜τΓ2. Both effects are derived from an asymptotic propagator analysis: while barrier crossing acceleration at intermediate memory can be understood as an effective particle mass reduction, slowing down for long memory is caused by the slow kinetics of energy diffusion. A simple and globally accurate heuristic formula for τMFP in terms of all relevant time scales of the system is presented and used to establish a scaling diagram featuring the Markovian overdamped and the Markovian inertial regimes, as well as the non-Markovian intermediate memory time regime where barrier crossing is accelerated and the non-Markovian long memory time regime where barrier crossing is slowed down.

75 FR 29891 - Special Local Regulation; Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-28

...-AA08 Special Local Regulation; Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay... Lighthouse Dock, Fire Island, NY due to the annual Maggie Fischer Memorial Great South Bay Cross Bay Swim..., Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, NY, in the Federal Register (74...

Computer-Based Instruction for TRIDENT FBM Training

DTIC Science & Technology

1976-06-01

remote voice feedback to an operator. In this case it is possible to display text which represents the voice messages required during sequential ...provides two main services: (a) the preparation of missiles for sequential launching with self-guidance after launch, and (b) the coordination of...monitor- ing the status of the guidance system in each missile. FCS SWS coordina- tion consists of monitoring systems involved in sequential functions at

One bipolar transistor selector - One resistive random access memory device for cross bar memory array

NASA Astrophysics Data System (ADS)

Aluguri, R.; Kumar, D.; Simanjuntak, F. M.; Tseng, T.-Y.

2017-09-01

A bipolar transistor selector was connected in series with a resistive switching memory device to study its memory characteristics for its application in cross bar array memory. The metal oxide based p-n-p bipolar transistor selector indicated good selectivity of about 104 with high retention and long endurance showing its usefulness in cross bar RRAM devices. Zener tunneling is found to be the main conduction phenomena for obtaining high selectivity. 1BT-1R device demonstrated good memory characteristics with non-linearity of 2 orders, selectivity of about 2 orders and long retention characteristics of more than 105 sec. One bit-line pull-up scheme shows that a 650 kb cross bar array made with this 1BT1R devices works well with more than 10 % read margin proving its ability in future memory technology application.

Intrafamilial similarities and cross-generational differences in the earliest childhood memories of daughters, mothers, and grandmothers.

PubMed

Sahin-Acar, Basak; Bakir, Tugce; Kus, Elif Gizem

2017-09-01

This study aimed to examine how daughters, mothers, and grandmothers from the same families resembled each other and how these three generations differed from each other in narrating their earliest childhood memories. Fifty-nine triads from the same families filled out a memory questionnaire and were asked to narrate their earliest childhood memories. Results revealed both intrafamilial similarities and cross-generational difference on characteristics of triads' earliest childhood memories. After earliest childhood memories were coded for memory characteristics, we measured intrafamilial similarities using intra-class correlation coefficients across three generations for each memory characteristic. Results revealed that the earliest childhood memories of members of the same family were significantly similar in terms of level of detail and volume. Although similar patterns among members of the same families were observed in self-related and other-related words, the other/self ratio did not display an intrafamilial similarity. We also measured cross-generational differences and found that daughters' reported age of their earliest childhood memories was dated significantly earlier compared to their grandmothers. Results revealed predominant intrafamilial similarities among the members of the same family and cross-generational differences in terms of the age of the earliest childhood memory.

Effect of saliva contamination and artificial aging on different primer/cement systems bonded to zirconia.

PubMed

Pitta, João; Branco, Teresa C; Portugal, Jaime

2018-05-01

Saliva contamination has been shown to decrease bonding to zirconia. Adopting a less contamination-sensitive cement system may be an alternative to decontamination. The purpose of this in vitro study was to assess the ability of different primer/cement systems to promote a durable bond to zirconia after saliva contamination. Zirconia blocks (Lava Plus) (N=320) were airborne-particle abraded (50 μm Al 2 O 3 ) and divided into 32 experimental groups (n=10) according to the variables in the study: saliva contamination; primer/cement system (Panavia SA [PSA]; RelyX Unicem 2 [RU2]; Bifix SE [BSE]; Panavia F2.0 [PF2]; Scotchbond Universal + RelyX Ultimate [SBU+RXU]; Futurabond M+ + Bifix QM [FBM+BQM]; All-Bond Universal + Duo-link [ABU+DL]; Z-Prime Plus + Duo-link [ZPP+DL]; and aging period (72 hours; 30 days with 10 000 thermocycles at 5°C to 55°C). After half of the blocks had been contaminated with fresh human saliva for 10 minutes, rinsed with water, and air-dried, each primer/cement was applied. Polymerized composite resin disks were then placed over the cement, and the resin cement was light-polymerized for 20 seconds each at 2 opposite margins. After the aging time, the specimens were tested in shear (1 mm/min). The failure mode was classified as adhesive, cohesive, or mixed. Statistical analysis of the shear bond strength (SBS) data was performed with ANOVA followed by Tukey honest significant difference post hoc tests. Chi-square tests were used to analyze the failure mode data (α=.05). The mean SBS ranged between 4.2 and 34.5 MPa. Shear bond strength was influenced (P<.001) by all the factors studied (cement system, saliva contamination, aging time). SBU+RXU and FBM+BQM showed a higher mean SBS than those of the other experimental groups (P<.05) and were the only groups not affected by saliva contamination (P>.05). Failure was predominantly classified as adhesive. In general, saliva contamination and aging decreased bonding efficacy. Two systems, combining an application of a universal adhesive and a resin cement (SBU+RXU and FBM+BQM) were not affected by saliva contamination. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

The People’s Liberation Army and China in Transition

DTIC Science & Technology

2003-08-01

and long- range land-attack cruise missiles. China currently has just one FBM, the Xia, which may not be opera - ble. Its successor class, the Type...prospects for U.S.- China relations and military-to-military cooperation, and the implications of these developments for U.S. defense planning...A R T I THE PEOPLE’S LIBERATION ARMY AND CHINA IN TRANSITION edited by Stephen J. Flanagan and Michael E. Marti, with contributions from: Richard

Parallel pathways for cross-modal memory retrieval in Drosophila.

PubMed

Zhang, Xiaonan; Ren, Qingzhong; Guo, Aike

2013-05-15

Memory-retrieval processing of cross-modal sensory preconditioning is vital for understanding the plasticity underlying the interactions between modalities. As part of the sensory preconditioning paradigm, it has been hypothesized that the conditioned response to an unreinforced cue depends on the memory of the reinforced cue via a sensory link between the two cues. To test this hypothesis, we studied cross-modal memory-retrieval processing in a genetically tractable model organism, Drosophila melanogaster. By expressing the dominant temperature-sensitive shibire(ts1) (shi(ts1)) transgene, which blocks synaptic vesicle recycling of specific neural subsets with the Gal4/UAS system at the restrictive temperature, we specifically blocked visual and olfactory memory retrieval, either alone or in combination; memory acquisition remained intact for these modalities. Blocking the memory retrieval of the reinforced olfactory cues did not impair the conditioned response to the unreinforced visual cues or vice versa, in contrast to the canonical memory-retrieval processing of sensory preconditioning. In addition, these conditioned responses can be abolished by blocking the memory retrieval of the two modalities simultaneously. In sum, our results indicated that a conditioned response to an unreinforced cue in cross-modal sensory preconditioning can be recalled through parallel pathways.

Fractional Brownian motion and long term clinical trial recruitment

PubMed Central

Zhang, Qiang; Lai, Dejian

2015-01-01

Prediction of recruitment in clinical trials has been a challenging task. Many methods have been studied, including models based on Poisson process and its large sample approximation by Brownian motion (BM), however, when the independent incremental structure is violated for BM model, we could use fractional Brownian motion to model and approximate the underlying Poisson processes with random rates. In this paper, fractional Brownian motion (FBM) is considered for such conditions and compared to BM model with illustrated examples from different trials and simulations. PMID:26347306

Fractional Brownian motion and long term clinical trial recruitment.

PubMed

Zhang, Qiang; Lai, Dejian

2011-05-01

Prediction of recruitment in clinical trials has been a challenging task. Many methods have been studied, including models based on Poisson process and its large sample approximation by Brownian motion (BM), however, when the independent incremental structure is violated for BM model, we could use fractional Brownian motion to model and approximate the underlying Poisson processes with random rates. In this paper, fractional Brownian motion (FBM) is considered for such conditions and compared to BM model with illustrated examples from different trials and simulations.

Continuous tunnel kiln direct-fired with bark to dry 1.75-inch southern pine in 12 hours.

Treesearch

P. Koch; W.L. Wellford

1977-01-01

Length-sorted lumber is surfaced on one side to 1.75-inch thickness, mechanically stacked 5 feet wide and 10 feet high on 1-1/4-inch-thick sticks, and continuously transported through a zone-controlled tunnel kiln at 8 ft./hr. to yield 500,000 fbm of lumber dried to 9 percent average MC per 168-hour week. In the tunnel, the lumber is dried for 8 (possibly 10) hours at...

Continuous tunnel kiln direct-fired with bark to dry 1.75-inch southern pine in 12 hours

Treesearch

Peter Koch; Walker L. Wellford

1976-01-01

Length-sorted lumber is surfaced on one side to 1.75-inch thickness, mechanically stacked 5 feet wide and 10 feet high on 1-1/4-inch-thick sticks, and continuously transported through a zone-controlled tunnel kiln at 8 ft./hr. to yield 500,000 fbm of lumber dried to 9 percent average MC per 168-hour week. In the tunnel, the lumber is dried for 8 (possibly 10) hours of...

Cross-modal working memory binding and word recognition skills: how specific is the link?

PubMed

Wang, Shinmin; Allen, Richard J

2018-04-01

Recent research has suggested that the creation of temporary bound representations of information from different sources within working memory uniquely relates to word recognition abilities in school-age children. However, it is unclear to what extent this link is attributable specifically to the binding ability for cross-modal information. This study examined the performance of Grade 3 (8-9 years old) children on binding tasks requiring either temporary association formation of two visual items (i.e., within-modal binding) or pairs of visually presented abstract shapes and auditorily presented nonwords (i.e., cross-modal binding). Children's word recognition skills were related to performance on the cross-modal binding task but not on the within-modal binding task. Further regression models showed that cross-modal binding memory was a significant predictor of word recognition when memory for its constituent elements, general abilities, and crucially, within-modal binding memory were taken into account. These findings may suggest a specific link between the ability to bind information across modalities within working memory and word recognition skills.

33 CFR 100.124 - Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York. 100.124 Section 100.124 Navigation and Navigable... NAVIGABLE WATERS § 100.124 Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York...

Evidence for a confidence-accuracy relationship in memory for same- and cross-race faces.

PubMed

Nguyen, Thao B; Pezdek, Kathy; Wixted, John T

2017-12-01

Discrimination accuracy is usually higher for same- than for cross-race faces, a phenomenon known as the cross-race effect (CRE). According to prior research, the CRE occurs because memories for same- and cross-race faces rely on qualitatively different processes. However, according to a continuous dual-process model of recognition memory, memories that rely on qualitatively different processes do not differ in recognition accuracy when confidence is equated. Thus, although there are differences in overall same- and cross-race discrimination accuracy, confidence-specific accuracy (i.e., recognition accuracy at a particular level of confidence) may not differ. We analysed datasets from four recognition memory studies on same- and cross-race faces to test this hypothesis. Confidence ratings reliably predicted recognition accuracy when performance was above chance levels (Experiments 1, 2, and 3) but not when performance was at chance levels (Experiment 4). Furthermore, at each level of confidence, confidence-specific accuracy for same- and cross-race faces did not significantly differ when overall performance was above chance levels (Experiments 1, 2, and 3) but significantly differed when overall performance was at chance levels (Experiment 4). Thus, under certain conditions, high-confidence same-race and cross-race identifications may be equally reliable.

Neural substrate of initiation of cross-modal working memory retrieval.

PubMed

Zhang, Yangyang; Hu, Yang; Guan, Shuchen; Hong, Xiaolong; Wang, Zhaoxin; Li, Xianchun

2014-01-01

Cross-modal working memory requires integrating stimuli from different modalities and it is associated with co-activation of distributed networks in the brain. However, how brain initiates cross-modal working memory retrieval remains not clear yet. In the present study, we developed a cued matching task, in which the necessity for cross-modal/unimodal memory retrieval and its initiation time were controlled by a task cue appeared in the delay period. Using functional magnetic resonance imaging (fMRI), significantly larger brain activations were observed in the left lateral prefrontal cortex (l-LPFC), left superior parietal lobe (l-SPL), and thalamus in the cued cross-modal matching trials (CCMT) compared to those in the cued unimodal matching trials (CUMT). However, no significant differences in the brain activations prior to task cue were observed for sensory stimulation in the l-LPFC and l-SPL areas. Although thalamus displayed differential responses to the sensory stimulation between two conditions, the differential responses were not the same with responses to the task cues. These results revealed that the frontoparietal-thalamus network participated in the initiation of cross-modal working memory retrieval. Secondly, the l-SPL and thalamus showed differential activations between maintenance and working memory retrieval, which might be associated with the enhanced demand for cognitive resources.

Emotion knowledge and autobiographical memory across the preschool years: a cross-cultural longitudinal investigation.

PubMed

Wang, Qi

2008-07-01

Knowledge of emotion situations facilitates the interpretation, processing, and organization of significant personal event information and thus may be an important contributor to the development of autobiographical memory. This longitudinal study tested the hypothesis in a cross-cultural context. The participants were native Chinese children, Chinese children from first-generation Chinese immigrant families in the U.S., and European American children. Children's developing emotion knowledge and autobiographical memory were assessed three times at home, when children were 3, 3.5, and 4.5 years of age. Children's emotion knowledge uniquely predicted their autobiographical memory ability across groups and time points. Emotion knowledge further mediated culture effects on autobiographical memory. The findings provide important insight into early autobiographical memory development, and extend current theoretical understandings of the emotion-memory interplay. They further have implications for the phenomenon of infantile amnesia and cross-cultural differences in childhood recollections.

Influence of encoding instructions and response bias on cross-cultural differences in specific recognition.

PubMed

Paige, Laura E; Amado, Selen; Gutchess, Angela H

2017-10-01

Prior cross-cultural research has reported cultural variations in memory. One study revealed that Americans remembered images with more perceptual detail than East Asians (Millar et al. in Cult Brain 1(2-4):138-157, 2013). However, in a later study, this expected pattern was not replicated, possibly due to differences in encoding instructions (Paige et al. in Cortex 91:250-261, 2017). The present study sought to examine when cultural variation in memory-related decisions occur and the role of instructions. American and East Asian participants viewed images of objects while making a Purchase decision or an Approach decision and later completed a surprise recognition test. Results revealed Americans had higher hit rates for specific memory, regardless of instruction type, and a less stringent response criterion relative to East Asians. Additionally, a pattern emerged where the Approach decision enhanced hit rates for specific memory relative to the Purchase decision only when administered first; this pattern did not differ across cultures. Results suggest encoding instructions do not magnify cross-cultural differences in memory. Ultimately, cross-cultural differences in response bias, rather than memory sensitivity per se, may account for findings of cultural differences in memory specificity.

Controllability of fractional higher order stochastic integrodifferential systems with fractional Brownian motion.

PubMed

Sathiyaraj, T; Balasubramaniam, P

2017-11-30

This paper presents a new set of sufficient conditions for controllability of fractional higher order stochastic integrodifferential systems with fractional Brownian motion (fBm) in finite dimensional space using fractional calculus, fixed point technique and stochastic analysis approach. In particular, we discuss the complete controllability for nonlinear fractional stochastic integrodifferential systems under the proved result of the corresponding linear fractional system is controllable. Finally, an example is presented to illustrate the efficiency of the obtained theoretical results. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Memory is preserved in older adults taking AT1 receptor blockers.

PubMed

Ho, Jean K; Nation, Daniel A

2017-04-26

Prior work suggests that some but not all antihypertensive treatments may benefit cognition and risk for Alzheimer's disease, independent of stroke. Angiotensin II receptor blockers (ARBs) have been highlighted as one antihypertensive drug class that may confer greatest benefit. The participants comprised 1626 nondemented adults, aged 55-91 years, recruited from Alzheimer's Disease Neuroimaging Initiative sites. Three groups were compared: ARB users (HTN-ARBs), other antihypertensive drug users (HTN-Other), and normotensives. In post hoc analyses, we also examined (1) users of ARBs and angiotensin-converting enzyme inhibitors (ACEIs), (2) users of blood-brain barrier (BBB)-crossing ARBs and users of non-BBB-crossing ARBs, and (3) users of BBB-crossing ARBs and ACEIs (BBB crossers) and users of non-BBB-crossing ARBs and ACEIs (BBB noncrossers). Groups were compared regarding cognition and magnetic resonance imaging measures of brain volume and white matter hyperintensities (WMH), using analysis of covariance and multilevel models. At baseline, the HTN-Other group performed worse than normotensives on Rey Auditory Verbal Learning Test (RAVLT) Immediate Recall (p = 0.002), Delayed Recall (p < 0.001), Recognition Memory (p = 0.001), and Trails A (p < 0.001) and B (p = 0.01). ARB users performed better than the HTN-Other group on Recognition Memory (p = 0.04) and worse than normotensives on Trails A (p = 0.04). The HTN-Other group performed worse than normotensives on Logical Memory Immediate (p = 0.02) and Delayed Recall over the 3-year follow-up (p = 0.007). Over the follow-up period, those taking BBB-crossing ARBs performed better than the HTN-Other group on AVLT Delayed Recall (p = 0.04), Logical Memory Immediate (p = 0.02), and Delayed Recall (p = 0.05). They also had fewer WMH than the HTN-Other group (p = 0.008) and those taking non-BBB-crossing ARBs (p = 0.05). There were no group differences in brain volume. Users of BBB-crossing medications (ARBs or ACEIs) showed better performance on AVLT Delayed Recall over time than all other groups, including normotensives (all p < 0.01), and had less WMH volume over time than the BBB noncrossers group (p = 0.03), although they had more WMH volume than normotensives (p = 0.01). The BBB noncrossers group performed worse than normotensives on Logical Memory Delayed Recall over time (p = 0.01), but the BBB crossers group was not significantly different (p = 0.13). Hypertensive participants demonstrated worse baseline memory and executive function, as well as greater memory decline, over the 3-year follow-up than normotensives, unless they were ARB users, who showed preserved memory compared with those taking other antihypertensive drugs. Users of BBB-crossing ARBs showed superior memory performance over time compared with other antihypertensive drug users and had less WMH volume. Users of BBB-crossing medications (ARBs or ACEIs) showed better list-learning memory performance over time than all other groups, including normotensives, and had less WMH volume over time than users of non-BBB-crossing medications. These findings demonstrate that ARBs, especially those of the BBB-crossing variety, are associated with greater memory preservation and less WMH volume than other antihypertensive medications.

THE DEPENDENCE OF PRESTELLAR CORE MASS DISTRIBUTIONS ON THE STRUCTURE OF THE PARENTAL CLOUD

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

Parravano, Antonio; Sanchez, Nestor; Alfaro, Emilio J.

2012-08-01

The mass distribution of prestellar cores is obtained for clouds with arbitrary internal mass distributions using a selection criterion based on the thermal and turbulent Jeans mass and applied hierarchically from small to large scales. We have checked this methodology by comparing our results for a log-normal density probability distribution function with the theoretical core mass function (CMF) derived by Hennebelle and Chabrier, namely a power law at large scales and a log-normal cutoff at low scales, but our method can be applied to any mass distributions representing a star-forming cloud. This methodology enables us to connect the parental cloudmore » structure with the mass distribution of the cores and their spatial distribution, providing an efficient tool for investigating the physical properties of the molecular clouds that give rise to the prestellar core distributions observed. Simulated fractional Brownian motion (fBm) clouds with the Hurst exponent close to the value H = 1/3 give the best agreement with the theoretical CMF derived by Hennebelle and Chabrier and Chabrier's system initial mass function. Likewise, the spatial distribution of the cores derived from our methodology shows a surface density of companions compatible with those observed in Trapezium and Ophiucus star-forming regions. This method also allows us to analyze the properties of the mass distribution of cores for different realizations. We found that the variations in the number of cores formed in different realizations of fBm clouds (with the same Hurst exponent) are much larger than the expected root N statistical fluctuations, increasing with H.« less

Levetiracetam selectively potentiates the acute neurotoxic effects of topiramate and carbamazepine in the rotarod test in mice.

PubMed

Luszczki, Jarogniew J; Andres, Marta M; Czuczwar, Piotr; Cioczek-Czuczwar, Anna; Wojcik-Cwikla, Joanna; Ratnaraj, Neville; Patsalos, Philip N; Czuczwar, Stanislaw J

2005-12-01

The effect of levetiracetam (LEV) on the acute neurotoxic profiles of various antiepileptic drugs (carbamazepine [CBZ], phenytoin [PHT], phenobarbital [PB], valproate [VPA], lamotrigine [LTG], topiramate [TPM], oxcarbazepine [OXC], and felbamate [FBM]) was evaluated in the rotarod test, allowing the determination of median toxic doses (TD50 values) with respect to impairment of motor coordination in mice. The TD50 of LEV administered singly was 1601 mg/kg. Whilst LEV at 150 mg/kg, being its TID50 (a dose increasing the electroconvulsive threshold by 50%), was without effect with regards to motor coordination impairment associated with PHT, PB, VPA, LTG, OXC, and FBM, it significantly enhanced that associated with CBZ and TPM co-administration. Thus LEV (150 mg/kg) significantly decreased the TD50 of CBZ from 53.6 to 37.3 mg/kg (P<0.01) and that of TPM from 423 to 246 mg/kg (P<0.01). In addition LEV (75 mg/kg) significantly decreased the TD50 of TPM from 423 to 278 (P<0.01). That concurrent measurement of total brain LEV, CBZ, and TPM concentrations showed that concentrations were not significantly different when AEDs were administered singly compared to when they were administered in combination would suggest that there is no pharmacokinetic interaction between these AEDs. Thus, the observed potentialization of the acute neurotoxic effects of CBZ and TPM by LEV is the consequence of a pharmacodynamic interaction. These data support both experimental and clinical published data advocating that LEV may interact with some AEDs by pharmacodynamic mechanisms.

The Dependence of Prestellar Core Mass Distributions on the Structure of the Parental Cloud

NASA Astrophysics Data System (ADS)

Parravano, Antonio; Sánchez, Néstor; Alfaro, Emilio J.

2012-08-01

The mass distribution of prestellar cores is obtained for clouds with arbitrary internal mass distributions using a selection criterion based on the thermal and turbulent Jeans mass and applied hierarchically from small to large scales. We have checked this methodology by comparing our results for a log-normal density probability distribution function with the theoretical core mass function (CMF) derived by Hennebelle & Chabrier, namely a power law at large scales and a log-normal cutoff at low scales, but our method can be applied to any mass distributions representing a star-forming cloud. This methodology enables us to connect the parental cloud structure with the mass distribution of the cores and their spatial distribution, providing an efficient tool for investigating the physical properties of the molecular clouds that give rise to the prestellar core distributions observed. Simulated fractional Brownian motion (fBm) clouds with the Hurst exponent close to the value H = 1/3 give the best agreement with the theoretical CMF derived by Hennebelle & Chabrier and Chabrier's system initial mass function. Likewise, the spatial distribution of the cores derived from our methodology shows a surface density of companions compatible with those observed in Trapezium and Ophiucus star-forming regions. This method also allows us to analyze the properties of the mass distribution of cores for different realizations. We found that the variations in the number of cores formed in different realizations of fBm clouds (with the same Hurst exponent) are much larger than the expected root {\\cal N} statistical fluctuations, increasing with H.

Memory T Cells Generated by Prior Exposure to Influenza Cross React with the Novel H7N9 Influenza Virus and Confer Protective Heterosubtypic Immunity

PubMed Central

McMaster, Sean R.; Gabbard, Jon D.; Koutsonanos, Dimitris G.; Compans, Richard W.; Tripp, Ralph A.; Tompkins, S. Mark; Kohlmeier, Jacob E.

2015-01-01

Influenza virus is a source of significant health and economic burden from yearly epidemics and sporadic pandemics. Given the potential for the emerging H7N9 influenza virus to cause severe respiratory infections and the lack of exposure to H7 and N9 influenza viruses in the human population, we aimed to quantify the H7N9 cross-reactive memory T cell reservoir in humans and mice previously exposed to common circulating influenza viruses. We identified significant cross-reactive T cell populations in humans and mice; we also found that cross-reactive memory T cells afforded heterosubtypic protection by reducing morbidity and mortality upon lethal H7N9 challenge. In context with our observation that PR8-primed mice have limited humoral cross-reactivity with H7N9, our data suggest protection from H7N9 challenge is indeed mediated by cross-reactive T cell populations established upon previous priming with another influenza virus. Thus, pre-existing cross-reactive memory T cells may limit disease severity in the event of an H7N9 influenza virus pandemic. PMID:25671696

Memory Dynamics in Cross-linked Actin Networks

NASA Astrophysics Data System (ADS)

Scheff, Danielle; Majumdar, Sayantan; Gardel, Margaret

Cells demonstrate the remarkable ability to adapt to mechanical stimuli through rearrangement of the actin cytoskeleton, a cross-linked network of actin filaments. In addition to its importance in cell biology, understanding this mechanical response provides strategies for creation of novel materials. A recent study has demonstrated that applied stress can encode mechanical memory in these networks through changes in network geometry, which gives rise to anisotropic shear response. Under later shear, the network is stiffer in the direction of the previously applied stress. However, the dynamics behind the encoding of this memory are unknown. To address this question, we explore the effect of varying either the rigidity of the cross-linkers or the length of actin filament on the time scales required for both memory encoding and over which it later decays. While previous experiments saw only a long-lived memory, initial results suggest another mechanism where memories relax relatively quickly. Overall, our study is crucial for understanding the process by which an external stress can impact network arrangement and thus the dynamics of memory formation.

Comparison of resistive switching characteristics using copper and aluminum electrodes on GeOx/W cross-point memories

PubMed Central

2013-01-01

Comparison of resistive switching memory characteristics using copper (Cu) and aluminum (Al) electrodes on GeOx/W cross-points has been reported under low current compliances (CCs) of 1 nA to 50 μA. The cross-point memory devices are observed by high-resolution transmission electron microscopy (HRTEM). Improved memory characteristics are observed for the Cu/GeOx/W structures as compared to the Al/GeOx/W cross-points owing to AlOx formation at the Al/GeOx interface. The RESET current increases with the increase of the CCs varying from 1 nA to 50 μA for the Cu electrode devices, while the RESET current is high (>1 mA) and independent of CCs varying from 1 nA to 500 μA for the Al electrode devices. An extra formation voltage is needed for the Al/GeOx/W devices, while a low operation voltage of ±2 V is needed for the Cu/GeOx/W cross-point devices. Repeatable bipolar resistive switching characteristics of the Cu/GeOx/W cross-point memory devices are observed with CC varying from 1 nA to 50 μA, and unipolar resistive switching is observed with CC >100 μA. High resistance ratios of 102 to 104 for the bipolar mode (CCs of 1 nA to 50 μA) and approximately 108 for the unipolar mode are obtained for the Cu/GeOx/W cross-points. In addition, repeatable switching cycles and data retention of 103 s are observed under a low current of 1 nA for future low-power, high-density, nonvolatile, nanoscale memory applications. PMID:24305116

Cross-cultural and gender differences in childhood amnesia.

PubMed

MacDonald, S; Uesiliana, K; Hayne, H

2000-11-01

In two experiments, we examined cross-cultural and gender differences in adults' earliest memories. To do this, we asked male and female adults from three cultural backgrounds (New Zealand European, New Zealand Maori, and Asian) to describe and date their earliest personal memory. Consistent with past research, Asian adults reported significantly later memories than European adults, however this effect was due exclusively to the extremely late memories reported by Asian females. Maori adults, whose traditional culture includes a strong emphasis on the past, reported significantly earlier memories than adults from the other two cultural groups. Across all three cultures, the memories reported by women contained more information than the memories reported by men. These findings support the view that the age and content of our earliest memories are influenced by a wide range of factors including our culture and our gender. These factors must be incorporated into any comprehensive theory of autobiographical memory.

Automatic orientation and 3D modelling from markerless rock art imagery

NASA Astrophysics Data System (ADS)

Lerma, J. L.; Navarro, S.; Cabrelles, M.; Seguí, A. E.; Hernández, D.

2013-02-01

This paper investigates the use of two detectors and descriptors on image pyramids for automatic image orientation and generation of 3D models. The detectors and descriptors replace manual measurements and are used to detect, extract and match features across multiple imagery. The Scale-Invariant Feature Transform (SIFT) and the Speeded Up Robust Features (SURF) will be assessed based on speed, number of features, matched features, and precision in image and object space depending on the adopted hierarchical matching scheme. The influence of applying in addition Area Based Matching (ABM) with normalised cross-correlation (NCC) and least squares matching (LSM) is also investigated. The pipeline makes use of photogrammetric and computer vision algorithms aiming minimum interaction and maximum accuracy from a calibrated camera. Both the exterior orientation parameters and the 3D coordinates in object space are sequentially estimated combining relative orientation, single space resection and bundle adjustment. The fully automatic image-based pipeline presented herein to automate the image orientation step of a sequence of terrestrial markerless imagery is compared with manual bundle block adjustment and terrestrial laser scanning (TLS) which serves as ground truth. The benefits of applying ABM after FBM will be assessed both in image and object space for the 3D modelling of a complex rock art shelter.

Verbal Working Memory Is Related to the Acquisition of Cross-Linguistic Phonological Regularities.

PubMed

Bosma, Evelyn; Heeringa, Wilbert; Hoekstra, Eric; Versloot, Arjen; Blom, Elma

2017-01-01

Closely related languages share cross-linguistic phonological regularities, such as Frisian -âld [ͻ:t] and Dutch -oud [ʱut], as in the cognate pairs kâld [kͻ:t] - koud [kʱut] 'cold' and wâld [wͻ:t] - woud [wʱut] 'forest'. Within Bybee's (1995, 2001, 2008, 2010) network model, these regularities are, just like grammatical rules within a language, generalizations that emerge from schemas of phonologically and semantically related words. Previous research has shown that verbal working memory is related to the acquisition of grammar, but not vocabulary. This suggests that verbal working memory supports the acquisition of linguistic regularities. In order to test this hypothesis we investigated whether verbal working memory is also related to the acquisition of cross-linguistic phonological regularities. For three consecutive years, 5- to 8-year-old Frisian-Dutch bilingual children ( n = 120) were tested annually on verbal working memory and a Frisian receptive vocabulary task that comprised four cognate categories: (1) identical cognates, (2) non-identical cognates that either do or (3) do not exhibit a phonological regularity between Frisian and Dutch, and (4) non-cognates. The results showed that verbal working memory had a significantly stronger effect on cognate category (2) than on the other three cognate categories. This suggests that verbal working memory is related to the acquisition of cross-linguistic phonological regularities. More generally, it confirms the hypothesis that verbal working memory plays a role in the acquisition of linguistic regularities.

Short Forms of the Wechsler Memory Scale--Revised: Cross- Validation and Derivation of a Two-Subtest Form.

ERIC Educational Resources Information Center

van den Broek, Anneke; Golden, Charles J.; Loonstra, Ann; Ghinglia, Katheryne; Goldstein, Diane

1998-01-01

Indicated excellent cross-validations with correlation of 0.99 for past formulas (J. L. Woodard and B. N. Axelrod, 1995; B. N. Axelrod et al, 1996) for estimating the Wechsler Memory Scale- Revised General Memory and Delayed Recall Indexes. Over 85% of the estimated scores were within 10 points of actual scores. Age, education, diagnosis, and IQ…

Cross-linguistic and cross-cultural effects on verbal working memory and vocabulary: testing language-minority children with an immigrant background.

PubMed

de Abreu, Pascale M J Engel; Baldassi, Martine; Puglisi, Marina L; Befi-Lopes, Debora M

2013-04-01

In this study, the authors explored the impact of test language and cultural status on vocabulary and working memory performance in multilingual language-minority children. Twenty 7-year-old Portuguese-speaking immigrant children living in Luxembourg completed several assessments of first (L1)- and second-language (L2) vocabulary (comprehension and production), executive-loaded working memory (counting recall and backward digit recall), and verbal short-term memory (digit recall and nonword repetition). Cross-linguistic task performance was compared within individuals. The language-minority children were also compared with multilingual language-majority children from Luxembourg and Portuguese-speaking monolinguals from Brazil without an immigrant background matched on age, sex, socioeconomic status, and nonverbal reasoning. Results showed that (a) verbal working memory measures involving numerical memoranda were relatively independent of test language and cultural status; (b) language status had an impact on the repetition of high- but not on low-wordlike L2 nonwords; (c) large cross-linguistic and cross-cultural effects emerged for productive vocabulary; (d) cross-cultural effects were less pronounced for vocabulary comprehension with no differences between groups if only L1 words relevant to the home context were considered. The study indicates that linguistic and cognitive assessments for language-minority children require careful choice among measures to ensure valid results. Implications for testing culturally and linguistically diverse children are discussed.

Exponential stability of impulsive stochastic genetic regulatory networks with time-varying delays and reaction-diffusion

DOE PAGES

Cao, Boqiang; Zhang, Qimin; Ye, Ming

2016-11-29

We present a mean-square exponential stability analysis for impulsive stochastic genetic regulatory networks (GRNs) with time-varying delays and reaction-diffusion driven by fractional Brownian motion (fBm). By constructing a Lyapunov functional and using linear matrix inequality for stochastic analysis we derive sufficient conditions to guarantee the exponential stability of the stochastic model of impulsive GRNs in the mean-square sense. Meanwhile, the corresponding results are obtained for the GRNs with constant time delays and standard Brownian motion. Finally, an example is presented to illustrate our results of the mean-square exponential stability analysis.

Lack of Original Antigenic Sin in Recall CD8+ T Cell Responses

PubMed Central

Zehn, Dietmar; Turner, Michael J.; Lefrançois, Leo; Bevan, Michael J.

2010-01-01

In the real world, mice and men are not immunologically naive, having been exposed to numerous antigenic challenges. Prior infections sometimes negatively impact the response to a subsequent infection. This can occur in serial infections with pathogens sharing cross-reactive Ags. At the T cell level it has been proposed that preformed memory T cells, which cross-react with low avidity to epitopes presented in subsequent infections, dampen the response of high-avidity T cells. We investigated this with a series of related MHC class-I restricted Ags expressed by bacterial and viral pathogens. In all cases, we find that high-avidity CD8+ T cell precursors, either naive or memory, massively expand in secondary cross-reactive infections to dominate the response over low-avidity memory T cells. This holds true even when >10% of the CD8+ T cell compartment consists of memory T cells that cross-react weakly with the rechallenge ligand. Occasionally, memory cells generated by low-avidity stimulation in a primary infection recognize a cross-reactive epitope with high avidity and contribute positively to the response to a second infection. Taken together, our data show that the phenomenon of original antigenic sin does not occur in all heterologous infections. PMID:20439913

Nanoscale thermal cross-talk effect on phase-change probe memory.

PubMed

Wang, Lei; Wen, Jing; Xiong, Bangshu

2018-05-14

Phase-change probe memory is considered as one of the most promising means for next-generation mass storage devices. However, the achievable storage density of phase-change probe memory is drastically affected by the resulting thermal cross-talk effect while previously lacking of detailed study. Therefore, a three dimensional model that couples electrical, thermal, and phase-change processes of the Ge2Sb2Te5 media is developed, and subsequently deployed to assess the thermal cross-talk effect based on Si/TiN/ Ge2Sb2Te5/diamond-like carbon structure by appropriately tailoring the electro-thermal and geometrical properties of the storage media stack for a variety of external excitations. The modeling results show that the diamond-like carbon capping with a thin thickness, a high electrical conductivity, and a low thermal conductivity is desired to minimize the thermal cross-talk, while the TiN underlayer has a slight impact on the thermal cross-talk. Combining the modeling findings with the previous film deposition experience, an optimized phase-change probe memory architecture is presented, and its capability of providing ultra-high recording density simultaneously with a sufficiently low thermal cross-talk is demonstrated. . © 2018 IOP Publishing Ltd.

Collaboration in recall: do pairs of people cross-cue each other to produce new memories?

PubMed

Meudell, P R; Hitch, G J; Boyle, M M

1995-02-01

When people collaborate over their recall of a shared experience, it might be expected that they could "cross-cue" each other so as to produce new memories not available to either member of the pair on their own. In a previous series of experiments (Meudell et al., 1992), we found that pairs of people always recalled more than one person, but we failed to show that social interaction facilitated performance so as to produce such "emergent" new memories. However, a phenomenon akin to cross-cuing was employed by Tulving and Pearlstone (1966) in their classic study of the availability and accessibility of memories; accordingly, in this study, we repeated Tulving and Pearlstone's work directly in a social context. So as to assess whether new memories emerged in collaborating pairs, a sequential design was employed. People learned categorized lists of words, and then all the subjects recalled the items strictly on their own. Subjects then recalled again in pairs (collaboratively) or once more on their own. The results showed that even when the opportunity for cross-cuing was directly manipulated through the provision of categorized lists, no additional new memories emerged in the collaborating groups. Possible mechanisms for the results are considered.

33 CFR 100.124 - Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York.

Code of Federal Regulations, 2011 CFR

2011-07-01

... South Bay Cross Bay Swim, Great South Bay, New York. 100.124 Section 100.124 Navigation and Navigable... NAVIGABLE WATERS § 100.124 Maggie Fischer Memorial Great South Bay Cross Bay Swim, Great South Bay, New York. (a) Regulated area. All navigable waters of Great South Bay, NY within a 100 yard radius of each...

The shape-memory effect in ionic elastomers: fixation through ionic interactions.

PubMed

González-Jiménez, Antonio; Malmierca, Marta A; Bernal-Ortega, Pilar; Posadas, Pilar; Pérez-Aparicio, Roberto; Marcos-Fernández, Ángel; Mather, Patrick T; Valentín, Juan L

2017-04-19

Shape-memory elastomers based on a commercial rubber cross-linked by both ionic and covalent bonds have been developed. The elastomeric matrix was a carboxylated nitrile rubber (XNBR) vulcanized with magnesium oxide (MgO) providing ionic interactions that form hierarchical structures. The so-named ionic transition is used as the unique thermal transition responsible for the shape-memory effect (SME) in these elastomers. These ionic interactions fix the temporary shape due to their behavior as dynamic cross-links with temperature changes. Covalent cross-links were incorporated with the addition of different proportions of dicumyl peroxide (DCP) to the ionic elastomer to establish and recover the permanent shape. In this article, the SME was modulated by modifying the degree of covalent cross-linking, while keeping the ionic contribution constant. In addition, different programming parameters, such as deformation temperature, heating/cooling rate, loading/unloading rate and percentage of tensile strain, were evaluated for their effects on shape-memory behavior.

Memory systems, processes, and tasks: taxonomic clarification via factor analysis.

PubMed

Bruss, Peter J; Mitchell, David B

2009-01-01

The nature of various memory systems was examined using factor analysis. We reanalyzed data from 11 memory tasks previously reported in Mitchell and Bruss (2003). Four well-defined factors emerged, closely resembling episodic and semantic memory and conceptual and perceptual implicit memory, in line with both memory systems and transfer-appropriate processing accounts. To explore taxonomic issues, we ran separate analyses on the implicit tasks. Using a cross-format manipulation (pictures vs. words), we identified 3 prototypical tasks. Word fragment completion and picture fragment identification tasks were "factor pure," tapping perceptual processes uniquely. Category exemplar generation revealed its conceptual nature, yielding both cross-format priming and a picture superiority effect. In contrast, word stem completion and picture naming were more complex, revealing attributes of both processes.

Cross-cultural beliefs about memory and aging for self and others: South Korea and Canada.

PubMed

Ryan, Ellen Bouchard; Jin, Young-Sun; Anas, Ann P

2009-01-01

Young adults in Canada (N = 161) and South Korea (N = 165) rated either themselves or typical others at target ages 25, 45, and 65 years. In both countries, poorer memory was anticipated with each increase in age on all 3 memory belief factors: capacity, change, and locus. Both groups demonstrated a self-protective bias about age-related decline, with Koreans showing a greater effect. These findings demonstrate the cross-cultural generality of negative memory stereotypes of middle and old age and the importance of self-other distinctions in age biases.

The Fluctuating Bond Model, a Glue for Cuprate Superconductivity?

NASA Astrophysics Data System (ADS)

Newns, Dennis

2008-03-01

Twenty years of research have yet to produce a consensus on the origin of high temperature superconductivity (HTS). The mechanism of HTS - which originates in the CuO2 plane, common to all HTS families - can be constrained by some key experimental facts regarding superconducting and pseudogap behaviors. Superconductivity, involving a Tc of order 100 K, exhibits an unusual d-wave superconducting gap, with Fermi liquid nodal excitations, and an anomalous doping- dependent oxygen isotope shift. A ``pseudogap,'' also with d-symmetry, leads to a dip in the density of states below a characteristic temperature scale T^*, which has a negative isotope shift; we associate the pseudogap with the recently observed spatially inhomogeneous (nanometer- scale) C4 symmetry breaking. The isotope shifts and other evidence imply a key role for oxygen vibrations, but conventional BCS single-phonon coupling is essentially forbidden by symmetry and by the on-site Coulomb interaction U. In a novel approach, we introduce a model based on a strong, local, nonlinear interaction between electrons within the Cu-O-Cu bond in the CuO2 plane, and the oxygen vibrational degrees of freedom, termed the Fluctuating Bond Model (FBM) [D.M. Newns and C.C. Tsuei, Nature Physics 3, 184 (2007)]. In mean field the model predicts a phase manifesting broken C4 symmetry, with a d-type pseudogap, and an upper phase boundary in temperature, with a negative isotope shift, which we identify with T^*. An intrinsic d-wave pairing tendency is found, leading to a transition temperature dome and an anomalous isotope shift similar to that found experimentally. The softening in the oxygen vibrational frequency below Tc, seen in Raman and neutron spectra, has a natural explanation in the FBM. Recent ab initio calculations have been implemented which provide microscopic support for the model.

Fractal properties of background noise and target signal enhancement using CSEM data

NASA Astrophysics Data System (ADS)

Benavides, Alfonso; Everett, Mark E.; Pierce, Carl; Nguyen, Cam

2003-09-01

Controlled-source electromagnetic (CSEM) spatial profiles and 2-D conductivity maps were obtained on the Brazos Valley, TX floodplain to study the fractal statistics of geological signals and effects of man-made conductive targets using Geonics EM34, EM31 and EM63. Using target-free areas, a consistent power-law power spectrum (|A(k)| ~ k ^-β) for the profiles was found with β values typical of fractional Brownian motion (fBm). This means that the spatial variation of conductivity does not correspond to Gaussian statistics, where there are spatial correlations at different scales. The presence of targets tends to flatten the power-law power spectrum (PS) at small wavenumbers. Detection and localization of targets can be achieved using short-time Fourier transform (STFT). The presence of targets is enhanced because the signal energy is spread to higher wavenumbers (small scale numbers) in the positions occupied by the targets. In the case of poor spatial sampling or small amount of data, the information available from the power spectrum is not enough to separate spatial correlations from target signatures. Advantages are gained by using the spatial correlations of the fBm in order to reject the background response, and to enhance the signals from highly conductive targets. This approach was tested for the EM31 using a pre-processing step that combines apparent conductivity readings from two perpendicular transmitter-receiver orientations at each station. The response obtained using time-domain CSEM is influence to a lesser degree by geological noise and the target response can be processed to recover target features. The homotopy method is proposed to solve the inverse problem using a set of possible target models and a dynamic library of responses used to optimize the starting model.

How performing a repetitive one-legged stance modifies two-legged postural control.

PubMed

Burdet, Cyril; Vuillerme, Nicolas; Rougier, Patrice R

2011-10-01

The proprioceptive cues in the control of movement is recognized as playing a major role in postural control. However, little is known about its possible increased contribution to postural control consecutive to repetitive muscular activations. To test this, the short-term effects induced by a 1-legged exercise on 2-legged postural control with the eyes closed were assessed in healthy subjects. The center-of-pressure (CP) displacements obtained using a force platform were split into 2 elementary movements: center-of-gravity vertical projection (CGv) and the difference (CP - CGv). These movements assessed the net postural performance and the level of neuromuscular activity, respectively, and were processed afterward (a) through variances, mean velocity, and the average surface covered by the trajectories and (b) a fractional Brownian motion (fBm) modeling. The latter provides further information about how much the subject controls the movements and the spatiotemporal relation between the successive control mechanisms. No difference was found using the classical parameters. In contrast, fBm parameters showed statistically significant changes in postural control after 1-legged exercises: The spatial and temporal coordinates of the transition points for the CG movements along the anteroposterior axis are decreased. Because the body movement control does not rely on visual or vestibular cues, this ability to trigger the corrective process of the CG movements more quickly in the postexercise condition and once a more reduced distance has been covered emphasizes how prior muscular activation improves body movement detection. As a general rule, these data show that the motor systems control body motions better after repetitive stimulation of the sensory cues. These insights should be of interest in physical activities based on a precise muscular length control.

Effect of mechanical processing and fat removal on the nutritive value of cottonseed for lactating dairy cows.

PubMed

Meyer, M J; Shirley, J E; Titgemeyer, E C; Park, A F; VanBaale, M J

2001-11-01

In experiment 1, 24 midlactation, multiparous Holstein cows were used in six 4 x 4 Latin squares to evaluate extruded-expelled cottonseed (EEC) as a source of ruminally undegradable protein (RUP). Diets were formulated to contain: 16% crude protein (CP), 35% RUP (SBM16); 18% CP, 35% RUP (SBM18); 16% CP, 40% RUP using EEC (EC16); and 16% CP, 40% RUP using a fishmeal-blood meal blend (FBM16). Milk yields (37.2 kg/d) and percentages of milk fat, protein, casein, and SNF were similar across diets. Cows fed FBM16 consumed less dry matter (DM) (28.0 kg/d) than those consuming other diets (29.4 kg/d). In experiment 2, 18 midlactation, multiparous Holstein cows were used in six 3 x 3 Latin squares to determine the value of EEC as a replacement for whole cottonseed in lactating cow diets. Diets contained whole cottonseed (CS), EEC plus tallow (ECT), or EEC (EC). Diets were formulated to be similar in energy, N, and RUP. Milk yields (35.5 kg/d), DM intake (27.0 kg/d), and milk fat percent were similar across diets. Percentages of milk protein and SNF were higher for EC than CS or ECT. These production data suggest that EEC can replace whole cottonseed in isocaloric diets and can be partially substituted for soybean meal or a fishmeal-blood meal blend without affecting lactational performance. In situ ruminal degradation and in vitro ammonia N release indicate that processing of EEC was inadequate to protect the protein from ruminal degradation and EEC would not be a source of RUP.

Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer.

PubMed

Luo, Chin-Hsiang; Lee, Whei-May; Liaw, Jiun-Jian

2009-01-01

Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor (MOUDI). The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), and combined with a fractional Brownian motion (fBm) processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m3 (dC/dlogdp) existed in the dominant mode (180-320 nm). A relatively high proportion of these aggregates appeared in PM1, accentuating the relevance regarding adverse health effects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coefficients (H) of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641-1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%-50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.

Memory reactivation and consolidation during sleep

PubMed Central

Paller, Ken A.; Voss, Joel L.

2004-01-01

Do our memories remain static during sleep, or do they change? We argue here that memory change is not only a natural result of sleep cognition, but further, that such change constitutes a fundamental characteristic of declarative memories. In general, declarative memories change due to retrieval events at various times after initial learning and due to the formation and elaboration of associations with other memories, including memories formed after the initial learning episode. We propose that declarative memories change both during waking and during sleep, and that such change contributes to enhancing binding of the distinct representational components of some memories, and thus to a gradual process of cross-cortical consolidation. As a result of this special form of consolidation, declarative memories can become more cohesive and also more thoroughly integrated with other stored information. Further benefits of this memory reprocessing can include developing complex networks of interrelated memories, aligning memories with long-term strategies and goals, and generating insights based on novel combinations of memory fragments. A variety of research findings are consistent with the hypothesis that cross-cortical consolidation can progress during sleep, although further support is needed, and we suggest some potentially fruitful research directions. Determining how processing during sleep can facilitate memory storage will be an exciting focus of research in the coming years. PMID:15576883

Improving text recall with multiple summaries.

PubMed

van der Meij, Hans; van der Meij, Jan

2012-06-01

QuikScan (QS) is an innovative design that aims to improve accessibility, comprehensibility, and subsequent recall of expository text by means of frequent within-document summaries that are formatted as numbered list items. The numbers in the QS summaries correspond to numbers placed in the body of the document where the summarized ideas are discussed in full. To examine the influence of QS summaries on participants' perceptions of text quality (i.e., comprehensibility, structure, and interest) and recall, an experimental - control group design compared the effects of a QS text with a structured abstract (SA) text. Forty psychology students participated voluntarily or received course credits. Students first read a control (SA) or experimental (QS) text on flashbulb memory (FBM). Next, their perceptions of text quality were measured through a questionnaire. Recall was assessed with an open answer test with items for facts, comprehension and higher order information. Perceptions of text quality did not vary across conditions. But QS did lead to significantly and substantially (d= 1.57) higher overall recall scores. Participants with the QS text performed significantly better on all item types than participants with the SA text. Studying a QS text led to a substantial improvement in recall compared to an SA text. Further research is needed to examine how readers study QS texts and whether a text model hypothesis or a repetition effect hypothesis accounts for the effectiveness. The first hypothesis posits that the QS summaries support the reader in constructing a text schema. The second attributes the effects of these summaries to their repetition of text topics. ©2011 The British Psychological Society.

Inability To Detect Cross-Reactive Memory T Cells Challenges the Frequency of Heterologous Immunity among Common Viruses.

PubMed

Rowntree, Louise C; Nguyen, Thi H O; Halim, Hanim; Purcell, Anthony W; Rossjohn, Jamie; Gras, Stephanie; Kotsimbos, Tom C; Mifsud, Nicole A

2018-06-15

Human memory T cells that cross-react with epitopes from unrelated viruses can potentially modulate immune responses to subsequent infections by a phenomenon termed heterologous immunity. However, it is unclear whether similarities in structure rather than sequence underpin heterologous T cell cross-reactivity. In this study, we aimed to explore the mechanism of heterologous immunity involving immunodominant epitopes derived from common viruses restricted to high-frequency HLA allotypes (HLA-A*02:01, -B*07:02, and -B*08:01). We examined EBV-specific memory T cells for their ability to cross-react with CMV or influenza A virus-derived epitopes. Following T cell immunoassays to determine phenotype and function, complemented with biophysical and structural investigations of peptide/HLA complexes, we did not detect cross-reactivity of EBV-specific memory T cells toward either CMV or influenza A virus epitopes presented by any of the selected HLA allomorphs. Thus, despite the ubiquitous nature of these human viruses and the dominant immune response directed toward the selected epitopes, heterologous virus-specific T cell cross-reactivity was not detected. This suggests that either heterologous immunity is not as common as previously reported, or that it requires a very specific biological context to develop and be clinically relevant. Copyright © 2018 by The American Association of Immunologists, Inc.

Interidentity memory transfer in dissociative identity disorder.

PubMed

Kong, Lauren L; Allen, John J B; Glisky, Elizabeth L

2008-08-01

Controversy surrounding dissociative identity disorder (DID) has focused on conflicting findings regarding the validity and nature of interidentity amnesia, illustrating the need for objective methods of examining amnesia that can discriminate between explicit and implicit memory transfer. In the present study, the authors used a cross-modal manipulation designed to mitigate implicit memory effects. Explicit memory transfer between identities was examined in 7 DID participants and 34 matched control participants. After words were presented to one identity auditorily, the authors tested another identity for memory of those words in the visual modality using an exclusion paradigm. Despite self-reported interidentity amnesia, memory for experimental stimuli transferred between identities. DID patients showed no superior ability to compartmentalize information, as would be expected with interidentity amnesia. The cross-modal nature of the test makes it unlikely that memory transfer was implicit. These findings demonstrate that subjective reports of interidentity amnesia are not necessarily corroborated by objective tests of explicit memory transfer. Copyright (c) 2008 APA, all rights reserved.

36 CFR 1501.1 - Cross reference to National Park Service regulations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Cross reference to National Park Service regulations. 1501.1 Section 1501.1 Parks, Forests, and Public Property OKLAHOMA CITY.... As permitted by the Oklahoma City National Memorial Act, the Oklahoma City National Memorial Trust...

36 CFR 1501.1 - Cross reference to National Park Service regulations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Cross reference to National Park Service regulations. 1501.1 Section 1501.1 Parks, Forests, and Public Property OKLAHOMA CITY.... As permitted by the Oklahoma City National Memorial Act, the Oklahoma City National Memorial Trust...

Reconfigurable pipelined processor

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

Saccardi, R.J.

1989-09-19

This patent describes a reconfigurable pipelined processor for processing data. It comprises: a plurality of memory devices for storing bits of data; a plurality of arithmetic units for performing arithmetic functions with the data; cross bar means for connecting the memory devices with the arithmetic units for transferring data therebetween; at least one counter connected with the cross bar means for providing a source of addresses to the memory devices; at least one variable tick delay device connected with each of the memory devices and arithmetic units; and means for providing control bits to the variable tick delay device formore » variably controlling the input and output operations thereof to selectively delay the memory devices and arithmetic units to align the data for processing in a selected sequence.« less

Sequential roles of primary somatosensory cortex and posterior parietal cortex in tactile-visual cross-modal working memory: a single-pulse transcranial magnetic stimulation (spTMS) study.

PubMed

Ku, Yixuan; Zhao, Di; Hao, Ning; Hu, Yi; Bodner, Mark; Zhou, Yong-Di

2015-01-01

Both monkey neurophysiological and human EEG studies have shown that association cortices, as well as primary sensory cortical areas, play an essential role in sequential neural processes underlying cross-modal working memory. The present study aims to further examine causal and sequential roles of the primary sensory cortex and association cortex in cross-modal working memory. Individual MRI-based single-pulse transcranial magnetic stimulation (spTMS) was applied to bilateral primary somatosensory cortices (SI) and the contralateral posterior parietal cortex (PPC), while participants were performing a tactile-visual cross-modal delayed matching-to-sample task. Time points of spTMS were 300 ms, 600 ms, 900 ms after the onset of the tactile sample stimulus in the task. The accuracy of task performance and reaction time were significantly impaired when spTMS was applied to the contralateral SI at 300 ms. Significant impairment on performance accuracy was also observed when the contralateral PPC was stimulated at 600 ms. SI and PPC play sequential and distinct roles in neural processes of cross-modal associations and working memory. Copyright © 2015 Elsevier Inc. All rights reserved.

Chemical cross-linking of polypropylenes towards new shape memory polymers.

PubMed

Raidt, Thomas; Hoeher, Robin; Katzenberg, Frank; Tiller, Joerg C

2015-04-01

In this work, syndiotactic polypropylene (sPP) as well as isotactic polypropylene (iPP) are cross-linked to gain a shape memory effect. Both prepared PP networks exhibit maximum strains of 700%, stored strains of up to 680%, and recoveries of nearly 100%. While x-iPP is stable for many cycles, x-sPP ruptures after the first shape-memory cycle. It is shown by wide-angle X-ray scattering (WAXS) experiments that cross-linked iPP exhibits homoepitaxy in the temporary, stretched shape but in contrast to previous reports it contains a higher amount of daughter than mother crystals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced tactile encoding and memory recognition in congenital blindness.

PubMed

D'Angiulli, Amedeo; Waraich, Paul

2002-06-01

Several behavioural studies have shown that early-blind persons possess superior tactile skills. Since neurophysiological data show that early-blind persons recruit visual as well as somatosensory cortex to carry out tactile processing (cross-modal plasticity), blind persons' sharper tactile skills may be related to cortical re-organisation resulting from loss of vision early in their life. To examine the nature of blind individuals' tactile superiority and its implications for cross-modal plasticity, we compared the tactile performance of congenitally totally blind, low-vision and sighted children on raised-line picture identification test and re-test, assessing effects of task familiarity, exploratory strategy and memory recognition. What distinguished the blind from the other children was higher memory recognition and higher tactile encoding associated with efficient exploration. These results suggest that enhanced perceptual encoding and recognition memory may be two cognitive correlates of cross-modal plasticity in congenital blindness.

Emotion Knowledge and Autobiographical Memory across the Preschool Years: A Cross-Cultural Longitudinal Investigation

ERIC Educational Resources Information Center

Wang, Qi

2008-01-01

Knowledge of emotion situations facilitates the interpretation, processing, and organization of significant personal event information and thus may be an important contributor to the development of autobiographical memory. This longitudinal study tested the hypothesis in a cross-cultural context. The participants were native Chinese children,…

The neural basis of visual dominance in the context of audio-visual object processing.

PubMed

Schmid, Carmen; Büchel, Christian; Rose, Michael

2011-03-01

Visual dominance refers to the observation that in bimodal environments vision often has an advantage over other senses in human. Therefore, a better memory performance for visual compared to, e.g., auditory material is assumed. However, the reason for this preferential processing and the relation to the memory formation is largely unknown. In this fMRI experiment, we manipulated cross-modal competition and attention, two factors that both modulate bimodal stimulus processing and can affect memory formation. Pictures and sounds of objects were presented simultaneously in two levels of recognisability, thus manipulating the amount of cross-modal competition. Attention was manipulated via task instruction and directed either to the visual or the auditory modality. The factorial design allowed a direct comparison of the effects between both modalities. The resulting memory performance showed that visual dominance was limited to a distinct task setting. Visual was superior to auditory object memory only when allocating attention towards the competing modality. During encoding, cross-modal competition and attention towards the opponent domain reduced fMRI signals in both neural systems, but cross-modal competition was more pronounced in the auditory system and only in auditory cortex this competition was further modulated by attention. Furthermore, neural activity reduction in auditory cortex during encoding was closely related to the behavioural auditory memory impairment. These results indicate that visual dominance emerges from a less pronounced vulnerability of the visual system against competition from the auditory domain. Copyright © 2010 Elsevier Inc. All rights reserved.

Does grammatical aspect affect motion event cognition? A cross-linguistic comparison of English and Swedish speakers.

PubMed

Athanasopoulos, Panos; Bylund, Emanuel

2013-03-01

In this article, we explore whether cross-linguistic differences in grammatical aspect encoding may give rise to differences in memory and cognition. We compared native speakers of two languages that encode aspect differently (English and Swedish) in four tasks that examined verbal descriptions of stimuli, online triads matching, and memory-based triads matching with and without verbal interference. Results showed between-group differences in verbal descriptions and in memory-based triads matching. However, no differences were found in online triads matching and in memory-based triads matching with verbal interference. These findings need to be interpreted in the context of the overall pattern of performance, which indicated that both groups based their similarity judgments on common perceptual characteristics of motion events. These results show for the first time a cross-linguistic difference in memory as a function of differences in grammatical aspect encoding, but they also contribute to the emerging view that language fine tunes rather than shapes perceptual processes that are likely to be universal and unchanging. Copyright © 2012 Cognitive Science Society, Inc.

Cross-reactive influenza virus–specific CD8+ T cells contribute to lymphoproliferation in Epstein-Barr virus–associated infectious mononucleosis

PubMed Central

Clute, Shalyn C.; Watkin, Levi B.; Cornberg, Markus; Naumov, Yuri N.; Sullivan, John L.; Luzuriaga, Katherine; Welsh, Raymond M.; Selin, Liisa K.

2005-01-01

The marked proliferation of activated CD8+ T cells is pathognomonic of EBV-associated infectious mononucleosis (IM), common in young adults. Since the diversity and size of the memory CD8+ T cell population increase with age, we questioned whether IM was mediated by the reactivation of memory CD8+ T cells specific to previously encountered pathogens but cross-reactive with EBV. Of 8 HLA-A2+ IM patients, 5 had activated T cells specific to another common virus, as evidenced by a significantly higher number of peripheral blood influenza A virus M158–66–specific T cells compared with healthy immune donors. Two patients with an augmented M1 response had tetramer-defined cross-reactive cells recognizing influenza M1 and EBV-BMLF1280–288, which accounted for up to one-third of their BMLF1-specific population and likely contributed to a skewed M1-specific T cell receptor repertoire. These epitopes, with only 33% sequence similarity, mediated differential effects on the function of the cross-reactive T cells, which may contribute to alterations in disease outcome. EBV could potentially encode an extensive pool of T cell epitopes that activate other cross-reactive memory T cells. Our results support the concept that cross-reactive memory CD8+ T cells activated by EBV contribute to the characteristic lymphoproliferation of IM. PMID:16308574

Cross-reactive influenza virus-specific CD8+ T cells contribute to lymphoproliferation in Epstein-Barr virus-associated infectious mononucleosis.

PubMed

Clute, Shalyn C; Watkin, Levi B; Cornberg, Markus; Naumov, Yuri N; Sullivan, John L; Luzuriaga, Katherine; Welsh, Raymond M; Selin, Liisa K

2005-12-01

The marked proliferation of activated CD8+ T cells is pathognomonic of EBV-associated infectious mononucleosis (IM), common in young adults. Since the diversity and size of the memory CD8+ T cell population increase with age, we questioned whether IM was mediated by the reactivation of memory CD8+ T cells specific to previously encountered pathogens but cross-reactive with EBV. Of 8 HLA-A2+ IM patients, 5 had activated T cells specific to another common virus, as evidenced by a significantly higher number of peripheral blood influenza A virus M1(58-66)-specific T cells compared with healthy immune donors. Two patients with an augmented M1 response had tetramer-defined cross-reactive cells recognizing influenza M1 and EBV-BMLF1(280-288), which accounted for up to one-third of their BMLF1-specific population and likely contributed to a skewed M1-specific T cell receptor repertoire. These epitopes, with only 33% sequence similarity, mediated differential effects on the function of the cross-reactive T cells, which may contribute to alterations in disease outcome. EBV could potentially encode an extensive pool of T cell epitopes that activate other cross-reactive memory T cells. Our results support the concept that cross-reactive memory CD8+ T cells activated by EBV contribute to the characteristic lymphoproliferation of IM.

Children's Memory for Words Under Self-Reported and Induced Imagery Strategies.

ERIC Educational Resources Information Center

Filan, Gary L.; Sullivan, Howard J.

The effectiveness of the use of self-reported imagery strategies on children's subsequent memory performance was studied, and the coding redundancy hypothesis that memory is facilitated by using an encoding procedure in both words and images was tested. The two levels of reported memory strategy (imagize, verbalize) were crossed with "think…

Does Grammatical Aspect Affect Motion Event Cognition? A Cross-Linguistic Comparison of English and Swedish Speakers

ERIC Educational Resources Information Center

Athanasopoulos, Panos; Bylund, Emanuel

2013-01-01

In this article, we explore whether cross-linguistic differences in grammatical aspect encoding may give rise to differences in memory and cognition. We compared native speakers of two languages that encode aspect differently (English and Swedish) in four tasks that examined verbal descriptions of stimuli, online triads matching, and memory-based…

Reversible TAD Chemistry as a Convenient Tool for the Design of (Re)processable PCL-Based Shape-Memory Materials.

PubMed

Defize, Thomas; Riva, Raphaël; Thomassin, Jean-Michel; Alexandre, Michaël; Herck, Niels Van; Prez, Filip Du; Jérôme, Christine

2017-01-01

A chemically cross-linked but remarkably (re)processable shape-memory polymer (SMP) is designed by cross-linking poly(ε-caprolactone) (PCL) stars via the efficient triazolinedione click chemistry, based on the very fast and reversible Alder-ene reaction of 1,2,4-triazoline-3,5-dione (TAD) with indole compounds. Typically, a six-arm star-shaped PCL functionalized by indole moieties at the chain ends is melt-blended with a bisfunctional TAD, directly resulting in a cross-linked PCL-based SMP without the need of post-curing treatment. As demonstrated by the stress relaxation measurement, the labile character of the TAD-indole adducts under stress allows for the solid-state plasticity reprocessing of the permanent shape at will by compression molding of the raw cross-linked material, while keeping excellent shape-memory properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Triple shape memory effects of cross-linked polyethylene/polypropylene blends with cocontinuous architecture.

PubMed

Zhao, Jun; Chen, Min; Wang, Xiaoyan; Zhao, Xiaodong; Wang, Zhenwen; Dang, Zhi-Min; Ma, Lan; Hu, Guo-Hua; Chen, Fenghua

2013-06-26

In this paper, the triple shape memory effects (SMEs) observed in chemically cross-linked polyethylene (PE)/polypropylene (PP) blends with cocontinuous architecture are systematically investigated. The cocontinuous window of typical immiscible PE/PP blends is the volume fraction of PE (v(PE)) of ca. 30-70 vol %. This architecture can be stabilized by chemical cross-linking. Different initiators, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane (DHBP), dicumylperoxide (DCP) coupled with divinylbenzene (DVB) (DCP-DVB), and their mixture (DHBP/DCP-DVB), are used for the cross-linking. According to the differential scanning calorimetry (DSC) measurements and gel fraction calculations, DHBP produces the best cross-linking and DCP-DVB the worst, and the mixture, DHBP/DCP-DVB, is in between. The chemical cross-linking causes lower melting temperature (Tm) and smaller melting enthalpy (ΔHm). The prepared triple shape memory polymers (SMPs) by cocontinuous immiscible PE/PP blends with v(PE) of 50 vol % show pronounced triple SMEs in the dynamic mechanical thermal analysis (DMTA) and visual observation. This new strategy of chemically cross-linked immiscible blends with cocontinuous architecture can be used to design and prepare new SMPs with triple SMEs.

Average cross-responses in correlated financial markets

NASA Astrophysics Data System (ADS)

Wang, Shanshan; Schäfer, Rudi; Guhr, Thomas

2016-09-01

There are non-vanishing price responses across different stocks in correlated financial markets, reflecting non-Markovian features. We further study this issue by performing different averages, which identify active and passive cross-responses. The two average cross-responses show different characteristic dependences on the time lag. The passive cross-response exhibits a shorter response period with sizeable volatilities, while the corresponding period for the active cross-response is longer. The average cross-responses for a given stock are evaluated either with respect to the whole market or to different sectors. Using the response strength, the influences of individual stocks are identified and discussed. Moreover, the various cross-responses as well as the average cross-responses are compared with the self-responses. In contrast to the short-memory trade sign cross-correlations for each pair of stocks, the sign cross-correlations averaged over different pairs of stocks show long memory.

Impact of electrically formed interfacial layer and improved memory characteristics of IrOx/high-κx/W structures containing AlOx, GdOx, HfOx, and TaOx switching materials.

PubMed

Prakash, Amit; Maikap, Siddheswar; Banerjee, Writam; Jana, Debanjan; Lai, Chao-Sung

2013-09-06

Improved switching characteristics were obtained from high-κ oxides AlOx, GdOx, HfOx, and TaOx in IrOx/high-κx/W structures because of a layer that formed at the IrOx/high-κx interface under external positive bias. The surface roughness and morphology of the bottom electrode in these devices were observed by atomic force microscopy. Device size was investigated using high-resolution transmission electron microscopy. More than 100 repeatable consecutive switching cycles were observed for positive-formatted memory devices compared with that of the negative-formatted devices (only five unstable cycles) because it contained an electrically formed interfacial layer that controlled 'SET/RESET' current overshoot. This phenomenon was independent of the switching material in the device. The electrically formed oxygen-rich interfacial layer at the IrOx/high-κx interface improved switching in both via-hole and cross-point structures. The switching mechanism was attributed to filamentary conduction and oxygen ion migration. Using the positive-formatted design approach, cross-point memory in an IrOx/AlOx/W structure was fabricated. This cross-point memory exhibited forming-free, uniform switching for >1,000 consecutive dc cycles with a small voltage/current operation of ±2 V/200 μA and high yield of >95% switchable with a large resistance ratio of >100. These properties make this cross-point memory particularly promising for high-density applications. Furthermore, this memory device also showed multilevel capability with a switching current as low as 10 μA and a RESET current of 137 μA, good pulse read endurance of each level (>105 cycles), and data retention of >104 s at a low current compliance of 50 μA at 85°C. Our improvement of the switching characteristics of this resistive memory device will aid in the design of memory stacks for practical applications.

Recirculating cross-correlation detector

DOEpatents

Andrews, W.H. Jr.; Roberts, M.J.

1985-01-18

A digital cross-correlation detector is provided in which two time-varying signals are correlated by repetitively comparing data samples stored in digital form to detect correlation between the two signals. The signals are sampled at a selected rate converted to digital form, and stored in separate locations in separate memories. When the memories are filled, the data samples from each memory are first fed word-by-word through a multiplier and summing circuit and each result is compared to the last in a peak memory circuit and if larger than the last is retained in the peak memory. Then the address line to leading signal memory is offset by one byte to affect one sample period delay of a known amount in that memory and the data in the two memories are then multiplied word-by-word once again and summed. If a new result is larger than a former sum, it is saved in the peak memory together with the time delay. The recirculating process continues with the address of the one memory being offset one additional byte each cycle until the address is shifted through the length of the memory. The correlation between the two signals is indicated by the peak signal stored in the peak memory together with the delay time at which the peak occurred. The circuit is faster and considerably less expensive than comparable accuracy correlation detectors.

Dissociation of Cross-Sectional Trajectories for Verbal and Visuo-Spatial Working Memory Development in Rubinstein-Taybi Syndrome

ERIC Educational Resources Information Center

Waite, Jane; Beck, Sarah R.; Heald, Mary; Powis, Laurie; Oliver, Chris

2016-01-01

Working 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…

Hippocampal-prefrontal theta-gamma coupling during performance of a spatial working memory task.

PubMed

Tamura, Makoto; Spellman, Timothy J; Rosen, Andrew M; Gogos, Joseph A; Gordon, Joshua A

2017-12-19

Cross-frequency coupling supports the organization of brain rhythms and is present during a range of cognitive functions. However, little is known about whether and how long-range cross-frequency coupling across distant brain regions subserves working memory. Here we report that theta-slow gamma coupling between the hippocampus and medial prefrontal cortex (mPFC) is augmented in a genetic mouse model of cognitive dysfunction. This increased cross-frequency coupling is observed specifically when the mice successfully perform a spatial working memory task. In wild-type mice, increasing task difficulty by introducing a long delay or by optogenetically interfering with encoding, also increases theta-gamma coupling during correct trials. Finally, epochs of high hippocampal theta-prefrontal slow gamma coupling are associated with increased synchronization of neurons within the mPFC. These findings suggest that enhancement of theta-slow gamma coupling reflects a compensatory mechanism to maintain spatial working memory performance in the setting of increased difficulty.

A Structural Approach to Establishing a Platform Chemistry for the Tunable, Bulk Electron Beam Cross-Linking of Shape Memory Polymer Systems

PubMed Central

Hearon, Keith; Besset, Celine J.; Lonnecker, Alexander T.; Ware, Taylor; Voit, Walter E.; Wilson, Thomas S.; Wooley, Karen L.; Maitland, Duncan J.

2014-01-01

The synthetic design and thermomechanical characterization of shape memory polymers (SMPs) built from a new polyurethane chemistry that enables facile, bulk and tunable cross-linking of low-molecular weight thermoplastics by electron beam irradiation is reported in this study. SMPs exhibit stimuli-induced geometry changes and are being proposed for applications in numerous fields. We have previously reported a polyurethane SMP system that exhibits the complex processing capabilities of thermoplastic polymers and the mechanical robustness and tunability of thermomechanical properties that are often characteristic of thermoset materials. These previously reported polyurethanes suffer practically because the thermoplastic molecular weights needed to achieve target cross-link densities severely limit high-throughput thermoplastic processing and because thermally unstable radiation-sensitizing additives must be used to achieve high enough cross-link densities to enable desired tunable shape memory behavior. In this study, we demonstrate the ability to manipulate cross-link density in low-molecular weight aliphatic thermoplastic polyurethane SMPs (Mw as low as ~1.5 kDa) without radiation-sensitizing additives by incorporating specific structural motifs into the thermoplastic polymer side chains that we hypothesized would significantly enhance susceptibility to e-beam cross-linking. A custom diol monomer was first synthesized and then implemented in the synthesis of neat thermoplastic polyurethane SMPs that were irradiated at doses ranging from 1 to 500 kGy. Dynamic mechanical analysis (DMA) demonstrated rubbery moduli to be tailorable between 0.1 and 55 MPa, and both DMA and sol/gel analysis results provided fundamental insight into our hypothesized mechanism of electron beam cross-linking, which enables controllable bulk cross-linking to be achieved in highly processable, low-molecular weight thermoplastic shape memory polymers without sensitizing additives. PMID:25411511

Cross-Linguistic and Cross-Cultural Effects on Verbal Working Memory and Vocabulary: Testing Language-Minority Children with an Immigrant Background

ERIC Educational Resources Information Center

Engel de Abreu, Pascale M. J.; Baldassi, Martine; Puglisi, Marina L.; Befi-Lopes, Debora M.

2013-01-01

Purpose: In this study, the authors explored the impact of test language and cultural status on vocabulary and working memory performance in multilingual language-minority children. Method: Twenty 7-year-old Portuguese-speaking immigrant children living in Luxembourg completed several assessments of first (L1)- and second-language (L2) vocabulary…

Total Ionizing Dose Influence on the Single-Event Upset Sensitivity of 130-nm PD SOI SRAMs

NASA Astrophysics Data System (ADS)

Zheng, Qiwen; Cui, Jiangwei; Liu, Mengxin; Zhou, Hang; Liu, Mohan; Wei, Ying; Su, Dandan; Ma, Teng; Lu, Wu; Yu, Xuefeng; Guo, Qi; He, Chengfa

2017-07-01

Effect of total ionizing dose (TID) on single-event upset (SEU) hardness of 130 nm partially depleted (PD) silicon-on-insulator (SOI) static random access memories (SRAMs) is investigated in this paper. The measurable synergistic effect of TID on SEU sensitivity of 130-nm PD SOI SRAM was observed in our experiment, even though that is far less than micrometer and submicrometer devices. Moreover, SEU cross section after TID irradiation has no dependence on the data pattern that was applied during TID exposure: SEU cross sections are characterized by TID data pattern and its complement data pattern are decreased consistently rather than a preferred state and a nonpreferred state as micrometer and sub-micrometer SRAMs. The memory cell test structure allowing direct measurement of static noise margin (SNM) under standby operation was designed using identical memory cell layout of SRAM. Direct measurement of the memory cell SNM shows that both data sides' SNM is decreased by TID, indicating that SEU cross section of 130-nm PD SOI SRAM will be increased by TID. And, the decreased SNM is caused by threshold shift in memory cell transistors induced by “radiation-induced narrow channel effect”.

Cross-Cultural Differences in the Neural Correlates of Specific and General Recognition

PubMed Central

Paige, Laura E.; Ksander, John C.; Johndro, Hunter A.; Gutchess, Angela H.

2017-01-01

Research suggests that culture influences how people perceive the world, which extends to memory specificity, or how much perceptual detail is remembered. The present study investigated cross-cultural differences (Americans vs. East Asians) at the time of encoding in the neural correlates of specific vs. general memory formation. Participants encoded photos of everyday items in the scanner and 48 hours later completed a surprise recognition test. The recognition test consisted of same (i.e., previously seen in scanner), similar (i.e., same name, different features), or new photos (i.e., items not previously seen in scanner). For Americans compared to East Asians, we predicted greater activation in the hippocampus and right fusiform for specific memory at recognition, as these regions were implicated previously in encoding perceptual details. Results revealed that East Asians activated the left fusiform and left hippocampus more than Americans for specific vs. general memory. Follow-up analyses ruled out alternative explanations of retrieval difficulty and familiarity for this pattern of cross-cultural differences at encoding. Results overall suggest that culture should be considered as another individual difference that affects memory specificity and modulates neural regions underlying these processes. PMID:28256199

Cross-cultural differences in the neural correlates of specific and general recognition.

PubMed

Paige, Laura E; Ksander, John C; Johndro, Hunter A; Gutchess, Angela H

2017-06-01

Research suggests that culture influences how people perceive the world, which extends to memory specificity, or how much perceptual detail is remembered. The present study investigated cross-cultural differences (Americans vs East Asians) at the time of encoding in the neural correlates of specific versus general memory formation. Participants encoded photos of everyday items in the scanner and 48 h later completed a surprise recognition test. The recognition test consisted of same (i.e., previously seen in scanner), similar (i.e., same name, different features), or new photos (i.e., items not previously seen in scanner). For Americans compared to East Asians, we predicted greater activation in the hippocampus and right fusiform for specific memory at recognition, as these regions were implicated previously in encoding perceptual details. Results revealed that East Asians activated the left fusiform and left hippocampus more than Americans for specific versus general memory. Follow-up analyses ruled out alternative explanations of retrieval difficulty and familiarity for this pattern of cross-cultural differences at encoding. Results overall suggest that culture should be considered as another individual difference that affects memory specificity and modulates neural regions underlying these processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transport behaviors of locally fractional coupled Brownian motors with fluctuating interactions

NASA Astrophysics Data System (ADS)

Wang, Huiqi; Ni, Feixiang; Lin, Lifeng; Lv, Wangyong; Zhu, Hongqiang

2018-09-01

In some complex viscoelastic mediums, it is ubiquitous that absorbing and desorbing surrounding Brownian particles randomly occur in coupled systems. The conventional method is to model a variable-mass system driven by both multiplicative and additive noises. In this paper, an improved mathematical model is created based on generalized Langevin equations (GLE) to characterize the random interaction with locally fluctuating number of coupled particles in the elastically coupled factional Brownian motors (FBM). By the numerical simulations, the effect of fluctuating interactions on collective transport behaviors is investigated, and some abnormal phenomena, such as cooperative behaviors, stochastic resonance (SR) and anomalous transport, are observed in the regime of sub-diffusion.

A cross-lagged model of the reciprocal associations of loneliness and memory functioning.

PubMed

Ayalon, Liat; Shiovitz-Ezra, Sharon; Roziner, Ilan

2016-05-01

The study was designed to evaluate the reciprocal associations of loneliness and memory functioning using a cross-lagged model. The study was based on the psychosocial questionnaire of the Health and Retirement Study, which is a U.S. nationally representative survey of individuals over the age of 50 and their spouses of any age. A total of 1,225 respondents had complete data on the loneliness measure in 2004 and at least in 1 of the subsequent waves (e.g., 2008, 2012) and were maintained for analysis. A cross-lagged model was estimated to examine the reciprocal associations of loneliness and memory functioning, controlling for age, gender, education, depressive symptoms, number of medical conditions, and the number of close social relationships. The model had adequate fit indices: χ2(860, N = 1,225) = 1,401.54, p < .001, Tucker-Lewis index = .957, comparative fit index = .963, and root mean square error of approximation = .023 (90% confidence interval [.021, .025]). The lagged effect of loneliness on memory functioning was nonsignificant, B(SE) = -.11(.08), p = .15, whereas the lagged effect of memory functioning on loneliness was significant, B(SE) = -.06(.02), p = .01, indicating that lower levels of memory functioning precede higher levels of loneliness 4 years afterward. Further research is required to better understand the mechanisms responsible for the temporal association between reduced memory functioning and increased loneliness. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Cross-cultural differences in categorical memory errors.

PubMed

Schwartz, Aliza J; Boduroglu, Aysecan; Gutchess, Angela H

2014-06-01

Cultural differences occur in the use of categories to aid accurate recall of information. This study investigated whether culture also contributed to false (erroneous) memories, and extended cross-cultural memory research to Turkish culture, which is shaped by Eastern and Western influences. Americans and Turks viewed word pairs, half of which were categorically related and half unrelated. Participants then attempted to recall the second word from the pair in response to the first word cue. Responses were coded as correct, as blanks, or as different types of errors. Americans committed more categorical errors than did Turks, and Turks mistakenly recalled more non-categorically related list words than did Americans. These results support the idea that Americans use categories either to organize information in memory or to support retrieval strategies to a greater extent than Turks and suggest that culture shapes not only accurate recall but also erroneous distortions of memory. © 2014 Cognitive Science Society, Inc.

Disturbance characteristics of half-selected cells in a cross-point resistive switching memory array

NASA Astrophysics Data System (ADS)

Chen, Zhe; Li, Haitong; Chen, Hong-Yu; Chen, Bing; Liu, Rui; Huang, Peng; Zhang, Feifei; Jiang, Zizhen; Ye, Hongfei; Gao, Bin; Liu, Lifeng; Liu, Xiaoyan; Kang, Jinfeng; Wong, H.-S. Philip; Yu, Shimeng

2016-05-01

Disturbance characteristics of cross-point resistive random access memory (RRAM) arrays are comprehensively studied in this paper. An analytical model is developed to quantify the number of pulses (#Pulse) the cell can bear before disturbance occurs under various sub-switching voltage stresses based on physical understanding. An evaluation methodology is proposed to assess the disturb behavior of half-selected (HS) cells in cross-point RRAM arrays by combining the analytical model and SPICE simulation. The characteristics of cross-point RRAM arrays such as energy consumption, reliable operating cycles and total error bits are evaluated by the methodology. A possible solution to mitigate disturbance is proposed.

Memory T cells in organ transplantation: progress and challenges

PubMed Central

Espinosa, Jaclyn R.; Samy, Kannan P.; Kirk, Allan D.

2017-01-01

Antigen-experienced T cells, also known as memory T cells, are functionally and phenotypically distinct from naive T cells. Their enhanced expression of adhesion molecules and reduced requirement for co-stimulation enables them to mount potent and rapid recall responses to subsequent antigen encounters. Memory T cells generated in response to prior antigen exposures can cross-react with other nonidentical, but similar, antigens. This heterologous cross-reactivity not only enhances protective immune responses, but also engenders de novo alloimmunity. This latter characteristic is increasingly recognized as a potential barrier to allograft acceptance that is worthy of immunotherapeutic intervention, and several approaches have been investigated. Calcineurin inhibition effectively controls memory T-cell responses to allografts, but this benefit comes at the expense of increased infectious morbidity. Lymphocyte depletion eliminates allospecific T cells but spares memory T cells to some extent, such that patients do not completely lose protective immunity. Co-stimulation blockade is associated with reduced adverse-effect profiles and improved graft function relative to calcineurin inhibition, but lacks efficacy in controlling memory T-cell responses. Targeting the adhesion molecules that are upregulated on memory T cells might offer additional means to control co-stimulation-blockade-resistant memory T-cell responses. PMID:26923209

The relationship between different exercise modes and visuospatial working memory in older adults: a cross-sectional study.

PubMed

Guo, Wei; Wang, Biye; Lu, Yue; Zhu, Qin; Shi, Zhihao; Ren, Jie

2016-01-01

The purpose of the study was to investigate the relationship between different exercise modes and visuospatial working memory in healthy older adults. A cross-sectional design was adopted. A total of 111 healthy older adults were enrolled in the study. They were classified by the exercise-related questionnaire to be in an open-skill group, closed-skill group or sedentary group. In experiment 1, the participants performed a visuospatial working memory task. The results indicated that both closed-skill (p < 0.05) and open-skill (p < 0.01) groups reached a higher accuracy than the sedentary group. Experiment 2 examined whether the exercise-induced benefit of working memory was manifested in passive maintenance or active manipulation of working memory which was assessed by visuospatial short-term memory task and visuospatial mental rotation task, respectively. The results showed that the open-skill (p < 0.01) group was more accurate than the sedentary group in the visuospatial short-term memory task, whereas the group difference in the visuospatial mental rotation task was not significant. These findings combined to suggest that physical exercise was associated with better visuospatial working memory in older adults. Furthermore, open-skill exercises that demand higher cognitive processing showed selective benefit for passive maintenance of working memory.

Memory for Sequences of Events Impaired in Typical Aging

ERIC Educational Resources Information Center

Allen, Timothy A.; Morris, Andrea M.; Stark, Shauna M.; Fortin, Norbert J.; Stark, Craig E. L.

2015-01-01

Typical aging is associated with diminished episodic memory performance. To improve our understanding of the fundamental mechanisms underlying this age-related memory deficit, we previously developed an integrated, cross-species approach to link converging evidence from human and animal research. This novel approach focuses on the ability to…

Circuit-Switched Memory Access in Photonic Interconnection Networks for High-Performance Embedded Computing

DTIC Science & Technology

2010-07-22

dependent , providing a natural bandwidth match between compute cores and the memory subsystem. • High Bandwidth Dcnsity. Waveguides crossing the chip...simulate this memory access architecture on a 2S6-core chip with a concentrated 64-node network lIsing detailed traces of high-performance embedded...memory modulcs, wc placc memory access poi nts (MAPs) around the pcriphery of the chip connected to thc nctwork. These MAPs, shown in Figure 4, contain

Effects of Induced Memory Strategies on Children's Memory for Pictures and Words.

ERIC Educational Resources Information Center

Filan, Gary; Sullivan, Howard

In this study of children's memory, two types of presentation modes (pictures or words) were crossed with two levels of memory strategy ("make a picture in your mind" or "think of the word") to comprise four treatments: see picture/think picture, see picture/think word, see word/think picture, see word/think word. The study was conducted with 144…

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.

Waste utilization of red snapper (Lutjanus sp.) fish bone to improve phosphorus contents in compost

NASA Astrophysics Data System (ADS)

Ramadhani, S.; Iswanto, B.; Purwaningrum, P.

2018-01-01

The purpose of this research is to get the idea that bone waste will be the P content enhancer in compost so that the compost produced meets the standard P levels specified in SNI 19-7030-2004 which regulating compost quality standard. Nutrient levels were obtained in fish bone meal (FBM) are C (3.35%), N (0.48%), P (30.90%) and K (0.02%). Effects of fish bone meal to the rising levels of P in the compost has been known. P levels of compost B, C, D, and E increased at 428.57; 542.85; 657.14 and 914.28% against the compost A (blank). FBM ideal addition indicated in compost B, as much as 15 gr, with a P content of 0.37% and has been passed according standards (0.10% for P). C/N ratio decreased over the 21 days period of composting, with the greatest decline was compost E with a ratio of 16:1. Highest nitrogen (N) levels recorded respectively in compost B and C with value of 1.09% and the lowest of recorded N content was compost A, D and E (1.08%). N content in all samples of compost were eligible minimum N of 0.40%. Carbon (C) is the highest recorded in compost B; 20.20% and the lowest in the compost E; 17.34%. Highest and lowest C levels on the compost has met the minimum C of 9.80%. Composting is done in a bucket as an aerobic composter (with air holes), compost pile turnover for each sample is controlled as much as once/2 days. Mesophilic period (23-450C) occurs during the 21-day period of composting. Compost B has P content of 0.37%, so it has fulfilled the provisions of SNI 19-7030-2004 about the recommended compost standard.

Temporal Variation and Scaling of Hydrological Variables in a Typical Watershed

NASA Astrophysics Data System (ADS)

Yang, C.; Zhang, Y. K.; Liang, X.; Liu, J.

2016-12-01

Temporal variations of the main hydrological variables over 16 years were systematically investigated based on the results from an integrated hydrological modeling at the Sagehen Creek Watershed in northern Sierra Nevada. Temporal scaling of these variables and damping effects of the hydrological system as well as its subsystems, i.e., the land surface, unsaturated zone, and saturated zone, were analyzed with spectral analyses. It was found that the hydrological system may act as a cascade of hierarchical fractal filters which sequentially transfer a non-fractal or less correlated fractal hydrological signal to a more correlated fractal signal. Temporal scaling of infiltration (I), actual evapotraspiration (ET), recharge (R), baseflow (BF), streamflow (SF) exist and the temporal autocorrelation of these variables increase as water moves through the system. The degree of the damping effect of the subsystems is different and is strongest in the unsaturated zone compared with that of the land surface and saturated zone. The temporal scaling of the groundwater levels (h) also exists and is strongly affected by the river: the temporal autocorrelation of h near the river is similar to that of the river stage fluctuations and increases away from the river. There is a break in the temporal scaling of h near the river at low frequencies due to the effect of the river. Temporal variations of the soil moisture (θ) is more complicated: the value of the scaling exponent (β) for θ increases with depth as water moves downwards and its high-frequency fluctuations are damped by the unsaturated zone. The temporal fluctuations of precipitation (P) and I are fractional Gauss noise (fGn), those of ET, R, BF, and SF are fractional Brownian motion (fBm), and those of h away from the river are 2nd-order fBm based on the values of β obtained in this study. Keywords: Temporal variations, Scaling, Damping effect, Hydrological system.

A mechanism for multidisciplinary dialogue: the memory & … series.

PubMed

Multhaup, Kristi S; Denham, Scott; Kelly, Hilton; Lom, Barbara

2011-01-01

Neuroscientists have long explored the mechanisms of memory from molecular, physiological, cognitive, and social perspectives. Scholars from other disciplines such as history, sociology, literature, and cultural studies, that do not traditionally cross-pollinate ideas with neuroscientists, also study memory from a variety of angles. In this article, we describe the founding of a multidisciplinary discussion series in which faculty and staff from the arts, humanities, social sciences, and natural sciences come together to explain how memory is integral to their scholarship and teaching. After panelists from different disciplines present opening comments, the floor is open for discussion with the audience that includes students, staff, and community members, as well as other faculty. Each year the series is anchored by a keynote address by an eminent scholar engaged in cross-disciplinary memory research. We outline the benefits of such thematic discussion series, highlighting the synchrony with the academy's increasing focus on interdisciplinarity, and on the need to train scholars to speak clearly about their work beyond their own disciplinary boundaries. More specifically, we focus on the need to train scientists to communicate with non-scientists. We have experienced success with this series and believe that the format could be adapted to a wide range of issues that cross disciplines (e.g., development, language, music, environmental studies).

A Mechanism for Multidisciplinary Dialogue: The Memory & … Series

PubMed Central

Multhaup, Kristi S.; Denham, Scott; Kelly, Hilton; Lom, Barbara

2011-01-01

Neuroscientists have long explored the mechanisms of memory from molecular, physiological, cognitive, and social perspectives. Scholars from other disciplines such as history, sociology, literature, and cultural studies, that do not traditionally cross-pollinate ideas with neuroscientists, also study memory from a variety of angles. In this article, we describe the founding of a multidisciplinary discussion series in which faculty and staff from the arts, humanities, social sciences, and natural sciences come together to explain how memory is integral to their scholarship and teaching. After panelists from different disciplines present opening comments, the floor is open for discussion with the audience that includes students, staff, and community members, as well as other faculty. Each year the series is anchored by a keynote address by an eminent scholar engaged in cross-disciplinary memory research. We outline the benefits of such thematic discussion series, highlighting the synchrony with the academy’s increasing focus on interdisciplinarity, and on the need to train scholars to speak clearly about their work beyond their own disciplinary boundaries. More specifically, we focus on the need to train scientists to communicate with non-scientists. We have experienced success with this series and believe that the format could be adapted to a wide range of issues that cross disciplines (e.g., development, language, music, environmental studies). PMID:23626499

Working memory for braille is shaped by experience

PubMed Central

Scherzer, Peter; Viau, Robert; Voss, Patrice; Lepore, Franco

2011-01-01

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. PMID:21655448

Gating of memory encoding of time-delayed cross-frequency MEG networks revealed by graph filtration based on persistent homology

PubMed Central

Hahm, Jarang; Lee, Hyekyoung; Park, Hyojin; Kang, Eunjoo; Kim, Yu Kyeong; Chung, Chun Kee; Kang, Hyejin; Lee, Dong Soo

2017-01-01

To explain gating of memory encoding, magnetoencephalography (MEG) was analyzed over multi-regional network of negative correlations between alpha band power during cue (cue-alpha) and gamma band power during item presentation (item-gamma) in Remember (R) and No-remember (NR) condition. Persistent homology with graph filtration on alpha-gamma correlation disclosed topological invariants to explain memory gating. Instruction compliance (R-hits minus NR-hits) was significantly related to negative coupling between the left superior occipital (cue-alpha) and the left dorsolateral superior frontal gyri (item-gamma) on permutation test, where the coupling was stronger in R than NR. In good memory performers (R-hits minus false alarm), the coupling was stronger in R than NR between the right posterior cingulate (cue-alpha) and the left fusiform gyri (item-gamma). Gating of memory encoding was dictated by inter-regional negative alpha-gamma coupling. Our graph filtration over MEG network revealed these inter-regional time-delayed cross-frequency connectivity serve gating of memory encoding. PMID:28169281

Endogenous Memory CD8 T Cells Directly Mediate Cardiac Allograft Rejection

PubMed Central

Su, C. A.; Iida, S.; Abe, T.; Fairchild, R. L.

2014-01-01

Differences in levels of environmentally induced memory T cells that cross-react with donor MHC molecules are postulated to account for the efficacy of allograft tolerance inducing strategies in rodents versus their failure in nonhuman primates and human transplant patients. Strategies to study the impact of donor-reactive memory T cells on allografts in rodents have relied on the pre-transplant induction of memory T cells cross-reactive with donor allogeneic MHC molecules through recipient viral infection, priming directly with donor antigen, or adoptive transfer of donor-antigen primed memory T cells. Each approach accelerates allograft rejection and confers resistance to tolerance induction, but also biases the T cell repertoire to strong donor-reactivity. The ability of endogenous memory T cells within unprimed mice to directly reject an allograft is unknown. Here we show a direct association between increased duration of cold ischemic allograft storage and numbers and enhanced functions of early graft infiltrating endogenous CD8 memory T cells. These T cells directly mediate rejection of allografts subjected to prolonged ischemia and this rejection is resistant to costimulatory blockade. These findings recapitulate the clinically significant impact of endogenous memory T cells with donor reactivity in a mouse transplant model in the absence of prior recipient priming. PMID:24502272

Cross-modal versus within-modal recall: differences in behavioral and brain responses.

PubMed

Butler, Andrew J; James, Karin H

2011-10-31

Although human experience is multisensory in nature, previous research has focused predominantly on memory for unisensory as opposed to multisensory information. In this work, we sought to investigate behavioral and neural differences between the cued recall of cross-modal audiovisual associations versus within-modal visual or auditory associations. Participants were presented with cue-target associations comprised of pairs of nonsense objects, pairs of nonsense sounds, objects paired with sounds, and sounds paired with objects. Subsequently, they were required to recall the modality of the target given the cue while behavioral accuracy, reaction time, and blood oxygenation level dependent (BOLD) activation were measured. Successful within-modal recall was associated with modality-specific reactivation in primary perceptual regions, and was more accurate than cross-modal retrieval. When auditory targets were correctly or incorrectly recalled using a cross-modal visual cue, there was re-activation in auditory association cortex, and recall of information from cross-modal associations activated the hippocampus to a greater degree than within-modal associations. Findings support theories that propose an overlap between regions active during perception and memory, and show that behavioral and neural differences exist between within- and cross-modal associations. Overall the current study highlights the importance of the role of multisensory information in memory. Copyright © 2011 Elsevier B.V. All rights reserved.

Cross-modal activation of auditory regions during visuo-spatial working memory in early deafness.

PubMed

Ding, Hao; Qin, Wen; Liang, Meng; Ming, Dong; Wan, Baikun; Li, Qiang; Yu, Chunshui

2015-09-01

Early deafness can reshape deprived auditory regions to enable the processing of signals from the remaining intact sensory modalities. Cross-modal activation has been observed in auditory regions during non-auditory tasks in early deaf subjects. In hearing subjects, visual working memory can evoke activation of the visual cortex, which further contributes to behavioural performance. In early deaf subjects, however, whether and how auditory regions participate in visual working memory remains unclear. We hypothesized that auditory regions may be involved in visual working memory processing and activation of auditory regions may contribute to the superior behavioural performance of early deaf subjects. In this study, 41 early deaf subjects (22 females and 19 males, age range: 20-26 years, age of onset of deafness < 2 years) and 40 age- and gender-matched hearing controls underwent functional magnetic resonance imaging during a visuo-spatial delayed recognition task that consisted of encoding, maintenance and recognition stages. The early deaf subjects exhibited faster reaction times on the spatial working memory task than did the hearing controls. Compared with hearing controls, deaf subjects exhibited increased activation in the superior temporal gyrus bilaterally during the recognition stage. This increased activation amplitude predicted faster and more accurate working memory performance in deaf subjects. Deaf subjects also had increased activation in the superior temporal gyrus bilaterally during the maintenance stage and in the right superior temporal gyrus during the encoding stage. These increased activation amplitude also predicted faster reaction times on the spatial working memory task in deaf subjects. These findings suggest that cross-modal plasticity occurs in auditory association areas in early deaf subjects. These areas are involved in visuo-spatial working memory. Furthermore, amplitudes of cross-modal activation during the maintenance stage were positively correlated with the age of onset of hearing aid use and were negatively correlated with the percentage of lifetime hearing aid use in deaf subjects. These findings suggest that earlier and longer hearing aid use may inhibit cross-modal reorganization in early deaf subjects. Granger causality analysis revealed that, compared to the hearing controls, the deaf subjects had an enhanced net causal flow from the frontal eye field to the superior temporal gyrus. These findings indicate that a top-down mechanism may better account for the cross-modal activation of auditory regions in early deaf subjects.See MacSweeney and Cardin (doi:10/1093/awv197) for a scientific commentary on this article. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development of Deployable Elastic Composite Shape Memory Alloy Reinforced (DECSMAR) Structures

DTIC Science & Technology

2006-05-01

battens nest. To mitigate the compromise of deployed performance due to the hinge cross-section, Nitinol SMA wires can be embedded in the composite...proportional limit by slip or conventional plastic deformation. As a logistics example, the particular Nitinol alloy used for proto-typing has...Memory Alloys,” Johnson Matthey, 2004. 10Cross, WB, Kariotis, AH, & Stimler, FJ, “ Nitinol Characterization Study,” NASA CR-1433, 1970. 11Proft, JL

Virus-specific CD4+ memory phenotype T cells are abundant in unexposed adults

PubMed Central

Su, Laura F.; Kidd, Brian A.; Han, Arnold; Kotzin, Jonathan J.; Davis, Mark M.

2013-01-01

While T cell memory is generally thought to require direct antigen exposure, we find an abundance of memory phenotype cells (20–90%, averaging over 50%) of CD4+ T cells specific for viral antigens in adults that have never been infected. These cells express the appropriate memory markers and genes, rapidly produce cytokines, and have clonally expanded. This contrasts with newborns where the same T cell receptor (TCR) specificities are almost entirely naïve, which may explain the vulnerability of young children to infections. One mechanism for this phenomenon is TCR cross-reactivity to environmental antigens and in support of this we find extensive cross-recognition by HIV-1 and influenza-reactive T lymphocytes to other microbial peptides and the expansion of one of these following influenza vaccination. Thus the presence of these memory phenotype T cells has significant implications for immunity to novel pathogens, child and adult health, and the influence of pathogen-rich versus hygienic environments. PMID:23395677

Rapid shape memory TEMPO-oxidized cellulose nanofibers/polyacrylamide/gelatin hydrogels with enhanced mechanical strength.

PubMed

Li, Nan; Chen, Wei; Chen, Guangxue; Tian, Junfei

2017-09-01

TEMPO-oxidized cellulose nanofibers/polyacrylamide/gelatin shape memory hydrogels were successfully fabricated through a facile in-situ free-radical polymerization method, and double network was formed by chemically cross-linked polyacrylamide (PAM) network and physically cross-linked gelatin network. TEMPO-oxidized cellulose nanofibers (TOCNs) were introduced to improve the mechanical properties of the hydrogel. The structure, shape memory behaviors and mechanical properties of the resulting composite gels with varied gel compositions were investigated. The results obtained from those different studies revealed that TOCNs, gelatin, and PAM could mix with each other homogeneously. Due to the thermoreversible nature of the gelatin network, the composite hydrogels exhibited attractive thermo-induced shape memory properties. In addition, good mechanical properties (strength >200kPa, strain >650%) were achieved. Such composite hydrogels with good shape memory behavior and enhanced mechanical strength would be an attractive candidate for a wide variety of applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Advanced Motor-Controller Development.

DTIC Science & Technology

1983-06-22

OUTPUTS: 16 BIT PROE:UCT IN ACCA , FiCC:B Oi:t2 -* 0011: 0172 B:7 .04E SIFY STA A MCAN:,* SF,-’E MULTIPLICAND 001t4 0175 iF CLF: A INIT RESUI_I_T AOll5...OL-:t41) 04: ELSE ACCA IS UNC:HANGED 0-142 01SF ::,A 0CI CLAMP 0’Fi A #0 TEST SIGN OF A C0It 0l91 E’E: fBM I C.LIPI EBRFNCH IF NEG 01t4 4 : : 001,15 19...ELSE S.:ET ACCA =-ACCB:1B TQJ5. 01 .’ NEG B .ESTOPE ACCE: 01155 C. l1’-9 E -9 PTI RETUR’N Al? I .9~~ _________ . .... ... | |- - - - . . rjOt :E

The impact of path crossing on visuo-spatial serial memory: encoding or rehearsal effect?

PubMed

Parmentier, Fabrice B R; Andrés, Pilar

2006-11-01

The determinants of visuo-spatial serial memory have been the object of little research, despite early evidence that not all sequences are equally remembered. Recently, empirical evidence was reported indicating that the complexity of the path formed by the to-be-remembered locations impacted on recall performance, defined for example by the presence of crossings in the path formed by successive locations (Parmentier, Elford, & Maybery, 2005). In this study, we examined whether this effect reflects rehearsal or encoding processes. We examined the effect of a retention interval and spatial interference on the ordered recall of spatial sequences with and without path crossings. Path crossings decreased recall performance, as did a retention interval. In line with the encoding hypothesis, but in contrast with the rehearsal hypothesis, the effect of crossing was not affected by the retention interval nor by tapping. The possible nature of the impact of path crossing on encoding mechanisms is discussed.

Triple-Shape Memory Polymers Based on Self-Complementary Hydrogen Bonding

PubMed Central

Ware, Taylor; Hearon, Keith; Lonnecker, Alexander; Wooley, Karen L.; Maitland, Duncan J.; Voit, Walter

2012-01-01

Triple shape memory polymers (TSMPs) are a growing subset of a class of smart materials known as shape memory polymers, which are capable of changing shape and stiffness in response to a stimulus. A TSMP can change shapes twice and can fix two metastable shapes in addition to its permanent shape. In this work, a novel TSMP system comprised of both permanent covalent cross-links and supramolecular hydrogen bonding cross-links has been synthesized via a one-pot method. Triple shape properties arise from the combination of the glass transition of (meth)acrylate copolymers and the dissociation of self-complementary hydrogen bonding moieties, enabling broad and independent control of both glass transition temperature (Tg) and cross-link density. Specifically, ureidopyrimidone methacrylate and a novel monomer, ureidopyrimidone acrylate, were copolymerized with various alkyl acrylates and bisphenol A ethoxylate diacrylate. Control of Tg from 0 to 60 °C is demonstrated: concentration of hydrogen bonding moieties is varied from 0 to 40 wt %; concentration of the diacrylate is varied from 0 to 30 wt %. Toughness ranges from 0.06 to 0.14 MPa and is found to peak near 20 wt % of the supramolecular cross-linker. A widely tunable class of amorphous triple-shape memory polymers has been developed and characterized through dynamic and quasi-static thermomechanical testing to gain insights into the dynamics of supramolecular networks. PMID:22287811

Heavy Ion Irradiation Fluence Dependence for Single-Event Upsets of NAND Flash Memory

NASA Technical Reports Server (NTRS)

Chen, Dakai; Wilcox, Edward; Ladbury, Raymond; Kim, Hak; Phan, Anthony; Seidleck, Christina; LaBel, Kenneth

2016-01-01

We investigated the single-event effect (SEE) susceptibility of the Micron 16 nm NAND flash, and found the single-event upset (SEU) cross section varied inversely with fluence. The SEU cross section decreased with increasing fluence. We attribute the effect to the variable upset sensitivities of the memory cells. The current test standards and procedures assume that SEU follow a Poisson process and do not take into account the variability in the error rate with fluence. Therefore, heavy ion irradiation of devices with variable upset sensitivity distribution using typical fluence levels may underestimate the cross section and on-orbit event rate.

Controlled Shape Memory Behavior of a Smectic Main-Chain Liquid Crystalline Elastomer

DOE PAGES

Li, Yuzhan; Pruitt, Cole; Rios, Orlando; ...

2015-04-10

Here, we describe how a smectic main-chain liquid crystalline elastomer (LCE), with controlled shape memory behavior, is synthesized by polymerizing a biphenyl-based epoxy monomer with an aliphatic carboxylic acid curing agent. Microstructures of the LCEs, including their liquid crystallinity and cross-linking density, are modified by adjusting the stoichiometric ratio of the reactants to tailor the thermomechanical properties and shape memory behavior of the material. Thermal and liquid crystalline properties of the LCEs, characterized using differential scanning calorimetry and dynamic mechanical analysis, and structural analysis, performed using small-angle and wide-angle X-ray scattering, show that liquid crystallinity, cross-linking density, and network rigiditymore » are strongly affected by the stoichiometry of the curing reaction. With appropriate structural modifications it is possible to tune the thermal, dynamic mechanical, and thermomechanical properties as well as the shape memory and thermal degradation behavior of LCEs.« less

Controlled Shape Memory Behavior of a Smectic Main-Chain Liquid Crystalline Elastomer

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

Li, Yuzhan; Pruitt, Cole; Rios, Orlando

Here, we describe how a smectic main-chain liquid crystalline elastomer (LCE), with controlled shape memory behavior, is synthesized by polymerizing a biphenyl-based epoxy monomer with an aliphatic carboxylic acid curing agent. Microstructures of the LCEs, including their liquid crystallinity and cross-linking density, are modified by adjusting the stoichiometric ratio of the reactants to tailor the thermomechanical properties and shape memory behavior of the material. Thermal and liquid crystalline properties of the LCEs, characterized using differential scanning calorimetry and dynamic mechanical analysis, and structural analysis, performed using small-angle and wide-angle X-ray scattering, show that liquid crystallinity, cross-linking density, and network rigiditymore » are strongly affected by the stoichiometry of the curing reaction. With appropriate structural modifications it is possible to tune the thermal, dynamic mechanical, and thermomechanical properties as well as the shape memory and thermal degradation behavior of LCEs.« less

A Longitudinal Study of Memory Advantages in Bilinguals

PubMed Central

Ljungberg, Jessica K.; Hansson, Patrik; Andrés, Pilar; Josefsson, Maria; Nilsson, Lars-Göran

2013-01-01

Typically, studies of cognitive advantages in bilinguals have been conducted previously by using executive and inhibitory tasks (e.g. Simon task) and applying cross-sectional designs. This study longitudinally investigated bilingual advantages on episodic memory recall, verbal letter and categorical fluency during the trajectory of life. Monolingual and bilingual participants (n = 178) between 35–70 years at baseline were drawn from the Betula Prospective Cohort Study of aging, memory, and health. Results showed that bilinguals outperformed monolinguals at the first testing session and across time both in episodic memory recall and in letter fluency. No interaction with age was found indicating that the rate of change across ages was similar for bilinguals and monolinguals. As predicted and in line with studies applying cross-sectional designs, no advantages associated with bilingualism were found in the categorical fluency task. The results are discussed in the light of successful aging. PMID:24023803

Ego Depletion Does Not Interfere With Working Memory Performance.

PubMed

Singh, Ranjit K; Göritz, Anja S

2018-01-01

Ego depletion happens if exerting self-control reduces a person's capacity to subsequently control themselves. Previous research has suggested that ego depletion not only interferes with subsequent self-control but also with working memory. However, recent meta-analytical evidence casts doubt onto this. The present study tackles the question if ego depletion does interfere with working memory performance. We induced ego depletion in two ways: using an e-crossing task and using a Stroop task. We then measured working memory performance using the letter-number sequencing task. There was no evidence of ego depletion interfering with working memory performance. Several aspects of our study render this null finding highly robust. We had a large and heterogeneous sample of N = 1,385, which provided sufficient power. We deployed established depletion tasks from two task families (e-crossing task and Stroop), thus making it less likely that the null finding is due to a specific depletion paradigm. We derived several performance scores from the working memory task and ran different analyses to maximize the chances of finding an effect. Lastly, we controlled for two potential moderators, the implicit theories about willpower and dispositional self-control capacity, to ensure that a possible effect on working memory is not obscured by an interaction effect. In sum, this experiment strengthens the position that ego depletion works but does not affect working memory performance.

Ego Depletion Does Not Interfere With Working Memory Performance

PubMed Central

Singh, Ranjit K.; Göritz, Anja S.

2018-01-01

Ego depletion happens if exerting self-control reduces a person’s capacity to subsequently control themselves. Previous research has suggested that ego depletion not only interferes with subsequent self-control but also with working memory. However, recent meta-analytical evidence casts doubt onto this. The present study tackles the question if ego depletion does interfere with working memory performance. We induced ego depletion in two ways: using an e-crossing task and using a Stroop task. We then measured working memory performance using the letter-number sequencing task. There was no evidence of ego depletion interfering with working memory performance. Several aspects of our study render this null finding highly robust. We had a large and heterogeneous sample of N = 1,385, which provided sufficient power. We deployed established depletion tasks from two task families (e-crossing task and Stroop), thus making it less likely that the null finding is due to a specific depletion paradigm. We derived several performance scores from the working memory task and ran different analyses to maximize the chances of finding an effect. Lastly, we controlled for two potential moderators, the implicit theories about willpower and dispositional self-control capacity, to ensure that a possible effect on working memory is not obscured by an interaction effect. In sum, this experiment strengthens the position that ego depletion works but does not affect working memory performance. PMID:29706923

Cross-cultural variation of memory colors of familiar objects.

PubMed

Smet, Kevin A G; Lin, Yandan; Nagy, Balázs V; Németh, Zoltan; Duque-Chica, Gloria L; Quintero, Jesús M; Chen, Hung-Shing; Luo, Ronnier M; Safi, Mahdi; Hanselaer, Peter

2014-12-29

The effect of cross-regional or cross-cultural differences on color appearance ratings and memory colors of familiar objects was investigated in seven different countries/regions - Belgium, Hungary, Brazil, Colombia, Taiwan, China and Iran. In each region the familiar objects were presented on a calibrated monitor in over 100 different colors to a test panel of observers that were asked to rate the similarity of the presented object color with respect to what they thought the object looks like in reality (memory color). For each object and region the mean observer ratings were modeled by a bivariate Gaussian function. A statistical analysis showed significant (p < 0.001) differences between the region average observers and the global average observer obtained by pooling the data from all regions. However, the effect size of geographical region or culture was found to be small. In fact, the differences between the region average observers and the global average observer were found to of the same magnitude or smaller than the typical within region inter-observer variability. Thus, although statistical differences in color appearance ratings and memory between regions were found, regional impact is not likely to be of practical importance.

One bout of open skill exercise improves cross-modal perception and immediate memory in healthy older adults who habitually exercise.

PubMed

O'Brien, Jessica; Ottoboni, Giovanni; Tessari, Alessia; Setti, Annalisa

2017-01-01

One single bout of exercise can be associated with positive effects on cognition, due to physiological changes associated with muscular activity, increased arousal, and training of cognitive skills during exercise. While the positive effects of life-long physical activity on cognitive ageing are well demonstrated, it is not well established whether one bout of exercise is sufficient to register such benefits in older adults. The aim of this study was to test the effect of one bout of exercise on two cognitive processes essential to daily life and known to decline with ageing: audio-visual perception and immediate memory. Fifty-eight older adults took part in a quasi-experimental design study and were divided into three groups based on their habitual activity (open skill exercise (mean age = 69.65, SD = 5.64), closed skill exercise, N = 18, 94% female; sedentary activity-control group, N = 21, 62% female). They were then tested before and after their activity (duration between 60 and 80 minutes). Results showed improvement in sensitivity in audio-visual perception in the open skill group and improvements in one of the measures of immediate memory in both exercise groups, after controlling for baseline differences including global cognition and health. These findings indicate that immediate benefits for cross-modal perception and memory can be obtained after open skill exercise. However, improvements after closed skill exercise may be limited to memory benefits. Perceptual benefits are likely to be associated with arousal, while memory benefits may be due to the training effects provided by task requirements during exercise. The respective role of qualitative and quantitative differences between these activities in terms of immediate cognitive benefits should be further investigated. Importantly, the present results present the first evidence for a modulation of cross-modal perception by exercise, providing a plausible avenue for rehabilitation of cross-modal perception deficits, which are emerging as a significant contributor to functional decline in ageing.

A Cross-Syndrome Study of the Differential Effects of Sleep on Declarative Memory Consolidation in Children with Neurodevelopmental Disorders

ERIC Educational Resources Information Center

Ashworth, Anna; Hill, Catherine M.; Karmiloff-Smith, Annette; Dimitriou, Dagmara

2017-01-01

Sleep plays an active role in memory consolidation. Because children with Down syndrome (DS) and Williams syndrome (WS) experience significant problems with sleep and also with learning, we predicted that sleep-dependent memory consolidation would be impaired in these children when compared to typically developing (TD) children. This is the first…

Serum high-density lipoprotein is associated with better cognitive function in a cross-sectional study of aging women.

PubMed

Bates, Kristyn A; Sohrabi, Hamid R; Rainey-Smith, Stephanie R; Weinborn, Michael; Bucks, Romola S; Rodrigues, Mark; Beilby, John; Howard, Matthew; Taddei, Kevin; Martins, Georgia; Paton, Athena; Shah, Tejal; Dhaliwal, Satvinder S; Foster, Jonathan K; Martins, Ian J; Lautenschlager, Nicola T; Mastaglia, Frank L; Gandy, Samuel E; Martins, Ralph N

2017-03-01

Purpose/Aim of the study: Poor cardiovascular health, including obesity and altered lipid profiles at mid-life, are linked to increased risk of Alzheimer's disease (AD). The biological mechanisms linking cardiovascular health and cognitive function are unclear though are likely to be multifactorial. This study examined the association between various lipoproteins and cognitive functioning in ageing women. We investigated the relationship between readily available biomarkers (i.e. serum lipoprotein) and cognitive decline in domains associated with increased risk of AD (e.g. episodic verbal memory performance and subjective memory complaint). We report cross-sectional data investigating the relationship between serum total cholesterol, triglycerides, high-density lipoprotein (HDL-C) and low-density lipoprotein with verbal memory and learning ability in 130 women with and without memory complaints (n = 71 and 59, respectively) drawn from a study investigating cognitively healthy Western Australians (average age 62.5 years old). After statistical modelling that controlled for the effects of age, depression and apolipoprotein E genotype, HDL-C was significantly associated with better verbal learning and memory performance, specifically short and long delay-free recalls (F = 3.062; p < .05 and F = 3.2670; p < .05, respectively). Our cross-sectional findings suggest that the positive effect of HDL-C on verbal memory may be present much earlier than previously reported and provide further support for the role of HDL-C in healthy brain ageing. Further exploration of the protective effect of HDL-C on cognitive function in ageing is warranted through follow-up, longitudinal studies.

36 CFR 1501.1 - Cross reference to National Park Service regulations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Cross reference to National... NATIONAL MEMORIAL TRUST GENERAL PROVISIONS § 1501.1 Cross reference to National Park Service regulations... (the Trust) adopts by cross reference the provisions of the National Park Service in 36 CFR chapter I...

36 CFR 1501.1 - Cross reference to National Park Service regulations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Cross reference to National... NATIONAL MEMORIAL TRUST GENERAL PROVISIONS § 1501.1 Cross reference to National Park Service regulations... (the Trust) adopts by cross reference the provisions of the National Park Service in 36 CFR chapter I...

Deficits in working memory, reading comprehension and arithmetic skills in children with mouth breathing syndrome: analytical cross-sectional study.

PubMed

Kuroishi, Rita Cristina Sadako; Garcia, Ricardo Basso; Valera, Fabiana Cardoso Pereira; Anselmo-Lima, Wilma Terezinha; Fukuda, Marisa Tomoe Hebihara

2015-01-01

Mouth breathing syndrome is very common among school-age children, and it is possibly related to learning difficulties and low academic achievement. In this study, we investigated working memory, reading comprehension and arithmetic skills in children with nasal and mouth breathing. Analytical cross-sectional study with control group conducted in a public university hospital. 42 children (mean age = 8.7 years) who had been identified as mouth breathers were compared with a control group (mean age = 8.4 years) matched for age and schooling. All the participants underwent a clinical interview, tone audiometry, otorhinolaryngological evaluation and cognitive assessment of phonological working memory (numbers and pseudowords), reading comprehension and arithmetic skills. Children with mouth breathing had poorer performance than controls, regarding reading comprehension (P = 0.006), arithmetic (P = 0.025) and working memory for pseudowords (P = 0.002), but not for numbers (P = 0.76). Children with mouth breathing have low academic achievement and poorer phonological working memory than controls. Teachers and healthcare professionals should be aware of the association of mouth breathing with children's physical and cognitive health.

When Do Visual and Verbal Memories Conflict?: The Importance of Working-Memory Load and Retrieval

ERIC Educational Resources Information Center

Morey, Candice C.; Cowan, Nelson

2005-01-01

Examinations of interference between verbal and visual materials in working memory have produced mixed results. If there is a central form of storage (e.g., the focus of attention; N. Cowan, 2001), then cross-domain interference should be obtained. The authors examined this question with a visual-array comparison task (S. J. Luck & E. K. Vogel,…

Cross-Cultural Beliefs about Memory and Aging for Self and Others: South Korea and Canada

ERIC Educational Resources Information Center

Ryan, Ellen Bouchard; Jin, Young-Sun; Anas, Ann P.

2009-01-01

Young adults in Canada (N = 161) and South Korea (N = 165) rated either themselves or typical others at target ages 25, 45, and 65 years. In both countries, poorer memory was anticipated with each increase in age on all 3 memory belief factors: capacity, change, and locus. Both groups demonstrated a self-protective bias about age-related decline,…

Post polymerization cure shape memory polymers

DOEpatents

Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

2017-01-10

This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

Post polymerization cure shape memory polymers

DOEpatents

Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

2014-11-11

This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

The Development of Memory Efficiency and Value-Directed Remembering across the Life Span: A Cross-Sectional Study of Memory and Selectivity

ERIC Educational Resources Information Center

Castel, Alan D.; Humphreys, Kathryn L.; Lee, Steve S.; Galvan, Adriana; Balota, David A.; McCabe, David P.

2011-01-01

Although attentional control and memory change considerably across the life span, no research has examined how the ability to strategically remember important information (i.e., value-directed remembering) changes from childhood to old age. The present study examined this in different age groups across the life span (N = 320, 5-96 years old). A…

The Association of Perceived Memory Loss with Osteoarthritis and Related Joint Pain in a Large Appalachian Population.

PubMed

Innes, Kim E; Sambamoorthi, Usha

2017-05-19

Previous studies have documented memory impairment in several chronic pain syndromes. However, the potential link between memory loss and osteoarthritis (OA), the second most common cause of chronic pain, remains little explored. In this cross-sectional study, we examine the association of perceived memory loss to OA and assess the potential mediating influence of sleep and mood disturbance in a large Appalachian population.  Cross-sectional.  US Ohio Valley.  A total of 21,982 Appalachian adults age 40 years or older drawn from the C8 Health Project (N = 19,004 adults without and 2,478 adults with OA). All participants completed a comprehensive health survey between 2005 and 2006. Medical history, including physician diagnosis of OA, lifestyle factors, short- and long-term memory loss, sleep quality, and mood were assessed via self-report.  After adjustment for demographic, lifestyle, health-related, and other factors, participants with OA were almost three times as likely to report frequent memory loss (adjusted odds ratios [ORs] for short- and long-term memory loss, respectively = 2.7, 95% confidence interval [CI] = 2.2-3.3, and 2.6, 95% CI = 2.0-3.3). The magnitude of these associations increased significantly with rising frequency of reported joint pain (adjusted OR for OA with frequent joint pain vs no OA = 3.3, 95% CI = 2.6-4.1, P trend  < 0.00001). Including measures of mood and sleep impairment attenuated but did not eliminate these associations (ORs for any memory loss = 2.0, 95% CI = 1.6-2.4, and 2.1, 95% CI = 1.7-2.8, adjusted for sleep and mood impairment, respectively; OR = 1.8, 95% CI = 1.4-2.2, adjusted for both factors).  In this large cross-sectional study, OA and related joint pain were strongly associated with perceived memory loss; these associations may be partially mediated by sleep and mood disturbance. © 2017 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Cross-Generational Storytelling

ERIC Educational Resources Information Center

Smith, Cindy; Thurston, Judy Kay

2007-01-01

What happens when you combine senior citizens, pre-service art teachers, and elementary students? Cross-generational connections based on sharing memories, ideas, skills, laughter, tears, and creativity. The authors describe the cross-generational book exchange project. This project was initiated when a group of Central Michigan University (CMU)…

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.

Broad cross-reactive T cell receptor repertoires recognizing dissimilar Epstein-Barr and influenza A virus epitopes

PubMed Central

Clute, Shalyn C.; Naumov, Yuri N.; Watkin, Levi B.; Aslan, Nuray; Sullivan, John L.; Thorley-Lawson, David A.; Luzuriaga, Katherine; Welsh, Raymond M.; Puzone, Roberto; Celada, Franco; Selin, Liisa K.

2013-01-01

Memory T cells cross-reactive with epitopes encoded by related or even unrelated viruses may alter the immune response and pathogenesis of infection by a process known as heterologous immunity. Because a challenge virus epitope may react with only a subset of the T cell repertoire in a cross-reactive epitope-specific memory pool, the vigorous cross-reactive response may be narrowly focused, or oligoclonal. We show here, by examining human T cell cross-reactivity between the HLA-A2-restricted influenza A virus-encoded M158-66 epitope (GILGFVFTL) and the dissimilar Epstein-Barr virus-encoded BMLF1280-288 epitope (GLCTLVAML), that under some conditions heterologous immunity can lead to a significant broadening rather than a narrowing of the T cell receptor repertoire. We suggest that dissimilar cross-reactive epitopes might generate a broad rather than narrow T cell repertoire if there is a lack of dominant high affinity clones, and this hypothesis is supported by computer simulation. PMID:21048112

The cross-race effect in face recognition memory by bicultural individuals.

PubMed

Marsh, Benjamin U; Pezdek, Kathy; Ozery, Daphna Hausman

2016-09-01

Social-cognitive models of the cross-race effect (CRE) generally specify that cross-race faces are automatically categorized as an out-group, and that different encoding processes are then applied to same-race and cross-race faces, resulting in better recognition memory for same-race faces. We examined whether cultural priming moderates the cognitive categorization of cross-race faces. In Experiment 1, monoracial Latino-Americans, considered to have a bicultural self, were primed to focus on either a Latino or American cultural self and then viewed Latino and White faces. Latino-Americans primed as Latino exhibited higher recognition accuracy (A') for Latino than White faces; those primed as American exhibited higher recognition accuracy for White than Latino faces. In Experiment 2, as predicted, prime condition did not moderate the CRE in European-Americans. These results suggest that for monoracial biculturals, priming either of their cultural identities influences the encoding processes applied to same- and cross-race faces, thereby moderating the CRE. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of cross-shaped Cu-nanowire resistive memory devices using a rapid, scalable, and designable inorganic-nanowire-digital-alignment technique (Conference Presentation)

NASA Astrophysics Data System (ADS)

Xu, Wentao; Lee, Yeongjun; Min, Sung-Yong; Park, Cheolmin; Lee, Tae-Woo

2016-09-01

Resistive random-access memory (RRAM) is a candidate next generation nonvolatile memory due to its high access speed, high density and ease of fabrication. Especially, cross-point-access allows cross-bar arrays that lead to high-density cells in a two-dimensional planar structure. Use of such designs could be compatible with the aggressive scaling down of memory devices, but existing methods such as optical or e-beam lithographic approaches are too complicated. One-dimensional inorganic nanowires (i-NWs) are regarded as ideal components of nanoelectronics to circumvent the limitations of conventional lithographic approaches. However, post-growth alignment of these i-NWs precisely on a large area with individual control is still a difficult challenge. Here, we report a simple, inexpensive, and rapid method to fabricate two-dimensional arrays of perpendicularly-aligned, individually-conductive Cu-NWs with a nanometer-scale CuxO layer sandwiched at each cross point, by using an inorganic-nanowire-digital-alignment technique (INDAT) and a one-step reduction process. In this approach, the oxide layer is self-formed and patterned, so conventional deposition and lithography are not necessary. INDAT eliminates the difficulties of alignment and scalable fabrication that are encountered when using currently-available techniques that use inorganic nanowires. This simple process facilitates fabrication of cross-point nonvolatile memristor arrays. Fabricated arrays had reproducible resistive switching behavior, high on/off current ratio (Ion/Ioff) 10 6 and extensive cycling endurance. This is the first report of memristors with the resistive switching oxide layer self-formed, self-patterned and self-positioned; we envision that the new features of the technique will provide great opportunities for future nano-electronic circuits.

Development of verbal short-term memory and working memory in children with epilepsy: Developmental delay and impact of time-related variables. A cross-sectional study.

PubMed

van Iterson, Loretta; de Jong, Peter F

2018-01-01

While short-term memory (STM) and working memory (WM) are understood as being crucial for learning, and children with epilepsy often experience learning difficulties, little is known about the age-related development of memory span tasks in children with epilepsy. Short-term memory and WM, operationalized as digit span forwards (DSF) or digit span backwards (DSB), respectively, were studied. Participants were 314 children with epilepsy and 327 typically developing children in ages between 5 and 15years and full scale intelligence quotient (FS-IQ)≥75. Cross-sectional analyses of the data were done with analyses of variance and analyses of covariance ((M)ANCOVAs) and generalized linear analyses. The analyses revealed that STM problems in epilepsy were mediated by age-related gains in WM as well as by differences in IQ. Working memory developed at a quick pace in the younger children, the pace slowed down to some extent in the later primary school years and resumed again later on. Working memory problems prevailed in epilepsy, independent of IQ and development of STM. Timing of the epilepsy in terms of age at onset and duration determined memory development. The youngest children with epilepsy showed age-appropriate development in STM but were the most vulnerable in terms of WM development. Later in the course of the epilepsy, the WM problems of the young children attenuated. In later onset epilepsy, WM problems were smaller but persisted over time. Copyright © 2017 Elsevier Inc. All rights reserved.

Cross-cultural differences in item and background memory: examining the influence of emotional intensity and scene congruency.

PubMed

Mickley Steinmetz, Katherine R; Sturkie, Charlee M; Rochester, Nina M; Liu, Xiaodong; Gutchess, Angela H

2018-07-01

After viewing a scene, individuals differ in what they prioritise and remember. Culture may be one factor that influences scene memory, as Westerners have been shown to be more item-focused than Easterners (see Masuda, T., & Nisbett, R. E. (2001). Attending holistically versus analytically: Comparing the context sensitivity of Japanese and Americans. Journal of Personality and Social Psychology, 81, 922-934). However, cultures may differ in their sensitivity to scene incongruences and emotion processing, which may account for cross-cultural differences in scene memory. The current study uses hierarchical linear modeling (HLM) to examine scene memory while controlling for scene congruency and the perceived emotional intensity of the images. American and East Asian participants encoded pictures that included a positive, negative, or neutral item placed on a neutral background. After a 20-min delay, participants were shown the item and background separately along with similar and new items and backgrounds to assess memory specificity. Results indicated that even when congruency and emotional intensity were controlled, there was evidence that Americans had better item memory than East Asians. Incongruent scenes were better remembered than congruent scenes. However, this effect did not differ by culture. This suggests that Americans' item focus may result in memory changes that are robust despite variations in scene congruency and perceived emotion.

36 CFR § 1501.1 - Cross reference to National Park Service regulations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Cross reference to National... NATIONAL MEMORIAL TRUST GENERAL PROVISIONS § 1501.1 Cross reference to National Park Service regulations... (the Trust) adopts by cross reference the provisions of the National Park Service in 36 CFR chapter I...

Arbitrary and semantic associations in subjective memory impairment and amnestic mild cognitive impairment among Taiwanese individuals: A cross-sectional study.

PubMed

Chang, Hsin-Te; Chen, Ta-Fu; Cheng, Ting-Wen; Lai, Ya-Mei; Hua, Mau-Sun

2018-05-01

Researchers have recently proposed a preclinical stage of dementia of Alzheimer's type (DAT), referred to as subjective memory impairment (SMI), with the aim of developing methods for the early detection of DAT and subsequent intervention. It has been proposed that the objective memory functions of individuals with SMI are normal; however, arbitrary and semantic associations are both used to describe the processes of memory. No previous studies have investigated these processes among individuals with SMI. Cross-sectional analysis was used to compare the memory function of individuals with SMI, amnestic mild cognitive impairment (aMCI), or DAT. One hundred and eighty-three participants were recruited from the Memory Clinic of National Taiwan University Hospital and communities in northern Taiwan, including individuals with no memory complaints (HC, n = 30) and individuals with SMI (n = 61), aMCI-single domain (n = 24), aMCI-multiple domain (n = 33), or DAT (n = 35). The Word Sequence Learning Test (WSLT) was used to assess the formation of arbitrary associations and the Logical Memory subtest of the Wechsler Memory Scale-Third Edition was used to assess the formation of semantic associations. Compared to the HC group, the SMI group performed poorly only on the WSLT, whereas the other groups performed poorly on both of the memory tasks. This study demonstrated that SMI individuals tend to perform poorly in the formation of arbitrary associations. Our findings suggest that tasks requiring arbitrary associations may provide greater sensitivity in the detection cognitive changes associated with preclinical DAT. Copyright © 2017. Published by Elsevier B.V.

Comparative Associations of Working Memory and Pain Catastrophizing With Chronic Low Back Pain Intensity.

PubMed

Simon, Corey B; Lentz, Trevor A; Bishop, Mark D; Riley, Joseph L; Fillingim, Roger B; George, Steven Z

2016-07-01

Because of its high global burden, determining biopsychosocial influences of chronic low back pain (CLBP) is a research priority. Psychological factors such as pain catastrophizing are well established. However, cognitive factors such as working memory warrant further investigation to be clinically useful. The purpose of this study was to determine how working memory and pain catastrophizing are associated with CLBP measures of daily pain intensity and movement-evoked pain intensity. This study was a cross-sectional analysis of individuals with ≥3 months of CLBP (n=60) compared with pain-free controls (n=30). Participants completed measures of working memory, pain catastrophizing, and daily pain intensity. Movement-evoked pain intensity was assessed using the Back Performance Scale. Outcome measures were compared between individuals with CLBP and those who were pain-free using nonparametric testing. Associations were determined using multivariate regression analyses. Participants with CLBP (mean age=47.7 years, 68% female) had lower working memory performance (P=.008) and higher pain catastrophizing (P<.001) compared with pain-free controls (mean age=47.6 years, 63% female). For individuals with CLBP, only working memory remained associated with daily pain intensity (R(2)=.07, standardized beta=-.308, P=.041) and movement-evoked pain intensity (R(2)=.14, standardized beta=-.502, P=.001) after accounting for age, sex, education, and interactions between pain catastrophizing and working memory. The cross-sectional design prevented prospective analysis. Findings also are not indicative of overall working memory (eg, spatial) or cognitive performance. Working memory demonstrated the strongest association with daily pain and movement-evoked pain intensity compared with (and after accounting for) established CLBP factors. Future research will elucidate the prognostic value of working memory on prevention and recovery of CLBP. © 2016 American Physical Therapy Association.

Comparative Associations of Working Memory and Pain Catastrophizing With Chronic Low Back Pain Intensity

PubMed Central

Lentz, Trevor A.; Bishop, Mark D.; Riley, Joseph L.; Fillingim, Roger B.; George, Steven Z.

2016-01-01

Background Because of its high global burden, determining biopsychosocial influences of chronic low back pain (CLBP) is a research priority. Psychological factors such as pain catastrophizing are well established. However, cognitive factors such as working memory warrant further investigation to be clinically useful. Objective The purpose of this study was to determine how working memory and pain catastrophizing are associated with CLBP measures of daily pain intensity and movement-evoked pain intensity. Design This study was a cross-sectional analysis of individuals with ≥3 months of CLBP (n=60) compared with pain-free controls (n=30). Method Participants completed measures of working memory, pain catastrophizing, and daily pain intensity. Movement-evoked pain intensity was assessed using the Back Performance Scale. Outcome measures were compared between individuals with CLBP and those who were pain-free using nonparametric testing. Associations were determined using multivariate regression analyses. Results Participants with CLBP (mean age=47.7 years, 68% female) had lower working memory performance (P=.008) and higher pain catastrophizing (P<.001) compared with pain-free controls (mean age=47.6 years, 63% female). For individuals with CLBP, only working memory remained associated with daily pain intensity (R2=.07, standardized beta=−.308, P=.041) and movement-evoked pain intensity (R2=.14, standardized beta=−.502, P=.001) after accounting for age, sex, education, and interactions between pain catastrophizing and working memory. Limitations The cross-sectional design prevented prospective analysis. Findings also are not indicative of overall working memory (eg, spatial) or cognitive performance. Conclusion Working memory demonstrated the strongest association with daily pain and movement-evoked pain intensity compared with (and after accounting for) established CLBP factors. Future research will elucidate the prognostic value of working memory on prevention and recovery of CLBP. PMID:26700272

Parietal control network activation during memory tasks may be associated with the co-occurrence of externally and internally directed cognition: A cross-function meta-analysis.

PubMed

Kim, Hongkeun

2018-03-15

Functional neuroimaging studies on episodic memory retrieval consistently indicated the activation of the precuneus (PCU), mid-cingulate cortex (MCC), and lateral intraparietal sulcus (latIPS) regions. Although studies typically interpreted these activations in terms of memory retrieval processes, resting-state functional connectivity data indicate that these regions are part of the frontoparietal control network, suggesting a more general, cross-functional role. In this regard, this study proposes a novel hypothesis which suggests that the parietal control network plays a strong role in accommodating the co-occurrence of externally directed cognition (EDC) and internally directed cognition (IDC), which are typically antagonistic to each other. To evaluate how well this dual cognitive processes hypothesis can account for parietal activation patterns during memory tasks, this study provides a cross-function meta-analysis involving 3 different memory paradigms, namely, retrieval success (hit > correct rejection), repetition enhancement (repeated > novel), and subsequent forgetting (forgotten > remembered). Common to these paradigms is that the target condition may involve both EDC (stimulus processing and motor responding) and IDC (intentional remembering, involuntary awareness of previous encounter, or task-unrelated thoughts) strongly, whereas the reference condition may involve EDC to a greater extent, but IDC to a lesser extent. Thus, the dual cognitive processes hypothesis predicts that each of these paradigms will activate similar, overlapping PCU, MCC, and latIPS regions. The results were fully consistent with the prediction, supporting the dual cognitive processes hypothesis. Evidence from relevant prior studies suggests that the dual cognitive processes hypothesis may also apply to non-memory domain tasks. Copyright © 2018 Elsevier B.V. All rights reserved.

Benefits of regular aerobic exercise for executive functioning in healthy populations.

PubMed

Guiney, Hayley; Machado, Liana

2013-02-01

Research suggests that regular aerobic exercise has the potential to improve executive functioning, even in healthy populations. The purpose of this review is to elucidate which components of executive functioning benefit from such exercise in healthy populations. In light of the developmental time course of executive functions, we consider separately children, young adults, and older adults. Data to date from studies of aging provide strong evidence of exercise-linked benefits related to task switching, selective attention, inhibition of prepotent responses, and working memory capacity; furthermore, cross-sectional fitness data suggest that working memory updating could potentially benefit as well. In young adults, working memory updating is the main executive function shown to benefit from regular exercise, but cross-sectional data further suggest that task-switching and post error performance may also benefit. In children, working memory capacity has been shown to benefit, and cross-sectional data suggest potential benefits for selective attention and inhibitory control. Although more research investigating exercise-related benefits for specific components of executive functioning is clearly needed in young adults and children, when considered across the age groups, ample evidence indicates that regular engagement in aerobic exercise can provide a simple means for healthy people to optimize a range of executive functions.

Deconstructing racial differences: the effects of quality of education and cerebrovascular risk factors.

PubMed

Carvalho, Janessa O; Tommet, Doug; Crane, Paul K; Thomas, Michael L; Claxton, Amy; Habeck, Christian; Manly, Jennifer J; Romero, Heather R

2015-07-01

To evaluate the effects of vascular conditions and education quality on cognition over time in White and African American (AA) older adults. We investigated cross-sectional and longitudinal racial differences in executive functioning (EF) and memory composites among Whites (n = 461) and AAs (n = 118) enrolled in a cohort study. We examined whether cerebrovascular risk factors and Shipley Vocabulary scores (a proxy for education quality) accounted for racial differences. On average, AAs had lower quality of education and more cerebrovascular risk factors including hypertension, diabetes, and obesity. AAs had lower mean EF and memory at baseline, but there were no group differences in rates of decline. Cross-sectional racial differences in EF and memory persisted after controlling for vascular disease, but disappeared when controlling for Shipley Vocabulary. Quality of education appears to be more important than cerebrovascular risk factors in explaining cross-sectional differences in memory and EF performance between White and AA older adults. Further investigation is needed regarding the relative contribution of education quality and cerebrovascular risk factors to cognitive decline among ethnically/racially diverse older adults. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Effect of lead and selenium on learning and memory ability in rats].

PubMed

Han, Xiaojie; Hu, Xiaoxia; Wei, Qing; Chen, Yilin; Yu, De'e; Hu, Qiansheng

2013-11-01

To study the effect of lead and (or) selenium on learning and memory ability in rats. SPF Wistar rats, after weaning, were divided into six groups, control group, Pb group (respectively Pb exposed), Se group (respectively Se added), Pb-Se group (added Se after Pb exposure), Se-Pb group (added Se before Pb exposure) and Pb + Se group (Pb and Se exposed simultaneously). After intervention for six weeks in rats, the spatial learning and memory of each group rats were measured by Morris water maze assay. Rats in Pb group had significantly longer latency, less site crossings, less percentage of time and distance spent in the target quadrant, and bigger first bearing compared with control group (P < 0.05). Rats in Pb and Se joint exposure groups had significantly shorter latency, more site crossings, less percentage of time and distance spent in the target quadrant, and smaller first bearing compared with Pb group (P < 0.05). There were no significant differences in the indexes of spatial learning and memory ability between the groups of lead and selenium joint exposure groups (P > 0.05). Lead damaged the ability of learning and memory in rats and organic selenium had protective effects on Pb-induced spatial learning and memory deficits in rats.

Cross-cultural differences for three visual memory tasks in Brazilian children.

PubMed

Santos, F H; Mello, C B; Bueno, O F A; Dellatolas, G

2005-10-01

Norms for three visual memory tasks, including Corsi's block tapping test and the BEM 144 complex figures and visual recognition, were developed for neuropsychological assessment in Brazilian children. The tasks were measured in 127 children ages 7 to 10 years from rural and urban areas of the States of São Paulo and Minas Gerais. Analysis indicated age-related but not sex-related differences. A cross-cultural effect was observed in relation to copying and recall of Complex pictures. Different performances between rural and urban children were noted.

Empirical Modeling Of Single-Event Upset

NASA Technical Reports Server (NTRS)

Zoutendyk, John A.; Smith, Lawrence S.; Soli, George A.; Thieberger, Peter; Smith, Stephen L.; Atwood, Gregory E.

1988-01-01

Experimental study presents examples of empirical modeling of single-event upset in negatively-doped-source/drain metal-oxide-semiconductor static random-access memory cells. Data supports adoption of simplified worst-case model in which cross sectionof SEU by ion above threshold energy equals area of memory cell.

Working memory: a developmental study of phonological recoding.

PubMed

Palmer, S

2000-05-01

A cross-sectional study using children aged 3 to 7 years and a cross-sequential study using children aged between 5 and 8 years showed that the development of phonological recoding in working memory was more complex than the simple dichotomous picture portrayed in the current literature. It appears that initially children use no strategy in recall, which is proposed to represent the level of automatic activation of representations in long-term memory and the storage capacity of the central executive. This is followed by a period in which a visual strategy prevails, followed by a period of dual visual-verbal coding before the adult-like strategy of verbal coding finally emerges. The results are discussed in terms of three working memory models (Baddeley, 1990; Engle, 1996; Logie, 1996) where strategy use is seen as the development of attentional processes and phonological recoding as the development of inhibitory mechanisms in the central executive to suppress the habitual response set of visual coding.

A water-responsive shape memory ionomer with permanent shape reconfiguration ability

NASA Astrophysics Data System (ADS)

Bai, Yongkang; Zhang, Jiwen; Tian, Ran; Chen, Xin

2018-04-01

In this work, a water-responsive shape memory ionomer with high toughness was fabricated by cross-linking hyaluronic acid sodium (HAS) and polyvinyl alcohol (PVA) through coordination interactions. The strong Fe3+-carboxyl (from HAS) coordination interactions served as main physical cross-linking points for the performance of water-responsive shape memory, which associated with the flexibility of PVA chain producing excellent mechanical properties of this ionomer. The optimized ionomer was not only able to recover to its original shape within just 22 s by exposing to water, but exhibited high tensile strength up to 35.4 MPa and 4 times higher tractility than the ionomer without PVA. Moreover, the ionomers can be repeatedly programed to various new permanent shapes on demand due to the reversible physical interactions, which still performed complete and fast geometric recovery under stimuli even after 4 cycles of reprograming with 3 different shapes. The excellent shape memory and strong mechanical behaviors make our ionomers significant and promising smart materials for variety of applications.

Suppression and Working Memory in Auditory Comprehension of L2 Narratives: Evidence from Cross-Modal Priming.

PubMed

Wu, Shiyu; Ma, Zheng

2016-10-01

Using a cross-modal priming task, the present study explores whether Chinese-English bilinguals process goal related information during auditory comprehension of English narratives like native speakers. Results indicate that English native speakers adopted both mechanisms of suppression and enhancement to modulate the activation of goals and keep track of the "causal path" in narrative events and that L1 speakers with higher working memory (WM) capacity are more skilled at attenuating interference. L2 speakers, however, experienced the phenomenon of "facilitation-without-inhibition." Their difficulty in suppressing irrelevant information was related to their performance in the test of working memory capacity. For the L2 group with greater working memory capacity, the effects of both enhancement and suppression were found. These findings are discussed in light of a landscape model of L2 text comprehension which highlights the need for WM to be incorporated into comprehensive models of L2 processing as well as theories of SLA.

Going global: the functions of autobiographical memory in cultural context.

PubMed

Alea, Nicole; Wang, Qi

2015-01-01

This special issue of Memory brings together research from around the globe, from Japanese, Chinese and East Indian cultures, to American and European societies, to the Caribbean, to Turkey and to Australia and New Zealand, which examines how and why people, from childhood to old age, remember the personal past in daily life. This journey highlights the important role of the cultural context in shaping the functional usages of autobiographical memory. We illuminate six major contributions of cross-cultural research to a broader and deeper understanding of the functions of autobiographical memory, and call attention to the filed that memory research must "go global."

Magnetic vortex racetrack memory

NASA Astrophysics Data System (ADS)

Geng, Liwei D.; Jin, Yongmei M.

2017-02-01

We report a new type of racetrack memory based on current-controlled movement of magnetic vortices in magnetic nanowires with rectangular cross-section and weak perpendicular anisotropy. Data are stored through the core polarity of vortices and each vortex carries a data bit. Besides high density, non-volatility, fast data access, and low power as offered by domain wall racetrack memory, magnetic vortex racetrack memory has additional advantages of no need for constrictions to define data bits, changeable information density, adjustable current magnitude for data propagation, and versatile means of ultrafast vortex core switching. By using micromagnetic simulations, current-controlled motion of magnetic vortices in cobalt nanowire is demonstrated for racetrack memory applications.

Music training improves verbal but not visual memory: cross-sectional and longitudinal explorations in children.

PubMed

Ho, Yim-Chi; Cheung, Mei-Chun; Chan, Agnes S

2003-07-01

The hypothesis that music training can improve verbal memory was tested in children. The results showed that children with music training demonstrated better verbal but not visual memory than did their counterparts without such training. When these children were followed up after a year, those who had begun or continued music training demonstrated significant verbal memory improvement. Students who discontinued the training did not show any improvement. Contrary to the differences in verbal memory between the groups, their changes in visual memory were not significantly different. Consistent with previous findings for adults (A. S. Chan, Y. Ho, & M. Cheung, 1998), the results suggest that music training systematically affects memory processing in accordance with possible neuroanatomical modifications in the left temporal lobe.

A Cross-cultural Study of Verbal Elaboration Productivity and Memory in Young Children

ERIC Educational Resources Information Center

Buium, Nissan; Turnure, James E.

1977-01-01

Fifty-six normal 5-year-old Israeli children were tested to determine whether questioning procedures found to be successful with American children for enhancing memory processes would be successful with children from another culture who spoke a different language. (Author/JMB)

75 FR 7600 - Agency Information Collection Activities: Proposed Collection; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-22

... suicide prevention; perceived and personal stigma related to depression and mental health seeking; and... Project: Cross-Site Evaluation of the Garrett Lee Smith Memorial Suicide Prevention and Early Intervention... the Garrett Lee Smith Memorial Youth Suicide Prevention and Early Intervention State/Tribal Programs...

Implicit memory for novel figure-ground displays includes a history of cross-border competition.

PubMed

Peterson, Mary A; Lampignano, Daniel W

2003-08-01

When configural cues specify that a figure lies on opposite sides of a repeated border in prime andprobe shapes, probe latencies are longer than when prime and probe borders are unrelated. Do such results reflect negative priming for the shape of the prime ground or cross-border competition from figure memory? The present study tested these alternatives by adding partial closure as a competing cue and reducing the similarity between the prime ground and the shape of the probe. Results supported the cross-border competition interpretation. Additional findings were that partial closure is a configural cue and that response effects can emerge from the potential shape on the ground side of a border. One prior experience was sufficient for these effects.

General upper bound on single-event upset rate. [due to ionizing radiation in orbiting vehicle avionics

NASA Technical Reports Server (NTRS)

Chlouber, Dean; O'Neill, Pat; Pollock, Jim

1990-01-01

A technique of predicting an upper bound on the rate at which single-event upsets due to ionizing radiation occur in semiconducting memory cells is described. The upper bound on the upset rate, which depends on the high-energy particle environment in earth orbit and accelerator cross-section data, is given by the product of an upper-bound linear energy-transfer spectrum and the mean cross section of the memory cell. Plots of the spectrum are given for low-inclination and polar orbits. An alternative expression for the exact upset rate is also presented. Both methods rely only on experimentally obtained cross-section data and are valid for sensitive bit regions having arbitrary shape.

Age differences in implicit memory: conceptual, perceptual, or methodological?

PubMed

Mitchell, David B; Bruss, Peter J

2003-12-01

The authors examined age differences in conceptual and perceptual implicit memory via word-fragment completion, word-stem completion, category exemplar generation, picture-fragment identification, and picture naming. Young, middle-aged, and older participants (N = 60) named pictures and words at study. Limited test exposure minimized explicit memory contamination, yielding no reliable age differences and equivalent cross-format effects. In contrast, explicit memory and neuropsychological measures produced significant age differences. In a follow-up experiment, 24 young adults were informed a priori about implicit testing. Their priming was equivalent to the main experiment, showing that test trial time restrictions limit explicit memory strategies. The authors concluded that most implicit memory processes remain stable across adulthood and suggest that explicit contamination be rigorously monitored in aging studies.

Modulating Hippocampal Plasticity with In Vivo Brain Stimulation

DTIC Science & Technology

2015-09-16

persists in the Schaffer collateral–CA1 region of the hippocampus . NMDA-dependent LTP has been shown to be essential for learning and memory ...S114 –S121. CrossRef Medline Neves G, Cooke SF, Bliss TV (2008) Synaptic plasticity, memory and the hippocampus : a neural network approach to causality...and memory . Understanding such molecular effects will lead to a better understanding of the mechanisms by which brain stimulation produces its effects

Caffeine and diphenyl diselenide improve long-term memory impaired in middle-aged rats.

PubMed

Leite, Marlon R; Marcondes Sari, Marcel Henrique; de Freitas, Mayara L; Oliveira, Lia P; Dalmolin, Laíza; Brandão, Ricardo; Zeni, Gilson

2014-05-01

The aim of the present study was to evaluate the effects of diphenyl diselenide (PhSe)2 supplemented diet (10ppm) associated to the administration of caffeine (15mg/kg; i.g.) for 30days on the novel object recognition memory in middle-aged rats. The present findings showed that (PhSe)2-supplemented diet enhanced short-term memory, but not long-term memory, of middle-aged rats in the novel object recognition task. The (PhSe)2 supplemented diet associated with caffeine administration improved long-term memory, but did not alter short-term memory, impaired in middle-aged rats. Daily caffeine administration to middle-aged rats had no effect on the memory tasks. Diet supplemented with (PhSe)2 plus caffeine administration increased the number of crossings and rearings reduced in middle-aged rats. Caffeine administration plus (PhSe)2 diets were effective in increasing the number of rearings and crossings, respectively, in middle-aged rats, [(3)H] glutamate uptake was reduced in hippocampal slices of rats from (PhSe)2 and caffeine plus (PhSe)2 groups. In addition, animals supplemented with (PhSe)2 showed an increase in the pCREB/CREB ratio whereas pAkt/Akt ratio was not modified. These results suggest that the effects of (PhSe)2 on the short-term memory may be related to its ability to decrease the uptake of glutamate, influencing the increase of CREB phosphorylation. (PhSe)2-supplemented diet associated to the administration of caffeine improved long-term memory impaired in middle-aged rats, an effect independent of CREB and Akt phosphorylation. Copyright © 2014 Elsevier Inc. All rights reserved.

Specificity, cross-reactivity, and function of antibodies elicited by Zika virus infection.

PubMed

Stettler, Karin; Beltramello, Martina; Espinosa, Diego A; Graham, Victoria; Cassotta, Antonino; Bianchi, Siro; Vanzetta, Fabrizia; Minola, Andrea; Jaconi, Stefano; Mele, Federico; Foglierini, Mathilde; Pedotti, Mattia; Simonelli, Luca; Dowall, Stuart; Atkinson, Barry; Percivalle, Elena; Simmons, Cameron P; Varani, Luca; Blum, Johannes; Baldanti, Fausto; Cameroni, Elisabetta; Hewson, Roger; Harris, Eva; Lanzavecchia, Antonio; Sallusto, Federica; Corti, Davide

2016-08-19

Zika virus (ZIKV), a mosquito-borne flavivirus with homology to Dengue virus (DENV), has become a public health emergency. By characterizing memory lymphocytes from ZIKV-infected patients, we dissected ZIKV-specific and DENV-cross-reactive immune responses. Antibodies to nonstructural protein 1 (NS1) were largely ZIKV-specific and were used to develop a serological diagnostic tool. In contrast, antibodies against E protein domain I/II (EDI/II) were cross-reactive and, although poorly neutralizing, potently enhanced ZIKV and DENV infection in vitro and lethally enhanced DENV disease in mice. Memory T cells against NS1 or E proteins were poorly cross-reactive, even in donors preexposed to DENV. The most potent neutralizing antibodies were ZIKV-specific and targeted EDIII or quaternary epitopes on infectious virus. An EDIII-specific antibody protected mice from lethal ZIKV infection, illustrating the potential for antibody-based therapy. Copyright © 2016, American Association for the Advancement of Science.

Long memory of abnormal investor attention and the cross-correlations between abnormal investor attention and trading volume, volatility respectively

NASA Astrophysics Data System (ADS)

Fan, Xiaoqian; Yuan, Ying; Zhuang, Xintian; Jin, Xiu

2017-03-01

Taking Baidu Index as a proxy for abnormal investor attention (AIA), the long memory property in the AIA of Shanghai Stock Exchange (SSE) 50 Index component stocks was empirically investigated using detrended fluctuation analysis (DFA) method. The results show that abnormal investor attention is power-law correlated with Hurst exponents between 0.64 and 0.98. Furthermore, the cross-correlations between abnormal investor attention and trading volume, volatility respectively are studied using detrended cross-correlation analysis (DCCA) and the DCCA cross-correlation coefficient (ρDCCA). The results suggest that there are positive correlations between AIA and trading volume, volatility respectively. In addition, the correlations for trading volume are in general higher than the ones for volatility. By carrying on rescaled range analysis (R/S) and rolling windows analysis, we find that the results mentioned above are effective and significant.

Cross-sectional and Longitudinal Analyses of Everyday Memory Lapses in Older Adults

PubMed Central

McAlister, Courtney; Schmitter-Edgecombe, Maureen

2016-01-01

Everyday memory lapses experienced by older adults (OA) were examined using a daily-diary checklist and retrospective questionnaire. In Experiment 1, 138 younger and 138 OAs indicated the frequency of forgetting of 16 memory lapses, and whether each occurred daily during the course of a week. OAs reported more memory lapses on the questionnaire, but not the daily diary. OAs reported more frequently forgetting names and words, while younger adults had more difficulty with appointments and personal dates. Fewer memory lapses on the daily diary were related to better performance on a laboratory-memory measure for OAs. In Experiment 2, 62 OAs returned for a five-year follow-up and endorsed experiencing more memory lapses on the daily diary compared to baseline, specifically forgetting more names and words, but not the retrospective questionnaire. Daily checklist memory lapses again correlated with the laboratory-memory measure. A daily checklist may be a viable way to assess everyday memory lapses. PMID:26810777

Prediction of error rates in dose-imprinted memories on board CRRES by two different methods. [Combined Release and Radiation Effects Satellite

NASA Technical Reports Server (NTRS)

Brucker, G. J.; Stassinopoulos, E. G.

1991-01-01

An analysis of the expected space radiation effects on the single event upset (SEU) properties of CMOS/bulk memories onboard the Combined Release and Radiation Effects Satellite (CRRES) is presented. Dose-imprint data from ground test irradiations of identical devices are applied to the predictions of cosmic-ray-induced space upset rates in the memories onboard the spacecraft. The calculations take into account the effect of total dose on the SEU sensitivity of the devices as the dose accumulates in orbit. Estimates of error rates, which involved an arbitrary selection of a single pair of threshold linear energy transfer (LET) and asymptotic cross-section values, were compared to the results of an integration over the cross-section curves versus LET. The integration gave lower upset rates than the use of the selected values of the SEU parameters. Since the integration approach is more accurate and eliminates the need for an arbitrary definition of threshold LET and asymptotic cross section, it is recommended for all error rate predictions where experimental sigma-versus-LET curves are available.

Are Asians Forgetful? Perception, Retention, and Recall in Episodic Remembering

ERIC Educational Resources Information Center

Wang, Qi

2009-01-01

Cross-cultural studies have shown that Asians exhibit less accessibility to episodic memories than Euro-Americans. This difference is often attributed to differential cognitive and social influences on memory retention, although there have been no empirical data concerning the underlying mechanism. Three studies were conducted to examine encoding…

Spatial Working Memory Is Necessary for Actions to Guide Thought

ERIC Educational Resources Information Center

Thomas, Laura E.

2013-01-01

Directed actions can play a causal role in cognition, shaping thought processes. What drives this cross-talk between action and thought? I investigated the hypothesis that representations in spatial working memory mediate interactions between directed actions and problem solving. Participants attempted to solve an insight problem while…

Abreacting and Assimilating Traumatic, Dissociated Memories of MPD Patients through Art Therapy.

ERIC Educational Resources Information Center

Jacobson, Mindy

1994-01-01

Notes that, when used to treat patients diagnosed with multiple personality disorder, art therapy aids in translating unspeakable memories into visual format. Discusses "stepping in," drawing process that may promote "cross-alter associations" to imagery drawn by other personalities. Addresses recovery of traumatic material…

The Nation's Combat Logistics Support Agency

Science.gov Websites

CENTCOM & SOCOM DLA Europe & Africa DLA Pacific History News Careers A graphic shows rows of cross -shaped gravestones in a cemetery with the words Heritage, History, Heroes over a partial American Flag background Remembering heritage, history and heroes on Memorial Day This Memorial Day, DLA employees and

Memory for Scientific Arguments and Their Sources: Claim-Evidence Consistency Matters

ERIC Educational Resources Information Center

Steffens, Brent; Britt, M. Anne; Braasch, Jason L.; Strømsø, Helge; Bråten, Ivar

2014-01-01

We investigated whether memory for scientific arguments and their sources were affected by the appropriateness of the claim-evidence relationship. Undergraduates read health articles in one of four conditions derived by crossing claim type (causal with definite qualifier, associative with tentative qualifier) and evidence type (experimental,…

LEARNING AND MEMORY TESTS IN DEVELOPMENTAL NEUROTOXICITY TESTING: A CROSS-LABORATORY COMPARISON OF CONTROL DATA.

EPA Science Inventory

The US EPA Developmental Neurotoxicity (DNT) Study Test Guideline (OPPTS 870.6300) calls for functional tests to assess the impact of chemicals on cognitive function in offspring following maternal exposure. A test of associative learning and memory is to be conducted around th...

A Life Course Model of Cognitive Activities, Socioeconomic Status, Education, Reading Ability, and Cognition

PubMed Central

Jefferson, Angela L.; Gibbons, Laura E.; Rentz, Dorene M.; Carvalho, Janessa O.; Manly, Jennifer; Bennett, David A.; Jones, Richard N.

2011-01-01

OBJECTIVES To cross-sectionally quantify the contribution of proxy measures of cognitive reserve reflective of the lifespan, such as education, socioeconomic status (SES), reading ability, and cognitive activities, in explaining late-life cognition. DESIGN Prospective observational cohort study of aging. SETTING Retirement communities across the Chicago metropolitan area. PARTICIPANTS Nine hundred fifty-one older adults free of clinical dementia in the Rush Memory and Aging Project (aged 79 ± 8, 74% female). MEASUREMENTS Baseline data on multiple life course factors included early-, mid-, and late-life participation in cognitive activities; early-life and adult SES; education; and reading ability (National Adult Reading Test; NART). Path analysis quantified direct and indirect standardized effects of life course factors on global cognition and five cognitive domains (episodic memory, semantic memory, working memory, visuospatial ability, perceptual speed). RESULTS Adjusting for age, sex, and race, education had the strongest association with global cognition, episodic memory, semantic memory, and visuospatial ability, whereas NART (followed by education) had the strongest association with working memory. Late-life cognitive activities had the strongest association with perceptual speed, followed by education. CONCLUSIONS These cross-sectional findings suggest that education and reading ability are the most-robust proxy measures of cognitive reserve in relation to late-life cognition. Additional research leveraging path analysis is warranted to better understand how these life course factors, reflecting the latent construct of cognitive reserve, affect abnormal cognitive aging. PMID:21797830

The role of age, working memory, and response inhibition in deviance distraction: A cross-sectional study.

PubMed

Leiva, Alicia; Andrés, Pilar; Servera, Mateu; Verbruggen, Frederick; Parmentier, Fabrice B R

2016-09-01

Sounds deviating from an otherwise repeated or structured sequence capture attention and affect performance in an ongoing visual task negatively, testament to the balance between selective attention and change detection. Although deviance distraction has been the object of much research, its modulation across the life span has been more scarcely addressed. Recent findings suggest possible connections with working memory and response inhibition. In this study we measured the performance of children and young and older adults in a cross-modal oddball task (deviance distraction), a working memory task (working memory capacity), and a response inhibition task (ability to voluntarily inhibit an already planned action) with the aim to establish the contribution of the latter 2 to the first. Older adults exhibited significantly more deviance distraction than children and young adults (who did not differ from each other). Working memory capacity mediated deviance distraction in children and older adults (though in opposite directions) but not in young adults. Response inhibition capacities did not mediate deviance distraction in any of the age groups. Altogether the results suggest that although the increase in deviance distraction observed in old age may partly reflect the relative impairment of working memory mechanisms, there is no straightforward and stable relation between working memory capacity and deviance distraction across the life span. Furthermore, our results indicate that deviance distraction is unlikely to reflect the temporary inhibition of responses. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

A life course model of cognitive activities, socioeconomic status, education, reading ability, and cognition.

PubMed

Jefferson, Angela L; Gibbons, Laura E; Rentz, Dorene M; Carvalho, Janessa O; Manly, Jennifer; Bennett, David A; Jones, Richard N

2011-08-01

To cross-sectionally quantify the contribution of proxy measures of cognitive reserve reflective of the lifespan, such as education, socioeconomic status (SES), reading ability, and cognitive activities, in explaining late-life cognition. Prospective observational cohort study of aging. Retirement communities across the Chicago metropolitan area. Nine hundred fifty-one older adults free of clinical dementia in the Rush Memory and Aging Project (aged 79 ± 8, 74% female). Baseline data on multiple life course factors included early-, mid-, and late-life participation in cognitive activities; early-life and adult SES; education; and reading ability (National Adult Reading Test; NART). Path analysis quantified direct and indirect standardized effects of life course factors on global cognition and five cognitive domains (episodic memory, semantic memory, working memory, visuospatial ability, perceptual speed). Adjusting for age, sex, and race, education had the strongest association with global cognition, episodic memory, semantic memory, and visuospatial ability, whereas NART (followed by education) had the strongest association with working memory. Late-life cognitive activities had the strongest association with perceptual speed, followed by education. These cross-sectional findings suggest that education and reading ability are the most-robust proxy measures of cognitive reserve in relation to late-life cognition. Additional research leveraging path analysis is warranted to better understand how these life course factors, reflecting the latent construct of cognitive reserve, affect abnormal cognitive aging. © 2011, Copyright the Authors. Journal compilation © 2011, The American Geriatrics Society.

Non-volatile memory based on the ferroelectric photovoltaic effect

PubMed Central

Guo, Rui; You, Lu; Zhou, Yang; Shiuh Lim, Zhi; Zou, Xi; Chen, Lang; Ramesh, R.; Wang, Junling

2013-01-01

The quest for a solid state universal memory with high-storage density, high read/write speed, random access and non-volatility has triggered intense research into new materials and novel device architectures. Though the non-volatile memory market is dominated by flash memory now, it has very low operation speed with ~10 μs programming and ~10 ms erasing time. Furthermore, it can only withstand ~105 rewriting cycles, which prevents it from becoming the universal memory. Here we demonstrate that the significant photovoltaic effect of a ferroelectric material, such as BiFeO3 with a band gap in the visible range, can be used to sense the polarization direction non-destructively in a ferroelectric memory. A prototype 16-cell memory based on the cross-bar architecture has been prepared and tested, demonstrating the feasibility of this technique. PMID:23756366

The impact of derivatives on Malaysian stock market

NASA Astrophysics Data System (ADS)

Malim, M. R.; Halim, F. A.; Murad, A.; Maad, H. A.; Annuar, N. F. M.

2017-09-01

The essential of derivatives has been discovered by researchers over recent decade. However, the conclusions made regarding the impact of derivatives on stock market volatility remains debatable. The main objective of this study is to examine the impact of derivatives on Malaysian stock market volatility by exploring FTSE Bursa Malaysia Kuala Lumpur Composite Index Futures (BMD FKLI) using FBM KLCI as the underlying asset. Generalized Autoregressive Conditional Heteroskedasticity (GARCH) (1, 1) model was employed to realize the objective. The results have shown that the introduction of futures trading has decreased the volatility of Malaysian stock market. The volatility increased vigorously during the Asian financial crisis compared to the Global financial crisis. However, the role of futures as a risk transfer is agreed as it could improve the market by decreasing the volatility in the spot market.

The effects of anticholinergic drugs on attention span and short-term memory skills in children.

PubMed

Giramonti, Karla M; Kogan, Barry A; Halpern, Leslie F

2008-01-01

Studies have shown cognitive problems in adults treated with anticholinergics. It is unclear if children are also susceptible to anticholinergic adverse effects. This study evaluates the effects of long-acting oxybutynin and tolterodine on short-term memory and attention in children with urgency and urge incontinence. Children with urgency or urge incontinence were recruited to take part in a prospective, randomized double-blinded placebo controlled trial using long-acting oxybutynin or tolterodine. Patients underwent a baseline test of their memory/recall ability and attention span using a standardized developmental/neuropsychological assessment tool. They were then randomized to either medication or placebo with retesting in 2 weeks, at which time they were crossed. They were retested after the second 2 weeks. Fourteen children (9 boys and 5 girls), ranging in age from 5 to 11 (M = 7.7) participated in the study. Attention and memory scores increased over time in all children, however, the analyses showed no significant negative effects of anticholinergic medications on attention or memory. Indeed, though not statistically significant, trends were for improvement in test scores in both areas. Our results in a double blinded cross-over trial suggest that long-acting oxybutynin and tolterodine do not have a deleterious effect on children's attention and memory. Other cognitive functions may be affected. (c) 2007 Wiley-Liss, Inc

Improved memory characteristics by NH3-nitrided GdO as charge storage layer for nonvolatile memory applications

NASA Astrophysics Data System (ADS)

Liu, L.; Xu, J. P.; Ji, F.; Chen, J. X.; Lai, P. T.

2012-07-01

Charge-trapping memory capacitor with nitrided gadolinium oxide (GdO) as charge storage layer (CSL) is fabricated, and the influence of post-deposition annealing in NH3 on its memory characteristics is investigated. Transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction are used to analyze the cross-section and interface quality, composition, and crystallinity of the stack gate dielectric, respectively. It is found that nitrogen incorporation can improve the memory window and achieve a good trade-off among the memory properties due to NH3-annealing-induced reasonable distribution profile of a large quantity of deep-level bulk traps created in the nitrided GdO film and reduction of shallow traps near the CSL/SiO2 interface.

Cross-Linguistic Differences in the Immediate Serial Recall of Consonants versus Vowels

ERIC Educational Resources Information Center

Kissling, Elizabeth M.

2012-01-01

The current study investigated native English and native Arabic speakers' phonological short-term memory for sequences of consonants and vowels. Phonological short-term memory was assessed in immediate serial recall tasks conducted in Arabic and English for both groups. Participants (n = 39) heard series of six consonant-vowel syllables and wrote…

Cannabis Use and Memory Brain Function in Adolescent Boys: A Cross-Sectional Multicenter Functional Magnetic Resonance Imaging Study

ERIC Educational Resources Information Center

Jager, Gerry; Block, Robert I.; Luijten, Maartje; Ramsey, Nick F.

2010-01-01

Objective: Early-onset cannabis use has been associated with later use/abuse, mental health problems (psychosis, depression), and abnormal development of cognition and brain function. During adolescence, ongoing neurodevelopmental maturation and experience shape the neural circuitry underlying complex cognitive functions such as memory and…

Functions of Memory Sharing and Mother-Child Reminiscing Behaviors: Individual and Cultural Variations

ERIC Educational Resources Information Center

Kulkofsky, Sarah; Wang, Qi; Koh, Jessie Bee Kim

2009-01-01

This study examined maternal beliefs about the functions of memory sharing and the relations between these beliefs and mother-child reminiscing behaviors in a cross-cultural context. Sixty-three European American and 47 Chinese mothers completed an open-ended questionnaire concerning their beliefs about the functions of parent-child memory…

Working Memory Influences on Cross-Language Activation during Bilingual Lexical Disambiguation

ERIC Educational Resources Information Center

Areas da Luz Fontes, Ana B.; Schwartz, Ana I.

2011-01-01

This study investigated the role of verbal working memory on bilingual lexical disambiguation. Spanish-English bilinguals read sentences that ended in either a cognate or noncognate homonym or a control word. Participants decided whether follow-up target words were related in meaning to the sentences. On critical trials, sentences biased the…

The representation of multiplication and division facts in memory.

PubMed

De Brauwer, Jolien; Fias, Wim

2011-01-01

Recently, using a training paradigm, Campbell and Agnew (2009) observed cross-operation response time savings with nonidentical elements (e.g., practice 3 + 2, test 5 - 2) for addition and subtraction, showing that a single memory representation underlies addition and subtraction performance. Evidence for cross-operation savings between multiplication and division have been described frequently (e.g., Campbell, Fuchs-Lacelle, & Phenix, 2006) but they have always been attributed to a mediation strategy (reformulating a division problem as a multiplication problem, e.g., Campbell et al., 2006). Campbell and Agnew (2009) therefore concluded that there exists a fundamental difference between addition and subtraction on the one hand and multiplication and division on the other hand. However, our results suggest that retrieval savings between inverse multiplication and division problems can be observed. Even for small problems (solved by direct retrieval) practicing a division problem facilitated the corresponding multiplication problem and vice versa. These findings indicate that shared memory representations underlie multiplication and division retrieval. Hence, memory and learning processes do not seem to differ fundamentally between addition-subtraction and multiplication-division.

Neurogranin as a predictor of memory and executive function decline in MCI patients.

PubMed

Headley, Alison; De Leon-Benedetti, Andres; Dong, Chuanhui; Levin, Bonnie; Loewenstein, David; Camargo, Christian; Rundek, Tatjana; Zetterberg, Henrik; Blennow, Kaj; Wright, Clinton B; Sun, Xiaoyan

2018-03-06

To determine whether high CSF levels of neurogranin (Ng) predict longitudinal decline in memory and executive function during early-stage Alzheimer disease (AD). Baseline levels of CSF Ng were studied in relation to cross-sectional and longitudinal cognitive performance over 8 years. Data were obtained from the Alzheimer's Disease Neuroimaging Initiative database, and participants with normal cognition (n = 111) and mild cognitive impairment (MCI) (n = 193) were included. High levels of CSF Ng were associated with poor baseline memory scores (β = -0.21, p < 0.0001). CSF Ng predicted both memory and executive function decline over time (β = -0.0313, p = 0.0068 and β = -0.0346, p = 0.0169, respectively) independently of age, sex, education, and APOE ε4 status. When the rate of decline by tertiles was examined, CSF Ng was a level-dependent predictor of memory function, whereby the group with highest levels of Ng showed the fastest rates of decline in both memory and executive function. When examined separately, elevated Ng was associated with cognitive decline in participants with MCI but not in those with normal cognition. The levels of CSF Ng were not associated with cognitive measures when tau and amyloid 42 (Aβ 42 ) were controlled for in these analyses. High CSF Ng associates with poor memory scores in participants with MCI cross-sectionally and with poor memory and executive function longitudinally. The association of Ng with cognitive measures disappears when tau and Aβ 42 are included in the statistical models. Our findings suggest that CSF Ng may serve as a biomarker of cognition. Synaptic dysfunction contributes to cognitive impairment in early-stage AD. © 2018 American Academy of Neurology.

Using event-related potentials to study perinatal nutrition and brain development in infants of diabetic mothers.

PubMed

deRegnier, Raye-Ann; Long, Jeffrey D; Georgieff, Michael K; Nelson, Charles A

2007-01-01

Proper prenatal and postnatal nutrition is essential for optimal brain development and function. The early use of event-related potentials enables neuroscientists to study the development of cognitive function from birth and to evaluate the role of specific nutrients in development. Perinatal iron deficiency occurs in severely affected infants of diabetic mothers. In animal models, severe perinatal iron deficiency targets the explicit memory system of the brain. Cross-sectional ERP studies have shown that infants of diabetic mothers have impairments in recognition memory from birth through 8 months of age. The purpose of this study was to evaluate longitudinal development of recognition memory using ERPs in infants of diabetic mothers compared with control infants. Infants of diabetic mothers were divided into high and low risk status based upon their birth weights and iron status and compared with healthy control infants. Infants were tested in the newborn period for auditory recognition memory, at 6 months for visual recognition memory and at 8 months for cross modal memory. ERPs were evaluated for developmental changes in the slow waves that are thought to reflect memory and the Nc component that is thought to reflect attention. The results of the study showed differences in development between the IDMs and control infants in the development of the slow waves over the left anterior temporal leads and age-related patterns of development in the NC component. These results are consistent with animal models showing that perinatal iron deficiency affects the development of the memory networks of the brain. This study highlights the value of using ERPs to translate basic science information obtained from animal models to the development of the human infant.

Using Event-Related Potentials to Study Perinatal Nutrition and Brain Development in Infants of Diabetic Mothers

PubMed Central

deRegnier, Raye-Ann; Long, Jeffrey D.; Georgieff, Michael K.; Nelson, Charles A.

2009-01-01

Proper prenatal and postnatal nutrition is essential for optimal brain development and function. The early use of event-related potentials enables neuroscientists to study the development of cognitive function from birth and to evaluate the role of specific nutrients in development. Perinatal iron deficiency occurs in severely affected infants of diabetic mothers. In animal models, severe perinatal iron deficiency targets the explicit memory system of the brain. Cross-sectional ERP studies have shown that infants of diabetic mothers have impairments in recognition memory from birth through 8 months of age. The purpose of this study was to evaluate longitudinal development of recognition memory using ERPs in infants of diabetic mothers compared with control infants. Infants of diabetic mothers were divided into high and low risk status based upon their birthweights and iron status and compared with healthy control infants. Infants were tested in the newborn period for auditory recognition memory, at 6 months for visual recognition memory and at 8 months for cross modal memory. ERPs were evaluated for developmental changes in the slow waves that are thought to reflect memory and the Nc component that is thought to reflect attention. The results of the study showed differences in development between the IDMs and control infants in the development of the slow waves over the left anterior temporal leads and age-related patterns of development in the NC component. These results are consistent with animal models showing that perinatal iron deficiency affects the development of the memory networks of the brain. This study highlights the value of using ERPs to translate basic science information obtained from animal models to the development of the human infant. PMID:17559331

Memories of unethical actions become obfuscated over time

PubMed Central

Kouchaki, Maryam; Gino, Francesca

2016-01-01

Despite our optimistic belief that we would behave honestly when facing the temptation to act unethically, we often cross ethical boundaries. This paper explores one possibility of why people engage in unethical behavior over time by suggesting that their memory for their past unethical actions is impaired. We propose that, after engaging in unethical behavior, individuals’ memories of their actions become more obfuscated over time because of the psychological distress and discomfort such misdeeds cause. In nine studies (n = 2,109), we show that engaging in unethical behavior produces changes in memory so that memories of unethical actions gradually become less clear and vivid than memories of ethical actions or other types of actions that are either positive or negative in valence. We term this memory obfuscation of one’s unethical acts over time “unethical amnesia.” Because of unethical amnesia, people are more likely to act dishonestly repeatedly over time. PMID:27185941

Memories of unethical actions become obfuscated over time.

PubMed

Kouchaki, Maryam; Gino, Francesca

2016-05-31

Despite our optimistic belief that we would behave honestly when facing the temptation to act unethically, we often cross ethical boundaries. This paper explores one possibility of why people engage in unethical behavior over time by suggesting that their memory for their past unethical actions is impaired. We propose that, after engaging in unethical behavior, individuals' memories of their actions become more obfuscated over time because of the psychological distress and discomfort such misdeeds cause. In nine studies (n = 2,109), we show that engaging in unethical behavior produces changes in memory so that memories of unethical actions gradually become less clear and vivid than memories of ethical actions or other types of actions that are either positive or negative in valence. We term this memory obfuscation of one's unethical acts over time "unethical amnesia." Because of unethical amnesia, people are more likely to act dishonestly repeatedly over time.

Flexible crossbar-structured resistive memory arrays on plastic substrates via inorganic-based laser lift-off.

PubMed

Kim, Seungjun; Son, Jung Hwan; Lee, Seung Hyun; You, Byoung Kuk; Park, Kwi-Il; Lee, Hwan Keon; Byun, Myunghwan; Lee, Keon Jae

2014-11-26

Crossbar-structured memory comprising 32 × 32 arrays with one selector-one resistor (1S-1R) components are initially fabricated on a rigid substrate. They are transferred without mechanical damage via an inorganic-based laser lift-off (ILLO) process as a result of laser-material interaction. Addressing tests of the transferred memory arrays are successfully performed to verify mitigation of cross-talk on a plastic substrate. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

DTIC Science & Technology

1983-06-01

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

Gaze movements and spatial working memory in collision avoidance: a traffic intersection task

PubMed Central

Hardiess, Gregor; Hansmann-Roth, Sabrina; Mallot, Hanspeter A.

2013-01-01

Street crossing under traffic is an everyday activity including collision detection as well as avoidance of objects in the path of motion. Such tasks demand extraction and representation of spatio-temporal information about relevant obstacles in an optimized format. Relevant task information is extracted visually by the use of gaze movements and represented in spatial working memory. In a virtual reality traffic intersection task, subjects are confronted with a two-lane intersection where cars are appearing with different frequencies, corresponding to high and low traffic densities. Under free observation and exploration of the scenery (using unrestricted eye and head movements) the overall task for the subjects was to predict the potential-of-collision (POC) of the cars or to adjust an adequate driving speed in order to cross the intersection without collision (i.e., to find the free space for crossing). In a series of experiments, gaze movement parameters, task performance, and the representation of car positions within working memory at distinct time points were assessed in normal subjects as well as in neurological patients suffering from homonymous hemianopia. In the following, we review the findings of these experiments together with other studies and provide a new perspective of the role of gaze behavior and spatial memory in collision detection and avoidance, focusing on the following questions: (1) which sensory variables can be identified supporting adequate collision detection? (2) How do gaze movements and working memory contribute to collision avoidance when multiple moving objects are present and (3) how do they correlate with task performance? (4) How do patients with homonymous visual field defects (HVFDs) use gaze movements and working memory to compensate for visual field loss? In conclusion, we extend the theory of collision detection and avoidance in the case of multiple moving objects and provide a new perspective on the combined operation of external (bottom-up) and internal (top-down) cues in a traffic intersection task. PMID:23760667

Modality independence of order coding in working memory: Evidence from cross-modal order interference at recall.

PubMed

Vandierendonck, André

2016-01-01

Working memory researchers do not agree on whether order in serial recall is encoded by dedicated modality-specific systems or by a more general modality-independent system. Although previous research supports the existence of autonomous modality-specific systems, it has been shown that serial recognition memory is prone to cross-modal order interference by concurrent tasks. The present study used a serial recall task, which was performed in a single-task condition and in a dual-task condition with an embedded memory task in the retention interval. The modality of the serial task was either verbal or visuospatial, and the embedded tasks were in the other modality and required either serial or item recall. Care was taken to avoid modality overlaps during presentation and recall. In Experiment 1, visuospatial but not verbal serial recall was more impaired when the embedded task was an order than when it was an item task. Using a more difficult verbal serial recall task, verbal serial recall was also more impaired by another order recall task in Experiment 2. These findings are consistent with the hypothesis of modality-independent order coding. The implications for views on short-term recall and the multicomponent view of working memory are discussed.

Cognitive reserve moderates the association between functional network anti-correlations and memory in MCI.

PubMed

Franzmeier, Nicolai; Buerger, Katharina; Teipel, Stefan; Stern, Yaakov; Dichgans, Martin; Ewers, Michael

2017-02-01

Cognitive reserve (CR) shows protective effects on cognitive function in older adults. Here, we focused on the effects of CR at the functional network level. We assessed in patients with amnestic mild cognitive impairment (aMCI) whether higher CR moderates the association between low internetwork cross-talk on memory performance. In 2 independent aMCI samples (n = 76 and 93) and healthy controls (HC, n = 36), CR was assessed via years of education and intelligence (IQ). We focused on the anti-correlation between the dorsal attention network (DAN) and an anterior and posterior default mode network (DMN), assessed via sliding time window analysis of resting-state functional magnetic resonance imaging (fMRI). The DMN-DAN anti-correlation was numerically but not significantly lower in aMCI compared to HC. However, in aMCI, lower anterior DMN-DAN anti-correlation was associated with lower memory performance. This association was moderated by CR proxies, where the association between the internetwork anti-correlation and memory performance was alleviated at higher levels of education or IQ. In conclusion, lower DAN-DMN cross-talk is associated with lower memory in aMCI, where such effects are buffered by higher CR. Copyright © 2016 Elsevier Inc. All rights reserved.

Neurons in the barrel cortex turn into processing whisker and odor signals: a cellular mechanism for the storage and retrieval of associative signals

PubMed Central

Wang, Dangui; Zhao, Jun; Gao, Zilong; Chen, Na; Wen, Bo; Lu, Wei; Lei, Zhuofan; Chen, Changfeng; Liu, Yahui; Feng, Jing; Wang, Jin-Hui

2015-01-01

Associative learning and memory are essential to logical thinking and cognition. How the neurons are recruited as associative memory cells to encode multiple input signals for their associated storage and distinguishable retrieval remains unclear. We studied this issue in the barrel cortex by in vivo two-photon calcium imaging, electrophysiology, and neural tracing in our mouse model that the simultaneous whisker and olfaction stimulations led to odorant-induced whisker motion. After this cross-modal reflex arose, the barrel and piriform cortices connected. More than 40% of barrel cortical neurons became to encode odor signal alongside whisker signal. Some of these neurons expressed distinct activity patterns in response to acquired odor signal and innate whisker signal, and others encoded similar pattern in response to these signals. In the meantime, certain barrel cortical astrocytes encoded odorant and whisker signals. After associative learning, the neurons and astrocytes in the sensory cortices are able to store the newly learnt signal (cross-modal memory) besides the innate signal (native-modal memory). Such associative memory cells distinguish the differences of these signals by programming different codes and signify the historical associations of these signals by similar codes in information retrievals. PMID:26347609

Common and differential electrophysiological mechanisms underlying semantic object memory retrieval probed by features presented in different stimulus types.

PubMed

Chiang, Hsueh-Sheng; Eroh, Justin; Spence, Jeffrey S; Motes, Michael A; Maguire, Mandy J; Krawczyk, Daniel C; Brier, Matthew R; Hart, John; Kraut, Michael A

2016-08-01

How the brain combines the neural representations of features that comprise an object in order to activate a coherent object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular object. Sixteen subjects completed one of the three versions (N=48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1-4Hz, theta: 4-7Hz; alpha: 8-12Hz; beta: 13-19Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of semantic object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during semantic object memory retrieval. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct access inter-process shared memory

DOEpatents

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

2013-10-22

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

Low-Power Architectures for Large Radio Astronomy Correlators

NASA Technical Reports Server (NTRS)

D'Addario, Larry R.

2011-01-01

The architecture of a cross-correlator for a synthesis radio telescope with N greater than 1000 antennas is studied with the objective of minimizing power consumption. It is found that the optimum architecture minimizes memory operations, and this implies preference for a matrix structure over a pipeline structure and avoiding the use of memory banks as accumulation registers when sharing multiply-accumulators among baselines. A straw-man design for N = 2000 and bandwidth of 1 GHz, based on ASICs fabricated in a 90 nm CMOS process, is presented. The cross-correlator proper (excluding per-antenna processing) is estimated to consume less than 35 kW.

Redundant single event upset supression system

DOEpatents

Hoff, James R.

2006-04-04

CMOS transistors are configured to operate as either a redundant, SEU-tolerant, positive-logic, cross-coupled Nor Gate SR-flip flop or a redundant, SEU-tolerant, negative-logic, cross-coupled Nand Gate SR-flip flop. The register can operate as a memory, and further as a memory that can overcome the effects of radiation. As an SR-flip flop, the invention can be altered into any known type of latch or flip-flop by the application of external logic, thereby extending radiation tolerance to devices previously incapable of radiation tolerance. Numerous registers can be logically connected and replicated thereby being electronically configured to operate as a redundant circuit.

Developmental Changes in Working Memory, Updating, and Math Achievement

ERIC Educational Resources Information Center

Lee, Kerry; Bull, Rebecca

2016-01-01

Children with higher working memory or updating (WMU) capacity perform better in math. What is less clear is whether and how this relation varies with grade. Children (N = 673, kindergarten to Grade 9) participated in a 4-year cross-sequential study. Data from 3 WMU (Listening Recall, Mr. X, and an updating task) and a standardized math task…

Working Memory Development in Children with Mild to Borderline Intellectual Disabilities

ERIC Educational Resources Information Center

Van der Molen, M. J.; Henry, L. A.; Van Luit, J. E. H.

2014-01-01

Background: The purpose of the current cross-sectional study was to examine the developmental progression in working memory (WM) between the ages of 9 and 16 years in a large sample of children with mild to borderline intellectual disabilities (MBID). Baddeley's influential WM model was used as a theoretical framework. Furthermore, the…

The Development of Short-Term and Incidental Memory: A Cross-Cultural Study.

ERIC Educational Resources Information Center

Wagner, Daniel A.

This study investigated developmental changes in memory performance for two contrasting populations in Urban and Rural Yucatan, Mexico. Subjects were divided into five groups defined by age, including children and adults. All urban S's were in school, while only the two younger rural groups were in school, and older rural S's had little or no…

Large conditional single-photon cross-phase modulation

NASA Astrophysics Data System (ADS)

Beck, Kristin; Hosseini, Mahdi; Duan, Yiheng; Vuletic, Vladan

2016-05-01

Deterministic optical quantum logic requires a nonlinear quantum process that alters the phase of a quantum optical state by π through interaction with only one photon. Here, we demonstrate a large conditional cross-phase modulation between a signal field, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. This approach avoids fundamental limitations associated with multimode effects for traveling optical photons. We measure a conditional cross-phase shift of up to π / 3 between the retrieved signal and control photons, and confirm deterministic entanglement between the signal and control modes by extracting a positive concurrence. With a moderate improvement in cavity finesse, our system can reach a coherent phase shift of p at low loss, enabling deterministic and universal photonic quantum logic. Preprint: arXiv:1512.02166 [quant-ph

No Acute Effects of Choline Bitartrate Food Supplements on Memory in Healthy, Young, Human Adults.

PubMed

Lippelt, D P; van der Kint, S; van Herk, K; Naber, M

2016-01-01

Choline is a dietary component and precursor of acetylcholine, a crucial neurotransmitter for memory-related brain functions. In two double-blind, placebo-controlled cross-over experiments, we investigated whether the food supplement choline bitartrate improved declarative memory and working memory in healthy, young students one to two hours after supplementation. In experiment 1, 28 participants performed a visuospatial working memory task. In experiment 2, 26 participants performed a declarative picture memorization task. In experiment 3, 40 participants performed a verbal working memory task in addition to the visuospatial working memory and declarative picture task. All tasks were conducted approximately 60 minutes after the ingestion of 2.0-2.5g of either choline bitartrate or placebo. We found that choline did not significantly enhance memory performance during any of the tasks. The null hypothesis that choline does not improve memory performance as compared to placebo was strongly supported by Bayesian statistics. These results are in contrast with animal studies suggesting that choline supplementation boosts memory performance and learning. We conclude that choline likely has no acute effects on cholinergic memory functions in healthy human participants.

No Acute Effects of Choline Bitartrate Food Supplements on Memory in Healthy, Young, Human Adults

PubMed Central

Lippelt, D. P.; van der Kint, S.; van Herk, K.; Naber, M.

2016-01-01

Choline is a dietary component and precursor of acetylcholine, a crucial neurotransmitter for memory-related brain functions. In two double-blind, placebo-controlled cross-over experiments, we investigated whether the food supplement choline bitartrate improved declarative memory and working memory in healthy, young students one to two hours after supplementation. In experiment 1, 28 participants performed a visuospatial working memory task. In experiment 2, 26 participants performed a declarative picture memorization task. In experiment 3, 40 participants performed a verbal working memory task in addition to the visuospatial working memory and declarative picture task. All tasks were conducted approximately 60 minutes after the ingestion of 2.0–2.5g of either choline bitartrate or placebo. We found that choline did not significantly enhance memory performance during any of the tasks. The null hypothesis that choline does not improve memory performance as compared to placebo was strongly supported by Bayesian statistics. These results are in contrast with animal studies suggesting that choline supplementation boosts memory performance and learning. We conclude that choline likely has no acute effects on cholinergic memory functions in healthy human participants. PMID:27341028

Multibit Polycristalline Silicon-Oxide-Silicon Nitride-Oxide-Silicon Memory Cells with High Density Designed Utilizing a Separated Control Gate

NASA Astrophysics Data System (ADS)

Rok Kim, Kyeong; You, Joo Hyung; Dal Kwack, Kae; Kim, Tae Whan

2010-10-01

Unique multibit NAND polycrystalline silicon-oxide-silicon nitride-oxide-silicon (SONOS) memory cells utilizing a separated control gate (SCG) were designed to increase memory density. The proposed NAND SONOS memory device based on a SCG structure was operated as two bits, resulting in an increase in the storage density of the NVM devices in comparison with conventional single-bit memories. The electrical properties of the SONOS memory cells with a SCG were investigated to clarify the charging effects in the SONOS memory cells. When the program voltage was supplied to each gate of the NAND SONOS flash memory cells, the electrons were trapped in the nitride region of the oxide-nitride-oxide layer under the gate to supply the program voltage. The electrons were accumulated without affecting the other gate during the programming operation, indicating the absence of cross-talk between two trap charge regions. It is expected that the inference effect will be suppressed by the lower program voltage than the program voltage of the conventional NAND flash memory. The simulation results indicate that the proposed unique NAND SONOS memory cells with a SCG can be used to increase memory density.

Association of subjective memory complaints with subsequent cognitive decline in community-dwelling elderly individuals with baseline cognitive impairment.

PubMed

Schofield, P W; Marder, K; Dooneief, G; Jacobs, D M; Sano, M; Stern, Y

1997-05-01

The validity of subjective memory complaints has been questioned by clinical studies that have shown little relationship between memory complaints and objective memory performance. These studies often have been cross-sectional in design, have excluded individuals with cognitive impairment, or have lacked a comparison group. The authors conducted a study that attempted to avoid these limitations. Memory complaints of 364 nondemented, community-dwelling elderly individuals were recorded as present or absent at the baseline evaluation. After 1 year, 169 subjects were reevaluated. Standardized neurologic and neuropsychological evaluations were used at each assessment to classify subjects as normal or cognitively impaired. At baseline, 31% of the normal subjects and 47% of those with cognitive impairment had memory complaints. Subjects with memory complaints had higher Hamilton depression scale scores than subjects without memory complaints but equivalent scores on a measure of total recall. At follow-up, multivariate analyses showed that subjects with baseline memory complaints had significantly greater decline in memory and cognition than subjects without memory complaints. Secondary analyses showed this effect to be confined to subjects with baseline cognitive impairment. Memory complaints may lack validity in subjects with normal cognition, but in nondemented individuals with cognitive impairment, memory complaints may predict subsequent cognitive decline.

Hurst Estimation of Scale Invariant Processes with Stationary Increments and Piecewise Linear Drift

NASA Astrophysics Data System (ADS)

Modarresi, N.; Rezakhah, S.

The characteristic feature of the discrete scale invariant (DSI) processes is the invariance of their finite dimensional distributions by dilation for certain scaling factor. DSI process with piecewise linear drift and stationary increments inside prescribed scale intervals is introduced and studied. To identify the structure of the process, first, we determine the scale intervals, their linear drifts and eliminate them. Then, a new method for the estimation of the Hurst parameter of such DSI processes is presented and applied to some period of the Dow Jones indices. This method is based on fixed number equally spaced samples inside successive scale intervals. We also present some efficient method for estimating Hurst parameter of self-similar processes with stationary increments. We compare the performance of this method with the celebrated FA, DFA and DMA on the simulated data of fractional Brownian motion (fBm).

Nozzle Initiative Industry Advisory Committee on Standardization of Carbon-Phenolic Test Methods and Specifications

NASA Technical Reports Server (NTRS)

Bull, William B. (Compiler); Pinoli, Pat C. (Compiler); Upton, Cindy G. (Compiler); Day, Tony (Compiler); Hill, Keith (Compiler); Stone, Frank (Compiler); Hall, William B.

1994-01-01

This report is a compendium of the presentations of the 12th biannual meeting of the Industry Advisory Committee under the Solid Propulsion Integrity Program. A complete transcript of the welcoming talks is provided. Presentation outlines and overheads are included for the other sessions: SPIP Overview, Past, Current and Future Activity; Test Methods Manual and Video Tape Library; Air Force Developed Computer Aided Cure Program and SPC/TQM Experience; Magneto-Optical mapper (MOM), Joint Army/NASA program to assess composite integrity; Permeability Testing; Moisture Effusion Testing by Karl Fischer Analysis; Statistical Analysis of Acceptance Test Data; NMR Phenolic Resin Advancement; Constituent Testing Highlights on the LDC Optimization Program; Carbon Sulfur Study, Performance Related Testing; Current Rayon Specifications and Future Availability; RSRM/SPC Implementation; SRM Test Methods, Delta/Titan/FBM/RSRM; and Open Forum on Performance Based Acceptance Testing -- Industry Experience.

A Cross-Modal Perspective on the Relationships between Imagery and Working Memory

PubMed Central

Likova, Lora T.

2013-01-01

Mapping the distinctions and interrelationships between imagery and working memory (WM) remains challenging. Although each of these major cognitive constructs is defined and treated in various ways across studies, most accept that both imagery and WM involve a form of internal representation available to our awareness. In WM, there is a further emphasis on goal-oriented, active maintenance, and use of this conscious representation to guide voluntary action. Multicomponent WM models incorporate representational buffers, such as the visuo-spatial sketchpad, plus central executive functions. If there is a visuo-spatial “sketchpad” for WM, does imagery involve the same representational buffer? Alternatively, does WM employ an imagery-specific representational mechanism to occupy our awareness? Or do both constructs utilize a more generic “projection screen” of an amodal nature? To address these issues, in a cross-modal fMRI study, I introduce a novel Drawing-Based Memory Paradigm, and conceptualize drawing as a complex behavior that is readily adaptable from the visual to non-visual modalities (such as the tactile modality), which opens intriguing possibilities for investigating cross-modal learning and plasticity. Blindfolded participants were trained through our Cognitive-Kinesthetic Method (Likova, 2010a, 2012) to draw complex objects guided purely by the memory of felt tactile images. If this WM task had been mediated by transfer of the felt spatial configuration to the visual imagery mechanism, the response-profile in visual cortex would be predicted to have the “top-down” signature of propagation of the imagery signal downward through the visual hierarchy. Remarkably, the pattern of cross-modal occipital activation generated by the non-visual memory drawing was essentially the inverse of this typical imagery signature. The sole visual hierarchy activation was isolated to the primary visual area (V1), and accompanied by deactivation of the entire extrastriate cortex, thus ’cutting-off’ any signal propagation from/to V1 through the visual hierarchy. The implications of these findings for the debate on the interrelationships between the core cognitive constructs of WM and imagery and the nature of internal representations are evaluated. PMID:23346061

Computational principles of working memory in sentence comprehension.

PubMed

Lewis, Richard L; Vasishth, Shravan; Van Dyke, Julie A

2006-10-01

Understanding a sentence requires a working memory of the partial products of comprehension, so that linguistic relations between temporally distal parts of the sentence can be rapidly computed. We describe an emerging theoretical framework for this working memory system that incorporates several independently motivated principles of memory: a sharply limited attentional focus, rapid retrieval of item (but not order) information subject to interference from similar items, and activation decay (forgetting over time). A computational model embodying these principles provides an explanation of the functional capacities and severe limitations of human processing, as well as accounts of reading times. The broad implication is that the detailed nature of cross-linguistic sentence processing emerges from the interaction of general principles of human memory with the specialized task of language comprehension.

Quantum memory in warm rubidium vapor with buffer gas.

PubMed

Bashkansky, Mark; Fatemi, Fredrik K; Vurgaftman, Igor

2012-01-15

The realization of quantum memory using warm atomic vapor cells is appealing because of their commercial availability and the perceived reduction in experimental complexity. In spite of the ambiguous results reported in the literature, we demonstrate that quantum memory can be implemented in a single cell with buffer gas using the geometry where the write and read beams are nearly copropagating. The emitted Stokes and anti-Stokes photons display cross-correlation values greater than 2, characteristic of quantum states, for delay times up to 4 μs.

Altered cognitive development in the siblings of individuals with schizophrenia

PubMed Central

Barch, Deanna M.; Cohen, Rachel; Csernansky, John

2014-01-01

The goal of the current study was to further investigate the late neurodevelopmental hypothesis of schizophrenia by examining cross-sectional, age-related changes in cognitive function among young adult: 1) siblings of individuals with schizophrenia (N = 66); (2) healthy control participants (N = 77); and (3) the siblings of healthy controls (N = 77). All subjects participated in a battery of tasks in four domains: 1) IQ; 2) working memory; 3) episodic memory; and 4) executive function. We found significant group differences in the relationships between age and performance in working memory and episodic memory, with similar patterns for executive function and verbal IQ. The siblings of individuals with schizophrenia showed impaired performance in working memory, episodic memory, and executive function. In addition, healthy controls and/or their siblings showed age-related improvements in all four cognitive domains, while the siblings of individuals with schizophrenia only showed this for verbal IQ. PMID:25485180

Altered cognitive development in the siblings of individuals with schizophrenia.

PubMed

Barch, Deanna M; Cohen, Rachel; Csernansky, John

2014-03-01

The goal of the current study was to further investigate the late neurodevelopmental hypothesis of schizophrenia by examining cross-sectional, age-related changes in cognitive function among young adult: 1) siblings of individuals with schizophrenia (N = 66); (2) healthy control participants (N = 77); and (3) the siblings of healthy controls (N = 77). All subjects participated in a battery of tasks in four domains: 1) IQ; 2) working memory; 3) episodic memory; and 4) executive function. We found significant group differences in the relationships between age and performance in working memory and episodic memory, with similar patterns for executive function and verbal IQ. The siblings of individuals with schizophrenia showed impaired performance in working memory, episodic memory, and executive function. In addition, healthy controls and/or their siblings showed age-related improvements in all four cognitive domains, while the siblings of individuals with schizophrenia only showed this for verbal IQ.

Air-stable memory array of bistable rectifying diodes based on ferroelectric-semiconductor polymer blends

NASA Astrophysics Data System (ADS)

Kumar, Manasvi; Sharifi Dehsari, Hamed; Anwar, Saleem; Asadi, Kamal

2018-03-01

Organic bistable diodes based on phase-separated blends of ferroelectric and semiconducting polymers have emerged as promising candidates for non-volatile information storage for low-cost solution processable electronics. One of the bottlenecks impeding upscaling is stability and reliable operation of the array in air. Here, we present a memory array fabricated with an air-stable amine-based semiconducting polymer. Memory diode fabrication and full electrical characterizations were carried out in atmospheric conditions (23 °C and 45% relative humidity). The memory diodes showed on/off ratios greater than 100 and further exhibited robust and stable performance upon continuous write-read-erase-read cycles. Moreover, we demonstrate a 4-bit memory array that is free from cross-talk with a shelf-life of several months. Demonstration of the stability and reliable air operation further strengthens the feasibility of the resistance switching in ferroelectric memory diodes for low-cost applications.

Ascent to moderate altitude impairs overnight memory improvements.

PubMed

Tesler, Noemi; Latshang, Tsogyal D; Lo Cascio, Christian M; Stadelmann, Katrin; Stoewhas, Anne-Christin; Kohler, Malcolm; Bloch, Konrad E; Achermann, Peter; Huber, Reto

2015-02-01

Several studies showed beneficial effects of sleep on memory performance. Slow waves, the electroencephalographic characteristic of deep sleep, reflected on the neuronal level by synchronous slow oscillations, seem crucial for these benefits. Traveling to moderate altitudes decreases deep sleep. In a randomized cross-over design healthy male subjects performed a visuo-motor learning task in Zurich (490 m) and at Davos Jakobshorn (2590 m) in random order. Memory performance was assessed immediately after learning, before sleep, and in the morning after a night of sleep. Sleep EEG recordings were performed during the nights. Our findings show an altitude induced reduction of sleep dependent memory performance. Moreover, this impaired sleep dependent memory performance was associated with reduced slow wave derived measures of neuronal synchronization. Our results are consistent with a critical role of slow waves for the beneficial effects of sleep on memory that is susceptible to natural environmental influences. Copyright © 2014 Elsevier Inc. All rights reserved.

Positive and negative generation effects in source monitoring.

PubMed

Riefer, David M; Chien, Yuchin; Reimer, Jason F

2007-10-01

Research is mixed as to whether self-generation improves memory for the source of information. We propose the hypothesis that positive generation effects (better source memory for self-generated information) occur in reality-monitoring paradigms, while negative generation effects (better source memory for externally presented information) tend to occur in external source-monitoring paradigms. This hypothesis was tested in an experiment in which participants read or generated words, followed by a memory test for the source of each word (read or generated) and the word's colour. Meiser and Bröder's (2002) multinomial model for crossed source dimensions was used to analyse the data, showing that source memory for generation (reality monitoring) was superior for the generated words, while source memory for word colour (external source monitoring) was superior for the read words. The model also revealed the influence of strong response biases in the data, demonstrating the usefulness of formal modelling when examining generation effects in source monitoring.

Do transactive memory and participative teamwork improve nurses' quality of work life?

PubMed

Brunault, Paul; Fouquereau, Evelyne; Colombat, Philippe; Gillet, Nicolas; El-Hage, Wissam; Camus, Vincent; Gaillard, Philippe

2014-03-01

Improvement in nurses' quality of work life (QWL) has become a major issue in health care organizations. We hypothesized that the level of transactive memory (defined as the way groups collectively encode, store, and retrieve knowledge) and participative teamwork (an organizational model of care based on vocational training, a specific service's care project, and regular interdisciplinary staffing) positively affect nurses' QWL. This cross-sectional study enrolled 84 ward-based psychiatric nurses. We assessed transactive memory, participative teamwork, perceived organizational justice, perceived organizational support, and QWL using psychometrically reliable and valid scales. Participative teamwork and transactive memory were positively associated with nurses' QWL. Perceived organizational support and organizational justice fully mediated the relationship between participative teamwork and QWL, but not between transactive memory and QWL. Improved transactive memory could directly improve nurses' QWL. Improved participative teamwork could improve nurses' QWL through better perceived organizational support and perceived organizational justice.

Long-Term Memory for Place Learning Is Facilitated by Expression of cAMP Response Element-Binding Protein in the Dorsal Hippocampus

ERIC Educational Resources Information Center

Brightwell, Jennifer J.; Smith, Clayton A.; Neve, Rachael L.; Colombo, Paul J.

2007-01-01

Extensive research has shown that the hippocampus is necessary for consolidation of long-term spatial memory in rodents. We reported previously that rats using a place strategy to solve a cross maze task showed sustained phosphorylation of hippocampus cyclic AMP response element-binding protein (CREB), a transcription factor implicated in…

Effect of Sentence Length and Complexity on Working Memory Performance in Hungarian Children with Specific Language Impairment (SLI): A Cross-Linguistic Comparison

ERIC Educational Resources Information Center

Marton, Klara; Schwartz, Richard G.; Farkas, Lajos; Katsnelson, Valeriya

2006-01-01

Background: English-speaking children with specific language impairment (SLI) perform more poorly than their typically developing peers in verbal working memory tasks where processing and storage are simultaneously required. Hungarian is a language with a relatively free word order and a rich agglutinative morphology. Aims: To examine the effect…

The Nature of Working Memory in Linguistic, Arithmetic and Spatial Integration Processes

ERIC Educational Resources Information Center

Fedorenko, Evelina; Gibson, Edward; Rohde, Douglas

2007-01-01

This paper reports the results of four dual-task experiments that were designed to determine the extent of domain-specificity of the verbal working memory resources used in linguistic integrations. To address this question, syntactic complexity was crossed in a 2x2 design with the complexity of a secondary task, which involved either (1)…

A Cross-Sectional and Follow-Up Functional MRI Study with a Working Memory Task in Adolescent Anorexia Nervosa

ERIC Educational Resources Information Center

Castro-Fornieles, Josefina; Caldu, Xavier; Andres-Perpina, Susana; Lazaro, Luisa; Bargallo, Nuria; Falcon, Carles; Plana, Maria Teresa; Junque, Carme

2010-01-01

Structural and functional brain abnormalities have been described in anorexia nervosa (AN). The objective of this study was to examine whether there is abnormal regional brain activation during a working memory task not associated with any emotional stimuli in adolescent patients with anorexia and to detect possible changes after weight recovery.…

Airway Memory CD4(+) T Cells Mediate Protective Immunity against Emerging Respiratory Coronaviruses.

PubMed

Zhao, Jincun; Zhao, Jingxian; Mangalam, Ashutosh K; Channappanavar, Rudragouda; Fett, Craig; Meyerholz, David K; Agnihothram, Sudhakar; Baric, Ralph S; David, Chella S; Perlman, Stanley

2016-06-21

Two zoonotic coronaviruses (CoVs)-SARS-CoV and MERS-CoV-have crossed species to cause severe human respiratory disease. Here, we showed that induction of airway memory CD4(+) T cells specific for a conserved epitope shared by SARS-CoV and MERS-CoV is a potential strategy for developing pan-coronavirus vaccines. Airway memory CD4(+) T cells differed phenotypically and functionally from lung-derived cells and were crucial for protection against both CoVs in mice. Protection was dependent on interferon-γ and required early induction of robust innate and virus-specific CD8(+) T cell responses. The conserved epitope was also recognized in SARS-CoV- and MERS-CoV-infected human leukocyte antigen DR2 and DR3 transgenic mice, indicating potential relevance in human populations. Additionally, this epitope was cross-protective between human and bat CoVs, the progenitors for many human CoVs. Vaccine strategies that induce airway memory CD4(+) T cells targeting conserved epitopes might have broad applicability in the context of new CoVs and other respiratory virus outbreaks. Copyright © 2016 Elsevier Inc. All rights reserved.

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

PubMed

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

2017-10-01

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

White matter and memory in healthy adults: Coupled changes over two years.

PubMed

Bender, Andrew R; Prindle, John J; Brandmaier, Andreas M; Raz, Naftali

2016-05-01

Numerous cross-sectional studies have used diffusion tensor imaging (DTI) to link age-related differences in white matter (WM) anisotropy and concomitant decrements in cognitive ability. Due to a dearth of longitudinal evidence, the relationship between changes in diffusion properties of WM and cognitive performance remains unclear. Here we examine the relationship between two-year changes in WM organization and cognitive performance in healthy adults (N=96, age range at baseline=18-79 years). We used latent change score models (LCSM) to evaluate changes in age-sensitive cognitive abilities - fluid intelligence and associative memory. WM changes were assessed by fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) in WM regions that are considered part of established memory networks and exhibited individual differences in change. In modeling change, we postulated reciprocal paths between baseline measures and change factors, within and between WM and cognition domains, and accounted for individual differences in baseline age. Although baseline cross-sectional memory performance was positively associated with FA and negatively with RD, longitudinal effects told an altogether different story. Independent of age, longitudinal improvements in associative memory were significantly associated with linear reductions in FA and increases in RD. The present findings demonstrate the sensitivity of DTI-derived indices to changes in the brain and cognition and affirm the importance of longitudinal models for evaluating brain-cognition relations. Copyright © 2015 Elsevier Inc. All rights reserved.

A cross-cultural perspective on aging and memory: Comparisons between Bangladesh and Sweden.

PubMed

Sternäng, Ola; Kabir, Zarina N; Hamadani, Jena D; Wahlin, Åke

2012-12-01

Most studies on cognitive aging have been conducted in high-income countries (mainly on Western populations). The main aim of this study was to compare the relative importance of predictors of episodic and semantic memory performance in older people (≥60 years) from Bangladesh (n = 400) and Sweden (n = 1,098). Hierarchical regression models were used in order to study the importance of some commonly used predictors in the two countries. A main finding was that variations in age did not have much impact on episodic and semantic memory performance in Bangladesh. Instead, sex was a strong predictor for semantic memory performance. In Sweden this pattern was reversed. In the Western world, chronological age is believed to be strongly associated with memory performance in cross-sectional studies, particularly in people greater than 60 years of age. This study indicates that the difference between the two countries (in relative importance of the predictors included in this study) is mainly due to the fact that years of education is connected to age in the Western world but to sex in Bangladesh. It remains to be examined whether earlier selective survival is also responsible for the relative absence of cognitive age differences in Bangladesh. © 2012 The Institute of Psychology, Chinese Academy of Sciences and Blackwell Publishing Asia Pty Ltd.

White Matter and Memory in Healthy Adults: Coupled Changes over Two Years

PubMed Central

Bender, Andrew R.; Prindle, John J.; Brandmaier, Andreas M.; Raz, Naftali

2016-01-01

Numerous cross-sectional studies have used diffusion tensor imaging (DTI) to link age-related differences in white matter (WM) anisotropy and concomitant decrements in cognitive ability. Due to a dearth of longitudinal evidence, the relationship between changes in diffusion properties of WM and cognitive performance remains unclear. Here we examine the relationship between two-year changes in WM organization and cognitive performance in healthy adults (N = 96, age range at baseline = 18–79 years). We used latent change score models (LCSM) to evaluate changes in age-sensitive cognitive abilities - fluid intelligence and associative memory. WM changes were assessed by fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) in WM regions that are considered part of established memory networks and exhibited individual differences in change. In modeling change, we postulated reciprocal paths between baseline measures and change factors, within and between WM and cognition domains, and accounted for individual differences in baseline age. Although baseline cross-sectional memory performance was positively associated with FA and negatively with RD, longitudinal effects told an altogether different story. Independent of age, longitudinal improvements in associative memory were significantly associated with linear reductions in FA and increases in RD. The present findings demonstrate the sensitivity of DTI-derived indices to changes in the brain and cognition and affirm the importance of longitudinal models for evaluating brain-cognition relations. PMID:26545457

Differential memory in the earth's magnetotail

NASA Technical Reports Server (NTRS)

Burkhart, G. R.; Chen, J.

1991-01-01

The process of 'differential memory' in the earth's magnetotail is studied in the framework of the modified Harris magnetotail geometry. It is verified that differential memory can generate non-Maxwellian features in the modified Harris field model. The time scales and the potentially observable distribution functions associated with the process of differential memory are investigated, and it is shown that non-Maxwelllian distributions can evolve as a test particle response to distribution function boundary conditions in a Harris field magnetotail model. The non-Maxwellian features which arise from distribution function mapping have definite time scales associated with them, which are generally shorter than the earthward convection time scale but longer than the typical Alfven crossing time.

Measuring Memory Reactivation With Functional MRI: Implications for Psychological Theory.

PubMed

Levy, Benjamin J; Wagner, Anthony D

2013-01-01

Environmental cues often remind us of earlier experiences by triggering the reactivation of memories of events past. Recent evidence suggests that memory reactivation can be observed using functional MRI and that distributed pattern analyses can even provide evidence of reactivation on individual trials. The ability to measure memory reactivation offers unique and powerful leverage on theoretical issues of long-standing interest in cognitive psychology, providing a means to address questions that have proven difficult to answer with behavioral data alone. In this article, we consider three instances. First, reactivation measures can indicate whether memory-based inferences (i.e., generalization) arise through the encoding of integrated cross-event representations or through the flexible expression of separable event memories. Second, online measures of memory reactivation may inform theories of forgetting by providing information about when competing memories are reactivated during competitive retrieval situations. Finally, neural reactivation may provide a window onto the role of replay in memory consolidation. The ability to track memory reactivation, including at the individual trial level, provides unique leverage that is not afforded by behavioral measures and thus promises to shed light on such varied topics as generalization, integration, forgetting, and consolidation. © The Author(s) 2013.

New Mode For Single-Event Upsets

NASA Technical Reports Server (NTRS)

Zoutendyk, John A.; Smith, Lawrence S.; Soli, George A.; Lo, Roger Y.

1988-01-01

Report presents theory and experimental data regarding newly discovered mode for single-event upsets, (SEU's) in complementary metal-oxide/semiconductor, static random-access memories, CMOS SRAM's. SEU cross sections larger than those expected from previously known modes given rise to speculation regarding additional mode, and subsequent cross-section measurements appear to confirm speculation.

Directional hippocampal-prefrontal interactions during working memory.

PubMed

Liu, Tiaotiao; Bai, Wenwen; Xia, Mi; Tian, Xin

2018-02-15

Working memory refers to a system that is essential for performing complex cognitive tasks such as reasoning, comprehension and learning. Evidence shows that hippocampus (HPC) and prefrontal cortex (PFC) play important roles in working memory. The HPC-PFC interaction via theta-band oscillatory synchronization is critical for successful execution of working memory. However, whether one brain region is leading or lagging relative to another is still unclear. Therefore, in the present study, we simultaneously recorded local field potentials (LFPs) from rat ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC) and while the rats performed a Y-maze working memory task. We then applied instantaneous amplitudes cross-correlation method to calculate the time lag between PFC and vHPC to explore the functional dynamics of the HPC-PFC interaction. Our results showed a strong lead from vHPC to mPFC preceded an animal's correct choice during the working memory task. These findings suggest the vHPC-leading interaction contributes to the successful execution of working memory. Copyright © 2017. Published by Elsevier B.V.

High-strain slide-ring shape-memory polycaprolactone-based polyurethane.

PubMed

Wu, Ruiqing; Lai, Jingjuan; Pan, Yi; Zheng, Zhaohui; Ding, Xiaobin

2018-06-06

To enable shape-memory polymer networks to achieve recoverable high deformability with a simultaneous high shape-fixity ratio and shape-recovery ratio, novel semi-crystalline slide-ring shape-memory polycaprolactone-based polyurethane (SR-SMPCLU) with movable net-points constructed by a topologically interlocked slide-ring structure was designed and fabricated. The SR-SMPCLU not only exhibited good shape fixity, almost complete shape recovery, and a fast shape-recovery speed, it also showed an outstanding recoverable high-strain capacity with 95.83% Rr under a deformation strain of 1410% due to the pulley effect of the topological slide-ring structure. Furthermore, the SR-SMPCLU system maintained excellent shape-memory performance with increasing the training cycle numbers at 45% and even 280% deformation strain. The effects of the slide-ring cross-linker content, deformation strain, and successive shape-memory cycles on the shape-memory performance were investigated. A possible mechanism for the shape-memory effect of the SR-SMPCLU system is proposed.

Large conditional single-photon cross-phase modulation

PubMed Central

Hosseini, Mahdi; Duan, Yiheng; Vuletić, Vladan

2016-01-01

Deterministic optical quantum logic requires a nonlinear quantum process that alters the phase of a quantum optical state by π through interaction with only one photon. Here, we demonstrate a large conditional cross-phase modulation between a signal field, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. This approach avoids fundamental limitations associated with multimode effects for traveling optical photons. We measure a conditional cross-phase shift of π/6 (and up to π/3 by postselection on photons that remain in the system longer than average) between the retrieved signal and control photons, and confirm deterministic entanglement between the signal and control modes by extracting a positive concurrence. By upgrading to a state-of-the-art cavity, our system can reach a coherent phase shift of π at low loss, enabling deterministic and universal photonic quantum logic. PMID:27519798

T inflammatory memory CD8 T cells participate to antiviral response and generate secondary memory cells with an advantage in XCL1 production.

PubMed

Jubin, Virginie; Ventre, Erwan; Leverrier, Yann; Djebali, Sophia; Mayol, Katia; Tomkowiak, Martine; Mafille, Julien; Teixeira, Marie; Teoh, Denise Y-L; Lina, Bruno; Walzer, Thierry; Arpin, Christophe; Marvel, Jacqueline

2012-06-01

Besides the classically described subsets of memory CD8 T cells generated under infectious conditions, are T inflammatory memory cells generated under sterile priming conditions, such as sensitization to allergens. Although not fully differentiated as pathogen-induced memory cells, they display memory properties that distinguish them from naive CD8 T cells. Given these memory cells are generated in an antigen-specific context that is devoid of pathogen-derived danger signals and CD4 T cell help, we herein questioned whether they maintained their activation and differentiation potential, could be recruited in an immune response directed against a pathogen expressing their cognate antigen and further differentiate in fully competent secondary memory cells. We show that T inflammatory memory cells can indeed take part to the immune response triggered by a viral infection, differentiate into secondary effectors and further generate typical central memory CD8 T cells and effector memory CD8 T cells. Furthermore, the secondary memory cells they generate display a functional advantage over primary memory cells in their capacity to produce TNF-α and the XCL1 chemokine. These results suggest that cross-reactive stimulations and differentiation of cells directed against allergens or self into fully competent pathogen-induced memory cells might have incidences in inflammatory immuno-pathologies.

Sources and characteristics of acoustic emissions from mechanically stressed geologic granular media — A review

NASA Astrophysics Data System (ADS)

Michlmayr, Gernot; Cohen, Denis; Or, Dani

2012-05-01

The formation of cracks and emergence of shearing planes and other modes of rapid macroscopic failure in geologic granular media involve numerous grain scale mechanical interactions often generating high frequency (kHz) elastic waves, referred to as acoustic emissions (AE). These acoustic signals have been used primarily for monitoring and characterizing fatigue and progressive failure in engineered systems, with only a few applications concerning geologic granular media reported in the literature. Similar to the monitoring of seismic events preceding an earthquake, AE may offer a means for non-invasive, in-situ, assessment of mechanical precursors associated with imminent landslides or other types of rapid mass movements (debris flows, rock falls, snow avalanches, glacier stick-slip events). Despite diverse applications and potential usefulness, a systematic description of the AE method and its relevance to mechanical processes in Earth sciences is lacking. This review is aimed at providing a sound foundation for linking observed AE with various micro-mechanical failure events in geologic granular materials, not only for monitoring of triggering events preceding mass mobilization, but also as a non-invasive tool in its own right for probing the rich spectrum of mechanical processes at scales ranging from a single grain to a hillslope. We review first studies reporting use of AE for monitoring of failure in various geologic materials, and describe AE generating source mechanisms in mechanically stressed geologic media (e.g., frictional sliding, micro-crackling, particle collisions, rupture of water bridges, etc.) including AE statistical features, such as frequency content and occurrence probabilities. We summarize available AE sensors and measurement principles. The high sampling rates of advanced AE systems enable detection of numerous discrete failure events within a volume and thus provide access to statistical descriptions of progressive collapse of systems with many interacting mechanical elements such as the fiber bundle model (FBM). We highlight intrinsic links between AE characteristics and established statistical models often used in structural engineering and material sciences, and outline potential applications for failure prediction and early-warning using the AE method in combination with the FBM. The biggest challenge to application of the AE method for field applications is strong signal attenuation. We provide an outlook for overcoming such limitations considering emergence of a class of fiber-optic based distributed AE sensors and deployment of acoustic waveguides as part of monitoring networks.

Modality specificity in the cerebro-cerebellar neurocircuitry during working memory.

PubMed

Ng, H B Tommy; Kao, K-L Cathy; Chan, Y C; Chew, Effie; Chuang, K H; Chen, S H Annabel

2016-05-15

Previous studies have suggested cerebro-cerebellar circuitry in working memory. The present fMRI study aims to distinguish differential cerebro-cerebellar activation patterns in verbal and visual working memory, and employs a quantitative analysis to deterimine lateralization of the activation patterns observed. Consistent with Chen and Desmond (2005a,b) predictions, verbal working memory activated a cerebro-cerebellar circuitry that comprised left-lateralized language-related brain regions including the inferior frontal and posterior parietal areas, and subcortically, right-lateralized superior (lobule VI) and inferior cerebellar (lobule VIIIA/VIIB) areas. In contrast, a distributed network of bilateral inferior frontal and inferior temporal areas, and bilateral superior (lobule VI) and inferior (lobule VIIB) cerebellar areas, was recruited during visual working memory. Results of the study verified that a distinct cross cerebro-cerebellar circuitry underlies verbal working memory. However, a neural circuitry involving specialized brain areas in bilateral neocortical and bilateral cerebellar hemispheres subserving visual working memory is observed. Findings are discussed in the light of current models of working memory and data from related neuroimaging studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Improving visual spatial working memory in younger and older adults: effects of cross-modal cues.

PubMed

Curtis, Ashley F; Turner, Gary R; Park, Norman W; Murtha, Susan J E

2017-11-06

Spatially informative auditory and vibrotactile (cross-modal) cues can facilitate attention but little is known about how similar cues influence visual spatial working memory (WM) across the adult lifespan. We investigated the effects of cues (spatially informative or alerting pre-cues vs. no cues), cue modality (auditory vs. vibrotactile vs. visual), memory array size (four vs. six items), and maintenance delay (900 vs. 1800 ms) on visual spatial location WM recognition accuracy in younger adults (YA) and older adults (OA). We observed a significant interaction between spatially informative pre-cue type, array size, and delay. OA and YA benefitted equally from spatially informative pre-cues, suggesting that attentional orienting prior to WM encoding, regardless of cue modality, is preserved with age.  Contrary to predictions, alerting pre-cues generally impaired performance in both age groups, suggesting that maintaining a vigilant state of arousal by facilitating the alerting attention system does not help visual spatial location WM.

Differential cross-reactivity of monoclonal antibody OPD4 (anti-CD45RO) in macaques.

PubMed

Wang, Xiaolei; Pahar, Bapi; Rasmussen, Terri; Alvarez, Xavier; Dufour, Jason; Rasmussen, Kelsi; Lackner, Andrew A; Veazey, Ronald S

2008-01-01

Immunologic research in nonhuman primates is occasionally limited by the availability of reagents that cross-react in nonhuman primates. One major limitation has been the lack of a monoclonal antibody to CD45RO. Although the monoclonal antibody UCHL-1 is used to detect CD45RO isoforms in humans, it does not react with nonhuman primates, mandating the use of alternative strategies to define "memory" T cell responses in nonhuman primates. The current study examined the reactivity and specificity of another antibody against CD45RO, clone OPD4, in macaques. Here we demonstrate that OPD4 specifically labels memory CD4+ T cells in approximately 44% of rhesus macaques (Macaca mulatta) of Indian but not Chinese origin. In contrast, tissues from pigtail macaques (Macaca nemestrina) react with this clone, indicating that OPD4 may be useful for examining memory CD4+ T cells in certain macaques, but its utility may be limited in other species or even among individual macaques.

Contact and other-race effects in configural and component processing of faces.

PubMed

Rhodes, Gillian; Ewing, Louise; Hayward, William G; Maurer, Daphne; Mondloch, Catherine J; Tanaka, James W

2009-11-01

Other-race faces are generally recognized more poorly than own-race faces. There has been a long-standing interest in the extent to which differences in contact contribute to this other-race effect (ORE). Here, we examined the effect of contact on two distinct aspects of face memory, memory for configuration and for components, both of which are better for own-race than other-race faces. Configural and component memory were measured using recognition memory tests with intact study faces and blurred (isolates memory for configuration) and scrambled (isolates memory for components) test faces, respectively. Our participants were a large group of ethnically Chinese individuals who had resided in Australia for varying lengths of time, from a few weeks to 26 years. We found that time in a Western country significantly (negatively) predicted the size of the ORE for configural, but not component, memory. There was also a trend for earlier age of arrival to predict smaller OREs in configural, but not component, memory. These results suggest that memory for configural information in other-race faces improves with experience with such faces. However, as found for recognition memory generally, the contact effects were small, indicating that other factors must play a substantial role in cross-race differences in face memory.

The effect of functional hearing loss and age on long- and short-term visuospatial memory: evidence from the UK biobank resource.

PubMed

Rönnberg, Jerker; Hygge, Staffan; Keidser, Gitte; Rudner, Mary

2014-01-01

The UK Biobank offers cross-sectional epidemiological data collected on >500,000 individuals in the UK between 40 and 70 years of age. Using the UK Biobank data, the aim of this study was to investigate the effects of functional hearing loss and hearing aid usage on visuospatial memory function. This selection of variables resulted in a sub-sample of 138,098 participants after discarding extreme values. A digit triplets functional hearing test was used to divide the participants into three groups: poor, insufficient and normal hearers. We found negative relationships between functional hearing loss and both visuospatial working memory (i.e., a card pair matching task) and visuospatial, episodic long-term memory (i.e., a prospective memory task), with the strongest association for episodic long-term memory. The use of hearing aids showed a small positive effect for working memory performance for the poor hearers, but did not have any influence on episodic long-term memory. Age also showed strong main effects for both memory tasks and interacted with gender and education for the long-term memory task. Broader theoretical implications based on a memory systems approach will be discussed and compared to theoretical alternatives.

The Impact of Nitinol Staples on the Compressive Forces, Contact Area, and Mechanical Properties in Comparison to a Claw Plate and Crossed Screws for the First Tarsometatarsal Arthrodesis.

PubMed

Aiyer, Amiethab; Russell, Nicholas A; Pelletier, Matthew H; Myerson, Mark; Walsh, William R

2016-06-01

Background The optimal fixation method for the first tarsometatarsal arthrodesis remains controversial. This study aimed to develop a reproducible first tarsometatarsal testing model to evaluate the biomechanical performance of different reconstruction techniques. Methods Crossed screws or a claw plate were compared with a single or double shape memory alloy staple configuration in 20 Sawbones models. Constructs were mechanically tested in 4-point bending to 1, 2, and 3 mm of plantar displacement. The joint contact force and area were measured at time zero, and following 1 and 2 mm of bending. Peak load, stiffness, and plantar gapping were determined. Results Both staple configurations induced a significantly greater contact force and area across the arthrodesis than the crossed screw and claw plate constructs at all measurements. The staple constructs completely recovered their plantar gapping following each test. The claw plate generated the least contact force and area at the joint interface and had significantly greater plantar gapping than all other constructs. The crossed screw constructs were significantly stiffer and had significantly less plantar gapping than the other constructs, but this gapping was not recoverable. Conclusions Crossed screw fixation provides a rigid arthrodesis with limited compression and contact footprint across the joint. Shape memory alloy staples afford dynamic fixation with sustained compression across the arthrodesis. A rigid polyurethane foam model provides an anatomically relevant comparison for evaluating the interface between different fixation techniques. Clinical Relevance The dynamic nature of shape memory alloy staples offers the potential to permit early weight bearing and could be a useful adjunctive device to impart compression across an arthrodesis of the first tarsometatarsal joint. Therapeutic, Level V: Bench testing. © 2015 The Author(s).

Dopamine D1 signaling organizes network dynamics underlying working memory.

PubMed

Roffman, Joshua L; Tanner, Alexandra S; Eryilmaz, Hamdi; Rodriguez-Thompson, Anais; Silverstein, Noah J; Ho, New Fei; Nitenson, Adam Z; Chonde, Daniel B; Greve, Douglas N; Abi-Dargham, Anissa; Buckner, Randy L; Manoach, Dara S; Rosen, Bruce R; Hooker, Jacob M; Catana, Ciprian

2016-06-01

Local prefrontal dopamine signaling supports working memory by tuning pyramidal neurons to task-relevant stimuli. Enabled by simultaneous positron emission tomography-magnetic resonance imaging (PET-MRI), we determined whether neuromodulatory effects of dopamine scale to the level of cortical networks and coordinate their interplay during working memory. Among network territories, mean cortical D1 receptor densities differed substantially but were strongly interrelated, suggesting cross-network regulation. Indeed, mean cortical D1 density predicted working memory-emergent decoupling of the frontoparietal and default networks, which respectively manage task-related and internal stimuli. In contrast, striatal D1 predicted opposing effects within these two networks but no between-network effects. These findings specifically link cortical dopamine signaling to network crosstalk that redirects cognitive resources to working memory, echoing neuromodulatory effects of D1 signaling on the level of cortical microcircuits.

Brain oscillatory substrates of visual short-term memory capacity.

PubMed

Sauseng, Paul; Klimesch, Wolfgang; Heise, Kirstin F; Gruber, Walter R; Holz, Elisa; Karim, Ahmed A; Glennon, Mark; Gerloff, Christian; Birbaumer, Niels; Hummel, Friedhelm C

2009-11-17

The amount of information that can be stored in visual short-term memory is strictly limited to about four items. Therefore, memory capacity relies not only on the successful retention of relevant information but also on efficient suppression of distracting information, visual attention, and executive functions. However, completely separable neural signatures for these memory capacity-limiting factors remain to be identified. Because of its functional diversity, oscillatory brain activity may offer a utile solution. In the present study, we show that capacity-determining mechanisms, namely retention of relevant information and suppression of distracting information, are based on neural substrates independent of each other: the successful maintenance of relevant material in short-term memory is associated with cross-frequency phase synchronization between theta (rhythmical neural activity around 5 Hz) and gamma (> 50 Hz) oscillations at posterior parietal recording sites. On the other hand, electroencephalographic alpha activity (around 10 Hz) predicts memory capacity based on efficient suppression of irrelevant information in short-term memory. Moreover, repetitive transcranial magnetic stimulation at alpha frequency can modulate short-term memory capacity by influencing the ability to suppress distracting information. Taken together, the current study provides evidence for a double dissociation of brain oscillatory correlates of visual short-term memory capacity.

On-the-fly Doppler broadening of unresolved resonance region cross sections

DOE PAGES

Walsh, Jonathan A.; Forget, Benoit; Smith, Kord S.; ...

2017-07-29

In this paper, two methods for computing temperature-dependent unresolved resonance region cross sections on-the-fly within continuous-energy Monte Carlo neutron transport simulations are presented. The first method calculates Doppler broadened cross sections directly from zero-temperature average resonance parameters. In a simulation, at each event that requires cross section values, a realization of unresolved resonance parameters is generated about the desired energy and temperature-dependent single-level Breit-Wigner resonance cross sections are computed directly via the analytical Ψ-x Doppler integrals. The second method relies on the generation of equiprobable cross section magnitude bands on an energy-temperature mesh. Within a simulation, the bands are sampledmore » and interpolated in energy and temperature to obtain cross section values on-the-fly. Both of the methods, as well as their underlying calculation procedures, are verified numerically in extensive code-to-code comparisons. Energy-dependent pointwise cross sections calculated with the newly-implemented procedures are shown to be in excellent agreement with those calculated by a widely-used nuclear data processing code. Relative differences at or below 0.1% are observed. Integral criticality benchmark results computed with the proposed methods are shown to reproduce those computed with a state-of-the-art processed nuclear data library very well. In simulations of fast spectrum systems which are highly-sensitive to the representation of cross section data in the unresolved region, k-eigenvalue and neutron flux spectra differences of <10 pcm and <1.0% are observed, respectively. The direct method is demonstrated to be well-suited to the calculation of reference solutions — against which results obtained with a discretized representation may be assessed — as a result of its treatment of the energy, temperature, and cross section magnitude variables as continuous. Also, because there is no pre-processed data to store (only temperature-independent average resonance parameters) the direct method is very memory-efficient. Typically, only a few kB of memory are needed to store all required unresolved region data for a single nuclide. However, depending on the details of a particular simulation, performing URR cross section calculations on-the-fly can significantly increase simulation times. Alternatively, the method of interpolating equiprobable probability bands is demonstrated to produce results that are as accurate as the direct reference solutions, to within arbitrary precision, with high computational efficiency in terms of memory requirements and simulation time. Analyses of a fast spectrum system show that interpolation on a coarse energy-temperature mesh can be used to reproduce reference k-eigenvalue results obtained with cross sections calculated continuously in energy and directly at an exact temperature to within <10 pcm. Probability band data on a mesh encompassing the range of temperatures relevant to reactor analysis usually require around 100 kB of memory per nuclide. Finally, relative to the case in which probability table data generated at a single, desired temperature are used, minor increases in simulation times are observed when probability band interpolation is employed.« less

A Proposal of TLS Implementation for Cross Certification Model

NASA Astrophysics Data System (ADS)

Kaji, Tadashi; Fujishiro, Takahiro; Tezuka, Satoru

Today, TLS is widely used for achieving a secure communication system. And TLS is used PKI for server authentication and/or client authentication. However, its PKI environment, which is called as “multiple trust anchors environment,” causes the problem that the verifier has to maintain huge number of CA certificates in the ubiquitous network because the increase of terminals connected to the network brings the increase of CAs. However, most of terminals in the ubiquitous network will not have enough memory to hold such huge number of CA certificates. Therefore, another PKI environment, “cross certification environment”, is useful for the ubiquitous network. But, because current TLS is designed for the multiple trust anchors model, TLS cannot work efficiently on the cross-certification model. This paper proposes a TLS implementation method to support the cross certification model efficiently. Our proposal reduces the size of exchanged messages between the TLS client and the TLS server during the handshake process. Therefore, our proposal is suitable for implementing TLS in the terminals that do not have enough computing power and memory in ubiquitous network.

BDNF val66met Polymorphism Affects Aging of Multiple Types of Memory

PubMed Central

Kennedy, Kristen M.; Reese, Elizabeth D.; Horn, Marci M.; Sizemore, April N.; Unni, Asha K.; Meerbrey, Michael E.; Kalich, Allan G.; Rodrigue, Karen M.

2014-01-01

The BDNF val66met polymorphism (rs6265) influences activity-dependent secretion of brain-derived neurotrophic factor in the synapse, which is crucial for learning and memory. Individuals homozygous or heterozygous for the met allele have lower BDNF secretion than val homozygotes and may be at risk for reduced declarative memory performance, but it remains unclear which types of declarative memory may be affected and how aging of memory across the lifespan is impacted by the BDNF val66met polymorphism. This cross-sectional study investigated the effects of BDNF polymorphism on multiple indices of memory (item, associative, prospective, subjective complaints) in a lifespan sample of 116 healthy adults aged 20-93 years. Advancing age showed a negative effect on item, associative and prospective memory, but not on subjective memory complaints. For item and prospective memory, there were significant age x BDNF group interactions, indicating the adverse effect of age on memory performance across the lifespan was much stronger in the BDNF met carriers than for the val homozygotes. BDNF met carriers also endorsed significantly greater subjective memory complaints, regardless of age, and showed a trend (p < .07) toward poorer associative memory performance compared to val homozygotes. These results suggest that genetic predisposition to the availability of brain-derived neurotrophic factor, by way of the BDNF val66met polymorphism, exerts an influence on multiple indices of episodic memory – in some cases in all individuals regardless of age (subjective memory and perhaps associative memory), in others as an exacerbation of age-related differences in memory across the lifespan (item and prospective memory). PMID:25264352

Quantum memory with optically trapped atoms.

PubMed

Chuu, Chih-Sung; Strassel, Thorsten; Zhao, Bo; Koch, Markus; Chen, Yu-Ao; Chen, Shuai; Yuan, Zhen-Sheng; Schmiedmayer, Jörg; Pan, Jian-Wei

2008-09-19

We report the experimental demonstration of quantum memory for collective atomic states in a far-detuned optical dipole trap. Generation of the collective atomic state is heralded by the detection of a Raman scattered photon and accompanied by storage in the ensemble of atoms. The optical dipole trap provides confinement for the atoms during the quantum storage while retaining the atomic coherence. We probe the quantum storage by cross correlation of the photon pair arising from the Raman scattering and the retrieval of the atomic state stored in the memory. Nonclassical correlations are observed for storage times up to 60 mus.

Emotional state and local versus global spatial memory.

PubMed

Brunyé, Tad T; Mahoney, Caroline R; Augustyn, Jason S; Taylor, Holly A

2009-02-01

The present work investigated the effects of participant emotional state on global versus local memory for map-based information. Participants were placed into one of four emotion induction groups, crossing high and low arousal with positive and negative valence, or a control group. They then studied a university campus map and completed two memory tests, free recall and spatial statement verification. Converging evidence from these two tasks demonstrated that arousal amplifies symbolic distance effects and leads to a globally-focused spatial mental representation, partially at the expense of local knowledge. These results were found for both positively- and negatively-valenced affective states. The present study is the first investigation of emotional effects on spatial memory, and has implications for theories of emotion and spatial cognition.

Multimorbidity and its relation to subjective memory complaints in a large general population of older adults.

PubMed

Aarts, S; van den Akker, M; Hajema, K J; van Ingen, A M; Metsemakers, J F M; Verhey, F R J; van Boxtel, M P J

2011-05-01

Multimorbidity has been suggested to be associated with a variety of negative health-related outcomes. The present study was designed to evaluate the association between multimorbidity and subjective memory complaints. This cross-sectional study was based on data obtained from a postal survey designed by the Public Health Service (Gemeentelijke Gezondheids Dienst, GGD) involving 15,188 persons aged 55 years and over living independently in Limburg, the Netherlands. Multivariate logistic regression analyses, adjusted for potentially important covariates, were performed to evaluate the association between self-reported multimorbidity and three outcomes related to subjective memory complaints. Multimorbidity was indeed related to subjective memory complaints. The association between multimorbidity and subjective memory complaints was positively influenced by age. Moreover, multimorbidity was related to the degree of worrying about memory complaints in people who perceived themselves as forgetful. Multimorbidity was also associated with reporting a larger increase in these subjective memory complaints during the past year. In this latter case, multimorbidity had more prognostic capability in men than in women. Psychological distress was related to all three subjective memory-related outcome measures. In our sample, which was representative of the Dutch population, multimorbidity was associated with subjective memory complaints. The relationship between multimorbidity and subjective memory complaints differed between men and women and between age groups.

Changes of EEG Spectra and Functional Connectivity during an Object-Location Memory Task in Alzheimer's Disease.

PubMed

Han, Yuliang; Wang, Kai; Jia, Jianjun; Wu, Weiping

2017-01-01

Object-location memory is particularly fragile and specifically impaired in Alzheimer's disease (AD) patients. Electroencephalogram (EEG) was utilized to objectively measure memory impairment for memory formation correlates of EEG oscillatory activities. We aimed to construct an object-location memory paradigm and explore EEG signs of it. Two groups of 20 probable mild AD patients and 19 healthy older adults were included in a cross-sectional analysis. All subjects took an object-location memory task. EEG recordings performed during object-location memory tasks were compared between the two groups in the two EEG parameters (spectral parameters and phase synchronization). The memory performance of AD patients was worse than that of healthy elderly adults The power of object-location memory of the AD group was significantly higher than the NC group (healthy elderly adults) in the alpha band in the encoding session, and alpha and theta bands in the retrieval session. The channels-pairs the phase lag index value of object-location memory in the AD group was clearly higher than the NC group in the delta, theta, and alpha bands in encoding sessions and delta and theta bands in retrieval sessions. The results provide support for the hypothesis that the AD patients may use compensation mechanisms to remember the items and episode.

Postencoding cognitive processes in the cross-race effect: Categorization and individuation during face recognition.

PubMed

Ho, Michael R; Pezdek, Kathy

2016-06-01

The cross-race effect (CRE) describes the finding that same-race faces are recognized more accurately than cross-race faces. According to social-cognitive theories of the CRE, processes of categorization and individuation at encoding account for differential recognition of same- and cross-race faces. Recent face memory research has suggested that similar but distinct categorization and individuation processes also occur postencoding, at recognition. Using a divided-attention paradigm, in Experiments 1A and 1B we tested and confirmed the hypothesis that distinct postencoding categorization and individuation processes occur during the recognition of same- and cross-race faces. Specifically, postencoding configural divided-attention tasks impaired recognition accuracy more for same-race than for cross-race faces; on the other hand, for White (but not Black) participants, postencoding featural divided-attention tasks impaired recognition accuracy more for cross-race than for same-race faces. A social categorization paradigm used in Experiments 2A and 2B tested the hypothesis that the postencoding in-group or out-group social orientation to faces affects categorization and individuation processes during the recognition of same-race and cross-race faces. Postencoding out-group orientation to faces resulted in categorization for White but not for Black participants. This was evidenced by White participants' impaired recognition accuracy for same-race but not for cross-race out-group faces. Postencoding in-group orientation to faces had no effect on recognition accuracy for either same-race or cross-race faces. The results of Experiments 2A and 2B suggest that this social orientation facilitates White but not Black participants' individuation and categorization processes at recognition. Models of recognition memory for same-race and cross-race faces need to account for processing differences that occur at both encoding and recognition.

Vortex-Core Reversal Dynamics: Towards Vortex Random Access Memory

NASA Astrophysics Data System (ADS)

Kim, Sang-Koog

2011-03-01

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

Can observations look back to the beginning of inflation?

NASA Astrophysics Data System (ADS)

Wetterich, C.

2016-03-01

The cosmic microwave background can measure the inflaton potential only if inflation lasts sufficiently long before the time of horizon crossing of observable fluctuations, such that non-linear effects in the time evolution of Green's functions lead to a loss of memory of initial conditions for the ultraviolet tail of the spectrum. Within a derivative expansion of the quantum effective action for an interacting scalar field we discuss the most general solution for the correlation function, including arbitrary pure and mixed quantum states. In this approximation no loss of memory occurs - cosmic microwave observations see the initial spectrum at the beginning of inflation, processed only mildly by the scale-violating effects at horizon crossing induced by the inflaton potential.

Mechanical properties and shape memory effect of thermal-responsive polymer based on PVA

NASA Astrophysics Data System (ADS)

Lin, Liulan; Zhang, Lingfeng; Guo, Yanwei

2018-01-01

In this study, the effect of content of glutaraldehyde (GA) on the shape memory behavior of a shape memory polymer based on polyvinyl alcohol chemically cross-linked with GA was investigated. Thermal-responsive shape memory composites with three different GA levels, GA-PVA (3 wt%, 5 wt%, 7 wt%), were prepared by particle melting, mold forming and freeze-drying technique. The mechanical properties, thermal properties and shape memory behavior were measured by differential scanning calorimeter, physical bending test and cyclic thermo-mechanical test. The addition of GA to PVA led to a steady shape memory transition temperature and an improved mechanical compressive strength. The composite with 5 wt% of GA exhibited the best shape recoverability. Further increase in the crosslinking agent content of GA would reduce the recovery force and prolong the recovery time due to restriction in the movement of the soft PVA chain segments. These results provide important information for the study on materials in 4D printing.

Influence of reward motivation on human declarative memory.

PubMed

Miendlarzewska, Ewa A; Bavelier, Daphne; Schwartz, Sophie

2016-02-01

Motivational relevance can prioritize information for memory encoding and consolidation based on reward value. In this review, we pinpoint the possible psychological and neural mechanisms by which reward promotes learning, from guiding attention to enhancing memory consolidation. We then discuss how reward value can spill-over from one conditioned stimulus to a non-conditioned stimulus. Such generalization can occur across perceptually similar items or through more complex relations, such as associative or logical inferences. Existing evidence suggests that the neurotransmitter dopamine boosts the formation of declarative memory for rewarded information and may also control the generalization of reward values. In particular, temporally-correlated activity in the hippocampus and in regions of the dopaminergic circuit may mediate value-based decisions and facilitate cross-item integration. Given the importance of generalization in learning, our review points to the need to study not only how reward affects later memory but how learned reward values may generalize to related representations and ultimately alter memory structure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Old Brains Come Uncoupled in Sleep: Slow Wave-Spindle Synchrony, Brain Atrophy, and Forgetting.

PubMed

Helfrich, Randolph F; Mander, Bryce A; Jagust, William J; Knight, Robert T; Walker, Matthew P

2018-01-03

The coupled interaction between slow-wave oscillations and sleep spindles during non-rapid-eye-movement (NREM) sleep has been proposed to support memory consolidation. However, little evidence in humans supports this theory. Moreover, whether such dynamic coupling is impaired as a consequence of brain aging in later life, contributing to cognitive and memory decline, is unknown. Combining electroencephalography (EEG), structural MRI, and sleep-dependent memory assessment, we addressed these questions in cognitively normal young and older adults. Directional cross-frequency coupling analyses demonstrated that the slow wave governs a precise temporal coordination of sleep spindles, the quality of which predicts overnight memory retention. Moreover, selective atrophy within the medial frontal cortex in older adults predicted a temporal dispersion of this slow wave-spindle coupling, impairing overnight memory consolidation and leading to forgetting. Prefrontal-dependent deficits in the spatiotemporal coordination of NREM sleep oscillations therefore represent one pathway explaining age-related memory decline. Copyright © 2017 Elsevier Inc. All rights reserved.

Cross-cultural differences in memory: the role of culture-based stereotypes about aging.

PubMed

Yoon, C; Hasher, L; Feinberg, F; Rahhal, T A; Winocur, G

2000-12-01

The extent to which cultural stereotypes about aging contribute to age differences in memory performance is investigated by comparing younger and older Anglophone Canadians to demographically matched Chinese Canadians, who tend to hold more positive views of aging. Four memory tests were administered. In contrast to B. Levy and E. Langer's (1994) findings, younger adults in both cultural groups outperformed their older comparison group on all memory tests. For 2 tests, which made use of visual stimuli resembling ideographic characters in written Chinese, the older Chinese Canadians approached, but did not reach, the performance achieved by their younger counterparts, as well as outperformed the older Anglophone Canadians. However, on the other two tests, which assess memory for complex figures and abstract designs, no differences were observed between the older Chinese and Anglophone Canadians. Path analysis results suggest that this pattern of findings is not easily attributed to a wholly culturally based account of age differences in memory performance.

Flexible and twistable non-volatile memory cell array with all-organic one diode-one resistor architecture.

PubMed

Ji, Yongsung; Zeigler, David F; Lee, Dong Su; Choi, Hyejung; Jen, Alex K-Y; Ko, Heung Cho; Kim, Tae-Wook

2013-01-01

Flexible organic memory devices are one of the integral components for future flexible organic electronics. However, high-density all-organic memory cell arrays on malleable substrates without cross-talk have not been demonstrated because of difficulties in their fabrication and relatively poor performances to date. Here we demonstrate the first flexible all-organic 64-bit memory cell array possessing one diode-one resistor architectures. Our all-organic one diode-one resistor cell exhibits excellent rewritable switching characteristics, even during and after harsh physical stresses. The write-read-erase-read output sequence of the cells perfectly correspond to the external pulse signal regardless of substrate deformation. The one diode-one resistor cell array is clearly addressed at the specified cells and encoded letters based on the standard ASCII character code. Our study on integrated organic memory cell arrays suggests that the all-organic one diode-one resistor cell architecture is suitable for high-density flexible organic memory applications in the future.

Working Memory and Speech Recognition in Noise under Ecologically Relevant Listening Conditions: Effects of Visual Cues and Noise Type among Adults with Hearing Loss

ERIC Educational Resources Information Center

Miller, Christi W.; Stewart, Erin K.; Wu, Yu-Hsiang; Bishop, Christopher; Bentler, Ruth A.; Tremblay, Kelly

2017-01-01

Purpose: This study evaluated the relationship between working memory (WM) and speech recognition in noise with different noise types as well as in the presence of visual cues. Method: Seventy-six adults with bilateral, mild to moderately severe sensorineural hearing loss (mean age: 69 years) participated. Using a cross-sectional design, 2…

BDNF val66met polymorphism affects aging of multiple types of memory.

PubMed

Kennedy, Kristen M; Reese, Elizabeth D; Horn, Marci M; Sizemore, April N; Unni, Asha K; Meerbrey, Michael E; Kalich, Allan G; Rodrigue, Karen M

2015-07-01

The BDNF val66met polymorphism (rs6265) influences activity-dependent secretion of brain-derived neurotrophic factor in the synapse, which is crucial for learning and memory. Individuals homozygous or heterozygous for the met allele have lower BDNF secretion than val homozygotes and may be at risk for reduced declarative memory performance, but it remains unclear which types of declarative memory may be affected and how aging of memory across the lifespan is impacted by the BDNF val66met polymorphism. This cross-sectional study investigated the effects of BDNF polymorphism on multiple indices of memory (item, associative, prospective, subjective complaints) in a lifespan sample of 116 healthy adults aged 20-93 years. Advancing age showed a negative effect on item, associative and prospective memory, but not on subjective memory complaints. For item and prospective memory, there were significant age×BDNF group interactions, indicating the adverse effect of age on memory performance across the lifespan was much stronger in the BDNF met carriers than for the val homozygotes. BDNF met carriers also endorsed significantly greater subjective memory complaints, regardless of age, and showed a trend (p<.07) toward poorer associative memory performance compared to val homozygotes. These results suggest that genetic predisposition to the availability of brain-derived neurotrophic factor, by way of the BDNF val66met polymorphism, exerts an influence on multiple indices of episodic memory - in some cases in all individuals regardless of age (subjective memory and perhaps associative memory), in others as an exacerbation of age-related differences in memory across the lifespan (item and prospective memory). This article is part of a Special Issue entitled Memory & Aging. Copyright © 2014 Elsevier B.V. All rights reserved.

Specificity and overlap of attention and memory biases in depression.

PubMed

Marchetti, Igor; Everaert, Jonas; Dainer-Best, Justin; Loeys, Tom; Beevers, Christopher G; Koster, Ernst H W

2018-01-01

Attentional and memory biases are viewed as crucial cognitive processes underlying symptoms of depression. However, it is still unclear whether these two biases are uniquely related to depression or whether they show substantial overlap. We investigated the degree of specificity and overlap of attentional and memory biases for depressotypic stimuli in relation to depression and anxiety by means of meta-analytic commonality analysis. By including four published studies, we considered a pool of 463 healthy and subclinically depressed individuals, different experimental paradigms, and different psychological measures. Memory bias is reliably and strongly related to depression and, specifically, to symptoms of negative mood, worthlessness, feelings of failure, and pessimism. Memory bias for negative information was minimally related to anxiety. Moreover, neither attentional bias nor the overlap between attentional and memory biases were significantly related to depression. Limitations include cross-sectional nature of the study. Our study showed that, across different paradigms and psychological measures, memory bias (and not attentional bias) represents a primary mechanism in depression. Copyright © 2017 Elsevier B.V. All rights reserved.

Working Memory, Motivation, and Teacher-Initiated Learning

NASA Astrophysics Data System (ADS)

Brooks, David W.; Shell, Duane F.

2006-03-01

Working memory is where we "think" as we learn. A notion that emerges as a synthesis from several threads in the research literatures of cognition, motivation, and connectionism is that motivation in learning is the process whereby working memory resource allocation is instigated and sustained. This paper reviews much literature on motivation and working memory, and concludes that the apparent novelty of the proposal offered to describe motivation in terms of working memory results from the apparent lack of cross-channel exchange among these research traditions. The relation between working memory and motivation is explored in the context of the interactive compensatory model of learning (ICML) in which learning is considered to result from the interaction of ability, motivation, and prior learning. The ICML is recast in light of the revised definition of motivation offered here. This paper goes on to suggest ways in which a range of teaching and learning issues and activities may be reconceptualized in the context of a model emphasizing a learner's working memory that makes use of chunks of previously acquired knowledge.

The Development of Memory Efficiency and Value-Directed Remembering Across the Lifespan: A Cross-Sectional Study of Memory and Selectivity

PubMed Central

Castel, Alan D.; Humphreys, Kathryn L.; Lee, Steve S.; Galván, Adriana; Balota, David A.; McCabe, David P.

2012-01-01

Although attentional control and memory change considerably across the lifespan, no research has examined how the ability to strategically remember important information (i.e., value-directed remembering) changes from childhood to old age. The present study examined this in different age groups across the lifespan (N=320, 5 to 96 years old). We employed a selectivity task where participants were asked to study and recall items worth different point values in order to maximize their point score. This procedure allowed for measures of memory quantity/capacity (number of words recalled) and memory efficiency/selectivity (the recall of high-value items relative to low-value items). Age-related differences were found for memory capacity, as young adults recalled more words than the other groups. However, in terms of selectivity, younger and older adults were more selective than adolescents and children. The dissociation between these measures across the lifespan illustrates important age-related differences in terms of memory capacity and the ability to selectively remember high-value information. PMID:21942664

The development of memory efficiency and value-directed remembering across the life span: a cross-sectional study of memory and selectivity.

PubMed

Castel, Alan D; Humphreys, Kathryn L; Lee, Steve S; Galván, Adriana; Balota, David A; McCabe, David P

2011-11-01

Although attentional control and memory change considerably across the life span, no research has examined how the ability to strategically remember important information (i.e., value-directed remembering) changes from childhood to old age. The present study examined this in different age groups across the life span (N = 320, 5-96 years old). A selectivity task was used in which participants were asked to study and recall items worth different point values in order to maximize their point score. This procedure allowed for measures of memory quantity/capacity (number of words recalled) and memory efficiency/selectivity (the recall of high-value items relative to low-value items). Age-related differences were found for memory capacity, as young adults recalled more words than the other groups. However, in terms of selectivity, younger and older adults were more selective than adolescents and children. The dissociation between these measures across the life span illustrates important age-related differences in terms of memory capacity and the ability to selectively remember high-value information.

Experimental characterization and computational modeling of unimorph shape memory polymer actuators incorporating transverse curvature in the substrate

NASA Astrophysics Data System (ADS)

Cantrell, Jason T.

This document outlines in detail the research performed by applying shape memory polymers in a generic unimorph actuator configuration. A set of experiments designed to investigate the influence of transverse curvature, the relative widths of shape memory polymer and composite substrates, and shape memory polymer thickness on actuator recoverability after multiple thermo-mechanical cycles is presented in detail. A theoretical model of the moment required to maintain shape fixity with minimal shape retention loss was developed and experimentally validated for unimorph composite actuators of varying cross-sectional areas. Theoretical models were also developed and evaluated to determine the relationship between the materials neutral axes and thermal stability during a thermo-mechanical cycle. Research was conducted on the incorporation of shape memory polymers on micro air vehicle wings to maximize shape fixity and shape recoverability while minimizing the volume of shape memory polymer on the wing surface. Applications based research also included experimentally evaluating the feasibility of shape memory polymers on deployable satellite antenna ribs both with and without resistance heaters which could be utilized to assist in antenna deployment.

Whorfian effects on colour memory are not reliable.

PubMed

Wright, Oliver; Davies, Ian R L; Franklin, Anna

2015-01-01

The Whorfian hypothesis suggests that differences between languages cause differences in cognitive processes. Support for this idea comes from studies that find that patterns of colour memory errors made by speakers of different languages align with differences in colour lexicons. The current study provides a large-scale investigation of the relationship between colour language and colour memory, adopting a cross-linguistic and developmental approach. Colour memory on a delayed matching-to-sample (XAB) task was investigated in 2 language groups with differing colour lexicons, for 3 developmental stages and 2 regions of colour space. Analyses used a Bayesian technique to provide simultaneous assessment of two competing hypotheses (H1-Whorfian effect present, H0-Whorfian effect absent). Results of the analyses consistently favoured H0. The findings suggest that Whorfian effects on colour memory are not reliable and that the importance of such effects should not be overestimated.

Workplace Exposures and Cognitive Function During Adulthood: Evidence From National Survey of Midlife Development and the O*NET.

PubMed

Grzywacz, Joseph G; Segel-Karpas, Dikla; Lachman, Margie E

2016-06-01

Expand understanding of the role of selected workplace exposures (ie, occupational complexity, conflict in the workplace, pace of work, and physical hazards) in adults' cognitive function. Cross-sectional data (n = 1991) from the second wave of the Midlife in the United States (MIDUS) study; restricted to participants who completed telephone-based cognitive assessments of episodic memory, executive functioning, and self-perceived memory. Occupational exposure data were harvested from the ONET Release 6.0. Greater complexity was associated with better self-perceived memory among women and men, and better episodic memory and executive functioning among women. Greater physical hazards were independently associated with poorer episodic memory and executive functioning. Objective assessments of physical and psychosocial exposures in the workplace are independently associated with cognitive outcomes in adulthood, with psychosocial exposures being particularly pronounced among women.

Cannabis use and memory brain function in adolescent boys: a cross-sectional multicenter functional magnetic resonance imaging study.

PubMed

Jager, Gerry; Block, Robert I; Luijten, Maartje; Ramsey, Nick F

2010-06-01

Early-onset cannabis use has been associated with later use/abuse, mental health problems (psychosis, depression), and abnormal development of cognition and brain function. During adolescence, ongoing neurodevelopmental maturation and experience shape the neural circuitry underlying complex cognitive functions such as memory and executive control. Prefrontal and temporal regions are critically involved in these functions. Maturational processes leave these brain areas prone to the potentially harmful effects of cannabis use. We performed a two-site (United States and The Netherlands; pooled data) functional magnetic resonance imaging (MRI) study with a cross-sectional design, investigating the effects of adolescent cannabis use on working memory (WM) and associative memory (AM) brain function in 21 abstinent but frequent cannabis-using boys (13-19) years of age and compared them with 24 nonusing peers. Brain activity during WM was assessed before and after rule-based learning (automatization). AM was assessed using a pictorial hippocampal-dependent memory task. Cannabis users performed normally on both memory tasks. During WM assessment, cannabis users showed excessive activity in prefrontal regions when a task was novel, whereas automatization of the task reduced activity to the same level in users and controls. No effect of cannabis use on AM-related brain function was found. In adolescent cannabis users, the WM system was overactive during a novel task, suggesting functional compensation. Inefficient WM recruitment was not related to a failure in automatization but became evident when processing continuously changing information. The results seem to confirm the vulnerability of still developing frontal lobe functioning for early-onset cannabis use. 2010 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.

Do older t'ai chi practitioners have better attention and memory function?

PubMed

Man, David W K; Tsang, William W N; Hui-Chan, Christina W Y

2010-12-01

Cognitive declines are common in older people and can be a major health issue in an aging world. One type of body-mind exercises, t'ai chi, can be a possible means to help maintaining older adults' cognitive abilities, in addition to beneficial effects of physical exercises. The purpose of this study was to investigate whether t'ai chi practitioners had better attention and memory functions than older people with or without regular exercises. A cross-sectional study examining the relationship between t'ai chi practice and age-, gender- and education-similar older peoples' attention and memory functions. Forty-two (42) community-dwelling elderly subjects, aged 60 or older, recruited from t'ai chi clubs in Hong Kong formed the t'ai chi group. Another 49 elderly having regular exercise habits were recruited from community centers for inclusion in the exercise group. A nonexercise group (normal healthy control) consisting of 44 subjects were also recruited by random selection and through contacting local elderly centers. They were also screened by the Modified Barthel Index, Chinese Mini-mental Status Examination, Geriatric Depression Scale, and evaluated by attention tests (Color Trail Form A-1 and 2) and memory tests (including Rivermead Behavioral Memory Test and The Hong Kong List Learning Test). The main finding was that the three groups differed in attention and memory functions, and the t'ai chi group had demonstrated better performance than the other two groups in most subtests. As a causal relationship cannot be assumed in the present cross-sectional study, future research is required to examine how t'ai chi can improve cognitive function using a randomized control trial as well as determining whether t'ai chi practice can lead to better health status among elderly people.

People Around Us. Language Arts Theme Units, Volume V. Cross Curricular Activities for Primary Grades.

ERIC Educational Resources Information Center

McAllister, Elizabeth A.; Hildebrand, Joan M.; Ericson, Joann H.

Suggesting that students in the primary grades can explore the world around them and practice valuable skills in spelling, reading, writing, communication, and language, this book presents cross-curricular units on "people around us" that reach diverse needs by working through emotional memory, deductive reasoning, and multiple intelligences.…

Suppression and Working Memory in Auditory Comprehension of L2 Narratives: Evidence from Cross-Modal Priming

ERIC Educational Resources Information Center

Wu, Shiyu; Ma, Zheng

2016-01-01

Using a cross-modal priming task, the present study explores whether Chinese-English bilinguals process goal related information during auditory comprehension of English narratives like native speakers. Results indicate that English native speakers adopted both mechanisms of suppression and enhancement to modulate the activation of goals and keep…

Rugby versus Soccer in South Africa: Content Familiarity Contributes to Cross-Cultural Differences in Cognitive Test Scores

ERIC Educational Resources Information Center

Malda, Maike; van de Vijver, Fons J. R.; Temane, Q. Michael

2010-01-01

In this study, cross-cultural differences in cognitive test scores are hypothesized to depend on a test's cultural complexity (Cultural Complexity Hypothesis: CCH), here conceptualized as its content familiarity, rather than on its cognitive complexity (Spearman's Hypothesis: SH). The content familiarity of tests assessing short-term memory,…

The effects of increasing semantic-associate list length on the Deese-Roediger-McDermott false recognition memory: Dual false-memory process in retrieval from sub- and supraspan lists.

PubMed

Jou, Jerwen; Arredondo, Mario L; Li, Cheng; Escamilla, Eric E; Zuniga, Richard

2017-10-01

In this study, the number of semantic associates in Deese-Roediger-McDermott (DRM) lists was varied from 4 to 14 in a modified Sternberg paradigm. The false alarm (FA) and correct rejection (CR) reaction time (RT)/memory-set size (MSS) functions of critical lures showed a cross-over interaction at approximately MSS 7, suggesting a reversal of the relative dominance between these two responses to the critical lure at this point and also indicating the location of the boundary between the sub- and supraspan MSS. For the subspan lists, FA to critical lures was slower than CR, suggesting a slow, strategic mechanism driving the false memory. Conversely, for the supraspan lists, critical lure FA was faster than its CR, suggesting a spontaneous mechanism driving the false memory. Results of two experiments showed that an automatic, fast, and a slow, controlled process could be error-prone or error-corrective, depending on the length of the DRM memory list. Thus there is a dual retrieval process in false memory as in true memory. The findings can be explained by both the activation/monitoring and the fuzzy-trace theories.

Translational Approaches Targeting Reconsolidation

PubMed Central

Kroes, Marijn C.W.; LeDoux, Joseph E.; Phelps, Elizabeth A.

2017-01-01

Maladaptive learned responses and memories contribute to psychiatric disorders that constitute a significant socio-economic burden. Primary treatment methods teach patients to inhibit maladaptive responses, but do not get rid of the memory itself, which explains why many patients experience a return of symptoms even after initially successful treatment. This highlights the need to discover more persistent and robust techniques to diminish maladaptive learned behaviours. One potentially promising approach is to alter the original memory, as opposed to inhibiting it, by targeting memory reconsolidation. Recent research shows that reactivating an old memory results in a period of memory flexibility and requires restorage, or reconsolidation, for the memory to persist. This reconsolidation period allows a window for modification of a specific old memory. Renewal of memory flexibility following reactivation holds great clinical potential as it enables targeting reconsolidation and changing of specific learned responses and memories that contribute to maladaptive mental states and behaviours. Here, we will review translational research on non-human animals, healthy human subjects, and clinical populations aimed at altering memories by targeting reconsolidation using biological treatments (electrical stimulation, noradrenergic antagonists) or behavioural interference (reactivation–extinction paradigm). Both approaches have been used successfully to modify aversive and appetitive memories, yet effectiveness in treating clinical populations has been limited. We will discuss that memory flexibility depends on the type of memory tested and the brain regions that underlie specific types of memory. Further, when and how we can most effectively reactivate a memory and induce flexibility is largely unclear. Finally, the development of drugs that can target reconsolidation and are safe for use in humans would optimize cross-species translations. Increasing the understanding of the mechanism and limitations of memory flexibility upon reactivation should help optimize efficacy of treatments for psychiatric patients. PMID:27240676

Nanoscale cross-point diode array accessing embedded high density PCM

NASA Astrophysics Data System (ADS)

Wang, Heng; Liu, Yan; Liu, Bo; Gao, Dan; Xu, Zhen; Zhan, Yipeng; Song, Zhitang; Feng, Songlin

2017-08-01

The main bottlenecks in the development of current embedded phase change memory (PCM) technology are the current density and data storage density. In this paper, we present a PCM with 4F2 cross-point diode selector and blade-type bottom electrode contact (BEC). A blade TiN BEC with a cross-sectional area of 630 nm2 (10 nm × 63 nm) reduces the reset current down to about 750 μA. The optimized diode array could supply this 750 μA reset current at about 1.7 V and low off-current 1 × 10-4 μA at about -5.05 V. The on-off ratio of this device is 7.5 × 106. The proposed nanoscale PCM device simultaneously exhibits an operation voltage as low as 3 V and a high density drive current with an ultra small cell size of 4F2 (108 nm × 108 nm). Over 106 cycling endurance properties guarantee that it can work effectively on the embedded memory.

The θ-γ neural code.

PubMed

Lisman, John E; Jensen, Ole

2013-03-20

Theta and gamma frequency oscillations occur in the same brain regions and interact with each other, a process called cross-frequency coupling. Here, we review evidence for the following hypothesis: that the dual oscillations form a code for representing multiple items in an ordered way. This form of coding has been most clearly demonstrated in the hippocampus, where different spatial information is represented in different gamma subcycles of a theta cycle. Other experiments have tested the functional importance of oscillations and their coupling. These involve correlation of oscillatory properties with memory states, correlation with memory performance, and effects of disrupting oscillations on memory. Recent work suggests that this coding scheme coordinates communication between brain regions and is involved in sensory as well as memory processes. Copyright © 2013 Elsevier Inc. All rights reserved.

Toxic effect of khat (Catha edulis) on memory: Systematic review and meta-analysis

PubMed Central

Berihu, Birhane Alem; Asfeha, Gebrekidan Gebregzabher; Welderufael, Abadi Leul; Debeb, Yared Godefa; Zelelow, Yibrah Berhe; Beyene, Hafte Assefa

2017-01-01

Background: People use khat (Catha edulis) for its pleasant stimulant effect of physical activity, consciousness, motor, and mental functions. Although there are reports assessing the effect of khat on memory, there was no study based on formal systematic review and meta-analysis. Objective: We have therefore conducted this meta-analysis to determine the level of evidence for the effect of khat (C. edulis Forsk) on memory discrepancy. Methods: MEDLINE, Cochrane Library, PubMed, Academic Search Complete, SPORTDiscus, ScienceDirect, Scopus, Web of Science, and Google Scholar were searched to retrieve the papers for this review. Keywords utilized across database search were khat, cat, chat, long-term memory, short-term memory, memory deficit, randomized control trial, and cross-sectional survey. The search was limited to studies in humans and rodents; published in English language. Result: Finding of various studies included in our meta-analysis showed that the effect of acute, and subchronic exposure to khat showed that short-term memory appears to be affected depending on the duration of exposure. However, does not have any effect on long-term memory. Conclusion: Although a number of studies regarding the current topic are limited, the evidenced showed that khat (C. edulis) induced memory discrepancy. PMID:28149078

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.

A novel vaccination strategy mediating the induction of lung-resident memory CD8 T cells confers heterosubtypic immunity against future pandemic influenza virus

PubMed Central

Lee, Yu-Na; Lee, Young-Tae; Kim, Min-Chul; Gewirtz, Andrew T.; Kang, Sang-Moo

2016-01-01

The currently used vaccine strategy to combat influenza A virus (IAV) aims to provide highly specific immunity to circulating seasonal IAV strains. However, the outbreak of 2009 influenza pandemic highlights the danger in this strategy. Here, we tested the hypothesis that universal vaccination that offers broader but weaker protection would result in cross protective T-cell responses after primary IAV infection, which would subsequently provide protective immunity against future pandemic strains. Specifically, we used tandem repeat M2e epitopes on virus-like particles (M2e5x VLP) that induced heterosubtypic immunity by eliciting antibodies to a conserved M2e epitope. M2e5x VLP was found to be superior to strain-specific current split vaccine in conferring heterosubtypic cross protection and in equipping the host with cross-protective lung-resident nucleoprotein-specific memory CD8+ T cell responses to a subsequent secondary infection with a new pandemic potential strain. Immune correlates for subsequent heterosubtypic immunity by M2e5x VLP vaccination were found to be virus-specific CD8+ T cells secreting IFN-γ and expressing lung-resident memory phenotypic markers CD69+ and CD103+ as well as M2e antibodies. Hence, vaccination with M2e5x VLP may be developable as a new strategy to combat future pandemic outbreaks. PMID:26864033

Memory and linguistic/executive functions of children with borderline intellectual functioning.

PubMed

Água Dias, Andrea B; Albuquerque, Cristina P; Simões, Mário R

2017-11-08

Children with Borderline Intellectual Functioning (BIF) have received a minimal amount of research attention and have been studied in conjunction with Intellectual and Developmental Disabilities. The present study intends to broaden the knowledge of BIF, by analyzing domains such as verbal memory and visual memory, as well as tasks that rely simultaneously on memory, executive functions, and language. A cross-sectional, comparison study was carried out between a group of 40 children with BIF (mean age = 10.03; 24 male and 16 female), and a control group of 40 normal children of the same age, gender, and socioeconomic level as the BIF group. The WISC-III Full Scale IQs of the BIF group ranged from 71 to 84. The following instruments were used: Word List, Narrative Memory, Rey Complex Figure, Face Memory, Rapid Naming (both RAN and RAS tests), and Verbal Fluency. The results showed deficits in children with BIF in verbal short-term memory, rapid naming, phonemic verbal fluency, and visual short-term memory, specifically in a visual recognition task, when compared with the control group. Long-term verbal memory was impaired only in older children with BIF and long-term visual memory showed no deficit. Verbal short-term memory stands out as a limitation and visual long-term memory as a strength. Correlations between the WISC-III and neuropsychological tests scores were predominantly low. The study expands the neuropsychological characterization of children with BIF and the implications of the deficits and strengths are stressed.

Hybrid associative memory using an incoherent correlation system

NASA Astrophysics Data System (ADS)

Taniguchi, Masaki; Ichioka, Yoshiki; Matsuoka, Katsunori

1990-10-01

A hybrid heteroassociative memory is presented that uses an incoherent system in which two correlators and a nonlinear element form a nonlinear feedback system. This system can recall any pattern from an input pattern without cross-talk or ghosts by properly designing a pair of filters installed in the correlators. Experiments on a simple hybrid system were performed to ensure the operation of the system and to demonstrate the usefulness of this proposed system.

High Band Technology Program (HiTeP)

DTIC Science & Technology

2005-03-01

clock distribution circuit. One Receiver Memory module receives 60MHz reference sine wave and distributes 60MHz clock signals to all Receiver Memory...Diagram UNCLASSIFIED 23 in N00014-99-C-0314 Integrated Defense Systems Final Report 1 March 2005 .. 4.ran FibreXpress Fibre-Channel PMC "Motrl Medea FCR...the Electrically Short Crossed-Notch (ESCN). It is shorter than traditional traveling wave notch antennas. The 2X ECSN fin length is approximately 1.2

Peripheral Ferroelectric Domain Switching and Polarization Fatigue in Nonvolatile Memory Elements of Continuous Pt/SrBi2Ta2O9/Pt Thin-Film Capacitors

NASA Astrophysics Data System (ADS)

Chen, Min-Chuan; Jiang, An-Quan

2011-07-01

We verify the domain sideway motion around the peripheral regions of the crossed capacitors of top and bottom electrode bars without electrode coverage. To avoid the crosstalk problem between adjacent memory cells, the safe distance between adjacent elements of Pt/SrBi2Ta2O9/Pt thin-film capacitors is estimated to be 0.156 μm. Moreover, the fatigue of Pt/SrBi2Ta2O9/Pt thin-film capacitors is independent of the individual memory size due to the absence of etching damage.

Thermoreversible Folding as a Route to the Unique Shape-Memory Character in Ductile Polymer Networks.

PubMed

McBride, Matthew K; Podgorski, Maciej; Chatani, Shunsuke; Worrell, Brady T; Bowman, Christopher N

2018-06-21

Ductile, cross-linked films were folded as a means to program temporary shapes without the need for complex heating cycles or specialized equipment. Certain cross-linked polymer networks, formed here with the thiol-isocyanate reaction, possessed the ability to be pseudoplastically deformed below the glass transition, and the original shape was recovered during heating through the glass transition. To circumvent the large forces required to plastically deform a glassy polymer network, we have utilized folding, which localizes the deformation in small creases, and achieved large dimensional changes with simple programming procedures. In addition to dimension changes, three-dimensional objects such as swans and airplanes were developed to demonstrate applying origami principles to shape memory. We explored the fundamental mechanical properties that are required to fold polymer sheets and observed that a yield point that does not correspond to catastrophic failure is required. Unfolding occurred during heating through the glass transition, indicating the vitrification of the network that maintained the temporary, folded shape. Folding was demonstrated as a powerful tool to simply and effectively program ductile shape-memory polymers without the need for thermal cycling.

Dually actuated triple shape memory polymers of cross-linked polycyclooctene-carbon nanotube/polyethylene nanocomposites.

PubMed

Wang, Zhenwen; Zhao, Jun; Chen, Min; Yang, Minhao; Tang, Luyang; Dang, Zhi-Min; Chen, Fenghua; Huang, Miaoming; Dong, Xia

2014-11-26

In this work, electrically and thermally actuated triple shape memory polymers (SMPs) of chemically cross-linked polycyclooctene (PCO)-multiwalled carbon nanotube (MWCNT)/polyethylene (PE) nanocomposites with co-continuous structure and selective distribution of fillers in PCO phase are prepared. We systematically studied not only the microstructure including morphology and fillers' selective distribution in one phase of the PCO/PE blends, but also the macroscopic properties including thermal, mechanical, and electrical properties. The co-continuous window of the immiscible PCO/PE blends is found to be the volume fraction of PCO (vPCO) of ca. 40-70 vol %. The selective distribution of fillers in one phase of co-continuous blends is obtained by a masterbatch technique. The prepared triple SMP materials show pronounced triple shape memory effects (SMEs) on the dynamic mechanical thermal analysis (DMTA) and the visual observation by both thermal and electric actuations. Such polyolefin samples with well-defined microstructure, electrical actuation, and triple SMEs might have potential applications as, for example, multiple autochoke elements for engines, self-adjusting orthodontic wires, and ophthalmic devices.

Estrogen and cognitive functioning in men with mild cognitive impairment.

PubMed

Sherwin, Barbara B

2002-01-01

Although men do not experience an abrupt cessation of gonadal hormone production at midlife as do women, levels of testosterone (T) decrease gradually with aging. Because estradiol (E2) arises mainly from the conversion of T in men, the availability of E2 also decreases with increasing age. In randomized clinical trials, E2 replacement therapy has been shown to maintain aspects of cognition in postmenopausal women, specifically with regard to verbal memory. The present prospective, randomized, cross-over trial is being undertaken in order to determine whether E2 will enhance verbal memory in men with Mild Cognitive Impairment (MCI). Men with MCI will randomly receive E2 or placebo for the first 3 mo of treatment and will then be crossed-over to the other treatment for an additional 3 mo. A battery of neuropsychological tests will be administered at pretreatment and, again, following each 3-mo treatment phase. It is hypothesized that elderly men with MCI will perform better on tests of explicit memory when they are being treated with E2 compared to their performance under placebo conditions.

Electrophysiological Repetition Effects in Persons with Mild Cognitive Impairment depend upon Working Memory Demand.

PubMed

Broster, Lucas S; Jenkins, Shonna L; Holmes, Sarah D; Edwards, Matthew G; Jicha, Gregory A; Jiang, Yang

2018-05-07

Forms of implicit memory, including repetition effects, are preserved relative to explicit memory in clinical Alzheimer's disease. Consequently, cognitive interventions for persons with Alzheimer's disease have been developed that leverage this fact. However, despite the clinical robustness of behavioral repetition effects, altered neural mechanisms of repetition effects are studied as biomarkers of both clinical Alzheimer's disease and pre-morbid Alzheimer's changes in the brain. We hypothesized that the clinical preservation of behavioral repetition effects results in part from concurrent operation of discrete memory systems. We developed two experiments that included probes of emotional repetition effects differing in that one included an embedded working memory task. We found that neural repetition effects manifested in patients with amnestic mild cognitive impairment, the earliest form of clinical Alzheimer's disease, during emotional working memory tasks, but they did not manifest during the task that lacked the embedded working memory manipulation. Specifically, the working memory task evoked neural repetition effects in the P600 time-window, but the same neural mechanism was only minimally implicated in the task without a working memory component. We also found that group differences in behavioral repetition effects were smaller in the experiment with a working memory task. We suggest that cross-domain cognitive challenge can expose "defunct" neural capabilities of individuals with amnestic mild cognitive impairment. Copyright © 2018. Published by Elsevier Ltd.

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

PubMed

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

2018-04-20

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

Severity of Acute Infectious Mononucleosis Correlates with Cross-Reactive Influenza CD8 T-Cell Receptor Repertoires.

PubMed

Aslan, Nuray; Watkin, Levi B; Gil, Anna; Mishra, Rabinarayan; Clark, Fransenio G; Welsh, Raymond M; Ghersi, Dario; Luzuriaga, Katherine; Selin, Liisa K

2017-12-05

Fifty years after the discovery of Epstein-Barr virus (EBV), it remains unclear how primary infection with this virus leads to massive CD8 T-cell expansion and acute infectious mononucleosis (AIM) in young adults. AIM can vary greatly in severity, from a mild transient influenza-like illness to a prolonged severe syndrome. We questioned whether expansion of a unique HLA-A2.01-restricted, cross-reactive CD8 T-cell response between influenza virus A-M1 58 (IAV-M1) and EBV BMLF1 280 (EBV-BM) could modulate the immune response to EBV and play a role in determining the severity of AIM in 32 college students. Only ex vivo total IAV-M1 and IAV-M1+EBV-BM cross-reactive tetramer + frequencies directly correlated with AIM severity and were predictive of severe disease. Expansion of specific cross-reactive memory IAV-M1 T-cell receptor (TCR) Vβ repertoires correlated with levels of disease severity. There were unique profiles of qualitatively different functional responses in the cross-reactive and EBV-specific CD8 T-cell responses in each of the three groups studied, severe-AIM patients, mild-AIM patients, and seropositive persistently EBV-infected healthy donors, that may result from differences in TCR repertoire use. IAV-M1 tetramer + cells were functionally cross-reactive in short-term cultures, were associated with the highest disease severity in AIM, and displayed enhanced production of gamma interferon, a cytokine that greatly amplifies immune responses, thus frequently contributing to induction of immunopathology. Altogether, these data link heterologous immunity via CD8 T-cell cross-reactivity to CD8 T-cell repertoire selection, function, and resultant disease severity in a common and important human infection. In particular, it highlights for the first time a direct link between the TCR repertoire with pathogenesis and the diversity of outcomes upon pathogen encounter. IMPORTANCE The pathogenic impact of immune responses that by chance cross-react to unrelated viruses has not been established in human infections. Here, we demonstrate that the severity of acute infectious mononucleosis (AIM), an Epstein-Barr virus (EBV)-induced disease prevalent in young adults but not children, is associated with increased frequencies of T cells cross-reactive to EBV and the commonly acquired influenza A virus (IAV). The T-cell receptor (TCR) repertoire and functions of these cross-reactive T cells differed between mild- and severe-AIM patients, most likely because these two groups of patients had selected different memory TCR repertoires in response to IAV infections encountered earlier. This heterologous immunity may explain variability in disease outcome and why young adults with more-developed IAV-specific memory T-cell pools have more-severe disease than children, who have less-developed memory pools. This study provides a new framework for understanding the role of heterologous immunity in human health and disease and highlights an important developing field examining the role of T-cell repertoires in the mediation of immunopathology. Copyright © 2017 Aslan et al.

A single dose of cocaine enhances prospective memory performance.

PubMed

Hutten, Nadia Rpw; Kuypers, Kim Pc; van Wel, Janelle Hp; Theunissen, Eef L; Toennes, Stefan W; Verkes, Robbert-Jan; Ramaekers, Johannes G

2018-06-01

Prospective memory is the ability to recall intended actions or events at the right time or in the right context. While cannabis is known to impair prospective memory, the acute effect of cocaine is unknown. In addition, it is not clear whether changes in prospective memory represent specific alterations in memory processing or result from more general effects on cognition that spread across multiple domains such as arousal and attention. The main objective of the study was, therefore, to determine whether drug-induced changes in prospective memory are memory specific or associated with more general drug-induced changes in attention and arousal. A placebo-controlled, three-way, cross-over study including 15 regular poly-drug users was set up to test the influence of oral cocaine (300 mg) and vaporised cannabis (300+150 'booster' µg/kg bodyweight) on an event-based prospective memory task. Attentional performance was assessed using a divided attention task and subjective arousal was assessed with the Profile of Mood States questionnaire. Results showed that cocaine enhanced prospective memory, attention and arousal. Mean performance of prospective memory and attention, as well as levels of arousal were lowest during treatment with cannabis as compared with placebo and cocaine as evinced by a significantly increased trend across treatment conditions. Prospective memory performance was only weakly positively associated to measures of attention and arousal. Together, these results indicate that cocaine enhancement of prospective memory performance cannot be fully explained by parallel changes in arousal and attention levels, and is likely to represent a direct change in the neural network underlying prospective memory.

The attentional boost effect and context memory.

PubMed

Mulligan, Neil W; Smith, S Adam; Spataro, Pietro

2016-04-01

Stimuli co-occurring with targets in a detection task are better remembered than stimuli co-occurring with distractors-the attentional boost effect (ABE). The ABE is of interest because it is an exception to the usual finding that divided attention during encoding impairs memory. The effect has been demonstrated in tests of item memory but it is unclear if context memory is likewise affected. Some accounts suggest enhanced perceptual encoding or associative binding, predicting an ABE on context memory, whereas other evidence suggests a more abstract, amodal basis of the effect. In Experiment 1, context memory was assessed in terms of an intramodal perceptual detail, the font and color of the study word. Experiment 2 examined context memory cross-modally, assessing memory for the modality (visual or auditory) of the study word. Experiments 3 and 4 assessed context memory with list discrimination, in which 2 study lists are presented and participants must later remember which list (if either) a test word came from. In all experiments, item (recognition) memory was also assessed and consistently displayed a robust ABE. In contrast, the attentional-boost manipulation did not enhance context memory, whether defined in terms of visual details, study modality, or list membership. There was some evidence that the mode of responding on the detection task (motoric response as opposed to covert counting of targets) may impact context memory but there was no evidence of an effect of target detection, per se. In sum, the ABE did not occur in context memory with verbal materials. (c) 2016 APA, all rights reserved).

Analysis of solid particles falling down and interacting in a channel with sedimentation using fictitious boundary method

NASA Astrophysics Data System (ADS)

Usman, K.; Walayat, K.; Mahmood, R.; Kousar, N.

2018-06-01

We have examined the behavior of solid particles in particulate flows. The interaction of particles with each other and with the fluid is analyzed. Solid particles can move freely through a fixed computational mesh using an Eulerian approach. Fictitious boundary method (FBM) is used for treating the interaction between particles and the fluid. Hydrodynamic forces acting on the particle's surface are calculated using an explicit volume integral approach. A collision model proposed by Glowinski, Singh, Joseph and coauthors is used to handle particle-wall and particle-particle interactions. The particulate flow is computed using multigrid finite element solver FEATFLOW. Numerical experiments are performed considering two particles falling and colliding and sedimentation of many particles while interacting with each other. Results for these experiments are presented and compared with the reference values. Effects of the particle-particle interaction on the motion of the particles and on the physical behavior of the fluid-particle system has been analyzed.

The suitability of monopolar and bipolar ion exchange membranes as separators for biological fuel cells.

PubMed

Harnisch, Falk; Schröder, Uwe; Scholz, Fritz

2008-03-01

A proton exchange (Nafion-117), a cation exchange (Ultrex CMI7000), an anion exchange (Fumasep FAD), and a bipolar (FumasepFBM) membrane have been studied to evaluate the principle suitability of ion exchange membranes as separators between the anode and the cathode compartment of biological fuel cells. The applicability of these membranes is severely affected by the neutral pH, and the usually low ionic strength of the electrolyte solutions. Thus, the ohmic resistance of the monopolar membranes was found to greatly increase at neutral pH and at decreasing electrolyte concentrations. None of the studied membranes can prevent the acidification of the anode and the alkalization of the cathode compartment, which occurs in the course of the fuel cell operation. Bipolar membranes are shown to be least suitable for biofuel cell application since they show the highest polarization without being able to prevent pH splitting between the anode and cathode compartments.

Update on the mechanism of action of antiepileptic drugs.

PubMed

Meldrum, B S

1996-01-01

Novel antiepileptic drugs (AEDs) are thought to act on voltage-sensitive ion channels, on inhibitory neurotransmission or on excitatory neurotransmission. Two successful examples of rational AED design that potentiate GABA-mediated inhibition are vigabatrin (VGB) by irreversible inhibition of GABA-transaminase, and tiagabine (TGB) by blocking GABA uptake. Lamotrigine (LTG) prolongs inactivation of voltage-dependent sodium channels. The anticonvulsant action of remacemide (RCM) is probably largely due to blockade of NMDA receptors and prolonged inactivation of sodium channels induced by its desglycinated metabolite. Felbamate (FBM) apparently blocks NMDA receptors, potentiates GABA-mediated responses, blocks L-type calcium channels, and possibly also prolongs sodium channel inactivation. Similarly, topiramate (TPM) has multiple probable sites of action, including sodium channels, GABA receptors, and glutamate (AMPA) receptors. Gabapentin (GBP) apparently has a completely novel type of action, probably involving potentiation of GABA-mediated inhibition and possibly also inactivation of sodium channels. The therapeutic advantages of the novel AEDs are as yet only partially explained by our present understanding of their mechanisms of action.

Left-frontal brain potentials index conceptual implicit memory for words initially viewed subliminally.

PubMed

Chen, Jason C W; Li, Wen; Lui, Ming; Paller, Ken A

2009-08-18

Neural correlates of explicit and implicit memory tend to co-occur and are therefore difficult to measure independently, posing problems for understanding the unique nature of different types of memory processing. To circumvent this problem, we developed an experimental design wherein subjects acquired information from words presented in a subliminal manner, such that conscious remembering was minimized. Cross-modal word repetition was used so that perceptual implicit memory would also be limited. Healthy human subjects viewed subliminal words six times each and about 2 min later heard the same words interspersed with new words in a category-verification test. Electrophysiological correlates of word repetition included negative brain potentials over left-frontal locations beginning approximately 500 ms after word onset. Behavioral responses were slower for repeated words than for new words. Differential processing of word meaning in the absence of explicit memory was most likely responsible for differential electrical and behavioral responses to old versus new words. Moreover, these effects were distinct from neural correlates of explicit memory observed in prior experiments, and were observed here in two separate experiments, thus providing a foundation for further investigations of relationships and interactions between different types of memory engaged when words repeat.

[Subjective memory loss--a sign of cognitive impairment in the elderly? An overview of the status of research].

PubMed

Riedel-Heller, S G; Schork, A; Matschinger, H; Angermeyer, M C

2000-02-01

According to the growing clinical interest in early indicators of dementia, numerous studies have examined the association between subjective memory complaints and cognitive performance in old age. Their results are contradictory. In this paper, studies carried out over the last 10 years are compared with regard to the study design and the assessment instruments used. The results are discussed with particular reference to the diagnostic validity of subjective memory complaints. The majority of case-control studies and cross-sectional studies of non-representative samples could not demonstrate an association between subjective memory complaints and cognitive performance. Most field studies of larger representative population samples, however, have come to the opposite conclusion. A consistent assessment of these statistically significant associations against the background of diagnostic validity showed that memory complaints cannot be taken as a clear clinical indicator for cognitive impairment. Subjective memory complaints may reflect depressive disorders and a multitude of other processes, of which an objective impairment of cognitive performance is just one aspect. As a consequence, an inclusion of subjective memory complaints as a diagnostic criterion for the diagnosis of "mild cognitive disorder" according to ICD-10 is not justified.

Modality-specific alpha modulations facilitate long-term memory encoding in the presence of distracters.

PubMed

Jiang, Haiteng; van Gerven, Marcel A J; Jensen, Ole

2015-03-01

It has been proposed that long-term memory encoding is not only dependent on engaging task-relevant regions but also on disengaging task-irrelevant regions. In particular, oscillatory alpha activity has been shown to be involved in shaping the functional architecture of the working brain because it reflects the functional disengagement of specific regions in attention and memory tasks. We here ask if such allocation of resources by alpha oscillations generalizes to long-term memory encoding in a cross-modal setting in which we acquired the ongoing brain activity using magnetoencephalography. Participants were asked to encode pictures while ignoring simultaneously presented words and vice versa. We quantified the brain activity during rehearsal reflecting subsequent memory in the different attention conditions. The key finding was that successful long-term memory encoding is reflected by alpha power decreases in the sensory region of the to-be-attended modality and increases in the sensory region of the to-be-ignored modality to suppress distraction during rehearsal period. Our results corroborate related findings from attention studies by demonstrating that alpha activity is also important for the allocation of resources during long-term memory encoding in the presence of distracters.

Encoding mechano-memories in filamentous-actin networks

NASA Astrophysics Data System (ADS)

Majumdar, Sayantan; Foucard, Louis; Levine, Alex; Gardel, Margaret L.

History-dependent adaptation is a central feature of learning and memory. Incorporating such features into `adaptable materials' that can modify their mechanical properties in response to external cues, remains an outstanding challenge in materials science. Here, we study a novel mechanism of mechano-memory in cross-linked F-actin networks, the essential determinants of the mechanical behavior of eukaryotic cells. We find that the non-linear mechanical response of such networks can be reversibly programmed through induction of mechano-memories. In particular, the direction, magnitude, and duration of previously applied shear stresses can be encoded into the network architecture. The `memory' of the forcing history is long-lived, but it can be erased by force applied in the opposite direction. These results demonstrate that F-actin networks can encode analog read-write mechano-memories which can be used for adaptation to mechanical stimuli. We further show that the mechano-memory arises from changes in the nematic order of the constituent filaments. Our results suggest a new mechanism of mechanical sensing in eukaryotic cells and provide a strategy for designing a novel class of materials. S.M. acknowledges U. Chicago MRSEC for support through a Kadanoff-Rice fellowship.

Autobiographical memory functions in young Japanese men and women.

PubMed

Maki, Yoichi; Kawasaki, Yayoi; Demiray, Burcu; Janssen, Steve M J

2015-01-01

The present study examined whether the three major functions of autobiographical memory observed in Western societies (i.e., directing-behaviour, social-bonding and self-continuity) also exist in an East Asian society. Two self-report measures were used to assess the autobiographical memory functions of Japanese men and women. Japanese young adults (N = 451, ages 17-28 years) first completed the original Thinking About Life Experiences (TALE) Questionnaire. They subsequently received three TALE items that represented memory functions and attempted to recall a specific instance of memory recall for each item. Confirmatory factor analyses on the TALE showed that the three functions were replicated in the current sample. However, Japanese participants reported lower levels of all three functions than American participants in a previous study. We also explored whether there was an effect of gender in this Japanese sample. Women reported higher levels of the self-continuity and social-bonding functions than men. Finally, participants recalled more specific instances of memory recall for the TALE items that had received higher ratings on the TALE, suggesting that the findings on the first measure were supported by the second measure. Results are discussed in relation to the functional approach to autobiographical memory in a cross-cultural context.

Cross-Modal Correspondences Enhance Performance on a Colour-to-Sound Sensory Substitution Device.

PubMed

Hamilton-Fletcher, Giles; Wright, Thomas D; Ward, Jamie

Visual sensory substitution devices (SSDs) can represent visual characteristics through distinct patterns of sound, allowing a visually impaired user access to visual information. Previous SSDs have avoided colour and when they do encode colour, have assigned sounds to colour in a largely unprincipled way. This study introduces a new tablet-based SSD termed the ‘Creole’ (so called because it combines tactile scanning with image sonification) and a new algorithm for converting colour to sound that is based on established cross-modal correspondences (intuitive mappings between different sensory dimensions). To test the utility of correspondences, we examined the colour–sound associative memory and object recognition abilities of sighted users who had their device either coded in line with or opposite to sound–colour correspondences. Improved colour memory and reduced colour-errors were made by users who had the correspondence-based mappings. Interestingly, the colour–sound mappings that provided the highest improvements during the associative memory task also saw the greatest gains for recognising realistic objects that also featured these colours, indicating a transfer of abilities from memory to recognition. These users were also marginally better at matching sounds to images varying in luminance, even though luminance was coded identically across the different versions of the device. These findings are discussed with relevance for both colour and correspondences for sensory substitution use.

Apolipoprotein E ε4 influences on episodic recall and brain structures in aging pilots

PubMed Central

Adamson, Maheen M.; Landy, Kelly M.; Duong, Susan; Fox-Bosetti, Sabrina; Ashford, J. Wesson; Murphy, Greer M.; Weiner, Michael; Taylor, Joy L.

2008-01-01

The apolipoprotein (APOE) ε4 allele is associated with cognitive deficits and hippocampal atrophy in nondemented middle-aged and older adults. It is not known to what extent this genetic risk factor for Alzheimer's disease (AD) impacts performance in late middle-aged and older workers in cognitively demanding occupations. This cross-sectional analysis examines brain–cognitive–genetic relationships in actively flying general aviation pilots, half of whom are APOE ε4 carriers. Fifty pilots were studied with structural MRI and memory tasks. Average visual paired associate memory recall performance was lower in APOE ε4 carriers than non-carriers. Memory performance correlated positively with hippocampal volume, but no structural differences were found in hippocampal or frontal volumes with respect to APOE ε4 allele. These results were evident in healthy professionals without any presenting memory problems and without selection for a family history of AD. These findings point to basic memory testing as a sensitive tool for detecting APOE ε4 -related influences on memory in aging workers. PMID:18760504

The spectro-contextual encoding and retrieval theory of episodic memory.

PubMed

Watrous, Andrew J; Ekstrom, Arne D

2014-01-01

The spectral fingerprint hypothesis, which posits that different frequencies of oscillations underlie different cognitive operations, provides one account for how interactions between brain regions support perceptual and attentive processes (Siegel etal., 2012). Here, we explore and extend this idea to the domain of human episodic memory encoding and retrieval. Incorporating findings from the synaptic to cognitive levels of organization, we argue that spectrally precise cross-frequency coupling and phase-synchronization promote the formation of hippocampal-neocortical cell assemblies that form the basis for episodic memory. We suggest that both cell assembly firing patterns as well as the global pattern of brain oscillatory activity within hippocampal-neocortical networks represents the contents of a particular memory. Drawing upon the ideas of context reinstatement and multiple trace theory, we argue that memory retrieval is driven by internal and/or external factors which recreate these frequency-specific oscillatory patterns which occur during episodic encoding. These ideas are synthesized into a novel model of episodic memory (the spectro-contextual encoding and retrieval theory, or "SCERT") that provides several testable predictions for future research.

Liver-primed memory T cells generated under noninflammatory conditions provide anti-infectious immunity.

PubMed

Böttcher, Jan P; Schanz, Oliver; Wohlleber, Dirk; Abdullah, Zeinab; Debey-Pascher, Svenja; Staratschek-Jox, Andrea; Höchst, Bastian; Hegenbarth, Silke; Grell, Jessica; Limmer, Andreas; Atreya, Imke; Neurath, Markus F; Busch, Dirk H; Schmitt, Edgar; van Endert, Peter; Kolanus, Waldemar; Kurts, Christian; Schultze, Joachim L; Diehl, Linda; Knolle, Percy A

2013-03-28

Development of CD8(+) T cell (CTL) immunity or tolerance is linked to the conditions during T cell priming. Dendritic cells (DCs) matured during inflammation generate effector/memory T cells, whereas immature DCs cause T cell deletion/anergy. We identify a third outcome of T cell priming in absence of inflammation enabled by cross-presenting liver sinusoidal endothelial cells. Such priming generated memory T cells that were spared from deletion by immature DCs. Similar to central memory T cells, liver-primed T cells differentiated into effector CTLs upon antigen re-encounter on matured DCs even after prolonged absence of antigen. Their reactivation required combinatorial signaling through the TCR, CD28, and IL-12R and controlled bacterial and viral infections. Gene expression profiling identified liver-primed T cells as a distinct Neuropilin-1(+) memory population. Generation of liver-primed memory T cells may prevent pathogens that avoid DC maturation by innate immune escape from also escaping adaptive immunity through attrition of the T cell repertoire. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

The effects of cholesterol on learning and memory.

PubMed

Schreurs, Bernard G

2010-07-01

Cholesterol is vital to normal brain function including learning and memory but that involvement is as complex as the synthesis, metabolism and excretion of cholesterol itself. Dietary cholesterol influences learning tasks from water maze to fear conditioning even though cholesterol does not cross the blood brain barrier. Excess cholesterol has many consequences including peripheral pathology that can signal brain via cholesterol metabolites, pro-inflammatory mediators and antioxidant processes. Manipulations of cholesterol within the central nervous system through genetic, pharmacological, or metabolic means circumvent the blood brain barrier and affect learning and memory but often in animals already otherwise compromised. The human literature is no less complex. Cholesterol reduction using statins improves memory in some cases but not others. There is also controversy over statin use to alleviate memory problems in Alzheimer's disease. Correlations of cholesterol and cognitive function are mixed and association studies find some genetic polymorphisms are related to cognitive function but others are not. In sum, the field is in flux with a number of seemingly contradictory results and many complexities. Nevertheless, understanding cholesterol effects on learning and memory is too important to ignore.

"The people I grew up with": the role of sociodemographic factors in early memories in an Italian sample.

PubMed

Artioli, Federica; Cicogna, Pera Carla; Occhionero, Miranda; Reese, Elaine

2012-01-01

This within-culture study aimed to investigate the age and density of earliest memories in a sample of Italian young adults. The framework of this study is sociocultural, with an emphasis on family reminiscing as contributing to early memories. In this regard Italy is of interest due to the fact that it is a Western but familial oriented culture, where multi-generational family ties are still strong in comparison with other European counterparts, providing for the opportunity to investigate the offset of childhood amnesia as a function of growing up in an extended family structure. Consistent with Mullen (1994), 90 undergraduate students were interviewed about their earliest memory and about sociodemographic factors in their early childhood years: household composition, gender, birth order, presence of family moves, and significant early childhood experiences. Participants who grew up in an extended family situation reported earlier and denser memories in comparison with those from nuclear families. Results are discussed in light of other cross-cultural work on childhood amnesia and with respect to sociocultural theories of the importance of family reminiscing for one's early memories.

Memory and selective attention in multiple sclerosis: cross-sectional computer-based assessment in a large outpatient sample.

PubMed

Adler, Georg; Lembach, Yvonne

2015-08-01

Cognitive impairments may have a severe impact on everyday functioning and quality of life of patients with multiple sclerosis (MS). However, there are some methodological problems in the assessment and only a few studies allow a representative estimate of the prevalence and severity of cognitive impairments in MS patients. We applied a computer-based method, the memory and attention test (MAT), in 531 outpatients with MS, who were assessed at nine neurological practices or specialized outpatient clinics. The findings were compared with those obtained in an age-, sex- and education-matched control group of 84 healthy subjects. Episodic short-term memory was substantially decreased in the MS patients. About 20% of them reached a score of only less than two standard deviations below the mean of the control group. The episodic short-term memory score was negatively correlated with the EDSS score. Minor but also significant impairments in the MS patients were found for verbal short-term memory, episodic working memory and selective attention. The computer-based MAT was found to be useful for a routine assessment of cognition in MS outpatients.

Environmental cue saliency influences the vividness of a remote spatial memory in rats.

PubMed

Lopez, Joëlle; de Vasconcelos, Anne Pereira; Cassel, Jean-Christophe

2008-07-01

The Morris water maze is frequently used to evaluate the acquisition and retrieval of spatial memories. Few experiments, however, have investigated the effects of environmental cue saliency on the strength or persistence of such memories after a short vs. long post-acquisition interval. Using a Morris water maze, we therefore tested in rats the effect of the saliency of distal cues on the vividness of a recent (5 days) vs. remote (25 days) memory. Rats trained in a cue-enriched vs. a cue-impoverished context showed a better overall level of performance during acquisition. Furthermore, the probe trials revealed that the rats trained and tested in the cue-impoverished context (1) spent less time in the target quadrant at the 25-day delay, and (2) swam shorter distances in the target area, with fewer crossings at both 5- and 25-day delays, as compared to their counterparts trained and tested in the cue-enriched context. Thus, the memory trace formed in the cue-enriched context shows better resistance to time, suggesting an implication of cue saliency in the vividness of a spatial memory.

Visuospatial bootstrapping: implicit binding of verbal working memory to visuospatial representations in children and adults.

PubMed

Darling, Stephen; Parker, Mary-Jane; Goodall, Karen E; Havelka, Jelena; Allen, Richard J

2014-03-01

When participants carry out visually presented digit serial recall, their performance is better if they are given the opportunity to encode extra visuospatial information at encoding-a phenomenon that has been termed visuospatial bootstrapping. This bootstrapping is the result of integration of information from different modality-specific short-term memory systems and visuospatial knowledge in long term memory, and it can be understood in the context of recent models of working memory that address multimodal binding (e.g., models incorporating an episodic buffer). Here we report a cross-sectional developmental study that demonstrated visuospatial bootstrapping in adults (n=18) and 9-year-old children (n=15) but not in 6-year-old children (n=18). This is the first developmental study addressing visuospatial bootstrapping, and results demonstrate that the developmental trajectory of bootstrapping is different from that of basic verbal and visuospatial working memory. This pattern suggests that bootstrapping (and hence integrative functions such as those associated with the episodic buffer) emerge independent of the development of basic working memory slave systems during childhood. Copyright © 2013 Elsevier Inc. All rights reserved.

Working memory plasticity and aging.

PubMed

Rhodes, Rebecca E; Katz, Benjamin

2017-02-01

The present research explores how the trajectory of learning on a working memory task changes throughout the life span, and whether gains in working memory performance are exclusively a question of initial working memory capacity (WMC) or whether age exerts an independent effect. In a large, cross-sectional study of younger, middle-aged, and older adults, we examined learning on a widely used working memory task-the dual n-back task-over 20 sessions of practice. We found that, while all age groups improved on the task, older adults demonstrated less improvement on the task, and also reached a lower asymptotic maximum performance than younger adults. After controlling for initial WMC, we found that age exerted independent effects on training gains and asymptotic performance; older adults tended to improve less and reached lower levels of performance than younger adults. The difference between younger and older adults' rates of learning depended in part on initial WMC. These results suggest that age-related effects on working memory include not only effects on capacity, but also plasticity and the ability to improve on a task. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Apolipoprotein E epsilon4 influences on episodic recall and brain structures in aging pilots.

PubMed

Adamson, Maheen M; Landy, Kelly M; Duong, Susan; Fox-Bosetti, Sabrina; Ashford, J Wesson; Murphy, Greer M; Weiner, Michael; Taylor, Joy L

2010-06-01

The apolipoprotein (APOE) epsilon4 allele is associated with cognitive deficits and hippocampal atrophy in nondemented middle-aged and older adults. It is not known to what extent this genetic risk factor for Alzheimer's disease (AD) impacts performance in late middle-aged and older workers in cognitively demanding occupations. This cross-sectional analysis examines brain-cognitive-genetic relationships in actively flying general aviation pilots, half of whom are APOE epsilon4 carriers. Fifty pilots were studied with structural MRI and memory tasks. Average visual paired associate memory recall performance was lower in APOE epsilon4 carriers than non-carriers. Memory performance correlated positively with hippocampal volume, but no structural differences were found in hippocampal or frontal volumes with respect to APOE epsilon4 allele. These results were evident in healthy professionals without any presenting memory problems and without selection for a family history of AD. These findings point to basic memory testing as a sensitive tool for detecting APOE epsilon4-related influences on memory in aging workers. Published by Elsevier Inc.

Physical exercise and cognitive function across the life span: Results of a nationwide population-based study.

PubMed

Gaertner, Beate; Buttery, Amanda K; Finger, Jonas D; Wolfsgruber, Steffen; Wagner, Michael; Busch, Markus A

2018-05-01

To examine cross-sectional and longitudinal associations between physical exercise and cognitive function across different age groups in a nationwide population-based sample of adults aged 18-79 years in Germany. Cross-sectional/prospective. Cognitive function was assessed in the mental health module of the German Health Interview and Examination Survey for Adults (DEGS1-MH, 2009-2012, n=3535), using a comprehensive neuropsychological test battery. Cognitive domain scores for executive function and memory were derived from confirmatory factor analysis. Regular physical exercise in the last three months was assessed by self-report and defined as no exercise, <2 and ≥2h (hours) of exercise per week. A subgroup of DEGS1-MH participants who previously participated in the German National Health Interview and Examination Survey 1998 (GNHIES98, 1997-1999, n=1624) enabled longitudinal analyses with a mean follow-up of 12.4 years. Compared to no exercise, more weekly physical exercise was associated with better executive function in cross-sectional (<2h: β=0.12; ≥2h: β=0.17; all p<0.001) and longitudinal analyses (<2h: β=0.14, p<0.001; ≥2h: β=0.15, p=0.001) using linear regression models adjusted for age, sex, education, smoking, alcohol consumption, fruit and vegetable consumption and obesity. Slightly weaker associations were found for memory in cross-sectional (<2h: β=0.08, p=0.009; ≥2h: β=0.08, p=0.026) and longitudinal analysis (<2h: β=0.09, p=0.036; ≥2h: β=0.08, p=0.114). There was no evidence of interaction between physical exercise and age. Higher levels of physical exercise were associated with better executive function and memory in cross-sectional and longitudinal analyses with no evidence for differential effects by age. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Dopamine D1 signaling organizes network dynamics underlying working memory

PubMed Central

Roffman, Joshua L.; Tanner, Alexandra S.; Eryilmaz, Hamdi; Rodriguez-Thompson, Anais; Silverstein, Noah J.; Ho, New Fei; Nitenson, Adam Z.; Chonde, Daniel B.; Greve, Douglas N.; Abi-Dargham, Anissa; Buckner, Randy L.; Manoach, Dara S.; Rosen, Bruce R.; Hooker, Jacob M.; Catana, Ciprian

2016-01-01

Local prefrontal dopamine signaling supports working memory by tuning pyramidal neurons to task-relevant stimuli. Enabled by simultaneous positron emission tomography–magnetic resonance imaging (PET-MRI), we determined whether neuromodulatory effects of dopamine scale to the level of cortical networks and coordinate their interplay during working memory. Among network territories, mean cortical D1 receptor densities differed substantially but were strongly interrelated, suggesting cross-network regulation. Indeed, mean cortical D1 density predicted working memory–emergent decoupling of the frontoparietal and default networks, which respectively manage task-related and internal stimuli. In contrast, striatal D1 predicted opposing effects within these two networks but no between-network effects. These findings specifically link cortical dopamine signaling to network crosstalk that redirects cognitive resources to working memory, echoing neuromodulatory effects of D1 signaling on the level of cortical microcircuits. PMID:27386561

Memory for environmental sounds in sighted, congenitally blind and late blind adults: evidence for cross-modal compensation.

PubMed

Röder, Brigitte; Rösler, Frank

2003-10-01

Several recent reports suggest compensatory performance changes in blind individuals. It has, however, been argued that the lack of visual input leads to impoverished semantic networks resulting in the use of data-driven rather than conceptual encoding strategies on memory tasks. To test this hypothesis, congenitally blind and sighted participants encoded environmental sounds either physically or semantically. In the recognition phase, both conceptually as well as physically distinct and physically distinct but conceptually highly related lures were intermixed with the environmental sounds encountered during study. Participants indicated whether or not they had heard a sound in the study phase. Congenitally blind adults showed elevated memory both after physical and semantic encoding. After physical encoding blind participants had lower false memory rates than sighted participants, whereas the false memory rates of sighted and blind participants did not differ after semantic encoding. In order to address the question if compensatory changes in memory skills are restricted to critical periods during early childhood, late blind adults were tested with the same paradigm. When matched for age, they showed similarly high memory scores as the congenitally blind. These results demonstrate compensatory performance changes in long-term memory functions due to the loss of a sensory system and provide evidence for high adaptive capabilities of the human cognitive system.

A Strategy to Design High-Density Nanoscale Devices utilizing Vapor Deposition of Metal Halide Perovskite Materials.

PubMed

Hwang, Bohee; Lee, Jang-Sik

2017-08-01

The demand for high memory density has increased due to increasing needs of information storage, such as big data processing and the Internet of Things. Organic-inorganic perovskite materials that show nonvolatile resistive switching memory properties have potential applications as the resistive switching layer for next-generation memory devices, but, for practical applications, these materials should be utilized in high-density data-storage devices. Here, nanoscale memory devices are fabricated by sequential vapor deposition of organolead halide perovskite (OHP) CH 3 NH 3 PbI 3 layers on wafers perforated with 250 nm via-holes. These devices have bipolar resistive switching properties, and show low-voltage operation, fast switching speed (200 ns), good endurance, and data-retention time >10 5 s. Moreover, the use of sequential vapor deposition is extended to deposit CH 3 NH 3 PbI 3 as the memory element in a cross-point array structure. This method to fabricate high-density memory devices could be used for memory cells that occupy large areas, and to overcome the scaling limit of existing methods; it also presents a way to use OHPs to increase memory storage capacity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Working Memory for Linguistic and Non-linguistic Manual Gestures: Evidence, Theory, and Application.

PubMed

Rudner, Mary

2018-01-01

Linguistic manual gestures are the basis of sign languages used by deaf individuals. Working memory and language processing are intimately connected and thus when language is gesture-based, it is important to understand related working memory mechanisms. This article reviews work on working memory for linguistic and non-linguistic manual gestures and discusses theoretical and applied implications. Empirical evidence shows that there are effects of load and stimulus degradation on working memory for manual gestures. These effects are similar to those found for working memory for speech-based language. Further, there are effects of pre-existing linguistic representation that are partially similar across language modalities. But above all, deaf signers score higher than hearing non-signers on an n-back task with sign-based stimuli, irrespective of their semantic and phonological content, but not with non-linguistic manual actions. This pattern may be partially explained by recent findings relating to cross-modal plasticity in deaf individuals. It suggests that in linguistic gesture-based working memory, semantic aspects may outweigh phonological aspects when processing takes place under challenging conditions. The close association between working memory and language development should be taken into account in understanding and alleviating the challenges faced by deaf children growing up with cochlear implants as well as other clinical populations.

Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions.

PubMed

Murphy, Gillian; Greene, Ciara M

2016-01-01

Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals.

Perceptual Load Affects Eyewitness Accuracy and Susceptibility to Leading Questions

PubMed Central

Murphy, Gillian; Greene, Ciara M.

2016-01-01

Load Theory (Lavie, 1995, 2005) states that the level of perceptual load in a task (i.e., the amount of information involved in processing task-relevant stimuli) determines the efficiency of selective attention. There is evidence that perceptual load affects distractor processing, with increased inattentional blindness under high load. Given that high load can result in individuals failing to report seeing obvious objects, it is conceivable that load may also impair memory for the scene. The current study is the first to assess the effect of perceptual load on eyewitness memory. Across three experiments (two video-based and one in a driving simulator), the effect of perceptual load on eyewitness memory was assessed. The results showed that eyewitnesses were less accurate under high load, in particular for peripheral details. For example, memory for the central character in the video was not affected by load but memory for a witness who passed by the window at the edge of the scene was significantly worse under high load. High load memories were also more open to suggestion, showing increased susceptibility to leading questions. High visual perceptual load also affected recall for auditory information, illustrating a possible cross-modal perceptual load effect on memory accuracy. These results have implications for eyewitness memory researchers and forensic professionals. PMID:27625628

Working Memory for Linguistic and Non-linguistic Manual Gestures: Evidence, Theory, and Application

PubMed Central

Rudner, Mary

2018-01-01

Linguistic manual gestures are the basis of sign languages used by deaf individuals. Working memory and language processing are intimately connected and thus when language is gesture-based, it is important to understand related working memory mechanisms. This article reviews work on working memory for linguistic and non-linguistic manual gestures and discusses theoretical and applied implications. Empirical evidence shows that there are effects of load and stimulus degradation on working memory for manual gestures. These effects are similar to those found for working memory for speech-based language. Further, there are effects of pre-existing linguistic representation that are partially similar across language modalities. But above all, deaf signers score higher than hearing non-signers on an n-back task with sign-based stimuli, irrespective of their semantic and phonological content, but not with non-linguistic manual actions. This pattern may be partially explained by recent findings relating to cross-modal plasticity in deaf individuals. It suggests that in linguistic gesture-based working memory, semantic aspects may outweigh phonological aspects when processing takes place under challenging conditions. The close association between working memory and language development should be taken into account in understanding and alleviating the challenges faced by deaf children growing up with cochlear implants as well as other clinical populations. PMID:29867655

A Memory B Cell Crossmatch Assay for Quantification of Donor-Specific Memory B Cells in the Peripheral Blood of HLA-Immunized Individuals.

PubMed

Karahan, G E; de Vaal, Y J H; Krop, J; Wehmeier, C; Roelen, D L; Claas, F H J; Heidt, S

2017-10-01

Humoral responses against mismatched donor HLA are routinely measured as serum HLA antibodies, which are mainly produced by bone marrow-residing plasma cells. Individuals with a history of alloimmunization but lacking serum antibodies may harbor circulating dormant memory B cells, which may rapidly become plasma cells on antigen reencounter. Currently available methods to detect HLA-specific memory B cells are scarce and insufficient in quantifying the complete donor-specific memory B cell response due to their dependence on synthetic HLA molecules. We present a highly sensitive and specific tool for quantifying donor-specific memory B cells in peripheral blood of individuals using cell lysates covering the complete HLA class I and class II repertoire of an individual. Using this enzyme-linked immunospot (ELISpot) assay, we found a median frequency of 31 HLA class I and 89 HLA class II-specific memory B cells per million IgG-producing cells directed at paternal HLA in peripheral blood samples from women (n = 22) with a history of pregnancy, using cell lysates from spouses. The donor-specific memory B cell ELISpot can be used in HLA diagnostic laboratories as a cross-match assay to quantify donor-specific memory B cells in patients with a history of sensitizing events. © 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.

Nitrogen-doped partially reduced graphene oxide rewritable nonvolatile memory.

PubMed

Seo, Sohyeon; Yoon, Yeoheung; Lee, Junghyun; Park, Younghun; Lee, Hyoyoung

2013-04-23

As memory materials, two-dimensional (2D) carbon materials such as graphene oxide (GO)-based materials have attracted attention due to a variety of advantageous attributes, including their solution-processability and their potential for highly scalable device fabrication for transistor-based memory and cross-bar memory arrays. In spite of this, the use of GO-based materials has been limited, primarily due to uncontrollable oxygen functional groups. To induce the stable memory effect by ionic charges of a negatively charged carboxylic acid group of partially reduced graphene oxide (PrGO), a positively charged pyridinium N that served as a counterion to the negatively charged carboxylic acid was carefully introduced on the PrGO framework. Partially reduced N-doped graphene oxide (PrGODMF) in dimethylformamide (DMF) behaved as a semiconducting nonvolatile memory material. Its optical energy band gap was 1.7-2.1 eV and contained a sp2 C═C framework with 45-50% oxygen-functionalized carbon density and 3% doped nitrogen atoms. In particular, rewritable nonvolatile memory characteristics were dependent on the proportion of pyridinum N, and as the proportion of pyridinium N atom decreased, the PrGODMF film lost memory behavior. Polarization of charged PrGODMF containing pyridinium N and carboxylic acid under an electric field produced N-doped PrGODMF memory effects that followed voltage-driven rewrite-read-erase-read processes.

Is residual memory variance a valid method for quantifying cognitive reserve? A longitudinal application.

PubMed

Zahodne, Laura B; Manly, Jennifer J; Brickman, Adam M; Narkhede, Atul; Griffith, Erica Y; Guzman, Vanessa A; Schupf, Nicole; Stern, Yaakov

2015-10-01

Cognitive reserve describes the mismatch between brain integrity and cognitive performance. Older adults with high cognitive reserve are more resilient to age-related brain pathology. Traditionally, cognitive reserve is indexed indirectly via static proxy variables (e.g., years of education). More recently, cross-sectional studies have suggested that reserve can be expressed as residual variance in episodic memory performance that remains after accounting for demographic factors and brain pathology (whole brain, hippocampal, and white matter hyperintensity volumes). The present study extends these methods to a longitudinal framework in a community-based cohort of 244 older adults who underwent two comprehensive neuropsychological and structural magnetic resonance imaging sessions over 4.6 years. On average, residual memory variance decreased over time, consistent with the idea that cognitive reserve is depleted over time. Individual differences in change in residual memory variance predicted incident dementia, independent of baseline residual memory variance. Multiple-group latent difference score models revealed tighter coupling between brain and language changes among individuals with decreasing residual memory variance. These results suggest that changes in residual memory variance may capture a dynamic aspect of cognitive reserve and could be a useful way to summarize individual cognitive responses to brain changes. Change in residual memory variance among initially non-demented older adults was a better predictor of incident dementia than residual memory variance measured at one time-point. Copyright © 2015. Published by Elsevier Ltd.

A comparison of IQ and memory cluster solutions in moderate and severe pediatric traumatic brain injury.

PubMed

Thaler, Nicholas S; Terranova, Jennifer; Turner, Alisa; Mayfield, Joan; Allen, Daniel N

2015-01-01

Recent studies have examined heterogeneous neuropsychological outcomes in childhood traumatic brain injury (TBI) using cluster analysis. These studies have identified homogeneous subgroups based on tests of IQ, memory, and other cognitive abilities that show some degree of association with specific cognitive, emotional, and behavioral outcomes, and have demonstrated that the clusters derived for children with TBI are different from those observed in normal populations. However, the extent to which these subgroups are stable across abilities has not been examined, and this has significant implications for the generalizability and clinical utility of TBI clusters. The current study addressed this by comparing IQ and memory profiles of 137 children who sustained moderate-to-severe TBI. Cluster analysis of IQ and memory scores indicated that a four-cluster solution was optimal for the IQ scores and a five-cluster solution was optimal for the memory scores. Three clusters on each battery differed primarily by level of performance, while the others had pattern variations. Cross-plotting the clusters across respective IQ and memory test scores indicated that clusters defined by level were generally stable, while clusters defined by pattern differed. Notably, children with slower processing speed exhibited low-average to below-average performance on memory indexes. These results provide some support for the stability of previously identified memory and IQ clusters and provide information about the relationship between IQ and memory in children with TBI.

Is residual memory variance a valid method for quantifying cognitive reserve? A longitudinal application

PubMed Central

Zahodne, Laura B.; Manly, Jennifer J.; Brickman, Adam M.; Narkhede, Atul; Griffith, Erica Y.; Guzman, Vanessa A.; Schupf, Nicole; Stern, Yaakov

2016-01-01

Cognitive reserve describes the mismatch between brain integrity and cognitive performance. Older adults with high cognitive reserve are more resilient to age-related brain pathology. Traditionally, cognitive reserve is indexed indirectly via static proxy variables (e.g., years of education). More recently, cross-sectional studies have suggested that reserve can be expressed as residual variance in episodic memory performance that remains after accounting for demographic factors and brain pathology (whole brain, hippocampal, and white matter hyperintensity volumes). The present study extends these methods to a longitudinal framework in a community-based cohort of 244 older adults who underwent two comprehensive neuropsychological and structural magnetic resonance imaging sessions over 4.6 years. On average, residual memory variance decreased over time, consistent with the idea that cognitive reserve is depleted over time. Individual differences in change in residual memory variance predicted incident dementia, independent of baseline residual memory variance. Multiple-group latent difference score models revealed tighter coupling between brain and language changes among individuals with decreasing residual memory variance. These results suggest that changes in residual memory variance may capture a dynamic aspect of cognitive reserve and could be a useful way to summarize individual cognitive responses to brain changes. Change in residual memory variance among initially non-demented older adults was a better predictor of incident dementia than residual memory variance measured at one time-point. PMID:26348002

Children's Comprehension of Object Relative Sentences: It's Extant Language Knowledge That Matters, Not Domain-General Working Memory.

PubMed

Rusli, Yazmin Ahmad; Montgomery, James W

2017-10-17

The aim of this study was to determine whether extant language (lexical) knowledge or domain-general working memory is the better predictor of comprehension of object relative sentences for children with typical development. We hypothesized that extant language knowledge, not domain-general working memory, is the better predictor. Fifty-three children (ages 9-11 years) completed a word-level verbal working-memory task, indexing extant language (lexical) knowledge; an analog nonverbal working-memory task, representing domain-general working memory; and a hybrid sentence comprehension task incorporating elements of both agent selection and cross-modal picture-priming paradigms. Images of the agent and patient were displayed at the syntactic gap in the object relative sentences, and the children were asked to select the agent of the sentence. Results of general linear modeling revealed that extant language knowledge accounted for a unique 21.3% of variance in the children's object relative sentence comprehension over and above age (8.3%). Domain-general working memory accounted for a nonsignificant 1.6% of variance. We interpret the results to suggest that extant language knowledge and not domain-general working memory is a critically important contributor to children's object relative sentence comprehension. Results support a connectionist view of the association between working memory and object relative sentence comprehension. https://doi.org/10.23641/asha.5404573.

Tracking KLRC2 (NKG2C)+ memory-like NK cells in SIV+ and rhCMV+ rhesus macaques.

PubMed

Ram, Daniel R; Manickam, Cordelia; Hueber, Brady; Itell, Hannah L; Permar, Sallie R; Varner, Valerie; Reeves, R Keith

2018-05-01

Natural killer (NK) cells classically typify the nonspecific effector arm of the innate immune system, but have recently been shown to possess memory-like properties against multiple viral infections, most notably CMV. Expression of the activating receptor NKG2C is elevated on human NK cells in response to infection with CMV as well as HIV, and may delineate cells with memory and memory-like functions. A better understanding of how NKG2C+ NK cells specifically respond to these pathogens could be significantly advanced using nonhuman primate (NHP) models but, to date, it has not been possible to distinguish NKG2C from its inhibitory counterpart, NKG2A, in NHP because of unfaithful antibody cross-reactivity. Using novel RNA-based flow cytometry, we identify for the first time true memory NKG2C+ NK cells in NHP by gene expression (KLRC2), and show that these cells have elevated frequencies and diversify their functional repertoire specifically in response to rhCMV and SIV infections.

Tactile Ranschburg effects: facilitation and inhibitory repetition effects analogous to verbal memory.

PubMed

Roe, Daisy; Miles, Christopher; Johnson, Andrew J

2017-07-01

The present paper examines the effect of within-sequence item repetitions in tactile order memory. Employing an immediate serial recall procedure, participants reconstructed a six-item sequence tapped upon their fingers by moving those fingers in the order of original stimulation. In Experiment 1a, within-sequence repetition of an item separated by two-intervening items resulted in a significant reduction in recall accuracy for that repeated item (i.e., the Ranschburg effect). In Experiment 1b, within-sequence repetition of an adjacent item resulted in significant recall facilitation for that repeated item. These effects mirror those reported for verbal stimuli (e.g., Henson, 1998a . Item repetition in short-term memory: Ranschburg repeated. Journal of Experimental Psychology: Learning, Memory, and Cognition, 24(5), 1162-1181. doi:doi.org/10.1037/0278-7393.24.5.1162). These data are the first to demonstrate the Ranschburg effect with non-verbal stimuli and suggest further cross-modal similarities in order memory.

Titanium oxide nonvolatile memory device and its application

NASA Astrophysics Data System (ADS)

Wang, Wei

In recent years, the semiconductor memory industry has seen an ever-increasing demand for nonvolatile memory (NVM), which is fueled by portable consumer electronic applications like the mobile phone and MP3 player. FLASH memory has been the most widely used nonvolatile memories in these systems, and has successfully kept up with CMOS scaling for many generations. However, as FLASH memory faces major scaling challenges beyond 22nm, non-charge-based nonvolatile memories are widely researched as candidates to replace FLASH. Titanium oxide (TiOx) nonvolatile memory device is considered to be a promising choice due to its controllable nonvolatile memory switching, good scalability, compatibility with CMOS processing and potential for 3D stacking. However, several major issues need to be overcome before TiOx NVM device can be adopted in manufacturing. First, there exists a highly undesirable high-voltage stress initiation process (FORMING) before the device can switch between high and low resistance states repeatedly. By analyzing the conductive behaviors of the memory device before and after FORMING, we propose that FORMING involves breaking down an interfacial layer between its Pt electrode and the TiOx thin film, and that FORMING is not needed if the Pt-TiOx interface can be kept clean during fabrication. An in-situ fabrication process is developed for cross-point TiOx NVM device, which enables in-situ deposition of the critical layers of the memory device and thus achieves clean interfaces between Pt electrodes and TiOx film. Testing results show that FORMING is indeed eliminated for memory devices made with the in-situ fabrication process. It verifies the significance of in-situ deposition without vacuum break in the fabrication of TiOx NVM devices. Switching parameters statistics of TiOx NVM devices are studied and compared for unipolar and bipolar switching modes. RESET mechanisms are found to be different for the two switching modes: unipolar switching can be explained by thermal dissolution model, and bipolar switching by local redox reaction model. Since it is generally agreed that the memory switching of TiOx NVM devices is based on conductive filaments, reusability of these conductive filaments becomes an intriguing issue to determine the memory device's endurance. A 1X3 cross-point test structure is built to investigate whether conductive filaments can be reused after RESET. It is found that the conductive filament is destroyed during unipolar switching, while can be reused during bipolar switching. The result is a good indication that bipolar switching should have better endurance than unipolar switching. Finally a novel application of the two-terminal resistive switching NVM devices is demonstrated. To reduce SRAM leakage power, we propose a nonvolatile SRAM cell with two back-up NVM devices. This novel cell offers nonvolatile storage, thus allowing selected blocks of SRAM to be powered down during operation. There is no area penalty in this approach. Only a slight performance penalty is expected.

Cross–dressers turn on T cells

PubMed Central

YEWDELL, JONATHAN W.; DOLAN, BRIAN P.

2012-01-01

Memory T cells remember viruses from previous infections, providing immunity by facilitating the killing of infected cells. For this, they exploit cross-dressing, the transfer of antigens between antigen-presenting cells. PMID:21455165

The avidity of cross-reactive virus-specific T cells for their viral and allogeneic epitopes is variable and depends on epitope expression.

PubMed

van den Heuvel, Heleen; Heutinck, Kirstin M; van der Meer-Prins, Ellen M W; Franke-van Dijk, Marry E I; van Miert, Paula P M C; Zhang, Xiaoqian; Ten Berge, Ineke J M; Claas, Frans H J

2018-01-01

Virus-specific T cells can recognize allogeneic HLA (allo-HLA) through cross-reactivity of their T-cell receptor (TCR). In a transplantation setting, such allo-HLA cross-reactivity may contribute to harmful immune responses towards the allograft, provided that the cross-reactive T cells get sufficiently activated upon recognition of the allo-HLA. An important determinant of T-cell activation is TCR avidity, which to date, has remained largely unexplored for allo-HLA-cross-reactive virus-specific T cells. For this purpose, cold target inhibition assays were performed using allo-HLA-cross-reactive virus-specific memory CD8 + T-cell clones as responders, and syngeneic cells loaded with viral peptide and allogeneic cells as hot (radioactively-labeled) and cold (non-radioactively-labeled) targets. CD8 dependency of the T-cell responses was assessed using interferon γ (IFNγ) enzyme-linked immunosorbent assay (ELISA) in the presence and absence of CD8-blocking antibodies. At high viral-peptide loading concentrations, T-cell clones consistently demonstrated lower avidity for allogeneic versus viral epitopes, but at suboptimal concentrations the opposite was observed. In line, anti-viral reactivity was CD8 independent at high, but not at suboptimal viral-peptide-loading concentrations. The avidity of allo-HLA-cross-reactive virus-specific memory CD8 + T cells is therefore highly dependent on epitope expression, and as a consequence, can be both higher and lower for allogeneic versus viral targets under different (patho)physiological conditions. Copyright © 2017 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

Replicating the positivity effect in picture memory in Koreans: evidence for cross-cultural generalizability.

PubMed

Kwon, Yookyung; Scheibe, Susanne; Samanez-Larkin, Gregory R; Tsai, Jeanne L; Carstensen, Laura L

2009-09-01

Older adults' relatively better memory for positive over negative material (positivity effect) has been widely observed in Western samples. This study examined whether a relative preference for positive over negative material is also observed in older Koreans. Younger and older Korean participants viewed images from the International Affective Picture System (IAPS), were tested for recall and recognition of the images, and rated the images for valence. Cultural differences in the valence ratings of images emerged. Once considered, the relative preference for positive over negative material in memory observed in older Koreans was indistinguishable from that observed previously in older Americans. (c) 2009 APA, all rights reserved.

Focused ion beam and field-emission microscopy of metallic filaments in memory devices based on thin films of an ambipolar organic compound consisting of oxadiazole, carbazole, and fluorene units

USGS Publications Warehouse

Pearson, Christopher; Bowen, Leon; Lee, Myung Won; Fisher, Alison L.; Linton, Katherine E.; Bryce, Martin R.; Petty, Michael C.

2013-01-01

We report on the mechanism of operation of organic thin film resistive memory architectures based on an ambipolar compound consisting of oxadiazole, carbazole, and fluorene units. Cross-sections of the devices have been imaged by electron microscopy both before and after applying a voltage. The micrographs reveal the growth of filaments, with diameters of 50 nm–100 nm, on the metal cathode. We suggest that these are formed by the drift of aluminium ions from the anode and are responsible for the observed switching and negative differential resistance phenomena in the memory devices.

Are Cross-National Differences in IQ Profiles Stable? A Comparison of Finnish and U.S. WAIS Norms

ERIC Educational Resources Information Center

Roivainen, Eka

2013-01-01

To study the concept of national IQ profile, we compared U.S. and Finnish WAIS, WAIS-R, and WAIS III nonverbal and working memory subtest norms. The U.S. standardization samples had consistently higher scores on the Coding and Digit span subtests, while the Finnish samples had higher scores on the Block design subtest. No stable cross-national…

Does widowhood affect memory performance of older persons?

PubMed

Aartsen, Marja J; Van Tilburg, Theo; Smits, Carolien H M; Comijs, Hannie C; Knipscheer, Kees C P M

2005-02-01

The loss of a spouse has been found to have a negative effect on physical and mental health and leads to increased mortality. Whether conjugal bereavement also affects memory functioning has largely been unexamined. The present study investigates the effect of widowhood on memory functioning in older persons. The sample consisted of 474 married women and 690 married men aged 60-85 years in 1992, followed up in 1995 and 1998. During the study 135 (28%) of the women and 69 (10%) of the men lost their spouse. Linear regression analysis was used to examine whether widowed men and women differed from those who had not been widowed in rate of memory change over 6 years. Cross-domain latent-change models were subsequently used to evaluate the extent to which changes in memory are related to changes in other domains of functioning that may be affected by widowhood. Older adults who lost a spouse during follow-up showed a greater decline in memory over 6 years than those who remained married. A higher level of depressive symptoms at baseline was related to lower levels of memory functioning and a greater decline. Memory decline was unrelated to changes in depressive symptoms and physical health. Loss of the spouse is related to a greater decline in memory in older adults. The absence of an association with physical functioning and the weak association with mental functioning suggest that losing a spouse has an independent effect on memory functioning.

Effects of treadmill exercise intensity on spatial working memory and long-term memory in rats.

PubMed

Wang, Xiao-Qin; Wang, Gong-Wu

2016-03-15

Moderate exercise promotes learning and memory. Most studies mainly focused on memory exercise effects of in the ageing and patients. There is lack of quantitative research about effect of regular exercise intensity on different memory types in normal subjects. Present study investigated the effects of different intensities of treadmill exercise on working memory and long-term memory. Fifty female Wistar rats were trained by T-maze delayed spatial alternation (DSA) task with 3 delays (10s, 60s and 300s). Then they got a 30min treadmill exercise for 30days in 4 intensities (control, 0m/min; lower, 15m/min; middle, 20m/min, and higher, 30m/min). Then animals were tested in DSA, passive avoidance and Morris water maze tasks. 1. Exercise increased the neuronal density of hippocampal subregions (CA1, CA3 and dentate gyrus) vs. naïve/control. 2. In DSA task, all groups have similar baseline, lower intensity improved 10s delay accuracy vs. baseline/control; middle and higher intensities improved 300s delay accuracy vs. baseline/control. 3. In water maze learning, all groups successfully found the platform, but middle intensity improved platform field crossing times vs. control in test phase. Present results suggested that treadmill exercise can improve long-term spatial memory and working memory; lower intensity benefits to short-term delayed working memory, and middle or higher intensity benefits to long-term delayed working memory. There was an inverted U dose-effect relationship between exercise intensity and memory performance, but exercise -working memory effect was impacted by delay duration. Copyright © 2016 Elsevier Inc. All rights reserved.

Obesity and episodic memory function.

PubMed

Loprinzi, Paul D; Frith, Emily

2018-04-17

Obesity-related lifestyle factors, such as physical activity behavior and dietary intake, have been shown to be associated with episodic memory function. From animal work, there is considerable biological plausibility linking obesity with worse memory function. There are no published systematic reviews evaluating the effects of obesity on episodic memory function among humans, and examining whether physical activity and diet influences this obesity-memory link. Thus, the purpose of this systematic review was to evaluate the totality of research examining whether obesity is associated with episodic memory function, and whether physical activity and dietary behavior confounds this relationship. A review approach was employed, using PubMed, PsychInfo, and Sports Discus databases. Fourteen studies met our criteria. Among these 14 reviewed studies, eight were cross-sectional, four were prospective, and two employed a randomized controlled experimental design. Twelve of the 14 studies did not take into consideration dietary behavior in their analysis, and similarly, nine of the 14 studies did not take into consideration participant physical activity behavior. Among the 14 studies, ten found an inverse association of weight status on memory function, but for one of these studies, this association was attenuated after controlling for physical activity. Among the 14 evaluated studies, four did not find a direct effect of weight status on memory. Among the four null studies, one, however, found an indirect effect of BMI on episodic memory and another found a moderation effect of BMI and age on memory function. It appears that obesity may be associated with worse memory function, with the underlying mechanisms discussed herein. At this point, it is uncertain whether adiposity, itself, is influencing memory changes, or rather, whether adiposity-related lifestyle behaviors (e.g., physical inactivity and diet) are driving the obesity-memory relationship.

Improved cache performance in Monte Carlo transport calculations using energy banding

NASA Astrophysics Data System (ADS)

Siegel, A.; Smith, K.; Felker, K.; Romano, P.; Forget, B.; Beckman, P.

2014-04-01

We present an energy banding algorithm for Monte Carlo (MC) neutral particle transport simulations which depend on large cross section lookup tables. In MC codes, read-only cross section data tables are accessed frequently, exhibit poor locality, and are typically too much large to fit in fast memory. Thus, performance is often limited by long latencies to RAM, or by off-node communication latencies when the data footprint is very large and must be decomposed on a distributed memory machine. The proposed energy banding algorithm allows maximal temporal reuse of data in band sizes that can flexibly accommodate different architectural features. The energy banding algorithm is general and has a number of benefits compared to the traditional approach. In the present analysis we explore its potential to achieve improvements in time-to-solution on modern cache-based architectures.

Preliminary findings on the Cross Cultural Test Of Face Recognition.

PubMed

O'Bryant, Sid E; McCaffrey, Robert J

2006-01-01

The utility of psychological tests cross-culturally has received a great deal of attention in psychology. However, this same level of attentiveness has yet to be realized in the field of neuropsychology. One such area of neuropsychological assessment that may be negatively impacted by racial and ethnic variables is the assessment of facial memory. There is a plethora of literature in cognitive psychology demonstrating an own-race recognition bias in human face memory. Simply stated, individuals are more apt to accurately remember faces of individuals who are of their own race rather than those of other races. Study 1 was conducted to evaluate the performance of the Cross Cultural Test of Face Recognition (CCTFR) in a diverse sample of non impaired individuals. Results suggested the presence of an own-race recognition bias present, but this had no impact on overall CCTFR performance. Study 2 was conducted to determine if CVA patients would perform more poorly than community controls on the CCTFR. As predicted, community controls significantly outperformed CVA patients, and the CCTFR demonstrated a moderate level of sensitivity and specificity. Combined, the results of these studies provide preliminary support for the utility of the CCTFR in the neuropsychological assessment of diverse patient populations. Clearly more research is needed to support the utility of this new test of face recognition, but preliminary results suggest that it may be a viable option for the assessment of visual memory across a spectrum of ethnic groups.

Dorsolateral prefrontal cortex bridges bilateral primary somatosensory cortices during cross-modal working memory.

PubMed

Zhao, Di; Ku, Yixuan

2018-05-01

Neural activity in the dorsolateral prefrontal cortex (DLPFC) has been suggested to integrate information from distinct sensory areas. However, how the DLPFC interacts with the bilateral primary somatosensory cortices (SIs) in tactile-visual cross-modal working memory has not yet been established. In the present study, we applied single-pulse transcranial magnetic stimulation (sp-TMS) over the contralateral DLPFC and bilateral SIs of human participants at various time points, while they performed a tactile-visual delayed matching-to-sample task with a 2-second delay. sp-TMS over the contralateral DLPFC or the contralateral SI at either an sensory encoding stage [i.e. 100 ms after the onset of a vibrotactile sample stimulus (200-ms duration)] or an early maintenance stage (i.e. 300 ms after the onset), significantly impaired the accuracy of task performance; sp-TMS over the contralateral DLPFC or the ipsilateral SI at a late maintenance stage (1600 ms and 1900 ms) also significantly disrupted the performance. Furthermore, at 300 ms after the onset of the vibrotactile sample stimulus, there was a significant correlation between the deteriorating effects of sp-TMS over the contralateral SI and the contralateral DLPFC. These results imply that the DLPFC and the bilateral SIs play causal roles at distinctive stages during cross-modal working memory, while the contralateral DLPFC communicates with the contralateral SI in the early delay, and cooperates with the ipsilateral SI in the late delay. Copyright © 2018 Elsevier B.V. All rights reserved.

Fragmented pictures revisited: long-term changes in repetition priming, relation to skill learning, and the role of cognitive resources.

PubMed

Kennedy, Kristen M; Rodrigue, Karen M; Raz, Naftali

2007-01-01

Whereas age-related declines in declarative memory have been demonstrated in multiple cross-sectional and longitudinal studies, the effect of age on non-declarative manifestations of memory, such as repetition priming and perceptual skill learning, are less clear. The common assumption, based on cross-sectional studies, is that these processes are only mildly (if at all) affected by age. To investigate long-term changes in repetition priming and age-related differences in identification of fragmented pictures in a 5-year longitudinal design. Healthy adults (age 28-82 years) viewed drawings of objects presented in descending order of fragmentation. The identification threshold (IT) was the highest fragmentation level at which the object was correctly named. After a short interval, old pictures were presented again along with a set of similar but novel pictures. Five years later the participants repeated the experiment. At baseline and 5-year follow-up alike, one repeated exposure improved IT for old (priming) and new (skill acquisition) pictures. However, long-term retention of priming gains was observed only in young adults. Working memory explained a significant proportion of variance in within-occasion priming, long-term priming, and skill learning. Contrary to cross-sectional results, this longitudinal study suggests perceptual repetition priming is not an age-invariant phenomenon and advanced age and reduced availability of cognitive resources may contribute to its decline. Copyright 2007 S. Karger AG, Basel.

Selective verbal and spatial memory impairment after 5-HT1A and 5-HT2A receptor blockade in healthy volunteers pre-treated with an SSRI.

PubMed

Wingen, M; Kuypers, K P C; Ramaekers, J G

2007-07-01

Serotonergic neurotransmission has been implicated in memory impairment. It is unclear however if memory performance is mediated through general 5-HT availability, through specific 5-HT receptors or both. The aim of the present study was to assess the contribution of 5-HT reuptake inhibition and specific blockade of 5-HT(1A) and 5-HT(2A) receptors to memory impairment. The study was conducted according to a randomized, double-blind, placebo-controlled, four-way cross-over design including 16 healthy volunteers. The treatment consisted of oral administration of escitalopram 20 mg + placebo, escitalopram 20 mg + ketanserin 50 mg, escitalopram 20 mg + pindolol 10 mg and placebo on 4 separate days with a washout period of minimum 7 days. Different memory tasks were performed including verbal memory, spatial working memory and reversal learning. Escitalopram showed an impairing effect on immediate verbal recall which nearly reached statistical significance. No effects of escitalopram were found on other types of memory. In combination with pindolol, immediate verbal recall was significantly impaired. Escitalopram in combination with ketanserin impaired spatial working memory significantly. No effects were found on reversal learning. Selective impairment of immediate verbal recall after a 5-HT(1A) partial agonist and selective impairment of spatial working memory performance after 5-HT(2A) receptor antagonist, both in combination with a selective serotonergic reuptake inhibitor (escitalopram), suggests that 5-HT(1A) and 5-HT(2A) receptors are distinctly involved in verbal and spatial memory.

Advancing reversible shape memory by tuning the polymer network architecture

DOE PAGES

Li, Qiaoxi; Zhou, Jing; Vatankhah-Varnoosfaderani, Mohammad; ...

2016-02-02

Because of counteraction of a chemical network and a crystalline scaffold, semicrystalline polymer networks exhibit a peculiar behavior—reversible shape memory (RSM), which occurs naturally without applying any external force and particular structural design. There are three RSM properties: (i) range of reversible strain, (ii) rate of strain recovery, and (iii) decay of reversibility with time, which can be improved by tuning the architecture of the polymer network. Different types of poly(octylene adipate) networks were synthesized, allowing for control of cross-link density and network topology, including randomly cross-linked network by free-radical polymerization, thiol–ene clicked network with enhanced mesh uniformity, and loosemore » network with deliberately incorporated dangling chains. It is shown that the RSM properties are controlled by average cross-link density and crystal size, whereas topology of a network greatly affects its extensibility. In conclusion, we have achieved 80% maximum reversible range, 15% minimal decrease in reversibility, and fast strain recovery rate up to 0.05 K –1, i.e., ca. 5% per 10 s at a cooling rate of 5 K/min.« less

Role of hippocampal and prefrontal cortical signaling pathways in dextromethorphan effect on morphine-induced memory impairment in rats.

PubMed

Ghasemzadeh, Zahra; Rezayof, Ameneh

2016-02-01

Evidence suggests that dextromethorphan (DM), an NMDA receptor antagonist, induces memory impairment. Considering that DM is widely used in cough-treating medications, and the co-abuse of DM with morphine has recently been reported, the aims of the present study was (1) to investigate whether there is a functional interaction between morphine and DM in passive avoidance learning and (2) to assess the possible role of the hippocampal and prefrontal cortical (PFC) signaling pathways in the effects of the drugs on memory formation. Our findings indicated that post-training or pre-test administration of morphine (2 and 6 mg/kg) or DM (10-30 mg/kg) impaired memory consolidation and retrieval which was associated with the attenuation of the levels of phosphorylated Ca(2+)/calmodulin-dependent protein kinase II (p-CAMKII) and cAMP responsive element-binding protein (p-CREB) in the targeted sites. Moreover, the memory impairment induced by post-training administration of morphine was reversed by pre-test administration of the same dose of morphine or DM (30 mg/kg), indicating state-dependent learning (SDL) and a cross-SDL between the drugs. It is important to note that the levels of p-CAMKII/CAMKII and p-CREB/CREB in the hippocampus and the PFC increased in drugs-induced SDL. In addition, DM administration potentiated morphine-induced SDL which was related to the enhanced levels of hippocampal and PFC CAMKII-CREB signaling pathways. It can be concluded that there is a relationship between the hippocampus and the PFC in the effect of DM and/or morphine on memory retrieval. Moreover, a cross SDL can be induced between the co-administration of DM and morphine. Interestingly, CAMKII-CREB signaling pathways also mediate the drugs-induced SDL. Copyright © 2015 Elsevier Inc. All rights reserved.

A Novel 1,4-Dihydropyridine Derivative Improves Spatial Learning and Memory and Modifies Brain Protein Expression in Wild Type and Transgenic APPSweDI Mice.

PubMed

Jansone, Baiba; Kadish, Inga; van Groen, Thomas; Beitnere, Ulrika; Moore, Doyle Ray; Plotniece, Aiva; Pajuste, Karlis; Klusa, Vija

2015-01-01

Ca2+ blockers, particularly those capable of crossing the blood-brain barrier (BBB), have been suggested as a possible treatment or disease modifying agents for neurodegenerative disorders, e.g., Alzheimer's disease. The present study investigated the effects of a novel 4-(N-dodecyl) pyridinium group-containing 1,4-dihydropyridine derivative (AP-12) on cognition and synaptic protein expression in the brain. Treatment of AP-12 was investigated in wild type C57BL/6J mice and transgenic Alzheimer's disease model mice (Tg APPSweDI) using behavioral tests and immunohistochemistry, as well as mass spectrometry to assess the blood-brain barrier (BBB) penetration. The data demonstrated the ability of AP-12 to cross the BBB, improve spatial learning and memory in both mice strains, induce anxiolytic action in transgenic mice, and increase expression of hippocampal and cortical proteins (GAD67, Homer-1) related to synaptic plasticity. The compound AP-12 can be seen as a prototype molecule for use in the design of novel drugs useful to halt progression of clinical symptoms (more specifically, anxiety and decline in memory) of neurodegenerative diseases, particularly Alzheimer's disease.

Improved self-healing of polyethylene/carbon black nanocomposites by their shape memory effect.

PubMed

Wang, Xiaoyan; Zhao, Jun; Chen, Min; Ma, Lan; Zhao, Xiaodong; Dang, Zhi-Min; Wang, Zhenwen

2013-02-07

In this work, the improved self-healing of cross-linked polyethylene (PE) (cPE)/carbon black (CB) nanocomposites by their shape memory effect (SME) is investigated. CB nanoparticles are found to be homogeneously dispersed in the PE matrix and significantly increase the strength of the materials. Compared with the breaking of linear PE (lPE) at the melting temperature (T(m)), the cPE and cPE/CB nanocomposites still have high strength above T(m) due to the formation of networks. The cPE and cPE/CB nanocomposites show both high strain fixity ratio (R(f)) and high strain recovery ratio (R(r)). Crystallization-induced elongation is observed for all the prepared shape memory polymer (SMP) materials and the effect becomes less remarkable with increasing volume fraction of CB nanoparticles (v(CB)). The scratch self-healing tests show that the cross-linking of PE matrix, the addition of CB nanoparticles, and the previous stretching in the direction perpendicular to the scratch favor the closure of the scratch and its complete healing. This SME-aided self-healing could have potential applications in diverse fields such as coating and structure materials.

Effect of Cross-linking Density on Creep and Recovery Behavior in Epoxy-Based Shape Memory Polymers (SMEPs) for Structural Applications

NASA Astrophysics Data System (ADS)

Rao, Kavitha V.; Ananthapadmanabha, G. S.; Dayananda, G. N.

2016-12-01

Epoxy-based shape memory polymers (SMEPs) are gaining importance in the area of aerospace structures due to their high strength and stiffness which is a primary requirement for an SMEP in structural applications. The understanding of viscoelastic behavior of SMEPs is very essential to assess their shape memory effect. In the present work, three types of SMEPs with varying cross-linking densities were developed by curing an aromatic epoxy resin with aliphatic amines. Glass transition temperature ( T g) was measured for these SMEPs using advanced rheometric expansion system, and from the T g measurements, a range of temperatures from glassy to rubbery regimes were chosen. At selected temperatures, creep-recovery tests were performed in order to evaluate the viscoelastic behavior of SMEPs and also to investigate the effect of temperature on creep-recovery. Further, a three-parameter viscoelastic model (Zener) was used to fit the data obtained from experiments. Model parameters like moduli of the springs and viscosity of the dashpot were evaluated by curve fitting. Results revealed that Zener model was well suited to describe the viscoelastic behavior of SMEPs as a function of test temperatures.

Modeling and optimization of shape memory-superelastic antagonistic beam assembly

NASA Astrophysics Data System (ADS)

Tabesh, Majid; Elahinia, Mohammad H.

2010-04-01

Superelasticity (SE), shape memory effect (SM), high damping capacity, corrosion resistance, and biocompatibility are the properties of NiTi that makes the alloy ideal for biomedical devices. In this work, the 1D model developed by Brinson was modified to capture the shape memory effect, superelasticity and hysteresis behavior, as well as partial transformation in both positive and negative directions. This model was combined with the Euler beam equation which, by approximation, considers 1D compression and tension stress-strain relationships in different layers of a 3D beam assembly cross-section. A shape memory-superelastic NiTi antagonistic beam assembly was simulated with this model. This wire-tube assembly is designed to enhance the performance of the pedicle screws in osteoporotic bones. For the purpose of this study, an objective design is pursued aiming at optimizing the dimensions and initial configurations of the SMA wire-tube assembly.

Formation of visual memories controlled by gamma power phase-locked to alpha oscillations.

PubMed

Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jiang, Haiteng; Gross, Joachim; Jensen, Ole

2016-06-16

Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity.

Inefficient Or Insufficient Encoding As Potential Primary Deficit In Neurodevelopmental Performance Among Children with OSA

PubMed Central

Spruyt, Karen; Capdevila, Oscar Sans; Kheirandish-Gozal, Leila; Gozal, David

2010-01-01

Memory (M) impairments have been suggested in pediatric Obstructive Sleep Apnea along with attention and executive (AE), language (L) and visuospatial (V) dysfunctions. NEPSY assessment of children aged 5–9-years who were either healthy (n= 43), or who had OSA without L, V, AE (OSA−, n= 22) or with L (n=6), V (n=1), AE (n=3) (OSA+, n=10) dysfunctions revealed no gross memory problems in OSA; however, over the 3 learning trials of cross-modal association learning of name with face, the OSA− progressively improved performance, whereas the OSA+ failed to progress. No within-group differences between immediate and delayed memory tasks were apparent. The data suggest the presence of slower information processing, and/or secondary memory problems, in the absence of retrieval or recall impairments among a subset of children with OSA. We hypothesize that inefficient/insufficient encoding may account for the primary deficit. PMID:20183722

Formation of visual memories controlled by gamma power phase-locked to alpha oscillations

PubMed Central

Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jiang, Haiteng; Gross, Joachim; Jensen, Ole

2016-01-01

Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity. PMID:27306959

Formation of visual memories controlled by gamma power phase-locked to alpha oscillations

NASA Astrophysics Data System (ADS)

Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jiang, Haiteng; Gross, Joachim; Jensen, Ole

2016-06-01

Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity.

Flexible Endian Adjustment for Cross Architecture Binary Translation

NASA Astrophysics Data System (ADS)

Zhu, Tong; Liu, Bo; Guan, Haibing; Liang, Alei

Different architectures and/or ISA (Instruction Set Architecture) representations hold different data arranging formats in the memory. Therefore, the adjustment of byte packing order (endianness) is indispensable in cross- architecture binary translation if the source and target machines are of heterogeneous endianness, which may otherwise cause system failure. The issue is inconspicuous but may lead to significant performance bottleneck. This paper investigates the key aspects of endianness and finds several solutions to endian adjustment for cross-architecture binary translation. In particular, it considers the two principal methods of this field - byte swapping and address swizzling, and gives a comparison of them in our DBT (Dynamic Binary Translator) - CrossBit.

Do Working Memory Deficits Underlie Reading Problems in Attention-Deficit/Hyperactivity Disorder (ADHD)?

PubMed

Kofler, Michael J; Spiegel, Jamie A; Soto, Elia F; Irwin, Lauren N; Wells, Erica L; Austin, Kristin E

2018-06-19

Reading problems are common in children with ADHD and show strong covariation with these children's underdeveloped working memory abilities. In contrast, working memory training does not appear to improve reading performance for children with ADHD or neurotypical children. The current study bridges the gap between these conflicting findings, and combines dual-task methodology with Bayesian modeling to examine the role of working memory for explaining ADHD-related reading problems. Children ages 8-13 (M = 10.50, SD = 1.59) with and without ADHD (N = 78; 29 girls; 63% Caucasian/Non-Hispanic) completed a counterbalanced series of reading tasks that systematically manipulated concurrent working memory demands. Adding working memory demands produced disproportionate decrements in reading comprehension for children with ADHD (d = -0.67) relative to Non-ADHD children (d = -0.18); comprehension was significantly reduced in both groups when working memory demands were increased. These effects were robust to controls for foundational reading skills (decoding, sight word vocabulary) and comorbid reading disability. Concurrent working memory demands did not slow reading speed for either group. The ADHD group showed lower comprehension (d = 1.02) and speed (d = 0.69) even before adding working memory demands beyond those inherently required for reading. Exploratory conditional effects analyses indicated that underdeveloped working memory overlapped with 41% (comprehension) and 85% (speed) of these between-group differences. Reading problems in ADHD appear attributable, at least in part, to their underdeveloped working memory abilities. Combined with prior cross-sectional and longitudinal findings, the current experimental evidence positions working memory as a potential causal mechanism that is necessary but not sufficient for effectively understanding written language.

Effects of subchronic benzo(a)pyrene exposure on neurotransmitter receptor gene expression in the rat hippocampus related with spatial learning and memory change.

PubMed

Qiu, Chongying; Cheng, Shuqun; Xia, Yinyin; Peng, Bin; Tang, Qian; Tu, Baijie

2011-11-18

Exposure of laboratory rats to Benzo(a)pyrene (BaP), an environmental contaminant with its high lipophilicify which is widely dispersed in the environment and can easily cross the blood brain barrier presenting in the central nervous system, is associated with impaired learning and memory. The purpose of the research was to examine whether subchronic exposure to BaP affects spatial learning and memory, and how it alters normal gene expression in hippocampus, as well as selection of candidate genes involving neurotransmitter receptor attributed to learning and memory. Morris water maze (MWM) was used to evaluate behavioral differences between BaP-treated and vehicle-treated groups. To gain a better insight into the mechanism of BaP-induced neurotoxicity on learning and memory, we used whole genome oligo microarrays as well as Polymerase Chain Reaction (PCR) to assess the global impact of gene expression. Male Sprague-Dawley rats were intraperitoneally injected with 6.25mg/kg of BaP or vehicle for 14 weeks. The results from the Morris water maze (MWM) test showed that rats treated with BaP exhibited significantly higher mean latencies as compared to vehicle controls. BaP exposure significantly decreased the number of crossing the platform and the time spent in the target area. After the hippocampus was collected from each rat, total RNA was isolated. Microarray and PCR revealed that exposure to BaP affected mRNA expression of neurotransmitter receptors. The web tool DAVID was used to analyze the significantly enriched gene ontology (GO) and KEGG pathways in the differentially expressed genes. Analysis showed that the most significantly affected gene ontology category was behavior. Furthermore, the fourth highest significantly affected gene ontology category was learning and memory. KEGG molecular pathway analysis showed that "neuroactive ligand-receptor interaction" was affected by BaP with highest statistical significance, and 9 candidate neurotransmitter receptor genes involving learning and memory were selected out. Our results revealed a close link between behavioral changes and altered neurotransmitter receptor gene expression in BaP-treated rats. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Genetics at school level: addressing the difficulties

NASA Astrophysics Data System (ADS)

Chu, Yu-Chien; Reid, Norman

2012-11-01

Background : A wide range of studies has offered suggestions why genetics is difficult and some of their key findings are summarised. Underpinning all of this is the way the brain works when handling information. The limitations of working memory capacity offer an interpretation of these difficulties Purpose : The aim is to confirm that working memory capacity (and the related concept of field dependency) controls performance in understanding genetics and whether it is possible to improve performance by changing the teaching approach to mininise overload. Programme description : The curriculum in Taiwan in genetics is outlined briefly. A wide range of measurements were made. Using a diagnostic test of understanding of underpinning ideas, the key areas of weakness were detected before the pupils started the course. Sample : Stage 1: 141 students in Taiwan, aged 13, boys and girls, drawn from a cross-section of Taiwanese pupils at this age, following their first course in genetics. Stage 2: 361 students, drawn from a cross-section of Taiwanese pupils at the same age, and divided into two groups (experimental-control) which both encompass the same ability range. Design and methods : Stage 1: test of pre-knowledge using structural communication grids, applied before the course commenced; working memory capacity using the figural intersection test; extent of field dependency using the group embedded figure test; understanding of genetics was measured at end of course; school test data collated. Stage 2: following a completely revised approach, performance in genetics was measured using traditional school tests and a word association test. Student perspectives were measured. Results : The test of pre-knowledge revealed key areas of difficulty. In addition, it was found that working memory capacity and extent of field dependency both correlated extremely highly with all measures of performance. Given that it has been established that working memory capacity controls performance, working memory demand explains why genetics is difficult. It was found that re-structuring the teaching approach to minimise mental overload brought about a very marked improvement in performance. Conclusions : The findings suggest that it is possible to reduce difficulties in understanding genetics by means of teaching re-design to minimise potential working memory overload, with concomitant improvements in learner confidence.

Developing a Non-Language Related Span Test for the Use in Language-Specific and Cross-Language Studies

ERIC Educational Resources Information Center

Shahnazari-Dorcheh, Mohammadtaghi; Roshan, Saeed

2012-01-01

Due to the lack of span test for the use in language-specific and cross-language studies, this study provides L1 and L2 researchers with a reliable language-independent span test (math span test) for the measurement of working memory capacity. It also describes the development, validation, and scoring method of this test. This test included 70…

Cerebral Glucose Metabolism is Associated with Verbal but not Visual Memory Performance in Community-Dwelling Older Adults.

PubMed

Gardener, Samantha L; Sohrabi, Hamid R; Shen, Kai-Kai; Rainey-Smith, Stephanie R; Weinborn, Michael; Bates, Kristyn A; Shah, Tejal; Foster, Jonathan K; Lenzo, Nat; Salvado, Olivier; Laske, Christoph; Laws, Simon M; Taddei, Kevin; Verdile, Giuseppe; Martins, Ralph N

2016-03-31

Increasing evidence suggests that Alzheimer's disease (AD) sufferers show region-specific reductions in cerebral glucose metabolism, as measured by [18F]-fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET). We investigated preclinical disease stage by cross-sectionally examining the association between global cognition, verbal and visual memory, and 18F-FDG PET standardized uptake value ratio (SUVR) in 43 healthy control individuals, subsequently focusing on differences between subjective memory complainers and non-memory complainers. The 18F-FDG PET regions of interest investigated include the hippocampus, amygdala, posterior cingulate, superior parietal, entorhinal cortices, frontal cortex, temporal cortex, and inferior parietal region. In the cohort as a whole, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in both the left hippocampus and right amygdala. There were no associations observed between global cognition, delayed recall in logical memory, or visual reproduction and 18F-FDG PET SUVR. Following stratification of the cohort into subjective memory complainers and non-complainers, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in the right amygdala in those with subjective memory complaints. There were no significant associations observed in non-memory complainers between 18F-FDG PET SUVR in regions of interest and cognitive performance. We observed subjective memory complaint-specific associations between 18F-FDG PET SUVR and immediate verbal memory performance in our cohort, however found no associations between delayed recall of verbal memory performance or visual memory performance. It is here argued that the neural mechanisms underlying verbal and visual memory performance may in fact differ in their pathways, and the characteristic reduction of 18F-FDG PET SUVR observed in this and previous studies likely reflects the pathophysiological changes in specific brain regions that occur in preclinical AD.

An fMRI study of episodic encoding across the lifespan: changes in subsequent memory effects are evident by middle-age.

PubMed

Park, Heekyeong; Kennedy, Kristen M; Rodrigue, Karen M; Hebrank, Andrew; Park, Denise C

2013-02-01

Although it is well-documented that there are age differences between young and older adults in neural activity associated with successful memory formation (positive subsequent memory effects), little is known about how this activation differs across the lifespan, as few studies have included middle-aged adults. The present study investigated the effect of age on neural activity during episodic encoding using a cross-sectional lifespan sample (20-79 years old, N=192) from the Dallas Lifespan Brain Study. We report four major findings. First, in a contrast of remembered vs. forgotten items, a decrease in neural activity occurred with age in bilateral occipito-temporo-parietal regions. Second, when we contrasted forgotten with remembered items (negative subsequent memory), the primary difference was found between middle and older ages. Third, there was evidence for age equivalence in hippocampal regions, congruent with previous studies. Finally, low-memory-performers showed negative subsequent memory differences by middle age, whereas high memory performers did not demonstrate these differences until older age. Taken together, these findings delineate the importance of a lifespan approach to understanding neurocognitive aging and, in particular, the importance of a middle-age sample in revealing different trajectories. Copyright © 2012 Elsevier Ltd. All rights reserved.

Carbonic anhydrase activation enhances object recognition memory in mice through phosphorylation of the extracellular signal-regulated kinase in the cortex and the hippocampus.

PubMed

Canto de Souza, Lucas; Provensi, Gustavo; Vullo, Daniela; Carta, Fabrizio; Scozzafava, Andrea; Costa, Alessia; Schmidt, Scheila Daiane; Passani, Maria Beatrice; Supuran, Claudiu T; Blandina, Patrizio

2017-05-15

Rats injected with by d-phenylalanine, a carbonic anhydrase (CA) activator, enhanced spatial learning, whereas rats given acetazolamide, a CA inhibitor, exhibited impairments of fear memory consolidation. However, the related mechanisms are unclear. We investigated if CAs are involved in a non-spatial recognition memory task assessed using the object recognition test (ORT). Systemic administration of acetazolamide to male CD1 mice caused amnesia in the ORT and reduced CA activity in brain homogenates, while treatment with d-phenylalanine enhanced memory and increased CA activity. We provided also the first evidence that d-phenylalanine administration rapidly activated extracellular signal-regulated kinase (ERK) pathways, a critical step for memory formation, in the cortex and the hippocampus, two brain areas involved in memory processing. Effects elicited by d-phenylalanine were completely blunted by co-administration of acetazolamide, but not of 1-N-(4-sulfamoylphenyl-ethyl)-2,4,6-trimethylpyridinium perchlorate (C18), a CA inhibitor that, differently from acetazolamide, does not cross the blood brain barrier. Our results strongly suggest that brain but not peripheral CAs activation potentiates memory as a result of ERK pathway enhanced activation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Memory and Spatial Cognition in Breast Cancer Patients Undergoing Adjuvant Endocrine Therapy

PubMed Central

Berndt, Ute; Leplow, Bernd; Schoenfeld, Robby; Lantzsch, Tilmann; Grosse, Regina; Thomssen, Christoph

2016-01-01

Introduction It is generally accepted that estrogens play a protective role in cognitive function. Therefore, it can be expected that subtotal estrogen deprivation following aromatase inhibition will alter cognitive performance. Methods In a cross-sectional study we investigated 80 postmenopausal women with breast cancer. Memory and spatial cognition were compared across 4 treatment groups: tamoxifen only (TAM, n = 22), aromatase inhibitor only (AI, n = 22), TAM followed by AI (‘SWITCH group’, n = 15), and patients with local therapy (LT) only (surgery and radiation, n = 21). Duration of the 2 endocrine monotherapy arms prior to the assessment ranged from 1 to 3 years. The ‘SWITCH group’ received 2-3 years TAM followed by at least 1 year and at most 3 years of AI. Memory and spatial cognition were investigated as planned comparisons. Investigations of processing speed, attention, executive function, visuoconstruction and self-perception of memory were exploratory. Results With regard to general memory, AI patients performed significantly worse than the LT group (p = 0.013). Significant differences in verbal memory did not remain significant after p-value correction for multiple testing. We found no significant differences concerning spatial cognition between the groups. Conclusion AI treatment alone significantly impairs general memory compared to the LT group. PMID:27721710

The effects of road traffic and aircraft noise exposure on children's episodic memory: the RANCH project.

PubMed

Matheson, Mark; Clark, Charlotte; Martin, Rocio; van Kempen, Elise; Haines, Mary; Barrio, Isabel Lopez; Hygge, Staffan; Stansfeld, Stephen

2010-01-01

Previous studies have found that chronic exposure to aircraft noise has a negative effect on children's performance on tests of episodic memory. The present study extended the design of earlier studies in three ways: firstly, by examining the effects of two noise sources, aircraft and road traffic, secondly, by examining exposure-effect relationships, and thirdly, by carrying out parallel field studies in three European countries, allowing cross-country comparisons to be made. A total of 2844 children aged between 8 years 10 months and 12 years 10 months (mean age 10 years 6 months) completed classroom-based tests of cued recall, recognition memory and prospective memory. Questionnaires were also completed by the children and their parents in order to provide information about socioeconomic context. Multilevel modeling analysis revealed aircraft noise to be associated with an impairment of recognition memory in a linear exposure-effect relationship. The analysis also found road traffic noise to be associated with improved performance on cued recall in a linear exposure-effect relationship. No significant association was found between exposure to aircraft noise and cued recall or prospective memory. Likewise, no significant association was found between road traffic noise and recognition or prospective memory. Taken together, these findings indicate that exposure to aircraft noise and road traffic noise can impact on certain aspects of children's episodic memory.

Relation between Working Memory Capacity and Auditory Stream Segregation in Children with Auditory Processing Disorder.

PubMed

Lotfi, Yones; Mehrkian, Saiedeh; Moossavi, Abdollah; Zadeh, Soghrat Faghih; Sadjedi, Hamed

2016-03-01

This study assessed the relationship between working memory capacity and auditory stream segregation by using the concurrent minimum audible angle in children with a diagnosed auditory processing disorder (APD). The participants in this cross-sectional, comparative study were 20 typically developing children and 15 children with a diagnosed APD (age, 9-11 years) according to the subtests of multiple-processing auditory assessment. Auditory stream segregation was investigated using the concurrent minimum audible angle. Working memory capacity was evaluated using the non-word repetition and forward and backward digit span tasks. Nonparametric statistics were utilized to compare the between-group differences. The Pearson correlation was employed to measure the degree of association between working memory capacity and the localization tests between the 2 groups. The group with APD had significantly lower scores than did the typically developing subjects in auditory stream segregation and working memory capacity. There were significant negative correlations between working memory capacity and the concurrent minimum audible angle in the most frontal reference location (0° azimuth) and lower negative correlations in the most lateral reference location (60° azimuth) in the children with APD. The study revealed a relationship between working memory capacity and auditory stream segregation in children with APD. The research suggests that lower working memory capacity in children with APD may be the possible cause of the inability to segregate and group incoming information.

Reversal Learning and Associative Memory Impairments in a BACHD Rat Model for Huntington Disease

PubMed Central

Abada, Yah-se K.; Nguyen, Huu Phuc; Ellenbroek, Bart; Schreiber, Rudy

2013-01-01

Chorea and psychiatric symptoms are hallmarks of Huntington disease (HD), a neurodegenerative disorder, genetically characterized by the presence of expanded CAG repeats (>35) in the HUNTINGTIN (HTT) gene. HD patients present psychiatric symptoms prior to the onset of motor symptoms and we recently found a similar emergence of non motor and motor deficits in BACHD rats carrying the human full length mutated HTT (97 CAG-CAA repeats). We evaluated cognitive performance in reversal learning and associative memory tests in different age cohorts of BACHD rats. Male wild type (WT) and transgenic (TG) rats between 2 and 12 months of age were tested. Learning and strategy shifting were assessed in a cross-maze test. Associative memory was evaluated in different fear conditioning paradigms (context, delay and trace). The possible confound of a fear conditioning phenotype by altered sensitivity to a ‘painful’ stimulus was assessed in a flinch-jump test. In the cross maze, 6 months old TG rats showed a mild impairment in reversal learning. In the fear conditioning tasks, 4, 6 and 12 months old TG rats showed a marked reduction in contextual fear conditioning. In addition, TG rats showed impaired delay conditioning (9 months) and trace fear conditioning (3 months). This phenotype was unlikely to be affected by a change in ‘pain’ sensitivity as WT and TG rats showed no difference in their threshold response in the flinch-jump test. Our results suggest that BACHD rats have a profound associative memory deficit and, possibly, a deficit in reversal learning as assessed in a cross maze task. The time course for the emergence of these symptoms (i.e., before the occurrence of motor symptoms) in this rat model for HD appears similar to the time course in patients. These data suggest that BACHD rats may be a useful model for preclinical drug discovery. PMID:24223692

Hippocampal atrophy in people with memory deficits: results from the population-based IPREA study.

PubMed

Ferrarini, Luca; van Lew, Baldur; Reiber, Johan H C; Gandin, Claudia; Galluzzo, Lucia; Scafato, Emanuele; Frisoni, Giovanni B; Milles, Julien; Pievani, Michela

2014-07-01

Clinical studies have shown that hippocampal atrophy is present before dementia in people with memory deficits and can predict dementia development. The question remains whether this association holds in the general population. This is of interest for the possible use of hippocampal atrophy to screen population for preventive interventions. The aim of this study was to assess hippocampal volume and shape abnormalities in elderly adults with memory deficits in a cross-sectional population-based study. We included individuals participating in the Italian Project on the Epidemiology of Alzheimer Disease (IPREA) study: 75 cognitively normal individuals (HC), 31 individuals with memory deficits (MEM), and 31 individuals with memory deficits not otherwise specified (MEMnos). Hippocampal volumes and shape were extracted through manual tracing and the growing and adaptive meshes (GAMEs) shape-modeling algorithm. We investigated between-group differences in hippocampal volume and shape, and correlations with memory deficits. In MEM participants, hippocampal volumes were significantly smaller than in HC and were mildly associated with worse memory scores. Memory-associated shape changes mapped to the anterior hippocampus. Shape-based analysis detected no significant difference between MEM and HC, while MEMnos showed shape changes in the posterior hippocampus compared with HC and MEM groups. These findings support the discriminant validity of hippocampal volumetry as a biomarker of memory impairment in the general population. The detection of shape changes in MEMnos but not in MEM participants suggests that shape-based biomarkers might lack sensitivity to detect Alzheimer's-like pathology in the general population.

A process-based approach to characterizing the effect of acute alprazolam challenge on visual paired associate learning and memory in healthy older adults.

PubMed

Pietrzak, Robert H; Scott, James Cobb; Harel, Brian T; Lim, Yen Ying; Snyder, Peter J; Maruff, Paul

2012-11-01

Alprazolam is a benzodiazepine that, when administered acutely, results in impairments in several aspects of cognition, including attention, learning, and memory. However, the profile (i.e., component processes) that underlie alprazolam-related decrements in visual paired associate learning has not been fully explored. In this double-blind, placebo-controlled, randomized cross-over study of healthy older adults, we used a novel, "process-based" computerized measure of visual paired associate learning to examine the effect of a single, acute 1-mg dose of alprazolam on component processes of visual paired associate learning and memory. Acute alprazolam challenge was associated with a large magnitude reduction in visual paired associate learning and memory performance (d = 1.05). Process-based analyses revealed significant increases in distractor, exploratory, between-search, and within-search error types. Analyses of percentages of each error type suggested that, relative to placebo, alprazolam challenge resulted in a decrease in the percentage of exploratory errors and an increase in the percentage of distractor errors, both of which reflect memory processes. Results of this study suggest that acute alprazolam challenge decreases visual paired associate learning and memory performance by reducing the strength of the association between pattern and location, which may reflect a general breakdown in memory consolidation, with less evidence of reductions in executive processes (e.g., working memory) that facilitate visual paired associate learning and memory. Copyright © 2012 John Wiley & Sons, Ltd.

A Latent Variables Examination of Processing Speed, Response Inhibition, and Working Memory during Typical Development

PubMed Central

McAuley, Tara; White, Desirée

2010-01-01

The present study addressed three related aims: (1) to replicate and extend previous work regarding the non-unitary nature of processing speed, response inhibition, and working memory during development, (2) to quantify the rate at which processing speed, response inhibition, and working memory develop and the extent to which the development of these latter abilities reflect general changes in processing speed, and (3) to evaluate whether commonly used tasks of processing speed, response inhibition, and working memory are valid and reliable when used with a developmentally diverse group. To address these aims, a latent variables approach was used to analyze data from 147 participants 6 to 24 years of age. Results showed that processing speed, response inhibition, and working memory were separable abilities and that the extent of this separability was stable cross the age range of participants. All three constructs improved as a function of age; however, only the effect of age on working memory remained significant after processing speed was controlled. The psychometric properties of tasks used to assess the constructs were age invariant, thus validating their use in studies of executive development. PMID:20888572

Subjective memory complaints among patients on sick leave are associated with symptoms of fatigue and anxiety

PubMed Central

Aasvik, Julie K.; Woodhouse, Astrid; Jacobsen, Henrik B.; Borchgrevink, Petter C.; Stiles, Tore C.; Landrø, Nils I.

2015-01-01

Objective: The aim of this study was to identify symptoms associated with subjective memory complaints (SMCs) among subjects who are currently on sick leave due to symptoms of chronic pain, fatigue, depression, anxiety, and insomnia. Methods: This was a cross-sectional study, subjects (n = 167) who were currently on sick leave were asked to complete an extensive survey consisting of the following: items addressing their sociodemographics, one item from the SF-8 health survey measuring pain, Chalder Fatigue Questionnaire, Hospital Anxiety and Depression Scale, Insomnia Severity Index, and Everyday Memory Questionnaire – Revised. General linear modeling was used to analyze variables associated with SMCs. Results: Symptoms of fatigue (p-value < 0.001) and anxiety (p-value = 0.001) were uniquely and significantly associated with perceived memory failures. The associations with symptoms of pain, depression, and insomnia were not statistically significant. Conclusions: Subjective memory complaints should be recognized as part of the complex symptomatology among patients who report multiple symptoms, especially in cases of fatigue and anxiety. Self-report questionnaires measuring perceived memory failures may be a quick and easy way to incorporate and extend this knowledge into clinical practice. PMID:26441716

Subjective memory complaints among patients on sick leave are associated with symptoms of fatigue and anxiety.

PubMed

Aasvik, Julie K; Woodhouse, Astrid; Jacobsen, Henrik B; Borchgrevink, Petter C; Stiles, Tore C; Landrø, Nils I

2015-01-01

The aim of this study was to identify symptoms associated with subjective memory complaints (SMCs) among subjects who are currently on sick leave due to symptoms of chronic pain, fatigue, depression, anxiety, and insomnia. This was a cross-sectional study, subjects (n = 167) who were currently on sick leave were asked to complete an extensive survey consisting of the following: items addressing their sociodemographics, one item from the SF-8 health survey measuring pain, Chalder Fatigue Questionnaire, Hospital Anxiety and Depression Scale, Insomnia Severity Index, and Everyday Memory Questionnaire - Revised. General linear modeling was used to analyze variables associated with SMCs. Symptoms of fatigue (p-value < 0.001) and anxiety (p-value = 0.001) were uniquely and significantly associated with perceived memory failures. The associations with symptoms of pain, depression, and insomnia were not statistically significant. Subjective memory complaints should be recognized as part of the complex symptomatology among patients who report multiple symptoms, especially in cases of fatigue and anxiety. Self-report questionnaires measuring perceived memory failures may be a quick and easy way to incorporate and extend this knowledge into clinical practice.

Parity of access to memory services in London for the BAME population: a cross-sectional study.

PubMed

Cook, Laura; Mukherjee, Sujoy; McLachlan, Tim; Shah, Rajendra; Livingston, Gill; Mukadam, Naaheed

2018-03-12

To investigate whether referrals to memory services in London reflect the ethnic diversity of the population. Memory service data including referral rates of BAME was collected from London Clinical Commissioning Groups (CCGs). The expected percentage of BAME referrals using census data was compared against White British population percentages using the chi squared test. We found that within 13,166 referrals to memory services across London, the percentage of people from BAME groups was higher than would be expected (20.3 versus 19.4%; χ 2 = 39.203, d.f. = 1, p < 0.0001) indicating that generally people from BAME groups are accessing memory services. Seventy-nine percent of memory services had more referrals than expected or no significant difference for all BAME groups. When there were fewer referrals then expected, the largest difference in percentage for an individual ethnic group was 3.3%. Results are encouraging and may indicate a significant improvement in awareness of dementia and help seeking behaviour among BAME populations. Prevalence of dementia in some ethnic groups may be higher so these numbers could still indicate under-referral. Due to the data available we were unable to compare disease severity or diagnosis type.

Aging, culture, and memory for categorically processed information.

PubMed

Yang, Lixia; Chen, Wenfeng; Ng, Andy H; Fu, Xiaolan

2013-11-01

Literature on cross-cultural differences in cognition suggests that categorization, as an information processing and organization strategy, was more often used by Westerners than by East Asians, particularly for older adults. This study examines East-West cultural differences in memory for categorically processed items and sources in young and older Canadians and native Chinese with a conceptual source memory task (Experiment 1) and a reality monitoring task (Experiment 2). In Experiment 1, participants encoded photographic faces of their own ethnicity that were artificially categorized into GOOD or EVIL characters and then completed a source memory task in which they identified faces as old-GOOD, old-EVIL, or new. In Experiment 2, participants viewed a series of words, each followed either by a corresponding image (i.e., SEEN) or by a blank square within which they imagined an image for the word (i.e., IMAGINED). At test, they decided whether the test words were old-SEEN, old-IMAGINED, or new. In general, Canadians outperformed Chinese in memory for categorically processed information, an effect more pronounced for older than for young adults. Extensive exercise of culturally preferred categorization strategy differentially benefits Canadians and reduces their age group differences in memory for categorically processed information.

Attention, memory, visuoconstructive, and executive task performance in adolescents with anxiety disorders: a case-control community study.

PubMed

Jarros, Rafaela Behs; Salum, Giovanni Abrahão; Silva, Cristiano Tschiedel Belem da; Toazza, Rudineia; Becker, Natália; Agranonik, Marilyn; Salles, Jerusa Fumagalli de; Manfro, Gisele Gus

2017-01-01

The aim of the present study was to assess children and adolescents with mild and severe anxiety disorders for their performance in attention, verbal episodic memory, working memory, visuoconstructive skills, executive functions, and cognitive global functioning and conduct comparative analyses with the performance of children free from anxiety disorders. Our sample comprised 68 children and adolescents aged 10 to 17 years (41 with current diagnoses of anxiety disorders and 27 controls) selected from a larger cross-sectional community sample of adolescents. Children and adolescents with anxiety disorders were categorized into two groups on the basis of anxiety severity (mild or severe). All participants underwent a neuropsychological assessment battery to evaluate attention, verbal episodic memory, working memory, visuoconstructive skills, and executive and cognitive functions. No differences were found in any neuropsychological tests, with the single exception that the group with mild anxiety had better performance on the Digit Span backward test compared to subjects with severe anxiety and to controls (p = 0.041; η2 = 0.11). Not only might anxiety disorders spare main cognitive functions during adolescence, they may even enhance certain working memory processes.

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

NASA Astrophysics Data System (ADS)

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

1995-12-01

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

Similarity in form and function of the hippocampus in rodents, monkeys, and humans.

PubMed

Clark, Robert E; Squire, Larry R

2013-06-18

We begin by describing an historical scientific debate in which the fundamental idea that species are related by evolutionary descent was challenged. The challenge was based on supposed neuroanatomical differences between humans and other primates with respect to a structure known then as the hippocampus minor. The debate took place in the early 1860 s, just after the publication of Darwin's famous book. We then recount the difficult road that was traveled to develop an animal model of human memory impairment, a matter that also turned on questions about similarities and differences between humans and other primates. We then describe how the insight that there are multiple memory systems helped to secure the animal model and how the animal model was ultimately used to identify the neuroanatomy of long-term declarative memory (sometimes termed explicit memory). Finally, we describe a challenge to the animal model and to cross-species comparisons by considering the case of the concurrent discrimination task, drawing on findings from humans and monkeys. We suggest that analysis of such cases, based on the understanding that there are multiple memory systems with different properties, has served to emphasize the similarities in memory function across mammalian species.

A Positive Correlation between Atypical Memory B Cells and Plasmodium falciparum Transmission Intensity in Cross-Sectional Studies in Peru and Mali

PubMed Central

Weiss, Greta E.; Clark, Eva H.; Li, Shanping; Traore, Boubacar; Kayentao, Kassoum; Ongoiba, Aissata; Hernandez, Jean N.; Doumbo, Ogobara K.; Pierce, Susan K.; Branch, OraLee H.; Crompton, Peter D.

2011-01-01

Background Antibodies that protect against Plasmodium falciparum (Pf) malaria are only acquired after years of repeated infections. The B cell biology that underlies this observation is poorly understood. We previously reported that “atypical” memory B cells are increased in children and adults exposed to intense Pf transmission in Mali, similar to what has been observed in individuals infected with HIV. In this study we examined B cell subsets of Pf -infected adults in Peru and Mali to determine if Pf transmission intensity correlates with atypical memory B cell expansion. Methodology/Principal Findings In this cross-sectional study venous blood was collected from adults in areas of zero (U.S., n = 10), low (Peru, n = 18) and high (Mali, n = 12) Pf transmission. Adults in Peru and Mali were infected with Pf at the time of blood collection. Thawed lymphocytes were analyzed by flow cytometry to quantify B cell subsets, including atypical memory B cells, defined by the cell surface markers CD19+ CD20+ CD21− CD27− CD10−. In Peru, the mean level of atypical memory B cells, as a percent of total B cells, was higher than U.S. adults (Peru mean: 5.4% [95% CI: 3.61–7.28]; U.S. mean: 1.4% [95% CI: 0.92–1.81]; p<0.0001) but lower than Malian adults (Mali mean 13.1% [95% CI: 10.68–15.57]; p = 0.0001). In Peru, individuals self-reporting ≥1 prior malaria episodes had a higher percentage of atypical memory B cells compared to those reporting no prior episodes (≥1 prior episodes mean: 6.6% [95% CI: 4.09–9.11]; no prior episodes mean: 3.1% [95% CI: 1.52–4.73]; p = 0.028). Conclusions/Significance Compared to Pf-naive controls, atypical memory B cells were increased in Peruvian adults exposed to low Pf transmission, and further increased in Malian adults exposed to intense Pf transmission. Understanding the origin, function and antigen specificity of atypical memory B cells in the context of Pf infection could contribute to our understanding of naturally-acquired malaria immunity. PMID:21264245

Optoelectronic associative memory

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin (Inventor)

1993-01-01

An associative optical memory including an input spatial light modulator (SLM) in the form of an edge enhanced liquid crystal light valve (LCLV) and a pair of memory SLM's in the form of liquid crystal televisions (LCTV's) forms a matrix array of an input image which is cross correlated with a matrix array of stored images. The correlation product is detected and nonlinearly amplified to illuminate a replica of the stored image array to select the stored image correlating with the input image. The LCLV is edge enhanced by reducing the bias frequency and voltage and rotating its orientation. The edge enhancement and nonlinearity of the photodetection improves the orthogonality of the stored image. The illumination of the replicate stored image provides a clean stored image, uncontaminated by the image comparison process.

Neurocognitive Aging and the Hippocampus Across Species

PubMed Central

Leal, Stephanie L; Yassa, Michael A.

2016-01-01

There is extensive evidence that aging is associated with impairments in episodic memory. Many of these changes have been ascribed to neurobiological alterations to the hippocampal network and its input pathways. A cross-species consensus is beginning to emerge suggesting that subtle synaptic and functional changes within this network may underlie the majority of age-related memory impairments. In this review, we survey convergent data from animal and human studies that have contributed significantly to our understanding of the brain-behavior relationships in this network, particularly in the aging brain. We utilize a cognitive as well as a neurobiological perspective, and synthesize data across approaches and species to reach a more detailed understanding of age-related alterations in hippocampal memory function. PMID:26607684

Soft errors in commercial off-the-shelf static random access memories

NASA Astrophysics Data System (ADS)

Dilillo, L.; Tsiligiannis, G.; Gupta, V.; Bosser, A.; Saigne, F.; Wrobel, F.

2017-01-01

This article reviews state-of-the-art techniques for the evaluation of the effect of radiation on static random access memory (SRAM). We detailed irradiation test techniques and results from irradiation experiments with several types of particles. Two commercial SRAMs, in 90 and 65 nm technology nodes, were considered as case studies. Besides the basic static and dynamic test modes, advanced stimuli for the irradiation tests were introduced, as well as statistical post-processing techniques allowing for deeper analysis of the correlations between bit-flip cross-sections and design/architectural characteristics of the memory device. Further insight is provided on the response of irradiated stacked layer devices and on the use of characterized SRAM devices as particle detectors.

Modulation of memory and visuospatial processes by biperiden and rivastigmine in elderly healthy subjects.

PubMed

Wezenberg, E; Verkes, R J; Sabbe, B G C; Ruigt, G S F; Hulstijn, W

2005-09-01

The central cholinergic system is implicated in cognitive functioning. The dysfunction of this system is expressed in many diseases like Alzheimer's disease, dementia of Lewy body, Parkinson's disease and vascular dementia. In recent animal studies, it was found that selective cholinergic modulation affects visuospatial processes even more than memory function. In the current study, we tried to replicate those findings. In order to investigate the acute effects of cholinergic drugs on memory and visuospatial functions, a selective anticholinergic drug, biperiden, was compared to a selective acetylcholinesterase-inhibiting drug, rivastigmine, in healthy elderly subjects. A double-blind, placebo-controlled, randomised, cross-over study was performed in 16 healthy, elderly volunteers (eight men, eight women; mean age 66.1, SD 4.46 years). All subjects received biperiden (2 mg), rivastigmine (3 mg) and placebo with an interval of 7 days between them. Testing took place 1 h after drug intake (which was around Tmax for both drugs). Subjects were presented with tests for episodic memory (wordlist and picture memory), working memory tasks (N-back, symbol recall) and motor learning (maze task, pursuit rotor). Visuospatial abilities were assessed by tests with high visual scanning components (tangled lines and Symbol Digit Substitution Test). Episodic memory was impaired by biperiden. Rivastigmine impaired recognition parts of the episodic memory performance. Working memory was non-significantly impaired by biperiden and not affected by rivastigmine. Motor learning as well as visuospatial processes were impaired by biperiden and improved by rivastigmine. These results implicate acetylcholine as a modulator not only of memory but also of visuospatial abilities.

Pre-stimulus thalamic theta power predicts human memory formation.

PubMed

Sweeney-Reed, Catherine M; Zaehle, Tino; Voges, Jürgen; Schmitt, Friedhelm C; Buentjen, Lars; Kopitzki, Klaus; Richardson-Klavehn, Alan; Hinrichs, Hermann; Heinze, Hans-Jochen; Knight, Robert T; Rugg, Michael D

2016-09-01

Pre-stimulus theta (4-8Hz) power in the hippocampus and neocortex predicts whether a memory for a subsequent event will be formed. Anatomical studies reveal thalamus-hippocampal connectivity, and lesion, neuroimaging, and electrophysiological studies show that memory processing involves the dorsomedial (DMTN) and anterior thalamic nuclei (ATN). The small size and deep location of these nuclei have limited real-time study of their activity, however, and it is unknown whether pre-stimulus theta power predictive of successful memory formation is also found in these subcortical structures. We recorded human electrophysiological data from the DMTN and ATN of 7 patients receiving deep brain stimulation for refractory epilepsy. We found that greater pre-stimulus theta power in the right DMTN was associated with successful memory encoding, predicting both behavioral outcome and post-stimulus correlates of successful memory formation. In particular, significant correlations were observed between right DMTN theta power and both frontal theta and right ATN gamma (32-50Hz) phase alignment, and frontal-ATN theta-gamma cross-frequency coupling. We draw the following primary conclusions. Our results provide direct electrophysiological evidence in humans of a role for the DMTN as well as the ATN in memory formation. Furthermore, prediction of subsequent memory performance by pre-stimulus thalamic oscillations provides evidence that post-stimulus differences in thalamic activity that index successful and unsuccessful encoding reflect brain processes specifically underpinning memory formation. Finally, the findings broaden the understanding of brain states that facilitate memory encoding to include subcortical as well as cortical structures. Copyright © 2016 Elsevier Inc. All rights reserved.

The association between subjective memory complaint and objective cognitive function in older people with previous major depression.

PubMed

Chu, Chung-Shiang; Sun, I-Wen; Begum, Aysha; Liu, Shen-Ing; Chang, Ching-Jui; Chiu, Wei-Che; Chen, Chin-Hsin; Tang, Hwang-Shen; Yang, Chia-Li; Lin, Ying-Chin; Chiu, Chih-Chiang; Stewart, Robert

2017-01-01

The goal of this study is to investigate associations between subjective memory complaint and objective cognitive performance in older people with previous major depression-a high-risk sample for cognitive impairment and later dementia. A cross-sectional study was carried out in people aged 60 or over with previous major depression but not fulfilling current major depression criteria according to DSM-IV-TR. People with dementia or Mini-Mental State Examination score less than 17 were excluded. Subjective memory complaint was defined on the basis of a score ≧4 on the subscale of Geriatric Mental State schedule, a maximum score of 8. Older people aged equal or over 60 without any psychiatric diagnosis were enrolled as healthy controls. Cognitive function was evaluated using a series of cognitive tests assessing verbal memory, attention/speed, visuospatial function, verbal fluency, and cognitive flexibility in all participants. One hundred and thirteen older people with previous major depression and forty-six healthy controls were enrolled. Subjective memory complaint was present in more than half of the participants with depression history (55.8%). Among those with major depression history, subjective memory complaint was associated with lower total immediate recall and delayed verbal recall scores after adjustment. The associations between subjective memory complaint and worse memory performance were stronger in participants with lower depressive symptoms (Hamilton Depression Rating Scale score<7). The results suggest subjective memory complaint may be a valid appraisal of memory performance in older people with previous major depression and consideration should be given to more proactive assessment and follow-up in these clinical samples.

Binding biological motion and visual features in working memory.

PubMed

Ding, Xiaowei; Zhao, Yangfan; Wu, Fan; Lu, Xiqian; Gao, Zaifeng; Shen, Mowei

2015-06-01

Working memory mechanisms for binding have been examined extensively in the last decade, yet few studies have explored bindings relating to human biological motion (BM). Human BM is the most salient and biologically significant kinetic information encountered in everyday life and is stored independently from other visual features (e.g., colors). The current study explored 3 critical issues of BM-related binding in working memory: (a) how many BM binding units can be retained in working memory, (b) whether involuntarily object-based binding occurs during BM binding, and (c) whether the maintenance of BM bindings in working memory requires attention above and beyond that needed to maintain the constituent dimensions. We isolated motion signals of human BM from non-BM sources by using point-light displays as to-be-memorized BM and presented the participants colored BM in a change detection task. We found that working memory capacity for BM-color bindings is rather low; only 1 or 2 BM-color bindings could be retained in working memory regardless of the presentation manners (Experiments 1-3). Furthermore, no object-based encoding took place for colored BM stimuli regardless of the processed dimensions (Experiments 4 and 5). Central executive attention contributes to the maintenance of BM-color bindings, yet maintaining BM bindings in working memory did not require more central attention than did maintaining the constituent dimensions in working memory (Experiment 6). Overall, these results suggest that keeping BM bindings in working memory is a fairly resource-demanding process, yet central executive attention does not play a special role in this cross-module binding. (c) 2015 APA, all rights reserved).

Editorial: subjective perceptions of memory functioning in old age - nature, correlates, and developmental trajectories.

PubMed

Hülür, Gizem; Gerstorf, Denis

2015-01-01

Subjective memory complaints are often used as diagnostic criteria for several neurocognitive disorders. Although a number of studies have examined subjective memory and its associations with memory functioning in adulthood and old age, it is still an open question whether subjective perceptions of one's memory indicate actual memory functioning or whether they are rather derived from factors other than memory, such as depressive symptoms. The studies in this special section examine subjective perceptions of memory functioning and their associations with objectively measured memory performance in general and in clinical populations. The four articles adopt cross-sectional and longitudinal methodologies and offer key insights into the nature, correlates, and developmental trajectories of subjective memory. To begin with, the studies compiled in this special section demonstrate that changes in subjective memory perceptions are indeed associated with changes in memory performance [Zimprich and Kurtz, this issue, pp. 223-231], but the size of associations between levels of and changes in subjective memory and memory performance is in part modulated by personality characteristics and depressive symptoms [Hülür et al., this issue, pp. 232-240]. Second, the studies compiled here show that factors other than memory are also closely associated with memory perceptions, including functional health as well as domain-general and health-specific control beliefs [Luszcz et al., this issue, pp. 241-250]. Third, the study by Thompson et al. [this issue, pp. 251-257] shows that self- and informant-reports of retrospective and prospective memory difficulties are not associated with performance-based measures and does not sufficiently differentiate between healthy controls and patients diagnosed with mild cognitive impairment or dementia. In our editorial, we put these findings in perspective and discuss implications for research and practice. To extend our knowledge, we conclude by outlining two key avenues for future research: (i) longitudinal multivariate studies of the construct space surrounding subjective memory and (ii) the viability of experience sampling studies with daily or hourly measurements to tackle some of the mechanisms underlying these associations. © 2015 S. Karger AG, Basel

Q-Bridge environmental impact statement : executive summary

DOT National Transportation Integrated Search

1997-04-01

This Executive Summary provides a brief overview of the Final Environmental Impact Statement/Section 4(f) Evaluation (FEIS) for Interstate 95 (I-95) - Pearl Harbor Memorial Bridge (Q-Bridge) Crossing New Haven Harbor Study. The information presented ...

Distinguished Flying Cross National Memorial Act

THOMAS, 112th Congress

Rep. Calvert, Ken [R-CA-44

2011-01-19

Senate - 10/31/2011 Received in the Senate and Read twice and referred to the Committee on Energy and Natural Resources. (All Actions) Tracker: This bill has the status Passed HouseHere are the steps for Status of Legislation:

Distinguished Flying Cross National Memorial Act

THOMAS, 111th Congress

Rep. Calvert, Ken [R-CA-44

2009-06-10

Senate - 03/22/2010 Received in the Senate and Read twice and referred to the Committee on Energy and Natural Resources. (All Actions) Tracker: This bill has the status Passed HouseHere are the steps for Status of Legislation:

Bio-inspired layered chitosan/graphene oxide nanocomposite hydrogels with high strength and pH-driven shape memory effect.

PubMed

Zhang, Yaqian; Zhang, Min; Jiang, Haoyang; Shi, Jinli; Li, Feibo; Xia, Yanhong; Zhang, Gongzheng; Li, Huanjun

2017-12-01

The layered nanocomposite hydrogel films containing chitosan (CS) and graphene oxide (GO) have been prepared by water evaporation induced self-assembly and subsequent physical cross-linking in alkaline solution. The layered CS/GO hydrogel films obtained have a nacre-like brick-and-mortar microstructure, which contributes to their excellent mechanical properties. The tensile strength and elongation at break of the hydrogel films with 5wt% GO are 5.35MPa and 193.5%, respectively, which are comparable to natural costal cartilage. Furthermore, the CS/GO hydrogel films exhibited pH-driven shape memory effect, and this unique phenomenon is mainly attributed to the reversible transition of partial physically cross-linking corresponding to hydrogen bondings and hydrophobic interactions between CS polymer chains due to pH changing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cross-cultural feigning assessment: A systematic review of feigning instruments used with linguistically, ethnically, and culturally diverse samples.

PubMed

Nijdam-Jones, Alicia; Rosenfeld, Barry

2017-11-01

The cross-cultural validity of feigning instruments and cut-scores is a critical concern for forensic mental health clinicians. This systematic review evaluated feigning classification accuracy and effect sizes across instruments and languages by summarizing 45 published peer-reviewed articles and unpublished doctoral dissertations conducted in Europe, Asia, and North America using linguistically, ethnically, and culturally diverse samples. The most common psychiatric symptom measures used with linguistically, ethnically, and culturally diverse samples included the Structured Inventory of Malingered Symptomatology, the Miller Forensic Assessment of Symptoms Test, and the Minnesota Multiphasic Personality Inventory (MMPI). The most frequently studied cognitive effort measures included the Word Recognition Test, the Test of Memory Malingering, and the Rey 15-item Memory test. The classification accuracy of these measures is compared and the implications of this research literature are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Theory of mind and executive function in Chinese preschool children.

PubMed

Duh, Shinchieh; Paik, Jae H; Miller, Patricia H; Gluck, Stephanie C; Li, Hui; Himelfarb, Igor

2016-04-01

Cross-cultural research on children's theory of mind (ToM) understanding has raised questions about its developmental sequence and relationship with executive function (EF). The current study examined how ToM develops (using the tasks from Wellman & Liu, 2004) in relation to 2 EF skills (conflict inhibition, working memory) in 997 Chinese preschoolers (ages 3, 4, 5) in Chengdu, China. Compared with prior research with other Chinese and non-Chinese children, some general patterns in development were replicated in this sample. However, the children showed culture-specific reversals in the developmental sequence of ToM. For example, Chengdu children performed differently on the 2 false-belief tasks that were thought to be equivalent. Furthermore, conflict inhibition as well as working memory uniquely predicted ToM performance. We discuss the issues of ToM development as they relate to test items and cross-cultural--and subcultural--differences. (c) 2016 APA, all rights reserved).

The polarity-dependent effects of the bilateral brain stimulation on working memory.

PubMed

Keshvari, Fatemeh; Pouretemad, Hamid-Reza; Ekhtiari, Hamed

2013-01-01

Working memory plays a critical role in cognitive processes which are central to our daily life. Neuroimaging studies have shown that one of the most important areas corresponding to the working memory is the dorsolateral prefrontal cortex (DLFPC). This study was aimed to assess whether bilateral modulation of the DLPFC using a noninvasive brain stimulation, namely transcranial direct current stimulation (tDCS), modifies the working memory function in healthy adults. In a randomized sham-controlled cross-over study, 60 subjects (30 Males) received sham and active tDCS in two subgroups (anode left/cathode right and anode right/cathode left) of the DLPFC. Subjects were presented working memory n-back task while the reaction time and accuracy were recorded. A repeated measures, mixed design ANOVA indicated a significant difference between the type of stimulation (sham vs. active) in anodal stimulation of the left DLPFC with cathodal stimulation of the right DLPFC [F(1,55)= 5.29, P=0.019], but not the inverse polarity worsened accuracy in the 2-back working memory task. There were also no statistically significant changes in speed of working memory [F(1,55)= 0.458,P=0.502] related to type or order of stimulation. The results would imply to a polarity dependence of bilateral tDCS of working memory. Left anodal/ right cathodal stimulation of DLPFC could impair working memory, while the reverser stimulation had no effect. Meaning that bilateral stimulation of DLFC would not be a useful procedure to improve working memory. Further studies are required to understand subtle effects of different tDCS stimulation/inhibition electrode positioning on the working memory.

Is subjective memory specific for memory performance or general across cognitive domains? Findings from the Seattle Longitudinal Study.

PubMed

Hülür, Gizem; Willis, Sherry L; Hertzog, Christopher; Schaie, K Warner; Gerstorf, Denis

2018-05-01

A growing body of research has examined whether people's judgments of their own memory functioning accurately reflect their memory performance at cross-section and over time. Relatively less is known about whether these judgments are specifically based on memory performance, or reflect general cognitive change. The aim of the present study was to examine longitudinal associations of subjective memory with performance in tests of episodic memory and a wide range of other cognitive tests, including the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Block Design, Comprehension, Digit Span, Digit Symbol, and Vocabulary subtests. We applied latent growth curve models to five occasions over up to 16 years of neuropsychological assessments from 956 participants of the Seattle Longitudinal Study (SLS; 57% women; age at baseline: M = 65.1, SD = 11.4, 38 - 96 years). Results revealed that lower self-reported Frequency of Forgetting was significantly associated with better performance in all cognitive domains at baseline. The baseline correlation of Frequency of Forgetting with memory performance was stronger than its correlations with performance in other cognitive tests. Furthermore, additional analyses with baseline data showed that a latent memory performance factor reliably predicted Frequency of Forgetting after controlling for a general cognitive factor. Over time, steeper increases in Frequency of Forgetting were associated with steeper declines in tests of memory performance and in the Block Design and Digit Symbol subtests. Taken together, these findings suggest that although self-reported Frequency of Forgetting reflects performance in a broad range of other cognitive domains, it also shows some specificity for memory performance. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Enhanced Requirement for TNFR2 in Graft Rejection Mediated by Low Affinity Memory CD8+ T Cells During Heterologous Immunity

PubMed Central

Krummey, Scott M.; Chen, Ching-Wen; Guasch, Sara A.; Liu, Danya; Wagener, Maylene; Larsen, Christian P; Ford, Mandy L.

2016-01-01

The affinity of a T cell receptor (TCR) binding to peptide:MHC profoundly impacts the phenotype and function of effector and memory cell differentiation. Little is known about the effect of low affinity priming on memory cell generation and function, which is particularly important in heterologous immunity, when microbe-specific T cells cross-react with allogeneic antigen and mediate graft rejection. We found that low affinity primed memory CD8+ T cells produced high levels of TNF ex vivo in response to heterologous rechallenge compared to high affinity primed memory T cells. Low affinity secondary effectors significantly upregulated TNFR2 on the cell surface and contained a higher frequency of TNFR2hi proliferating cells. Low affinity primed secondary effectors concurrently downregulated TNF production. Importantly, blockade of TNFR2 attenuated graft rejection in low but not high affinity primed animals. These data establish a functional connection between TNF signaling and TCR priming affinity and have implications for the immunomodulation of pathogenic T cell responses during transplantation. PMID:27481849

Non-replicating adenovirus vectors expressing avian influenza virus hemagglutinin and nucleocapsid proteins induce chicken specific effector, memory and effector memory CD8+ T lymphocytes

PubMed Central

Singh, Shailbala; Toro, Haroldo; Tang, De-Chu; Briles, Worthie E.; Yates, Linda M.; Kopulos, Renee T.; Collisson, Ellen W.

2010-01-01

Avian influenza virus (AIV) specific CD8+ T lymphocyte responses stimulated by intramuscular administration of an adenovirus (Ad) vector expressing either HA or NP were evaluated in chickens following ex vivo stimulation by non-professional antigen presenting cells. The CD8+ T lymphocyte responses were AIV specific, MHC-I restricted, and cross-reacted with heterologousH7N2 AIV strain. Specific effector responses, at 10 days post-inoculation (p.i.), were undetectable at 2 weeks p.i., and memory responses were detected from 3 to 8 weeks p.i. Effector memory responses, detected 1 week following a booster inoculation, were significantly greater than the primary responses and, within 7 days, declined to undetectable levels. Inoculation of an Ad-vector expressing human NP resulted in significantly greater MHC restricted, activation of CD8+ T cell responses specific for AIV. Decreases in all responses with time were most dramatic with maximum activation of T cells as observed following effector and effector memory responses. PMID:20557918

Single-Event Effect Performance of a Conductive-Bridge Memory EEPROM

NASA Technical Reports Server (NTRS)

Chen, Dakai; Wilcox, Edward; Berg, Melanie; Kim, Hak; Phan, Anthony; Figueiredo, Marco; Seidleck, Christina; LaBel, Kenneth

2015-01-01

We investigated the heavy ion single-event effect (SEE) susceptibility of the industry’s first stand-alone memory based on conductive-bridge memory (CBRAM) technology. The device is available as an electrically erasable programmable read-only memory (EEPROM). We found that single-event functional interrupt (SEFI) is the dominant SEE type for each operational mode (standby, dynamic read, and dynamic write/read). SEFIs occurred even while the device is statically biased in standby mode. Worst case SEFIs resulted in errors that filled the entire memory space. Power cycle did not always clear the errors. Thus the corrupted cells had to be reprogrammed in some cases. The device is also vulnerable to bit upsets during dynamic write/read tests, although the frequency of the upsets are relatively low. The linear energy transfer threshold for cell upset is between 10 and 20 megaelectron volts per square centimeter per milligram, with an upper limit cross section of 1.6 times 10(sup -11) square centimeters per bit (95 percent confidence level) at 10 megaelectronvolts per square centimeter per milligram. In standby mode, the CBRAM array appears invulnerable to bit upsets.

Effect of methamphetamine exposure and cross-fostering on cognitive function in adult male rats.

PubMed

Hrubá, Lenka; Schutová, Barbora; Pometlová, Marie; Rokyta, Richard; Slamberová, Romana

2010-03-17

The aim of our study was to examine the effect of prenatal methamphetamine (MA) exposure and cross-fostering on cognitive functions of adult male rats tested in Morris water maze (MWM). Rat mothers were exposed daily to injection of MA (5mg/kg) or saline for 9 weeks: prior to impregnation, throughout gestation and lactation periods. Females without any injections were used as an absolute control. On postnatal day 1, pups were cross-fostered so that each mother raised 4 pups of her own and 8 pups from the mothers with the other two treatments. Four types of tests were used: (1) Place navigation test (Learning), (2) Probe test (Probe), (3) Retention memory test (Memory) and (4) Visible platform task. Our results demonstrate that the prenatal exposure to MA does not impact learning and memory, while postnatal exposure to MA shows impairments in cognition. In the test of learning, all animals fostered to MA-treated dams had longer latencies, bigger search error and used lower spatial strategies than the animals fostered to control or saline-treated mother, regardless of prenatal exposure. Regardless of postnatal exposure, the animals prenatally exposed to saline swam faster in all the tests than the animals prenatally exposed to MA and controls, respectively. This study indicates that postnatal but not prenatal exposure to MA affects learning in adult male rats. However, it is still not clear whether these impairments are due to a direct effect of MA on neuronal structure or due to an indirect effect of MA mediated by impaired maternal care. Copyright 2009 Elsevier B.V. All rights reserved.

An adaptive technique for multiscale approximate entropy (MAEbin) threshold (r) selection: application to heart rate variability (HRV) and systolic blood pressure variability (SBPV) under postural stress.

PubMed

Singh, Amritpal; Saini, Barjinder Singh; Singh, Dilbag

2016-06-01

Multiscale approximate entropy (MAE) is used to quantify the complexity of a time series as a function of time scale τ. Approximate entropy (ApEn) tolerance threshold selection 'r' is based on either: (1) arbitrary selection in the recommended range (0.1-0.25) times standard deviation of time series (2) or finding maximum ApEn (ApEnmax) i.e., the point where self-matches start to prevail over other matches and choosing the corresponding 'r' (rmax) as threshold (3) or computing rchon by empirically finding the relation between rmax, SD1/SD2 ratio and N using curve fitting, where, SD1 and SD2 are short-term and long-term variability of a time series respectively. None of these methods is gold standard for selection of 'r'. In our previous study [1], an adaptive procedure for selection of 'r' is proposed for approximate entropy (ApEn). In this paper, this is extended to multiple time scales using MAEbin and multiscale cross-MAEbin (XMAEbin). We applied this to simulations i.e. 50 realizations (n = 50) of random number series, fractional Brownian motion (fBm) and MIX (P) [1] series of data length of N = 300 and short term recordings of HRV and SBPV performed under postural stress from supine to standing. MAEbin and XMAEbin analysis was performed on laboratory recorded data of 50 healthy young subjects experiencing postural stress from supine to upright. The study showed that (i) ApEnbin of HRV is more than SBPV in supine position but is lower than SBPV in upright position (ii) ApEnbin of HRV decreases from supine i.e. 1.7324 ± 0.112 (mean ± SD) to upright 1.4916 ± 0.108 due to vagal inhibition (iii) ApEnbin of SBPV increases from supine i.e. 1.5535 ± 0.098 to upright i.e. 1.6241 ± 0.101 due sympathetic activation (iv) individual and cross complexities of RRi and systolic blood pressure (SBP) series depend on time scale under consideration (v) XMAEbin calculated using ApEnmax is correlated with cross-MAE calculated using ApEn (0.1-0.26) in steps of 0.02 at each time scale in supine and upright position and is concluded that ApEn0.26 has highest correlation at most scales (vi) choice of 'r' is critical in interpreting interactions between RRi and SBP and in ascertaining true complexity of the individual RRi and SBP series.

Energy-efficient writing scheme for magnetic domain-wall motion memory

NASA Astrophysics Data System (ADS)

Kim, Kab-Jin; Yoshimura, Yoko; Ham, Woo Seung; Ernst, Rick; Hirata, Yuushou; Li, Tian; Kim, Sanghoon; Moriyama, Takahiro; Nakatani, Yoshinobu; Ono, Teruo

2017-04-01

We present an energy-efficient magnetic domain-writing scheme for domain wall (DW) motion-based memory devices. A cross-shaped nanowire is employed to inject a domain into the nanowire through current-induced DW propagation. The energy required for injecting the magnetic domain is more than one order of magnitude lower than that for the conventional field-based writing scheme. The proposed scheme is beneficial for device miniaturization because the threshold current for DW propagation scales with the device size, which cannot be achieved in the conventional field-based technique.

Low power consumption resistance random access memory with Pt/InOx/TiN structure

NASA Astrophysics Data System (ADS)

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

2013-09-01

In this study, the resistance switching characteristics of a resistive random access memory device with Pt/InOx/TiN structure is investigated. Unstable bipolar switching behavior is observed during the initial switching cycle, which then stabilizes after several switching cycles. Analyses indicate that the current conduction mechanism in the resistance state is dominated by Ohmic conduction. The decrease in electrical conductance can be attributed to the reduction of the cross-sectional area of the conduction path. Furthermore, the device exhibits low operation voltage and power consumption.

Distinguished Flying Cross National Memorial Act

THOMAS, 112th Congress

Sen. Boxer, Barbara [D-CA

2011-05-02

Senate - 07/28/2011 Committee on Energy and Natural Resources Subcommittee on National Parks. Hearings held. With printed Hearing: S.Hrg. 112-214. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

Scalable cross-point resistive switching memory and mechanism through an understanding of H2O2/glucose sensing using an IrOx/Al2O3/W structure.

PubMed

Chakrabarti, Somsubhra; Maikap, Siddheswar; Samanta, Subhranu; Jana, Surajit; Roy, Anisha; Qiu, Jian-Tai

2017-10-04

The resistive switching characteristics of a scalable IrO x /Al 2 O 3 /W cross-point structure and its mechanism for pH/H 2 O 2 sensing along with glucose detection have been investigated for the first time. Porous IrO x and Ir 3+ /Ir 4+ oxidation states are observed via high-resolution transmission electron microscope, field-emission scanning electron spectroscopy, and X-ray photo-electron spectroscopy. The 20 nm-thick IrO x devices in sidewall contact show consecutive long dc cycles at a low current compliance (CC) of 10 μA, multi-level operation with CC varying from 10 μA to 100 μA, and long program/erase endurance of >10 9 cycles with 100 ns pulse width. IrO x with a thickness of 2 nm in the IrO x /Al 2 O 3 /SiO 2 /p-Si structure has shown super-Nernstian pH sensitivity of 115 mV per pH, and detection of H 2 O 2 over the range of 1-100 nM is also achieved owing to the porous and reduction-oxidation (redox) characteristics of the IrO x membrane, whereas a pure Al 2 O 3 /SiO 2 membrane does not show H 2 O 2 sensing. A simulation based on Schottky, hopping, and Fowler-Nordheim tunneling conduction, and a redox reaction, is proposed. The experimental I-V curve matches very well with simulation. The resistive switching mechanism is owing to O 2- ion migration, and the redox reaction of Ir 3+ /Ir 4+ at the IrO x /Al 2 O 3 interface through H 2 O 2 sensing as well as Schottky barrier height modulation is responsible. Glucose at a low concentration of 10 pM is detected using a completely new process in the IrO x /Al 2 O 3 /W cross-point structure. Therefore, this cross-point memory shows a method for low cost, scalable, memory with low current, multi-level operation, which will be useful for future highly dense three-dimensional (3D) memory and as a bio-sensor for the future diagnosis of human diseases.

Sex differences in episodic memory in early midlife: impact of reproductive aging.

PubMed

Rentz, Dorene M; Weiss, Blair K; Jacobs, Emily G; Cherkerzian, Sara; Klibanski, Anne; Remington, Anne; Aizley, Harlyn; Goldstein, Jill M

2017-04-01

Few have characterized cognitive changes with age as a function of menopausal stage relative to men, or sex differences in components of memory in early midlife. The study aim was to investigate variation in memory function in early midlife as a function of sex, sex steroid hormones, and reproductive status. A total of 212 men and women aged 45 to 55 were selected for this cross-sectional study from a prenatal cohort of pregnancies whose mothers were originally recruited in 1959 to 1966. They underwent clinical and cognitive testing and hormonal assessments of menopause status. Multivariate general linear models for multiple memory outcomes were used to test hypotheses controlling for potential confounders. Episodic memory, executive function, semantic processing, and estimated verbal intelligence were assessed. Associative memory and episodic verbal memory were assessed using Face-Name Associative Memory Exam (FNAME) and Selective Reminding Test (SRT), given increased sensitivity to detecting early cognitive decline. Impacts of sex and reproductive stage on performance were tested. Women outperformed men on all memory measures including FNAME (β = -0.30, P < 0.0001) and SRT (β = -0.29, P < 0.0001). Furthermore, premenopausal and perimenopausal women outperformed postmenopausal women on FNAME (initial learning, β= 0.32, P = 0.01) and SRT (recall, β= 2.39, P = 0.02). Across all women, higher estradiol was associated with better SRT performance (recall, β = 1.96, P = 0.01) and marginally associated with FNAME (initial learning, β = 0.19, P = 0.06). This study demonstrated that, in early midlife, women outperformed age-matched men across all memory measures, but sex differences were attenuated for postmenopausal women. Initial learning and memory retrieval were particularly vulnerable, whereas memory consolidation and storage were preserved. Findings underscore the significance of the decline in ovarian estradiol production in midlife and its role in shaping memory function.

Nanoscale superconducting memory based on the kinetic inductance of asymmetric nanowire loops

NASA Astrophysics Data System (ADS)

Murphy, Andrew; Averin, Dmitri V.; Bezryadin, Alexey

2017-06-01

The demand for low-dissipation nanoscale memory devices is as strong as ever. As Moore’s law is staggering, and the demand for a low-power-consuming supercomputer is high, the goal of making information processing circuits out of superconductors is one of the central goals of modern technology and physics. So far, digital superconducting circuits could not demonstrate their immense potential. One important reason for this is that a dense superconducting memory technology is not yet available. Miniaturization of traditional superconducting quantum interference devices is difficult below a few micrometers because their operation relies on the geometric inductance of the superconducting loop. Magnetic memories do allow nanometer-scale miniaturization, but they are not purely superconducting (Baek et al 2014 Nat. Commun. 5 3888). Our approach is to make nanometer scale memory cells based on the kinetic inductance (and not geometric inductance) of superconducting nanowire loops, which have already shown many fascinating properties (Aprili 2006 Nat. Nanotechnol. 1 15; Hopkins et al 2005 Science 308 1762). This allows much smaller devices and naturally eliminates magnetic-field cross-talk. We demonstrate that the vorticity, i.e., the winding number of the order parameter, of a closed superconducting loop can be used for realizing a nanoscale nonvolatile memory device. We demonstrate how to alter the vorticity in a controlled fashion by applying calibrated current pulses. A reliable read-out of the memory is also demonstrated. We present arguments that such memory can be developed to operate without energy dissipation.

Relation between Working Memory Capacity and Auditory Stream Segregation in Children with Auditory Processing Disorder

PubMed Central

Lotfi, Yones; Mehrkian, Saiedeh; Moossavi, Abdollah; Zadeh, Soghrat Faghih; Sadjedi, Hamed

2016-01-01

Background: This study assessed the relationship between working memory capacity and auditory stream segregation by using the concurrent minimum audible angle in children with a diagnosed auditory processing disorder (APD). Methods: The participants in this cross-sectional, comparative study were 20 typically developing children and 15 children with a diagnosed APD (age, 9–11 years) according to the subtests of multiple-processing auditory assessment. Auditory stream segregation was investigated using the concurrent minimum audible angle. Working memory capacity was evaluated using the non-word repetition and forward and backward digit span tasks. Nonparametric statistics were utilized to compare the between-group differences. The Pearson correlation was employed to measure the degree of association between working memory capacity and the localization tests between the 2 groups. Results: The group with APD had significantly lower scores than did the typically developing subjects in auditory stream segregation and working memory capacity. There were significant negative correlations between working memory capacity and the concurrent minimum audible angle in the most frontal reference location (0° azimuth) and lower negative correlations in the most lateral reference location (60° azimuth) in the children with APD. Conclusion: The study revealed a relationship between working memory capacity and auditory stream segregation in children with APD. The research suggests that lower working memory capacity in children with APD may be the possible cause of the inability to segregate and group incoming information. PMID:26989281

No differences in performance on test of working memory and executive functioning between healthy elderly postmenopausal women using or not using hormone therapy.

PubMed

Grigorova, M; Sherwin, B B

2006-06-01

On average, ovarian function ceases at the age of 52 years so that estrogen (E) levels are chronically low following the menopause. Numerous studies have found that hormone therapy (HT) helps to protect verbal memory, a hippocampal function. Estrogen receptors are also found in the prefrontal cortex (PFC), suggesting that estrogen may modulate executive and working memory functions, both mediated by the PFC. The possible role of progesterone (P) on executive functions and working memory is unknown. To examine the relationship between neuropsychological performance, age of initiation of HT, and duration of HT use. In this cross-sectional study, the neuropsychological performance of 37 postmenopausal women (mean age, 65 years) who used either estrogen-only or sequential E + P (E-alone group)(n = 22) or E + P continuously (n = 15) was compared to that of 28 healthy postmenopausal women matched for age and education who had never used HT. It was hypothesized that the E-only users would perform better then the E + P and the never-users on neuropsychological tests of verbal memory, executive function and working memory. Results showed only minor between-group differences on working memory scores such that the E + P users were slowest to generate a response on the N-Back test of working memory. No group differences on tests of executive functions were found. There was no relationship between neuropsychological performance, age of initiation of HT, or duration of HT use.

Contribution of norepinephrine to emotional memory consolidation during sleep.

PubMed

Groch, Sabine; Wilhelm, Ines; Diekelmann, Susanne; Sayk, Friedhelm; Gais, Steffen; Born, Jan

2011-10-01

There is increasing evidence indicating that slow wave sleep (SWS) supports memory consolidation. This effect may in part originate from phasic noradrinergic (NE) activity occurring during SWS in the presence of tonically lowered NE levels. Here, we examined whether NE supports the consolidation of amygdala-dependent emotional memory during SWS. In a double-blind cross-over study, 15 men learned emotional and neutral materials (stories, pictures) in the evening before a 3-h period of early SWS-rich retention sleep, during which either placebo or clonidine, an α2-adrenoceptor agonist which blocks locus coeruleus NE release, was intravenously infused. Memory retrieval as well as affective ratings and heart rate responses to the pictures were assessed 23 h after learning. Clonidine reduced plasma NE levels but had no effect on SWS. While retention of story content words and pictures per se remained unaffected, clonidine distinctly blocked the superiority of emotional compared to neutral memory for temporal order, with this superiority of emotional over neutral memories observed only in the placebo condition. Heart rate responses to pictures were not affected, but whereas under placebo conditions familiar negative pictures were rated less arousing and with a more negative valence compared to pictures not seen before; these differences were abolished after clonidine. Given that memory for the temporal order of events depends on the hippocampus to a greater extent than item memory, our findings suggest that NE activity during early SWS-rich sleep facilitates consolidation of memories that involve both, a strong amygdalar and hippocampal component. Copyright © 2011 Elsevier Ltd. All rights reserved.

Emotional memory can be persistently weakened by suppressing cortisol during retrieval.

PubMed

Rimmele, Ulrike; Besedovsky, Luciana; Lange, Tanja; Born, Jan

2015-03-01

Cortisol's effects on memory follow an inverted U-shaped function such that memory retrieval is impaired with very low concentrations, presumably due to insufficient activation of high-affine mineralocorticoid receptors (MR), or with very high concentrations, due to predominant low-affine glucocorticoid receptor (GR) activation. Through corresponding changes in re-encoding, the retrieval effect of cortisol might translate into a persistent change of the retrieved memory. We tested whether partial suppression of morning cortisol synthesis by metyrapone, leading to intermediate, circadian nadir-like levels with presumed predominant MR activation, improves retrieval, particularly of emotional memory, and persistently changes the memory. In a randomized, placebo-controlled, double-blind, within-subject cross-over design, 18 men were orally administered metyrapone (1g) vs. placebo at 4:00 AM to suppress the morning cortisol rise. Retrieval of emotional and neutral texts and pictures (learned 3 days earlier) was assessed 4h after substance administration and a second time one week later. Metyrapone suppressed endogenous cortisol release to circadian nadir-equivalent levels at the time of retrieval testing. Contrary to our expectations, metyrapone significantly impaired free recall of emotional texts (p<.05), whereas retrieval of neutral texts or pictures remained unaffected. One week later, participants still showed lower memory for emotional texts in the metyrapone than placebo condition (p<.05). Our finding that suppressing morning cortisol to nadir-like concentrations not only impairs acute retrieval, but also persistently weakens emotional memories corroborates the concept that retrieval effects of cortisol produce persistent memory changes, possibly by affecting re-encoding. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Cortisol effects on autobiographic memory retrieval in PTSD: an analysis of word valence and time until retrieval.

PubMed

Wingenfeld, Katja; Driessen, Martin; Schlosser, Nicole; Terfehr, Kirsten; Carvalho Fernando, Silvia; Wolf, Oliver Tobias

2013-09-01

In healthy participants, cortisol administration has been found to impair autobiographic memory retrieval. We recently reported that administration of 10 mg of hydrocortisone had enhancing effects on autobiographical memory retrieval, i.e. more specific memory retrieval, in patients with posttraumatic stress disorder (PTSD), while in healthy controls the impairing effects were replicated. We here report a re-analysis of these data with respect to cue-word valence and retrieval time. In a placebo-controlled cross-over study, 43 patients with PTSD and 43 age- and sex-matched healthy controls received either placebo or hydrocortisone orally before the autobiographical memory test was performed. We found that the effects of cortisol on memory retrieval depended on cue-word valence and group (significant interaction effects of drug by group and drug by valence by group). The enhancing effect of cortisol on memory retrieval in PTSD seemed to be relatively independent of cue-word valence, while in the control group the impairing effects of cortisol were only seen in response to neutral cue-words. The second result of the study was that in patients as well as in controls, cortisol administration led to faster memory retrieval compared to placebo. This was seen in response to positive and (to lesser extend) to neutral cue-words, but not in response to negative cue-words. Our findings illustrate that the opposing effects of cortisol on autobiographical memory retrieval in PTSD patients and controls are further modulated by the emotionality of the cue-words.

Trauma memory characteristics and the development of acute stress disorder and post-traumatic stress disorder in youth.

PubMed

McKinnon, A; Brewer, N; Meiser-Stedman, R; Nixon, R D V

2017-03-01

The present study addresses gaps in knowledge regarding the association between trauma memory processes and posttraumatic stress responses in youth. Our primary goal was to explore the relative contribution of perceptions of trauma memory quality versus narrative trauma memory characteristics to explain overall adjustment. Children (N = 67) were interviewed within four weeks (T1) of an injury leading to hospital treatment and then again eight weeks later (T2). In each interview, the child told a trauma narrative (which were later coded), and answered the Trauma Memory Quality Questionnaire (Meiser-Stedman, Smith, Yule, & Dalgleish, 2007a), a self-report measure indexing the sensory, fragmented, and disorganised characteristics of trauma memory. They then completed measures of Acute Stress Disorder (ASD) symptoms and associated psychopathology at T1 and measures of Posttraumatic Stress (PTS) symptoms and associated psychopathology at T2. Self-reported trauma memory characteristics predicted ASD symptoms cross-sectionally at T1 and PTS symptoms prospectively over time. At both time points, self-reported trauma memory characteristics accounted for all of the unique variance in symptoms initially explained by narrative characteristics. A reduction in self-report ratings, but not the hypothesised narrative features (e.g., disorganised or lexical elements of the narrative), significantly predicted a reduction in PTS symptoms over time. The small sample size and the absence of a within-subjects narrative control were the main limitations of the study. These findings underscore the importance of self-reported trauma memory characteristics to the aetiology of PTSD. Copyright © 2016 Elsevier Ltd. All rights reserved.

Memory and mood during the night and in the morning after repeated evening doses of MDMA.

PubMed

Kuypers, K P C; Wingen, M; Ramaekers, J G

2008-11-01

Previously it has been shown that MDMA causes memory impairment during daytime testing. However, MDMA is usually taken in the evening or during the night. In addition, it is known that sleep deprivation also causes memory impairment. The present study aimed to assess whether evening doses of MDMA added to, or interacted with the memory impairment due to sleep deprivation. Fourteen healthy subjects participated in a double-blind, placebo-controlled, two-way cross-over study. Treatments consisted of MDMA 75 and 50 mg divided over the evening or double placebo. Memory tests and subjective measures of mood were conducted at baseline and three times post dosing that is at 6.30 pm, 9.30 pm, 1.30 am and 7 am, respectively -1.5, 1.5, 5.5 and 11 h relative to drug intake (first dose). Memory performance detoriated progessively over time as a function of sleep loss, independent of treatment. MDMA added to this impairment as indicated by a significant main effect of MDMA on verbal and spatial memory performance. Mood ratings and response speed revealed an MDMA by Time interaction. After administration of MDMA response speed improved and feelings of vigor, friendliness, elation, anxiety, confusion, arousal and positive mood increased in magnitude during the night, while all these parameters returned to placebo-like levels on the final morning session. It is concluded that evening doses of MDMA selectively impair memory performance, and that this impairment is additional to the effect of sleep deprivation on memory performance.

Position, scale, and rotation invariant holographic associative memory

NASA Astrophysics Data System (ADS)

Fielding, Kenneth H.; Rogers, Steven K.; Kabrisky, Matthew; Mills, James P.

1989-08-01

This paper describes the development and characterization of a holographic associative memory (HAM) system that is able to recall stored objects whose inputs were changed in position, scale, and rotation. The HAM is based on the single iteration model described by Owechko et al. (1987); however, the system described uses a self-pumped BaTiO3 phase conjugate mirror, rather than a degenerate four-wave mixing proposed by Owechko and his coworkers. The HAM system can store objects in a position, scale, and rotation invariant feature space. The angularly multiplexed diffuse Fourier transform holograms of the HAM feature space are characterized as the memory unit; distorted input objects are correlated with the hologram, and the nonlinear phase conjugate mirror reduces cross-correlation noise and provides object discrimination. Applications of the HAM system are presented.

Neuropsychological Correlates of Diffusion Tensor Imaging in Schizophrenia

PubMed Central

Nestor, Paul G.; Kubicki, Marek; Gurrera, Ronald J.; Niznikiewicz, Margaret; Frumin, Melissa; McCarley, Robert W.; Shenton, Martha E.

2009-01-01

Patients with schizophrenia (n = 41) and healthy comparison participants (n = 46) completed neuropsychological measures of intelligence, memory, and executive function. A subset of each group also completed magnetic resonance diffusion tensor imaging (DTI) studies (fractional anisotropy and cross-sectional area) of the uncinate fasciculus (UF) and cingulate bundle (CB). Patients with schizophrenia showed reduced levels of functioning across all neuropsychological measures. In addition, selective neuropsychological–DTI relationships emerged. Among patients but not controls, lower levels of declarative–episodic verbal memory correlated with reduced left UF, whereas executive function errors related to performance monitoring correlated with reduced left CB. The data suggested abnormal DTI patterns linking declarative–episodic verbal memory deficits to the left UF and executive function deficits to the left CB among patients with schizophrenia. PMID:15506830

Subjective health and memory self-efficacy as mediators in the relation between subjective age and life satisfaction among older adults.

PubMed

Stephan, Yannick; Caudroit, Johan; Chalabaev, Aïna

2011-05-01

Perceiving oneself as younger than one's actual age functions as a self-enhancing positive illusion that promotes life satisfaction. However, no research has yet focused on the mechanisms through which a youthful subjective age could be related to higher life satisfaction. The purpose of this study was to identify the mediating role of resources, such as subjective health and memory self-efficacy, in the relation between subjective age and life satisfaction among older adults. A cross-sectional study was conducted with 250 older individuals aged from 60 to 77 years who completed measures of subjective age, subjective health, memory self-efficacy, and life satisfaction. Path analysis revealed that subjective age was positively related to both subjective health and memory self-efficacy, and that subjective health and memory self-efficacy were both positively related to life satisfaction. Bootstrap procedures further indicated that subjective age has significant total and specific indirect contribution to life satisfaction through subjective health and memory self-efficacy. This study fills a gap in existing literature and suggests that a youthful subjective age is associated with higher life satisfaction because it is related to higher evaluation of health and memory self-efficacy. It provides an initial support for a resource-based explanation of the relation between subjective age and life satisfaction.

Rivastigmine but not vardenafil reverses cannabis-induced impairment of verbal memory in healthy humans.

PubMed

Theunissen, E L; Heckman, P; de Sousa Fernandes Perna, E B; Kuypers, K P C; Sambeth, A; Blokland, A; Prickaerts, J; Toennes, S W; Ramaekers, J G

2015-01-01

One of the most often reported cognitive deficits of acute cannabis administration is an impaired recall of previously learned information. The aim of the present study was to determine whether cannabis-induced memory impairment in humans is mediated via glutamatergic or cholinergic pathways. Fifteen occasional cannabis users participated in a double-blind, placebo-controlled, six-way cross-over study. On separate test days, subjects received combinations of pretreatment (placebo, vardenafil 20 mg or rivastigmine 3 mg) and treatment (placebo or 1,376 mg cannabis/kg body weight). Cognitive tests were administered immediately after inhalation of treatment was finished and included measures of memory (visual verbal learning task, prospective memory test, Sternberg memory test), perceptual-motor control (critical tracking task), attention (divided attention task) and motor impulsivity (stop signal task). The results of this study demonstrate that subjects under the influence of cannabis were impaired in all memory tasks, in critical tracking, divided attention and the stop signal task. Pretreatment with rivastigmine attenuated the effect of cannabis on delayed recall and showed a trend towards significance on immediate recall. When cannabis was given in combination with vardenafil, there were no significant interaction effects in any of the tasks. The present data therefore suggest that acetylcholine plays an important role in cannabis-induced memory impairment, whereas similar results for glutamate have not been demonstrated in this study.

Does cognitive performance map to categorical diagnoses of schizophrenia, schizoaffective disorder and bipolar disorder? A discriminant functions analysis.

PubMed

Van Rheenen, Tamsyn E; Bryce, Shayden; Tan, Eric J; Neill, Erica; Gurvich, Caroline; Louise, Stephanie; Rossell, Susan L

2016-03-01

Despite known overlaps in the pattern of cognitive impairments in individuals with bipolar disorder (BD), schizophrenia (SZ) and schizoaffective disorder (SZA), few studies have examined the extent to which cognitive performance validates traditional diagnostic boundaries in these groups. Individuals with SZ (n=49), schizoaffective disorder (n=33) and BD (n=35) completed a battery of cognitive tests measuring the domains of processing speed, immediate memory, semantic memory, learning, working memory, executive function and sustained attention. A discriminant functions analysis revealed a significant function comprising semantic memory, immediate memory and processing speed that maximally separated patients with SZ from those with BD. Initial classification scores on the basis of this function showed modest diagnostic accuracy, owing in part to the misclassification of SZA patients as having SZ. When SZA patients were removed from the model, a second cross-validated classifier yielded slightly improved diagnostic accuracy and a single function solution, of which semantic memory loaded most heavily. A cluster of non-executive cognitive processes appears to have some validity in mapping onto traditional nosological boundaries. However, since semantic memory performance was the primary driver of the discrimination between BD and SZ, it is possible that performance differences between the disorders in this cognitive domain in particular, index separate underlying aetiologies. Copyright © 2015 Elsevier B.V. All rights reserved.

1Interaction between serum BDNF and aerobic fitness predicts recognition memory in healthy young adults

PubMed Central

Whiteman, Andrew; Young, Daniel E.; He, Xuemei; Chen, Tai C.; Wagenaar, Robert C.; Stern, Chantal; Schon, Karin

2013-01-01

Convergent evidence from human and non-human animal studies suggests aerobic exercise and increased aerobic capacity may be beneficial for brain health and cognition. It is thought growth factors may mediate this putative relationship, particularly by augmenting plasticity mechanisms in the hippocampus, a brain region critical for learning and memory. Among these factors, glucocorticoids, brain derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF), hormones that have considerable and diverse physiological importance, are thought to effect normal and exercise-induced hippocampal plasticity. Despite these predictions, relatively few published human studies have tested hypotheses that relate exercise and fitness to the hippocampus, and none have considered the potential links to all of these hormonal components. Here we present cross-sectional data from a study of recognition memory; serum BDNF, cortisol, IGF-1, and VEGF levels; and aerobic capacity in healthy young adults. We measured circulating levels of these hormones together with performance on a recognition memory task, and a standard graded treadmill test of aerobic fitness. Regression analyses demonstrated BDNF and aerobic fitness predict recognition memory in an interactive manner. In addition, IGF-1 was positively associated with aerobic fitness, but not with recognition memory. Our results may suggest an exercise adaptation-related change in the BDNF dose-response curve that relates to hippocampal memory. PMID:24269495

Tolerance induction of IgG+ memory B cells by T cell-independent type II antigens.

PubMed

Haniuda, Kei; Nojima, Takuya; Ohyama, Kyosuke; Kitamura, Daisuke

2011-05-15

Memory B cells generated during a T cell-dependent immune response rapidly respond to a secondary immunization by producing abundant IgG Abs that bind cognate Ag with high affinity. It is currently unclear whether this heightened recall response by memory B cells is due to augmented IgG-BCR signaling, which has only been demonstrated in the context of naive transgenic B cells. To address this question, we examined whether memory B cells can respond in vivo to Ags that stimulate only through BCR, namely T cell-independent type II (TI-II) Ags. In this study, we show that the TI-II Ag (4-hydroxy-3-nitrophenyl) acetyl (NP)-Ficoll cannot elicit the recall response in mice first immunized with the T cell-dependent Ag NP-chicken γ-globulin. Moreover, the NP-Ficoll challenge in vivo as well as in vitro significantly inhibits a subsequent recall response to NP-chicken γ-globulin in a B cell-intrinsic manner. This NP-Ficoll-mediated tolerance is caused by the preferential elimination of IgG(+) memory B cells binding to NP with high affinity. These data indicate that BCR cross-linking with a TI-II Ag does not activate IgG(+) memory B cells, but rather tolerizes them, identifying a terminal checkpoint of memory B cell differentiation that may prevent autoimmunity.

Similar patterns of neural activity predict memory function during encoding and retrieval.

PubMed

Kragel, James E; Ezzyat, Youssef; Sperling, Michael R; Gorniak, Richard; Worrell, Gregory A; Berry, Brent M; Inman, Cory; Lin, Jui-Jui; Davis, Kathryn A; Das, Sandhitsu R; Stein, Joel M; Jobst, Barbara C; Zaghloul, Kareem A; Sheth, Sameer A; Rizzuto, Daniel S; Kahana, Michael J

2017-07-15

Neural networks that span the medial temporal lobe (MTL), prefrontal cortex, and posterior cortical regions are essential to episodic memory function in humans. Encoding and retrieval are supported by the engagement of both distinct neural pathways across the cortex and common structures within the medial temporal lobes. However, the degree to which memory performance can be determined by neural processing that is common to encoding and retrieval remains to be determined. To identify neural signatures of successful memory function, we administered a delayed free-recall task to 187 neurosurgical patients implanted with subdural or intraparenchymal depth electrodes. We developed multivariate classifiers to identify patterns of spectral power across the brain that independently predicted successful episodic encoding and retrieval. During encoding and retrieval, patterns of increased high frequency activity in prefrontal, MTL, and inferior parietal cortices, accompanied by widespread decreases in low frequency power across the brain predicted successful memory function. Using a cross-decoding approach, we demonstrate the ability to predict memory function across distinct phases of the free-recall task. Furthermore, we demonstrate that classifiers that combine information from both encoding and retrieval states can outperform task-independent models. These findings suggest that the engagement of a core memory network during either encoding or retrieval shapes the ability to remember the past, despite distinct neural interactions that facilitate encoding and retrieval. Copyright © 2017 Elsevier Inc. All rights reserved.

Ripple-triggered stimulation of the locus coeruleus during post-learning sleep disrupts ripple/spindle coupling and impairs memory consolidation

PubMed Central

Novitskaya, Yulia; Sara, Susan J.; Logothetis, Nikos K.

2016-01-01

Experience-induced replay of neuronal ensembles occurs during hippocampal high-frequency oscillations, or ripples. Post-learning increase in ripple rate is predictive of memory recall, while ripple disruption impairs learning. Ripples may thus present a fundamental component of a neurophysiological mechanism of memory consolidation. In addition to system-level local and cross-regional interactions, a consolidation mechanism involves stabilization of memory representations at the synaptic level. Synaptic plasticity within experience-activated neuronal networks is facilitated by noradrenaline release from the axon terminals of the locus coeruleus (LC). Here, to better understand interactions between the system and synaptic mechanisms underlying “off-line” consolidation, we examined the effects of ripple-associated LC activation on hippocampal and cortical activity and on spatial memory. Rats were trained on a radial maze; after each daily learning session neural activity was monitored for 1 h via implanted electrode arrays. Immediately following “on-line” detection of ripple, a brief train of electrical pulses (0.05 mA) was applied to LC. Low-frequency (20 Hz) stimulation had no effect on spatial learning, while higher-frequency (100 Hz) trains transiently blocked generation of ripple-associated cortical spindles and caused a reference memory deficit. Suppression of synchronous ripple/spindle events appears to interfere with hippocampal-cortical communication, thereby reducing the efficiency of “off-line” memory consolidation. PMID:27084931

Is There a Relation between EEG-Slow Waves and Memory Dysfunction in Epilepsy? A Critical Appraisal

PubMed Central

Höller, Yvonne; Trinka, Eugen

2015-01-01

Is there a relationship between peri-ictal slow waves, loss of consciousness, memory, and slow-wave sleep, in patients with different forms of epilepsy? We hypothesize that mechanisms, which result in peri-ictal slow-wave activity as detected by the electroencephalogram, could negatively affect memory processes. Slow waves (≤4 Hz) can be found in seizures with impairment of consciousness and also occur in focal seizures without impairment of consciousness but with inhibited access to memory functions. Peri-ictal slow waves are regarded as dysfunctional and are probably caused by mechanisms, which are essential to disturb the consolidation of memory entries in these patients. This is in strong contrast to physiological slow-wave activity during deep sleep, which is thought to group memory-consolidating fast oscillatory activity. In patients with epilepsy, slow waves may not only correlate with the peri-ictal clouding of consciousness, but could be the epiphenomenon of mechanisms, which interfere with normal brain function in a wider range. These mechanisms may have transient impacts on memory, such as temporary inhibition of memory systems, altered patterns of hippocampal–neocortical interactions during slow-wave sleep, or disturbed cross-frequency coupling of slow and fast oscillations. In addition, repeated tonic–clonic seizures over the years in uncontrolled chronic epilepsy may cause a progressive cognitive decline. This hypothesis can only be assessed in long-term prospective studies. These studies could disentangle the reversible short-term impacts of seizures, and the impacts of chronic uncontrolled seizures. Chronic uncontrolled seizures lead to irreversible memory impairment. By contrast, short-term impacts do not necessarily lead to a progressive cognitive decline but result in significantly impaired peri-ictal memory performance. PMID:26124717

Promoting Sleep Oscillations and Their Functional Coupling by Transcranial Stimulation Enhances Memory Consolidation in Mild Cognitive Impairment.

PubMed

Ladenbauer, Julia; Ladenbauer, Josef; Külzow, Nadine; de Boor, Rebecca; Avramova, Elena; Grittner, Ulrike; Flöel, Agnes

2017-07-26

Alzheimer's disease (AD) not only involves loss of memory functions, but also prominent deterioration of sleep physiology, which is already evident at the stage of mild cognitive impairment (MCI). Cortical slow oscillations (SO; 0.5-1 Hz) and thalamocortical spindle activity (12-15 Hz) during sleep, and their temporal coordination, are considered critical for memory formation. We investigated the potential of slow oscillatory transcranial direct current stimulation (so-tDCS), applied during a daytime nap in a sleep-state-dependent manner, to modulate these activity patterns and sleep-related memory consolidation in nine male and seven female human patients with MCI. Stimulation significantly increased overall SO and spindle power, amplified spindle power during SO up-phases, and led to stronger synchronization between SO and spindle power fluctuations in EEG recordings. Moreover, visual declarative memory was improved by so-tDCS compared with sham stimulation and was associated with stronger synchronization. These findings indicate a well-tolerated therapeutic approach for disordered sleep physiology and memory deficits in MCI patients and advance our understanding of offline memory consolidation. SIGNIFICANCE STATEMENT In the light of increasing evidence that sleep disruption is crucially involved in the progression of Alzheimer's disease (AD), sleep appears as a promising treatment target in this pathology, particularly to counteract memory decline. This study demonstrates the potential of a noninvasive brain stimulation method during sleep in patients with mild cognitive impairment (MCI), a precursor of AD, and advances our understanding of its mechanism. We provide first time evidence that slow oscillatory transcranial stimulation amplifies the functional cross-frequency coupling between memory-relevant brain oscillations and improves visual memory consolidation in patients with MCI. Copyright © 2017 the authors 0270-6474/17/377111-14$15.00/0.

Characteristics of Reduced Graphene Oxide Quantum Dots for a Flexible Memory Thin Film Transistor.

PubMed

Kim, Yo-Han; Lee, Eun Yeol; Lee, Hyun Ho; Seo, Tae Seok

2017-05-17

Reduced graphene oxide quantum dot (rGOQD) devices in formats of capacitor and thin film transistor (TFT) were demonstrated and examined as the first trial to achieve nonambipolar channel property. In addition, through a gold nanoparticle (Au NP) layer embedded between the rGOQD active channel and dielectric layer, memory capacitor and TFT performances were realized by capacitance-voltage (C-V) hysteresis and gate program, erase, and reprogram biases. First, capacitor structure of the rGOQD memory device was constructed to examine memory charging effect featured in hysteretic C-V behavior with a 30 nm dielectric layer of cross-linked poly(vinyl alcohol). For the intervening Au NP charging layer, self-assembled monolayer (SAM) formation of the Au NP was executed to utilize electrostatic interaction by a dip-coating process under ambient environments with a conformal fabrication uniformity. Second, the rGOQD memory TFT device was also constructed in the same format of the Au NPs SAMs on a flexible substrate. Characteristics of the rGOQD TFT output showed novel saturation curves unlike typical graphene-based TFTs. However, The rGOQD TFT device reveals relatively low on/off ratio of 10 1 and mobility of 5.005 cm 2 /V·s. For the memory capacitor, the flat-band voltage shift (ΔV FB ) was measured as 3.74 V for ±10 V sweep, and for the memory TFT, the threshold voltage shift (ΔV th ) by the Au NP charging was detected as 7.84 V. In summary, it was concluded that the rGOQD memory device could accomplish an ideal graphene-based memory performance, which could have provided a wide memory window and saturated output characteristics.

Long-term memory in older children/adolescents and adults with autism spectrum disorder.

PubMed

Williams, Diane L; Minshew, Nancy J; Goldstein, Gerald; Mazefsky, Carla A

2017-09-01

This study extends prior memory reports in autism spectrum disorders (ASD) by investigating memory for narratives after longer recall periods and by examining developmental aspects of narrative memory using a cross-sectional design. Forty-seven older children/adolescents with ASD and 31 youth with typical development (TD) and 39 adults with ASD and 45 TD adults were compared on memory for stories from standardized measures appropriate for each age group at three intervals (immediate, 30 min, and 2 day). Both the youth with and without ASD had difficulty with memory for story details with increasing time intervals. More of the youths with ASD performed in the range of impairment when recalling the stories 2 days later as compared to the TD group. The adults with ASD had more difficulty on memory for story details with increasing delay and were poorer at recall of thematic information (needed to create a gist) across the three delay conditions as compared to the TD group. Analyses of the individual results suggested that memory for details of most of the adults with ASD was not impaired when applying a clinical standard; however, a significant percentage of the adults with ASD did not make use of thematic information to organize the narrative information, which would have helped them to remember the stories. The youth with and without ASD performed similarly when both were at a stage of development when memory for details is the primary strategy. The adults with ASD had difficulty with use organizational strategies to support episodic memory. Autism Res 2017, 10: 1523-1532. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Experimental Study of Floating-Gate-Type Metal-Oxide-Semiconductor Capacitors with Nanosize Triangular Cross-Sectional Tunnel Areas for Low Operating Voltage Flash Memory Application

NASA Astrophysics Data System (ADS)

Liu, Yongxun; Guo, Ruofeng; Kamei, Takahiro; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Ishikawa, Yuki; Hayashida, Tetsuro; Sakamoto, Kunihiro; Ogura, Atsushi; Masahara, Meishoku

2012-06-01

The floating-gate (FG)-type metal-oxide-semiconductor (MOS) capacitors with planar (planar-MOS) and three-dimensional (3D) nanosize triangular cross-sectional tunnel areas (3D-MOS) have successfully been fabricated by introducing rapid thermal oxidation (RTO) and postdeposition annealing (PDA), and their electrical characteristics between the control gate (CG) and FG have been systematically compared. It was experimentally found in both planar- and 3D-MOS capacitors that the uniform and higher breakdown voltages are obtained by introducing RTO owing to the high-quality thermal oxide formation on the surface and etched edge regions of the n+ polycrystalline silicon (poly-Si) FG, and the leakage current is highly suppressed after PDA owing to the improved quality of the tetraethylorthosilicate (TEOS) silicon dioxide (SiO2) between CG and FG. Moreover, a lower breakdown voltage between CG and FG was obtained in the fabricated 3D-MOS capacitors as compared with that of planar-MOS capacitors thanks to the enhanced local electric field at the tips of triangular tunnel areas. The developed nanosize triangular cross-sectional tunnel area is useful for the fabrication of low operating voltage flash memories.

Interplay of non-Markov and internal friction effects in the barrier crossing kinetics of biopolymers: insights from an analytically solvable model.

PubMed

Makarov, Dmitrii E

2013-01-07

Conformational rearrangements in biomolecules (such as protein folding or enzyme-ligand binding) are often interpreted in terms of low-dimensional models of barrier crossing such as Kramers' theory. Dimensionality reduction, however, entails memory effects; as a result, the effective frictional drag force along the reaction coordinate nontrivially depends on the time scale of the transition. Moreover, when both solvent and "internal" friction effects are important, their interplay results in a highly nonlinear dependence of the effective friction on solvent viscosity that is not captured by common phenomenological models of barrier crossing. Here, these effects are illustrated using an analytically solvable toy model of an unstructured polymer chain involved in an inter- or intramolecular transition. The transition rate is calculated using the Grote-Hynes and Langer theories, which--unlike Kramers' theory--account for memory. The resulting effective frictional force exerted by the polymer along the reaction coordinate can be rationalized in terms of the effective number of monomers engaged in the transition. Faster transitions (relative to the polymer reconfiguration time scale) involve fewer monomers and, correspondingly, lower friction forces, because the polymer chain does not have enough time to reconfigure in response to the transition.

Positional priming of visual pop-out search is supported by multiple spatial reference frames

PubMed Central

Gokce, Ahu; Müller, Hermann J.; Geyer, Thomas

2015-01-01

The present study investigates the representations(s) underlying positional priming of visual ‘pop-out’ search (Maljkovic and Nakayama, 1996). Three search items (one target and two distractors) were presented at different locations, in invariant (Experiment 1) or random (Experiment 2) cross-trial sequences. By these manipulations it was possible to disentangle retinotopic, spatiotopic, and object-centered priming representations. Two forms of priming were tested: target location facilitation (i.e., faster reaction times – RTs– when the trial n target is presented at a trial n-1 target relative to n-1 blank location) and distractor location inhibition (i.e., slower RTs for n targets presented at n-1 distractor compared to n-1 blank locations). It was found that target locations were coded in positional short-term memory with reference to both spatiotopic and object-centered representations (Experiment 1 vs. 2). In contrast, distractor locations were maintained in an object-centered reference frame (Experiments 1 and 2). We put forward the idea that the uncertainty induced by the experiment manipulation (predictable versus random cross-trial item displacements) modulates the transition from object- to space-based representations in cross-trial memory for target positions. PMID:26136718

Windowed multipole for cross section Doppler broadening

NASA Astrophysics Data System (ADS)

Josey, C.; Ducru, P.; Forget, B.; Smith, K.

2016-02-01

This paper presents an in-depth analysis on the accuracy and performance of the windowed multipole Doppler broadening method. The basic theory behind cross section data is described, along with the basic multipole formalism followed by the approximations leading to windowed multipole method and the algorithm used to efficiently evaluate Doppler broadened cross sections. The method is tested by simulating the BEAVRS benchmark with a windowed multipole library composed of 70 nuclides. Accuracy of the method is demonstrated on a single assembly case where total neutron production rates and 238U capture rates compare within 0.1% to ACE format files at the same temperature. With regards to performance, clock cycle counts and cache misses were measured for single temperature ACE table lookup and for windowed multipole. The windowed multipole method was found to require 39.6% more clock cycles to evaluate, translating to a 7.9% performance loss overall. However, the algorithm has significantly better last-level cache performance, with 3 fewer misses per evaluation, or a 65% reduction in last-level misses. This is due to the small memory footprint of the windowed multipole method and better memory access pattern of the algorithm.

Diffusion, Dispersion, and Uncertainty in Anisotropic Fractal Porous Media

NASA Astrophysics Data System (ADS)

Monnig, N. D.; Benson, D. A.

2007-12-01

Motivated by field measurements of aquifer hydraulic conductivity (K), recent techniques were developed to construct anisotropic fractal random fields, in which the scaling, or self-similarity parameter, varies with direction and is defined by a matrix. Ensemble numerical results are analyzed for solute transport through these 2-D "operator-scaling" fractional Brownian motion (fBm) ln(K) fields. Contrary to some analytic stochastic theories for monofractal K fields, the plume growth rates never exceed Mercado's (1967) purely stratified aquifer growth rate of plume apparent dispersivity proportional to mean distance. Apparent super-stratified growth must be the result of other demonstrable factors, such as initial plume size. The addition of large local dispersion and diffusion does not significantly change the effective longitudinal dispersivity of the plumes. In the presence of significant local dispersion or diffusion, the concentration coefficient of variation CV={σc}/{\\langle c \\rangle} remains large at the leading edge of the plumes. This indicates that even with considerable mixing due to dispersion or diffusion, there is still substantial uncertainty in the leading edge of a plume moving in fractal porous media.

Solar particle induced upsets in the TDRS-1 attitude control system RAM during the October 1989 solar particle events

NASA Astrophysics Data System (ADS)

Croley, D. R.; Garrett, H. B.; Murphy, G. B.; Garrard, T. L.

1995-10-01

The three large solar particle events, beginning on October 19, 1989 and lasting approximately six days, were characterized by high fluences of solar protons and heavy ions at 1 AU. During these events, an abnormally large number of upsets (243) were observed in the random access memory of the attitude control system (ACS) control processing electronics (CPE) on-board the geosynchronous TDRS-1 (Telemetry and Data Relay Satellite). The RAR I unit affected was composed of eight Fairchild 93L422 memory chips. The Galileo spacecraft, launched on October 18, 1989 (one day prior to the solar particle events) observed the fluxes of heavy ions experienced by TDRS-1. Two solid-state detector telescopes on-board Galileo designed to measure heavy ion species and energy, were turned on during time periods within each of the three separate events. The heavy ion data have been modeled and the time history of the events reconstructed to estimate heavy ion fluences. These fluences were converted to effective LET spectra after transport through the estimated shielding distribution around the TDRS-1 ACS system. The number of single event upsets (SEU) expected was calculated by integrating the measured cross section for the Fairchild 93L422 memory chip with average effective LET spectrum. The expected number of heavy ion induced SEUs calculated was 176. GOES-7 proton data, observed during the solar particle events, were used to estimate the number of proton-induced SEUs by integrating the proton fluence spectrum incident on the memory chips, with the two-parameter Bendel cross section for proton SEUs.

Simulating Pre-Asymptotic, Non-Fickian Transport Although Doing Simple Random Walks - Supported By Empirical Pore-Scale Velocity Distributions and Memory Effects

NASA Astrophysics Data System (ADS)

Most, S.; Jia, N.; Bijeljic, B.; Nowak, W.

2016-12-01

Pre-asymptotic characteristics are almost ubiquitous when analyzing solute transport processes in porous media. These pre-asymptotic aspects are caused by spatial coherence in the velocity field and by its heterogeneity. For the Lagrangian perspective of particle displacements, the causes of pre-asymptotic, non-Fickian transport are skewed velocity distribution, statistical dependencies between subsequent increments of particle positions (memory) and dependence between the x, y and z-components of particle increments. Valid simulation frameworks should account for these factors. We propose a particle tracking random walk (PTRW) simulation technique that can use empirical pore-space velocity distributions as input, enforces memory between subsequent random walk steps, and considers cross dependence. Thus, it is able to simulate pre-asymptotic non-Fickian transport phenomena. Our PTRW framework contains an advection/dispersion term plus a diffusion term. The advection/dispersion term produces time-series of particle increments from the velocity CDFs. These time series are equipped with memory by enforcing that the CDF values of subsequent velocities change only slightly. The latter is achieved through a random walk on the axis of CDF values between 0 and 1. The virtual diffusion coefficient for that random walk is our only fitting parameter. Cross-dependence can be enforced by constraining the random walk to certain combinations of CDF values between the three velocity components in x, y and z. We will show that this modelling framework is capable of simulating non-Fickian transport by comparison with a pore-scale transport simulation and we analyze the approach to asymptotic behavior.

Relational Associative Learning Induces Cross-Modal Plasticity in Early Visual Cortex

PubMed Central

Headley, Drew B.; Weinberger, Norman M.

2015-01-01

Neurobiological theories of memory posit that the neocortex is a storage site of declarative memories, a hallmark of which is the association of two arbitrary neutral stimuli. Early sensory cortices, once assumed uninvolved in memory storage, recently have been implicated in associations between neutral stimuli and reward or punishment. We asked whether links between neutral stimuli also could be formed in early visual or auditory cortices. Rats were presented with a tone paired with a light using a sensory preconditioning paradigm that enabled later evaluation of successful association. Subjects that acquired this association developed enhanced sound evoked potentials in their primary and secondary visual cortices. Laminar recordings localized this potential to cortical Layers 5 and 6. A similar pattern of activation was elicited by microstimulation of primary auditory cortex in the same subjects, consistent with a cortico-cortical substrate of association. Thus, early sensory cortex has the capability to form neutral stimulus associations. This plasticity may constitute a declarative memory trace between sensory cortices. PMID:24275832

No lower cognitive functioning in older adults with attention-deficit/hyperactivity disorder.

PubMed

Semeijn, E J; Korten, N C M; Comijs, H C; Michielsen, M; Deeg, D J H; Beekman, A T F; Kooij, J J S

2015-09-01

Research illustrates cognitive deficits in children and younger adults with attention-deficit/hyperactivity disorder (ADHD). Few studies have focused on the cognitive functioning in older adults. This study investigates the association between ADHD and cognitive functioning in older adults. Data were collected in a cross-sectional side study of the Longitudinal Aging Study Amsterdam (LASA). A diagnostic interview to diagnose ADHD was administered among a subsample (N = 231, age 60-94). ADHD symptoms and diagnosis were assessed with the Diagnostic Interview for ADHD in Adults (DIVA) 2.0. Cognitive functioning was assessed with tests in the domains of executive functioning, information processing speed, memory, and attention/working memory. Regression analyses indicate that ADHD diagnosis and ADHD severity were only negatively associated with cognitive functioning in the attention/working memory domain. When adjusting for depression, these associations were no longer significant. The study shows that ADHD in older adults is associated with lower cognitive functioning in the attention/working memory domain. However, this was partly explained by depressive symptoms.

Expedition Memory: Towards Agent-based Web Services for Creating and Using Mars Exploration Data.

NASA Technical Reports Server (NTRS)

Clancey, William J.; Sierhuis, Maarten; Briggs, Geoff; Sims, Mike

2005-01-01

Explorers ranging over kilometers of rugged, sometimes "feature-less" terrain for over a year could be overwhelmed by tracking and sharing what they have done and learned. An automated system based on the existing Mobile Agents design [ I ] and Mars Exploration Rover experience [2], could serve as an "expedition memory" that would be indexed by voice as wel1 as a web interface, linking people, places, activities, records (voice notes, photographs, samples). and a descriptive scientific ontology. This database would be accessible during EVAs by astronauts, annotated by the remote science team, linked to EVA plans, and allow cross indexing between sites and expeditions. We consider the basic problem, our philosophical approach, technical methods, and uses of the expedition memory for facilitating long-term collaboration between Mars crews and Earth support teams. We emphasize that a "memory" does not mean a database per se, but an interactive service that combines different resources, and ultimately could be like a helpful librarian.

The Effect of Neurocognitive Function on Math Computation in Pediatric ADHD: Moderating Influences of Anxious Perfectionism and Gender.

PubMed

Sturm, Alexandra; Rozenman, Michelle; Piacentini, John C; McGough, James J; Loo, Sandra K; McCracken, James T

2018-03-20

Predictors of math achievement in attention-deficit/hyperactivity disorder (ADHD) are not well-known. To address this gap in the literature, we examined individual differences in neurocognitive functioning domains on math computation in a cross-sectional sample of youth with ADHD. Gender and anxiety symptoms were explored as potential moderators. The sample consisted of 281 youth (aged 8-15 years) diagnosed with ADHD. Neurocognitive tasks assessed auditory-verbal working memory, visuospatial working memory, and processing speed. Auditory-verbal working memory speed significantly predicted math computation. A three-way interaction revealed that at low levels of anxious perfectionism, slower processing speed predicted poorer math computation for boys compared to girls. These findings indicate the uniquely predictive values of auditory-verbal working memory and processing speed on math computation, and their differential moderation. These findings provide preliminary support that gender and anxious perfectionism may influence the relationship between neurocognitive functioning and academic achievement.

Living in history: how war, terrorism, and natural disaster affect the organization of autobiographical memory.

PubMed

Brown, Norman R; Lee, Peter J; Krslak, Mirna; Conrad, Frederick G; G B Hansen, Tia; Havelka, Jelena; Reddon, John R

2009-04-01

Memories of war, terrorism, and natural disaster play a critical role in the construction of group identity and the persistence of group conflict. Here, we argue that personal memory and knowledge of the collective past become entwined only when public events have a direct, forceful, and prolonged impact on a population. Support for this position comes from a cross-national study in which participants thought aloud as they dated mundane autobiographical events. We found that Bosnians often mentioned their civil war and that Izmit Turks made frequent reference to the 1999 earthquake in their country. In contrast, public events were rarely mentioned by Serbs, Montenegrins, Ankara Turks, Canadians, Danes, or Israelis. Surprisingly, historical references were absent from (post-September 11) protocols collected in New York City and elsewhere in the United States. Taken together, these findings indicate that it is personal significance, not historical importance, that determines whether public events play a role in organizing autobiographical memory.

Consolidation in older adults depends upon competition between resting-state networks

PubMed Central

Jacobs, Heidi I. L.; Dillen, Kim N. H.; Risius, Okka; Göreci, Yasemin; Onur, Oezguer A.; Fink, Gereon R.; Kukolja, Juraj

2015-01-01

Memory encoding and retrieval problems are inherent to aging. To date, however, the effect of aging upon the neural correlates of forming memory traces remains poorly understood. Resting-state fMRI connectivity can be used to investigate initial consolidation. We compared within and between network connectivity differences between healthy young and older participants before encoding, after encoding and before retrieval by means of resting-state fMRI. Alterations over time in the between-network connectivity analyses correlated with retrieval performance, whereas within-network connectivity did not: a higher level of negative coupling or competition between the default mode and the executive networks during the after encoding condition was associated with increased retrieval performance in the older adults, but not in the young group. Data suggest that the effective formation of memory traces depends on an age-dependent, dynamic reorganization of the interaction between multiple, large-scale functional networks. Our findings demonstrate that a cross-network based approach can further the understanding of the neural underpinnings of aging-associated memory decline. PMID:25620930

Blocking Mineralocorticoid Receptors Impairs, Blocking Glucocorticoid Receptors Enhances Memory Retrieval in Humans

PubMed Central

Rimmele, Ulrike; Besedovsky, Luciana; Lange, Tanja; Born, Jan

2013-01-01

Memory retrieval is impaired at very low as well as very high cortisol levels, but not at intermediate levels. This inverted-U-shaped relationship between cortisol levels and memory retrieval may originate from different roles of the mineralocorticoid (MR) and glucocorticoid receptor (GR) that bind cortisol with distinctly different affinity. Here, we examined the role of MRs and GRs in human memory retrieval using specific receptor antagonists. In two double-blind within-subject, cross-over designed studies, young healthy men were asked to retrieve emotional and neutral texts and pictures (learnt 3 days earlier) between 0745 and 0915 hours in the morning, either after administration of 400 mg of the MR blocker spironolactone vs placebo (200 mg at 2300 hours and 200 mg at 0400 hours, Study I) or after administration of the GR blocker mifepristone vs placebo (200 mg at 2300 hours, Study II). Blockade of MRs impaired free recall of both texts and pictures particularly for emotional material. In contrast, blockade of GRs resulted in better memory retrieval for pictures, with the effect being more pronounced for neutral than emotional materials. These findings indicate indeed opposing roles of MRs and GRs in memory retrieval, with optimal retrieval at intermediate cortisol levels likely mediated by high MR but concurrently low GR activation. PMID:23303058

Blocking mineralocorticoid receptors impairs, blocking glucocorticoid receptors enhances memory retrieval in humans.

PubMed

Rimmele, Ulrike; Besedovsky, Luciana; Lange, Tanja; Born, Jan

2013-04-01

Memory retrieval is impaired at very low as well as very high cortisol levels, but not at intermediate levels. This inverted-U-shaped relationship between cortisol levels and memory retrieval may originate from different roles of the mineralocorticoid (MR) and glucocorticoid receptor (GR) that bind cortisol with distinctly different affinity. Here, we examined the role of MRs and GRs in human memory retrieval using specific receptor antagonists. In two double-blind within-subject, cross-over designed studies, young healthy men were asked to retrieve emotional and neutral texts and pictures (learnt 3 days earlier) between 0745 and 0915 hours in the morning, either after administration of 400 mg of the MR blocker spironolactone vs placebo (200 mg at 2300 hours and 200 mg at 0400 hours, Study I) or after administration of the GR blocker mifepristone vs placebo (200 mg at 2300 hours, Study II). Blockade of MRs impaired free recall of both texts and pictures particularly for emotional material. In contrast, blockade of GRs resulted in better memory retrieval for pictures, with the effect being more pronounced for neutral than emotional materials. These findings indicate indeed opposing roles of MRs and GRs in memory retrieval, with optimal retrieval at intermediate cortisol levels likely mediated by high MR but concurrently low GR activation.

Aging, culture, and memory for socially meaningful item-context associations: an East-West cross-cultural comparison study.

PubMed

Yang, Lixia; Li, Juan; Spaniol, Julia; Hasher, Lynn; Wilkinson, Andrea J; Yu, Jing; Niu, Yanan

2013-01-01

Research suggests that people in Eastern interdependent cultures process information more holistically and attend more to contextual information than do people in Western independent cultures. The current study examined the effects of culture and age on memory for socially meaningful item-context associations in 71 Canadians of Western European descent (35 young and 36 older) and 72 native Chinese citizens (36 young and 36 older). All participants completed two blocks of context memory tasks. During encoding, participants rated pictures of familiar objects. In one block, objects were rated either for their meaningfulness in the independent living context or their typicality in daily life. In the other block, objects were rated for their meaningfulness in the context of fostering relationships with others or for their typicality in daily life. The encoding in each block was followed by a recognition test in which participants identified pictures and their associated contexts. The results showed that Chinese outperformed Canadians in context memory, though both culture groups showed similar age-related deficits in item and context memory. The results suggest that Chinese are at an advantage in memory for socially meaningful item-context associations, an advantage that continues from young adulthood into old age.

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

PubMed Central

Brown, Thackery I.; Stern, Chantal E.

2014-01-01

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

PTSD symptoms lead to modification in the memory of the trauma: a prospective study of former prisoners of war.

PubMed

Dekel, Sharon; Solomon, Zahava; Ein-Dor, Tsachi

2016-03-01

With the growing interest in the role of trauma memory in posttraumatic stress disorder (PTSD), this prospective study examined long-term changes in memory and the bidirectional relationship between symptoms of PTSD and trauma memory. A sample of Israeli former prisoners of the 1973 Yom Kippur War (N = 103) was assessed in 1991 and in 2008. Participants' PTSD symptom clusters, measured by the PTSD Inventory, and recollections of subjective and objective exposure during captivity, measured by a self-report questionnaire, were assessed at both times. Data on prewar and postwar negative life events and psychotherapy were also collected. Repeated-measures analysis revealed that participants' recollections were increasingly negative over time (P < .001). Applying an autoregressive cross-lagged modeling strategy showed that the PTSD symptoms of hyperarousal facilitated subsequent amplifications in their recollections (P < .01). These findings challenge the accuracy of reports of traumatic experiences and show that PTSD symptoms, in part, lead to the formation of more negative recollections over time. The findings suggest that the original memory is repeatedly updated under the influence of the individual's emotional state. The findings are discussed in the context of the reconsolidation theory of memory. © Copyright 2016 Physicians Postgraduate Press, Inc.

Neurocognitive Models of Medical Decision-Making Capacity in Traumatic Brain Injury Across Injury Severity.

PubMed

Triebel, Kristen L; Novack, Thomas A; Kennedy, Richard; Martin, Roy C; Dreer, Laura E; Raman, Rema; Marson, Daniel C

2016-01-01

To identify neurocognitive predictors of medical decision-making capacity (MDC) in participants with mild and moderate/severe traumatic brain injury (TBI). Academic medical center. Sixty adult controls and 104 adults with TBI (49 mild, 55 moderate/severe) evaluated within 6 weeks of injury. Prospective cross-sectional study. Participants completed the Capacity to Consent to Treatment Instrument to assess MDC and a neuropsychological test battery. We used factor analysis to reduce the battery test measures into 4 cognitive composite scores (verbal memory, verbal fluency, academic skills, and processing speed/executive function). We identified cognitive predictors of the 3 most clinically relevant Capacity to Consent to Treatment Instrument consent standards (appreciation, reasoning, and understanding). In controls, academic skills (word reading, arithmetic) and verbal memory predicted understanding; verbal fluency predicted reasoning; and no predictors emerged for appreciation. In the mild TBI group, verbal memory predicted understanding and reasoning, whereas academic skills predicted appreciation. In the moderate/severe TBI group, verbal memory and academic skills predicted understanding; academic skills predicted reasoning; and academic skills and verbal fluency predicted appreciation. Verbal memory was a predictor of MDC in controls and persons with mild and moderate/severe TBI. In clinical practice, impaired verbal memory could serve as a "red flag" for diminished consent capacity in persons with recent TBI.

Aging, Culture, and Memory for Socially Meaningful Item-Context Associations: An East-West Cross-Cultural Comparison Study

PubMed Central

Yang, Lixia; Li, Juan; Spaniol, Julia; Hasher, Lynn; Wilkinson, Andrea J.; Yu, Jing; Niu, Yanan

2013-01-01

Research suggests that people in Eastern interdependent cultures process information more holistically and attend more to contextual information than do people in Western independent cultures. The current study examined the effects of culture and age on memory for socially meaningful item-context associations in 71 Canadians of Western European descent (35 young and 36 older) and 72 native Chinese citizens (36 young and 36 older). All participants completed two blocks of context memory tasks. During encoding, participants rated pictures of familiar objects. In one block, objects were rated either for their meaningfulness in the independent living context or their typicality in daily life. In the other block, objects were rated for their meaningfulness in the context of fostering relationships with others or for their typicality in daily life. The encoding in each block was followed by a recognition test in which participants identified pictures and their associated contexts. The results showed that Chinese outperformed Canadians in context memory, though both culture groups showed similar age-related deficits in item and context memory. The results suggest that Chinese are at an advantage in memory for socially meaningful item-context associations, an advantage that continues from young adulthood into old age. PMID:23593288

Memory Age Identity as a predictor of cognitive function in the elderly: A 2-year follow-up study.

PubMed

Chang, Ki Jung; Hong, Chang Hyung; Lee, Yun Hwan; Chung, Young Ki; Lim, Ki Young; Noh, Jai Sung; Kim, Jin-Ju; Kim, Haena; Kim, Hyun-Chung; Son, Sang Joon

2018-01-01

There is a growing interest in finding psychosocial predictors related to cognitive function. In our previous research, we conducted a cross-sectional study on memory age identity (MAI) and found that MAI might be associated with objective cognitive performance in non-cognitively impaired elderly. A longitudinal study was conducted to better understand the importance of MAI as a psychosocial predictor related to objective cognitive function. Data obtained from 1345 Korean subjects aged 60 years and above were analyzed. During the two-year follow-up, subjective memory age was assessed on three occasions using the following question: How old do you feel based on your memory? Discrepancy between subjective memory age and chronological age was then calculated. We defined this value as 'memory age identity (MAI)'. A generalized estimating equation (GEE) was then obtained to demonstrate the relationship between MAI and Korean version-Mini Mental State Examination (K-MMSE) score over the 2 years of study. MAI was found to significantly (β=-0.03, p< 0.0001) predict objective cognitive performance in the non-cognitively impaired elderly. MAI may be a potential psychosocial predictor related to objective cognitive performance in the non-cognitively impaired elderly. Copyright © 2017 Elsevier B.V. All rights reserved.

Cladribine treatment of multiple sclerosis is associated with depletion of memory B cells.

PubMed

Ceronie, Bryan; Jacobs, Benjamin M; Baker, David; Dubuisson, Nicolas; Mao, Zhifeng; Ammoscato, Francesca; Lock, Helen; Longhurst, Hilary J; Giovannoni, Gavin; Schmierer, Klaus

2018-05-01

The mechanism of action of oral cladribine, recently licensed for relapsing multiple sclerosis, is unknown. To determine whether cladribine depletes memory B cells consistent with our recent hypothesis that effective, disease-modifying treatments act by physical/functional depletion of memory B cells. A cross-sectional study examined 40 people with multiple sclerosis at the end of the first cycle of alemtuzumab or injectable cladribine. The relative proportions and absolute numbers of peripheral blood B lymphocyte subsets were measured using flow cytometry. Cell-subtype expression of genes involved in cladribine metabolism was examined from data in public repositories. Cladribine markedly depleted class-switched and unswitched memory B cells to levels comparable with alemtuzumab, but without the associated initial lymphopenia. CD3 + T cell depletion was modest. The mRNA expression of metabolism genes varied between lymphocyte subsets. A high ratio of deoxycytidine kinase to group I cytosolic 5' nucleotidase expression was present in B cells and was particularly high in mature, memory and notably germinal centre B cells, but not plasma cells. Selective B cell cytotoxicity coupled with slow repopulation kinetics results in long-term, memory B cell depletion by cladribine. These may offer a new target, possibly with potential biomarker activity, for future drug development.

Evaluating spatial memory function in mice: a within-subjects comparison between the water maze test and its adaptation to dry land.

PubMed

Llano Lopez, L; Hauser, J; Feldon, J; Gargiulo, P A; Yee, B K

2010-05-01

The Morris water maze (WM) is a common spatial memory test in rats. It has been adapted for evaluating genetic manipulations in mice. One major acknowledged problem of this cross-species translation is floating. We investigated here in mice the feasibility and practicality of an alternative paradigm-the cheeseboard (CB), which is a dry version of the WM, in a within-subject design allowing direct comparison with the conventional WM. Under identical task demands (reference or working memory), mice learned in the CB as efficiently as in the WM. Furthermore, individual differences in learning rate correlated between the two reference memory tests conducted separately in the two mazes. However, no such correlation was found with respect to reference memory retention or working memory performance. This study demonstrated that the CB is an effective alternative to the WM as spatial cognition test. Additional tests in the CB confirmed that the mice relied on extra maze cues in their spatial search. We would recommend the CB as a valuable addition to, rather than a replacement of the WM in phenotyping transgenic mice, because the two apparatus might diverge in the ability to detect individual differences in various domains of mnemonic functions.

Immigration, Language Proficiency, and Autobiographical Memories: Lifespan Distribution and Second-Language Access

PubMed Central

Esposito, Alena G.; Baker-Ward, Lynne

2015-01-01

This investigation examined two controversies in the autobiographical literature: how cross-language immigration affects the distribution of autobiographical memories across the lifespan and under what circumstances language-dependent recall is observed. Both Spanish/English bilingual immigrants and English monolingual non-immigrants participated in a cue word study, with the bilingual sample taking part in a within-subject language manipulation. The expected bump in the number of memories from early life was observed for non-immigrants but not immigrants, who reported more memories for events surrounding immigration. Aspects of the methodology addressed possible reasons for past discrepant findings. Language-dependent recall was influenced by second-language proficiency. Results were interpreted as evidence that bilinguals with high second-language proficiency, in contrast to those with lower second-language proficiency, access a single conceptual store through either language. The final multi-level model predicting language-dependent recall, including second-language proficiency, age of immigration, internal language, and cue word language, explained ¾ of the between-person variance and ⅕ of the within-person variance. We arrive at two conclusions. First, major life transitions influence the distribution of memories. Second, concept representation across multiple languages follows a developmental model. In addition, the results underscore the importance of considering language experience in research involving memory reports. PMID:26274061

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

PubMed

Esposito, Alena G; Baker-Ward, Lynne

2016-08-01

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

Latent Semantic Analysis.

ERIC Educational Resources Information Center

Dumais, Susan T.

2004-01-01

Presents a literature review that covers the following topics related to Latent Semantic Analysis (LSA): (1) LSA overview; (2) applications of LSA, including information retrieval (IR), information filtering, cross-language retrieval, and other IR-related LSA applications; (3) modeling human memory, including the relationship of LSA to other…

Economic impact for the region of replacement of the Merchants Bridge.

DOT National Transportation Integrated Search

2016-01-01

The Merchants Memorial Mississippi Rail Bridge and MacArthur Bridge over the Mississippi River make up the most heavily used Mississippi River rail crossing in the country. A large contributor to the popularity of the Merchants Bridge is its accessib...

Cross-Cultural Invariance in Story Recall.

ERIC Educational Resources Information Center

Mandler, Jean M.; And Others

1980-01-01

Compares data on recall of stories by Liberian nonschooled children, nonliterate adults, nonschooled literate adults and schooled literate adults to similar data on American children and adults. Results indicate a universality of certain kinds of schematic organization and their control of memorial processes. (CM)

Simultaneous Presence of Non- and Highly Mutated Keyhole Limpet Hemocyanin (KLH)-Specific Plasmablasts Early after Primary KLH Immunization Suggests Cross-Reactive Memory B Cell Activation.

PubMed

Giesecke, Claudia; Meyer, Tim; Durek, Pawel; Maul, Jochen; Preiß, Jan; Jacobs, Joannes F M; Thiel, Andreas; Radbruch, Andreas; Ullrich, Reiner; Dörner, Thomas

2018-06-15

There are currently limited insights into the progression of human primary humoral immunity despite numerous studies in experimental models. In this study, we analyzed a primary and related secondary parenteral keyhole limpet hemocyanin (KLH) immunization in five human adults. The primary challenge elicited discordant KLH-specific serum and blood effector B cell responses (i.e., dominant serum KLH-specific IgG and IgM levels versus dominant KLH-specific IgA plasmablast frequencies). Single-cell IgH sequencing revealed early appearance of highly (>15 mutations) mutated circulating KLH-specific plasmablasts 2 wk after primary KLH immunization, with simultaneous KLH-specific plasmablasts carrying non- and low-mutated IgH sequences. The data suggest that the highly mutated cells might originate from cross-reactive memory B cells (mBCs) rather than from the naive B cell repertoire, consistent with previous reported mutation rates and the presence of KLH-reactive mBCs in naive vaccinees prior to immunization. Whereas upon secondary immunization, serum Ab response kinetics and plasmablast mutation loads suggested the exclusive reactivation of KLH-specific mBCs, we, however, detected only little clonal overlap between the peripheral KLH-specific secondary plasmablast IgH repertoire and the primary plasmablast and mBC repertoire, respectively. Our data provide novel mechanistic insights into human humoral immune responses and suggest that primary KLH immunization recruits both naive B cells and cross-reactive mBCs, whereas secondary challenge exclusively recruits from a memory repertoire, with little clonal overlap with the primary response. Copyright © 2018 by The American Association of Immunologists, Inc.

The Garrett Lee Smith Memorial Suicide Prevention Program

PubMed Central

Goldston, David B.; Walrath, Christine M.; McKeon, Richard; Puddy, Richard W.; Lubell, Keri M.; Potter, Lloyd B.; Rodi, Michael S.

2011-01-01

Responding to calls for greater efforts to reduce youth suicide, the Garrett Lee Smith (GLS) Memorial Act to date has provided funding for 68 state, territory, and tribal community grants, and 74 college campus grants for suicide prevention efforts. Suicide prevention activities supported by GLS grantees have included education, training programs including gatekeeper training, screening activities, infrastructure for improved linkages to services, crisis hotlines, and community partnerships. Through participation in both local- and cross-site evaluations, GLS grantees are generating data regarding the local context, proximal outcomes, and implementation of programs, as well as opportunities for improvement of suicide prevention efforts. PMID:20560746

The Garrett Lee Smith memorial suicide prevention program.

PubMed

Goldston, David B; Walrath, Christine M; McKeon, Richard; Puddy, Richard W; Lubell, Keri M; Potter, Lloyd B; Rodi, Michael S

2010-06-01

In response to calls for greater efforts to reduce youth suicide, the Garrett Lee Smith (GLS) Memorial Act has provided funding for 68 state, territory, and tribal community grants, and 74 college campus grants for suicide prevention efforts. Suicide prevention activities supported by GLS grantees have included education, training programs (including gatekeeper training), screening activities, infrastructure for improved linkages to services, crisis hotlines, and community partnerships. Through participation in both local- and cross-site evaluations, GLS grantees are generating data regarding the local context, proximal outcomes, and implementation of programs, as well as opportunities for improvement of suicide prevention efforts.

Cross talk and diffraction efficiency in angular multiplexed memories using improved polypeptide

NASA Astrophysics Data System (ADS)

Ramenah, Harry K.; Bertrand, Paul; Soubari, E. H.; Meyrueis, Patrick

1996-12-01

We studied energy coupling between gratings and angularly multiplexed 20 gratings with a uniform diffraction efficiency within 25 micrometer layer thickness of dichromated gelatin. The dependence of diffraction efficiency on beam ratio is given. We recorded a matrix form memory of nxmxp elements, where n and m are the rows and columns and p the number of multiplexes. For indication only, n equals m equals 10, p equals 20, the surface area of the matrix is 1 cm2. Color diffractive images and digital data are illustrated as well as video, cartography and medical applications.

Timing the state of light with anomalous dispersion and a gradient echo memory

NASA Astrophysics Data System (ADS)

Clark, Jeremy B.

We study the effects of anomalous dispersion on the continuous-variable entanglement of EPR states (generated using four-wave mixing in 85 Rb) by sending one part of the state through a fast-light medium and measuring the state's quantum mutual information. We observe an advance in the maximum of the quantum mutual information between modes. In contrast, due to uncorrelated noise added by a small phase-insensitive gain, we do not observe any statistically significant advance in the leading edge of the mutual information. We also study the storage and retrieval of multiplexed optical signals in a Gradient Echo Memory (GEM) at relevant four-wave mixing frequencies in 85Rb. Temporal multiplexing capabilities are demonstrated by storing multiple classical images in the memory simultaneously and observing the expected first-in last-out order of recall without obvious cross-talk. We also develop a technique wherein selected portions of an image written into the memory can be spatially targeted for readout and erasure on demand. The effect of diffusion on the quality of the recalled images is characterized. Our results indicate that Raman-based atomic memories may serve as a flexible platform for the storage and retrieval of multiplexed optical signals.

Flammulina velutipes polysaccharides improve scopolamine-induced learning and memory impairment in mice by modulating gut microbiota composition.

PubMed

Su, Anxiang; Yang, Wenjian; Zhao, Liyan; Pei, Fei; Yuan, Biao; Zhong, Lei; Ma, Gaoxing; Hu, Qiuhui

2018-03-01

Flammulina velutipes polysaccharides (FVP) have been proved to be effective in improving learning and memory impairment in mice. However, their underlying mechanism remains unclear. The aim of this study was to investigate the relationship between memory improvement and gut microbiota regulation of FVP. The results showed a significant decrease in the relative abundances of Clostridia and Bacilli but a significant increase in Bacteroidia, Erysipelotrichia and Actinobacteria in the FVP-treated group versus the control group. Fecal microbiota transplantation of mice with 'FVP microbiota' derived from FVP-fed mice resulted in improved learning and memory function compared to colonization with 'common microbiota' derived from control individuals. FVP and 'FVP microbiota' significantly increased the numbers of platform crossings and the swimming distance of mice in the probe test and decreased the escape latency and total swimming distance of mice in the hidden platform test. Moreover, FVP and 'FVP microbiota' regulated cytokines, such as IL-1β, TNF-α, IL-6 and IL-10, suggesting a mechanism involving the suppression of neuroinflammation. This study indicated that the regulation of the gut microbiome may have a causal role in improving scopolamine-induced impairment of learning and memory.

Individual differences in language and working memory affect children's speech recognition in noise.

PubMed

McCreery, Ryan W; Spratford, Meredith; Kirby, Benjamin; Brennan, Marc

2017-05-01

We examined how cognitive and linguistic skills affect speech recognition in noise for children with normal hearing. Children with better working memory and language abilities were expected to have better speech recognition in noise than peers with poorer skills in these domains. As part of a prospective, cross-sectional study, children with normal hearing completed speech recognition in noise for three types of stimuli: (1) monosyllabic words, (2) syntactically correct but semantically anomalous sentences and (3) semantically and syntactically anomalous word sequences. Measures of vocabulary, syntax and working memory were used to predict individual differences in speech recognition in noise. Ninety-six children with normal hearing, who were between 5 and 12 years of age. Higher working memory was associated with better speech recognition in noise for all three stimulus types. Higher vocabulary abilities were associated with better recognition in noise for sentences and word sequences, but not for words. Working memory and language both influence children's speech recognition in noise, but the relationships vary across types of stimuli. These findings suggest that clinical assessment of speech recognition is likely to reflect underlying cognitive and linguistic abilities, in addition to a child's auditory skills, consistent with the Ease of Language Understanding model.

Effects of prestudy and poststudy rest on memory: Support for temporal interference accounts of forgetting.

PubMed

Ecker, Ullrich K H; Tay, Jia-Xin; Brown, Gordon D A

2015-06-01

According to interference-based theories of memory, including temporal-distinctiveness theory, both prestudy and poststudy rest should have beneficial impacts on memory performance. Specifically, higher temporal isolation of a memorandum should reduce proactive and/or retroactive interference, and thus should result in better recall. In the present study, we investigated the effects of prestudy and poststudy rest in a free recall paradigm. Participants studied three lists of words, separated by either a short or a long period of low mental activity (a tone-detection task). Recall targeted the second list; this list was studied in one of four conditions, defined by the fully crossed factors of prestudy and poststudy rest duration. Two experiments revealed a beneficial effect of prestudy rest (and, to a lesser extent, of poststudy rest) on list recall. This result is in line with interference-based theories of memory. By contrast, a beneficial effect of prestudy rest is not predicted by consolidation accounts of memory and forgetting; our results thus require additional assumptions and/or a better specification of the consolidation process and its time course in order to be reconciled with consolidation theory.

Increased dietary vitamin K intake is associated with less severe subjective memory complaint among older adults.

PubMed

Soutif-Veillon, Anne; Ferland, Guylaine; Rolland, Yves; Presse, Nancy; Boucher, Kariane; Féart, Catherine; Annweiler, Cedric

2016-11-01

Increased dietary intake of vitamin K, a fat-soluble nutrient involved in brain health and function, has been associated with better cognitive performance in older adults. Our objective was to determine whether the dietary vitamin K intake was associated with the presence and severity of subjective memory complaint among older adults. Observational, cross-sectional cohort study. One hundred sixty older adults taking no vitamin K antagonist were included. The daily dietary vitamin K intake was assessed using a 50-item food frequency questionnaire. The subjective memory complaint was assessed at the same time using the Memory Complaint Questionnaire (MAC-Q; score 0-30, best). Serious subjective memory complaint was defined as MAC-Q score ≤15. Age, gender, body mass index, education level, number of comorbidities, history of stroke, objective cognitive disorders, functional autonomy, mood, serum concentrations of vitamin B12, TSH, albumin, and estimated glomerular filtration rate were used as potential confounders. Compared to participants without serious subjective memory complaint, those with serious subjective memory complaint (n=110) had a lower mean dietary vitamin K intake (298.0±191.8μg/day versus 393.8±215.2μg/day, P=0.005). Increased log dietary vitamin K intake was positively associated with the MAC-Q score used as a quantitative variable (fully adjusted β=0.79, P=0.031), and inversely with serious subjective memory complaint (fully adjusted OR=0.34, P=0.017). Increased dietary vitamin K intake was associated with fewer and less severe subjective memory complaint in older adults taking no vitamin K antagonists. These findings provide epidemiological data supporting future vitamin K replacement trials. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Predictors of Memory in Healthy Aging: Polyunsaturated Fatty Acid Balance and Fornix White Matter Integrity.

PubMed

Zamroziewicz, Marta K; Paul, Erick J; Zwilling, Chris E; Barbey, Aron K

2017-07-01

Recent evidence demonstrates that age and disease-related decline in cognition depends not only upon degeneration in brain structure and function, but also on dietary intake and nutritional status. Memory, a potential preclinical marker of Alzheimer's disease, is supported by white matter integrity in the brain and dietary patterns high in omega-3 and omega-6 polyunsaturated fatty acids. However, the extent to which memory is supported by specific omega-3 and omega-6 polyunsaturated fatty acids, and the degree to which this relationship is reliant upon microstructure of particular white matter regions is not known. This study therefore examined the cross-sectional relationship between empirically-derived patterns of omega-3 and omega-6 polyunsaturated fatty acids (represented by nutrient biomarker patterns), memory, and regional white matter microstructure in healthy, older adults. We measured thirteen plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acids, memory, and regional white matter microstructure in 94 cognitively intact older adults (65 to 75 years old). A three-step mediation analysis was implemented using multivariate linear regressions, adjusted for age, gender, education, income, depression status, and body mass index. The mediation analysis revealed that a mixture of plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acids is linked to memory and that white matter microstructure of the fornix fully mediates the relationship between this pattern of plasma phospholipid polyunsaturated fatty acids and memory. These results suggest that memory may be optimally supported by a balance of plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acids through the preservation of fornix white matter microstructure in cognitively intact older adults. This report provides novel evidence for the benefits of plasma phospholipid omega-3 and omega-6 polyunsaturated fatty acid balance on memory and underlying white matter microstructure.

Slow-oscillatory Transcranial Direct Current Stimulation Modulates Memory in Temporal Lobe Epilepsy by Altering Sleep Spindle Generators: A Possible Rehabilitation Tool.

PubMed

Del Felice, Alessandra; Magalini, Alessandra; Masiero, Stefano

2015-01-01

Temporal lobe epilepsy (TLE) is often associated with memory deficits. Given the putative role for sleep spindles memory consolidation, spindle generators skewed toward the affected lobe in TLE subjects may be a neurophysiological marker of defective memory. Slow-oscillatory transcranial direct current stimulation (sotDCS) during slow waves sleep (SWS) has previously been shown to enhance sleep-dependent memory consolidation by increasing slow-wave sleep and modulating sleep spindles. To test if anodal sotDCS over the affected TL prior to a nap affects sleep spindles and whether this improves memory consolidation. Randomized controlled cross-over study. 12 people with TLE underwent sotDCS (0.75 Hz; 0-250 μV, 30 min) or sham before daytime nap. Declarative verbal and visuospatial learning were tested. Fast and slow spindle signals were recorded by 256-channel EEG during sleep. In both study arms, electrical source imaging (ESI) localized cortical generators. Neuropsychological data were analyzed with general linear model statistics or the Kruskal-Wallis test (P or Z < 0.05), and neurophysiological data tested with the Mann-Whitney t test and binomial distribution test (P or Z < 0.05). An improvement in declarative (P = 0.05) and visuospatial memory performance (P = 0.048) emerged after sotDCS. SotDCS increased slow spindle generators current density (Z = 0.001), with a shift to the anterior cortical areas. Anodal sotDCS over the affected temporal lobe improves declarative and visuospatial memory performance by modulating slow sleep spindles cortical source generators. SotDCS appears a promising tool for memory rehabilitation in people with TLE. Copyright © 2015 Elsevier Inc. All rights reserved.

How landmark suitability shapes recognition memory signals for objects in the medial temporal lobes.

PubMed

Martin, Chris B; Sullivan, Jacqueline A; Wright, Jessey; Köhler, Stefan

2018-02-01

A role of perirhinal cortex (PrC) in recognition memory for objects has been well established. Contributions of parahippocampal cortex (PhC) to this function, while documented, remain less well understood. Here, we used fMRI to examine whether the organization of item-based recognition memory signals across these two structures is shaped by object category, independent of any difference in representing episodic context. Guided by research suggesting that PhC plays a critical role in processing landmarks, we focused on three categories of objects that differ from each other in their landmark suitability as confirmed with behavioral ratings (buildings > trees > aircraft). Participants made item-based recognition-memory decisions for novel and previously studied objects from these categories, which were matched in accuracy. Multi-voxel pattern classification revealed category-specific item-recognition memory signals along the long axis of PrC and PhC, with no sharp functional boundaries between these structures. Memory signals for buildings were observed in the mid to posterior extent of PhC, signals for trees in anterior to posterior segments of PhC, and signals for aircraft in mid to posterior aspects of PrC and the anterior extent of PhC. Notably, item-based memory signals for the category with highest landmark suitability ratings were observed only in those posterior segments of PhC that also allowed for classification of landmark suitability of objects when memory status was held constant. These findings provide new evidence in support of the notion that item-based memory signals for objects are not limited to PrC, and that the organization of these signals along the longitudinal axis that crosses PrC and PhC can be captured with reference to landmark suitability. Copyright © 2017 Elsevier Inc. All rights reserved.

Relationships between behavioral syndromes and cognitive domains in Alzheimer disease: the impact of mood and psychosis.

PubMed

Koppel, Jeremy; Goldberg, Terry E; Gordon, Marc L; Huey, Edward; Davies, Peter; Keehlisen, Linda; Huet, Sara; Christen, Erica; Greenwald, Blaine S

2012-11-01

Behavioral disturbances occur in nearly all Alzheimer disease (AD) patients together with an array of cognitive impairments. Prior investigations have failed to demonstrate specific associations between them, suggesting an independent, rather than shared, pathophysiology. The objective of this study was to reexamine this issue using an extensive cognitive battery together with a sensitive neurobehavioral and functional rating scale to correlate behavioral syndromes and cognitive domains across the spectrum of impairment in dementia. Cross-sectional study of comprehensive cognitive and behavioral ratings in subjects with AD and mild cognitive impairment. Memory disorders research center. Fifty subjects with AD and 26 subjects with mild cognitive impairment; and their caregivers. Cognitive rating scales administered included the Mini-Mental State Examination; the Modified Mini-Mental State Examination; the Boston Naming Test; the Benton Visual Retention Test; the Consortium to Establish a Registry for Alzheimer's Disease Neuropsychology Assessment; the Controlled Oral Word Test; the Wechsler Memory Scale logical memory I and logical memory II task; the Wechsler Memory Scale-Revised digit span; the Wechsler Adult Intelligence Scale-Revised digit symbol task; and the Clock Drawing Task together with the Clinical Dementia Rating Scale and the Neuropsychiatric Inventory. Stepwise regression of cognitive domains with symptom domains revealed significant associations of mood with impaired executive function/speed of processing (Δr = 0.22); impaired working memory (Δr = 0.05); impaired visual memory (Δr = 0.07); and worsened Clinical Dementia Rating Scale (Δr = 0.08). Psychosis was significantly associated with impaired working memory (Δr = 0.13). Mood symptoms appear to impact diverse cognitive realms and to compromise functional performance. Among neuropsychological indices, the unique relationship between working memory and psychosis suggests a possible common underlying neurobiology. 2012 American Association for Geriatric Psychiatry

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

PubMed

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

2018-01-15

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

A close relationship between verbal memory and SN/VTA integrity in young and older adults.

PubMed

Düzel, Sandra; Schütze, Hartmut; Stallforth, Sabine; Kaufmann, Jörn; Bodammer, Nils; Bunzeck, Nico; Münte, Thomas F; Lindenberger, Ulman; Heinze, Hans-Jochen; Düzel, Emrah

2008-11-01

Age-related dysfunction in dopaminergic neuromodulation is assumed to contribute to age-associated memory impairment. However, to date there are no in vivo data on how structural parameters of the substantia nigra/ventral tegmental area (SN/VTA), the main origin of dopaminergic projections, relate to memory performance in healthy young and older adults. We investigated this relationship in a cross-sectional study including data from the hippocampus and frontal white matter (FWM) and also assessing working memory span and attention. In groups of young and older adults matched for the variance of their age distribution, gender and body mass index, we observed a robust positive correlation between Magnetization Transfer Ratio (MTR)--a measure of structural integrity--of the SN/VTA and FWM with verbal learning and memory performance among older adults, while there was a negative correlation in the young. Two additional imaging parameters, anisotropy of diffusion and diffusion coefficient, suggested that in older adults FWM changes reflected vascular pathology while SN/VTA changes pointed towards neuronal loss and loss of water content. The negative correlation in the young possibly reflected maturational changes. Multiple regression analyses indicated that in both young and older adults, SN/VTA MTR explained more variance of verbal learning and memory than FWM MTR or hippocampal MTR, and contributed less to explaining variance of working memory span. Together these findings indicate that structural integrity in the SN/VTA has a relatively selective impact on verbal learning and memory and undergoes specific changes from young adulthood to older age that qualitatively differ from changes in the FWM and hippocampus.

Drawing enhances cross-modal memory plasticity in the human brain: a case study in a totally blind adult

PubMed Central

Likova, Lora T.

2012-01-01

In a memory-guided drawing task under blindfolded conditions, we have recently used functional Magnetic Resonance Imaging (fMRI) to demonstrate that the primary visual cortex (V1) may operate as the visuo-spatial buffer, or “sketchpad,” for working memory. The results implied, however, a modality-independent or amodal form of its operation. In the present study, to validate the role of V1 in non-visual memory, we eliminated not only the visual input but all levels of visual processing by replicating the paradigm in a congenitally blind individual. Our novel Cognitive-Kinesthetic method was used to train this totally blind subject to draw complex images guided solely by tactile memory. Control tasks of tactile exploration and memorization of the image to be drawn, and memory-free scribbling were also included. FMRI was run before training and after training. Remarkably, V1 of this congenitally blind individual, which before training exhibited noisy, immature, and non-specific responses, after training produced full-fledged response time-courses specific to the tactile-memory drawing task. The results reveal the operation of a rapid training-based plasticity mechanism that recruits the resources of V1 in the process of learning to draw. The learning paradigm allowed us to investigate for the first time the evolution of plastic re-assignment in V1 in a congenitally blind subject. These findings are consistent with a non-visual memory involvement of V1, and specifically imply that the observed cortical reorganization can be empowered by the process of learning to draw. PMID:22593738

Drawing enhances cross-modal memory plasticity in the human brain: a case study in a totally blind adult.

PubMed

Likova, Lora T

2012-01-01

In a memory-guided drawing task under blindfolded conditions, we have recently used functional Magnetic Resonance Imaging (fMRI) to demonstrate that the primary visual cortex (V1) may operate as the visuo-spatial buffer, or "sketchpad," for working memory. The results implied, however, a modality-independent or amodal form of its operation. In the present study, to validate the role of V1 in non-visual memory, we eliminated not only the visual input but all levels of visual processing by replicating the paradigm in a congenitally blind individual. Our novel Cognitive-Kinesthetic method was used to train this totally blind subject to draw complex images guided solely by tactile memory. Control tasks of tactile exploration and memorization of the image to be drawn, and memory-free scribbling were also included. FMRI was run before training and after training. Remarkably, V1 of this congenitally blind individual, which before training exhibited noisy, immature, and non-specific responses, after training produced full-fledged response time-courses specific to the tactile-memory drawing task. The results reveal the operation of a rapid training-based plasticity mechanism that recruits the resources of V1 in the process of learning to draw. The learning paradigm allowed us to investigate for the first time the evolution of plastic re-assignment in V1 in a congenitally blind subject. These findings are consistent with a non-visual memory involvement of V1, and specifically imply that the observed cortical reorganization can be empowered by the process of learning to draw.

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).

Presenilin-1 familial Alzheimer’s disease mutation alters hippocampal neurogenesis and memory function in CCL2 null mice

PubMed Central

Kiyota, Tomomi; Morrison, Christine M; Tu, Guihua; Dyavarshetty, Bhagyalaxmi; Weir, Robert A; Zhang, Gang; Xiong, Huangui; Gendelman, Howard E

2015-01-01

Aberrations in hippocampal neurogenesis are associated with learning and memory, synaptic plasticity and neurodegeneration in Alzheimer’s disease (AD). However, the linkage between them, β-amyloidosis and neuroinflammation is not well understood. To this end, we generated a mouse overexpressing familial AD (FAD) mutant human presenilin-1 (PS1) crossed with a knockout (KO) of the CC-chemokine ligand 2 (CCL2) gene. The PS1/CCL2KO mice developed robust age-dependent deficits in hippocampal neurogenesis associated with impairments in learning and memory, synaptic plasticity and long-term potentiation. Neurogliogenesis gene profiling supported β-amyloid independent pathways for FAD-associated deficits in hippocampal neurogenesis. We conclude that these PS1/CCL2KO mice are suitable for studies linking host genetics, immunity and hippocampal function. PMID:26112421