Displaying publications 41 - 60 of 275 in total

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  1. Bamatraf S, Hussain M, Aboalsamh H, Qazi EU, Malik AS, Amin HU, et al.
    Comput Intell Neurosci, 2016;2016:8491046.
    PMID: 26819593 DOI: 10.1155/2016/8491046
    We studied the impact of 2D and 3D educational contents on learning and memory recall using electroencephalography (EEG) brain signals. For this purpose, we adopted a classification approach that predicts true and false memories in case of both short term memory (STM) and long term memory (LTM) and helps to decide whether there is a difference between the impact of 2D and 3D educational contents. In this approach, EEG brain signals are converted into topomaps and then discriminative features are extracted from them and finally support vector machine (SVM) which is employed to predict brain states. For data collection, half of sixty-eight healthy individuals watched the learning material in 2D format whereas the rest watched the same material in 3D format. After learning task, memory recall tasks were performed after 30 minutes (STM) and two months (LTM), and EEG signals were recorded. In case of STM, 97.5% prediction accuracy was achieved for 3D and 96.6% for 2D and, in case of LTM, it was 100% for both 2D and 3D. The statistical analysis of the results suggested that for learning and memory recall both 2D and 3D materials do not have much difference in case of STM and LTM.
    Matched MeSH terms: Memory, Short-Term/physiology
  2. Barnacle GE, Tsivilis D, Schaefer A, Talmi D
    Psychophysiology, 2018 04;55(4).
    PMID: 29023754 DOI: 10.1111/psyp.13014
    Emotional enhancement of free recall can be context dependent. It is readily observed when emotional and neutral scenes are encoded and recalled together in a "mixed" list, but diminishes when these scenes are encoded separately in "pure" lists. We examined the hypothesis that this effect is due to differences in allocation of attention to neutral stimuli according to whether they are presented in mixed or pure lists, especially when encoding is intentional. Using picture stimuli that were controlled for semantic relatedness, our results contradicted this hypothesis. The amplitude of well-known electrophysiological markers of emotion-related attention-the early posterior negativity (EPN), the late positive potential (LPP), and the slow wave (SW)-was higher for emotional stimuli. Crucially, the emotional modulation of these ERPs was insensitive to list context, observed equally in pure and mixed lists. Although list context did not modulate neural markers of emotion-related attention, list context did modulate the effect of emotion on free recall. The apparent decoupling of the emotional effects on attention and memory, challenges existing hypotheses accounting for the emotional enhancement of memory. We close by discussing whether findings are more compatible with an alternative hypothesis, where the magnitude of emotional memory enhancement is, at least in part, a consequence of retrieval dynamics.
    Matched MeSH terms: Memory, Episodic*
  3. Battal Merlet L, Morel S, Blanchet A, Lockman H, Kostova M
    Psychiatry Res, 2014 Dec 30;220(3):752-9.
    PMID: 25240943 DOI: 10.1016/j.psychres.2014.08.034
    Schizophrenia is associated with severe episodic retrieval impairment. The aim of this study was to investigate the possibility that schizophrenia patients could improve their familiarity and/or recollection processes by manipulating the semantic coherence of to-be-learned stimuli and using deep encoding. Twelve schizophrenia patients and 12 healthy controls of comparable age, gender, and educational level undertook an associative recognition memory task. The stimuli consisted of pairs of words that were either related or unrelated to a given semantic category. The process dissociation procedure was used to calculate the estimates of familiarity and recollection processes. Both groups showed enhanced memory performances for semantically related words. However, in healthy controls, semantic relatedness led to enhanced recollection, while in schizophrenia patients, it induced enhanced familiarity. The familiarity estimates for related words were comparable in both groups, indicating that familiarity could be used as a compensatory mechanism in schizophrenia patients.
    Matched MeSH terms: Memory, Episodic*
  4. Bhuvanendran S, Bakar SNS, Kumari Y, Othman I, Shaikh MF, Hassan Z
    Sci Rep, 2019 10 10;9(1):14507.
    PMID: 31601902 DOI: 10.1038/s41598-019-50954-y
    Alzheimer's disease (AD) is the second most occurring neurological disorder after stroke and is associated with cerebral hypoperfusion, possibly contributing to cognitive impairment. In the present study, neuroprotective and anti-AD effects of embelin were evaluated in chronic cerebral hypoperfusion (CCH) rat model using permanent bilateral common carotid artery occlusion (BCCAO) method. Rats were administered with embelin at doses of 0.3, 0.6 or 1.2 mg/kg (i.p) on day 14 post-surgery and tested in Morris water maze (MWM) followed by electrophysiological recordings to access cognitive abilities and synaptic plasticity. The hippocampal brain regions were extracted for gene expression and neurotransmitters analysis. Treatment with embelin at the doses of 0.3 and 0.6 mg/kg significantly reversed the spatial memory impairment induced by CCH in rats. Embelin treatment has significantly protected synaptic plasticity impairment as assessed by hippocampal long-term potentiation (LTP) test. The mechanism of this study demonstrated that embelin treatment alleviated the decreased expression of BDNF, CREB1, APP, Mapt, SOD1 and NFκB mRNA levels caused by CCH rats. Furthermore, treatment with embelin demonstrated neuromodulatory activity by its ability to restore hippocampal neurotransmitters. Overall these data suggest that embelin improve memory and synaptic plasticity impairment in CCH rats and can be a potential drug candidate for neurodegenerative disease-related cognitive disorders.
    Matched MeSH terms: Spatial Memory/drug effects
  5. Binti Mohd Yusuf Yeo NA, Muthuraju S, Wong JH, Mohammed FR, Senik MH, Zhang J, et al.
    Brain Behav, 2018 09;8(9):e01093.
    PMID: 30105867 DOI: 10.1002/brb3.1093
    INTRODUCTION: Centella asiatica is an herbal plant that contains phytochemicals that are widely believed to have positive effects on cognitive function. The adolescent stage is a critical development period for the maturation of brain processes that encompass changes in physical and psychological systems. However, the effect of C. asiatica has not been extensively studied in adolescents. The aim of this study was therefore to investigate the effects of a C. asiatica extract on the enhancement of learning and memory in adolescent rats.

    METHODS: The locomotor activity, learning, and memory were assessed by using open field test and water T-maze test. This study also examined changes in neuronal cell morphology using cresyl violet and apoptosis staining. We also performed immunohistochemical study to analyse the expression of the glutamate AMPA receptor (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) GluA1 subunit and the GABA receptor (γ-Aminobutyric Acid) subtype GABAA α1 subunit in the hippocampus of the same animals.

    RESULTS: We found no significant changes in locomotor activity (p > 0.05). The water T-maze data showed that 30 mg/kg dose significantly (p  0.05). Histological data revealed no neuronal morphological changes. Immunohistochemical analysis revealed increased expression of the AMPA GluA1 receptor subunit but there was no effect on GABAA receptor α1 subunit expression in the CA1 and CA2 subregions of the hippocampus.

    CONCLUSIONS: The C. asiatica extract therefore improved hippocampus-dependent spatial learning and memory in a dose-dependent manner in rats through the GluA1-containing AMPA receptor in the CA1 and CA2 sub regions of the hippocampus.

    Matched MeSH terms: Memory/drug effects*
  6. Blackburn K
    Oral Hist Rev, 2009;36(2):231-52.
    PMID: 19999634
    The Pacific War and the Japanese Occupation were traumatic periods in the lives of people now over seventy years old in Malaysia and Singapore. This study traces why individuals interviewed for oral history of the Pacific War and the Japanese Occupation have often been able to tell stories of trauma without being overwhelmed by their reminiscences. It emphasizes that memories of traumatic experiences of the Pacific War and the Japanese Occupation in Malaysia and Singapore are mediated and eased by supportive social networks that are part of the interview subject's community. The individual's personal memories of traumatic war experiences are positioned in the context of the collective memory of the group and, thus, are made easier to recall. However, for individuals whose personal memories are at variance with the collective memory of the group they belong to, recalling traumatic experiences is more difficult and alienating as they do not have the support in their community. The act of recalling traumatic memories in the context of the collective memory of a group is particularly relevant in Malaysia and Singapore. These countries have a long history of being plural societies, where although the major ethnic groups -- the Malays, Chinese, and Indians -- have lived side by side peacefully, they have lived in culturally and socially separate worlds, not interacting much with the other groups. The self -- identity of many older people who lived through the Pacific War and the Japanese Occupation is inextricably bound up with their ethnicity. Oral history on war trauma strongly reflects these identities.
    Matched MeSH terms: Memory*
  7. Bonn GB
    Front Psychol, 2013;4:920.
    PMID: 24367349 DOI: 10.3389/fpsyg.2013.00920
    This paper examines the concept of free will, or independent action, in light of recent research in psychology and neuroscience. Reviewing findings in memory, prospection, and mental simulation, as well as the neurological mechanisms underlying behavioral control, planning, and integration, it is suggested in accord with previous arguments (e.g., Wegner, 2003; Harris, 2012) that a folk conception of free will as entirely conscious control over behavior should be rejected. However, it is argued that, when taken together, these findings can also support an alternative conception of free will. The constructive nature of memory and an integrative "default network" provide the means for novel and creative combinations of information, such as the imagining of counterfactual scenarios and alternative courses of action. Considering recent findings of extensive functional connections between these systems and those that subsume motor control and goal maintenance, it is argued that individuals have the capability of producing novel ideas and translating them into actionable goals. Although most of these processes take place beneath conscious awareness, it is argued that they are unique to the individual and thus, can be considered a form of independent control over behavior, or free will.
    Matched MeSH terms: Memory
  8. Butt UM, Letchmunan S, Hassan FH, Koh TW
    PLoS One, 2024;19(4):e0296486.
    PMID: 38630687 DOI: 10.1371/journal.pone.0296486
    Crime remains a crucial concern regarding ensuring a safe and secure environment for the public. Numerous efforts have been made to predict crime, emphasizing the importance of employing deep learning approaches for precise predictions. However, sufficient crime data and resources for training state-of-the-art deep learning-based crime prediction systems pose a challenge. To address this issue, this study adopts the transfer learning paradigm. Moreover, this study fine-tunes state-of-the-art statistical and deep learning methods, including Simple Moving Averages (SMA), Weighted Moving Averages (WMA), Exponential Moving Averages (EMA), Long Short Term Memory (LSTM), Bi-directional Long Short Term Memory (BiLSTMs), and Convolutional Neural Networks and Long Short Term Memory (CNN-LSTM) for crime prediction. Primarily, this study proposed a BiLSTM based transfer learning architecture due to its high accuracy in predicting weekly and monthly crime trends. The transfer learning paradigm leverages the fine-tuned BiLSTM model to transfer crime knowledge from one neighbourhood to another. The proposed method is evaluated on Chicago, New York, and Lahore crime datasets. Experimental results demonstrate the superiority of transfer learning with BiLSTM, achieving low error values and reduced execution time. These prediction results can significantly enhance the efficiency of law enforcement agencies in controlling and preventing crime.
    Matched MeSH terms: Memory, Long-Term
  9. C CL
    Explore (NY), 2011 Sep-Oct;7(5):300-13.
    PMID: 21907153 DOI: 10.1016/j.explore.2011.06.001
    The present article begins with an overview of how staff at the Center for Dialogue and Human Wellbeing (CDBH)-at Tecnológico de Monterrey University in Chihuahua, México-approach the process of conflict transformation. Specifically, it focuses on CDBH's strategies for dealing with historical injury, as well as the individual and collective trauma existing between and among communities engaged in ongoing conflict. It proceeds to examine how traumatic memories are stored in the mind/brain, and how trauma can impact on individuals and communities locked into a cycle of violence. The ensuing section provides an overview of the debate and the literature concerning psychotherapeutic and holistic-kinesthetic approaches for addressing individual and collective trauma. A hypothetical workshop is then offered to give readers a clear idea of how trauma work is actually carried out. The article ends by asking what approaches can best be applied for transforming collective trauma into sacred memories, which can become the driving force for a continuing commitment to building and sustaining peace among segments of communities that had previously been in conflict with one another.
    Matched MeSH terms: Memory
  10. Cacha LA, Ali J, Rizvi ZH, Yupapin PP, Poznanski RR
    J Integr Neurosci, 2017;16(4):493-509.
    PMID: 28891529 DOI: 10.3233/JIN-170038
    Using steady-state electrical properties of non-ohmic dendrite based on cable theory, we derive electrotonic potentials that do not change over time and are localized in space. We hypothesize that clusters of such stationary, local and permanent pulses are the electrical signatures of enduring memories which are imprinted through nonsynaptic plasticity, encoded through epigenetic mechanisms, and decoded through electrotonic processing. We further hypothesize how retrieval of an engram is made possible by integration of these permanently imprinted standing pulses in a neural circuit through neurotransmission in the extracellular space as part of conscious recall that acts as a guiding template in the reconsolidation of long-term memories through novelty characterized by uncertainty that arises when new fragments of memories reinstate an engram by way of nonsynaptic plasticity that permits its destabilization. Collectively, these findings seem to reinforce this hypothesis that electrotonic processing in non-ohmic dendrites yield insights into permanent electrical signatures that could reflect upon enduring memories as fragments of long-term memory engrams.
    Matched MeSH terms: Memory; Memory, Long-Term
  11. Calleja MO, Willoughby AR
    Atten Percept Psychophys, 2023 Feb;85(2):293-300.
    PMID: 36596986 DOI: 10.3758/s13414-022-02634-9
    Previous experiments investigating visual search have shown that distractors that are semantically related to a search target can capture attention and slow the search process. In two experiments, we examine if distractors exactly matching, or semantically related to, search-irrelevant information held in working memory (WM) can also influence visual search while ruling out potential effects of color similarity. Participants first viewed and memorized an image of an everyday object, then they determined if a target item was present or absent in a two-object search array. On exact-match trials, the memorized object appeared as a distractor; on semantic-match trials, an object semantically related to the memorized object appeared as a distractor. Both exact-match and semantic-match distractors slowed search when the target was present in the search array. Our findings extend previous findings by demonstrating WM-driven attentional guidance by complex objects rather than simple features. The results also suggest that visual search can be influenced by distractors sharing only semantic features with a search-irrelevant, but active, WM representation.
    Matched MeSH terms: Memory, Short-Term*
  12. Careena S, Sani D, Tan SN, Lim CW, Hassan S, Norhafizah M, et al.
    PMID: 30186358 DOI: 10.1155/2018/9318789
    Cognitive disability is a common feature associated with a variety of neurological conditions including Alzheimer's Disease (AD), Parkinson's Disease (PD), brain injury, and stroke. Emerging evidence has demonstrated that neuroinflammation plays an important role in the development of cognitive impairment. Current available therapies are relatively ineffective in treating or preventing cognitive disabilities, thus representing an important, unfulfilled medical need. Hence, developing potential treatment is one of the major areas of research interest. Edible bird's nests (EBN) are nests formed by swiftlet's saliva containing sialic acid, which is believed to improve brain function. This present study was embarked upon to evaluate the learning and memory enhancing potential effect of EBN by using Morris water maze test in a Wistar rat model of LPS-induced neuroinflammation. LPS elicited cognitive impairment in the rats by significantly increasing the escape latency while decreasing the number of entries in the probe trial, which are coupled with increased production of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and oxidative markers (ROS and TBARS) in the hippocampus. Treatment with EBN (125 mg/kg, 250 mg/kg, and 500 mg/kg; p.o.) effectively reversed the effect of LPS on escape latency and probe trial and, in addition, inhibited the LPS-induced upregulation of proinflammatory cytokines and oxidative markers. These findings are suggestive that there is existence of neuroprotective effect contained inside the edible bird's nest.
    Matched MeSH terms: Memory
  13. Chai WJ, Abd Hamid AI, Abdullah JM
    Front Psychol, 2018;9:401.
    PMID: 29636715 DOI: 10.3389/fpsyg.2018.00401
    Since the concept of working memory was introduced over 50 years ago, different schools of thought have offered different definitions for working memory based on the various cognitive domains that it encompasses. The general consensus regarding working memory supports the idea that working memory is extensively involved in goal-directed behaviors in which information must be retained and manipulated to ensure successful task execution. Before the emergence of other competing models, the concept of working memory was described by the multicomponent working memory model proposed by Baddeley and Hitch. In the present article, the authors provide an overview of several working memory-relevant studies in order to harmonize the findings of working memory from the neurosciences and psychological standpoints, especially after citing evidence from past studies of healthy, aging, diseased, and/or lesioned brains. In particular, the theoretical framework behind working memory, in which the related domains that are considered to play a part in different frameworks (such as memory's capacity limit and temporary storage) are presented and discussed. From the neuroscience perspective, it has been established that working memory activates the fronto-parietal brain regions, including the prefrontal, cingulate, and parietal cortices. Recent studies have subsequently implicated the roles of subcortical regions (such as the midbrain and cerebellum) in working memory. Aging also appears to have modulatory effects on working memory; age interactions with emotion, caffeine and hormones appear to affect working memory performances at the neurobiological level. Moreover, working memory deficits are apparent in older individuals, who are susceptible to cognitive deterioration. Another younger population with working memory impairment consists of those with mental, developmental, and/or neurological disorders such as major depressive disorder and others. A less coherent and organized neural pattern has been consistently reported in these disadvantaged groups. Working memory of patients with traumatic brain injury was similarly affected and shown to have unusual neural activity (hyper- or hypoactivation) as a general observation. Decoding the underlying neural mechanisms of working memory helps support the current theoretical understandings concerning working memory, and at the same time provides insights into rehabilitation programs that target working memory impairments from neurophysiological or psychological aspects.
    Matched MeSH terms: Memory Disorders; Memory, Short-Term
  14. Cheku Nurul Hasmaria Cheku Yahaya, Md Gapar Md Johar
    MyJurnal
    This paper aims to presents the implementation of Organizational Memory Information System (OMIS) framework in managing knowledge in organization. OMIS providing a way for organization to leveraging tacit knowledge in capturing, codifying, storing and transferring knowledge. Every year data, information and knowledge had increased then becomes wasted memories due to the retirement, replacement and resignation of staff. This can have a great impact if the knowledge is not used wisely for future purpose. This could give great impact when it is not used wisely. Organization become more efficient and competitive if they used the collections of memory in the form of collected data, information, and knowledge. Organizations which are not efficient will do the process, and study the same repeatedly. Implementation of this framework is a good way to increase effectiveness of knowledge sharing in university. But some knowledge is hard to capture especially tacit knowledge. Many organizations attempt to capture tacit knowledge and codify it so that it can be shared around the organization for greater value. So this paper is mainly focused on implementation of Organizational Memory Information System (OMIS) framework in order to manage knowledge more centralized and organized in organization.
    Matched MeSH terms: Memory
  15. Chen S, Lin Z, Tan KL, Chen R, Su W, Zhao H, et al.
    Front Psychiatry, 2020;11:564843.
    PMID: 33061920 DOI: 10.3389/fpsyt.2020.564843
    Butyrylcholinesterase (BChE) efficiently hydrolyzes acetylcholine (ACh) at high concentrations when acetylcholinesterase (AChE) is substrate-inhibited. Recent studies have shown that BChE also has a function that is independent of ACh, but it has not been fully explored. Low BChE expression is accompanied with higher stress-induced aggression and ghrelin levels in stress models, and BChE knockout mice exhibit cognitive and memory impairments. However, the role of BChE in posttraumatic stress disorder (PTSD) remains unclear. In the present study, we investigated the role of BChE in contextual fear memory and its regulatory effect on the expression of factors related to the glutamate (Glu)-glutamine (Gln) cycle via knockdown studies. We used AAVs and lentiviruses to knockdown BChE expression in the mouse hippocampal CA1 region and C8D1A astrocytes. Our behavioral data from those mice injected with AAV-shBChE in the hippocampal CA1 region showed strengthened fear memory and increased dendritic spine density. Elevated Glu levels and glutamine synthetase (GS) enzyme activity were detected in contextual fear conditioned-BChE knockdown animals and astrocytes. We observed that an AAV-shBChE induced lowering of BChE expression in the hippocampus CA1 region enhanced contextual fear memory expression and promoted the astrocytic Glu-Gln cycle but did not elevate ACh-hydrolyzing activity. This study provides new insight into the regulatory role of BChE in cognition and suggests potential target for stress-related psychiatric disorder such as PTSD where patients experience fear after exposure to severe life-threatening traumatic events.
    Matched MeSH terms: Memory
  16. Cherian SB, Bairy KL, Rao MS
    Indian J Exp Biol, 2009 Nov;47(11):893-9.
    PMID: 20099462
    With a view to examine the effect of chronic maternal stress on cognitive function in the offspring during young age, pregnant Wistar rats were subjected to restraint stress from embryonic day 11 till delivery. Male and female pups born to these stressed rats were subjected to passive avoidance test on postnatal day 30 and 31. Results were compared with rats of the same age and sex born to control mothers, which were not stressed. The results showed that prenatal maternal restraint stress impairs the memory retention during young age in both sexes. The memory retention deficit induced by maternal restraint stress was evident in the decreased latency to enter the dark compartment of passive avoidance apparatus by the rats born to stressed mothers. The observed behavioral deficit may be due to the insult of stress on the developing hippocampus, a structure of the brain concerned with learning and memory. The results suggest that prolonged prenatal stress leads to long lasting malfunction in the behavioral development during young age in both male and female young rats. However when compared to their respective stress naïve controls, it seems evident that prenatal restraint stress has a less effect on females which could be due to their oesterogenic effects. These data reinforce the view that prenatal stress affects cognitive development in a sex-specific manner.
    Matched MeSH terms: Memory Disorders/etiology*
  17. Chidambaram SB, Pandian A, Sekar S, Haridass S, Vijayan R, Thiyagarajan LK, et al.
    Environ Toxicol, 2016 Dec;31(12):1955-1963.
    PMID: 26434561 DOI: 10.1002/tox.22196
    PURPOSE: Present study was undertaken to evaluate the antiamnesic effect of Sesamum indicum (S. indicum) seeds (standardized for sesamin, a lignan, content) in scopolamine, a muscarinic antagonist intoxicated mice.

    METHODS: Male Swiss albino mice (18-22 g bw) were pretreated with methanolic extract of sesame seeds (MSSE) (100 and 200 mg/kg/day, p.o) for a period of 14 days. Scopolamine (0.3 mg/kg, i.p.) was injected on day 14, 45 ± 10 min after MSSE administration. Antiamnesic effect of MSSE was evaluated using step-down latency (SDL) on passive avoidance apparatus and transfer latency (TL) on an elevated plus maze. To unravel the mechanism of action, we examined the effects of MSSE on the genes such as acetyl cholinesterase (AChE), muscarinic receptor M1 subtype (mAChRM1 ), and brain derived neurotrophic factor (BDNF) expression within hippocampus of experimental mice. Further, its effects on bax and bcl-2 were also evaluated. Histopathological examination of hippocampal CA1 region was performed using cresyl violet staining.

    RESULTS: MSSE treatment produced a significant and dose dependent increase in step down latency in passive avoidance test and decrease in transfer latency in elevated plus maze in scopolamine intoxicated injected mice. MSSE down-regulated AChE and mAChRM1 and up-regulated BDNF mRNA expression. Further, it significantly down-regulated the bax and caspase 3 and up-regulated bcl-2 expression in scopolamine intoxicated mice brains. Mice treated with MSSE showed increased neuronal counts in hippocampal CA1 region when compared with scopolamine-vehicle treated mice.

    CONCLUSION: Sesame seeds have the ability to interact with cholinergic components involved in memory function/restoration and also an interesting candidate to be considered for future cognitive research. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1955-1963, 2016.

    Matched MeSH terms: Memory/drug effects*
  18. Chin KY, Tay SS
    Nutrients, 2018 Jul 09;10(7).
    PMID: 29987193 DOI: 10.3390/nu10070881
    Alzheimer’s disease (AD) is plaguing the aging population worldwide due to its tremendous health care and socioeconomic burden. Current treatment of AD only offers symptomatic relief to patients. Development of agents targeting specific pathologies of AD is very slow. Tocotrienol, a member of the vitamin E family, can tackle many aspects of AD, such as oxidative stress, mitochondrial dysfunction and abnormal cholesterol synthesis. This review summarizes the current evidence on the role of tocotrienol as a neuroprotective agent. Preclinical studies showed that tocotrienol could reduce oxidative stress by acting as a free-radical scavenger and promoter of mitochondrial function and cellular repair. It also prevented glutamate-induced neurotoxicity in the cells. Human epidemiological studies showed a significant inverse relationship between tocotrienol levels and the occurrence of AD. However, there is no clinical trial to support the claim that tocotrienol can delay or prevent the onset of AD. As a conclusion, tocotrienol has the potential to be developed as an AD-preventing agent but further studies are required to validate its efficacy in humans.
    Matched MeSH terms: Memory/drug effects
  19. Chin WC, Zaidi Isa, Abu Hassan Shaari Mohd Nor
    This study investigates the value-at-risk (VaR) using nonlinear time-varying volatility (ARCH model) and extreme-value-theory (EVT) methodologies. Similar VaR estimation and prediction are observes under the EVT and heavy-tailed long-memory ARCH approaches. The empirical results evidence the EVT-based VaR are more accurate but only at higher quantiles. It is also found that EVT approach is able to provide a convenient framework for asymmetric properties in both the lower and upper tails which implies that the risk and reward are not equally likely for the short- and long-trading positions in Malaysian stock market.
    Matched MeSH terms: Memory
  20. Chin WC, Zaidi Isa, Abu Hassan Shaari Mohd. Nor
    Sains Malaysiana, 2008;37:233-237.
    This article study the influences of structural break to the fractionally integrated time-varying volatility model in Malaysian stock markets from year 1996 to 2006. A fractionally integrated autoregressive conditional heteroscedastic (FIGARCH) model combines with sudden changes of volatility is develops to study the possibility of structural change in Asian financial crisis and currency crisis. Our empirical results evidence substantially reduction in long memory clustering volatility after the inclusion of sudden changes in the volatility. Finally, the estimation, diagnostic and model selection evaluations indicate that the fractionally integrated model with structural change is out-performed compared to the standard model.
    Matched MeSH terms: Memory
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