On the relationship between imprint and reliability in Hf_(0.5)Zr_(0.5)O_(2) based ferroelectric random access memory

The detrimental effect of imprint,which can cause misreading problem,has hindered the application of ferroelectric HfO_(2).In this work,we present results of a comprehensive reliability evaluation of Hf_(0.5)Zr_(0.5)O_(2)-based ferroelectric random access memory.The influence of imprint on the retention and endurance is demonstrated.Furthermore,a solution in circuity is pro-posed to effectively solve the misreading problem caused by imprint.

Three dimensional finite element analysis of anatomic distal radius Nitinol memory connector treating distal radius fracture

Objective: To study the memory biomechanical character of anatomic distal radius Nitinol memory connector (DRMC) in treating distal radius fracture. Methods: Establishing three dimensional model and finite element analysis, we calculated the stress in and around the fracture faces when distal radius fracture was fixated with DRMC. Results: Axial holding stress produced by holding part of DRMC on distal radius was 14.66 MPa. The maximum stress of holding part was 40-70 MPa, the minimum stress was 3-7 MPa,and the stress of compression part was 20-40 MPa. Conclusion: The distribution of stress produced by DRMC around the fracture line is reasonable, and axial holding stress can help stabilize fracture during earlier period. The existence of longitudal compression and memory effect can transfer fixated disused section into developed section and enhance fracture healing.

Memory Training and Task Specificity in 90-99-Year-Old Seniors with Mild Cognitive Impairment

Managing memory deficits is a central problem among older adults with mild cognitive impairment (MCI). This study examined the effects of memory training on memory performance in an understudied “oldest-old” population ranging in age from 90 to 99 years. Eighteen mild to moderately cognitive-impaired older seniors, 90 years and older were recruited from memory clinics established in senior living communities. Treatment sessions took place, on average, twice weekly, for 55 minutes. Memory intervention included nineteen computer-based exercises customized to focus on memory loss. The specificity of memory training was very clear;memory training produced significant effects (F(3,51) = 2.81, p = 0.05) on memory performance, especially after 6 months of training, while other outcome measures showed no effects as predicted. Based on the results, it can be concluded that interventions targeting cognition and memory in the oldest-old MCI population can significantly improve memory function and reduce cognitive deficits.

Timed Petri Net Models of Shared-Memory Bus-Based Multiprocessors

In shared-memory bus-based multiprocessors, when the number of processors grows, the processors spend an increasing amount of time waiting for access to the bus (and shared memory). This contention reduces the performance of processors and imposes a limitation of the number of processors that can be used efficiently in bus-based systems. Since the multi-processor’s performance depends upon many parameters which affect the performance in different ways, timed Petri nets are used to model shared-memory bus-based multiprocessors at the instruction execution level, and the developed models are used to study how the performance of processors changes with the number of processors in the system. The results illustrate very well the restriction on the number of processors imposed by the shared bus. All performance characteristics presented in this paper are obtained by discrete-event simulation of Petri net models.

Nine Months of Memory Training Increases Cognistat Measured Memory in 79 - 89 Year-Old Mild Cognitively Impaired Individuals

The effects of a memory training paradigm on performance across multiple cognitive domains, measured via the Cognistat, in 70 - 89 year-old individuals with mild cognitive impairment (MCI), were examined. Memory training sessions were conducted on average twice weekly, for 55 minutes each session, for 9 months. Across the testing period, Cognistat-measured memory increased relative to performance in other cognitive domains. Additionally, performance on non-memory measures remained stable or declined. Thus, memory training in older adult, MCI individuals may result in improved memory, but not in improvement in other, non-memory, cognitive domains. Results replicate previous work examining “oldest-old” individuals ranging in age from 90 to 99 years old at the time of study start.

A Brief Report Investigating Subjective and Objective Memory Pre- and Post-Memory Training in 70- to 96-Year-Old Individuals with Mild Memory Deficit

Subjective memory impairment is a major complaint among older adults;however, research is conflicting regarding the relationship between subjective memory impairment and objectively measured memory loss. Here, individuals with mild memory impairment completed the memory subscale of the Cognistat as a measure of objective memory, and the Memory Complaint Questionnaire (MCQ) as a measure of subjective memory, prior to and following a 3-month memory training program. Results revealed that individuals with more, compared with fewer, memory complaints performed worse on the Cognistat. Additionally, increased Cognistat performance fol-lowing the memory training procedure was associated with decreased MCQ measured complaints. There was suggestive evidence that the memory training procedure improved memory, and thus future research is warranted. These findings imply that older, memory-impaired, adults, despite their memory impairment, are indeed able to judge, and may be accurately concerned with, the extent of their own memory loss. It should be noted that serious statistical limitations here indicate the need for replication to confirm the validity of the findings.

Set Programming Method and Performance Improvement of Phase Change Random Access Memory Arrays

A novel slow-down set waveform is proposed to improve the set performance and a 1 kb phase change random access memory chip fabricated with a 13nm CMOS technology is implemented to investigate the set performance by different set programming strategies based on this new set pulse. The amplitude difference （I1 - I2） of the set pulse is proved to be a crucial parameter for set programming. We observe and analyze the cell characteristics with different I1 - I2 by means of thermal simulations and high-resolution transmission electron microscopy, which reveal that an incomplete set programming will occur when the proposed slow-down pulse is set with an improperly high I1 - I2. This will lead to an amorphous residue in the active region. We also discuss the programming method to avoid the set performance degradations.

Emotion and Memory: Emotional Guidance for the History Education of the Nanjing Massacre

The emotion of hatred is a quite sensitive topic in the history education of the Nanjing Massacre.With what emotions should we study and remember this part of Chinese history? How can we achieve the vision of world peace by virtue of the history education of the Nanjing Massacre? All these questions are unavoidable in the practice of history education of the Nanjing Massacre.The emotion of hatred is based on biological instincts developed during our social evolution and it plays a significant part in constructing the historical memory of the Nanjing Massacre,which should never be underestimated.Therefore,rationally understanding the emotion of hatred in the history education of the Nanjing Massacre,and offering correct guidance,is of great significance for remembering and developing a correct view of our history,forming a proper world view,and achieving the fundamental goal of cherishing and maintaining peace.

The Differing Effects of Nociception and Pain Memory on Pain Thresholds in Participants with and without a History of Injury: A Pretest-Posttest Quasi Experimental Study

Purpose: Memory has been identified as an important protective feature to prevent future injury, but its role has yet to be ascertained. The current study aimed to determine whether there was a difference in pressure pain threshold (PPT) responses between participants with a prior history of injury of lower extremity injury (PSI) and those without (NPSI) when exposed to 1) experimental mechanical pain, 2) short-term memory recall of a painful stimulus, or 3) long-term memory of the pain associated with a prior injury. Subjects and Methods: The study used a pretest-posttest quasi-experimental design. A convenience sample of 59 pain-free participants was recruited from an urban university. Twenty-nine PSI and 30 NPSI were stratified into two groups based on their injury history with PPT values measured at baseline and immediately following each of the three experimental conditions. A repeated measure ANCOVA analysis was conducted for each condition to determine whether there was a difference in PPT responses between the two groups. Results: There was a statistically significant difference in PPT values between the two groups when exposed to experimental pain, F(1,57) = 6.010, p = 0.017, partial η2 = 0.095 and with long-term pain memory, F(1,57) = 4.886, p = 0.031, partial η2 = 0.079. There was no statistically significant difference between groups with short-term pain memory, F(1,57) = 3.925, p = 0.052, partial η2 = 0.064. Conclusions: These findings suggest that pain processing may be altered by pain memory, highlighting the role of experience and memory in the rehabilitation process.

3D magnetotelluric inversions with unstructured finite-element and limited-memory quasi-Newton methods

Traditional 3D Magnetotelluric(MT) forward modeling and inversions are mostly based on structured meshes that have limited accuracy when modeling undulating surfaces and arbitrary structures. By contrast, unstructured-grid-based methods can model complex underground structures with high accuracy and overcome the defects of traditional methods, such as the high computational cost for improving model accuracy and the difficulty of inverting with topography. In this paper, we used the limited-memory quasi-Newton(L-BFGS) method with an unstructured finite-element grid to perform 3D MT inversions. This method avoids explicitly calculating Hessian matrices, which greatly reduces the memory requirements. After the first iteration, the approximate inverse Hessian matrix well approximates the true one, and the Newton step(set to 1) can meet the sufficient descent condition. Only one calculation of the objective function and its gradient are needed for each iteration, which greatly improves its computational efficiency. This approach is well-suited for large-scale 3D MT inversions. We have tested our algorithm on data with and without topography, and the results matched the real models well. We can recommend performing inversions based on an unstructured finite-element method and the L-BFGS method for situations with topography and complex underground structures.

Test-Retest Reliability, Convergent Validity and Practice Effects of the RBANS in a Memory Clinic Setting: A Pilot Study

This pilot study examined the psychometric properties and clinical utility of a brief neuropsychological instrument (Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The test-retest reliability, practice effects and convergent validity of RBANS were examined in participants without objective cognitive impairment. The tests were administered at two time points at approximately a two weeks’ interval, with 30 cognitively intact participants with a mean age of 63.3 ± 5.8 years. Adequate test-retest reliabilities were found for RBANS subtests, index and total scale scores with significant gain scores in immediate memory and visuospatial function. The RBANS showed good convergent validity and the RBANS supplemented with executive and language measures (Colour Trails Test and 30-item modified Boston Naming Test, respectively) demonstrated excellent convergent validity with a formal neuropsychological battery. This pilot study has provided the preliminary evidence of reliability and convergent validity of the RBANS. Additionally, it also provides insight on the practice effects so that clinicians may assess significant changes in RBANS subtests and domain indexes for clinical practice.

Cross-sectional associations between cortical thiclmess and physical activity in older adults with spontaneous memory complaints:The MAPT Study

Background:Age-related changes in brain structure may constitute the starting point for cerebral function alteration.Physical activity(PA)demonstrated favorable associations with total brain volume,but its relationship with cortical thickness(CT)remains unclear.We investigated the cross-sectional associations between PA level and CT in community-dwelling people aged 70 years and older.Methods:A total of 403 older adults aged 74.8±4.0 years(mean±SD)who underwent a baseline magnetic resonance imaging examination and who had data on PA and confounders were included.PA was assessed with a questionnaire.Participants were categorized according to PA levels.Multiple linear regressions were used to compare the brain CT(mm)of the inactive group(no PA at all)with 6 active groups(growing PA levels)in 34 regions of interest.Results:Compared with inactive persons,people who achieved PA at a level of 1500-1999 metabolic equivalent task-min/week(i.e.,about6-7 h of brisk walking for exercise) and those who achieved it at 2000-2999 metabolic equivalent task-min/week(i.e.,8-11 h of brisk walking for exercise)had higher CT in the fusiform gyrus and the temporal pole.Additionally,dose-response associations between PA and CT were found in the fusiform gyrus(B=0.011,SE=0.004,adj.p=0.035),the temporal pole(B=0.026,SE=0.009,adj.p=0.048),and the caudal middle frontal gyrus,the entorhinal,medial orbitofrontal,lateral occipital,and insular cortices.Conclusion:This study demonstrates a positive association between PA level and CT in temporal areas such as the fusiform gyrus,a brain region often associated to Alzheimer’s disease in people aged 70 years and older.Future investigations focusing on PA type may help to fulfil remaining knowledge gaps in this field.

650 ps SET speed in Ge_(2)Sb_(2)Te_(5) phase change memory induced by TiO_(2) dielectric crystal plane

Crystallization speed of phase change material is one of the main obstaclesfor the application of phase change memory(PCM)as storage classmemory in computing systems,which requires the combination ofnonvolatility with ultra-fast operation speed in nanoseconds.Here,wepropose a novel approach to speed up crystallization process of the onlycommercial phase change chalcogenide Ge_(2)Sb_(2)Te_(5)(GST).By employingTiO_(2) as the dielectric layer in phase change device,operation speed of650 ps has been achieved,which is the fastest among existing representativePCM,and is comparable to the programing speed of commercialdynamic random access memory(DRAM).Because of its octahedralatomic configuration,TiO_(2) can provide nucleation interfaces for GST,thus facilitating the crystal growth at the determinate interface area.Ti–O–Ti–O four-fold rings on the(110)plane of tetragonal TiO_(2) is critical forthe fast-atomic rearrangement in the amorphous matrix of GST thatenables ultra-fast operation speed.The significant improvement of operationspeed in PCM through incorporating standard dielectric materialTiO_(2) in DRAM paves the way for the application of phase change memoryin high performance cache-type data storage.

miR-429-3p mediates memory decline by targeting MKP-1 to reduce surface GluA1- containing AMPA receptors in a mouse model of Alzheimer’s disease

Alzheimer ’s disease(AD) is a leading cause of dementia in the elderly.Mitogen-activated protein kinase phosphatase 1(MKP-1) plays a neuroprotective role in AD.However,the molecular mechanisms underlying the effects of MKP-1 on AD have not been extensively studied.MicroRNAs(miRNAs) regulate gene expression at the post-transcriptional level,thereby repressing mRNA translation.Here,we reported that the microRNA-429-3p(miR-429-3p) was significantly increased in the brain of APP23/PS45 AD model mice and N2AAPPAD model cells.We further found that miR-429-3p could downregulate MKP-1 expression by directly binding to its 3’-untranslated region(3’ UTR).Inhibition of miR-429-3p by its antagomir(A-miR-429) restored the expression of MKP-1 to a control level and consequently reduced the amyloidogenic processing of APP and Aβ accumulation.More importantly,intranasal administration of A-miR-429 successfully ameliorated the deficits of hippocampal CA1 long-term potentiation and spatial learning and memory in AD model mice by suppressing extracellular signal-regulated kinase(ERK1/2)-mediated GluAl hyperphosphorylation at Ser831 site,thereby increasing the surface expression of GluAl-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors(AMPARs).Together,these results demonstrate that inhibiting miR-429-3p to upregulate MKP-1 effectively improves cognitive and synaptic functions in AD model mice,suggesting that miR-429/MKP-1 pathway may be a novel therapeutic target for AD treatment.

Self-selective memristor-enabled in-memory search for highly efficient data mining

Similarity search,that is,finding similar items in massive data,is a fundamental computing problem in many fields such as data mining and information retrieval.However,for large-scale and high-dimension data,it suffers from high computational complexity,requiring tremendous computation resources.Here,based on the low-power self-selective memristors,for the first time,we propose an in-memory search(IMS)system with two innovative designs.First,by exploiting the natural distribution law of the devices resistance,a hardware locality sensitive hashing encoder has been designed to transform the realvalued vectors into more efficient binary codes.Second,a compact memristive ternary content addressable memory is developed to calculate the Hamming distances between the binary codes in parallel.Our IMS system demonstrated a 168energy efficiency improvement over all-transistors counterparts in clustering and classification tasks,while achieving a software-comparable accuracy,thus providing a low-complexity and low-power solution for in-memory data mining applications.

Advances in the understanding and enhancement of the human cognitive functions of learning and memory

Learning and memory are among the key cognitive functions that drive the human experience.As such,any defective condition associated with these cognitive domains could affect our navigation through everyday life.For years,researchers have been working toward having a clear understanding of how learning and memory work,as well as ways to improve them.Many advances have been made,as well as some challenges that have also been faced in the process.That notwithstanding,there are prospects with regards to the frontier of the enhancement of learning and memory in humans.This review article selectively highlights four broad areas of focus in research into the understanding and enhancement of learning and memory.Brain stimulation,effects of sleep,effects of stress and emotion,and synaptic plasticity are the main focal areas of this review,in terms of some pivotal research works,findings and theories.

Ferro-floating memory:Dual-mode ferroelectric floating memory and its application to in-memory computing

Various core memory devices have been proposed for utilization in future inmemory computing technology featuring high energy efficiency.Flash memory is considered as a viable choice owing to its high integration density,stability,and reliability,which has been verified by commercialized products.However,its high operating voltage and slow operation speed issues caused by the tunneling mechanism make its adoption in in-memory computing applications difficult.In this paper,we introduce a dual-mode memory device named“ferro-floating memory”,fabricated using van der Waals(vdW)materials(h-BN,MoS2,andα-In2Se3).The vdW material,α-In2Se3,acts as a polarization control layer for the ferroelectric memory operation and charge storage layer for the conventional flash memory operation.Compared to the tunnelingbased memory operation,the ferro-floating memory operates 1.9 and 3.3 times faster at 6.7 and 5.8 times lower operating voltages for programming and erasing operations,respectively.The dual-mode operation improves the linearity of conductance change by 5 times and the dynamic range by 48%through achieving conductance variation regions.Furthermore,we assess the effects of the variation in device operating voltage on neural networks and suggest a memory array operating scheme for maximizing the networks'performance through various training/inference simulations.

Experimental Effects of Acute Exercise on Cognitive-Based Short-Term Memory Improvement:A Meta-analysis of Repeated Measures Studies

The purpose of this meta-analysis was to evaluate the effects of acute exercise on short-term memory improvement.The computerized literature searches using electronic databases and examinations of reference lists from relevant studies yielded six studies meeting our inclusionary criteria.In a total of six studies,16 standardized regression coefficient effect sizes(ESs)were calculated to be meta-analyzed.The meta-analyses showed a statistically significant increase in short-term memory improvement across both the exercise and non-exercise control groups in trials 1-5[ES=0.96,95%CI(0.95,0.97),P<0.001].However,there was no significant subgroup difference between exercise and control groups(Q_(b)=0.40,df=1,P=0.53).Our meta-analytic review provides suggestive evidence that an acute bout of exercise prior to learning does not result in short-term memory improvement to a greater extent than a non-exercise control.Additional research is needed to further evaluate whether acute exercise enhances long-term memory via enhanced learning and/or post-learning mechanisms.

Deep machine learning unravels the structural origin of mid-gap states in chalcogenide glass for high-density memory integration

The recent development of three-dimensional semiconductor integration technology demands a key component-the ovonic threshold switching(OTS)selector to suppress the current leakage in the high-density memory chips.Yet,the unsatisfactory performance of existing OTS materials becomes the bottleneck of the industrial advancement.The sluggish development of OTS materials,which are usually made from chalcogenide glass,should be largely attributed to the insufficient understanding of the electronic structure in these materials,despite of intensive research in the past decade.Due to the heavy first-principles computation on disordered systems,a universal theory to explain the origin of mid-gap states(MGS),which are the key feature leading to the OTS behavior,is still lacking.To avoid the formidable computational tasks,we adopt machine learning method to understand and predict MGS in typical OTS materials.We build hundreds of chalcogenide glass models and collect major structural features from both short-range order(SRO)and medium-range order(MRO)of the amorphous cells.After training the artificial neural network using these features,the accuracy has reached~95%when it recognizes MGS in new glass.By analyzing the synaptic weights of the input structural features,we discover that the bonding and coordination environments from SRO and particularly MRO are closely related to MGS.The trained model could be used in many other OTS chalcogenides after minor modification.The intelligent machine learning allows us to understand the OTS mechanism from vast amount of structural data without heavy computational tasks,providing a new strategy to design functional amorphous materials from first principles.