Characteristic time of transition from write error to retention error in voltage-controlled magnetoresistive random-access memory

Voltage controlled magnetoresistive random access memory (VC MRAM) is a promising candidate for a future low-power high-density memory. The main causes of bit errors in VC MRAM are write error and retention error. As the size of the memory cell decreases, the data retention time decreases, which causes a transition from the write-error-dominant region to the retention-error-dominant region at a certain operating time. Here we introduce the characteristic time of the transition from the write-error-dominant region to the retention-error-dominant region and analyze how the characteristic time depends on the effective anisotropy constant, $K_{0}$. The characteristic time is approximately expressed as $t_{\rm c} = 2\, w\, \tau$, where $w$ is the write error rate, and $\tau$ is the relaxation time derived by Kalmkov [J. Appl. Phys. 96, (2004) 1138-1145]. We show that for large $K_{0}$, $t_{\rm c}$ increases with increase of $K_{0}$ similar to $\tau$. The characteristic time is a key parameter for designing the VC MRAM for the variety of applications such as machine learning and artificial intelligence.Comment: 6 pages, 5 figure

社会教育における生活記録の系譜

早大学位記番号:新7298早稲田大

Differences in Velopharyngeal Structure during Speech among Asians Revealed by 3-Tesla Magnetic Resonance Imaging Movie Mode

Objective. Different bony structures can affect the function of the velopharyngeal muscles. Asian populations differ morphologically, including the morphologies of their bony structures. The purpose of this study was to compare the velopharyngeal structures during speech in two Asian populations: Japanese and Thai. Methods. Ten healthy Japanese and Thai females (five each) were evaluated with a 3-Tesla (3 T) magnetic resonance imaging (MRI) scanner while they produced vowel-consonant-vowel syllable (/asa/). A gradient-echo sequence, fast low-angle shot with segmented cine and parallel imaging technique was used to obtain sagittal images of the velopharyngeal structures. Results. MRI was carried out in real time during speech production, allowing investigations of the time-to-time changes in the velopharyngeal structures. Thai subjects had a significantly longer hard palate and produced shorter consonant than Japanese subjects. The velum of the Thai participants showed significant thickening during consonant production and their retroglossal space was significantly wider at rest, whereas the dimensional change during task performance was similar in the two populations. Conclusions. The 3 T MRI movie method can be used to investigate velopharyngeal function and diagnose velopharyngeal insufficiency. The racial differences may include differences in skeletal patterns and soft-tissue morphology that result in functional differences for the affected structures

Principles of the magnetic resonance imaging movie method for articulatory movement : a review

Magnetic resonance imaging (MRI) has become a critical tool for dental examination. MRI has many advantages over radiographic examination methods, including the lack of a requirement for patient exposure and the ability to capture high-contrast images of various tissue and organ types. However, MRI also has several limitations, including long examination times and the existence of metallic or motion artifacts. A cardiac imaging method using cine sequences was developed in the 1990s. This technique allows for analysis of heart movement and functional blood flow. Moreover, this method has been applied in dentistry. Recent research involving 3T MRI has led to the achievement of a temporal resolution of <10 ms, surpassing the frame rate of typical video recording. The current review introduces the history and principles of the cine sequence method and its application to the oral and maxillofacial regions

Skeletal muscle mass and vitamin D

A clearer understanding of skeletal muscle mass (SMM) in middle-aged and elderly individuals is important for maintaining functionality. In the present study, age-related changes in SMM, the threshold of SMM with walking difficulty, intestinal nutrient absorption rate, and various serum factors were examined in Japanese populations of different ages. We used 24-h creatinine excretion as a measure of total body SMM. Age-related decreases in SMM, intestinal nutrient absorption rates, and serum 25-hydroxyvitamin D [25(OH)D] concentrations were significantly higher in women than in men. The cut-off values for SMM (kg), its percentage of total body weight (BW), the SMM index [SMMI] (Kg / m2), and creatinine height index (CHI) (%) in elderly individuals with walking difficulty were approximately 8-10 kg, 17-20% of BW, 3.9-4.6 kg / m2, and 44%, respectively. Serum 25(OH)D concentrations were closely associated with SMM (kg, % of BW, kg / m2) and CHI (%) as well as the intestinal absorption rates of nitrogen (%) and phosphorus (%) in women, but not in men. The present results demonstrate that vitamin D is an important metabolic factor in skeletal muscle, and contributes to the optimal management of skeletal muscle and the prevention of sarcopenia