Dynamics of magnetic vortex core switching in nanometer-scale permalloy disk, having a single vortex ground state, was investigated by micromagnetic modeling. When an in-plane magnetic field pulse with an appropriate strength and duration is applied to the vortex structure, additional two vortices, i.e., a circular-and an anti-vortex, are created near the original vortex core. Sequentially, the vortex-antivortex pair annihilates. A spin wave is created at the annihilation point and propagated through the entire element; the relaxed state for the system is the single vortex state with a switched vortex core.

No abstract

Neuromorphic computing has the potential to accelerate high performance parallel and low power in-memory computation, artificial intelligence, and adaptive learning. Despite emulating the basic functions of biological synapses well, the existing artificial electronic synaptic devices have yet to match the softness, robustness, and ultralow power consumption of the brain. Here, we demonstrate an all-inorganic flexible artificial synapse enabled by a ferroelectric field effect transistor based on mica. The device not only exhibits excellent electrical pulse modulated conductance updating for synaptic functions but also shows remarkable mechanical flexibility and high temperature reliability, making robust neuromorphic computation possible under external disturbances such as stress and heating. Based on its linear, repeatable, and stable long-term plasticity, we simulate an artificial neural network for the Modified National Institute of Standards and Technology handwritten digit recognition with an accuracy of 94.4%. This work provides a promising way to enable flexible, low-power, robust, and highly efficient neuromorphic computation that mimics the brain.

No abstract

Flexible ferroelectric field effect transistors (FeFETs) with multiple functionalities and tunable properties are attractive for low power sensing, nonvolatile data storage, as well as emerging memristor applications such as artificial synapses, though the state-of-art flexible FeFETs based on organic materials possess low polarization, large coercivity, and high operating voltage, and suffer from poor thermal stability. Here, developed is an all-inorganic flexible FeFET based on epitaxial Pb(Zr 0.1 Ti 0.9 )O 3 /ZnO heterostructure on a mica substrate, which not only operates under a small voltage (±6 V) and thus consumes low power with an excellent on/off ratio of 10 4 as well as retention characteristics, but also shows robust FeFET performance under large bending deformation (4 mm), extended bending cycling (500 cycles), and high temperature operation at 200 °C. Importantly, the FeFET characteristics depend on temperature, but not on temperature history, critical for operation under repeated thermal loading. The excellent mechanical flexibility and functional robustness of the flexible FeFET originate from the unique van der Waals bonded layer structure of mica, facilitating a small bending radius yet modest strain. This work demonstrates the great promise of mica as a universal platform to integrate complicated functional devices for flexible electronics, especially under harsh environment.

We investigated the influence of the magnetic field pulse parameters and the size of the Fe element to the vortex core switching by micromagnetic modeling. When the magnetic field pulse with an appropriate strength and duration is applied to 30nm thick Fe circular disks with diameters between 100nm and 1μm, the vortex configuration is perturbed away from the equilibrium state, and the circular symmetric distribution of the in-plane magnetization around the vortex core deforms. This leads to the creation of a new vortex core with the opposite polarity and an antivortex. With increasing time, the vortex-antivortex pair annihilates. As a result of the annihilation, a single vortex core with opposite polarity remains and a vortex core switch is realized. The process of core switching, however, strongly depends on the amplitude and duration of the magnetic pulse.

Background evidence concerning the relationship between sleep quality and cognitive impairment is limited and inconsistent. Objective to examine the association of sleep quality with memory impairment and poor cognitive function in a large sample of older Chinese. Methods 15,246 participants aged 50+ years of the Guangzhou Biobank Cohort Study who attended the second physical examination from 2008 to 2012 were included. Sleep quality was assessed using Pittsburgh Sleep Quality Index (PSQI), and cognitive performance was assessed using both Delayed Word Recall Test (DWRT) and Mini-Mental State Examination (MMSE). Memory impairment was defined by DWRT score < 4 and poor cognitive function by MMSE score < 25. Results after adjusting for potential confounders, lower habitual sleep efficiency was associated with a higher risk of memory impairment and poor cognitive function with a dose-response pattern (both P for trend <0.001). The adjusted odds ratio (OR, 95% confidence interval (CI)) for poor cognitive function in those with the sleep efficiency of 75–85%, 65–75% and <65%, versus ≥85%, was 1.31 (1.12–1.53), 1.41 (1.16–1.73) and 1.33 (1.09–1.63), respectively. No association of the global PSQI score with memory impairment or poor cognitive function was found. Conclusions in older Chinese people, lower habitual sleep efficiency was associated with a higher risk of memory impairment and poorer cognitive function.

Early detection of oral precancerous and malignant lesions is still a diagnostic challenge for most of clinicians, and ideal adjuncts for detection of these lesions are currently unavailable. Our preliminary study has indicated that rose bengal (RB) staining might have the potency as a diagnostic aid; however, its clinical significance and reliability in hospital-based population are still not clear. In the present study, we investigated the efficacy of RB staining in detection of oral precancerous and malignant lesions. RB staining was conducted in 132 patients, and staining results were determined by a 4-graded shade guide, which had been quantitatively measured in the 1976 CIEL*a*b* space by instrumental colorimetry. Histological examination was performed in 128 of 132 patients after RB staining. The sensitivity and specificity to detect epithelial dysplasia (DP) and oral squamous cell carcinoma were 93.9 and 73.7%, respectively. The positive and negative likelihood ratios were 3.570 and 0.082, respectively. Moreover, RB staining seemed promising to detect DP in oral leukoplakia, lichen planus and leukokeratosis. In this study, 5 of 6 DP or oral squamous cell carcinoma were identified by RB staining before histological examination. In conclusion, RB staining may be a valuable diagnostic test in detection of oral precancerous and malignant lesions. ' 2007 Wiley-Liss, Inc.Key words: rose bengal; early detection; oral squamous cell carcinoma; epithelial dysplasia; colorimetry It was estimated that cancer of the head and neck, including all oral, laryngeal and pharyngeal sites, is the fifth most common cancer, accounting for about 615,000 new cases annually. 1 About 40% of head and neck malignancies are known to be squamous cell carcinomas (SCCs) arising in the oral cavity, 1 and it has one of the lowest survival rates, 50%, within a 5-year period. 2 These survival rates have remained relatively unchanged for the past 3 decades, probably because of late recognition of the disease. Consequently, emphasis has been placed on early detection and diagnosis of precancerous lesions and early stages of oral cancer. Nevertheless, oral epithelial lesions have many different presentations, such that clinical variants require diagnostic tests beyond visual examination to obtain definitive diagnoses. [3][4][5] Adjuncts for detection of lesions and selection of biopsy sites include toluidine blue staining, exfoliative cytology and other recently emerging techniques. But because of various reasons, such as less effective when used in oral precancerous lesions, inevitably bewildered when equivocal results occurred, 4,6 these techniques have not been accepted all over the world at present.Rose bengal (RB), the 4,5,6,7-tetrachloro-2 0 ,4 0 ,5 0 ,7 0 -tetraiododerivative of fluorescein, has been widely used to diagnose various ocular surface disorders. 7 It has been believed to stain desquamated ocular epithelial cells, dead or degenerated cells but not healthy epithelial cells, or wherever there is poor protection of the surface e...