ABSTRACT
Steady-state visual evoked potential (SSVEP) has been widely used in the research of brain-computer interface (BCI) system in recent years. The advantages of SSVEP-BCI system include high classification accuracy, fast information transform rate and strong anti-interference ability. Most of the traditional researches induce SSVEP responses in low and middle frequency bands as control signals. However, SSVEP in this frequency band may cause visual fatigue and even induce epilepsy in subjects. In contrast, high-frequency SSVEP-BCI provides a more comfortable and natural interaction despite its lower amplitude and weaker response. Therefore, it has been widely concerned by researchers in recent years. This paper summarized and analyzed the related research of high-frequency SSVEP-BCI in the past ten years from the aspects of paradigm and algorithm. Finally, the application prospect and development direction of high-frequency SSVEP were discussed and prospected.
Subject(s)
Humans , Brain-Computer Interfaces , Evoked Potentials, Visual , AlgorithmsABSTRACT
BACKGROUND:The microvolt T-wave alternans (MTWA) is an important index for ventricular arrhythmias prediction and is a promising tool to evaluate non-invasively malignant ventricular arrhythmia and risk of sudden death.OBJECTIVE:To introduce a algorithm for detecting TWA using Poincare mapping method (PM),which is a technique for dynamics systems to display periodic behavior.METHODS:Samples series of beat to beat cycles were selected to prepare Poincare mapping to describe TWA distdbution.D_(twa),which denoted the sum distances between the origin to even and odd series,was used to present the presence and absence of TWA.RESULTS AND CONCLUSION:This algorithm was applied in MIT/BIH Arrhythmia database and European ECG ST-T database,and D_(twa) used for correlation analysis with V_(twa),which denoted TWA amplitude of Spectrum Method.The cross-correlation coefficient was γ= 0.984.The algorithm can identify the absence and presence of TWA accurately and provide idea for further study of TWA-PM.
ABSTRACT
OBJECTIVE: To observe the influence of arecoline (Ar) on human sperm motility in vitro. METHODS: 50 cases of normal human male sperm which had been screened were incubated in different concentration of Ar solution (10 ?g?mL-1,50 ?g?mL-1,100 ?g?mL-1),taking the optimized sperm as control group. After the incubation lasting 0.5,1,2 h, computer assisting sperm analysis system (CASA) was used to analyze the Mot, (a+b) PM,VCL and VSL of sperm. RESULTS: The Mot of sperm incubated in 10 ?g?mL-1 Ar solution for 1 h was significantly different from that of control group(P