Xu Cui

 

   



544 Stories by Xu Cui

QQ上遇到骗子了

昨天晚上QQ上,有一个高中同学给我打招呼。我就启动了视频聊天,那边也有视频,没有声音。我猜想他的话筒有问题了吧,这也正常。他问了常规性的问题,比如我在哪里啊,什么时候回来啊等等。我也回答了。让后他说他
2 0 sec read

What does a wavelet transform plot tell you?

Let’s say you collected some brain data (time series) using NIRS while the participants were performing a task (say finger tapping), and you use the wt function in the “Cross Wavelet and Wavelet Coherence Toolbox” (link dead. Please
15 1 min read

Hyperbolic discounting emerges from the scalar property of interval timing

Ten dollars today is more attractive than the same amount of money tomorrow and is consistent with the well known proverb, “a bird in the hand is worth two in the bush”. We all know that the value of a reward is discounted over time. How the value di
0 16 sec read

9 common mistakes in presentation and slides

When you give a presentation, try to avoid the following common mistakes: Too much text The best way to bore your audience.  Also, audience will start focusing and reading the text and ignore your talk. Read slides People read text faster than you. Y
0 32 sec read

Ric Elias: 3 things I learned while my plane crashed

Ric Elias is the CEO of Red Ventures, a marketing services company that grew out of Elias’ long experience in business. He had a front-row seat on Flight 1549, the plane that crash-landed in the Hudson River in New York in January 2009. What di
0 24 sec read

What is the probability that the sun will rise tomorrow?

Laplace introduced the sunrise problem in 18th century. With prior knowledge that the sun has risen N days in the past consecutively (not knowing the gravity rules etc), what is your confidence that the sun will rise tomorrow? Let p be the probabilit
1 1 min read

Handy programs to visualize NIRS data (5): plot2

Let’s say you have two correlated variables, x and y. You may have more then one data points with x=10 and y=5. But if you do a scatter plot all these data points of the same value will become a single dot. You may want to use circles with size
0 31 sec read

Handy programs to visualize NIRS data (4): wt

In case you need to visualize your time series in both time and frequency domain (or just frequency domain), you can use the wt (wavelet transform) function in the Cross Wavelet and Wavelet Coherence toolbox by Grinsted et al. I often find the color
0 33 sec read

Handy programs to visualize NIRS data (3): plotFFT

Sometimes you wish to know the spectrum of a time series. plotFFT is a handy function for this purpose. You instantly know the power of the signal at each frequency. Here is an example on how to use this function: figure; plotFFT(randn(1,1000)); Sour
0 11 sec read