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HAZEL SIVE: From your class exercise about restriction endonucleases, you should now be able to manipulate a piece of DNA to reveal blunt ends or sticky ends. You should know whether or not it's a 5-prime overhang or a 3-prime overhang. And this will set us up for the next topic I want to discuss, which is the question of the vector and ligation. Let's set the stage for this topic by looking back at the overall view that I gave you on cloning and using a gene of interest. We've talked about cutting the DNA now. And we haven't talked about how you exactly isolate your gene of interest. But we'll not worry about that for the moment. What we need to talk about now is the next step, how you're going to put your gene of interest into some kind of carrier DNA molecule that will allow it to replicate to high copy number. And the reason that this can occur is because of these things called vectors. A vector is really a virus that grows in bacteria. It may ...

hello I'm Mary Rutter from the Harvard Kent School in Charlestown and I teach kindergarten I use the star Festival CD-ROM as part of our unit on Japan and places in the world I also use it as a connection between Family Life Family roots and just to make the adventure more real we start our adventure on our airplane which the kids painted and designed and then we prepare for our trip by Kathy in our suitcases which of course are made of paper since kindergarten is the paper capital of the world inside the suitcase is a plain piece of white paper and the children are asked to draw the things that they think they will need on their trip and sometimes you get what they would need some children want to bring all the toys they own and one of the boys this year wanted to bring an ice cream machine unfortunately when he went through customs in Japan they would not let them in they made him take it out of his suitcase of course I am the Customs official um after we prepare we...

Let us now abstract from our previous example and provide a general definition of what a discrete time, finite state Markov chain is. First, central in the description of a Markov process is the concept of a state, which describes the current situation of a system we are interested in. For example, in the case of the checkout counter example, the number of customers in the queue provided the right level of information needed to define a useful state. Time is assumed to be discrete, that is, divided in discrete time steps. The system starts at time 0 in an initial state, and at each successive time step, the system goes from its current state to a next one chosen with some randomness. As a result, after n such transitions, the state of the system will be random, and so we can think of it as a random variable. Let Xn be this random variable. That is, Xn represents the state in which the system is after n transitions from an initial state in which it started to operate. As a...

Recall from our last video that it was impossible for us to use hierarchical clustering because of the high resolution of our image. So in this video, we will try to segment the MRI image using the k-means clustering algorithm. The first step in k-means clustering involves specifying the number of clusters, k. But how do we select k? Well, our clusters would ideally assign each point in the image to a tissue class. Or a particular substance, for instance, grey matter or white matter, and so on. And these substances are known to the medical community. So setting the number of clusters depends on exactly what you're trying to extract from the image. For the sake of our example, let's set the number of clusters here, k, to five. And since the k-means clustering algorithm starts by randomly assigning points to clusters, we should set the seed, so that we all obtain the same clusters. So let's type set.seed, and give it a value of 1. To run the k-means clustering a...