Good morning Hank, it's Tuesday October 27th, 2015, a significant day in YouTube history because tomorrow YouTube Red launches, which may or may not change online video forever. Also, you will notice that I trimmed my beard because Nerdfighters had started to refer to it as the underpuff. Right, but YouTube Red, so until now, YouTube has always been like network television and radio before it and advertising-supported medium. Now, there are obvious advantages to this. Creators get paid, unlike most social media sites, and also it's free for viewers. But there are also disadvantages. Ad-supported media tends to seek the broadest possible audience because what advertisers really want is the most possible eyeballs to see their message. And with Ad-supported media, we generally end up with stuff that lots of people will watch over stuff that like some people will really, really love. You know, like broad-spectrum shows like Law & Order can succeed, but niche shows like Firefly or Arrested Development can't. Also, I know you probably don't think you're affected by advertising, but you are. To quote Emily Nussbaum's brilliant recent essay on what advertising has done to television, our comfort with being sold to may look like savvy, but it feels like innocence. I mean, hey, corporations know a lot more about what influences my consumptive habits than I do. That phenomenon has been studied extensively, sources in the doodly-doo, where you can also find a link to Nussbaum's essay. So, okay, having acknowledged my advertising ambivalence, let's explore my YouTube Red ambivalence. Here's the idea. For $10 a month, you can add free YouTube, offline watching, and all the music you want. So it's like Spotify plus ad-free YouTube. Also, there will be some new original shows from people like PewDiePie and other YouTubers that are only available to YouTube Red subscribers. So like the question I've heard the most from people is, is this good for creators? Which speaks a lot to how awesome the YouTube viewership is. The answer to that question is, yeah? Some portion of that $10 per month will go to the YouTubers you watch. I don't really know how much yet. And per viewer, YouTube Red will generate more money for creators than advertising. That said, it's like a thousand times more valuable to support a creator through Patreon or through buying merch than through either YouTube Red or advertising. Actually, it's not like a thousand. It is a thousand times better, maybe even two thousand. The best way to financially support creators you care about remains directly. So I don't think that's the reason to get YouTube Red, but I do think there are good reasons. I mean, I'm gonna get it. But anyway, Hank, here's what concerns me the most. Will YouTube Red create two classes of YouTube viewers, those who can pay and those who can't? One of the things that makes YouTube really special is that at its best, it's a flat platform for both creators and audiences, right? Like, I have the same capacity to reach an audience sitting here in my basement as a major media company does. And on the audience side, if you have access to a device and the internet, all of YouTube is available to you. Now that started to change a little on the creator side of things, as production values have risen, but I really don't want it to change on the audience side. Like, YouTube is gonna remain essentially the same for everyone who doesn't become a Red subscriber. The only difference is that you won't have access to these new, high-budget, original shows. Like PewDiePie is making a horror show with the producers of The Walking Dead, and that sounds awesome. And it would also be completely impossible in an advertising-supported medium. But Nerdfighters, I wonder if you would be excited or scared if your favorite creators did such a show. I'm asking for a friend, by the way. Like, it allows creators to have the kinds of budgets you can't have for advertising-supported projects, but on the other hand, it limits the number of people who can actually see the thing to Red subscribers. In short, Hank, I don't know how to feel about all this stuff. We've always been uncomfortable with advertising, and it's nice to see YouTube moving away from sole reliance upon it. I think YouTube Red will be a good option for a lot of people without harming the experience of the majority who stick with ad-supported YouTube. In general, I think that subscriptions make viewers more powerful and brands slightly less so, and that's good news. But I'm not sure I want YouTube to look like cable TV when it grows up. I want YouTube to be driven by the stuff that makes it interesting, by passionate fan communities who do awesome stuff together, by the direct relationship between creator and audience. I mean, at its best, YouTube isn't something you watch. It's something you're part of. So the question becomes, is YouTube Red a step toward that promised land or away from it? I don't know. That's not a rhetorical question. I look forward to continuing the conversation in comments, Nerdfighters. Hank, I'll see you tomorrow. Nope, Friday. Gosh, I was so in Brotherhood 2.0 mode.


Alright, one of the things that keeps people from creating content consistently is that they think they need to do more research. And maybe once you start writing an article or planning a video. At that point, you do some research. And the problem is, you realize as you do research that there's always more research to do. This is a real issue for a lot of us who care about the quality of information that we put out. Now, I want to make a guess. I really believe this is true, which is that you already know enough to be helpful for your audience that if you can write a new article once a week for an entire year and not do a minute more of research. And I think it is actually really good practice to not do any research before you create content. Because the stories and the lessons that are already within your life experience needs to be mined and shared so that it can benefit your audience. Rather than always depending on external information to validate what you're saying. Now, of course, the difference is if you are in a technical field or a medical field, you know, there needs to be some obviously you need to, you know, confirm that what you're saying is scientifically or technically accurate. So let me explain what I see are two primary modes of research that relates to content production. So the one type is exploratory and explore and in exploratory research. You are simply, you know, you're reading a book you're enjoying surfing the web and reading articles watching videos doing some research without a particular article in mind. You are doing some additional course taking or learning exploratory research probably happens all the time for you without you even really trying because you're fascinated by your field. So you naturally like to read things in your field. So that's exploratory research it probably happens organically and on its own. So exploratory research is confirmatory research. And this is where you are confirming a definition of a word, or you are clarifying that you actually do understand a concept that you're writing about. Maybe you are finding a few facts and figures that will add to your article or to your video, or to your podcast episode. So exploratory research to confirmatory research to make sure I understand the word confirmatory and knew how to spell it, you know, correctly. So that's one example. Right. So, when you are actually doing the content production, you might need to do a little bit of confirmatory research, but it's really important to limit how much confirmatory research you do. In fact, I think it's mostly optional. Rarely do you get someone commenting and saying well you got that one fact, or that one definition wrong I mean it might happen every now and then. But if you generally are sharing a helpful lesson or an inspiring idea. A minor fact that's not exactly right, or a word that's not exactly correct. It's not going to make the article bad or the video back. In fact, a lot of, well, as we know, a lot of viral news articles have a lot of wrong facts now I'm not saying that you should do that. But what I'm saying is that people readers viewers are extraordinarily forgiving, especially if you've built an audience who trusts you now you might say George are you telling us that we should be sharing inaccurate information no I'm not saying that. What I'm saying is that it would be a good idea to separate out your research time from your writing time. Usually, like I said your exploratory research you probably do it anyway, but you might want to say, Okay, I'm going to be writing about this topic I'm going to be doing a video or podcast episode next week about this. I'm going to spend a focused 30 to 60 minutes only doing some more exploratory and a bit of confirmatory research on that. Before I before I then spend that focused time writing or making a video so in other words, if you can separate out your research and content production time your research time versus your writing time or recording time. That's wonderful. Now, I wouldn't I say content production and you can do your writing and video, making in the same session work session, but try not to put so much research in there because then you start going down the rabbit hole of, you know, forever early for forever additional information that you realize you need to discover. So, exploratory research, confirmatory research, and then content production. Another type of research I want to tell you about which I think is the most valuable type, which is primary research, or original research. This is where you do some experiments in your field.  And you've, you're now reporting on what it's like to try that technique out in your own life. Or based on what you've tried with friends or clients. That's primary research and that's very valuable because that's what people will want to link to to say, Wow, look, you know, George did this experimentation and, you know, this is what he discovered. So that's one type of original original research is your own experimentations. And then, you know, within your own life and in clients lives, and the other type of original or primary research is taking surveys or polls.  So original or primary research is really the most valuable and of course it has to be done separately than writing your article or making your video so the bottom line is the, you know, I guess maybe the parting words of encouragement I have for you. It's, it's very important for you to be creating content on a consistent basis. If you want to maintain or strengthen your creativity and your muscles of communication. If you don't create consistently, those capacities within you start to wither away, and it gets harder to get back into it. So, you know, at least once a week, at least once a week, you should be creating something new, writing an article making a video recording a podcast episode something like that. Now, that's why you should make research optional compared to creating content like I said, even if you didn't, not another minute of research you have enough within you, your own life, your own original research really, you have enough within you to create many dozens of articles and videos and while you're creating without having to research. While you're doing that consistently, you're probably on the side doing exploratory or original research anyway, because of your own passion and interest in your topic. And then those will eventually be integrated into additional content that you create so please go forth and create content. About accuracy, I know it sounds terrible when I say it, but what I mean is, don't be afraid of the judgment of others who are going to confirm every fact and figure you cite. Now if you're citing facts and figures those should be quite quick to pull up on Google confirmatory research that's what I mean, but you know you don't have to. I think you know what I mean you need to make it lighter in terms of the free content you're putting out there now. This is different than paid courses, like if you're if people are buying a course from you. You need to do more exploratory original or confirmatory research to make sure that you are selling people things that if they're applying it to their life, especially to their health, right, or or to their finances, right there are certain places that have higher ramifications. If you're not accurate. So those kinds of things you need to obviously do more especially when it's paid, but when it's free content. That's my bottom line encouragement for you is you need to be consistent at it. Don't worry about research. You're already doing research on the side. You need to do more research in a very short period of time 15 minutes for each article you write just confirming a fact or figure or a date or a definition or something like that and that's it create consistently. No matter what. All right, so I hope this is encouraging and helpful. And there's my dog buddy in the video those of you who are watching it. Yeah, enjoy your create your creativity and your consistency because that is what will really make you a better and better communicator over time.  I wish you well. My name is George cow authentic business coach I love talking about how do we build a business that is based on our, our life experiences, so that we can create a fulfilling business that is genuinely helpful to others as well. And I look forward to seeing you in another video or episode. Take care.


This is Dr. Rajiv Goyal, من's health expert from Manipal Hospital, گروگرہ. Food is medicine, food is poison. If you have chosen your food well, you will have a good health span. Life span and health span are two components. A good life span and a good health span is desired rather than just a good life span. And food choice makes the difference.


Hello, and welcome to this presentation of the ARM Cortex-M4 Core. In addition to the main Cortex-M7 CPU, the STM32-H747-H757 and STM32-H745-H755 microcontrollers integrate a Cortex-M4 Core in order to benefit from the powerful performance of the 32-bit processor architecture, and particularly of the high level of deterministic processing. Based on the ARM Cortex-M4 Core, the STM32-H7 series doubles the DSP capability of a single-cycle DSP Mac for data processing and the single-precision FPU performance. In addition to the computation capability offered by the ARM Cortex-M7 Core, the STM32-H7 offers more control, performance, and enhanced execution determinism. Many application domains can benefit from the dual-core architecture of the STM32-H745-755-747-757 devices. The Cortex-M4 in the STM32-H7 microcontroller offers support for eight independent memory regions with independent configurable attributes for access permission, read-write allowed or not in privileged, unprivileged mode, execution permission, executable region or region prohibited for instruction fetch, and cache policies that affect art accelerator instruction cache behavior. For more details, please visit the ARM website on which you can find all information about the Cortex-M4 Core.


What's going on, everyone? Sam here with late in sports cards, ripping 22. Panini Limited, football hobby, 7 box, half case break, number 9, random team style. Here's a look again at your random results. As always, you can find these on the website under the results tab, as well as the link in chat. Good luck, guys. Got one more regular random team to fill up, which is going to be number 10, breaking after this. I'm going to have Donnie drop you that link really quick. When do you have the chance? About to Kirk Cousins, the 125. Jags and Pats. There's Lamar to 75 for the Ravens. It's 23, actually, I believe. Big print line on that one. Send an empty box and wrapper with the Ravens. OK, well, the online thing's going to be 25. Is it? Yeah. Really? Well, I think I'm going to know. Maybe. We'll be surprised. We'll double check that. Is it going low with Lamar? With the Ravens, yeah. Soon to Shopify? No, it probably is Shopify. Let me just double check because that's going to annoy me if it is. Yeah, I don't know what happened there. It's weird. Let's see. No, no, you're right. OK, Brian Burns, Daniel Jones. We got Doug Flutie, four of 99. Nice one there for the bills. That's pretty sweet. I think that's going to Carl right there. That's Carl. Carl, I helped you a little bit. There you go, Carl. This is like how it reminds me of select. Yeah, kind of, I would say. A redemption in here as well. Base, base, base. Redemption is going to be Ruby Spotlight. Trayvon Walker going to the Jags. Nice one there, Jags. That's sick. Ross taking a spot. I believe we're down to 22 now. Because, yeah, there was an order that didn't go through, so we should be down to 22. Yeah, I was being Shopify with Shopify-ing again. Yeah. Shopify, gunner, Shopify. You know how that goes. There's Chris O'Lave, RPA. That is 16 out of 99. Nice one there for the Saints. Grats on that. Nola, Nola Saints. Herbert to 99. There you go, illegal. Hey. It's going to be Garrett Wilson to 75 on the jersey. What is that? Unlimited potential. Piantae Ingram rookie. Willie McGinnis, five of 10. Nice one there on the Game Day Aesthetics for the Patriots. Congrats on that, Lance. Lance, nice one there. Couple more tiered spots coming in for today. Thank you there, Rob H. Redemption is going to be Jameson Williams, Silver Spotlight. Nice one there for the Lions. Grats on that Detroit. Nice one coming your way. Very cool by, I think, a Shopify-ing again. I think they're supposed to be 21. Maybe not. There's an Amon Ross St. Brown to 99. Limited Ink. Limited Ink. Jalen Petrie rookie.  There's a Herbert again to 99. Dalvin, Herbie Base. Ooh, nice. Steve Young, Jerry Rice, one of 10 on the Duos. Very nice. Grats on that, Niners. Try and Logan. Try and Logan. Two Herbies out of 99 for illegal. Oh boy. And guys, 23 to go actually on the next one. No, 22 to go. 22 to go. 22 to go. Shopify is just messing me up here again. There's Mackerel, 40 of 99. Three colored RPA for the Panthers. Grats on that, Carolina. Jeff taking a couple of tiered spots later on as well. Think Jeff M. I think tiered down to like seven to go now. Not bad. There's Johorn, 43 of 99 on the membership. A cell phone celebration, baby. Congrats on that, Saints. That's sick. One of the best celebrations in our history right there. That was something else, dude. Zay Jones to 125. Base and base. It's going to be a George Pickens to 125 for the Steelers. Nice one there. Is it harder to complete a rainbow of a top player? Get all of one parallel that's like out of 25.  Or do the Kenny Pickett rainbow. I honestly think it would be easier to get the 25. I think it would be too.  It's going to be a Tyler Algier to 99 for the Falcons. Nice one there, Falcons. Illegal. Does the rainbow include the one-on-one? I would assume so, but in this scenario. Mike Evans, there's a George Pickens. 59 of 99 for the Steelers. Nice one there, Pittsburgh. Grats on that one. Just hit a tweet, if you don't mind. Nice Pickens. An NFL young boy. 2 up to 99. C and Aaron Jones. It's going to be a memorabilia sky more to 99 for the Chiefs. Grats on that, Chiefs.  The Pickets. Yeah, I think it'd be harder to do like the rainbow of a player. It'd be more expensive. I don't know if it'd be harder. Harder, necessarily. I think it'd just be more expensive. Kirk Cousins to 125. Cup, Davis Mills. Got a Jonathan Taylor to 99 for the Colts. Nice one there. It's going to be Richard Sherman, 8 of 15 on the membership auto for the Niners. Really cool memberships coming out of this so far. Joe Horn and Richard Sherman. Put me on a sorry receiver like Donnie. That's what you're going to get. Torture in a 101. Probably was. I'm not going to knock it up. Even disagree with that. Romeo Dobbs to 199 for the Packers. Nice one there. Four again, Green Bay. Congrats, Green Bay. It's a retire. Davis Mills to 125. There's Jameson Williams to 125 as well in the Jersey card for the Lions. Leonis and their membership coming up. It looks like these are fun, dude. It's going to be Dave Casper for the Raiders, 98 of 99. That's sweet. Grats on that one there. Raiders, Herbie and RPA, Brian Robinson, Jr. 110 out of 199 for the Commanders. That'll do it for the break, guys. Do a quick recap here. I hope that Herbie was another round. Jamo, that's Jonathan Taylor, Skye Moore, George Pickens, Duel for the Niners, Garrett Wilson, Lamar, Dave Casper, Romeo Dobbs, Richard Sherman, George Pickens, a Brian Robinson, Jr. RPA. We had Tyler Algier, Joe Horn, Matt Corral, Monroe St. Brown, Jameson Williams, Willie McGinnis to 10, Chris Olave, Trayvon Walker, and Doug Flutie. That is going to do it for the break, guys. Thanks again for the fail. Let's fill up number 10, everybody. Thanks again.


I first got interested in the idea of going to Mars when I was three years old. And lift on, lift on. She wants to be the first or one of the first to go to Mars. She's a regular kid with a dream that she's willing to pursue. Spaceflight is very risky business. You have to take it serious or you will die. If the option was to go to Mars and never come back, I would still want to go and be a part of the mission. When Alyssa was younger, I remember Alyssa coming to me and asking me, had human beings ever been to Mars? And I explained to her that we'd been to the moon, but not Mars, but it would be her generation to become the Mars generation and go to Mars. This would be something really cool.  Little did I know that I would be raising a child that I'm supporting to leave this planet. I do everything that every other normal kid does except on the side. I'm training to become an astronaut and go to Mars. Kids are always told you can do whatever you want to do. You can be whatever you want to be. Alyssa has heard that, but she has accepted that I'm going to have to work really, really hard to get to where I want to be. She's the youngest to ever graduate from Advanced Space Academy. She was the first person to complete all NASA's space camps in the world. Got her rocket license before getting her driver's permit. Currently I have my basic Superdiver certification and I'm working on my advance. She's doing the International Baccalaureate, so she's doing college level classes in 10th grade. Multilingual education, so she's taking her classes in four languages, English, French, Spanish, Chinese. She's got the right mental attitude. She's doing everything that she can physically here on Earth to prepare herself for that journey to Mars. I don't think there's anything specifically that kind of makes it easier for me or makes it something that others can't do. It's just something that I've kind of really focused myself on what I want to accomplish. By the mid-2030s, I believe we can send humans to orbit Mars and return them safely to Earth. Going to Mars is absolutely essential for continuing a human species as a whole. It is very important that we keep exploring because it has already been said that a single planet species will become extinct. Just going to Mars is that first baby step and showing people how we can move on from planet Earth, which is kind of like our little cradle now. We're destroying our own planet. If we don't continue to explore, we could end up not having a planet to live on. So even though there are a lot of risk in going to Mars, I believe that the rewards are so much greater. Yeah, space is a dangerous place. And yeah, there's so much that I'm giving up for it. But at the end of the day, there's so much good that can come from this mission. The big plans for Mars is eventually terraforming it. Change Mars to kind of become like another Earth, to have a second home for humans to live on. Let's checkmate. Booyah! There are companies that want to send one way and colonize Mars. And then there are people like NASA and ESA that are working together that want to have a return trip. So I still have to look at it as a father that I'll have my child for 20 more years and then I may not ever see her again. And that's hard. But for what she's wanting to do, I have to support her. I have to let her go. It's bigger than the two of us. We know that the next 20 years together is going to be important because we know for sure that those are 20 years that we can spend together. Obviously it's not the best thing to be telling your daughter to go and go on a mission to Mars and leave the planet, but I still know that he supports me anyway. Every time Alyssa talks about having to go to space and how she can't get married and how she can't have kids, it makes me sad because I'm saying, oh, she's going to leave me one day. But then I remember, we might as well live now and when the future comes we'll be able to accept it because we didn't waste time.   Last year we put out a call for the next cadre of astronauts. We had thousands apply and we're accepting less than 10. The biggest challenge for Alyssa is just trying to get everything done that she wants to have for her unique resume. Specifically for the Mars mission, I would say that they're even more precise about who they want for that mission. So thinking about all that motivates me to put in the hard work now that I know to build up kind of a good resume that helps me stand out from others when I do apply. The opportunity to be one of the youngest people that's ever ventured into space, to be a trailblazer, a pioneer, I think this is everything she's always wanted to do. She just recently was accepted to Possum Academy. She's the youngest person ever to be accepted to that program. Basically everyone who's ever gone to this program either has a college degree, either has a master's, either has a PhD or is working on any of those, so they're all a lot older than I am. What Possum Academy is, they are preparing people for space flight. I will actually be certified to go to space. I think it's really significant that Alyssa is a girl who has this huge dream to make it to Mars. She is someone that girls can look up to and say, hey, look at what she did. Look at what this girl did who was the same as me once. So it is important to inspire kids and also adults.  No matter how crazy it might sound, follow that through and never give up on your dream. The 2033 mission that they always talk to us about, that's when the sun is going to have the least amount of radiation going. That's when Mars is going to be the closest that it's been in thousands of years. That's when they'll have the technology perfected. Yes, if she was a few years older, a few years younger, it may not be working out, but the way doors have opened for her, it is definitely destiny working its hand that this kid is meant to go to Mars. Mars will be the greatest adventure ever.


Strange events at Ginny-Metherels this week. My microphone, which is pretty stiff really, suddenly just turned upside down whilst I was watching it. I was rather surprised because it's never happened before. This carrier bag which had been hung on the side here for random bits of rubbish, suddenly it did this. There was no breeze and no windows or doors were open. It was literally as if it was being moved by invisible hands. What do you think's happening at Ginny-Metherels?


So, now we go to the fourth lecture of this course, we will talk about more of vector calculus in this lecture. So, first is you know gradient concept, the gradient is has got both magnitude and direction, magnitude is describing the maximum rate of change of a scalar field and direction is the direction of the maximum, right. So, we will see you know example of this in the next slide and more explanation. So, again the gradient in Cartesian coordinates you have this expression, in cylindrical coordinates you have this expression and in electrostatics you have E vector given by minus del V. Now here you know of course units match because this is volts per meter because del is 1 by meter. So, volts per meter and E of course is volts per meter. Now, other thing to note here this minus sign you know let us understand intuitively why there should be minus sign. So, E is always from high to low, electric field intensity is say from positive to negative charge, by convention we take positive things at higher negative things as lower. So, E is from high to low, gradient is always from low to high, when we say gradient it is always low to high. So, that is you know very logical that is why that E and del V are separated by minus sign, okay. So, if you take an equipotential surface, right any equipotential surface if suppose this is an equipotential surface and suppose there are two points with you know x x x 1 y 1 and x 2 y 2 then you can write the distance vector P joining these two points as dx ax hat plus dy ay hat plus dz az hat whereas dx is x 2 minus x 1 and similarly, right. So, now since it is an equipotential surface the potential difference between any two points on this surface is 0. So, that means dV is equal to 0 between any two points. So, dV equal to 0 now dV can be written from you know total differential formula as this is it not this is dV can be written as this expression. Now, this expression can be written as del V dot del P because you have both the expressions del V is here and dP as a vector expression is here if you take the dot product of these two vectors you will get this, right. So, that means you have dV is equal to 0 is the gradient of V dot dP and now it is 0 because it is equipotential surface, right. That means del V and dP are orthogonal because we have just you know in the previous lecture we saw dot product is 0 means the cos of angle is 0. So, that means angle has to be 90 degrees. So, that means this del V and dP distance vector they are orthogonal but E and del V they are in the same direction in the sense they are oriented along the same direction of course their directions are opposite, right. But that means what it means is del V as well as E are normal to the equipotential surface, right. Next comes the divergence. Divergence gives the net flux outflow from a close surface per unit volume with volume tending to 0. By definition divergence A is given by this limit del the volume small unit volume tending to 0 close surface integral A dot dS by del of volume or delta volume. So, now this divergence A in Cartesian coordinates is this and in cylindrical coordinates is given by this expression. Now remember divergence is always flow source. If divergence is non-zero that means there is some source there which is responsible for flow of fields, right. Now let us again take the example that we have been seeing quite often since beginning of this course this lead to ground structure. So, when now first you notice that I have purposely drawn this positive charges here little bit closer to each other on this side and then little bit sparsely spaced things on this. Why that happens because because of presence of this other electron electrode and which is at ground potential those you know charges negative charges on that will basically attract positive charges. So, if and if it was an isolated conductor cylindrical conductor then the charges would be uniformly distributed, right. So, this why I am telling you this is whenever you see or draw anything you should draw with the background physics taken into account. So, you should not just draw positive charges moment you know you have this another conductor coming the charges get redistributed. Similarly, on this ground plane although I have not shown these three charges will be more closely spaced as compared to the charges on the at the far ends is it not. So, now you know it is easy to understand that divergence will be positive here because field vector is originating, right. So, nothing is coming in and something is going out. So, divergence net divergence is positive whereas on this negative charges something is coming in, but nothing is going out from those points. So, the divergence is negative, right. Whereas point P if you take some point P in between the divergence is 0. Now, how do we understand that now this this line middle line field line you assume that it is impinging on this some kind of you know cube and this at this point you know you have that at the center of the cube you have point P at the center of the cube you have point P and now by definition if you calculate your closed surface integral a.ds. So, now there are six sides here is it not for this cube the four these four sides will not contribute to the you know dot product because of the reason that you know you have this the field is perpendicular to the area vector is it not field is perpendicular for because for this phase for example the area vector is going to be like this that is going to be perpendicular to this field. So, the dot product is going to be 0. So, the only two sides that will contribute to the dot product are the front and backside because in that case you have you know field as well as you know normals along the same direction the difference being the unit normal on the front phase is going to be outside. See concept of unit normal we need to understand with reference to open surfaces and closed surfaces. Suppose you know you take this open surface now these are open surface now these suppose you take this surface for this surface you have two choices for unit normal either it could be like this or it could be on the opposite side going in the opposite direction. So, but this choice does not remain with you if you consider if you are considering the corresponding counter integral if the corresponding counter integral you are considering like this then counter integral is in this direction. So, the unit normal will be in this direction whereas if the counter integral is being taken like this in anticlockwise direction your unit normal to this open surface will be in this direction. But if you take closed surface something like this there is a closed surface all these know for all sides of surfaces of this closed surface the unit normal is always outward normal. So, for this surface it will be like this for this surface it will be like this like this and like this. So, for closed surface there is no problem it is always outward normal for open surface if you are considering the corresponding counter integral then again you are unit normal direction gets fixed if counter integral is not being considered with reference to the open surface then you can take the unit normal in either direction. So, the unit normal in this case is opposite to the direction of the field for this front face whereas for the back face the unit normal is along the direction of the field and both those that is why those dot products will also cancel each other that is why overall dot product for the entire closed surface is 0 and that proves that you know since this is 0 divergence is 0 that is why you know it is the case. So, the divergence theorem is divergence A dv evaluated over volume is equal to closed surface integral A dot ds. Now effectively why this theorem is useful because you are converting 3D into 2D integral this is very very useful particularly you know in you know integral equation numerical techniques where the dimension of integral reduced by 1 similarly if suppose you know you are doing a 2D analysis mostly you know in this course also we are doing a 2 dimension analysis. So, when we are doing 2 dimension analysis what we are typically do we take the cross section which is perpendicular to the current always you know whenever you show a cross section we will find we either show dot or cross that is the current direction that means you are taking always cross section which is perpendicular to the current and then we do what is the approximation that we do the infinite you know the same 2D condition that you see on the paper it continues infinitely in z direction right. So, that is the approximation we do. So, when you do that approximation there also if you apply you know this divergence theorem effectively what you are doing is this divergence A dv is the same thing here it is effectively ds into 1. So, this is volume ds into 1 is volume that means you are taking per unit depth in the z direction is it clear what I am saying. So, per unit depth in z because it is a two dimensional approximation and although z is infinite we take for calculation we take we do calculation per per unit depth. So, effectively it is ds into 1 and this is dl into 1. So, this is also ds this ds and this is same dl into 1 is this ds. So, both the equations are same, but since we are actually doing a 2D approximation already already we have reduced the dimension by 1 by further you know invoking divergence theorem we have further reduced the dimension of the integral by 1 again this is very useful when you do two dimensional analysis. We again go to that virtual electromagnetic laboratory where in divergence is explained through some field plots. Now, you can see here divergence of now what is this equation it is x ax hat y y a y hat so divergence by formula is 0 is it not. But then how do we understand this. So, here for example you can see take any point here and you will understand that the rate of change of field with x and rate of change of field with y they are exactly cancelling out. If x the direction the field slope in x direction if it is increasing the field slope with y direction is reducing by the same amount. So, that makes you know the divergence equal to 0. The vector with positive divergence it is very easy. At every point for example in electrostatic field there is positive volume charge density that is positive flow source. Similarly, for negative divergence at every point there will be negative volume charge density that is negative flow source. So, now we will go to the next which is curl. Curl is measure of circulation of a vector field and it is circulation per unit area and it is a vortex source and by definition del cross a is given by this formula and again earlier in case of divergence volume was tending to 0 here the corresponding surface is tending to 0. So, here it is what is in question a surface which is bounded by close counter. And you know you have this the vortex source the most common example that we can think of is a current source. The current here is coming out of this paper and the corresponding field again given by the right hand rule. So, current the field direction is in anticlockwise way. So, here the loop this area is normal to the vortex source and that will give the maximum circulation that is the meaning of this max. So, your loop or the area vector is arranged such that it basically that area vector because area vector will be normal to the plane and that area vector is along the same direction of the vortex source and that will give the maximum circulation. So, for example if you you know current source is like this and if you your loop is not along this but it is like this then you will not get the maximum circulation calculated by this formula. Then the formula for curl in Cartesian and cylindrical coordinates is as given here. So, just to you know sort of quickly understand this just see the direction of this. So, it is yz zx xy better to write in this form rather than putting a minus sign and just interchanging these two terms because this makes it simple yz zx xy. So, it is in the same sequence and then finally you know you have the Ampere's law in point form is del cross h is equal to j. Remember probably I did not mention when I was talking about Maxwell's equations. So, Maxwell's equations that we have seen they are like point form of differential form of equations because they are involving all curl divergence and all that and they they involve derivatives partial derivatives. So, that means Maxwell's equations that we have seen till now they are basically point form of equations they are telling you what is happening at a point because derivatives tell you because derivatives change from point to point is it not. So, this Maxwell's equation that we saw in the till now involving divergence and curl operations they are basically point form. So, this is you know point form of Ampere's law and when you actually take the surface integral from both sides on both sides then you have integral j dot ds is equal to i and apply Stokes theorem which converts surface integral open surface integral into closed line integral l. So, you will get h dot dl is equal to i. So, again here Stokes theorem is useful in converting 2D integral into 1D integral. Similarly, you can actually see the there is some excrement in virtual lab on curl also that actually you can see in your leisure time. If you go to electrostatic fields we start with Coulomb's law which is f is equal to q 1 q 2 upon 4 pi epsilon 0 r square wherein this q 2 upon 4 pi epsilon 0 r square is the electric field intensity due to charge q 2 and if that electric field intensity is acting on q 1 then you will get force on charge q 1 as q 1 times e. So, e is q 2 upon 4 pi epsilon 0 r square. Now, in case of you know electric fields you can either have line charge surface charge or volume charge. So, line charge is rho l dl and the corresponding electric field intensity is this. Again remember both rho l is the Coulomb per meter line charge per unit length whereas this rho is the distance variable in cylindrical coordinates distance from the axis. When it comes to surface charge you have dq as rho s ds and corresponding electric field intensity is given by rho s upon twice epsilon naught a n vector. Now, here how do we understand this? Now, you know you have this capacitor problem we know the field distribution like this. Now, understand this field distribution using this formula. If you take only the positive plate of the capacitor then you have the field lines like this as well as field lines going up. Remember because positive charge the field will emanate from below as well as on the top but I have shown only the field lines on the bottom. Similarly, the negative plate you have the field lines terminating on that. Similarly, there will be field lines terminating on this side. So, now if you superpose because linearity is there there are no non-linearities in this problem you will get the resultant field distribution as given by this. So, only in this region between the two plates you will get addition because both the fields are in the same direction whereas above and below you will have cancellation of fields because of the two fields. And that is how you get this and the corresponding formula of E resultant as rho s surface charge upon epsilon naught a n hat. And remember what we have seen d vector is nothing but really rho s is it not because d upon epsilon is E and unit of rho s is also coulomb per meter square unit of d is also coulomb per meter square. D can be related to surface charge density on the conductor surface or to volume charge density in non-conductors through the equation divergence d is equal to rho V. So, as mentioned here in free space d is equal to epsilon 0 E and only one of the two vectors d and a is sufficient both vectors are not required only when you have material and corresponding polarization which we will see later you need both the vector that means when p vector is also there polarization you have to actually you can differentiate between d and E and you have to have a separate treatment given to both vectors. Now the Gauss law is basically total electric plus 2 closed surface is equal to charge enclosed within it. So, that actually can be expressed as q is equal to closed surface integral d dot d s which is also but q is also integral rho V d V volume charge integrated over the volume charge density integrated over the volume. So, again now if you apply divergence theorem you will get divergence d d V and that is why now if you correlate this and this expression you will get divergence d is equal to rho V. So, in a way we have derived the first Maxwell's equations from Gauss law. Now the next point is potential work and energy. Potential difference V AB by definition is minus integral A to B E dot dl and that is also potential also is defined as work done per unit charge. So, now actually if you see here if V AB is this V B A is minus B to A because I am just changing this interchanging this as well as the integral I am interchanging. So, it is minus B to A and E is minus del V. So, this minus sign and this minus sign goes and you get something positive. So, when you go from B to A you will get positive voltage and that is what it should be because it is a gradient. So, that way we have just verified the sign convention is correct. The other thing is important thing is electrostatic field is a conservative field. That means if you take two points C and D here the E dot dl along this path and along this path is same because the potential difference is same. Is it not? Both will give you the same answer. And now since both these are in the same you know they are their magnitudes are same. Now you take the total integral like this circular total integral will be 0. Is it not? And now you apply Stokes theorem you will get this and then finally del cross E equal to 0. Now, this becomes in case of time varying fields it will become del cross will become minus daba V by daba T which we will see later. But for electrostatics this is 0. Now this one important thing what is this conservative field? See here it is written conservative fields cannot do any work. So, what is the meaning? Suppose you have a capacitor which is you know connected to a battery and you basically you know charge this capacitor by closing this switch and this is plus minus. So, in certain time constant you know this will get charged and the corresponding energy will get stored. We call this as potential energy but this potential energy got stored only when the some charges move. So, remember always the work will be done only when charges move. The static charges will not do any work. Similarly, now this charge capacitor with this potential energy is not going to do any useful work unless you make those charges move. For example, now this capacitor you short by connecting in parallel with resistor this capacitor will get discharged in no time and then it will produce heat in this resistor. Now that heat of course is a work it may be useful or non-useful but it is a work. In some cases it will be useful work for heating applications. So, the point to be noted here is when it was only capacitor was charged and you know the charges were static it was only potential energy that is not capable of doing any useful work because charges are static and it is a conservative field. Only when those charges were allowed to move by shorting that capacitor what you have is basically the charges moving and the corresponding kinetic energy and the work. So, kinetic energy you can associate with work always that is why the charges have to move in electromagnetic charges have to be moving to effectively do some work. These are very important concept to be understood. Now the next point here is the energy density that is energy per unit volume is half epsilon E square. This expression we will use you know quite often in the FEM theory to start with when we talk of energy minimization and energy total energy is the volume integral of this. The last topic of this lecture is here we will talk about current densities. Three types of current densities are discussed here conduction current density, convection current density and displacement current density. For all these current densities this expression of I is same. I is dq by dt and it is integral j dot ds that remains same but j conduction is given by sigma E it is governed by Ohm's law potential difference and again this is j equal to sigma E is called as point form of Ohm's law which is V equal to I R. So, j equal to sigma E is more universally applicable as compared to V equal to I R because for application of V equal to I R you need to have you know the conductor of certain you know uniform dimensions so that you can calculate resistance as O L by A and all that is it not. Then you can easily apply that Ohm's law but j equal to sigma E you can apply for any arbitrary shape conductor at every point. Whereas V equal to I R is like a integral form because we are actually finding the potential difference across the end of a conductor. So that is a integral form. So, in finite element method we will use this when we calculate for example losses, eddy current losses or losses in any conducting part. The loss is given by j square upon sigma dV integrated over volume. This also can be represented as rho j square dV because one upon sigma is the resistivity. Note that watts per meter cube is unit of j square by sigma or rho j square. So, again I think rho in today's lecture we have used third time for a different, is it not? So, now this rho is resistivity. So, rho was earlier used for volume charge density then cylindrical axis distance and now this is the resistivity. So, please bear in mind the differences. So, this is resistivity. So, convection current density is given by this rho V there is a volume charge density into its velocity. So, now this is not governed by Ohm's law. That means potential difference is not causing this convection current to flow. It is like you can imagine suppose there is some liquid insulation and you have by some means generated charges you have deposited those charges there and you make that liquid to flow by some mechanical means like pump. So, now those charges which you have introduced they will flow and constitute current and that will be convection current. So, that is convection current density. So, needless to say in this course on machines and equipment we will not have this convection current density except if you are doing some advance analysis for example in case of transomers wherein you are trying to understand static electrification phenomena for example whereas wherein static charges get developed due to you know friction between oil and solid insulation and because of pump action those charges move there this convection current would be applicable. But otherwise in normal circumstances this conduction current density would be applicable. In Maxwell's equation what we actually you know C, J right is basically combination of both conduction and convection if both are applicable. Remember all these equations generally are they are general in our this course also we will be writing most general form of equations but then depending upon the problem solved depending upon the variables applicable some variables will get eliminated in the formulation. Then finally the displacement current density which is you know sometimes you know not very easy to understand. So, this was introduced by Maxwell for bring in consistency with the continuity equation. So, continuity equation is this divergence J is equal to minus dou by dou by t. So, what is you know this first let us understand continuity equation. Suppose you have some volume and if you evaluate divergence J for that volume and if the divergence J is positive that means some charges would get depleted from that volume is it not. So, that is the meaning. So, some charges getting depleted means dou by rho v by dou by t, dou by t is becoming negative and this negative of negative is positive and that is why divergence J is positive right. So, this is the first explanation. In the you know starting of the next lecture I will explain the other view point with respect to circuit. But what is the inconsistency here? So, del cross H is equal to J if we you know consider the original Ampere's law in point form and divergence if we take the divergence of this. So, we know divergence of curl is identically 0 right and that means divergence J will be equal to 0 because we are taking divergence of both sides. So, divergence J here is given by this that means we are forcing dou by rho v by dou by t equal to 0 which may not be the case particularly at the high frequencies because if you convert this into time harmonic form then it will become minus j omega rho v at very high frequencies particularly this is not going to be insignificant. So, this is the inconsistency right. So, whenever you have you know for example capacitor currents becoming appreciable in at high frequencies stray capacitance currents becoming high at you know significant at high frequencies you cannot actually you know have divergence J equal to 0 because then we are actually not allowing this term to be finite in some cases right. So, more about this point in the next lecture. Thank you.


People ask me why I still use vanilla HTML, CSS, and occasionally JavaScript on my YouTube channel. Where's the React content? What about some CSS and JS? When are you going to make a video using Tailwind, Bootstrap, Interior UI, etc? There are two reasons that I stick with vanilla HTML, CSS, and JavaScript though. First off, it's really important to understand the core languages that all of those things are built on top of. And second, it's much easier to take something that I make with regular old CSS and incorporate it into your workflow of choice than for people to try and turn something I write using Tailwind or some CSS in JS solution, which they're not familiar with, and implement that with however they're writing their CSS. But I can't put enough emphasis on that first point that I just mentioned. Knowing the core language is so important. People are often told learn React because it's popular. I see it all the time on social media and even within my Discord community. The problem though is people listen to that advice and they go out and they learn React, but they never take the time to learn JavaScript first. And while they're learning React, the tutorials and courses they follow are using Bootstrap or Tailwind and they never actually learn CSS. Quick side note, it's painfully obvious when people are using Tailwind having never actually learned CSS first and it's doubly painful to debug. There's nothing wrong with Tailwind but you can't use it without a decent understanding of CSS. So please learn that first. But going back to what I was just talking about learning the core languages, when people skip that step it leads to questions like this one right here, which were on a recent video of mine where I was looking at doing like a sticky header and how you could get it to change when you scroll down a little bit. Now the focus of that video was on about eight lines of JavaScript to get that actually working. Now I'm not here to judge at all. I understand that if you're a beginner and you want to incorporate what I was teaching there into a React project that you're working on, it might not be super straightforward and there's probably a few tweaks that you are going to have to make. The problem is when you've only used React, you don't know the parts of the code that you're writing that are React specific and the parts that are regular JavaScript. And I'm not speaking from some high and mighty spot here either. I made the same mistake but the previous generation's similar mistake, where I learned jQuery before getting into JavaScript itself. I think that the reason that I felt into this trap is the same reason that people get into modern JavaScript frameworks early on as well. React tutorials are going to show you how to make a website and make things work, whereas a JavaScript tutorial might just get bogged down in theory and you're not really sure what the point of everything you're learning is. I ran into this exact same thing with jQuery. jQuery is basically all about DOM manipulation. So learning it was about making things happen rather than going over how to make yet another type of loop in JavaScript. It felt more meaningful and like I was making some progress because I was actually building things while I was learning it and getting things to happen and it was much more exciting and it felt much more impactful. But ultimately, learning jQuery first held me back for a long time. I would have been better off getting a good understanding of JavaScript first and then using jQuery to help speed things up and improve my workflow. But then I also thought, what's the point in learning JavaScript first? Like most people, I never thought jQuery would die, so knowing just that would be completely fine. Just like today, I'm sure people figure React is never going to go away. And just to give an idea of how big jQuery was, it's still currently being used on over 77% of all websites. React, for comparison's sake, is being used on about 3.3%. jQuery was basically the king and it didn't even really have any challengers like React has today. And then one day it was basically kicked to the curb. Things come and go, trends change, new better things pop up and the industry shifts. All the while, the core languages that these things are built on top of are always there and slowly improving over time. Now yes, learning things like React and Tailwind can help you be more employable, but that never means that the expense of having a strong understanding of the core languages. And if you enjoyed this video, the script was actually based on a recent newsletter I sent out where I often talk about more general things like this rather than very CSS specific things. I also share all the recent stuff I was up to share other people's really cool things that I stumble across. It's a weekly newsletter. It comes out every Sunday. And if that sounds interesting to you, the link to it is just down below. If not, you can watch this video right here instead. And with that, I'd like to thank my enablers of awesome, James Enrico, Michael Simon, Tim and Johnny, as well as all my other patrons with their monthly support. And of course, until next time, don't forget to make a unicorn on the internet just a little bit more awesome.


Howdy, so I got another tail and I got something to fuss about so let's get right to it So over the weekend. I had a friend of mine who? Contacted me she called me up on the smartphone. She's another consultant and She asked me she said Mitch. How do I take my picture off of LinkedIn? And I said well, why do you want to take your picture off of LinkedIn and she said because I'm tired of getting These messages from these men who I don't even know hitting on me and I said really on LinkedIn You know cuz LinkedIn is supposed to be a business Networking thing it's supposed to be you know you put your business on there You put your name on there and where you work and all this other kind of stuff and she said yeah it's just it keeps happening and I had to think about that a little bit because Because even though that caught me off guard when she mentioned it as I thought about it later on I realized that I know a lot of women who don't put their picture on LinkedIn And there's a lot of women that don't want to put their picture on Twitter Don't want to put their picture on their blogs. Don't want to put their picture Anywhere in social media because there seems to be this thing where everyone thinks that they have a license Men I hate to say that but yeah men you think you have a license to basically Comment on how women look or you want to you know say how pretty they are or different things like that When okay, some may be pretty but they're projecting something else if someone is putting up modeling pictures on Instagram and you say oh you look nice or how pretty okay, that's one thing But if you start saying things that you want to do to them you've got way over the line And I know that you've created a fake name because almost all of them create fake names. Y'all know who you are So you can say that stuff Or you create your real name, but you block your site you make it private And so that you can go and do all this other kind of mess and I'm thinking that's just the Most cowardice thing that I can think of now like I said I'm linked in Why do people want to risk their reputation by doing stuff like that? You know, I did an interview I think last year with a young lady named named Jessica and I'll link to it here because you know it was a very interesting video video interview and she's a Facebook expert and She divulged for the first time ever how she had gone to a local networking thing and Got hit on by someone and not just hit on as far as you know Would you like to go on a date or whatever? But some vile stuff and she couldn't believe it and so she called the guy out She basically reported the guy they threw him out of that and threw him out of the organization But it made her a little bit shy and not necessarily want to go to networking events anymore Come on people really is your life so bad that you have to do this kind of thing out in public And you could risk your business by doing mess like that. Is it really that important for you? Sure, you know what? Growing up used to hear all these things these stereotypes about men would see women walking down the street Baby and whistling also the kind of stuff what turned out at what the stereotype that happens now I am so amazed at that because it's never been anything. I've ever done now. I am not approved. I Recognize a pretty woman Looking really nice or whatever and you appreciate that I've known tons of pretty women as a matter of fact My friend Scott used to say how is it? You know all these pretty women and you're not dating any of them Well, because I've never been one who has Objectified women in that way so that I wanted to say all these kinds of things You know, I have a lot of women friends who are pretty attractive because they know they can trust me my wife You know, okay, I don't know how I ended up married to her Because she's just you know way prettier Then I could have ever gotten lucky and she chased me I'm just gonna say that and she'll probably watch this and say no, I didn't but you know you did But I can't believe how these kinds of things happen Where I've been out with her and I sometimes tend to walk behind her and I will watch men watching her Now none of them ever hit on her because they watch her then they look at me looking at them And then they look away real quick I don't know why I get such enjoyment out of that But I do because they know I've got them and what's interesting just as a sidebar is that women will look at her as well Then they'll look at me looking at them and they look away. What the devil, you know I mean, it's just one of those kind of questions where I hate to ask this But I have to ask this question in general our most men pigs That's the nicest way that I can say that kind of thing. I don't understand it Why do we feel I'll include me on this even though I don't do it But why do we feel we have the right to say anything we want to to women just because they look nice Because they dress nice because they're pretty that matter whether they're older young sometimes Maybe that you may not necessarily even think that they're necessarily pretty but you just feel that you have the right to say these things When did you feel that? Someone granted you the right. Is this a male superiority thing? It certainly isn't an appreciation thing because you know what they don't appreciate it almost none of them And I have to say almost because back in the 80s There was someone I worked with named Holly and she was stunning stunning blonde real pretty wore the flanty dresses And we used to go out to this thing on Wednesdays. That's used to call party in the plaza. So it was they would have local bands who would play in the Federal Plaza and sometimes we would go together and For whatever reason people knew we weren't together I guess and they didn't really care at that time. And so she got hit on all the time And she would just smile through it. And so I said to her how do you feel about getting hit on by all these men? She says well, if I didn't want to get hit on I wouldn't dress like this Well, you know, I guess there are some women who like that But the majority of women really don't like it.  How do you how are you doing? You look nice Is there something wrong with that?  What woman doesn't want to see you saying all these nasty vile things on Twitter on Facebook or whatever please LinkedIn and There's a young lady.  You can say all this nasty stuff.  Let's just say that you have no guts. You have no honor. You have no integrity. You have no ethics Stop, okay. And if you're on LinkedIn doing this, do you really not ever want any business? Is that what you want your reputation to be?  Most of you guys am I wrong here? Let me know your thoughts. Y'all take care.  Okay, Mitch Mitchell y'all take care


a warm welcome to the 23rd session of the third module of signals and systems. We have seen something very interesting in the last few sessions, namely that sampling essentially amounts to multiplying an input signal by a periodic waveform, so simple. In fact, we wonder why we did start the whole discussion on sampling with such a simple interpretation. Well, there was an intent behind it, because sampling is deeper than just ideal sampling or sampling with pulses. Sampling essentially is a philosophical question of whether you can represent a signal more efficiently than in its raw form by representing it as a function of every point in time or every point on the independent variable. And we did begin the discussion that way and carried it out to a certain extent and finally, looked at what is conventionally understood to be sampling or sampling and reconstruction in the context of signal tossing. Now, one thing that we would now like to bring in is a little beyond sampling, see after you sample would you like to just let the sample waveform drop to 0 or would you like to hold on to it. So, the idea of holding on or smoothly joining samples is a new idea that we wish to bring in. So, you see we have been talking about sampling and reconstruction, in a way we need to talk about sampling and interpolation, let us write that down clearly here. So, sampling and interpolation, interpolation really means interpolate means to fill up the region in between to complete the waveform in between samples. Now, what approaches can we take to interpolate the waveform, let us see there are several different possibilities. So, let me illustrate graphically, let us take the smooth waveform that we have and let me choose to sample you remember we are always going to write sample that every multiple of T s and we should choose a few negative multiples to otherwise it gives the impression sampling starts at 0 which is not quite correct. So, minus 2 T s minus T s and then several positive values of T s. So, you have this waveform x of t that I have shown you with t as the time passes and now I start taking samples at every point, every point of sampling. So, here we are here we have this sample here. Now, the issue is you have this sample here and you have this sample here, what do we want to put in between that is the question of interpolation. What is it that we want to put in between samples? Do we want to hold on to the previous sample until we reach the next and then change over to the next, if we do that the waveform will look like this let us show that. So, here if we do what is called a sample and hold of course, this is just you know. So, this is this is the waveform. So, if we do a sample and hold we get the waveform which I am now showing in green you know in bold green. So, the bold green waveform that we have here is essentially a sampled and held output or the output of a sample and hold circuit a sample and hold device. Now, you could have many other possibilities. I shall show one more possibility in red on the same graph. So, we could have this. So, the red waveform essentially what is called a linear interpolate. I am drawn you know you can think of them as straight line joining the points that you have obtained by sample. Of course, you could have other kinds of interpolation and when you interpolate it is not necessary that you should just consider two at a time. So, you could for example, want to look at one sample and the next two samples and make a smooth joining of all of them and keep doing this for you know the next three samples 1 plus 2, 1 plus 2 and so on. So, you know you could have more advanced forms of interpolation. At the moment what we want to do is to analyze what would happen if we sampled and held because this would then give us an idea how to handle this whole idea of interpolating of filling up the gaps between samples. So, let us now analyze a sample and hold circuit or a sample and hold mechanism from a spectral perspective. Can we think of this whole business of sampling and holding as a set of systems. So, systemically what is it? Essentially we could think of a sample and hold as a cascade or as a series connection of two systems. So, you have the signal to be sampled, you have an ideal sampler here and then you have a linear shift invariant system. The impulse response of this linear shift invariant system is essentially a pulse, but remember here a pulse lasting all through the sample interval. So, here the pulse that we are talking about is not that short pulse which is going towards an impulse. We are talking about this pulse which begins at 0 and lasts until t s. Now, let us analyze this cascade that you saw and let us confirm, let us verify or convince ourselves that indeed this leads to what we expected to namely it leads to a sampling and held waveform. So, let us mark the outputs everywhere. Let us call this signal x t. Let us call the output of the of course, the ideal sampler let us say the sampling interval is t s. Let us call this x s t for sampled and let us call the output here x h t h for held. Let us draw this for each specific sample point by assuming some random x t. So, we have a simple signal let us draw it like this. Let us mark the sampling points. Let us draw the output now of just the ideal sampler. So, here you must understand ideal impulse is coming in. Now, you know whenever you hold, so whenever you pass this x s t through the linear shift invariant system that we have shown with impulse response h t what happens? Each impulse here is replaced by that pulse that we showed. So, on passing x s t through h t it is very simple. A linear shift invariant system when you say the impulse response of a linear shift invariant system you are essentially saying that the system response to each impulse with its impulse response. So, this impulse here at minus t s is going to result in a pulse from here to here. Similarly, this impulse here results in a pulse of course, scaled appropriately and so to this and so on. So, the green one is the output x h t. So, you see the good thing is we now have a systemic description what really is meant by sampling and holding. And now a frequency domain analysis is very easy. Let us do it. We already know how to handle sampling. Now we need to find out what happens when you pass through the LSI system. So, in the frequency domain passing through that linear shift invariant system essentially means multiplying the Fourier transform of x s t with the frequency response of that system. That system is clearly stable because its impulse response is absolutely integrable. So, let us write that down. Let us find the frequency response. This is a very easy frequency response to evaluate. Essentially, it would be a sine x by x kind of function or a sine by variable kind of function, sinc function as we know it. Let us evaluate it. As usual, we can make a slight replacement here rearrange the terms as they say. So, you know this part can be rewritten in terms of sine and we could now simplify it. Let us do that. So, it will be easiest for us to multiply by T s by 2 and multiply by 2 by T or T s by 2 in the numerator as well and we can now simplify this. So, we will take the 2 from here and put it along with this. And thus we get T s raised to the power minus j omega T s by 2 sine omega T s by 2 by omega T s by 2. So, here if we put omega is 2 pi f, then we get essentially pi f T s here. You will recall that we have seen this before. It is not entirely new to us. Now, this is the frequency response. So, it is clear. We are now well set to do the frequency domain analysis. We have the ideal sampler for which I know the Fourier domain analysis. I have this linear shift invariant system for which I again know the analysis. Let me put them together and we will put them together in the session that is to come. We will meet again in the 24th session. Thank you.


What's up guys, welcome back. Today's Thursday. So what that means, ticket tip Thursday time. Yes! Like always, my name is Shiraz. Here on Thumbs Up Around where we talk about buying tickets, selling tickets, making sure that you have all the fun with your tickets. Today is all about ticket disclosures. So we're gonna jump into it really quick, but there's a few things we do need to cover. One, what are ticket disclosures? Two, what kind of disclosures are we gonna find related to vaccinated seating sections, vaccinated tickets, COVID tickets, that kind of thing, what are we gonna find there? And then three, how do you actually go ahead and identify these things when you're going ahead and buying those tickets? Strap in, it's gonna be a quick one, so let's go. All right, so first off, what are ticket disclosures? Essentially, when you go in to buy that seat or ticket, there are certain descriptive words, key words that you may identify or see when you're going ahead and actually trying to buy that seat. Some of the most common ones are side view, rear view seating. Sometimes it'll be something as simple as, you know, a will call delivery versus mobile ticket delivery depending on where you're looking for these seats. And then you may also see the more common one related to ADA type seating. This seating is reserved for individuals who require that type of seating. So again, if you see that type of disclosure when you're going ahead and buying those tickets, make sure it applies to you because you don't wanna end up buying a ticket that you can't use. Now, there are some new disclosures that have started to creep up, specifically around COVID vaccine type rules. As I mentioned in a previous video, many organizations are moving towards adding vaccinated seating sections and these seating sections require a separate disclosure because they're acting differently than how a non-vaccinated seating section would work. Let me explain. In a non-COVID seating section, those are basically how we're dealing tickets right now with pods. So seats are, you know, separated between three or six feet apart. They're in groups of two, four, six, whatever the case may be.  With the new seats that they've rolled out and vaccinated seating sections, these sections are not spread out at all. Seats are right beside each other. Everyone is all together, all having a great time. So when these tickets are purchased and sold, there is a requirement for the individuals using these tickets to actually have been vaccinated fully. Teams and venues will be checking this prior to your entry into the venue. So if you haven't been fully vaccinated, you cannot use these types of seats. It's all well and good. You can go ahead and decide which seating section applies to you, which ones you are comfortable sitting in. And that's great. However, it can be a bit difficult trying to identify which type of tickets you are purchasing. And because of that, we're gonna dive into a few examples of what it looks like to buy tickets on Ticketmaster and a few resell marketplaces such as StubHub and Vivid Seats. Let's begin. So first off, we're gonna take a look at New York Yankees example here. First thing you see when you get to a ticket page, obviously you get the disclosure saying, you know, trying to reopen safely, blah, blah, blah, except the terms and conditions. Fantastic, wonderful, excellent. Let's continue. So what you can see here is this entire venue, there are many seats available. And just when you hover over them, you take a look and you zoom in, everything kind of looks the same. You can't identify which is, you know, vaccinated seating section, which is not. So right now, when I look around and I'm trying to buy seats, I can take a look and see and I zoom in, I can see there's these seats are all in pods. You can see there, group of four, blah, blah, blah, every seat is the same altogether. The way that New York Yankees have done it is a bit interesting. They said, if you wanna purchase seats in a vaccination friendly seating section, you can go ahead and type in the code vaccine and it will unlock all the eligible seats that are available to you. And now I'm being presented with seats that are eligible for vaccine eligible sections. As you can see, the amount of sections available to you have now changed completely because these are the only sections where you can sit in vaccination friendly zones. And again, teams are putting these seats all over the entire venue. So you do have options at different price points, different locations around the venue to be able to find and pick and choose what it is you wanna do in terms of your seating options. Now, if you look at NFL tickets, it's a bit different because they are going under the assumption that all seats will be able to be sold at 100% capacity. And so there are no disclosures on any of the seats. It's a bit of a different way of doing it. But again, they do have their initial disclosure on the main page that says, you know, this event is subject to COVID rules and safety guidelines, so it may be subject to change. However, the seats themselves, there is no initial requirement for that seat to be sold to only a vaccinated individual unless that venue requires it. These seats are not being restricted to vaccinated versus non-vaccinated seating sections. So again, do make sure you're paying attention because this could potentially be an issue if you do wanna sit in a certain type of zone. Last one on Ticketmaster, the Brooklyn Nets, the way they've done it, they've actually separated their event into two separate types. One event is actually for vaccinated seating sections only and the other event is for non-vaccinated seating sections. So again, make sure you double check, pay attention to where you're actually gonna be sitting and what kind of seats you do want. If we jump on over into resell marketplaces, again, the type of location of where to look for these disclosures can be a bit different, but we'll just jump into a few different options. So I know with this event specifically, there are vaccinated seating sections and non-vaccinated seating sections. So as you can see here, these two seats down here, there are some additional restrictions or limitations. So that's kind of a good idea or a good way to identify if there are any disclosures. So I scroll down again, mobile ticket, but then you see down here, full vaccination required to sit in this section. So this is gonna be their first place for you to go ahead and take a look, see if there is a requirement for these seats. These disclosures are there for a reason. When you get your ticket, it should also say it on the ticket itself whether there are any disclosures as well. So that should be another way for you to identify if you do or don't require to have any kind of COVID vaccine depending on the type of seats you're sitting in. Now, last two examples are both on vivid seats. They do things a little bit different, but it's still kind of the same thing. So I know that this section here, 420B, is a vaccinated section. You can see the disclosure right in front of you saying vaccinated section. You know that this seat's gonna have some kind of COVID vaccine requirement. So if you go ahead and drill down a little bit further, you can even see, it'll give you in the notes, it'll tell you right there, a vaccinated fan section, you require proof of vaccination. Now, going back to the Blue Jays, you know there are certain sections where there are vaccinated seating sections mixed in with non-vaccinated seating sections. So putting a disclosure on this entire section doesn't work in this instance. So instead, you gotta pay attention to see what the notes are. So what I'm gonna do, I'm gonna take a look at the disclosures. I can just jump into this section here and let's see. That means there is no requirement for proof of vaccination. However, if you go to a seat where there is requirement, such as one over here, you can see this section here, vaccinated fan sections. So again, disclosure is there. So again, be careful, make sure you pay attention to what you're actually purchasing. Don't just zoom through the entire process, assuming everything will be fine because it won't necessarily always work out that way. So that's a look into multiple platforms, how they actually go ahead and make those disclosures available to you. Again, if there are no disclosures being made in the notes section, specifically around fan vaccinated seating sections or a requirement for proof of vaccination, you can go to the assumption that those seats do not require it. But with that being said, one, always double check with the venue because they may have specific rules of entry into the venue and as well, do make sure that you pay attention to your tickets themselves, make sure when you get them, take a look at them, see if there is any other additional requirements. If there are and they weren't disclosed, contact your exchange immediately, see if everything is as it should be. If it is, congratulations, go ahead and go to the event, it's gonna be great. If it's not, they'll hopefully deal with it as soon as possible. If you guys have any questions at all, reach out to me below in the comments. Otherwise, hit me up on Twitter or Instagram, thumbs up run, I'll get back to you guys right there because I wanna make sure you guys can all get into your events safely and as smoothly as possible. If you guys enjoyed this video, definitely let me know by hitting the like button down below. Also, be sure to subscribe if you haven't already, great new content coming out every single week in. See you guys next time.


Welcome back to Science Live. I would now like to introduce two very special guests, the Vice-Chancellor Professor Paul Johnson and the Dean of the Faculty of Science Professor Tony O'Donnell. Welcome to Science Live. Future's vision is about ensuring that today's students get the educational experience that will position them for tomorrow's careers. So with Education Futures we're looking at how we use technology in the classroom and outside of the classroom, how we put students at the centre of their learning experience, their their own personal intellectual journey as they go through their opportunities here at UWA, how we give them all the skills that they will need in terms of analytical skills, laboratory skills, communication skills, so that at the point of graduation they will be able to make really good decisions about what their future career will be. For some it may be a further degree and research for others it will be going off to get a job with an employer but that job of course is only the entry point to a career and we want to make sure that our graduates have the capacity not just to get a good job at the entry point to a career but have the skills to go on learning, to go on focusing on questions, analysing complex situations so that they can build those careers, whatever path they choose. And we know that that means we have to change, we've got to make use of all the possibilities with new technology but technology is just one part of the Education Futures vision because actually what we also need to make sure is that and you don't get those just by interacting with the screen so the technology part is crucially important but so is the face-to-face learning experience with some of the world's best academic staff and also here at UWA with some of the very best students. Bright students learning with other bright students produce fantastic outcomes. Okay thank you. Although the word vision is used I know the vision is already started would you like to tell me about some of the education practices that are already in place at UWA for both our undergraduate and postgraduate students. So we're doing a huge amount across all the subject areas here at UWA obviously there's a lot of laboratory experience for science students and we're focusing on ways in which that can be built upon so that the laboratory experience isn't just kind of going through a formulaic set of experiments but so that students are given real world problems, they can work in groups, they can apply their knowledge with guidance from the staff to produce solutions to those problems then write up research papers around that so they get a real experience of how to address the uncertainties, the unknowns. Remembering always that what the future career will focus on whether it's a research career or a career with a major employer it's about bringing skills to focus on complexity. If no one employs pays a lot of money to employ bright graduates to solve yesterday's problems those have already been solved we know the answers. So graduates and there are many different approaches to this across our different degree programs to give students these insights in a sense insights into the unknown. For us the for the faculty the education futures vision is about anticipating the future needs of our students that includes the students that we have here currently but also the students that will be enrolling excellent staff here as the Vice Chancellor has mentioned. We are already teaching at the leading edge we are researching at the leading edge and as one of the world's best universities UWA wants to stay at the leading edge therefore for the faculty of science and I think generally for the university the education futures vision is about ensuring we remain one of the world's best universities both for education and research. In practical terms and I think this is what your question is about in practical terms what is it we're doing well basically we're looking at this from three different perspectives. First of all the the design and structure of our courses and this is something that the university and the faculty embarked on way before 2012. 2012 marked a milestone in us actually preparing for 2020 but 2012 prior to 2012 the faculties the science faculties were actually looking at how do we actually take students all the way through from where the students are today coming to find out about our courses all the way through their undergraduate degree into their postgraduate work and then into it then importantly into into employment. So one of the things that we have done and it's been a part of the faculty's strategy as part of its development has been to ensure that postgraduate degrees butt on to the end of undergraduate degrees so we have end on masters programs that actually provide a pathway and with the university's help we've actually managed now to make that is really quite quite efficient so I'm hoping today that some of the students that we're seeing at open day today will actually be thinking not just about where what they're coming into study next year as undergraduates but actually thinking about what sort of career do they want and what and asking the university and asking the faculty what can you do to help me get onto onto onto that pathway so specific examples are the way in which we've actually got masters programs that actually join our undergraduate programs the fact that we've got two majors fact that students have flexibility and choice in those majors so just imagine how the advantage a student would have actually having doing a major in the first major in say agricultural sciences just think how better off it is if they were the other way around as well actually come up to do business as the first major and then do agricultural science as a second major and we've actually started to see this year an increase in students wanting to do those sorts of options so it's not just science of business it can be science and arts and that's the that's the great thing about the new courses 2012 the other thing that we're focused on is actually the content of those courses we see many our students coming up now many different types of experience I think the way in which I was taught and probably Paul was taught just wouldn't be relevant today actually I was watching the videos earlier on from my office and the under 25s are much more relaxed sitting here in front of a camera than people like myself so I think you know we need to Paul mentioned adapting the technologies and introducing the technologies well we need to do we need to be very much aware this is the way this university needs to to move and I think the the 2020 vision is the education futures vision is a great way of actually rallying faculties and the staff around actually trying to develop that trying to as I said anticipate future needs of our students the other thing is around the content is if you look at some of the things we were trying to do one of the things the Vice Chancellor has asked us to look at is we often think about careers as what can I do with my degree you know so one of the things we are looking at now in order to get new programs up we have to have provide the university with a good examples of what these degrees might lead into what sort of jobs our students might do do with this and this reflects the fact that this university has a very high success rate in putting its students into employment and more importantly particularly if you're a parent those students actually start on higher salaries than than the national average but we're also looking at how to what the other thing that we've been looking at as well how can we actually help students start their own businesses so one of the things that Paul has been pushing is entrepreneurship and commercialization and to build that into our undergraduate and our postgraduate programs and we have some good examples starting next year so the masters of biotechnology actually is a program we have developed jointly with the business school so students will get taught state of the art molecular biology gene technology environmental technologies from some of the very best researchers in the world and but they will also from our business school be actually taught by professionals in in business administration but also in commercialization and spin out they will meet with business angels the faculty will run competition in actually trying to sponsor some of these these initiatives and the third thing we're doing is and it's again it's an integral part of the education future program and that is actually to ensure that all of our students have an enrichment experience of some sort the university is very keen on us spending sending our students overseas and this faculty has been I can't remember Paul what were we aiming were we aiming for 100% or 50% 50% we're currently at about 22% of each cohort of graduating students has spent some time studying overseas and you know we want to get that up to 50% yes so 50% of the students studying overseas now the other students we would expect to give a meaningful enrichment experience whilst they're here at UW and that might be an industrial and industrial placement so some of our masters programs do have an explicit industrial placement bit built into them the other area that we're very as a science faculty you might think is a little surprising but we actually are also developing a new masters in international development regional development again we've gone outside the faculty to actually bring in expertise from from politics because if you're involved in international development it's not just a bit climate change and agricultural productivity or urban planning it's also about that social political dimension so we bring staff in from from outside so the faculty has a fairly well developed plan to actually integrate and to build up that enrichment for our students as we go forward okay well thank you so much for both coming and sharing UW's 2020 vision with us thank you for your time today thank you there are over 10 000 universities in the world there are 39 in Australia and of the five in western Australia only one is ranked in the top 100 in the world the university of western Australia it's why our graduates are preferred by employers and earn higher graduate salaries choose wisely and you'll be career ready for life


You can turn your toy lightsaber into a high-quality build with Adafruit's ARPY 2040 prop maker feather and Circuit Python. This toy lightsaber features a detachable blade that we were able to upgrade with a strip of Neopixels. We gutted the toy's electronics and added the ARPY 2040 prop maker feather. We really like the injection molded parts, so there's no 3D printing in this project. The original blade only has around 20 LEDs, so we swapped them out for a strip of Neopixels for getting better animations that can be set to any color. The stock blade has white LEDs that show noticeable dark spots when compared to our Neopixel blade. The Circuit Python code has customizable settings for colors and you can adjust the sensitivity of the swings so you can make it match your preference. You can also swap out the audio files to make it super custom. To learn how to upgrade your toy lightsaber, go to learn.adafruit.com Get the parts to build this project, links are in the description. Start by removing the pommel, then remove the screw from the battery cover. The two halves are held together with just a few screws so it's easy to take apart. Carefully unplug the connectors from the main board and desolder the wires from the various components. You can splice wires to extend the cable from the pogo pin connector. Attach a 2-pin JST cable to the terminals on the battery holder so we can plug it into the feather. The wires from the button can be attached to the prop maker's screw block terminals. You'll need to cut the trace on the back of the feather to disable lipocharging so we can safely use alkaline batteries. Add another JST cable for the power switch and insulate the exposed pins with some capped-on tape to avoid shorting. Then we can plug everything together and close it back up. Take apart the blade by removing the screws from the pogo pin connector, then remove the plastic pin from the tube. Carefully slide out the diffuser and take out the LED PCB while keeping the cover and diffuser inside the tube. Now we can solder the wires from the pogo pin connector to our strip of neopixels. Then we can fit it into the diffuser sleeve and slide it back into the tube. Place the covers of the pogo pin connector back onto the blade and secure it using the screws. We think this makes our toy lightsaber so much better and really like how we were able to use most of the electronics. We hope this inspires you to upgrade your toy props with Circuit Python and the ARC-B2040 Promaker Feather.