Okay. So, who has a ham radio license? We've got quite a few hams here. Okay. So, there's no big surprises in this talk for you, but I hope you'll find something interesting in it. Who is studying for a ham radio license at the moment? Okay. And who's thought about starting to apply for a ham radio license? Who would like to? Okay. Very good. So, ham radio is a scientific hobby. It's non-commercial. Licence is required to transmit and anybody can receive without a license. Ham radio has a lot of things in common with free software development. Learning in education, experimentation, innovation, volunteering. And by the way, FOSSTEM is still looking for volunteers if anybody is interested. Technical excellence, science, and communications, of course. Ham radio plays a big role in emergency communications in many parts of the world when something goes wrong. Radio amateurs are the first on the scene. Hardware skills are optional. You don't need to know everything about electronics or constructing circuit boards or antennas to be successful in ham radio. Many people are interested in digital modes and things like software-defined radio, which is the purpose of this room today. You do need to know about the theory in order to pass the exam. Most hams only have a subset of skills. Some people are very, very strong with digital modes or software. Others have very good skills and workshops for building antennas. So people often come together through clubs and through their local community to put these skills together and build complete solutions. There are also national associations who join together many of the clubs. It's not a free-for-all. In the free software world, we often talk about the freedoms that you have with software. In amateur radio, there's no religion, no politics, and no entertainment. Otherwise, you can use it for social communications. So to speak to your friends and family if they have licenses, you can use it for experimentation, but you can't use it for other types of broadcasting. So it's not as free as the freedom in free software. This is an overview of the radio spectrum. One of these little dongles, which I'm going to demonstrate shortly, will pick up everything from about 24 MHz somewhere about here all the way up to maybe 1.7 GHz. With an up converter, which you can add to the dongle, like this, you can start getting signals from down here as well. So propagation is a big topic in amateur radio. At those lower ends of the spectrum, the longer wavelengths, you can make contacts all around the world with signals that are reflected through the atmosphere at various times of the day or night. On the higher frequency, so VHF and UHF, you can make local contacts, often with a higher quality using an FM mode, but you won't get the same distance. You won't get signals reflecting through the atmosphere and going all the way to Australia. On the other hand, you can bounce those signals off the moon and they'll come back if you have enough power. There are many different modes. Yeah, it's okay. There are many different modes. CW or Morse code is the most basic. You've got single sideband, frequency modulation, packet data, which is a digital mode and television, and you can do all of these types of transmission with amateur radio. The dongle here only costs about $20. The quality of the signals you receive will depend to a large extent on the antenna that you use. With a little antenna like this, which will cost you about $5, you can do a very good job of picking up a lot of signals in your local area, so for a few hundred meters around where you live. If you create a more elaborate antenna like this, this is a 20-meter loop antenna that I've constructed myself using bits I purchased off the internet. If you use the right cables and connectors and you attach this to the up converter and then into the dongle, you can receive signals from all around the world. I'll just pull this out so we can pass it around the room. The way this was constructed, I purchased a 25-meter roll of enamel copper wire. It costs less than €10. I purchased a box of these little insulators of eBay. Once again, you can get boxes of them for less than €10. This is a ballon. It connects from the enamel copper wire to the coaxial cable like this. The costs of those vary. This one is rated to transmit up to 300 watts. Something that can transmit more power might cost more money. There are also some cheaper ones that are not suitable for transmitting. That one was about €30. I get the measurements off a website and just cut the wire to the right length and strip off these little bits on the end of the wire, put them into the terminal blocks on the ballon. It's tied on here for strength and support, and then it's connected into the little terminal here for electrical contact. Would anyone like to help me pass this around the room? Just try and unroll it somehow. It's a loop. Just hold that together. If you sit and just take it around the room, you can keep that end here. We'll just show how big it is. Just try and unroll it. I spend a few minutes on this just to emphasise that a lot of effort goes into making the antennas because this is a big part of success in amateur radio. With a large antenna like this, even with a couple of small bits and pieces like this that I've purchased off the internet, I really can receive signals from all around the world, but I wouldn't normally operate the antenna in the room. I'd have it outside somewhere or possibly in a rooftop or on a balcony. The transmission line that you use also makes a big difference to the success of your radio system. This is a very thin 50-ohm coax. Most amateur radio systems use 50-ohm, so not the 75-ohm coax you'd use for TV. But this one's quite thin. We'd use a larger, thicker coax for this type of HF reception, especially if we had to run the cable 20 or 30 metres. You can see some of that outside where the local amateur radio club have set up a booth and they've got a mast outside the building. Did anyone see the mast when they were coming over here? These little connectors, they also make a big difference to your success. If you buy really cheap ones off eBay, I'd suggest you test them thoroughly because they may be holding you back if they're not working. How would you know? How would you know? You'd need some test equipment or if you actually have positive results, then you might have a good sign that it's working. If you're transmitting and you use something like the SWR metre, that might also give you clues that your connectors are not working well, but you don't know if it's the connector or the cable or the antenna. This is a block diagram of a radio system, so a real radio, not a SDR. So there are a number of oscillators, mixers, finally a FMD modulator, and eventually we get an audio signal. So that's just for receiving. A transmitter block diagram looks similar, but in reverse. SDR is a lot simpler. You've got a filter, some amplification, an oscillator and a mixer, and then an analog digital converter. And everything else from that other block diagram is then done here in the software. So these are the RTL-SDR dongles. Who has one of these already? Okay, everyone in the room. Who doesn't have one? Anybody? Yes. So they're very easy to get. If you're purchasing one of these, you'll find the most generic ones for TV reception are less than 10 euro. But they don't have the stability to get narrowband signals from transmitters like this. So that's why we buy these slightly more expensive ones, which are about 20 euro, made for the purpose of SDR, not just for TV reception. They basically have a different crystal oscillator in them with more stability. They have a better case. And they have the SMA connector, which allows you to connect to most of the antennas and other things you'll be interested in. So a little bit about Debian. It's one of the things that brings me here today is Debian. In Debian, we have a whole operating system. We have over 20,000 packages. Everything is free software. So we guarantee that we give you the source code for everything in Debian. We have a big process for producing Debian and for ensuring the quality of a stable release of the Debian operating system. Within the Debian community, like in every community that you'll encounter in the free software, you'll find a few radio amateurs. We've got about a thousand Debian developers, so we've got quite a few radio amateurs in there. And we've grouped together to produce packages of stuff that's interesting for other radio amateurs. That's the Debian Hams team in Debian. And what we have is a blend of Debian, which means you can actually build a Debian CD that comes pre-installed with all the stuff you'll be interested in ready to run in the shack. You can run it from a CD or DVD. You can put it onto a USB stick, put it into an old computer in the shack, and get up and running right away. Now, who uses Debian already? Who uses a derivative of Debian like Ubuntu? So it's well known that Debian freezes every two years, and then everything sits there at the same version for two years. And in a fast-moving area like SDR, you may not be satisfied with that. You may want cutting-edge releases of things. We have a way of doing this in Debian called the Backport System. So we actually build backports of the cutting-edge releases of things on a stable system, and then we release that into the Backport's catalog so you can very conveniently install those packages with the same apt-get utility that you use to install any of the stable packages. So you can see an example here from GQRX, which is an SDR application. The stable release of Debian has version 2.3.1. The latest version is 2.6. And the Backport, which is a BPO here, is also 2.6. So somebody who installed the last stable release in 2014 can get this immediately without any compiling. So this makes the Backport very relevant for fast-moving fields like SDR. So going on to the demo, how are we going with the antenna? Where did the antenna end up? Down here. Any questions about the antenna? Okay. One question. Do we have a microphone for questions? I'm afraid no. You have to repeat them. Okay. It's a power and you have to use what you need to mix them. So this device, especially when you are transmitting for high power, the signal is already very low power. So how do you mix this with this antenna? Because the device do it itself. This antenna, so he's asked me about transmitting with high power. This antenna would not be used for a high-power transmission. This other antenna can handle high-power RF.   Thank you. But you actually have to check the thickness of the wire that you use for building an antenna like this. Like this one, you can see it's actually not that flexible. It's not a really thin wire. Like if you opened up a wire from your speakers and pulled the bits of copper apart, they're a lot thinner than this. This is actually quite thick and can handle a few hundred watts of power. I'll come back to you after the demo. Yep, okay.


Hello and welcome to the session. The question says integrate the following function and the function is 4x plus 1 upon root over 2x square plus x minus 3. So let's start with the solution and we have to integrate the given function so we have integral 4x plus 1 upon root over 2x square plus x minus 3 into dx. Now let us put t is equal to 2x square plus x minus 3. So differentiating both sides with respect to x on the left hand side we have dt upon dx and on the right hand side we have 4x plus 1. So dt is equal to 4x plus 1 into dx. So this integral can further be written as integral dt upon root over t which is further equal to integral t raised to the power minus half into dt. This is further equal to t raised to the power minus half plus 1 upon minus half plus 1 plus c since integral of the function x raised to the power n with respect to x is equal to x raised to the power n plus 1 upon n plus 1 plus c. Thus we have root over t upon 1 by 2 plus c or we have 2 root t plus c and t is square plus x minus 3 thus on integrating the given function we get the answer as 2 into 2x square plus x minus 3 plus c. So this completes the session by intake care.


Hi, my name is Sapir and I'm going to tell you about Statistically Center for Advertisement transfer from LPN and the Randomization. This is a joint work with Neobitansky. In this work, our goal is to expand the reach of the Learning Party with Noise Hardness Assumption or LPN in short. And we hope we can contribute to the ongoing research of this problem. It's a long-studied problem and it's highly related to the well-known problem of decoding random binary linear codes. It's one of the few candidates who are considered to be resilient to quantum attacks. And also we should keep in mind it's twin problem NWE. And generally speaking LPN is far behind NWE, both in terms of known applications. We know how to construct many more applications from NWE and also in terms of hardness results. So generally speaking we much better understand NWE, but we also want to understand better the problem of LPN. In this work we focus on two methods, Statistically Center for Advertisement transfer or SSPOT in short. This is an oblivious transfer protocol where we really take the round complexity and the security to the extreme. It's a two-message protocol meaning that each party is allowed to send only one message. And we consider the best possible security guarantees for such a protocol meaning that the receiver choice bit is kept computationally hidden while the sender second message is kept statistically hidden. This is a very short protocol and very secure and therefore it's not surprising that it found many applications in cryptography and especially towards reducing the round complexity of cryptographic protocols such as proof systems, pure computations, hard problems in statistical zero knowledge and more. So the question raises up here and that we try to answer in the paper is can we construct Statistically Center for Advertisement transfer from the learning party with noise assumption? And it turns out that generally the answer to this question is yes, we can. And in the paper we show the following two results. So first we show that we can construct a two-message Statistically Center for Advertisement transfer in the common random string model using just LPN. And then we show that we can actually remove the CRS using a standard Nissan Vignette on-style randomization assumption. So overall we get that we can have an SSPOT protocol in the plain model using LPN and the randomization. Now just let me tell you a bit more about the results. So first we should mention that there is a caveat to our work and it is that we rely on LPN in the so-called low-noise regime. But it aligns with our current understanding of the problem of LPN and I'm going to expand more about it in the talk. Still this is the first quantum secure SSPOT construction that is not based on LWE. And we use different proof techniques from LWE and we hope they can be useful in the future research of the problem of learning party with noise. Thank you very much for listening and hope to see you in the conference.


In this video, I'm going to show you one trick that's going to help you become a better facilitator in just eight minutes.  What you're going to see next is a video from our course called Workshopper Master, which is basically a program that teaches people how to become master level facilitators. And this is going to be one of the six laws of master levels facilitation. And these are often the things that people who learn facilitation don't think about. So these are sort of uncommon or counterintuitive things that people often just forget about. And it sort of makes their workshops less interesting. Okay, I don't want to waste any more time. I want you to be a better facilitator eight minutes from now. Let's go. Law number three, start strong and stronger. This is one of the easiest laws to implement, but also the law that 90% of workshops forget. This law relies on two phenomena of the human brain. One is called the serial position effect. And the serial position effect basically means that people tend to remember the first few things and the last few things in a series. This can be numbers, this can be events, this can be a whole day at Disneyland. They generally remember the start and the end more than anything else as the first phenomena. And the second phenomena is called the peak end rule. And the peak end rule basically says that people don't remember an experience based on all of the individual moments of an experience. So for example, they won't remember the workshop because of all the individual moments. They'll remember one peak, meaning one high point, and they'll remember the end and pretty much nothing else. Two of these things combined mean that if you get the start right and if you get the end right, you've basically covered 80% of the things that people are actually going to remember about your workshop. And this is why at AJ & Smart, we try to make sure our workshops start strong, start memorably, and they end strong because they're going to forget everything in the middle anyway. And really the start and the end are the way you can really build in powerful moments that people go away with and think about forever. So to repeat, start strong, end stronger. This literally means the ending is the most important part of your workshop. The starts, of course, important, but even if you manage to mess that up, you need to stick the ending. People will leave feeling like it was the most amazing thing they've ever been part of, if you can get the end right.  Well, people are still going to remember the start, one peak, and the end. And if these were nothing special, then the workshop will feel like nothing special. They'll feel like it just passed like a blur. And even if you got stuff done, and even if it was really interesting, and even if you actually achieved your task of solving the problems and doing whatever you were asked to do, they're still not necessarily going to have interesting memories if you don't start strong and end stronger with your workshop. So let's have a look at some things you can do to actually make this happen. Tip number one is to end with a highlight session.  Then simply point at parts of the agenda. So for example, if you ran the expert interview session in the morning, simply point at that and say, hey, this morning we started with expert interviews. What's something you remember? What's something you enjoyed? What's something that changed when you did this exercise? And you asked the group and always someone will put up their hand and say, actually, for me, it was really interesting to see that I was able to get all my ideas out without talking. And so what you've done is you've had someone in the group create a highlight for you and it feels good in the group. Then I'll go to the next section. Okay, we did the map. What's something positive that someone remembers from the map? What's something that stood out for you? What's something that was different from how you normally work? Someone put up their hand and they'll say, hey, this is what I remember from it. And the cool thing is by the time you get to the end of the agenda, people in the audience or your participants have basically highlighted peaks and interesting points during the workshop for you and for everybody else. And this leaves everybody going home with a really good vibe of the highlights and the memories and interesting things that happened during the workshop. And it also allows people who had special experiences during certain moments. It basically allows them to talk about their peak, which maybe other people didn't have. And that basically gives other people the experience of, oh, yeah, there was this cool moment that happened there. And it really locks in some really nice memories at the end of the workshop. So one great way to end stronger is to go through the agenda of the day of everything that you've completed.  Give yourself a clap. Now, what we want to do is just go through and remember some of the things we did today. In the first exercise in the morning, we did how might we use what's something you guys remember from that and just let them talk about it. So that first tip is really just asking people to summarize parts of the day for you and for the group. It's a killer way to end the workshop. It sounds boring, but it always works really well. Tip number two, and I really love this one and it's again focused on the ending. And this is really you showing the progress that happened in the workshop. We do this in a couple of ways. If we're doing an in-person workshop, we'll take a photo of the empty room before the workshop started and the empty room with the people in it before the workshop actually started. The walls are empty. There's nothing there. Nothing has happened yet. Then we'll take a picture of the full room with all of the workshop materials and I'll simply show that on a slide at the end of the workshop. And I'll say, when we got here this morning, how did you feel? You know, what did you think was going to happen? You know, we talk about what happened before and I talked to them. Like, what were your expectations? Then I showed them the picture at the end of the day and I really highlight how far they've come. When you came here today, you had all of these broad ideas. Right now you have something tangible. You're moving forward. You all did amazing work. Here's what the room looks like. Here's what the day looked like. So I essentially take pictures in an in-person workshop or I take screenshots of the Miro board for a remote workshop and I show them that at the end. Here's what the Miro board looked like just three hours ago. We had nothing. Now look how much progress we've made. Look how much we've moved forward. It's a really great way to lock in the feeling of progression at the end of the day and give people the feeling of pride that what they've created is something special. It's a great way to like put a cap on the end of the day because it really should feel like closure. It shouldn't just fade out because sometimes the last exercise in the day can be a tough one. You really need to close down the workshop properly and showing the progress that people have made. Like the previous step, asking them for the highlights but doing it visually is another fantastic way to end stronger. Tip number three is find the rituals that work for you for the start and end of a workshop. At AJ and SMART for example, when we're running in-person workshops, the start of the day is where the best coffee is. So at the very, very start of the day, that's where we actually make really good coffee from roasted beans with proper milk and everything. And then throughout the day, we kind of settle on just straight up pre-made coffee straight from a machine. So at the start of the day at AJ and SMART, one of the things in our rituals is coffee and that's how we started. Another great way that we start workshops is we use warm-ups that we know get people into the moment very quickly. Another thing is if you're running a remote workshop, a great way to get people excited, especially if you're all over the world, is really think about what could you get delivered to someone's house in the morning before the workshop starts to simulate this feeling of having some nice food, nice coffee at the start of the day. It's really about taking care of the fact that something has started and something has ended. And really so the best coffee, the best food for us is always at the start at the end of the day. Another thing we sometimes do at the end of a workshop is a little meditation. We'll do a little exercise where we have people write like where they wanna be in two years. It is all these little things, but really have rituals up your sleeve that you can test at the start and the end of workshops and don't be lazy about it. Seriously, the amount of workshops that just fade out and fade in, it doesn't make sense if these are the moments that people are going to remember. You have to start strong and end stronger and that is law three of master level facilitation. All right, if you liked that and I hope you did and I hope you got some value out of it, down below this video, there's a free training which will give you a much bigger insight into the different laws and all of the different things that we teach in our online programs around facilitation. It's a one hour free training and there's a lot more than you just saw in this video. So if that's your sort of thing, definitely check that out. And finally, let me know if this video was useful to you. We need to know that sort of stuff in the comments. It helps us figure out what other types of videos to put out. Thank you so much. And did you notice that I have braces now but I didn't have braces in that video? Did you notice? See ya.


So one of the nice things about the fundamental equation for the Gibbs energy in this case or in any of the energies is that it immediately tells us several or a thermodynamic derivatives. So for example, reading directly off of this equation, derivative of g with respect to p at constant t is going to be this coefficient v. So we know the rate at which the Gibbs free energy changes when I change the pressure of an object is the volume of the object. So let's see if we can understand what that expression means a little bit. Typically, the way we'll use that expression would be if we exert pressure on something, change the pressure on an object. And we want to know how much is Gibbs free energy changes. This is the equation we can use to determine that. So we'll rearrange this equation, for example, to say dg is equal to vdp. That, of course, is exactly like this equation if I ignore the temperature term. So if we're at constant temperature, either because I'm ignoring this term or because I know this derivative, Gibbs free energy change is volume times change in pressure. If I want to know the finite change in pressure, changing Gibbs energy rather than the infinitesimally small changing Gibbs energy, I just need to integrate this expression integral of vdp. So what do we do with this? There's a couple of things we could do. One, if we can assume that the thing I'm changing the pressure of is relatively incompressible. So for example, let's suppose I have a bottle of water. I can exert pressure. I can squeeze on this water bottle and I can't change its volume very much. So water doesn't shrink. Its volume doesn't change very much as the pressure changes. So if I squeeze the water, it's not going to change its volume very much. We say that water is not quite perfectly incompressible, but close to an incompressible fluid, in which case I could say since the volume is not changing as I change the pressure on the bottle of water, I can pull the v out of the integral. v doesn't depend on the pressure. And then integral of dp is just delta p. So for example, let's work a numerical example. Let's say I have this bottle of water, which the label tells me is half a liter, 500 milliliters. If that bottle of water is at room temperature, if it has a volume of half a liter. And if I squeeze the water bottle, so right now it's at a pressure of one atmosphere. And I'm going to exert pressure. I'm going to squeeze on the bottle, exert a pressure. Let's say I squeeze hard enough to be exerting a pressure of two atmospheres. The question is, how much have I changed the Gibbs free energy of the water in a bottle? So what is delta G? Well, we have an expression that can answer that question quite simply. It's just volume times the change in pressure if I can assume the water is incompressible. So that's going to be half a liter multiplied by the change in pressure from one atmosphere to two atmospheres, so that's one atmosphere. That will give me the Gibbs free energy change in liters times atmospheres, which is not a unit of energy, but it's not the most convenient unit of energy. To convert that to a more convenient unit of energy, I need to convert liter atmospheres to joules, for example. And we could look up a conversion factor. There's 101.325 joules in a liter atmosphere. What's convenient, often, is to remember the gas constant 8.314 joules per mole Kelvin is the same as the gas constant 0.08206.08206 liter atmospheres per mole Kelvin. So this many joules is equal to that many liter atmospheres. That ratio is 101.325. So 0.5 liter atmospheres times 101. That works out to a couple of sig figs to be 51 joules. So what we've been able to figure out is that I've raised the free energy of the water in this bottle by 51 joules when I squeeze on it and exert a pressure of two atmospheres rather than just the one atmosphere that the room air is pressing on the bottle with right now. So we can calculate the Gibbs free energy change when I compress, when I increase the pressure on an object, if it's incompressible. Not everything can be treated as incompressible, however. If this bottle contained not a liquid, not an incompressible liquid like water, but if it contained a gas, maybe an ideal gas, then we would have to make a different assumption. The good news is we can still do that. If we back up to before we made our assumption that the liquid was incompressible, this result is always true. Free energy change is volume times dp integrated from some initial pressure to some final pressure. If we don't pull the v out of the integral, if we acknowledge that the volume might in fact be changing as I change the pressure, as I increase the pressure, the volume is going to decrease for something like your gas, the volume is a function of pressure, so I have to leave it inside this integral. If it's an ideal gas, so here's our second set of conditions, for an ideal gas, we know exactly what the volume of an ideal gas is. It's nRT over P, but that's an integral we can do. If we've done this at constant temperature, the n and the R and the T can come out of the integral. Integral of 1 over P is just natural log of P. And if I evaluate that from P1 to P2, lower limit P1, upper limit P2, ln of P2 minus ln of P1 is the same as ln of P2 over P1. So this expression, delta G is positive nRT, log P2 over P1, that's an expression we can use for the free energy of compression of an ideal gas. This expression would be the free energy of compression of an incompressible object. Let's go ahead and work an example comparable to this one. Let's say that we had half a liter of an ideal gas, still at 298 Kelvin. And again, I want to raise the pressure from one atmosphere to two atmospheres. Same problem as before, but now I'm squeezing a gas. If I imagine that this water bottle is now filled with air instead of with water, then when I squeeze it, exert two atmospheres of pressure on it, the volume will shrink quite a bit. So this is the equation we would need to use. In order to use this expression, I'm going to need to know how many moles of gas are in the container. So I know V and T and P, so I can calculate the number of moles. PV equals nRT, so n is equal to PV over RT. One atmosphere times 298. Sorry, one atmosphere times half a liter divided by the gas constant divided by 298. We don't need to spend time doing ideal gas law problems, so I'll just tell you what the answer. That gives me 0.02 moles of gas in this half liter bottle at room temperature. So that's now enough information to calculate the free energy change when I compress that gas. It's nRT log P2 over P1. So putting numbers in just to make sure the units work out. So I've got 0.02 moles of the gas. The gas constant I'll use in this case is because I want the answer to come out in joules. I'll use the gas constant in joules, 8.314 joules per mole Kelvin. I'm multiplying that by the temperature of 298 Kelvin and also the natural log of this ratio of pressures, P2 of two atmospheres divided by P1 of one atmosphere. So let's double check in this natural log. Atmospheres cancel atmospheres. The natural log is of a unitless quantity, as it should be. In the nRT product, moles cancel top and bottom. Kelvin cancel top and bottom. And I'm left with an answer in just joules. And if we do the arithmetic, it turns out to be the case that the free energy when I compress a gas inside this container changes by 35 joules rather than the 51 joules when I compress the liquid. So those are the numerical answers. One interesting question we can ask is why does the free energy change by less when I compress the gas than when I compress the liquid? One way to think about that answer is the rate at which the free energy changing, the free energy goes up. Volume is positive. So the free energy is always going to go up when I increase the pressure. The rate at which the free energy is going up is the volume of the substance. For the liquid, the volume was always the same. I could squeeze harder and harder and harder. Every additional atmosphere of pressure I add increases the free energy by the same amount. But for the gas, when I increase the pressure, the volume keeps shrinking. So the fact that the gas has shrunk, that its volume has decreased as I began squeezing on it, means the free energy starts rising less and less because the volume is smaller. So the reason the free energy goes up less for the gas than for the liquid is because the gas actually does shrink, can be compressed as I exert pressure on it. So we have two different expressions now. We have, I guess, three different expressions. This is the most general expression. If we want to know how the free energy changes as we change the pressure, this is always correct. If we make assumptions that the substance is incompressible or an ideal gas, we can arrive at two different results. In other circumstances, if the pressure dependence of the volume had a different form other than the ideal gas behavior, as it will for other substances, we could obtain other expressions still.