this is bbc news. the headlines: dramatic new footage has emerged of the momenta dam collapsed in brazil, killing at least 110 people. around 200 more are still missing after the wave of mud and slurry surged down the valley. the fact—checking website snopes and the associated press say they are cutting ties with facebook. media reports last year suggested that fact checkers working with facebook have been frustrated by its lack of transparency. the united states has suspended a landmark nuclear weapons treaty with russia which has been in force for three decades. announcing the move, secretary of state mike pompeo said russia had six months to demonstrate it was complying. we have lots more on our website and

you can follow me and some of the tea m you can follow me and some of the team on social media. now on bbc news, it's time for click. this week, barriers without walls. teentech trump the border? how microsoft came back from the dead —— can tech. and the magic behind the avengers. the construction of all wall at the us- the construction of all wall at the us— mexican border has dominated american politics since donald trump joined the presidential race back in

2015. we are going to build a great border wall to stop illegal immigration. it reached its crescendo in december when the now president announced the federal government shutdowns over its funding. we are going to have a shutdown. there's nothing we can do about that. a record 35 days later it was finally lifted, without any real resolution, and it could easily be back on within weeks. as trump tweeted out a new design for his wall, now made of steel rather than concrete, the democrats did offer a potential compromise, to find a border which used technology rather than physical barriers. but is that feasible, and what would it look like? we spent nick to arizona to investigate. so i'm on my way to the border patrol station, one of the

most technologically advanced control centres on the us — mexico border. the checkpoint itself processes hundreds of thousands of people every month. but today, i'm going on a ride along with agent dan hernandez of border patrol, whose job it is to keep out those attempting to cross illegally. just be advised i am going to be around your location. we have 262 miles of border fence with mexico but thousands of miles on the north and oi'i thousands of miles on the north and on the american side. it's a daunting task, and it's very vast, but with a technology we are able to get a leg up on our adversaries —— with the technology. dan's patrol zone is larger than the state of new jersey. his sector of duty, to zogg, made almost 40,000 arrests in 2017 —— tucson. 0ut made almost 40,000 arrests in 2017 —— tucson. out in this unforgiving terrain, field agents like him go

about their daily patrol. every piece of technology used by them is vital and has to be reliable, even down to the radio calls. this has encryption stronger than most police department because of the national security concerns, because of the criminal element. you have a radio thatis criminal element. you have a radio that is equipped with gps, so if something should happen, i become incapacitated, the press that button and help will come. help will come from here. the nogales control centre, where officers can literally see what is going on, thanks to a newly updated surveillance system. the solar powered integrated fixed towers, also known as ifts, have long skirt —— large—scale cameras coupled with radar to provide high altitude points of view with watchful eyes back at base. we are tracking systems that can detect movement, and it places the camera at the source of the movement.

therefore, we would see some pixelation, the cameras, just by the remote nature of their placement, it was very difficult to focus far away. but with technology, we have increased the amount of distances we can see and the accuracy of the images, and we are seeing really crisp, sharp images. so we are able to identify things that come over the fence, people that come over the fence, contra band that the fence, people that come over the fence, contraband that comes over the fence. and not only that, but it increases safety. if i go out to an area andi increases safety. if i go out to an area and i don't know what i'm waiting on and i don't know what's out there and i run into an assailant with it might be a bad situation, but if i know that prior to going in there, i might be able to going in there, i might be able to bring other resources with me. as well as saving agents' time and potentially saving them, the ifts have helped secure areas where physical barriers are not. down here, fencing has been raised to prevent erosion from water flow, but a person could easily walk through here. for all intents and purposes,

we consider this defence, the wall. we don't want to think this is keeping america safe, we have the fencing is a tool, as another system we can utilise, but it by no means as opposed to keep anybody in or out. we are the force with the agents, in conjunction with the technology, and this being utilised asa technology, and this being utilised as a tool, that seamless integration of all three components is what makes the border secure, is having the agents to make an arrest, the wall, and then the technology to supplement earth. this could bejust a couple of miles it could be a couple of hundred yards. five minutes down the road, then shows me a border section where technology is already having to do most of the work in keeping people out. just looking at this, this is completely not what i was expecting to see, i guess when people have visions of the wall or, you know, the mexican border, the us mexican border. like isaid, the border, the us mexican border. like i said, the presence of the fence isn't here. it's not a very powerful

fence, by any means. it'sjust isn't here. it's not a very powerful fence, by any means. it's just meant to keep vehicles out. while these sticks won't stop determined individuals, i'm told scattered sensors buried in the ground all around the area could catch them offguard. technology is intended to help agents do their duties, but of course, it is not always committal that get caught in the net. the recent migrant caravan crisis highlighted how many families make the perilous journey and highlighted how many families make the perilousjourney and hope highlighted how many families make the perilous journey and hope for a better life in the us. many have been torn apart and some children have died since being detained by authorities. for dan, he says he is just doing hisjob. authorities. for dan, he says he is just doing his job. no matter on what side of the spectrum you follow on, border security is important for the entire country. we are law enforcement officers, we don't dictate the law, we just enforce the laws. so the best way to enforce the laws. so the best way to enforce the laws is by doing it are the most effective and most efficient way. in 2017, border patrols seized over

890,000 pounds, or 400,000 2017, border patrols seized over 890,000 pounds, or400,000 kilos, smuggled drugs across the us— mexico divide. drug mules, they try to camouflage themselves into the natural environment, so a lot of times you may not be able to see them, but the cameras can detect body heat and infrared technology allows us to see them in the middle of the dark knight. so our technology is usually one step above the criminal element. as well as giving agent eyes on from a long—range of rural terrain, imposing structures like them have also been used to mitigate crime in urban areas. nogales is a city divided into back. on the us side, 20,000 residents. 0n the other, 210,000. so it is up that hill there isa 210,000. so it is up that hill there is a rvss tower, remove videos of evatt and keeping a close eye across this area which historically has

been quite dangerous. but having an eye in the sky has helped improve safety. 0r eye in the sky has helped improve safety. or so i thought. you have the tin roof there. yes, those are rocks. yes, those are all rocks thrown at agents. 0k, we got to get out of you. you've got to go, you've got to go, you've got to go. so actually... we actuallyjust heard a rock lender but that barrage they are, so obviously people up there are, so obviously people up there are throwing stones at us —— rock land on that garrard shved. no-one is that, just be advised. —— garage there. this is an area when people involved in human smuggling are purged, andi involved in human smuggling are purged, and i believe there is one person underneath that treaty. so he isa human person underneath that treaty. so he is a human smuggler scout. others that feel, knowing there is a guy who is watching you? it is a co nsta nt, who is watching you? it is a constant, they are other all the time. you get more and more used to

it. while scout may sit for hours at a time, people crossing the desert moved from is place to place, so border patrol have mobile surveillance trucks to reach remote areas. they are equipped with thermal rangefinders, enabling operators to measure the difference between themselves and people crossing —— distance, and laser pointers, to give agents in the field wearing nightvision goggles ahead up. won multiple surveillance capability truck can do the work of six people, all four people. customs and border protection has also begun testing drones with facial recognition cameras to help monitor the borderfrom recognition cameras to help monitor the border from an even recognition cameras to help monitor the borderfrom an even higher vantage point. and border patrol is trialling a new mobile —based navigation tools to agents can keep track of each other‘s live whereabouts. the border is changing every single day, and with technology or investment in technology or investment in technology allows us to keep up with the trends, with the smugglers, with counteracting any kind of negative action towards the united states at the border. while trump's wall continues to be a bone of

contention, maintaining the border stretches beyond can be erecting more steel fencing. as i have come to learn, communication tools and surveillance systems play a pivotal role in everyday operations. whether technology can replace a war altogether here is something which will be debated in the coming weeks. —— replaced a wall. hello and welcome to the week in tech. it was the week that samsung announced a giant,1 the week that samsung announced a giant, 1 terabyte internal storage chip for smartphones, apple acknowledged the flaw in its face time software which allowed eavesdropping, and the usjustice department filed criminal charges against chinese company huawei and its chief financial officer. the company and its cfo deny the charges, which include bank fraud, obstruction of justice charges, which include bank fraud, obstruction ofjustice and theft of technology. the facebook research page 13 to 35 —year—olds were almost com plete page 13 to 35 —year—olds were almost complete access to their

smartphones. the app is now no longer available on its app store. previously, the social network could let people install apps without going through apple. meanwhile, mit has made an inflatable pills to monitor the interior of your stomach. the sensors inside the ingestible tablet can potentially monitor problems inside the tummy forup to 30 monitor problems inside the tummy for up to 30 days. it rapidly absorbs water once inside the body, and to deflate, patients simply drink the calcium solution to shrink the jellylike bill back to a size which can go out the other end. 0ne more robot story for you from the italian institute of technology. it has unveiled a soft robot which mimics plant handles. the plastic tube stretches when electricity passes that it in coils when the voltage is removed. researchers hope it could eventually help develop wea ra ble it could eventually help develop wearable devices that can change shape. so i get the jazzy bright

yellow headphones. i am in seattle with amos miller and his guide dog, trevor, and i'm about to try soundscape, a navigation at that uses no visuals, just 3d sounds. 0k, so i'm hearing voices. the over lake transit centre is 200m that way. as i turn transit centre is 200m that way. as iturn around, transit centre is 200m that way. as i turn around, the phone are just the stereo sound so that the speech appears to keep coming from the correct direction. having it in 3-d space in that way makes it really effortless to know where things are. you don't have to do calculation is in your head, and engage with them. you can just hear where in your head, and engage with them. you canjust hear where it in your head, and engage with them. you can just hear where it is. this 3-d you can just hear where it is. this 3—d audio is called dynamic binaural sound, and we are now going to use it to find our way to our destination. now, instead of giving you step—by—step instructions, the way that soundscape works is it will place an audio beacon, a virtual

audio beacon, on the destination. so you can hear where it is, and we can decide how to get there. beacon, 210 metres. i am hearing it. which side are you hearing? and it really is quite instinctive, just head in the rough direction that the sound is coming from. i think it's in this direction here. ok. so do wejust walk in the direction? so now, we use our analytical skills to pay attention to what's around us. right, we don't just attention to what's around us. right, we don'tjust walk into that tree there. we don't walk into that tree. trevor, my dog, is pretty good at avoiding trees. so should we go? ido at avoiding trees. so should we go? i do know, dogs entries, they kind of... you know. what is incredible is if he had never tried binaural sound, the trapping stays in the direction it should be coming from. i'm sorry, i overshot. this is augmented reality

and audio and it's a great idea. the sound is instinctive and unobtrusive which means we can have a chat without stopping and listening to spoken instructions. find the doll, boy. he's arrived. that is, in the true sense of the word, a beacon. and audio beacon that would follow it as if someone is calling us. exactly. so, you may be asking, whose headquarters and my out? which cheeky start—up has come up out? which cheeky start—up has come up with this idea. remember these guys? yes, microsoft. go on, admit it. you thought they were so last century, didn't you? paulallen it. you thought they were so last century, didn't you? paul allen and bill gates's company to find an era with all conquering windows

operating system for pcs but now we all use google and apple phones which have left microsoft way behind. microsoft are, by the time other smartphones came along, very complacent. they the successful softwa re complacent. they the successful software business with office and windows on the xbox and it couldn't manoeuvre the way a smaller, more focused company kind of good. you getan focused company kind of good. you get an established business doing one thing, you put all your efforts into doing that one thing and then you struggle to manoeuvre or anticipate the new technology that is coming along and that may disrupt it. about 25 years ago, they were on top of the technology industry and now where are they? it turns out they are back on top of the technology industry. never mind apple, forget google and facebook,

at the end of november 2018, microsoft became the most valuable company in the world for the first time since 2002. so where did it all go right? well, i'd say about here. five years ago, the new boss was able to turn the tanker around. any ceo sets the direction. steve clayton is microsoft's storyteller is wales versed in explaining microsoft's resurgence that has seen it triple since nadella took over. where this guy started the wave and the sky missed the wave, this guy was determined to catch the next big one. cloud computing. it turns out it's not devices that a mobile, its people at a mobile and what the cloud has allowed us to do is to put

softwa re cloud has allowed us to do is to put software anywhere on any device. nadella seemed to accept that to move with the times, the company was going to have to do what it did in the beginning and be guided, at least in part, by the youngsters. let me show you a demo. young employees like this one which led him to win the company ‘s fourth internal hackathon in 2017. we are on these live streams, understanding them pixel by pixel and finding interesting moments and showing them to people. the result is the hype zone. that means fans of the most popular games in the world such as fortnite, mean they can use the microsoft —— the microsoft site max —— mixerto find microsoft —— the microsoft site max —— mixer to find the best battles. the game is kind of boring during the start. it gets really interesting. during the endgame,

there are only two or three players left so they try to use this technology to identify these super exciting and games. and any microsoft employee with an eye —— with an idea can come to this space, the garage, to hack, and work on ideas. is there any workable than a garage? that would be the batcave. i'm looking at a visualisation of global worked —— earthquakes over the last 50 years. microsoft changed the last 50 years. microsoft changed the way we worked once with windows and here is one possible workspace of the future. using its augmented reality headset, this is a glints of how our computing workspace may one day be all about physical space. today, we havejoining us, some of my team—mates. today, we havejoining us, some of my team-mates. jinna in new york,

high. and there is peter. spencer, how's it going? and they can see us as well. this is spatial, a prototype environment where people can appearto be prototype environment where people can appear to be in the same room and share the same images, videos and share the same images, videos and even 3—d models. and share the same images, videos and even 3-d models. so you have a big model of mars here. 0h, and even 3-d models. so you have a big model of mars here. oh, my goodness. amazing though this is, it might seem a bit too futuristic right now but i wonder how futuristic those early graphical user interfaces like windows seen way back in the 80s. whichever way you look at it, microsoft seems to be thinking differently to its previous incarnation. it is really interesting the difference that a ceo makes even for a massive company like this. 0k, ceo makes even for a massive company like this. ok, the previous ceo, steve bulmer called open source a

cancer and here we are with a company that is embracing all things open source, actively embracing other ideas and software and the numbers don't lie. microsoft is back in the game. it's february and that means it's awards season and the one award we love you click more than any is best visual effects. last year we talked to the visual effects tea m year we talked to the visual effects team is behind all the most amazing looking movies and the next four weeks we are going to be speaking to some of the biggest names in the industry as they tell us how they made some of the biggest films of past year. and frankly, no movie was bigger than avengers infinity war, so big in fact it needed several effects houses to work on individual sequences in the film in order to

bring's mightiest euros to lie. —— bring's mightiest euros to lie. —— bring earth's bring's mightiest euros to lie. —— bring ea rth‘s mightiest bring's mightiest euros to lie. —— bring earth's mightiest heroes to life. in time, you will know what it is like to feel so desperately you are right, that to fail is everything. 3500 effects shots, which is a huge numberfor a film. hear me, and rejoice. it was a major sequence, the part of the film were the timestamp is attempted to be taken from dr strange. wearable to collect data and do motion capture. they went out to greenwich village andi they went out to greenwich village and i think pretty much photographed all of it. in terms of acting, the brief was that it was war—torn, the

trees were on fire. everything that's close—up and burning. because we we re that's close—up and burning. because we were on the show fairly early, in a preproduction phase, all of the designs of the suits were really only in 2—dimensional form. designs of the suits were really only in 2—dimensionalform. it designs of the suits were really only in 2—dimensional form. it was to try to realise them in cg and realise them in terms of motion, have actually would move and work. its nano tech. robert downeyjr had quite a bit of input into how that worked. a couple of calls that you pull. and the seat tightens and allows the nano tech to come out and spread over a twitch was his idea.

spider—man has got his own problems as the character because he is so bindi and can quite often, the dislocations in his anatomy that would occur are quite often hidden artfully. a lot of the effects are defined by the story and the storyboard. he is an alien so it's ha rd to storyboard. he is an alien so it's hard to find a restroom —— a reference. the character is held in quite distinguished, he is a wizard, so we looked a distinguished looking english actors. peter cushing and christopher lee. what is their skin look like. try and infuse some of that character. bring me the stone.

we are all over social media. you will find us on facebook, youtube, instagram and true to. —— twitter. think keep watching and we will see you soon. hello there. friday was another day with severe transport disruption due to heavy snow. and it was across central and southern england that had the worst of it, particularly stretches of the m3 towards the basingstoke area. we also had some problems around the m2 in kent as well late in the day. some of those problems were pictured from the greywell area overlooking a stretch of the m3. you can see just how horrendous the conditions look there on the main carriageway,

completely covered in snow. so transport disruption has been a factor with the forecast through friday, and again into saturday too, with the risk of some snow still around, but ice as well fairly widely. looking at the weather picture over the next few hours, the snow that we have across south—east england becoming confined to kent before slowly beginning to ease away. there will be some further wintry showers across the eastern side of scotland into eastern parts of england. wherever those showers fall, of course, that adds to the risk of ice, with a widespread and sharp frost once again. the forecast for saturday is, yes, there will be more wintry weather around, after a cold and frosty start, locally icy too, we'll see further wintry showers trickling down the eastern coast, probably staying quite cloudy for a good part of the morning across the south—east,

maybe with some flurries, but nothing too heavy. some showers affecting western parts of wales but they will ease with time. we will see a few showers coming in across the north—west of northern ireland into western scotland. again, the showers are a bit of a mixture here with some rain around sea level. in land, a few with sleet and snow mixed in. saturday a decent kind of day with some bright or sunny spells after that cold and icy start. temperatures will be struggling once again, looking at another cold day for the time of year, temperatures around 3 oor 4. that goes into saturday night and clear skies leading to a sharp fall in temperature is the most of the uk. —6 in newcastle, there is the risk of some icy stretches, but further west we will see some cloud thicken as the weather system approaches the atlantic on sunday. this is going to bring another spell of wintry weather. we could see a few more centimetres of snow, this time targeting possibly the high ground in northern ireland, but the far north of england and scotland could see maybe 3—6cm but there is a tendency at lower levels for that snow to transition back to rain as mild air tries to move in from the west.

5—6 degrees for glasgow and belfast. the weather into next week, it is all changing, it turns more milder but there will be some heavy rain around as well and it will often be pretty windy. welcome to bbc news, broadcasting to viewers in north america and around the globe. i'm reged ahmad. our top stories: a wave of toxic destruction — dramatic new footage shows the moment a dam collapsed in brazil. at least 110 people are dead and more than 200 still missing. the question that everyone here isjust stunned by is how, in a big, modern, growing economy, this could ever have been allowed to happen. russia condemns america's decision to pull out of a nuclear disarmament treaty signed during the cold war.

the us says moscow's new cruise missile violates the terms of the deal. we have a special report from venezuela, where opponents of nicholas maduro say they've been detained and tortured in the past few days. facebook loses two of its key fact—checking partners, prompting questions about how committed it is to rooting