in the pyramids, dark matter, and the big bang theory. don't forget, of course you can get all the latest news around the clock in a website that's dw dot com from mike look. and thanks for watching the invite for the power to kicks in the south china sea. why ships are here? what this is supposed to mean of a global conflict of the decades of chinese expansion is in the nation is resisting with us in the course of a powerful incentive on september 28th. 2 our universe, our planet, or even ourselves,

everything is made up of the same components of elementary particles. if we take a person and a chair and break them down into their components, we find adams and within them electrons. clark's include ones. without elementary particles, there would be no stable atoms. everything would fall apart. they literally hold the world together. elementary particles are not only the basic components of all matter. some can even penetrate any form of matter. the book is home to daisy. the german electron synchrotron. one of the world's largest

fundamental physics research centers more than 2000 scientists from over 40 countries work here, the particle physicists because challenge funding bag that takes us into the enormous tunnel system below the daisy grounds. funding becca is one of the world's most renowned particle physicists, a professor at the university of humble and lead scientist that daisy has only some parts of the tunnel are still being used for experiments. our team is allowed to film there. if i'm, if we going on the grounds to the hair acceleration, it's the largest accelerate to the gym and he has a have a bill i'm getting in touch anyone entering the tunnel needs an oxygen unit for safety and has to report in by telephone system from the christy and spun and vega. hello, i'm entering the here a tunnel and here

a west going towards here. a news i'm not behind the door is the heart of particle physics at daisy. the hair of tunnel hair stands for head drawn electron ring accelerator. the united so long definitely you found a problem with something i'm some and then the camera is so long. you need a bike to get from one experiment to another. it's fine. and you can see that it isn't actually a ring. you can get me riding through a straight section. now. the electrons and protons are accelerated through the straight sections. then the, the tunnel slowly starts to coach in deposit cool beans onto accelerated in the section, just redirected here. the proton bane travels in the launch of a vacuum tube and the electron beam goes through the lowest storage ring in the opposite direction. and if we were to try so much,

much the lead eventually come out of the curve and see how this electron too much is with the product onto the electrons to show that the protons in the next to take to the port on control center 4 protons burst and released new elementary particles. what physics is aiming for with these particle collisions is the reconstruction of the beginning of space and time. the reconstruction of the big bank, our universe emerged from a huge explosion, some 13800000000 years ago. particle physics has not yet succeeded in pinpointing the actual moment. but it can look back to a millions of a 1000000000 of a 2nd after the big bang. the debate about whether indivisible particles could exist goes back to the ancient

greeks some 2500 years ago. the greek philosopher, democritus, among others, called them adams from the ancient greek tumbles meaning indivisible. the debate continued until 1911, when it was 1st experimentally proven that adams themselves are indeed divisible. adams consist of electrons, neutrons and protons. the term elementary particles 1st appeared in the 1930 in the 2nd half of the 20th century, teams from the us and daisy and humbled among others were finally able to demonstrate that protons and neutrons are also divisible and consist of corks and blue ones. the standard model of particle physics lists for groups of known elementary particles. the core group consists of 6 particles in total.

the left tons, including electronics and ones, also comprises 6 particles. the. the group of gauge bows on the forced particles currently includes 4 types, including blue ones and photons. finally, there are the scalar bones. so far physics knows of only one elementary particle in this group. the higgs both on detected in 2012. it is the most recent addition to the particle family, the berlin, the, the noise museum. we meet viviana level, the curator of egyptian and oriental pye. right. the she takes us to the pirates collection. some of the oriental and ancient egyptian manuscripts on display here were originally rolled up or folded like these amulets. so

far they've had to be painstakingly unrolled and unfolded by him. the popularity isn't the wonderful guy right, or very fragile. when we want to open a piece for pirates conservator decides if it's possible, or if a package like this one, for example, will follow the parts interesting. i was into pieces. of course, you don't want us out of interest interest me. some 60000 pi ryan, the other manuscripts are stored in excavation boxes from 19 o 7. back then huge quantities of such artifacts were found during excavations on the la funding island and the nile river. with conservators, sophie elizabeth, but tell needs that he latha is looking for a pi right whose contents might be deciphered by means of particle physics without unfolding or damaging them. using a handheld x ray machine develops jointly with visits his tons,

abraham mancha. they have found a pirates packet that could have been printed with iron containing ink, and have decided to scan the document with even more powerful x rays. this is done at the heading home center for materials and energy in berlin's funds, a district to be as specializes in come a graphic, imaging of a wide range of materials for the pirates pack it from the egyptian museum draws on the pioneering research of a well known german physicist, the wilhelm calling ahead of on can discovered x rays at the end of the 19th century. shortly after he succeeded in capturing the 1st images, revolutionizing medical diagnostics and earning him the nobel prize in physics. for the 1st time, it was possible to visualize the bone structure of a living being without surgical intervention

the, the principal is relatively simple. x rays are produced by the rapid acceleration of electronics that is, elementary particles the, the denser the material, the less radiation can penetrate. its very dense material like bone appears, white and the x ray fluids and soft tissue like fat or muscle, are less dense. and so appear great. the organs containing large amounts of air, like the lungs allowed the majority of the rays through and appear black and the image of the well x rays can be harmful to living beings. they have long been proven tool for non destructive testing. and materials research supplies,

and we mentioned toys accessing done, the x rays pulse through vis franklin and then hit the detector team and we take a whole series of images, not just one of the 90 guns. we rotate the sample once 3360 degrees. what? i'm a quarter protection of very many, very different angles. they ask you this way that we can generate a 3 d reconstruction of the volume. so that's the sort of the scan only takes a few minutes and delivers numerous 3 dimensional x rate images of the pirates packet. but the writing inside can still not be read. this is where scientists from the to the institute in berlin step in the mathematician, daniel about him. and his team have developed software that can virtually, on a full, the pirates packet. he traces the individual layers in the 3 d model with the mouse

. the computer programs in virtually assembles the many x ray images into a flat surface. the structure of the plan fibers is clearly visible. finally, the image data from the x ray image is transferred to the, virtually on the folded piracy and distinct characters appear on the screen. you can see the pirates fibers really well up to the left is versed in 15, oriental scripts and language is from different heroes. including higher radek or coptic aromatic and arabic, because some model negotiated of a few was far strong, gets and, and visit the 1st time in the history of tyra's research. and we can read about pirates vert, truly, it's vicky sometimes having to physically open it up. time is the here. this is really sensational. this piece here is a topic texas. here is a piano which is the mass to an article. and then this symbol not freak as

a cop there. i call this is i'm not 5 and joe. a joy or just shows put joy in to me way. oh lord, jesus christ. the quotes from this is the short form for lord jesus christ and early christianity that out of my hand. a wonderful example of the fact that early christianity and personal piety existed on elephant team system from perhaps as early as the 4th century. when the game had been remembered, there seemed to be folded emulate that someone would have carried with them the monthly like spices. thanks to physics and i t. some aspects of christianity's early history can now be rewritten. the geneva, the european organization for nuclear research for cern is the world's largest research center in the field of particle physics. here at the swiss border with france almost 20000 scientists from all over the world have been researching the

properties of elementary particles. since 1954 we made german particle businesses to close down front and back again. it's r and p is regularly in switzerland to monitor experiments. yes, this is an overview of the launch hadron collider. we here on the sun side and then at the certain score is the large hadron collider. the world's largest particle accelerator. the ring shaped tunnel is almost 100 meters below ground. i, let's think i can just spend an hour flash advice of stuff on my side of the state as you know really starts with the both of the hydrogen. when it's hydrogen consists of one pro tillman, one electron to, it's as soon as the electron is extracted. and then the proton goes into a linear accelerator where it's energy is increasing as a huff. the speed of light finally got in uninspired fault, is finding out that by email, and they're like in the protocol and has been said 33 more. pre exhilarates is

a simple finally being directed into the large hadron collider. and that's where it's accelerated to new lights they done alphabetically, caught in that the bush line is to out in a fuss. please explain this type in the collider. protons are accelerated in opposite directions and shot at each other at 4 points in the ring. at almost the speed of light with 4 huge detectors measured the collisions i know these are the ductwork and one of the east cool to see a mess detector is located directly opposite this the inside and out on the other side of the ring i did is i think that's where we're going now documented c m s stands for compact and one solenoid. and it is one of the most exciting physics experiments of our time. here in the c m. s. control room,

the experiments collisions are coordinated and monitored other physicists from all over the world are connected in real time. including a scientific team from daisy and home board. i don't have blog at all. some 4000 researchers from 55 countries worldwide are involved in the see a mess. experiment seamless experiment is at the large hadron collider. and it's an experiment to look at the fundamental building blocks of matter, and understanding the fundamental forces in the universe and to learn more about how the universe was created. it's taking place at certain because a house, it's the most powerful accelerator in the world right now. and it's also a community that brings together is to choose from all around the world and the expertise for them to, to really advance the field,

a particle in 2012 researchers that sir and achieve their greatest success to date, experimental proof of the long sought higgs' bows on it was named after british physicist peter higgs, who concurrently with his french colleague false why on last described of the properties of the as yet unknown particle. the 2 or jointly awarded the nobel prize in physics and 2013 today is unusual to drive the proton collisions and the underground tunnel have been stopped in order to do maintenance work on the late fee for its detectors. is coming up for the last card in my tying. this is a diagram of to see a method to take to take to concede the, normally the protons would be colliding in the center of the detector right now. and kind of put that there aren't any protons in the collider at the moment that

will buy skins in these attach. and here's what we see instead of these particles here, which a cold calls make new ones, you know who and to produce, didn't cosmic rays at at tech, to investigate, possibly nearly through the detector. and so the detector reconstructed something non linear one, and then we would know that it was out of alignment and needed to be corrected to. and so we use these cause, make new ones to calibrate down to take to very precisely fiction. i've done a picture of the parentheses, this difference the cost of the because there are no particle collisions. today, we're allowed into the 100 meter deep detector room. this would otherwise not be possible as harmful radiation could be released during operation if it's the same as the tech to at that of his desk. a asked to the tech to into

who can i give you? the c m. s to take the here is the heaviest detector in high energy physics investigate the 65 percent heavy of the meal hotel on what we can see through police. but the protons come from here and also from behind. and then they collide in the middle of the detect uh tech. when they collide, they practically explode on and then we analyze the fragments via another z. and then the polk stick a proton collisions release, new elementary particles like bows, alms, left tons and clarks. which can then be measured in the c a m s detector. by identifying the particles produced in each collision, measuring their momentum trajectories and energies, and then piecing together all the information. the scientists can recreate and describe what actually happens during the collision. the things that allow them

and then let's see, and this is an equal quentin e. and this allows me to visit study the micro causing the policy cool effects. and you have the give me a might, if it's fascinating that the more you learned about it's micro cause a man because the more you understand about the big picture with name, the origin of the universe, this when you've as on by monday, monday, put total into protons collide for a fraction of a 2nd time the collision recreate the conditions of the big bang. the house had some of the defect box and the we can simulate these clocks and glue owns and swimming around. do me cycles make susie mountie by shooting price homes that each of them with incredibly high energy and 5 on the screen. these kinds of a n a d open on the see if it's mike traveling back in time to the origin, devalue, universe steals. this is the leave as when the protons collide, the elementary particles that shoot off in all directions, leave their traces in the individual segments of the detector. and these traces are

translated into a huge phone use of digital data. it all happens in this underground computer room, where all the data from the c a mess detector is received as far as stand and seem as to take to talk to you to imagine packets made off of 100000000000 protons, a shelter to each other in the c m s to take the amount was equipment and less than that's, that's step. this means you know, once but 40000000 packet. the 2nd only these are cases for the pm. interfered with each collision of these packets. some 60 protons collide with the protons and the impact it's released hundreds and thousands of particles, different types of psychiatric. then letting them to take to an else can. i'm at least different particles are recorded by the detector. and that is, if it's a cottage and in this room picked up a lease physical signal from the collisions and the detect. so we have in digitize

settings that color on an o. when that is, if that these a lot of data. so huge files that we have to pre select in the field around the information we can use at least from an ident expire, otherwise we can store. so this one is a dot and false alex yet one on sat down to the next of all the, the pyramids of these um, on the outskirts of the egyptian capital cairo, were built to stand for a turn, a deep and are indeed the only remaining wonder of the ancient world. how many chambers are hidden inside the 3 pyramids is still a mystery? the 3 main chambers among others have already been discovered. but researchers are certain, there must be more, perhaps even the body and the burial artifacts of the pharaoh key ups will be found the since 2015 teams of researchers from japan and france have been using

particle physics to study the 3 pyramids of visa using move on imaging, they are reconstructing their inner structure without damaging a single stone. the in the standard model of particle physics milan belong to the group of left on the lawns are formed in the upper layers of the atmosphere. when particles of cosmic radiation collide with air molecules. the particles which travel at almost the speed of light even penetrate large masses of stone around $10000.00 new ones, hit every square meter of the earth every minute at sea level, the scanners detect the ones that constantly race through the structure. those that pass through many stone blocks lose a lot of energy and leave

a relatively weak trace on the scanners. but if the move on slow through hollow space, they lose less energy forming a stronger image on the scanners. in this way, they reveal the internal structure of the pyramids and help to discover previously hidden treasure chambers and other rooms without having to move a single stone. in 2017, the research team has made a spectacular discovery using move on imaging. a previously unknown 30 meter long chamber in the great pyramid. milan scanning has also proven its worth and inspecting the contaminated for go seem a nuclear reactor in japan. engineers can examine the condition and integrity of the power plants, outer shell, from a greater distance, without having to physically enter the immediate highly radioactive zone.

the blue on imaging is also used in bulk analogy, where the flow of elementary particles reveals the underground structure of volcanoes. this enables a kind of early warning system for potential volcanic eruptions. but the flow of elementary particles can not only illuminate matter, but also transmit information. ready cellular phones are based on a discovery from the 19th century. ready they send and receive electromagnetic waves, which thanks to particle physics, we know are also elementary particles, namely photons. cellphones operate using the electromagnetic force described in the standard model of particle physics. the

silicon based sensors and cell phones are based on the same principle as the detectors had to turn the symbol of the band odd enough to institute for tropical medicine. just north of the piers is a research center where more than 400 scientists research dangerous pathogens they study, for example, the exact blueprint a virus is using extremely high intensity x ray technology. monthly and holes in the hall research has the structure of sonya viruses. a group of dangerous pathogens introduced to central europe long ago by exotic insects of vanya infection. like the last, the virus can be fatal. and there are currently no vaccines or effective drugs. this is why the molecular structure of the new viruses needs to be completely

decoded. first, we have to generate the biological sample for examinations. for example, we need protein crystals for x ray analysis, l 5, because a single protein is not enough for the food and it's the sample has to meet the certain conditions for crystallization to be possible at all. we can easily see cells under normal optical microscope. so we can see protein finish dash for this we need her to call physics, which helps us to make even the smallest atomic unit i'm visible. above, i'm high. the cell cultures are swirled for 2 days at around $27.00 degrees to supply them with as much oxygen as possible. this is important for the production of the protein under the optical microscope, monthly of holes in tall checks, whether the examples are suitable for further analysis. if a green shimmering signal forms in the cells they have produced the desired protein

. before the sample can be examined and a particle accelerator, the proteins are sorted by size. we can see the separation of proteins quite clearly. here to use of the messing of this protein signal is shown in blue. you see mission, it's a nice strong signal james. and our target protein is in the peak here then. so we can select which cubes were the target protein as well separated from all the other items. that will be our, your sample and we can continue working with it. in the final step, the target protein from the cold room is mixed with various chemicals to grow of protein crystals. this can take days or weeks. busy time unfortunately, no ma'am. i susan's proteins are not visible under an optical microscope. we need x

ray crystallography to see these proteins, these building blocks of viruses in the fine is detail using the support. and these are the protein crystals that have for him to phone time. they vary in size into a very nice straight edges, invest which shows their high quality last segment sizes, one of one qualitative with a kind of miniature lasso. she fishes out the best crystals and stores them in a container filled with liquid nitrogen via holes in tall vin takes them to daisy, the german electron synchrotron in the west of hum board. this is also home to the center for structural systems biology. c, s. s b for short. the biology, chemistry, medicine and physics research teams work together here in the field of infection biology. right next to the css b building is

a huge experiment. all. it is directly connected to a particle accelerator. the 3rd generation of the positron electron tandem ring accelerator. petra, 3 for short. petra 3 is a particle accelerator and one of the wide strongest x ray generators. it allows researchers to examine the smallest samples, like the tiny crystals from the band hot enough to institute. the minds based firm by on tech has also used to petra 3 to investigate the effectiveness and messenger capability of all in a vaccines. the packets of electron slide through the 2.3 kilometer particle accelerator ring at near light speed, the special magnets force them into a sneaking pass causing them to admit high intensity and highly focused x rays.

these x rays are millions of times more intense than those from conventional sources and up to $5000.00 times finer than a human hair. the, the x rays pass through some 50 measuring stations in several experiments halls where the sample from the band hall knocked institute is now being further examined here. nothing at holes in tall meats, structural biologist, christie. i live on the right. yeah. that sounds my sample set up a little bit on this and i've even prepared it please tell me little research as how the human body absorbs in transport. it's nutrients and medications . the uses crystallography to study the structures of the molecule is responsible for

transport. this is how protein crystallography works. to be able to visualize the 3, the structure of proteins with atomic level precision, highly focused x rays are beamed through the rotating cultivated crystal. the regularly arranged crystal structures deflect the x rays and create a characteristic pattern on a detector. the, the proteins 3 d structure can be determined from the position and intensity of the various light spots produced. knowledge of the structure can now help in developing new drugs that target precisely where pathogens such as a bunch of virus are vulnerable. the samples from the band hot enough to institute have been measured and the

radiation collected in the detector has been converted into a 3 d structural animation. protein crystallography has greatly advanced and accelerated massey of holes in tall and pushed down. looks research. yeah. because it's possible to develop a drug just by seeing whether it inhibits virus growth on cells, that type of thing. but it's very time consuming and you usually don't really understand why a drug works. the way it does, i'm assume that in our case, using elementary particles, we can find out exactly how we drug works or design a drug to stop certain mechanisms. stop. developing such a drug is one of the just download permissions. the atomic lee precise protein imaging helps him enormously because messenger proteins direct the drugs to the parts of the body where the active ingredient is supposed to work in mutual

wouldn't be as he and the method it's available here on campus and petra, 3 in particular, move to this made it possible to investigate these messenger systems and with us, by the help we work with tiny crystals time and only with the strong x ray beam. can we determine the structures just to and these are the developments of these methods has been an absolute milestone structural biology. traditional food in the long to get these to send troops developing small molecules to combat specific proteins this, this tiny molecule, inspect the crystallography is measuring accuracy, is helping researchers to keep pace with the rapid spread of previously on researched viruses. you know, how is the detective doing everything works on just a few 100 meters away at daisy we once again the particle physicist christiane funding back up the key and his team are analyzing the data from the particle

collisions at sir and in geneva, where proteins are again, being collided on the list as the homewood team is video link to the control room of the c m. s. experiment sean and back as team and germany now continuously checks the quality of the collision data from switzerland using its t at life spit out from the top nomic team s experiment. we now see and live images of the data collection of a c, a mass experiments. it's 2 protons collided here in the middle of the detector. and all these particles of fragments from the collision. some have left a lot of traces in the detector image just like a jet leads, a trailer condensation in the sky. he's in doesn't he said these are the green lines here. and so was this, these red and blue dogs represent the particles measure the energy cloud task. in these precision analyses,

data on known elementary particles is separated from what could possibly indicate new particles. and not only that must him up by december splits his joints missing from tides and we do both see them and applies. and we precisely measure the particles we know and trying to learn from the deviations we find at the imaging act like we also actively search for new particles that could help to explain things. what sense in my life, the fact that you find that sense of the universe? he's doc massa and only 15 percent and he's non mass us, the mass ends and molecules. it's designed to spin up monday, that ties liking these job and i put black beans in for doc method and white things for known method. i see it as, as file everything that's black. when that is what we don't understand by simple one, that's doc match material and that's what we're looking for. and as i swabs it's one of the biggest mysteries in science and system to material. and that's who can be assigned to the question that i have for the individual stuff. but what exactly

is this dark matter? the particle, physicists like chris john, sean, and beg a are looking for in numerous experiments. physicists have already proven that dark matter exist, and that it makes up 85 percent of all matter in the universe. but they have no idea what it is made of the. the search for dark matter is to search for what holds our entire universe together. 6 because without it or galaxy, for example, the milky way would fly a part the planets journey around their star, the gravitational mass of which keeps them in their orbits. stars and turn the orbit around the center of their galaxy. theoretically the further away

a celestial body is from its center of gravity, the slower it should move. but measurements have shown that the outer stars of the milky way move much faster than expected, or calculated astrophysics explains it this way. our galaxy consists of much more matter than what is visible and this invisible matter or dark matter also exerts a gravitational pull on the celestial bodies. 6 so that they can move faster without veering out of orbit. the researchers are using various methods to search for the as yet unknown dark matter particles. not only with underground detectors and particle accelerators, but also with telescopes in space. in the search for dark matter, there is even an experiment in which light is supposed to penetrate a solid wall. the

box of linen uh heads the helps experiment which is set up in a roughly 300 meter long straight section of the hair. a tunnel at daisy in humble outs stands for any light particle search. lemme is a particle physicist that daisy and devises novel particle physics experiments. a team of more than 200 specialists has developed and built the entire lp's facility of daisy over a period of 12 years. it is the 1st experiment worldwide in which very light particles of dark matter could be produced and detected in the laboratory. to do this, light would have to pass through an opaque wall, which is technically impossible. you have your voice in your construction. we're

trying to find something completely new. name a dock mouth with doing this by attempting things they shouldn't actually walk once a so. so like this was showing a flashlight on the wall, or it's normally nothing to get through funds. we use much more elaborate method. it was kind of a pitiful task it through the alternator. and then we cannot explain why the existence of a new form, but not under control spots. ok. so we're examining what we think is impossible to see if it's possible. after all, if it's is, do we have found something completely on you know, in the alps experiment, laser light will be amplified by a factor of $10000.00 and a type of micro chamber. the light will then pass through a strong magnetic field. in theory, a photon or light particle could be transformed into an axiom as the new relevant to the particle will be called if it can be detected. the laser light would be

stopped by the wall, but the axial on would simply pass through because nothing can stop dark matter. in the magnetic field on the other side, the axial and should be transformed back into a photon. more like a detector would measure the light particle that seems to have passed through the wall. the transformations, if they occur at all, would be extremely rare. the detector must therefore be able to recognize a few photons per day. if it succeeds a new dark matter particle will have been found, which would be a sensational discovery. because i'm isaac's pelham in familiar success is the fulfillment of a technological golf course. so i'm very certain that all helps experiments will succeed. and the nature up in the sign, if you will find off my tongue to the no one knows how long it will take to solve the mystery of dark matter.

the but the large number of particle physics experiments worldwide makes new discoveries more and more likely, the, with a very tangible benefits and will be sent. so what if we look back is we see the book really well together, electricity, very electromagnetic way, on the internet. one x rays, i just came from completely fall factual groundbreaking. we're search in to completely new things, especially physically is this one months for she has a possibilities. this is the, it's sometimes hard to explain what you're actually doing. items you can see in the pond of goals, you can't see them. so you can't type still smell them. but i still think it's important to research these elementary particles. ultimately,

it's the only way to understand where we've come from, a steam english that's and this will have to come up with a 6 is nothing more, less than apply to that school philosophy. you couldn't, we can explain it well and we know how to approach it. it's already working. we apply precision because knology on precision paul school physics here. so talk them out to is still a michigan region because when we have a complete picture of how we actually came into the well that just the fundamental questions from the philosophy. the supposed to meet them to an attachment is because the thing that's so fascinating about particle physics to my piece that we can describe these complex mess up. everything that surrounds us just in terms of the elementary particles kind of by man's and trusting image. and you almost think someone must have been clever enough to formulates how well to world of elementary particles, relatively simple in the mean time touching the upstairs. almost like it was planned to try and contact the engine desktop relaunched again. and i am testing

the shift your guide to life and it it to, to explore the latest online trend, navigate your way through the digital jungle, get a global perspective. we'll be your guide and show you what's possible. you decide what really matters to you. sit in 15 minutes on the double you sent optical pollution and heavy c o l phrases and it's going to change cost.

join us on a journey into the future of seafaring climate away. how ships can become clean in this on d w, the we are all set with what seemed closely due to bring use a story behind the news. we read about unbiased information of the

this is dw news ally from berlin is really air strikes, killed dozens in northern and central gossip. israel says it targeted him. mos command centers put some mazda officials, say, a mosque and former school sheltering displays. people were hit and explosions echo around baby boot israel, post the lebanese capital as it expands its military operation against the militant group. has paula is really armed forces order civilians to evacuate theory. plus tunisia of votes in presidential elections incumbent ty, so he is expected to win as his main operative opponents are either in jail.