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the international space station isn't

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just a laboratory for experiments about

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how the human body responds in being in

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a weightlessness

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it's a place where scientists are

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studying how many things behave when

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there is no gravity present in one

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experiment researchers are examining the

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behavior of liquids inside containers

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it's called the spheres slosh experiment

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and flight engineers kimia yui and chao

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lingren will be conducting another

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experiment run later this week this

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morning we're going to learn more about

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that experiment from jacob roth the

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co-principal investigator who joins us

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from his office at the kennedy space

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center in florida good morning jacob

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good morning amiko thank you uh for

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joining us here spheres slash so can you

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tell me start start by just explaining

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in this fierce loss what are we looking

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at

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or the behavior of all fluids or are we

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looking at some some only some in

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particular

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so here at the launch services program

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we're particularly concerned uh with

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launch vehicle upper stage propellants

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and how they behave during coasts or

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before separation events

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but the experiment was really designed

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as a more of a broad study of general

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fluid behavior

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briefly explain why are we wanting to

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understand this

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so um particularly for upper stage

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propellants uh we get concerned about

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what the fluids are doing um you know

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you fire your engines and you're under a

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gravity environment and then you go into

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a coast and the fluids move around and

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predicting where they are um what kind

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of walls will get wetted

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what kind of moments that might generate

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on the rocket itself what that might do

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to your separation attitude for a

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spacecraft all of those things come are

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very difficult to predict and can have a

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big effect on the mission success

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okay so talk to me about the sphere

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satellites how are those being used

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to contribute to this research

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so the spheres uh really had two

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advantages the first advantage was that

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they have a kind of a reproducible

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consistent thrust

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turns out that that thrust is a little

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low so we can only use it in certain

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situations

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but that was kind of the big thing but

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the biggest reason we use them more than

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anything else was that they were already

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on station

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so we took advantage of their power

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they had a lot of capabilities the

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computers you know and all this stuff

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was already there saved us from having

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to build it ourselves and made it a lot

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quicker and a lot easier to get on the

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station

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describe what happens during one of

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those experiment sessions yeah so after

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uh after setup after they get everything

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buttoned up and everything put together

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we have a series of test maneuvers we

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found out in our first checkout session

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that there's a lot of bubbles that form

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inside the liquid

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and that makes it really hard for us to

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get a good initial condition so before

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every maneuver they perform what we call

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a settling maneuver where they spin it

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either around one sphere or around the

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center to try and get the bubbles out

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and then they slowly slow it down so

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that they've got a good initial

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condition

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after that we'll perform a maneuver

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where we start data collection and then

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a given maneuver will happen either the

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spheres will fire and move it around a

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certain trajectory to try and see what

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the fluid is going to do or we'll have

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the astronaut push it or pull it or

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rotate it or push it and let it float

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across the room

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and during that whole time we're taking

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accelerometer and gyro data as well as

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images to get an idea of what the fluid

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is doing and we'll perform a series of

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those maneuvers until we run out of time

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and we'll tear everything down and

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download the data

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okay so well with all the sophisticated

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computer programs to model all sorts of

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phenomena why would we need to use this

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type of demonstration what makes this uh

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practical

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so that's a very good question and it's

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really the point of this practical

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demonstration this type of experiment

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was to improve those models

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computer programs and models have been

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written we have the computational fluid

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dynamics as well as pendulum swash

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models but they've all been validated in

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1g cases they've all been validated

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against you know experiments that have

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occurred on the ground and so we really

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don't know how well they predict low g

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environments so this experiment was

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really designed to make those computer

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models better or to make us

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have less uncertainty about how well

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they're predicting

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now your experiment arrived on the

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station about two years ago i can't

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believe it's already been two years so

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how many more sessions are you planning

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and what can you say about what we've

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learned so far as a result of the

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sessions we've had

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okay so um we have this session this

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this week um we have one additional

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session left after that um in addition

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we're also planning possibly in the next

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year to send up a pair of at least one

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if not two tanks

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um we're hoping to to do a little bit

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more now that we've studied how they

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behave we're going to be putting some

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internals inside the tanks and trying to

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understand a little bit about how we can

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contain or control the fluid so it stays

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where we want

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as for what we've learned we've really

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learned a great deal about how

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unintuitive low g fluid behavior is

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we do know from some initial looks that

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our models have proven to be fairly

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accurate at bulk fluid motion

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but we've also found some good areas for

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improvement particularly we struggle

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with

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bubbles and droplet behavior and how

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whether or not they recollect into the

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bulk fluid or not that's been very

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difficult for us to predict

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i will mention

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that some of this data we've already

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used to improve our models and to reduce

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our uncertainty particularly for the mms

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the magnetospheric multiscale mission

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that launched in march they were very

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concerned about fluid behavior during

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their multi-spacecraft separation

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sequence because they had four

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spacecraft that had to be separated in a

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particular interval with particular

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attitudes and they were very concerned

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about what the fluid would do and so

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this data was helpful in easing their

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worry a little bit

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well this is certainly interesting and

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really great that you guys are able to

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make use of the sphere satellites that

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are already in place onboard the

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international space station

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also i understand that there's some an

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education outreach component can you

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share with me some of your results with

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the middle and high school students that

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you guys have worked with

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yeah so we've worked with a wide range

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of students um in you know starting at

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the college level we've had florida tech

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built this apparatus and we continue to

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the younger individuals you know given

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how visual our results are how great the

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pictures and videos are we use that

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really well to get them engaged um they

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particularly find

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the fluid images and uh and videos

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fascinating we've also particularly

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engaged with first robotics

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as a robotics competition and we've

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given a number of presentations to them

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on on how using that type of robotics

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can be done for uh for real science

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and then we've also been working here at

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the kennedy space center visitor center

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to provide presentations to visiting

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student groups

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great well thank you jacob i think

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that's all the time we have thank you so

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much for joining us and answering some

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of these questions good luck to you and

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your team as you continue to uh research

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this