Let us review quickly what you know on the state space technique so that we will go forward applying this. Of course, we had already discussed a few of the points. We will just put down all the equations just to revise what all you have done in the previous classes on some controls. So, this all of you know this is the response y of t and the impulse response function and this is the convolution term. You know the convolution part of the response which when we take the Laplace transform of that equation you get the multiplication of this convolution term or convolution integral and we also saw that the Laplace transform of e power at is Si minus a inverse right and that the g of s which is the impulse you know transfer function is given by this equation. Go back and look at it. d is usually equal to 0 in our cases. So, that can go off and very standard equation comes from remember x dot is equal to ax plus bu y of t is equal to cx plus du from that we get this. And the poles of the system are determined from this determinant, determinant equal to 0 and you know the importance of poles and once let us call p 1 p 2 be the poles of the system and if p 1 p 2 are the poles of the system then g of s is written say for example in partial fraction form and that if you now take the inverse Laplace transform you get g of t which is given by this function. In other words the poles play a role which are loosely called as the Eigen values of this things poles or Eigen values. One of the questions which people have especially when they come from a vibration background is that of the connection between the natural frequency and these poles. There is always a confusion as to what we mean by natural frequency and damping. In other words the poles of the system are expressed in a slightly different fashion okay as omega n and zeta for example omega is the natural frequency and zeta is the damping ratio. So, the relationship between say for example if the poles of course you know that it has to be a complex conjugate okay or if or it can be only real in which case you are looking at the time for relaxation 0.66 and so on you know that is given by this time and more importantly if you want to pick the relationship between the poles the natural frequency and damping then the relationship is given by this form okay. So, it is people usually say that natural frequency is the Eigen value or poles and so on they are not strictly correct yes one comes from the other but please note that if these are the poles okay the complex conjugate poles then this is what is the natural frequency okay. Now you understand the natural frequency and the poles you know what are important okay. Further than this about the effect of poles you all know it and that you know that in the S plane if this is the left of S plane then the poles are situated in the left of S planes S plane the system is stable basically because you have this e power term here and hence when it is negative okay the e power minus term minus into t would now start decreasing with time and hence okay the system becomes stable okay. Electrical engineers have very interesting analogy or very interesting way of interpretation not analogy but interesting way of interpretation how they interpret this. So, this is the j omega okay. So, you would notice that if I want to look at the frequency response what is that I do I replace S by j omega right. In other words when I want to plot the frequency response then I what do I do I plot omega here okay and the response in the y direction or in the y axis. So, you would notice that actually as I go along omega I go up that axis okay I at various places okay I go up this axis as I go up the axis if you look at what actually I calculate okay I calculate the distances between the poles okay between that point and the poles that is what is meant by the denominator actually that is the distance. You would notice that as I go along okay above this and when I come to a minimum distance point a minimum distance point okay assuming that these distances are large to the other pole to the other pole the distances are large okay since it is in the denominator okay as I move along omega my response actually keeps increasing because the distance keeps decreasing okay. So, when I come to this point because as I go remember as I go along omega actually I am going above in the y axis. So, when the distance is least I get the maximum response okay in other words that is why you have that remember that is the omega that you would get the maximum response. So, then as I move away the response now starts dropping okay. So, when there is no real term which means that your poles lie on the imaginary axis what would happen that it would go to infinity and so you would have a graph which goes like that and comes down. So, this is another interpretation okay especially used in filter design where it is very simple to understand okay the filters which is low pass filter or high pass filter or band pass filter for example okay those things can be band pass filter can be understood very easily by these distances okay which are in the denominator right and which one by the denominator one by the distance is small then the response is large okay after all you are looking at the response in the left hand side okay. So, that is a neat interpretation for the frequency response function okay. In the last class any questions okay please revise once the state space formulation if you have any doubts okay. In the last class we were looking at remember the transfer functions right we said that the two important transfer functions that we had looked at is for lateral acceleration okay lateral acceleration we in fact what we did was to find out the lateral acceleration versus delta front okay as well as what is the other one we did r by delta. So, I can write this as Ay just for simplicity Ay by delta and r by delta remember that we had only the front delta f and so on right. Now we also if you remember right we also wrote down the steady state gain okay right we wrote down the steady state gain the steady state gain at s is equal to 0 is u squared divided by L into 1 plus k u squared and that is equal to u divided by L into 1 plus k u squared right this is what we wrote down right. Now what I am going to do is to apply whatever we have done here okay to whatever we have done so far in other words I am interested to find out the folds of the system and then determine the omega n and the damping characteristics of the system this is what I am going to do now okay why are we doing this remember in the last class we said that we need to understand this whole concept of the response from an objective perspective okay from an objective perspective and hence we need to understand how actually the system behaves okay and can be written in terms of omega n and delta okay I am going to write down now a series of equations very simple algebra okay so I am not going to derive that step by step so that is going to take a lot of time so I am going to write down all these equations because interpretation becomes important so I am going to do that later okay one of the things I promised that we have to look at also what are called as the zeros right what are zeros the numerator okay the same what you did with the denominator you do that with the numerator okay we have not looked at the zeros yet we will have a very interesting thing what happens to the zeros that we will do it okay after we finish this derivation we are going to follow for objective there are a number of objective metrics as they are called we are going to follow this paper by Mimuro Mimuro et al SAE 910 sorry 901 734 this is not the only way of looking at objective evaluation but it looks you know quite simple quite appealing and hence I am taking this paper right so the first step let me write down what all you already have it so I do not have it in memory so I am going to write down what is A matrix for our problem if there is any doubt go back and refer this are all there in your notes right so this is this is A actually if you look at literature there is a lot of confusion on this C alpha f and alpha r I was looking at a thesis the other day there is a lot of confusion people have put C alpha f and alpha r to be negative okay in the the signs are given in such a fashion that C alpha f and C alpha r are given as negative in which case the whole understeer oversteer gradient definitions change okay so this looks like an accepted practice but I would like you to I would like to warn you that when you read paper or a book be clear okay like how is this definition or given you know what is this definition we are taken minus alpha f so that ultimately that equation becomes you know plus C alpha f okay sorry we taken minus alpha f and so C alpha f we kept it as positive okay so that we get the force centripetal force accordingly but there are people who have written this alpha f to be positive and written C alpha f to be negative okay in which case their k definition would change and so on just a bit of a bit of warning so when you read a book ultimately everything would boil down to the same thing but but then the same interpretations but then you have to be careful on the signs because when you do a problem or you want to understand it you know things would be different you have to be careful on that right.  Modern vehicle dynamics follows the language of controls very closely in fact if you look at older books okay the approach would be very different state space approach is usually not followed in older vehicle dynamics books but today because of the importance of automotive controls most people have shifted to the language of controls and hence we are talking the language of state space okay makes also very this whole subject to be very elegant because you are just applying what you studied in controls to vehicle dynamics.    Now, from this I can find out the poles okay and then write down the omega n and the damping ratio zeta right I am going to follow a slightly simpler technique okay which all of you know it so I am going to just write this in this terms you know which you all of you know I am just going to write the final result because I want to quickly get into the interpretation part so that I can write this down as a squared by omega n squared plus 2 zeta s by omega n plus 1 okay in this form write that last term in this form right from which okay when I rewrite that anyway that is equal to 0 so when I rewrite it in this form I will get omega n to be 2l divided by u root of c alpha f c alpha r into 1 plus k u squared divided by i z into m and zeta to be 1 by 2l into i z plus m a squared c alpha f i z plus m p squared c alpha r divided by root of i z into m c alpha f c alpha r into 1 plus k u squared done now we will get into why we did this. n will be 1 by I won't be a s squared you just see 2 zeta note that it is 2 zeta omega n so 1 by omega n squared l squared so l by okay I think right okay now why did we do this or what is the I hope I am just check quite simple just check whether it is okay now here we pick up a physical interpretation what is the physical interpretation of these things there are four quantities of interest one of the quantities I will write the expression later there are four quantities of interest in this one is what is let me call that as a1 all of this we have we have already derived okay 1 is what is called as the steady state response response of your velocity remember what this quantity was v divided by l into 1 plus k u squared which we just now wrote the second quantity of interest is omega n okay which is actually the natural frequency of the system the third quantity of interest is damping though remember calls this as natural frequency of yaw and natural frequency of damping I would resist from calling this because they are just the poles okay of the system I would not like to give them a name let us say that omega n is the natural frequency of the system and then let me introduce a fourth quantity which I would call as phi which is the phase lag 1 hertz of lateral acceleration okay now what is the physical meaning of the first one I know the expressions now okay so let us not worry about the expressions if I give you a system you will be able to find out so what is the physical meaning of steady state response of your velocity okay what do you think is the steady state response to your velocity what does it mean that is a ratio between your r to delta okay so higher it is what does it mean easily r would be developed or in other words you can interpret that to be the heading easiness I want to head how easy I am going to head okay so in other words how easily I am going to have the yaw for the car in order to get into the maneuver which I would like to have so this would give you what is called as heading easiness right okay now all of you know either natural frequency either you can express it in terms of radians per second or you can express it in terms of hertz okay all of you know something about the natural frequency of the system what is that you know about the natural frequency of the system you know or you understand the responsiveness of the system okay clear the larger the natural frequency remember that in your earlier classes for a simple spring dash pot system a second order system okay you were able to get what is the rise time what is the peak time TP what is the settling time TS okay overshoot all those things remember that you did those things for a second order system and that those were functions of 1 by omega n okay so omega n in other words gives me the responsiveness of the system okay heading for example now it is heading because that is what we use the word heading in order to understand the maneuverability so we get what is called as heading responsiveness of the system yeah what is what is the all the factors like settling time okay which is 4 divided by omega n to zeta okay and peak time all those factors are all functions of omega n okay larger the omega n smaller it is smaller is the same for example the peak time so smaller the peak time means I will reach I will reach what I want faster okay so it is ease with which I will go our response of the system is now better when omega n is increased right damping obviously all of us know it is it is responsiveness as well as there is a directional damping so I would not oscillate larger it is better that it would not get me an oscillating system right and the last thing is the phase lag what is the importance of 1 hertz is because most of the systems have you know the frequencies of excitation natural frequencies near 1 hertz so 1 hertz is just given but what is this phase lag what does that tell you what is what do you understand with the word phase lag or fun yes so in other words in other words intuitively I know that if the phase lag is small okay what what I give is immediately heard by the system or responded by the system or in other words it is easier for me to control the system okay so I would call this as controllability right so these are the 4 yes no this is for lateral acceleration phase lag of not so how do I find out find this out remember we had the transfer function yesterday okay in that transfer function we have to substitute s is equal to j omega and then you would get that at 1 hertz and that is what you would get now what murmur would date isn't this is this is not very difficult physics all of you know this what murmur would date was to plot this as a rhombus he plotted this as a rhombus so how did he do that in a very I would say interesting fashion okay. He had the natural frequency f n in one of the see there is no two axis look at this carefully the positive side he had f n he had phi increasing like this usually phi can be say minus e t minus 40 and so on okay that is how he plotted phi then he plotted the damping coefficient zeta in this axis right and of course the other one a 1 here why did he plotted like this very simple that if I now plot that for a car like this okay it simply means that understanding the physics of all these four it simply means that larger this rhombuses larger means f n is larger good for me phi is larger that means that look at how it is going minus 40 minus minus 80 minus 40 and so on okay it is usually the minus and then okay larger it is which means that your yes his response is very fast so that is a lag is small okay larger it is good for me damping and larger it is my first term which is the hidden easiness is better so he simply said that plot this like this when you plot it like this then the larger this rhombus the larger the rhombus better is the vehicle handling simple okay it is very easy to now understand or else it is not it is yeah you have to go into too much of details but here this is the first or the easiest way to understand vehicle handling look at the area of this rhombus and I am going to find out how good is my weight okay but but look at all the equations which are there may be some of them I have written here some of them you do not have here a 1 and 5 okay phase lag I have to write down that equation that is a tricky equation let me write down a 1 also so let me write down a 1 here a 1 which you already have u divided by l into 1 plus k u squared and phi is r tan a l c alpha r divided by l c alpha r u divided by 2 pi minus pi i z u that is a lengthy expression but I want you to check this slightly doubtful whether there is a 2 here or not fn divided by fn squared minus 1 just check this I think it should be right check whether that is correct now there is one small way small one issue what is the issue with all these expressions what is the issue the interesting issue here is that it not only depends upon the car of course it depends upon the tires extensively so the tires are going to play a great role in handling no issues okay in fact we have if you remember we have linearized the tire performance or tire characteristics and just put that initial slope okay not bad not the best way because we need to get this other tire models okay but we usually assume that we are we are not going to be away from the linear case we will come to how he determined this experimentally in a minute okay but before that let us look at these things carefully what are the other the peculiarities yes this and this has an effect more importantly velocities seem to have an effect okay the velocities are important so all these things are functions of velocity you are written down a yeah and velocities are important in other words a vehicle handling also depends upon the velocity so if you want to test a vehicle it is not enough if you test at 80 kilometers per hour or it is not enough if you draw this rhombus at 80 kilometers per hour so we also need to plot that for different velocities and what do you expect look at that carefully and tell me what would what would happen to a1 what would happen to other factors for a particular k most instances actually with increase in velocity v or u rather than our case as we increase the velocity rhombus now goes down so the words the handling characteristics depend upon the velocity vehicle which performs very well at 80 kilometers per hour okay will have will see a deterioration with velocities yes the typical value see because I have this formula okay we will do a problem in the during one of the assignments I have all this formula here okay I know the values of k just substitute it vary it with the velocity in fact if in other words if I want to now plot omega n versus I need to do say what I need to do is to omega n versus u if I now plot it the graph would look something like this clear so if I now plot each of these quantities with velocity for example omega n if I plot it would be like this so now I get those I have already the formulas there I get those and then plot it here right very simple nothing very difficult so now the other one is the understeer and the oversteered vehicle how is the understeered and the oversteered vehicle going to be affected now what would happen to an understeer I would as the vehicle becomes more and more understeered how will that go look at that formulas and tell me as the big vehicle becomes understeer what would increase okay omega n would increase a1 will decrease so it will move like this and obviously the oversteered vehicles move in the opposite direction now how did number determine for cars in other words what is the experiment he did or he recommended this group recommended an experiment called the pulse steer a pulse steer test in a pulse steer test in a matter of 0.4 seconds a steering is given an input okay of about 60 degrees and back so that is the pulse steer you give a pulse actually to the system okay so you give a pulse to the system it is like it is like giving an impulse okay so the pulse excites number of frequencies that is the reason why we went to the pulse of the system right here there are we can look at why pulse and so on from from f of t point of view but I am not going to do that this class but go back and read and maybe when you have time the later part of the course when we talk about ride and we talk about f of t we will look at the beauty of that pulse okay so he gave a pulse to system and said that at least about in 0.4 seconds okay this was done this was done so that the lateral acceleration or in the order of about 0.25 to 0.3 so that the assumption that we made regarding the tires that they are linear is valid clear in fact we have done a lot of work on this and we we found that this with an expert driver this rhombus okay which we call as memuro rhombus and the subjective evaluation for driver matched very closely so in other words we found this to be a excellent objective evaluation tool alright so now you know you see the importance of tires and we will see the importance of other things okay has to how they are going to be affected right any questions yeah depending upon the value of k this would vary and so I know the k values that you have come again what I suggest is that okay I understand that how much it would vary we will do a problem okay that is the easiest way to understand it okay how for example you are asking how big is the k okay would it be would it would it have an effect okay if k is larger small right we are talking about a typical car what is the k value which is an understeer coefficient car okay so what we will do is maybe we will do that in the next class okay I will work out and I will I will put some values to this so that you will understand how exactly that varies you know that is your doubt how much it varies we will put typical values in the next class and we will okay work out a problem that would give you an idea as to how it varies right in fact the experimental setup at experiment okay we will we will do that maybe in the next class this experiment you will do it in your vehicle dynamics lab class okay you will do this in the lab class so that is the reason why we there is a lot of experiments that need to be explained you know this course is too short we cannot do everything here so this course is more on theory the experimental vehicle dynamics you will do in vehicle dynamics lab right anyway we will pick up we will give you some dope on this in the next class okay I am going to give you an exercise okay do this you remember that we defined beta okay V by U remember that find out an expression for the transfer function for beta okay that will be an exercise and we will follow it up in the next class stop here and follow it.


So, from here, the first move is raising the hand straight as a reaching out. So I'm just reaching out straight, and it happens to make contact with the dummy arm. That's all I'm doing. Okay? That's it. So from here, I'm just basically just raising it up, like that. And I'll show you the use for this in a second, but first let's learn the technique.


Yeah, in the last three lectures we have been looking at the issue of magneto resistance and any material which loses its resistance in the presence or absence of magnetic field becomes very interesting. In the first example, we looked at rare earth manganites which actually has a genie inside the lattice, the magnetism controls the electrical conductivity and as a result there is a huge drop in resistance when you try to disturb the magnetic ordering there. And in the next example, we saw it need not be a ferromagnetic material in bulk, but if you can make stacked layers of ferromagnet an anti ferromagnet or ferromagnet and spacer layer then you would expect a colossal change in the resistance. So, we looked at few examples of this metallic multi layers, we are actually looking into the theme of the various aspects of magneto resistance, we call it GMR, we call it TMR, CMR. GMR and TMR are predominantly involving metallic ferromagnetic layers whereas CMR is confined more to oxides. So, we looked at the example of CMR, we looked at example of multi layers of GMR and we looked little bit into the mechanism of TMR which brings about a colossal change in resistance. Just to give you a recap of what is the central issue, the issue is to make use of the electron spin, electron has a down spin and electron has a up spin therefore, you can try to exploit the orientation of this electron spin up or spin down and you can try to moderate the electrical conductivity. In the bulk there are ferromagnetic materials, as you know paramagnetic material is best exemplified in this fashion, when magnetic field is removed the moments are oriented in random way whereas, when they are aligned when applied magnetic field is stronger and it can reorient all this in one direction. So, this is the situation of a paramagnet and then we also looked at a typical ferromagnet, typical ferromagnet gets ordered below T c, they are ordered like this and above T c they get reoriented into a paramagnetic phase. Now, the point is the presence of magnetic field produces only anisotropic magnitude resistance and the order of such change in resistance is very very small. As a result you cannot bring about a colossal change in resistance when you are looking at anisotropic magnitude resistance therefore, you need to use the same ferromagnetic material but you should align it in different way, you should stack it in different way then you can induce a colossal drop in magnitude resistance. So far we have seen the many phases of magnitude resistance, we call this as GMR, we call this as TMR and we call this as CMR. A GMR predominantly we are talking about metallic multilayers and organic inorganic multilayers, in TMR we looked at metal insulator, metal trial layers and the CMR predominantly rarer the manganese and ruthinates. Today I am going to spend little bit more time on this issue of organic inorganic multilayers and why it is advantages, why we need to go for such a combination of organic inorganic multilayers. Now, just to bring back to focus the two important mechanisms that governs, we said if there is a ferromagnet here which is aligned in this direction, ferromagnet here which is aligned in this direction and it is separated by a non-magnet of this dimension. Then you have two different resistance pathway, one is if the up spin electron is going from here to here then you have a resistance pathway in this form and if you have a down spin then you have a resistance pathway in this form. So, if your if it is an anti-parallel direction, your ferromagnets are anti-parallel aligned then you have a different pathway for resistance and this is the model that we propose. So, overall if you have a anti-parallel situation then you have larger resistance and if you apply a magnetic field you have a smaller resistance specially via this form which we call it a short circuit therefore, you can see a change in the magnet of resistance. This is mostly a spin dependence scattering which happens across the interface. The other one we also told about the mechanism of tunneling magnet of resistance. In the aligned case you actually have the spin up electrons going from here to here when they are aligned parallely and in that case the spin sub bands both are same. Whereas, when it is aligned in anti-ferromagnetic fashion the spin up band is located here whereas, in this case spin up band is located here therefore, there is a reluctance for this electron to go here and therefore, this resistance is going to be greater in the anti-parallel way. So, these are two important considerations for the resistance across multi layers. Another example that we can think of is instead of a insulator a non-magnetic insulator you can try to replace that with a ferromagnetic insulator. What would happen if there is a ferromagnetic insulator then electron when it goes from here to here if suppose it is up spin and then it has to retain its spin memory when it goes to this layer and in that case if there is a ferromagnetic ordering or if there is a ferromagnetic alignment in this insulating phase then the spin up can have this electron can have a spin memory which can be retained as it goes to this layer. So, this is also a useful concept instead of using a non-magnetic insulator you can go for a ferromagnetic insulator to maintain the spin memory as the electron goes from one electrode to the other electrode. So, in that case what is a situation this red m h loop m versus h loop what you see here corresponds to nickel ferrite n f o is nothing but n i f e 2 o 4 which is a spinal ferrite and this is a ferromagnetic and this is insulator typically it gives a magnetic hysteresis loop of this fashion and you also have the hysteresis loop of the un sintered ion layer which is having a rather different coercivity compared to the bottom layer which is actually grown at 250 degree c. So, you have essentially same thickness of ion but with different coercivity because in one case you grew the film at 250 therefore the coercivity changes and the other case you have ion which is deposited at room temperature therefore it has a different coercivity. So, you have two different coercive ferromagnetic electrodes and separated by a ferromagnetic insulator typically you would see the device showing the m versus h loop in this form. So, what is unique about this you have the staircase you have the staircase type of hysteresis loop which is typical for a device. So, if a device is performing then you have the staircase sort of feature and then the magneto resistance also shows a pronounced activity you can see although the order of percentage m r is rather low but you can clearly see this butterfly shaped butterfly wing shaped m r curve which clearly shows that this sort of magneto resistive feature can be accomplished with a ferromagnetic insulator. So, this is another example one can think of you can make this device in this fashion you first put ion electrode and then this is your NFO layer and then you put another stripe of Fe then you can measure the voltage that develops across this interface. So, this is one example where we can show that you can use variety of spacer layers not just non-magnetic layer you can use MGO we have already seen one example of MGO which is neither magnetic nor it is metallic but it is firm it is a anti ferromagnetic insulator and this is also showing a pronounced tunneling magneto resistance. Now GMR can also be seen in granular systems what is granular system for example, if you take cobalt silver these two are not immiscible in other words we can say they are immiscible they are immiscible alloys. So, if you actually deposit say silver layer and then you try to put cobalt layer it would not grow as a silver layer and then as a two dimensional cobalt layer what would happen because of the immiscibility all the cobalt will actually form clusters they will form clusters of cobalt atoms and it will be deposited on the silver matrix. Now the interaction between these clusters will determine what sort of magneto resistance that you can get and this is also called as granular system one drawback about the granular system is the field sensitivity is less we can also achieve that using iron and silver. Now you can make several such composites for example, one can run through nickel ferrite Ppy this is a example of how this GMR can be seen even in bulk because your NFO is nothing but ferromagnetic insulator you can try to provide the conducting pathway by coating it intimately with polypropylene or polypyrrole. So, in this case you take pyrrole and you try to polymerize it inside to with suspended nickel ferrite. So, as pyrrole is getting polymerized you will see that this nickel ferrite particles are coated intimately by pyrrole polypyrrole as a result you get a conducting matrix like this. So, the moments are actually aligned randomly and you have the polypyrrole matrix which is actually holding all this nickel ferrite clusters. Now this can give a some glue whether we can achieve magneto resistance in this sort of bulk composites because so far we have seen whether there is pronounced MR in metallic multi layers. Now we can also see whether there is any faint chance of harvesting a large percentage magneto resistance in bulk composites. If you actually take a look at the infrared spectra and the x ray diffraction spectra you would find it is very interesting that the pure NFO that is nickel ferrite gives a typical spinal pattern whereas the P P y which is a polymer gives you amorphous pattern. Now if you keep loading nickel ferrite in P P y to the order of 50 percent 70 percent or 90 percent in spite of loading that much of nickel ferrite even with little percentage of P P y you can see still the faint amorphous pattern dominates over the crystalline nickel ferrite what it suggests that nickel ferrite can be intimately coated by polypyrrole as a result you can try to measure the magneto resistance in bulk in such composites. The infrared spectra also gives you a clue about this particular band which is propping up with the increasing NFO because this is a characteristic nickel oxygen bond which can be seen in this NFO P P y matrix. So, one can actually make quite a bit of composite materials with the wide range of loading capacity and one can see whether this also gives pronounced gmr. If you actually take polypropylene itself which is a metallic polymer you would see that there is a positive magneto resistance and it is of the order of less than 1 percent although but it shows a more significant mr at 80 k. But what we find here for optimum composition of 50 percent NFO which is NFO P P y composite we see mr is much more higher than even the 90 percent. So, there seems to be some influence of the NFO loading on polypyrrole and there seems to be some way that we can look for magneto resistance even in this bulk composites although the magnitude is less. We can also look at the other granular system that is cobalt silver again in this case you have the iron or cobalt silver which is dispersed in the silver matrix and we can achieve this sort of cobalt silver alloys by using sodium borohydride as the reducing agent and this is the overall reaction as to what happens sodium borohydride reacts with metal salts and it releases metal and boric acid and all these can be easily removed filtered therefore essentially you get a pure metal. If you are going to take 2 metals m n and m prime n plus then you can actually get alloy and this alloy can be nano in size as I told you if it is a granular mr the feature is something similar to this where you have the saturation value is rather high because the switching phenomena of this randomly oriented moments takes larger field as a result you have a very low saturation effect. Nevertheless we can see for a 60 percent cobalt doped silver alloy in other words 60 40 alloy we can say you see a very nice trend of a metallic behavior down to 4 kelvin and we have tried to measure the magnetic property or the TC for this alloy and this is reported to be above 350 kelvin because of the measuring constraints one cannot measure magneto resistance beyond 350. So for this reason we have tried to measure the mr at 350 and we see that near to TC this sort of granular alloy show a pronounced effect of up to 20 percent mr in this bulk cobalt silver composites. This is new because there are no reports where cobalt silver alloy is known to show such high values. It is possible from this work that one can try to prepare by either sputtering or other methods to prepare cobalt silver films and try to look at the TC close to sorry mr close to the TC. We can also try to do this with iron silver alloy composites where you see again a clear metallic behavior down to 4 kelvin and one can see that with increasing temperature the resistance increases and mr shows a very clear feature although the mr percentage is significantly low but it is showing higher proportion at 5 k compared to 300 k. So you have another composition iron silver 50 50 alloy which also shows similar trend where you see lesser mr percentage at room temperature compared to 5 kelvin and this can be engineered for applications if we can translate this composites into thin films. So I have shown you a variety of combinations of alloys which show mr behavior just to sum up at this stage what I have shown to you is that this stacking of multi layers is very important and one can try to engineer a variety of combinations as spacer layers and we can try to observe significant mr in cases of metallic multi layers and there is lot more work to be done for spacer layers which are not traditionally metallic. So we will go to another important issue of organic multi layers we can start from the origin where exactly this idea stems from this is known as a predominant feature in organic light emitting diodes. In organic light emitting diodes we have almost all the layers which are organic but for the anode and the cathode. So why this organics can be brought into spin tronics what is the need and what are the advantages over the metallic multi layers is the question. Now spin based electronics as you know we can try to read the information of each of this domains if we can look at the spin orientation. So depending on the spin orientation you can have a binary information storage that has non-volatility it can have high integration density and fast switching time and low power consumption. All these are advantages for spin based electronics which are obviously absent or incurs costly penalties when you think of the regular semi conducting industry. So for this reason we need to look at new possible avenues where we can try to look for wider applications involving organic spin tronics. Now why spins in organics there are two perturbing factors of spin orientation in bulk. Number one you have spin orbit interaction in this case interaction between electron spin and nuclear charge are becoming important and this is more pronounced for heavier atoms. The spin orbit interaction is more pronounced for heavier atoms and then you also have another competing interaction which is hyper fine interaction this interaction is between the electron spin and the nuclear spin. So you have two issues that you confront in the multi layer systems specially when you think of spin tronics one is electron spin interacting with nuclear charge another one electron spin competing with nuclear spin. As a result you have the spin tronic values or the magneto resistance values are considerably low specially when you involve heavier atoms because the spin orbit coupling contribution is of the order of z to the power 4, z is the nuclear charge as a result since this is dependent on z power 4 the contribution of spin orbit coupling is usually dominating and that is why we should try to see whether we can completely ignore this contribution so that you can maximize on the GMR or the magneto resistance ratio. There comes the issue of organic molecules if I need to subdue this both this effects then I should look for organic molecules which are lighter atoms and they are better alternatives because you can minimize both on spin orbit coupling and hyper fine interaction to a larger level as a result there is a search for new compounds. Now where does organic come into picture in electronics the classic example is that of organic LED because in the year 1987 it was Wanslik and Tang who actually reported organic electro luminescent devices which appeared in applied physics letters and a typical organic LED configuration is like this.  Now if this is sandwiching a organic semiconductor then light comes out of the ITO layer which brings about a new generation of display devices these are all the old devices which are presently coming into market you can bring down the screen size because you can go for large area and also you can minimize on the deposition intricacies. So organic semiconductors brings about a new generation of devices which involves spin too. Now spins in organics is construed in this way what is the mechanism of this organic LED as you see here electrons come from the anode and then holes go from the cathode and they do combine here when they combine first they are held by a columbically bound electron hole pair and this value 1 3 specially refers to 1 spin singlet and 3 spin triplets both in electron hole pairs and they together combine as excitons.  So you can actually have the singlet exciton and the triplet exciton of which the excitonic spin singlets are the ones which radiate the fluorescent light. In other words if you look at the spin statistics you have 25 percent or one fourth of the possibility is the singlet exciton and three fourth of the possibility is the triplet exciton and because of spin selection rule only the singlet excitons are allowed to radiate and therefore they account for the light that you see in a organic LED. In other words of the excitons that are produced due to electron hole combination you have only 25 percent which is responsible for the light emission and 75 percent is spin forbidden. There are ways to harvest this if you can annihilate this triplets then you can convert this into singlet pair and thereby you can increase the efficiency of this singlet excitons which radiate fluorescent light. So this is what I said the singlet which is responsible for the fluorescence and the triplet excitons which are responsible for the phosphorescence. This is the theoretical limit and the experimental observations are slightly higher than 25 percent in various cases. Now these are some of the organic molecules which are used in the current OLED devices and mostly these are all polymers PPV, PFO, MEH, PPV and P3H and so on. Now how can we translate this spin LED into a spin magnet or resistive device? If you carefully look at this configuration this is your OLED device and if you want to convert it into a spin valve all you need to do is replace this anode cathode and anode by ferromagnetic electrodes. So if you replace ITO with a ferromagnetic electrode if you replace aluminum with a ferromagnetic electrode then you are essentially making a spin valve device which involves a organic layer. This ferromagnetic electrode can be a metal inorganic metal such as say iron or it can be cobalt. So essentially you are making a iron organic iron electrode device where you can look for the spin valve operation and this is typically the way we can cartonize the spin valve structure that involves a organic where you have a ferromagnet 1 and ferromagnet 2. This is the organic layer and as you see that when the ferromagnets are aligned then there is more of electron mobility as a result you have a current high situation when the spin valve is open. Now if they are anti-parallel aligned then you have current low and therefore even with this sort of a configuration ferromagnet organic layer ferromagnet device you can essentially bring about a spin valve response using organic. And this is the way that a spin valve will work if you have this sort of a configuration then you will see a sharp rise in the resistance as a result you can imitate this to be like a inorganic spin valve. So in organic spin valve what are the examples? Park actually reported this first work where he used LSMO and cobalt as the ferromagnetic electrodes. One of the reason why LSMO which is lanthanum strontium manganese oxide which is used is because this is known to be a 100 percent spin polarized half metal and therefore we can use this as a bottom electrode and the interface also can by and large can be moderated if you are going to put organic layer. P3HT is nothing but a thiophene moiety with substitutions and this is a good hold transport layer as a result we can try to have this in between two ferromagnetic electrodes and the cobalt can be used as a top electrode which is reported by Majumdar and co workers and they have reported this in 2006. So this is a typical configuration of a organic spin valve where you are essentially using ferromagnetic electrodes and your middle layer is your organic but what are the problems here? Problems in making this is to do with the interface because to grow a organic and a inorganic interface it is very very difficult because this organic layer should be good enough to wet the inorganic layer or the inorganic layer has to be atomically flat so that you can make a very thin two dimensional layer of your organic which is the challenge otherwise many such structures could have been realized by now. So far the limitation is you cannot grow a good interface here because of the roughness that is coming from the inorganic layer and because of the growth mode which can vary for the organic layer. Nevertheless for the device that we saw which involves cobalt P3HT LSMO layer you can see here the magneto resistance at 300 k and magneto resistance at 5 k it is sufficiently remarkable responses there. In this case you can see at 5 k a very large response and in the other case you see a faint response of about 3 percent at 300 k which is not a bad number considering the metallic multi layers at room temperature definitely there is a good response for this device. Spin injection and spin transport and spin detection seemingly are proved in this organic electronic device these are small but distinct signature at room temperature therefore spin polarized transport through organic materials is therefore possible. So what is this organic magneto resistance which can be called as OMAR organic multi layers first even before a typical organic spin wall was done a typical OLED device was taken and magnet was kept in closer proximity and this is the response that you would see a huge change in the resistance with the driving voltage is realized when you have PFO as the organic layer and therefore a typical OLED device can also give you a large magneto resistance it need not necessarily involve a ferromagnet organic ferromagnet trial layers even a typical organic LED can give you large room temperature response because of the spin statistics that are involved in such phenomena. Using this as a clue towards printed magnetic senses based on organic diodes Majumdar group have come out with another structure which involves silver aluminum and P3HT and put it between the magnets and then you can see a clear MR behavior that can be that can be seen this gives us the challenge to go for printed electronics which is another good development in this field using organic layers. So one can go for different models and how do we understand the organic magneto resistance there are several issues that are being addressed one is the bipolaronic issue then the charge pair issues and also the spin-spin interactions all these are discussed in different examples which are quoted in the recent past. I would like to leave with the one more example on organic insulator we can take two ferromagnetic layers and we can put a spacer and this spacer can be a non-magnetic insulator which is a organic layer and what would happen in such situation we can try to make this sort of organic layers using pulse electron deposition which is a rugged facility and this is a typical pulse electron deposition chamber which has facility for a six target carousel and you can use this pulse electron beam to ablate the material from the target and typically during a ablation protocol you would see the plasma that is coming out because you can you can essentially use this pulse beam for any type of material not only metallic but you can use organic material you can use insulating material to ablate this sort of compounds and this is the overall setup while in use. So we can see some examples as to how we can look for magneto resistance using organic layers in the next slide. So this is a very good facility for making organic trial layers mainly because the insulating organic material can easily be ablated this is very different compared to pulse laser deposition pulse laser deposition is a technique where laser plume laser light falls on the target something like this and then it ablates the material but if the material is insulating and it has a wide band gap then it is difficult for the laser light to be absorbed by the material and ablation will be remarkably low. So for this reason you can replace that with the electron beam then you can try to ablate any material either metallic or insulating material. So you can make any device applications and this is typically for the compound PTFE which is commercially known as Teflon. Teflon is a good insulator and we can use Teflon as a organic layer between two ferromagnetic electrodes and typically if you have the PTFE deposited using PED you can see the thickness profile and this thickness profile is evaluated from a profile of meter and you can actually go up to 21 22 nanometers 22 nanometer thick PTFE layer can be deposited and this is how you can look at your thickness profile one can also go down up to 5 nanometer comfortably with a continuous deposition of this film in two dimensional way. So after ensuring that it is possible for us to make a device structure of this configuration iron PTFE iron tri layer and how do you go about it first you put a iron stripe like this and then we can put the organic layer and then you can put one more metallic layer on the top and you can measure across the electrodes and then you can also see the AFM images of the iron layer which is deposited as a bottom electrode this is actually deposited at 200 degree C and then you can put a 6 nanometer thick PTFE film the surface looks like this and then the top layer which is actually deposited at room temperature shows a much larger grain size compared to smaller grain size for iron electrode. Now how does the device respond if you individually take the top and the bottom electrodes iron electrodes you can see the coercivity is different because when you deposit the iron at 200 degree C or so then the coercivity shrinks whereas the top layer shows higher coercivity which is deposited at room temperature and this is the typical signature for the device when device is there then you would see this two step hysteresis loop which is showing the clear device operation now you can vary the thickness we can go down to 2 nanometer, 4 nanometer, 3 nanometer and 6 nanometer and as you increase the PTFE thickness you can see that this step is more resolved compared to smaller one thicknesses now the question is when you can achieve such small thickness of this PTFE layers whether the device can clearly show magneto resistance is the question you would see that in the next slide when you have 3 nanometer and 4 nanometer although you have this two step hysteresis loop which is characteristic of a device but when you look at the magneto resistance they are essentially showing negative magneto resistance negative MR which means the top iron layer is actually getting coupled with the bottom iron layer only then you will see a negative magneto resistance but if they are clearly separated by PTFE layer then you should actually see positive magneto resistance which is nothing but the response for tunneling magneto resistance device so what does that mean even though you have a two step magnetic hysteresis there is shorting between shorting between the bottom and the top iron electrodes it is short circuiting as a result we can say that this layer is not flat or it is not fully covered there are pin holes in this layer which is actually bringing about a short circuit between the top and the bottom electrode so what you do if you go further to 6 nanometer if you go to 6 nanometer then you see this response is much clearer and if you look at the magneto resistance compared to the previous one in previous one it is a inverted response whereas when you go to higher thickness you see that the response is now positive so what does that mean at a critical thickness of say 6 nanometer you are able to clearly demonstrate a tunneling magneto resistance behavior as a result you see a positive MR although the value is very less still it is appreciable to show that organic spintronic can be demonstrated now what is the clue for whether this device is working if you look at the resistance value for such a device you can see in the presence and absence of field the resistance is varying and the value of resistance gives you a clue as to whether such a device is working suppose the top electrode and the bottom electrode are short circuiting then the value of this resistance will be less than 5 ohms or this may be in milli ohms because it is essentially coming from ion electrode the fact that you are seeing a very high resistance it means the organic layer is able to decouple the resist the bottom electrode from the top electrode as a result you see a pronounced TMR value so this is another example that we can look more positively into making organic spin wall or organic TMR junctions which can give you pronounced GMR behavior there are lot more things one has to do especially in understanding how the inorganic organic surfaces work just to conclude what we have seen so far spin and spintronics will pay way for future electronics number one and organics in spintronics is a fundamentally logical and plausible goal provided you have a ways and means to deposit this organic films in a very sequential way and spin polarized transport in organic is now proved even at room temperature if you can carefully look for a suitable combinations then you can achieve maximum spin polarized transport via organic layers and we can also say organic magneto resistance phenomenon opens possibilities for new application of this existing technology. So, we have actually in essence seen different phases of the MR phases of MR one we saw about a GMR which is in stacked multi layers and then we saw some examples of tunneling magneto resistance in trial layers we have seen some example of granular MR in bulk composites and we have also seen organic GMR where we are bringing the hyperfine interactions and the spin orbit coupling interactions into focus and we have tried to see whether organic spintronics can become a vital tool to address to the issue of magnetic storage. So, with this I will stop and we will continue with other examples of electrical conductivity in inorganic materials in the next lecture.


I would like to extend my heart to gratitude to you because my entire journey, initially you have been with me throughout my journey. Throughout the entire journey I was preparing for my IGC-Net. It was in the last August 2022. I did make a subscription to your course for 6 months and it turned out to be immensely helpful. Whenever we students prepare for the IGC-Net, we often wonder random things.  So the way you prepare and you have designed your course. If you have made it so beautifully, you know, me and my parents always say that whenever I was getting prepared for my IGC-Net, your boys truly become a part of our living. Every day. Who are you? Okay. Thank you ma'am. I'm fine. And at the very beginning, I would like to extend my heart to gratitude to you because my entire journey, initially you have been with me throughout my journey. Throughout the entire journey I was preparing for my IGC-Net. It was in the last August 2022. I did make a subscription to your course for 6 months and it turned out to be immensely helpful. Thank you so much. Whenever we students prepare for the IGC-Net, we often wonder randomly.  So the way you prepare and you have designed your course. And if you have made it so beautifully, you know, me and my parents always say that whenever I was getting prepared for my IGC-Net exam, your boys truly become a part of our living. Every day. I used to wake up in the night when I used to go to sleep. I always used to hear your records, your lectures or your lectures and I used to prepare my notes from them. And I heard almost all your lectures, ma'am. Since the August 2022 to February 2023 because the exam was in fast March, I heard almost all of your lectures and I made a note from them and this time to be really helpful. Thank you. Thank you so much Aditi. That really means a lot to me. I want to know a little bit about you, which city are you from and what have you done in your graduation and post-graduation? Ma'am, I am from Kamarpukur. It's the birthplace of Srirama Krishna, West Bengal. The holy holy place. Extremely ma'am, extremely. And it's also a place of international importance too. So many people from India and from across the world, they come here. They pay a visit to Srirama Krishna mosque. So I'm really lucky and blessed enough to have an opportunity to stay here. I did my honors from Vivekananda Mahavigalai, West Bengal. And I did my masters from the University of Bhatman. Okay. And you started preparing, you said in October 2022? No, August 2022. And you cleared net in the first attempt. Yes ma'am. I cleared net in the first attempt and I also cleared gate in the first attempt too with all India ranks 16. Oh my God. Wonderful. That is so appreciable. Congratulations for clearing both these dignified exams. I wanted to know Aditi from you a little bit about how did you plan your daily schedule? Like what was like, was it a fixed schedule or was it something that you did as per your mood? Ma'am, actually absolutely there's no such strict schedule was not there. Actually, I love to study. So for most of the part of the day, I initially for some months it was my only job to hear to all your lectures and preparing notes from them. And apart from that, the paper world preparation was also there. So these two were going simultaneously and I also, apart from preparing notes from your lectures ma'am, I sincerely attended to almost all the mock tests that you provided. And this is, I think it helped me the most in my preparation in understanding where I'm lagging behind and in rectifying my faults. Wonderful. Wonderful. And for paper one two ma'am, I did subscription to your paper one mock test series. The mock test series was there, I bought subscription to it and I was solving the questions and it turned out to be really very helpful. Wow, wonderful. Another important thing I wanted to ask you Aditi is that, so when you used to give mock tests, so suppose out of 100 you got 80 marks in the mock test, so what was your approach to look at those 20 questions which you did wrong? Yes ma'am, yes ma'am. Actually whenever I was giving the mock tests, whenever I felt that I am doing this question, so or I'm getting these questions wrong or I'm not being able to properly remember them, but I thought that there is a much more need to put an emphasis on my revision. That's the thing which I think is the most important one. And ma'am you can remember I think in 2022, October when the NATE was completed, you conducted a Zoom session for analysis of the question paper and I was present at the Zoom session and I asked you at the question, when I was just starting my, I just started my internet preparation and I asked you that ma'am, I'm making the notes, I'm hearing to your lectures but it often turns out to be that I'm not being able to remember the names properly, I'm just jumbling them up and then you told me that it's not like that once I read and it's done, three times, four times, continuous and I think most important a little parallel revisions. I mean if I read it and I close up the chapter and then after two months I think that I will be revisioning them. I, by the time I would have forgotten everything.   It's not possible that every day what I studied yesterday, I'm revisioning today, it's the best thing, best possible thing but always it was not possible but something I did that for next some days, for instance I am picking up the American literature module and for the next three or four days I would be preparing notes from your lectures and then I would be starting revisioning throughout everything and then I'd be completing that module and I'll move to the next one. This is something I did and whenever I used to make notes from your lectures and I was to revise, the mock test was the most essential thing. I mean I was very curious when my course will be completed and when I will be giving the mock test. So I can find out. Because you also have that analysis after every mock test. So it helps you understand that okay this is where I stand, this is where the topper stand, where am I. This is very important, very important. The kind of analysis, the kind of ranked chart, the kind of mistakes and whether it was just silly mistake or whether it was the wrong, it was the difficult questions that I got wrong or the easy questions and the analysis was very apt and very very helpful. It helps me a lot man. True, true, wonderful, wonderful. And one more thing I wanted to ask you Aditi, since you're saying that revision and mock test, these were the two things that really helped and shaped the operation. What do you think in regards to the importance of the units? Which are the most important units of UGC net? Plus like you would, how would you say that a person should start when he looked at the UGC net syllabus? Actually man, I think British literature is always the most important and also the most vast too. But when I started preparing notes from your lectures, I started with the smaller ones. I started with culture studies, then I think I moved to English in India. British literature course is the last one that I started doing because I saw that there are the 250 lectures and I think that let me at first get this done and when these notes are being done, then I will very comfortably and very... Relax with a piece of mind that you would do the entire... I will move to British literature. But I think man, each and every question, each and every module is equally important because often it happens that just for one question, one can miss the native, one can miss the Jats. And this question, where from which unit it would come, we have no idea. So therefore all the modules. All the modules, right. And one last question Aditi that what was your strategy to solve paper in the exam hall? So since you've cleared net in the first attempt, you must have thought of it in beforehand that okay, where I'll get those three hours and those 150 questions, 50 for paper one and 100 for paper two. How am I going to approach them? Ma'am, I started from paper one. From one to 50, I completed paper one questions and then I moved to paper two. Okay. So if there were questions which you were not able to attempt, what did you do in that case? Ma'am, actually, if there were questions that initially if I see that these questions about this, I have no idea. I used to mark these questions that I will be doing later. And if I find that often it happens that there are two options and there is a confusion between that this one or that one. So in that case, I would have marked the question for revision and that the way I used to proceed because time management is also something very important, which also I learned that in any examination, time management is something very, very important. And one thing I wanted to understand from you on the last note that what was about the cause that you really like, you would have started with something, you would have started at a point where you had no idea and then you gradually were able to understand through the course. So throughout your preparation, what were the things that you really liked about the course? Actually ma'am, throughout the preparation, what I personally felt that patience is the thing which is required the most. And for any kind of preparation and this is the first thing. And the second thing is that I never even read anything with any kind of pressure or with any kind of anxiety. I mean, I believe in this that I will try to give my best and God will take care of the rest because I can't read in a hurry. I can't read with always something happening in the back of my mind that I have to do this, I have to do this within this. And I just read freely. I just enjoy the process of reading and whatever I'm gaining, whatever new I'm learning, I try to assimilate them. And even in exam hall 2 ma'am, whenever I'm seated at the exam hall, I try to give my best and whatever happens, it comes with God's grace. So this thing I really learned and with your course, something that really very amazing happened that a clear direction was provided to us because so that I didn't have to wander through this and this, this writer and this writer. So my preparation was going in a very strict and very relevant direction since the very first day. And for the first time I bought your subscription and I saw the writers who have provided and the mind maps. So this is something ma'am, I think also very important, a proper direction, a proper trajectory is really needed. Yes, an organized way in which you know that, okay, this is, I have to complete. Yes ma'am, this is also a belief in that if I do the hard work in a random way, in a Brownian motion, that something this, sometimes that, sometimes this and I don't think it is that much beneficial. Rather if I have to channelize my effort in a way, in a particular way and this channelization, it really came from the way you have designed your course. Thank you so much. Thank you so much Aditi and I would want to congratulate you and your family members for this achievement of yours. And at the same time, I'm going to wish you all the very best for all the upcoming milestones that you're going to clear, especially the the GRF that you are trying for, for the December as well as for the set exam that you are going to sit for. And I'm really, really hoping that just like gate where you got all India ranked 16, you are going to be the top performer in the next net as well as the set. Thank you ma'am. Thank you ma'am. My best wishes are there with you and I would really pray that you succeed in every endeavor that you do. Thank you so much. Thank you for taking out time and sharing your experience with us. Thank you ma'am. It's indeed an honour to have an opportunity to talk to a person like you. And it's really, for every student who is aspiring for UGC net, your course is something really amazing, amazing.  You have designed your course with so much love. This is really, really extraordinary. Thank you ma'am. Thank you. Thank you so much for your kind words. Thank you. Bye bye everybody. Thank you. Bye.


Tonight, we're talking about youth addiction to mobile phones, and with me in the studio is Zakia Rashid, a counseling psychologist, and Lin Zinyawaira, a teenager who is going to be given as experience as far as the addiction to mobile phones is concerned. You can be part of this conversation by tweeting and sharing your views and comments on our social media platforms, that is on Y254Channel, hashtag Y254News on Twitter, and also Y254Channel on Facebook. Cell phone addiction is a modern phenomenon and has put many traditional assumptions to the test. In the past, addiction meant something different to parents, where parents were more worried about their kids being addicted to cocaine, heroin, and nicotine. Today, the addiction landscape has shifted. Teens hooked to their smartphones for seven hours on average each day. Cell phones addiction goes well beyond texting and talking. It includes apps, games, and in particular social media. For teens, cell phones have become a way to comment and criticize, approve and admire. They're not always communicating with friends. Often they are commenting on the activities, checking for likes and responses to their own posts. The clinical community defines cell phone addiction as a behavioral disorder, which means obsessive views that affect everyday functioning. Like any addiction, once triggered, it can be quite difficult to stop. These are biological components to this behavior. The brain reacts to the cell phone, as if it were a drug. Studies have shown that both the phone ringing and the alert of a new text cause a brain to release dopamine. So that is basically some of the effects that the mobile phone or that is how far addiction has really become. It has become an issue of concern in the society that is in Kenya and even globally. But tonight we seek to understand how far can you stay without checking your phone? Or how many times in a day do you check your phone? And starting this discussion tonight, I would like to start with my first question directing it to Lindsay, as a young person probably. How many times do you check your phone? And for those times that you're checking your phone, what would you be doing? To start with, I cannot do without my phone. So sometimes I usually check on nothing, but I just have that habit that I need to have my phone. So sometimes I even have this behavior. When you're talking to me, I'm looking at my phone. But when you ask me, what are you looking at? I can't answer. Probably I'm looking for new notifications because I'm in social media sites. I'm looking whether my tweets have been retweeted or whether my Instagram pictures have been liked or whether there's something trendy so that I can actually post it or be the first one to retweet it.  This is not something that is only affecting the teenagers as much as the teenagers are the higher percentage of people who are getting addicted to their phones. Adults to these days, most of the times you find them who are on their phones, especially people driving. You can find someone they are driving. And maybe when they're waiting for the green light to say go, people will go to check on their phones. How many times in a day do you check your phone? OK, thank you, Patricia. And I'm laughing because I found it a little bit. It's a tough question. I can't, I may not really be able to count the numbers, you know, in terms of how many times I check my phone. But I can say that I'm very much sure that I may not exceed the limits why I say I'm addicted to my phone. Personally, I can leave my phone home, go to work or go to town or go to wherever, and I'll not crave for my phone simply because I left it in the house or even rethink of going back to go and get my phone. I'll just say, I forgot it, so be it. Let me move on. I'll get in the evening and check what called, wasn't called and life goes OK, we are living in an era whereby parents, when your little baby cries, you just give them your phone. You put on a game, put on a cartoon for them and give them that phone. Parents are more secure these days to have their children in the house hooked in their iPads, the phones and everything, then have their kids playing outside. So probably what would you say is at the dangers that parents are giving or exposing their kids to at such an early age? First of all, I can say it is really sad that such situations, scenarios are happening because we think that sometimes I think we do the parents do this in, you know, unintentionally because sometimes they are also busy. They are also caught up in their own issues and they don't stop to think that when I throw this phone at the child to start looking at it or whatever, I am causing damage to this child. First of all, health wise, it means that these phones have lots of, you know, what we say, things that are not OK, health wise. They are using things like radio shows that all those things are happening in the phone because these things you are told they are not even good when you sleep around them because they emit certain let's say gases or are usually not good for the health. So when we leave the children with these things already from day one, we are it's health hazard to the children. We are causing them damage, health wise, and we are not so sure what is happening. And this is not some of the things that are happening. Like, you know, there and then this is things that are happening systematically. So with the time we may realize this child may not be feeling well. Maybe the ears are not hearing well. Maybe somewhere there may be this eye damage, ear damage. And yet we may not be able to trace back and say this is the phone until maybe an expert gets to tell us that this has happened because of the phone. So sometimes we forget that this is a thing that may happen. We just rethink think of it's now here and now I use this as a toy. That is not a toy. A phone or any other mobile device is not a toy. OK. So Lindsay, for you, when at what age did your parents get you a phone? I got my phone when I was in class seven when that was when I was 13 years around. And do you have do you have siblings? Do you have younger siblings? Yes, I do have younger siblings. And do they have do they own mobile? Yes, they have mobile phones. Actually, a case scenario is when my young brother wanted a phone and my dad didn't really was wondering, where do you need a phone?  You're still learning. Actually, you just hear once in a while on Saturdays and he had to cry for that phone. And he had to get it because his reasoning was every person has it. How am I supposed to get it exactly? And just as one thing I know is we are times have changed. We also learning so much from technology myself. I'm the kind of woman who will give my daughter the phone because there's so much they're learning rather than playing with kids outside. But sometimes don't you think that it's damage? For example, if I asked you, what does your brother do on the phone? Like what type of content do they assess on the phone? And how many times probably how many hours do they spend on that phone after school? To be honest, we don't check because there's a time he actually the reason why my parents bought him a phone, other than the fact that his friends have a phone, it's because he had once logged in using my mom's phone on Instagram. Then my mom saw some messages on Instagram and he was like, I have to get you a phone because I don't want to be receiving such content on my phone. Zakir, having to hear that, this parent was so concerned. But she saw some type of messages that she was like, I don't think these messages are supposed to be channeled through my phone and deciding that I'm going to get my son his own phone. As she helped or is she just like creating an avenue whereby now these messages can keep on coming. This kid can keep on assessing such content over the phone. It is really again very sad because it's like you're trying to, you know, dig up one hole and covering the other. So it is not a helping situation because it means simply means that in that situation, it means that it is OK for that child to get that information. So long as the mother does not see it, it does not come through me. It is OK. Whatever he takes, it is OK. But the question is, is that really OK? Because what if that content is not so good for that child? Because depending on what the mother saw, it could be detrimental information. But is it OK if the child gets to see so long as that is his or her phone? That is the question. So I think these are misplaced priorities. We tend to think that by making, giving them their phones, we are actually settling the dispute, making the situation better. But you are making the situation even worse because I'd rather this child use my phone, I get to see the information that's channeled through my phone and get to deal with it. How I talk to my child, how I make them understand that maybe this content is not for them or there's a time for this content than hide that information by making sure that it does not pass through me. OK. I really like what you've said. But now, do you think at what age, probably, would we say these kids should be now allowed? I know we are saying that technology is there are a lot of innovations, but are we going to let these innovations cost damage to our kids, to our sisters, to our younger brothers? The answer, Patricia, is no. We should not let these technology damage our children, our sisters, our brothers and our friends. The thing is we cannot say that there is a specific age set for a child to get a phone, but as parents, as the people concerned, as the significant others, there are some questions we need to ask ourselves. For example, a seven year old, what are they supposed to get a phone for? Is it because they're accessing school material? And if it's a school material, what kind of school material is that? That they're not getting from school. It has to come from the phone. Second, is it communication? Because if it's communication, where is this child for this person to be able to communicate with? Because as a parent and as a seven year old, it means either there's a man in the house, if I want general information, I have to call the man and say, I want to talk to my child. I don't have to call that child straight away. Then if it is another, you know, that kind of communication again, I do not have to communicate to the child directly, especially when I'm not around. Because some parents have argued that when I'm at work, when I'm doing this and that, I have to call my child get to know how they are doing. I can just be asking the nanny, but you brought that nanny there and you trust that nanny. That's why you brought that child to the house in the first place.  OK. Yes. So in terms of addiction, Lindsey, would you say you're addicted to your phone? Would you say that you're addicted to your phone? Of course. For me, I'd say yes, I'm addicted, but it's a disorder. Yes, I'd really say that yes, I'm addicted because I cannot concentrate without my phone. Like you said, if I left my phone in the house, I would go back for it because I can't imagine a day without it. A case in scenario is when I was traveling and then my phone got stolen in Amatatu. It was 10 p.m.  Hey, my phone has gotten lost and I can't come home. I mean, no, not even that. I'm standing at an M-Pesa shop and they're selling phones. My mom said, but you know, those phones are not legit. I was like, let me just buy it for tonight because it's not expensive. What did you say at the moment you're by your phone gets lost and you cannot you can't go home? This is it's 10 p.m. And you feel like these attachments that you have with your phone, you can't go home. Can't you call that addiction? Is that addiction? Maybe probably let's like here as a counseling psychologist to help us with that. Because she has said she cannot leave the house and probably learn that she has forgotten a phone and go about the day without going back and taking that phone. Is that not addiction? That is lazy. I'm sorry to say this. That is addiction, you know, addiction because again, we ask ourselves how do we assess to get to know that this is addiction and this hasn't reached the point where we call it addiction.  I can keep my hands off my phone for even a whole day and have no problem with that. But now if you cannot keep your hands off the phone for even five minutes or the phone has to be wherever you are seated, you see, people are eating and the phone is just there. You see, people are talking to someone and they have become a behavior in church. It's a big deal. You can imagine the phones while the pastor is up there, you can imagine. And then we also say that when you see an individual now you are going to bed and the phone has to be somewhere next, which is again is also a health hazard. Yeah, people sleep next to their phones and we've seen even in social media, there are some social media telling us how things are exploding, you know, around them, people have died. That is if at all it's true. But again, we say, yes, it's a health hazard to even our ears, to even our eyes, to even our brains. So we are actually feeding our brains with a lot of stuff about just hearing and, you know, getting the information. So that is addiction because again, we say, for how long can you stay without a phone? And we say, if you stay without a phone, do you get what you call withdrawal symptoms? That if I don't have a phone, I'm agitated, I have anxiety, I'm almost getting depressed. That is, yes, preoccupation with the phone. Most of the time you are preoccupied with a new phone in town, the new make, the digital one that already says there is something. OK. Linda shared with me something that was still working in. I hope you allow me to share when she said her phone is just not a five thousand shillings phone. And every other time she has this phone that costs her almost a fortune, she will still crave for another one, which costs more than that. What are you doing with all this? It's because of that craving for new money. You know, the idea or the thought is that when I get this one, it's so modernized, even the material, the content will be better. You know, I'll be getting good pictures. I'll be getting, you know, the information is very clear. The pictures are so good and all these things put together and make people, that is addiction. OK. We're going to take a very short break. And when we come back, we'll be talking about how phone addiction affects sleep patterns and health wise. And don't go far away. We have way lots of things to cover on this discussion. We'll be right back on my two five four news updates. Why two five four, imagine. That's what I'm talking about. Pro-exclusive entertainment. Oh, thank you for staying with us on why two five four news updates. And we're talking about youth addiction to mobile phones. You can be part of this conversation by sharing your views and comments on our social media platforms that is on Twitter at why two five four channel, hashtag why two five four news and on Facebook at why two five four channel. So we're going to look at I'll just go through some of her effects of mobile phone overuse. We have social comparison. We have health problems. We have anti social tendencies. We have we have psychological problems. And then we have night time for news. We realize that using mobile phones, some people don't sleep at all. So we have poor sleeping habits, depression and delinquency, self esteem and emotional well being. We have fun, fun time replaces sleep, content stimulates brain, depressed teenagers use social media more and screen light suppresses melatonin. When you tell a young person that being on the phone, most of the times it's going to affect the sleep patterns. They seem to argue with it because you've gotten used to this. It has become a habit. So you don't have struggle sleeping. You're used to the two hours at probably four hours you get to sleep. So, Zakia, what do you think now should be like? What do we tell to these young people? How do we convince them that this thing is so, so dangerous and you guys like need to fight other activities that are more productive to do to engage you? OK, thank you, Patricia. I think first of all, sensitization is very, very important in what we call now psychoeducation because telling somebody that this is not OK without any proof sometimes becomes so difficult because they are not in a position to see the effects. You know, the effects are not tangible. It's not something they can see and say, OK, I just didn't sleep yesterday or I spent a lot of time on phone today. I have, for example, a headache. But some of them even go through that. They can actually associate their headaches and all that with the issues with not sleeping because of their funds. But they still do not want to admit to the fact that they are not OK. So what we say that a lot of psychoeducation is very important. And in psychoeducation, we have to involve the medics to make them, you know, you know, make people understand that this is not just a short term kind of effect. It takes time or it happens after a very long time. And you may not be able to see it, you know, through the naked eye. It is something that is happening internally. Like now when you are talking about cancer, we are told some of cancers are because of radiation. Now this radiation, all these things are through the phones. So when you are sleeping and your phone is just next to your pillow or just under your pillow, what do you think is getting inside your body? So if you do not psychoeducate them in this manner to make them understand, then it's just to send their phone. But they ask you how, you know, how now and you cannot prove because you have nothing tangible evidence to tell them. So that is very important. Second, let's be able to assess their performance because most of the time the youth, especially, you know, the millennials, as we call them, we have to assess the pattern of their performance and that we are able to argue with them because some of them, in fact, majority, will not be able to perform well, for example, in schools or even at work. They will sleep or even oversleep because if somebody sleeps at three or four and they're supposed to work up at, for example, six, you'll find some of them are just dozing off in class. Some of them who are going to work will not even go to work around the time that is supposed to be there and they will not be giving so many excuses. In fact, when you go to an office and find people giving so many excuses, yesterday they had this excuse to go to work.  Just to prove that and did something happen. That's why I'm coming late. So when we see these people or these kind of excuses, then we are able to tell something is not right and we should be able to talk straight forward to these people and tell them something is not right with you, kindly go and get help. OK, so Lindsay, we've talked about how phone addiction affects someone's sleep. There are also cases whereby it can affect the position which you are as you use your mobile phone. Sometimes the spinal cord or the area around the neck can be affected. Having heard about all these things, what do you think probably as a young person, because now you represent the number of young people out there, what do you think can be done as a young person? What other activities do you think that youths can be encouraged to get into, to avoid being on the phone for a very long time? So first of all, I think more activities that entails people. It could be sporting activities because that will keep you busy off your phone and you need to get time, you need to get even time to actually touch your phone. That's one. It can also be these gatherings that happen and then you have talk sessions, those activities we have drama. You see, these are activities that are very strenuous and sometimes you don't even get time to even have a break and have your phone. Let's even talk about gym.  So some of these activities that will actually put you so much on it so that you can even get time to go and use your mobile phone. As was speaking earlier, you talked about social media.  If after this show, we were to take a picture and you posted it on your social media platforms, let's say Facebook or Instagram, and you didn't get like, how many likes would you get and feel like I now call it? First, my achievement is how many followers do I have? How many followers do you have on Instagram? For example, I have a new account and the new account that I opened actually last week. I'm only following 40 people. But my following is 2000, I guess. Oh, God, and you started last week? Yes. And when I started my Instagram account I said how many followers I have? OK, so actually, I'm very key. If I put a picture right now and in seconds, I don't see any like, then I remove it. But why? Because that is like you're going now. You're seeking validation out there. There you want. Yeah, you're seeking validation out there. Don't you think that this is something that you really need to work on? Not really. What I think is in social media, what do people want to see? For example, for you to have such a following and get your following very few, which doesn't really happen, then if I take a picture right now, holding this mic, do the kind of followers I have, do they want to see that really? OK, for example, if I place this picture probably on Twitter, I'd get so many likes because people will be motivated. Oh, OK, she was talking about this and this and this. OK, so Instagram people don't like people holding mics. No, that is what you're trying to say. They don't want to see your audience. You see, you see, Instagram is not really serious. You see, Instagram, you'd get more likes, for example, if you took a picture on the beach. OK, understand. But then don't you think we've had instances whereby young people have committed suicide because they posted a picture, someone did not like them. People commented so negatively about them and there was no one to see it because we've taken this thing to be a very normal thing. And people have done terrible, terrible things because of it. Don't you think this is something that should be addressed? Don't you think we need to have better ways on how to make people feel validated before you get to social media and seek for validation from there? To be honest, yes, at some point, because I can tell you, recently we had a case of a person on Twitter. Twitter is known for the mature people and the working class. But also we saw how people, actually, even celebrities, attacked a young guy calling himself an entertainer who is actually a brand. Yes, and the last comment that guy gave was, I don't think I deserve to be in this world. So from that, you can see that also social media comes with its own pressure and it needs to be very strong because this is someone whose image has been circulating. And this is someone who people have been retreating his image. And so he's even shy to even stand up and approach people because he's lost his credibility. Yes, OK, let me go through something here. In 2008, China became the first country to declare internet addiction among children as a clinical disorder, according to gaming companies and advised gaming companies to set a cap on how much time children can spend on their playing online. Twenty four million young people in China are estimated to be internet addicts as a result, the US government also started a program last year whereby people can go to be treated or it's a rehabilitation center from to help you now heal from from addiction. And also the Chinese government has four hundred centers. Do you think Kenya needs one of these centers? Do we need one? We don't need one. Patricia, we need many. OK. We need many. Why? Because we have to nip this problem, this problem in the bad. We don't have to wait until, you know, looking at our population and China's would say, yes, we are very few and maybe we need one center. But no, it's not one because looking at the towns that we have, the cities that we have, maybe we should say in each and every city, we should have a center so that people are able to access the center. People are able to get that kind of assistance or treatment as early as possible. Because this is what we say. Addiction is a brain disease. That is what people are forgetting. They just think a brain disease is only when I take alcohol.  No, this is a brain disease. And once this problem gets into the brain, believe you me, getting out is a very big problem. Yes, it needs a lot of medical intervention. It needs a lot of counseling. This is psychological intervention for some people to be able to get out of it gradually because getting in wasn't that quick. Even getting out isn't that quick as well. We need this kind of assistance too. Yes, we need the centers, not one, but many, especially within the cities because this problem is growing within the cities.  We go to the village and we still already see people already catching up with the internet and all these things. And where this data, believe you me, a lot of things are happening. Yeah, it's true. So we get to say, yes, we need them. And as much as we have them again, this is not the only thing that we can do. We also need to start dealing with this problem from the household level. It doesn't have to get so clinical. We can start from the household by what, like, for example, Lyns, you were sharing. Can we encourage our children to do all these other activities instead of just trying to suit them with phones?  Can we go with that child to the kitchen? As I cut onions, they are cutting tomatoes and doing this. Sit them on the working space there and let them take a blunt knife. Let them do something. So instead of just leaving them there in the living room because with a phone, they'll be very quiet. Then again, when you talk about these activities, how we encourage children or the youth or the youngsters to participate in these activities because even as you say, the youngsters or the youth, even the grown-ups, just as you said, they are also part of this. Some of them have really gotten so addicted. It is shocking. A whole grown-up seated there, you are talking, for example, Zavista has come to the house and you are there talking and the person is busy on the phone and you wonder, am I really needed here? Okay, yeah, that has become a very big problem. So, Lindsay, last year France banned use of mobile phones in primary schools and high and middle schools. As you wind up, what do you... If Kenya decided to have one of these centers in every county, what would you advise? What activities do you think people like you would be interested in so that we get people who have the mobile phone addiction? Probably, we would invest in sporting activities, let's say swimming, let's say things like hockey, some of these sporting activities that really strain you, such that even at night, you don't even have time to just go and sleep, you know? And also, you're able to interact with people because one thing that comes with the phone also is your sociability, it decreases. So now, if I find you interesting, then there's a reason to put my phone aside. Okay, so thank you very much, guys, for really finding time to talk about this. I think we'll have another day where we get deeper into social media and bullying and all these things because it's quite a very big topic. But what I can say is technology is good. I'll be not going to say that technology is not a good thing, it is a good thing that is happening to us, but the thing is, parents maybe have, confused, have limits to when your kids or when your teenage kids are at home, have them go out there and socialize and mingle with others even during events that are at home. So that is how we hand for you tonight on Y254 news updates. My name is Patricia Murioki. Do have yourselves a very good night.