Yeah, now the next is write down state variables. What are the state variables all these terms? We will understand today. Okay, there are so many terms. We need to understand processes we need to understand because we'll be using these terms very frequently in this chapter. We haven't done this kind of thing chapters before because we were doing atoms new gas pressure volume, right? P is equals to NIT density electrons proton that is what we were discussing, right? But this is different. Okay, we are having a different different terms that we will be using. So first of all, you should be familiar or comfortable with all these terms, then only you will be able to understand the concept. Okay, a state variable is not that the state variable is something else. You're talking about a state function, that is what I'm talking about. Okay, terms you understand properly. The one that you are talking about depend upon a state not on path that is a state function. Isn't it? I'm talking about state variables, state variables means what? Suppose the position of an object. How do we define the position of an object? What I'll do, I'll take the help of Cartesian system, Cartesian coordinate. So I can say this point A is 3 unit on x-axis and 2 unit on y-axis, 3, 2. So the coordinate of this point is what? 3 comma 2? Yes or no? So this is the variable we are using to explain the position of point A there. Yeah, that's right, that's right. Okay, so what are variables we are using to explain the or to define the position of an object, which is mostly gaseous over here. Correct. So in gaseous state also we have discussed it that the variables are pressure, volume and temperature mainly. Okay, a fixed position will have a fixed pressure, fixed volume, fixed temperature. Correct. That will change only when the position will change. At this point you see we have a fixed value of pressure here, a fixed value of pressure, volume and temperature. If you change the position somewhere here, then here we'll have some different value of pressure, volume and temperature. So variables are what? Variables are the terms which defines the position of an object. So mainly for objects like heavier object, now that we use Cartesian system, here for gaseous we use pressure, volume and temperature. Understood. So this we call it as state variables. Sorry, write down the definition quickly, all of you. Definition write down. Variables which defines the state of a system is called state variable. Variable which defines the state of a system is called state variable. Example, we have mainly three state variables we have. That is pressure, volume and temperature. Three state variables we have. Okay, next I'll write down when all the variables, when all the variables, state variables, when all the variables are fixed, not changing, it is fixed. Then we say that system is at particular state. When all the variables are fixed, then we say the system is at a particular state. So you have a state over here. This state will have certain pressure, certain volume, certain temperature and this will have certain volume, certain pressure, certain temperature. So suppose this is state A, this is state B. So here we define pressure suppose P A, V A and T A. Okay. And then here it is P B, V B and T B. Now how do we get this, how do we have this change in a state? Okay. So we can have various possibilities. So we can go from A to B by infinite number of parts basically. We say there are infinite number of parts but practically it is not there. We have to study four, five parts over here. So point I'm trying to make that you can go from point A to point B. There are many different ways, right? You can go like this. You can go like this. There are many different ways we can have from A to B if you want to go. All these different parts that we have, we call it as process, understood? Process. You must have done isothermal process, isometric process, isochoric process, reversible process, irreversible process, many things, correct? So the path by which change in state variable is there, right? One or more than one, that is not the problem, right? If only one state variable is changing, then also we say a system is under process, okay? If more than one state variable is changing, then also we say the system is under process, okay? So all these paths by which change in state variables is there is possible. We call it as processes, right? What are different, different processes? We have few examples I have given you, right? That is isothermal, isochoric, isochoric, adiabatic, many other things, right? So all these state variables we will see, sorry, process we will see later on, but that is how the change in state possible by different, different paths which we call it as, you know, which we call it as processes, correct? So state variable is this, next. Right on next, thermodynamic properties, thermodynamic properties. See, mainly we have two types of properties. The first one is extensive properties and the second one is intensive property, okay? First you write down extensive property. These are the properties, these are the properties which depends upon, which depends upon mass or the amount that you are taking, right? Amount or mass that you are taking, okay? Extensive properties are additive in nature. We can add two extensive property. Example I will tell you, with example you will understand additive in nature, additive in nature. So example if you see of extensive property, examples we have mass. Mass is an extensive property, isn't it? Okay, you have an object of 2 kg mass. For example, suppose this is the object of 2 kg mass we have.  What is the total mass here in this direction? What is the weight component here?  Yes or no? This kind of question you must have done in physics. So this is why we are adding the 2 mass here, right? 1 plus 2 because mass is in extensive property. We can directly add the 2, okay? So other examples, examples you must remember in need exam, in others exams also, they have asked this question many times that which of this is an example of extensive property, okay? The first definition the mass I have given, the example I have given that is mass. Then we have moles, then we have volume, then we have energy, energy, U, internal energy. What is H stands for? Tell me what is H stands for enthalpy? What is G stands for? Gifts free energy. What is S stands for? Entropy. S stands for entropy, correct? So all these terms are extensive property, right? Apart from this resistance is an extensive property, okay? Heat capacity is also an extensive property. Examples you must remember. I will tell you a few tricks by which you can memorize, you can understand the examples, but yes, you have to memorize this, important this one. Whatever we have done so far, this portion is the most important one. What is density? Density is intensive, right? That's why density is non-additive. You mix oil and water. Yes, you mix oil and water, so you cannot say the density of the mixture would be density of oil plus density of water that you cannot say, correct? And one more thing you can understand. If you take water, so if you take one spoon of water or one bucket of water, the density of water won't change, right? Right? That's why density is an intensive property. That intensive property is what is the one which is independent of the amount or the mass of the substance. So the second property, thermodynamic property you write down, that is intensive property. Intensive property, we have many examples, write down, these are the properties which is independent of, which is independent of mass, independent of mass and non-additive in nature. It is non-additive, non-additive. Okay. Examples of intensive property, we have pressure, intensive, then we have temperature, pressure, temperature, density, intensive, all concentration term.  Molarity, molality, concentration term are intensive. Okay? Mole fraction also a concentration term, intensive, correct? Boiling point, boiling point intensive, melting point intensive, boiling point, melting point intensive. No, molarity won't depend upon mass, it won't change. You take two liter of coca bottle, correct? And you put this into a glass, right? So the glass one and the bottle one, the test will be same, it won't change because molarity is same, concentration is same, right? Boiling point, melting point, we have conductivity, we have conductivity, resistivity, conductivity, resistivity, molar volume. See one very important point I'm telling you here, volume is what? Intensive or extensive? Volume is intensive or extensive? Yes, so volume is extensive, but molar volume is intensive because molar volume is volume of one mole, right? Molar volume is the volume of one mole, hence it is intensive. So whenever you see this term, molar term are specific. Okay, molar term are specific. These two terms, if it is mentioned there, it means the entire term is intensive in nature. Molar means for one mole, specific means for one gram, are you getting it? Yes, tell me, whenever you see molar volume, molar enthalpy, enthalpy is what? Enthalpy is extensive. So if I write down molar enthalpy, it becomes intensive. So molar term is mentioned, it is for one mole, it is enthalpy. It is intensive. Molar enthalpy is intensive, okay? Molar entropy is intensive because molar term is written over there. Molar entropy is intensive, okay? Heat capacity is extensive, correct? Heat capacity is extensive, but molar heat capacity is intensive. Yes, yes, molarity is also intensive, yeah. Molar heat capacity is intensive, right? Specific heat capacity, again specific heat capacity, intensive. So whenever you see molar or specific word written, it means it is an intensive property. Without any thought, you can go with this, okay? Refractive index, reflective index, intensive, okay? Viscosity, viscosity, intensive, surface tension, intensive, dielectric constant, dielectric constant, intensive, pH value, intensive, EMF of the cell, of cell, intensive, copy this down. What is solubility? Intensive or extensive? Solubility is intensive, okay? Because the definition of solubility, if you see, it is the ability of a compound to get dissolved in any solvent at a given temperature. So it is temperature dependent process. Usually, you don't define this in intensive or extensive, but if you ask, we'll take a particular temperature and at that temperature, no matter what amount of solute you have put in, a fixed amount will get dissolved, okay? So it is an intensive property. One more very important relation you try to understand in this. Density, we all know. Intensive or extensive, we have seen density is intensive. Density is equals to mass by volume, mass by volume. If you look at this, density is an intensive property. Intensive property, mass is extensive property, volume is also extensive property. So from this definition, you can easily define that when the ratio, if you take the ratio of two extensive property, it becomes intensive in nature. So note down this point, the ratio of of two extensive property, extensive property becomes intensive, becomes intensive, okay? Another example you see, we have a mole fraction, mole fraction, mole fraction what we can write, given number of moles by total moles. So moles are extensive only. So extensive, extensive, this becomes intensive, right? So this formula, this, you know, observation you must keep in mind. If you get confused in the exam, you can think of this way also. Formulages you try to recall from that also you will understand. Clear? No doubt. Okay. One more question. Delta T is intensive or extensive? Change in any variable. Intensive or extensive? Yes, intensive. Change is always intensive. It has nothing to do with the temperature that you have taken. Change if you find out, so it is always intensive in nature. Yeah. Next write down that is thermodynamic functions. Okay. Okay. Write down next. Delta T is intensive. That's what I said. No. Next write down thermodynamic functions. Thermodynamic function, we have two types. We have of two types. First one is state function and the second one is path function. State function is the one which is independent of path. Independent of path. For example, we have pressure, volume, temperature, enthalpy, internal energy, entropy, Gibbs free energy, etc. Path function is it depends upon path. It depends upon, for example, we have heat and work. Suppose you are at this position A. You are supposed at position A and if you want to go to position B, there are infinite number of paths possible. One is this. You can go directly from A to B. One possibility is this. Another possibility is you can roam around and then you can come to this point B. Okay. Another possibility is you can go to some other point and then this and then this. You can go. Means the point I'm trying to make, there are infinite number of paths possible here.  Depends upon the wish. But the thing is, if you choose the longer path, you have to do more amount of work. More amount of fuel you have to use. That's why the work done and heat required, energy required, it depends upon the path that you choose. But if you talk about the pressure at point A, if it is PA and pressure at B is PB, or for instance, if I say volume is VA, VB, TA, TB is the temperature, no, like it doesn't matter what path you choose. The pressure at B is always PB. It won't change. It does not depend upon the path that you are choosing. That's why these variables depends only upon the state of the, you know, of the system, at what state, at what position the system is. Based on that only, we have the value of PA, PB, pressure, volume, temperature, enthalpy and all. But heat and work, it depends upon what path you are choosing. Hence, these two are path function. This is the state function. Thermodynamic equilibrium. See in thermodynamics, we'll deal with the system which are in thermodynamic equilibrium, always, whether it is mentioned or not. We always consider the system which are in thermodynamic equilibrium. Okay?  Correct? Thermodynamic equilibrium is defined when a system is in, when a system is at, when a system is at thermal, chemical, mechanical equilibrium, all three kind of equilibrium, thermal, chemical and mechanical equilibrium, then it is said to be in, then it is said to be in thermodynamic equilibrium. All three equilibriums are there, then thermodynamic equilibrium. We'll have a chapter of equilibrium also, chemical equilibrium and ionic equilibrium, which we'll discuss after this chapter. Okay? There you will have the understanding of what does this equilibrium means. Okay? Briefly, I'll just give you the meaning of this, what is thermal equilibrium, what is chemical equilibrium and all. Right? Thermal equilibrium is the one in which the two object or two system is at the same temperature. Like, for example, if I have this object at 100 degrees Celsius and I have the another object, which is at 10 degrees Celsius, for instance, I'm saying. If you connect these two or if you keep these two in contact, then what happens from 100 degrees Celsius, the heat starts flowing into 10 degrees Celsius because of the difference in temperature. So after some time what happens, both system will be at the same temperature. Right? And when the temperature is same, there is no more heat transfer because the two object or system is now, is at thermal equilibrium. So thermal equilibrium is what it is based upon the temperature. Two system is at the same temperature. They are set to be in thermal equilibrium. Clear? So thermal equilibrium is based upon, based on temperature, constant temperature we have in the two object, two system, chemical equilibrium. When we have constant concentration, if concentration is not changing, constant concentration, concentration changes, but the rate of change is same. Okay. So overall, you know, the concentration is constant only. Last one is mechanical equilibrium. What is mechanical equilibrium? Right? When we have equal pressure, equal pressure, mechanical equilibrium you can understand. You have an object like this and suppose you are trying to pull the object with some force 10 Newton and same amount of force you are applying in the opposite direction 10 Newton. Then we have equal force in the two direction, equal pressure we have. Right? Then this object is said to be in mechanical equilibrium. So when these two, these three equilibrium exist, then the system is said to be in thermodynamic equilibrium and in thermodynamics deals with thermodynamic equilibrium only. Next. Next we have thermodynamic processes. Definition you write down. It is an, what is the process? So it is an operation by which, it is an operation by which a system is changing its state, is changing its state. It denotes the path, denotes the path followed, followed by the system, denotes the path followed by the system while changing the state. If you talk about change over here, change we can also have three types. Change if you see, we have three types we have here. The first one we can say physical change or phase change. Physical change or phase change means what? Solid to liquid conversion, phase change we have. And then we have chemical change and then we have state change. State change means variable is changing, pressure, volume, temperature, right? State change means state variable. It's not the physical state, it's a state variable. So we have this physical change means solid to liquid conversion, liquid to gas, gas to solid. This conversion we have here. This is the change one. Chemical change is mainly deals with the reaction. So reactant to product, the change we have. Reactant to product. And state variable changes means the change in pressure, volume, temperature. So mainly we have this one. The third one is the important one we have here. Copy this down first. Okay. Different processes that we have here, you see, the first process is isothermal process. Isothermal process. Second one is isometric process. Third one is isochoric process. Isochoric process. All these things we have discussed. Then the fourth one is adiabatic process. Adiabatic process. Fifth one is cyclic process. And apart from these five, we have two more processes that is reversible and irreversible. We'll discuss that after this. What is isothermal process? We have constant temperature. Isobaric bar is the unit of pressure. Iso means equal. So we have constant pressure. And the third one isochoric is constant volume. Adiabatic process I have told you. There's no change, exchange of heat. So delta Q is zero for adiabatic process. Cyclic process, initial and final state is same. Initial and final state is same. Okay. For example, you see, this is pressure. This is volume. This is pressure. This is volume. Okay. Now the process, suppose it starts with the point A goes to B, then B to C, C to D and D to A. So it's a cyclic process. Initial and final state is same. Okay. This is also a cyclic process. Obviously you see there's a cyclic process. Right. So cyclic process is the one in which initial and final state is same. Since initial and final state is same over here, so all those variables which are, which are state variables change in all those variables, state variables are zero. Because delta P, if you write, it is PF minus PI. Right. It is final pressure minus initial pressure. But since the final and initial position is same only here. So PF and PI is also equal. And that's why delta P is zero. Similarly, delta V is zero. Delta H is zero. Delta U is zero. Delta T is zero. Right. Delta G is zero. All these change in state variables are zero in cyclic process. Yes. Did you sign it out? Copy this out? Yeah. Finished all of you? Done? Okay. Suppose if pressure volume graph is given, then how do you find out the work done? Just I'm asking. Tell me. You know this? Have you done this in school? No. Right. Okay. Pressure volume graph, if it is given, then directly you can find out the area under the curve. That would be the work done. Okay. Directly. Suppose if I ask you, what is the work done in this process? A to B, B to C, C to D, D to N. Then what you will say? You will find out the area of this. Yeah. P delta V. You'll find out the area of this rectangle. And you'll say, so this is the work done. So that's fine. Okay. But this we can do. We can find out area only if PV graph is given. If PV graph is not given, you cannot find out this because work done is P delta V. So pressure volume graph you must require. So sometimes what happens in the question, instead of PV, they'll give you PT graph or VT graph. So you should know how to convert a PT graph into PV graph or VT graph into PT graph. Means this conversion you should know how to convert one graph into another graph. So let's discuss one example on this. Conversion of graph, graph conversion heading right down. How we'll discuss. We'll discuss after this. This we haven't finished. Reversible, irreversible after this we'll discuss. Okay. Let us finish this first. Right. So the process that we have discussed, no, based on that only we have this. So we'll finish it out first. So suppose here. So this axis is given. It is PT pressure and temperature graph. This is P. This is V. This is PV. This is VP. So this graph is actually given here. Passes through origin constant temperature. This is the graph we have. Okay. And it is given here. The process is going from A to B, A to B. Then we have B to C and C to A. This is a graph given. You need to convert this into the pressure volume graph. Now how do we do this? You see. Could you tell me the process AB? What is this process? AB. What is the name of the process? AB, BC and CA. What is the name of the process? But we didn't, we don't talk about heating over here. AB you see it is PT graph. No, compare this with PV is equals to NRT guys you see. Compare this with PV is equals to NRT. Correct. So we have graph of PNT. Here you see graph of PNT passing through origin. So it is constant volume we have here. Correct. Constant volume. So AB is isochoric. Can we say that AB is isochoric? Similarly, BC is constant temperature. So BC is isothermal and CA is constant pressure. So it is isobaric. Clear? No doubt. Isochoric, isochoric. But what is happening here you see? Pressure is increasing. Pressure is increasing. This you must remember. This is given. Pressure is increasing. B to C we have isothermal but pressure is decreasing. Right? And C to A we have isobaric. Temperature is decreasing. Isn't it? So further if we extend this pressure is increasing. Volume is constant. So temperature will also increase. Temperature will also increase here. Similarly here pressure is decreasing. Process is isothermal. So volume will increase. Volume should increase in this process. And temperature is decreasing. Pressure is constant. So volume should decrease in this process. Can we say that? Is it clear till here? No doubt. Please respond all of you. CLR you can type it. This is one thing. Now we know this PV graph at constant temperature. It goes like this. It is rectangular hyperbola. And we have done this in gaseous state also. The graph goes like this. Isn't it? Can you doubt in this? This is the PV graph we have. Constant temperature. It is it is an isothermal graph. Yes. Constant temperature. So BC process is this. But now the question is question is where we should take the point B? This is point B or this is point B? Could you answer this? Which one is the point B? Top one or the bottom one? Right? You need to hit and trial. Hit and trial you need to apply here. So suppose I am taking this point as B, right? This point as C. Then what happens you see? B to C, the process is expansion or compression. B to C, the process is expansion or compression, expansion. Expansion means volume increases. That is what the thing over here, volume increases. It means our assumption is correct. If you take it other way, just for this one, I am just trying to make you understand. Suppose I am taking B over here and C over here. So B to C is the case of compression. So volume should decrease but here the volume is increasing. It means this our assumption is wrong. Hence the order should be this. B should be here. Right? B should be here. C is here. And this is the case of expansion. No doubt. Yes, tell me. All of you clear? Right? Now the question is where we should take A? Either we should take A this side or this side? That's the question. So again you can give it a try. You can assume it this side and compare the other relationship. So for example, suppose I am assuming A is somewhere here. So what will happen? A to B is this and C to A is this. This is the graph we have. So A to B, what is happening here you see? A to B, the volume is decreasing. Correct? Constant pressure A to B, volume is decreasing. A to B, right? Here you see A to B is constant volume process but volume is not constant here. It means this assumption is wrong. Are you getting my point? If you take A this side, right? A to B should be isochoric constant volume process, right? Which is not coming out to be over here. It is volume is changing over here. That's why this our assumption is again wrong and hence we will take A somewhere here. Here we'll take A. Now what happens? A to B is this, right? A to C is this, correct? So A to B the process, the graph goes like this. A to B, B to C and C to A. Now you can cross check all the data. A to B is isochoric. You see A to B is isochoric constant volume and pressure is increasing, correct? Pressure is increasing. So constant volume, pressure increases. So temperature will also increase. That is what the point we have here. C to A, we have isochoric constant pressure, volume decreases, right? So C to A isochoric volume decreases. So this graph is correct. Did you understand this? Because constant volume we have no. Why linear? Because PV is equals to NRT. One degree equation it is. Tell me, read out. Prakul understood why this linear? All of you understood? Type in please. Yeah. Could you draw VT graph from this? Similarly you need to do. Try this. VT graph you try once. Done. Okay. So VT graph, the line which passes through origin that represents constant temperature line, sorry pressure line, isobaric process it is, right? Isobaric process is C to A. So on this line we have two points A and C. So where we should place this A and C? Should we place C over here and A over here or other way? C above A down. Okay. So we'll write C above A down. Okay. So I'm placing this A over here and C here. How do you understand this? You have to take a guess on it. Okay. You have to take a guess, just a hunch you can say. And then you need to cross check the other things which is coming out to be in line or not. Okay. If it is like fine, if it is coming out to be the other conditions is fine according to your assumption, it means your assumption is correct. Otherwise you have to take the other assumption. Okay. That is how we do this. Suppose I'm taking C over here, A over here. So C to A, C to A is what? C to A is isobaric process. Yes, it is isobaric process passing through origin and the line is this. C to A you see volume is decreasing, right? Volume is decreasing. So temperature will also decrease. So that's what the point we have here. C to A volume decreases. If you take it other way, then it is a case of expansion. Volume increases wrong. Okay. Now, should we take B this side on the top or on the bottom? This side to this side, that is what the question. Suppose if you take B over here, then A to B is the case of expansion. Right. So volume decreases. Volume decreases. You see A to B is a case of expansion. Volume increases, but temperature is constant. But A to B is constant volume process. No, A to B is isocoding. So if you consider B over here, volume won't be constant. Right. That's why this B we need to take over here. B will be somewhere here and C and B will continue. Okay. So this is the graph we have over here. This is B. A to B is this. B to C is this and C to A is this. Now we'll cross check all the data. A to B, you see constant volume, temperature increases. A to B, constant volume, isocodic temperature increases. B to C, constant temperature, volume increases. B to C isothermal, constant temperature, volume increases. So this is the correct VT graph we have from PV we have drawn or PT. So if VT is given, you can convert into PV. If PT is given, you can convert into PV like this and then you can find out the work done in this process. Any doubt in this? Yeah, we'll do one more. Just a second. One more example on this, you see. Okay. The first graph is VT. And this VT graph, you need to convert into PV and PT. The graph that is given is this. This is the graph we have. A point is this. We have A to B, B to C, and then C to A. Try this one. Done? Yeah. A to B is isothermal, correct. B to C is isobaric. Isobaric correct. C to A is isocorrect. Yeah, that's right. Keith, on that side. Okay. So if you draw the graph here, I'll just tell you like the process which is isothermal. Isothermal process is A to B, right? Isothermal process is A to B and that too compression, right? Volume is decreasing. AB is isothermal process. So volume decreases. Volume decreases here. Volume is decreasing. That means pressure increases. That's one thing. Second is B to C. BC is isobaric. Isobaric and volume increases, correct? Volume is increasing, right? Volume is increasing. Pressure is constant. Temperature is also increasing. CA is isocorrect. Isocorrect. Temperature is decreasing and temperature decreasing. Volume constant. Pressure is also decreasing here. This is the information we have with the given graph, correct? Now A to B is isothermal. So this graph will go like this. PV graph if you draw. So A to B, the graph will be like this, okay? But since it is pressure is increasing, so we must have A over here and B somewhere here so that the pressure increases like this, okay? B to C is isocorrect. So isocorrect. B to C is isobaric. So if you take C over here, so pressure won't be constant over here. So I'll take C somewhere here. I'll take C somewhere here and these two points I'll join, right? So we have C over here. So BC. B to C is isobaric, you see? Pressure constant. And C to A is isocoric. Volume constant. Pressure decreases. Pressure decreases. Volume increases. Temperature increases. This is the graph we have PV. Understood? And the PV graph, if I draw here, it goes like this. Same logic you can apply, you will get this. A is here. B is here. C is here and A is here. A, B, C, A. This is the PV graph here. All of you have got this? Any doubt in this? Understood? Yes. So graph conversion is very important. You must take care of this thing. This data, you must have to match with all the processes that you are following. Clear? Okay. So have you done reversible, irreversible process? Reversible and irreversible. So reversible, irreversible process we'll discuss. We'll take a break now because it will take a bit of time to explain that too because after the break we'll start this. Correct? So after the break, we'll start with reversible, irreversible process. We'll resume the session at 6.25. Okay? Take a break now. Yeah, guys. Take a break. Yeah.


Hello, I'm Professor Kay Wilhelm. I'm a consultation liaison psychiatrist at St Vincent's Hospital and that means that I deal with a lot of people with complex problems to do with grief, depression, suicidality. So I'm going to talk today about grief and depression from a psychiatric viewpoint. The first thing is some definitions. I'm not going to talk at length about grief, but just to acknowledge it is a natural response. It's a painful process. It can be expressed in many ways and it can affect people's physical and emotional health. When I talk to people about grief, I talk about it as being an emotional spring cleaning in that I think people bring out all the issues around the loss, the good and the bad, and hopefully throw out the bad and keep the good. That's what I encourage people to do. From a psychiatric point of view, a labelling point of view, grief can become complicated in various ways and that's one of the things we're going to talk about. So when does a normal mood state become abnormal? It can be when it is too intense, when it's too long lasting, when it seems appropriate to the recipient, the trigger and where is it different from depression? In depression, people seem to lack this capacity for spontaneous remission and that is one of the ways that it can be different to grief. So what is depression? Where is grief is something that you can work through? Depression, as I've said, can stay with you and people can lose this ability to be able to turn it off as they need to. But there are some things that I have in common, particularly times of lack of appetite and sleep, the more non-specific hallmarks of depression and in that way, I think they're similar but grief I've found, I've also found from my own experience, tends to come in waves and can be put away at other times and depression doesn't have that kind of feeling and it is much more persistent. It's also accompanied by loss and despair, feelings of blackness and a lot of what's called rumination going over and over about poor self-esteem, blaming and guilt and feeling of being slowed down and I'll get on to what all that's about. You might say well people when they're grieving also feel they have self-recriminations and yes it is common with grieving to say I wish I'd done more for that person or if I'd been there on that day or that sort of thing. The recriminations in depression are much more to do with the past and can bring up things that have been forgotten for decades that keep coming back so much more has this feeling of self-punishment. Just to go over what depression is though, we all have normal mood swings and that is part of life and some people have more of them than others and this can be related to their personality, their temperament and to some extent to cultures, some cultures encourage more emotional expression than others. With depression these questions about whether they feel depressed is one but whether they've lost their feeling of worthlessness, sorry whether they've lost their feeling of self-worth and become feeling worthless and feeling hopeless and much more self-critical and feel like giving up they would be hallmarks and pointers towards a clinical depression. So this is what the clinical depression looks like in psychiatric terms, in labelling terms that people have a number of symptoms and say some of the non-specific ones and some of those more specific ones and in diagnostic terms that they have a persistent change in mood that goes on for at least two weeks and the term disorder means that it's having a significant impact on their life, their functioning and or their seeking help for it. So I've mentioned that the key features are this lack of this drop in self-esteem, more self-crisis and depressed mood but not everyone expresses it as depressed mood and these rather non-specific features which can overlap with a number of other conditions and the ones I'm going to talk about that are worrisome are features to do with what I'm calling a melancholic depression and anhedonia is a loss of joy and inability to be cheered up. The ruminations which are just thoughts that just go round and round and round and relentlessly feeling hopeless and having what's called dial and mood variation where they usually in the morning feel terrible and as the day goes on feel better and then worse again the following morning and this being slowed down mentally and physically and often with cognitive changes and suicidality and in the extremes intense agitation and psychosis and that's what a melancholic looks like so it's a depression but it's got these what are called psychomotor changes and it's really important to register them. It's often the family that actually registered them so that's a melancholic depression and often people will say they can't think any longer they don't know how they managed with their life in general and the family say there is a change in in their behavior. Now there are two kinds of melancholia one is what's called a functional melancholia which occurs in younger people this has a strong genetic predisposition there's usually a family history of either depression or bipolar disorder the other group they get it though people who take stimulants I'm talking about cocaine and fetamines which in the short term make people elated but then make them feel intensely depressed and if they've got the genetic predisposition to a melancholia can go on and develop this and that is what's called a functional shutdown of these pathways which have to do with how you express emotion and tying up with memories that go along with it. Now the other group that get this melancholia are an older group and here it's not so much to do with family history but more to do with underlying physical illness generally cardiovascular disease this has been called late onset depression this is more endogenous depression is all about and it's now called vascular depression and it has an increased risk of delirium and here if you do an MRI scan the the um I'm just showing you this you see some little micro vascular infarcts along those same pathways clearly this is tied up with history of hypertension vascular disease diabetes smoking now the other important thing obviously is to think about doing a suicide risk assessment in people who've got this kind of depression and this is has got a high risk of suicide so it's important that people recognize and also that they think about depression those are some of the questions that can be asked so going back to the where this fits in with um with grief there are a number of different trajectories that can happen I'm going to go through each of these first one is that the person is grieving and they then get over the grief in what is an expected timeframe and an expected way but then they go on and develop a depressive illness and this may be because they've developed an illness it may be um the other thing is that a lot of life events can still precipitate that vascular kind of depression it could be that they've got a um they haven't been able to move on with their life even though they've grieved and they've got a sense of isolation and they're feeling rather hopeless and a bit trapped um then there are some people who develop an initial grief but it then continues and slowly morphs into a depression and other people who have been they say they've been depressed all their lives and they have more probably a history of trauma or a history of not being able to cope um what we would call a vulnerable personality style and this is just one more thing along that trajectory that they have to cope with and they do have different treatment implications so if you go with the first one and in terms of diagnostic categories you could say that this is either a new episode of depression or a complicated grief depending on how they appear in um in relationship to each other but here would be a matter of uh of dealing with the depression as it's arisen and uh at times this can be because people have developed a new illness it can be an onset of diabetes and um it's now realized that diabetes in fact a lot of it is stress related so it's it's conceivable that someone can we uh have a grief episode have to deal with that and as part of that and the stress of dealing with that that they can actually have a a reemergence or a beginning of a new physical illness which in turn can lead to depression and I'm talking about things like an autoimmune disease or a same diabetes or um also if the older it could be that they're developing a cognitive changes due to dementia now all of these can present as depression and so it's a matter of dealing with the depression and then going back and seeing if the grief has been thoroughly dealt with or new issues have emerged as part of that I guess one of the issues might be if the person has developed this sort of illness that um the person who they're grieving has had for example and that may bring up new issues the other situation is somebody has been grieving and then over time it's just not resolving and it slowly morphs into a depressive episode and that's where the real trick comes about time to work out when it's still grief and when it's become depression um when it becomes depression instead of life getting easier life is becoming harder and they're perhaps withdrawing more they maybe have started some new activities found a little bit of peace in their lives but now it's going back the other way and so asking those questions about whether they're able to be cheered up whether they're still getting joy out of their normal activities what their sleep's like and particularly if they're becoming much more slowed down and if they're ruminating and maybe bringing up um new things from the past just say on that count um our memories can play tricks on us because when you put down memories you put them down with an emotional tag so that if you have been very guilty or very sad um and you become guilty or sad again you actually retrieve old memories from the past that have got that same emotional tag which which can be um difficult and and it can sort of make sense of what can happen for some people here at some stage or other in both of those cases you may consider using an antidepressant um antidepressants I'm not advised for grief itself grief is a process that needs to be worked through and antidepressants can in fact impede the grieving process but if they are now become clinically depressed it may be um then it's worth considering giving them an antidepressant and as I say then going back and regrouping around the grieving process then there's another group of people who say they've been depressed all of their lives this generally has to do with people who've had a very unhappy life so very what we call a prejudicial childhood it may be related to some trauma events in their childhood and this grief event is just one more of a whole litany of things that's happened to them um some of this is just bad luck some of it may be things um that they've brought on themselves because of perhaps using substances which have led to the making unwise decisions etc however here the grief is still obviously important but it's equally important then to go back and try and help them address some of the other issues in their life so here um it's often the case of addressing the trauma it may be addressing substance use it may be addressing other activities they've had that are rather self-defeating so that this generally leads to a longer course it's also going to be complicated if the person who has died that they're grieving uh is part of the trauma that's been induced in the past and the other terrible irony is that if people have had a complicated relationship to the person they're grieving it's it's harder for them to grieve that that person so that if they wish they were dead for example when they die that can impede their grief process and that's where you need to go back later and try and help them work through what's actually gone so what would I do as a psychiatrist if I'm dealing with people who are in that situation obviously it's important that they can understand what's going on and there are some good um materials around to help people with that now some online some um I'm sure will be addressed by other people educating them on all of this there's a technique which I find very useful called expressive writing um where people write about trauma from their past write about what's going on for them for a number of days in a row if they've had a lot of trauma it's advised they do this with uh with the knowledge of somebody else who doesn't necessarily read what they have written but knows that what they're doing and can it address issues that come up there's a whole lot of literature around that and if anyone's interested I'm happy to pass pass that on obviously um referral for specific grief counseling is important it's a matter of working out at what point that's going to be most useful and talking to the person about that it can be a really important time to help people look after themselves better and sleep is clearly important um and helping people uh have better sleep hygiene and there's no better information about that too it's not just a matter of not having caffeine but um there are some particular exercises people can do before they sleep um exposing them to morning light can help having a wind down routine doing some writing before bed using lavender oil the pillow can all help there's a lot of information now about diet and the importance of your microbiome and I encourage people to use a Mediterranean diet and look after themselves exercise is incredibly important and can also help with dealing with both grief and depression and it's a matter of finding the right exercise using exercise exposing yourself to the morning light is extremely helpful and obviously substance use and using substances can also interfere with the grieving process and cause depression and um it's enthusiastic anti-smoker most people don't realize that smoking a packet of cigarettes a day leads to four times the rate of suicidal ideation and again can impede the grieving process it also causes new onsets of depression antidepressants have their place for some people particularly if they have a clear cut clinical depression they can also help with sleep some antidepressants can help with sleep clearly they need somebody to monitor that and it's generally GP it can be a psychiatrist and to make sure that they haven't got any suicidal ideations part of that I just have to turn my lights back on again um then there's a matter of what other mental health issues there might be and some of them might come to light for the first time for example if somebody has had a very close-knit relationship with their spouse but they're actually being socially fobic or may have a low grade schizophrenia and the spouse has protected them and it now becomes apparent if that person's not around so it can be a time as part of the grieving process to perhaps start new behaviors to perhaps be able to venture forth more I'm a great enthusiast for interpersonal therapy I'm going to mention a paper on the next page there is also something called interpersonal counseling which can be used by therapists who are not used to using interpersonal therapy but one of the specific domains in interpersonal therapy is grief and it's got a very much a flavor of getting the person personally to grief but then to take up new roles which is clearly important here and it's also useful to for depression so it can be a very useful therapy here and as I said using the whole process as mentioned emotional spring cleaning as a way of promoting growth and being able to perhaps start a new life um and just to mention on the that article I've written an article that is available in a GP magazine but I think it's fairly available about using interpersonal therapy and it shows some of the domains and questions you can ask but it may be useful the other thing that I have have which didn't unfortunately come out in these slides as a series of little cards which have some techniques that people could use but I think learning to use mindfulness skills learning problem solving skills I've mentioned the expressive writing being able to uh take up new activities and to venture forth and one of the um the the phrases that I give people is no one can go back and make a brand new start but anyone can start from here and make a brand new ending but trying to use this as an opportunity to to move forward if possible and as I say it is possible to help the person deal with grief and depression I'm going to leave it there thank you very much for your time


Working as an assistant professor in computer science and engineering department at Walton Institute of Technology, Solapur. Today, we are going to discuss on buffer cache and buffer header in UNIX operating system. Learning outcomes. At the end of this lecture or session, students will understand the concepts of buffer cache and buffer header. Before going to understand the buffer cache and buffer header, we need to just overview at the architecture of our kernel. Basically, in this kernel architecture, we will have the three different levels. In the first level, it is a user level. Second one is a kernel level and third one is a hardware level. In user level, user will perform or write some programs which are going to be executed on the operating system. So, now here we have made the three levels. Now, in the first level, there are some user programs and there will be some libraries. In the kernel level, again, it is divided into the two parts, the file subsystem and process control subsystems. User can interact with this file subsystem and process control subsystem with the help of system call interface. Now, after this file subsystem will come to the buffer cache that is in between the file subsystem and the blocks. Now, this blocks is again connected to the device driver and then that device driver is connected to the hardware control. That hardware control is going to interact with the hardware level, that is the third level of the unisopering system. If you look into this architecture, first of all, user will write a program and he will execute some functions. He wants to access some resources of the hardware and kernel. At that time, he needs to execute the system calls. That system calls first will be interact with the file subsystem means here each and everything will be treated as a file in unisopering system. Now, when that kernel wants to read or write some data from the hardware or the disk, at that time, there is an important concept we will use as a buffer cache. Means before going to write any data onto the file subsystem from the hardware or disk, we need to get it into the buffer cache. And after that, again if we want to write some data onto the buffer, then again we need to use this buffer cache. Now, how we are going to use all these things, we will look into the next slides. As I explained, there will be three levels of unisopering system, user level, kernel level and hardware level. We have already seen an overview of these things. Now, file system layout, basically in the file system layout, we will have the boot block, super block, inode list and data blocks. Boot blocks. Boot blocks is nothing but the first sector contained the bootstrap code to initialize the operating system. Means from here, our operating system is going to be start. Next one is a super block. Means how many files it can store and where to find the free space. All these things will be done with the help of this super block. Inode list. The inode list is the file in the file system. Each inode may represent a file or a directory. The last one is the data blocks. The list of data blocks to carry out the information in the files means whenever we are going to save any data on the disk, at that time we need to go through these layouts. Means we will actually store the data on the blocks and that blocks is represented, that blocks will represent the information in the files. And these files will be accessed with the help of the inode. And this inode or this part of this again super block. In this way, this layout will use. Now, here will come the what is mean by a buffer. A buffer is also called a buffer memory, is a portion of a computer memory that is set aside as a temporary holding place for data. That is being sent or received from an external device such as a hard disk, keyboard or printer. A buffer in a computer system is usually located in between the two devices that have the different speeds for handling the data or used when there is a difference in timing of events. For example, central processing unit have far higher speed than the hard disk and thus the data that is to be used by the CPU is first copied from the hard disk to the buffer while the CPU is performing the other task so that it will be available for the CPU to use at high speed. That is without wasting the CPU time waiting for the data. Means here we can say to make a proper synchronization between the CPU and hard disk. This buffer will perform a very major and important role. Now we will come for the next one what is mean by the buffer cache. The kernel could read and write the directly to and from the disk for all file system access but systems response time and throughput would be poor because of the slow disk transfer. The kernel therefore attempts to minimize the frequency of the disk access by keeping a pool of internal data buffers that is called the buffer cache. Means what? In this buffer cache our kernel will store the list recently used data. Means when user will request for some data from the hard disk directly going to visit or directly accessing the hard disk before that kernel will first look into the data into the buffer cache. If the data is available in the cache at that time directly it will utilize it. It means it will perform the fastest operations with the help of this buffer. Now just look into this diagram in the disk will have the 1, 2, 3, 4 these are the different data blocks and in the memory will have the 1 and 2 means what the user wants to read the file block. At that time that kernel first bring that block into the memory and again when user wants to write some data on the file block at that time again we need to bring that block into the memory and we will need to perform some operations. We need to perform some write operations on that block and again it will copy back into the disk. This will happen in the buffer cache. Now we will go for the buffer header. Each buffer header is a data structure just like the inode which is used to store the information for the physical buffer it represents. Now just we look into the buffer header. Now in this buffer header we will have the device number, block number, status, pointer to the data area, pointer to the previous buffer on a hash queue, pointer to the next buffer on the hash queue, pointer to the previous buffer on the free list, pointer to the next buffer on the free list means these are the different attributes the buffer header is going to be stored. Now here basically the device number is nothing but the data and block is nothing but the buffer block. Now we will look into the here. The device number field and the block number field that specify the file system and the block number of the data on the disk and uniquely identify the buffer. Basically the status of the buffer is combination of the following conditions. The buffer is currently locked means the term locked and busy will be used interchangeably as will free and unlocked means the buffer is currently locked or unlocked free or unlocked busy we can identify with the help of the status and again the buffer contains the valid data. This status will indicate whether the buffer is going to store the valid data or not. The kernel must write the buffer content to the disk before reassigning the buffer. This condition is known as the delayed write. The kernel is currently reading or writing the contents of the buffer to the disk. That will indicate the status and the last one is a process is currently waiting for the buffer to become free. So now these are the different status of the buffer headers. Now again the buffer header also contains the two set of pointers that we have already elaborated in the previous slides. This pointer is used by the buffer allocation and some algorithm to maintain the overall structure of the buffer pool. We will explain these things into the next videos. Now think and write is buffer cache will affect on the overall performance of the CPU. Can buffer is an important thing which affect on the performance of the CPU while reading or writing in the data on to the disk here. Yes, buffer is usually located between the two devices that have different speeds for handling the data are used when there is a difference in the timing of events. With the help of buffer the system will performs the proper synchronization of process means what? When any process wants to access some data from the disk at that time what it will do it will first of all execute the read system call it means it will give the details which data block is going to be access and now after that it will send the request to the kernel then what kernel will do? The kernel will go to the buffer block and check whether that data is available in the buffer. If the data is available in the buffer at that time it will just read the data and give the response back to the user and now if the data is not available in the buffer at that time what you need to do? You need to access the data block on the disk and again you need to read that data again come back to the buffer cache make the entry of that data block into the data cache and give that data block to the process. Now this is the things means what? If the data is available in the buffer at that time it will stop going forward it means stop accessing the disk. It means directly process will execute the system call look into the data into the cache if data is available then directly give you the response to the process and it will start its execution. So in that way it will improve the performance so that is why buffer is a very important task important part of the architecture. Now references we got this data from the design of Unix operating system by Moorish batch and we have referred some websites like slideshares.com and all.


This figure comes from a U.S. government from the Environmental Protection Agency, EPA, and it's based on just a fascinating study that was published in 2011 that takes into account the changes in temperature evaporation. It takes into account changes in rainfall that are expected if we keep emitting a lot of CO2 when we look out late in the century. What you see is low risk of drought as expected, so something like over here in places up near the pole, for example, where not a huge number of people live at this time. But what you'll notice is the high risk of drought in very big areas where actually a whole lot of people live now. And so this is one of those plots that is maybe a little bit worrisome if you look out to the future and we don't decide to change our behavior because there is projections that we make drought more likely in a whole lot of places where a whole lot of people now live.


What's up everybody, Jason here for JasperCaseBrace.com. 2022 Leaf Decadence Multi-Sport One Box Break round of number block number six sold out. Again, last box of the case, three autographs only guys, three hits, a big hit or miss, but a very, very nice product here guys. So again, this is round of number block stuff, of course. Everybody knows how it works. You get a round of number from zero through nine. We go by the first number, the last, so the serial number dash. And let's see what we get here guys. Everything number to 10 or less. Here's the dice roll, here's the customer names, here's the numbers, zero, one, two, three, four, five, six, seven, eight, nine. Dice roll, it's four and a five, nine times. Here we go. One, two, three, four, five, six, seven, eight, nine. Boom, nine times, four, five, nine. Thomas last but not most of the top down a nester. Now let's go nine times here. One, two, three, four, five, six, seven, eight, nine. Spot three at the top, down to zero. Boom, nine times, nine times. All right, let's see how it played out. So Thomas at three, Michael at two, C.O. with four, Kurt with seven, Matt with nine, Steve Locke with one and five, Michael with six, C.O. with eight, and then Nestor with zero. So I'm not gonna give you usually trade numbers, so just give it like 30 seconds, but close it right now probably. Start the break. Okay folks, here we go. All right, we'll go from right to left. Here we go. First one, K.D.B. Nice one there. Oh, folks came out. Two of 10, two. Spot two is Michael L. Poetry in motion, Penny Hardaway. Two of three, another one for spot two, going to Michael L. Man, back to back hits for you buddy, jeez. Can he go for the sweep? Should be the multi-signed one. Looks like it's threes. The epic three. Wow, look at that. How about an Allen Iverson, Stephen Curry, and a Damien Lillard, which I believe bronze is out of 10, so everybody should have a chance at this. Three out of 10, last spot mojo going to Thomas Hall. And there you go, man, putting me to work. Get rewarded. Spot three, last spot mojo buddy, congratulations. Got the Iverson Triple with Curry and Dame Dala Dane. Very nice. Just like that. Triple auto, very nice solid case and all three boxes honestly. So I appreciate you guys, no more decadence for now, but hopefully we get some more soon again. JasperysCaseBricks.com.