Use of Enzymes for Clinical Diagnosis

Use of Enzymes for Clinical Diagnosis Clinical enzymology is branch off medical science deals with the usage of enzymes for diagnosis prognosis of various diseases. In general, each enzyme of clinical significance is found in many tissues of the body, and in healthy individuals, these enzyme exhibit very low levels in serum. In certain disease states or with cell injury, these intracellular enzymes are released into the blood and are indicative of the presence of a pathological condition. Quantification of enzyme levels in serum is useful in determining the presence of disease. Based on the individuals physical symptoms, several enzymes may be chosen for analysis to determine if a pattern develops that aids in identifying the tissue source of the enzyme elevation in the serum(2). The understanding of enzyme kinetics allows for laboratory measurement of plasma levels. Damaged or dying cells within organ can release enzymes into the circulation, these plasma enzyme levels can be used to develop a differential diagnosis of a patient with respect to specific organ disease and dysfunction(1). Like others analyte use for clinical chemistry analysis, specific pre-analytical influences have to be taken into consideration. Analysis of enzyme measurement would involve the process from the start to the end that comprises the pre-analytical factors, analytical and post analytical factors. Pre- analytical issues in the enzyme measurement include the types of specimens, the specific anticoagulants and preservative in the tubes and the specimen collection procedure. Table 2.0 describe the type of enzymes, the specimen of choice and the pre-analytical factors that can affect the enzyme measurement. Slight hemolysis can be accepted as there is no CK ain rbc, however severe or moderate hemolysis can cause enzymes and intermediates (adenylate kinase,ATP,glucose 6-phosphatea) liberated from the erytrocytes and may affect the lag phase and the side reactions occurring in the assay system(3) Lactate Dehydrogenase LDH Serum or heparanised plasma Plasma containing anticoagulant especially oxalate, should not be used. Haemolysed specimen 150 times LDH in rbc than serum(3) Alkaline Phosphatare ALP Serum or haparinized plasma ALP-, free hemolysis. Complexing anticoagulants such as citrate,oxalate, and edta must be avoided. Storage and doing test later than 4 hours can cause loss of activity EDTA concentration in the sample-reagent mixture, causing chelation of metallic cations, and this can affect the activity of the alkaline phosphatase Gamma Glutamyl Transferase GGT Serum free from hemolysis preferred. EDTA -plasma ( up to 1 mg/mL blood) can be used Heparin produces turbidity in the reaction mixture; citrate, oxalate and fluoride depress activity by 10 15 % The rate of disappearance of substrate or the rate of appearance of product had been utilized for enzyme measurement. Usually, measuring small increase in product it is much easier than to measure small decrease in a large amount of substrate. In some enzyme measurements, neither the product not the substrate of a chemical reaction can be measured conveniently. In such cases the enzymatic reaction can be coupled to another reaction that uses the product of the enzyme catalyzed reaction to produce an indicator substance (1). The rate of change in concentration of substrate or product is the principle of kinetic method for most of the enzyme measurement. The accuracy of Kinetic makes it easier to detect changes in reaction conditions and samples requiring dilution. In a kinetic reaction, the rate of reaction can be expressed as ΔP/ΔT, the change in amount of per unit time. The amount of enzyme in a sample is measured by the rate of reaction  catalyzed by the enzyme. This rate is directly proportioned to the amount of enzyme and is expressed in enzyme unit, IU/L (4). Substrate depletion phase is a period during an enzyme assay when the concentration of substrate is falling and the assay is not following zero-order kinetics(5). The amount of substrate must be present in sufficient quantity, so that the reaction rate is limited only by the amount of enzymes. In order to get optimal method of enzyme measurement, the substrate concentration is one of the important parameters. It is essential for the concentration of the substrate(s) is saturating during the measured period of the reaction(6). At saturating substrate concentrations, the reaction velocity is pseudo zero order with respect to the substrate and the velocity is proportional only to the enzyme concentration. Figure 1.0; describe the importance of substrate depletion in enzyme measurement. Enzyme activity High Moderate Low Substrate depletion Substrate depletion Lag phase Absorbance Time Figure 1.0 Enzyme activity can be calculated from a plot of absorbance versus time when monitoring an enzyme-catalysed reaction. When reagents and serum are mixed, there may initially be a period of a time when mixing and any preliminary reactions occur; this is termed the lag period. Following this phase, the reaction will proceed at zero-order kinetics (V max); at this point, the rate of appearance of product (as measured from the slope of the line, ΔA/ΔT) is directly proportional to the enzyme activity present. As the reaction proceeds and substrate is depleted, the rate of reaction will fall below V max and the plot is no longer linear. At this point, the reaction is no longer zero order with respect to substrate concentration; rate of reaction is now dependent on both amount of substrate (which is declining) and amount of enzyme present, making it difficult to calculate amount of enzyme present. (Adapted from Henrys Clinical Diagnostic and Management by Laboratory Metho ds) An organic component of enzymes is called coenzyme. Coenzymes participate in many of the enzyme analyses performed in the clinical laboratory. As the coenzyme make up a part of the active site, the role of this coenzyme in enzymatic transamination is crucial as an example the use of pyridoxal phosphate for expression of enzyme activity for aspartate aminotransferase and alanine aminotransferase measurement(7). Table 3.0 describe the enzyme, the coenzyme and the clinical relevance of the enzyme measurement for laboratory diagnosis. In conclusion, the type of assay method, sample preparation, age and storage conditions are the variables that have to be taken into consideration in the determination of enzyme activity. Other important variables in determining enzyme activity include temperature, pH, concentration of substrate, concentration of cofactors of the assay, use of other enzyme reactions as indicators, and whether the forward or backward reaction is used to measure the enzyme. All of these variables can lead to significant differences in enzyme activity between methods (1). Enzyme Co-enzyme Clinical relevance Creatinine kinase (CK) Nicotinamide adenine dinucleotide Elevations of total CK in serum are associated with cardiac disorders, such as AMI, and skeletal muscle disorder, such as muscular dystrophy. Occasionally,elevations are due to central nervous system, including seizures and cerebral vascular accidents. CK-MB values greater than 6 % of total CK are suggestive of AMI. When AMI is suspected, troponin is assayed in conjunction with CK-MB, and sometimes myoglobin is assayed. Following AMI, Ck-MB levels rise within 4-6 hrs,peak at 12-24 hours, and return to normal within 2-3 days(2). Aspartate aminotransferase pyridoxal phosphate AST is used to evaluate hepatocellular disorders (up to 100 times upper reference limit in infectious mononucleosis, and up to 4 times upper reference limit in cirrhosis), skeletal muscle disorders ( up to 8 times upper reference limit) and acute pancreatitis(8). In AMI, AST rises within 6-8 hours, peaks at 18-24 hours, and return to normal within 4-5 days. AST is not used to diagnose AMI, but awareness of the AST pattern may be useful when ruling out other disorders, including concurrent liver damage(2). Lactate dehydrogenase (LD) NAD Elevated in cardiac disorders (AMI), hepatic diseases (viral hepatitis,cirrhosis,infectious mononucleosis),skeletal muscle diseases, haemolytic and haematological disorders (acute lymphoblastic leukemia) In AMI, LD levels rise within 8-12 hours, peak at 24-48 hours, and return to normal in 7 10 days. Although LD and LD isoenzymes are not used to diagnose AMI, knowledge of their pattern may be useful when assessing concurrent liver damage(2).

Renaissance Architecture

Renaissance Architecture Between 1400 and 1600 AD classical ideas of an † age of awakening† took place in Italy and northern Europe. This period was called † The Renaissance† which means †born anew† in French. Renaissance architecture was inspired by the architecture of classic/ancient Greece and Rome. Before Gothic architecture was very asymmetrical and complex. The renaissance architecture was highly symmetrical and very proportioned.Features Of Renaissance Buildings: †¢symmetrical arrangement of windows and doors †¢use of classical columns and pilasters †¢ triangular pediments †¢square lintel †¢arches †¢domes †¢niches with sculptures Great Renaissance Architects †¢Giacomo da Vignola †¢Andrea Palladio †¢Fillipo Brunelleschi †¢Michelangelo Buonarroti Examples Of Renaissance Buildings The San Gio Rigo Maggiore in Venice is an example for an renaissance building. †¢the Redentore in Venice t he basilica in Vicenza †¢the rotunda near Vicenza †¢the Louvre in Paris The Phases Of Renaissance For more than five centuries, artists in northern Italy were exploring new Ideas during the beginning of the early 1500s, Italy saw an explosion of talent and innovation. This period is called †The High Renaissance† during the next century renaissance ideas spread through northern Europe, slowly replacing the former Gothic approaches to art and architecture.During the 1600s renaissance ideas developed into heavily ornamented baroque style. Even after the renaissance period ended architects were inspired by renaissance ideas. In the 1700s and early 1800s, fashionable architects designed stately neo classical buildings. A century later, American architects like Richard Morris hunt designed grand renaissance revival style homes that resembled villas and palaces from renaissance Italy. Benny Opoku-Arthur Langston Beckford-Uibel

Forward the Foundation Chapter 4

8 Raych looked at Hari Seldon after the two politicians had gone and fingered his mustache. It gave him satisfaction to stroke it. Here in the Streeling Sector, some men wore mustaches, but they were usually thin despicable things of uncertain color-thin despicable things, even if dark. Most men did not wear them at all and suffered with naked upper lips. Seldon didn't, for instance, and that was just as well. With his color of hair, a mustache would have been a travesty. He watched Seldon closely, waiting for him to cease being lost in thought, and then found he could wait no longer. â€Å"Dad?† he said. Seldon looked up and said, â€Å"What?† He sounded a little annoyed at having his thoughts interrupted, Raych decided. Raych said, â€Å"I don't think it was right for you to see those two guys.† â€Å"Oh? Why not?† â€Å"Well, the thin guy, whatever his name is, was the guy you made trouble for at the Field. He can't have liked it.† â€Å"But he apologized.† â€Å"He didn't mean it. But the other guy, Joranum-he can be dangerous. What if they had had weapons?† â€Å"What? Here in the University? In my office? Of course not. This isn't Billibotton. Besides, if they had tried anything, I could have handled both of them together. Easily.† â€Å"I don't know, Dad,† said Raych dubiously. â€Å"You're getting-â€Å" â€Å"Don't say it, you ungrateful monster,† said Seldon, lifting an admonishing finger. â€Å"You'll sound just like your mother and I have enough of that from her. I am not getting old-or, at least, not that old. Besides, you were with me and you're almost as skilled a Twister as I am.† Raych's nose wrinkled. â€Å"Twisting ain't much good.† (It was no use. Raych heard himself speak and knew that, even eight years out of the morass of Dahl, he still slipped into using the Dahlite accent that marked him firmly as a member of the lower class. And he was short, too, to the point where he sometimes felt stunted. But he had his mustache and no one ever patronized him twice.) He said, â€Å"What are you going to do about Joranum?† â€Å"For now, nothing.† â€Å"Well, look, Dad, I saw Joranum on TrantorVision a couple of times. I even made some holotapes of his speeches. Everyone is talking about him, so I thought I would see what he has to say. And, you know, he makes some kind of sense. I don't like him and I don't trust him, but he does make some kind of sense. He wants all sectors to have equal rights and equal opportunities-and there ain't nothing wrong with that, is there?† â€Å"Certainly not. All civilized people feel that way.† â€Å"So why don't we have that sort of stuff? Does the Emperor feel that way? Does Demerzel?† â€Å"The Emperor and the First Minister have an entire Empire to worry about. They can't concentrate all their efforts on Trantor itself. It's easy for Joranum to talk about equality. He has no responsibilities. If he were in the position to rule, he would find that his efforts would be greatly diluted by an Empire of twenty-five million planets. Not only that, but he would find himself stopped at every point by the sectors themselves. Each one wants a great deal of equality for itself-but not much equality for others. Tell me, Raych, are you of the opinion that Joranum ought to have a chance to rule, just to show what he can do?† Raych shrugged. â€Å"I don't know. I wonder. But if he had tried anything on you, I would have been at his throat before he could move two centimeters.† â€Å"Your loyalty to me, then, exceeds your concern for the Empire.† â€Å"Sure. You're my dad.† Seldon looked at Raych fondly, but behind that look he felt a trace of uncertainty. How far could Joranum's nearly hypnotic influence go? 9 Hari Seldon sat back in his chair, the vertical back giving as he did so and allowing him to assume a half-reclining position. His hands were behind his head and his eyes were unfocused. His breathing was very soft, indeed. Dors Venabili was at the other end of the room, with her viewer turned off and the microfilms back in place. She had been through a rather concentrated period of revision of her opinions on the Florina Incident in early Trantorian history and she found it rather restful to withdraw for a few moments and to speculate on what it was that Seldon was considering. It had to be psychohistory. It would probably take him the rest of his life, tracking down the byways of this semichaotic technique, and he would end with it incomplete, leaving the task to others (to Amaryl, if that young man had not also worn himself out on the matter) and breaking his heart at the need to do that. Yet it gave him a reason for living. He would live longer with the problem filling him from end to end-and that pleased her. Someday she would lose him, she knew, and she found that the thought afflicted her. It had not seemed it would at the start, when her task had been the simple one of protecting him for the sake of what he knew. When had it become a matter of personal need? How could there be so personal a need? What was there about the man that caused her to feel uneasy when he was not in her sight, even when she knew he was safe so that the deeply ingrained orders within her were not called into action? His safety was all that she had been ordered to be concerned with. How did the rest intrude itself? She had spoken of it to Demerzel long before, when the feeling had made itself unmistakable. He had regarded her gravely and said, `'You are complex, Dors, and there are no simple answers. In my life there have been several individuals whose presence made it easier for me to think, pleasanter to make my responses. I have tried to judge the ease of my responses in their presence and the unease of my responses in their final absence to see whether I was the net gainer or loser. In the process, one thing became plain. The pleasantness of their company outweighed the regret of their passing. On the whole, then, it is better to experience what you experience now than not to.† She thought: Hari will someday leave a void, and each day that someday is closer, and I must not think of it. It was to rid herself of the thought that she finally interrupted him. â€Å"What are you thinking of, Hari?† â€Å"What?† Seldon focused his eyes with an apparent effort. â€Å"Psychohistory, I assume. I imagine you've traced another blind pathway.† â€Å"Well now. That's not on my mind at all.† He laughed suddenly. â€Å"Do you want to know what I'm thinking of? Hair!† â€Å"Hair? Whose?† â€Å"Right now, yours.† He was looking at her fondly. â€Å"Is there something wrong with it? Should I dye it another color? Or perhaps, after all these years, it should go gray.† â€Å"Come! Who needs or wants gray in your hair. But it's led me to other things. Nishaya, for instance.† â€Å"Nishaya? What's that?† â€Å"It was never part of the pre-Imperial Kingdom of Trantor, so I'm not surprised you haven't heard of it. It's a world, a small one. Isolated. Unimportant. Overlooked. I only know anything at all about it because I've taken the trouble to look it up. Very few worlds out of twenty-five million can really make much of a sustained splash, but I doubt that there's another one as insignificant as Nishaya. Which is very significant, you see.† Dors shoved her reference material to one side and said, â€Å"What is this new penchant you have for paradox, which you always tell me you detest? What is this significance of insignificance?† â€Å"Oh, I don't mind paradoxes when I perpetrate them. You see, Joranum comes from Nishaya.† â€Å"Ah, it's Joranum you're concerned with.† â€Å"Yes. I've been viewing some of his speeches-at Raych's insistence. They don't make very much sense, but the total effect can be almost hypnotic. Raych is very impressed by him.† â€Å"I imagine that anyone of Dahlite origins would be, Hari. Joranum's constant call for sector equality would naturally appeal to the downtrodden heatsinkers. You remember when we were in Dahl?† â€Å"I remember it very well and of course I don't blame the lad. It just bothers me that Joranum comes from Nishaya.† Dors shrugged. â€Å"Well, Joranum has to come from somewhere and, conversely, Nishaya, like any other world, must send its people out at times, even to Trantor.† â€Å"Yes, but, as I've said, I've taken the trouble to investigate Nishaya. I've even managed to make hyperspatial contact with some minor official which cost a considerable quantity of credits that I cannot, in good conscience, charge to the department.† â€Å"And did you find anything that was worth the credits?† â€Å"I rather think so. You know, Joranum is always telling little stories to make his points, stories that are legends on his home planet of Nishaya. That serves a good purpose for him here on Trantor, since it makes him appear to be a man of the people, full of homespun philosophy. Those tales litter his speeches. They make him appear to be from a small world, to have been brought up on an isolated farm surrounded by an untamed ecology. People like it, especially Trantorians, who would rather die than be trapped somewhere in an untamed ecology but who love to dream about one just the same.† â€Å"But what of it all?† â€Å"The odd point is that not one of the stories was familiar to the person I spoke to on Nishaya.† â€Å"That's not significant, Hari. It may be a small world, but it's a world. What is current in Joranum's birth section of the world may not be current in whatever place your official came from.† â€Å"No no. Folktales, in one form or another, are usually worldwide. But aside from that, I had considerable trouble in understanding the fellow. He spoke Galactic Standard with a thick accent. I spoke to a few others on the world, just to check, and they all had the same accent.† â€Å"And what of that?† â€Å"Joranum doesn't have it. He speaks a fairly good Trantorian. It's a lot better than mine, actually. I have the Heliconian stress on the letter `r.' He doesn't. According to the records, he arrived on Trantor when he was nineteen. It is just impossible, in my opinion, to spend the first nineteen years of your life speaking that barbarous Nishayan version of Galactic Standard and then come to Trantor and lose it. However long he's been here, some trace of the accent would have remained-Look at Raych and the way he lapses into his Dahlite way of speaking on occasion.† â€Å"What do you deduce from all this?† â€Å"What I deduce-what I've been sitting here all evening, deducing like a deduction machine-is that Joranum didn't come from Nishaya at all. In fact, I think he picked Nishaya as the place to pretend to come from, simply because it is so backwoodsy, so out-of-the-way, that no one would think of checking it. He must have made a thorough computer search to find the one world least likely to allow him to be caught in a lie.† â€Å"But that's ridiculous, Hari. Why should he want to pretend to be from a world he did not come from? It would mean a great deal of falsification of records.† â€Å"And that's precisely what he has probably done. He probably has enough followers in the civil service to make that possible. Probably no one person has done as much in the way of revision and all of his followers are too fanatical to talk about it.† â€Å"But still-Why?† â€Å"Because I suspect Joranum doesn't want people to know where he really comes from.† â€Å"Why not? All worlds in the Empire are equal, both by laws and by custom.† â€Å"I don't know about that. These high-ideal theories are somehow never borne out in real life.† â€Å"Then where does he come from? Do you have any idea at all?† â€Å"Yes. Which brings us back to this matter of hair.† â€Å"What about hair?† â€Å"I sat there with Joranum, staring at him and feeling uneasy, without knowing why I was feeling uneasy. Then finally I realized that it was his hair that made me uneasy. There was something about it, a life, a gloss†¦ a perfection to it that I've never seen before. And then I knew. His hair is artificial and carefully grown on a scalp that ought to be innocent of such things.† â€Å"Ought to be?† Dors's eyes narrowed. It was clear that she suddenly understood. â€Å"Do you mean-â€Å" â€Å"Yes, I do mean. He's from the past-centered, mythology-ridden Mycogen Sector of Trantor. That's what he's been laboring to hide.† 10 Dors Venabili thought coolly about the matter. It was her only mode of thought-cool. Not for her the hot flashes of emotion. She closed her eyes to concentrate. It had been eight years since she and Hari had visited Mycogen and they hadn't been there long. There had been little to admire there except the food. The pictures arose. The harsh, puritanical, male-centered society; the emphasis on the past; the removal of all body hair, a painful process deliberately self-imposed to make themselves different so that they would â€Å"know who they were†; their legends; their memories (or fancies) of a time when they ruled the Galaxy, when their lives were prolonged, when robots existed. Dors opened her eyes and said, â€Å"Why, Hari?† â€Å"Why what, dear?† â€Å"Why should he pretend not to be from Mycogen?† She didn't think he would remember Mycogen in greater detail than she; in fact, she knew he wouldn't, but his mind was better than hers-different, certainly. Hers was a mind that only remembered and drew the obvious inferences in the fashion of a mathematic line of deduction. He had a mind that leaped unexpectedly. Seldon liked to pretend that intuition was solely the province of his assistant, Yugo Amaryl, but Dors was not fooled by that. Seldon liked to pose as the unworldly mathematician who stared at the world out of perpetually wondering eyes, but she was not fooled by that, either. â€Å"Why should he pretend not to be from Mycogen?† she repeated as he sat there, his eyes lost in an inward look that Dors always associated with his attempt to squeeze one more tiny drop of usefulness and validity out of the concepts of psycho-history. Seldon said finally, â€Å"It's a harsh society, a limiting society. There are always those who chafe over its manner of dictating every action and every thought. There are always those who find they cannot entirely be broken to the harness, who want the greater liberties available in the more secular world outside. It's understandable.† â€Å"So they force the growth of artificial hair?† â€Å"No, not generally. The average Breakaway-that's what the Mycogenians call the deserters and they despise them, of course-wears a wig. It's much simpler but much less effective. Really serious Breakaways grow false hair, I'm told. The process is difficult and expensive but is almost unnoticeable. I've never come across it before, though I've heard of it. I've spent years studying all eight hundred sectors of Trantor, trying to work out the basic rules and mathematics of psychohistory. I have little enough to show for it, unfortunately, but I have learned a few things.† â€Å"But why, then, do the Breakaways have to hide the fact that they're from Mycogen? They're not persecuted that I know of.† â€Å"No, they're not. In fact, there's no general impression that Mycogenians are inferior. It's worse than that. The Mycogenians aren't taken seriously. They're intelligen -everyone admits that-highly educated, dignified, cultured, wizards with food, almost frightening in their capacity to keep their sector prosperous-but no one takes them seriously. Their beliefs strike people outside Mycogen as ridiculous, humorous, unbelievably foolish. And that view clings even to Mycogenians who are Breakaways. A Mycogenian attempt to seize power in the government would be crushed by laughter. Being feared is nothing. Being despised, even, can be lived with. But being laughed at-that's fatal. Joranum wants to be First Minister, so he must have hair, and, to be comfortable, he must represent himself as having been brought up on some obscure world as far from Mycogen as he can possibly manage.† â€Å"Surely there are some people who are naturally bald.† â€Å"Never as completely depilated as Mycogenians force themselves to be. On the Outer Worlds, it wouldn't matter much. But Mycogen is a distant whisper to the Outer Worlds. The Mycogenians keep themselves so much to themselves that it is a rare one, indeed, who has ever left Trantor. Here on Trantor, though, it's different. People might be bald, but they usually have a fringe of hair that advertises them as nonMycogenian-or they grow facial hair. Those very few who are completely hairless-usually a pathological condition-are out of luck. I imagine they have to go around with a doctor's certificate to prove they are not Mycogenians.† Dors, frowning slightly, said, â€Å"Does this help us any?† â€Å"I'm not sure.† â€Å"Couldn't you let it be known that he is a Mycegonian?† â€Å"I'm not sure that could be done easily. He must have covered his tracks well and even if it could be done-â€Å" â€Å"Yes?† Seldon shrugged. â€Å"I don't want to invite an appeal to bigotry. The social situation on Trantor is bad enough without running the risk of loosing passions that neither I nor anyone else could then control. If I do have to resort to the matter of Mycogen, it will only be as a last resort.† â€Å"Then you want minimalism, too.† â€Å"Of course.† â€Å"Then what will you do?† â€Å"I made an appointment with Demerzel. He may know what to do.† Dors looked at him sharply. â€Å"Hari, are you falling into the trap of expecting Demerzel to solve every problem for you?† â€Å"No, but perhaps he'll solve this one.† â€Å"And if he doesn't?† â€Å"Then I'll have to think of something else, won't I?† â€Å"Like what?† A look of pain crossed Seldon's face. â€Å"Dors, I don't know. Don't expect me to solve every problem, either.† 11 Eto Demerzel was not frequently seen, except by the Emperor Cleon. It was his policy to remain in the background for a variety of reasons, one of which was that his appearance changed so little with time. Hari Seldon had not seen him over a period of some years and had not spoken to him truly in private since the days of his early time on Trantor. In light of Seldon's recent unsettling meeting with Laskin Joranum, both Seldon and Demerzel felt it would be best not to advertise their relationship. A visit by Hari Seldon to the First Minister's office at the Imperial Palace would not go unnoticed, and so for reasons of security they had decided to meet in a small yet luxuriously appointed suite at the Dome's Edge Hotel, just outside the Palace grounds. Seeing Demerzel now brought back the old days achingly. The mere fact that Demerzel still looked exactly as he always had made the ache sharper. His face still had its strong regular features. He was still tall and sturdy-looking, with the same dark hair with the hint of blond. He was not handsome, but was gravely distinguished. He looked like someone's ideal picture of what an Imperial First Minister ought to look like, not at all like any such official in history before his time ever had. It was his appearance, Seldon thought, that gave him half his power over the Emperor, and therefore over the Imperial Court, and therefore over the Empire. Demerzel advanced toward him, a gentle smile curving his lips without altering in any way the gravity of his countenance. â€Å"Hari,† he said. â€Å"It is pleasant to see you. I was half-afraid you would change your mind and cancel.† â€Å"I was more than half-afraid you would, First Minister.† â€Å"Eto-if you fear using my real name.† â€Å"I couldn't. It won't come out of me. You know that.† â€Å"It will to me. Say it. I would rather like to hear it.† Seldon hesitated, as though he couldn't believe his lips could frame the words or his vocal cords sound them. â€Å"Daneel,† he said at length. â€Å"R. Daneel Olivaw,† said Demerzel. â€Å"Yes. You will dine with me, Hari. If I dine with you, I won't have to eat, which will be a relief.† â€Å"Gladly, though one-way eating is not my idea of a convivial time. Surely a bite or two-â€Å" â€Å"To please you-â€Å" â€Å"Just the same,† said Seldon, â€Å"I can't help but wonder if it is wise to spend too much time together.† â€Å"It is. Imperial orders. His Imperial Majesty wants me to.† â€Å"Why, Daneel?† â€Å"In two more years the Decennial Convention will be meeting again. You look surprised. Have you forgotten?† â€Å"Not really. I just haven't thought about it.† â€Å"Were you not going to attend? You were a hit at the last one.† â€Å"Yes. With my psychohistory. Some hit.† â€Å"You attracted the attention of the Emperor. No other mathematician did.† â€Å"It was you who were initially attracted, not the Emperor. Then I had to flee and stay out of the Imperial notice until such time as I could assure you that I had made a start on my psychohistorical research, after which you allowed me to remain in safe obscurity.† â€Å"Being the head of a prestigious Mathematics Department is scarcely obscurity.† â€Å"Yes, it is, since it hides my psychohistory.† â€Å"Ah, the food is arriving. For a while, let's talk about other things as befits friends. How is Dors?† â€Å"Wonderful. A true wife. Hounds me to death with her worries over my safety.† â€Å"That is her job.† â€Å"So she reminds me-frequently. Seriously, Daneel, I can never be sufficiently grateful to you for bringing us together.† â€Å"Thank you, Hari, but, to be truthful, I did not foresee married happiness for either of you, especially not Dors-â€Å" â€Å"Thank you for the gift just the same, however short of the actual consequences your expectations were.† â€Å"I'm delighted, but it is a gift, you will find, that may be of dubious further consequence-as is my friendship.† To this, Seldon could make no reply and so, at a gesture from Demerzel, he turned to his meal. After a while, he nodded at the morsel of fish on his fork and said, â€Å"I don't actually recognize the organism, but this is Mycogenian cooking.† â€Å"Yes, it is. I know you are fond of it.† â€Å"It's the Mycogenians' excuse for existence. Their only excuse. But they have special meaning to you. I mustn't forget that.† â€Å"The special meaning has come to an end. Their ancestors, long, long ago, inhabited the planet of Aurora. They lived three hundred years and more and were the lords of the Fifty Worlds of the Galaxy. It was an Auroran who first designed and produced me. I don't forget that; I remember it far more accurately-and with less distortion-than their Mycogenian descendants do. But then, long, long ago, I left them. I made my choice as to what the good of humanity must be and I have followed it, as best I could, all this time.† Seldon said with sudden alarm, â€Å"Can we be overheard?† Demerzel seemed amused. â€Å"If you have only thought of that now, it is far too late. But fear not, I have taken the necessary precautions. Nor have you been seen by too many eyes when you came. Nor will you be seen by too many when you leave. And those who do see you will not be surprised. I am well known to be an amateur mathematician of great pretensions but of little ability. That is a source of amusement to those at the court who are not entirely my friends and it would not surprise anyone here that I should be concerned about laying the groundwork for the forthcoming Decennial Convention. It is about the convention that I wish to consult you.† â€Å"I don't know that I can help. There is only one thing I could possibly talk about at the convention-and I can't talk about it. If I attend at all, it will only be as part of the audience. I do not intend to present any papers.† â€Å"I understand. Still, if you would like to hear something curious, His Imperial Majesty remembers you.† â€Å"Because you have kept me in his mind, I suppose.† â€Å"No. I have not labored to do so. However, His Imperial Majesty occasionally surprises me. He is aware of the forthcoming convention and he apparently remembers your talk at the earlier one. He remains interested in the matter of psychohistory and more may come of it, I must warn you. It is not beyond the bounds of possibility that he may ask to see you. The court will surely consider it a great honor-to receive the Imperial call twice in a single lifetime.† â€Å"You're joking. What could be served by my seeing him?† â€Å"In any case, if you are called to an audience, you can scarcely refuse. How are your young protegs, Yugo and Raych?† â€Å"Surely you know. I imagine you keep a close eye on me.† â€Å"Yes, I do. On your safety but not on every aspect of your life. I am afraid my duties fill much of my time and I am not all-seeing.† â€Å"Doesn't Dors report?† â€Å"She would in a crisis. Not otherwise. She is reluctant to play the role of spy in nonessentials.† Again the small smile. Seldon grunted. â€Å"My boys are doing well. Yugo is increasingly difficult to handle. He's more of a psychohistorian than I am and I think he feels I hold him back. As for Raych, he's a lovable rascal-always was. He won me over when he was a dreadful street urchin and what's more surprising is that he won over Dors. I honestly believe, Daneel, that if Dors grew sick of me and wanted to leave me, she would stay on anyway for her love of Raych.† Demerzel nodded and Seldon continued somberly. â€Å"If Rashelle of Wye hadn't found him lovable, I would not be here today. I would have been shot down-† He stirred uneasily. â€Å"I hate to think of that, Daneel. It was such an entirely accidental and unpredictable event. How could psychohistory have helped in any way?† â€Å"Have you not told me that, at best, psychohistory can deal only in probabilities and with vast numbers, not with individuals?† â€Å"But if the individual happens to be crucial-â€Å" â€Å"I suspect you will find that no individual is ever truly crucial. Not even I-or you.† â€Å"Perhaps you're right. I find that, no matter how I work away under these assumptions, I nevertheless think of myself as crucial, in a kind of supernormal egotism that transcends all sense. And you are crucial, too, which is something I have come here to discuss with you-as frankly as possible. I must know.† â€Å"Know what?† The remains of the meal had been cleared away by a porter and the room's lighting dimmed somewhat so that the walls seemed to close in and give a feeling of great privacy. Seldon said, â€Å"Joranum.† He bit off the word, as though feeling the mention of the name alone should be sufficient. â€Å"Ah. Yes.†** â€Å"You know about him?† â€Å"Of course. How could I not know?† â€Å"Well, I want to know about him, too.† â€Å"What do you want to know?† â€Å"Come, Daneel, don't play with me. Is he dangerous?† â€Å"Of course he is dangerous. Do you have any doubt of that?† â€Å"I mean, to you? To your position as First Minister?† â€Å"That is exactly what I mean. That is how he is dangerous.† â€Å"And you allow it?† Demerzel leaned forward, placing his left elbow on the table between them. â€Å"There are things that don't wait for my permission, Hari. Let us be philosophical about it. His Imperial Majesty, Cleon, First of that Name, has now been on the throne for eighteen years and for all that time I have been his Chief of Staff and then his First Minister, having served in scarcely lesser capacities during the last years of the reign of his father. It is a long time and First Ministers rarely remain that long in power.† â€Å"You are not the ordinary First Minister, Daneel, and you know it. You must remain in power while psychohistory is being developed. Don't smile at me. It's true. When we first met, eight years ago, you told me the Empire was in a state of decay and decline. Have you changed your mind about that?† â€Å"No, of course not.† â€Å"In fact, the decline is more marked now, isn't it?† â€Å"Yes, it is, though I labor to prevent that.† â€Å"And without you, what would happen? Joranum is raising the Empire against you.† â€Å"Trantor, Hari. Trantor. The Outer Worlds are solid and reasonably contented with my deeds so far, even in the midst of a declining economy and lessening trade.† â€Å"But Trantor is where it counts. Trantor-the Imperial world we're living on, the capital of the Empire, the core, the administrative center- is what can overthrow you. You cannot keep your post if Trantor says no. â€Å"I agree.† â€Å"And if you go, who will then take care of the Outer Worlds and what will keep the decline from being precipitate and the Empire from degenerating rapidly into anarchy?† â€Å"That is a possibility, certainly.† â€Å"So you must be doing something about it. Yugo is convinced that you are in deadly danger and can't maintain your position. His intuition tells him so. Dors says the same thing and explains it in terms of the Three Laws or Four of-of-â€Å" â€Å"Robotics,† put in Demerzel. â€Å"Young Raych seems attracted to Joranum's doctrines-being of Dahlite origin, you see. And I-I am uncertain, so I come to you for comfort, I suppose. Tell me that you have the situation well in hand.† â€Å"I would do so if I could. However, I have no comfort to offer. I am in danger.† â€Å"Are you doing nothing?† â€Å"No. I'm doing a great deal to contain discontent and blunt Joranum's message. If I had not done so, then perhaps I would be out of office already. But what I'm doing is not enough.† Seldon hesitated. Finally he said, â€Å"I believe that Joranum is actually a Mycogenian.† â€Å"Is that so?† â€Å"It is my opinion. I had thought we might use that against him, but I hesitate to unleash the forces of bigotry.† â€Å"You are wise to hesitate. There are many things that might be done that have side effects we do not want. You see, Hari, I don't fear leaving my post-if some successor could be found who would continue those principles that I have been using to keep the decline as slow as possible. On the other hand, if Joranum himself were to succeed me, then that, in my opinion, would be fatal.† â€Å"Then anything we can do to stop him would be suitable.† â€Å"Not entirely. The Empire can grow anarchic, even if Joranum is destroyed and I stay. I must not, then, do something that will destroy Joranum and allow me to stay-if that very deed promotes the Fall of the Empire. I have not yet been able to think of anything I might do that would surely destroy Joranum and just as surely avoid anarchy.† â€Å"Minimalism,† whispered Seldon. â€Å"Pardon me?† â€Å"Dors explained that you would be bound by minimalism.† â€Å"And so I am.† â€Å"Then my visit with you is a failure, Daneel.† â€Å"You mean that you came for comfort and didn't get it.† â€Å"I'm afraid so.† â€Å"But I saw you because I sought comfort as well.† â€Å"From me?† â€Å"From psychohistory, which should envision the route to safety that I cannot.† Seldon sighed heavily. â€Å"Daneel, psychohistory has not yet been developed to that point.† The First Minister looked at him gravely. â€Å"You've had eight years, Hari.† â€Å"It might be eight or eight hundred and it might not be developed to that point. It is an intractable problem.† Demerzel said, â€Å"I do not expect the technique to have been perfected, but you may have some sketch, some skeleton, some principle that you can use as guidance. Imperfectly, perhaps, but better than mere guesswork.† â€Å"No more than I had eight years ago,† said Seldon mournfully. â€Å"Here's what it amounts to, then. You must remain in power and Joranum must be destroyed in such a way that Imperial stability is maintained as long as possible so that I may have a reasonable chance to work out psychohistory. This cannot be done, however, unless I work out psychohistory first. Is that it?† â€Å"It would seem so, Hari.† â€Å"Then we argue in a useless circle and the Empire is destroyed.† â€Å"Unless something unforeseen happens. Unless you make something unforeseen happen.† â€Å"I? Daneel, how can I do it without psychohistory?† â€Å"I don't know, Hari.† And Seldon rose to go-in despair.

What Is a Schema in Psychology Definition and Examples

A schema is a cognitive structure that serves as a framework for one’s knowledge about people, places, objects, and events. Schemas help people organize their knowledge of the world and understand new information. While these mental shortcuts are useful in helping us make sense of the large amount of information we encounter on a daily basis, they can also narrow our thinking and result in stereotypes. Key Takeaways: Schema A schema is a mental representation that enables us to organize our knowledge into categories.Our schemas help us simplify our interactions with the world. They are mental shortcuts that can both help us and hurt us. We use our schemas to learn and think more quickly. However, some of our schemas may also be stereotypes that cause us to misinterpret or incorrectly recall information.There are many types of schemas, including object, person, social, event, role, and self schemas.Schemas are modified as we gain more information. This process can occur through assimilation or accommodation. Schema: Definition and Origins The term schema was first introduced in 1923 by developmental psychologist Jean Piaget. Piaget proposed a stage theory of cognitive development that utilized schemas as one of its key components. Piaget defined schemas as basic units of knowledge that related to  all aspects of the world. He suggested that different schemas are mentally applied in appropriate situations to help people both comprehend and interpret information. To Piaget, cognitive development hinges on an individual acquiring more schemas and increasing the nuance and complexity of existing schemas. The concept of schema was later described by psychologist Frederic Bartlett in 1932. Bartlett conducted experiments that tested how schemas factored into people’s memory of events. He said that people organize concepts into mental constructs he dubbed schemas. He suggested that schemas help people process and remember information. So when an individual is confronted with information that fits their existing schema, they will interpret it based on that cognitive framework. However, information that doesn’t fit into an existing schema will be forgotten. Examples of Schemas For example, when a child is young, they may develop a schema for a dog. They know a dog walks on four legs, is hairy, and has a tail. When the child goes to the zoo for the first time and sees a tiger, they may initially think the tiger is a dog as well. From the child’s perspective, the tiger fits their schema for a dog. The child’s parents may explain that this is a tiger, a wild animal. It is not a dog because it doesn’t bark, it doesn’t live in peoples houses, and it hunts for its food. After learning the differences between a tiger and a dog, the child will modify their existing dog schema and create a new tiger schema. As the child grows older and learns more about animals, they will develop more animal schemas. At the same time, their existing schemas for animals like dogs, birds, and cats will be modified to accommodate any new information they learn about animals. This is a process that continues into adulthood for all kinds of knowledge. Types of Schemas There are many kinds of schemas that assist us in understanding the world around us, the people we interact with, and even ourselves. Types of schemas include: Object schemas, which help us understand and interpret inanimate objects, including what different objects are and how they work. For example, we have a schema for what a door is and how to use it. Our door schema may also include subcategories like sliding doors, screen doors, and revolving doors.Person schemas, which are created to help us understand specific people. For instance, one’s schema for their significant other will include the way the individual looks, the way they act, what they like and don’t like, and their personality traits.Social schemas, which help us understand how to behave in different social situations. For example, if an individual plans to see a movie, their movie schema provides them with a general understanding of the type of social situation to expect when they go to the movie theater.Event schemas, also called scripts, which encompass the sequence of actions and behaviors one expects during a given event. For example, when an individual goe s to see a movie, they anticipate going to the theater, buying their ticket, selecting a seat, silencing their mobile phone, watching the movie, and then exiting the theater.Self-schemas, which help us understand ourselves. They focus on what we know about who we are now, who we were in the past, and who we could be in the future.Role schemas, which encompass our expectations of how a person in a specific social role will behave. For example, we expect a waiter to be warm and welcoming. While not all waiters will act that way, our schema sets our expectations of each waiter we interact with. Modification of Schema As our example of the child changing their dog schema after encountering a tiger illustrates, schemas can be modified. Piaget suggested that we grow intellectually by adjusting our schemas when new information comes from the world around us. Schemas can be adjusted through: Assimilation, the process of applying the schemas we already possess to understand something new.Accommodation, the process of changing an existing schema or creating a new one because new information doesn’t fit the schemas one already has. Impact on Learning and Memory Schemas help us interact with the world efficiently. They help us categorize incoming information so we can learn and think more quickly. As a result, if we encounter new information that fits an existing schema, we can efficiently understand and interpret it with minimal cognitive effort. However, schemas can also impact what we pay attention to and how we interpret new information. New information that fits an existing schema is more likely to attract an individual’s attention. In fact, people will occasionally change or distort new information so it will more comfortably fit into their existing schemas. In addition, our schemas impact what we remember. Scholars William F. Brewer and James C. Treyens demonstrated this in a 1981 study. They individually brought 30 participants into a room and told them that the space was the office of the principal investigator. They waited in the office and after 35 seconds were taken to a different room. There, they were instructed to list everything they remembered about the room they had just been waiting in. Participants’ recall of the room was much better for objects that fit into their schema of an office, but they were less successful at remembering objects that didn’t fit their schema. For example, most participants remembered that the office had a desk and a chair, but only eight recalled the skull or bulletin board in the room. In addition, nine participants claimed that they saw books in the office when in reality there weren’t any there. How Our Schemas Get Us Into Trouble The study by Brewer and Trevens demonstrates that we notice and remember things that fit into our schemas but overlook and forget things that don’t. In addition, when we recall a memory that activates a certain schema, we may adjust that memory to better fit that schema. So while schemas can help us efficiently learn and understand new information, at times they may also derail that process. For instance, schemas can lead to prejudice. Some of our schemas will be stereotypes, generalized ideas about whole groups of people. Whenever we encounter an individual from a certain group that we have a stereotype about, we will expect their behavior to fit into our schema. This can cause us to misinterpret the actions and intentions of others. For example, we may believe anyone who is elderly is mentally compromised. If we meet an older individual who is sharp and perceptive and engage in an intellectually stimulating conversation with them, that would challenge our stereotype. However, instead of changing our schema, we might simply believe the individual was having a good day. Or we might recall the one time during our conversation that the individual seemed to have trouble remembering a fact and forget about the rest of the discussion when they were able to recall information perfectly. Our dependence on our schemas to simplify our interactions with the world may cause us to maintain incorrect and damaging stereotypes. Sources Brewer, William F., and James C. Treyens. Role of Schemata in Memory for Places. Cognitive Psychology, vol. 13, no. 2, 1981, pp. 207-230. https://doi.org/10.1016/0010-0285(81)90008-6Carlston, Don. â€Å"Social Cognition.† Advanced Social Psychology: The State of the Science, edited by Roy F. Baumeister and Eli J. Finkel, Oxford University Press, 2010, pp. 63-99Cherry, Kendra. The Role of a Schema in Psychology. VeryWell Mind, 26 June 2019. https://www.verywellmind.com/what-is-a-schema-2795873McLeod, Saul. â€Å"Jean Piagets Theory of Cognitive Development.†Ã‚  Simply Psychology, 6 June 2018.  https://www.simplypsychology.org/piaget.htmlSchemas and Memory. Psychologist World. https://www.psychologistworld.com/memory/schema-memory