An Introduction To Logic Gates Essay

An Introduction To Logic Gates Essay Logic circuit is one that behaves like a switch, i.e. a two-positive devise with ON or OFF states. This is termed as binary device, in which the ON state is represented by 1 and the OFF state by 0. We require devising a logic statement which can be expressed in only one of two forms. For instance As you may know, computers store information in gigabytes, megabytes, and so on. The fundamental unit of storage is the bit or binary digit, which is similar to a switch. Like a switch, which has two states on or off, the bit has two states 1 and 0 (sometimes represented as true and false. We use this abstraction to represent numbers with the binary number system. In order to perform calculations, the computer manipulates bits by means of logical operations, which use inputs to yield a particular output based on the input bits states. To explicitly define the logic, we use truth tables which express the outputs in terms of all combinations of inputs. Examples of truth tables for logical operations are given below: Logical AND (i.e. A.B=C) Logical OR (i.e. A+B=C) Logical NOT (i.e. A) A useful way of representing these logical operations is by means of logic gates, which are pictorial representations of the logic. The most basic logic gates, which illustrate the Boolean logic of the above truth tables, are AND logic gate C=A.B OR logic gate C=A+B NOT logic gate B=A Using the logic gates above, we can create schematics of more complicated circuits. These combinational logic circuits involve feeding the output of one gate to the input of another gate. This allows us to create useful circuits that function according to our needs. Examples are provided below: F=X.Y.Z F=X+Y+Z F=X+Y.Z We probably know that calculators and computers store decimal (0-9) numbers as long strings of zeros and ones in a form called binary code. Each number is stored using microscopic electronic switches called transistors. Its easy to store binary numbers simply by switching transistors on and off. Switching on a transistor stores a number one; switching it off stores a zero. So storing numbers is easy. But how can you add, subtract, multiply, and divide using nothing but electric currents? Calculators and computers do these using clever electronic circuits called logic gates. Fig:1.1 Photo: A gate can keep we out or let we into a field. In the same way, a microscopic logic gate is a barrier in an electronic circuit that can let electricity through or stop it flowing altogether. Put lots of logic gates together and you make a machine thats capable of basic mathematical reasoning. TYPES OF LOGIC GATES: Logic gates: circuits that compare A logic gate might sound horribly complex, but its simply an electric circuit with two inputs and an output. It receives two incoming electric currents, compares them, and sends on a new, outgoing electric current depending on what it finds. A logic gate is a bit like a doorman or bouncer who is allowed to let people into a nightclub only if they pass certain tests. There are quite a few different types of logic gate, the most common of which are called AND, OR, NOT, XOR (Exclusive Or), NAND (NOT AND), and NOR (NOT OR). Lets look at the three simpler ones, AND, OR, and NOT: AND Suppose we went to a nightclub where the doormans job is to enforce a simple rule: Everyone in our group must wear a tie to come in. We went along with a friend one night. If were both wearing ties, youll get in. If only one of we is wearing a tie, or if neither of us is, neither of you will get in. An AND logic gate works the same way with two electrical inputs. If both inputs are switched on (that is, carry a number 1), the output will be 1 as well. Otherwise the output will be 0. In electronics, we can represent an AND gate with this little symbol. Three ways in which the gate can work are shown below. OR Were not wearing a tie, so you go to another club further down the street. Here, the person on the door is enforcing a different rule: A group of people can come in if any one of them is a member. If either we or our friend is a member, or if you both are members, we can both come in. If neither of we is a member, youre both left out in the cold. An OR logic gate works this way with two electrical inputs. If either input is switched on (that is, carries a number 1), the output will be 1 as well. Otherwise the output will be 0. In electronics, we represent an OR gate with a different symbol. Three ways in which it can work are shown beneath: NOT So far, weve failed to get into either of the clubs. But theres one last hope: you know a friend is having a party a few streets away. The only trouble is, theres a really argumentative and contrary person on the door. He talks to each person in turn as they approach him. If youre nice and polite, he shouts abuse at you and turns you away. But if youre rude to him, he likes that for some reason and lets you in. In other words, he does exactly the opposite of what youd expect! In electronics, theres a logic gate that works in the same, contrary way and its called a NOT gate or invertor. Unlike AND and OR gates, it has only one input and one output. The output is exactly the opposite of the input, so if the input is a 0, the output is a 1 and vice versa. Heres how we represent a NOT in electronics. Two ways it can work are shown beneath. The other three common logic gates are variations on these three. XOR (Exclusive OR) is like an OR, but it switches off if both the inputs are switched on. NAND is just like AND, only the end result is swapped over (so where AND produces an output of 1, NAND produces an output of 0). NOR is like OR with the end result swapped over in the same way. Calculators can do all the things they need to do using different combinations of logic gates. Its logic gates that control how the display works in a calculator and more logic gates that figure out the results of calculations. Lets take a closer look NAND gate This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate. The outputs of all NAND gates are high i any of the inputs are low. The symbol is an AND gate with a small circle on the output. The small circle represents inversion.   NOR gate This is a NOT-OR gate which is equal to an OR gate followed by a NOT gate. The outputs of all NOR gates are low if any of the inputs are high. The symbol is an OR gate with a small circle on the output. The small circle represents inversion.   EXOR gate The Exclusive-OR gate is a circuit which will give a high output if either, but not both, of its two inputs are high. An encircled plus sign () is used to show the EOR operation. EXNOR gate The Exclusive-NOR gate circuit does the opposite to the EOR gate. It will give a low output if either, but not both, of its two inputs are high. The symbol is an EXOR gate with a small circle on the output. The small circle represents inversion. The NAND and NOR gates are called universal functions since with either one the AND and OR functions and NOT can be generated. Note: A function in sum of products form can be implemented using NAND gates by replacing all AND and OR gates by NAND gates. A function in product of sums form can be implemented using NOR gates by replacing all AND and OR gates by NOR gates. IMPLEMENTATION OF LOGIC GATES FIG: 1.2 130 ELECTRONIC CALCULATOR   The Friden 130 uses diode-resistor OR and AND logic gates, with transistor-based inverter, buffer, and flip-flop devices. It performs math operations in bit-serial form, using the magnetostrictive delay line as the medium for storing its working registers. Logic levels are 0 Volts representing logic 1, and -12 Volts (nominally) representing logic 0. The delay line input transducer is driven with a pulse of approximately 20V, and by the time the signal makes it to the other end of the delay line, the voltage induced in the transducer is approximately 35mV, or 35/1000ths of a volt. Digits are stored within the delay line as a series of pulses arranged in groups for each digit. Zero pulses represent a zero, and nine pulses represent a nine, with the numbers in-between represented by a number of pulses matching the number. As the pulses exit the delay line, they are amplified and fed into the counters (the A and/or D counters), which count the number of pulses in the digit to form a uniq ue five-bit identifier that represents the number. The counter registers are not configured as counters in the usual binary sense. They are instead configured as five stage switch-tail shift registers, such that they count in a sequence of shifting 1s. For example; 0 is represented as 00000; 1 as 10000; 2 as 11000; 3 as 11100; 4 as 11110; 5 as 11111; with 6 as 01111, and ending with 9 as 00001. With five flip flops, each counter can represent the numbers zero through nine as unique combinations of bit patterns. In terms of applying logic gates to real world applications, many gates can be used in Figure1`.3CEP-1114 Piezo Buzzer Frequency processing. For example, when dealing with piezo audio transducers such as the CEP-1114, an oscillating frequency signal is require to produce a sound pattern from the buzzer.   Figure 3: AND gate signal output wave generator such as an oscilloscope or a programmed PIC must be logically processed with a second frequency signal to create a combination of high/low outputs which will turn the Buzzer on and off creating a sound pattern. So if you used a Square-wave signal from a PIC as one input into an AND gate and a second varying frequency as the other input, it is proven due to AND gate logic that when both signals are high the buzzer will produce a sound, and any other combination will turn the buzzer off. Furthermore, as you can see from Figure 3 on the left, the output is only high when both Input A and Input B are high. If Input B was changed or altered, this would alter the output signal sent to the buzzer. Imagine that Input B was stretched so that only one period was observed in the time give rather than two periods. This would extent the time that Input B is high and would increase the time that the output is high. Additionally, if variation of the waveform inputs is difficult or impossible, variation of the output can still be accomplished by simply changing the logic gate implemented. If the AND gate currently being used was replaced with a NAND gate, the output would be completely reversed. Every time the output was high using the AND gate will now be low, and every time the output was low will now be high. Conclusion Logic gates come in all shapes and sizes, and whether they are used in combinations or individually, they provide the user with many options and solutions to problems which may appear difficult at first. Furthermore, these seven basic logic gates ease the complexity of Boolean algebra and allow for simple application in electronics and circuit analysis. These gates can be used in almost any situation such as comparison of frequencies when developing filters in communication or in more mechanical settings when using choppers and inverters which compare input and output currents to determine modulating indexes. Figure 2: CEP-1114 Piezo Buzzer FLIP FLOPS Flip flops are actually an application of logic gates. With the help of Boolean logic you can create memory with them. This is the most basic idea of a Random Access Memory [RAM]. If the logic gates are designed correctly, they will be helpful in remembering the input value given to them. A higher application of flip flops is helpful in designing better electronic circuits. The main use of flip flops is the implementation of a feedback circuit. As a memory relies on the feedback concept, flip flops can be used to design it. Given below is a simple feedback circuit using two inverter logic gates. Take a look. Though this circuit is not good for practical electronic circuits, it will help you to get a clear idea on what a feedback circuit is. When the value of the output Q happens to be 0, it always remains 0. If the output happens to be 1, it always remains 1 There are mainly four types of flip flops that are used in electronic circuits. They are The basic flip flop or S-R Flip Flop Delay Flip Flop [D Flip Flop] J-K flip flop T flip flop 1. S-R Flip Flop The SET-RESET flip flop can be designed with the help of two NOR gates and also two NAND gates. These flip flops are also referred to as S-R Latch. S-R Flip Flop using NOR Gate The flip flop has mainly two inputs, called the SET [S] and RESET [R]. There are also two outputs, Q and Q. The diagram and truth table is shown below. S-R Flip Flop using NOR Gate From the diagram it is evident that the flip flop has mainly four states. They are S=1, R=0-Q=1, Q=0 This state is also called the SET state. S=0, R=1-Q=0, Q=1 This state is known as the RESET state. In both the states you can see that the outputs are just compliments of each other and that the value of Q follows the value of S. S=0, R=0-Q Q = Remember If both the values of S and R are switched to 0, then the circuit remembers the value of S and R in their previous state. S=1, R=1-Q=0, Q=0 [Invalid] This is an invalid state because the values of both Q and Q are 0. They are supposed to be compliments of each other. Normally, this state must be avoided. S-R Flip Flop using NAND Gate The circuit of the S-R flip flop using NAND Gate and its truth table is shown below. S-R Flip Flop using NAND Gate Like the NOR Gate S-R flip flop, this one also has four states. They are S=1, R=0-Q=0, Q=1 This state is also called the SET state. S=0, R=1-Q=1, Q=0 This state is known as the RESET state. In both the states you can see that the outputs are just compliments of each other and that the value of Q follows the compliment value of S. S=0, R=0-Q=1, Q =1 [Invalid] If both the values of S and R are switched to 0 it is an invalid state because the values of both Q and Q are 1. They are supposed to be compliments of each other. Normally, this state must be avoided. S=1, R=1-Q Q= Remember If both the values of S and R are switched to 1, then the circuit remembers the value of S and R in their previous state. Clocked S-R Flip Flop It is also called a Gated S-R flip flop. The invalid state can only be removed by using a bistable SR flip-flop that can change outputs when certain invalid states are met regardless of the condition of either the Set or the Reset inputs. For this, a clocked S-R flip flop is designed by adding two AND gates to a basic NOR Gate flip flop. The circuit diagram and truth table is shown below. Clocked S-R Flip Flop A clock pulse [CP] is given to the inputs of the AND Gate. In the beginning the outputs of both the AND Gates remain 0 until the value of CP is 0. When a pulse is given the value of CP turns 1. This makes the values at S and R to pass through the NOR Gate flip flop. But when both the S and R values turn 1, the HIGH value of CP causes both of them to turn to 0 for a short moment. As soon as the pulse is removed, the flip flop state becomes intermediate. Thus either of the two states may be caused, and it depends on whether the set or reset input of the flip-flop remains a 1 longer than the transition to 0 at the end of the pulse. Thus the invalid states can be eliminated. 2. D Flip Flop The circuit diagram and truth table is given below. D Flip Flop D flip flop is actually a slight modification of the above explained clocked SR flip-flop. From the figure you can see that the D input is connected to the S input and the complement of the D input is connected to the R input. The D input is passed on to the flip flop when the value of CP is 1. When CP is HIGH, the flip flop moves to the SET state. If it is 0, the flip flop switches to the CLEAR state. To know more about the triggering of flip flop click on the link below. TAKE A LOOK :  TRIGGERING OF FLIP FLOPS TAKE A LOOK :  MASTER-SLAVE FLIP FLOP CIRCUIT 3. J-K Flip Flop The circuit diagram and truth-table of a J-K flip flop is shown below. J-K Flip Flop A J-K flip flop can also be defined as a modification of the S-R flip flop such that it is a refinement at the indeterminate state of the SR flip flop. The inputs J and K behave just like the S and R inputs of the S-R flip flop. The letter J stands for SET and the letter K stands for CLEAR. When both the inputs J and K have a HIGH state, the flip-flop is designed to switch to its complement state. So if the value of Q was 1, it switches to Q=0 and if the value of Q was 0 it switches to Q=1. Two 3-input AND Gates are used in the circuit. The output Q of the flip flop is given as a feedback to the input of the AND along with other inputs like K and clock pulse [CP]. So, the flip flop gets a CLEAR signal when the value of CP is 1 only if the value of Q was earlier 1. Similarly output Q of the flip flop is given as a feedback to the input of the AND along with other inputs like J and clock pulse [CP]. So the output becomes SET when the value of CP is 1 only if the value of Q was earlier 1. The output may be repeated in transitions once they have been complimented for J=K=1 because of the feedback connection in the JK flip-flop. This can be avoided by setting a time duration lesser than the propagation delay through the flip-flop. The restriction on the pulse width can be eliminated with a master-slave or edge-triggered construction. 4. T Flip Flop This is a much simpler version of the J-K flip flop. Both the J and K inputs are connected together and thus are also called a single input J-K flip flop. When clock pulse is given to the flip flop, the output begins to toggle. Here also the restriction on the pulse width can be eliminated with a master-slave or edge-triggered construction. Take a look at the circuit and truth table below. T Flip Flop Conclusion Logic gates come in all shapes and sizes, and whether they are used in combinations or individually, they provide the user with many options and solutions to problems which may appear difficult at first. Furthermore, these seven basic logic gates ease the complexity of Boolean algebra and allow for simple application in electronics and circuit analysis. These gates can be used in almost any situation such as comparison of frequencies when developing filters in communication or in more mechanical settings when using choppers and inverters which compare input and output currents to determine modulating indexes

Don’t Shoot: A call for International Diplomacy Essay -- Essays Papers

Don’t Shoot: A call for International Diplomacy Worldwide terrorism became the central focus of the United States’ foreign policy following the September 11, 2001 attacks on the World Trade Center and the Pentagon. At that time, the world saw the obvious hatred that other countries hold toward the U.S. and the extreme danger that came with it. Our eyes were opened to foreign issues that many of us were not previously aware of. President Bush’s initial response to the new danger was to overtake and reform two regimes, Afghanistan and Iraq, as well as to eliminate Iraqi dictator Saddam Hussein. Instability still exists in these areas of the world, but there looms a much more immediate threat in the nuclear countries of Iran and North Korea. Said countries both possess histories of nuclear proliferation, which have recently become more threatening. Each country has violated treaties in regards to their nuclear pursuits and, presently, both countries are actively developing weapons of mass destruction. The United States has established a trend of forcefully instituting change in other countries where it sees fit, as in Afghanistan and Iraq. In the case of Iran and North Korea, such a policy is unnecessary at this time. There currently exists insufficient threat from either country to warrant an attack, so a preemptive strike would be disastrous and unnecessary. The only circumstances that necessitate physical force are those in which the United States and/or other nations are immediately and inevitably endangered. We do not possess the military or economic resources for another full-scale war front as most of our troops and funds have been exhausted in Afghanistan and Iraq (Schwenninger 17). The United States’ course of... ... 50-51. Coulter, Ann. Treason: Liberal Treachery from the Cold War to the War on Terrorism. New York: Three Rivers Press, 2003. Forbes, Steve. â€Å"Ticking Bomb.† Forbes 6 Sep. 2004: 33. Gannon, Jeff. â€Å"Iraqi Leader Challenges Western Media Bias.† Talon News 28 Sep. 2004: 25-26. Hanson, Victor Davis. â€Å"Kill the insurgents. Stop Talking.† The New Republic. 7 June 2004: 13-14. Hirsch, Michael and John Barry. â€Å"Madmen, Rogues & Nukes.† Newsweek 11 Oct. 2004: 34-35. â€Å"Japanese official says North Korea holds nuclear weapons: report.† 17 Oct. 2004: n.pag. On-line. Internet. 18 Oct. 2004. Available WWW: http://news.yahoo.com. Scoblic, J. Peter. â€Å"As I Say: Bush v. Bush on North Korea.† The New Republic 4 Oct 2004: 11-13. â€Å"Will the US now attack Tehran?† New Statesman 27 Sep. 2004: 6. Zakaria, Fareed. â€Å"A Vision, and Little Else.† Newsweek 13 Sep 2004: 37.

Effective teachers Essay

I. The Power of an Effective Teacher and Why We Should Assess It This is the value of the teacher, who looks at a face and says there’s something behind that and I want to reach that person, I want to influence that person, I want to encourage that person, I want to enrich, I want to call out that person who is behind that face, behind that colour, behind that language, behind that tradition, behind that culture. I believe you can do it. I know what was done for me. The transformative power of an effective teacher is something almost all of us have experienced and understand on a personal level. If we were particularly fortunate, we had numerous exceptional teachers who made school an exciting and interesting place. Those teachers possessed a passion for the subjects that they taught and genuine care for the students with whom they worked. They inspired us to play with ideas, think deeply about the subject matter, take on more challenging work, and even pursue careers in a particular field of study. Some exceptional teachers achieve celebrity status, such as Jaime Escalante, the math teacher who inspired the film Stand and Deliver, but thousands of unsung heroes go unrecognized in their remarkable work with students on a daily basis. ? II. Qualities of an Effective teacher Think back to when you were in school. Who was your favourite teacher? Who was the teacher you dreaded having? Almost everyone will instantly be able to answer these two questions. We’ve all had terrific teachers and, unfortunately, most of us have had teachers that were not effective. So what qualities does an effective teacher have that an ineffective teacher does not? The answer is that it takes a perfect blend of several qualities to create a truly effective teacher who can have a lasting impact on virtually every student. In this article, we examine ten qualities that virtually every effective teacher will possess. a)An effective teacher loves to teach. The single most important quality that every teacher should possess is a love and passion for teaching young people. Unfortunately, there are teachers who do not love what they do. This  single factor can destroy a teacher’s effectiveness quicker than anything else. Teachers who do not enjoy their job cannot possibly be effective day in and day out. There are too many discouraging factors associated with teaching that is difficult enough on a teacher who absolutely loves what they do, much less on one who doesn’t have the drive, passion, or enthusiasm for it. On top of that, kids are smarter than what we give them credit for. They will spot a phony quicker than anyone and thus destroy any credibility that the teacher may have. b)An effective teacher demonstrates a caring attitude. Even teachers who love their job can struggle in this area, not because they don’t care, but because they get caught up so much in the day to day routine of teaching that they can forget that their students have lives outside of school. Taking the time to get to know a student on a personal level takes a lot of time and dedication. There is also a line that no teacher wants to cross where their relationship becomes too personal. Elite teachers know how to balance this without crossing that line and once a student believes the teacher truly cares for them, then there is no limit to what that student can achieve. c)An effective teacher can relate to his or her students. The best teachers work hard to figure out how to relate to each of their students. Common interest can be hard to find, but exceptional teachers will find a way to connect with their students even if they have to fake it. For instance, you may have a student who is a Lego fanatic. You can relate to that student if you do something as simple as ordering a Lego catalogue and then going through it and discussing it with that student. Even if you have no actual interest in Lego’s, the student will think you do and thus naturally create a connection. d)An effective teacher is willing to think outside the box. There is no one set cookie cutter way to teach. A cookie cutter approach would likely be boring for both teachers and students. What makes teaching so exciting is that kids learn differently, and we have to find and utilize different strategies and differentiated learning to reach every student. What works for one student, will not work for every student. Teachers have to be willing to be creative and adaptive in their lessons, thinking outside the box on a continual basis. If you try to teach every concept in the same manner, there will be students who miss out on key factors because they aren’t wired to learn that way. e)An effective teacher is an excellent communicator. To be the best possible teacher you must be an effective communicator. However, in this area you are not just limited to being a skilled communicator to your students although that is a must. You must also be a strong communicator with parents of your students as well as your faculty/staff team within in your building. If you have a difficulty communicating with any of these three groups, then you limit your overall effectiveness as a teacher. f)An effective teacher is proactive rather than reactive. This can be one of most difficult aspects for a teacher to conquer. Intense planning and organization can ultimately make your job all the more less difficult. Teachers who plan ahead, looking for aspects that they might have issues with, and proactively looking for solutions to solve those problems will have less stress on them, than those teachers who wait until a problem arises and then tries to address it. Being proactive does not replace being adaptive. No matter how well you plan, there will be surprises. However, being proactive can cut down on these surprises tremendously, thus making you more effective overall. g)An effective teacher strives to be better. A teacher who has grown complacent in what they do is the most ineffective kind of teacher. Any teacher who is not looking for new and better teaching strategies isn’t being an effective teacher. No matter how long you have taught, you should always want to grow as a teacher. Every year there is new research, new technology, and new educational tools that could make you a better teacher. Seek out professional development opportunities and try to apply something new to your class every year. h)An effective teacher uses a variety of media in their lessons. Like it or not we are in the 21st century, and this generation of students was born in the digital age. These students have been bombarded by technological advances unlike any other generation. They have embraced it, and if we as teachers do not, then we are falling behind. This is not to say that we should eliminate textbooks and worksheets completely, but effective teachers are not afraid to implement other forms of media within their lessons. i)An effective teacher challenges their students. The most effective teachers, are often the ones that many students think are the most difficult. This is because they challenge their students and push them harder than the average teacher does. These are the teachers who are often students’ least favourite teachers at the time, but then later on in life they are the ones that we all remember and want to thank, because of how well they prepared us for life after our time with them. Being an effective teacher does not mean you are easy. It means that you challenge every one of your students and maximize your time with them so that they learn more than they ever thought they could learn. j)An effective teacher understands the content that they teach and knows how to explain that content in a manner that their students understand. There are teachers who do not know the content well enough to effectively teach it. There are teachers who are truly experts on the content, but struggle to effectively explain it to their students. The highly effective teacher both understands the content and explains it on level. This can be a difficult skill to accomplish, but the teachers who can, maximize their effectiveness as a teacher. III. Effective teaching strategies Six keys to classroom Excel a) Interest and explanation – â€Å"When our interest is aroused in something, whether it is an academic subject or a hobby, we enjoy working hard at it. We come to feel that we can in some way own it and use it to make sense of the world around us. † (p. 98). Coupled with the need to establish the relevance of content, instructors need to craft explanations that enable students to understand the material. This involves knowing what students understand and then forging connections between what is known and what is new. b) Concern and respect for students and student learning – Rams den starts with the negative about which he is assertive and unequivocal. â€Å"Truly awful teaching in higher education is most often revealed by a sheer lack of interest in and compassion for students and student learning. It repeatedly displays the classic symptom of making a subject seem more demanding than it actually is. Some people may get pleasure from this kind of masquerade. They are teaching very badly if they do. Good teaching is nothing to do with making things hard. It is nothing to do with frightening students. It is everything to do with benevolence and humility; it always tries to help students feel that a subject can be mastered; it encourages them to try things out for themselves and succeed at something quickly. † (p. 98) c) Appropriate assessment and feedback – This principle involves using a variety of assessment techniques and allowing students to demonstrate their mastery of the material in different ways. It avoids those assessment methods that encourage students to memorize and regurgitate. It recognizes the power of feedback to motivate more effort to learn. d)Clear goals and intellectual challenge – Effective teachers set high standards for students. They also articulate clear goals. Students should know up front what they will learn and what they will be expected to do with what they know. e)Independence, control and active engagement – â€Å"Good teaching fosters [a] sense of student control over learning and interest in the subject matter. † (p. 100). Good teachers create learning tasks appropriate to the student’s level of understanding. They also recognize the uniqueness of individual learners and avoid the temptation to impose â€Å"mass production† standards that treat all learners as if they were exactly the same. â€Å"It is worth stressing that we know that students who experience teaching of the kind that permits control by the learner not only learn better, but that they enjoy learning more. † (p. 102. ) f)Learning from students – â€Å"Effective teaching refuses to take its effect on students for granted. It sees the relation between teaching and learning as problematic, uncertain and relative. Good teaching is open to change: it involves constantly trying to find out what the effects of instruction are on learning, and modifying the instruction in the light of the evidence collected. † ?

Definition and Examples of Comparison in Composition

Definition and Examples of Comparison in Composition In composition, comparison is a  rhetorical strategy and method of organization in which a writer examines similarities and/or differences between two people, places, ideas, or things.Words and phrases that often signal a comparison include similarly, likewise, by comparison, by the same token, in like manner, in the same way, and in a similar fashion. Comparison (often referred to as comparison and contrast) is one of the classical rhetorical exercises known as the  progymnasmata. Comparison/Contrast Essays A Brother of St. Francis, by Grace RhysLaughter, by Joseph AddisonThe Lowest Animal, by Mark TwainLuxuries, by George AdeOf Youth and Age, by Francis BaconOn the Difference Between Wit and Humor, by Charles S. BrooksRed-Bloods and Mollycoddles, by G. Lowes DickinsonTwo Ways of Seeing a River, by Mark TwainWatching Baseball, Playing Softball, by Lubby Juggins Style Scrapbook Comparison in Laurie Lees AppetiteComparison in Sarah Vowells Place Description Etymology From the Latin, compare. Examples and Observations A car is useless in New York, essential everywhere else. The same with good manners.(Mignon McLaughlin, The Complete Neurotics Notebook. Castle Books, 1981)The truth of the matter was, the baby looked very much like a mouse in every way. He was only about two inches high; and he had a mouses sharp nose, a mouses tail, a mouses whiskers, and the pleasant, shy manner of a mouse. Before he was many days old he was not only looking like a mouse but acting like one, toowearing a gray hat and carrying a small cane.(E.B. White, Stuart Little. Harper, 1945)Must a powerful fairy like myself condescend to explain her doings to you who are no better than an ant by comparison, though you think yourself a great king?(Andrew Lang, The Wonderful Sheep. The Blue Fairy Book, 1889)Immigrants in Canada are . . . more culturally similar to the native population than immigrant groups in other nations. Canadian immigrants nationalize at very high rates. They participate in the labor force at rates similar to the native population; their unemployment is lower; their occupational prestige is similar; and their income is the same as the native population.(J.P. Lynch and R.J. Simon, Immigration the World Over. Rowman Littlefield, 2003)establish a clear basis for comparison;make a thorough and specific presentation; andprovide an effective arrangement for the material. Comparison and Contrast EssaysTo gain the most from your use of comparison and contrast, . . . you need to(W.J. Kelly, Strategy and Structure. Allyn and Bacon, 1999)Arranging Details in Comparison and Contrast EssaysOrdering detail in a comparison-contrast essay requires some thought. One possible arrangement is the block pattern whereby all the points about one subject are made (in a block) then all the points about the other subject are made (in a second block). . . .A second possible arrangement for the details of comparison-contrast is the alternating pattern, whereby a point is made for one subject, then for the other. A second point is made for the first subject, then for the other. This alternating pattern continues until all the points are made for both subjects. . . .In general, the block method works better for essays with fewer points of comparison or contrast that are not extensively developed . . ..An alternating pattern is usually a better choice for an essay with many points of comparison and contrast or an essay with extensively developed ideas.(Barbara Fine Clouse, Patterns for a Purpose. McGraw-Hill, 2003) Complaining vs. MoaningVisitors to Britain are rarely able to graspsometimes after decades of residencythe vital distinction its inhabitants make between complaining and moaning. The two activities seem similar, but there is a profound philosophical and practical difference. To complain about something is to express dissatisfaction to someone whom you hold responsible for an unsatisfactory state of affairs; to moan is to express the same thing to someone other than the person responsible. The British are powerfully embarrassed by complaining, and experience an almost physical recoil from people who do it in public. They do love to moan though. The background music of British life is a running aria of moaning about pretty much everythingour weather, our politics, our permanently under-performing national sports teams, our reality-TV-obsessed media, and so on. Moaning, a source of entertainment in its own right, is also an important psychic comfort blanket, a way of venting resentment without taking responsibility for effecting change.(John Lanchester, Party Games. The New Yorker, June 7, 2010) European Football vs. American FootballAlthough European football is the parent of American football, the two games show several major differences. European football, sometimes called association football or soccer, is played in more than 80 countries, making it the most widely played sport in the world. American football, on the other hand, is popular only in the United States and Canada. Soccer is played by 11 players with a round ball. Football, also played by 11 players in somewhat different positions on the field, uses an elongated round ball. Soccer has little body contact between players, and therefore requires no special protective equipment. Football, in which players make maximum use of body contact to block a running ball carrier and his teammates, requires special headgear and padding. In soccer, the ball is advanced toward the goal by kicking it or by butting it with the head. In football, on the other hand, the ball is passed from hand to hand across the opponents goal. These are just a few of the features that distinguish association and American football.(student paragraph, Football and Soccer) A Sexist Interlude by Bill Bryson: Women vs. Men at the Checkout CounterAlthough the store had only just opened, the food hall was busy and there were long queues at the tills. I took a place in a line behind eight other shoppers. They were all women and they all did the same mystifying thing: They acted surprised when it came time to pay. This is something that has been puzzling me for years. Women will stand there watching their items being rung up, and then when the till lady says, Thats four pounds twenty, love, or whatever, they suddenly look as if theyve never done this sort of thing before. They go Oh! and start rooting in a flustered fashion in their handbag for their purse or checkbook, as if no one had told them that this might happen.Men, for all their many shortcomings, like washing large pieces of oily machinery in the kitchen sink or forgetting that a painted door stays wet for more than thirty seconds, are generally pretty good when it comes to paying. They spend their time in line doing a wallet inventory and sorting through their coins. When the till person announces the bill, they immediately hand over an approximately correct amount of money, keep their hands extended for the change however long it takes or however foolish they may begin to look if there is, say, a problem with the till roll, and thenmark thispocket their change as they walk away instead of deciding that now is the time to search for the car keys and reorganize six months worth of receipts.(Bill Bryson, Notes From a Small Island. William Morrow, 1995 Pronunciation: kom-PAR-eh-son Also Known As: comparison and contrast

enzymes essays

enzymes essays The experiment is designed to determine whether the catalytic behavior of the enzyme is altered if the normal chemical environment is changed. The goal is to lower the concentration of lactase, so more excess enzyme is available to produce a greater amount of product for the same enzyme with the same volume in a sixty second period. The substrate o-nitrophenyl-B D-galactopyranoside (ONPG) was used. A diluted Lact-Aid solution was the enzyme. The enzyme never reached saturation point in either the control or treatment. The use of fewer enzymes decreased the absorption of the ONPG. The 1/2X takes a longer amount of time to get to the same point as the 1X. Enzymes are catalysts. Most are proteins. Enzymes bind temporarily to one or more of the reactants of the reaction they catalyze. In doing so, they lower the amount of activation energy needed and thus speed up the reaction. Lactase is an enzyme normally found in the small intestine that catalyzes the hydrolysis of the disaccharide lactose (milk sugar) to the monosaccharide galactose and glucose. The pH of the small intestine is alkaline (pH=8) and the temperature is 37C in humans. Salt concentrations on the order of 0.1 M (100 mM) are considered physiological. We worked to characterize lactase activity under optimal conditions such as are found in the small intestine. The usual means by which enzyme activity is assessed is through measurement of the rate of product formation or the rate of substrate disappearance could also be measured. The rate of lactose disappearance can not be measured by a spectronic-20, so the synthetic compound, ONPG is used as the alternative substrate. Wh en ONPG is hydrolyzed by lactase, it yields the product 0-nitropenolate and galactose. O-nitropenolate is yellow in color and absorbs at a wavelength of 420 nm, so the spectronic-20 can be used to measure its appearance. Our experiment was designed to determine whether the catalytic beha...

Geothermal Energy Research Paper Example | Topics and Well Written Essays - 3000 words

Geothermal Energy - Research Paper Example The researcher states that the heat from the Earth is called geothermal energy and have many advantages as it is renewable and does not spoil the environment. It is renewable because the heat emanating from the earth's interiors is virtually limitless. There are many countries worldwide including U.S that produce geothermal energy in a considerable amount. This paper focuses on the origin of the geothermal energy, scientific principles on which it is based and how it is being harnessed safeguarding our environment. The paper also looks into the cost of production of geothermal energy and other cost economics when compared with the energy produced from fossil fuels. According to the Pacific Northwest Electric Power Planning and Conservation Act of 1980 and the National Energy Policy Act of 1992, geothermal energy is a renewable resource. The reason being rainwater continue to feed the underground aquifers. The Earth's heat is an inexhaustible and continuous source of energy. It is an established fact, mentioned by the researcher that geothermal energy has a promising future due to its environmentally friendly nature and being a renewable type. The cost economics tilt hugely in favor of this renewable source of energy and recent advances in drilling and exploration technology will make it more lucrative in coming years. Global warming and ecological disturbances throughout the world necessitates the use of natural and clean energy resource replacing the fossil fuel based energy as much as possible.

Internet Marketing Strategy Case Study Example | Topics and Well Written Essays - 3000 words

Internet Marketing Strategy - Case Study Example LVMH thus controlled a portfolio of 50 luxury brands and is the number one worldwide seller of champagne, cognac, fashion and leather goods and number three worldwide seller of perfumes and cosmetics. The company's revenues topped $10 billion in 2000. The growth of the internet has been a challenge in marketing for traditional companies as Louis Vuitton. Since internet is an egalitarian medium of retailing, Luis Vuitton which caters for the luxury customer did not view it as a brand multiplier in the initial stages, it has gradually developed its web presence over the years. There is however adequate scope for enhancement of internet marketing and branding by Luis Vuitton. Internet marketing strategies are build around segmentation, targeting and positioning(STP). A company utilising the web site as a tool for marketing has to take STP into account. (Tanahashi: 2001). Segmentation is carried out to identify the most suitable target market and position the brand to attain competitive edge. Simultaneously the customer's needs and expectations can be easily researched on the internet. Differentation with rivals, an essential marketing parameter can also be easily accomplished. (Tanahashi : 2001). Another issue is differentiation within the market, its level of maturity and customer segmentation based on the innovator theory. The innovator theory determines that every market has different levels of customers. A miniscule 2.5 percent are said to be innovators or those who will seek a new product for its novelty. These are followed by opinion leaders or early adapters (13.5%), early majority (34%), late majority (34%), and laggards or late adapters (16%). ( Rogers : 2002). The internet provides easy tools to assess the size of each segment. Internet marketing strategy also entails facets such as key word search. Customers are homing onto products on the web by keying in product identity. Search engines facilitate location of the best or most sought after product. There is a necessity to see how key word search results can provide market visibility to the product. For brand measurement on line, it is also necessary to understand why a particular product is not bought. This implies measurement of the clients product outside the conversion rate, which is possible on the internet. Thus click through and conversion rates can be achieved through better branding.(Key Word Search Marketing : 2005). Internet Marketing is carried out by using advertising banners, pay per click advertising, e mail marketing strategies, search engine optimization articles, blog marketing and business strategy to connect with a large number of customers simultaneously without the need for physical presence. Web marketing involves focusing and indivi dualizing advertising campaigns by using superior information available to market analysts through the internet. (Internet Marketing: 2005). Speed is of essence in internet marketing and it allows new products and services to reach the user within minutes if required. The key to effective internet marketing is ensuring the basics. The fundamentals entail assessing the needs of the consumer and providing these requirements as quickly as possible. This would