Thursday, November 28, 2019

William Shakespeare an Example of the Topic Literature Essays by

William Shakespeare William Shakespeares actual birth date is not officially known, but according to records and research he was born on April 23, 1564. This date is also Saint Georges Day, a British holiday. He was born on Henley Street in Stratford Upon Avon to parents John and Mary. His father was a tanner and leather goods salesman who became somewhat wealthy. He was a successful businessman and he also held several positions in the town of Stratford including one equal to being the mayor. He later lost this job and fell into poverty before dying in 1601. Shakespeares parents had three children that died before William was born, and he had two siblings named Gilbert and Joan. Because his father was an important man in Stratford when William was young, William received a good education. He attended a grammar school at Stratford upon Avon. This is where he first studied many of the Latin and English authors that later influenced his plays. Need essay sample on "William Shakespeare" topic? We will write a custom essay sample specifically for you Proceed After leaving the school because of his fathers loss of the public service job, William married Anne Hathaway in 1582 when he was eighteen and she was twenty six. There is evidence that she was already many months pregnant when they got married. They had three children: Susanna and twins Hamnet and Judith who were named after close family friends. Shakespeare would leave his wife and children behind when he moved to London to become an actor. The years 1585-1592 are called Shakespeares lost years because not a lot is known about what he did or what happened in his life during this time frame. Around 1585 he moved to London to study acting. By 1592 he was a popular and respected actor in London. He had also started writing plays of his own by this time, including Henry II and The Comedy of Errors. Most of his plays were performed by a troupe called Pembrokes Men. Shakespeare wrote for this troupe and acted with them too. The troupe performed plays for Queen Elizabeth often. Shakespeare left theatre briefly after 1592 when an outbreak of the plague made many theatres close. He wrote sonnets and poetry until he returned to theatre around 1594. Shakespeare bought the Globe Theatre with his troupe the Chamberlains Men after he returned to acting. The Globe was an open-air theatre and got its name because it was shaped like an octagon and was round like a globe. The Globe was one of the major theatres in London at the time, along with the Rose, the Swan and the Hope. Shakespeare and his troupe continued to perform for Queen Elizabeth and her court at this theatre. The Globe Theatre would later burn down during a performance of King Henry VII. Shakespeare continued to write, act and be involved in theatre until he died in 1616. The cause of Shakespeares death is unknown to this day. The vicar of Stratfords Holy Trinity Church explained Shakespeares death in an entry in his journal by saying, Shakespeare, Drayton and Ben Jonson had a merry meeting and it seems drank too hard, for Shakespeare died of a fever there contracted. Shakespeares influence in literature has continued to the present day for many reasons. He continues to be considered one of the most famous and influential writers and poets in history because his characters still seem believable and real even though his stories are set in a time long ago. The reader is still able to relate to them because Shakespeare wrote about common human emotions and understandable events. His characters are motivated by jealousy, anger, greed, power, love and lust. Readers can always relate to a character in Shakespeares work or sympathize with what the character goes through because people still feel those kinds of emotions today and always will. Shakespeare also wrote in a language and style that were unique when he first wrote his plays and sonnets and are now considered classic. Shakespeare is said to have impacted the English language as a whole, not just literature. He did this with the language he used in his plays and the structures and languages in hi s sonnets and poetry. Most of Shakespeares sonnets were written in the 1590s and there are references in them to many people in Shakespeares life, including his wife Anne. But the first 126 sonnets Shakespeare wrote were actually addressed to a man, making some people question Shakespeares sexuality. There is no proof that Shakespeare was or wasnt gay, and people continue to debate what he meant by addressing these sonnets to a male. Many of Shakespeares tragedies were based on Greek and Roman myths or historical events, like Julius Caesar. Shakespeare also wrote histories like Richard III and King Henry VIII that focused on real historical figures and their lives. Shakespeares comedies include Much Ado About Nothing and A Midsummer Nights Dream. Many of Shakespeares comedies include comical situations involving lovers and some kind of magical element like fairies, sprites or witches. Shakespeares plays and sonnets have inspired many movies over the years. There have been many movie versions of Shakespeares plays like Romeo and Juliet and Macbeth where actors use the actual lines of the play. But there are also movies that do not follow the lines of the play but have a story based on issues addressed in the play or that mimic the plays characters. Some recent examples are the musical West Side Story, which was based on Romeo and Juliet, and the movie Ten Things I Hate About You and which was based on Taming of the Shrew. These are just two examples of films, musicals, plays and books that continue to be influenced by Shakespeares language, structure and stories. Works Cited Shakespeares Globe. Shakespeare Resource Center. 21 May 2010. May 27, http://www.bardweb.net/globe.html Shakespeares Influence on Other Writers. Shakespeare Online. 10 May 2010. May 27, 2010. http://www.shakespeare-online.com/biography/shakespearewriter.html

Monday, November 25, 2019

Electrical Conductivity of the Heart essays

Electrical Conductivity of the Heart essays Have you ever wondered just how important your heart is? Do you ever think about it to keep it beating? Well, the answer is probably no. Your heart is an amazing organ. It has the ability to function on its own. The heart is about the size of you fist lying in the middle of you chest. It is composed of numerous fibers and tissues, which allows it to operate and pump blood though out your body. The fibers allow electricity to be transmitted across the heart. The main areas that deal with the electrical impulses are the SA node, the AV node, the Bundle of His, and the purkinje fibers. Together, all these components contract the heart and pump blood through the body. The sinoatrial (SA) node, or the natural pacemaker of the heart, is where the electrical impulses are generated. It is located in the upper wall of the right atrium near the opening from the superior vena cava. The SA node sets the contraction rate by generating nerve impulses which travel through the heart wall and then both atria contract. It does not need an external stimuli for the production of the electrical impulses, it does this on its own. The normal rate for the impulses to be generated is between sixty and eighty beats per minute. This rate can increase when one is aroused, exercising, angry, or frightened and this rate can decrease when one is sleeping or hibernating. From the SA node to the next receptor in the heart, it only takes fifty milliseconds for the signal to travel. The next set of specialized tissue is the atrioventricular (AV) node. It is located in the bottom of the right atrium in the interatrial septum. When the electrical signals reach the AV node from the SA node, the signal is delayed for one-tenth of a second to allow the atria to empty their contents of blood. The AV node is slightly smaller in size than the SA node and the AV node causes both ventricles to contract. The normal rate of the AV node is between forty and...

Thursday, November 21, 2019

Analyze the issues associated with sampling, validity, reliability and Assignment

Analyze the issues associated with sampling, validity, reliability and bias for both approaches - Assignment Example zed by randomization of research participants into control and experimental groups, followed by administration of a treatment to the intervention group (Cottrell & McKenzie, 2010). Non-experimental design is however suitable for exploratory analysis and involves observations for descriptive purposes (Morra-Imas, Morra, & Rist, 2009). Reliability is one of the necessities of an experimental design and defines dependability of results for deriving conclusion. Validity, however, defines truthfulness of data (Karwowski, 2010). The first level of Bloom’s taxonomy, remembering, offers a basis for analyzing potential issues to reliability and validity in experimental designs. Inability to remember data means that wrong information can be incorporated in a study. When this happens, the data and its analysis are no longer consistent with actual observation, inducing validity concerns. In addition, reported data from some sub sets of an experimental sample will deviate from those from o ther parts, inducing internal reliability concerns. When this is significant, developed conclusion may not be consistent with population parameters, inducing external reliability concerns. Using accurate data collection and recording instruments and immediate data caption can however ensure validity and reliability based on ability to remember (Sevilla, n.d.). Reliability and validity are also significant at the experimental design’s data analysis stage in which ability to understand involved concepts in information and to apply the developed knowledge in analysis are necessary (White, 2010). The need to understand features of each data set and to identify potential relationships establishes this because failure to understand and apply the features threatens dependability and truthfulness of data. The issues further threaten ability to make inferences and to investigate causal relationships, which are the main objectives of experimental design. Sampling and bias are also incident to

Wednesday, November 20, 2019

Do the questions below. ( every questions should be more than 200 Term Paper

Do the questions below. ( every questions should be more than 200 words) - Term Paper Example However, it does not mean that labor is the most valuable practice though some historical perspectives give labor such prominence. This occurs in social structures where development of productive forces is minimal so the labor activity completely occupies the individual’s life. This highlights the need to recognize labor as the centre of the ontology of culture (Stanley and Wise 1). This is because additional aspects of human activity entirely depend on the capability of individuals to provide labor within a stipulated time. Additionally, advancement of productive forces determines the capacity of individuals coupled with the extent of complication of social needs that require labor satisfaction. Marx’s expression â€Å"changes his own nature† draws mistranslation, particularly because the word â€Å"nature† can have two interpretations. The first meaning relates to human beings as the subjects of the action; a subject performing an activity needs to alter his or her own nature in a definite way to achieve the stipulated targets. The other meaning of â€Å"nature† relates to environment and emphasizes the alterations of the world because of intentional activity (Stanley and Wise 1). Additionally, humans alter the world to launch their own social objects to change the course of the society. Q: 66. â€Å"Give everyday examples illustrating the contradiction that in everyday practical activity exchange-value is sometimes considered immanent and sometimes considered relative†. Presently, in each practical activity, exchange value may be either immanent or relative. Products attain value because they are expressed in monetary terms. The value form of a product exists after different products have been compared with each other. The value of products is dynamic because it continuously develops based on trading processes (Lendvai 1). Presently, individuals objectify the worth of produced goods to enhance trade. By doing this, t he individuals are evaluating and contrasting the value of their efforts. Additionally, while individuals are comparing and justifying the products’ value before exchange, they are also comparing the intensity of their efforts. Therefore, the worth of a product largely depends on the worth of other products regardless of product evaluation (Lendvai). This depicts that exchange value is at times relative. It is imperative to say that immanence is a notion of relationship. Therefore, exchange value is at times transcendental and exceeds the physical features of objects, implying that values exist above the individual senses (Lendvai 1). An example to illustrate this is that the aesthetic worth of a painting is not similar with the textile of the canvas and the oils within it, though the painting cannot exist without these substances. Additionally, the exchange value of an object like diamond cannot subsist without its physical and chemical reality. Similarly, two portions of wo od fixed with the figure of a cross may enjoy sacramental value. Therefore, these examples clearly show that exchange value can be immanent or relative. Q: 98. â€Å"Take two very different kinds of labor, such as teaching and construction work, and discuss in what respect they are equal†. There exists a relationship between teaching and construction work. Teachers serve as architects of a better future of students because they nurture and monitor their progress, thereby ensuring that these

Monday, November 18, 2019

How does the academic study of problem solving and thinking relate to Essay

How does the academic study of problem solving and thinking relate to everyday life - Essay Example Along with maturation, people obtain substantial competence that enables them to solve common problems encountered daily. (Holyoak 1995, p. 267) However, Anderson (1993, p. 39) explains, not everything requiring solution, like routine activities, is indeed problems. For example, summing-up a three-month electric bill, though requires solution is not a problem because one simply has to compute it either manually or electronically, but how to pay the bill with practically nothing left in one’s pocket is surely a problem. The difference here lies on the immediate availability of achieving the task. Computing the bill could be easily achieved with the simple knowledge of addition or much easier the use of calculator, but where to find the money to pay the bill not to be cut off power presents a problem, as there is no immediate solution to it. Hence a problem is determined by the gap between the present state and the target goal wherein the means to solve the gap is not immediatel y evident (Schwarz & Skurnik 2003, p. 267). Problem solving begins with problem identification (Rudd 2005, p. 11). Generally defined as the activity by which the goal of eliminating the gap is undertaken without certainty of success (Tallman, Leik, Gray, & Stafford, 1993, cited in Nelson, Brice & Gunby 2010, p.74), problem solving which could be correct or erroneous differs for every individual, because individual experiences and task demands, which problem solving entails, vary (Martinez 1998, p. 605). Similarly, the difficulty of solving problems differs in degree depending on the nature of the problem. Some could be easy; others could be truly hard or could never be solved at all. (Joswiak 2004, p. 19) ‘The relative ease of solving a problem will depend on how successful the solver has been in representing crucial elements of the task environment in his problem space’ (Simon, 1978, p. 276). The more exposed a person to varied task of compelling nature, the greater is the chance of that person to handle problems of similar/related nature. For example, an ex-marine has the greater chance of surviving a physical assault than a language teacher who has yet to experience physical violence. Moreover, problem solving has two aspects: The answer that which solve the problem, and the solution procedure by which way the answer is known (Robertson 2001, p. 6). With a variety of problems that people come across everyday solutions also vary by which Robertson (2001, pp. 6-11) says problems can also be categorised. One, what knowledge does the problem require – would it be â€Å"knowledge-lean† or â€Å"knowledge-rich† problems (p. 7)? For example, household maintenance though complex requires simple management, whereas ensuring national security is far more complicated that it requires expertise. Steif, Lobue, Kara, & Fay (2010, p. 135) suggest that the ability to determine fitted conceptual knowledge in order to solve a problem is cons idered a metacognitive skill. This according to Greeno (1978, p. 62) is learnable. Although, Gagne (1979) clarifies that what can be learned in problem solving are its specific aspects, cited as: "rules of syntax and mathematics," "knowledge about particular objects and events," "specific cognitive strategies" (cited in Mayer 1987, p. 111). Two, what is the nature of the goal? Is it technical, routine, domestic, political,

Friday, November 15, 2019

Interaction of Dye-surfactants and Dye-amino Acids

Interaction of Dye-surfactants and Dye-amino Acids Review of the literature shows that the study of interaction of dye-surfactants and dye-amino acids provide useful important information about physiological systems because of its widespread applications and relatively complex behaviour. These investigations are important from point of view of technology of dyeing processes as well as for chemical researches, such as biochemistry, analytical chemistry, and photosensitization. Most of the work on amino acids and biomolecules have been carried out in pure and mixed aqueous solutions but the investigation of spectroscopic, tensiometric and thermodynamic properties of amino acids in aqueous dye solution has rarely been done. On the other hand although studies have been made involving dye–surfactant interactions, yet this particular field of research is still important for improvised dyeing process in terms of theoretical, technological, environmental as well as economic point of view [1]. The dye-surfactant interaction has importa nce in many areas such as the spectral behaviour of dye in microheterogenous systems, dye-sensitized solar cells, and photocatalysis like photocatalytic water splitting. It is important to understand how surfactants and dyes interact in aqueous solutions to clarify the mechanisms of dyeing and other finishing procedures. Hence the investigation of interaction between surfactants / amino acid in aqueous dye solution was undertaken using different useful techniques. Mata et. al [2] investigated the physicochemical properties of pure cationic surfactants (quaternary salts) in aqueous solution by means of surface tension (at 303.15 K), conductance (at 293.15–333.15 K), dye solubilization and viscosity measurements. From the results it appeared that changes in the nature of the surfactant (such as changes in chain length, polar head group or counter ion) have a severe effect on the subsequent self-assembly in water. The increase in hydrophobic character of the surfactant decreases the CMC, induces sphere-to-rod transition at lower concentration and increases the solubilizing power of surfactant towards orange OT. Viscosity results indicated that the size of the micelles is relatively small at CMC and grows longer with increasing surfactant concentration. The plots of differential conductivity, (dk/dc)T,P, versus the total surfactant concentration enables us to determine the CMC values more precisely. The critical micelle concentration (cmc) and degree of ionization (ÃŽ ²) of cationic surfactants, dodecyldimethylethylammonium bromide (DDAB) and dodecyltrimethylammonium chloride (DTAC) in aqueous media were determined by Mehta et. al [3] from the conductivity measurements at different temperatures. The cmc behavior of DDAB and DTAC was analyzed in comparison with the results of DTAB in terms of effect of counter ion and increase in alkyl chain. It was observed that by changing the counter ion from chloride (DTAC) to bromide along with the increase in alkyl chain on polar head group (DDAB), the cmc shows a decrease. Thermodynamics of the system reveals that at lower temperatures, the micellization in case of DDAB was found to be entropy-driven, while at higher temperatures it was enthalpy driven. In DTAC system only entropic effect dominates over the entire temperature range. The aggregation properties of a cationic surfactant, DTAB, at different compositions in water-DMSO mixtures was studied by Và ©ronique Peyre et. al [4] using combination of techniques such as SANS, conductivity, and density measurements. Different complementary approaches were used for the interpretations of data. This multi-technique study explains the reason for the decrease in ionization degree, role of solvation in micellization and emphasizing the dissymmetric solvation of the chain by DMSO and the head by water. The study is interesting from the point of view that micellization process has been described by using combined analysis from molecular to macroscopic scale. Apparent and partial molar volumes of decyldimethylbenzylammonium chloride (C10DBACl) at (15, 25, and 35)  °C have been calculated from results of density measurements by A. G. Perez et. al [4]. The specific conductivities of the solutions have been determined at the same temperatures. The results served for the estimation of critical micelle concentration, cmc, ionization degree, (ÃŽ ²), and standard free energy of micellization, (à ¢Ã‹â€ Ã¢â‚¬  G), of the surfactant. J. J. Galan, J. R. RodrÄ ±guez [5] studied the molality dependence of specific conductivity of pentadecyl bromide, cetylpyridinium bromide and cetylpiridinium chloride in aqueous solutions in the temperature range of 30–45 à ¢-†¹C. The critical micelle concentration (cmc) and ionization degree of the micelles, ÃŽ ², were determined directly from the experimental data. Comparing our results for C16PBr and C16PCl water solutions, it can be observed that the substitution of the bromide anion by the more hydrophilic chloride leads to an increase in cmc by a factor of approximately 1.3. Chanchal Das and Bijan Das [6] have studied the micellization behavior of three cationic surfactants, viz., hexadecyl-, tetradecyl-, and dodecyltrimethylammonium bromide (CTAB, TTAB, and DTAB, respectively) in ethylene glycol (EG) (1) + water (2) mixed solvent media with varying mass fractions of EG (w1) by means of electrical conductivity and surface tension measurements. Temperature dependence of the critical micelle concentrations was also investigated to understand the micellar thermodynamics of these systems. From the study of the temperature dependence of the cmc of these surfactants in the EG (1) + water (2) mixture with w1 ) 0.30, they had demonstrated that the micellization was mainly governed by an enthalpy-entropy compensation effect. Data on the thermodynamics of adsorption demonstrate that the surface activity of these surfactant decreases with the addition of EG to water at a given temperature and that the adsorption of surfactant at the air/mixture interface takes plac e spontaneously. The micellisation behaviour of cetyltrimethylammonium bromide (CTABr) in different mass fraction (17–47) of ethylene glycol (EG), dimethylsulfoxide (DMSO), and dimethylformamide (DMF)–water mixed solvents, was studied by Olaseni et. al [7] using electrical conductivity measurement at different temperatures (293.1–313.1 K). The results of the thermodynamic analysis showed that addition of organic solvents, which are principally located in the bulk phase made the micellisation process less spontaneous. The London-dispersion interaction represented the major attraction force for micellisation and micellisation proceeded via an exothermic process. Sar Santosh K and Rathod Nutan [8] evaluated cmc, ÃŽ ± value and the thermodynamic parameters of the process of micellization for alkyl (C12, C14, and C16) trimethylammonium bromide systems in presence of water-dimethylformamide (5-20 % v/v) binary mixtures over a temperature range of 298-318 K. It was observed that both the cmc and ÃŽ ± value were dependent upon the (v/v %) of solvent and temperature and the micellization tendency of cationic surfactant decreases in the presence of solvents. It was also observed that the micellization is favored in general by entropy and enthalpy at higher temperatures, whereas it is favored mainly by entropy at low temperatures. A. Ali et. al [9] have studied the thermodynamic properties of sodium dodecyl sulphate in micellar solution of L-serine and L-threonine by fluorescence spectroscopy and dynamic light scattering techniques. They observed a decrease in cmc of SDS in Thr solutions as compared to that in Ser. The determined values of à ¢Ã‹â€ Ã¢â‚¬  G become increasingly negative in the order: water > Ser >Thr, suggesting that the formation of micelles is more favorable in presence of amino acids than in pure water. The aggregation behavior of SDS was explained in terms of structural changes in mixed solutions. On the basis of dynamic light scattering it was suggested that the size of SDS micelles was influenced by the presence of amino acids. F. Jalali and A. Gerandaneh [10] computed the critical micelle concentration (cmc) of cetyltrimethylammonium bromide (CTAB) conductometrically in binary mixtures of water + cosolvent at various temperatures and in the presence of potassium bromide (2.0 – 14 X10-3 M). Dioxane and acetonitrile were used as cosolvents added to water. Addition of organic solvents to water increased the cmc value of CTAB, but the presence of KBr lowered cmc. Thermodynamic parameters of micellization, were evaluated for each solution according to the pseudo-phase model, and the changes observed in these parameters were related to the presence of KBr and cosolvents in aqueous solution. The conductivity of (cosolvent C water) in the presence of increasing concentration of 1-hexadecylpyridinium bromide was measured at various temperatures by F. Jalali et al. [11]. Acetonitrile, dimethylformamide, dimethylsulfoxide, dioxane and ethylene glycol were used as cosolvents. From the conductivity data, the critical micelle concentration c.m.c., and the effective degree of counter ion dissociation ÃŽ ±, were obtained at various temperatures. In all the cases studied, a linear relationship between ([c.m.c] / mol . dm-3) and the mass fraction of cosolvent in solvent mixtures was observed. The thermodynamic properties à ¢Ã‹â€ Ã¢â‚¬  Hand à ¢Ã‹â€ Ã¢â‚¬  Swere evaluated from the temperature dependence of the equilibrium constants for micellization of the surfactant. While the micellization process in pure water is both enthalpy and entropy stabilized, it becomes entropy destabilized in all solvent mixtures used; the values of à ¢Ã‹â€ Ã¢â‚¬  S being more negative with increase i n the cosolvent content of the solvent mixtures. The resulting à ¢Ã‹â€ Ã¢â‚¬  H against Tà ¢Ã‹â€ Ã¢â‚¬  S plot showed a fairly good linear correlation, indicating the existence of an enthalpy–entropy compensation in the micellization process. The effect of the simultaneous presence of an electrolyte (NaBr) and nonelectrolyte species (DMSO and AN) in aqueous solution on the micellization of HDPB was studied by F. Jalali and A. Shaeghi Rad [12]. They concluded that the presence of NaBr favors the micellization of HDPB mainly due to a decrease in repulsions between micelle head groups. Adding a cosolvent, such as DMSO or AN, to water inhibits the formation of micelles because of the increase in hydrophobic character of the mixed solvent, which increases the attraction of surfactant monomers toward the solvent.

Wednesday, November 13, 2019

The Pathetic Jay Gatsby of Fitzgerald’s The Great Gatsby Essay examples

The Pathetic Jay Gatsby of The Great Gatsby      Ã‚  Ã‚   Pathetic is a term used to describe someone who is pitifully unsuccessful.   Success is not necessarily measured in wealth or fame, but it is measured by how much one has accomplished in life.   A successful person is one who has set many goals for himself and then goes out in life and accomplishes some of them, but goes on living even if failing on others.   In the novel The Great Gatsby, Jay Gatsby is a pathetic character because he wasted his whole life chasing an unrealistic dream.         Ã‚  Ã‚  Ã‚  Ã‚   Gatsby's dream is unrealistic because "it depends for its success upon Daisy's discontent with her marriage and her willingness to exchange it for a life of love.   But Daisy's discontent, like her sophistication, is a pose."(Aldridge 36)   The fact is, Daisy has almost all of the things that a woman could want out of a marriage.   She is very wealthy, she has a beautiful daughter, and her relationship with her husband is of a comfortable nature.   It is true that her life is not very exciting, but it is unreasonable to think that she would trade all that she had in her marriage to Tom Buchanan for Jay Gatsby.   At that time, divorce was very uncommon, and it was very unlikely that any woman would leave her husband for any reason at all.         Ã‚  Ã‚  Ã‚  Ã‚   Everything that Gatsby ever did in his whole life was based upon his pursuit of the dream.   He   moved to New York and bought his very expensive mansion because of Daisy.   Jordan Baker said, "Gatsby bought that house so that Daisy would be just across the bay."(Fitzgerald 83)   He held many expensive parties in the hope that Daisy mi... ...ing as a flawless plan.   A successful person would achieve their goals by meeting their needs in life by using what was given to them. Gatsby tried to do the opposite, and failed.   "Gatsby's story it is a story of failure - the prolongation of the adolescent incapacity to distinguish between dream and reality, between the terms demanded of life and the terms offered."(Troy 21-22)       Works Cited    Fitzgerald, F. Scott.   The Great Gatsby.   New York: Macmillan, 1992.    Twentieth Century Interpretations of the Great Gatsby.   Ed. Ernest H. Lockridge.   Englewood Cliffs, N.J.: Prentice-Hall, 1968.    Troy, William.   "Scott Fitzgerald - The Authority of Failure."   F. Scott Fitzgerald: A Collection of Critical Essays.   Ed. Arthur Mizener. Englewood Cliffs, N.J.: Prentice-Hall, 1963.   21-22.    Â