Research and the Sciences Essay Example for Free

Research and the Sciences Essay There has long been an ongoing argument: Is social science scientific? Which approach is better in conducting natural sciences and social sciences? It is believed that hypothetico-deductive approach may be applicable to the natural sciences while it does not relate well to the social sciences. By analyzing research from different levels, this essay presents a judgment that social sciences are sciences. First of all, the concept of research and science are given. Secondly, by accepting that social sciences are different from natural sciences, the features that identify social sciences from natural sciences are summarized. There are many choices of approaches to conduct research. In the level of philosophy, research approaches could go to inductive approach and deductive approach. Qualitative research and quantitative research distinguish each other methodologically. In this essay, the different approaches are compared and contrasted after a concise interpretation of these concepts. And finally, the question better approach to research in natural sciences and social sciences is considered. Research is defined by Join and Keith as seeking through methodical process to add ones knowledge and, hopefully to others by the discovery of nontrivial and insight (Join and Keith, 1996). Williams defined science as the ensemble of knowledge and practices that best reflect and operationalize a critical attitude to the discovery of the world at that moment in time (Williams, 2000 p.26). Basically, sciences can be divided into social sciences and natural sciences. Social sciences study human being and their behavior, while natural sciences study physical world. The presupposition that natural science is the benchmark of research, in some degree, accounts for why most people associate the word research with activities that are substantially removed from daily life and which usually take place in a laboratory. And accordingly arises the doubt whether social science is science. A good deal of overlap and unavoidable duplication will be encountered if any attempt is made to review social sciences and natural sciences  systematically (McErlean, 2000). Yet there are still some typical features in which social sciences are different from nature sciences. Historically and perhaps intuitively, the natural and the social sciences have been identified by distinct subject matters: Natural science is a branch of science which deals with the physical world (Pearsall, 1999 P.950), while social science is the scientific study of human society and social relationships (Pearsall, 1999 p.1362). Invariability of observations is different in two kinds of sciences. The difference lies probably in the number of relevant factors that must be taken into account for explaining or predicting events in the real world(McErlean, 2000). It is agreed that verification is not easy to come by in the social sciences, while it is the chief business in the natural sciences. Measurability of phenomena, whereas physics is clearly ahead of all other disciplines. Natural sciences have got constancy of numerical relationship which social sciences has not got. The social sciences deal so close to a mans own everyday experience that they do not accord the respect as natural sciences. The field of natural sciences needs higher standards of admission and requirements than the social sciences. On this score, the natural sciences are better than the social sciences (McErlean, 2000). Since social sciences differ from natural sciences in many ways, should different approaches be chosen when conducing social science research and natural sciences? This is another baffling question. Now we will turn to the discussion of deduction and induction. Philosophically the approaches are focused on the consideration of induction and deduction, as well as the relationship between approaches and sciences. Deduction entails the development of a conceptual and theoretical structure prior to its testing through empirical research methods. (Carson et al, 2001 p.11). Induction is the action or process of inducing something (Pearsall, 1999). It is learning by reflecting upon particular past experiences and through the formulation of abstract concepts, theories and generalizations that explain past and predict future experience (Gill and Johnson, 2002). Induction and deduction approaches are different in many aspects. They are best used in different stages of Learning Cycle. When learning takes place, the difference between deductive and inductive approach is that one starts  with theory which tested through observation while the other starts with observation and tries to create theory (Gill and Johnson, 2002). Localization of Induction differs from that of deduction (Carson et al, 2001 P12). Induction might prevent the researcher benefiting from existing theory, while deduction might prevent the development of new and useful theory. In contrast to the deductive tradition, theory is the outcome of induction (Carson et al, 2001 P12). The time needed for induction is often prolonged than deduction B Deductive research is normally possible to predict accurately the time schedules, it is quicker to complete, though the time must be devoted to set up the study prior to data collection and analysis. Deduction and induction carry unequal risk. The deductive approach can be a lower-risk strategy, albeit there are risks like the non-return of questionnaires. With induction it is quite possible that no useful data patterns and theory will not emerge. The effect of deduction or induction is relevant to the ability of researcher. The way one thinks about the development of knowledge affects, unwittingly, the way he goes about doing research (Saunders et al, 2000). So it is more appropriate to adopt the inductive approach if the researcher is particularly interested in understanding why something is happening rather than describe what is happening, Inductive designs begin with specific observations and build toward general patterns. This is different to the hypothetical-deductive approach of experimental designs that require the specification of main variables and the statement of specific research hypotheses before data collection begins (Pattern, 1987). Saunders et al (2000) has shown the main differences between deductive and inductive approaches as can be seen in diagram 1. The blending of Induction and Deduction are preferable in conducting a research. In deductive argument, conclusion follows logically from the premises, while inductive argument, in which the premises support the conclusion but do not guarantee it (Rosenberg, 2000). It seems that deductive is more impressive than inductive. Not only because it is more highly structured and more appropriate for people who are inexperienced in research matters but also because it is the basis of much knowledge that  they do have of the subject (Walley, 2002), But the two approaches are not mutually exclusive. They are better at doing different things. So the balance of both approaches in the same research project is preferable. Not only is it perfectly possible to combine approaches with the same piece of research, but also in human beings experience it is often advantageous to do so (Saunders et al, 2000). For example: Sadie decided to conduct a research project on violence at work and its effects on the stress levels of staff. She considered the different ways she would approach the work were she to adopt, the deductive approach and the inductive approach. If she decided to adopt a deductive approach, She should standardize the stress responses of the staff. On the other hand, if she decided to adopt an inductive approach she may have decided to interview some staffs who had been subjected to violence at work. She may have been interested in their feelings about the events that they had experienced, how they coped with the problems they experienced and their views about the possible causes of the violence (Saunders et al, 2000). In order to gain more comprehensive results, it is better to combine both approaches. Diagram 1 Emphasizes of Deduction and Induction Deduction emphasizesInduction emphasizes Scientific principlesGaining an understanding of the meanings humans attach to events From theory to dataFrom observation to theory The collection of quantitative dataThe collection of qualitative data The application of controls to ensure validity of dataResearcher is part of the research process Ensure clarity of definitionLess need generalize Highly structured approachMore flexible structure to permit changes of research emphasis Researcher independence of what is being researchedDependent researcher Select samples of sufficient size Saunders et al (2000 p.91) Researcher may use a variety of methodology to conduct research. It is said that the concept of induction often is applied to qualitative research (Strauss and Corbin, 1998 p.136) while deduction is applied to quantitative research. Qualitative research is so called because its emphasis lies in producing data which is rich in insight, understanding, explanation and depth of information, but which cannot be justified statistically (Crouch, 1985). Qualitative research usually produces descriptions, explanations and reasons (Strauss and Corbin, 1998). It seeks to answer how and why type questions (Walley, 1995). The strengths of qualitative research derive from its inductive approach, its focus on specific situations or people, and its emphasis on words rather than numbers (Maxwell, 1996). It may involve statistics but it is not based on statistical significance. It is characterized by the use of group discussions, personal interviews, projective techniques and non-probability sampling (Walley, 1995) .The usefulness of qualitative research depends very much on the skills of the researcher (Gill and Johnson, 2002). Qualitative methods are particularly oriented toward exploration, discovery, and inductive logic. Walley (2002) cited Proctor (1997) as Quantitative research that primarily research concerned with eliciting information which has statistical significance. Its focus is on quantification of phenomena sampling and large scales postal questionnaires. The quantitative data identify areas of focus whist the qualitative data give substance to those areas of focus. Whereas qualitative data can put flesh on the bones of quantitative results, brining the results to life through in-depth case elaborations (Patton, 1987). The patterns displayed in quantitative research can be enriched with the addition of qualitative information (Gill and Johnson, 2002). The  qualitative should direct the quantitative feedback into the qualitative in a circular (Strauss and Corbin, 1998). Thus, recent developments in the evaluation profession have led to multiple methods including combinations of qualitative and quantitative data. Some evaluation questions are determined deductively while others are left sufficiently open to permit inductive analyses based on direct observations. Indeed, there is often a flow from inductive approaches to find out what the important questions and variables are, to deductive hypotheses-testing aimed at confirming exploratory findings, then back again to inductive analysis to look for rival hypotheses and unanticipated or unmeasured factors (Patton, 1987). Sayre believed that: qualitative methods are chosed because of its emphasis on progresses and meanings while quantitative methods are utilized because they substantiate. Actually both methodologies are combined to provide a comprehensive approach to problem solving (Sayre, 2001). The relation between qualitative research and quantitative research are clearly showed below in the diagram 2. Diagram 2 qualitative research and quantitative research Qualitative researchQuantitative research Type of questions ProbingNon-probing Sample sizeSmallLarge Information per respondentMuchVaries AdministrationRequires interviewer with special skillsFewer special skills required Type of analysisSubjective, interpretativeStatistical Hardware requiredTape recorders, projection devices, discussion guides replicationDifficultEasy Researcher training necessaryPsychology, sociology, social psychology, consumer behaviour, marketing, marketing research Statistics, decision models. decision-support systems, computer programming, marketing, marketing research Type of researchexploratoryDescriptive or causal Proctor (2000) In conclusion, the differences between social sciences and natural sciences have been discussed, and the approaches and methods used in conducting both sciences have been compared and contrasted. Social sciences and natural sciences are fundamentally different in many ways, yet social sciences are, beyond all doubt, scientific too. From the view of philosophy, there are inductive research and deductive research. The deductive approach is probably more impressive. Methodologically quantitative research differs from qualitative research. Each approach has its unique advantages and disadvantages. It would be easy to fall into the trap of thinking that one research approach is better than another. Actually they are better in different situations, depending on where the research emphasis lies. It is encouraged to think in a more flexible way about the research approaches and methods adopted. Yet the best policy in conducting research is to blend approaches. So, it is clear that social sciences are sciences likewise as natural sciences. Adopted appropriately, the methodological approach of natural science can be used to study the social world (Williams, 2000). One approach cannot therefore be considered to be better than another in conducting  research in both natural sciences and social sciences. So it is high time to stop arguing about whether social sciences are science or not. Alternatively, to consider which approach is preferable or how to blend them together is what deserves thinking when a research is conducted. Reference Bancroft, G and Osullivan, G.(1993)Quantitative Methods For Accounting and Business Studies .3rded.Berkshire:McGRAW-HILL Book Company Europe. Carson, D.; Gilmore, A.; Perry, C.; Gronhang, K(2001)Qualitative Marketing Research. London: Sage publications. Gill, J. and Johnson, P.(2002)Research methods for managers .3rd.ed.London:Sage Publications Ltd Greenfield, T.(2002).Research Methods For Postgraduates. 2nded. London: Arnold. Sharp, J. A. and Howard, K (1996). The Management of a Student Research Project 2nd.ed Aldershot:Gower Publishing Limited. Maxwell, J.A. (1996)Qualitative Research Design-an interactive approach. London: Sage Publications Mcerlean, J.(2000).Philosophy of Science-From Foundations to Contemporary Issues. London: Routledge. Papineau, D.eds.(1996).The Philosophy of Science Oxford: Oxford University Press. Patton, M .Q (1987). How To Use Qualitative Methods In Evaluation. London: Sage Publications Pearsall, J. eds.(1999).Oxford dictionary. Oxford :Oxford university press. Proctor, T. (2000)Essentials of Marketing Research.2nd.ed.London:Financial Times prentice Hall Robson, S. and Foster, A. (1989) Qualitative Research in Action London: Great Britain. Rosenberg, A.(2000).Philosophy of Science:Acontemporary Introduction.London:Routledge. Saunders, M; Lewis, P. and Thornhill, A. (2000). Research Methods for Business Students. 2nd.ed Harlow: Financial Times Prentice Hall. Sayre, S. (2001) Qualitative methods for Marketplace Research. London: Sage publications. Strauss, A and Corbin, J. (1998) Basics of Qualitative Research. London: Sage Publications, Inc. Walley, K. (1995) Qualitative Research-Discussion Paper. Newport: Harper Adams Agricultural College. Walley, K. (2002) Research Methods For The Agrifood Industry. Newport: Harper Adams University College. Williams, M. (2000).Science and social science-An introduction. London: Routledge.

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A History of Computers by: Paul Little The idea of a machine that would make man’s calculations easier, faster, and more accurate is no new notion. The Abacus, Napier’s rods, the Calculating Clock, and the Stepped Reckoner are a few examples of early computer ideas In the more recent history of the computer, we can see how computers have morphed changed from clunky, million-dollar machines into the compact and convenient devices which can held on the tip of ones finger. John von Neumann’s name is most well-known among the potential â€Å"founders† of the first computer (and also known for work in quantum mechanics) but who the credit belongs to can be debated. Von Neumann wrote a memorandum explaining the Electronic Numerical Integrator and Calculator (ENIAC) but the ENIAC was developed by J. Preper Eckert and John Mauchly of the Moore School of the University of Pennsylvania in the mid-1940s. The credit for this invention is shady because Mauchly reportedly visited John Atanasoff before building the ENIAC. Atanasoff built the Atanasoff/Berry Computer in the early 1940s at Iowa State University. But, von Neumann’s name is the most well-known and thus settles the issue! The model von Neumann came up with for the basic computer structure is still today, with modifications for speed and size, his computer is still the foundation for many computers. Part of the the reason his work was seen in high standards was hs reports on his work. The Academic Press Dictionary states that â€Å"von Neumann’s report was so we... ...Whether you agree or not, the NSA’s new 1.7 billion facility being built to store internet users data and phone call and is the largest facility ever built to do so, can be viewed as a new treat to people personal data and piracy. Believed â€Å"once finished† ith the ability to hold not only the most but some of if not the biggest super computers in the world. It is said the facility once up and running will be able to store data at the rate of 20 terabytes per minute, many times over. The ability to do so is in its self amazing and the other technology that will be used there I am sure will be just as mind boggling. But most are more concerned with the negative potential (and rightfully so) over the technical scale of the project, but ever the less this will probably be the start of the next (out of many past and future) computer generation.

The Advantages Imparted By Resin Addition To Conventional Glass Ionomer Outweigh The Disadvantages

Glass Ionomer Cements (GIC) is created when ion-leachable calcium alumino-silicate glass powder that contains fluoride reacts with polyalkenoic acid. Recently, the use of GIC has been extensive in dentistry as it can be modified by combining it with several substances and the properties can be further enhanced. GIC cement was initially developed by Wilson and Kent in England in the year 1972 (Graig, 2002). When created earlier, the GIC was not an aesthetic material and did not have any translucency. It was utilized to full only small class V abrasive lesions.It was slowly modified and can be used in several clinical processes such as luting, as a lining and a base, etc. GIC has certain unique properties that may not be present in any other material. It helps to conserve the tooth structure and it directly bonds with the tooth. The GIC cement directly bonds to the dentine present in the tooth. It helps to remineralise caries and hence can be utilized by preserving the tooth material. The GIC cement slowly releases fluoride over a long-period. This property of GIC can also be utilized in caries prevention and in patient’s having a high-risk of developing caries (Mount, 1998).The powder present in the resin-modified GIC cement is somewhat similar to the conventional GIC’s. The liquid contains monomers and polymers to ensure the strength of the GIC cement is increased (Graig, 2002). The GIC cement has usually two components, a powder and a liquid. The powder is a ion-leachable alumina-silicate glass. The liquid contains polymers and copolymers of acrylic acid dissolved in water. During the setting reaction Aluminium ions and calcium ions are released by the glass and polymers release acid groups.The setting reaction takes place slowly and results in the formation of a cross-linked gel matrix. Aluminium ions may be exchanged slowly in the gel matrix which helps to strengthen it. This process occurs very slowly until the final set. The calcium present i n the gel matrix may combine with the exposed GIC cement bonds using both diffusion an the adsorption phenomenon (Mount, 1998). When the freshly cut tooth surface is smeared with GIC, the polyalkenoic acid plays a very important role in initiating adhesion. The carboxyl ions present in the acid displaces the phosphate ions present in the apatite crystals.The Calcium phosphate-polyalkenoate crystalline complex formed at the interface of the tooth surface and the GIC material plays a very important role in bonding. This phenomenon is frequently-known as diffusion based adhesion (Mount, 1998). When the intermediate complex phase is subjected to acid etching, it was more resistant to etching than the other portions of the tooth. When forces were applied to debond the restoration to the tooth, the complex phase formed was left behind. The carboxyl group of the polyacid of the GIC combines with the collagen molecules of the dentin to form a bond.The strength of this bond may be increased by using conditioning agents such as citric acid and hydrogen peroxide which help to remove the smear layer. However, polyacrylic acid is the best material in removing the smear layer and improving adhesion. Polyacrylic acid helps to remove the smear layer, but does not interfere with the dentinal plugs that block the entry into the dentinal tubules. This helps to prevent the development of hypersensitivity following restoration. This solution can also be utilized remove the smear layer (Mount, 1998). The Cement so formed may have a lot of limitations which may restrict use.GIC cement is slightly more soluble in the saliva compared to several other dental cements especially the resin containing cements. However, GIC cement is more resistant to solubility than other cements such as silicate cements. Another problem of GIC cement is that it may begin to disintegrate in the oral cavity when certain problems such as zerostomia or Sjogern’s syndrome are present. This is because th e GIC cement tends to lose its moisture in the oral cavity. In such a circumstance, GIC restorations have to be replaced every few months or maximum on an annual basis.Frequently, the cement has to be covered by a composite resin lining to ensure that the GIC cement does not face the ruthless environment of the mouth, especially in Sjorgren’s syndrome (Mount, 1998). Resin modified GIC cements helps to make the material more resistant to both excessive solubility in the oral cavity and excessive destruction from unfavourable conditions present in the mouth such as Sjogren’s syndrome (Mount 1998). GIC cement tends to shrink slowly with time. The shrinkage on an average basis (volumetrically) is about 3 %.This shrinkage develops slowly over a period of time. On the tooth side of the restoration, as the GIC combines with the collagen and the tooth surface to form a bond, the shrinkage may not be much to result in debonding of the restoration from the tooth. The stress rela xation is not much on the tooth side of the restoration. When the cement tends to set slowly, it usually absorbs water and also dissolves slightly more in the saliva. Slowly setting cements overall do not have good mechanical properties but anyway shrink less than the faster setting GIC’s.A cavity varnish or a Composite Resin may have to be applied to the surface of slow-setting GIC cement in order to protect if from the oral environment during the initial stages following setting. In resin-modified GIC cements, even if the resin content is about 5 %, it would result in reduced amounts of shrinkage at the time of placement. The shrinkage that develops over a period of time occurs much more slowly. The adhesion formed between the tooth surface and the GIC helps to limit shrinkage to some extent (Mount,1998). GIC cements are weak material and lack rigidity.They are susceptible to fracture compared to other materials such as dental amalgams and composite resins. Those restoratio ns with GIC prepared in high stress bearing areas, having high occlusal load, usually fail within a short period of time. However, research suggests that the resin-modified GIC cements have a better strength compared to the conventional GIC cements. The transverse strength of resin-modified GIC cement is almost twice that of conventional GIC cement (Graig, 2002). They also have higher fracture resistance, almost comparable to micro-filled composite resins.On an average, the compressive strength of conventional GIC cements is about 70 to 220 MPa, and that for luting GIC cements is about 10 to 150 MPa. The compressive strength for a resin-modified GIC cement is about 110 to 220 MPa. The tensile strength for conventional GIC cements is about 12 to 16 MPa and that for luting GIC cement is about 6 to 15 MPa. The tensile strength of resin -modified GIC cement is about 15 to 16 Moa. The Shear strength of the conventional GIC cement is about 30 to 40 MPa and for the luting GIC cement is abo ut 20 to 25 MPa.On the other hand, the resin-modified GIC cement has shear strength of about 60 to 70 MPa. During the early days, the GIC cements did not have a good compressive and tensile strengths. However, nowadays due to advancements in the materials, the compressive and tensile strengths of conventional GIC is approaching that of resin-modified GIC and also the microfilled composite resins (Mount, 1998). However, the resin-modified GIC cements should only be utilized in low –stress bearing areas. They can be utilized in patients having a high-caries rate as the GIC cement has anti-cariogenic properties (Graig, 2002).Many dental practitioners consider using cermets cements or sliver-impregnated GIC cements in load-bearing areas as they would feel that it helps improve the facture toughness of the GIC. However, this is a wrong perception as cermets cements only help to improve the abrasive resistance. Conventional GIC cements have a reasonable amount of resistance to abra sion. They may be susceptible to abrasion during the initial stages following placement (Mount 1998). Self-curing GIC cements may have moderate translucency, but this may take several days to develop.Self-curing GIC cements tend to be affected by the presence of water during the initial period following setting. Hence, self-curing GIC cements may have to be carefully sealed during placement for at least 24 hours until some amount of translucency is achieved. The technique of placement plays a very important role in the case of conventional GIC. Resin-modified GIC cements show a much better translucency compared to the conventional GIC cements. The translucency is achieved immediately following curing with light. The translucency may slightly worsen over the next few days following placement, but this may not be perceived to the eye.Following this, the translucency improves again and sometimes it even achieves a greater amount of translucency compared to that obtained following curin g (Mount, 1998). HEMA (about 15 to 25 %), certain polymerisable groups (1%) and a photo-initiator are present in the liquid component of the resin-modified GIC cement. The light –activation of the GIC enables polymerization of the resin, and the chemical reaction between the liquid and the powder components of the GIC goes on as in an auto-curing system. The final setting of the resin-modified GIC cement is the same as that of conventional cement.As HEMA is present in the liquid component of the resin-modified GIC cement, using thinly consistency cements would bring about a higher HEMA content in the final set mixture. A thick mixture would contain 4. 5 % HEMA, whereas thinly-mixed GIC cement would contain about 15 % HEMA. The HEMA is capable of drawing water from the oral environment and degrading. Further, HEMA is released into the dentin. The presence of certain trace elements in the GIC cement brings about an oxidation-reduction reaction and ensures that the HEMA is not l eft behind. Hence, water is not absorbed from the environment by the GIC cement.During the setting of the resin-modified GIC cement, two basic reactions occur between the powder and the liquid. The first is the acid-base reaction between the polyalkenoic acid and the glass powder. Two separate matrices are formed, one is a hydrogel of the ionomer salts and the other is a poly-HEMA matrix. When these two matrices are formed, the interactions prevent the acid-base reactions from completing. The HEMA particles will begin to set following activation by light, and will prevent the auto-curing GIC cement from absorbing water almost immediately (Mount, 1998).This will also ensure that a greater amount of strength is achieved by the restoration almost immediately (Graig, 2002). The acid-base reaction, the light-curing reaction (along with the presence of the photo-initiator) and the oxidation-reduction reactions ensure that adequate cross-linking takes place in the resin-modified GIC cement . The light-curing reaction ensures sufficient and immediate hardening of the GIC mass provided the light activation is performed. The acid-base reaction will continue for a few days to bring about hardening within a few days.The cross-linking formed in the acid-base reactions and the HEMA matrix will ensure that water is not taken up by the GIC mass. The 5 to 15 % HEMA present in the GIC ensures that water is not immediately taken up by the GIC mass. However, as a sufficient quantity of substances present in the conventional GIC cement is present, the chances of dehydration following the initial setting reaction are still high. Hence, light-cured resin-modified GIC cement should also be protected with a low-viscosity resin sealant (Mount, 1998).When resin-modified GIC cement is utilized as a base below composite resin restorations, there is no need to etch the GIC cement before inserting the composite resin material. HEMA helps in forming a chemical bond between the GIC cement and the composite resin. Efforts should be made during the etching process to prevent accident etching of the GIC cement. However, etching the GIC cement would not result in an adverse affect. When GIC cement is utilized below amalgam restorations, it is better to use resin-modified GIC cement as it can tolerate higher strengths compared to the conventional GIC cements (Graig, 2002).Resin-modified GIC cements are frequently utilized below composite resin restorations since the year 1985, so as to lower microleakage. Besides, fluorides released by the GIC would ensure that secondary caries does not develop. The composite resin would ensure that superior aesthetic effects of the restoration would be maintained. Fluorides leached by the GIC would ensure that the restoration has some anti-cariogenic effect. Earlier, conventional GIC cement was utilized below composite restorations, and only mechanical interlocking between both the materials occurred.The GIC present below the resin material was lost over a period of time. There is no chemical bonding between the GIC and the composite resin restoration and hence, the bond strength is very poor. The use of rein-modified GIC cements present below composite resins helps to improve the bond strength as a chemical bonding would be formed between the monomer present in the GIC and certain substances present in the composite resin (Taher, 2007). The GIC utilized in a laminate or sandwich technique can be used in two fashions, that is open sandwich and closed sandwich technique.In the open sandwich technique, portions of the GIC are exposed to the oral cavity. The GIC is not only utilised to cover the exposed dentin but is also placed peripherally to form a type of seal. In the closed technique, the GIC covers the dentin and is in turn completely covered by the composite resin restoration. Using conventional GIC cements, the failure rates were 13 to 35 % within 2 years and 75 % within 6 years. The conventional GIC cements place d were capable of degenerating to a greater extent in the saliva and are also susceptible to fracture due to decreased fracture resistance.Gradually, resin-modified GIC began to replace the conventional GIC under composite restorations. As resin-modified GIC cements have superior properties, they would ensure a longer life, and would also have an anti-cariogenic effect. Studies demonstrated that the resin-modified GIC developed better proprieties and was not much technique-sensitive compared to the conventional GIC cements. In the open-sandwich technique, the marginal seal developed by the resin –modified GIC cement was much better than the composite resin materials and hence is preferred.The caries rate was much less in the patients using Resin-modified GIC cements compared to the conventional GIC cements. A study was conducted by Dentists in a city in Sweden to study the effect of using resin-modified GIC cements on about 239 restorations. It was found that the 5 % of the r estorations had become unacceptable after 3 years (that is about 5 % of all restorations treated with open-sandwich techniques had failed). Tooth fractures developed in about 2. 5 % of the restorations. Minor erosions of the GIC were observed in 4 %. Secondary caries developed only in one of the 239 restorations.The properties of resin-modified GIC cements is much superior to conventional GIC cement when utilized beneath composite restorations in a sandwich technique. The Resin-modified GIC cements are less susceptible to dissolve and disintegrate in the salvia compared to the conventional GIC cements. It also adapts well to the cavity walls and offers a chemical bonding with the composite resin. The failure rate with resin modified GIC cements was much less compared to that of conventional GIC cements. The sandwich technique can be utilized as an alternative to amalgam restorations especially in those with a high caries index.The restorations produced have a lower failure rate and has a much longer life. However, the use of resin-modified GIC cements for sandwich technique has not been studied on a long term basis (van Dijken, 1999). The bond strengths formed between resin-modified GIC cements and the composite resin materials was higher compared to that between the conventional GIC and the composite restorations following etch and bond technique. In etch and bond technique, the bond strength formed was about 2. 42 MPa compared to that of 6. 87 to 7. 05 MPa formed between the resin-modified GIC and the composite restorations (Knight, 2006).Another study conducted in the University of Cardiff by Chadwick et al (2007), demonstrated that resin-modified GIC cement had a much better success rate compared to conventional GIC cements. The failure rates of conventional GIC cements were between 6. 6 to 60 %. The failure rates of resin-modified GIC cements were found to be between 2 to 14 %, suggesting superior mechanical properties. Some amount of evidence is present from past literature that resin-modified GIC cements could also be utilised to a certain extent in small and moderate sized class II restorations (Chadwick, 2007).A study was conducted to study the surface properties of resin-modified composite resins compared to that of conventional GIC and that of composite resin restorations. The materials were examined following polishing with silicon carbide. The composite resin restorations and the resin-modified GIC cements were more resistant to the effect of foodstuff such as tea, coffee and red wine on the restoration than the conventional GIC. The surface roughness of the composite resin restoration and the resin-modified restoration were much lesser compared to the conventional GIC restoration (Bagheri, 2007).There are not much of differences in the composition of the resin-modified GIC and the conventional GIC cements. The resin-modified GIC contains a small percentage of monomers and polymers to bring about superior mechanical properti es. Resin-modified GIC cements are more resistant to solubility and excessive disintegration from several factors that operate from within the oral cavity. The shrinkage that develops in resin-modified GIC is much slower and less compared to conventional GIC cement. Resin–modified GIC cements have higher transverse strengths, compressive strengths and fracture resistance compared to conventional GIC cements.Even the tensile strengths and the shear strengths of resin-modified GIC cements are higher than conventional GIC cements. However, resin-modified GIC cements should not be utilized in high stress bearing areas, as they could fail. Resin-modified GIC achieves its final properties almost immediately, following curing with light. Resin-modified cements have better properties when placed below composite and amalgam restorations. Below composite restorations, it forms a chemical bond with the composite. As its strength is higher, it can be utilized below amalgam restorations.I t also helped to reduce the secondary caries rate as they released fluorides over a period of time. The surface properties of Resin-modified GIC are also much better compared to that of conventional GIC, and hence the aesthetic properties would be much better. All these superiorities do imply that Resin-modified GIC should be preferred for use in various situations. However, the Resin-modified GIC should not be utilized to fill large cavities in stress bearing areas, as they are susceptible to fail.

Criricism of Wilkie Collins’ Woman in White Essay

Criricism of Wilkie Collins’ Woman in White â€Å"To Mr. Collins belongs the credit of having introduced into fiction those most mysterious of mysteries, the mysteries which are at our own doors.† So said Henry James in an unsigned review of another author’s work. But his view was certainly not shared by all those who cast their opinions into the fray. An unsigned review in the Saturday Review said of Collins’ work, â€Å"Estimated by the standard of great novels, the Woman in White is nowhere. Somewhere between these two points are friends and correspondents of Mr. Wilkie Collins. Novelist George Meredith wrote to Collins himself saying, â€Å"The tension of the W[oman] in W[hite] is not exactly pleasant, though cleverly produced. One wearies of†¦show more content†¦Another is a good-natured family lawyer of the old school. A third is a brave and determined lady.† Playing on Collins’ own comparisons to a court trial this reviewer wrote, â€Å"They are not staring at the spectators , or, if they are, they are staring listlessly and vacantly, like witnesses who are waiting to be called before the court, and have nothing to do until their turn arrives.† Of course many positive critiques of the novel existed. One was written as a direct reaction to the Saturday Review piece. This anonymous reviewer of the Spectator cried out , â€Å"The vivid and manifold emotions with which we read her story are still fresh in our memory, and we retain a lively sense of the personality of every actor in it from Marian and Laura down to the old parish clerk. Yet we are told that the author `does not attempt to paint character or passion. He is not in the least imaginative!’ Mashallah!† This critic ends his or her review stating, â€Å"To sneer at the best thing of its kind because it is not something else is a convenient mode of detraction, and, when done with assurance and a certain degree of literary tact, it may pass with the unwary for authoritative criticism; but it seems a pitiful thing after all when once the trick of it has been discovered.† And once again a middle road emerged from between the two extreme views. An unsigned in The Times praised Collins, but with restraint. â€Å"We must be content to ask, in the name of