Laser Tissue Interaction

Laser Tissue Interaction Laser-Tissue interaction Like normal light, laser light can interact with tissue in four basic ways1 as follows: (1) Reflection: some light reflects back off the surface, its energy neither penetrating nor interacting with tissue. (2) Transmission: some (light) may be transmitted through tissue, albeit unchanged as if transparent to the laser beam and without interaction between the incident beam and the tissue. (3) Scatter: some light may penetrate the tissue and be scattered without causing a noticeable effect on the tissue2 .Scattering causes some lessening of light energy with distance, together with distortion in the beam, whereby rays proceed in an uncontrolled direction through the medium. Moreover, back-scatter can occur as the laser beam hits the tissue, most commonly in short wavelengths, e.g. diode, Nd:YAG (≠¥50% back-scatter). (4) Absorption: some light may be absorbed into a component of the tissue, whereby there will be transference of energy to the tissue, i.e. the incident energy of the beam is attenuated by the medium and transferred into another form. In clinical dentistry, depending on the value of the energy, there is conversion into heat or, in the case of very low values, photobiostimulation of receptor tissue sites (e.g. sun-bathing the stimulation of ‘tanning melanocytes by low-grade UV sunlight versus the damaging sun-burn with higher exposure values) Laser wavelength absorption and tissue composition Laser tissue interactions, as described above, are not exclusive and occur in varying proportions within tissues depending on the chemical and or molecular variation found within such complex biological systems. The degree of interaction is usually proportional to the level of absorption of a particular wavelength by tissue. Tissue elements that absorb a particular wavelength or spectrum of light energy to a high degree are called chromophores. All (organic) matter has the property of ‘absorption specificity which determines how it reacts to incident radiation. Indeed, the preferential absorption of specific wavelengths of radiant energy by chromophores within tissues accounts for the unique interactions that occur between the monochromatic light energy of lasers and various tissue elements. Laser wavelengths thus affect certain, inter-related components of the target tissue, that is: its water content; colour; and chemical composition. In dentistry, oral tissue comprises one o r more chromophores haemoglobin, melanin and allied pigmented proteins, (carbonated) hydroxyapatite, and water. Generally speaking, any predominantly pigmented tissue absorbs shorter laser wavelengths (i.e. visible and near infra-red), whereas non-pigmented tissue absorbs longer wavelengths. Consequently, absorption peaks of water and (carbonated) hydroxyapatite, coincident with Er:YAG, Er:YSGG and CO2 wavelengths, would support the potentially advantageous use of these lasers in hard tissue management. Moreover, oral soft tissues mainly comprise water, which predominantly controls the tissue effects of laser emissions within the infrared spectrum, such as CO2. Therefore, CO2 laser energy is absorbed very efficiently by tissue fluids with minimal penetration beyond the surface2. Conversely, water is comparatively transparent to the emission of the Nd:YAG laser, which accounts for its tendency to penetrate deeper into tissue. In this way, whereas CO2 wavelength might penetrate oral epithelia to a depth of 0.1-0.2 mm, Nd: YAG and diode wavelengths can result in an equivalent-power penetration of 4-6 mm.3 Light Absorption in Tissue Absorption characteristics for various wavelengths in four absorption media (oxyhaemoglobin, melanin, hydroxyapatite and water). The absorption coefficient is plotted as a function of the wavelength, and the absorption coefficient for a given material is plotted on this graph. A high absorption coefficient means the given laser wavelength is well absorbed in the selected medium. A low absorption corresponds with a greater degree of transparency allowing the light to penetrate deeper into the medium. Note that the vertical scale is logarithmic; that is, each grid line is equivalent to a change of the absorption coefficient by 1 order of magnitude (factor 10). Photobiological Effect The overriding beneficial effect of laser energy is absorption of the light by the target tissue and the transfer of laser energy, thus causing a tissue interaction (Photobiological Effect). There are four basic interactions that can occur following absorption of laser energy: (1) Photochemical (Photochemolysis): certain wavelengths of laser light are absorbed by naturally occurring chromophores or wavelength- specific light absorbing substances that are able to induce certain biochemical reactions at cellular level. Derivatives of naturally occurring chromophores or dyes have been used as photosensitizers to induce biological reactions within tissues for both diagnostic and therapeutic applications. Photochemical interactions include photobiostimulation, photodynamic therapy, and tissue fluorescence. Certain biological pigments, upon absorbing laser light, can fluoresce, which can be used for detecting teeth caries. Lasers can also be used in a non- surgical mode for biostimulation or more rapid wound healing, pain relief, increased collagen growth and a general anti- inflammatory effect. Photodynamic interaction is demonstrated by PAD (Photo-Activated Disinfection) in which a 635nm laser used to activate a dye solution of tolonium chloride placed in a ca rious cavity or root canal. Activation of the tolonium chloride releases oxygen species which disrupt the membranes of micro-organisms found in caries, periodontal pockets and root canals. (2) Photothermal (Photothermolysis): light energy absorbed by the tissues is transformed into heat energy which then produces tissue effects as follows: Coagulation and haemostasis: from 60oC to 70oC, this is the secondary effects through conduction of the heat generated. Photopyrolysis: from 65oC to 90oC, target tissue proteins undergo permanent morphological change (protein denaturation) as result of dissociation of covalent bonds. Photovaporolysis: at 100oC +, inter- and intra-cellular water in soft tissue and interstitial water in hard tissue is vaporised. This destructive phase transfer results in expansive volume change, which can aid the ablative effect of the laser by dissociating large tissue elements. This will be carried onto a further phase: transfer to hydrocarbon gases and production of residual carbon (carbonization).4 The amount of laser energy absorbed by the tissue largely determines the thermal interaction produced and is in turn dependant on the wavelength of the laser light to a great degree, but also on other parameters such as spot size, power density, pulse duration and frequency, and the optical properties and composition of the tissue irradiated. The CO2 (10600nm) is highly absorbed by the water content of oral soft tissues, whereby 90% of the energy is absorbed within the first 100 microns of penetrating the tissue surface5. Hence, even at relatively low power densities using a focused beam, there is rapid tissue vaporization of the water with charring and burning of the organic content of the tissue. Photothermal interaction causes the irradiated target tissue to absorb the laser energy and converts it into heat, thereby producing a direct temperature rise in the irradiated tissue volume. When this energy is applied for long enough, heat conduction will cause a temperature rise in surrounding tissues as well. Hence, thermal effects, such as coagulation necrosis, are produced indirectly in collateral areas and are one of the mechanisms responsible for haemostasis when cutting or vaporizing with a laser. (3) Thermal relaxation Heat dissipation or diffusion from the irradiated tissue site will determine the extent of collateral damage seen and is largely dependant on the thermal conductivity of the tissue. The time required for diffusion of the heat or ‘thermal relaxation time is defined as the time required for the accumulated heat energy within the tissue mass to cool to 37% of its original value6. The degree of heat conduction and rate of tissue cooling both determine the extent of collateral tissue damage for a given wavelength of laser light and tissue type. The composition of the tissue in terms of its structure, water content and vascularity will greatly determine heat conduction/tissue cooling and therefore collateral damage. Moreover, factors such as the volume and surface area of tissue irradiated will also influence the rate of heat dissipation. With continuous laser emission there is no thermal relaxation time, but with pulsed emissions there are brief periods of time allowing for heat dissipation or cooling between pulses7. Tissues should be allowed a period of cooling approximately three times their thermal relaxation time to avoid accumulation of heat energy in surrounding tissue and therefore collateral damage. This can be managed effectively using a combination of appropriate power density and pulse duration for the desired procedure8, 9. Factors that influence thermal relaxation are summarized as follows: Laser absorption characteristics of the target tissue Laser emission mode : continuous wave or pulsed emission Laser incident power Laser power density Beam movement: relative to tissue site; rapid laser beam movement will reduce heat build-up and aid thermal relaxation. Endogenous coolant: water content and vascularity of the tissue. Exogenous coolant: water, air, pre-cooling of tissue.10, 11 (4) Photomechanical and photoelectrical: These are non- thermal interactions produced by high energy, short pulsed laser light, including: photodisruption, photodisassociation, photoplasmolysis and photoacoustic interaction. Absorption of laser energy pulses results in rapid expansion or generation of shock waves that are capable of rupturing intermolecular and atomic bonds (photo-disruption or photodisassociation ). Thus, the laser beams energy is transformed into vibration or kinetic energy. A pulse of laser energy on hard dentinal tissues can produce a shock wave, which might explode or pulverize the tissue, creating an abraded crater. This is an example of the photoacoustic effect of laserlight.12 Photoplasmolysis is a process of tissue removal through the formation of electrically charged ions and particles that exist in‘plasma state, a semi-gaseous, high -energy state which is neither solid, liquid, or gas.13 This process is observed in ultra-short pulsed lasers, e.g. Nd: YAG, Er:YAG, with pulse widths of

The Status of Women in New Testament and Lysistrata :: Lysistrata Essays

The Status of Women in New Testament and Lysistrata Since the beginning of time the treatment of women has improved dramatically. In the earliest of times women were mere slaves to men. Today women are near equals in almost all fields. In 411 B.C., when Lysistrata was written, men had many stunning advantages to that of their female counterparts. Although women's rights between 30 and 100 A.D., the time of the New Testament, were still not what they are today, the treatment of women was far better. Overall, the equality of women in the New Testament exceeds that of the women in Lysistrata in three major ways: physical mobility, society's view of women's nature, and women's public legal rights. Albeit in Lysistrata the women were shown as revolutionaries rising up against the men, women in classical Greece were never like that. Aristophanes created the play as a comedy, showing how the world might be in the times of the Peloponesian war if women tried to do something. It was the women's job to stay home and tend to the house, and never leave, unlike they did in the play, the women were shown as revolutionaries rising up against the men, women in classical Greece were never like that. The activities of women in Classical Athens were confined to "bearing children, spinning and weaving, and maybe managing the domestic arrangements. No wandering in the beautiful streets for them." The suppression of women went so far as to divide the house into separate areas for males and females. While the women stayed home, the men were usually out fighting, and when they weren't fighting, they were entertaining their friends and having sexual favors performed by courtesans. The rights of women in early Christianity were a far cry from today, although they were much better off than their Athenian counterparts. In the Christian church, women were treated as equals. The first evidence of this is when the woman with hemorrhages touches Jesus' clothing and he says that her faith has made her well (Mark 5:34). This shows that both sexes are treated equally in that eyes of god even though at this time the hemorrhages that the

B.F. Skinner

Skinner's theories suggest that all human behaviors result from the conditioning stimuli that operate upon them. As such, human nature has little to do with matters spiritual or moral and more to do with what aspects of character are reinforced by positive stimuli and extinguished by negative stimuli.For example, ‘good' people who have lived with ‘high moral fibre' are those who have been reinforced to do so, and ‘bad' people who have lived with little moral or spiritual regard for others are those who have been reinforced to do so (or conversely, have been negatively reinforced to be concerned with others).(Boeree, 1998) Skinner's view of human nature is considered problematic by most rationalists for the simple fact that it reduces it to a series of conditioned behaviors — an empirically sequenced string of if-then actions — that coldly implies the irrelevance of higher reasoning to explain them. (Boeree, 1998) As such, any moral rationalization of h uman behavior is merely post hoc reasoning. Nonetheless, it is difficult to reconcile Skinner's model of human behavior with determinism. While determinism holds that every event creates a fixed result , Skinner holds that every event (i.  e. human behavior) is maintained only by the properties of a reinforcer (Newall, 2005; Boeree, 2006).This creates a small but significant contradiction because the question of how a reinforcer shapes human behavior becomes moot when said reinforcer is also pre-determined. References Boeree, C. George (1998). B. F. Skinner. Retrieved February 29, 2008, from http://webspace. ship. edu/cgboear/skinner. html Newall, P. (2005) Free Will and Determinism. Retrieved February 29, 2008, from http://www. galilean-library. org/int13. html

Education Disparity Essays

Education Disparity Essays Education Disparity Essay Education Disparity Essay I consider the education the most important thing. This is the inducement of everything. It is the basis, the key of everything what then you can rely on. The inequality in the education was always an issue everywhere in the world, where a minority is exist. Not just in the developing countries, for instance Africa, but in the developed countries too. The lack of good education is I think the first issue facing various societies all over the world.A good education, which is not reached of everyone, provides the children for have good chances in the life, to be successful, to be able to compete in the labor market and to get a good job. Those who do not have the opportunity to learn in the same circumstances, because of the discrimination based on race or financial status, without education they will not be able to cope with the others, so it’s a vicious circle.The state, which not support the social mobility and the government which not make enough effort for the integration can’t be succeed, because I think, the state’s aim is to have well educated, occupied citizens to be able to develop. The state should not grudge the money for these integration programs and for the education, because these educational differences cause mostly the problem between the minority and majority. It’s something which is completely solvable; we just should deal with it. I would like to introduce an example from Hungary. Here, there is a very big gipsy minority which causes a big problem in the country.People just can not keep saying that they do not work, they do not study, they do not pay the taxes. But why they do not work? Why they do not study? May because they do not have the same opportunity to do it, because there are segregated schools and they not treated the same like the others. I was volunteering in one of these segregated schools in Budapest, where just gipsy kids were studying. After school on Fridays I went there and I tutored some of these kids, I helped them to learn reading, counting, I prepared them to a performance. I saw the circumstances where they were learning, their teachers, their parents, their possibilities.If you live in a poor neighborhood, or you are a member of the minority, it’s expected that the school you attend are lacking many necessities. This issue is also in connection with the racism, and I would like to come up with Jane Elliott’s „blue-eyed/brown-eyed experience. If there is an prejudice from the minority, that for instance they do not study and work, after a time they will act according to the prejudice. So if people say that the minority do not want to work and study, and people do not do anything against this (they do not give the opportunity), the minority will accept that situation and they will act like the prejudice.The break-out is very hard, because the parental education and behaviors really affect the children’s future. The disparity is also manifest itself in financial differences. The poverty in many cases also do not have the same opportunities like the others, however they are the same or even more talented. It’s more true about the higher-education, because I think it does not promote social equality as effectively as it should. In many cases there are very talented, enthusiastic students who can not attend in the higher education because of the lack of money.I would pay much more attention to these problems. First of all I would create equality in the education to give the possibilities to everyone. I would invest more money to the education, because in long- term this is the key why a nation can be successful. It’s something which is very profitable, because the education and the economy are strongly connected. Secondly, there should be more programs which promote the social mobility and the talented people. I would expand the economic foundation for the grants and scholarship.

B2B and Reseller Markets Essay

B2B and Reseller Markets Essay B2B and Reseller Markets Essay B2B and Reseller Markets Business-to-business (B2B) concept involves the aspect of decision-making in the majority of industry sectors (Hutt Speh, 2013). The majority of the collaborative business models in the modern times have made an effort to improve the face of marketing through the support of the B2B relationships amongst the entities. The application of the B2B also comes with challenges in the fulfillment of the negotiations and interactions imposed through the collaborative models in managing public business marketing processes (Hutt Speh, 2013). In this research, the description of the use of interaction protocols in defining and managing the processes in B2B relationships forms the core subject. The advancement of technology has enabled businesses conduct marketing electronically facilitating the existence of the Business-to-Business (B2B) E-Commerce (Hutt Speh, 2013). In some of the B2B relationships, the aspect of interaction forms significant challenge. The interactions within the B2B framework occur in three vital layers including content, communication, and business process. Internet-centered B2B related business models are effective in conducting business-to-business (B2B) commerce in the majority of the industry sectors. As one of the instantaneous mediums, the development of technology provides the business entities with new and improvised electronic marketplaces (Hutt Speh, 2013). Business Processes In the layer of business process, the B2B relationships necessitate the management of two distinct business processes including public processes and private processes (Hutt Speh, 2013). The private processes forms part of the enterprise itself managed through each enterprise in an independent way. The private processes receive support within the enterprises through a traditional Workflow Management System, proprietary systems or the ERP systems (Meyer, 2007). The public processes enable the spanning of the organizational boundaries following the involvement with the enterprises involved in the B2B relationship. The processes are under joint management and agreed on by the partners (Meyer, 2007). The activities of the public process have an abstract nature with the support of the private processes. As a clear distinction aid, the public and private processes enable the corresponding organizations abstract the internal process management from the respective management processes across enterprises. The collaborative business models usage have been proposed under several application domains including the supply chain management. The collaborative models have the support of B2B relationship with the inclusion of public business processes jointly managed through partner organizations (Meyer, 2007). Some of the collaborative models necessitate the businesses to establish autonomous B2B with the partners enabling the organizations collaboration. From the perspective of marketing, the collaborative models impose significant challenges in support of the management of the public business processes involved in B2B relationships and they are: Autonomy, the enterprises should have the ability to behave as relative autonomous entities, hiding their internal activities, decisions, and processes (Meyer, 2007). The information system in the management of B2B relationships in the enterprises should have independence. Decentralized management of the corresponding business processes through the enterprises joint management. Peer-to-peer interactions within the enterprises systems for the management of the B2B relationships to imply that the systems interact in a direct means without the independent third party system mediation Negotiation is inclusive in the management of the public processes. Although the proposal of web service composition and workflow approaches still stands in the management of the public processes, there are shortcomings presented in the achievement of autonomy, decentralization, negotiation, and P2P interaction capabilities. B2B Relationships Interaction Protocols The interaction protocols have been in the long run used in the major area of multi-agent systems for the representation of interactions among the involved agents (Hutt Speh, 2013). In B2B context of relationships, interaction protocol enables the management and modeling of the interactions among the involved enterprises in the B2B relationship. The interactions represent the business processes of the public that the enterprises agreed on the aspect of collaboration. Through this means, adapting the concept to the B2B relationships, an interaction protocol enables the description of the high-level communication pattern (Hutt Speh, 2013). This is through the admissible message sequence amid the enterprises playing different roles. The major objective of the interaction protocols is the abstraction of the public processes from specified services involved within the enterprises framework. This is for executing the supported public services internal activities (Hutt Speh, 2013). Within the system, different interaction protocols have one of the highest abstraction levels. An interaction protocol message does not represent the message on the business network. Interaction protocol message in implemented through the application of a lower-level protocol-involving network set of messages (Meyer, 2007). According to B2B three layers application, the interaction protocols transpire in the business process layer with the communication protocols occurring in the layer of communication. The major elements in the interaction protocol include messages, roles, control flows, conditions, deadlines, and logical connectors (Meyer, 2007). The roles are the responsibility in terms of the message sequence the enterprises performs in the B2B relationship. Messages involve the expression of the interactions containing the semantics defining their form. A message can be a representation of the decision, business information, acceptation, acknowledgement, proposal, and rejection. The messages can be of the asynchronous forms or synchronous. Conditions are defined as the messages to represent when messages can be sent (Meyer, 2007). The interaction protocol has two significant control flows. One of the control flows represents messages control flow defining the parallel or the alternative messages of the interaction protocol steps (Meyer, 2007). The second flow is a representation of the internal execution flow of the role describing the different reactions. These are of the roles to the incoming messages. The basic logical connectors are applicable in defining the control flows with deadline defined on the messages that represents time a role sends a message (Hutt Speh, 2013). B2B Standards and Interaction Protocols The B2B standards enable the exchange of messages amongst the enterprises in the B2B relationship. B2B standards are also utilized in the implementation and the exchange of messages defining interaction protocols (Kurtz, 2014). The enterprises should consider an agreement on the B2B standard to be applicable in exchanging the interaction messages. This is to enable the enterprises implement different and independent systems for the joint execution of similar interaction protocols (Kurtz, 2014). This is without the application of the proprietary communication protocol at a lower level. The B2B standards are large in number and consist of the following specification elements: A machine-process able definition language for defining the public processes An exchange sequence defining the transactions possible as required through every message and the constraints of the specified message, performance and like time-outs The business documents structure involved in the content of the message The form in which the messages are packaged and transported on the corresponding networks through specified communication protocols including SMTP and HTTP Messages Security Mechanisms All the B2B standard elements necessitate the implementation of the interaction protocols. Some of the standards specify only the elements defining the business documents (Pride et al, 2007). The rest of the B2B standards enable the specification of the required elements. The implementation of a message using the B2B standards enables each of the interaction protocol messages to consist of more messages. The transaction messages enable the keeping of the message as a unit through the application of responses. In the business transactions, one of the roles performs the requesting of the specified activity with the other one performing the responding activity (Pride Ferrell, 2007). The B2B relationships are under the management of public and private entities with an explicit separation between the private and public processes managed in an independent means (Pride Ferrell, 2007). The modeling of the public business process through an interaction protocol of the B2B relationships focuses on the messages enterprises exchanges for interaction and message orchestration. The interaction protocols facilitates greater enterprise autonomy in marketing framework since the enterprises hides internal activities, decisions and services necessitated for supporting public processes (Pride Ferrell, 2007). Public Business Processes Modeling with Interaction Protocols In the B2B perspective of modeling interaction protocols, the two languages necessary includes the textual modeling language and the graphical language modeling (Villarreal et al, 2003). The former provides the intuitive semantics that enables the business marketing process designers understand and define the public process for interaction representation between partners. The second language enables the enterprises exchange the interaction protocol descriptions. They can be understood and process able through the information system of the B2B relationships for the interaction protocol execution (Villarreal, Salomone, and Chiotti, 2003). The major difference that exists between the interaction protocols and the other approaches for public processes modeling is the interaction protocols not defining the services or activities (Kurtz, 2014). The modeling of the process with the aspect of the interaction protocols draws the focus on the messages sent and received through the roles of the enterprise in every step of the process. For exemplifying the interaction protocol modeling, capacity planning and collaborative planning processes are defined through a partner-partner collaborative model. The collaborative model carries out the business process amongst the enterprises manufacturing belonging to different chains of supply in the market (Kurtz, 2014). The model has a public business process carried out jointly by partners in a decentralized procedure. The collaborative model necessitates the enterprise establishment of an independent B2B relationship with the partners (Kurtz, 2014). Conclusion Interaction protocols in the B2B relationships perspective enable the management and modeling of public business processes consideration through autonomous and heterogeneous partners. This is for the relative achievement of B2B relationships goals. The protocols provide an abstraction framework level for modeling interactions that represents public processes. With the models of the B2B relationships, the messages exchanged by the corresponding enterprises are significant. The protocols of B2B also enable the implementation of interaction protocol for marketing systems fulfilling the collaborative business models requirements. IMP communicative acts facilitate the definition of the B2B relationship interaction protocols without the consideration of the B2B standards applicable in the implementation process. Achieving the independence between the B2B standards and interaction protocols is possible. The independence provides several of the benefits to the business marketing practice. The enterprises have the ability to carry out implementation programs of the interaction protocol with their networks with different partners using B2N standards of different versions. The communicative acts also enable the B2B standards joint functionality for the provision of advanced solutions to the B2B environments. This enables the marketing enterprise systems supporting the B2B relationships to facilitate the understanding of same interaction protocol independent of the technologies used in building them. Visit our online essay writing service to get professional writing help from academic experts who are hired to produce high-quality custom essays from scratch!

Choose your own Coursework Example | Topics and Well Written Essays - 1000 words

Choose your own - Coursework Example People moving up and down and deliveries taking place, that would later work against us. The assignment given to us humiliated my comrade, Benson, and he questioned the mission as we boarded the cargo ship. I was very attentive and picked every step since I could be cannon-folder in no time. It was difficult making my way out into the yard using the walls for cover. I had lost all hope and my dignity was at an all-time low. Benson had talked, complained and was tired; it was time for him to see things develop without commenting or uttering any word. It was time to move out and carry our heavy guns on our shoulders. This is an experience that I could not believe to be going through in real life. The gun-strap was heavy, but I was optimistic about getting relieved once I started using it eventually. From my standpoint, I could see two guards standing at ease under a swathe of lamplight, and they were very tired calling for a reprieve on deaf ears. Sadly, these soldiers dropped down and cried as they hit the floor. I developed sympathetic feelings towards them and concluded they did so because of humanity. I was traumatized by the activities going on at the port and knew that one day, I would be dead, and my family back home will never hear any more from me. My ears were filled with the noise and sounds of the port; I become paranoid forcing me to hide behind a huge iron door for my security. I started feeling lonely since I could no longer see Benson, the only person I banked on for my strength and survival. The death of our people and opponents was rising and the developments thrilled me. The initiation of weapons of mass destruction was a loss to humanity since people were claiming their fellow human beings. â€Å"What a terrible day,† I cast the day because I never expected to see the entire taking place. It was frightening, and I was in solidarity with my fellow men. Although I had my gun with me, a gun given without my consent, it was impossible using it

'In company reporting, the measurement of the amount of impairment of Essay - 1

'In company reporting, the measurement of the amount of impairment of many types of assets is so subjective as to be meaningless - Essay Example Some assets can't be reported simply, so the subjectivity arises from the choice of impairment modeling and accounting presentation: Like trying to map a 3-dimensional sphere on a 2-dimensional plane, inevitable distortions crop up no matter what approach one takes to presenting the data. Yet other assets, while objectively declining in value, do so at a rate that is impossible to determine, so any presentation is subjective because it is a choice as to what data to include and what not to, what prediction to make. Yet even this incomplete, subjective picture is far from meaningless for investors, auditors and stakeholders. Asset impairment is defined as, â€Å"An unexpected or sudden decline in the service utility of a capital asset, such as a factory, property or vehicle. This could be the result of physical damage to the asset, obsolescence due to technological innovation, or changes to the legal code. Impairments can be written off† (InvestorWords, 2011). Assets can declin e for a variety of reasons. Simple wear and tear can make an asset less than its expected new or even used value: For example, a vehicle that operated in difficult conditions such as snow or sand could be below the expected market value for a vehicle of that age. In this sense, asset depreciation is a subset of asset impairment. But this determination can be subjective: It requires guessing the cost of the additional damage which could vary from potential buyer to potential buyer. Technological innovation can make some objects obsolete: Certainly, computers have obsolescence and an incredibly high rate of turnover. But anticipating that requires expecting Moore's Law to continue operating, as well as treating the computer as a unified asset, yet different parts of the computer depreciate at different rates and accounting standards are always changing to reflect that for different electronics (Ward, 2011). A legal change could make a piece of machinery become illegal in a particular country, but then the asset could be sold elsewhere, which could require a degree of subjective currency anticipation and assessment of liquidation risk and benefit. This is why goodwill is recognized as the standard for impairment of many assets, and it is commonly accepted that there is a great degree of subjectivity in making this determination. â€Å"We are facing a new era of economic development with a growing significance of intangible assets. Goodwill constitutes a significant asset for numerous companies, especially those which are operating in high technology industries. According to the growing importance of intangibles there has also been a significant change in standards associated with accounting for goodwill† (Jerman and Manzin, 2006). In particular, using fair value accounting for goodwill and for determining the need for disclosures leads to inherent subjectivity: â€Å"The fair value may be determined by using different approaches such as using available ma rket prices, present value techniques, prices for similar assets and other valuation techniques. Users of financial information should consider that market values are not always on disposal. Consequently fair value estimates are based on subjective judgment† (Jerman and Manzin, 2006, 222-223). One of the reasons why there is so much subjectivity is because investors rightly demand disclosures of