By T. Yussuf. The Richard Stockton College of New Jersey.

However order provera online pills pregnancy test calculator, it is emphasized that the use of a Craig plot does not guarantee that the resultant analogues will be more active than the lead because the parameters used may not be relevant to the mechanism by which the analogue acts buy provera 5mg amex pregnancy 25 weeks. It is emphasized that only some of the compounds will be more active than the lead compound. The method is most useful when it is not possible to make the large number of compounds necessary to produce an accurate Hansch equation. However, its use is limited because it requires the lead compound to have an unfused aromatic ring system and it only produces analogues that are substituents of that aromatic system. In addition, the Topliss method also depends on the user being able to rapidly measure the biological activity of the lead compound and its analogues. In both cases the investigation starts with the conversion of the lead into the first analogue at the top of the tree, either the 4-chloro analogue (Figure 4. The activity of this analogue is measured and classified as either less (L), approximately the same (E) or significantly greater (M) than that of the original lead. If the activity is greater than that of the lead the next analogue to be prepared is the next one on the M route. Alternatively, if the activity of the analogue is less than that of the original lead the next step is to produce the analogue indicated by the L route on the tree. Utilisation of Operational Schemes for Analog Synthesis in Drug Design by J G Topliss is followed and the appropriate analogue synthesized. This procedure is repeated, the activity of each new analogue being compared with that of its precursor in order to determine which branch of the tree gives the next ana- logue. It should be realized that only some of the compounds synthesized will be more potent than the original lead A S. The first step in the Topliss approach is to synthesize the 4-chloro derivative (B) of A. Suppose the activity of B is greater than that of A, then following the M branch the Topliss tree (Figure 4. In this case, the Topliss tree shows that the next most promising analogue is the 4-trifluromethyl derivative of (D) of A. At this point one would also synthesize and biologically test the 2,4-dichloro (E) and the 4-nitro analogues (F) of A. It is emphasized that the decision tree is not a synthetic pathway for the production of each of the analogues. It simply suggests which of the substituents would be likely to yield a more potent analogue. The synthetic route for producing each of the suggested analogues would vary for each analogue and would use the most appropriate starting materials. The Topliss decision tree does not give all the possible analogues but it is likely that a number of the most active analogues will be found by this method. Illustrate the answer by reference to the changes in the activities of 4-alkylresorcinols caused by changes in the chain length of the 4-alkyl group. Assume that these groups are introduced into the section of the lead’s structure that does not contain its pharmacophore. These equations are obtained using so called ‘models’ of the system being studied (see sections 5. The reliability of the mathematical methods used to obtain and solve the equations is well known and so in most cases it is possible to obtain a reliable estimate of the accuracy of the results. In some cases the calculated values are believed to be more accurate than the experimentally determined figures because of the higher degree of experimental error in the experimental work. Graphics packages that convert the data for the structure of a chemical species into a variety of easy to understand visual formats have also been developed (Figure 5. Consequently, in medicinal chemistry, it is now possible to visualize the three dimensional shapes of both the ligands and their target sites. In addition, sophisticated computational chemistry packages also allow the medicinal chemist to evaluate the interactions between a compound and its target site before synthesizing that compound (see section 5. This means that the medicinal chemist need only synthesize and test the most promising of the compounds, which considerably increases the chances of discovering a potent drug. Molecular modelling is a complex subject and it is not possible to cover it in depth in this text. For workers wishing to use it as a tool in drug design it will be necessary to either ask a competent computational chemist to make the necessary calculations and graphic conversions or to treat the computer as a black box and use the relevant computer program according to its manufacturer’s instructions. The most common com- putational methods are based on either molecular or quantum mechanics. In these equations the positions of the atoms in the structure are represented by either Cartesian or polar coordinates (Figure 5. In the past, the initial values of these atomic coordinates were set by the modeller. However, as it is now customary to construct models from existing structural fragments (see section 5. Once the energy equation is established, the computer computes the set of coordinates which correspond to a minimum total energy value for the system. This set of coordinates is converted into the required visual display by the graphics package (Figure 5. However, although the calculations made by computers are always accurate, the calculated result should be checked for accuracy against experimental observations. In this respect it is essential that the approximations on which the calculations are based are understood. For example, most calculations are based on a frozen molecule at 0 K in a vacuum and so do not take into account that the structure is vibrating or the influence of the medium in which the chemical species is found. Calculations taking these factors into account would undoubtedly give a more realistic picture of the structure. Quantum mechanics calculations are more expensive to carry out because they require considerable more computing power and time than molecular mechanics calculations. Consequently, molecular mechanics is the more useful source of the large structures of interest to the medicinal chemist and so this chapter will concentrate on this method. To save time and expense, structures are often built up using information obtained from databases, such as the Cambridge and Brookhaven databases. Information from databases may also be used to check the accuracy of the modelling technique. However, in all cases, the accuracy of the structures obtained will depend on the accuracy of the data used in their determination. Furthermore, it must be appreciated that the molecular models produced by computers are a caricature of reality that simply provide us with a useful picture for design and communication purposes. It is important to realize that we still do not know what molecules actually look like! Ribbon representations are usually used to depict large molecules, such as nucleic acids and proteins.

Nurses seek validation of the patients’ problems with the patients or support persons buy 2.5 mg provera overnight delivery breast cancer tattoos designs. The nurses then propose hypotheses about the problems and the solutions order provera now menstrual xex, such as: Eight glasses of water a day will improve bowel evacuation. Interventions are designed based on the conservation principles: conservation of energy, structural integrity, per- son integrity, and social integrity. The expectation is that this approach will maintain wholeness and promote adaptation. The outcome of hypothesis testing is evaluated by assessing for organismic response that means the hypotheses are supported or not supported. Consequences of care are either therapeutic or supportive: therapeutic measures improve the sense of well-being; supportive measures pro- vide comfort when the downward course of illness cannot be influenced. If the hypotheses are not supported, the plan is revised and new hypotheses are proposed. The scientific process is used to make observations and select relevant data to form hypothetical statements about the patients’ predica- ments (Schaefer, 1991a). These decisions are not the role pletely to every alteration in his or her life of the health-care providers or families (Levine, pattern. Atheoryofnursing must recognize 6 “Persons who require the intensive inter- the importance of unique detail of care for a ventions of critical care units enter with a con- single patient within an empiric framework tract of trust. The model’s universality is supported by the 8 The nurse is responsible for recognizing the model’s use in a variety of situations and patients’ state of altered health and the patient’s organis- conditions across the life span. Swavely, Rothenberger, Hess, & Willistin, 1996), emergency room (Pond & Taney, 1991), primary Values care (Pond, 1991), in the operating room (Crawford-Gamble, 1986), long-term/extended 1 All nursing actions are moral actions. This model has been used with a variety of pa- 3 Ethical behavior “is the day-to-day expres- tients across the life span, including the neonate sion of one’s commitment to other persons and (Mefford, 1999; Tribotti, 1990), infant (Newport, the ways in which human beings relate to one 1984; Savage & Culbert, 1989), young child (Dever, another in their daily interactions” (Levine, 1991), pregnant woman (Roberts, Fleming, & 1977, p. Clark (1992) provides examples of the use of tients (Cox, 1991; Foreman, 1991, 1996; Hirschfeld, the conservation principles with the individual, 1976), including the frail elderly patient (Happ, family, and community as a testament to the personal communication, January 31, 1995; model’s flexibility/universality. The approach to community begins with the The model has been used as a framework for collection of facts and a thorough community as- wound care (Cooper, 1990), managing respiratory sessment (provocative facts). The internal environ- illness (Dow & Mest, 1997; Roberts, Brittin, Cook, ment assessment directs the nurse to examine the & deClifford, 1994), managing sleep in the patient patterns of health and disease among the people of with a myocardial infarction (Littrell & Schumann, the community and their use of programs available 1989), developing nursing diagnoses (MacLean, to promote a healthy community. The assessment 1989; Taylor, 1989), practicing enterostomal ther- of the external environment directs the nurse to ex- apy (Neswick, 1997), assessing for changes in amine the perceptual, operational, and conceptual bladder function in posthysterectomy women levels of the environment in which the people live. It has also been used for devel- The perceptual environment incorporates those oping plans of care for women with chronic illness factors that are processed by the senses. On a com- (Schaefer, 2002), care of intravenous sites (Dibble, munity basis these factors might include an assess- Bostrom-Ezrati, & Rizzuto, 1991), skin care (Burd ment of: et al. The operational environment would encourage Current work on the model is in process in the a more detailed assessment of the factors in the en- areas of community health. The following is a brief vironment that affect the individual’s health but are summary of beginning clarification of the model’s not perceived by the people. This discussion focuses on ment on the ethnic and cultural patterns in the community-based care using Levine’s Conserva- community. An assessment of types of houses of tion Model to provide a foundation for the future worship and health-care settings might be included. Using Levine’s Conservation Model, conservation principles to guide continued assess- community was initially defined as “a group of peo- ment to assure a thorough understanding of the ple living together within a larger society, sharing community. Levine (1973) maintained that research Assessment of personal integrity might include: is critical to the development of a scientifically 1. Political environment to nursing that is scientific, research oriented, and universal in practice. She said that research should Assessment of the social integrity might include: focus on the maintenance of wholeness and the in- 1. Opportunities for employment purpose of discovery, and contrary to the notion of Table 9–2 Levine’s Conservation Model—Nursing Process in the Community Process Application of the Process Assessment Collection of provocative facts through observation and interview. The nurse uses observation, review of census data, statistics, data from community member inter- views, and so on to collect provocative facts about the community. Use of windshield assessments or other formally developed community assessments are helpful in the collection of data. Hypotheses Directs the nurse to provide interventions that will promote adaptation and maintain wholeness of the community. In discussion with the community members, the nurse validates her judgments about the community’s predicament. The nurse then proposes hypotheses about the problems and solu- tions, such as: Providing shelter to abused women will reduce the morbidity associated with continuous uninterrupted abuse. The nurses select the most appropri- ate solutions with the help of the community members. Interventions are based on the con- servation principles of energy, structural integrity, personal integrity, and social integrity. The shelter for abused women provides for structural integrity of the community while preserving the energy, personal, and social integrity of the women who choose shelter. The outcome of hypothesis testing is evaluated by assessing for organismic response. For example, an expected outcome of shelters for abused women might be a reduction in emer- gency room visits for injury resulting from suspected abuse or an increase in the number of women who are able to remove themselves from an abusive relationship. Conservation of energy can be maintained by servation, whereas Roberts, Fleming, and (Yeates) placing the infant skin to skin on the mother’s Giese (1991) focused on energy conservation and chest, covered with a warm blanket (Newport, structural integrity. Ludington (1990) found that simple skin-to- framework and consider how the findings support skin contact was effective in reducing activity the goal of promoting adaptation and maintaining and state-related energy expenditure in the new- wholeness. There is no significant difference in energy description, both qualitative and quantitative ap- expenditure between basin, tub, or shower proaches are appropriate to develop the model and bathing 5 to 17 days postmyocardial infarction theories derived from the model. The differ- approach helps to explain how the patient experi- ences that did exist were related more to subject ences the challenges to their internal and external variability than the type of bathing. The quantitative approach helps to mental group had significantly lower oxygen test the relationships between the variables, and, in consumption than did the control group. These predictive models help clinicians alter the perature on the first and third postoperative days environments to promote adaptation and maintain best predicts delirious patients (Foreman, 1989). Acutely confused patients were differentiated Combining qualitative and quantitative (mixed best from those not confused by 10 variables methods) approaches to the study concepts using representing all four conservation principles. Interactions with patients are both in ventilator patients 100 percent of the time predictive and creative. Qualitative research helps and that fatigue and depression were signifi- to provide a way for the nurses to repeatedly share cantly correlated. Qualitative data turbances were present and nutrition was helps to explain the quantitative data and provides compromised, there were no significant rela- a more holistic perspective regarding the data expe- tionships with fatigue. Schaefer’s (1991b; Schaefer & Shober-Potylycki, Several investigators have contributed signifi- 1993) research supports the finding that the ex- cant research to the support and expansion of the perience of fatigue in congestive heart failure is Conservation Model as a model for nursing prac- an experience that affects one’s whole sense of tice. Following is a summary of promotion for preterm infants derived from several of the conclusions of research using the Levine’s Conservation Model. Although the proposed models as, and resulted in less perineal damage than, were not supported, findings revealed that an in- sustained breath holding during the second crease in the level of consistency of nursing care- stage of labor (Yeates & Roberts, 1984). There giving decreased the age at which health was were no differences in the mean duration of the achieved, and an increase in the level of consis- second stage of labor between the two groups.

All Chinese patent medicines of the same name have the same proportions of ingredients buy provera from india breast cancer of america. A medicine known as ‘four gentleman decoction’ (si jun zi tang) is an example of such a product buy provera 2.5 mg with visa menopause last period. The formula comprises: • Main herb: Radix panax ginseng (ren shen), to enhance spleen qi • Associate: Rhizoma atractylodis macrocephalae (bai zhu), to strengthen the spleen and dry off the ‘dampness’ • Adjuvant: Sclerotium poriae cocos (fu ling), to assist the main and associate herbs • Guide: Radix glycyrrhizae uralensis (zhi gan cao), to harmonise the other three herbs and regulate spleen qi. Under the Drug Administration Act 2001 post-marketing surveillance of adverse drug reactions is mandatory in China. Whenever an adverse reaction event occurs, the manufacturer, the medical institutions and the seller are obliged to report it. The main legislation requires that medicines placed on the market must have a licence, which requires meeting standards of safety, quality and efficacy. These licensing conditions pose inappropriate demands on most herbal medicines, because plants are chemically complex and variable, active constituents are not always known and the huge costs cannot be recouped through patenting. Under the 1968 Act, herbal remedies are exempt from the licensing requirement if either the herbal remedy is made up on the premises from which it is supplied, after a one-to-one consultation (Section 6. These exemptions only apply to plant remedies, so medicines containing non-plant ingredients require a medicine licence. In recent years these provisions, which provide no specific regulation for herbal medicines, have been considered inadequate to ensure their safety and quality. There are a number of reasons including: adverse effects from some herbal ingredients (natural does not mean safe); misidentification of some Figure 6. Traditional Chinese medicine | 159 herbs and occasional substitution of toxic for safe species; illegal inclusion of prescription-only drugs or heavy metals in some ‘herbal’ medicines; microbial contamination; and discovery of problematic herb–drug interactions. This establishes a registration scheme for industrially produced over-the-counter herbal medicines, under which manufacturers have to demonstrate safety and quality, but not efficacy. Quality is guided by European good manufacturing practice, and safety is protected by requiring evidence of at least 30 years of safe use, of which at least 15 years must be within the European Community. There is a lead-in time to allow manufacturers and suppliers to make the necessary adjustments, but after 2011 any over-the-counter herbal product that is not registered under this scheme will be illegal. This lead time is, however, only for products that were on the market before April 2004. Such medicines will not have to be licensed and, because they are not industrially produced, will not have to be registered under the European Directive. There are, however, concerns about the quality and safety of herbal medicines supplied by this route. The issue is how to strengthen the public’s protection while preserving their access to herbal medicines. First, members of the statutory register can be tied, through a codes of practice, to suppliers that have been audited and demonstrated satisfactory standards of quality assurance. The Register of Chinese Herbal 160 | Traditional medicine Medicine has provided a good model for such an arrangement through its Approved Suppliers scheme. As it will be illegal to practise under the title of herbalist or Chinese medicine practitioner without membership of the register, the public will have stronger assurance about the quality of Section 6. Second, some more potent items in the materia medica can be restricted to use by registered practitioners. These are unlicensed medicines that would be considered industrially produced and thus, once the European directive is in force, would have to be registered under that scheme in order to remain legal. However, it seems likely that most of these patents would be considered unsuitable for registration under the European directive, because even if they met the tough quality assurance standards, most would not be suitable for over-the-counter use. On the other hand, they are industrially produced, so they could not be supplied under the normal Section 6. One way in which access might be preserved is through the so-called ‘Specials’ regimen, a provision in European medicines law that allows authorised health professionals to commission a third party (who would have to possess a manufacturer’s license) to make up medicines according to a particular specification. As registered herbalists would be authorised health professionals, it would in principle be possible for herbalists to commission a range of products for the exclusive use of practitioners on the statutory register. Under the new specials regimen, it is the practitioner who would be responsible for the formulation of any herbal patent medicine. Suppliers would not be able to advertise their products but would be able to advertise that they are able to provide a service. Although there have been no prosecutions to date arising specifically from the use of non-plant ingredients – hence the Traditional Chinese medicine | 161 law has never been tested in the courts – the wider concerns about the lack of regulation of herbal medicines have put this issue in the spotlight and it is clearly desirable to put this part of the materia medica onto a secure legal footing. The herbal community is therefore pressing for an extension of the licensing exemptions to non-plant medicines. It is suggested that, although the research is of variable quality, it should not be ignored. Adverse events, tolerability, and haemato- logical and biochemical parameters were monitored during the study. Treatment of side effects associated with chemotherapy treatment Short-term side effects of chemotherapy include fatigue, nausea, vomiting, mucositis, and myelosuppression or neutropenia. These occur during the course of treatment and generally resolve within months of completion of 162 | Traditional medicine chemotherapy. A variety of Chinese medicinal herbs has been used for managing these side effects. This has led to problems, because most of those who seek treatment are unable to distinguish between adequately and inadequately trained practitioners. Practitioners fall into three broad categories: • Those who have had a full training in the discipline This may be practitioners who have trained in China, normally for 5 years. Fully trained practitioners have training similar to that given to orthodox doctors in the west. They receive some training in western medicine and can distinguish those conditions that would be best treated by western medicine. These medicines carry with them a risk of adverse reactions; the risk needs to be quantified and as far as possible minimised. They should not take them if they are not labelled and [do not] include a list of ingredients in English. Even then, clear labelling is not in itself a guarantee of good quality standards. These companies import herbs from the People’s Republic of China either directly or through dealers in Hong Kong. The quality of imported herbs varies considerably, and great skill is needed to ensure that the correct herbs are provided to the practitioner. Some substitution of herbs is acceptable in China but can lead to problems if the wholesaler or practi- tioner is unaware of the substitution (see below). Confusion may arise over the precise identity of the herb being ordered; no standardised nomenclature exists for herbs.

Newell and Simon suggested that problem solving involves a number of stages that result in a solution to any given problem order 5mg provera with visa women's health big book of exercises uk. This model has been applied to many different forms of problem solving and is a useful framework for examining clinical decisions (see Figure 4 5 mg provera womens health zone link health. The stages involved are as follows: 1 Understand the nature of the problem and develop an internal representation. At this stage, the individual needs to formulate an internal representation of the problem. This process involves understanding the goal of the problem, evaluating any given conditions and assessing the nature of the available data. Newell and Simon differentiated between two types of plans: heuristics and algorithms. An algorithm is a set of rules that will provide a correct solution if applied correctly (e. However, most human problem solving involves heuristics, which are rules of thumb. Heuristics may involve developing parallels between the present problem and previous similar ones. The individual then decides whether the heuristics have been successful in the attempt to solve the given problem. If they are considered unsuccessful, the individual may need to develop a new approach to the problem. The end-point of the problem-solving process involves the individual deciding that an acceptable solution to the problem has been reached and that this solution provides a suitable outcome. According to Newell and Simon’s model of problem solving, hypotheses about the causes and solutions to the problem are developed very early on in the process. They regarded this process as dynamic and ever-changing and suggested that at each stage of the process the individual applies a ‘means end analysis’, whereby they assess the value of the hypothesis, which is either accepted or rejected according to the evidence. This type of model involves information processing whereby the individual develops hypotheses to convert an open problem, which may be unmanageable with no obvious end-point, to one which can be closed and tested by a series of hypotheses. Models of problem solving have been applied to clinical decision making by several authors (e. MacWhinney 1973; Weinman 1987), who have argued that the process of formulating a clinical decision involves the following stages (see Figure 4. The initial questions in any consultation from health professional to the patient will enable the health professional to understand the nature of the problem and to form an internal repre- sentation of the type of problem. Early on in the problem-solving process, the health professional develops hypotheses about the possible causes and solutions to the problem. The health professional then proceeds to test the hypotheses by searching for factors either to confirm or to refute their hypotheses. Research into the hypothesis testing process has indicated that although doctors aim to either confirm or refute their hypothesis by asking balanced questions, most of their questioning is biased towards confirmation of their original hypothesis. Therefore, an initial hypothesis that a patient has a psychological problem may cause the doctor to focus on the patient’s psychological state and ignore the patient’s attempt to talk about their physical symptoms. Furthermore, the type of hypothesis has been shown to bias the collection and interpretation of any information received during the consultation (Wason 1974). The outcome of the clinical decision-making process involves the health professional deciding on the way forward. Weinman (1987) suggested that it is important to realize that the outcome of a consultation and a diagnosis is not an absolute entity, but is itself a hypothesis and an informed guess that will be either confirmed or refuted by future events. Explaining variability Variability in the behaviour of health professionals can therefore be understood in terms of the processes involved in clinical decisions. For example, health professionals may: s access different information about the patient’s symptoms; s develop different hypotheses; s access different attributes either to confirm or to refute their hypotheses; s have differing degrees of a bias towards confirmation; s consequently reach different management decisions. Explaining variability – the role of health professionals’ health beliefs The hypothesis testing model of clinical decision making provides some understanding of the possible causes of variability in health professional behaviour. Perhaps the most important stage in the model that may lead to variability is the development of the original hypothesis. Health professionals are usually described as having professional beliefs, which are often assumed to be consistent and predictable. However, the development of the original hypothesis involves the health professional’s own health beliefs, which may vary as much as those of the patient. Components of models such as the health belief model, the protection motivation theory and attribution theory have been developed to examine health professionals’ beliefs. The beliefs involved in making the original hypothesis can be categorized as follows: 1 The health professional’s own beliefs about the nature of clinical problems. For example, if a health professional believes that health and illness are determined by biomedical factors (e. However, a health professional who views health and illness as relating to psychosocial factors may develop hypotheses reflecting this perspective (e. Health professionals will have pre-existing beliefs about the prevalence and incidence of any given health problem that will influence the process of developing a hypothesis. For example, some doctors may regard childhood asthma as a common complaint and hypothesize that a child presenting with a cough has asthma, whereas others may believe that childhood asthma is rare and so will not consider this hypothesis. Weinman (1987) argued that health professionals are motivated to consider the ‘pay-off’ involved in reaching a correct diagnosis and that this will influence their choice of hypothesis. He suggested that this pay-off is related to their beliefs about the seriousness and treatability of an illness. For example, a child presenting with abdominal pain may result in an original hypothesis of appendicitis as this is both a serious and treatable condition, and the benefits of arriving at the correct diagnosis for this condition far outweigh the costs involved (such as time-wasting) if this hypothesis is refuted. Marteau and Baum (1984) have argued that health professionals vary in their perceptions of the serious- ness of diabetes and that these beliefs will influence their recommendations for treatment. Brewin (1984) carried out a study looking at the relationship between medical students’ perceptions of the controllability of a patient’s life events and the hypothetical prescription of antidepressants. The results showed that the students reported variability in their beliefs about the controllability of life events; if the patient was seen not to be in control (i. This suggests that not only do health professionals report inconsistency and variability in their beliefs, this variability may be translated into variability in their behaviour. The original hypothesis will also be related to the health professional’s existing knowledge of the patient. Such factors may include the patient’s medical history, knowledge about their psychological state, an under- standing of their psychosocial environment and a belief about why the patient uses the medical services. Stereotypes are sometimes seen as problematic and as confounding the decision-making process. However, most meet- ings between health professionals and patients are time-limited and consequently stereotypes play a central role in developing and testing a hypothesis and reaching a management decision. Stereotypes reflect the process of ‘cognitive economy’ and may be developed according to a multitude of factors such as how the patient looks/talks/ walks or whether they remind the health professional of previous patients.

Original flms should always be acquired and examined since duplicate flms are very ofen incorrectly oriented (see Chapter 10) order discount provera online menstrual art. Even if fve restorations are consistent among the ante- mortem and postmortem records buy provera 5 mg menstrual cramps 8 months pregnant, signifcant doubt must be raised if one unexplained exclusionary item is noted. For example, if the antemortem records show a full crown on a certain tooth and the postmortem record shows an occlusal amalgam on the same tooth, the comparison results in exclusion. Once a body is released, it may be buried or cremated before discovery that a record is inadequate or an image is substandard. Te accurate reconstruction of the antemortem record is an equally important phase of the identifcation process. With careful attention to detail, dental identifcations can be completed in a relatively short time period and at a reasonable cost when compared to other means of identifca- tion. In some instances, the forensic dentist may fnd it useful to consider the new technologies available to assist in the comparison process. With advances in this and other forensic identifcation sciences, new methods will become more commonplace. Trough the cooperative eforts of medical examiners, coroners, law enforcement ofcials, and forensic odontologists, dental com- parisons can be efciently and accurately completed to identify or exclude. Uses and disclosures for which consent, an authori- zation, or opportunity to agree or object is not required, uses and disclosures about decedents. Paper presented at American Academy of Forensic Sciences, Annual Meeting, F7, New Orleans. Paper presented at American Academy of Forensic Sciences, Annual Meeting, F6, Seattle. Te diversity of adult dental patterns in the United States and the implications for personal identifcation. Establishing personal identifcation based on specifc patterns of missing, flled, and unrestored teeth. Computer-aided dental identifcation: An objective method for assessment of radiographic image similarity. Detection and classifcation of composite resins in incinerated teeth for forensic purposes. Identifcation through x-ray fuorescence analysis of dental restorative resin materials: A comprehensive study of noncremated, cremated, and processed-cremated individuals. Identifcation of incinerated root canal flling materials afer exposure to high heat incineration. In fact, research and development spanning from 1831 until 1895 incrementally led to his discovery. Tis included work by Faraday, Geissler, and Hittof in creating and developing the frst high-tension electrical evacu- ated tubes, which produced what were named cathode rays within the device. Te cathode rays produced a spark caused by a stream of high-speed electrons traversing a small gap and striking a metal target. Tis work was followed by Sir William Crookes and Professor Heinrich Hertz, who demonstrated that 187 188 Forensic dentistry cathode rays produced forescence and heat within and without the tube. However, Röentgen did, in fact, discover that other invisible rays emanating from the device possessed the ability to penetrate solid objects and produce photographic shadows of fesh and bones. When there is a confict between the written dental record and antemortem radiographs of a subject, deference is given to the radiographs as the gold standard having less potential for human error than charted dental information. Tis chapter on the basic theory of dental radiography is presented at a level such that the principles pertinent to the topics and themes most important to forensic dental investi- gations are emphasized. Tus, electrical energy is converted to kinetic energy, which is then converted to electromagnetic energy. Only 1% or less of the bombarding electron energy is converted into x-radiation, with the remaining energy resulting in a very large gain of heat, which is the greatest cause of tube failure. Tis fact accounts for the absolute need to follow the manufacturer’s recommended duty cycle by waiting the specifed amount of time between exposures. Te setting of a mass disaster morgue is more likely to destroy a tube head than working on typical dental patients, where the time for placing flms afer each exposure helps protect the duty cycle. Te resulting x-ray beam is comprised of millions of photons of vary- ing energy (wavelengths) and is referred to as having a continuous or poly- chromatic spectrum. Older x-ray units produce even more variation in the uniformity of the beam as the alternating current rises and falls. Tese units are more ef- cient and provide more high-energy, diagnostically useful photons and cut exposure times roughly in half. Older units also have difculty in producing the extremely short exposure times (usually tenths of a second) required by digital x-ray sensors, which require signifcantly less radiation than flm. One very simple but efective method to accomplish this is to cover the opening of the tube head collimator in an old unit with round sections of rare earth screen material until the beam is weakened sufciently to allow longer expo- sure settings comparable to the unit’s timer capabilities. Terefore, there is always a varying amount of magnifcation of the object in any plane flm image. Te degree of magnifcation is determined by the ratio of the x-ray source-to-object distance and source-to-flm distance. Te larger the distance from the source to the image receptor, the less magnifcation occurs. Likewise, the closer the object to the receptor, the less the magnif- cation and the sharper the image will be. Tat is because the energy of the quickly diverging beam will weaken mathematically as a square of its distance. Terefore, changing the distance of an individual to the x-ray source from 1 foot to 4 feet reduces the dose or intensity of the radiation to 1/16th of the original dose. New technology in the form of handheld generators that are truly pow- ered by direct current from rechargeable batteries is now in great use in forensic dentistry (Aribex™ Nomad™) but will be discussed further later in this chapter and in other chapters in this textbook. Terefore, the total of the external and internal structures of the object is represented in the image and not simply the surface area. Tis is signifcant in that a radiographic image reveals objects that cannot be per- ceived with the naked eye. Tis also means, however, that dental radiographic images require interpretation by the observer because the image is presented as a two-dimensional representation of a three-dimensional object. Radiographic images of the teeth and maxillofacial structures can only be created due to the fact that the beam of electromagnetic energy is attenu- ated in varying degrees, depending on the absorption characteristics of dif- ferent structures through which it passes, and that recording media will react diferently depending on the energy received. Tus, an amalgam restoration 190 Forensic dentistry absorbs much more energy than its surrounding enamel and dentin, allow- ing less energy to reach the receptor at that location and creating an invisible latent image. Trough some mode of processing of the receptor, the amalgam will later be displayed in an image that can be detected visually. With dental flm the processing involves chemicals; with digital sensors it may involve modern electronics and lasers. Dental x-ray “receptors” have undergone numerous changes over the history and advances in dental radiography.

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