European survey of dental X-ray equipment

The implementation of an X-ray Quality Assurance (QA) program is a legal requirement in Europe as stipulated in the EU Council Directive 97/43/EURATOM (MED). A review of the literature has identified that European countries are performing some level of QA testing of their dental X-ray equipment, although the type and level to which testing is performed can differ. The European SENTINEL co-ordination action proposed to collate a survey of equipment data for both conventional and digital dental X-ray installations among the SENTINEL partners. The European QA results confirm that systems can be operated below tolerance, and in some cases significantly so, while still in clinical use. This can occur despite servicing of equipment. The results have emphasised the fact that there is a requirement for the medical physics/engineering professions to become more closely involved in the management of dental radiology equipment. This also includes their involvement in the development and delivery of appropriate training courses for dentists and suppliers of dental radiology equipment.     

X射线安检仪性能检测研究

X射线安检仪(以下简称安检仪)受到使用频率及人为因素的影响,其技术性能参数肯定会发生漂移、变化,导致测量结果失准,因而需要定期进行计量性能检测,以保证其正常有效运行,确保监测结果的准确可靠。该文对安检仪的特点、作用以及主要性能参数的检测方法作了一定的研究。     

Effect of X-ray exposure on the pharmaceutical quality of drug tablets using X-ray inspection equipment

Context: X-ray inspection equipment is widely used to detect missing materials and defective goods in opaque containers. Its application has been expanded to the pharmaceutical industry to detect the presence of drug tablets in aluminum foil press-through packaging. However, the effect of X-rays on the pharmaceutical quality of drug tablets is not well known.

Objective: In this study, the effect of X-rays on the pharmaceutical quality of drug tablets was investigated.

Methods: Exposure of acetaminophen, loxoprofen and mefenamic acid tablets to X-ray doses of 0.34?mGy (thrice the dose by X-ray scanning) to 300?Gy (maximum dose from our X-ray equipment) was demonstrated, and the samples were evaluated by formulation tests.

Results: Exposure to X-rays did not affect the pharmaceutical quality of the drug content. The samples exposed to X-rays exhibited almost the same profile in formulation tests (dissolution test, disintegrating test and hardness test) as control samples (0?Gy). The combination of X-ray exposure with accelerated temperature and humidity tests (six months) also did not affect the pharmaceutical quality. The color change of light-sensitive drugs (nifedipine and furosemide tablets) after X-ray exposure was negligible (Conclusion: The X-ray scanning and X-ray exposure under our experimental conditions did not affect the pharmaceutical quality of drug tablets.     

Guaranteeing safety in high-pressure vessels and chemical equipment tanks from the point of view of brittle fracture

Conclusions Two basic approaches for evaluation of safety from the point of view of brittle fracture of high-pressure vessels and chemical equipment tanks are presented. Obviously not all structures require evaluation based on the approaches presented. It is not necessary to make an evaluation of the safety of vessels and tanks produced from austenitic steels in which the possibility of appearance of brittle fracture is absent. This is also true for repeated start-up of apparatus with a low level of membrane stresses with /_0.2<0.1. Such an evaluation must be made for new structures and apparatus produced using a new welding method, apparatus after a change in material made of types of steel which have not been checked in practice, that with deviations from production instructions and standards, etc.If in evaluation of the safety of a structure using the proposed approaches a negative result is obtained under the given conditions, it will not necessarily fail brittlely. In such a case the size of the critical defect must be considered and the acceptability of the structure discussed. The reliability of the structure may also be evaluated with the use of other methods of fracture mechanics or based on the transition temperature. In any case it is necessary to use all existing possible methods of evaluation of the safety of a structure. Only after this may the structure be assumed unsatisfactory from the point of view of brittle fracture.Brno, Czechoslovakia. Translated from Problemy Prochnosti, No. 1, pp. 30–34, January, 1985.     

Contractual hazards and long-term contracting: a TCE view from the petroleum industry

We use the tools of transaction cost economics (‘TCE’)and economic analysis more generally to analyze the provisionsof a long-term multi-million-dollar contract in the petroleumindustry, the 35 year Field Contractors Agreement signed in1965 for the development of a major oil field just offshorefrom Long Beach, California. There is a substantial public recordregarding the deliberations that ultimately led to the choiceof contract terms. That record makes it possible to identifyhow various TCE-based and related economic concerns—aboutdealing with information impactedness and restricting the scopefor opportunistic behavior— affected the choice of contractualprovisions. As such, this case study provides useful insightsinto the relevance of TCE.     

Multimeter for diagnostic X-ray equipment radiation and electrical parameters

Translated from Izmeritel'naya Tekhnika, No. 11, pp. 59–60, November, 1989.     

X射线安检设备中探测技术研究

从70年代开始,对通过重要的出入口的人员所携带的行李物品进行安全检查已成为国际上广泛采用的安全措施.近年来,受到航空安全等需要的驱使,安全检测技术得到迅速发展.在各种检测手段中,低成本、低剂量、非接触式、可成像的X射线安检设备应用最为普遍.本文对X射线探测违禁品的几种方法做了总结,阐述了单能量法、双能量法、双视角、CT及散射法的探测原理及优缺点,最后对安检技术的未来发展趋势进行了预测.     

Splines from a Bayesian point of view

Summary Procedures using splines for estimating values of linear functionals of an unknown function based on finitely many possibly noisy observations of function values are reviewed taking a Bayesian point of view. Interpolation with splines is emphasized as an example of Bayesian numerical analysis, smoothing with splines is presented as interpolation in estimated function values. Extensions of the approach to estimating values of non-linear functionals applied to the unknown function and to estimation subject to linear constaints on the unknown function are discussed. Furthermore, invariance of Bayesian inference to modifications of the prior distribution, resulting from alternative choices of an appropriate function space for estimation, is addressed, too.     

Discipline-based approaches to evidence-based practice: a view from nursing.

BACKGROUND: Research carried out by nurses or by others on patient problems of concern to nurses is contributing to the development of evidence-based nursing practice. In the past few decades, there has been a dramatic increase in clinical research, in health services research, and in the content and process of informatics, all focused on nursing care. The translation of findings of this research into clinical practice and the organization of nursing is less dramatic. The opportunity to implement research-based practice is great, but requires attention, methods, and resources. Also required are a database and an information system which include terms essential to nursing practice. DIMENSIONS OF NURSES' INVOLVEMENT IN EVIDENCE-BASED PRACTICE: The importance of nurses' involvement in evidence-based practice (EBP) can be viewed from three perspectives: (1) nurses' participation in medical problems and medical interventions, (2) nursing problems and nursing interventions, and (3) development and use of a standardized language that describes the problems, interventions, and outcomes important to nursing. APPLYING EBP TO COMBINED MEDICAL AND NURSING PROBLEMS: The best outcomes for a specific patient population are achieved through a combination of the medical and nursing problems and evidence-based interventions. Examples of problems of importance to nursing practice and research include pain, dehydration, incontinence, lifestyle change, confusion, immobility, knowledge deficit, noncompliance, anxiety, skin breakdown, inappropriate use of restraints, and falls. Interventions for prevention and treatment of the individual problem or combination of problems comprise the focus of nursing research and EBP.     

In-situ investigations of magnetron sputtering processes with laboratory X-ray equipment

An Fe-Al duplex film was prepared on a Si(111)-wafer by sputter deposition in a vacuum chamber with two integrated small magnetron sources. The chamber allows the in-situ investigation of such sputtering processes using grazing incidence X-ray reflectivity, X-ray scattering measurements and X-ray diffraction. We will present details of the new cell and present the first results obtained using reflectivity measurements of the Fe-Al thin films. Here we will focus on the detailed evaluation of the specular reflectivity data of the iron films only, which clearly indicates the presence of an iron oxide, the density and roughness of which were determined and their changes with the film thickness were discussed in the framework of thin film growth models.     

Decoherence: the view from the history and philosophy of science

We present a brief history of decoherence, from its roots in the foundations of classical statistical mechanics, to the current spin bath models in condensed matter physics. We then analyse the philosophical importance of decoherence in three different foundational problems, and find that its role in their solutions is less than that commonly believed. What makes decoherence more philosophically interesting, we argue, are the methodological issues it draws attention to, and the question of the universality of quantum mechanics.     

Magnetic impurity in a luttinger liquid: A view from conformal field theory

Exact results are reported for the low-temperature thermodynamics of a spin-1/2 magnetic impurity coupled to a 1D interacting electron system. The use of conformal field theory techniques reveals that there are only two types of critical behaviors consistent with the symmetries of the problem: either a local Fermi liquid, or else a theory identical to that recently proposed by Furusaki and Nagaosa. We also show that forward electron scattering on the impurity produces the same critical behavior as the two-channel Kondo effect for noninteracting electrons.This work is supported by NSF grant DMR-9205125 (P. F.), and a grant from the Swedish Natural Science Research Council (H. J.).     

Maintenance optimisation from a decision theoretical point of view

Maintenance optimisation is rarely discussed from a decision theoretical point of view. It is believed that maintenance programmes may benefit from using decision theory in a more formal manner. In decision theory there is a sharp line of demarcation between establishing requirements and preferences on one side, and methods for seeking an optimal solution in accordance with the requirements and preferences on the other side. We discuss requirements and preferences concerning maintenance, and how to model these by value and utility functions. Next we discuss how to choose the optimum set of maintenance actions. Influence diagrams are introduced to visualise the relation between maintenance actions, system characteristics and value functions. Finally an illustrative example is given.     

Free patent databases on the Internet: a critical view

Free patent databases on the Internet are useful, particularly as they allow users in numerous locations to quickly access information. This advantage of ease of access is however a disadvantage if the novice user does not realise that expert advice is needed at the site itself, and ideally from staff at patent libraries, so that a good search can be constructed and so that the results can be properly interpreted. Other problems include the potential disappearance of such databases, or charging for them; problems in adequate access, particularly when the latest software is used; poorly designed search masks in many sites; poor or non-existent help; and the inability to browse data. Suggestions to improve the situation include ensuring that compatible products on CD-ROM or DVD co-exist; much better help keys; hypertext links to classifications and to patent libraries; and easy scanning through drawings.     

Interlaboratory comparison and accreditation in quality control testing of diagnostic X-ray equipment

The University of Tartu provides a quality control service to the majority of diagnostic X-ray departments in Estonia. Its methodology has been adopted from the IEC and other relevant standards. Recently the Testing Centre of the University of Tartu was accredited on this methodology by ISO/IEC 17025. Besides the implementation of the quality management system, participation in interlaboratory comparison (ILC) was one of the prerequisites for the accreditation. Tests for estimating reproducibility of tube voltage and dose rate, accuracy of the voltage and accuracy of exposure time were carried out on a diagnostic X-ray unit in the Radiation and Nuclear Safety Authority in Helsinki. The measurement performance was judged by calculating deviation E(n) normalised with respect to the stated uncertainties. E(n) values for all tests were less than unity and by the common ILC criteria the testing performance could be considered as acceptable.     

The politics of contraception: The view from Tokyo

It is not generally known that Japan is virtually the only country in the world where oral contraceptives have not been approved officially. The reasons for this rather bizarre situation are partly cultural, partly political, and probably also due to the pressure of the private medical sector responsible for abortions. The situation has suddenly changed and, by 1990, it is likely that the first oral contraceptives will appear on the Japanese market. Details of the government guidelines are presented which will make this event possible, and it is pointed out that Japan represents potentially the largest untapped market in the world; six million Japanese women may be using oral contraceptives by the turn of the century.