Periodontics in the next millennium

This article prognosticates where periodontology will be in the next millennium. The forecasting of such events is wrought with confusion because such predictions are shadowed by bias, dogmatism, prejudice, experiences, and opinions from either a closed or open mind. The results of the survey from 101 periodontists reflect opinions from varied backgrounds, years of clinical experience, and individual levels of success or failure. The responses cannot be tested for accuracy or duplicated by another survey except to wait out the test of time for the year 2025. Clinicians will be challenged to make decisions on accepting new techniques and concepts as these are brought into the therapeutic fold of periodontics. The clinician will be met with new possibilities as a paradigm shift is inevitable for periodontal practice in the next millennium. After all, who would have thought in the 1960s, the soft tissue augmentation era, that 22 years later in 1982, the regeneration of the lost attachment apparatus (alveolar bone, cementum, and periodontal ligament) would become a reality. This survey strongly suggests that by the end of the first quarter of the twenty-first century, local delivery of antimicrobials, growth and differentiation factors, and root biomodification agents will have a major impact on the practice of periodontics. One thing is certain, in the next millennium, considering the responses from this survey, a new era in periodontics will be here. By the year 2025, the research, development, and dissemination of new periodontal knowledge will be beyond the imagination from what was considered usual and customary for the twentieth century.     

Animal models of anxiety: an ethological perspective

In the field of anxiety research, animal models are used as screening tools in the search for compounds with therapeutic potential and as simulations for research on mechanism underlying emotional behaviour. However, a solely pharmacological approach to the validation of such tests has resulted in distinct problems with their applicability to systems other than those involving the benzodiazepine/GABAA receptor complex. In this context, recent developments in our understanding of mammalian defensive behaviour have not only prompted the development of new models but also attempts to refine existing ones. The present review focuses on the application of ethological techniques to one of the most widely used animal models of anxiety, the elevated plus-maze paradigm. This fresh approach to an established test has revealed a hitherto unrecognized multidimensionality to plus-maze behaviour and, as it yields comprehensive behavioural profiles, has many advantages over conventional methodology. This assertion is supported by reference to recent work on the effects of diverse manipulations including psychosocial stress, benzodiazepines, GABA receptor ligands, neurosteroids, 5-HT1A receptor ligands, and panicolytic/panicogenic agents. On the basis of this review, it is suggested that other models of anxiety may well benefit from greater attention to behavioural detail.     

人工晶体材料的生长技术

人工晶体材料在半导体、光电子、激光、宇航等现代高新技术中起着日益重要以至关键的作用，人工晶体材料及其生长的研究已成为国际材料学界的一个热门，文章主要介绍几种常用的晶体生长技术。     

加快组建湖南有色集团中央研究院提升核心竞争力

文章介绍了现代企业中央研究院的内涵及成功的实例，论述了湖南有色金属控股集团有限公司组建中央研究院的重要性和迫切性，并就公司已具备的各项基础条件，提出了中央研究院运行机制和管理模式的构想，这对中央研究院的组建、运行、发展、提升核心竞争力，具有积极的影响和作用。     

粉末冶金Cu基金刚石工具的研究现状及进展

以金刚石颗粒为磨料,与金属胎体混合,经烧结制取的金刚石工具,为加工玻璃、花岗岩、大理石等硬脆材料不可替代的新型工具。本文阐述了Cu基金刚石工具的研究现状,主要包括Cu基胎体的分类、预合金化技术、金刚石表面金属化技术、稀土元素在Cu基金刚石工具中的应用等。研发新的合金体系与新技术,提高Cu基金刚石工具的综合性能,是今后的研究方向。     

Castability of aluminium alloys

Castability is the ability of an alloy to be cast without formation of defects such as cracks, segregations, pores or misruns. Alloy dependent phenomena that determine castability are fluidity, macrosegregation, hot tearing and porosity. These phenomena have been known for a long time but have only recently become well understood and work is underway to develop predictive castability models. These models require input of physical properties, such as solidification path, dendrite coherency, solidification shrinkage and interdendritic permeability. Some of these properties are difficult to determine experimentally but new experimental techniques are being developed to extract such data. This paper will review the phenomena that limit castability of aluminium alloys. The influence of alloy composition on fluidity, macrosegregation, hot tearing and porosity will be described. Models for castability prediction will be briefly reviewed and data on coherency, fluidity, permeability and shrinkage will be presented.     

EEG dimension in sons of alcoholics

Recent advances in the field of nonlinear dynamics have provided new conceptual models, as well as novel analytical techniques applicable to studies in alcohol research. One measurement technique, which has been developed in an attempt to characterize nonlinear systems in physics and biology, is the estimation of attractor dimension. This dimension may be seen as a measure of the information required to describe the current behavior of a system. We have applied these techniques to the analysis of EEG collected from 17 men with alcoholic fathers and 19 men with no alcoholic relatives. The men with alcoholic fathers were found to have a lower EEG attractor dimension than their matched controls. This suggests that the EEG of young men with alcoholic fathers may be "more organized" or "less complex" than men with no alcoholic relatives. Although more studies will be needed to explore this hypothesis, these studies suggest that further development of nonlinear approaches to the analysis of brain systems are likely to generate new clinical measures, as well as new ways of viewing brain electrical function and alcoholism.     

Some issues in estimating the effect of prognostic factors from incomplete covariate data

In evaluating prognostic factors by means of regression models, missing values in the covariate data are a frequent complication. There exist statistical tools to analyse such incomplete data in an efficient manner, and in this paper we make use of the traditional maximum likelihood principle. As well as an analysis including the incompletely measured covariates, such tools also allow further strategies of data analysis. For example, we can use surrogate variables to improve the prediction of missing values or we can try to investigate a questionable "missing at random' assumption. We discuss these techniques using the example of a clinical study where one important covariate is missing for about half the subjects. Additionally we consider two further issues: evaluation of differences between estimates from a complete case analysis and analyses using all subjects and assessment of the predictive value of missing values.     

Pediatric cardiopulmonary bypass: a review of current practice

Devices and techniques used for pediatric cardiopulmonary bypass are ever changing. There are frequently reports in the literature about new techniques and new devices. Periodic surveys are helpful because they reveal the actual extent to which these techniques and devices are applied to clinical practice. Advances in research are bringing about a better understanding of the intricate aspects of CPB and the effects of CPB on pediatric patients. There appears to be a trend from widely divergent approaches to CPB for pediatric patients to more uniformity in practice. For example, the use of membrane oxygenation and arterial line filtration has become universal, and there is an increase in the use of all types of safety devices. Techniques reported in the medical literature at the beginning of the decade, such as, the use of modified ultrafiltration, the use of centrifugal cell washers to process packed red blood cells before adding them to the prime, and the use of the antifibrinolytic drug, aprotinin, have become part of practice at a large number of pediatric heart centers. Periodic surveys are useful, as they provide a measurement of current practice. They also provide a historical record of the advances in the field.     

Degradation of gamma D- and gamma s-crystallins in human lenses

Debates within nursing can take the form of useful discussion and critique or verbal conflict generated from inflexible paradigm positions intolerant of differing stances perceived to be of no value. It is suggested that the most profitable process is debate that generates understanding of the strengths and limitations of various tools and techniques and helps identify suitable usage rather than uncritical advocacy or outright rejection. Suggested uses will thus themselves become subject to further debate and practitioners will be encouraged to adopt a use that suits their practice setting and role. The quantitative-qualitative research debate, criticisms of the nursing process and nursing models and reflective practice are examined. Dogmatic positions are highlighted and uses that are potentially controversial are identified.     

Mediators and pharmacology of visceral sensitivity: from basic to clinical investigations

Over the last decade, the role of visceral sensitivity has been largely recognized in the pathophysiology of functional digestive disorders, particularly in the irritable bowel syndrome. These studies have highlighted the role of afferent pathways arising from the gut as a possible target for new treatments intended to relieve pain or modify altered reflexes present in such patients. These pharmacological targets have been identified mainly by studies on animal models of visceral hyperalgesia of various origins including local inflammation. Locally, several mediators are of paramount importance for sensitization of nerve endings: 5-hydroxytryptamine, bradykinin, tachykinins, calcitonin gene-related peptide, and neurotrophins. Selective antagonists to various subtypes of their receptors are currently available and have been shown to be active in these animal models. Other substances, such as somatostatin, opiold peptides, cholecystokinin, oxytocin, and adenosine, modulate the transmission of nociceptive inputs from the gut to the brain and are of clinical interest. This article reviews the current understanding of these mediators. Although these agents seem to be promising tools for the treatment of visceral hyperalgesia and its consequences (abdominal pain and disturbed reflexes), their clinical efficacy remains to be shown. A better understanding of the nature and the location of the defect in the sensory pathways may permit the selection of subgroups of patients for treatment according to the pharmacological properties of these new therapeutic agents.     

Cancer consequences of the Chernobyl accident in Europe outside the former USSR: a review

Therapeutic research is being stepped up to light Alzheimer's disease (AD), although its heterogeneity, the insufficiency of physiopathological knowledge, and the lack of a reference treatment impede the development of a drug to combat it. However, progress has opened up many avenues. Some recent approaches that have led to therapeutic research are identification of biochemical abnormalities, identification of dysfunction in several neurotransmitter systems (cholinergic, catecholaminergic, serotonergic, and peptidergic systems), and the study of senile plaques and neurofibrillary degeneration tangles. Although some types of therapy have been used for a long time (e.g., metabolic products such as nootropes), recently developed drugs target different systems: for example, neurotransmitter systems are important for symptomatic improvements in cognitive functions. The principal improvements expected with some new anticholinesterases whose role is to increase the available amount of central acetylcholine are in memory and attention. Second, retarding neuronal degeneration by acting on amyloid plaques is another possible future therapy. Here, protease inhibitors appear to be interesting tools. Third, the endototoxin etiology of neurodegenerative illnesses remains uncertain. After the first attempts with N-methyl-D-aspartate (NMDA) antagonists that had inescapable side effects, hopes rose with some new pharmacological tools such as the AMPA/kainate antagonists. Fourth, a possible stimulation of neuronal plasticity by neurotrophic factors such as nerve growth factor (NGF) constitutes another prospected research area. Fifth, the inflammatory aspects of degenerative diseases attract the attention of many laboratories and preliminary reports are hopeful. Finally, out of the established pharmacological tools, gene therapy, though still hypothetical, may become the expected treatment in the future. Pharmacotherapy used in the most common types of dementia has until now been largely palliative and dealt with symptoms. It is nonetheless not unreasonable to look forward to the development of drugs that will be able to combat the evolution of the dementia itself, rather than its symptoms. A list of different products developed to treat AD is concluded by an evaluation of the expected results and, in particular, the orientations likely to be necessary.     

Pathophysiology of the neuroregulation of growth hormone secretion in experimental animals and the human

During the last decade, the GH axis has become the compelling focus of remarkably active and broad-ranging basic and clinical research. Molecular and genetic models, the discovery of human GHRH and its receptor, the cloning of the GHRP receptor, and the clinical availability of recombinant GH and IGF-I have allowed surprisingly rapid advances in our knowledge of the neuroregulation of the GH-IGF-I axis in many pathophysiological contexts. The complexity of the GHRH/somatostatin-GH-IGF-I axis thus commends itself to more formalized modeling (154, 155), since the multivalent feedback-control activities are difficult to assimilate fully on an intuitive scale. Understanding the dynamic neuroendocrine mechanisms that direct the pulsatile secretion of this fundamental growth-promoting and metabolic hormone remains a critical goal, the realization of which is challenged by the exponentially accumulating matrix of experimental and clinical data in this arena. To the above end, we review here the pathophysiology of the GHRH somatostatin-GH-IGF-I feedback axis consisting of corresponding key neurotransmitters, neuromodulators, and metabolic effectors, and their cloned receptors and signaling pathways. We propose that this system is best viewed as a multivalent feedback network that is exquisitely sensitive to an array of neuroregulators and environmental stressors and genetic restraints. Feedback and feedforward mechanisms acting within the intact somatotropic axis mediate homeostatic control throughout the human lifetime and are disrupted in disease. Novel effectors of the GH axis, such as GHRPs, also offer promise as investigative probes and possible therapeutic agents. Further understanding of the mechanisms of GH neuroregulation will likely allow development of progressively more specific molecular and clinical tools for the diagnosis and treatment of various conditions in which GH secretion is regulated abnormally. Thus, we predict that unexpected and enriching insights in the domain of the neuroendocrine pathophysiology of the GH axis are likely be achieved in the succeeding decades of basic and clinical research.     

Myocarditis and inflammatory cardiomyopathy: microbiological and molecular biological aspects

Myocarditis is an inflammatory disease of the myocardium associated with cardiac dysfunction. The natural history of myocarditis is frequently characterised by the evolution in dilated cardiomyopathy. Due to its variable clinical manifestation from latent to very severe clinical forms, such as acute congestive heart failure and sudden death, its prevalence is still unknown and probably underestimated. In spite of the development of various diagnostic modalities, early and definite diagnosis of myocarditis still depends on the detection of inflammatory infiltrates in endomyocardial biopsy specimens according to the Dallas criteria. Routine application of immunohistochemistry, used for identification and characterisation of inflammatory cell populations, has now significantly increased the sensistivity of the diagnosis of inflammatory cardiomyopathy. Various molecular techniques, such as PCR, gene sequencing and real-time PCR, often applied on the same endomyocardial specimen, have become an essential part of the diagnostic armamentarium for rapid, specific and sensitive identification of infective agents. The correct application of molecular techniques will allow increasingly more information to be obtained: new epidemiology, new patient risk stratification and overall more appropriate medical treatment.     

Why Use Enactable Models of Construction Processes?

Construction is a process-based industry. In such an industry it is important to have a clear understanding of the process. One way to achieve this is by the use of a process model. In a European Community funded research project the business process of a small U.K. construction company was modeled and analyzed. Both visual modeling and enactable modeling techniques were used in this exercise. This paper aims to show how process understanding can be better achieved by a combination of visual models and enactable models. This is supported by examples from the construction company process studied. The tools and techniques used in this exercise are those developed by the collaborators of the project. The visual modeling is done using ProcessWise WorkBench and Role Activity Diagrams. The view of the business process given by the ProcessWise WorkBench models is predominantly process based, whereas Role Activity Diagrams provide a role based view of the process. The enactable modeling is done using RolEnact, a modeling tool that enacts formal specifications of processes.     

Construction Business Competitiveness and Global Benchmarking

The focus of this paper is on developing “quality” and sustainable construction businesses capable of riding market shifts and growing both nationally and internationally. Knowledge of current management tools and techniques will no doubt prove useful in the quest for transforming a nonperforming business. However, no long lasting effect can be expected unless attention is paid to the fundamental principles and practices that govern organizational behavior, including the views an organization has of its customers, competitors, and itself. Commercial performance of organizations has increasingly become not only dependent on resource efficiency, but also on retooling and aggressive new business development initiatives as well as reduction in base production and operational costs. The human factors and mental models that people have within any given organization profoundly affect the success or failure of that organization. In this paper a critical review of the current concepts and techniques influencing construction organizations is offered with a focus on people and organizational improvements. A set of critical success factors is then distilled, followed by a systematic process of applying the same to achieve success.     

Contribution of Nonlinear Finite-Element Analysis to Evaluation of Two Structural Concrete Failures

The failure of two reinforced concrete structures is recounted, one involving a warehouse structure and the other an offshore platform base structure. Design details and factors leading to the collapses are identified and discussed. The structures were subsequently analyzed using nonlinear finite-element analysis procedures, taking into account relevant second-order behavior models. The analyses provided an accurate assessment of the load capacities and failure modes observed, as well as meaningful insights into the underlying behavior mechanisms and factors leading to the failures. This paper supports the view that nonlinear analysis techniques have become useful everyday tools for design office applications, particularly in forensic work, and also gives evidence suggesting that errors in the design of modern structures can be potentially more catastrophic than in the past, and that advanced assessment techniques will assume increased importance as a result.     

Role of laparoscopic ultrasound in cancer management

Clinical practice guidelines have enormous potential to improve the quality of and accountability in health care. Making the most of this potential should become easier as guideline developers integrate guidelines within information systems and electronic medical records. A major barrier to such integration is the lack of computing infrastructure in many clinical settings. To successfully implement guidelines in information systems, developers must create more specific recommendations than those that have been required for traditional guidelines. Using reusable software components to create guidelines can make the development of protocols faster and less expensive. In addition, using decision models to produce guidelines enables developers to structure guideline problems systematically, to prioritize information acquisition, to develop site-specific guidelines, and to evaluate the cost-effectiveness of the explicit incorporation of patient preferences into guideline recommendations. Ongoing research provides a foundation for the use of guideline development tools that can help developers tailor guidelines appropriately to their practice settings. This article explores how medical informatics can help clinicians find, use, and create practice guidelines.     

硬质合金刀具涂层技术的研究进展

随着涂层技术的进步，使得硬质合金刀具涂层方法在不断地进步，日趋复杂化和多样化；硬质合金刀具涂层种类也在不断地更新，从单一的化合物涂层朝着多元复杂化合物涂层发展，涂层层数也从几层到十几层发展。本文简要地综述了目前国内外涂层硬质合金刀具的特点，高温化学气相沉积涂层(HTCVD或简称CVD)、物理气相沉积涂层(PVD)、等离子化学气相沉积涂层(PCVD)、中温化学气相沉积涂层(MTCVD)和离子辅助物理气相沉积涂层(IBVD)这5种硬质合金刀具涂层方法的机理、特点和缺点，以及单渗层涂层硬质合金、多渗层涂层硬质合金和新渗层涂层硬质合金这3种硬质合金刀具涂层的特点和应用。