The risk concept in medicine — Statistical and epidemiological aspects: A case report for applied mathematics in cardiology

In this study the theory of risk factors is discussed. The risk-concept is essential in cardiology and is, furthermore, important not only in medicine in general, but also and particularly in ecology. Since environmental risk factors endanger our health, ecological risks have to be taken as medical problems. If a factor or a set of factors is a necessary but not a sufficient condition for a disease we speak of a risk factor or of risk factors. Statistical analysis of risk factors can be performed by multivariate methods. A method which is particularly useful for finding the most important of a set of risk factors, is discriminant analysis.     

Risk,cost-effectiveness and profit: Problems in cardiovascular research and practice

Risk is the probability that within a certain time some expected negative event will take place. In medicine risk can be related to a decision or to some intrinsic factors which are associated with the probability of the occurrence of a disease. Decisions can be necessary in the individual life with respect to the question of visiting a physician or performing a certain diagnostic or therapeutic procedure. The introduction of new pharmaceutical or technical products into medical use are another set of decisions which can generate certain risks. Intrinsic or inherent risk factors are a set of variables or signs and symptoms which indicate the presence of a certain probability that some disease or event, e.g., arteriosclerosis or sudden infant death syndrome, may occur. Risk is always related to judgement. In a decision process cost, effectiveness and profit can be used to estimate the magnitude of the risk to be taken. In a similar way the problems in connection with an inherent risk are primarily related to the recognition of the magnitude of risk and to the possibility of prophylactic measures. In our own area of research, the sudden infant death syndrome (SIDS) is an event where only risk factors can be observed. We point at two facts in this context: Highly complex patterns of symptoms like behaviour can better be classified by intuitive Gestalt perception. A medical procedure like induction of labour can itself become a risk factor.     

Low target prevalence is a stubborn source of errors in visual search tasks

In visual search tasks, observers look for targets in displays containing distractors. Likelihood that targets will be missed varies with target prevalence, the frequency with which targets are presented across trials. Miss error rates are much higher at low target prevalence (1%-2%) than at high prevalence (50%). Unfortunately, low prevalence is characteristic of important search tasks such as airport security and medical screening where miss errors are dangerous. A series of experiments show this prevalence effect is very robust. In signal detection terms, the prevalence effect can be explained as a criterion shift and not a change in sensitivity. Several efforts to induce observers to adopt a better criterion fail. However, a regime of brief retraining periods with high prevalence and full feedback allows observers to hold a good criterion during periods of low prevalence with no feedback.     

认知与情绪过程的脑诱发电位研究——情绪的适应性假说

本研究观测了30名女性被试在月经周期中的不同激素时相对图像刺激的情绪价值的主观评估和脑诱发电位反应。调节刺激的情绪价值的五类幻灯片分别为普通人像、婴儿像、皮肤病人像、男模特儿像和女模特儿像。实验发现只有脑诱发电位的P3成份随刺激的情绪价值和激素的时相而变化。被评为喜爱与不喜爱的图像(婴儿像和皮肤病人像)所诱发的P3波在幅度上均明显高于中性图像(普通人像)所致的P3反应。在高孕激素时相,对婴儿像和男模特儿像的P3反应高于在低孕激素时相对同类刺激的P3反应。高孕激素时相还伴有对各类图像性感程度评估值的降低。对各类图像喜爱程度的评估则随雌激素水平的上升而增高。上述实验结果表明,P3波敏感于刺激的情绪价值并反映了认知与情绪过程中受生理状态调节的适应性变化。     

Characterization of the discriminative stimulus effects of lorcaserin in rats

Lorcaserin is approved by the Food and Drug Administration for treating obesity and is under consideration for treating substance use disorders; it has agonist properties at serotonin (5‐HT)_2C receptors and might also have agonist properties at other 5‐HT receptor subtypes. This study used drug discrimination to investigate the mechanism(s) of action of lorcaserin. Male Sprague–Dawley rats discriminated 0.56 mg/kg i.p. lorcaserin from saline while responding under a fixed‐ratio 5 schedule for food. Lorcaserin (0.178‐1.0 mg/kg) dose‐dependently increased lorcaserin‐lever responding. The 5‐HT_2C receptor agonist mCPP and the 5‐HT_2A receptor agonist DOM each occasioned greater than 90% lorcaserin‐lever responding in seven of eight rats. The 5‐HT_1A receptor agonist 8‐OH‐DPAT occasioned greater than 90% lorcaserin‐lever responding in four of seven rats. The 5‐HT_2C receptor selective antagonist SB 242084 attenuated lorcaserin‐lever responding in all eight rats and the 5‐HT_2A receptor selective antagonist MDL 100907 attenuated lorcaserin‐lever responding in six of seven rats. These results suggest that, in addition to agonist properties at 5‐HT_2C receptors, lorcaserin also has agonist properties at 5‐HT_2A and 5‐HT_1A receptors. Because some drugs with 5‐HT_2A receptor agonist properties are abused, it is important to fully characterize the behavioral effects of lorcaserin while considering its potential for treating substance use disorders.     

Distraction and body-focused hand movements.

The hypothesis that apparently irrelevant self- or object-manipulatory hand movements may act as a means of coping with distraction was tested by experimentally manipulating the amount and type of distraction experienced by 10-year-old children while they engaged in the Stroop colour-confusion and colour-naming tasks. If the hypothesis was correct, then increases in distraction were expected to be associated with increases in the frequency of these body-focused movements. The external distractions consisted of either the occurrence of a light signalling the need to perform a reaction time task or listening to distracting sounds through headphones. None of the hand movements increased in frequency with increases in secondary distraction, whether the secondary distractor was visual or auditory.     

Philosophy of medicine in Austria

It seems impossible to completely cover the field indicated by the title of this report because of the many contributions of individual physicians and non-physicians to problems of the philosophy of medicine in Austria, and to their solution. The main trends are rooted in historic developments and in the current problems of medicine and health care, which are similar world-wide. In Austria famous names like empress Maria Theresia or the physician Ignaz Semmelweis have to be mentioned in connection with the development of the ideas of a philosophy of medicine. In recent times again influential and well-known persons in related fields of medicine and health care are Austrians. However, the main line of new developments goes mostly unseen by the public: activities in medical ethics with the goal to humanize health care, carried on by groups of young physicians, biomedical engineers and students.     

Stereo and motion cues in preattentive vision processing--some experiments with random-dot stereographic image sequences

Low-level preattentive vision processing is of special interest since it seems the logical starting point of all vision processing. Exploration of the human visual processing system at this level is, however, extremely difficult, but can be facilitated by the use of stroboscopic presentation of sequences of random-dot stereograms, which contain only local spatial and temporal information and therefore limit the processing of these images to the low level. Four experiments are described in which such sequences were used to explore the relationships between various cues (optical flow, stereo disparity, and accretion and deletion of image points) at the low level. To study these relationships in more depth, especially the resolution of conflicting information among the cues, some of the image sequences presented information not usually encountered in 'natural' scenes. The results indicate that the processing of these cues is undertaken as a set of cooperative processes.