H.A.M. Daanen

Physiological criteria for functioning of hands in the cold. A review

Hands are important instruments in daily life. Without hands man is hardly able to function independently. Proper functioning of the hands is determined by several physiological parameters. These physiological parameters in turn are influenced by environmental factors. In this view of the literature, physiological processes in manual dexterity are described and the influence of a cold environment on separate physiological processes is studied. In general, cold means loss of dexterity. For reasons of safety and performance, it is important to restrict the loss of manual dexterity. For this purpose, in this study minimum criteria are given for all separate physiological components. Most important minimum criteria are: a local skin temperature of 15 degrees C, a nerve temperature of 20 degrees C and a muscle temperature of 28 degrees C. Only during maximum dynamic work is a muscle temperature of 38 degrees C recommended. These temperatures are average values, and of course individual differences are evident.

Whole body scanners

In dit artikel wordt een overzicht gegeven van de op dit moment beschikbare lichaamsscanners.

3D whole body scanners revisited

An overview of whole body scanners in 1998 (H.A.M. Daanen, G.J. Van De Water. Whole body scanners, Displays 19 (1998) 111-120) shortly after they emerged to the market revealed that the systems were bulky, slow, expensive and low in resolution. This update shows that new developments in sensing and processing technology, in particular in structured light scanners, have produced a new generation of easy to transport, fast, inexpensive, accurate and high resolution scanners. The systems are now moving to the consumer market with high impact for the garment industry. Since the internet sales of garments is rapidly increasing, information on body dimensions become essential to guarantee a good fit, and 3D scanners are expected to play a major role.

Made-to-measure pattern development based on 3D whole body scans

Purpose – New techniques are required to link 3D whole body scans to manufacturing techniques to allow for the mass‐customization of clothes. This study aims to compare two methods of producing skirts based on 3D whole body scans.Design/methodology/approach – Three females participated in the study. They were scanned with an accurate 3D whole body scanner. A set of relevant 1D measures was automatically derived from the 3D scan. The measures were incorporated in a skirt pattern and the skirt was made from jeans material. The second method was based on triangulation of the scanned waist‐to‐hip part. The points in the 3D scan were first converted to triangles and these triangles were thereafter merged with neighboring triangles of similar orientation until about 40 triangles remained. These triangles were sewn together to form a “patchwork”‐skirt. All females performed fit tests afterwards.Findings – The fit of the 3D‐generated patchwork skirt was much better than the fit of the skirt generated by the 1D sc...

Reproducibility of the mean power frequency of the surface electromyogram.

SummaryThere is evidence in the literature that the decrease of mean power frequency (MPF) during exercise is greater as a muscle becomes more fatigued. After strenuous exercise this phenomenon can last several days. It is usually assumed, however, that the MPF has a good reproducibility. In this study the reproducibility of the MPF of the surface electromyogram of the biceps brachii muscle was investigated for five subjects on 5 successive days. Force level, muscle length and skin temperature were kept constant. The results show that interindividual differences in MPF were large (SD 11.5 Hz). However, during these 5 days, the range in MPF for individual subjects was small. The SD of the trials within subjects and days was 2.0 Hz, while the SD of the days within subjects was 2.4 Hz (variability of the trials excluded). It is hypothesized that this SD may be due to variations in the electrode replacement. It is concluded that the variability in MPF for a subject is small compared to the decrease of the MPF associated with muscle fatigue and which can therefore be determined reliably during longitudinal studies.

Specificity of surface-EMG on the intrinsic lumbar back muscles

Abstract The cross-correlation coefficient functions (CCCFs) between twelve bipolar surface electrodes, placed symmetrically on the intrinsic lumbar back muscles (ILBM) were computed in order to estimate the amount of cross-talk. It was found that the CCCF values were mainly influenced by the distance between the electrodes. Other factors, such as static versus dynamic experimental conditions, the activity level, the angle between the dipole axis and the muscle fibres, the ECG, noise, power-line-induced-a.c.-components and resistance of biological material, have less influence, but nevertheless they do change the CCCF values. The absolute maximum in the CCCF can be used to validate EMG-signals. Absolute maxima in the CCCF within the range from 0 to 0.30 are considered as sufficient specific EMG-signals. The technique can be used to optimise the location of electrodes for the selective recording of localised muscle activity.

Non-invasive continuous core temperature measurement by zero heat flux

Reliable continuous core temperature measurement is of major importance for monitoring patients. The zero heat flux method (ZHF) can potentially fulfil the requirements of non-invasiveness, reliability and short delay time that current measurement methods lack. The purpose of this study was to determine the performance of a new ZHF device on the forehead regarding these issues. Seven healthy subjects performed a protocol of 10 min rest, 30 min submaximal exercise (average temperature increase about 1.5 °C) and 10 min passive recovery in ambient conditions of 35 °C and 50% relative humidity. ZHF temperature (T(zhf)) was compared to oesophageal (T(es)) and rectal (T(re)) temperature. ΔT(zhf)-T(es) had an average bias ± standard deviation of 0.17 ± 0.19 °C in rest, -0.05 ± 0.18 °C during exercise and -0.01 ± 0.20 °C during recovery, the latter two being not significant. The 95% limits of agreement ranged from -0.40 to 0.40 °C and T(zhf) had hardly any delay compared to T(es). T(re) showed a substantial delay and deviation from T(es) when core temperature changed rapidly. Results indicate that the studied ZHF sensor tracks T(es) very well in hot and stable ambient conditions and may be a promising alternative for reliable non-invasive continuous core temperature measurement in hospital.

Reliability of an infrared forehead skin thermometer for core temperature measurements

The SensorTouch thermometer performs an infrared measurement of the skin temperature above the Superficial Temporal Artery (STA). This study evaluates the validity and the accuracy of the SensorTouch thermometer. Two experiments were performed in which the body temperature was measured with a rectal sensor, with an oesophageal sensor and with the SensorTouch. After entering a warm chamber the SensorTouch underestimated the core temperature during the first 10 minutes. After that, the SensorTouch was not significantly different from the core temperature, with an average difference of 0.5°C (SD 0.5°C) in the first study and 0.3°C (SD 0.2°C) in the second study. The largest differences between the SensorTouch and the core temperature existed 15 minutes after the start of the exercise. During this period the SensorTouch was significantly higher than the core temperature. The SensorTouch did not provide reliable values of the body temperature during periods of increasing body temperature, but the SensorTouch might work under stable conditions.

Optimal postures and positioning for human body scanning

Advancements in technology for digitizing the surface of the human body are providing new opportunities for research in engineering anthropometry, the study of human body measurement for design and evaluation purposes. The availability of the technology is just the first step in applying surface scanning to engineering anthropometry; several issues remain to be resolved to make these tools useful for engineering applications. One important issue is the standardization of positioning and the posture of the subject for scanning. In engineering it is not enough to be able to measure one individual one time in one posture, but it is also necessary to measure the individual in different postures and compare the individual with many other people who have been comparably measured. Not surprisingly, people can be more difficult to measure precisely than fixed stationary objects. In the process of developing standardized procedures for surveying the civilian populations of North America and Europe, an experiment was conducted to determine optimal scanning positions. While this experiment used just one type of scanning technology, many of the methods are transferable to other methods as well. This paper discusses the results from that investigation.

cold-induced metabolism

Purpose of review Cold response can be insulative (drop in peripheral temperature) or metabolic (increase in energy expenditure). Nonshivering thermogenesis by sympathetic, norepinephrineinduced mitochondrial heat production in brown adipose tissue is a well known component of this metabolic response in infants and several animal species. In adult humans, however, its role is less clear. Here we explore recent findings on the role and variability of nonshivering thermogenesis in adults. Recent findings Large individual differences exist in mild cold response with respect to the relative contribution of the insulative response and the metabolic (nonshivering) response. In search for the possible explanations of this variation, recent studies on potential mechanisms of nonshivering thermogenesis in humans are presented. Emphasis is given to the role of uncoupling proteins, mitochondrial ATP‐synthase, and calcium cycling. The potential contribution of human skeletal muscle to nonshivering thermogenesis is discussed. The differences in nonshivering thermogenesis can partly be attributed to factors such as age, gender, physical fitness, adaptation, and diet. There are indications that genetic variation affect cold response. Summary The implications of the observed large individual variation in cold response is that a low metabolic response to cold can partly explain increased risk to develop obesity. Both the effect of environmental factors and genetic factors on nonshivering thermogenesis require more well controlled studies. With extended knowledge on these factors it can be ascertained if a pharmacological regimen is possible which would mimic the effects of chronic cold or elevated catecholamine levels, without attendant side effects.