Comfort of fenestrated hydrogel lenses

A controlled, double-masked, randomized study was conducted on ten subjects to determine the effect of fenestration size on the initial comfort of hydrogel contact lenses. Four fenestrated lenses were tested, each lens containing four mid-peripheral fenestrations of the same size. The diameter of the fenestrations used in the four lenses ranged from 0.39 to 0.96 mm. An unfenestrated lens was also tested. All lenses were made of HEMA and were ordered with the following specifications: -3.00 D, 14.0 mm diameter, 8.4 mm back central optic radius and 0.06 mm centre thickness. There was a significant negative correlation between comfort and fenestration size, indicating that larger fenestrations are less comfortable. Even the lens with the smallest fenestrations (0.39 mm) was significantly less comfortable than the unfenestrated lens. The implication of this finding is that fenestrations may not be clinically efficacious in view of the poor comfort (and presumably increased mechanical effect of the fenestration edges on the tarsal conjunctiva) of fenestrated lenses.     

逆行静脉穿刺的临床应用效果观察

目的探讨逆行静脉穿刺的临床应用效果，为长期静脉输液及浅静脉穿刺困难的患者提高手背浅静脉的利用率，以保护血管。方法随机选择静脉输液患者126例（正向和逆向静脉穿刺），采用掌指关节附近血管进行静脉穿刺。结果两种穿刺方法对同种液体最大滴速无显著影响（P〉0．05），对手的活动度及局部渗出、肿胀有显著影响（P〈0．01）。结论逆行静脉穿刺可提高穿刺的成功率，便于固定，增加患者的舒适度。     

Thermal regulatory responses to submaximal cycling following lower-body cooling in humans

This study compared the effects of pre-exercise cooling with control water immersions on exercise-induced thermal loads derived from steady-state submaximal exercise. Eight healthy male participants [mean (SEM) age 29 (1) years, maximal oxygen uptake 3.81 (0.74) l·min^–1, and body surface area 1.85 (0.11) m²] took part in experiments that included 30 min of baseline data collection [ambient temperature 21.3 (0.2°C)], 30 min of immersion in water to the level of the supra-iliac crest [water temperatures of 35.1 (0.3)°C for thermoneutral and 17.7 (0.5)°C for precooled treatments], and 60 min of cycling exercise at 60% of maximal oxygen uptake. No significant differences were noted during exercise in net mechanical efficiency, metabolic rate, O₂ pulse, or ratings of perceived exertion between the two treatments. Precooling resulted in a significant negative body heat storage during immersion and allowed greater heat storage during exercise. However, net body heat storage for the entire protocol was no different between treatments. Cooling significantly lowered rectal, mean skin, and mean body temperatures as well as more than doubling the exercise time until a 0.5°C rectal temperature increase was observed. The cooling trial significantly delayed onset of sweating by 19.62 min and decreased sweat rate by 255 ml·h^–1 compared to control. Thermal and sweat sensation scores were lower after the cooling treatment compared to control. These data suggest that lower-body precooling is effective at decreasing body heat storage prior to exercise and decreases reliance on heat dissipation mechanisms during exercise. Therefore, this unique, well-tolerated cooling treatment should have a broader application than other precooling treatments. Electronic Publication     

Local thermal unpleasantness and discomfort prediction in the vicinity of thermoneutrality

This work emphasizes a better understanding of the origin of human thermal discomfort under heterogeneous but steady environments, in subjects in the vicinity of physiological and sensory thermoneutrality. The knowledge of skin temperatures allows a psychophysiological study aiming at linking the body thermal state (local and global) to thermal sensation (perceptive and affective judgements). By using two driving simulators, 345 subjects were exposed to different thermal environments, modulated by factors such as the air distribution in the automotive cockpit or the clothing insulation (winter or summer). This work shows that consideration of the local thermal state is essential for the evaluation of thermal comfort in the case of non-uniform environments. Our experimental conditions point out that the overall sensation of discomfort is quantitative, with local unpleasantness needing to be felt for a certain number of body surfaces. A local origin is suggested for cold discomfort, in opposition to the global characteristics of warm discomfort.     

Thermal pleasantness sensation: an indicator of thermal stress

Summary The degree of pleasantness or unpleasantness of thermal sensation aroused by a particular peripheral thermal stimulus has been shown to be an indicator of thermal state of the body in relation to the thermoregulatory set point. This phenomenon is known as thermal alliesthesia. The quantification of thermal alliesthesia was possible using two methods: (1) A set of temperature stimuli (15, 20, 25, 30, 35, and 38 C) was applied, by means of a Peltier thermode 5.5×2.7 cm², on the back of the hand, the forehead, and the back of the neck. When each stimulus had been applied for 5 s the subjects voted their degree of thermal pleasantness/unpleasantness on a psychophysical scale ranging from +2.0 for very pleasant to –2.0 for very unpleasant. (2) The subjects were also asked to adjust the Peltier thermode temperature, without looking at the temperature scale, such that the temperature (on the back of the neck) was maintained at the level the subjects considered most pleasant. The subjects also rated their general thermal comfort sensation on a five point scale ranging from +2.0 for very comfortable to –2.0 for very uncomfortable. Rectal temperature and skin temperature at eight locations were continuously recorded. Passive thermal exposures (54) were made with nine passive subjects and 42 exposures were done with working (50 watt) subjects. All exposures were carried out in a climatic chamber at a constant temperature, relative humidity (45%), and air speed (0.3 m/s). Each subject underwent 6 exposures at six room temperatures of 15, 20, 25, 30, 35, and 40 C. The results of work exposures confirmed the findings of previous studies; namely, the effect of core temperature change overrides any effect due to mean skin temperature on alliesthesial response. A mathematical function to predict the mean slope of the thermal pleasantness rating/stimulus line (a measure of the alliesthesial response) was derived using the data obtained from the passive thermal exposures. The results indicate that alliesthesial response can be used as a quantitative indicator of thermal stress.Supported by the European Coal and Steel Community, Luxembourg     

Heat and water vapour transfer of protective clothing systems in a cold environment,measured with a newly developed sweating thermal manikin

A moveable sweating thermal manikin has recently been developed. Thermal and water-vapour resistances of three kinds of cold-protective clothing ensembles, laminated with polytetrafluoroethylene, polyurethane and without a laminate were measured, with the aid of the manikin in a cold environment of 5°C with a relative humidity of 70% and an air velocity of around 1.5 m s^–1. Two sweating rates of 65 and 130 g m^–2 h^–1 were employed. Supplied heat fluxes in both of the sweat rates ranged from 350 W m^–2 to 400 W m^–2. To maintain a comfortable condition, the skin wettedness (w) (mean weighted value) had to be kept at 0.6. The measurements obtained from the manikin when testing the three ensembles were w=0.3 (approximately) for the low sweat rate and w0.6 for the high sweat rate, irrespective of the property differences among the ensembles. In addition, the condensation in the ensembles in comparison with those calculated from an analytical equation is discussed. Condensation mass fluxes in the ensembles obtained byexperiment and those from the calculation agreed sufficiently well. Thus, distribution of the condensation in the ensembles was estimated using the equation.     

Self-reported comfort in athletic training of gender-specific and non-gender-specific injuries and issues

Context: To assist athletes in maintaining optimal health, athletic trainers must work with athletes of both sexes.Objective: To examine athletic trainers'' comfort levels in providing care for gender-specific and non-gender-specific injuries and issues.Design: We mailed 235 Gender Comfort in Athletic Training Questionnaires to program directors, who were asked to distribute and collect them.Setting: We randomly selected 21 athletic training education program directors and invited them by e-mail to participate in the study. Fourteen program directors representing the 10 National Athletic Trainers'' Association districts agreed to participate.Patients or Other Participants: A total of 192 participants returned completed questionnaires, for a response rate of 82% (103 women, 89 men; 101 senior athletic training students, 91 certified athletic trainers).Main Outcome Measure(s): The questionnaire consisted of 17 injuries and issues common to both female and male athlete scenarios. Three gender-specific items were added to each scenario. Responses were scored on a 5-point scale anchored by 1 (very uncomfortable) and 5 (very comfortable). Participants were asked to indicate the reason for any degree of discomfort. Internal consistency, determined by the Cronbach alpha, was .92 for the female athlete scenario and .93 for the male athlete scenario.Results: We found significant differences between women and men certified athletic trainers for the female and male athlete scenarios. Overall, women were more comfortable caring for female injuries and issues, whereas men were more comfortable caring for male injuries and issues. Certified athletic trainers reported more comfort overall than athletic training students. The most common underlying reason reported for discomfort in caring for female and male injuries and issues was experience level.Conclusions: Athletic training education programs should provide early and more deliberate experiences with injuries and issues of a more intimate nature, including those that are gender specific and non-gender specific. These experiences may increase athletic trainers'' level of comfort in providing care to athletes of the opposite sex.     

Pointwise‐constrained optimal control of a semiactive vehicle suspension

This article presents an optimal control strategy (OCS) for semiactive vehicle suspensions with road profile sensors. The suspension is modeled as a quarter‐car model with a magnetorheological (MR) damper. The OCS main objective is to minimize the fourth‐power acceleration of the sprung mass. In addition, three pointwise constraints of the model are taken into account when the optimal control problem is solved: suspension travel limits (upper and lower) and tyre vertical force. In order to deal with a large number of constraints, we implement the gradient optimization method based on the method of moving asymptotes routine, which shows very good performance reaching optimal controls while satisfying the constrains. The solution has been compared with two passive MR damper configurations (low and high damping) as well as Skyhook and Balance control strategies for three different road inputs. Results show that OCS fulfills the constraints and reduces the sprung mass acceleration peak and the root‐mean‐quad acceleration up to 59% , in comparison to passive strategies.