Subjective responses to display bezel characteristics

High quality flat panel computer displays (FPDs) with high resolution screens are now commonplace, and black, grey, white, beige and silver surrounds (‘bezels’), matt or glossy, are in widespread use. It has been suggested that bezels with high reflectance, or with a high gloss, could cause eyestrain, and we have investigated this issue. Twenty office workers (unaware of the study purpose) used six different FPDs, for a week each, at their own desk. These displays were identical apart from the bezel colour (black, white or silver) and shininess (matt or glossy). Participants completed questionnaires about their visual comfort at the end of each week, and were fully debriefed in lunch-time focus groups at the end of the study. For the white and the silver bezels, the glossiness of the bezel was not an issue of concern. The participants were significantly less content with the glossy black surround than with the matt black surround, and in general the glossy black bezel was the least-liked of all those used. With the possible exception of this surround, there was no evidence of significantly increased visual discomfort, indicative of eyestrain, as a result of high or low bezel reflectance, or of high glossiness

The evaluation of medical devices with healthy people?

Much of the research of thermal and physical comfort is completed with healthy participants in regular life scenarios. The translation of these findings into clinical settings for people with disease, deficiency or restrictions adds a level of complexity. As an example this study evaluated the effectiveness of a patient warming mattress device on body temperature and ratings of thermal comfort/sensation. Hypothermia has been linked to higher mortality rates in trauma patients admitted to hospital. Patient warming devices have been developed to assist the temperature of the patient and studies on these report varied effects. Laboratory trials with shivering inhibition (Goheen et al, 1997, Greif et al, 2000) found improvements from forced air and resistive blankets but without shivering inhibition (Williams et al, 2005) showed no benefit in warming from 35°C. A physical evaluation of the warming mattress device with a thermal manikin reported an energy contribution to the user (~70W). To support the physical evaluation a user trial was conducted. Nine healthy volunteer participants (27.78+4.99 Years) were exposed to three conditions using a repeated measures counterbalanced design. The participants were cooled in an environment with an air temperature of 0°C (60 minutes) then exposed to 30 minutes of a warming intervention. 1.Hot mattress HM. Mattress preheated to 18°C, under standard blankets 2.Warmed mattress WM. Mattress turned on at start of warming period, under standard blankets 3.Cold mattress CM. Control condition, no power to mattress, under standard blankets. During the cooling phase, aural and mean skin temperature (Tsk) significantly decreased for all conditions (p<0.01). Tsk increased following each warming intervention but aural temperature continued to decline. Significant increase in overall mean thermal comfort was seen during the first ten minutes of the warming phase for HM in comparison to CM and WM (p<0.05) but not at 20 and 30 minutes. This was mirrored by the overall mean thermal sensation rating across the same timeframe. HM increased thermal sensation from very cold to cool with CM and WM showing and increase from very cold to cold. This study revealed the effect of the device (HM) gave short term comfort and sensation gains at the start of the warming phase but the passive insulation provided (CM) also allowed re-warming to occur. This was the expected thermoregulatory response for a group of healthy participants. This group does not necessarily represent the hospital population with pathology that inhibits their normal responses to cold, e.g. circulatory shut-down, shock or trauma. For accurate application, the trial data needs to be closely matched with the limitations of the health condition in the target population. The challenge is now to explore the relationship between data from healthy cohorts and how that can be used for groups of patients with known physical and physiological conditions and limitations. The validity of a patient’s subjective assessment of their condition lying in a hospital bed is currently unclear. Evidence needs to show whether a patient in a hospital bed can accurately report joint position, thermal comfort, skin wettedness, pressure points etc to assist in the management of their condition

Human wetness perception in relation to textile water absorption parameters under static skin contact

Skin-wetness-perception (WP) greatly affects thermal and sensorial discomfort in clothing and as such is of great interest to the clothing industry. Following neurophysiological studies of WP, this study looks at textile parameters affecting WP. Twenty-four fabrics, varying in thickness, fibre-type and absorption capacity were studied. Using twelve participants (males/females), the WP induced was studied in four wetness states: 1:Dry; 2:ABS, all having the same absolute water content of 2400μl per sample (= 0.024μl·mm-2); 3:100REL, saturated with water to their individual absorption capacity; 4:50REL, to 50% of the value in 3. As total absorption capacity was highly correlated (r=0.99) to fabric thickness, condition 3 and 4 were equivalent to having the same water content per volume of textile, i.e. 0.8 and 0.4μl·mm-3 respectively. Samples were applied to the upper back, statically to minimise the contribution of surface roughness/friction. WP was highly correlated to drop in skin temperature induced by the wet fabric, and increased with application pressure of the fabric. No effect of fibre-type was observed. In REL, with equal μl·mm-3, WP showed a positive correlation to total fabric watercontent-per-area (μl·mm-2), and thus also to thickness, given the correlation between the latter two, with saturation above 1.5μl·mm-2. In ABS on the other hand, with equal μl·mm-2, and thus with relative water content (μl·mmμl·mm-3) inversely proportional to thickness, WP was also inversely proportional to thickness. Thus WP showed opposing responses depending on the wetting type, indicating that the methodology of manipulating water content should be selected in relation to the product end-use

The effects of combined arterial de-oxygenation and systemic cooling on the rate of muscular fatigue development

Cooling and fatigue are known to have similar effects on muscle performance and physiology [1]. Studies have shown a significantly increased rate of fatigue development during both low, and high intensity work [2, 3]. Numerous researchers have also reported that acute hypoxemia exaggerates the rate of fatigue development, centrally [4, 5, 6, 7] and peripherally [7, 8, 9, 10, 11, 12]. While abundant research exists on cold and hypoxic stressors separately, the interactive effects of combined exposure on the rate of muscle fatigue development remains unexamined. We hypothesised that relative to baseline performance levels, independent exposure to arterial de-oxygenation and systemic cooling will induce a significant increase on post exercise fatigue, compared to values observed during thermoneutral normoxia. During combined hypoxic-cold exposure, we expected a significant synergistic interaction on post exercise fatigue, with peripheral blood flow reductions during cold accentuating the fatiguing effect of low arterial oxygenation

The interactive effect of cooling and hypoxia on forearm fatigue development

Purpose: To examine the effect of separate and combined exposure to hypoxia [normoxia (FIO2 = 0.21) vs. moderate altitude (FIO2 = 0.13)] and temperature [thermoneutral (22 °C) vs. cold (5 °C)] on muscle fatigue development in the forearm, after repeated low-resistance contractions. Methods: Eight males were exposed for 70 min to four separate conditions in a balanced order. Conditions were normoxic-thermoneutral (N), hypoxic-thermoneutral, normoxic-cold and hypoxic-cold. After 15-min seated rest, participants carried out intermittent dynamic forearm exercise at 15 % maximal isometric voluntary contraction (MVC) for eight consecutive, 5-min work bouts. Each bout was separated by 110 s rest during which MVC force was collected. Results: When exposed to hypoxia and cold independently, the exercise protocol decreased MVC force of the finger flexors by 8.1 and 13.9 %, respectively, compared to thermoneutral normoxia. When hypoxia and cold were combined, the decrease in MVC force was 21.4 % more than thermoneutral normoxia, reflecting an additive effect and no interaction. EMG relative to force produced during MVC, increased by 2 and 1.2 μV per kg (36 and 23 % of N) for cold and hypoxia, respectively. When the stressors were combined the effect was additive, increasing to 3.1 μV per kg (56 % of N). Conclusion: When compared to exercise in thermoneutral normoxic conditions, both cold and hypoxia significantly reduce brief MVC force output. This effect appears to be of mechanical origin, not a failure in muscle fibre recruitment per se. Additionally, the reduction in force is greater when the stressors are combined, showing an additive effect

Human thermal sensitivity: A methodological comparison

Human thermal sensitivity: A methodological compariso

The role of decreasing contact temperatures and skin cooling in the perception of skin wetness

Cold sensations are suggested as the primary inducer of the perception of skin wetness. However, limited data are available on the effects of skin cooling. Hence, we investigated the role of peripheral cold afferents in the perception of wetness. Six cold-dry stimuli (producing skin cooling rates in a range of 0.02 to 0.41°C/s) were applied on the forearm of 9 female participants. Skin temperature and conductance, thermal and wetness perception were recorded. Five out of 9 participants perceived wetness as a result of cold-dry stimuli with cooling rates in a range of 0.14 to 0.41°C/s, while 4 did not perceive skin wetness at all. Although skin cooling and cold sensations play a role in evoking the perception of wetness, these are not always of a primary importance and other sensory modalities (i.e. touch and vision), as well as the inter-individual variability in thermal sensitivity, might be equally determinant in characterising this perception

Sweat distribution and perceived wetness across the human foot [Abstract]

Sweat distribution and perceived wetness across the human foot [Abstract

Body mapping of thermal sensitivity to skin wetness across the torso

Humidity receptors have never been identified on human skin and the ability to perceive skin wetness has been suggested to rely on the sensory inputs arising from thermal cold afferents. However, limited data are available on how thermal afferents and their regional distribution influence the perception of wetness. PURPOSE: Given the regional variability in thermal sensitivity across the torso, here we examined whether regional differences in the sensitivity to wetness exist

Individual and combined impact of hypoxia and acute inorganic nitrate ingestion on autonomic thermoregulatory responses to the cold [Abstract]

No description supplie