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News
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Aitor Coca, our former
project director and star research subject, completed his Ph.D. in June and is
now a post-doctoral fellow at the National Personal Protective Technology
Laboratory, CDC/NIOSH, Pittsburgh Pennsylvania. He can be reached at <acoca@cdc.gov>
Recent Publications:
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Koscheyev, V.S., Coca, A., & Leon, G.R.
(2007). Overview of
physiological principles to support thermal balance and comfort of
astronauts in open space and on planetary surfaces.
Acta
Astronautica, 60(4-7), 479-487.
Although
specialists have attempted to improve the space suit to provide better
protection in open space or on planetary surfaces, there has been a relative
lack of attention to features of human thermoregulatory processes that influence
comfort and therefore have an impact on the effectiveness of protective
equipment. Our findings showed that different body tissues transfer heat in/out
of the body in a different manner. There are also individual differences in
thermal transfer through body areas with different proportions of tissues;
therefore, data on the thermal profile of each astronaut needs to be used to
estimate the optimal body areas for heat/cold transfer in and out of the body in
an individually tailored cooling/warming garment. Principles for supporting
thermal comfort in space were formulated based on a series of studies to
evaluate the human body's response to uniform/nonuniform thermal conditions on
the body surface. We conclude that future space suit design and comfort support
of astronauts can be easier and more effective if these principles are
incorporated.
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Koscheyev, V.S., Leon, G.R., Coca, A., & Treviño, R.C.
(2006). Physiological design of a space suit cooling/warming garment and thermal
control as keys to improve astronaut comfort, performance and safety.
Habitation, 11, 15-25.
We describe our past and current program of research
focused on the application of physiological principles of heat transfer to
advance the effectiveness of space suits currently used by astronauts and for
future lunar or Mars missions. The output of these investigations is as follows:
1) a physiologically based more lightweight shortened liquid cooling/warming
garment (SLCWG) designed to increase effectiveness while minimizing circulating
water volume, flow rate, and energy consumption; 2) physiologically designed
warming gloves with tubing bypass to mitigate hand/finger discomfort and augment
heat delivery by blood flow; 3) augmentation of heat delivery by blood flow to
improve lower limb blood circulation and sustain comfort; 4) an adequate index
of thermal balance/imbalance and comfort with potential to initiate automatic
thermal feedback to an advanced spacesuit portable life support system.
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Koscheyev, V.S., Leon, G.R., Coca, A., Kim, J-H., & Treviño,
R.C. (2006). Informativeness of the finger temperature/heat flux as an index of
human thermal status under local cold influences. Proceedings of the 36th
International Conference on Environmental Systems. SAE Technical Paper Series
2006-01-2237. Warrendale, PA:SAE International.
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Introduction: Human
thermoregulation during EVA remains a challenge. The establishment
of a high correlation between the thermal status of the fingers and the
heat surplus/deficit in the body provides an index with potential to
more effectively monitor and control the astronaut’s thermal status.
This series of studies evaluated the changes in finger temperature (Tfing)
trajectories in conditions relevant to EVA. Methods: In different
experiments, subjects were donned in a liquid cooling/warming garment (LCWG)
that covered the full body surface except for the face and hands; they
wore either a physiologically designed warming glove or the Phase VI
glove. The experimental protocols were as follows: imposition of
temperature differences in the left and right gloves; different thermal
insulation levels of the gloves; sequential grasping of a highly cold
rail in different glove conditions; placement of the finger thermistor
on different sites of the finger. Results: The findings showed
that Tfing reflected body heat content irrespective of
differences in local cold within the gloves; local hand comfort was
highly dependent on total body heat content. The inclusion of a warming
glove within the Phase VI glove showed potential to enhance glove
function. Tfing readings informative about body heat
content were obtained by placing the sensor on the proximal phalanx of
the finger. Conclusions: This series of experiments has
application for enhancing the design of protective equipment for EVA,
and for more closely monitoring and controlling the thermal status of
the astronaut to judge thermal balance/imbalance of the body.
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Koscheyev, V.S., Leon, G.R.,
Coca, A., & Treviño, R.C. (2005). Redirection of biological heat from head to
fingers during a body cooling event. Aviation, Space, and Environmental
Medicine, 76, 828-832
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Introduction: Maintaining hand comfort in the cold
while sustaining optimal performance is still a challenge. There has been little
research on the efficacy of transporting biological heat from the head to the
hands to stabilize finger comfort, although there are notable temperature
differences between these two areas in the cold. Method: A tubing bypass between the head and the hands
was designed as an independent component in a liquid cooling/warming garment (LCWG).
Seven subjects (4 males, 3 females) were studied comparing finger temperature (Tfing)
change in two conditions: LCWG with additional bypass, and LCWG without bypass.
The protocol consisted of 3 stages: 1. comfort stabilization, LCWG inlet water
temperature 33oC, water in loop in bypass condition 23oC; 2. body cooling, LCWG
inlet water temperature 20oC; 3. rewarming, LCWG inlet water temperature 45oC.
Result: The time to reach the 25oC Tfing discomfort
criterion was significantly longer in the Bypass condition (p<0.01); Tfing was
significantly higher at the same time point when Tfing 25ºC was reached in the
Control condition (p<0.01). Conclusion: The incorporation of a bypass transferring
biological heat from a high to a low skin temperature area has potential to
improve local finger comfort and thus increase the time personnel can work in
cold environments.
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Koscheyev, V.S.,
Leon, G.R., & Coca, A. (2005). Finger heat flux/temperature as an indicator of
thermal imbalance with application for extravehicular activity. Acta
Astronautica, 57, 713-721
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The designation of a simple, non-invasive, and highly precise
method to monitor the thermal status of astronauts is important to enhance
safety during extravehicular activities (EVA) and onboard emergencies. Finger
temperature (Tfing), finger heat flux, and indices of core temperature (Tc)
[rectal (Tre), ear canal (Tec)] were assessed in 3 studies involving different
patterns of heat removal/insertion from/to the body by a multi-compartment
liquid cooling/warming garment (LCWG). Under both uniform and nonuniform
temperature conditions on the body surface, Tfing and finger heat flux were
highly correlated with garment heat flux, and also highly correlated with each
other. Tc responses did not adequately reflect changes in thermal balance during
the ongoing process of heat insertion/removal from the body. Overall, Tfing/finger
heat flux adequately reflected the initial destabilization of thermal balance,
and therefore appears to have significant potential as a useful index for
monitoring and maintaining thermal balance and comfort in extreme conditions in
space as well as on Earth.
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