Evidence-based Approach to the Analysis of Serious Decompression Sickness with Application to EVA Astronauts PDF Download
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Author: Johnny Conkin
Publisher:
ISBN:
Category : Aviation medicine
Languages : en
Pages : 60
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Book Description
It is important to understand the risk of serious hypobaric decompression sickness (DCS) to develop procedures and treatment responses to mitigate the risk. Since it is not ethical to conduct prospective tests about serious DCS with humans, the necessary information was gathered from 73 published reports. We hypothesize that a 4-hr 100% oxygen (O2) prebreathe results in a very low risk of serious DCS, and test this through analysis. We evaluated 258 tests containing information from 79,366 exposures in altitude chambers. Serious DCS was documented in 918 men during the tests. A risk function analysis with maximum likelihood optimization was performed to identify significant explanatory variables, and to create a predictive model for the probability of serious DCS [P(serious DCS)]. Useful variables were Tissue Ratio, the planned time spent at altitude (Talt), and whether or not repetitive exercise was performed at altitude. Tissue Ratio is P1N2/P2, where P1N2 is calculated (N2) pressure in a compartment with a 180-min half-time for N2 pressure just before ascent, and P2 is ambient pressure after ascent. A prebreathe and decompression profile Shuttle astronauts use for extravehicular activity (EVA) includes a 4-hr prebreathe with 100% O2, an ascent to P2=4.3 lb per sq. in. absolute, and a Talt=6 hr. The P(serious DCS) is: 0.0014 (0.00096-0.00196, 95% confidence interval) with exercise and 0.00025 (0.00016-0.00035) without exercise. Given 100 Shuttle EVAs to date and no report of serious DCS, the true risk is less than 0.03 with 95% confidence (Binomial Theorem). It is problematic to estimate the risk of serious DCS since it appears infrequently, even if the estimate is based on thousands of altitude chamber exposures. The true risk to astronauts may lie between the extremes of the confidence intervals since the contribution of other factors, particularly exercise, to the risk of serious DCS during EVA is unknown. A simple model that only accounts for four important variables in retrospective data is still helpful to increase our understanding about the risk of serious DCS.
Author: Johnny Conkin
Publisher:
ISBN:
Category : Aviation medicine
Languages : en
Pages : 60
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Book Description
It is important to understand the risk of serious hypobaric decompression sickness (DCS) to develop procedures and treatment responses to mitigate the risk. Since it is not ethical to conduct prospective tests about serious DCS with humans, the necessary information was gathered from 73 published reports. We hypothesize that a 4-hr 100% oxygen (O2) prebreathe results in a very low risk of serious DCS, and test this through analysis. We evaluated 258 tests containing information from 79,366 exposures in altitude chambers. Serious DCS was documented in 918 men during the tests. A risk function analysis with maximum likelihood optimization was performed to identify significant explanatory variables, and to create a predictive model for the probability of serious DCS [P(serious DCS)]. Useful variables were Tissue Ratio, the planned time spent at altitude (Talt), and whether or not repetitive exercise was performed at altitude. Tissue Ratio is P1N2/P2, where P1N2 is calculated (N2) pressure in a compartment with a 180-min half-time for N2 pressure just before ascent, and P2 is ambient pressure after ascent. A prebreathe and decompression profile Shuttle astronauts use for extravehicular activity (EVA) includes a 4-hr prebreathe with 100% O2, an ascent to P2=4.3 lb per sq. in. absolute, and a Talt=6 hr. The P(serious DCS) is: 0.0014 (0.00096-0.00196, 95% confidence interval) with exercise and 0.00025 (0.00016-0.00035) without exercise. Given 100 Shuttle EVAs to date and no report of serious DCS, the true risk is less than 0.03 with 95% confidence (Binomial Theorem). It is problematic to estimate the risk of serious DCS since it appears infrequently, even if the estimate is based on thousands of altitude chamber exposures. The true risk to astronauts may lie between the extremes of the confidence intervals since the contribution of other factors, particularly exercise, to the risk of serious DCS during EVA is unknown. A simple model that only accounts for four important variables in retrospective data is still helpful to increase our understanding about the risk of serious DCS.
Author: Peter Skalfist
Publisher: Cambridge Stanford Books
ISBN:
Category : History
Languages : en
Pages : 160
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Book Description
Several project teams from NASA, ESA and other organizations have investigated the possibility of establishing a colony in orbit. They found that the Moon and near-Earth asteroids have enough materials available, that solar energy is readily available in large quantities. The advantages of this system are its proximity to the Earth and its lower escape velocity, which facilitates the exchange of goods and services.
Author: Daniel Mikelsten
Publisher: Cambridge Stanford Books
ISBN:
Category : History
Languages : en
Pages : 173
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Book Description
Asteroid mining is the exploitation of raw materials from asteroids and other minor planets, including near-Earth objects. Based on known terrestrial reserves, and growing consumption in both developed and developing countries, key elements needed for modern industry and food production could be exhausted on Earth within 50 to 60 years. In response, it has been suggested that platinum, cobalt and other valuable elements from asteroids may be mined and sent to Earth for profit, used to build solar-power satellites and space habitats, and water processed from ice to refuel orbiting propellant depots. Looking beyond the Milky Way, there are at least 2 trillion other galaxies in the observable universe. Space colonization can roughly be said to be possible when the necessary methods of space colonization become cheap enough to meet the cumulative funds that have been gathered for the purpose, in addition to estimated profits from commercial use of space. Intergalactic travel would either have to involve voyages lasting millions of years, or a possible faster than light propulsion method based on speculative physics, such as the Alcubierre drive. There are, however, no scientific reasons for stating that intergalactic travel is impossible in principle. Uploaded human minds or AI may be transmitted to other galaxies in the hope some intelligence there would receive and activate them.
Author: Vasil Teigens
Publisher: Cambridge Stanford Books
ISBN:
Category : History
Languages : en
Pages : 415
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Book Description
Although its roots lie in early rocket technologies and the international tensions that followed World War II, the space race began after the Soviet launch of Sputnik 1 on October 4, 1957. The space race became an important part of the cultural and technological rivalry between the USSR and the United States during the Cold War. Modern space exploration is reaching unbelievable areas. Mars is the focal point of space exploration. In the long term, there are tentative plans for manned orbital and landing missions to the Moon and Mars, establishing scientific outposts that will then give way to permanent and self-sufficient settlements. Additional exploration will potentially involve expeditions and settlements on other planets and their moons, as well as the establishment of mining and fueling outposts, particularly in the asteroid belt. Physical exploration outside the solar system will be robotic in the foreseeable future.
Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 636
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Author:
Publisher:
ISBN:
Category : Adaptation (Biology)
Languages : en
Pages : 628
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Author: Johnny Conkin
Publisher:
ISBN:
Category : Atmospheric pressure
Languages : en
Pages : 122
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Author: Laura A. Thompson
Publisher:
ISBN:
Category : Atmospheric pressure
Languages : en
Pages : 52
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Author: Michael R. Dobbs
Publisher: Elsevier Health Sciences
ISBN: 0323052606
Category : Medical
Languages : en
Pages : 729
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Book Description
Clinical Neurotoxicology offers accurate, relevant, and comprehensive coverage of a field that has grown tremendously in the last 20 years. You'll get a current symptomatic approach to treating disorders caused by neurotoxic agents, environmental factors-such as heavy metals and pesticides-and more. Apply discussions of cellular and molecular processes and pathology to clinical neurology. Leading authorities and up-and-coming clinical neurotoxicologists present their expertise on wide-ranging, global subjects and debate controversies in the specialty, including Gulf War Syndrome. And, Expert Consult functionality allows you to access the full text of the book online, from any Internet connection. Provides a complete listing of neurotoxic agents-from manufactured to environmental-so you get comprehensive, clinical coverage. Covers how toxins manifest themselves according to age and co-morbidity so that you can address the needs of all your patients. Offers broad and in-depth coverage of toxins from all over the world through contributions by leading authorities and up-and-coming clinical neurotoxicologists. Features discussion of controversial and unusual topics such as Gulf War Syndrome, Parkinson's Disease, motor neuron disease, as well as other issues that are still in question. Includes access to www.expertconsult.com, a companion website where you can quickly search the complete contents of the book. Your purchase entitles you to access the web site until the next edition is published, or until the current edition is no longer offered for sale by Elsevier, whichever occurs first. If the next edition is published less than one year after your purchase, you will be entitled to online access for one year from your date of purchase. Elsevier reserves the right to offer a suitable replacement product (such as a downloadable or CD-ROM-based electronic version) should online access to the web site be discontinued.
Author: Print&online
Publisher: Annual Reviews
ISBN: 9780824305543
Category : Medical
Languages : en
Pages : 646
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Book Description
