Thursday, March 19, 2020
What Happens To The Human Body In A Vacuum
What Happens To The Human Body In A Vacuum As humans get closer to the time when astronauts and explorers will be living and working in space for long periods of time, a lot of questions arise about what it will be like for those who make their careers out there. There is a great deal of data based on long-duration flights by such astronauts as Mark Kelly and Peggy Whitman, but the life sciences experts at most space agencies need a lot more data to understand what will happen to future travelers. They already know that the long-term inhabitants aboard the International Space Station have experienced some major and puzzling changes to their bodies, some of which last long after they are back on Earth. Mission planners are using their experiences to help plan missions to the Moon, Mars, and beyond. Crew members on the International Space Station work with such technology as 3-D printers to understand how these and other technology can be used in space. This is a printer inside the Microgravity Science Glovebox aboard the station. NASA However, despite this priceless data from actual experiences, people also get a lot of non-valuable data from Hollywood movies about what its like to live in space. In those cases, drama usually trumps scientific accuracy. In particular, the movies are big on gore, especially when it comes to depicting the experience of being exposed to vacuum. Unfortunately, those movies and TV shows (and video games) give the wrong impression about what its like to be in space. Vacuum in the Movies In the 1981 movie Outland, starring Sean Connery, there is a scene where a construction worker in space gets a hole in his suit. As the air leaks out, the internal pressure drops and his body is exposed to a vacuum, we watch in horror through his faceplate as he swells up and explodes. Could that really happen, or was that dramatic license? A somewhat similar scene occurs in the 1990 Arnold Schwarzenegger movie, Total Recall. In that movie, Schwarzenegger leaves the pressure of the habitat of a Mars colony and begins to blow up like a balloon in the much lower pressure of the Mars atmosphere, not quite a vacuum. He is saved by the creation of an entirely new atmosphere by an ancient alien machine. Again, could that happen, or was dramatic license at play? Those scenes bring up an entirely understandable question: What happens to the human body in a vacuum? The answer is simple: it wont blow up. The blood wont boil, either. However, it will be a quick way to die if an astronauts spacesuit is damaged. What Really Happens in a Vacuum There are a number of things about being in space, in a vacuum, that can cause harm to the human body. The unfortunate space traveler wouldnt be able to hold their breath for long (if at all), because it would cause lung damage. The person would probably remain conscious for several seconds until the blood without oxygen reaches the brain. Then, all bets are off. The vacuum of space is also pretty darn cold, but the human body doesnt lose heat that fast, so a hapless astronaut would have a little time before freezing to death. Its possible that they would have some problems with their eardrums, including a rupture, but maybe not. Being marooned in space exposes the astronaut to high radiation and the chances for a really bad sunburn. Their body might actually swell some, but not to the proportions so dramatically shown in Arnold Schwarzeneggers movie, Total Recall. The bends are also possible, just like what happens to a diver who surfaces too quickly from a deep underwater dive. That condition is also known as decompression sickness and happens when dissolved gases in the bloodstream create bubbles as the person decompresses. The condition can be fatal and is taken seriously by divers, high-altitude pilots, and astronauts. Astronauts train extensively underwater on Earth, wearing pressure suits, to simulate working in space. NASA/Johnson Space Center. While normal blood pressure will keep a persons blood from boiling, the saliva in their mouth could very well begin to do so. Theres actually evidence for that happening from an astronaut who experienced it. In 1965, while performing tests at the Johnson Space Center, a subject was accidentally exposed to a near vacuum (less than one psi) when his space suit leaked while in a vacuum chamber. He did not pass out for about fourteen seconds, by which time unoxygenated blood had reached his brain. Technicians began to repressurize the chamber within fifteen seconds and he regained consciousness at around the equivalent of 15,000 feet of altitude. He later said that his last conscious memory was of the water on his tongue beginning to boil. So, theres at least one data point about what its like to be in a vacuum. It wont be pleasant, but it wont be like the movies, either. There have actually been cases of parts of astronauts bodies being exposed to vacuum when suits were damaged. They survived due to quick action and safety protocols. The good news from all those experiences is that the human body is amazingly resilient. The worst problem would be lack of oxygen, not lack of pressure in the vacuum. If returned to a normal atmosphere fairly quickly, a person would survive with few if any irreversible injuries after an accidental exposure to vacuum. More recently, astronauts on the International Space Station found an air leak from a hole made by a technician on the ground in Russia. They were in no danger of losing their air right away, but they had to go to some effort to get it plugged safely and permanently. Edited and updated by Carolyn Collins Petersen.
Tuesday, March 3, 2020
Understanding French Stressed Pronouns
Understanding French Stressed Pronouns Stressed pronouns, also known as disjunctive pronouns, are used to emphasize a noun or pronoun that refers to a person. There are nine forms in French. Please see the table at the bottom of the page. French stressed pronouns correspond in some ways to their English counterparts, but are very different in other ways. Note that the English translations sometimes require different sentence structures altogether. Stressed pronouns are used in the following ways in French: I. To emphasize nouns or pronouns (accent tonique)    - Je pense quil a raison.    - Moi, je pense quil a tort.    - Je ne sais pas, moi.    - I think hes right.    - I think hes wrong.    - I dont know. II. After cest and ce sont (accent tonique)    Cest toi qui à ©tudies lart.    Youre the one whos studying art.    Ce sont elles qui aiment Paris.    They love Paris. III. When a sentence has more than one subject or object   Michel et moi jouons au tennis.    Michael and I are playing tennis.   Toi et lui, vous à ªtes trà ¨s gentils.    You and he are very kind.   Je les ai vus, lui et elle.    I saw him and her. IV. To ask and answer questions    - Qui va la plage ?    - Lui.    - Who is going to the beach?    - He is.    Jai faim, et toi?    Im hungry, and you? V. After prepositions    Vas-tu manger sans moi?    Are you going to eat without me?    Louis habite chez elle.    Louis lives at her house. VI. After que in comparisons    Elle est plus grande que toi.    She is taller than you (are).    Il travaille plus que moi.    He works more than I (do). VII. With emphatic words like aussi, non plus, seul, and surtout    Lui seul a travaillà © hier.    He alone worked yesterday.    Eux aussi veulent venir.    They want to come too. VIII. With -mà ªme(s) for emphasis   Prà ©pare-t-il le dà ®ner lui-mà ªme?    Is he making dinner himself?   Nous le ferons nous-mà ªmes.    Well do it ourselves. IX. With the negative adverb ne...que and conjunction ne...ni...ni   Je ne connais que lui ici.    Hes the only one I know here.    Ni toi ni moi ne le comprenons.    Neither you nor I understand it. X. After the preposition to indicate possession   Ce stylo est moi.    This pen is mine.   Quel livre est toi?    Which book is yours? XI. With certain verbs that dont allow a preceding indirect object pronoun   Je pense toi.    Im thinking of you.    Fais attention eux.    Pay attention to them. Note: Soi is used for unspecified persons. Would you like to test your skills with French stressed pronouns? English French me moi you toi him lui her elle oneself soi us nous you vous them (masc) eux them (fem) elles How to Use the French Pronoun Soi Soi is one of the most often misused French pronouns. Its the third person indefinite stressed pronoun, which means that it is used only for unspecified persons; i.e., with an indefinite pronoun or impersonal verb. Soi is equivalent to one or oneself, but in English, we usually say everyone instead.    On va chez soi.   Everyone is going (to his or her respective) home.    Chacun pour soi.   Every man for himself.    Il faut avoir confiance en soi.   One should have confidence in oneself (in him/herself).    Tout le monde doit le faire soi-mà ªme.   Everyone has to do it him/herself. Some French students get confused between soi-mà ªme and lui-mà ªme. If you remember that soi can only be used for unspecified persons, you should be ok.   Il va le faire lui-mà ªme.   Hes going to do it himself.   On va le faire soi-mà ªme.   Everyone is going to do it him/herself.
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