Respiratory system

Basic types of respiratory structures

Ventricles of the Brain
The term triage may have originated during the Napoleonic Wars from the work of Dominique Jean Larrey. Expressed as a percentage, rejection is defined as: This article is about the concept of triage as it occurs in medical emergencies and disasters. Similar issues may occur for paramedics in the field in the earliest stages of mass casualty incidents when large numbers of potentially serious or critical patients may be combined with extremely limited staffing and treatment resources. Basically, what he does is squeeze my lip until the puss comes out and helps it sometimes on the way out. So forget those slow masses, the conventional designers, marketers, and columnists stuck in the old-paradigm thinking; leave it to the new-paradigm guitarists and designers, who are reality-based and recognize their desires, their actual practice, and the solutions aimed at those real-world practices.


Bowel resection

Cut, no flesh removed describes a practice known as nicking or pricking, which currently is categorized as Type IV. And sewn closed corresponds to Type III, infibulation. For the years and country profiles: In Abusharaf, Rogaia Mustafa.

University of Pennsylvania Press. Bagnol, Brigitte; Mariano, Esmeralda The Oxford Dictionary of the Jewish Religion. British Crusades in Colonial Sudan. Wombs and Alien Spirits: University of Wisconsin Press. Why Aren't Jewish Women Circumcised? Gender and Covenant In Judaism. University of California Press.

El Guindi, Fadwa El Dareer, Asma Woman, Why Do You Weep: The Female Circumcision Controversy: Hosken, Fran []. The Missionary Movement in Colonial Kenya: The Foundation of Africa Inland Church. Greek Papyri in the British Museum. The Beginning of the End". Female "Circumcision" in Africa: Archived from the original PDF on 29 October Mandara, Mairo Usman View of Nigerian Doctors on the Medicalization Debate". Culture Controversy and Change.

Sex and Social Justice. New York and Oxford: In James, Stanlie M. Genital Cutting and Transnational Sisterhood. University of Illinois Press. Female Circumcision and Clitoridectomy in the United States: A History of a Medical Treatment.

University of Rochester Press. In Borch, Merete Falck. Language and Translation in Postcolonial Literatures. Journal of Medical Ethics. WHO collaborative prospective study in six African countries". Berer, Marge 30 June It's female genital mutilation and should be prosecuted". Health Care for Women International. Black, John July Journal of the Royal Society of Medicine. Elchalal, Uriel; Ben-Ami, B. Essén, Birgitta; Johnsdotter, Sara July Acta Obstetricia et Gynecologica Scandinavica.

Archived from the original PDF on 14 April International Journal of Epidemiology. BMJ Clinical research ed. Gallard, Colette 17 June Gruenbaum, Ellen September—October Research Findings, Gaps, and Directions".

Hayes, Rose Oldfield 17 June Carey; Teklemariam, Mamae 19 January New England Journal of Medicine. Iavazzo, Christos; Sardi, Thalia A. Archives of Gynecology and Obstetrics.

Ismail, Edna Adan Edna Adan University Hospital. Studies in Family Planning. Johnsdotter, Sara; Essén, Birgitta May Archived from the original PDF on 21 September Who is at risk in the U. Public Health Reports Washington, D. Kelly, Elizabeth; Hillard, Paula J. Current Opinion in Obstetrics and Gynecology. Khazan, Olga 8 April The Journal of Sex Research. Knight, Mary June Some remarks on the practice of female and male circumcision in Graeco-Roman Egypt".

Kool, Renée; Wahedi, Sohail 15 April A Comparative Law Perspective". Mandara, Mairo Usman March International Journal of Gynaecology and Obstetrics. Mackie, Gerry December Mackie, Gerry June Journal of Religion in Africa. Reviews in Obstetrics and Gynecology. Annals of Medical and Health Sciences Research. Zeitschrift für Ägyptische Sprache und Altertumskunde. Reisel, Dan; Creighton, Sarah M.

Rodriguez, Sarah July American medicine and female sexuality in the late nineteenth century". Journal of the History of Medicine and Allied Sciences. Rushwan, Hamid September A tragedy for women's reproductive health". African Journal of Urology.

Isaac Baker Brown and his harmless operative procedure". Shell-Duncan, Bettina June Female Genital Cutting and the Politics of Intervention". International Journal of Gynaecology and Obstetrics: Toubia, Nadia 15 September The New England Journal of Medicine. Wakabi, Wairagala 31 March A cross-sectional study from Erbil city". Stanley; Khan, Shane March Cappa, Claudia, et al. United Nations Children's Fund, July Classification of female genital mutilation , Geneva: World Health Organization, Eliminating Female genital mutilation: An Interagency Statement , Geneva: World Health Organization, January A Global Concern , New York: United Nations Children's Fund, February A Teachers' Guide , Geneva: What Might the Future Hold?

Intensifying global efforts for the elimination of female genital mutilations" , United Nations General Assembly, adopted 20 December Izett, Susan; Toubia, Nahid.

An Overview , Geneva: Accelerating Change , Annual report , New York: Mackie, Gerry ; LeJeune, John. Miller, Michael; Moneti, Francesca. Changing a harmful social convention: Moneti, Francesca; Parker, David.

The Dynamics of Social Change , Florence: Clitoridectomy Dysmenorrhea Dyspareunia Gishiri cutting Husband stitch Infibulation Keloid scars Pelvic inflammatory disease Rectovaginal fistula Vesicovaginal fistula. Female genital mutilation Activists against female genital mutilation.

Abuse during childbirth Acid throwing Breast ironing Bride burning Bride buying Dating abuse Domestic violence outline management and pregnancy Dowry death Eve teasing Honor killing Female genital mutilation Gishiri cutting Infibulation Husband stitch Female infanticide Femicide Foot binding Force-feeding Forced abortion Forced marriage Forced pregnancy Forced prostitution Human trafficking Murder of pregnant women Raptio Sati Violence against prostitutes.

Sexual assault Campus sexual assault Mass sexual assault Rape and pregnancy laws Types of rape by deception corrective date gang genocidal in war marital prison statutory Sexual slavery Sexual violence. Prosecution of gender-targeted crimes November 25th February 6th Serial rapist. Distortion and power-tube saturation voicing: John Murphy, chief engineer for Carvin Corp.

Once you have a well-behaved clipper -- even if it's just simple diodes, as in the stomp boxes -- it is the precise combination of pre- and post-clipping EQ that mostly determines how an amp sounds.

The 'secret' of the best sounding guitar amps lies in the pre-clipping EQ response curve. Pre-distortion equalization Controlling guitar EQ, central EQ, and cabinet EQ Getting more treble in the post-amp stage via speakers Tone control circuits Table of parametric-EQ settings to produce various EQ curves 3-band eq needed on electric guitars, pickup response curves needed Selecting Pickups Distortion voicing.

Modelling amps Online research page for "amp modelling" or "modelling amps". Analog controlled, discrete solid-state modelling amps: Tech 21 - Trademark 60, Trademark Digitally controlled discrete solid-state modelling amps: Peavey - Transformer solid-state modelling amp Fender - Cyber-Twin. Digitally controlled DSP-algorithm modelling amps: Designers should incorporate an actual power tube not 12AX7 and dummy load in the signal processing stage, perhaps using Power Scaling to run the tube cool.

Practical ways to get authentic, authoritative cranked-amp tone with minimal noise leakage The ideal approach is to create a permanent setup of a double-layered guitar speaker isolation cabinet in another room, or a super-insulated closet in another room. The most ideal would be a small massive concrete or brick room with inner insulation on the surfaces.

Purchase one or two guitar speakers dedicated to this isolation booth and one or two guitar-cab mics dedicated to this isolation booth. The ideal is a booth large enough to roll in a 4x12 cab and mic setups, with breathing room for the speakers. These form an abstract transducer processing module, converting a high-power signal as the input signal, to a complexly smoothed and complexly distorted multimiked output signal which you can then blend and equalize at the mixer.

Be sure to put an equalizer on either side of this speaker-mic transducer processing module: A minimal approach is to place an isolation box over a miked combo amp in the same room or put the miked combo or cab in a closet as a makeshift iso booth.

Best is a many-layer isolation booth in a distant room. It is a practical idea to keep a good power attenuator such as the THD Hot Plate in between whatever amplifier you use to drive the guitar speaker, and the guitar speaker. This can be used to incrementally reduce the volume late at night alas, reducing the amount of highly desirable, even though subtle, speaker distortion.

A power attenuator also enables using a watt amp to drive a watt guitar speaker without blowing up the speaker too soon. You should purchase extra guitar speakers, because speakers are like tubes and guitar strings: You can also use a muffled guitar speaker without a cab or mics, or in a face-down cab, just to load the amp -- but the Weber MASS may be a less expensive and more ergonomic solution; it's a power attenuator using an actual guitar speaker, without surface, as the dummy load component.

It has tone controls on the line-level Out jack. For a further tonal compromise, using no actual guitar speakers, but still obtaining power-tube saturation, use a dummy load then a guitar speaker cab simulator. Circuit using a preamp tube as a low-watt power tube Amp modelling is an advance but need to integrate a power tube interacting with speakers So far, no single product combines a low-watt power tube with full processing, for ideal DI Power-tube redesign of multieffects processors Quiet power tube saturation: Tube preamp, low-watt power tube, solid-state power amp Low-wattage power tube saturation; Fretlight and computer-augmented jamming.

Speakers Speakers Speaker clank and the "physical" sound The importance of using an actual guitar speaker; the need for speaker articles Balancing speaker power handling capacity and amp Speaker specs. Good rock tone requires hard-driven speakers, not direct-to-console.

Amp or cabinet isolation booths, control room isolation, and speaker isolation cabinets. The Tone Engine concept integrated speaker isolation cabinet. Extra gear required for a speaker isolation cabinet rig. Speaker isolation cabinet vs. Most companies misrepresent the efficacy of their isocab, should warn that they leak bass, and should offer an outer box as well, perhaps as a kit. A hybrid isobox might produce the desired sound at truly private levels by integrating a power attenuator and 6" guitar speaker.

Double-layered, nonresonant, multi-miked speaker isolation cabinet, 10" spk. Euphonic Audio - Rumble Seat - designed for bass. Folded Space Micro Room - 6" 5-watt speaker, built-in power attenuator. Building an attenuation cab.

Comparison table for power-tube saturation products - major page, several years out of date Variable-wattage amps. Categorization of below amps is best estimate based on information gathered so far.

In the past, amps called the first control Gain and the 2nd Volume, but that Volume knob ought to be renamed to "Power Tube Distortion Intensity" and a 3rd knob be added, called Volume or Power Scale. In a conventional amp that's run with a power attenuator, the so-called "Master Volume" no longer primarily acts as a listening-volume controller; it is forced to behave instead as a distortion-voicing control, with the power attenuation knob now servicing as the real listening-volume controller.

As guitarists move to dialing-in more of their tone through the power-tube stage, 2- or 3-channel amp designers will need to move or extend their "channels" to include parameter changes in the power-amp stage.

A 2-channel amp now needs a 2-channel power amp in a certain sense with two separate Scale controls, to switch between combinations of preamp distortion and power tube saturation at selected volumes. Maven Peal - Zeeta amp with variable wattage and Sag circuit - 1-watt lowest limit on volume.

Rhino Amps ext - some models use Power Scaling, mainly high-gain amps for Metal. I surmise that their implementation of Power Scaling was poorly done, wasn't licensed from L. Mojave Ampworks - Peacemaker, Scorpion, Coyote, Sidewinder, Plexi 45, and all future Mojave amps ext - has Power Dampening, a kind of Power Scaling that doesn't use solid-state to control plate voltage.

There is even what I consider a recall of the old-paradigm models to retrofit what all amps ought to have, the new-paradigm equivalent of Master Volume. We are now offering the Mojave Peacemaker and Scorpion with an adjustable power level that still has our exact Mojave tone. The amp still has the clarity, definition, good brightness and authoritative bass response at near bedroom levels or where ever you choose the amp to be set volume wise. This is a new feature that will be found on all Scorpions and Peacemakers models.

We also offer this Mod for all Peacemaker and Scorpion users so no one is left behind. We are adding it to the Coyote as well. That's how you know they're working. But I know what you mean — when I first moved out to Titan, it took me a good month to get used to 'em.

I was up all night most nights hearing chimes all over the hab ringing. It was like this constant drone with a few off notes every now and then to make sure you didn't relax.

I complained to anybody who'd listen, which was nobody. All I did was get myself a rep as another dumb groundhog fresh off the boat. The chimes didn't just bother me at night, either. In public spaces they make quiet conversation just about impossible. And I just about failed my first semester in school from being distracted.

Seriously, if I hadn't still been under Immigrant's Probation, I would have had to do a public service sentence. As it was, I did have to take the Habitat Orientation class again — listening to the damned wind chimes the whole time. But let me tell you — They were absolutely right to bust me. They confiscated my ear buds when I got caught so I didn't have them during a weekend maintenance cycle on the hab.

We were living in a retired Trans-Chronian, the kind they used to have before the River -class came out. The counter-spinning rings were always breaking down or getting fatigued or some damn thing, so we only had gravity maybe five days a week. My little sisters loved it — I'd play catch with them, with the toddler standing in as the ball. Anyway, the apartment had only pair of rooms, and my parents got one and the girls the other.

I slept in a bag in the living room and lived out of a foot locker. One night I woke up from a dead sleep with the uncontrollable feeling that something was wrong. I couldn't put my finger out what it was, but the effect was disturbing.

I figured that I was just having trouble sleeping from the wind chimes when I realized that was what was wrong — I wasn't hearing the chimes.

A glance up told me that the chimes in the living room were still going, but I really didn't need it. The sound of all the chimes in our apartment had gotten so far under my skin over the weeks we'd been living there that I pretty much figured out immediately which chimes had stopped.

You guessed it — the girls' room. By the time I got in there they were both awake and holding hands while spinning like they teach you. My parents were in there a couple seconds after me, but only because they had farther to go. Anyway, it was nothing much as vent problems go. A stuffed rabbit toy had gotten jammed into the fan — so the girls got grounded and had to do extra chores for a week.

They whined about it, and kids do, and then we all went back to bed. It took a me good while to go back to sleep after that. For all I my complaining about those annoying, distracting, aggravating wind chimes, if we didn't have 'em up that night my sisters would have never have woken up.

Yeah, Fireproof is another absolute classic from grand-master Hal Clement. And it hammers home a hard truth you can find in Lazarus Long's notebooks. On Terra, being ignorant shortens your lifespan. Being willfully ignorant is just asking for it. And being willfully ignorant in space means you are doing your darndest to cop a Darwin Award.

You don't just need a good education to get a job in space, you need so you don't die. Read how that moron saboteur Hart thinks education is a waste of time. Up to when his flaming body gets splattered all over the wall because he thinks he's so smart. He thinks Nah, I don't need no stinkin' physics and chemistry!

That's the last thing that goes through his brain, besides the bulkhead. If Igno-Spy had ever had a high-school Science class he might have realized he was turning the inside of his jail cell into a freaking free-fall thermobaric weapon.

With him flicking his Bic at the fuse like Wile E. To conserve his oxygen supply, the curly-haired cadet had set the controls of his boat on a steady orbit around one of the larger asteroids and lay down quietly on the deck.

One of the first lessons he had learned at Space Academy was, during an emergency in space when oxygen was low, to lie down and breath as slowly as possible. And, if possible, to go to sleep. Sleep, under such conditions, served two purposes. While relaxed in sleep, the body used less oxygen and should help fail to arrive, the victim would slip into a suffocating unconsciousness, not knowing if and when death took the place of life.

Unpleasant odors in the air is a problem, but there is not much one can do about it. After all, you can't just open up a window to let in some fresh air, not in the vacuum of space. NASA carefully screens all materials, sealants, foods, and everything else to ensure that they do not emit noticeable odor in the pressurized habitat sections of spacecraft and space stations. Such odors can quickly become overpowering in such tight quarters. There's a fortune awaiting the man who invents a really good deodorizer for a spaceship.

That's the one thing you can't fail to notice. Oh, they try, I grant them that. The air goes through precipitators each time it is cycled; it is washed, it is perfumed, a precise fraction of ozone is added, and the new oxygen that is put in after the carbon dioxide is distilled out is as pure as a baby's mind; it has to be, for it is newly released as a by-product of the photosynthesis of living plants.

That air is so pure that it really ought to be voted a medal by the Society for the Suppression of Evil Thoughts. Besides that, a simply amazing amount of the crew's time is put into cleaning, polishing, washing, sterilizing - oh, they try! But nevertheless, even a new, extra-fare luxury liner like the Tricorn simply reeks of human sweat and ancient sin, with undefinable overtones of organic decay and unfortunate accidents and matters best forgotten.

Once I was with Daddy when a Martian tomb was being unsealed - and I found out why xenoarchaeologists always have gas masks handy. But a spaceship smells even worse than that tomb. It does no good to complain to the purser. He'll listen with professional sympathy and send a crewman around to spray your stateroom with something which I suspect merely deadens your nose for a while.

But his sympathy is not real, because the poor man simply cannot smell anything wrong himself. He has lived in ships for years; it is literally impossible for him to smell the unmistakable reek of a ship that has been lived in - and, besides, he knows that the air is pure; the ship's instruments show it. None of the professional spacers can smell it. But the purser and all of them are quite used to having passengers complain about the "unbearable stench" - so they pretend sympathy and go through the motions of correcting the matter.

Not that I complained. I was looking forward to having this ship eating out of my hand, and you don't accomplish that sort of coup by becoming known first thing as a complainer. But other first-timers did, and I certainly understood why - in fact I began to have a glimmer of a doubt about my ambitions to become skipper of an explorer ship. But - Well, in about two days it seemed to me that they had managed to clean up the ship quite a bit, and shortly thereafter I stopped thinking about it.

I began to understand why the ship's crew can't smell the things the passengers complain about. Their nervous systems simply cancel out the old familiar stinks - like a cybernetic skywatch canceling out and ignoring any object whose predicted orbit has previously been programmed into the machine. But the odor is still there. I suspect that it sinks right into polished metal and can never be removed, short of scrapping the ship and melting it down. Thank goodness the human nervous system is endlessly adaptable.

His hole was on the eighth level, off a residential tunnel a hundred meters wide with fifty meters of carefully cultivated green park running down the center.

The main corridor's vaulted ceiling was lit by recessed lights and painted a blue that Havelock assured him matched the Earth's summer sky. Living on the surface of a planet, mass sucking at every bone and muscle, and nothing but gravity to keep your air close, seemed like a fast path to crazy.

The blue was nice, though. Some people followed Captain Shaddid's lead by perfuming their air. Not always with coffee and cinnamon scents, of course. Havelock's hole smelled of baking bread. Others opted for floral scents or semipheromones. Candace, Miller's ex-wife, had preferred something called EarthLily, which had always made him think of the waste recycling levels. These days, he left it at the vaguely astringent smell of the station itself.

Recycled air that had passed through a million lungs. The circle of life on Ceres was so small you could see the curve. He liked it that way. Infinitely more serious than annoying odors are harmful atmospheric contaminants. They share the same problem that a spacecraft cannot open the windows to bring in some fresh air.

But unlike odors, these can harm or kill. Basic atmospheric monitors will keep an eye on the breathing mix inside the habitat module for oxygen and carbon dioxide levels.

But prudent spacecraft will have monitors for carbon monoxide and other deadly gases, hooked up to strident alarms. In space no one can hear you scream, but in the habitat module's atmosphere everybody can hear that high-pitched squeaky wheel in the ventilator. And there may be permanent hearing loss from loud noises, say, from rocket engines. As a point of reference, the normal ambient noise level on the International Space Station is 60 db. Acoustic criteria are specified in terms of A-weighted sound level L A or equivalent A-weighted sound level L eq , where it is a specified time period, usually 8 or 24 hours.

The equivalent A-weighted sound level is defined as the constant sound level that, in a given situation and time period, conveys the same sound energy as the actual time varying A-weighted sound. The basic unit for these measurements is the decibel. Space station laboratory modules should have A-weighted sound levels not exceeding 55 dB a noise criterion curve of approximately 50 and reverberation times not exceeding 1.

These values should permit 95 percent intelligibility for sentences under conditions of normal vocal effort with the talker and the listener visible to each other. Environments with A-weighted sound levels above 55 dB will require assistance for adequate speech communication.

Designers of audiecommunication systems should recognize that the systems will amplify and distribute noise as well as speech signals to both intended and unintended listeners. Therefore, their use should be carefully controlled.

For sleeping areas, background A-weighted sound levels below 45 dB are preferred, while levels up to 60 dB A are acceptable. Brief noises or transients during continuous noise backgrounds are particularly disturbing to sleep. The probability of full behavioral awakening increases with increasing sound level of the transient.

For transients with an L A of 60 dB, the probability of full behavioral awakening is about 0. The risk for producing significant hearing loss is negligible in noise exposures to an L eq24 of 80 dB. A hearing conservation program similar to that described by the Occupational Safety and Health Administration should be initiated for exposures to an L eq8 of 85 dB or more. If acoustic requirements for acceptable speech communication, sleep, and hearing conservation are met, problems of annoyance and task disruption will be minimal.

Vibration criteria are specified for linear vibration in the Hz frequency range. To reduce the probability of motion sickness, it is recommended that acceleration not exceed 2.

Specific tasks requiring more stringent vibrational criteria should be analyzed on an individual basis. In the absence of appropriate information, these tasks should be simulated on earth to determine vibration sensitivity and required accuracy.

If head or finger control is required to an accuracy of 5mm rms or 2. Hypergolics hiss too, with a harsher metallic note, bangs and pings. Hydroxy rockets , they roar. Solid packs are similar, but rougher, with underlying stutters and clicks. You hear it with your bones. Hard burn, in the jargon, refers to the practice of injecting a limited supply of antiprotons into the exhaust of a fusion torch for short, high-power bursts.

Former astronaut Jay Buckey, now at Dartmouth Medical School in Hanover, New Hampshire, US, says that both temporary and permanent hearing loss were recorded after flights on the Soviet and Russian Salyut and Mir stations, even for stays as short as seven days.

The lost hearing was usually at higher frequencies. The living quarters of the ISS are the Russian Zvezda module, which is the noisiest module on the station. NASA says the goal is for the working area to have noise levels at or below 60 decibels dB and sleep bunks to be 50dB. At their peak several years ago, noise levels reached 72 to 78dB in the working area and 65 dB in the sleep stations.

Decibels are measured on a logarithmic scale, meaning, for example, that 60dB is 10 times louder than 50dB. NASA has worked to reduce the noise and its effect on the crew.

By November , noise levels had been lowered to between 62 to 69dB in the work area and 55 to 60dB in the sleep compartments. Astronauts on the ISS used to have to wear ear plugs all day but are now only wear them for 2 to 3 hours per work day. According to the US National Institutes of Health, however, noise levels below 80dB are unlikely to lead to hearing loss, even with prolonged exposure.

But while the primary cause of hearing loss in general is high noise levels, Buckey suggested in a paper in Aviation Space and Environmental Medicine that several other factors might contribute to the problem in space. Elevated intracranial pressure, higher carbon dioxide levels and atmospheric contaminants may make the inner ear more sensitive to noise, he says.

But there have been no studies yet to test these ideas. Buckey had designed a device to measure hearing loss of astronauts on the ISS, but his project was cancelled around the start of when NASA reduced funding for life sciences.

Crews have installed fan vibration isolators and mufflers on fan outlets, and acoustic padding to wall panels. The current crew, Russian cosmonaut Pavel Vinogradov and US astronaut Jeff Williams, installed a sound-insulating cover on the Russian carbon dioxide removal system. They also started adding acoustic padding near the Russian air conditioner. Future crews will swap out 30 to 40 fans with quieter versions.

Meteors are probably nothing to worry about. On average a spacecraft will have to wait for a couple of million years to be hit by a meteor larger than a grain of sand. But if you insist, there are a couple of precautions one can take. First one can sheath the ship in a thin shell with a few inches of separation from the hull. This "meteor bumper" aka " Whipple shield " will vaporize the smaller guys. For larger ones, use radar. It is surprisingly simple. For complicated reasons that I'm sure you can figure out for yourself, a meteor on a collision course will maintain a constant bearing it's a geometric matter of similar triangles.

So if the radar sees an object whose bearing doesn't change, but whose range is decreasing, it knows that You Have A Problem. This happens on Earth as well. If you are racing a freight train to cross an intersection, and the image of the front of the train stays on one spot on your windshield, you know that you and the engine will reach the intersection simultaneously. One can make an hard-wired link between the radar and the engines, but it might be a good idea to have it sound an alarm first.

This will give the crew a second to grab a hand-hold. You did install hand-holds on all the walls, didn't you? And require the crew to strap themselves into their bunks while sleeping. Having said that, Samuel Birchenough points out that anybody who has played the game Kerbal Space Program know that an object that is not on a fixed bearing can still hit you. If your spacecraft and the other object are in orbit around a planet, the object's bearing will be constantly changing up to the last few kilometers before the collision.

The moon, now visibly larger and almost painfully beautiful, hung in the same position in the sky, such that he had to let his gaze drop as he lay in the chair in order to return its stare.

This bothered him for a moment -- how were they ever to reach the moon if the moon did not draw toward the point where they were aiming? It would not have bothered Morrie, trained as he was in a pilot's knowledge of collision bearings, interception courses, and the like. But, since it appeared to run contrary to common sense, Art worried about it until he managed to visualize the situation somewhat thus: It was a simple matter of similar triangles, easy to see with a diagram but hard to keep straight in the head.

The moon was speeding to their meeting place at about miles an hour, yet she would never change direction; she would simply grow and grow and grow until she filled the whole sky. To guard against larger stuff Captain Yancey set up a meteor-watch much tighter than is usual in most parts of space. The only condition necessary for collision is that the other object hold a steady bearing-no fancy calculation is involved.

The only action necessary then to avoid collision is to change your own speed, any direction, any amount. This is perhaps the only case where theory of piloting is simple. Commander Miller put the cadets and the sublieutenants on a continuous heel-and-toe watch, scanning the meteor-guard 'scopes.

Even if the human being failed to note a steady bearing the radars would "see" it, for they were so rigged that, if a "blip" burned in at one spot on the screen, thereby showing a steady bearing, an alarm would sound- and the watch officer would cut in the jet, fast! A more practical study of any such device shows that any extraneous object that does not change its aspect angle is necessarily on a collision course. Ergo, any target that does not move causes the alarm to ring, and the autopilot to swerve aside.

If the habitat module or space suit is punctured, all the air will start rushing out. Unless you and the other occupants want to experience first-hand all the many horrible ways that space kills you , you'd better patch that hole stat!

An instrument called a Manometer will register a sudden loss of pressure and trigger an alarm. Life support will start high-pressure flood of oxygen, and release some bubbles. The bubbles will rush to the breach, pointing them out to the crew. The crew will grab an emergency hull patch thoughtfully affixed near all external hull walls and seal the breach. The emergency hull patches are metal discs. They look like saucepan covers with a rubber flange around the edge.

They will handle a breach up to fifteen centimeters in diameter. Never slap them over the breach, place it on the hull next to the breach and slide it over. Once over the breach, air pressure will hold it in place until you can make more permanent repairs. A more advanced alternative to bubbles are "plug-ups" or "tag-alongs".

These are plastic bubbles full of helium and liquid sealing plastic. The helium is enough to give them neutral buoyancy, so they have no strong tendency to rise or sink.

They fly to the breach, pop, and plug it with quick setting goo. Much to the relief of the crew caught in the same room with the breach when the automatic bulkheads slammed shut. Holden froze, watching the blood pump from Shed's neck, then whip away like smoke into an exhaust fan.

The sounds of combat began to fade as the air was sucked out of the room. His ears throbbed and then hurt like someone had put ice picks in them. As he fought with his couch restraints, he glanced over at Alex. The pilot was yelling something, but it didn't carry through the thin air. Naomi and Amos had gotten out of their couches already, kicked off, and were flying across the room to the two holes. Amos had a plastic dinner tray in one hand. Naomi, a white three-ring binder.

Holden stared at them for the half second it took to understand what they were doing. The world narrowed, his peripheral vision all stars and darkness. By the time he'd gotten free, Amos and Naomi had already covered the holes with their makeshift patches.

The room was filled with a high-pitched whistle as the air tried to force its way out through the imperfect seals. Holden's sight began to return as the air pressure started to rise. He was panting hard, gasping for breath. Someone slowly turned the room's volume knob back up and Naomi's yells for help became audible. She was pointing at a small red-and-yellow panel on the bulkhead near his crash couch.

Years of shipboard training made a path through the anoxia and depressurization. Inside were a white first aid kit marked with the ancient red-cross symbol, half a dozen oxygen masks, and a sealed bag of hardened plastic disks attached to a glue gun.

He wasn't sure if her voice sounded distant because of the thin air or because the pressure drop had blown his eardrums.

Holden yanked the gun free from the bag of patches and threw it at her. She ran a bead of instant sealing glue around the edge of her three-ring binder.

She tossed the gun to Amos, who caught it with an effortless backhand motion and put a seal around his dinner tray. The whistling stopped, replaced by the hiss of the atmosphere system as it labored to bring the pressure back up to normal. Little gas-filled plastic balls swarm into the compartment. They range from golf-ball to tennis-ball size. A new man, I decide. He's heard about the Commander. He's too anxious to look good.

He's concentrating too much. Doing his job one part at a time, with such thoroughness that he muffs the whole. The plug-ups will drift aimlessly throughout the patrol, and will soon fade into the background environment. No one will think about them unless the hull is breached.

Then our lives could depend on them. They'll rush to the hole, carried by the escaping atmosphere. If the breach is small, they'll break trying to get through. A quick-setting, oxygen-sensitive goo coats their insides.

The cat scrambles after the nearest ball. He bats it around. It survives his attentions. He pretends a towering indifference. He's a master of that talent of the feline breed, of adopting a regal dignity in the face of failure, just in case somebody is watching.

Breaches too big for the plug-ups probably wouldn't matter. We would be dead before we noticed them. Once a pressurized habitat module or space suit springs a leak in the vacuum of space, all the air starts howling out the hole escaping into the void. Since people generally need air to breath or they die, there is an intense interest in how long it will take the air to go bye-bye. Veteran rocketeers, vacationing on Terra, tend to have a momentary panic if they feel the wind.

Their instincts tell them there is a hull breach. You probably won't use this equation, but to calculate an approximate time it will take for all the air to totally escape:.

If you want to get fancy and take the atmospheric temperature into account, use Fliegner's Formula equation from quote below:. However, what we and the hapless people inside the breached compartment are more interested in is how long it takes the pressure to drop to the deadly level of anoxia, i.

Remember if the compartment is using high pressure So if a posh passenger cabin of 15 cubic meters with high pressure has a 3 centimeter one inch diameter hole area 7. So if it punches a perfect hole the same diameter as the bullet the hole will have a radius of 0.

This will bring the 15 m 3 cabin down to anoxia in about seconds or The time will drop if the hole is more ragged or if there are multiple holes. Obviously each additional hole cuts the time in half. Somebody in a space suit doesn't have that kind of time. The space suit uses low pressure. A hole a half-centimeter in diameter has a hole area of 1. As long as the suit's air tanks can keep up the loss the pressure won't drop. But once the tanks are empty, the pressure will drop to anoxia levels in a mere Does this mean that crewpeople in a combat spacecraft will do their fighting in space suits?

Probably not, for the same reason that crewpeople in combat submarines do not do their fighting while wearing scuba gear. The gear is bulky, confining, and tiring to wear. They will not wear it even though in both cases the vessel is surrounded by stuff you cannot breath. They may, however, wear partial-pressure suits or have emergency space suits handy. Those suits will only protect you for ten minutes or so, but in exchange you won't be hampered like you were wearing three sets of snow-suits simultaneously.

Instead, the ship's pressurized inhabitable section will be divided into individual sections by bulkheads, and the connecting airtight hatches will be shut. The air pressure might be lowered a bit. We do not see the room explosively decompress when the railgun projectile shoots through the Donnager's hull and wall. Except for the fact that air is being sucked out into "hard vacuum," everyone manages to stay in their seats.

This happens for a few reasons. The first is the hole, or constriction, is too small for all the air in the room to explosively leave the room. The second deals with the fact that air is made of atoms. Air escaping the hole in the hull to the vacuum of space leaves at approximately the speed of sound. As air molecules exit the hole, the remaining molecules have to "catch up. All cars do not move together. One car slowly inches forward and then everyone follows.

This means there is no explosive decompression unless the entire wall is suddenly removed. While the crew has some time to act, that time is very limited. Scientists and engineers have looked at the physics of constricted airflow for some time with regard to aircraft. It is a very good idea to know what happens to an aircraft if a hole forms while in flight.

Fliegner was one of the first engineers to look at this problem and was able to work out how much air leaves depending on the pressure inside a cabin and the size of a hole. We know this as Fliegner's Formula:. As we expect, the air flow depends on the hole's area, cabin pressure and temperature. Of course, Fliegner's Formula is not that accurate. As the leak progresses, the pressure in the cabin drops and this also affects air flow through the hole.

Have no fear, we can use the equation and a little physics to figure out the time it takes the pressure to drop to a certain level. We have some new variables: Now that we have figured out the equation, we can model what happens inside the cabin and how much time the Canterbury crew have to act.

While you would not necessarily die, you can fall unconscious. We assume that the Canterbury crew can not help themselves and will eventually die as the cabin pressure decreases until all the air is sucked out to the vacuum.

Maybe Shed is the lucky one here. While we do not have the exact dimensions of the room, we can make a few assumptions. Based on the body sizes of the crew, I assume the room is 10 meters by 10 meters by 5 meters or cubic meters in size.

If we plot the graph over time we see that the pressure drops to half its value where everyone has a little over a minute to plug up the holes.

Assuming that everything happens in real-time, from the moment Sed loses his head to the second the holes are sealed, the crew manages to do seal the holes with some seconds to spare. While the estimated size of the room may be larger than it really is, the point is The show definitely gets the science right and the urgency the crew must act to save their lives.

It was just after reveille, "A" deck time, and I was standing by my bunk, making it up. I had my Scout uniform in my hands and was about to fold it up and put it under my pillow. I still didn't wear it. None of the others had uniforms to wear to Scout meetings so I didn't wear mine.

But I still kept it tucked away in my bunk. Suddenly I heard the goldarnest noise I ever heard in my life. It sounded like a rifle going off right by my ear, it sounded like a steel door being slammed, and it sounded like a giant tearing yards and yards of cloth, all at once.

Then I couldn't hear anything but a ringing in my ears and I was dazed. I shook my head and looked down and I was staring at a raw hole in the ship, almost between my feet and nearly as big as my fist.

There was scorched insulation around it and in the middle of the hole I could see blackness—then a star whipped past and I realized that I was staring right out into space. I don't remember thinking at all. I just wadded up my uniform, squatted down, and stuffed it in the hole.

For a moment it seemed as if the suction would pull it on through the hole, then it jammed and stuck and didn't go any further. But we were still losing air. I think that was the point at which I first realized that we were losing air and that we might be suffocated in vacuum. There was somebody yelling and screaming behind me that he was killed and alarm bells were going off all over the place. You couldn't hear yourself think. The air-tight door to our bunk room slid across automatically and settled into its gaskets and we were locked in.

I know it has to be done. I know that it is better to seal off one compartment and kill the people who are in it than to let a whole ship die—but, you see, I was in that compartment, personally. I guess I'm just not the hero type. I could feel the pressure sucking away at the plug my uniform made. With one part of my mind I was recalling that it had been advertised as "tropical weave, self ventilating" and wishing that it had been a solid plastic rain coat instead.

I was afraid to stuff it in any harder, for fear it would go all the way through and leave us sitting there, chewing vacuum. I would have passed up desserts for the next ten years for just one rubber patch, the size of my hand.

It was the ordinary sort of pillow, soft foam rubber. I snatched one hand out and then the other, and then I was kneeling on it and pressing down with the heels of my hands.

It dimpled a little in the middle and I was scared we were going to have a blowout right through the pillow. Noisy was screaming again and Captain Harkness was still asking for somebody, anybody, in compartment H to tell him what was going on. That was a popular idea. About three of them jumped to it. Noisy got clipped in the side of the neck, then somebody poked him in the pit of his stomach and they swarmed over him.

If Noisy lets out a peep, slug him again. I told him and that is about all there was to it. They took a while to get to us because—I found this out afterward—they isolated that stretch of corridor first, with the air-tight doors, and that meant they had to get everybody out of the rooms on each side of us and across the passageway.

But presently two men in space suits opened the door and chased all the kids out, all but me. Then they came back. One of them was Mr. The other man squatted down and took over holding the pillow in place. Ortega had a big metal patch under one arm. It had sticky padding on one side. I wanted to stay and watch him put it on but he chased me out and closed the door. The corridor outside was empty but I banged on the air-tight door and they let me through to where the rest were waiting.

They wanted to know what was happening but I didn't have any news for them because I had been chased out. After a while we started feeling light and Captain Harkness announced that spin would be off the ship for a short time. Ortega and the other man came back and went on up to the control room. Spin was off entirely soon after that and I got very sick.

Basic Home-Built CO2 Laser Information