Wikipedia:Reference desk/Archives/Science/2006 September 3

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September 3

Genetic Engineering's impact on Plant Biodiversity

What are the impacts of Genetic Engineering on Plant Biodiversity? I know a bit and have already looked at http://www.biotech-monitor.nl/2805.htm and a couple of wiki articles.

Cheers, Daniel.thorpe

Basically, as people engineer plants so that they are more profitable/healthy/etc (desirable), the biodiversity goes down because the undesirable plants get unpropagated. When a disease hits that is very detrimental to a certain genome, like the desirable genome, then all those plants die. Without other genomes readily accessible, it is hard to replant. In theory, if we all converted to the most desirable genome, and then it died, well there'd be no more of that type of plant. M.manary 00:12, 3 September 2006 (UTC)

but none of those effects are specific to genetic enginering, if we all switched to one non-gm type of plant we'd go down the same road. Xcomradex 00:19, 3 September 2006 (UTC)

surely introducing wierd and wonderful genes into plants, at least in the short term, increases the biodiversity of plants? You're creating a new species. Whether this species has an effect on others to effect biodiversity, who knows?! Aaadddaaammm 01:13, 3 September 2006 (UTC)

Transgenesis does not, in itself, create a new species. Most genetic engineering of plants for commerical purposes, can be thought of as simply a way of accelerating the same changes that could potentially be brought about by many, many years of selective breeding. The modern farming methods that grow the GM plants may well decrease biodiversity, but the process of genetic engineering - transgenesis - itself is surely increasing biodiversity. Rockpocket 01:56, 3 September 2006 (UTC)

Ahh, yes but wouldn't (due to Darwin's theory) the GM Plants become the "fittest" and eventually become the new dominant species of plant in the area? Especially if they were allowed to breed, wouldn't a disease resistant, or whatever the modification was, plant become a weed-esque organism? There is also the Chance of something like Agrobacterium Tumafaciens (I think thats the spelling) could asexually transmit the changed genomes. Thanks for your help by the way. Daniel.thorpe 10:28, 5 September 2006 (UTC)

Interstellar travel

Let's assume we can aim a spacecraft in the direction of a star (or rather, where the star will be when the spacecraft gets there), fire the thrusters, and have it arrive within 15 AU of the star without any further navigation. Under this unrealistic assumption, and using current technology, is it possible to:

1. Use RTGs to aim the spacecraft at Alpha Centauri and fire the thrusters.
2. Shut the spacecraft down.
3. When the spacecraft is very close to the star, have its solar panels generate enough energy to power a light bulb.

If this is possible, is it possible to send a signal back to Earth to confirm the spacecraft's arrival? If so, how about sending a picture and some measurements back to Earth? --Bowlhover 06:15, 3 September 2006 (UTC)

If thousands of years have passed, the nuclear fuel may have lost much of it's radioactivity by then, unless you choose a fuel with a very long half life, in which case only a very low power output would be produced. StuRat 07:13, 3 September 2006 (UTC)

Was it really necessary to shove this in here? Couldn't it just have gone after mine? Seriously, what the hell? Black Carrot 20:24, 3 September 2006 (UTC)

Mine was a response to Bowlhover, not to you, so I placed it after his. I was even careful to double indent my comment so it was also clear that yours is not a response to my comment. Also, mine was only one sentence, so didn't push yours away from the original question by much, whereas yours was 4 sentences long. So what's the problem ? StuRat 02:48, 4 September 2006 (UTC)

We have to wait ten years to get news back from Pluto. Does it really seem plausible that we could set up communication with another star on a reasonable timespan? The Alpha Centauri article says it'd take 4.39 years just for the return message to flash back to us, at the speed of light. Black Carrot 06:23, 3 September 2006 (UTC)

Other than that, though, and the near insurmountable difficulty of calculating and following the right trajectory, and the additional difficulty of sending a tight enough signal in just the right direction to hit the Earth half a decade later, I don't see why not. Black Carrot 06:29, 3 September 2006 (UTC)

It doesn't take ten years to get a signal from Pluto - it isn't ten light years away. Stop picking on that poor former-planet! I'm more concerned about the amount of energy it would take to send a detectable signal from the other star. I don't think that solar panels would cut it. Clarityfiend 20:31, 3 September 2006 (UTC)

I know that sending a probe to Alpha Centauri will take a very long time, but even if it takes 18000 years, that's OK. The reason I asked the question was because I'm curious about whether any electronic equipment can survive in empty space for tens of thousands of years, and still be operational.

As a separate question, what's currently the most realistic way to travel to Alpha Centauri? Again I don't care about the time it takes, just that it's realistic. --Bowlhover 06:49, 3 September 2006 (UTC)

My plan:

1) Build a huge linear accelerator, powered by an onboard full scale nuclear reactor, in the asteroid belt.

2) It will then clamp onto a metallic asteroid which will be at the front end of the accelerator, and be approximately 90% of the total mass, with the ship being the remaining 10%.

3) Move the accelerator out of the plane containing the planets, and into a position on a line between the Sun and Alpha Centauri. This movement can be done with conventional booster rockets which are then discarded.

4) Aim the accelerator toward AC, then fire up the linear accelerator. A continuous mining operation will remove metal from the asteroid, which is then accelerated to the speed of light and ejected toward the Sun (so the stream doesn't pose a hazard to anyone). This propels the ship at approximately 1 g.

5) After about a year, the ship will be at near light speed and half of the mass will have been used up. Turn the engine off.

6) Cruise for about 4 years at near light speed, then rotate the ship the other way around (rockets can do this).

7) Repeat the process to decelerate at 1 g for about a year, with the matter stream directed into AC. This will use up about 50% of the remaining mass, which is 25% of the original mass.

8) Turn the ship slightly, near the end of the burn, to achieve a stable orbit about AC.

9) You've reached AC in about 6 years. Have fun exploring ! StuRat 11:00, 3 September 2006 (UTC)

After edit coflict:

Possible? Maybe. Pointless? Certainly. A few decades from now we will be able to build a spaceship that will overtake the one we send now before it reaches the star. This will remain true until the time it takes a spacecraft to get to a given star will approach the time it takes to develop a considerably faster spacecraft. By that time we might also live longer than that time, so people then might be interrested in doing this. But by that time we may also have other means to get that info without travelling there, so we may never travel to the stars. DirkvdM 06:59, 3 September 2006 (UTC)

Any traditionally rocket propelled ship would surely be picked up a century later by our then much faster ships, and put into a museum. This takes all the fun out of spending billions of dollars to send the first ship, doesn't it ? StuRat 07:05, 3 September 2006 (UTC)

Unless Klingons see it first and use it as a target for shooting practice. DirkvdM 07:28, 3 September 2006 (UTC)

Don't be silly. It would be the Kzinti. Clarityfiend 20:33, 3 September 2006 (UTC)

The only plausible type of interstellar travel I can think of, is outlined here, all the way at the bottom of the section. Catastrophe Surfing, kind of long winded--VectorPotential^{71.247.243.173} 11:47, 3 September 2006 (UTC)

Product Success

If I wanted to find out how successful something's been (how many copies a book's sold, say) how could I get that information reliably? Black Carrot 06:33, 3 September 2006 (UTC)

• With books it's particularly hard because in a lot of cases the numbers collected are actually the books sold to the stores. Book stores usually overorder and send the stuff they don't sell back, resulting in either books being warehoused or destroyed. That's why I personally prefer the Print on Demand model as it wastes a lot less paper. - Mgm|^(talk) 08:54, 3 September 2006 (UTC)

rubella virus

what system in the body does the rubella virus (aka German measels) occur in?

any help would be greatly appreciated!! Sammie hero 07:14, 3 September 2006 (UTC)

The Rubella article will tell all... "The virus usually enters the body through the nose or throat. Like most viruses living along the respiratory tract, it is passed from person to person by tiny droplets in the air that are breathed out. Rubella can also be transmitted from a mother to her developing baby through the bloodstream via the placenta." Rockpocket 08:20, 3 September 2006 (UTC)

Time dimensions

There are (at least) three spatial dimensions. These are expressed as exponents of length. I can visualise m, m² and m³. But in, say, acceleration, there is an exponent of time: m/s². Does this indicate a second time dimension? And can I use thinking about acceleration to get an idea of what that Second Temporal Dimension is like? The link touches on the subject, but doesn't quite help me. Also, power is kg.m²/s³. Does this mean there is a Third Temporal Dimension? And more? Also, I dn't know of any derived units that use a higher spatial dimension than three. Are there? DirkvdM 07:54, 3 September 2006 (UTC)

I always thought of acceleration as (meter per second) per second. That way I never had to imagine time squared. Now you have me confused! The SI unit for polar moment of inertia is meter to the fourth power (m^4). ---Sluzzelin 08:33, 3 September 2006 (UTC)

No, units have nothing to do with dimensions. StuRat 10:41, 3 September 2006 (UTC)

Could you emphazi that a little more suitly? Surely, m² and m³ have something to do with the second and third spatial dimension. And it takes just a small mental step to think that the use of s² indicates a second temporal dimension. DirkvdM 12:17, 3 September 2006 (UTC)

Units are generally a summary of the calculation, in this case accelaration is expressed as a vector quantity with dimension length/time², which means you square time, not you multiply two seperate time dimensions together. If there was more than one time dimension you would know about it. For a start you'd be a Tachyon. Philc _T^E_C^I 12:37, 3 September 2006 (UTC)

Well let me reverse it then. If s² is not about a second temporal dimension, then is m² also not about a second spatial dimension? Surely it is. Or let me ask this in more general terms. What does it mean to square a unit?

But let me follow your lead. Suppose I'm a tachyon. :) The article says a tachyon "can never slow to light speed or below". In other words, it exists beyond the speed limit, so not in our reality. So in another dimension? I must admit that I'm totally out of my league here, but you brought up the tachyon, so don't blame me. :) DirkvdM 13:36, 3 September 2006 (UTC)

Hehe, fiar enough, m² doesnt necesarily mean two dimentional space, though it can be used to mean this. I can also just implying a square relationship between this variable and another, ke=½mv², here we have a v², but all it is saying is that it is a square relationship between ke/½m and v, v is still a single value, and the ² does not imply that it is a 2-dimensional value.

Tachyons I brought up because above the speed of light things get complicated, for example, above the speed of light spacial and time dimensions swap round, so there are 3 time dimensions and 1 spacial dimension. Where as we recquire an infinite amount of energy to reach the speed of light, tachyons recquire an infinite amount ot decalerate to the speed of light. Now I dont quite understand the physics of navigating multiple time dimensions or anything, but tachyons exist in them, and mutliple time dimensions are possible, and exist in our univers, but we can only interact with one. Which is probably for the better, but there existence isnt anything to do with units involving time² variables. Philc _T^E_C^I 13:48, 3 September 2006 (UTC)

metres per second squared is just a shorthand for metres per second per second. It doesn't really mean metres per squared second. Skittle 14:21, 3 September 2006 (UTC)

Yeah. a m/s²=(dm/ts)/ts=(distance/time)/time. It's not that there are two separate dimensions of time, it's that you're working out an intricate relationship between a dimension of distance and the one dimension of time. You would use essentially the same math, though, if there were two time dimensions to consider. You could also have some fun linking it to spatial concepts by adding in calculus. The integral of acceleration (distance over time squared) d-time, is velocity (distance over time), the integral of which, d-time, is just distance. So, given a graph of acceleration from a starting time to an ending time, velocity is the area under the graph, and distance is the area under that graph. Both computations use the same unique time dimension, though. Black Carrot 20:19, 3 September 2006 (UTC)

There's a difference between meters squared and square meters. The former you can get when you multiply two quantities together, such as velocity; the latter involves the second spatial dimension. The confusion arises because the same notation is used for both.

That being said, there's no reason I can think of why multiple time dimensions can't exist. We just aren't equipped to detect them. Maybe you should talk to the Wormhole Aliens of Star Trek: Deep Space Nine. (Cue the Twilight Zone theme)...for your perusal. Clarityfiend 20:41, 3 September 2006 (UTC)

Not that I expect an answer to this late reply, but isn't the same notation used for a reason? Or reasoning the other way around, if these are two different things, then shouldn't there be different notations? DirkvdM 20:46, 12 December 2006 (UTC)

The fact that you can multiply 1 second by 1 second and get 1 second squared doen't imply anything about reality. I could imagine a quantity with units of seconds^100, but that doesn't mean I have created 100 time dimensions. --bmk

If two things have the same properties they are the same. Or at least that's how it should be in physics. It's not like the first time in (m/s)/s is any different from the second one (no pun). At least in the sense that length is no different whether it's width or height. But together they form an extra dimension. So if that goes for length, shouldn't it also go for time? As a variation of my first statement, the same mathematical operation must have the same meaning wherever it's applied. If you apply adding a power to length once (m² in stead of m¹) you express an extra dimension. If you do that again (m³ in stead of m²), you get an extra dimension again. How would one describe things in the fourth spatial dimension? with m⁴, right? So here, raising to a different power seems to express a different dimension. And why would the same mathematical operation have a different meaning when applied to a different unit? DirkvdM 08:45, 4 September 2006 (UTC)

If time had 2 dimensions your life could be an infinitely long spiral in some fixed area. Bounded yet eternal. Three square yards and...no, dammit, I can't think of a decent pun!! Rentwa 20:03, 4 September 2006 (UTC)

No, I'm pretty sure thats not right,time still has rules even if there are multiple dimensions, there are still issues with going backwards in it (i.e. its not possible). Philc _T^E_C^I 20:15, 4 September 2006 (UTC)

If time had two dimensions, the Universe would be unstable. Q.v. Spacetime#Privileged character of 3+1 spacetime. -- Fuzzyeric 00:31, 6 September 2006 (UTC)

No, the s² does not imply an extra time dimension. As someone said above, it's just a shorthand. The formal expression for acceleration is d²x/dt², i.e. the second time derivative of position; which does equal m/s² (for meters and seconds) which is the form people who haven't leanred calculus know. Would people still ask if there was an extra time dimension if it was expressed as v/t?

Weird sky

While I was coming home today, I noticed something weird about the clouds. They had these thick, dark bands, which were perfectly straight-edged and converged into a similar area out at sea. It kind of looks like that effect when the sun is setting, and some bands of light come through the clouds. The bands, however, were in the east, and the sun was in the west. I took photos when I walked to the beach later, but they didn't come out great, and the bands had faded lots. Thanks. --liquidGhoul 09:40, 3 September 2006 (UTC)

• If you live in the North Eastern United States, you might have been looking at what was left of a tropical storm, but I suppose you'd probably notice that. Ok, scratch that, your user page says you're Australian (:VectorPotential^{71.247.243.173} 12:02, 3 September 2006 (UTC)

Here is a pic. The photos were worse than I thought, as you can only see one of the bands (most had faded by now), and it seems they were light bands. It was just there were so many bands previously that the dark looked the minority, hence they were dark bands. It is kind of hard to see, but is still visible. --liquidGhoul 12:39, 3 September 2006 (UTC)

I assume it's the sun. When it shines through the holes in the clouds, and there is sufficient mist in the air, you'll see the rays, like you'll see a laser beam when it passes through smoke). I see that effect quite often here in Germany. —da Pete (ばか) 14:13, 3 September 2006 (UTC)

He said it wasn't the "sun filtering through the clouds effect". Could it be that they were just indications of rain far off? No, after taking a second look that doesn't look too likely either. Strange.  freshofftheufoΓΛĿЌ  14:35, 3 September 2006 (UTC)

(edit conflict)Yeah, it wasn't shining through, you can see from my shadow in the photo that the sun was behind me, not the cloud. I have seen rain out at sea, and that usually starts much lower, and is parallel. When this was obvious, there were some bands that were vertical, but most were at different angles, and converging to the same general area. The best explanation I could think of was reflections of the sun off the cloud, but there is no way in hell that it could be that perfect looking. The clouds should reflect it in all different directions. Thanks --liquidGhoul 14:42, 3 September 2006 (UTC)

Take a looksee at anticrepuscular rays. Weregerbil 15:00, 3 September 2006 (UTC)

Wow, that is awesome. I will have to keep an eye out for it more often. Thanks. --liquidGhoul 15:14, 3 September 2006 (UTC)

Yes, I would say those are anticepuscular rays. Nice photo, if you see it again and can get a good picture, stick it on the article! — [Mac Davis] (talk) (Desk|Help me improve)

Fat or Muscle?

Hello guys....I weigh too much(about 195 pounds,173 Cm height) and hence I have decided to fast one square meal.I have a hanging belly...Now if I just fast and don't do excersize,will my belly get reduced?...or just my muscle get reduced?..I checked my weight and I can read it's dropping pretty well every week.If my weight is dropping but I can't see pretty changes in my belly shape..Is it good to fast? and continue this way? or must I do excersize?...I'm trying to reduce my calorie intake to 1000kcal per day.Now I have reduced my wieght to about 155 pounds and I'm looking not that obese but my belly is still hanging...Can anyone help me in this please?...Thanks in advance..

What's your age ? You are more likely to sag after losing weight if you're older. In any event, the cure is to exercise. I suggest sit-ups for the belly. If you have lots of loose skin, though, then surgery would be required to remove it. StuRat 10:36, 3 September 2006 (UTC)

Doing sit-ups does not reduce the amount of fat on the stomach, it only increases the muscle underneath. You won't see any results from sit-ups until the fat above it is removed. You should be doing aerobic exercise, as that will increase the health of your heart (then other organs) as it has probably been damaged from being overweight, depending on how long you were overweight. This should also result in it being easier to lose weight. Go running or swimming to achieve this. Also, make sure you are getting all neccesary nutrients, a malnourished body will hold on to as much fat as possible. This is achieved through eating healthily (vegies, nuts, meat). Everybody is different as to where they will lose weight last, for you it is probably the stomach. --liquidGhoul 11:10, 3 September 2006 (UTC)

At 155 pounds, I would say the excess fat is already gone, all that is left now is to tone the muscles. StuRat 11:25, 3 September 2006 (UTC)

I agree with the advice about exercise. And as for your gut, burned fat tends to be harvested first from around the organs, and later redistributed. You may not see the final results of your weight loss for two or three months, at which time your body has finished re-balancing the fat content of your body. Anchoress 11:17, 3 September 2006 (UTC)

To add to the above: Do an activity that you enjoy which forces you to exercise. It's a lot easier to aim for a more active lifestyle than it is to start exercising all of a sudden, though the difference is really only in the perception. A sagging belly is a sign that your body isn't holding itself together, and something as seemingly unrelated as back exercise can have noticeable results. One of the most important things is keeping a routine, and you have to be comfortable doing it. Reducing your calorie intake may help, but that should never be the focus of your "diet lifestyle". I mean, think about it this way: Exercise requires concious physical action, fasting requires no extranuous act other than resisting the urge to eat. Do you really think that fasting could logically have more benefit than exercise? There are lots of studies that suggest fasting has the opposite effect on dieting, as the body goes into a calorie conservation mode and thus you gain wait easier from smaller amounts of food.  freshofftheufoΓΛĿЌ  11:29, 3 September 2006 (UTC)

When I used to go cycling a lot, it kept my tummy really trim. 62.253.52.65 13:55, 3 September 2006 (UTC)

Hearty Thanks for yout tips all friends.I'll keep all these in my mind...I have one more to ask...I'm now 24yrs old.I now look perfect and fit,say all my girl friends...But when I remove my shirt I still get embarrassed since I have loose muscles\fat whatever hanging esp the belly..But my shoulder and hip bones are almost visible and I look skinny except for my belly which is very loose...Is it just the fat or loosly packed muscles?...Now to reduce this what kind of steps should I have to follow?..Can dieting reduce this or should I have to follow the exercise as described earlier?....

Is exercise really "the cure?" Prof. Richard A. Muller disputes [1], and says the best way is just to eat less. Muscles don't "hang" it is either skin or fat that does. — [Mac Davis] (talk) (Desk|Help me improve)

Muscles may not hang, but the ligatures and bones that are supported by them do, particularly the hip and shoulders. A good posture can go a long way towards making you look healthy. I haven't seen Muller's stuff before, but I'll take a look at it now.  freshofftheufoΓΛĿЌ  05:55, 4 September 2006 (UTC)

I've read it, but I don't see what that proves. It's a non-conclusive report (more like a diary) by a high-profile physicist. Good for him that he lost 30 pounds, but it's not exactly a paper that I'd quote.  freshofftheufoΓΛĿЌ  06:01, 4 September 2006 (UTC)

That's a good article. I like the guy who wrote it. It's worth keeping in mind, though, that it did take him seven months to lose all 30 pounds. How long would it have taken if he'd excersized as well? Black Carrot 19:54, 3 September 2006 (UTC)

Something else to keep in mind is that you can still reduce your caloric intake by eating smaller meals rather than starving yourself for half the day. That helps keep your basal metabolism up. I think that's what bodybuilders do. AEuSoes1 21:03, 3 September 2006 (UTC)

Hey thanks about that...That's what I've been thinking about so far...I better take small amount of intake regularly instead of starving and sure it all goes toward a positive way...Thanks again friends...

It's best to have a healthy diet AND exercise. --Proficient 17:45, 4 September 2006 (UTC)

Insect

I believe that this is a insect belonging to the Dermaptera order, but perhaps someone can tell what family or species is it? --Andreas Rejbrand 10:15, 3 September 2006 (UTC)

Could it be an earwig ? StuRat 10:27, 3 September 2006 (UTC)

I thought I said that :) Earwig = the Dermaptera order --Andreas Rejbrand 10:41, 3 September 2006 (UTC)

Having found the insect in Sweden, perhaps it is a Forficula auricularia? --Andreas Rejbrand 19:22, 3 September 2006 (UTC)

Circumstances for watching polarized light

Hi, I live around 65 North, are my chances for getting a view of Haidinger's brush better or worse than someone living further south? I also understand from the article that there are TWO brushes, each 90 degrees away from the sun. There isn't any at 180, then? The brush sounds really awesome, I can't wait to gaze into the sky for minutes and minutes, like a moron, with all my friends wondering what I'm doing. :) 81.93.102.35 10:53, 3 September 2006 (UTC)

If your aim is to just see a Haidinger's bush, it's much easier to see on a TFT screen then in the sky. I've seen a very good webpage on it, I'll try to dig up its address. – b_jonas 17:17, 3 September 2006 (UTC)

Anyway, I doubt that there are two brushes each 90 degrees away from the sun because the position of the bush depends on where you're looking at. – b_jonas 17:19, 3 September 2006 (UTC)

I don't think Latitude makes much difference. In Seattle I see Haidigener's Brushes all the time. It's best towards evening when the band of sky-polarization occupies the zenith. If not at sundown, you'll have to stare at the dark band of sky which is 90deg away from the sun. The brushes look like a wide bow-tie shape, with two yellowish quadrants and two bluish quadrants. Also, it's much easier to see the brushes if one stares straight up and then spins around. That way the brushes appear to be rotating, and you won't just seem questionable for staring upwards, you'll instead look like a complete fool.  :) --Wjbeaty 00:49, 9 September 2006 (UTC)

STI's

If you either of your parents has an STI before you're born, excluding HIV, could you get it after your born? Please respond on my talkpage: user:100110100. Thanks!68.148.165.213 12:45, 3 September 2006 (UTC)

Sure, see congenital syphilis, and why do you think silver drops were routinely put in the eyes of newborns for most of the last century? To prevent gonococcal opthalmia neonatorum. Chlamydia trachomatis as well can be transmitted during delivery and cause infant conjunctivitis and bronchiolitis. Oh, and don't forget congenital herpes. And sorry we do not email private answers. alteripse 13:02, 3 September 2006 (UTC)

Thank you for your response. No, I have an account on Wikipedia. That's what you type in the search box to get to my talk page, but thanks for your response. How do you know of you have a STI from your parent (within the context of the above)?68.148.165.213 13:47, 3 September 2006 (UTC)

You get tested for whatever the mother has. --liquidGhoul 13:55, 3 September 2006 (UTC)

An infant with a congenital STI has a variety of problems apparent in infancy. If you are an adult wondering if you "inherited" something like that from your mother decades ago, you have bigger problems than an infection. alteripse 16:38, 3 September 2006 (UTC)

But STI's do not necessarily change genes, nor does it affect the baby prenatally. Can't STI's show up after the baby is born? I.e., affecting a person after the person is out of the womb? Or tube, in the case of invitro babies?24.70.95.203 16:58, 3 September 2006 (UTC)

STIs can indeed affect the baby prenatally. Congenital syphilis is a prime example of this. The symptoms of prenatally/perinatally acquired STDs are not typically the same as the symptoms of primary infection. For example, if you were exposed to chlamydia during birth, you are more likely to get conjunctivitis or pneumonia than urethritis. And "test-tube babies" still go through pregnancy in the womb! InvictaHOG 18:23, 3 September 2006 (UTC)

Pardon my response, I didn't make it clear. What I meant is that some STI's do not affect the baby prenatally, SOME, not all.100110100 00:04, 4 September 2006 (UTC)

You are right, a baby can get exposure to HSV2 during delivery and not develop disease. It is perhaps a matter of semantics whether you call that "getting it". Certainly it may take days or weeks for real trouble to develop (like herpes encephalitis. If you are asking if it seem healthy and can incubate for years and decades before the infection causes problems, we don't think so, or at least it is very rare or cannot be recognized as a congenitally acquired STD. HIV is about the only exception I can think of to the general rule that congenitally acquired STDs either cause trouble in early infancy or not at all. alteripse 00:25, 4 September 2006 (UTC)

Thanks for the response. Ok, can you get a get HSV2 during delievery\prenatally but be a carrier, or for a lack of better words, be able to infect other people, without showing any symptoms, even 'till the day you die'? I know that HSV2, you get get anywhere. Ok, I'll explain my situation. My parents never tested themselves for STI's and they still haven't. I am a virgin. But from the wikipedia article Herpes simplex virus, it says you can can it anywhere, & from what I garner from my talk page, InvictaHOG says that you can get HSV2 and NEVER display symptoms even by the time your dead [And come to think of it maybe even after your dead. Am I right?]. From this information, I just want to stay away from people. But that's so inconsiderate. So maybe as much information you guys could provide would be greatly appreciated. Thank you.100110100 07:13, 5 September 2006 (UTC)

I do not understand your concern. The world is full of viruses and we have all been exposed to a variety of them and carry some of them within us. I think the last sentences of my second and third answers apply here and are the limits of my expertise on this topic in this forum. You have given no reason for your fear that you are infected, and if so, that it came from your conception, gestation, or parturition. Before you make renunciations of close physical relationships for the rest of your life, pay a visit to an infectious disease consultant with expertise in virology to explain your fears and get reassurance. It might cost you a trip to a big city and $300 but if it settles this fear for you it is cheap at the price. If the infectious disease consultant assures you your fears are groundless, but you still can't shed them, a therapist will be a bigger expense and effort but might still be worth it. Don't make important decisions based on what a bunch of random guys here know ex vertice. Good luck. alteripse 10:42, 5 September 2006 (UTC) PS Either of these might be places to start based on your IP location: [2]. I think your best choice would be the pediatric inf dis dept at your local medical schood/children's hospital because those are the doctors with the most expertise in perinatal transmission; the UAlberta fellowship info says one of the 4 attendings specializes in virology. Alternatively: [3] but I would confirm ID board certification and virology interest before making appt. And it will be a lot cheaper in canada.

HSV 2\HSV-2

Can you have HSV 2\HSV-2 and never display symptoms? Please respond on my talkpage: user:100110100. Thanks!68.148.165.213 13:44, 3 September 2006 (UTC)

HSV 2\HSV-2 = herpes simplex virus 2\herpes simplex virus-224.70.95.203 17:10, 3 September 2006 (UTC)

Yes InvictaHOG 18:20, 3 September 2006 (UTC)

Ever in you life? Thanks.100110100 23:29, 3 September 2006 (UTC)

Ok, sorry let me rephrase my question: Must you display at least A symptom of HSV 2 [or otherwise called herpes simplex virus 2, herpes simplex virus-2, or HSV-2] in your lifetime, [i.e.: before you die] if you have HSV 2 [or otherwise called herpes simplex virus 2, herpes simplex virus-2, or HSV-2]?100110100 00:09, 4 September 2006 (UTC)

Why does this edible oil mixture taste bitter?

Recently I bought a mixture of flax seed oil, sunflower oil, olive oil, evening primrose oil, soya lecithin, and rice bran oil. It is supposed to give a balanced amount of Omega 3, 6 and 9, but I just bought it as it was a cheap way of buying non-fish omega 3.

I know that Flaxseed oil tastes or smells like putty, because that's what putty is made of, but it also had an unpleasant bitter taste.

Interesting. --Proficient 17:46, 4 September 2006 (UTC)

I have previously eaten all the ingrediants separately except Evening Primrose Oil and Rice Bran Oil, and none of them tasted bitter, nor are they mentioned as being bitter in Wikipaedia.

Thanks

Some of these oils (e.g. olive oil and flax seed oil) contain polyphenols such as tannin, which taste bitter to the human tongue. Maybe some of them were masked in their original states and activated through the mixing process. (Or maybe the mix uses unbalanced bitter-tasting products to begin with).---Sluzzelin 14:11, 3 September 2006 (UTC)

Bicycle seatpost has rusted into frame

Can anyone suggest the best way to remove the seatpost please? I do not mind destroying the seatpost, but not the frame. Thanks.

Is the post or the frame rusted? The best method I can think of (not as any sort of expert is to remove the seat and drop down something that will catch at the end, then pull and rotate. Good luck. --\/\/slack (talk) 15:02, 3 September 2006 (UTC)

Try a pipe wrench and twist the post, might work if it isn't totally rusted and the worst thing that can happen is you'll mangle the top of the post, which you don't want anyway. If that dosen't work you could try getting a machinest to drill it out, but I'm not sure how well that would work and there is a good chance you would wreck the frame. The only other option I can think of would be to get a bicycle shop to heat up the frame so that it expands and the post can be removed. My father had this done when his crank rusted into the frame and it didn't seem to affect the steel frame's strenth, though it did a job on the paint. Still there is risk there as well. It's also probably wise to think about the rest of the bike before you do something pricey too, is the rest of the bike worth keeping or not? That probably isn't the only thing that has rusted on it. I had this problem on an ancient racing bike that I got for free. The post is still in there, the rest of the bike wasn't worth the repair. 24.137.78.34 15:10, 3 September 2006 (UTC)

From WD-40: "Two rules get you through life: If it's stuck and it's not supposed to be, WD-40 it. If it's not stuck and it's supposed to be, duct tape it." :-) Maybe a combination of WD-40 and vise grips? Weregerbil 15:13, 3 September 2006 (UTC)

Some bicycle mechanics will remove the cranks and bottom bracket, turn the frame upside down, pour motor oil into the seat tube through the bottom bracket shell, and let it sit for a day or two, then apply some torsion to the seat post. Sometimes, the seat post lug can be slightly spread to facilitate dislodgement. At all times, one must use a combination of force and restraint so that the frame is not damaged. Because this often takes experience, you might consider having a bicycle mechanic do this task if your initial attempts are not successful.--Mark Bornfeld DDS 16:24, 3 September 2006 (UTC)

I would either take Mark's suggestion (you might improve on it with rust eater (dunno the english term)) or if that does not work, you should be able to either drill the seatpost out completely (you will need to fixate both the bike and the drill) or to drill a small hole down along the seatpost so you can 'fold' it into the bike frame. Another way would be to get a winding drill and create a screw thread into which you screw (and perhaps even glue it in with strong loktite (the kind for large ships) or some such) a bar with a handle. This should give you _lots_ leverage. RichiH 17:22, 3 September 2006 (UTC)

My solution would be: spray some WD40 into the crack. Leave for 24 hrs. THen, get a pair of Mole grips, tighten hard and give stem a twist. If no movement, gently tap the end of the grips with hammer. I still noemovement, spray more WD 40 and leave for another 24 hrs. Repeat process until stem is loose. 8-)--Light current 18:12, 3 September 2006 (UTC)

Although I'm in complete agreement with the utility of WD-40, in this case, a specific penetrating oil (American trademark: "Liquid Wrench") may work better for this than WD-40. Give it lots of time to work its way along the seat post, though. (And I mean lots, I'm talking several days or more.) And yes, let gravity work it down and then flip the bike and let it flow up, err, down from the bottom bracket. I also agree with whoever suggested lots and lots of torque/a pipe wrench.

Atlant 22:48, 7 September 2006 (UTC)

complex carbohydrates

finally, after clicking all over the place I get here. Question: May I please have a list of complex carbohydrates? I am diabetic, and controlling it with diet and exercise. I want a simple list of foods that are considered complex carbohydrates. Thank you Linda Johnson

The American Diabetes Association and Diabetes UK give you a summary. Though the lists posted here aren't all too comprehensive, the websites might point you to further information. ---Sluzzelin 14:51, 3 September 2006 (UTC)

Complex carbohydrates is in cookery another name for starches. For example, rice, pasta, bread, potatoes, beans. See Starch#Starches_as_food. The wholemeal kinds are to be preferred. I would not eat bananas even though listed as a starch - I expect they have a lot of sugar in them also.

You may also be interested in the articles Diabetic diet, Diabetes management, Diabetes, and low Glycemic index foods, including List of foods with a low glycemic index.

This site http://www.netdoctor.co.uk/focus/nutrition/facts/lifestylemanagement/carbohydrates.htm has a list of complex carbohydrates:

bananas

barley

beans

brown rice

chickpeas

lentils

nuts

oats

parsnips

potatoes

root vegetables

sweet corn

wholegrain cereals

wholemeal breads

wholemeal cereals

wholemeal flour

wholemeal pasta

yams

There seems to be a lot of medical quackery on the internet, so don't believe everything you read.

I do hope you are doing this under regular medical supervision - your sight is at risk if you are not. Take care. 81.104.12.75 15:14, 3 September 2006 (UTC)

Slow decrease in weight at sub orbital velocities

Hi, I know that the Concorde airliners flew fast enough to decrease the weight of the passengers from your article, and that at 7800 m/s one's weight is zero since it is orbital speed. I am wondering how fast the weight decreases in relation to speed. I realize that height also has something to do with it, but unless I am really off, this is not generally significant? Thank you for your patience. 24.137.78.34 15:01, 3 September 2006 (UTC)

It is not the speed at which it reaches altitude, it is the falling that get's you weightless I believe. — [Mac Davis] (talk) (Desk|Help me improve)

Let's see if I make a mess of the math...

The centrifugal force can be calculated with F=v²/r.

Concorde's cruising speed is(was) 2170 km/h = 603 m/s. Earth radius r=6372000 m (could add the plane's altitude but the effect is small). Flying east at the equator the Earth's rotation (465 m/s) adds to the speed: F = (603 m/s + 465 m/s)² / 6372000 m = 0.179 m/s². This is about 1.8% of Earth normal gravity (9.78 m/s²) so a 100 kg person would weigh 1.8 kg extra. Flying west you need to subtract the velocities, giving 0.00299 m/s², i.e. a very tiny difference (Earth rotation and plane speed almost cancel each other out).

Hmm, the Concorde article quotes 1% and 0.3% weight differences. I'm guessing the article assumes Europe to US flight rather than equatorial flight which I used. Earth rotational speed of 200 m/s gives 1% and 0.3%; I'll bet the article assumes a London/New York flight.

At the speeds of an X-15 you'd be 10% lighter.

See also: [4]. Weregerbil 19:12, 3 September 2006 (UTC)

Thank you very much, that was exactly what I wanted to know. I did not know that the centrifugal force equation could be used to calculate it, though it makes a lot of sense now. 24.137.78.34 20:19, 3 September 2006 (UTC)

Nikon D70 question

Hi Wickies

A quick one for ya

I have a Nikon D70 camara and did some long exposures the other night which resulted in a purple "fog" in the top right of the picture on any exposure over about 3 mins. I thought it might be some sort of light pollution so I put the camara in a dark bag with the lense cap on and tried several exposures of differing lengths from 3 to 10 mins. The purple fog persisted in the top right of each exposure. The longer the exposure the further the purple fog drifted across the picture. Any ideas what it might be? Me being a bit of a thick'o when it comes to electronics means I ain't got a clue other than thinking that something must be energising the top right (or bottom left?) corner of the photo sensor. Anyone had this problem with a digital camara before?--Eye 16:33, 3 September 2006 (UTC)

This explains the noise fog. [5] You can apparently map this into the camera for noise reduction. --Zeizmic 22:21, 3 September 2006 (UTC)

And if the camera can't do that, use one of those bagged shots in Photoshop and substract it (can't think from the top of my head how to do that, but it's possible and in other applications too probably). Ideally, you should have one for each exposure duration, but using a long one and varying the amount of substraction should also work. DirkvdM 07:42, 5 September 2006 (UTC)

Spiral path of a Hawk

What advantage does a hawk/an eagle get, when it follows a logarithmic spiral instead of an Archimedean spiral-while diving on it's prey ? Thanking you,--Pupunwiki 16:39, 3 September 2006 (UTC)

I read something about this in Mario Livio's book "The Golden Ratio." He seems to suggest that it has to do with optimizing energy. The bird, while following a particular spiral path, is able to keep its eye on the prey, while at the same time maximizing its own velocity. - R_Lee_E (talk, contribs) 16:52, 3 September 2006 (UTC)

Sidenote - From what I've gathered, Livio's thesis is to show that the reason we find the logarithmic spiral (or golden spiral) present so frequently in nature (i.e. galaxies, sunflowers, the flight path of birds of prey, etc.) can be explained in terms of energy conservation, or energy optimization. For instance, Livio shows that the reason why the golden mean makes an appearance in the sunflower ([6]) is because it allows for the maximum amount of sunflower seeds to be packed into the smallest area - thus making the most efficient maneuver possible with the energy at its expenditure. A similar phenomenon is seen in the stemgrowth of most plants, wherein each ascending leaf grows according to the golden mean. This is to help prevent the lower leafs from being shaded by the leafs directly above them. The 'golden mean' itself seems to be a kind of sweetspot in nature. Various processes within nature, whether living or non-living, seem to 'settle into' the golden ratio 'groove.' - R_Lee_E (talk, contribs) 21:06, 3 September 2006 (UTC)

(sigh) The obvious spirals in a sunflower are not logarithmic: the angle between the spiral and the radius approaches a right angle, until at some point that series of spirals fades out and is replaced by the next. [7] [8] Nor is there any necessary connexion between logarithmic spirals and the golden ratio. —Tamfang 22:44, 3 September 2006 (UTC)

No connection between the logarithmic spiral and the golden ratio? Golden spiral "In geometry, a golden spiral is a logarithmic spiral whose growth factor b is related to φ, the golden ratio." - R_Lee_E (talk, contribs) 22:55, 3 September 2006 (UTC)

No necessary connexion, I said. Yes, you can find a special logarithmic spiral whose constant is the golden ratio (or any other real number ≥1), but I'm forever seeing all log.spirals sloppily called "golden" or "Fibonacci" and it's best to avoid encouraging that. —Tamfang 06:24, 4 September 2006 (UTC)

It has been claimed that dogs, to catch a frisbee, like baseball players catching a ball, maintain an optical constant angle: How Dogs Navigate to Catch Frisbees. Indeed, if you miss the frisbee/ball and it zooms just past you, the angle will change quickly. It follows that if the angle doesn't change it cannot zoom just past you. Either it hits you (and hopefully you catch it), or it is not approaching. The same strategy may be followed by the diving bird. In a plane, with a stationary target, this implies a logarithmic spiral: the angle between the tangent vector and the vector to the centre of the spiral is constant. I'm not sure what it means in a 3D context. --Lambiam^Talk 02:55, 4 September 2006 (UTC)

drawing molecules

what software do people use on wikipedia to draw and upload the png's of molecules like styrene?

The note on Image:Styrene.png indicates it was drawn with ChemDraw. Images are uploaded with any web browser.- Nunh-huh 17:38, 3 September 2006 (UTC)

An excellent free software is ACD ChemSketch [9]. --Andreas Rejbrand 20:31, 3 September 2006 (UTC)

see also Wikipedia:WikiProject Chemistry/Structure drawing workgroup —Pengo ^{talk · contribs} 12:32, 6 September 2006 (UTC)

600/1000V

I should know this but am ashamed to say I dont. What does 600/1000V mean when marked on single electric cables?--Light current 18:33, 3 September 2006 (UTC)

Cables are marked with all sorts of things. This voltage is the rating of maximum voltage that the wire can hold, and you can hold it in your hand. This is usually welding cable (600 V). All you would want to know is here. [10] --Zeizmic 01:21, 4 September 2006 (UTC)

I could not find the meaning in that source of the 600/1000V rating. Why are there two numbers and a slash? Does it mean that the maximum voltage is (600/1000)V = 600mV? --Lambiam^Talk 03:03, 4 September 2006 (UTC)

Neither could I. Ive seen it on British cables and that ref was for US underwriters labs. So it may be specific to Europe or just UK. The voltage rating is either 600v or 1000v obviously under different conditions. What are those conditions?--Light current 03:10, 4 September 2006 (UTC)

I would guess 600v when enclosed (eg in a duct with other cables) and 1000v when laid in the open.--Shantavira 06:59, 4 September 2006 (UTC)

I believe the first number is maximum voltage between wire and ground, and the second number is maximum voltage between two wires.[11][12]. Weregerbil 12:02, 4 September 2006 (UTC)

Ahh thats it! Thank you!! I thought it had to be something simple--Light current 12:51, 4 September 2006 (UTC)

So its probably single phase against 3 phase. Notice 1000 = 600 x sqrt(3) (approx). I wonder if this applies to all the other dual voltage specs.--Light current 13:30, 4 September 2006 (UTC)

600 watts/1000 volts perhaps? --Proficient 17:47, 4 September 2006 (UTC)

I dont really think so!--Light current 00:45, 5 September 2006 (UTC)

An extract from BS 6231:2006 Electric cables. 600/1000 V PVC insulated cables for switchgear and controlgear wiring here (BS=British Standard) says that 600/1000 V cables are "intended for use at alternating voltages not exceeding 600 V to earth, and direct voltages not exceeding 1000 V to earth". It's puzzling that the ratio between the two numbers is not √2, but perhaps this is to allow for distorted power waveforms that have higher crest factors than pure sine waves. --Heron 20:47, 4 September 2006 (UTC)

So now we have two contrdictory stories. One from BSI and one from a US cable manf. So obviously these markings do not mean the same here as they do in the US!--Light current 00:50, 5 September 2006 (UTC)

600/1000V shows that the cable is a Trirated Cable, rated by CSA and UL to 600V and BS6231 to 1000V. [13]

Question about getting fluids Intravenously

I've tried to read Intravenous therapy, but if the answer is there, it's either been added since I last checked, or I didn't understand it. What I'm wondering is, in as basic terms as possible, how does the body accept fluid in an IV? I can understand drugs, cause those are supposed to be going in the bloodstream, and get there whether taken orally or any other way. But I'm just talking about fluids, like for dehydration. I'm sure (I guess) that when you drink water, some of it goes into the blood, but surely not all of it, the rest.. comes back out. Yet if given water (or, water/solution, whatever it is they actually give you) in an IV, it somehow still ends up being excreted. How does it not just all end up watering down the blood, but actually gets everywhere it needs to go, as it would from the stomach? -Goldom ‽‽‽ ⁂ 20:10, 3 September 2006 (UTC)

in the drinking case, the water that comes back out comes out via the bloodstream, after being absorbed from the small intestine and then collected at the kidneys. so when you get drugs by iv, you simply cut the intestines out of the loop, and pee out the excess as normal. Xcomradex 21:36, 3 September 2006 (UTC)

I think you have a basic misunderstanding of how water is distributed normally. The way it gets from the intestines to everywhere else is via the bloodstream. That is, it gets absorbed thru the intestinal walls into the bloodstream, then is delivered to the individual cells via capillaries, and is then absorbed thru the cell walls. Excess water is absorbed from the bloodstream by the kidneys and the excreted as urine. The only parts that may be dried out as a result of getting all your fluids intravenously are within the digestive tract. While your body has some capacity to keep the mouth and digestive tract moist with saliva and mucous (generated using water from the bloodstream), this capacity can be reduced by certain conditions or medications. If this method is reduced and liquids are no longer consumed normally, dry mouth can occur. For this reason, nurses will frequently dab the mouth with moist swabs or give the patient ice chips (if they are awake), to alleviate dry mouth. StuRat 22:26, 3 September 2006 (UTC)

Also, eating food but not drinking any fluids would be bad, causing constipation. Fortunately, if a patient is not allowed or able to drink fluids, then they aren't allowed or able to eat, either. StuRat 22:31, 3 September 2006 (UTC)

TFTs v CRTs

How reliable are TFTs now? Are they as reliable as CRTs?--Light current 20:53, 3 September 2006 (UTC)

I doubt it, you can have CRTs which are over 20 years old. I doubt that TFTs can last that long. --liquidGhoul 23:40, 3 September 2006 (UTC)

Any ideas how long TFTs last?--Light current 23:55, 3 September 2006 (UTC)

Shouldn't CRTs last pretty much forever? I know that TFTs don't, but not for how long. I remember reading about organic LCD screens, the are supreme in all areas concerning the picture, but they die in a few years. — [Mac Davis] (talk) (Desk|Help me improve)

Not for ever. See [14] 01:59, 4 September 2006 (UTC)

My Sony GDM FW-900 CRT (a pretty expensive one) died after three years, just after the Sony waranty expired. I had to resort to legal threats (based on the EU legal waranty) to get them to replace it. DirkvdM 07:48, 5 September 2006 (UTC)

Yes but was it the tube itself that failed? THats what im asking about--Light current 19:46, 6 September 2006 (UTC)

Fructose - how much is too much?

The fructose article says that eating fructose has some negative effects. How much is too much? How many apples is too much, so to speak. Thanks// Jack Daw 20:53, 3 September 2006 (UTC)

The question is equivalent to asking how much sugar is too much. It depends on your age, size, metabolism, activity level, other carb intake, etc. It does appear to contribute more to obesity than an equivalent amount of glucose. alteripse 00:18, 4 September 2006 (UTC)

One politician over here in Sweden reportedly eats 30 apples a day, he's 60+ I'd suppose, quite fit for his age and looks generally healthy. Got me curious... Jack Daw 13:30, 5 September 2006 (UTC)

Fructose is after all, just sugar. As I say, it is not the substance that is toxic, it is the dose. — [Mac Davis] (talk) (Desk|Help me improve)

That's the layman's answer, Mac. The advanced answer is that a mole of fructose may be more harmful than a mole of glucose, because fructose raises uric acid levels (which reduces hepatic sensitivity to insulin) in liver cells, may not be detected as well as glucose by the satiety and metabolic homeostasis neurons in the hypothalamus, and does not serve as an efficient insulin secretagogue in the pancreas. alteripse 01:06, 4 September 2006 (UTC)

Ahh! Fructose will kill us all!!! :) — [Mac Davis] (talk) (Desk|Help me improve)

PS: Sometime's it's the substance that's toxic, not the dose. Uranium for instance has no natural metabolic use in the body - it just sits there and zaps your cells until you get cancer. Any dose above zero is toxic. --bmk

(veering off topic) ... but see radiation hormesis.--Shantavira 07:08, 4 September 2006 (UTC)

BMK, well then you're in trouble, because you've been eating uranium as soon as you started to eat solid food. See the FDA. And your understanding of the risks uranium poses is way off; the stuff is much more chemically toxic than it is radiologically toxic (which isn't difficult, because its hardly radioactive at all). --Robert Merkel 00:48, 5 September 2006 (UTC)