# Search results for query: *

1. ### International Change Electric Charge Day

Hello. What would you think of the international scientific community calling to change all negatively charged particles to positive and vice versa? Do you think there's a circumstance where we should switch or should have switched? The only reason I brought this up is that it came up when...
2. ### Finding a closed form expression given decimal approximation

One thing I don't quite understand yet: Evaluating the approximation to these (with several bases) leads to a value that appears to always be less than using Ramanujan's method. For example: let n = 4 (where n is the base of powers under the radical) and you get: t^2-2t-1=0 t=1+\sqrt{2}...
3. ### Finding a closed form expression given decimal approximation

I've made a nice little excel file to help study these. Interestingly, if you use 4 as a base, it seems to converge to exactly 2. It's the only number so far that I've seen do this. I've tried powers of 2 up to 2^16, and those appear non-rational so far. If anyone wishes to use it, you'll...
4. ### Finding a closed form expression given decimal approximation

Thank you guys! It's a lead!
5. ### Finding a closed form expression given decimal approximation

Good evening. Is there a way to take a decimal approximation and see if there is a relatively simple expression? I'm guessing there might be software for this, but I'm not sure I'm even asking the appropriate question. If it matters, the number I'm after is...
6. ### Water activity meter reading over 1

Thank you for all the posts here. I've decided the readings above one are probably from hysteresis, probably due to a difference in frequency of sampling temperature and mirror fogginess. The makers of the device (it's an Aqualab 4) could assume that people would only use the result at a stable...
7. ### Water activity meter reading over 1

Good evening. I recently was taught how to use our new water activity meter, and I noticed something strange. This meter uses changes in the reflectance of a mirror. Whenever we'd bring the sample up to temperature, the measurement would reach a low point, then at about 0.5° below our set...
8. ### Guide 34 pH Buffers

Hello! Can anyone recommend a good guide 34 and NIST traceable pH buffer vendor. Our experience with our current vendor has left a bit to be desired, and we need a large variety of standards that limits our supply. Thank you for reading this and any help you may offer.
9. ### Ecological pyramids

There are usually a lot less consumers, heterotrophs, than producers, autotrophs, because a portion of the energy will always be lost with each transfer. Some of it will be due to heat loss while other parts will be due the energy required to digest and process the producer.
10. ### Does experiencing a static shock mean that you are grounded?

Keep in mind too, just because you don't feel a shock or later detect a failure of the circuit does not mean you have not damaged it too. This of course depends on the properties of the electronics you're working on.
11. ### Interstellar - Spectacularly Stupid Movie

I went into the film with high expectations, and it more than satisfied me. The story was very well written, and the acting was quite compelling yet natural. The visual effects were absolutely beautiful too. I must now find a way to implement gravitational lensing into my ray tracer.
12. ### Natural Selection, why not even better?

Wheels would be enormously different from current structure in place. How would you grow and maintain an axle? How would you prevent infection there? Any steps on the way to making them would probably be non-functional, and wheels would probably be less agile than limbs for most terrain.
13. ### How can I see Infra-Red and Ultra Violet waves?

Humans can actually see UV light, but you have to lack a lens to do so. http://en.wikipedia.org/wiki/Aphakia
14. ### How imperfect is the human machine

Additionally, skeletal muscles must expend energy to maintain a force even if no work is performed as it takes energy to keep setting filaments into the contracted state. See the paragraphs under "Comparison of Smooth Muscle Contraction and Skeletal Muscle Contraction"...
15. ### Which is larger, Graham's number or

Sorry to link to wikipedia, but you may be interested in TREE(3), and I can't find too much info on it. A is the Ackermann function. http://en.wikipedia.org/wiki/Kruskal%27s_tree_theorem
16. ### How to be better at getting signs, and letters right in algebra?

I had some sloppiness problems with my algebra when I left high school. I don't know if the same causes yours, but one thing that helped me was writing my problems out more neatly in addition to the suggestions above. I thanked myself a lot once my more advanced classes came around.
17. ### Wifi out of range. Options?

You can retransmit an WiFi signal using extenders or certain routers, but I don't think your school will want to do that. The passcode will quite likely be shared with non-students, and it is probably a crime to alter your schools network without their permission. Additionally, throughput and...
18. ### Can light be synthetically created ?

You don't have to have the alternating electric field. In your antenna, the alternating electric field necessarily creates an alternating magnetic field. Creating an antenna for lower frequency waves is not a problem, but as far as I know, no one has created any circuitry that oscillate with...
19. ### Networking with 3 computers

If B and C are both virtual machines, then I am thinking B and C share the same communication channel, right ? I'm not quite sure what you mean by this. Are B and C instances of an OS running on the same computer? If B and C are separate, and B (or your router) is your VPN gateway, simply set...
20. ### Want to know what is the best in terms of friction

http://en.wikipedia.org/wiki/Friction#Approximate_coefficients_of_friction has some static friction coefficient values for lubricated steel on steel. I would not trust these values for any serious work though. The coefficient of static friction gives you an approximation of static friction as...
21. ### Using the greenhouse effect for energy?

The energy coming into the greenhouse will still be proportional to the area of the greenhouse, so the average power available is still only the power of the sunlight hitting the box. This leads me to think that you'd be better off simply heating the water directly with sunlight. Perhaps you...
22. ### High-Vacuum connectors

Your roughing pump shouldn't let air back into the system (at least not very quickly), so you'll at least need a venting valve. NSAspook's recommendation ought to work great. Just remember, try not to get fingerprints on hard to clean areas when you build it. What are the makes and models...
23. ### High-Vacuum connectors

For a typical diffusion pump on an electron microscope, you can expect about a 20-30 minute warmup with a 40 minute cool down time with water cooling. We have a hi-vac valve on top of the diffusion pump though, so we can keep the diffusion pump under vacuum as it cools. That may shorten our...
24. ### High-Vacuum connectors

I'm sorry I can't be more specific since, but hopefully some of this helps. We use Tygon plastic tubing to connect our mechanical pump to our vacuum chamber at my work's lab, but we're only seeking to achieve 10^-5 torr. As for venting your chamber, if you need to rapidly cycled your vacuum...
25. ### Perpetual Motion In The Gravitational Field

I don't understand what relation your other questions have to perpetual motion. If you take an object and place it some distance away from Earth in space, and no other forces change the objects motion, the object will have kinetic energy equal to the work you did to move it when it returns to...
26. ### How do I identify different bacteria on culture plates?

A couple of the most important tests are aero tolerance and gram staining / potassium hydroxide. Aero tolerance testing uses liquid growth media to see if the bacteria in question use oxygen, tolerate it, or die in its presence. Gram staining let's you differentiate between two common cell...
27. ### Plotting 3d graphs

I don't know if it can do vectors, but Microsoft mathematics is free now. It can do equations, inequalities, parametrics, and tables.
28. ### Medical How safe are dental materials?

It's my understanding the mercury amalgam fillings are being phased out too. My dentist mentioned using some sort of porcelain and dental cement mix as an option.
29. ### If an Atom was the size of a grain of salt

Mark44, you may wish to double check that. It's been a while since my chem prof explained this to me, but I believe the additional proton in helium makes it smaller, especially since both electrons are in the same shell...
30. ### Exercise and weight loss

It's in the amaranth family, if I recall correctly. I roast mine a little bit to enhance the nutty flavor, which isn't very strong pre roasting. It's pretty good with onions, peppers, tomatoes, and garlic. You can pretty much treat it like couscous concerning flavoring. For pictures...
31. ### What stage of mitosis can chromosomes be counted and why?

Is this a homework question? Look at how the chromosomes are arranged during various phases of mitosis. Then look at some karyotype photos. What would be convenient about the particular phase in question concerning chromosome structure and placement? Why do the other phases present greater...
32. ### Tips Picking up TEM grids?

Nice tips, thank you very much. I actually prepped my first viable sample today. Our acetone washer is very finicky, and it tends to blow out the form at coating if it's in a bad mood. Hehehe, I remember one of my biology instructors getting extremely angry at a guy for picking up our...
33. ### Tips Picking up TEM grids?

It probably wouldn't, but that's the statement I was given when I asked about them. We do test for asbestos, but if we have asbestos fibers floating around, then we have bigger problems than my ruining grids. Oh, and we use cleaned tweezers under a laminar flow hood, so if they do introduce...
34. ### Tips Picking up TEM grids?

I'm wondering if I can make this task easier, since I've ruined a lot of grids lately. Currently, I'm trying to use tweezers, but I lack the subtlety to grip them firmly enough without bending them. We can't use vacuum on them since it would potentially contaminate our samples. I've thought...
35. ### Do 3 dimensional matrices exist?

Dalcde, I know it's not a book, but this guide helped me out a lot conceptually: http://www.grc.nasa.gov/WWW/k-12/Numbers/Math/documents/Tensors_TM2002211716.pdf I haven't used tensors very often, so I can't really suggest a book.
36. ### L1 and L2 cache? Question

It's my understanding that L2 caches were often external when they first came out but have since been added to the same die on newer processors. On most multicore systems, theyre actually part of the core, and L3 cache is shared between cores. I think I had a pentium system that had an...
37. ### Goldbach conjecture proof

http://arxiv.org/ftp/math/papers/0005/0005185.pdf" [Broken] Is this the paper you were talking about ode_to_joy?
38. ### Reaction of Fructose with Ethanol

Homework Statement Show the reaction of fructose and ethanol. This is an example of the formation of ______. The homework concerns the formation of hemiacetals and hemiketals as well as the cyclic forms of important sugars. Homework Equations None The Attempt at a Solution I believe my...
39. ### Why is the sum of odd numbers is a square

I love finding patterns like that. You may be interested in seeing this: http://mathforum.org/library/drmath/view/56866.html It explains a little bit about induction, and provides a proof by induction.
40. ### Guess the number i bet you lose

2298 is found 109 times 9617 is found 81 7841 is found 97 8283 is found 90 Looks like I'm losing so far. Is Pi not conjectured (but unproven) to be normal? If Pi is normal, people should average nearly 100 finds if they were to conduct a bunch of trials. It's an interesting game. If someone...
41. ### Algorithm to calculate root (or power) in computer

If you are writing it in c++, you can include math or math.h depending on your compiler and use the pow() function. Some other languages have similar math libraries. I suspect your looking for something lower level without functions other than base instructions. This may be of interest to...
42. ### About electrocution when being wet

You certainly can receive a shock with one hand in your pocket. The rule is to help prevent you from getting a hand to hand shock which is generally nastier than a hand to foot. It's harder to have a hand on ground when one is in your pocket.
43. ### Computer shuts down during graphically intense games.

Are you getting a BSOD? If so, make sure your drivers and games are up to date. Every now and then, graphics card drivers get released that screw up. If not, try different power supply and graphics card. Sometimes the temp sensors on those chips is a little too far from the actual die, so...
44. ### ALVEO - Crackpot medical cures

I don't swear by colloidal silver. There's no evidence that it's effective, and it's dangerous. If someone here is thinking about using colloidal silver, I suggest looking at research and talking to your traditional doctor. http://nccam.nih.gov/health/silver/
45. ### Medical Caffeine and nicotine

This sounds like a homework question, but I will give you a hint. Caffeine is an adenosine competitive inhibitor in the CNS while nicotine is a cholinergic at nicotinic receptors in the CNS and SNS. Look at what those mean for differences. For similarities, I would definitely look at their...
46. ### Converting 24min to Hours: True or False?

You seem to have miscalculated the value for \frac{1}{60}. \frac{1}{60} = 0.01666 ...
47. ### Medical Mechanism for compensatory RESPIRATORY acidosis caused by metabolic alkalosis?

It's mostly from slowed respiratory rate. Chemoreceptors lining the blood vessels, especially the carotid bodies detect blood CO2 levels. The decreased partial pressure of CO2 will cause these bodies to send less stimulatory signals to the respiratory center in the medulla which leads to...
48. ### Can you help me to balance this tnx

Indeed I did, my apologies.
49. ### Can you help me to balance this tnx

In the future, you'll want to ask homework questions under Physicsforums -> Science Education -> Homework & Coursework There is probably a mistake on your products side. Instead of HNO2, it's probably HNO3, nitric acid. The equation cannot balance with HNO2. To find your coefficients...
50. ### Graphics Problem

Give us some more information to properly help you, please. What version of windows do you have? Is your OS 32 bit or 64 bit? Have you done windows updates? After you have told me this, I can give you some tips perhaps.