# Clock Definition and 19 Discussions

CLOCK (Circadian Locomotor Output Cycles Kaput) or Clock is a gene encoding a basic helix-loop-helix-PAS transcription factor that is believed to affect both the persistence and period of circadian rhythms.
Research shows that the CLOCK gene plays a major role as an activator of downstream elements in the pathway critical to the generation of circadian rhythms.

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1. ### A What's "const. K" in É. Gourgoulhon "SR in General Frames" eq. (2.11)?

In sect. 2.3.2 "Ideal Clock", p. 33, of É. Gourgoulhon's text book on "Special Relativity in General Frames" $$\tau_C [ \, \text{tick}_{j}, \text{tick}_{(j + N)} \, ] = K_C \, N.$$ (equation (2.11); notation adapted.) The only other reference to this "constant K" is on the following page...
2. ### B Need help designing a clock with a repeating signal

Hello! I am in need of a clock expert. Just a disclaimer, I am vastly unfamiliar with much of the inner-workings of clocks and need some help. I have only built a simple Graham Escapement clock, previously. I need to build a clock that triggers a single signal to occur three times at equally...
3. ### I SR: which clock was slower?

I don't know much about the math of SR, but this is what's bothering me: if a moving clock B ticks slower than the stationary one I have (A), then from the viewpoint of B, my clock (A) is ticking slower. So if we turn around and meet each other in the middle, which clock was slower than which...
4. ### I Why are atomic clocks so accurate?

For any clock, the way I define accuracy of the clock is based on the Q factor (the ability to reject noise) and the inherent noise in the system. In that case, can you explain me why atomic clocks are so accurate? Do they have high Q factor? (if so, how)? or low noise to begin with?
5. ### B Why does GPS require an accurate clock?

Why do GPS need a cesium clock accurate to 10ns? Is this strictly for time keeping or is there some synchronization between satellites?
6. ### B Length contraction applet - have they got it wrong?

Hi, I was browsing the internet for interactive simulations illustrating special relativity concepts. It seems to me that those in this http://kcvs.ca/concrete/visualizations/special-relativity are mostly nice and clear, although not very "chrome-friendly" (I have to use firefox to play their...
7. ### Changing the coordinate system of the hands of clock

I want to understand what changing coordinate system means for hands of clock. Let's say the clock only has hour and minute hand. It can move let's say just in the upper 180 deg. of the clock (as shown in the figure). The area between the two hands is V1, and the rest is V2. Depending on the...
8. ### I Special relativity timebomb on distant planet 'paradox'?

I thought of this 'paradox' which is somewhat similar to the twin paradox but can't be explained by a lack of symmetry etc. It is very similar to many paradoxes I have heard before of which the resolution is known (which is why I am mostly sure this can be resolved) Bob is looking through his...
9. ### I Does a hot clock run slower?

Hi. Temperature is movement on a microscopic scale, and movement leads to time dilation. So what happens if we heat up a clock? Let's for example assume a pendulum with negligible thermal expansion, such that all other thermal effects on the period can be neglected. Will it run slower? What...
10. ### I Clock thought experiment

This is a thought experiment I came up with this evening. It must surely have been considered before but I couldn't find any reference and I've come up with it independently. NASA has positioned a clock in Earth's thermosphere that can be viewed from outer space with a powerful enough telescope...
11. ### How to calculate Clock Skew of nodes in a distributed system

A distributed system has 3 nodes ##N_1##, ##N_2## and ##N_3##, each having its own clock. The clocks of nodes ##N_1##, ##N_2## and ##N_3## tick 800, 810 and 795 times/ms. The system uses the external synchronization mechanism, in which all 3 nodes receive the real time every 30 seconds from...
12. ### SPI Clock Line

From my understanding of how SPI interface works, the clock basically sends out data when it is set to HIGH(or LOW). So, why does it seem like in pictures of the SPI lines, the setting of HIGH and LOW appears periodically. Can't we just put data onto DATA line, turn CLOCK line on to send, then...
13. ### Measuring motion

Dear PF Forum, I'm sorry if I ask the basic question here again. Just need confirmation. V = 0.6; Gamma = 1.25 TRAVEL travels at 0.6c. STAY stays. Pic 02 is Pic 01 boosted -V. 1. All STAY knows about TRAVEL is: Proper Time Speed Is this true? And mutually for TRAVEL 2. At B (and C)...
14. ### Measuring distance, speed and clock

Dear PF Forum, I'd like to know how we measure speed, distance clock in space? ##v = 0.6c \gamma = 1.25## Supposed the distance between A and B is 900 ls. And supposed A and B keeps exchanging signal for 6 seconds interval. Because the distance between A and B is 900 ls, there are 150 signals...
15. ### Why the Shapiro delay is calculated with respect to the....?

Why the Shapiro time delay is calculated with respect to the difference in coordinates and not with respect to the physical distance? I follow the discussion of Clifford (Theory and Experiment in Gravitational Physics) which uses isotropic coordinates and PPN approximation. To make more clear my...
16. ### Speed of Light Question

Hello everyone! Recently my work has been more involved with high energy physics. I have been looking into some things, and I would like help with an understanding of the speed of light. So far, the main ideas I have seen have been thought experiments, with minor (if any) direction to...
17. ### Can clock transport tell us anything important

Clock transport can be used to compare one clock with another in an absolute sense. All we have to do is to transport a clock between two A-frame clocks that have been synchronized per Einstein's definition. Let's call the transported clock "T" and the left-hand and right-hand E-synch'd clocks...
18. ### Has a real clock corrections, with respect to an ideal clock?

Hello In Special (and General) Relativity, has a physical (real) clock corrections, with respect to an ideal (mathematical) clock? For example, the physical clock has mass, so it will affect its own measure. This is only an example I thought, I don't know if there are more corrections...
19. ### Tower Clock Gearing and Motor Speed

Hello all, first post on here. My fathers friend recently died of cancer and he was the person we used to turn to for this question, I've been racking my brain and searching the net for info, found this link (http://www.schsm.org/html/gear_ratio_calculations.html) and have got the ratio down...