Shift Definition and 653 Threads

Shift work is an employment practice designed to make use of, or provide service across, all 24 hours of the clock each day of the week (often abbreviated as 24/7). The practice typically sees the day divided into shifts, set periods of time during which different groups of workers perform their duties. The term "shift work" includes both long-term night shifts and work schedules in which employees change or rotate shifts.In medicine and epidemiology, shift work is considered a risk factor for some health problems in some individuals, as disruption to circadian rhythms may increase the probability of developing cardiovascular disease, cognitive impairment, diabetes, and obesity, among other conditions.

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  1. E

    S-wave phase shift for quantum mechanical scattering

    a.) The potential is a delta function, so ##V \left( r \right) = \frac {\hbar^2} {2\mu} \gamma \delta \left(r-a \right)##, therefore ##V \left( r \right) = \frac {\hbar^2} {2\mu} \gamma ## at ##r=a##, and ##V \left( r \right) = 0## otherwise. I've tried a few different approaches: 1.) In...
  2. K

    I Is the Isotope Shift the Same for Different Vibrational Levels in Molecules?

    Hello! Is the isotope shift between 2 (low lying) vibrational levels of the lowest 2 electronic levels (of a diatomic molecule) the same, no matter what the 2 levels are? For example, is the isotope shift associated to the ##0 \to 0## vibrational transition of 2 molecular isotopes (here I mean...
  3. J

    B Redshift & Energy Conservation: Questions Answered

    Hi, I have read over several threads already on this and have a few questions if someone could please answer that would be great: 1) The threads seem to suggest that energy is not conserved (or at least it isn't a requirement) on the scale of the universe. Why does it not have to be conserved...
  4. nima_kheradhoosh

    How can I apply a variable phase shift to an AC signal generated by a VFD?

    Hey fellas, I’m trying to apply a variable phase shift (0 to 180 degrees) on an AC signal generated from a Variable Frequency Drive (VFD). The frequency is variable and ranged between 10 and 50 Hz. the voltage amplitude is also variable between 10-50Volts (this shouldn’t be a problem I suppose)...
  5. Z

    Threshold voltage shift vs temperature

    In a field effect transistor, does the threshold voltage decrease with increasing temperature? Imagine that there would be an increase in thermally generated carriers and thus the device would reach saturation faster? I realize the mobility would decrease, but the increase of thermal carriers...
  6. centinela20

    How to calculate the horizontal shift?

    I don't understand what horizontal shift means. I believe that means calculate the horizontal component of a_cx. But when I do that a_{cx} is in terms only of the angle and the radius of the earth. But what I need is to include the 50 m vertical distance, so I think that maybe we need to use...
  7. Z

    I How to calculate the Lamb Shift in Hydrogen?

    This recent article (https://www.quantamagazine.org/physicists-finally-nail-the-protons-size-and-hope-dies-20190911/) on the size of the proton left me with a couple of confusing questions: 1/ Is the amount of the lamb shift completely determined by Feynman diagrams or is "it spends part of its...
  8. jeffinbath

    B Is there more to the Red Shift than we think?

    How can we be certain that it is not the case that a minor proportion of the red shift from distant galaxies is not caused by the doppler effect or by gravitational fields or by dispersion from cosmic dust but is caused by a light aging factor? There is a small general red shift from stars held...
  9. M

    Hydraulic/pneumatic paradigm shift

    Subsequently, I had the idea to keep cylinder ends stationary, and to find some ways to expand the cylinder wall so to speak. I have done some preliminary work in this area, and in looking at what happens to the volume of fluid itself reveals quite a few incredible things, and opens up a very...
  10. E

    Shift in wavelength of photons from the Sun using energy argument

    I came across a question recently which involved calculating the change in wavelength of a photon between being emitted from the surface of the sun and arriving at the Earth. The method that was implied involved calculating the GPE's of the photon (assuming the photon to have a mass h/[c...
  11. D

    I have tried building a phase shift oscillator, but it won't work

    I built a phase shift oscillator, but it Won't work. I visit the website https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Phase-shift_oscillator&ved=2ahUKEwiV4Y-26OHiAhUClawKHQhACO8QFjANegQIChAG&usg=AOvVaw0YoHKumGz0Xl3fYKtIRdFa and copied the schematic I saw...
  12. S

    B Phase shift in Mach-Zehnder interferometer

    I'm confused by the phase shifts in a Mach-Zehnder interferometer because I keep finding two different explanations. One explanation (for example, given on Wikipedia, but also elsewhere) states that on each reflection, the phase shift is 180 degrees, but only, if light is reflected from the...
  13. W

    Linear Feedback Shift register of size 2^7

    From this table: Looking at the 7 row and taking the first entry, 1 This is 000001 Adding back the highest and lowest bit: 10000011 And then the equation would just be x^7 + x +1 ? Or taking the taking the third entry, 7 This is 000111 Adding back the highest and lowest bit: 10001111 And...
  14. AwesomeTrains

    I Help understanding the formula for the total phase shift of a waveplate stack

    I have problems deriving a formula in a paper I'm reading for a project. The paper is about putting a number of waveplates in series rotated relatively to each other to form a tuneable broadband waveplate. For the i-th waveplate the jones matrix is given by: $$ J_{i}(\delta_i, \Theta_i)=...
  15. P

    A No hidden variables in QM - a paradigm shift?

    If we would learn (somehow) that the pilot wave theory is false, that there are not even "non local" hidden variables, would this lead to a paradigm shift in physics? I ask because it would mean that a Laplace demon wouldn't even in theory able to predict the exact future motions of particles...
  16. D

    Why Won't My 74HC595 Shift Register Outputs Turn Off?

    I bought a 74hc595 shift register. The 1st output and 2nd output won't change. They turn on two diodes and none of them will turn off. How do you get the 1st output To output a zero? I have studied the Datasheet doesn't help.
  17. A

    A How, and in what atoms does the Lamb shift occur?

    The Uehling potential due to vacuum polarization by virtual electron-positron pairs is said to be the dominant contribution — 205.0073 meV — to the Lamb shift between the 2P1/22P1/2 and 2S1/22S1/2 states of muonic hydrogen. In the Wikipedia page (https://en.wikipedia.org/wiki/Lamb_shift), it is...
  18. S

    B [Curiosity] Are there any central databases of Red Shift?

    I'm curious to know if there are any central databases of red shift - whether stars, galaxies or other objects.
  19. D

    Beat frequency and Doppler shift

    I found the beat frequency to be 4 Hz and the carrier frequency to be 260 Hz, but I'm not sure how to apply them to the solution/integrate the doppler and beat frequency equations?
  20. R

    Am I understanding horizontal shift properly?

    Homework Statement I mean, it does make sense, if I plot f(x)= x^2 and f(x-1) = (x-1)^2 and find where they intersect the x/y axis, it does make sense. But the book I'm reading (Stewarts) confuses me with the following:"Likewise, if g(x) = f(x-c), c>0, then the value of g at x is the same as...
  21. L

    How to introduce a phase shift in an AC circuit

    Hello, I am trying to think of a way to introduce a phase shift in an ac circuit. For example, sin(omega*t+theta) to change theta. How can I go about doing this? I do not think introducing a cap or inductor would work, even though it shifts the voltage from the current graphs (phasors). A...
  22. R

    I Exploring the Lamb Shift: G-Factor & Angular Momentum

    Good day dear forum, greetings from Argentina. I am studying the Lamb Shift, which says that in the atomic orbitals, an upward energy shift occurs due to an interaction of the electron with itself. This means that a level s can have an energy slightly greater than a level p. So far so good, but...
  23. B

    I Phase shift after double-slit for entangled photons

    Hi all, I'm trying to understand how to describe the quantum state of entangled photons, including their phase, if one of them encounters a double-slit. Here's a simple example: Suppose you have two polarization-entangled photons A and B in the following Bell state: \begin{equation}...
  24. P

    I Why is the Phase Shift in Grover's Algorithm Applied to All Elements Except 0?

    Hi everybody, I've read some pages in Nielsens "Quantum Computing" book, it's very interesting, but especially at Grover's algorithm, there occurs a question for me. It is said that a phase shift is performed, which is defined as follows: ##|0\rangle \rightarrow |0\rangle \\ |x\rangle...
  25. wlc88

    B The Red Light Shift and Space Debris

    Hi, As I understand it the theory that the universe is expanding is in part based off the red light shift. My question is could atoms in space, dust etc cause the red light to travel faster. I realize that space isn’t a medium, but could the aforementioned atoms and dust exist in such...
  26. W

    I How many galaxies do we have red shift data for?

    Im wondering does anyone know roughly how many galaxies we have red shift data for, just a ball park. Is it hundreds? thousands? millions?
  27. L

    MATLAB Can I know the reconstruction of phase shift interferometry in Matlab

    I want to know the reconstruction of phase shift interferometry by angular spectrum method in matlab
  28. S

    I How to differentiate Doppler shift from star emission

    I have seen people talking about measuring Doppler shift of stars to know how fast they are receding from us. But if I measured say a particular frequency f, how do I know whether this is shifted frequency or just the emission?
  29. B

    Phase shift and circular polarization

    What is the phase difference between the right circularly polarized and left circularly polarized light of the same amplitude? And how do you calculate it?
  30. FactChecker

    B Lightning Flash Intensity & Color Shift for Moving Train Observers

    Consider the traditional thought experiment of moving train observers, the "stationary" observers, and the flash of a lightning strike at the midpoint of the train. It seems that the stationary observers would expect the train observers to see different flash intensities (due to different...
  31. J

    A Why does Efm shift in MOSFETs?

    Hi, I'm studying MOSFET and the book says that when N-channel mosfet has negative or positive gate voltage, the energy band diagram will shift. I don't understand why Efm shifts. Now when Vg is negative the Efm shifts upwards, Why? And when later when Vf is positive the Efm also shifts again? I...
  32. B

    Laplace Transform Time Shift Property

    Homework Statement I’m being asked to prove if and why (what instances in which) T<0 for the Laplace transform property of time shifting doesn’t hold. Homework Equations L{f(t-T)}=e^-aT* F(s) The Attempt at a Solution I know that for T<0 there are instances where the property cannot hold, but...
  33. entropy1

    I Frequency spectrum of phase shift

    What does a 180 degree phase shift of a sinusoidal in a signal do to the frequency spectrum of the signal?
  34. gmalcolm77

    I Red Shift Energy: Understanding the Light Phenomena

    I find it difficult to conceptualize red shift when thinking of light as a stream of photons. In thinking of it as a wave phenomena, I can see it as a matter of a given energy concentration/area. But why should a photon lose energy as a result of the velocity of the emitter?
  35. opus

    Finding amplitude, period, phase shift on uglier functions

    Homework Statement State the amplitude, period, phase shift, and vertical shift: ##y=\frac{5}{2}sec\left(\frac{π}{x}-4π\right)-2## Homework EquationsThe Attempt at a Solution [/B] Amplitude: Amplitude is equal to the absolute value of a. So the amplitude here is ##\frac{5}{2}## Vertical...
  36. DarkMattrHole

    I Does red shift approach infinite near time zero?

    Hi. I'm trying to get an idea how to look at the beginning, before the cosmic background radiation (CBR) and what we can detect with our eyes, and what we can assume about earlier times than light was around. I was looking into the red shift effect effect, as not only a measure of relative...
  37. P

    I Classical waves and the Doppler shift

    In the video: The professor mentions how the wavelength will be the same for a moving observer vs a moving observer for a classical wave like a sound wave. However, how does that explain doppler shift? Don't we observe the effect because a moving observer measures a different wavelength than a...
  38. K

    Doppler shift of a hydrogen line on sun

    Homework Statement Homework Equations [/B] delta lambda/lambda = velocity/speed of light radius of the sun= 696 *10^6mThe Attempt at a Solution Hello, the solution states the correct answer for this problem is 5.8*10^-12m. This is exactly 2x my answer but i don't really know what i did...
  39. J

    I Have we measured the change in the red shift over time?

    Have experiments been done to measure the red shifts of distant objects over time? If inflation is correct, the the speed at which an object is receding relative to us is based on how far away that object is located. Therefore, the most distant objects would also have the highest acceleration...
  40. isukatphysics69

    Phase Shift in Sinusoidal Functions: Solving for Φ in Different Cases

    Homework Statement Homework Equations Asin(wt + Φ) The Attempt at a Solution let t = 0 Case A: -.10 = .20sin(Φ) sin-1(-.10/.20) = Φ = -0.52 Case B: .10 = .10sin(Φ) sin-1(.10/.10) = Φ = 1.57Case C: -.05 = .05sin(Φ) sin-1(-.05/.05) = Φ = -1.57Case D: 0 = .20sin(Φ) sin-1(0/.20) = Φ = 0 Now...
  41. C

    I How does the thickness of a beam splitter affect the phase shift produced?

    I'm having trouble understanding the phase shift produced by a beam splitter. I seem to be finding conflicting information. I'm specifically looking to understand a 50/50 beam splitter where one side has a dielectric mirror, as shown in this figure from wikipedia: I understand the pi...
  42. jfizzix

    Does pitch perception shift up while growing up?

    I think this question boils down to whether the parts of the inner ear grow from say age 6 to age 26. My thought is that if the parts of the inner inner ear do grow a little, then their response to what was a shorter wavelength of sound in the past will be the same as to what is a longer...
  43. Teslascience

    I Do dark matter and dark energy have an effect on the red shift?

    Do dark matter and energy affect on red shift phenomena? If yes, what, and what is the consequence of it?
  44. itoero

    B How does the Doppler shift explain changes in photon energy without interaction?

    According to doppler shift you can measure low energy photons at one side of a star and higher energy photons at the other side of a star. How is this possible? I know the classical explanation but what happens on an atomic level?
  45. neilparker62

    I Exploring the Ground State Lamb Shift: Advances and Controversies

    What exactly is the so-called "Ground State Lamb Shift". It seems to have been an 'in vogue' quantity up till 1995 or so - then vanished from the literature ?? It's the 'self energy' or something like that of an electron in H 1S orbital. A scientist (at NIST) told me it's a term that has gone...
  46. W

    How Does the Hamiltonian Affect the Time Evolution of a Qubit's Density Matrix?

    Homework Statement In a computational basis, a qubit has density matrix ## \rho = \left( \begin{array}{ccc} \frac{1}{2} & \frac{1}{3} \\ \frac{1}{3} & \frac{1}{2} \\ \end{array} \right)## At t=0. Find the time dependence of ##\rho## when the Hamiltonian is given by ##AI+BY##, ##A## and ##B##...
  47. Mohammad Fajar

    B Why Light Experienced a Doppler Shift?

    It's already known in physical communities that the velocity of light always constant and not depend on motion of observer or source. But it is also teached to us that there are aslo Doppler shift experienced by light wave like that when measuring CMB radiation. But for me it is makes a...
  48. M

    MHB Is the list a circular shift of the other?

    Hey! :o I want to write a progarmm in python that reads two lists A, B and checks if the one of the lists is a circular shift of the other list. The result is either True or False. I thought to do something like that: if sorted(A) == sorted(B): C = True else: C = False But it cannot...
  49. Buckethead

    B Why do photons allow Doppler shift

    If we (a detector) are moving toward a star that emits a single photon (due to its distance) and that photon hits our detector, it will be blue shifted. My question is why. If the color of a photon is a reflection of its energy level and since the speed of the photon is always coming at us at...
  50. M

    Question regarding phase shift between two signals

    Homework Statement Two sinusoidal voltages with amplitude 15Volts and frequency 2,771Hz are separated in time by 68% of a period. What is the phase shift in degrees between the two signals?Homework Equations y= Asin(omega)(x-h) The Attempt at a Solution I know my A is 15 and I'm pretty sure...
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