What is Shift: Definition and 653 Discussions

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. L

    Intrinsic Redshift: Current Status and Research

    I came across this Wikipedia article ,http://en.wikipedia.org/wiki/Intrinsic_redshift, that describes the idea of intrinsic red shift but the references seem old. What is the status of this idea today?
  2. R

    Mathematica Mathematica Circular Shift of Array Elements

    Hi All, does anyone know of a mathematica function that efficiently circularly shifts all array elements? e.g. {1,2,3,4,5} -> {4,5,1,2,3} without iterating? The reason I ask is because I have a huge data set I'm working with and right now iterating through is very processing intensive...
  3. B

    Doppler Shift Train Problem

    Homework Statement The Doppler shift was first tested in 1845 by the French scientist B. Ballot. He had a trumpet player sound a 463 Hz note while riding on a flat-car pulled by a locomotive. At the same time, a stationary trumpeter played the same note. Ballot heard 5 beats/s. How fast was...
  4. N

    Understanding the AC Stark Shift in a 2-Level Atom

    Homework Statement Hi In my book, they do calculations on a 2-level atom. After some approximations, they reach the following equation for the coefficient for the first (lower) level: c_1(t)\approx c_1(0)e^{-i|\Omega|^2t/\delta} where Omega is the Rabi frequency and delta is the...
  5. S

    Which scattering angle corresponds to the largest Compton shift and why?

    Homework Statement An electron initially at rest is scattered by a photon. a) Which scattering angle corresponds to the largest Compton shift and why? b) At what minimum photon energy can half of the photon energy be transferred onto the electron?Homework Equations \Delta \lambda = \lambda_2 -...
  6. J

    Conservation of energy and red shift

    If due to redshift, light shifts towards the red end of the spectrum and the energy of photons = hc/\lambda, then how does this reduction in energy of the photons not violate the conservation of energy law?
  7. F

    Valence Band Shift of n-Type Semiconductor

    What does it mean if the valence band of a n-type semiconductor shifts towards lower binding energy after deposition of a metal on-top. Is it simply charge transfer from the metal towards the semiconductor or vice versa? I mean , the valence band is fully occupied, so there are no states for the...
  8. S

    Exploring the Differences Between High and Low Red Shift Galaxies

    How do high red shift galaxies differ from low red shift galaxies? Dow e see significant differences? if so what ?
  9. W

    Capacitance linking to phase shift

    Hi, I'm looking for an equation which links capacitance to the phase difference between two microphones (picking up audio from a loudspeaker). (the speaker gives off a signal at 3 kHz). My experiment, at the end of the process, was devised to be linked into the setting of microphone...
  10. M

    Find the amplitude and phase shift of an oscillating spring?

    Homework Statement A 205 g mass attached to a horizontal spring oscillates at a frequency of 4.60 Hz. At t =0s, the mass is at x= 6.00 cm and has v_x =- 34.0 cm/s. Determine Amplitude and Phase Shift. Homework Equations x(t)=Acos(\omega*t) \omega=(2*\pi)/T T=1/f The Attempt at a...
  11. S

    Amplitude of wave stretched as well as red shift?

    The expansion of spacetime stretches and red shifts the wavelength of light. Is the amplitude of the wave stretched as well? So that very distant stars appear brighter, and therefor nearer?
  12. S

    Finding Eigenvalues using Double Shift QR Method

    Homework Statement Let T be an 8 x 8 symmetric tri-diagonal matrix with 20 down the main diagonal and 4887227 down the super and sub-diagonals. Use the explicit double shift QR method to find all the eigenvalues of T to at least 12 significant figures. I am using MATLAB to find the QR factors...
  13. R

    Doppler Shift at Right Angles Confusion

    Hi, I'm reading "The First Three Minutes" by Steven Weinberg And am confused about this paragraph... "Astronomers are able to measure the motion of a luminous body in a direction directly along the line of sight much more accurately than they can measure its motion at right angles to...
  14. marcus

    What caused the shift of interest in quantum cosmology?

    This raises an interesting physics question. What physics reason could there be for the shift of researcher interest in quantum cosmology which this Inspire search illustrates? Here is the Inspire top ten quantum cosmo list for 1996-1998...
  15. B

    Simple Harmonic Motion- Phase Shift Help

    Homework Statement A 590.0 g mass oscillates with an amplitude of 11.4 cm on a spring whose spring constant is 27.7 N/m. At t=0.00 s the mass is 3.14 cm to the right of the equilibrium position and moving to the right. Homework Equations x(t)=Acos(Wt + phi) The Attempt at a Solution...
  16. Kawakaze

    Red shift and narrowband filters

    Im planning on trying out some narrowband filters to hopefully dodge the light pollution here and get some nice photos, I was just wondering if red shift ever comes into play, could a distant object be shifted enough to be actually blocked by the filter? I know it depends on the filter and so...
  17. G

    Opinions on Red Shift? Discuss Here

    in my simple opinion the red shift is caused by the increasing distance of the light source and the light destination. its accepted by everyone that light has a constant speed in space, but i think that the constant speed is relative to the source object (kinda like sound). so to keep it simple...
  18. C

    How Does Redshift and Lambda-CDM Model Explain the Universe's Expansion?

    I would first like to thank everyone on this website. So much knowledge i haven't been able to leave. I am researching the time line of the universe and have read a lot of great articles about red shift and the Lambda-CDM. I found a Cosmology Calculator where you can find out the distance in...
  19. A

    [Cosmology] Red Shift Problem

    Homework Statement The redshift of a galaxy is measured at the present epoch t0 and again at the infnitesimal future epoch t0 + δt0. Show that the rate of change of z with t0 is given by \frac{dz}{dt_{o}}=(1+z)H_{o}-H(z) Homework Equations Hint - Start From: \frac{\delta z}{\delta...
  20. N

    Blue shift galaxies and the expanding universe

    We are told the universe is expanding because galaxies are red shifted and that it is a doppler effect. Do blue shifted galaxies contradict the idea of an expanding universe?
  21. R

    Question regarding red shift and tired light hypothesis

    The idea that distant objects are receeding from us and thereby producing a proportional redshift --seems to be a fundamental tenant in terms of current cosmological thinking and theory. There have been alternate ideas proposed in the past including the tired light hypothesis-(whereby light...
  22. N

    Is Phenyl Shift Better Than Methyl Shift in Carbocation Rearrangement?

    why is phenyl shift better than methyl shift?
  23. E

    Exploring the Red Shift in Stars: Uncovering the Mysteries of Our Galaxy

    When I look at the stars in the sky with my undressed eye, they are blue. But pictures of stars taken by scientist always show them as red. Does this mean that the stars in our galaxy are fairly stationary and/or moving closer to earth? Will I find that most red shifts will be seen in stars...
  24. A

    Doppler Shift Light from another galaxy

    When we analyze the light coming from a distant galaxy, we find a particular absorption line with a wavelength of 1118 nm. This same absorption line in light from the sun has a wavelength of 625 nm is this galaxy moving towards us or away from us? Calculate the magnitude of the velocity of...
  25. L

    Geometry of Signals and its Relation to Time Shift

    On page 7 of the attached document, it says that because "the above geometry does not depend on t", the trajectory of the first signal must be the same as the trajecotry of the second, just shifted by \Delta t. I don't understand: a) how it doesn't depend on t? there's a dt in the formula...
  26. A

    Photon Red Shift Energy losses in expanding universe theories

    The evidence points to an expanding universe, we tell this by looking at the redshift/distance relationship, objects further away are receding faster, with their redshift and distance at an almost linear relation. My question is, the photons emitted by those objects that we are just now...
  27. fluidistic

    Trying to understand a constant in the phase shift (or difference?) of 2 waves

    I'm reading through Hecht's book on Optics and I fail to understand something. I think it's the third edition, page 380, chapter 9 (Interference). So he's talking about spherical waves emitted by 2 sources. He says that the waves can be written under the form \vec E _1 (r_1 ,t)=\vec E_{01}...
  28. K

    Why perihelion shift and not aphelion?

    Hi.. The explanation of the perihelion shift of Mercury was one of the major victories of GR. But since the whole orbit precesses, why do people always talk about the perihelion shift and not, say, the aphelion shift? Is the perihelion shift easier to observe or something?
  29. J

    How to eliminate phase shift between signals?

    hello friends, I have a voltage and current input signal in simulink which has a small phase shift between the two signals. Is their a way so that i can eliminate this phase difference to zero? thanks
  30. P

    Doppler shift question (galaxy movement)

    Homework Statement In a distant galaxy, an emission line of hydrogen that has a rest wavelength of 656 nm has an observed wavelength of 662.6 nm. Is the galaxy moving away from us or toward us? How fast is it moving in (km/sec)? Homework Equations velocity = ((shifted wavelength -...
  31. K

    AC circuits, Inductance and phase shift.

    Homework Statement An electric motor draws a 1A (rms) from the 230V (rms) mains. and is found to shift the phase of the 50Hz alternating current by 30% of the period. What is the self inductance of the coils in the motor? Homework Equations The Attempt at a Solution i've started...
  32. J

    Understanding Doppler Shift: Impact on Sound Waves and Airplane Movement

    Imagine this scenario: An aeroplane emits a sound wave. The sound wave propagates in all directions. a) If the plane is flying forward, it emits a sound towards a reflector in front of it. When the sound is reflected, its frequency is reduced, presuming the plane is traveling towards the...
  33. P

    What Causes the Discrepancy in Doppler Shift for Satellites in Orbit?

    At page http://www.qsl.net/vk3jed/doppler.html" is discussed Doppler shift at various ham radio frequencies. I calculated for this Doppler shift relative velocity of their satellite as 6720 m/s. Their satellite in height of 800 km above ground and at circular orbit should have velocity of 7453...
  34. F

    Perturbation Theory - Shift of Ground State

    Homework Statement Use leading order perturbation theory to calculate the ground state shift of hydrogen due to perturbation: \hat{V} Homework Equations 1. Leading terms in expansion of energy: E=mc^{2}+\frac{p^{2}}{2m}-\frac{p^{4}}{8m^{3}c^{2}}+... 2. \hat{H}=\hat{H}_{0}+\hat{V} where...
  35. TrickyDicky

    Gravitational redshift from doppler shift

    Hi, I'm interested in the derivation of the gravitational redshift formula from the Doppler shift in an accelerated frame formula (or viceversa), that are linked by the Equivalence principle, it should be pretty straightforward but I get stuck. Anyone can show me this or point me to a link with...
  36. mrspeedybob

    Light, gravity, and red shift.

    Light responds to gravitation. Light has momentum. Given these two postulates it follows that if a photon passes a massive body both the photon and the body will be effected, though admittedly the effect on the massive body will be extremely slight. Put another way, a photon has its own...
  37. M

    Laplace transform with time shift

    Homework Statement I need to find the Laplace transform of t*e-t*u(t-tau) 2. Homework Equations and attempt at solution I know the general form of the transform, but my problem is in the time shift of the step function. If both parts of the expression were (t-tau), then I could just...
  38. V

    Shift and convolution in matrix form

    The operators act on a vector to produce another vector. They are matrices, therefore. For instance, the backward shift (aka delay) operator, z, acting on vector, say y, translates k-th element into k-1-th: zyk = yk-1. It is normally z-1 in z-transform but I will ignore the difference where it...
  39. S

    Understanding Doppler Shift in Radio-Equipped Plumbing Vans

    Problem: Three radio-equipped plumbing vans are broadcasting on the same frequency,f0. Van 1 is moving north of van 2 with speed v, van 2 is fixed, and van 3 is moving west of van 2 with speed v. what change in frequency (f-f0) does van 3 hear from van 2? From van 1? Attempt at solution...
  40. C

    Frequency shift of emitted photon due to recoil

    (From Bransden and Joachain Chapter 1 problem 21): Show that the fractional change in the frequency of a photon absorbed or emitted by an atom initially at rest is (f-f0)/f = +- hf/(2Mc^2) where M is the mass of the atom and f0 is the frequency of the transition uncorrected for the recoil of...
  41. M

    Speed inorder to shift green light to blue light?

    Hypothetically if your in a jet or spaceship & are shining a green laser pen out the window how fast must you travel to cause the green light (570 nm) to change into low energy blue light (475 nm)
  42. R

    Red shift of light and expanding universe - Your help needed.

    This relates to Doppler's effect. The phenomenon: It is quite simple and says that light emitted from a moving object will be redshifted when the object is moving away from us (earth) and blueshifted when the object is moving towards us (earth). I was thinking of this phenomenon and arrived...
  43. S

    Red shift, gravity, and dark energy.

    When matter is transformed into light energy within a star, the gravity associated with the matter is now associated with the light's energy. As space expands, the redshift is dilluting the light's energy and reducing the gravity associated with that energy. Would the energy dillution further...
  44. S

    Is blue shift a potential problem for near light speed travel?

    I've heard that future spaceships traveling at near the speed of light will have to deal with massive amounts of radiation due to interstellar gas. I think these spaceships might also have to deal with radiation from star light being blue shifted. How close to the speed of light would one have...
  45. P

    Laps and Shift Function: Understanding the Role of t^a in Wald's GR Book (p.255)

    Could anyone explain me what is the interpretation of t^a filed in Wald's GR book (p.255). It's defined as any (?) field which fulfills condition t^a \nabla_a t , where t is "time function". What is the difference between g^{ab}\nabla_b t and t^a. Thanks for answer.
  46. R

    How do I calculate the gravitational red shift for a white dwarf star?

    Homework Statement After a star like the Sun has exhausted most of the hydrogen in its core it expands and cools to form a red giant. Eventually, when it has exhausted all its nuclear fuel, it sheds its outer layers and contracts and becomes a white dwarf of similar size to the Earth as...
  47. E

    Red Shift & Time: Can Time Be Expanding Too?

    Hello! I'm brand new to the forum and have a question that has been nagging at me for some time. I've read a great number of articles regarding the red shift, as well as time being a dimension. I was wondering if anyone has addressed the possibility that time might also be subject to the red...
  48. O

    Understanding Young's Double Slit Experiment: Why 4.5 Fringes Shift?

    I have a problem on Young's double slits which says that the central bright fringe shifts 4.5? fringes after a piece of plastic is placed in front one of the slits. My question is: Why is the central bright fringe shifted for 4.5 fringes? Shouldn't it be 0.5 fringe instead since maximum...
  49. P

    4-Bit Shift Register in Verilog

    This is basically a continuation of a previous problem I submitted. I worked out the previous problem, now I need to figure out another problem. This 4-bit shift register won't load the number I am trying to load. I have exhausted every possible error where it could be wrong. I commented...
  50. D

    Oscillation conditions: Feedback phase shift

    One of the conditions for oscillation is that the (regenerative) feedback loop must provide a 180 degree phase shift. This is due to the fact that, for a regenerative effect, the signal must undergo n*360 degrees phase shift: 180 from the amplifier and another 180 from the feedback network...
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