What is String: Definition and 1000 Discussions

In molecular biology, STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) is a biological database and web resource of known and predicted protein–protein interactions.
The STRING database contains information from numerous sources, including experimental data, computational prediction methods and public text collections. It is freely accessible and it is regularly updated. The resource also serves to highlight functional enrichments in user-provided lists of proteins, using a number of functional classification systems such as GO, Pfam and KEGG. The latest version 11b contains information on about 24,5 million proteins from more than 5000 organisms. STRING has been developed by a consortium of academic institutions including CPR, EMBL, KU, SIB, TUD and UZH.

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  1. Hatem

    B Vibration Patterns of Strings within Quarks?

    Is it possible to study/observe the virbation patterns of a string within a quark? I understang that String Theory is a theoretical framework, however is it possible to make an observation linking the vibrations of the strings within the quarks to the particles produced? If so, has there even...
  2. I

    Find tension in string between two blocks on horizontal surface

    Did I draw the free body diagram incorrectly by treating the two blocks as one system? My textbook claims the answer is 25 N.
  3. L

    Does a massless string cause a normal force when attached to a wall?

    I'm almost certain that if it was a "steel rod" or something heavy like that, the normal (the force written in green) would exist. But does it exist for a "massless ideal string"? I mean, there is tension in the string of course, but would that cause the normal perpendicular to the wall?
  4. A

    I Distribution of torsion in a steel guitar string

    This isn't a question about torsion pendulums because it goes well beyond linear physics. The question is roughly, how many times can you rotate the end of a steel string, with the other end fixed, before it breaks? Also, how does the torsion distribute along the string? I tried to answer both...
  5. U

    I The impracticality of a TOE

    I am reading a hebrew translation of the popular book by Michio Kaku on HyperSpace. It seems Superstring Theory will never be refuted since if it's a theory of everything then you need infinite energies since the universe is infinite, and we can never get a from finite machines infinite...
  6. C

    Assumptions for string vibrator system

    For this, Is it possible to calculate the time it takes for the initial antinode at the string vibrator to become a node in the transient phase of the system? Also do we assume that once the system has reached steady state, that the mass has such a large inertia that it is stationary so acts as...
  7. B

    Python UnimplementedError: Cast string to float is not supported

    Hello everyone, I have this problem that I can't solve: I have two types of images contained in two different folders. I have to create a dataset with these images and train a cycleGAN model, but for simplicity we assume that I want to print them on monitor and forget the cycleGAN. My code is...
  8. A

    Conservation of power in a traveling wave on a string

    The statement of the problem is: Consider a taut string that has a mass per unit length ##\mu_1## carrying transverse wave pulses of the form ##y = f(x - v_1 t)## that are incident upon a point P where the string connects to a second string with mass per unit length ##\mu_2##. Derive $$1 = r^2...
  9. SamuuLau

    I The effect of temperature on the damping of a guitar string

    I am a high school student and recently I have been working on a project about how temperature affects the frequency of a string emits. I have read blogs like https://www.physicsforums.com/threads/tension-and-frequency-with-change-in-temperature.833185/ and completed the part of thermal...
  10. Conn_coord

    B Long String Theory: Unveiling the Universe's Secrets

    In theories of particle physics based on string theory, the characteristic length scale of strings is assumed to be on the order of the Planck length, or 10−35 meters. I am sure few people have heard about the long strings theory. If there is information on the topic big request to share it...
  11. gasgas

    Ring Impedance & String Connection: Is It Valid?

    If we consider the coefficient b as the rings impedance, we can consider the effective impedance on the right to be b+Z2 where Z2 is the impedance of the second string. Then because there is no reflection it follows that Z1=b+Z2 or b=Z1-Z2. Is this a valid solution? My professor went through a...
  12. B

    What is the minimum time at a given angle on a cone with constant size?

    I tried to come up with expression of time in terms of φ, α, and some constant value of cone size that does not depend on angle (I used R as cone radius). I though I could use that expression to see at what angle time is going to minimum, but I came up with expression from which I can't make a...
  13. C

    I Can we solve this Morin's problem without conservation of string?

    For this problem, The solutions are, However, how would we solve this without using the idea of conservation of string? Can we apply Newtons second law to each mass? My working is: Then apply Newton's Second Law to each pulley, (Line 1) (Line 2) (Line 3) (Line 4) Many thanks!
  14. W

    Python Is This String a Palindrome?

    Hi, I'm trying to write a program in Python 3 to determine whether a string is a palindrome. I wrote one already ; it runs, to reverse a string. I now want to use it to determine palindromes , by testing whether a string equals its reverse. To practice slicing as well, I want to write the...
  15. H

    Sign hanging from massless beam attached to hinge supported by string

    Attempted creating equations for zeros of torque and components of forces in x and y as seen in picture. Got lost with having only variables and the d & 2L for the length of the beam. Not sure how to do the question with two points of contact between the beam and the sign. Is the center center...
  16. Eugene Chen

    A How do we derive the number of string excitation modes for large N?

    On page 52 in Becker, Becker, Schwarz, there is an equation (2.148) for the number of open string excitation modes. I tried to Tayler expand eq 2.145, but couldn't reproduce 2.148. Plus, one gets 2.145 by setting w close to 1; even if I use the 2.146 and try to analyze it around 0, I am still...
  17. S

    Correct statement about transverse wave propagating along a string

    My answer is (1) only but my teacher said (3) is also correct. I don't understand why, I think when the wave is moving to the left both Q and R will be moving upwards, no? Thanks
  18. Drakkith

    Passing a Reference to a String in C#

    I'm using C# to program in Unity and I'm having some trouble with getting a tooltip box to update every frame. Simplified, Class A (and several other classes and instances of classes) has a string that stores the tooltip text and updates it every frame. Class B contains the logic to generate the...
  19. Lluis Olle

    I Some thoughts about Bell's string paradox alternatives

    Thinking about Bell's string paradox , I understand that if both spaceships maintain the same and constant proper acceleration, the string breaks because of the non-simultaneity of the acceleration effects at both ends of the string. But I want to introduce and consider a slight and subtle...
  20. S

    Find the probability that the shorter piece of a 20cm string is at least 8cm when the string is cut randomly

    I want to ask about part (c). This is what I did: the length of the shorter piece should be 8 ≤ X < 10 so P (8 ≤ X < 10) = 2 . (1/20) = 1/10 But my teacher said the correct answer is 2/10. Where is my mistake? Thanks
  21. A

    I The speed of a waves on a string in Simple harmonic motion

    The speed of a wave in simple harmonic motion on a string is $$v= \sqrt{\frac{F}{\mu}}$$ where v= the horizontal velocity of the wave on a string. Is the F the horizontal force or the resultant force (combination of Fy and Fx)?
  22. B

    I Filling in Missing Values in a string of data

    hello, I’m trying to figure out if I’m doing this correctly or if there’s a different way that I should be finding a missing value. I’m trending data for an automatic transformer. Every month I collect the operations counter value and at the end of the year sum the number of tap changes...
  23. M

    I Polynomials can be used to generate a finite string of primes....

    F(n)=##n^2 −n+41## generates primes for all n<41. Questions: (1) Are there polynomials that have longer lists? (2) Is such a list of polynomials finite (yes, no, unknown)? (3) Same questions for quadratic polynomials?
  24. A

    MATLAB No End" Boundary Conditions in Wave on a String

    How did they impose boundary conditions here if "no end" is selected? Here: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html I would like to do the same thing without changing the wave equation of the string.
  25. O

    Hamiltonian open string

    On ***page 38*** of Becker Becker Schwarz, we're given ***equation 2.69*** which is the Hamiltonian for a string given as $$H=\frac{T}{2}\int_{0}^{\pi}(\dot{X}^{2}+X^{'2})$$ Considering the open string we have...
  26. M

    Cylinder Falling from Unwinding String

    I need help with this homework question and I'm blanking out. Can anyone help me to answer this question correctly.
  27. MathematicalPhysicist

    Suggestions for future reading — Supergravity by Freedman or A First Course in String Theory by Zweibach?

    What do you recommend to read first, Supergravity by Freedman or A First Course in String Theory by Zweibach? For future consideration.
  28. alan123hk

    Roughly how many people in this world actually know about string theory?

    Roughly how many people in this world actually know about string theory? I'm guessing no more than a few hundred because the math of string theory is so esoteric.
  29. K

    I String theory calculation of Extremal black hole entropy problem

    one of the claimed successes of string theory is its ability to derive the correct Hawking-Bekenstein equations to calculate the quantum entropy of a black hole without any free paramenters, specifically Extremal black hole entropy using supersymmetry and maximal charge. I was wondering if...
  30. A

    I My textbook is deriving wave speed on a string under tension

    My textbook is deriving wave speed on a string under tension with confusing thetas. It assumes ##\tan \theta_1 = \frac{-F_1}{F_T}## and ##\tan \theta_2 = \frac{F_2}{F_T}## which confuses me. I know for sure theta is the angle due to the position of y and x, ##\tan \theta = \frac{y}{x}##, but I...
  31. A

    Tension in string pulling two carts

    F - T = m*a 820t - T = m*0.7805t T = 820t - m*0.7805t I am confused what I would use as mass? Mass of cart A, or mass of cart A and tractor?
  32. F

    Pulling down on the string connected to a whirling block on a table

    At the time of release, the equation of motion of blocks A and B T-m_ag = m_aa and T=m_b\omega^2R respectively, where T is the tension in the string. Solving for the acceleration a then gives a=\frac{m_b\omega^2R - m_ag}{m_a}. Not sure what I did wrong or what incorrect assumptions I made...
  33. M

    A Percentage of String Theory Research in Theoretical Physics

    What percentage of current new research in theoretical physics is focused on string theory/M-theory/supersymmetry? Are most PhD students or tenure track researchers still working in that space or are other ideas becoming more fashionable? I assume it must be less than 10 or 20 years ago, but...
  34. Adgorn

    Morin's mechanics problem 2.3 (motionless chain)

    In his solution, Morin solves the problem as the hint suggests: cutting the chain into small pieces, taking the component of the external forces along the curve (which is just the component of gravity here) and summing up an in integral, obtaining 0. He then claims that because the "total...
  35. Al-Layth

    Circular Motion Problem -- Ball on a String Spinning in a Vertical Circle

    #F= m\frac{v^2}{r} = mw^{2}r# #m=5# #r=0.9# #F= 5\frac{v^2}{0.9} = (0.9)5w^{2}# #5\frac{v^2}{0.9} = (0.9)5w^{2}# #\frac{v^2}{0.9} = (0.9)w^{2}# #v=0.9w# then I get stuck cause I have both unknowns in one equations (i bet it has something to do with the question’s use of “minimum” but I...
  36. S

    Finding the frequency of a string based on Mass and Tension

    I saw the following problem in a test I was reviewing: I don't understand how they got their answer. I used the formula: ƒ=sqrt(T / u) / 2L where f is the frequency of the string, T is the tension, u is the linear mass density, and L is the length of the string. I got: T = mg = 50 * 9.8 = 490N...
  37. E

    Effect of temperature on vibrational frequency of a violin string

    Variables: Dependent: Vibrational frequency of violin string (Measured using mobile tuning app) Independent: Temperature in which string is plucked (Measured using infrared thermometer) Controlled: Violin String, Tension of violin string, Length of violin string, Method of plucking...
  38. A

    A Loop Quantum gravity or String theory?

    I understand that string theory has almost no testable predictions, however loop quantum gravity is an enticing candidate for only quantum gravity and it doesn't explain much of symmetry, constants, mixing angles etc in Standard model. There is obviously not enough evidence to create a full...
  39. M

    Guitar string tension: effect of total length - continued

    This wiki page offers an incomplete equation for calculating tension over a length of string. Can you please help complete the equation? https://en.wikipedia.org/wiki/String_bending It is referenced here in this thread post #23...
  40. MathematicalPhysicist

    A What possible experiments will falsify String Theory?

    Or will confirm its predictions? As far as I can tell, you can only raise the bar on the energies required from the accelerator, but you cannot give an upper bound, where beyond it the theory is doomed... This isn't science... we might as well say we need infinite energies. 🙃
  41. R

    I am calculating the forces on String cheese with net force = 0

    Here is the link to the question. https://www.khanacademy.org/science/physics/forces-Newtons-laws/Newtons-laws-of-motion/a/what-is-Newtons-second-law What is the magnitude of the force F1 ? What is the magnitude of the force F2 ? Here is my drawing I made At this step I am lost. ## ay...
  42. D

    How replace a numeral in the string 'abc1def' w/ an array element?

    Summary:: I need to loop through a number of strings replacing the numerals in them with an array element so that e.g.: flos1Field, flos2Field, flos3Field, etc. become flosAField, flosBField, flosCField. The array would be something like: const letters = ["A", "B", "C"]; I put the question in...
  43. StenEdeback

    Question about string theory

    I am doing private studies in string theory and am reading "A first course in string theory" by Barton Zwiebach. Below equation 6.52 the author says "Since the second term on the right-hand side must vanish...". I do not understand why this term must vanish, and I would be grateful for an...
  44. shivajikobardan

    How to check whether a string is odd palindrome in python?

    I am learning to code and 1 thing that surprises me is how do I internalize all the code? I understand the code. I know the algorithm as well. But I want to be able to solve any types of problems(related ones) after learning 1 code. How do I become able to do that? So for that I am first trying...
  45. shivajikobardan

    How to check a string is odd palindrome in python?

    I am learning to code and 1 thing that surprises me is how do I internalize all the code? I understand the code. I know the algorithm as well. But I want to be able to solve any types of problems(related ones) after learning 1 code. How do I become able to do that? So for that I am first trying...
  46. P

    Vertical spring connected between two bodies with a rope above them

    Question: A string spring is connected between two bodys with a rope above them. M1 = 25Kg M2 = 50KG Distance between them is 100m. I answered a bit and got to the point where the distance between the two masses are 110m ( the mass below got 10m lower and is on balance, I mean, acceleration = 0...
  47. vibha_ganji

    Another Doubt From Halliday Resnick Krane -- Puck on a string in circular motion

    Hello! This is a problem from Halliday Resnick Krane (Chapter 4: Problem #15). “A puck is moving in a circle of radius r0 with a constant speed v0 on a level frictionless table. A string is attached to the puck, which holds it in the circle; the string passes through a frictionless hole and is...
  48. C

    Comp Sci Validating Braces Placement for Expression Evaluation

    Here's what I've done: Mentor note: replaced icode tags with code=python and \code pair. def valid_braces_placement(s, L): if len(L)==0: return False string = '' for element in L: string = string + str(element) D = ['+','-','*'] return...
  49. G

    To find the modulus of elasticity of a light elastic string

    Could I please ask for help with the following question? Four uniform rods of equal length l and weight w are freely jointed to form a framework ABCD. The joints A and C are connected by a light elastic string of natural length a. The framework is freely suspended from A and takes up the shape...