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. U

    Force on a Pulley: Understanding Tension and Tangents

    Homework Statement I'm having trouble understanding an example given in K&K's Intro to Mechanics textbook. 'A string with tension ##T## is deflected through an angle ##\theta_0## by a smooth fixed pulley. What is the force on the pulley'. I don't understand how (in the first picture) they...
  2. Spinnor

    B Photon, string theory string, E&M field

    Is it possible to associate electric and magnetic fields with the vibrating string that is thought to represent a photon in string theory? Thanks!
  3. R

    Tension in string when ball is at the top of a circle

    Homework Statement A child is swinging a .325 kg ball at the end of a .74 m long string in a vertical circle. string can withstand a tension of 12 N before breaking. What is the tension in the string when the ball is at the top of the circle if its speed at that point is 3.4 m/s? Homework...
  4. binbagsss

    A Intro to String Theory: Lightcone Gauge & Oscillators

    Lightcone gauge is ##X^u=\tau=1/\sqrt{2}(X^0+X^{D-1})## (1) The mode expansions are: My book says 'it is possible to solve for one of the oscillators in terms of all the others' with this relation. What is a oscillator? Is this any of the ##X^{D}## coordinates, what exactly does ##n##...
  5. Viet Tu

    B What is status of String Theory now?

    Are there anything new in String theory?
  6. EthanVandals

    Centripetal Force and Work: Understanding the Relationship

    Homework Statement A 5kg ball is swung in a circle of radius .5 meters at a constant speed of 2 meters per second, how much work does the centripetal force do as the ball does once in a circle?If the ball were pushed the same distance as the circumference of the circle with a force equivalent...
  7. L

    How Do You Calculate Phase Difference and Equilibrium Timing in Harmonic Waves?

    Homework Statement the velocity of a harmonic wave in a strung-wire is 1550m/s and the wave's frequency is 740Hz there are two oscillators (?) in the wave called A and B such that B is 2m further ahead of A in the direction of the wave's travela) calculate the phase difference between A and B...
  8. S

    Motion of two objects connected by a string

    Homework Statement As shown in Figure 1, two objects A and B of the same mass m are moving on a horizontal plane without friction along x axis. The two objects are connected by a string of length l. The mass of the string is negligible, and the length is constant. At time t = 0, A is to the...
  9. R

    Finding wavelength and fundamental frequency with string

    The length of a string is 1328 cm. It is held fixed at each end. The string vibrates in eight sections; i.e., the string has eight antinodes, and the string vibrates at 97 Hz. Find the wavelength and fundamental frequency. I have no clue, anything helps! Thank you!
  10. E

    Perfect Inelastic collision with string tension

    Homework Statement A small wooden block with mass 0.800 kg is suspended from the lower end of a light cord that is 1.60 m long. The block is initially at rest. A bullet with mass 0.0132 kg is fired at the block with a horizontal velocity v-_i. The bullet strikes the block and becomes embedded...
  11. H

    Force diagram of a spinning mass tied to a string

    Homework Statement In an effort to rev up his class, Mr. H does a demonstration with a bucket of water tied to a 1.3-meter long string. The bucket and water have a mass of 1.8 kg. Mr. H whirls the bucket in a vertical circle such that it has a speed of 3.9 m/s at the top of the loop and 6.4 m/s...
  12. Anatalbo

    Sliding blocks and a string problem

    Homework Statement Block A, with weight 3w, slides down an inclined plane S of slope angle 36.9 degrees at a constant speed while plank B, with weight w, rests on top of A and is attached by a cord to the wall. If the coefficient of kinetic friction is the same between A and B and between S...
  13. T

    Fortran Repeating Strings in Fortran: Why is My Output Not Matching My Key?

    Hi, guys. For my project this week I have to code a cipher, and I am just getting used to what, what with the code. The problem I am having is that I have assinged my key and instered that into the repeat function but I only get one output of maths and not seven, why is this? program Jason...
  14. T

    Sound & Music, String Frequency

    Homework Statement Suppose a string is 0.50 m long, it has a mass per unit length of 1.2 g/m, and it is under a tension of 52 N. What is the frequency of the second mode of this string? Express your answer in the SI unit for frequency? Homework Equations f = Vs/2L Vs = sqrt (F/μ) The Attempt...
  15. FritoTaco

    How can I display string arrays in a JApplet without using integers?

    I don't know how to display what the string you see in the array. Do I need to put something in the paint method? It's annoying because my book and everywhere I look only show examples using integers and not strings. This code is in the init method. I can't find out where to display the "dog"...
  16. K

    Analysis of tennis string tension

    I have a decent background in physics, but something that has always confused me is how to think about how the tension of the string in a tennis racquet affects how the ball leaves the strings. For example, the traditional lore in tennis is that tauter strings will give more control, whereas...
  17. N

    I Non linear interpretations of QM and string theory?

    Are interpretations that are non linear with respect to the wave function (eg. GRW, transactional) compatible with string theory?
  18. T

    Sound of vibrating string - modes

    Homework Statement Suppose we listen to the sound of a vibrating string with a pickup that is sensitive to the motion at a point 1/3 of the string's length from one end. Which statement is true? A.) We will be able to hear all of the modes except the third B.) We will not be able to hear the...
  19. kolleamm

    Storing a string in a created obj type

    Homework Statement How can I store String s in X x_obj [] = new X [100] ;2. What I tried I tried x_obj [0] = s; But it didn't work. I know there are easier ways but this is how I have to do it. Thanks in advance
  20. john101

    The Mysterious Phenomenon of Knotting a String Around a Rod

    Hi. I've been searching for some description of the following. Something that will explain it and perhaps even some maths about it. Take a rod or a stick and tie a string around its middle. Hang it so the string is unwound, still. Start turning the rod so the string twists around. Keep...
  21. E

    Dynamics question related to conservation of string

    Homework Statement http://tinypic.com/r/10f5ni8/9 http://[PLAIN]http://i66.tinypic.com/10f5ni8.png Homework Equations I have a problem understanding this problem. It asks for the velocity of block A when block B is moved 300mm/s to the right. The equation for the cord length is given as...
  22. Arman777

    What is the impulse on the ball from the string?

    Homework Statement A ball of mass 1.00Kg is attached to a loose string fixed to a ceiling.The ball is released from the rest and falls 2.00m,where the string suddenly stops it.Find the impulse on it from the string. Homework Equations .[/B] Kinematic equations...
  23. Mary curie

    B Is String Theory Real? | Get the Answer

    Hello everybody! I hope you are having a great day ! My question: is the strings theory a REAL theory ... is it really the final answer to the relationship between relativity and quantum mechanics! ? [emoji54]
  24. N

    MHB Calculate Strings with int calculate(string exp) Function

    If input is 2: call int calculate(string exp) function. This function will return the computation of a string expression (exp). For example: calculate(“54321+222”) will return 54543 calculate(“120*20”) will return 2400 calculate(“235/3”) will return 78 calculate(“356-32”) will return 324My code...
  25. U

    Constant string length question with pulleys

    Homework Statement Given Ma = Mb =Mc and muk between c and the surface is 0.30 Homework Equations (rope length) = constant Maaa = Mag - T Mbab = Mbg - 2T Mcac = T - (mu)Mcg The Attempt at a Solution The equations I came up on my own and the answer key did as well. The problem is I also need...
  26. J

    Help understanding a vibrating string question

    Homework Statement So I don't really understand what the professor means by "show why the displacements y(x,t) should satisfy this boundary value problem" in problem 1. Doesn't that basically boil down to deriving the wave equation? At least in problem 2 he says what he wants us to show...
  27. F

    I How do we excite specific standing waves on a string?

    Hello, I am aware that there are specific oscillatory patterns than can form on on a string. These patterns are called normal modes and represent standing waves. Each standing wave has an associated frequency f which indicates the speed at which the string's points are moving up and down...
  28. Chip

    A Unifying String Theory and SuSy

    It seems that the latest data out of CERN suggest a mass of the Higgs Boson that is smack in the middle of what would be suggested by parallel universes/string theory and SuSy. Do you think Edward Whitten, Savas Dimopoulos, and probably others could get together in a room to unify these two...
  29. F

    Circular motion: ring on string

    Homework Statement Homework Equations F = mw^2r [/B]The Attempt at a Solution For part a, I can't get the constant of half with the tan a I am getting tan a = w^2l/g
  30. N

    I Does the length of a string depend on it's energy?

    Does the length of a string depend on its energy, or does its energy depend on its length? Similarly, does the area of a d brane depend on its energy, or does its energy depend on its energy? Are these stupid questions?
  31. haushofer

    A Problems with quantizing branes in string theory

    Dear all, recently I'm reading up some string/M-theory, especially the role of branes, because I'm writing a popular science book in Dutch. Every textbook states the issues one encounters when you try to quantize p-branes for p>1, as is discussed e.g. here...
  32. K

    I Can string theory reproduce Hawking radiation in non-extremel black holes in 4D?

    can string theory reproduce hawking radiation in non-extremel black holes in 4D? i.e physically realistic black holes. do they exactly match hawking's calculations? what is the interpretation of hawking radiation in string theory?
  33. RavenBlackwolf

    Transverse Wave on a String

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > A transverse wave on a string has an amplitude of 16cm, a wavenumber of 5.7m-1, and a frequency of 39Hz. What is the propagation speed of that wave? (a) 6.84 m/s (b) 39.2 m/s (c) 43 m/s (d) 6.24...
  34. ChloeYip

    How Does Wavelength Influence the Power of a Wave on a String?

    Homework Statement http://i.imgur.com/sWZS9vQ.png Homework Equations P=½ √μF ω2 A2 The Attempt at a Solution How is the equation related to the wavelength? Thanks
  35. S

    What is the tension in the lift cable and in the string?

    1. Part One: A mass M1 = 30 kg is suspended by a light string from the ceiling of a lift of mass M2 = 300kg. If the lift accelerates upwards at 1 m/s2, what is the tension in the lift cable and in the string? (g=9.8 m/s) Part Two: If the string breaks when subjected to a tension of more than...
  36. L

    How is tension in a string affected by moment of inertia?

    Homework Statement I'm in need of a more conceptual answer, rather than numerical. Say you have a block on a horizontal frictionless table (block 1). Then you have a string tied to block one and strung over a pulley that is at the right end of the table (the pulley has mass). On the other...
  37. V

    What is the binding force for a falling disk with string?

    Homework Statement Let's have a disk of mass ##m## and radius ##a## and massless rope tangled in it. One end of rope is tied to the ceiling and the disk is falling freely down. System has one degree of freedom. As a coordinate we can choose angle ## \phi## which says an angle of rotation from...
  38. Kevin McHugh

    I Unraveling the Mysteries of Leptons in String Theory

    Could someone explain or point me in the right direction on how string theory explains the leptons? TIA, Kevin
  39. G

    Finding maximum height of a string before it goes slack

    Homework Statement A mass m is suspended by a light elastic string. When the mass remains at rest it is at a point 0, which is a distance a + b below the point from which the string is suspended from the ceiling, where a is the natural length of the string. The mass is pulled down a distance h...
  40. Efast

    What is the speed of a wave on the string?

    Homework Statement The tension in the string is 90N; the string is 60cm long and has a weight of 34.44g. What is the speed of the wave on the string? Answer: 396 m/s Homework Equations v = √ T / (m/L) The Attempt at a Solution v = √ 90N / (0.0344kg/0.6m) v = 39.6 m/s Huh? This looks like it...
  41. Julie1703

    B The dimension of time in String Theory

    I was doing some reading on String Theory...I'm not a scientist, but i enjoy it (so forgive me if my question is stupid) and i was wondering: Being time a dimension, could it be the dimension the strings exist in? And interaction between all particles and all forces determine how they vibrate...
  42. B

    Wave speed for non-uniform density?

    Homework Statement A long rope with mass m = 10 kg is suspended from the ceiling and hangs vertically. A wave pulse is produced at the lower end of the rope and the pulse travels up the rope. (a) Explain why the speed of the wave pulse change as it moves up the rope; does it increase or...
  43. Revengeance

    Centripetal force ball on a string lab

    Homework Statement So referring to this lab , http://static3.mbtfiles.co.uk/media/docs/newdocs/international_baccalaureate/physics/824297/html/images/image12.pngIn this lab you are holding the plastic tube and twirling it to make the small mass spin in a circle. Keep in mind there is a mass on...
  44. J

    String Theory and Theoretical vs. Mathematical Physics

    Hello, I have a question about the the difference between mathematical physics and theoretical physics in general and about the difference between the MSc Theoretical and Mathematical Physics courses at Edinburgh in particular. I am planning to apply, however I am not sure which of the two...
  45. Elvis 123456789

    Lagrangian of two masses connected by string on inclined pln

    Two masses, m1 and m2, are attached by a light string of length D. Mass m1 starts at rest on an inclined plane and mass m2 hangs as shown. The pulley is frictionless but has a moment of inertia I and radius R. Find the Lagrangian of the system and determine the acceleration of the masses using...
  46. S

    I Macroscopic versus microscopic standing waves

    I have read the description of electrons as standing waves based on an analogy with a string vibrating at its natural frequencies: thus the different quantum levels are akin to the tones or harmonics of the string, right? So far, so good, but then I have seen contradictory complementary views...
  47. Mr Davis 97

    Counting number of consecutive elt's in nit string

    Homework Statement How many strings of length 10 contain either five consecutive 0s or five consecutive 1s? Homework EquationsThe Attempt at a Solution So this problem isn't too bad, and I have a pretty good idea of how to solve it. However, I am not sure whether the problem is referring to...
  48. Hughng

    Comp Sci Unmash a string in C++ using recursion

    Homework Statement MUST USE RECURSION TO SOLVE THESE PARTS. Part A: Have a user input a string. Then display this string smashed up as follows: display the first character in the string, then the last, then the second, then the second to last, then the third... So if the string is “abcdef”, it...
  49. ShayanJ

    A Exploring the Dual Low Energy Limits of Superstring Theory

    Let's consider superstring theory on a 10 dimensional Minkowski background. And assume there is a D3-brane on which the open strings end and closed strings wander around freely in the background. I want to know, in what limit this gives a supergravity theory in which I can study it by using the...
  50. wolram

    B Is supersymmetry a part of string theory

    Is supersymmetry part of string theory or does it have a place in the standard model
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