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. soothsayer

    Coexistence of LQG and String Theory?

    Can Loop Quantum Gravity and String Theory coexist? What if String theory was correct in its description of matter and 3 of the 4 forces, with the only difference from modern M theory being that there is simply no real particle called the graviton, and instead, gravity is as is described by LQG...
  2. M

    Higgs Boson, String Theory and Gravity

    Hi everybody, let's assume the Higg's boson exists. If I understand String theory correctly (and I understand very little of it), then Higg's particle - just as any other particle - can be expressed as a particular vibration state of a string. If I understand Higg's theory correctly, then...
  3. marcus

    What Are the Current Trends in String Theory Research?

    Each year, the annual String conference provides us with a kind of snapshot of the field as it is today. The lineup of invited speakers and the titles of their talks give an idea of the current activity and interests of string researchers. This year Strings 2012 is in Munich and starts on...
  4. stripes

    VERY simple: String index out of bounds exception

    Homework Statement I am making a very, very simple program that takes in the date (of type string) from the user in the form DD/MM/YYYY. It then confirms whether or not the date is legitimate or not. For example, 09/07/2012 is valid, but 09/17/2012 is not valid. My program compiles...
  5. T

    The dimensions of elementary particles in quantum physics and string theory

    I noticed that in quantum physics, an elementary particle has no dimensions, and is point like, but in string theory has one dimension. Why is this?
  6. C

    Does the discovery of the Higgs Boson disprove String Theory?

    From what I understand, the Higgs Boson was the last missing piece of the Standard Model (12 indivisible particles, 4 forces). Now that the Standard Model is complete, has String Theory been disproved? Is there a conflict between the Standard Model and String Theory?
  7. P

    Which string cutten? (impulse)

    suppose a metal ball is hanging by a string and there is another string is hanging at buttom of the ball if you pull buttom string very fast which of strings (up and buttom) will be cutten ?
  8. Spinnor

    Adding or removing energy from a guitar string.

    Say we have a guitar with electrical pickups near each end of one string. Say this guitar string is ideal in that it looses no energy to any form of "friction". Say the electrical pickups can act to both remove and add energy to the guitar string in the two dimensions perpendicular to the...
  9. I

    Close tube with string oscillation

    Homework Statement In attached figure, a closed tube is placed near a string that is fixed at one end and has a weight attached to its other end. When bridges A and B are positioned at the points shown,plucking the string between A and B causes the tube to resonate at its fundamental...
  10. C

    Explaning gravitation via string theory

    This may be a silly question since i am relatively new to the string theory. While going through a quantization of the bosonic string , I see a tower of states appearing corresponding to different modes of excitations of the bosonic string. Now I was trying to figure out how this whole machine...
  11. R

    The Wave Equation (vibrating string)

    Homework Statement The differential equation describing the motion of a stretched string can be written \frac{\partial ^2 y}{\partial x^2} = \frac{\mu}{T} \frac{\partial^2 y}{\partial t^2} μ is the the mass per unit length, and T is the tension. (i) Write down the most general solution you...
  12. X

    Length of string by wave length

    The 3rd harmonic on a piano string occurs when a 45.0 cm wave is produced. How long is the string. This question is really confusing can i get some leads to help me out please and thank u
  13. R

    What is the Tension in a Rotating String?

    Homework Statement A body of mass 1.00kg is tied to a string and rotates on a horizontal, frictionless table. If the length of the string is 40cm and the speed of revolution is 2.0m/s, find the tension of the string. Homework Equations a = v^2 / r f = ma v = 2∏rf Thanks :)
  14. Demystifier

    String theory in arbitrary number of dimensions

    A long time ago, physicists thought that only a small class of quantum field theories (QFT's) makes physical sense - those which are renormalizable. But then gradually it became accepted (Weinberg was the most influential figure in that regard) that QFT does not really need to be renormalizable...
  15. L

    String Theory - Determinate or Indeterminate?

    A fundamental difference between classical and quantum mechanics is that the former is deterministic; the latter, probabilistic. I'm wondering where string theory fits into this picture? Is the landscape described by string theory determinate or indeterminate? Along the same lines, classical...
  16. R

    Does String Theory explain unexplained phenomina?

    I like to think myself as adequately familiar with the concept of String Theory and it's basic fundamentals, But I'm wondering if string theory offers explanations to the currently unexplained such as universal expansion, quantum Entangelment, radio active decay, why virtual exist, etc? Or does...
  17. A

    Solve the Equilibrium of a Light Elastic String with Mass m

    Homework Statement Hi Can anyone please help with this question? A light elastic string AB has natural length l and modulus of elasticity 2mg. Another light elastic string CD has natural length l and modulus of elasticity 4mg. The strings are joined at their ends B and C and the end A...
  18. A

    Tension in a string simple pendulum

    Homework Statement Hi Guys I obtained a slighty different answer. Can anyone kindly verify where I am going wrong? The question is stated thus: A simple pendulum is of length 0.5m and the bob has mass 0.25kg. Find the greatest value for the tension in the string when the pendulum is set...
  19. S

    If String Theory explains/ leads to gravity, how does it not make predictions?

    If String Theory explains/"leads to gravity, how does it not make predictions? String Theory "predicts" gravity. It can explain gravity and it explains "small" structures. If String Theory includes these two topics shouldn't it predict what happens when Quantum Gravity becomes non-negligible...
  20. P

    Frequency of a standing wave on a string

    Homework Statement a 50m length of string with mass 0.0175 kg has waves traveling at 112 m/s. There is a mass attached to the string, 0.45 kg that is creating a 4.41 N tension. What is the frequency of the string vibrator? Homework Equations v=f*λ f= [√T/(m/L)]/2L The Attempt at a...
  21. Z

    [BASH] Possible to echo only certain range of WORDS in a string?

    Hi, I'm new to Bash scripting and I need some help with this: I need to echo only a specified range of words from a string based on index; so for example if I had: a="hello how are you today" Is there a way to echo only "how are you" by specifying the index 2 to 4? (in one line...
  22. C

    Wave motion finding number of nodes in string.

    Homework Statement An aluminium wire of length L1=60 cm and of cross sectional area 1.00×10-2cm2 is connected to a steel wire of the same cross sectional area. The compound wire; loaded with a block of mass m=10kg is arranged so it is hanging freely from a suspended pulley so that the...
  23. M

    Maths for Postgraduate String Theory: Analysis, Algebra, or Topology?

    I admit I don't know anything about string theory (nobody really does at an undergraduate level) but it sounds interesting and seems like something challenging. I am majoring in physics and maths but I am getting to the point in my undergraduate studies where I can begin to specialize more in my...
  24. T

    Elastic String Displacement u(x,t)

    Homework Statement Consider an elastic string of length L whose ends are held fixed. The string is set in motion with no initial velocity from an initial position u(x, 0) = f (x). Assume that the parameter alpha = 1. Find the displacement u(x,t) for the given initial position f(x) The Attempt...
  25. B

    QCD string tension at strong coupling: log(g^2) vs. g^2

    Hi everyone, I am trying to understand some things about confinement in lattice QCD. It has been very difficult so far to find a clear book chapter or review article, so I had to resort to the original literature in many cases, and I came across some apparently incompatible statements about...
  26. P

    Vibrating String: Interpreting ∂u/∂x(L,t)=0 Boundary Condition

    Homework Statement (∂^2 u)/(∂t^2 )=a^2 (∂^2 u)/(∂x^2 ) x∈(0,l) t>0 u(0,t)=0 ; ∂u/∂x(L,t)=0 u(x,o)=u1; ∂u/∂t(x,o)=x I can not figure out physical interpretation of boundary condition ∂u/∂x(L,t)=0, what does it mean. Can someone can help me with this ? Homework Equations The...
  27. C

    Standing waves on a string.

    Homework Statement During the experiment you will be collecting data similar to that in the table below. The experimental set up is the same as that described in your lab manual. Complete this table. Assume that the frequency is 50 Hz, and is known accurately. this is the data given. 1...
  28. J

    Need help calculating the tension in the string of two boxes with friction

    Homework Statement Two boxes are connected by a cord running over a pulley. Box A sits on a table and has a mass of 5.0 kg while box B hangs freely and has a mass of 2.0 kg. Box A moves to the right and box B moves downwards. If the coefficient of kinetic friction between box A and the table...
  29. S

    Ball Spinning Horizontally on String

    Homework Statement There is a ball spinning on a string in a circle in a horizontal plane in a gravitational field. What is the rotational frequency w in terms of the angle of the string to the normal line of the plane of motion, the length of the string, m, and g? The original homework was...
  30. O

    String Theory & Particle-Wave Duality: Can Oscillating Strings Explain?

    I'm not sure if this question is something that has been asked before or if i thought about it myself or if it's completely ridiculous! But I was thinking, if, according to String Theory, particles are 1-dimensional strings that go through modes of oscillation, could they describe how a...
  31. H

    Lab Prep - Speed of a wave on a stretched string

    Homework Statement 1) Show that the expression for the mass per unit length, μ, of a wire in terms of its density and diameter is μ = \frac{πρd^2}{4} 2) Using equations (3) and (4) show that the expression for the error in frequency in terms of the error in length and the error in diameter...
  32. A

    Pendulum with non-rigid string

    Hello guys, this is my first post so if I have something done wrong, please tell me. :P When we come across with pendula, they are all with rigid rod, whether with mass or not. I wonder if the pendulum has a non-rigid string which can estimate the motion of string when the pendulum rises...
  33. S

    Papers to prove and disprove string theory/ M Theory?

    Hello, My name is Holly... I'm new here... so i have no idea weather I put this in the right section! D: ... Sorry if so :3 Basically, I have been put to the task of writing a paper on String Theory and weather or weather not String Theory/ M-Theory (i can do either one, will do the...
  34. D

    Tension in a string (Kleppner 2.23)

    Homework Statement A piece of string of length I and mass M is fastened into a circular loop and set spinning about the center of a circle with uniform angular velocity ω. Find the tension in the string. Suggestion: Draw a force diagram for a small piece of the loop subtending a small angle Δθ...
  35. C

    Quantum Master Equation in String Theory

    Can anyone give me a general sense of what the quantum master equation (or BV master equation) is and how it relates to string theory? I'm an undergraduate physics student and am hoping to do research with a professor on the topic, but need some basic knowledge on the subject.
  36. E

    Sound Waves Traveling Down a String

    Homework Statement A brother and sister try to communicate with a string tied between two tin cans. If the string is 9.5m long, has a mass of 55g and is pulled taut with tension 6N, how much time does it take for a wave to travel from one end of the string to the other? Homework Equations...
  37. E

    Speed of Waves traveling on a taut string

    Homework Statement If the string is mass 9.5 m long, has a mass of 55g and is pulled taut with a tension of 6N, how much time does it take for a wave to travel from one end of the string to the other? Homework Equations v=√(T/M) M=mass/length The Attempt at a Solution First I...
  38. C

    Is it possible to combine string theory and LQG?

    Good evening. I am wondering if string theory and loop quantum gravity could be combined into a single theory. I have been trying to decide which of the two I should choose as my "religion," but I feel that both are correct. Could string theory and loop quantum gravity be different...
  39. R

    Is string theory just a new math?

    I have read in a couple different places that the math that comes out of string theory has helped a couple of different other branches of physics like quantum computing and condensed matter physics. Quote from: http://www.ams.org/news/math-in-the-media/11-2011-media "Maybe string theory is...
  40. K

    How to reduce the force exerted by a guitar string to a Vernier sensor?

    I am doing a project, where I am measuring the tension exerted by different guitar strings from different sets for the classical guitar. I have a Vernier dual force sensor to do it, so the method would be just attaching one end of the guitar string to the Vernier sensor, while the other end...
  41. M

    Tension in string of objects connected question :o

    Homework Statement In the attachment! This is a multiple choice question where you have to choose one of the strings. Intuitively I chose Z as I would think that in the first fraction of time it would feel the force acting on it first. However, if this wasn't a multiple choice I...
  42. Whovian

    C/C++ File Input & Output in C++: Why Use a String Literal?

    I felt like learning a bit about file input and output in C++. Tried some code, couldn't get it to work unless I made the path to the file a string literal, not a variable type. Why is this, and is there any way to get a string data type to be inputted as a path?
  43. I

    Mathematics Topics in String Theory

    Hello all, I am currently a Junior in High School with a deep interest in Physics/Mathematics, specifically in the area of theoretical Physics and String Theory. I was accepted to a summer course on String Theory and am quite excited. The course stated that the only prerequisite is Single...
  44. I

    Length of string on instrument to produce specific frequency

    Homework Statement You are designing a two-string instrument with metal string 35.0 long, as shown in the figure . Both strings are under the same tension. String has a mass of 8.45 and produces the note middle C (frequency 262 ) in its fundamental mode. To extend the range of your...
  45. O

    Segmentation fault reading string on cin read

    Homework Statement I'm trying to read a string from cin. When it hits the "cin >> strWord" statement, I get the following error message: Segementation fault (core dumped). The input file is named "data4nine". I'm really not sure what a segmentation fault is and why I'm getting it The...
  46. B

    Statics: a hinge held up by a string with a mass

    Homework Statement A uniform beam of mass M and length L is mounted on a hinge at a wall as shown in the figure. It is held in a horizontal position by a wire making an angle (theta) as shown. A mass m is placed on the beam a distance from the wall, and this distance can be varied...
  47. B

    Beat frequency: which equation to use to find the mass of string 2

    Homework Statement Two strings of equal length, L, are each clamped at both ends and are under the same tension T. String 1 has a mass of 45.00 g and vibrates at a frequency of 512 Hz. String 2 is slightly heavier. When the two strings are plucked at the same time, beats with a frequency...
  48. K

    Phase change from mass in middle of a string

    Homework Statement There is a mass M in the middle of an infinite string, of the same linear density on both sides. The reflection coefficient is r=-ip/(1+ip) where p=ω^2 M/2Tk How does the phase change on reflection vary with M, for fixed ω and T? Homework Equations Phase change...
  49. 9

    Wave on a string meeting a boundary between areas of different densities

    This is the problem I'm working on: http://i.imgur.com/PBMFG.png I'm very behind with normal modes and waves, and I need to figure out how to do this sort of question in time for my exams, so I'm hoping that you guys will be able to help me see how this can be answered. I've answered the...
  50. D

    Net Force on a Spinning Ball Attached to a String Question

    Hi all, I have a conceptual question about the net force of a rotating or spinning ball attached to a string. If we have a situation such as a tether-ball game where the ball is being swung around a string at an angle to the vertical, is the net force the tension in the string, or the...
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