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.

View More On Wikipedia.org
Recent contents Top users
  1. W

    [SQL] Rule of Thumb for Queries: Length of String vs Speed?

    Hi all, Just curious as to whether it is a good rule of thumb ( though not an actual rule) that out of two effective queries (i.e., two queries q1, q2 that return the desired result) , the query that is shortest as a string, i.e., has the fewest total words, will run faster? I understand the...
  2. M

    Can you determine if a string of particle pairs is composed of entangled pairs?

    I've gotten interested in this question since the recent loophole free bell test performed at Delft University (group of Ronald Hanson). In this test they use entanglement swapping which I hadn't heard about before. After some research I even found out that there is such a thing as delayed...
  3. moenste

    Fundamental frequency if string halved and tension * 4

    Homework Statement The fundamental frequency of vibration of a particular string is f. What would the fundamental frequency be if the length of the string were to be halved and the tension in it were to be increased by a factor of 4? Answer: 4 f 2. The attempt at a solution We have f = f1...
  4. ChickenTarm

    How do I find the normal modes of massless string w/ masses?

    Homework Statement So, a string with length L and a mass of M is given tension T. Find the frequencies of the smallest three modes of transverse motion. Then compare with a massless string with the same tension and length, but there are 3 masses of M/3 equally spaced. So this is problem #1...
  5. P

    What is the current status of susy and string theory?

    I heard that the LHC was supposed to do some testing on supersymmetry but i didn't hear anything from them and is string theory still possible or not.
  6. G

    String theory & Quantum Mechanics

    Did string theory come about as a possible solution to quantum mechanic's "something being in several places at the same time" paradox so to speak? I am not a math-guy or pretend to know anything about physics. I m just curious. I was thinking that what appears as something being in multiple...
  7. M

    Are nodes on a string perfect nulls?

    Maybe I'm thinking about this incorrectly, but I would assume that the wave loses energy after bouncing back and before hitting the wave moving in the opposite direction. Wouldn't this prevent a perfect null (if the amplitudes were different)?
  8. I

    MATLAB Matlab Switch w/ string function

    hey hey :) So this is the code i came up with %% part 2 x=[1 2 3 4 5]; % 1 is freshman % 2 is softmore % 3 is junior % 4 is senior % >4 is super senior for i=1:5 s=input('number: '); switch s case 1 yearNumber='freshman'; case 2...
  9. TheMathNoob

    TokenCounter of a string displaying not desirable results

    Homework Statement I am currently coding a program which reads a file and makes a graph based on the arrangement of the data in the file. The first line of the file stands for the number of vertices and the rest of the lines stand for the edges something like this: 3 1 2 2 3 3 4 In the first...
  10. bcrowell

    What is the interpretation of a Misner string in Bonnor's theory?

    I came across the term "Misner string" in this paper: http://arxiv.org/abs/1509.07854 My understanding is that this originated in the study of spacetimes such as Taub-NUT. If I'm understanding correctly, this involves CTCs encircling the string. Misner's original interpretation of the string...
  11. Enne

    How competitive is string theory compared to other fields?

    I'm Indian and I've heard stuff that it is difficult to get into a good PhD program in the US/UK for string theory because the competition is more fierce than other fields. Furthermore,the likelihood for getting academic positions is even tougher(added to the fact that I'm from a different...
  12. thorq

    Parallel string walking between two threaded cylinders?

    Hello, I have a problem that seems to have beaten me. I want to make a cable-driven reduction system between a threaded rod (pinion) and a larger threaded cylinder. Because of string walking, the string between the two has to stay at all times straight, parallel to the ground so that...
  13. S

    Two blocks connected by a string

    Two 2.4-kg blocks are connected by a string draped over the edge of a slippery table, so that one block is on the table and the other is just hanging off the edge. A restraint holds the block on the table in place, and the string is 0.50 m long. After the restraint is removed, what speed does...
  14. G

    Finding tension in string in vertical circle

    Homework Statement [/B] Your niece finds her father's watch. The light watch chain has a length of 48 cm, and the mass of the watch is 270 g. Your niece swings the watch in a vertical circle, maintaining the speed of the watch at 2.3 m/s. Find the tension in the chain when it makes an angle of...
  15. Remixex

    Question about mg on oscilations course

    On a test our teacher asked about a system composed of (string -> mass -> string -> mass) hanging, that began to oscillate up and down. We all considered weight (mg) when applying Newton's second law to find the associated differential equation. When we met our teacher again he said that we...
  16. F

    Can you find tension on a string without mass

    So my pulley system has 3 masses two of which are connected to a center mass on top of a table. No mass was given for any of the objects but of two masses hanging from the table, the one on the right is 2 times the mass on the left. I hope I haven't confused you but its like a three step diagram...
  17. pyctz

    Transverse waves moving (a string)

    in transverse wave (traveling pulse) when a particle move down it has maximum velocity at equilibrium point , why it stop suddenly at this point?
  18. A

    Foucault pendulums -- ordering the part that connects the string to the ceiling

    Do you know where I can order a part that connects string to the ceiling? The part has to be rotate free with very tiny friction. Inside the part may be air filled or vacuum. There has to be no hard wired connection between the ceiling and the part. I would make one if I know how. Hope someone...
  19. Chrono G. Xay

    Can We Predict Damping Coefficient of a String Using Mathematical Simulation?

    Is it possible to predict the damping coefficient of a string using a mathematical simulation that included the string's diameter, length, frequency (and therefore tension), material density, and elastic modulus (if not also its Poisson's ratio) as opposed to simply looking at the amplitudes of...
  20. M

    Vibrate a string with electricity? Best ways?

    Is it possible to vibrate a string with electricity? I'm guessing an electro-magnet placed close to the string would be able to vibrate it. If the electro-magnet is used to vibrate the string, I'm guessing the electro-magnet should be pulsed at the fundamental resonate frequency of the string...
  21. D

    Finding Tension of a string tied to a wall

    In the figure we see two blocks connected by a string and tied to a wall, with θ = 33°. The mass of the lower block is m = 0.9 kg; the mass of the upper block is 4.0 kg. Find the tension in the string that is tied to the wall. -I have the forces of Block A as Tension, Normal Force, and Gravity...
  22. Chrono G. Xay

    Predicting Initial Length of String Needed Before Stretch

    I have put together an equation whose purpose is: With a desired 'magnitude of static friction' ( μ_s ), 'fundamental frequency' ( f ), and 'tension' ( T ), initial conditions such as 'string breakover angle' ( Θ_0 ), 'nut-tuner distance' ( L_{h,0} ), and 'string diameter' ( d ), and...
  23. S

    How Does the Energy of a Struck String Change Over Time?

    Homework Statement An undisturbed string is struck from below by a hammer of width 2a, as shown in the figure. Calculate the total energy of the wave motion and show that it is equal to the energy the string has when it is first struck 3 cases: t=0+ (string just got struck) t>(a/c) (when...
  24. erickbq

    [Statics - Torques] Determining the tension of a string

    Homework Statement A 10.0kg sphere is attached to the incline by a horizontal string. Determine the tension in the string. Homework Equations (F⃗ net)x=ΣFx=0 (F⃗ net)y=ΣFy=0 Στ=0 τ = (radial disance)(F) The Attempt at a Solution 1. I began by determining all the relevant forces associated...
  25. N

    M Theory -- can a fundamental open string end on an M5 brane?

    In M Theory, can an elementary open 1d string attach its ends on an M5 brane? According to M theory, the elementary string are created when an M2 brane is wrapped tightly around a circular dimension. When the open string is created can its end point attach on an M5 brane??
  26. N

    Can the 5 brane of M theory turn into a 1 string?

    Can the 5brane turn into a fundamental string?
  27. S

    String Theory: Compactification Estimate Update

    A lot of people quote 10^ 500 as the number of different ways of compactifying the extra dimension in string theory. But I recall somoene saying at a talk that its now much larger than that. What's the current estimate?
  28. S

    String gets deformed and released - derive equation

    Homework Statement [/B] This graph shows an infinite string on the x-axis. The middle part is deformed as shown. The string is released at time t=0 - give the analytical solution of the problem, i.e. find for t>0 - sketch the string displacement \xi(x) for a sequence of times t. (I'd like...
  29. Hamza Abbasi

    Tension in the string and tangential accleration

    Homework Statement A particle of mass m is whirled on the end of a string of length R. The motion is in vertical plane in Earth's gravitational field . The instantaneous speed is v when the string makes angle Ө with the horizontal. Find the tension T in the string and the tangential...
  30. Master replies:

    Is the closed string an unknot?

    A unknot is pretty much a circle or a 2-sphere, so is a closed string, maybe a bit more irregular but approximatly the same. Of course more is needed to identify the closed string as an unknot than the shape. I assume that it is not so, yet I have no reason to deny it. I hope you may give me a...
  31. Master replies:

    SO(32) heterotic String theory

    I have been following along the problem on SO(32) st. in Zwiebach's "A first course in String theory" and my question concerns this problem. I have no problem with the mathematics of SO(32), at least not at the simple level Zwiebach discusses it, rather the "why" behind a particular concept of...
  32. Armando Valle

    B Can someone explain string theory?

    Can someone explain string theory? and how it works please? I am really interested thanks :D
  33. DavideGenoa

    What is the power of a wave in a string?

    Hi, friendsi! My text of physics, Gettys', shows how the energy, both kynetic and potential, of a small element ##\Delta x## of a string, through which a wave (whose wave function is ##y:\mathbb{R}^2\to\mathbb{R}##, ##(x,t)\mapsto y(x,t)##) runs, is: ##\Delta E=\Big[...
  34. BiGyElLoWhAt

    On a scale of 1 to String, how speculative is this?

    http://arxiv.org/abs/1503.09158 Is this a legitimite thing? I've never heard of 4th color charge or quark-lepton unification.
  35. J

    Energy changes of a stretched string

    Homework Statement This is the answer : For part d) of this question, I don't understand "stretching/extension reduces and velocity increases/height increases" . Homework Equations Hooke's Law: F=kx The Attempt at a Solution Ok, so if extension is reduce, then force reduces too. Then...
  36. Cosmology2015

    A First Course in String Theory/Invariant Interval/Metric

    Hello, Before starting, I would like to apologize for any errors in the use of symbols. This is my first time :sorry:. I am studying the wonderful book of Barton Zwiebach, "A First Course in StringTheory". In chapter 02, I am experiencing for the first time with the mathematics of special...
  37. N

    Can string theory and Penrose interpretation coexist?

    Can the M theory/ string theory coexist with the penrose interpretation of quantum mechanics?
  38. F

    Cut the String - Energy and Friction

    Homework Statement http://imgur.com/FZM5gqC,RlLeGmP#1 http://imgur.com/FZM5gqC,RlLeGmP#0 Homework Equations f^k_{AB} = \mu_k N_{AB} W_{f,i} = \int_{r_i}^{r_f} \vec{F} \cdot d\vec{r} E^{mech}_f = E^{mech}_i + W^{NC}_{f,i} U_{elastic} = \frac{1}{2} k x^2 The Attempt at a Solution Since the...
  39. D

    Wavelength of traveling wave on string (one end clamped and one end free)

    1. Homework Statement A 30-cm long string, with one end clamped and the other free to move transversely, is vibrating in its second harmonic. The wavelength of the constituent traveling waves is A -- 10 cm B -- 40 cm C -- 120 cm D -- 30 cm E -- 60 cm Homework Equations for second...
  40. S

    2-D Motion Problem with 2 masses attached by a string.

    1. Homework Statement Two blocks of masses m1 = 3.7 kg and m2 = 3.3 kg are connected by a string as shown in the figure above. The horizontal surface is frictionless. A 15 N force directed at 18 degrees above the horizontal acts on m2. Determine the acceleration of the blocks and the tension in...
  41. N

    String theory, string dimensions?

    Strings are said to be one dimensional, due to the math. And I understand that there are problems in the math when they put the strings in 3 or 2 dimensions. According to string theory, lengths smaller than Planck length have no physical significance. Could it be that strings are 3...
  42. D

    Standing waves on a moving string

    Hello, I have the configuration as shown in attached picture. I know how to calculate string tension and measure frequency if the string is not moving. But what happens if the string is moving at a constant speed? Are there still standing waves? Can we still calculate the string tension? What if...
  43. andyrk

    Tension in a Mass-less String: Explained

    I get that tension in a mass-less string arises because of electrostatic forces which arise because atoms of the string are pulled apart. I also understand that it is equal and opposite in direction at all points because otherwise the string would accelerate infinitely. But what about the last...
  44. kelvin490

    Analysis of Standing Waves on a Fixed-End String

    By considering the superposition of two waves propagating through a string, one representing the original or incident wave and the other representing the wave reflected at the fixed end, if both ends of the string is fixed then the waves can reflected and travel back and forth. Standing wave can...
  45. kelvin490

    Why Does a Wave Reflect at a Free End with Unchanged Polarity?

    A wave pulse on a string moving from left to right towards a free end will reflect and propagates from right to left with the same speed and amplitude as the incident wave, and with the same polarity. My question is, why the slope and the vertical force must be zero at the free end? If the...
  46. kelvin490

    Question about force in transverse waves on a string

    In deriving wave equation or power transmission of wave transmitted by a string, it is usually stated (with some assumptions) that the transverse force on a point of the string is proportional to the slope at that point. An example is given in p.20 of this notes...
  47. Spinnor

    Spinors and spin in String Theory.

    Assume String Theory is headed in the right direction, can one understand electron (or any Standard Model particle spin for that matter) spin roughly in terms of some small spinning string? If so, would you consider that a selling point of the theory as it provides an explanation for intrinsic...
  48. G

    Static friction between 2 blocks and tension of string

    Homework Statement the maximum force is F=F1 +F2 + T as shown in the textbook... I can't understand why the tension of spring is also = F1...Is it because of the writer assume the spring is directly attached to the part P (upper part of the block) ?? Homework EquationsThe Attempt at a Solution
  49. O

    2 blocks connected by massless string VS. pulley system

    (Note: The title would better describe the subject if written like this: "2 blocks on a horizontal frictionless surface connected by a massless string vs. pulley system")Hello, I have a problem regarding pulling two blocks of different masses connected by a string horizontally with opposing...
  50. middleearthss

    What is the tension in the string?

    Homework Statement A string is connected to a box A mass M at its left end and a box B mass 2M at its right end. Boxes A and B start pulling in opposite directions at the same time with forces which are time dependent and described by functions F(t)=Ct for box A and F(t)=Dt for box B. Values of...
Back
Top