Related topics: physical review letters

Computational study reveals how Ebola nucleocapsid stabilizes

The Ebola virus causes a serious infection with a mortality rate between 50% and 90%. Nucleoproteins in the virus assemble into a helical arrangement and encapsulate a single stranded RNA genome, ssRNA, to form a rodlike ...

High pressure is key for better optical fibers

Optical fiber data transmission can be significantly improved by producing the fibers, made of silica glass, under high pressure, researchers from Japan and the US report in the journal npj Computational Materials.

Upgraded X-ray laser shows its soft side

The second phase of a major upgrade project is now online at the Linac Coherent Light Source (LCLS), the pioneering X-ray free-electron laser at Department of Energy's SLAC National Accelerator Laboratory. On September 12, ...

Are antivitamins the new antibiotics?

Antibiotics are among the most important discoveries of modern medicine and have saved millions of lives since the discovery of penicillin almost 100 years ago. Many diseases caused by bacterial infections—such as pneumonia, ...

'Seeing' and 'manipulating' functions of living cells

A research group composed of Professor Takayuki Shibata and his colleagues at Department of Mechanical Engineering, Toyohashi University of Technology, has given greater functionalities to atomic force microscopy (AFM). Our ...

Decoding material wear with supercomputers

Wear and friction are crucial issues in many industrial sectors: What happens when one surface slides across another? Which changes must be expected in the material? What does this mean for the durability and safety of machines?

A fresh twist in chiral topology

The concept of chirality is well-established in science: when an object cannot be superimposed on its mirror image, both the object and its mirror image are called chiral. In the drug industry, for instance, more than 50% ...

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Perturbation theory (quantum mechanics)

In quantum mechanics, perturbation theory is a set of approximation schemes directly related to mathematical perturbation for describing a complicated quantum system in terms of a simpler one. The idea is to start with a simple system for which a mathematical solution is known, and add an additional "perturbing" Hamiltonian representing a weak disturbance to the system. If the disturbance is not too large, the various physical quantities associated with the perturbed system (e.g. its energy levels and eigenstates) can, from considerations of continuity, be expressed as 'corrections' to those of the simple system. These corrections, being 'small' compared to the size of the quantities themselves, can be calculated using approximate methods such as asymptotic series. We can therefore study the complicated system based on our knowledge of the simpler one.

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