Clade C es el subtipo más prevalente de HIV-1 en el mundo. La estructura cristalina del núcleo de clade C gp120 es descrito por Bjorkman y colegas, en conjunto con el complejo CD4 y el receptor CD4 - inducidos por anticuerpo. El trabajo revela que el anticuerpo hace contacto con ambos, gp120 y CD4. La portada de la revista muestra una escultura de vidrio de una partícula viral realizada por el artistaLuke Jerram (http://www.lukejerram.com/projects/glass_microbiology).pp 608–613
Study confirms principle’s limits on measurement accuracy.
Encapsulating the strangeness of quantum mechanics is a single mathematical expression. According to every undergraduate physics textbook, the uncertainty principle states that it is impossible to simultaneously know the exact position and momentum of a subatomic particle — the more precisely one knows the particle’s position at a given moment, the less precisely one can know the value of its momentum.
But the original version of the principle, put forward by physicist Werner Heisenberg in 1927, couches quantum indeterminism in a different way — as a fundamental limit to how well a detector can measure quantum properties. Heisenberg offered no direct proof for this version of his principle, and expressed his ideas “only informally and intuitively”, says physicist Jos Uffink of the University of Minnesota in Minneapolis.
Now researchers say that they have a formal proof. “Our work shows that you can’t measure something with an accuracy any better than the fundamental quantum uncertainty,” says Paul Busch, a theoretical physicist at the University of York, UK, who with his colleagues posted the proof on 6 June on the arXiv preprint server1. Not only does the work place this measurement aspect of the uncertainty principle on solid ground — something that researchers had started to question — but it also suggests that quantum-encrypted messages can be transmitted securely.