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In 1872, Maxwell proposed his famous 'demon' thought experiment1. By discerning which particles in a gas are hot and which are cold, and then performing a series of reversible actions, Maxwell's demon could rearrange the particles into a manifestly lower-entropy state. This apparent violation of the second law of thermodynamics was resolved by twentieth-century theoretical work2: the entropy of the Universe is often increased while gathering information3, and there is an unavoidable entropy increase associated with the demon's memory4. The appeal of the thought experiment has led many real experiments to be framed as demon-like. However, past experiments had no intermediate information storage5, yielded only a small change in the system entropy6,7 or involved systems of four or fewer particles8-10. Here we present an experiment that captures the full essence of Maxwell's thought experiment. We start with a randomly half-filled three-dimensional optical lattice with about 60 atoms. We make the atoms sufficiently vibrationally cold so that the initial disorder is the dominant entropy. After determining where the atoms are, we execute a series of reversible operations to create a fully filled sublattice, which is a manifestly low-entropy state. Our sorting process lowers the total entropy of the system by a factor of 2.44. This highly filled ultracold array could be used as the starting point for a neutral-atom quantum computer.

CRISPR/Cas (clustered regularly interspaced palindromic repeats/CRISPR-associated) systems are a bacterial defence against invading foreign nucleic acids derived from bacteriophages or exogenous plasmids (1-4). These systems use an array of small [...]

Change history: We could not replicate the results in Fig. 2a and g of this Letter, and new information has revealed a flaw in the interpretation of Fig. 2h. As a result, we do not have evidence to support RNA degradation as the mechanism that underlies Cas9-mediated regulation of FTN_1103 mRNA expression; see accompanying Amendment. This has not been corrected online., Author(s): Timothy R. Sampson [sup.1] [sup.2] [sup.3] , Sunil D. Saroj [sup.4] , Anna C. Llewellyn [sup.1] [sup.2] [sup.3] , Yih-Ling Tzeng [sup.4] , David S. Weiss [sup.2] [sup.3] [sup.4] [...]

Author(s): Toshiya Kinoshita [1]; Trevor Wenger [1]; David S. Weiss (corresponding author) [1] It is a fundamental assumption of statistical mechanics that a closed system with many degrees of freedom [...]

Gamma-aminobutyric acid (GABA), a prominent inhibitory neurotrasmitter in the brain, activates the ion pores which are chloride selective to the receptor complex. Cloning of the subunits constituting the hetero-pentameric GABA channel provides less information on the activation domains. Xenopus oocytes exhibit the Rat wild-type or the mutated subunits which are numbered as alpha-1, beta-2 and gamma-2. Two separate and homologous domains of the beta-subunits are identified and isolated.

Nature 497, 254-257 (2013); doi:10.1038/nature12048 In this Letter, we described two small RNAs (scaRNA and tracrRNA) within the Francisella novicida CRISPR/Cas locus that are necessary for repression of an endogenous [...]

Reports the identification of two separate and homologous domains of the beta-subunit, each of which contributes a tyrosine and threonine essential for activation by gamma-aminobutyric acid (GABA). Evidence which suggests that the two identified domains of the beta-subunit contribute a major component of the GABA receptor.