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ABSTRACT:The analytic information theory of quantum systems includes the exact determination of their spatial extension or multidimensional spreading in both position and momentum spaces by means of the familiar variance and its generalization, the power and logarithmic moments, and, more appropriately, the Shannon entropy and the Fisher information. These complementary uncertainty measures have a global or local character, respectively, because they are power-like (variance, moments), logarithmic (Shannon) and gradient (Fisher) functionals of the corresponding probability distribution. Here we explicitly discuss all these spreading measures (and their associated uncertainty relations) in both position and momentum for the main prototype in D-dimensional physics, the hydrogenic system, directly in terms of the dimensionality and the hyperquantum numbers which characterize the involved states. Then, we analyze in detail such measures for s-states, circular states (i.e., single-electron states of highest angular momenta allowed within an electronic manifold characterized by a given principal hyperquantum number), and Rydberg states (i.e., states with large radial hyperquantum numbers n).

African swine fever virus (ASFV) encodes a novel DNA polymerase, constituted of only 174 amino acids, belonging to the polymerase (pol) X family of DNA polymerases. Biochemical analyses of the purified enzyme indicate that ASFV pol X is a monomeric DNA-directed DNA polymerase, highly distributive, lacking a proofreading 3-5-exonuclease, and with a poor discrimination against dideoxynucleotides. A multiple alignment of family X DNA polymerases, together with the extrapolation to the crystal structure of mammalian DNA polymerase ␤ (pol ␤), showed the conservation in ASFV pol X of the most critical residues involved in DNA binding, nucleotide binding, and catalysis of the polymerization reaction. Therefore, the 20-kDa ASFV pol X most likely represents the minimal functional version of an evolutionarily conserved pol ␤-type DNA polymerase core, constituted by only the "palm" and "thumb" subdomains. It is worth noting that such an "unfingered" DNA polymerase is able to handle templated DNA polymerization with a considerable high fidelity at the base discrimination level. Base excision repair is considered to be a cellular defense mechanism repairing modified bases in DNA. Interestingly, the fact that ASFV pol X is able to conduct filling of a single nucleotide gap points to a putative role in base excision repair during the ASFV life cycle.Despite the variety of existing DNA polymerases, there are a few basic principles that are common to all these enzymes, irrespective of their role either in DNA replication or in DNA repair. The basic chemistry of each individual reaction always involves a pair of divalent metal ions that are coordinated by carboxylate residues. Such a two-metal ion mechanism, originally proposed by Beese and Steitz (1) and probably extrapolative to all nucleotidyltransferases (2-4), appears to be either evolutionarily conserved or acquired by convergent evolution of nonhomologous proteins. In addition to the general deoxynucleotidyl transfer mechanism, it appears that some structural convergency could apply also for the interaction with DNA, a common substrate; an overall view of the crystal structures available for DNA-dependent polymerases always shows a hand-shaped structure, with "thumb," "palm," and "fingers" subdomains, defining at least one cleft for holding DNA (5-12). Moreover, both DNA replicases and DNA repair enzymes are often multienzymatic proteins, having built-in nucleolytic activities that exist as individual structural modules, separated from the polymerization domain. Thus, the paradigmatic Escherichia coli DNA polymerase I (pol I) 1 has a proofreading 3Ј-5Ј-exonuclease, and a 5Ј-3Ј-exonuclease to remove the RNA from the Okazaki fragments (13). Most DNA replicases are also endowed with a proofreading 3Ј-5Ј-exonuclease domain, having an evolutionarily conserved pol I-type active site (14). Reverse transcriptases have an RNase H activity, required for second strand DNA synthesis (reviewed in Telesnitsky and Goff (15)). Even pol ␤, the smallest of the known DNA polymerases (39 kDa)...

We compute the entanglement of the ground state and several singlet and triplet excited states of the helium atom using high-quality, state-of-the-art wavefunctions. The behaviour of the entanglement of the helium eigenstates is similar to that observed in some exactly soluble two-electron systems. In particular, the amount of entanglement exhibited by the eigenstates tends to increase with energy.