Open questions in utility theory

Throughout this paper, our main idea is to explore different classical questions arising in Utility Theory, with a particular attention to those that lean on numerical representations of preference orderings. We intend to present a survey of open questions in that discipline, also showing the state-of-art of the corresponding literature.This work is partially supported by the research projects ECO2015-65031-R, MTM2015-63608-P (MINECO/ AEI-FEDER, UE), and TIN2016-77356-P (MINECO/ AEI-FEDER, UE)

Finding the Needles in the Metagenome Haystack

In the collective genomes (the metagenome) of the microorganisms inhabiting the Earth’s diverse environments is written the history of life on this planet. New molecular tools developed and used for the past 15 years by microbial ecologists are facilitating the extraction, cloning, screening, and sequencing of these genomes. This approach allows microbial ecologists to access and study the full range of microbial diversity, regardless of our ability to culture organisms, and provides an unprecedented access to the breadth of natural products that these genomes encode. However, there is no way that the mere collection of sequences, no matter how expansive, can provide full coverage of the complex world of microbial metagenomes within the foreseeable future. Furthermore, although it is possible to fish out highly informative and useful genes from the sea of gene diversity in the environment, this can be a highly tedious and inefficient procedure. Microbial ecologists must be clever in their pursuit of ecologically relevant, valuable, and niche-defining genomic information within the vast haystack of microbial diversity. In this report, we seek to describe advances and prospects that will help microbial ecologists glean more knowledge from investigations into metagenomes. These include technological advances in sequencing and cloning methodologies, as well as improvements in annotation and comparative sequence analysis. More significant, however, will be ways to focus in on various subsets of the metagenome that may be of particular relevance, either by limiting the target community under study or improving the focus or speed of screening procedures. Lastly, given the cost and infrastructure necessary for large metagenome projects, and the almost inexhaustible amount of data they can produce, trends toward broader use of metagenome data across the research community coupled with the needed investment in bioinformatics infrastructure devoted to metagenomics will no doubt further increase the value of metagenomic studies in various environments

Propeller-like Conformation of Diphenylacetic Acid

Abstract Crystal structure of diphenylacetic acid has been solved by X-ray diffraction. The crystals are monoclinic, space group P21/c, with a = 12.254(4) Å, b = 7.2260(8) Å, c = 17.521(4) Å, ß = 133.38(1)°, Mr = 212.24, V = 1127.6(5) Å3, Z = 4 and R = 0.045. A strong hydrogen bond links the molecules in dimers. The dimers are connected by weaker C–H···p and p···p interactions. A calculation was performed for the isolated molecule and for the dimer within the Hartree-Fock (HF) level with a 6-311G(d) basis set. In both calculations, the minimum of the energy is achieved with the phenyl rings assuming a more symmetric arrangement around the central carboxylic plane than is experimentally observed. Graphical Abstract In diphenylacetic acid the molecules are coupled in dimers by a strong hydrogen bonds. Weaker intermolecular interactions involving the aromatic ring p systems join the dimers together