Search results for " cluster"

A gene transfer agent and a dynamic repertoire of secretion systems hold the keys to the explosive radiation of the emerging pathogen Bartonella

2013

Gene transfer agents (GTAs) randomly transfer short fragments of a bacterial genome. A novel putative GTA was recently discovered in the mouse-infecting bacterium Bartonella grahamii. Although GTAs are widespread in phylogenetically diverse bacteria, their role in evolution is largely unknown. Here, we present a comparative analysis of 16 Bartonella genomes ranging from 1.4 to 2.6 Mb in size, including six novel genomes from Bartonella isolated from a cow, two moose, two dogs, and a kangaroo. A phylogenetic tree inferred from 428 orthologous core genes indicates that the deadly human pathogen B. bacilliformis is related to the ruminant-adapted clade, rather than being the earliest diverging…

The accuracy of molecular dipole moments in standard electronic structure calculations

2000

Abstract A systematic investigation has been carried out of the accuracy of calculated molecular equilibrium dipole moments of 11 polar closed-shell molecules, using the HF, MP2, CCSD and CCSD(T) models and correlation-consistent basis sets. Augmented basis sets are important for improving the basis-set convergence, but the quality of the results depends more on the correlation treatment than on the cardinal number of the basis set. Augmented triple-zeta basis sets are sufficient for most calculations. The mean absolute error of the HF calculations is 0.16 D, which is reduced at the MP2 and CCSD levels to 0.048 and 0.025 D, respectively. The CCSD(T) errors are small – typically

Medical news aggregation and ranking of taking into account the user needs

2019

The purpose of this work is to develop an intelligent information system that is designed for aggregation and ranking of news taking into account the needs of the user. The online market for mass media and the needs of readers, the purpose of their searches and moments is not enough to find the news is analyzed. A conceptual model of the information aggression system and ranking of news that would enable presentation of the work of the future intellectual information system, to show its structure is constructed. The methods and means for implementation of the intellectual information system are selected. An online resource for aggregation and ranking of news, news feeds and flexible setting…

A study of the B and Be star population in the field of the LMC open cluster NGC 2004 with VLT-FLAMES

2005

Observations of hot stars belonging to the young cluster LMC-NGC2004 and its surrounding region have been obtained with the VLT-GIRAFFE facilities in MEDUSA mode. 25 Be stars were discovered; the proportion of Be stars compared to B-type stars is found to be of the same order in the LMC and in the Galaxy fields. 23 hot stars were discovered as spectroscopic binaries (SB1 and SB2), 5 of these are found to be eclipsing systems from the MACHO database, with periods of a few days. About 75% of the spectra in our sample are polluted by hydrogen (Halpha and Hgamma), [SII] and [NII] nebular lines. These lines are typical of HII regions. They could be associated with patchy nebulosities with a bi-m…

Cluster-based active learning for compact image classification

2010

In this paper, we consider active sampling to label pixels grouped with hierarchical clustering. The objective of the method is to match the data relationships discovered by the clustering algorithm with the user's desired class semantics. The first is represented as a complete tree to be pruned and the second is iteratively provided by the user. The active learning algorithm proposed searches the pruning of the tree that best matches the labels of the sampled points. By choosing the part of the tree to sample from according to current pruning's uncertainty, sampling is focused on most uncertain clusters. This way, large clusters for which the class membership is already fixed are no longer…

Discovering Protein Complexes in Protein Interaction Networks

2009

An ab initio potential energy surface for the C2H2-N2 system

2012

International audience; An ab initio potential energy surface determined at the CCSD(T) level of theory is presented for the van der Waals complex C2H2-N2. Additional calculations performed with the HF- and DFT-SAPT methods compare well with the CCSD(T) results and allow a better understanding of the main features of this interaction potential surface. An expansion of this surface over spherical harmonics has also been performed. The global energy minimum of the complex is obtained for the linear conformation. The T conformations are the least attractive. Such characteristics mainly arise because of the variation, in sign and in absolute value of the electrostatic energy between all these c…

Biosynthesis of heterocycles: From isolation to gene cluster

2015

This book describes biosynthetic methods to synthesize heterocyclic compounds, offering a guide for the development of new drugs based on natural products. The authors explain the role of natural products in chemistry and their formation along with important analytical methods and techniques for working with heterocycles. Covers methods and techniques: isotopic labelling, enzymes and mutants, and pathway identification. Provides a thorough resource of information specifically on heterocyclic natural products and their practical biosynthetic relevance. Explains the role of natural products in chemistry and their formation. Discusses gene cluster identification and the use of biogenetic engin…

Differences in mosquito (Diptera: Culicidae) biodiversity across varying climates and land-use categories in Eastern Spain

2011

Intensive larval samplings of mosquitoes (Diptera: Culicidae) were carried out between 2005 and 2008 in several biotopes located in a varying climate region in Eastern Spain. The biodiversity was analyzed and divided into alpha, beta and gamma components with the aim of comparing the mosquito biodiversity according to the different structure of the landscape due to the incidence of climatic and anthropic patterns. Likewise the synanthropic index of Nuorteva was calculated for each species. A total of 11,279 mosquitoes belonging to 29 species was collected and identified. Mosquito biodiversity is higher in the wettest and nonanthropized areas. Using a cluster analysis, all this information w…

A computational study of some electric and magnetic properties of gaseous BF3 and BCl3

2005

We present the results of an extended computational study of the electric and magnetic properties connected to Cotton-Mouton birefringences, on the trifluoro- and trichloroborides in the gas phase. The electric dipole polarizabilities, magnetizabilities, quadrupole moments, and higher-order hypersusceptibilities—expressed as quadratic and cubic frequency-dependent response functions—are computed within Hartree-Fock, density-functional, and coupled-cluster response theories employing singly and doubly augmented correlation-consistent basis sets and London orbitals in the magnetic property calculations. The results, which illustrate the capability of time-dependent density-functional theory f…