460 research outputs found
Associated production of the charged Higgs boson and single top quark at the LHC
The left-right twin Higgs(LRTH) model predicts the existence of the charged
Higgs . In this paper, we study the production of the charged Higgs
boson with single top quark via the process at the
Large Hadron Collider(LHC). The numerical results show that the
production cross section can reach the level of in the reasonable
parameter space of the LRTH model. We expect that, as long as it is not too
heavy, the possible signatures of the heavy charged Higgs boson
might be detected via the decay mode at the LHC
experiments.Comment: This paper has been withdrawn by the author(s) due to some mistakes
in this pape
Fano Effect through Parallel-coupled Double Coulomb Islands
By means of the non-equilibrium Green function and equation of motion method,
the electronic transport is theoretically studied through a parallel-coupled
double quantum dots(DQD) in the presence of the on-dot Coulomb correlation,
with an emphasis put on the quantum interference. It has been found that in the
Coulomb blockage regime, the quantum interference between the bonding and
antiboding DQD states or that between their Coulomb blockade counterparts may
result in the Fano resonance in the conductance spectra, and the Fano peak
doublet may be observed under certain non-equilibrium condition. The
possibility of manipulating the Fano lineshape is predicted by tuning the
dot-lead coupling and magnetic flux threading the ring connecting the dots and
leads. Similar to the case without Coulomb interaction, the direction of the
asymmetric tail of Fano lineshape can be flipped by the external field. Most
importantly, by tuning the magnetic flux, the function of four relevant states
can be interchanged, giving rise to the swap effect, which might play a key
role as a qubit in the quantum computation.Comment: 7 pages, 5 figure
Weighting Methods In The Construction Of Area Deprivation Indices
This study applies and compares several weighted average (WA) methods and Principal Component Analysis (PCA) for the construction of composite area-based deprivation index. The WA methods are based on weights that depend on standard deviation, correlation and data entropy. This paper also proposes three new approaches of WA method by suggesting their respective weights to depend on mean absolute deviation, inter-quartile range and data entropy where the probability is estimated by empirical density function and Gaussian kernel function. The deprivation indices produced by WA methods and PCA are then utilized to rank deprivation level of eighty-one administrative districts in Peninsular Malaysia
Characterization and modeling of the Haemophilus influenzae core and supragenomes based on the complete genomic sequences of Rd and 12 clinical nontypeable strains
The genomes of 9 non-typeable H. influenzae clinical isolates were sequenced and compared with a reference strain, allowing the characterisation and modelling of the core-and supra genomes of this organism
Semileptonic decays in the light-cone QCD sum rules
Semileptonic () decays are investigated systematically in the
light-cone QCD sum rules. Special emphasis is put on the LCSR calculation on
weak form factors with an adequate chiral current correlator, which turns out
to be particularly effective to control the pollution by higher twist
components of spectator mesons. The result for each channel depends on the
distribution amplitude of the the producing meson. The leading twist
distribution amplitudes of the related heavy mesons and charmonium are worked
out by a model approach in the reasonable way. A practical scenario is
suggested to understand the behavior of weak form factors in the whole
kinematically accessible ranges. The decay widths and branching ratios are
estimated for several () decay modes of current interest.Comment: 8 pages, talk given by the first arthur at 4th International
Conference on Flavor Physics (ICFP 2007), Beijing, China, Sept 24-28, 200
A NEW METHOD OF STM TIP FABRICATION FOR INSITU ELECTROCHEMICAL STUDIES
A new method of STM tip fabrication utilizing the electrophoresis technique and the ability of mercury to expand and shrink upon changing the temperature is introduced, and experimental details for tip etching and tip plating are described. Tips electrophoretically plated in 601 water-soluble electrophoretic varnish at 40 V for more than 30 min show good insulation behavior with exposed tip electrode disk radii around 0.8-mu-m. The apices of the plated tips remain undestroyed and clean after undergoing the mercury-touching procedure' and the electrophoretic process. The characterization of ultramicroelectrode behaviors and the STM imaging capability of the plated tips are demonstrated
Comparative Genomic Analyses of the Moraxella catarrhalis Serosensitive and Seroresistant Lineages Demonstrate Their Independent Evolution
Contains fulltext :
172169.pdf (publisher's version ) (Open Access)The bacterial speciesMoraxella catarrhalishas been hypothesized as being composed of two distinct lineages (referred to as the seroresistant [SR] and serosensitive [SS]) with separate evolutionary histories based on several molecular typing methods, whereas 16S ribotyping has suggested an additional split within the SS lineage. Previously, we characterized whole-genome sequences of 12 SR-lineage isolates, which revealed a relatively small supragenome when compared with other opportunistic nasopharyngeal pathogens, suggestive of a relatively short evolutionary history. Here, we performed whole-genome sequencing on 18 strains from both ribotypes of the SS lineage, an additional SR strain, as well as four previously identified highly divergent strains based on multilocus sequence typing analyses. All 35 strains were subjected to a battery of comparative genomic analyses which clearly show that there are three lineages-the SR, SS, and the divergent. The SR and SS lineages are closely related, but distinct from each other based on three different methods of comparison: Allelic differences observed among core genes; possession of lineage-specific sets of core and distributed genes; and by an alignment of concatenated core sequences irrespective of gene annotation. All these methods show that the SS lineage has much longer interstrain branches than the SR lineage indicating that this lineage has likely been evolving either longer or faster than the SR lineage. There is evidence of extensive horizontal gene transfer (HGT) within both of these lineages, and to a lesser degree between them. In particular, we identified very high rates of HGT between these two lineages for ss-lactamase genes. The four divergent strains aresui generis, being much more distantly related to both the SR and SS groups than these other two groups are to each other. Based on average nucleotide identities, gene content, GC content, and genome size, this group could be considered as a separate taxonomic group. The SR and SS lineages, although distinct, clearly form a single species based on multiple criteria including a large common core genome, average nucleotide identity values, GC content, and genome size. Although neither of these lineages arose from within the other based on phylogenetic analyses, the question of how and when these lineages split and then subsequently reunited in the human nasopharynx is explored
Generation of Genic Diversity among Streptococcus pneumoniae Strains via Horizontal Gene Transfer during a Chronic Polyclonal Pediatric Infection
Although there is tremendous interest in understanding the evolutionary roles of horizontal gene transfer (HGT) processes that occur during chronic polyclonal infections, to date there have been few studies that directly address this topic. We have characterized multiple HGT events that most likely occurred during polyclonal infection among nasopharyngeal strains of Streptococcus pneumoniae recovered from a child suffering from chronic upper respiratory and middle-ear infections. Whole genome sequencing and comparative genomics were performed on six isolates collected during symptomatic episodes over a period of seven months. From these comparisons we determined that five of the isolates were genetically highly similar and likely represented a dominant lineage. We analyzed all genic and allelic differences among all six isolates and found that all differences tended to occur within contiguous genomic blocks, suggestive of strain evolution by homologous recombination. From these analyses we identified three strains (two of which were recovered on two different occasions) that appear to have been derived sequentially, one from the next, each by multiple recombination events. We also identified a fourth strain that contains many of the genomic segments that differentiate the three highly related strains from one another, and have hypothesized that this fourth strain may have served as a donor multiple times in the evolution of the dominant strain line. The variations among the parent, daughter, and grand-daughter recombinant strains collectively cover greater than seven percent of the genome and are grouped into 23 chromosomal clusters. While capturing in vivo HGT, these data support the distributed genome hypothesis and suggest that a single competence event in pneumococci can result in the replacement of DNA at multiple non-adjacent loci
Design and validation of a supragenome array for determination of the genomic content of Haemophilus influenzae isolates
Abstract
Background
Haemophilus influenzae colonizes the human nasopharynx as a commensal, and is etiologically associated with numerous opportunistic infections of the airway; it is also less commonly associated with invasive disease. Clinical isolates of H. influenzae display extensive genomic diversity and plasticity. The development of strategies to successfully prevent, diagnose and treat H. influenzae infections depends on tools to ascertain the gene content of individual isolates.
Results
We describe and validate a Haemophilus influenzae supragenome hybridization (SGH) array that can be used to characterize the full genic complement of any strain within the species, as well as strains from several highly related species. The array contains 31,307 probes that collectively cover essentially all alleles of the 2890 gene clusters identified from the whole genome sequencing of 24 clinical H. influenzae strains. The finite supragenome model predicts that these data include greater than 85% of all non-rare genes (where rare genes are defined as those present in less than 10% of sequenced strains). The veracity of the array was tested by comparing the whole genome sequences of eight strains with their hybridization data obtained using the supragenome array. The array predictions were correct and reproducible for ~ 98% of the gene content of all of the sequenced strains. This technology was then applied to an investigation of the gene content of 193 geographically and clinically diverse H. influenzae clinical strains. These strains came from multiple locations from five different continents and Papua New Guinea and include isolates from: the middle ears of persons with otitis media and otorrhea; lung aspirates and sputum samples from pneumonia and COPD patients, blood specimens from patients with sepsis; cerebrospinal fluid from patients with meningitis, as well as from pharyngeal specimens from healthy persons.
Conclusions
These analyses provided the most comprehensive and detailed genomic/phylogenetic look at this species to date, and identified a subset of highly divergent strains that form a separate lineage within the species. This array provides a cost-effective and high-throughput tool to determine the gene content of any H. influenzae isolate or lineage. Furthermore, the method for probe selection can be applied to any species, given a group of available whole genome sequences.http://deepblue.lib.umich.edu/bitstream/2027.42/112375/1/12864_2012_Article_5193.pd
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