1,479 research outputs found
The significance of epidemic plasmids in the success of multidrug-resistant drug pandemic extraintestinal pathogenic Escherichia coli
DATA AVAILABILITY : Data sharing is not
applicable to this article as no data sets were
generated or analyzed during the current study.Epidemic IncF plasmids have been pivotal in
the selective advantage of multidrug-resistant
(MDR) extraintestinal pathogenic Escherichia
coli (ExPEC). These plasmids have offered several
advantages to their hosts that allowed them
to coevolve with the bacterial host genomes and
played an integral role in the success of ExPEC.
IncF plasmids are large, mosaic, and often contain
various types of antimicrobial resistance
(AMR) and virulence associated factor (VAF)
genes. The presence of AMR, VAF genes, several
addition/restriction systems combined with
truncated transfer regions, led to the fixation of
IncF plasmids in certain ExPEC MDR clones,
such as ST131 and ST410. IncF plasmids entered
the ST131 ancestral lineage in the mid 1900s and different ST131 clade/CTX-M plasmid
combinations coevolved over time. The
IncF_CTX-M-15/ST131-C2 subclade combination
emerged during the early 2000s, spread
rapidly across the globe, and is one of the
greatest clone/plasmid successes of the millennium.
The ST410-B3 subclade containing
blaCTX-M-15 incorporated the NDM-5 carbapenemase
gene into existing IncF platforms, providing
an additional positive selective
advantage that included the carbapenems. A
ââplasmid-replacementââ clade scenario occurred
in the histories of ST131 and ST410 as different
subclades gained different AMR genes on different
IncF platforms. The use of antimicrobial
agents will generate selection pressures that
enhance the risks for the continuous emergence
of MDR ExPEC clone/IncF plasmid combinations.
The reasons for clade/IncF replacements
and associations between certain clades and
specific IncF plasmid types are unknown. Such
information will aid in designing management
and prevention strategies to combat AMR.Research grants from the JPIAMR/Canadian Institute Health Research program and National Institute of Health. The study is in part supported by NIAID grant R01AI090155.https://www.springer.com/journal/40121am2024Medical MicrobiologySDG-03:Good heatlh and well-bein
XPS evidence for molecular charge-transfer doping of graphene
By employing x-ray photoelectron spectroscopy (XPS), we have been able to
establish the occurrence of charge-transfer doping in few-layer graphene
covered with electron acceptor (TCNE) and donor (TTF) molecules. We have
performed quantitative estimates of the extent of charge transfer in these
complexes and elucidated the origin of unusual shifts of their Raman G bands
and explained the differences in the dependence of conductivity on n- and
p-doping. The study unravels the cause of the apparent difference between the
charge-transfer doping and electrochemical doping.Comment: 15 pages, 5 figure
Study of an Alternate Mechanism for the Origin of Fermion Generations
In usual extended technicolor (ETC) theories based on the group
, the quarks of charge 2/3 and -1/3 and the charged
leptons of all generations arise from ETC fermion multiplets transforming
according to the fundamental representation. Here we investigate a different
idea for the origin of SM fermion generations, in which quarks and charged
leptons of different generations arise from ETC fermions transforming according
to different representations of . Although this
mechanism would have the potential, {\it a priori}, to allow a reduction in the
value of relative to conventional ETC models, we show that, at least
in simple models, it is excluded by the fact that the technicolor sector is not
asymptotically free or by the appearance of fermions with exotic quantum
numbers which are not observed.Comment: 6 pages, late
Recommended from our members
Mechanical performance and corrosion behaviour of Zr-based bulk metallic glass produced by selective laser melting
Nearly fully dense, glassy Zr52.5Cu17.9Ni14.6Al10Ti5 bulk specimens were fabricated by selective laser melting (SLM) and their behaviour during compressive loading, during wear testing and in a corrosive medium was investigated. Their performance was compared with as-cast material of the same composition. The additively manufactured samples exhibit a yield strength around 1700 MPa combined with a plastic strain of about 0.5% after yielding despite the residual porosity of 1.3%, which is distributed uniformly in the samples. The propagation of shear bands in the bulk metallic glass prepared by SLM was studied. The specific wear rate and the worn surfaces demonstrated that similar wear mechanisms are active in the SLM and the as-cast samples. Hence, manufacturing the glass in layers does not adversely affect the wear properties. The same holds for the corrosion tests, which were carried out in 0.01 M Na2SO4 and 0.1 M NaCl electrolyte. The anodic polarization curves of SLM samples and as-cast samples revealed a similar corrosion behaviour. However, the SLM samples have a slightly reduced susceptibility to pitting corrosion and exhibit an improved surface healing ability, which might be attributed to an improved homogeneity of the additively manufactured glass
Thin deformable mirrors for a reconfigurable space telescope
As part of a small satellite technology demonstration that will utilize autonomous assembly, reconfiguration, and docking technology to form the primary mirror for the missionâs telescope payload, the mirror segments are required to modify and control their shape, in order to allow for imaging in different configurations. This paper focuses on the development of 10 cm diameter active lightweight mirrors. The current mirror design, control scheme, and fabrication methods are described, as well as experimental results on initial samples. The data demonstrates that the mirrors are capable of at least 100 microns of displacement during operation, and that fabrication on polished molds can result in high quality reflective surfaces
Thermoelectrics Near the Mott Localization-Delocalization Transition
We give an overview on current status of the theoretical research on
Thermoelectricity for correlated materials. We derive the theoretical formulas
which become exact at low and high temperature and discuss the intermediate
temperature results. In particular, we show that within Dynamical Mean Field
Theory the low temperature sign of the thermopower is not necessary the same as
in LDA, and that significant non-universality is expected due to strong
correlations.Comment: appeared in "Properties and Applications of Thermoelectric
Materials", Edited by V. Zlatic and A.C. Hewson, Springe
The effect of a 24-hour photoperiod on the survival, growth and swim bladder inflation of pre-flexion yellowfin tuna (Thunnus albacares) larvae
The effects of two different continuous photoperiod regimes on survival, growth and swim bladder inflation of pre-flexion yellowfin tuna (Thunnus albacares) larvae were investigated. Each photoperiod regime was tested twice with a different larval cohort to confirm the observed results. Trials 1 and 2 tested the effect of a reduced night-time light intensity (10-molesm-2s-1=30% of the daytime intensity) and found that those larvae reared for 8days under the 24h lighting (24-L) photoperiod exhibited a slight improvement in survival compared to those reared under the control photoperiod of 12h light (12-L), however these improvements were not significant. In addition, those larvae reared under this photoperiod regime were equal in length to those in the control. Trials 3 and 4 compared the same variables in larvae reared under a continuous photoperiod (24-L) with a constant light intensity of 30-molesm-2s-1, against those reared under the aforementioned 12-L photoperiod. Survival of larvae under the continuous photoperiods were 9±1% (n=2) and 10±2% (n=3) for Trials 3 and 4, respectively, compared to less than 1% in both control treatments; differences that in both cases were highly significant. In addition, in both trials larvae cultured under the 24-L photoperiod were significantly larger and exhibited more advanced development than those reared under the 12-L photoperiod, however swim bladder inflation was significantly lower. We suggest that the improved survival and growth achieved under a continuous photoperiod is due to the extended foraging time combined with the prevention of mortality caused by night-time sinking
Classification of protein interaction sentences via gaussian processes
The increase in the availability of protein interaction studies in textual format coupled with the demand for easier access to the key results has lead to a need for text mining solutions. In the text processing pipeline, classification is a key step for extraction of small sections of relevant text. Consequently, for the task of locating protein-protein interaction sentences, we examine the use of a classifier which has rarely been applied to text, the Gaussian processes (GPs). GPs are a non-parametric probabilistic analogue to the more popular support vector machines (SVMs). We find that GPs outperform the SVM and na\"ive Bayes classifiers on binary sentence data, whilst showing equivalent performance on abstract and multiclass sentence corpora. In addition, the lack of the margin parameter, which requires costly tuning, along with the principled multiclass extensions enabled by the probabilistic framework make GPs an appealing alternative worth of further adoption
Exact time-localized solutions in Vacuum String Field Theory
We address the problem of finding star algebra projectors that exhibit
localized time profiles. We use the double Wick rotation method, starting from
an Euclidean (unconventional) lump solution, which is characterized by the
Neumann matrix being the conventional one for the continuous spectrum, while
the inverse of the conventional one for the discrete spectrum. This is still a
solution of the projector equation and we show that, after inverse
Wick-rotation, its time profile has the desired localized time dependence. We
study it in detail in the low energy regime (field theory limit) and in the
extreme high energy regime (tensionless limit) and show its similarities with
the rolling tachyon solution.Comment: 27 pages, 2 figures. v2: typos corrected, ref added, comment added in
last section, to appear on NP
Spin Exciton in quantum dot with spin orbit coupling in high magnetic field
Coulomb interactions of few () electrons confined in a disk shaped
quantum dot, with a large magnetic field applied in the z-direction
(orthogonal to the dot), produce a fully spin polarized ground state. We
numerically study the splitting of the levels corresponding to the multiplet of
total spin (each labeled by a different total angular momentum )
in presence of an electric field parallel to , coupled to by a
Rashba term. We find that the first excited state is a spin exciton with a
reversed spin at the origin. This is reminiscent of the Quantum Hall
Ferromagnet at filling one which has the skyrmion-like state as its first
excited state. The spin exciton level can be tuned with the electric field and
infrared radiation can provide energy and angular momentum to excite it.Comment: 9 pages, 9 figures. submitted to Phys.Rev.
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