1,457 research outputs found
The NAD(P)H-utilizing glutamate dehydrogenase of Bacteroides thetaiotamicron belongs to enzyme family I, and its activity is affected by trans-acting gene(s) positioned downstream of gdhA
Previous studies have suggested that regulation of the enzymes of ammonia assimilation in human colonic Bacteroides species is coordinated differently than in other eubacteria. The gene encoding an NAD(P)H-dependent glutamate dehydrogenase (gdhA) in Bacteroides thetaiotaomicron was tinned and expressed in Escherichia coli by mutant complementation from the recombinant plasmid pANS100. Examination of the predicted GdhA amino acid sequence revealed that this enzyme possesses motifs typical of the family I-type hexameric GDH proteins. Northern blot analysis with a gdhA-specific probe indicated that a single transcript with an electrophoretic mobility of ~1.6 kb was produced in both B. thetaiotaomicron and E. coli gdhA transformants. Although gdhA transcription was unaffected, no GdhA enzyme activity could be detected in E. coli transformants when smaller DNA fragments from pANS100, which contained the entire gdhA gene, were analyzed. Enzyme activity was restored if these E. coli strains were cotransformed with a second plasmid, which contained a 3-kb segment of DNA located downstream of the gdhA coding region. Frameshift mutagenesis within the DNA downstream of gdhA in pANS100 also resulted in the loss of GdhA enzyme activity. Collectively, these results are interpreted as evidence for the role of an additional gene product(s) in modulating the activity of GDH enzyme activity. Insertional mutagenesis experiments which led to disruption of the gdhA gene on the B. thetaiotaomicron chromosome indicated that gdhA mutants were not glutamate auxotrophs, but attempts to isolate similar mutants with insertion mutations in the region downstream of the gdhA gene were unsuccessful
False discovery rate: setting the probability of false claim of detection
When testing multiple hypothesis in a survey --e.g. many different source
locations, template waveforms, and so on-- the final result consists in a set
of confidence intervals, each one at a desired confidence level. But the
probability that at least one of these intervals does not cover the true value
increases with the number of trials. With a sufficiently large array of
confidence intervals, one can be sure that at least one is missing the true
value. In particular, the probability of false claim of detection becomes not
negligible. In order to compensate for this, one should increase the confidence
level, at the price of a reduced detection power. False discovery rate control
is a relatively new statistical procedure that bounds the number of mistakes
made when performing multiple hypothesis tests. We shall review this method,
discussing exercise applications to the field of gravitational wave surveys.Comment: 7 pages, 3 table, 3 figures. Prepared for the Proceedings of GWDAW 9
(http://lappc-in39.in2p3.fr/GWDAW9) A new section was added with a numerical
example, along with two tables and a figure related to the new section. Many
smaller revisions to improve readibilit
Training-induced inversion of spontaneous exchange bias field on La1.5Ca0.5CoMnO6
In this work we report the synthesis and structural, electronic and magnetic
properties of La1.5Ca0.5CoMnO6 double-perovskite. This is a re-entrant spin
cluster material which exhibits a non-negligible negative exchange bias effect
when it is cooled in zero magnetic field from an unmagnetized state down to low
temperature. X-ray powder diffraction, X-ray photoelectron spectroscopy and
magnetometry results indicate mixed valence state at Co site, leading to
competing magnetic phases and uncompensated spins at the magnetic interfaces.
We compare the results for this Ca-doped material with those reported for the
resemblant compound La1.5Sr0.5CoMnO6, and discuss the much smaller spontaneous
exchange bias effect observed for the former in terms of its structural and
magnetic particularities. For La1.5Ca0.5CoMnO6, when successive magnetization
loops are carried, the spontaneous exchange bias field inverts its sign from
negative to positive from the first to the second measurement. We discuss this
behavior based on the disorder at the magnetic interfaces, related to the
presence of a glassy phase. This compound also exhibits a large conventional
exchange bias, for which there is no sign inversion of the exchange bias field
for consecutive cycles
Biographies
There is a prevailing bias, even amongst the actors directly involved, to consider activities
falling under the migration-development banner as bipolar engagements, i.e. activities
linking a country of origin of migrants to their country of present residence. Such
conceptualisations assume the nation-state as the default frame of reference. Whilst
progress has certainly been made towards a necessary sophistication of migration related
issues in policy thinking and related academic research, the migration-development nexus
remains something still often considered as essentially something to approach within a
singular or bipolar nation-state framework. This can be seen in studies of potential policy
interventions related to transnational flows such as human capital transfers, remittance
flows and community development projects initiatives. Taking the case of the Transnational
Synergy for Cooperation and Development (TRANSCODE) Programme, and focusing on
empirical insights gained with this programme in relation to its conceptual underpinnings,
we explore alternative modes of incorporating migration and development. This article
thus seeks to provide insights in opportunities for alternative initiatives resulting out of
cross-fertilization of experiences and ideas between migrant organisations and other actors
engaged in migration and development efforts
Homogeneous nucleation of dislocations as a pattern formation phenomenon
Dislocation nucleation in homogeneous crystals initially unfolds as a linear
symmetry-breaking elastic instability. In the absence of explicit nucleation
centers, such instability develops simultaneously all over the crystal and due
to the dominance of long range elastic interactions it advances into the
nonlinear stage as a collective phenomenon through pattern formation. In this
paper we use a novel mesoscopic tensorial model (MTM) of crystal plasticity to
study the delicate role of crystallographic symmetry in the development of the
dislocation nucleation patterns in defect free crystals loaded in a hard
device. The model is formulated in 2D and we systematically compare lattices
with square and triangular symmetry. To avoid the prevalence of the
conventional plastic mechanisms, we consider the loading paths represented by
pure shears applied on the boundary of the otherwise unloaded body. These
loading protocols can be qualified as exploiting the 'softest' and the
'hardest' directions and we show that the associated dislocation patterns are
strikingly different
Correlation between Gamma-Ray bursts and Gravitational Waves
The cosmological origin of -ray bursts (GRBs) is now commonly
accepted and, according to several models for the central engine, GRB sources
should also emit at the same time gravitational waves bursts (GWBs). We have
performed two correlation searches between the data of the resonant
gravitational wave detector AURIGA and GRB arrival times collected in the BATSE
4B catalog. No correlation was found and an upper limit \bbox{} on the averaged amplitude of gravitational waves
associated with -ray bursts has been set for the first time.Comment: 7 pages, 3 figures, submitted to Phys. Rev.
Analysis of the impact of financial crises on Ouro Scheffer's jewelry sales
This article studies financial crises and their impact on the main types of financial investment. Specifically, the objective of this study is to analyze the impact that financial crises generated in purchase of jewelry at Ouro Scheffer. It was therefore necessary to first revise the concept of main types of investment in variable income and fixed income, as well as a history of gold, and to analyze the main financial crises. Applied and quantitative research was then carried out with an analysis of three temporal series: gold, Ibovespa and Ouro Scheffer''s jewelry sales revenue. The results found that the main financial crises of 1999 and 2008 had an impact on the jewelry sales temporal series. It was also possible to determine that these crises generated an impact on the gold and Ibovespa temporal series
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