711 research outputs found
Susceptibility of South African native conifers to the pitch canker pathogen, Fusarium circinatum
AbstractFusarium circinatum is an economically important pathogen of Pinus species, which also occurs on Douglas fir (Pseudotsuga menzeisii). It causes pitch canker of mature trees and root and collar rot of seedlings and cuttings. In 2007, pitch canker was observed on Pinus radiata in the Western Cape and this was the first outbreak of this disease in South Africa. The Cape flora in this area includes native coniferous species of Podocarpus and Widdringtonia. In this study, seedlings of P. latifolia, P. elongatus, P. henkelii, W. schwartzii, W. cederbergensis and W. nodiflora were inoculated with a virulent isolate of F. circinatum, to assess their susceptibility. Six weeks after inoculation, there was no lesion development in any of the species inoculated. Pinus patula seedlings used as a positive control were severely affected. Results of this study show that species of Podocarpus and Widdringtonia, native to the Western Cape, are not threatened by the pitch canker fungus
Sphaeropsis sapinea and Botryosphaeria dothidea endophytic in Pinus spp. and Eucalyptus spp. in South Africa
Sphaeropsis sapinea (Fr.: Fr.) Dyko & B. Sutton and the anamorph of Botryosphaeria dothidea (Moug.) Ces. et De Not. are morphologically and ecologically similar fungi that cause serious canker and die-back diseases of Pinus and Eucalyptus spp. respectively in South Africa. In this article, the presence of both these fungi as symptomless endophytes In healthy pine and eucafypt tissue was demonstrated. Sphaeropsis sapinea was present in 50% of young, green P patula Schl. et Cham., and 90% of P. radiata D. Don cones. In contrast, it was virtually absent from the cones of P. elliottii Engalm. et Vasey and P. taeda L. Botryosphaeria dothidea, on the other hand, was found to be common in all the Eucalyptus spp. tested, occurring in 93% of E. smithii R. T. Bak., 77% of E. camaldulensis Dehnh., 63% of E. grandis Hill ex Maid, and 57% of E. nitens (Deane et Maid.) Maid, leaves tested. The enigma of the rapid Ingress of both these fungi In stressed or damaged trees might therefore be explained by their endophytic habit
SCARB2 mutations as modifiers in Gaucher disease: the wrong enzyme at the wrong place?
Unlike most lysosomal proteins, β-glucocerebrosidase (GCase), the hydrolase defective in Gaucher disease (GD), is delivered to lysosomes through its interaction with the transmembrane protein LIMP2. A few years ago, mutations in its coding gene, SCARB2, were reported to modify the severity of GD phenotype.
The existence of a great variety of GD phenotypes is well-known, with numerous patients who carry identical genotypes presenting remarkable phenotypic variability. Over the years, that variability has been attributed to other genetic, epigenetic and/or environmental factors. Still, there is still much to learn on this subject. Recently, an association between Parkinson's disease (PD) and the presence of mutations in the GBA gene has been demonstrated. Moreover, there are also studies suggesting that genetic variants in the SCARB2 gene may also be risk factors for PD.
We analysed the SCARB2 gene in the Portuguese cohort of 91 GD patients, having identified 3 different SCARB2 coding variants. Of those, 2 were known polymorphisms with high prevalence in the normal population (p.M159V and p.V396I) and the third was a novel coding variant, p.T398M, present in heterozigousity in a single patient.
Our study demonstrated that, at least for the Portuguese population, genetic variability at SCARB2 does not account much to the GD phenotypic spectrum. Nevertheless, in vitro analyses of the novel p.T398M are envisaged, in order to further characterize the effect of this variant on the levels and sub-cellular location of GCase. The clinical presentation of the patient harbouring this coding variant will also be discussed.FCT PTDC/SAU-GMG/102889/2008; SFRH/BD/124372/2016N/
Model-independent search for CP violation in D0→K−K+π−π+ and D0→π−π+π+π− decays
A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states K−K+π−π+ and π−π+π+π− is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fb−1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the K−K+π−π+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the π−π+π+π− final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity
Search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓
A search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓ is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions at √s=7 TeV, collected by the LHCb experiment. The observed number of Bs0→e±μ∓ and B0→e±μ∓ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0→e±μ∓)101 TeV/c2 and MLQ(B0→e±μ∓)>126 TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds
Measurements of long-range near-side angular correlations in TeV proton-lead collisions in the forward region
Two-particle angular correlations are studied in proton-lead collisions at a
nucleon-nucleon centre-of-mass energy of TeV, collected
with the LHCb detector at the LHC. The analysis is based on data recorded in
two beam configurations, in which either the direction of the proton or that of
the lead ion is analysed. The correlations are measured in the laboratory
system as a function of relative pseudorapidity, , and relative
azimuthal angle, , for events in different classes of event
activity and for different bins of particle transverse momentum. In
high-activity events a long-range correlation on the near side, , is observed in the pseudorapidity range . This
measurement of long-range correlations on the near side in proton-lead
collisions extends previous observations into the forward region up to
. The correlation increases with growing event activity and is found
to be more pronounced in the direction of the lead beam. However, the
correlation in the direction of the lead and proton beams are found to be
compatible when comparing events with similar absolute activity in the
direction analysed.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-040.htm
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
Study of the production of and hadrons in collisions and first measurement of the branching fraction
The product of the () differential production
cross-section and the branching fraction of the decay () is
measured as a function of the beauty hadron transverse momentum, ,
and rapidity, . The kinematic region of the measurements is and . The measurements use a data sample
corresponding to an integrated luminosity of collected by the
LHCb detector in collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb
results of the fragmentation fraction ratio, , the
branching fraction of the decay is
measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi
pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4},
\end{equation*} where the first uncertainty is statistical, the second is
systematic, the third is due to the uncertainty on the branching fraction of
the decay , and the
fourth is due to the knowledge of . The sum of the
asymmetries in the production and decay between and
is also measured as a function of and .
The previously published branching fraction of , relative to that of , is updated.
The branching fractions of are determined.Comment: 29 pages, 19figures. All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm
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