481 research outputs found
Involvement of SNP marker located on the Calcium binding protein gene in adaptive traits and organoleptic performances of the olive tree
Olive trees importance is mainly due to the economic and health benefits, especially in the Mediterranean basin. Unfortunately, to enhance productivity and quality of olive oil, the study of both molecular and phenotypic characterizations of olive cultivars is crucial. We consider the analysis of 14 Tunisian olive cultivars of known origin sampled from different areas of the country based on SNP marker (CALC) located in calcium binding protein gene. Accordingly, we assessed the potential genotype-phenotypes links between the SNP, on the one hand, and the quantitative and qualitative parameters, on the other. The statistical analysis based on bivariate analysis for the CALC marker suggests that Chemlali varieties with CG genotypes have better capacity to produce fruit, fruit oil, oil content in carotene, cholesterol and linoleic acid than homozygote GG genotypes varieties. These results are confirmed by a multivariate logistic regression.Keywords: Olea europaea L; CALC; calcium binding protein; bivariate analysis; multivariate logistic regression
Molecular characterization of γ gliadin from durum wheat (Triticum turgidum L. Subsp. Durum ((Desf.) Husn.)
The gluten quality is one of the main factors affecting the quality of durum wheat. It depends primarily on its storage proteins composition (glutenins and gliadins). In order to set up and initiate a technological quality improvement program of durum wheat we have conducted a prospection of the different protein sequences of gliadin in different databases for Triticum, then the filtration steps and assembly by appropriate software have been conducted to reduce the number of redundant sequences. On the other hand, we have isolated a gene from Iride "Gli-A1" encoding a γ-gliadin protein associated with gluten strength and viscoelasticity of the dough, we performed an in silico molecular and structural analysis in order to define its putative functional properties. The latter could be a valuable candidate as molecular marker for selecting high nutritive value of durum wheat and/or for genetic improvement of durum wheat quality.Keywords: in silico; Storage Proteins; Gliadin; Triticum ; wheat; technological qualit
Bi-directional Alfv\'en Cyclotron Instabilities in the Mega-Amp Spherical Tokamak
Alfv\'en cyclotron instabilities excited by velocity gradients of energetic
beam ions were investigated in MAST experiments with super-Alfv\'enic NBI over
a wide range of toroidal magnetic fields from ~0.34 T to ~0.585 T. In MAST
discharges with high magnetic field, a discrete spectrum of modes in the
sub-cyclotron frequency range is excited toroidally propagating counter to the
beam and plasma current (toroidal mode numbers n < 0).Comment: 28 pages, 13 figures. This article has been submitted to Physics of
Plasmas. After it is published, it will be found at
http://scitation.aip.org/content/aip/journal/pop/brows
Genetic Association of rs1021188 and DNA Methylation Signatures of TNFSF11 in the Risk of Conductive Hearing Loss
Otosclerosis (OTSC) is a complex bone disorder of the otic capsule, which causes conductive hearing impairment in human adults. The dysregulation of the signaling axis mediated by the receptor activator of nuclear factor-kappa-B (RANK), RANK ligand (RANKL), and osteoprotegerin has been widely attributed to the context of metabolic bone disorders. While genetic associations and epigenetic alterations in the TNFSF11 gene (RANKL) have been well-linked to metabolic bone diseases of the skeleton, particularly osteoporosis, they have never been addressed in OTSC. This study aimed to assess whether the genetic association of rs1021188 polymorphism in the upstream of TNFSF11 and the DNA methylation changes in its promoter CpG-region reveal the susceptibility of OTSC. Peripheral blood DNA samples were collected from unrelated Tunisian-North African subjects for genotyping (109 cases and 120 controls) and for DNA methylation analysis (40 cases and 40 controls). The gender-stratified analysis showed that the TNFSF11 rs1021188 C/T was associated with OTSC in men (p = 0.023), but not in women (p = 0.458). Individuals with CC genotype were more susceptible to OTSC, suggesting an increased risk to disease development. Using publicly available data, the rs1021188 was within a cluster grouping the subpopulations with African ethnicity. Moreover, 26 loci in the TNFSF11 gene were in linkage disequilibrium with rs1021188, revealing relative similarities between different populations. Significant differences in both DNA methylation and unmethylation status were detected with 4.53- and 4.83-fold decreases in the global DNA methylation levels in female and male OTSC groups, respectively. These changes could contribute to an increased risk of OTSC development. Bioinformatic analyses indicated that each of the rs1021188 variations and the DNA methylation changes in the promoter CpG-sites within TNFSF11 may play an important role in its transcription regulation. To our knowledge, this is the first study that investigates an independent effect of the rs1021188 polymorphism and DNA hypomethylation of TNFSF11 promoter in OTSC. Genetic and epigenetic changes in the regulatory regions of TNFSF11 could offer new molecular insights into the understanding of the complexity of OTSC
Aerodynamic investigations of ventilated brake discs.
The heat dissipation and performance of a ventilated brake disc strongly depends
on the aerodynamic characteristics of the flow through the rotor passages. The
aim of this investigation was to provide an improved understanding of ventilated
brake rotor flow phenomena, with a view to improving heat dissipation, as well
as providing a measurement data set for validation of computational fluid
dynamics methods. The flow fields at the exit of four different brake rotor
geometries, rotated in free air, were measured using a five-hole pressure probe
and a hot-wire anemometry system. The principal measurements were taken using
two-component hot-wire techniques and were used to determine mean and unsteady
flow characteristics at the exit of the brake rotors. Using phase-locked data
processing, it was possible to reveal the spatial and temporal flow variation
within individual rotor passages. The effects of disc geometry and rotational
speed on the mean flow, passage turbulence intensity, and mass flow were
determined. The rotor exit jet and wake flow were clearly observed as
characterized by the passage geometry as well as definite regions of high and
low turbulence. The aerodynamic flow characteristics were found to be reasonably
independent of rotational speed but highly dependent upon rotor geometry
Review article: MHD wave propagation near coronal null points of magnetic fields
We present a comprehensive review of MHD wave behaviour in the neighbourhood
of coronal null points: locations where the magnetic field, and hence the local
Alfven speed, is zero. The behaviour of all three MHD wave modes, i.e. the
Alfven wave and the fast and slow magnetoacoustic waves, has been investigated
in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null
points, for a variety of assumptions, configurations and geometries. In
general, it is found that the fast magnetoacoustic wave behaviour is dictated
by the Alfven-speed profile. In a plasma, the fast wave is focused
towards the null point by a refraction effect and all the wave energy, and thus
current density, accumulates close to the null point. Thus, null points will be
locations for preferential heating by fast waves. Independently, the Alfven
wave is found to propagate along magnetic fieldlines and is confined to the
fieldlines it is generated on. As the wave approaches the null point, it
spreads out due to the diverging fieldlines. Eventually, the Alfven wave
accumulates along the separatrices (in 2D) or along the spine or fan-plane (in
3D). Hence, Alfven wave energy will be preferentially dissipated at these
locations. It is clear that the magnetic field plays a fundamental role in the
propagation and properties of MHD waves in the neighbourhood of coronal null
points. This topic is a fundamental plasma process and results so far have also
lead to critical insights into reconnection, mode-coupling, quasi-periodic
pulsations and phase-mixing.Comment: 34 pages, 5 figures, invited review in Space Science Reviews => Note
this is a 2011 paper, not a 2010 pape
Influence of plasma turbulence on microwave propagation
It is not fully understood how electromagnetic waves propagate through plasma
density fluctuations when the size of the fluctuations is comparable with the
wavelength of the incident radiation. In this paper, the perturbing effect of a
turbulent plasma density layer on a traversing microwave beam is simulated with
full-wave simulations. The deterioration of the microwave beam is calculated as
a function of the characteristic turbulence structure size, the turbulence
amplitude, the depth of the interaction zone and the size of the waist of the
incident beam. The maximum scattering is observed for a structure size on the
order of half the vacuum wavelength. The scattering and beam broadening was
found to increase linearly with the depth of the turbulence layer and
quadratically with the fluctuation strength. Consequences for experiments and
3D effects are considered.Comment: 16 pages, 13 figures. This is an author-created, un-copyedited
version of an article submitted for publication in Plasma Physics and
Controlled Fusion. IoP Publishing Ltd is not responsible for any errors or
omissions in this version of the manuscript or any version derived from i
Genome profiling of ERBB2-amplified breast cancers
<p>Abstract</p> <p>Background</p> <p>Around 20% of breast cancers (BC) show <it>ERBB2 </it>gene amplification and overexpression of the ERBB2 tyrosine kinase receptor. They are associated with a poor prognosis but can benefit from targeted therapy. A better knowledge of these BCs, genomically and biologically heterogeneous, may help understand their behavior and design new therapeutic strategies.</p> <p>Methods</p> <p>We defined the high resolution genome and gene expression profiles of 54 <it>ERBB2</it>-amplified BCs using 244K oligonucleotide array-comparative genomic hybridization and whole-genome DNA microarrays. Expression of ERBB2, phosphorylated ERBB2, EGFR, IGF1R and FOXA1 proteins was assessed by immunohistochemistry to evaluate the functional ERBB2 status and identify co-expressions.</p> <p>Results</p> <p>First, we identified the <it>ERBB2</it>-<it>C17orf37</it>-<it>GRB7 </it>genomic segment as the minimal common 17q12-q21 amplicon, and <it>CRKRS </it>and <it>IKZF3 </it>as the most frequent centromeric and telomeric amplicon borders, respectively. Second, GISTIC analysis identified 17 other genome regions affected by copy number aberration (CNA) (amplifications, gains, losses). The expression of 37 genes of these regions was deregulated. Third, two types of heterogeneity were observed in <it>ERBB2</it>-amplified BCs. The genomic profiles of estrogen receptor-postive (ER+) and negative (ER-) <it>ERBB2</it>-amplified BCs were different. The WNT/β-catenin signaling pathway was involved in ER- <it>ERBB2</it>-amplified BCs, and <it>PVT1 </it>and <it>TRPS1 </it>were candidate oncogenes associated with ER+ <it>ERBB2</it>-amplified BCs. The size of the <it>ERBB2 </it>amplicon was different in inflammatory (IBC) and non-inflammatory BCs. <it>ERBB2</it>-amplified IBCs were characterized by the downregulated and upregulated mRNA expression of ten and two genes in proportion to CNA, respectively. IHC results showed (i) a linear relationship between <it>ERBB2 </it>gene amplification and its gene and protein expressions with a good correlation between ERBB2 expression and phosphorylation status; (ii) a potential signaling cross-talk between EGFR or IGF1R and ERBB2, which could influence response of <it>ERBB2</it>-positive BCs to inhibitors. FOXA1 was frequently coexpressed with ERBB2 but its expression did not impact on the outcome of patients with <it>ERBB2</it>-amplified tumors.</p> <p>Conclusion</p> <p>We have shown that ER+ and ER- <it>ERBB2</it>-amplified BCs are different, distinguished <it>ERBB2 </it>amplicons in IBC and non-IBC, and identified genomic features that may be useful in the design of alternative therapeutical strategies.</p
Evaluation of strain and stress states in the single point incremental forming process
Single point incremental forming (SPIF) is a promising
manufacturing process suitable for small batch production.
Furthermore, the material formability is enhanced in
comparison with the conventional sheet metal forming processes,
resulting from the small plastic zone and the incremental
nature. Nevertheless, the further development of the SPIF
process requires the full understanding of the material deformation
mechanism, which is of great importance for the effective
process optimization. In this study, a comprehensive
finite element model has been developed to analyse the state
of strain and stress in the vicinity of the contact area, where the
plastic deformation increases by means of the forming tool
action. The numerical model is firstly validated with experimental
results from a simple truncated cone of AA7075-O
aluminium alloy, namely, the forming force evolution, the
final thickness and the plastic strain distributions. In order to
evaluate accurately the through-thickness gradients, the blank
is modelled with solid finite elements. The small contact area
between the forming tool and the sheet produces a negative
mean stress under the tool, postponing the ductile fracture
occurrence. On the other hand, the residual stresses in both
circumferential and meridional directions are positive in the
inner skin of the cone and negative in the outer skin. They
arise predominantly along the circumferential direction due to
the geometrical restrictions in this direction.The authors would like to gratefully acknowledge the
financial support from the Portuguese Foundation for Science and Technology
(FCT) under project PTDC/EMS-TEC/1805/2012. The first author is
also grateful to the FCT for the postdoctoral grant SFRH/BPD/101334/2014.info:eu-repo/semantics/publishedVersio
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