131 research outputs found
Kinetics of coherent order-disorder transition in
Within a phase field approach which takes the strain-induced elasticity into
account, the kinetics of the coherent order-disorder transition is investigated
for the specific case of alloy. It is shown that a microstructure
with cubic precipitates appears as a transient state during the
decomposition of a homogeneous disordered solid solution into a microstructure
with tetragonal precipitates embedded into a disordered matrix. At
low enough temperature, favored by a weak internal stress, only
precipitates grow in the transient microstructure preceding nucleation of the
precipitates that occurs exclusively at the interface of the solid
solution with the precipitates. Analysis of microstructures at
nanoscopic scale shows a characteristic rod shape for the
precipitates due to the combination of their tetragonal symmetry and their
large internal stress.Comment: 2 postscript figures and 1 JPG pag
Non-linear numerical simulations of magneto-acoustic wave propagation in small-scale flux tubes
We present results of non-linear, 2D, numerical simulations of
magneto-acoustic wave propagation in the photosphere and chromosphere of
small-scale flux tubes with internal structure. Waves with realistic periods of
three to five minutes are studied, after applying horizontal and vertical
oscillatory perturbations to the equilibrium model. Spurious reflections of
shock waves from the upper boundary are minimized thanks to a special boundary
condition. This has allowed us to increase the duration of the simulations and
to make it long enough to perform a statistical analysis of oscillations. The
simulations show that deep horizontal motions of the flux tube generate a slow
(magnetic) mode and a surface mode. These modes are efficiently transformed
into a slow (acoustic) mode in the vA < cS atmosphere. The slow (acoustic) mode
propagates vertically along the field lines, forms shocks and remains always
within the flux tube. It might deposit effectively the energy of the driver
into the chromosphere. When the driver oscillates with a high frequency, above
the cut-off, non-linear wave propagation occurs with the same dominant driver
period at all heights. At low frequencies, below the cut-off, the dominant
period of oscillations changes with height from that of the driver in the
photosphere to its first harmonic (half period) in the chromosphere. Depending
on the period and on the type of the driver, different shock patterns are
observed.Comment: 22 pages 6 color figures, submitted to Solar Physics, proceeding of
SOHO 19/ GONG 2007 meeting, Melbourne, Australi
Soft and hard tissue assessment of immediate implant placement: a case series
Objectives : The aim of this prospective study was to evaluate clinically and radiographically the success and esthetic result of immediate implant placement at the time of extraction. Material and methods : Twelve patients with 14 titanium screw-shaped implants (13–16 mm length and 4.3 or 5 mm diameters) were placed in the extraction sockets. Defects after implant placement were recorded, and then filled up with deproteinized bovine bone mineral, bioabsorbable collagen membrane, and absorbable pins. The defect was again re-evaluated at second-stage surgery. Clinical and radiographic parameters of the peri-implant conditions were assessed at the moment of prosthesis placement and at 1-year follow-up. Results : The cumulative implant survival and success rate was 100% after a 1-year observation period. Analysis of the esthetic result showed that the mean pink esthetic score (PES) was 11.1 (SD 1.35) at 1-year follow-up. At 1 year, 64.3% papillae had a score of 2 and the remaining 35.7% score 3 according to the Jemt (1997) papillary index. Optimal value of width of the keratinized mucosa was recorded in 13 (92.9%) implant cases in both periods of follow-up. At 1-year follow-up, the linear distance between implant-shoulder to the bone peaks remains stable with a mean of 2.62±0.2 mm at the mesial and 2.9±0.58 mm at the distal aspect. Conclusion : Careful evaluation of potential extraction sites before immediate implant installation promotes optimal implant esthetics. To cite this article: Juodzbalys G, Wang H-L. Soft and hard tissue assessment of immediate implant placement: a case series. Clin. Oral Impl. Res. 18 , 2007; 237–243 doi:10.1111/j.1600-0501.2006.01312.xPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74957/1/j.1600-0501.2006.01312.x.pd
Multiwavelength Observations of Supersonic Plasma Blob Triggered by Reconnection Generated Velocity Pulse in AR10808
Using multi-wavelength observations of Solar and Heliospheric Observatory
(SoHO)/Michelson Doppler Imager (MDI), Transition Region and Coronal Explorer
(TRACE) 171 \AA, and H from Culgoora Solar Observatory at Narrabri,
Australia, we present a unique observational signature of a propagating
supersonic plasma blob before an M6.2 class solar flare in AR10808 on 9th
September 2005. The blob was observed between 05:27 UT to 05:32 UT with almost
a constant shape for the first 2-3 minutes, and thereafter it quickly vanished
in the corona. The observed lower bound speed of the blob is estimated as
215 km s in its dynamical phase. The evidence of the blob with
almost similar shape and velocity concurrent in H and TRACE 171 \AA\
supports its formation by multi-temperature plasma. The energy release by a
recurrent 3-D reconnection process via the separator dome below the magnetic
null point, between the emerging flux and pre-existing field lines in the lower
solar atmosphere, is found to be the driver of a radial velocity pulse outwards
that accelerates this plasma blob in the solar atmosphere. In support of
identification of the possible driver of the observed eruption, we solve the
two-dimensional ideal magnetohydrodynamic equations numerically to simulate the
observed supersonic plasma blob. The numerical modelling closely match the
observed velocity, evolution of multi-temperature plasma, and quick vanishing
of the blob found in the observations. Under typical coronal conditions, such
blobs may also carry an energy flux of 7.0 ergs cm
s to re-balance the coronal losses above active regions.Comment: Solar Physics; 22 Pages; 8 Figure
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
Use of discriminant analysis based on echocardiography for classification of congestive heart failure in dogs with myxomatous mitral valve disease
Comprehensive analysis of epigenetic clocks reveals associations between disproportionate biological ageing and hippocampal volume
The concept of age acceleration, the difference between biological age and chronological age, is of growing interest, particularly with respect to age-related disorders, such as Alzheimer’s Disease (AD). Whilst studies have reported associations with AD risk and related phenotypes, there remains a lack of consensus on these associations. Here we aimed to comprehensively investigate the relationship between five recognised measures of age acceleration, based on DNA methylation patterns (DNAm age), and cross-sectional and longitudinal cognition and AD-related neuroimaging phenotypes (volumetric MRI and Amyloid-β PET) in the Australian Imaging, Biomarkers and Lifestyle (AIBL) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Significant associations were observed between age acceleration using the Hannum epigenetic clock and cross-sectional hippocampal volume in AIBL and replicated in ADNI. In AIBL, several other findings were observed cross-sectionally, including a significant association between hippocampal volume and the Hannum and Phenoage epigenetic clocks. Further, significant associations were also observed between hippocampal volume and the Zhang and Phenoage epigenetic clocks within Amyloid-β positive individuals. However, these were not validated within the ADNI cohort. No associations between age acceleration and other Alzheimer’s disease-related phenotypes, including measures of cognition or brain Amyloid-β burden, were observed, and there was no association with longitudinal change in any phenotype. This study presents a link between age acceleration, as determined using DNA methylation, and hippocampal volume that was statistically significant across two highly characterised cohorts. The results presented in this study contribute to a growing literature that supports the role of epigenetic modifications in ageing and AD-related phenotypes
First-Principles Phase Stability Calculations of Pseudobinary Alloys of (Al,Zn)3Ti with L12, D022, and D023 Structures
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