1,682 research outputs found
Revitalisation endodontic treatment of traumatised immature teeth: a prospective long-term clinical study
Purpose
Continuation of root development following revitalisation endodontics (RET) has been shown to be unpredictable with lower success rates in traumatised teeth. This study reports the outcomes for RET in traumatised teeth over a review period of 4 years.
Methods
A prospective uncontrolled study, where RET was performed on traumatised upper immature anterior teeth with necrotic pulps in 15 children (mean age = 8.3 years), was conducted. Patients were reviewed at 3, 9, 12, 24, and 48 months, where clinical and radiographic assessments were performed. At the last review appointment, patients and parents answered questions assessing their perception and acceptance of tooth colour change over time. McNemar’s Exact test and linear mixed model assessment were used to assess changes in pulpal electrical response and radiographic evidence of continuation of root development over time, respectively.
Results
There was 83.3% healing with no significant changes in EPT responses, and no significant changes in root lengths, while significant changes in root widths (p < 0.05) and root apex widths (p < 0.001) were found over time. Twenty-five percent of patients and 33% of parents felt that there were changes in tooth colour following RET over time.
Conclusion
Within the limitations of this study, traumatised teeth treated using RET showed no significant root lengthening, however, acceptable periapical healing, slow thickening of root dentinal walls, and rapid development of apical closure were evident over a period of 43 months. Using Portland cement and omitting minocycline, did not eliminate crown colour change following RET
Conformal Ricci collineations of static spherically symmetric spacetimes
Conformal Ricci collineations of static spherically symmetric spacetimes are
studied. The general form of the vector fields generating conformal Ricci
collineations is found when the Ricci tensor is non-degenerate, in which case
the number of independent conformal Ricci collineations is \emph{fifteen}; the
maximum number for 4-dimensional manifolds. In the degenerate case it is found
that the static spherically symmetric spacetimes always have an infinite number
of conformal Ricci collineations. Some examples are provided which admit
non-trivial conformal Ricci collineations, and perfect fluid source of the
matter
Spacelike Ricci Inheritance Vectors in a Model of String Cloud and String Fluid Stress Tensor
We study the consequences of the existence of spacelike Ricci inheritance
vectors (SpRIVs) parallel to for model of string cloud and string fluid
stress tensor in the context of general relativity. Necessary and sufficient
conditions are derived for a spacetime with a model of string cloud and string
fluid stress tensor to admit a SpRIV and a SpRIV which is also a spacelike
conformal Killing vector (SpCKV). Also, some results are obtained.Comment: 11 page
SN 2013ej - A type IIL supernova with weak signs of interaction
We present optical photometric and spectroscopic observations of supernova
2013ej. It is one of the brightest type II supernovae exploded in a nearby
( Mpc) galaxy NGC 628. The light curve characteristics are similar to
type II SNe, but with a relatively shorter ( day) and steeper ( mag (100 d) in V) plateau phase. The SN shows a large drop of
2.4 mag in V band brightness during plateau to nebular transition. The absolute
ultraviolet (UV) light curves are identical to SN 2012aw, showing a similar UV
plateau trend extending up to 85 days. The radioactive Ni mass estimated
from the tail luminosity is M which is significantly lower
than typical type IIP SNe. The characteristics of spectral features and
evolution of line velocities indicate that SN 2013ej is a type II event.
However, light curve characteristics and some spectroscopic features provide
strong support in classifying it as a type IIL event. A detailed SYNOW
modelling of spectra indicates the presence of some high velocity components in
H and H profiles, implying possible ejecta-CSM interaction. The
nebular phase spectrum shows an unusual notch in the H emission which
may indicate bipolar distribution of Ni. Modelling of the bolometric
light curve yields a progenitor mass of M and a radius of R, with a total explosion energy of
erg.Comment: 19 pages, 19 figures, 6 tables. Accepted for publication in Ap
Competing mechanisms and scaling laws for carbon nanotube scission by ultrasonication
Dispersion of carbon nanotubes (CNTs) into liquids typically
requires ultrasonication to exfoliate individuals CNTs from bundles.
Experiments show that CNT length drops with sonication time (or
energy) as a power law t?m. Yet the breakage mechanism is not
well understood, and the experimentally reported power law
exponent m ranges from approximately 0.2 to 0.5. Here we simulate
the motion of CNTs around cavitating bubbles by coupling
Brownian dynamics with the Rayleigh-Plesset equation. We observe
that, during bubble growth, CNTs align tangentially to the
bubble surface. Surprisingly, we find two dynamical regimes during
the collapse: shorter CNTs align radially, longer ones buckle.We
compute the phase diagram for CNT collapse dynamics as a function
of CNT length, stiffness, and initial distance from the bubble
nuclei and determine the transition from aligning to buckling. We
conclude that, depending on their length, CNTs can break due to
either buckling or stretching. These two mechanisms yield different
power laws for the length decay (0.25 and 0.5, respectively), reconciling
the apparent discrepancy in the experimental data
On global models for isolated rotating axisymmetric charged bodies; uniqueness of the exterior field
A relatively recent study by Mars and Senovilla provided us with a uniqueness
result for the exterior vacuum gravitational field generated by an isolated
distribution of matter in axial rotation in equilibrium in General Relativity.
The generalisation to exterior electrovacuum gravitational fields, to include
charged rotating objects, is presented here.Comment: LaTeX, 21 pages, uses iopart styl
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