1,371 research outputs found
Irredundant Triangular Decomposition
Triangular decomposition is a classic, widely used and well-developed way to
represent algebraic varieties with many applications. In particular, there
exist sharp degree bounds for a single triangular set in terms of intrinsic
data of the variety it represents, and powerful randomized algorithms for
computing triangular decompositions using Hensel lifting in the
zero-dimensional case and for irreducible varieties. However, in the general
case, most of the algorithms computing triangular decompositions produce
embedded components, which makes it impossible to directly apply the intrinsic
degree bounds. This, in turn, is an obstacle for efficiently applying Hensel
lifting due to the higher degrees of the output polynomials and the lower
probability of success. In this paper, we give an algorithm to compute an
irredundant triangular decomposition of an arbitrary algebraic set defined
by a set of polynomials in C[x_1, x_2, ..., x_n]. Using this irredundant
triangular decomposition, we were able to give intrinsic degree bounds for the
polynomials appearing in the triangular sets and apply Hensel lifting
techniques. Our decomposition algorithm is randomized, and we analyze the
probability of success
Effect of Long-Term Cycling Load for Abutment Screw Fixation in Implant Prosthodontics
The aim of this in vitro study was to use rotational tests on commercially available abutment screws to evaluate their potential for preload generation and to follow changes in torque by using newer fixation geometry on the interface of the implant-abutment screw joint. Five identical implant/abutment assemblies were chosen from each of the following systems: external hex with standard abutment and Replace with TorgTite screw (Nobel Biocare), Camlog universal abutment (Altatec Biotechnologies), DenTi internal hex (Dentimplant Ltd. Szentes, Hungary), straight abutment with internal antirotational element (Uniplant, Sinalisal, Budapest). Wax patterns of the upper premolar were performed and then cast from nickel-chrome alloy and full crown castings were cemented on abutments. In a test machine the magnitude and time of chewing function was predefined by using the desired force pattern. Each specimen
was stressed for cycles equivalent to an intaoral load of 5 months or longer timescale. In the static test greater loss in torques was calculated for standard Branemark and Replace screw joints.
Assuming that the optimum proportion is the same when we calculate loosening versus tightening torque we obtained a decrease between 0.70-0.59 for Replace and Branemark abutments and a more moderate loss of between 0.90-0.84 for the other systems investigated. The ten month equivalent cycling test produced a loosening torque of 16-17 Ncm for Branemark and Replace abutments. Similar decrease in torque was not found for the
other three systems. It was concluded that different approach in achievement of necessary mechanical integration can be seen in implant systems, although a reliable loosening torque could be measured after a longer time scale
Effect of Long-Term Cycling Load for Abutment Screw Fixation in Implant Prosthodontics
The aim of this in vitro study was to use rotational tests on commercially available abutment screws to evaluate their potential for preload generation and to follow changes in torque by using newer fixation geometry on the interface of the implant-abutment screw joint. Five identical implant/abutment assemblies were chosen from each of the following systems: external hex with standard abutment and Replace with TorgTite screw (Nobel Biocare), Camlog universal abutment (Altatec Biotechnologies), DenTi internal hex (Dentimplant Ltd. Szentes, Hungary), straight abutment with internal antirotational element (Uniplant, Sinalisal, Budapest). Wax patterns of the upper premolar were performed and then cast from nickel-chrome alloy and full crown castings were cemented on abutments. In a test machine the magnitude and time of chewing function was predefined by using the desired force pattern. Each specimen
was stressed for cycles equivalent to an intaoral load of 5 months or longer timescale. In the static test greater loss in torques was calculated for standard Branemark and Replace screw joints.
Assuming that the optimum proportion is the same when we calculate loosening versus tightening torque we obtained a decrease between 0.70-0.59 for Replace and Branemark abutments and a more moderate loss of between 0.90-0.84 for the other systems investigated. The ten month equivalent cycling test produced a loosening torque of 16-17 Ncm for Branemark and Replace abutments. Similar decrease in torque was not found for the
other three systems. It was concluded that different approach in achievement of necessary mechanical integration can be seen in implant systems, although a reliable loosening torque could be measured after a longer time scale
8Be cluster emission versus alpha evaporation in 28Si + 12C
The possible occurence of highly deformed configurations in the Ca
di-nuclear system formed in the Si + C reaction is investigated
by analyzing the spectra of emitted light charged particles. Both inclusive and
exclusive measurements of the heavy fragments (A 10) and their
associated light charged particles (protons and particles) have been
made at the IReS Strasbourg {\sc VIVITRON} Tandem facility at bombarding
energies of (Si) = 112 MeV and 180 MeV by using the {\sc
ICARE} charged particle multidetector array. The energy spectra, velocity
distributions, in-plane and out-of-plane angular correlations of light charged
particles are compared to statistical-model calculations using a consistent set
of parameters with spin-dependent level densities. This spin dependence
approach suggests the onset of large nuclear deformation in Ca at high
spin. This conclusion might be connected with the recent observation of
superdeformed bands in the Ca nucleus. The analysis of
particles in coincidence with S fragments suggests a surprisingly strong
Be cluster emission of a binary nature.Comment: 39 pages 15 figure
Search for emission of unstable Be clusters from hot Ca and Ni nuclei
The possible occurence of highly deformed configurations is investigated in
the Ca and Ni di-nuclear systems as formed in the Si +
C and Si + Si reactions, respectively, by using the
properties of emitted light charged particles. Inclusive as well as exclusive
data of the heavy fragments (A 6) and their associated light charged
particles (p, d, t, and -particles) have been collected at the IReS
Strasbourg VIVITRON Tandem facility with two bombarding energies
Si) = 112 and 180 MeV by using the ICARE charged particle
multidetector array, which consists of nearly 40 telescopes. The measured
energy spectra, velocity distributions, in-plane and out-of-plane angular
correlations are analysed by Monte Carlo CASCADE statistical-model calculations
using a consistent set of parameters with spin-dependent level densities.
Although significant deformation effects at high spin are needed, the remaining
disagreement observed in the Si + C reaction for the S
evaporation residue suggests an unexpected large unstable Be cluster
emission of a binary nature.Comment: 13 pages latex, 9 eps figures. Paper presented at the XXXIX
International Winter Meeting on Nuclear Physics, Bormio(Italy) January 22-27,
2001 (to be published at Ricerca Scientifica ed Educazione Permanente
Dissipative collisions in O + Al at E=116 MeV
The inclusive energy distributions of fragments (3Z7) emitted in
the reaction O + Al at 116 MeV have been measured in
the angular range = 15 - 115. A non-linear
optimisation procedure using multiple Gaussian distribution functions has been
proposed to extract the fusion-fission and deep inelastic components of the
fragment emission from the experimental data. The angular distributions of the
fragments, thus obtained, from the deep inelastic component are found to fall
off faster than those from the fusion-fission component, indicating shorter
life times of the emitting di-nuclear systems. The life times of the
intermediate di-nuclear configurations have been estimated using a diffractive
Regge-pole model. The life times thus extracted (
Sec.) are found to decrease with the increase in the fragment charge. Optimum
Q-values are also found to increase with increasing charge transfer i.e. with
the decrease in fragment charge.Comment: 9 pages, 4 figures, 1 tabl
Ethnic differences and heterogeneity in genetic and metabolic makeup contributing to nonalcoholic fatty liver disease
Obesity is the most prevalent noncommunicable disease in the 21st century, associated with triglyceride deposition in hepatocytes leading to nonalcoholic fatty liver disease (NAFLD). NAFLD is now present in around a third of the world's population. Epidemiological studies have concluded that ethnicity plays a role in complications and treatment response. However, definitive correlations of ethnicity with NAFLD are thoroughly under-reported. A comprehensive review was conducted on ethnic variation in NAFLD patients and its potential role as a crucial effector in complications and treatment response. The highest NAFLD prevalence is observed in Hispanic populations, exhibiting a worse disease progression. In contrast, African-Caribbeans exhibit the lowest risk, with less severe steatosis and inflammation, lower levels of triglycerides, and less metabolic derangement, but conversely higher prevalence of insulin resistance. The prevalence of NAFLD in Asian cohorts is under-reported, although reaching epidemic proportions in these populations. The most well-documented NAFLD patient population is that of Caucasian ethnicity, especially from the US. The relative paucity of available literature suggests there is a vital need for more large-scale multi-ethnic clinical cohort studies to determine the incidence of NAFLD within ethnic groups. This would improve therapy and drug development, as well as help identify candidate gene mutations which may differ within the population based on ethnic background
Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets
An experimental overview of reactions induced by the stable, but weakly-bound
nuclei 6Li, 7Li and 9Be, and by the exotic, halo nuclei 6He, 8B, 11Be and 17F
on medium-mass targets, such as 58Ni, 59Co or 64Zn, is presented. Existing data
on elastic scattering, total reaction cross sections, fusion processes, breakup
and transfer channels are discussed in the framework of a CDCC approach taking
into account the breakup degree of freedom.Comment: 7 pages, 6 figures, Invited Talk given by C. Beck to the 10th
International Conference on Nucleus-Nucleus Collisions, August 16-21, 2009
Beijing, China; Paper submitted to the NN2009 Proceedings, Nuclear Physics A
(to be published
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