Computer Simulation of Tooth Mobility using Varying Material Properties

Tooth mobility is the major cause of stress on a tooth implant or partial denture and often results in the damage of the device. For many prosthetic devices like dental bridges, a partial denture used for a person who is missing a tooth to give the appearance and function of a tooth, mobility can cause up to double the amount of stress in comparison to a fixed model. Creating a computer simulation of tooth mobility using Finite Element Analysis allows one to understand and predict this movement in order to improve future dental prosthetic devices. The main cause of tooth mobility within the mouth is the periodontal ligament (PDL). This ligament is a soft biological tissue that surrounds the roots of teeth. The tooth moves when a force like mastication, or chewing, causes the ligament to deform. This deformation is due to the small Young’s Modulus of the ligament. The Young’s Modulus determines the stiffness of a material. In the case of the PDL, the Young’s Modulus is sometimes noted to be 30,000 times smaller than that of dentin, this is the material that makes up the majority of the tooth, and of the alveolar bone, this is the bone in which the tooth lies. The deformation of the PDL is also due to the viscoelastic nature of the ligament. The major elastic component of the ligament is collagen, this material allows the PDL to stretch to a certain limit, and the major viscous component of the ligament is the interstitial fluid between the cells, this allows the material to have a fluid-like nature (4)

Superheavy nuclei in a chiral hadronic model

Superheavy nuclei are investigated in a nonlinear chiral SU(3)-model. The proton number Z=120 and neutron numbers of N=172, 184 and 198 are predicted to be magic. The charge distributions and alpha-decay chains hint towards a hollow stucture

Nuclei, superheavy nuclei, and hypermatter in a chiral SU(3) model

A model based on chiral SU(3)-symmetry in nonlinear realisation is used for the investigation of nuclei, superheavy nuclei, hypernuclei and multistrange nuclear objects (so called MEMOs). The model works very well in the case of nuclei and hypernuclei with one Lambda-particle and rules out MEMOs. Basic observables which are known for nuclei and hypernuclei are reproduced satisfactorily. The model predicts Z=120 and N=172, 184 and 198 as the next shell closures in the region of superheavy nuclei. The calculations have been performed in self-consistent relativistic mean field approximation assuming spherical symmetry. The parameters were adapted to known nuclei

Chiral model for dense, hot and strange hadronic matter

Introduction: Until now it is not possible to determine the equation of state (EOS) of hadronic matter from QCD. One succesfully applied alternative way to describe the hadronic world at high densities and temperatures are effective models like the RMF-models [1], where the relevant degrees of freedom are baryons and mesons instead of quarks and gluons. Since approximate chiral symmetry is an essential feature of QCD, it should be a useful concept for building and restricting e ective models. It has been shown [2,3] that effective sigma-omega models including SU(2) chiral symmetry are able to obtain a reasonable description of nuclear matter and finite nuclei. Recently [4] we have shown that an extended SU(3) × SU(3) chiral sigma-omega model is able to describe nuclear matter ground state properties, vacuum properties and finite nuclei satisfactorily. This model includes the lowest SU(3) multiplets of the baryons (octet and decuplet[5]), the spin-0 and the spin-1 mesons as the relevant degrees of freedom. Here we will discuss the predictions of this model for dense, hot, and strange hadronic matter

The dusty heart of nearby active galaxies. I. High-spatial resolution mid-IR spectro-photometry of Seyfert galaxies

We present 8-13 micron imaging and spectroscopy of 9 type 1 and 10 type 2 AGN obtained with the VLT/VISIR instrument at spatial resolution <100 pc. The emission from the host galaxy sources is resolved out in most cases. The silicate absorption features are moderately deep and emission features are shallow. We compare the mid-IR luminosities to AGN luminosity tracers and found that the mid-IR radiation is emitted quite isotropically. In two cases, IC5063 and MCG-3-34-64, we find evidence for extended dust emission in the narrow-line region. We confirm the correlation between observed silicate feature strength and Hydrogen column density recently found in Spitzer data. In a further step, our 3D clumpy torus model has been used to interpret the data. We show that the strength of the silicate feature and the mid-IR spectral index can be used to get reasonable constraints on the dust distribution in the torus. The mid-IR spectral index, alpha, is almost exclusively determined by the radial dust distribution power-law index, a, and the silicate feature depth is mostly depending on the average number of clouds, N0, along an equatorial line-of-sight and the torus inclination. A comparison of model predictions to our type 1 and type 2 AGN reveals typical average parameters a=-1.0+/-0.5 and N0=5-8, which means that the radial dust distribution is rather shallow. As a proof-of-concept of this method, we compared the model parameters derived from alpha and the silicate feature to more detailed studies of IR SEDs and interferometry and found that the constraints on a and N0 are consistent. Finally, we might have found evidence that the radial structure of the torus changes from low to high AGN luminosities towards steeper dust distributions, and we discuss implications for the IR size-luminosity relation. (abridged)Comment: 22 pages, 13 figues, 6 tables; Accepted for publication in A&A; Note that this is the second submitted paper from the series, but we changed paper order. This one will be referred to as paper I, the previously submitted arXiv:0909.4539 will become paper I

Determination of the packing fraction in photonic glass using synchrotron radiation nanotomography

Photonic glass is a material class that can be used as photonic broadband reflectors, for example in the infrared regime as thermal barrier coating films. Photonic properties such as the reflectivity depend on the ordering and material packing fraction over the complete film thickness of up to 100 μm. Nanotomography allows acquiring these key parameters throughout the sample volume at the required resolution in a non-destructive way. By performing a nanotomography measurement at the PETRA III beamline P05 on a photonic glass film, the packing fraction throughout the complete sample thickness was analyzed. The results showed a packing fraction significantly smaller than the expected random close packing giving important information for improving the fabrication and processing methods of photonic glass material in the future

The Subak in Diaspora: Balinese Farmers and the Subak in South Sulawesi

The subak has a long history as an irrigators’ institution on Bali. It has also spread across Indonesia along with Balinese farmers who were resettled by colonial and post-colonial governments or who have migrated spontaneously since colonial times. While subaks have been much researched in Bali itself, little is known about subaks outside Bali. Luwu District in South Sulawesi is one of the areas where thousands of Balinese families settled in the last four decades. Based on research in this transmigration area, this paper analyzes the emergence and development of the subak in relation to the development of irrigation infrastructure of a state-built irrigation system. A comparison between two Balinese settlements in the same system shows that differences in infrastructural and managerial conditions and arrangements between parts of the irrigation system were major determinants of the institutional space allowed for the subak and ways in which the subaks developed

Short Enantioselective Total Synthesis of Tatanan A and 3-epi-Tatanan A Using Assembly-Line Synthesis

Short and highly stereoselective total syntheses of the sesquilignan natural product tatanan A and its C3 epimer are described. An assembly-line synthesis approach, using iterative lithiation–borylation reactions, was applied to install the three contiguous stereocenters with high enantio- and diastereoselectivity. One of the stereocenters was installed using a configurationally labile lithiated primary benzyl benzoate, resulting in high levels of substrate-controlled (undesired) diastereoselectivity. However, reversal of selectivity was achieved by using a novel diastereoselective Matteson homologation. Stereospecific alkynylation of a hindered secondary benzylic boronic ester enabled completion of the synthesis in a total of eight steps

An XMM-Newton spectral survey of 12 micron selected galaxies. II. Implications for AGN selection and unification

We present a multi-waveband analysis of a 126 galaxy sub-sample of the 12 micron galaxy sample (12MGS), for which we have carried out a detailed X-ray spectral analysis of in a previous paper. We present optical activity classes and we characterise these by their X-ray, 12 um and [OIII] luminosities and by their X-ray spectral properties. Our most interesting results are: Seyfert (Sy) 1s and Sy 2s show significantly different LX distributions from each other; Sy 2s with a detection of an HBLR show a significantly higher LX than those without a detection; Sy 1s also present a significantly different L(12um) distribution from both Sy1.2-1.9s and Sy 2s; the Sy 2 fraction decreases towards high LX; X-ray indications of AGN power agree well with the optical classifications; There is X-ray evidence for the presence of an AGN in 17% of HII/AGN composites and 40% of LINERs; we advocate the use of a LX >10^41 erg/s in the X-ray selection of AGN, which gives a contamination rate of only 3% from star-forming galaxies; Sy 1s and Sy 2 have the same intrinsic {\Gamma}; in 24% of cases the absorption measured in X-rays does not correspond directly with that implied in the optical band from the visibility of the BLRs; the obscured fraction in AGN is a strong function of LX peaking at 10^42 erg/s; The average obscured and Compton thick fractions for this sample are 62\pm5% and 20\pm4% respectively, which are higher than hard X-ray and optically selected samples; we assess the use of the T ratio (FX/F[OIII]) for selecting Compton thick candidates. We conclude here that this quantity can often be unreliable due uncertainties in the extinction corrections to the [OIII] flux. These results have important impacts on AGN selection and unification and the results from the 12MGS are particularly useful as a local analogue to z=1 24 um samples.Comment: 27 pages, 12 figures, accepted for publication by MNRA