Porcelain Surface Roughness, Color and Gloss Changes after Orthodontic Bonding

The purpose of this study was to evaluate the alteration in surface characteristics after orthodontic debonding of two types of porcelain systems commonly used in prosthetic dentistry. For this purpose, porcelain specimens were fabricated from low-fusing (n = 20) and high-fusing (n = 20) porcelain. The baseline surface roughness, color, and gloss were evaluated using profilometry, color shade index, and gloss study. All specimens were bonded with brackets and debonded using a testing machine at a rate of 0.1 mm/minute crosshead speed. The porcelain surfaces were polished using a 12-fluted carbide composite removal bur (low-fusing, n = 20; high-fusing, n = 20). In addition, half of each porcelain group was further polished using a series of Sof-Lex discs (low-fusing, n = 10; high-fusing, n = 10). The postdebond porcelain surface characteristics roughness, color, and gloss were reevaluated and compared with baseline measurements. The results were analyzed with two-way analysis of variance and Tukey multiple comparisons test, with porcelain type (low-fusing or high-fusing) and polishing protocol (carbide bur or carbide bur and discs) serving as discriminate variables at α = 0.05 level of significance. Bonding and debonding increased all roughness parameters tested; however, no change was revealed between the two polishing protocols. Similarly, gloss and color index changes were significantly altered after resin grinding, regardless of the polishing method used. No difference was identified between the two porcelain types with respect to roughness, color index, or gloss. Orthodontic bonding alters the porcelain surfaces, and postdebond polishing does not restore the surface to the prebond state

External Development: Turning Problems into Opportunities

9 pages

External Development: Turning Problems into Opportunities

9 pages

Treatment of HIV-associated cryptococcal meningitis in South Africa: The case for amphotericin B over conventional dose fluconazole for initial therapy

Cryptococcal meningitis is a major cause of morbidity and mortality in African AIDS patients, accounting for between 13% and 17% of deaths in Ugandan HIV-infected individuals(1,2) and 44% of deaths in a cohort of HIV-seropositive South African miners.(3) This burden of disease is a result of high incidence, especially in southern and East Africa, and high acute mortality.(4,6) In much of Africa, fluconazole rather than amphotericin B was, and still is, widely used as initial therapy, for a variety of reasons. These include the availability of fluconazole through free access programmes and in generic form, and the attractiveness of an easy to. use, safe oral regimen over a difficult to administer intravenous drug with significant side-effects, requiring inpatient admission and close laboratory monitoring. In addition, in the absence of antiretroviral therapy, treatment of cryptococcal meningitis has in the recent past been palliative rather than curative, reducing the rationale for more aggressive therapy, if this is associated with increased side-effects. However, what data there are suggest that outcomes with fluconazole at conventional dosage (up to 400 mg/d) as initial therapy are poor. In addition, the cost of amphotericin B, previously considerable in South Africa, has been reduced! More importantly, increasing access to antiretroviral therapy (ART) now means that the long-term prognosis of patients with cryptococcal meningitis is good, provided they survive the acute infection.(8) We summarise the evidence that a factor contributing to high acute mortality in cryptococcal meningitis is the inadequacy of fluconazole at up to 400 mg/d as an induction regimen, and present the case for initial treatment with amphotericin B in South Africa, where feasible

Treatment of HIV-associated cryptococcal meningitis in South Africa: The case for amphotericin B over conventional dose fluconazole for initial therapy

Cryptococcal meningitis is a major cause of morbidity and mortality in African AIDS patients, accounting for between 13% and 17% of deaths in Ugandan HIV-infected individuals1,2 and 44% of deaths in a cohort of HIV-seropositive South African miners.3 This burden of disease is a result of high incidence, especially in southern and East Africa, and high acute mortality.4-6 In much of Africa, fluconazole rather than amphotericin B was, and still is, widely used as initial therapy, for a variety of reasons. These include the availability of fluconazole through free access programmes and in generic form, and the attractiveness of an easy to use, safe oral regimen over a difficult to administer intravenous drug with significant side-effects, requiring inpatient admission and close laboratory monitoring. In addition, in the absence of antiretroviral therapy, treatment of cryptococcal meningitis has in the recent past been palliative rather than curative, reducing the rationale for more aggressive therapy, if this is associated with increased side-effects. However, what data there are suggest that outcomes with fluconazole at conventional dosage (up to 400 mg/d) as initial therapy are poor. In addition, the cost of amphotericin B, previously considerable in South Africa, has been reduced.7 More importantly, increasing access to antiretroviral therapy (ART) now means that the long-term prognosis of patients with cryptococcal meningitis is good, provided they survive the acute infection.8 We summarise the evidence that a factor contributing to high acute mortality in cryptococcal meningitis is the inadequacy of fluconazole at up to 400 mg/d as an induction regimen, and present the case for initial treatment with amphotericin B in South Africa, where feasible. Southern African Journal of HIV Medicine Vol. 8 (3) 2007: pp. 36-3

3D Reconstruction of the Density Field: An SVD Approach to Weak Lensing Tomography

We present a new method for constructing three-dimensional mass maps from gravitational lensing shear data. We solve the lensing inversion problem using truncation of singular values (within the context of generalized least squares estimation) without a priori assumptions about the statistical nature of the signal. This singular value framework allows a quantitative comparison between different filtering methods: we evaluate our method beside the previously explored Wiener filter approaches. Our method yields near-optimal angular resolution of the lensing reconstruction and allows cluster sized halos to be de-blended robustly. It allows for mass reconstructions which are 2-3 orders-of-magnitude faster than the Wiener filter approach; in particular, we estimate that an all-sky reconstruction with arcminute resolution could be performed on a time-scale of hours. We find however that linear, non-parametric reconstructions have a fundamental limitation in the resolution achieved in the redshift direction.Comment: 11 pages, 6 figures. Accepted for publication in Ap

On the Structure of the Observable Algebra of QCD on the Lattice

The structure of the observable algebra ${\mathfrak O}_{\Lambda}$ of lattice QCD in the Hamiltonian approach is investigated. As was shown earlier, ${\mathfrak O}_{\Lambda}$ is isomorphic to the tensor product of a gluonic $C^{*}$-subalgebra, built from gauge fields and a hadronic subalgebra constructed from gauge invariant combinations of quark fields. The gluonic component is isomorphic to a standard CCR algebra over the group manifold SU(3). The structure of the hadronic part, as presented in terms of a number of generators and relations, is studied in detail. It is shown that its irreducible representations are classified by triality. Using this, it is proved that the hadronic algebra is isomorphic to the commutant of the triality operator in the enveloping algebra of the Lie super algebra ${\rm sl(1/n)}$ (factorized by a certain ideal).Comment: 33 page