Validation Of A Cariogenic Biofilm Model To Evaluate The Effect Of Fluoride On Enamel And Root Dentine Demineralization

Due to gingival recession both enamel and root dentine are at risk of developing caries. Both tissues are exposed to a similar environment, however there is not a validated model to evaluate the effect of fluoride on these dental substrates simultaneously. Hence, this study aimed to validate a caries model to evaluate the effect of fluoride to prevent demineralization on enamel and root-dentine. Streptococcus mutans UA159 biofilms were formed on saliva-coated bovine enamel and root dentine slabs (n = 12 per group) mounted in the same well of culture plates. The biofilms were exposed 8x/day to 10% sucrose and treated 2x/day with fluoridated solutions containing 0, 150, 450, or 1,350 ppm F; thus, simulating the use of low to high fluoride concentration toothpastes. The pH values of the culture medium was monitored 2x/day as a biofilm acidogenicity indicator. After 96 h, biofilms were collected for fluoride concentration analysis. The percentage of surface hardness loss (% SHL) was calculated for slabs. The fluoride uptake by the enamel and dentine was also determined. The model showed a dose-response because the biofilm and fluoride uptake increased and % SHL decreased at increasing fluoride concentrations (p < 0.05). Fluoride in the biofilm formed on dentine and fluoride uptake by dentine were higher than those for enamel. With the same fluoride concentration treatment, the percentage of reduction of demineralization was lower for dentine than for enamel. In conclusion, the model was validated in terms of a dose-response effect of fluoride on enamel and root dentine. Furthermore, the findings support the clinical data, suggesting that higher fluoride concentrations are necessary to control caries of root dentine than of enamel.111Foundation of UNICAMP (FUNCAMP) [4252

Melnikov theory to all orders and Puiseux series for subharmonic solutions

We study the problem of subharmonic bifurcations for analytic systems in the plane with perturbations depending periodically on time, in the case in which we only assume that the subharmonic Melnikov function has at least one zero. If the order of zero is odd, then there is always at least one subharmonic solution, whereas if the order is even in general other conditions have to be assumed to guarantee the existence of subharmonic solutions. Even when such solutions exist, in general they are not analytic in the perturbation parameter. We show that they are analytic in a fractional power of the perturbation parameter. To obtain a fully constructive algorithm which allows us not only to prove existence but also to obtain bounds on the radius of analyticity and to approximate the solutions within any fixed accuracy, we need further assumptions. The method we use to construct the solution -- when this is possible -- is based on a combination of the Newton-Puiseux algorithm and the tree formalism. This leads to a graphical representation of the solution in terms of diagrams. Finally, if the subharmonic Melnikov function is identically zero, we show that it is possible to introduce higher order generalisations, for which the same kind of analysis can be carried out.Comment: 30 pages, 6 figure

Yangian Symmetry for the Tree Amplituhedron

17 pages, 4 figures; v2: extended discussion of results, minor typos corrected, version published in Journal of Physics ATree-level scattering amplitudes in planar N=4 super Yang-Mills are known to be Yangian-invariant. It has been shown that integrability allows to obtain a general, explicit method to find such invariants. The uplifting of this result to the amplituhedron construction has been an important open problem. In this paper, with the help of methods proper to integrable theories, we successfully fill this gap and clarify the meaning of Yangian invariance for the tree-level amplituhedron. In particular, we construct amplituhedron volume forms from an underlying spin chain. As a by-product of this construction, we also propose a novel on-shell diagrammatics for the amplituhedron.Peer reviewe

The First Detailed Abundances for M giants in Baade's Window from Infrared Spectroscopy

We report the first abundance analysis of 14 M giant stars in the Galactic bulge, based on R=25,000 infrared spectroscopy (1.5-1.8um) using NIRSPEC at the Keck II telescope. Because some of the bulge M giants reach high luminosities and have very late spectral type, it has been suggested that they are the progeny of only the most metal rich bulge stars, or possibly members of a younger bulge population. We find the iron abundance and composition of the M giants are similar to those of the K giants that have abundances determined from optical high resolution spectroscopy: =-0.190 +/- 0.020 with a 1-sigma dispersion of 0.08 +/- 0.015. Comparing our bulge M giants to a control sample of local disk M giants in the Solar vicinity, we find the bulge stars are enhanced in alpha elements at the level of +0.3 dex relative to the Solar composition stars, consistent with other studies of bulge globular clusters and field stars. This small sample shows no dependence of spectral type on metallicity, nor is there any indication that the M giants are the evolved members of a subset of the bulge population endowed with special characteristics such as relative youth or high metallicity. We also find low 12C/13C < 10, confirming the prsence of extra-mixing processes during the red gaint phase of evolutionComment: 19 pages, 7 figures, accepted for publication in the Astrophysical Journa

MITO measurements of the Sunyaev-Zeldovich Effect in the Coma cluster of galaxies

We have measured the Sunyaev-Zeldovich effect towards the Coma cluster (A1656) with the MITO experiment, a 2.6-m telescope equipped with a 4-channel 17 arcminute (FWHM) photometer. Measurements at frequency bands 143+/-15, 214+/-15, 272+/-16 and 353+/-13 GHz, were made during 120 drift scans of Coma. We describe the observations and data analysis that involved extraction of the S-Z signal by employing a spatial and spectral de-correlation scheme to remove a dominant atmospheric component. The deduced values of the thermal S-Z effect in the first three bands are DT_{0} = -179+/-38,-33+/-81,170+/-35 microKelvin in the cluster center. The corresponding optical depth, tau=(4.1+/-0.9) 10^{-3}, is consistent (within errors) with both the value from a previous low frequency S-Z measurement, and the value predicted from the X-ray deduced gas parameters.Comment: Ap.J.Letters accepted, 4 pages, 2 figure

Red Giant stars in the Large Magellanic Cloud clusters

We present deep J,H,Ks photometry and accurate Color Magnitude Diagrams down to K ~18.5, for a sample of 13 globular clusters in the Large Magellanic Cloud. This data set combined with the previous sample of 6 clusters published by our group gives the opportunity to study the properties of giant stars in clusters with different ages (ranging from ~80 Myr up to ~3.5 Gyr). Quantitative estimates of star population ratios (by number and luminosity) in the Asymptotic Giant Branch, the Red Giant Branch and the He-clump, have been obtained and compared with theoretical models in the framework of probing the so-called phase transitions. The AGB contribution to the total luminosity starts to be significant at ~200 Myr and reaches its maximum at ~5-600 Myr, when the RGB Phase Transition is starting. At ~900 Myr the full developing of an extended and well populated RGB has been completed. Both the occurrence of the AGB and RGB Phase Transitions are sharp events, lasting a few hundreds Myr only. These empirical results agree very well with the theoretical predictions of simple stellar population models based on canonical tracks and the fuel-consumption approach.Comment: 32 pages, 11 figures, accepted to Ap

A behavioral genetic study of humor styles in an Australian sample

The present study investigated the extent to which individual differences in humor styles are attributable to genetic and/or environmental factors in an Australian sample. Participants were 934 same-sex pairs of adult twins from the Australian Twin Registry (546 monozygotic pairs, 388 dizygotic pairs) who completed the Humor Styles Questionnaire (HSQ). The HSQ measures four distinct styles of humor - affiliative, self-enhancing, aggressive, and self-defeating. Results revealed that additive genetic and non-shared environmental factors accounted for the variance in all four humor styles, thus replicating results previously obtained in a sample of twins from the United Kingdom. However, a study conducted with a U.S. sample produced different results and we interpret these findings in terms of cross-cultural differences in humor

The intermediate-age globular cluster NGC 1783 in the Large Magellanic Cloud

We present Hubble Space Telescope ACS deep photometry of the intermediate-age globular cluster NGC 1783 in the Large Magellanic Cloud. By using this photometric dataset, we have determined the degree of ellipticity of the cluster ($\epsilon$=0.14$\pm$0.03) and the radial density profile. This profile is well reproduced by a standard King model with an extended core (r_c=24.5'') and a low concentration (c=1.16), indicating that the cluster has not experienced the collapse of the core. We also derived the cluster age, by using the Pisa Evolutionary Library (PEL) isochrones, with three different amount of overshooting (namely, $\Lambda_{os}$=0.0, 0.10 and 0.25). From the comparison of the observed Color-Magnitude Diagram (CMD) and Main Sequence (MS) Luminosity Function (LF) with the theoretical isochrones and LFs, we find that only models with the inclusion of some overshooting ($\Lambda_{os}$=0.10-0.25) are able to reproduce the observables. By using the magnitude difference $\delta V_{SGB}^{He-Cl}=0.90$ between the mean level of the He-clump and the flat region of the SGB, we derive an age $\tau$=1.4$\pm$0.2 Gyr.Comment: Accepted to publication by A

Metabolic Factors and Their Influence on the Clinical Course and Response to HCV Treatment

Nowadays, direct-acting antivirals (DAA) have been used for hepatitis C virus (HCV) treatment leading to cure in 90–95% of non-cirrhotic patients depending on genotype, treatment experience, and regimen used. It was observed rates of antiviral response above 90% in compensated cirrhotic patients that should be treated for long time and/or ribavirin may be required. Metabolic syndrome, obesity, and insulin resistance are increasing worldwide and further contribute to hepatic steatosis and have long been recognized as a cause of lipid deposition in the liver. These factors affect the rate of antiviral response to interferon-based therapy, but it seems not impact DAA treatment. The effect of HCV eradication on hepatic steatosis and progression to fibrosis, cirrhosis, and hepatocellular carcinoma warrants further study in the era of direct-acting antivirals. Other factors that could be related to increase liver damage are vitamin D and associated polymorphisms. Patients with low concentration of total vitamin D [25(OH)D] presented high degree of fibrosis and high values of total cholesterol and triglycerides. In this chapter, we review the challenges and metabolic pathology associated with HCV infection and, discuss the influence of some metabolic factors which can cause liver damage

A near-infrared spectroscopic screening of the red giant populations in omega Centauri

Near-infrared spectra of 21 giants in omega Centauri, spanning the whole range of metallicities observed in this cluster, are presented. This work is part of a coordinated photometric and spectroscopic campaign in the optical and in the infrared, aimed at studying the complex stellar population of omega Centauri and understanding its formation and chemical evolution. By analyzing the several CO and OH molecular bands and atomic lines in the spectra of the selected giants, metal abundances and abundance ratios have been obtained. The existence of three major metallicity regimes at [Fe/H]=-1.6, -1.2 and [Fe/H]<-0.5 has been confirmed. The most metal-rich stars in our sample show a lower (if any) alpha-enhancement when compared to the more metal-poor components, suggesting that they should have formed in a medium significantly polluted by type Ia supernova ejecta. Isotopic carbon abundances have been also inferred, providing an average 13C/12C=4, which clearly indicates that extra-mixing processes occurred in the stellar interiors during the ascent on the Red Giant Branch.Comment: 22 pages, 7 .ps figures. aastex. Accepted for pubilcation in the Astrophysical Journa