Oral Health Behaviour of Nine-Year-Old Children and Their Parents in Sarajevo

The oral health situation in Bosnia and Herzegovina is among the worst in Europe. We investigated the oral health behaviour of primary schoolchildren and their parents in Sarajevo. This was an anonymous cross-sectional survey among third-grade schoolchildren and their parents’ oral health habits in Canton Sarajevo. Cluster random sampling yielded a representative sample from all the public schools in Canton Sarajevo in 2019. The survey targeted a total of 441 children and 365 parents. Two thirds (66.5%) of the children reported brushing their teeth twice daily, and almost half of them failed to use fluoride toothpaste daily. Girls brushed their teeth significantly more often than did the boys (74% vs. 58%, p = 0.004). Children living in residential areas of middle and high socioeconomic status (SES) reported better oral health habits than did those living in areas of low SES. Our study showed that Sarajevo children’s oral health habits were poor. One-third of the nine-year-olds failed to brush their teeth according to recommendations, and almost half of them failed to use fluoride toothpaste daily. Improving the children’s oral health in the future will urgently require national oral health promotion and prevention programmes.publishedVersio

Levenberg-Marquardt algorithm for acousto-electric tomography based on the complete electrode model

The inverse problem in Acousto-Electric tomography concerns the reconstruction of the electric conductivity in a domain from knowledge of the power density function in the interior of the body. This interior power density results from currents prescribed at boundary electrodes (and can be obtained through electro-static boundary measurements together with auxiliary acoustic measurement. In Electrical Impedance Tomography, the complete electrode model is known to be the most accurate model for the forward modelling. In this paper, the reconstruction problem of Acousto-Electric tomography is posed using the (smooth) complete electrode model, and a Levenberg-Marquardt iteration is formulated in appropriate function spaces. This results in a system of partial differential equations to be solved in each iteration. To increase the computational efficiency and stability, a strategy based on both the complete electrode model and the continuum model with Dirichlet boundary condition is proposed. The system of equations is implemented numerically for a two dimensional scenario and the algorithm is tested on two different numerical phantoms, a heart and lung model and a human brain model. Several numerical experiments are carried out confirming the feasibility, accuracy and stability of the methods

Enhanced 2D-image upconversion using solid-state lasers

Based on enhanced upconversion, we demonstrate a highly efficient method for converting a full image from one part of the electromagnetic spectrum into a new desired wavelength region. By illuminating a metal transmission mask with a 765 nm Gaussian beam to create an image and subsequently focusing the image inside a nonlinear PPKTP crystal located in the high intra-cavity field of a 1342 nm solid-state Nd:YVO4 laser, an upconverted image at 488 nm is generated. We have experimentally achieved an upconversion efficiency of 40% under CW conditions. The proposed technique can be further adapted for high efficiency mid-infrared image upconversion where direct and fast detection is difficult or impossible to perform with existing detector technologies

Oral Health Behaviour of Nine-Year-Old Children and Their Parents in Sarajevo

The oral health situation in Bosnia and Herzegovina is among the worst in Europe. We investigated the oral health behaviour of primary schoolchildren and their parents in Sarajevo. This was an anonymous cross-sectional survey among third-grade schoolchildren and their parents’ oral health habits in Canton Sarajevo. Cluster random sampling yielded a representative sample from all the public schools in Canton Sarajevo in 2019. The survey targeted a total of 441 children and 365 parents. Two thirds (66.5%) of the children reported brushing their teeth twice daily, and almost half of them failed to use fluoride toothpaste daily. Girls brushed their teeth significantly more often than did the boys (74% vs. 58%, p = 0.004). Children living in residential areas of middle and high socioeconomic status (SES) reported better oral health habits than did those living in areas of low SES. Our study showed that Sarajevo children’s oral health habits were poor. One-third of the nine-year-olds failed to brush their teeth according to recommendations, and almost half of them failed to use fluoride toothpaste daily. Improving the children’s oral health in the future will urgently require national oral health promotion and prevention programmes.</p

Singly-resonant sum frequency generation of visible light in a semiconductor disk laser

In this paper a generic approach for visible light generation is presented. It is based on sum frequency generation between a semiconductor disk laser and a solid-state laser, where the frequency mixing is achieved within the cavity of the semiconductor disk laser using a singlepass of the solid-state laser light. This exploits the good beam quality and high intra-cavity power present in the semiconductor disk laser to achieve high conversion efficiency. Combining sum frequency mixing and semiconductor disk lasers in this manner allows in principle for generation of any wavelength within the visible spectrum, by appropriate choice of semiconductor material and single-pass laser wavelength

A New Approach for Designing Orthogonal Wavelets for Multicarrier Applications

yesThe Daubechies, coiflet and symlet wavelets, with properties of orthogonal wavelets are suitable for multicarrier transmission over band-limited channels. It has been shown that similar wavelets can be constructed by Lagrange approximation interpolation. In this work and using established wavelet design algorithms, it is shown that ideal filters can be approximated to construct new orthogonal wavelets. These new wavelets, in terms of BER behave slightly better than the wavelets mentioned above, and much better than biorthogonal wavelets, in multipath channels with additive white Gaussian noise (AWGN). It is shown that the construction, which uses a simple simultaneous solution to obtain the wavelet filters from the ideal filters based on established wavelet design algorithms, is simple and can easily be reproduced

Incoherent optical frequency domain reflectometry for distributed thermal sensing

This thesis reports the main results from an investigation of a fibre-optic distributed temperature sensor based on spontaneous Raman scattering. The technique used for spatial resolving is the incoherent optical frequency domain reflectometry, where a pump laser is sine-modulated with a stepwise increasing frequency, after which the inverse Fourier transform is applied to the signal from the backscattered light. This technique is compared with the more conventional optical time domain reflectometry, where a short pulse is sent through the fibre, and the location of the scattering section is determined by the time difference from the emission to the detection of light. A temperature sensor with a range of 2-4km comprising a step-index multi-mode fibre and a high-power 980nm pump laser existed prior to the start of the PhD study. In this study, a sensor range of approximately 10km, and a spatial resolution of order 1m is strived to be achieved. These demands are attempted to be reached by employing a low-loss telecom-grade transmission single-mode fibre or an alternative fibre as the sensing fibre, and a pump laser operating in the low-loss region of silica. An analysis of the optical module comprising a pump laser, optical filters, optical fibre and photo-detectors are presented. Limitations, trade-offs and optimisation processes are described for setups having different specifications with respect to range, resolution and accuracy. The analysis is conducted using computer simulation programs developed and implemented in Matlab. The computer model is calibrated and tested, and describes the entire system with high precision. Noise analysis and digital processing of the detected signal are discussed as well. An equation describing the standard deviation of the measured temperature is derived for the device, and shows the dependency of the accuracy on measurement time, resolution, range, attenuation and detector parameters. Temperature measurements on 7.8km low-loss graded-index multi-mode fibre and 14km standard single-mode fibre with a spatial resolution varying from 0.5m to 6m are given as representative examples of the achieved accuracy (0.5 degrees C to 5 degrees C) and range, with measurement time of a few minutes. Measurements on 25km were conducted as well to demonstrate this possibility; with a short measurement time it was not possible to obtain a reasonable accuracy though. In addition to the Raman based temperature sensor, a quasi-distributed fibre-optic temperature and strain sensor based on an array of fibre Bragg gratings interrogated by a tuneable laser is also developed and analysed. This type of fibre-sensor is particularly suitable for strain monitoring on large concrete constructions such as bridges. The sensor is built and tested in a field trial on a bridge, and the estimated accuracy of around 2 mu times epsilon is achieved