Vertical Laser Lines Research Articles

Can the Treatment of Dental Malocclusions Affect the Posture in Children?

The aim of this study was to investigate whether the treatment of the dental malocclusions can affect the postural attitude in children. Sixty patients aged 9-12 years in mixed dentition were enrolled. The patients underwent an orthodontic evaluation for dental malocclusion and a postural examination by means of a vertical laser line (VLL) and a stabilometric-baropodometric platform. The children were treated with a functional appliance according to the type of malocclusion for two years. The position of the head and of the atlanto-occipital joint (C0-C1) respects to the VLL, the typologies of podalic support and the distribution of the body weight on the feet were evaluated before and after the orthodontic treatment. A significant correction of the position of the head, with a physiological extension of C0-C1, a significant improvement of the typology of podalic support and a homogeneous distribution of the body weight on the feet were observed after the treatment of the malocclusions. Conclusion; From our results, the treatment of dental malocclusion can contribute to ameliorate the postural attitude in children.

A method for volumetric retinal tissue oxygen tension imaging

ABSTRACTPurpose: Inadequate retinal oxygenation occurs in many vision-threatening retinal diseases, including diabetic retinopathy, retinal vascular occlusions, and age-related macular degeneration. Therefore, techniques that assess retinal oxygenation are necessary to understand retinal physiology in health and disease. The purpose of the current study is to report a method for the three-dimensional (3D) imaging of retinal tissue oxygen tension (tPO2) in rats.Methods: Imaging was performed in Long Evans pigmented rats under systemic normoxia (N = 6) or hypoxia (N = 3). A vertical laser line was horizontally scanned on the retina and a series of optical section phase-delayed phosphorescence images were acquired. From these images, phosphorescence volumes at each phase delay were constructed and a 3D retinal tPO2 volume was generated. Retinal tPO2 volumes were quantitatively analyzed by generating retinal depth profiles of mean tPO2 (MtPO2) and the spatial variation of tPO2 (SVtPO2). The effects of systemic condition (normoxia/hypoxia) and retinal depth on MtPO2 and SVtPO2 were determined by mixed linear model.Results: Each 3D retinal tPO2 volume was approximately 500 × 750 × 200 μm (horizontal × vertical × depth) and consisted of 45 en face tPO2 images through the retinal depth. MtPO2 at the chorioretinal interface was significantly correlated with systemic arterial oxygen tension (P = 0.007; N = 9). There were significant effects of both systemic condition and retinal depth on MtPO2 and SVtPO2, such that both were lower under hypoxia than normoxia and higher in the outer retina than inner retina (P < 0.001).Conclusion: For the first time, 3D imaging of retinal tPO2 was demonstrated, with potential future application for assessment of physiological alterations in animal models of retinal diseases.

Visualization of the light field of multifocal intraocular lenses using a dual wavelength approach

PurposeTo implement a setup which allows simultaneous visualization of the far and near distance light field of multifocal intraocular lenses (MIOL) with two different wavelengths.MethodsWe used two different laser systems (532 nm and 405 nm) in junction with Powell lenses to create vertical laser lines. One laser line was collimated to simulate far distance imaging while the second laser line was diverging simulating near distance imaging at approximately 0.3 m distance. The MIOL was placed in a glass cuvette filled with balanced saline solution which was doped with two different fluorophores. The fluorophores were chosen to have a large Stokes shift and good separation between their excitation and emission bands. Image acquisition was performed with a slit lamp bio microscope and a digital single reflex camera. We investigated three different IOL types: a bifocal MIOL, a trifocal MIOL and an extended depth of focus IOL.ResultsWe found that Propidium iodide and Fluorescein were appropriate fluorophores. Propidium iodide was excited at 532 nm and showed a red fluorescence while Fluorescein was excited at 405 nm showing the green fluorescence. Both lasers required a high power of approximately 30 mW in order to create a visible fluorescent reaction in the cuvette. All three MIOL types provided a good separation between far and near distance light. The regions of overlapping light fields were visible as yellow fluorescence.ConclusionsIn contrast to the previously published setups using a single wavelength with collimated excitation light and axially separated far and near distance foci the current setup allows superposition of the far and near distance foci which is more realistic compared to the situation in the eye. The dual wavelength approach enables an easy optical separation of far and near distance light.

In Vivo Measurement of Pediatric Vocal Fold Motion Using Structured Light Laser Projection

The aim of the study was to present the development of a miniature structured light laser projection endoscope and to quantify vocal fold length and vibratory features related to impact stress of the pediatric glottis using high-speed imaging. The custom-developed laser projection system consists of a green laser with a 4-mm diameter optics module at the tip of the endoscope, projecting 20 vertical laser lines on the glottis. Measurements of absolute phonatory vocal fold length, membranous vocal fold length, peak amplitude, amplitude-to-length ratio, average closing velocity, and impact velocity were obtained in five children (6-9 years), two adult male and three adult female participants without voice disorders, and one child (10 years) with bilateral vocal fold nodules during modal phonation. Independent measurements made on the glottal length of a vocal fold phantom demonstrated a 0.13mm bias error with a standard deviation of 0.23mm, indicating adequate precision and accuracy for measuring vocal fold structures and displacement. First, invivo measurements of amplitude-to-length ratio, peak closing velocity, and impact velocity during phonation in pediatric population and a child with vocal fold nodules are reported. The proposed laser projection system can be used to obtain invivo measurements of absolute length and vibratory features in children and adults. Children have large amplitude-to-length ratio compared with typically developing adults, whereas nodules result in larger peak amplitude, amplitude-to-length ratio, average closing velocity, and impact velocity compared with typically developing children.

Biomass pyrolysis in a heated-grid reactor: Visualization of carbon monoxide and formaldehyde using Laser-Induced Fluorescence

The development of improved biomass pyrolysis models is vital for more accurate modelling and design of biomass conversion equipment. Such improved models must be based on reliable experimental data: biomass should be pyrolyzed at high heating rates and the reaction products should be measured using an on-line, non-intrusive method. Therefore, a heated grid reactor with heating rate of 300–600 K/s was used to study pyrolysis of biomass at temperatures in the range of 500–700 °C. The formation of formaldehyde and carbon monoxide from wood at high heating rates was successfully visualized using Laser-Induced Fluorescence (LIF). A thin vertical laser line or sheet was present directly above the biomass lying on the heated grid. Two-photon excitation at 230 nm was applied to induce fluorescence of carbon monoxide present in the volatiles, whereas excitation of formaldehyde was done at 355 nm. Visualization of these compounds shows that the release rises strongly with temperature; this typically happens on a timescale in the order of seconds. In principle, the method described allows for the determination of truly primary products. Future research is recommended, aimed at quantifying the concentrations measured by LIF. Care must be taken to calibrate for quenching of the fluorescence signal. Avoiding secondary reactions taking place in the gas phase is another experimental challenge.

New Method for Surveying and Mapping Architectural Plane In-House with Laser Reticule Images

Surveying and mapping the appearance of architecture plane is a supporting technology of historic buildings. To meet the need of plan survey in-house, a new close-range photogrammetry method was developed by laser reticule system. With the help of the system, two parallel level lines and eight vertical laser lines can be marked on the surface of inner walls. When the relationship between the distance from a vertical line and the length of the same line on an image picture is studied, the spatial location of room corners and some characteristic points on the images can be determined. Based on the photogrammetry and plane table operation method, architectural plane mapping can be done easily following a set of laser reticule images which were shot in situ closed by a non-metric digital camera. More details of historic buildings can be recorded on drawing sheets and images monogamy at the same time by using the proposed method, which are the basic information for the structural analysis of historic buildings.