Phase-Induced Amplitude Apodization of Telescope Pupils for Extrasolar Terrestrial Planet Imaging

In this paper, an alternative to the classical pupil apodization techniques (use of an amplitude pupil mask) is proposed. It is shown that an apodized pupil suitable for imaging of Extrasolar planets can be obtained by reflection of an unapodized flat wavefront on 2 mirrors. By carefully choosing the shape of these 2 mirrors, it is possible to obtain a contrast better than 10^{9} at a distance smaller than 2 \lambda/d from the optical axis. Because this technique preserves both the angular resolution and light gathering capabilities of the unapodized pupil, it allows efficient detection of terrestrial extrasolar planets with a 1.5m telescope in the visible.Comment: 9 pages, 9 figures, Accepted for publication in A&A. Postscript file with full-resolution figures can be found at http://www.naoj.org/staff/guyon/publications/PIAA.p

Environmental risks for children oral health in Low Danube region

The study was aimed to assess the environmental risks for children oral health in Low Danube region.Material and methods. The study was conducted in 2011-2021. Information on the state of drinking water, the level of environmental safety of food, qualitative and quantitative composition of food was obtained from the reports of territorial institutions of the sanitary-epidemiological service of Odessa region. Actual nutrition was assessed using standard questionnaires. The assessment of the level of environmental and hygienic safety was based on the recommendations of the EPA. Statistical processing was performed by methods of analysis of variance and correlation using specialized software Statistica 10.0.Results. Excessive carbohydrate intake and excessive nitrate load are the main environmental risk factors for dental pathology in children living in the Danube region. Qualitative composition of diets plays a bigger role than mineral composition of drinking water.Conclusion. 1. Drinking water of suboptimal mineral composition was consumed by 41.7% of people, high content of refined carbohydrates was inherent in the diets of 63.0% of surveyed children.2. Children’s diet is characterized with subdeficiency of B vitamins, excessive consumption of refined carbohydrates and a significant nitrate load

Population Study of the Variation in Monochromatic Aberrations of the Normal Human Eye Over the Central Visual Field

Abstract We present data analysis for ocular aberrations of 60 normal eyes measured with a Hartmann-Shack (HS) wavefront sensor (WFS). Aberration measurements were made on-axis and at 5 degree field angles in the nasal, inferior, temporal and superior semi-meridians. Particular attention is given to aberration distributions and possible strategies for aberration correction are discussed. A versatile HS WFS was designed and constructed with features of simultaneous pupil centre determination, off-axis capability, real-time data displays, and efficient lenslet sampling orientation. The subject alignment is achieved by the use of a parallel channel that is recombined with the sensing channel to simultaneously image the eye and the HS spots onto a single CCD. The pupil centre is determined using this image of the eye (iris edge), rather than the HS spots. The optical design includes a square lenslet array positioned with its diagonals aligned with the most typical principal astigmatic meridians of the eye. This favourable orientation helps to enlarge the dynamic range of the WFS. The telecentric re-imaging of the HS spots increases the robustness of the system to defocus in the event of CCD misalignment

N=1 Supergravity Chaotic Inflation in the Braneworld Scenario

We study a N=1 Supergravity chaotic inflationary model, in the context of the braneworld scenario. It is shown that successful inflation and reheating consistent with phenomenological constraints can be achieved via the new terms in the Friedmann equation arising from brane physics. Interestingly, the model satisfies observational bounds with sub-Planckian field values, implying that chaotic inflation on the brane is free from the well known difficulties associated with the presence of higher order non-renormalizable terms in the superpotential. A bound on the mass scale of the fifth dimension, M_5 \gsim 1.3 \times 10^{-6} M_P, is obtained from the requirement that the reheating temperature be higher than the temperature of the electroweak phase transition.Comment: 5 pages, 1 Table, Revtex

Damages Identification in the Cantilever-based on the Parameters of the Natural Oscillations

An approach to parametric identification of damages such as cracks in the rod cantilever construction is described. The identification method is based on analysis of shapes of the natural oscillations. The analytic modelling is performed in the Maple software on the base of the Euler-Bernoulli hypothesis. Crack is modelled by an elastic bending element. Transverse oscillations of the rod are considered. We take into account first four eigen modes of the oscillations. Parameters of amplitude, curvature and angle of bends of the waveforms are analysed. It was established that damage location is revealed by ‘kink’ on corresponding curves of the waveforms. The parameters of oscillation shapes are sensitive to the crack parameters in different degree. The novelty of the approach consists in that the identification procedure is divided into two stages: (a) it is determined the crack location, and (b) it is determined the crack size. Based on analytical modelling, an example of determination of dependence of the crack parameters on its size in the cantilever rod is presented. Study of features of the waveforms during identification of the fracture parameters shows that the features found in the form of ‘kinks’ and local extreme a of the angle between the tangent and curvature of waveforms for different modes of bending oscillations, define the crack location in cantilever. They can serve as one of diagnostic signs of crack identification and allow us to determine its location.