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Sample records for population difference grating

  1. Dynamic population gratings in rare-earth-doped optical fibres

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, Serguei [Optics Department, CICESE, km.107 carr. Tijuana-Ensenada, Ensenada, 22860, BC (Mexico)], E-mail: steps@cicese.mx

    2008-11-21

    Dynamic Bragg gratings can be recorded in rare-earth (e.g. Er, Yb) doped optical fibres by two counter-propagating mutually coherent laser waves via local saturation of the fibre optical absorption or gain (in optically pumped fibres). Typical recording cw light power needed for efficient grating formation is of sub-mW-mW scale which results in characteristic recording/erasure times of 10-0.1 ms. This review paper discusses fundamental aspects of the population grating formation, their basic properties, relating wave-mixing processes and also considers different applications of these dynamic gratings in single-frequency fibre lasers, tunable filters, optical fibre sensors and adaptive interferometry.

  2. Dynamic population gratings in rare-earth-doped optical fibres

    International Nuclear Information System (INIS)

    Stepanov, Serguei

    2008-01-01

    Dynamic Bragg gratings can be recorded in rare-earth (e.g. Er, Yb) doped optical fibres by two counter-propagating mutually coherent laser waves via local saturation of the fibre optical absorption or gain (in optically pumped fibres). Typical recording cw light power needed for efficient grating formation is of sub-mW-mW scale which results in characteristic recording/erasure times of 10-0.1 ms. This review paper discusses fundamental aspects of the population grating formation, their basic properties, relating wave-mixing processes and also considers different applications of these dynamic gratings in single-frequency fibre lasers, tunable filters, optical fibre sensors and adaptive interferometry.

  3. Phasor analysis of binary diffraction gratings with different fill factors

    International Nuclear Information System (INIS)

    MartInez, Antonio; Sanchez-Lopez, Ma del Mar; Moreno, Ignacio

    2007-01-01

    In this work, we present a simple analysis of binary diffraction gratings with different slit widths relative to the grating period. The analysis is based on a simple phasor technique directly derived from the Huygens principle. By introducing a slit phasor and a grating phasor, the intensity of the diffracted orders and the grating's resolving power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors

  4. Phasor analysis of binary diffraction gratings with different fill factors

    Energy Technology Data Exchange (ETDEWEB)

    MartInez, Antonio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain); Sanchez-Lopez, Ma del Mar [Instituto de BioingenierIa y Departamento de Fisica y Arquitectura de Computadores, Universidad Miguel Hernandez, 03202 Elche (Spain); Moreno, Ignacio [Departamento de Ciencia de Materiales, Optica y TecnologIa Electronica, Universidad Miguel Hernandez, 03202 Elche (Spain)

    2007-09-11

    In this work, we present a simple analysis of binary diffraction gratings with different slit widths relative to the grating period. The analysis is based on a simple phasor technique directly derived from the Huygens principle. By introducing a slit phasor and a grating phasor, the intensity of the diffracted orders and the grating's resolving power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors.

  5. Feasibility of Fiber Bragg Grating and Long-Period Fiber Grating Sensors under Different Environmental Conditions

    Directory of Open Access Journals (Sweden)

    Jian-Neng Wang

    2010-11-01

    Full Text Available This paper presents the feasibility of utilizing fiber Bragg grating (FBG and long-period fiber grating (LPFG sensors for nondestructive evaluation (NDE of infrastructures using Portland cement concretes and asphalt mixtures for temperature, strain, and liquid-level monitoring. The use of hybrid FBG and LPFG sensors is aimed at utilizing the advantages of two kinds of fiber grating to implement NDE for monitoring strains or displacements, temperatures, and water-levels of infrastructures such as bridges, pavements, or reservoirs for under different environmental conditions. Temperature fluctuation and stability tests were examined using FBG and LPFG sensors bonded on the surface of asphalt and concrete specimens. Random walk coefficient (RWC and bias stability (BS were used for the first time to indicate the stability performance of fiber grating sensors. The random walk coefficients of temperature variations between FBG (or LPFG sensor and a thermocouple were found in the range of −0.7499 °C/ to −1.3548 °C/. In addition, the bias stability for temperature variations, during the fluctuation and stability tests with FBG (or LPFG sensors were within the range of 0.01 °C/h with a 15–18 h time cluster to 0.09 °C/h with a 3–4 h time cluster. This shows that the performance of FBG or LPFG sensors is comparable with that of conventional high-resolution thermocouple sensors under rugged conditions. The strain measurement for infrastructure materials was conducted using a packaged FBG sensor bonded on the surface of an asphalt specimen under indirect tensile loading conditions. A finite element modeling (FEM was applied to compare experimental results of indirect tensile FBG strain measurements. For a comparative analysis between experiment and simulation, the FEM numerical results agreed with those from FBG strain measurements. The results of the liquid-level sensing tests show the LPFG-based sensor could discriminate five stationary liquid

  6. Psychophysical and physiological responses to gratings with luminance and chromatic components of different spatial frequencies.

    Science.gov (United States)

    Cooper, Bonnie; Sun, Hao; Lee, Barry B

    2012-02-01

    Gratings that contain luminance and chromatic components of different spatial frequencies were used to study the segregation of signals in luminance and chromatic pathways. Psychophysical detection and discrimination thresholds to these compound gratings, with luminance and chromatic components of the one either half or double the spatial frequency of the other, were measured in human observers. Spatial frequency tuning curves for detection of compound gratings followed the envelope of those for luminance and chromatic gratings. Different grating types were discriminable at detection threshold. Fourier analysis of physiological responses of macaque retinal ganglion cells to compound waveforms showed chromatic information to be restricted to the parvocellular pathway and luminance information to the magnocellular pathway. Taken together, the human psychophysical and macaque physiological data support the strict segregation of luminance and chromatic information in independent channels, with the magnocellular and parvocellular pathways, respectively, serving as likely the physiological substrates. © 2012 Optical Society of America

  7. Pulsed recording of anisotropy and holographic polarization gratings in azo-polymethacrylates with different molecular architectures

    DEFF Research Database (Denmark)

    Forcén, Patricia; Oriol, Luis; Alcala, Rafael

    2008-01-01

    Recording of anisotropy and holographic polarization gratings using 532 nm, 4 ns light pulses has been carried out in thin films of polymers with the same azobenzene content (20 wt %) and different molecular architectures. Random and block copolymers comprising azobenzene and methylmethacrylate (...

  8. Fast and stable gratings inscription in POFs made of different materials with pulsed 248 nm KrF laser

    DEFF Research Database (Denmark)

    Marques, C. A.F.; Min, R.; Leal, A.

    2018-01-01

    This paper presents fiber Bragg grating (FBG) inscription with a pulsed 248 nm UV KrF laser in polymer optical fibers (POFs) made of different polymers, namely polymethyl methacrylate (PMMA), cyclic-olefin polymer and co-polymer, and Polycarbonate. The inscribed gratings and the corresponding...... inscription parameters are compared with grating inscribed in POFs made of the aforementioned materials but with the hitherto most used laser for inscription, which is a continuous wave 325 nm UV HeCd laser. Results show a reduction of the inscription time of at least 16 times. The maximum time reduction...... is more than 130 times. In addition, a reflectivity and a bandwidth close to or higher than the ones with the 325 nm laser were obtained. The polymer optical fiber Bragg gratings (POFBGs) inscribed with the 248 nm laser setup present high stability with small variations in their central wavelength...

  9. Birefringence Bragg Binary (3B) grating, quasi-Bragg grating and immersion gratings

    Science.gov (United States)

    Ebizuka, Noboru; Morita, Shin-ya; Yamagata, Yutaka; Sasaki, Minoru; Bianco, Andorea; Tanabe, Ayano; Hashimoto, Nobuyuki; Hirahara, Yasuhiro; Aoki, Wako

    2014-07-01

    A volume phase holographic (VPH) grating achieves high angular dispersion and very high diffraction efficiency for the first diffraction order and for S or P polarization. However the VPH grating could not achieve high diffraction efficiency for non-polarized light at a large diffraction angle because properties of diffraction efficiencies for S and P polarizations are different. Furthermore diffraction efficiency of the VPH grating extinguishes toward a higher diffraction order. A birefringence binary Bragg (3B) grating is a thick transmission grating with optically anisotropic material such as lithium niobate or liquid crystal. The 3B grating achieves diffraction efficiency up to 100% for non-polarized light by tuning of refractive indices for S and P polarizations, even in higher diffraction orders. We fabricated 3B grating with liquid crystal and evaluated the performance of the liquid crystal grating. A quasi-Bragg (QB) grating, which consists long rectangle mirrors aligned in parallel precisely such as a window shade, also achieves high diffraction efficiency toward higher orders. We fabricated QB grating by laminating of silica glass substrates and glued by pressure fusion of gold films. A quasi-Bragg immersion (QBI) grating has smooth mirror hypotenuse and reflector array inside the hypotenuse, instead of step-like grooves of a conventional immersion grating. An incident beam of the QBI grating reflects obliquely at a reflector, then reflects vertically at the mirror surface and reflects again at the same reflector. We are going to fabricate QBI gratings by laminating of mirror plates as similar to fabrication of the QB grating. We will also fabricate silicon and germanium immersion gratings with conventional step-like grooves by means of the latest diamond machining methods. We introduce characteristics and performance of these gratings.

  10. Simulation of subwavelength metallic gratings using a new implementation of the recursive convolution finite-difference time-domain algorithm.

    Science.gov (United States)

    Banerjee, Saswatee; Hoshino, Tetsuya; Cole, James B

    2008-08-01

    We introduce a new implementation of the finite-difference time-domain (FDTD) algorithm with recursive convolution (RC) for first-order Drude metals. We implemented RC for both Maxwell's equations for light polarized in the plane of incidence (TM mode) and the wave equation for light polarized normal to the plane of incidence (TE mode). We computed the Drude parameters at each wavelength using the measured value of the dielectric constant as a function of the spatial and temporal discretization to ensure both the accuracy of the material model and algorithm stability. For the TE mode, where Maxwell's equations reduce to the wave equation (even in a region of nonuniform permittivity) we introduced a wave equation formulation of RC-FDTD. This greatly reduces the computational cost. We used our methods to compute the diffraction characteristics of metallic gratings in the visible wavelength band and compared our results with frequency-domain calculations.

  11. Contributing factors to VEP grating acuity deficit and inter-ocular acuity difference in children with cerebral visual impairment.

    Science.gov (United States)

    Cavascan, Nívea Nunes; Salomão, Solange Rios; Sacai, Paula Yuri; Pereira, Josenilson Martins; Rocha, Daniel Martins; Berezovsky, Adriana

    2014-04-01

    To investigate contributing factors to visual evoked potential (VEP) grating acuity deficit (GAD) and inter-ocular acuity difference (IAD) measured by sweep-VEPs in children with cerebral visual impairment (CVI). VEP GAD was calculated for the better acuity eye by subtracting acuity thresholds from mean normal VEP grating acuity according to norms from our own laboratory. Deficits were categorized as mild (0.17 ≤ deficit children (66 males-57 %) with ages ranging from 1.2 to 166.5 months (median = 17.7) was examined. VEP GAD ranged from 0.17 to 1.28 log units (mean = 0.68 ± 0.27; median = 0.71), and it was mild in 23 (20 %) children, moderate in 32 (28 %) and severe in 60 (52 %). Severe deficit was significantly associated with older age and anti-seizure drug therapy. IAD ranged from 0 to 0.49 log units (mean = 0.06 ± 0.08; median = 0.04) and was acceptable in 96 (83 %) children. Children with strabismus and nystagmus had IAD significantly larger compared to children with orthoposition. In a large cohort of children with CVI, variable severity of VEP GAD was found, with more than half of the children with severe deficits. Older children and those under anti-seizure therapy were at higher risk for larger deficits. Strabismus and nystagmus provided larger IADs. These results should be taken into account on the clinical management of children with this leading cause of bilateral visual impairment.

  12. Multi-objective optimization of cooling air distributions of grate cooler with different clinker particles diameters and air chambers by genetic algorithm

    International Nuclear Information System (INIS)

    Shao, Wei; Cui, Zheng; Cheng, Lin

    2017-01-01

    Highlights: • A multi-objective optimization model of air distributions of grate cooler by genetic algorithm is proposed. • Optimal air distributions of different conditions are obtained and validated by measurements. • The most economic average diameters of clinker particles is 0.02 m. • The most economic amount of air chambers is 9. - Abstract: The paper proposes a multi-objective optimization model of cooling air distributions of grate cooler in cement plant based on convective heat transfer principle and entropy generation minimization analysis. The heat transfer and flow models of clinker cooling process are brought out at first. Then the modified entropy generation numbers caused by heat transfer and viscous dissipation are considered as objective functions respectively which are optimized by genetic algorithm simultaneously. The design variables are superficial velocities of air chambers and thicknesses of clinker layer on different grate plates. The model is verified by a set of Pareto optimal solutions and scattered distributions of design variables. Sensitive analysis of average diameters of clinker particles and amount of air chambers are carried out based on the optimization model. The optimal cooling air distributions are compared by heat recovered, energy consumption of cooling fans and heat efficiency of grate cooler. And all of them are selected from the Pareto optimal solutions based on energy consumption of cooling fans minimization. The results show that the most effective and economic average diameter of clinker particles is 0.02 m and the amount of air chambers is 9.

  13. A single-longitudinal-mode Brillouin fiber laser passively stabilized at the pump resonance frequency with a dynamic population inversion grating

    International Nuclear Information System (INIS)

    Spirin, V V; López-Mercado, C A; Kinet, D; Mégret, P; Fotiadi, A A; Zolotovskiy, I O

    2013-01-01

    We demonstrate a single-longitudinal-mode Brillouin ring fiber laser passively stabilized at the resonance frequency with a 1.7 m section that is an unpumped polarization-maintaining erbium-doped fiber. The two coupled all-fiber Fabry–Perot interferometers that comprise the cavity, in combination with the dynamical population inversion gratings self-induced in the active fiber, provide adaptive pump-mode selection and Stokes wave generation at the same time. The laser is shown to emit a single-frequency Stokes wave with a linewidth narrower than 100 Hz. (letter)

  14. Optical Fiber Grating based Sensors

    DEFF Research Database (Denmark)

    Michelsen, Susanne

    2003-01-01

    In this thesis differenct optical fiber gratings are used for sensor purposes. If a fiber with a core concentricity error (CCE) is used, a directional dependent bend sensor can be produced. The CCE direction can be determined by means of diffraction. This makes it possible to produce long......-period gratings in a fiber with a CCE direction parallel or perpendicular to the writing direction. The maximal bending sensitivity is independent on the writing direction, but the detailed bending response is different in the two cases. A temperature and strain sensor, based on a long-period grating and two...... sampled gratings, was produced and investigated. It is based on the different temperature and strain response of these gratings. Both a transfer matrix method and an overlap calculation is performed to explain the sensor response. Another type of sensor is based on tuning and modulation of a laser...

  15. Fiber Optic Bragg Gratings

    National Research Council Canada - National Science Library

    Battiato, James

    1998-01-01

    Coupled mode theory was used to model reflection fiber gratings. The effects of experimental parameters on grating characteristics were modeled for both uniform and non-uniform grating profiles using this approach...

  16. Access Platforms for Offshore Wind Turbines Using Gratings

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.

    2008-01-01

    The paper deals with forces generated by a stationary jet on different types of gratings and a solid plate. The force reduction factors for the different gratings compared to the solid plate mainly depend on the porosity of the gratings, but the geometry of the grating is also of some importance........ The derived reduction factors are expected to be applicable to design of offshore wind turbine access platforms with gratings where slamming also is an important factor....

  17. Curved VPH gratings for novel spectrographs

    Science.gov (United States)

    Clemens, J. Christopher; O'Donoghue, Darragh; Dunlap, Bart H.

    2014-07-01

    The introduction of volume phase holographic (VPH) gratings into astronomy over a decade ago opened new possibilities for instrument designers. In this paper we describe an extension of VPH grating technology that will have applications in astronomy and beyond: curved VPH gratings. These devices can disperse light while simultaneously correcting aberrations. We have designed and manufactured two different kinds of convex VPH grating prototypes for use in off-axis reflecting spectrographs. One type functions in transmission and the other in reflection, enabling Offnerstyle spectrographs with the high-efficiency and low-cost advantages of VPH gratings. We will discuss the design process and the tools required for modelling these gratings along with the recording layout and process steps required to fabricate them. We will present performance data for the first convex VPH grating produced for an astronomical spectrograph.

  18. Geometrical optics modeling of the grating-slit test.

    Science.gov (United States)

    Liang, Chao-Wen; Sasian, Jose

    2007-02-19

    A novel optical testing method termed the grating-slit test is discussed. This test uses a grating and a slit, as in the Ronchi test, but the grating-slit test is different in that the grating is used as the incoherent illuminating object instead of the spatial filter. The slit is located at the plane of the image of a sinusoidal intensity grating. An insightful geometrical-optics model for the grating-slit test is presented and the fringe contrast ratio with respect to the slit width and object-grating period is obtained. The concept of spatial bucket integration is used to obtain the fringe contrast ratio.

  19. Delayed discrimination of spatial frequency for gratings of different orientation: behavioral and fMRI evidence for low-level perceptual memory stores in early visual cortex.

    Science.gov (United States)

    Baumann, Oliver; Endestad, Tor; Magnussen, Svein; Greenlee, Mark W

    2008-07-01

    The concept of perceptual memory refers to the neural and cognitive processes underlying the storage of specific stimulus features such as spatial frequency, orientation, shape, contrast, and color. Psychophysical studies of perceptual memory indicate that observers can retain visual information about the spatial frequency of Gabor patterns independent of the orientation with which they are presented. Compared to discrimination of gratings with the same orientation, reaction times to orthogonally oriented gratings, however, increase suggesting additional processing. Using event-related fMRI we examined the pattern of neural activation evoked when subjects discriminated the spatial frequency of Gabors presented with the same or orthogonal orientation. Blood-oxygen level dependent BOLD fMRI revealed significantly elevated bilateral activity in visual areas (V1, V2) when the gratings to be compared had an orthogonal orientation, compared to when they had the same orientation. These findings suggest that a change in an irrelevant stimulus dimension requires additional processing in primary and secondary visual areas. The finding that the task-irrelevant stimulus property (orientation) had no significant effect on the prefrontal and intraparietal cortex supports a model of working memory in which discrimination and retention of basic stimulus dimensions is based on low-level perceptual memory stores that are located at an early stage in the visual process. Our findings suggest that accessing different stores requires time and has higher metabolic costs.

  20. Characterization of Early Age Curing and Shrinkage of Metakaolin-Based Inorganic Binders with Different Rheological Behavior by Fiber Bragg Grating Sensors.

    Science.gov (United States)

    Palumbo, Giovanna; Iadicicco, Agostino; Messina, Francesco; Ferone, Claudio; Campopiano, Stefania; Cioffi, Raffaele; Colangelo, Francesco

    2017-12-22

    This paper reports results related to early age temperature and shrinkage measurements by means fiber Bragg gratings (FBGs), which were embedded in geopolymer matrices. The sensors were properly packaged in order to discriminate between different shrinkage behavior and temperature development. Geopolymer systems based on metakaolin were investigated, which dealt with different commercial aluminosilicate precursors and siliceous filler contents. The proposed measuring system will allow us to control, in a very accurate way, the early age phases of the binding systems made by metakaolin geopolymer. A series of experiments were conducted on different compositions; moreover, rheological issues related to the proposed experimental method were also assessed.

  1. Waveguide silicon nitride grating coupler

    Science.gov (United States)

    Litvik, Jan; Dolnak, Ivan; Dado, Milan

    2016-12-01

    Grating couplers are one of the most used elements for coupling of light between optical fibers and photonic integrated components. Silicon-on-insulator platform provides strong confinement of light and allows high integration. In this work, using simulations we have designed a broadband silicon nitride surface grating coupler. The Fourier-eigenmode expansion and finite difference time domain methods are utilized in design optimization of grating coupler structure. The fully, single etch step grating coupler is based on a standard silicon-on-insulator wafer with 0.55 μm waveguide Si3N4 layer. The optimized structure at 1550 nm wavelength yields a peak coupling efficiency -2.6635 dB (54.16%) with a 1-dB bandwidth up to 80 nm. It is promising way for low-cost fabrication using complementary metal-oxide- semiconductor fabrication process.

  2. Gravitational Grating

    Science.gov (United States)

    Rahvar, Sohrab

    2018-05-01

    In this work, we study the interaction of the electromagnetic wave (EW) from a distant quasar with the gravitational wave (GW) sourced by the binary stars. While in the regime of geometric optics, the light bending due to this interaction is negligible, we show that the phase shifting on the wavefront of an EW can produce the diffraction pattern on the observer plane. The diffraction of the light (with the wavelength of λe) by the gravitational wave playing the role of gravitational grating (with the wavelength of λg) has the diffraction angle of Δβ ˜ λe/λg. The relative motion of the observer, the source of gravitational wave and the quasar results in a relative motion of the observer through the interference pattern on the observer plane. The consequence of this fringe crossing is the modulation in the light curve of a quasar with the period of few hours in the microwave wavelength. The optical depth for the observation of this phenomenon for a Quasar with the multiple images strongly lensed by a galaxy where the light trajectory of some of the images crosses the lensing galaxy is τ ≃ 0.2. By shifting the time-delay of the light curves of the multiple images in a strong lensed quasar and removing the intrinsic variations of a quasar, our desired signals, as a new method for detection of GWs can be detected.

  3. The spectral combination characteristic of grating and the bi-grating diffraction imaging effect

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper reports on a new property of grating, namely spectral combination, and on bi-grating diffraction imaging that is based on spectral combination. The spectral combination characteristic of a grating is the capability of combining multiple light beams of different wavelengths incident from specific angles into a single beam. The bi-grating diffraction imaging is the formation of the image of an object with two gratings: the first grating disperses the multi-color light beams from the object and the second combines the dispersed light beams to form the image. We gave the conditions necessary for obtaining the spectral combination. We also presented the equations that relate the two gratings’ spatial frequencies, diffraction orders and positions necessary for obtaining the bi-grating diffraction imaging.

  4. Speed and the coherence of superimposed chromatic gratings.

    Science.gov (United States)

    Bosten, J M; Smith, L; Mollon, J D

    2016-05-01

    On the basis of measurements of the perceived coherence of superimposed drifting gratings, Krauskopf and Farell (1990) proposed that motion is analysed independently in different chromatic channels. They found that two gratings appeared to slip if each modulated one of the two 'cardinal' color mechanisms S/(L+M) and L/(L+M). If the gratings were defined along intermediate color directions, observers reported a plaid, moving coherently. We hypothesised that slippage might occur in chromatic gratings if the motion signal from the S/(L+M) channel is weak and equivalent to a lower speed. We asked observers to judge coherence in two conditions. In one, S/(L+M) and L/(L+M) gratings were physically the same speed. In the other, the two gratings had perceptually matched speeds. We found that the relative incoherence of cardinal gratings is the same whether gratings are physically or perceptually matched in speed. Thus our hypothesis was firmly contradicted. In a control condition, observers were asked to judge the coherence of stationary gratings. Interestingly, the difference in judged coherence between cardinal and intermediate gratings remained as strong as it was when the gratings moved. Our results suggest a possible alternative interpretation of Krauskopf and Farell's result: the processes of object segregation may precede the analysis of the motion of chromatic gratings, and the same grouping signals may prompt object segregation in the stationary and moving cases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Fabrication update on critical-angle transmission gratings for soft x-ray grating spectrometers

    Science.gov (United States)

    Heilmann, Ralf K.; Bruccoleri, Alex; Mukherjee, Pran; Yam, Jonathan; Schattenburg, Mark L.

    2011-09-01

    Diffraction grating-based, wavelength dispersive high-resolution soft x-ray spectroscopy of celestial sources promises to reveal crucial data for the study of the Warm-Hot Intergalactic Medium, the Interstellar Medium, warm absorption and outflows in Active Galactic Nuclei, coronal emission from stars, and other areas of interest to the astrophysics community. Our recently developed critical-angle transmission (CAT) gratings combine the advantages of the Chandra high and medium energy transmission gratings (low mass, high tolerance of misalignments and figure errors, polarization insensitivity) with those of blazed reflection gratings (high broad band diffraction efficiency, high resolution through use of higher diffraction orders) such as the ones on XMM-Newton. Extensive instrument and system configuration studies have shown that a CAT grating-based spectrometer is an outstanding instrument capable of delivering resolving power on the order of 5,000 and high effective area, even with a telescope point-spread function on the order of many arc-seconds. We have fabricated freestanding, ultra-high aspect-ratio CAT grating bars from silicon-on-insulator wafers using both wet and dry etch processes. The 200 nm-period grating bars are supported by an integrated Level 1 support mesh, and a coarser external Level 2 support mesh. The resulting grating membrane is mounted to a frame, resulting in a grating facet. Many such facets comprise a grating array that provides light-weight coverage of large-area telescope apertures. Here we present fabrication results on the integration of CAT gratings and the different high-throughput support mesh levels and on membrane-frame bonding. We also summarize recent x-ray data analysis of 3 and 6 micron deep wet-etched CAT grating prototypes.

  6. Off-plane x-ray reflection grating fabrication

    Science.gov (United States)

    Peterson, Thomas J.; DeRoo, Casey T.; Marlowe, Hannah; McEntaffer, Randall L.; Miles, Drew M.; Tutt, James H.; Schultz, Ted B.

    2015-09-01

    Off-plane X-ray diffraction gratings with precision groove profiles at the submicron scale will be used in next generation X-ray spectrometers. Such gratings will be used on a current NASA suborbital rocket mission, the Off-plane Grating Rocket Experiment (OGRE), and have application for future grating missions. The fabrication of these gratings does not come without challenges. High performance off-plane gratings must be fabricated with precise radial grating patterns, optically at surfaces, and specific facet angles. Such gratings can be made using a series of common micro-fabrication techniques. The resulting process is highly customizable, making it useful for a variety of different mission architectures. In this paper, we detail the fabrication method used to produce high performance off-plane gratings and report the results of a preliminary qualification test of a grating fabricated in this manner. The grating was tested in the off-plane `Littrow' configuration, for which the grating is most efficient for a given diffraction order, and found to achieve 42% relative efficiency in the blaze order with respect to all diffracted light.

  7. Deep-etched sinusoidal polarizing beam splitter grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Cao, Hongchao; Lv, Peng

    2010-04-01

    A sinusoidal-shaped fused-silica grating as a highly efficient polarizing beam splitter (PBS) is investigated based on the simplified modal method. The grating structure depends mainly on the ratio of groove depth to grating period and the ratio of incident wavelength to grating period. These ratios can be used as a guideline for the grating design at different wavelengths. A sinusoidal-groove PBS grating is designed at a wavelength of 1310 nm under Littrow mounting, and the transmitted TM and TE polarized waves are mainly diffracted into the zeroth order and the -1st order, respectively. The grating profile is optimized by using rigorous coupled-wave analysis. The designed PBS grating is highly efficient (>95.98%) over the O-band wavelength range (1260-1360 nm) for both TE and TM polarizations. The sinusoidal grating can exhibit higher diffraction efficiency, larger extinction ratio, and less reflection loss than the rectangular-groove PBS grating. By applying wet etching technology on the rectangular grating, which was manufactured by holographic recording and inductively coupled plasma etching technology, the sinusoidal grating can be approximately fabricated. Experimental results are in agreement with theoretical values.

  8. An elastomeric grating coupler

    NARCIS (Netherlands)

    Kocabas, A.; Ay, F.; Dana, A.; Aydinli, A.

    We report on a novel nondestructive and reversible method for coupling free space light to planar optical waveguides. In this method, an elastomeric grating is used to produce an effective refractive index modulation on the surface of the optical waveguide. The external elastomeric grating binds to

  9. Bragg gratings in Topas

    DEFF Research Database (Denmark)

    Zhang, C.; Webb, D.J.; Kalli, K.

    We report for the first time fibre Bragg grating inscription in microstructured optical fibre fabricated from Topas® cyclic olefin copolymer. The temperature sensitivity of the grating was studied revealing a positive Bragg wavelength shift of approximately 0.8 nmK-1,the largest sensitivity yet...

  10. Optical Fiber Grating Hydrogen Sensors: A Review.

    Science.gov (United States)

    Dai, Jixiang; Zhu, Li; Wang, Gaopeng; Xiang, Feng; Qin, Yuhuan; Wang, Min; Yang, Minghong

    2017-03-12

    In terms of hydrogen sensing and detection, optical fiber hydrogen sensors have been a research issue due to their intrinsic safety and good anti-electromagnetic interference. Among these sensors, hydrogen sensors consisting of fiber grating coated with sensitive materials have attracted intensive research interests due to their good reliability and distributed measurements. This review paper mainly focuses on optical fiber hydrogen sensors associated with fiber gratings and various materials. Their configurations and sensing performances proposed by different groups worldwide are reviewed, compared and discussed in this paper. Meanwhile, the challenges for fiber grating hydrogen sensors are also addressed.

  11. Nanostructure Diffraction Gratings for Integrated Spectroscopy and Sensing

    Science.gov (United States)

    Guo, Junpeng (Inventor)

    2016-01-01

    The present disclosure pertains to metal or dielectric nanostructures of the subwavelength scale within the grating lines of optical diffraction gratings. The nanostructures have surface plasmon resonances or non-plasmon optical resonances. A linear photodetector array is used to capture the resonance spectra from one of the diffraction orders. The combined nanostructure super-grating and photodetector array eliminates the use of external optical spectrometers for measuring surface plasmon or optical resonance frequency shift caused by the presence of chemical and biological agents. The nanostructure super-gratings can be used for building integrated surface enhanced Raman scattering (SERS) spectrometers. The nanostructures within the diffraction grating lines enhance Raman scattering signal light while the diffraction grating pattern of the nanostructures diffracts Raman scattering light to different directions of propagation according to their wavelengths. Therefore, the nanostructure super-gratings allows for the use of a photodetector array to capture the surface enhanced Raman scattering spectra.

  12. Defect grating modes as superimposed grating states

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Sopaheluwakan, A.; Andonowati, A.; de Ridder, R.M; de Ridder, R.M.; Altena, G; Altena, G.; Geuzebroek, D.H.; Geuzenboek, D.; Dekker, R.; Dekker, R

    2003-01-01

    For a symmetric grating structure with a defect, we show that a fully transmitted defect mode in the band gap can be obtained as a superposition of two steady states: an amplified and an attenuated defect state. Without scanning the whole band gap by transmission calculations, this simplifies the

  13. Spherical grating spectrometers

    Science.gov (United States)

    O'Donoghue, Darragh; Clemens, J. Christopher

    2014-07-01

    We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

  14. Different level of population differentiation among human genes

    Directory of Open Access Journals (Sweden)

    Zhang Ya-Ping

    2011-01-01

    Full Text Available Abstract Background During the colonization of the world, after dispersal out of African, modern humans encountered changeable environments and substantial phenotypic variations that involve diverse behaviors, lifestyles and cultures, were generated among the different modern human populations. Results Here, we study the level of population differentiation among different populations of human genes. Intriguingly, genes involved in osteoblast development were identified as being enriched with higher FST SNPs, a result consistent with the proposed role of the skeletal system in accounting for variation among human populations. Genes involved in the development of hair follicles, where hair is produced, were also found to have higher levels of population differentiation, consistent with hair morphology being a distinctive trait among human populations. Other genes that showed higher levels of population differentiation include those involved in pigmentation, spermatid, nervous system and organ development, and some metabolic pathways, but few involved with the immune system. Disease-related genes demonstrate excessive SNPs with lower levels of population differentiation, probably due to purifying selection. Surprisingly, we find that Mendelian-disease genes appear to have a significant excessive of SNPs with high levels of population differentiation, possibly because the incidence and susceptibility of these diseases show differences among populations. As expected, microRNA regulated genes show lower levels of population differentiation due to purifying selection. Conclusion Our analysis demonstrates different level of population differentiation among human populations for different gene groups.

  15. Different level of population differentiation among human genes.

    Science.gov (United States)

    Wu, Dong-Dong; Zhang, Ya-Ping

    2011-01-14

    During the colonization of the world, after dispersal out of African, modern humans encountered changeable environments and substantial phenotypic variations that involve diverse behaviors, lifestyles and cultures, were generated among the different modern human populations. Here, we study the level of population differentiation among different populations of human genes. Intriguingly, genes involved in osteoblast development were identified as being enriched with higher FST SNPs, a result consistent with the proposed role of the skeletal system in accounting for variation among human populations. Genes involved in the development of hair follicles, where hair is produced, were also found to have higher levels of population differentiation, consistent with hair morphology being a distinctive trait among human populations. Other genes that showed higher levels of population differentiation include those involved in pigmentation, spermatid, nervous system and organ development, and some metabolic pathways, but few involved with the immune system. Disease-related genes demonstrate excessive SNPs with lower levels of population differentiation, probably due to purifying selection. Surprisingly, we find that Mendelian-disease genes appear to have a significant excessive of SNPs with high levels of population differentiation, possibly because the incidence and susceptibility of these diseases show differences among populations. As expected, microRNA regulated genes show lower levels of population differentiation due to purifying selection. Our analysis demonstrates different level of population differentiation among human populations for different gene groups.

  16. Fibre Bragg grating for flood embankment monitoring

    Science.gov (United States)

    Markowski, Konrad; Nevar, Stanislau; Dworzanski, Adam; Hackiewicz, Krzysztof; Jedrzejewski, Kazimierz

    2014-11-01

    In this article we present the preliminary studies for the flood embankment monitoring system based on the fibre Bragg gratings. The idea of the system is presented. The Bragg resonance shift is transformed to the change of the power detected by the standard InGaAs photodiode. The discrimination of the received power was executed by another fibre Bragg grating with different parameters. The project of the fully functional system is presented as well.

  17. Corrugated grating on organic multilayer Bragg reflector

    Science.gov (United States)

    Jaquet, Sylvain; Scharf, Toralf; Herzig, Hans Peter

    2007-08-01

    Polymeric multilayer Bragg structures are combined with diffractive gratings to produce artificial visual color effects. A particular effect is expected due to the angular reflection dependence of the multilayer Bragg structure and the dispersion caused by the grating. The combined effects can also be used to design particular filter functions and various resonant structures. The multilayer Bragg structure is fabricated by spin-coating of two different low-cost polymer materials in solution on a cleaned glass substrate. These polymers have a refractive index difference of about 0.15 and permit multilayer coatings without interlayer problems. Master gratings of different periods are realized by laser beam interference and replicated gratings are superimposed on the multilayer structure by soft embossing in a UV curing glue. The fabrication process requires only polymer materials. The obtained devices are stable and robust. Angular dependent reflection spectrums for the visible are measured. These results show that it is possible to obtain unexpected reflection effects. A rich variety of color spectra can be generated, which is not possible with a single grating. This can be explained by the coupling of transmission of grating orders and the Bragg reflection band. A simple model permits to explain some of the spectral vs angular dependence of reflected light.

  18. Adaptable Diffraction Gratings With Wavefront Transformation

    Science.gov (United States)

    Iazikov, Dmitri; Mossberg, Thomas W.; Greiner, Christoph M.

    2010-01-01

    Diffraction gratings are optical components with regular patterns of grooves, which angularly disperse incoming light by wavelength. Traditional diffraction gratings have static planar, concave, or convex surfaces. However, if they could be made so that they can change the surface curvature at will, then they would be able to focus on particular segments, self-calibrate, or perform fine adjustments. This innovation creates a diffraction grating on a deformable surface. This surface could be bent at will, resulting in a dynamic wavefront transformation. This allows for self-calibration, compensation for aberrations, enhancing image resolution in a particular area, or performing multiple scans using different wavelengths. A dynamic grating gives scientists a new ability to explore wavefronts from a variety of viewpoints.

  19. QTL mapping for combining ability in different population-based ...

    Indian Academy of Sciences (India)

    2013-12-13

    Dec 13, 2013 ... ability and for geneticists to research the genetic basis of combining ability. [Li L., Sun C., ... population-based NCII designs by a simulation study. J. Genet. ... combining ability could also be applied to other population- based NCII ... was to estimate how different base populations, sample sizes, heritability ...

  20. Design Factors Affect User Experience for Different Cultural Populations

    Science.gov (United States)

    Chu, Sauman

    2016-01-01

    With increasing changes in our demographic populations and new immigrants settling in the US, there is an increasing need for visual communications that address the diversity of our populations. This paper draws from the results of the researcher's several past research and teaching projects that worked with different cultural populations. These…

  1. Switchable Bragg gratings

    DEFF Research Database (Denmark)

    Marckmann, Carl Johan

    2003-01-01

    Research Center (MIC) at the Technical University of Denmark. The Bragg gratings were fabricated at COM using UV irradiation of the planar waveguides using the phase mask method. The induction of a frozen-in DC electric field into the samples was performed by thermal poling of the Bragg gratings...... layers, it becam possible to investigate the symmetry properties of the third-order nonlinearities. Contrary to the expectations for an amorphous material, the measurements indicated an almost polarization independent third-order nonlinearity - the most probable explanation being electrostriction......The subject of this ph.d. thesis was the development of an electrically switchable Bragg grating made in an optical waveguide using thermal poling to be applied within optical telecommunication systems. The planar waveguides used in this thesis were fabricated at the Micro- and Nanotechnology...

  2. Grateful Med: getting started.

    Science.gov (United States)

    Shearer, B; McCann, L; Crump, W J

    1990-01-01

    When a local medical library is not available, it is often necessary for physicians to discover alternate ways to receive medical information. Rural physicians, particularly, can make use of a computer program called Grateful Med that provides access to the same literature available to physicians in large cities. This program permits the user to perform database searches on the National Library of Medicine database (MEDLINE), corresponding to the primary index to medical literature, Index Medicus. In this article, we give the procedure for procuring a National Library of Medicine password and for making efficient use of the Grateful Med program.

  3. Effective length of short Fabry-Perot cavity formed by uniform fiber Bragg gratings.

    Science.gov (United States)

    Barmenkov, Yuri O; Zalvidea, Dobryna; Torres-Peiró, Salvador; Cruz, Jose L; Andrés, Miguel V

    2006-07-10

    In this paper, we describe the properties of Fabry-Perot fiber cavity formed by two fiber Bragg gratings in terms of the grating effective length. We show that the grating effective length is determined by the group delay of the grating, which depends on its diffraction efficiency and physical length. We present a simple analytical formula for calculation of the effective length of the uniform fiber Bragg grating and the frequency separation between consecutive resonances of a Fabry-Perot cavity. Experimental results on the cavity transmission spectra for different values of the gratings' reflectivity support the presented theory.

  4. Electro-optic diffraction grating tuned laser

    International Nuclear Information System (INIS)

    Hughes, R.S.

    1975-01-01

    An electro-optic diffraction grating tuned laser comprising a laser medium, output mirror, retro-reflective grating and an electro-optic diffraction grating beam deflector positioned between the laser medium and the reflective diffraction grating is described. An optional angle multiplier may be used between the electro-optic diffraction grating and the reflective grating. (auth)

  5. Fiber facet gratings for high power fiber lasers

    Science.gov (United States)

    Vanek, Martin; Vanis, Jan; Baravets, Yauhen; Todorov, Filip; Ctyroky, Jiri; Honzatko, Pavel

    2017-12-01

    We numerically investigated the properties of diffraction gratings designated for fabrication on the facet of an optical fiber. The gratings are intended to be used in high-power fiber lasers as mirrors either with a low or high reflectivity. The modal reflectance of low reflectivity polarizing grating has a value close to 3% for TE mode while it is significantly suppressed for TM mode. Such a grating can be fabricated on laser output fiber facet. The polarizing grating with high modal reflectance is designed as a leaky-mode resonant diffraction grating. The grating can be etched in a thin layer of high index dielectric which is sputtered on fiber facet. We used refractive index of Ta2O5 for such a layer. We found that modal reflectance can be close to 0.95 for TE polarization and polarization extinction ratio achieves 18 dB. Rigorous coupled wave analysis was used for fast optimization of grating parameters while aperiodic rigorous coupled wave analysis, Fourier modal method and finite difference time domain method were compared and used to compute modal reflectance of designed gratings.

  6. Bragg grating rogue wave

    Energy Technology Data Exchange (ETDEWEB)

    Degasperis, Antonio [Dipartimento di Fisica, “Sapienza” Università di Roma, P.le A. Moro 2, 00185 Roma (Italy); Wabnitz, Stefan, E-mail: stefan.wabnitz@unibs.it [Dipartimento di Ingegneria dell' Informazione, Università degli Studi di Brescia and INO-CNR, via Branze 38, 25123 Brescia (Italy); Aceves, Alejandro B. [Southern Methodist University, Dallas (United States)

    2015-06-12

    We derive the rogue wave solution of the classical massive Thirring model, that describes nonlinear optical pulse propagation in Bragg gratings. Combining electromagnetically induced transparency with Bragg scattering four-wave mixing may lead to extreme waves at extremely low powers.

  7. Silicon graphene Bragg gratings.

    Science.gov (United States)

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-03-10

    We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented.

  8. Slit and phase grating diffraction with a double crystal diffractometer

    International Nuclear Information System (INIS)

    Treimer, Wolfgang; Hilger, Andre; Strobl, Markus

    2006-01-01

    The lateral coherence properties of a neutron beam (λ=0.5248nm) in a double crystal diffractometer (DCD) were studied by means of single slit diffraction and by diffraction by different perfect Silicon phase gratings. Perfect agreements were found for the lateral coherence length measured with the slit and for the one determined by Silicon phase gratings, however, some peculiarities are still present

  9. On interfaces between cell populations with different mobilities

    KAUST Repository

    Lorenzi, Tommaso

    2016-11-18

    Partial differential equations describing the dynamics of cell population densities from a fluid mechanical perspective can model the growth of avascular tumours. In this framework, we consider a system of equations that describes the interaction between a population of dividing cells and a population of non-dividing cells. The two cell populations are characterised by different mobilities. We present the results of numerical simulations displaying two-dimensional spherical waves with sharp interfaces between dividing and non-dividing cells. Furthermore, we numerically observe how different ratios between the mobilities change the morphology of the interfaces, and lead to the emergence of finger-like patterns of invasion above a threshold. Motivated by these simulations, we study the existence of one-dimensional travelling wave solutions.

  10. Polarization sensitivity testing of off-plane reflection gratings

    Science.gov (United States)

    Marlowe, Hannah; McEntaffer, Randal L.; DeRoo, Casey T.; Miles, Drew M.; Tutt, James H.; Laubis, Christian; Soltwisch, Victor

    2015-09-01

    Off-Plane reflection gratings were previously predicted to have different efficiencies when the incident light is polarized in the transverse-magnetic (TM) versus transverse-electric (TE) orientations with respect to the grating grooves. However, more recent theoretical calculations which rigorously account for finitely conducting, rather than perfectly conducting, grating materials no longer predict significant polarization sensitivity. We present the first empirical results for radially ruled, laminar groove profile gratings in the off-plane mount which demonstrate no difference in TM versus TE efficiency across our entire 300-1500 eV bandpass. These measurements together with the recent theoretical results confirm that grazing incidence off-plane reflection gratings using real, not perfectly conducting, materials are not polarization sensitive.

  11. Optical fiber Bragg gratings. Part II. Modeling of finite-length gratings and grating arrays.

    Science.gov (United States)

    Passaro, Vittorio M N; Diana, Roberto; Armenise, Mario N

    2002-09-01

    A model of both uniform finite-length optical fiber Bragg gratings and grating arrays is presented. The model is based on the Floquet-Bloch formalism and allows rigorous investigation of all the physical aspects in either single- or multiple-periodic structures realized on the core of a monomodal fiber. Analytical expressions of reflectivity and transmittivity for both single gratings and grating arrays are derived. The influence of the grating length and the index modulation amplitude on the reflected and transmitted optical power for both sinusoidal and rectangular profiles is evaluated. Good agreement between our method and the well-known coupled-mode theory (CMT) approach has been observed for both single gratings and grating arrays only in the case of weak index perturbation. Significant discrepancies exist there in cases of strong index contrast because of the increasing approximation of the CMT approach. The effects of intragrating phase shift are also shown and discussed.

  12. Talbot effect of the defective grating in deep Fresnel region

    Science.gov (United States)

    Teng, Shuyun; Wang, Junhong; Zhang, Wei; Cui, Yuwei

    2015-02-01

    Talbot effect of the grating with different defect is studied theoretically and experimentally in this paper. The defects of grating include the loss of the diffraction unit, the dislocation of the diffraction unit and the modulation of the unit separation. The exact diffraction distributions of three kinds of defective gratings are obtained according to the finite-difference time-domain (FDTD) method. The calculation results show the image of the missing or dislocating unit appears at the Talbot distance (as mentioned in K. Patorski Prog. Opt., 27, 1989, pp.1-108). This is the so-called self-repair ability of grating imaging. In addition, some more phenomena are discovered. The loss or the dislocation of diffraction unit causes the diffraction distortion within a certain radial angle. The regular modulation of unit separation changes the original diffraction, but the new periodicity of the diffraction distribution rebuilds. The self-imaging of grating with smaller random modulation still keeps the partial self-repair ability, and yet this characteristic depends on the modulation degree of defective grating. These diffraction phenomena of the defective gratings are explained by use of the diffraction theory of grating. The practical experiment is also performed and the experimental results confirm the theoretic predictions.

  13. Grating stimulated echo

    International Nuclear Information System (INIS)

    Dubetsky, B.; Berman, P.R.; Sleator, T.

    1992-01-01

    A theory of a grating simulated echo (GTE) is developed. The GSE involves the sequential excitation of atoms by two counterpropagating traveling waves, a standing wave, and a third traveling wave. It is shown that the echo signal is very sensitive to small changes in atomic velocity, much more sensitive than the normal stimulated echo. Use of the GSE as a collisional probe or accelerometer is discussed

  14. Unified design of sinusoidal-groove fused-silica grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Cao, Hongchao; Lu, Peng

    2010-10-20

    A general design rule of deep-etched subwavelength sinusoidal-groove fused-silica grating as a highly efficient polarization-independent or polarization-selective device is studied based on the simplified modal method, which shows that the device structure depends little on the incident wavelength, but mainly on the ratio of groove depth to incident wavelength and the ratio of wavelength to grating period. These two ratios could be used as the design guidelines for wavelength-independent structure from deep ultraviolet to far infrared. The optimized grating profile with a different function as a polarizing beam splitter, a polarization-independent two-port beam splitter, or a polarization-independent grating with high efficiency of -1st order is obtained at a wavelength of 1064 nm, and verified by using the rigorous coupled-wave analysis. The performance of the sinusoidal grating is better than a conventional rectangular one, which could be useful for practical applications.

  15. Cancer mortality among two different populations of French nuclear workers

    Energy Technology Data Exchange (ETDEWEB)

    Samson, Eric; Telle-Lamberton, Maylis; Caer-Lorho, Sylvaine [Institut de Radioprotection et de Surete Nucleaire (IRSN), Fontenay-aux-Roses (France). DRPH, SRBE, LEPID; and others

    2011-08-15

    The aim of this paper is to study the effect of external photon radiation on the mortality of two populations of French nuclear workers: workers exposed only to external photon radiation and workers potentially exposed also to internal contamination or to neutrons. External photon radiation has been measured through individual dosimeters. Potential exposure to internal contamination or to neutrons has been assessed by experts on the basis of quantitative measurements or of worksite and type of activity. The mortality observed in each population was compared with that expected from national mortality statistics, by computing standardized mortality ratios. Dose-effect relationships were analyzed through trend tests and log-linear Poisson regressions. 14,796 workers were exposed only to external photon radiation; 14,408 workers were also potentially exposed to internal radiation or to neutrons. Between 1968 and 1994, the number of deaths is respectively, 645 and 1,197. The mean external photon dose was respectively, 3.7 and 12.9 mSv. Similar Healthy Worker Effects were observed in the two populations (SMR = 0.59). SMR of 2.41 90% CI [1.39-3.90] was observed for malignant melanoma among workers of the second population. Significant dose-effect relationships were observed: among workers exposed only to external photon radiation for leukemia except CLL and in the other population, for cancers and other diseases related to tobacco or alcohol consumption. Results differed between the two populations. The increase in leukemia risk with dose in the first population will have to be confirmed with extended follow-up. In the other population, results may have been confounded by alpha-emitters inhalation, tobacco, or alcohol consumption.

  16. Cancer mortality among two different populations of French nuclear workers

    International Nuclear Information System (INIS)

    Samson, Eric; Telle-Lamberton, Maylis; Caer-Lorho, Sylvaine

    2011-01-01

    The aim of this paper is to study the effect of external photon radiation on the mortality of two populations of French nuclear workers: workers exposed only to external photon radiation and workers potentially exposed also to internal contamination or to neutrons. External photon radiation has been measured through individual dosimeters. Potential exposure to internal contamination or to neutrons has been assessed by experts on the basis of quantitative measurements or of worksite and type of activity. The mortality observed in each population was compared with that expected from national mortality statistics, by computing standardized mortality ratios. Dose-effect relationships were analyzed through trend tests and log-linear Poisson regressions. 14,796 workers were exposed only to external photon radiation; 14,408 workers were also potentially exposed to internal radiation or to neutrons. Between 1968 and 1994, the number of deaths is respectively, 645 and 1,197. The mean external photon dose was respectively, 3.7 and 12.9 mSv. Similar Healthy Worker Effects were observed in the two populations (SMR = 0.59). SMR of 2.41 90% CI [1.39-3.90] was observed for malignant melanoma among workers of the second population. Significant dose-effect relationships were observed: among workers exposed only to external photon radiation for leukemia except CLL and in the other population, for cancers and other diseases related to tobacco or alcohol consumption. Results differed between the two populations. The increase in leukemia risk with dose in the first population will have to be confirmed with extended follow-up. In the other population, results may have been confounded by alpha-emitters inhalation, tobacco, or alcohol consumption.

  17. Population parameters to compare dog breeds : differences between five Dutch purebred populations

    NARCIS (Netherlands)

    Nielen, A.L.J.; Beek, van der S.; Ubbink, G.J.; Knol, B.W.

    2001-01-01

    Differences in five purebred dog populations born in 1994 in the Netherlands were evaluated using different parameters. Numerically, the Golden Retriever was the largest breed (840 litters of 234 sires) and the Kooiker Dog (101 litters of 41 sires) the smallest. The litter per sire ratio was largest

  18. Spectral tuning of the diameter-dependent-chirped Bragg gratings written in microfibers.

    Science.gov (United States)

    Xiao, Peng; Liu, Tong; Feng, Fu-Rong; Sun, Li-Peng; Liang, Hao; Ran, Yang; Jin, Long; Guan, Bai-Ou

    2016-12-26

    Chirped fiber Bragg gratings can straightforwardly and efficiently be fabricated onto microfibers with a uniform phase mask. Due to the variation of the propagating constant, which depends on the fiber diameter, the broadband spectrum of the grating can be formed. Depending on the different responses to the ambient refractive index in different parts of the grating, the bandwidth of the grating can be tuned by changing the surrounding solution. In addition, by being partly immersed in a liquid, the diameter-chirped Bragg grating can act as a broadband Fabry-Perot interferometer, whose spectrum can be tuned by means of controlling the liquid level and ambient refractive index.

  19. Overview of diffraction gratings technologies for spaceflight satellites and ground-based telescopes

    Science.gov (United States)

    Cotel, A.; Liard, A.; Desserouer, F.; Pichon, P.

    2017-11-01

    The diffraction gratings are widely used in Space-flight satellites for spectrograph instruments or in ground-based telescopes in astronomy. The diffraction gratings are one of the key optical components of such systems and have to exhibit very high optical performances. HORIBA Jobin Yvon S.A.S. (part of HORIBA Group) is in the forefront of such gratings development for more than 40 years. During the past decades, HORIBA Jobin Yvon (HJY) has developed a unique expertise in diffraction grating design and manufacturing processes for holographic, ruled or etched gratings. We will present in this paper an overview of diffraction grating technologies especially designed for space and astronomy applications. We will firstly review the heritage of the company in this field with the space qualification of different grating types. Then, we will describe several key grating technologies developed for specific space or astronomy projects: ruled blazed low groove density plane reflection grating, high-groove density holographic toroidal and spherical grating, and finally transmission Fused Silica Etched (FSE) grism-assembled grating. We will not present the Volume Phase Holographic (VPHG) grating type which is used in Astronomy.

  20. Overview of diffraction gratings technologies for space-flight satellites and astronomy

    Science.gov (United States)

    Cotel, Arnaud; Liard, Audrey; Desserouer, Frédéric; Bonnemason, Francis; Pichon, Pierre

    2014-09-01

    The diffraction gratings are widely used in Space-flight satellites for spectrograph instruments or in ground-based telescopes in astronomy. The diffraction gratings are one of the key optical components of such systems and have to exhibit very high optical performances. HORIBA Jobin Yvon S.A.S. (part of HORIBA Group) is in the forefront of such gratings development for more than 40 years. During the past decades, HORIBA Jobin Yvon (HJY) has developed a unique expertise in diffraction grating design and manufacturing processes for holographic, ruled or etched gratings. We will present in this paper an overview of diffraction grating technologies especially designed for space and astronomy applications. We will firstly review the heritage of the company in this field with the space qualification of different grating types. Then, we will describe several key grating technologies developed for specific space or astronomy projects: ruled blazed low groove density plane reflection grating, holographic blazed replica plane grating, high-groove density holographic toroidal and spherical grating and transmission Fused Silica Etched (FSE) grismassembled grating.

  1. Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter

    International Nuclear Information System (INIS)

    Deng Yang; Liu Yuan; Gao Dingshan

    2011-01-01

    We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

  2. Psychological and behavioral differences between low back pain populations

    DEFF Research Database (Denmark)

    Eklund, A.; Bergstrom, G.; Bodin, L.

    2015-01-01

    Background: Psychological, behavioral and social factors have long been considered important in the development of persistent pain. Little is known about how chiropractic low back pain (LBP) patients compare to other LBP patients in terms of psychological/behavioral characteristics. Methods......: In this cross-sectional study, the aim was to investigate patients with LBP as regards to psychosocial/behavioral characteristics by describing a chiropractic primary care population and comparing this sample to three other populations using the MPI-S instrument. Thus, four different samples were compared. A......: The data show statistically significant overall differences across samples for the subgroups based on psychological and behavioral characteristics. The cluster classifications placed (in terms of the proportions of the adaptive copers and dysfunctional subgroups) sample A between B and the two secondary...

  3. Hierarchical differences in population coding within auditory cortex.

    Science.gov (United States)

    Downer, Joshua D; Niwa, Mamiko; Sutter, Mitchell L

    2017-08-01

    Most models of auditory cortical (AC) population coding have focused on primary auditory cortex (A1). Thus our understanding of how neural coding for sounds progresses along the cortical hierarchy remains obscure. To illuminate this, we recorded from two AC fields: A1 and middle lateral belt (ML) of rhesus macaques. We presented amplitude-modulated (AM) noise during both passive listening and while the animals performed an AM detection task ("active" condition). In both fields, neurons exhibit monotonic AM-depth tuning, with A1 neurons mostly exhibiting increasing rate-depth functions and ML neurons approximately evenly distributed between increasing and decreasing functions. We measured noise correlation ( r noise ) between simultaneously recorded neurons and found that whereas engagement decreased average r noise in A1, engagement increased average r noise in ML. This finding surprised us, because attentive states are commonly reported to decrease average r noise We analyzed the effect of r noise on AM coding in both A1 and ML and found that whereas engagement-related shifts in r noise in A1 enhance AM coding, r noise shifts in ML have little effect. These results imply that the effect of r noise differs between sensory areas, based on the distribution of tuning properties among the neurons within each population. A possible explanation of this is that higher areas need to encode nonsensory variables (e.g., attention, choice, and motor preparation), which impart common noise, thus increasing r noise Therefore, the hierarchical emergence of r noise -robust population coding (e.g., as we observed in ML) enhances the ability of sensory cortex to integrate cognitive and sensory information without a loss of sensory fidelity. NEW & NOTEWORTHY Prevailing models of population coding of sensory information are based on a limited subset of neural structures. An important and under-explored question in neuroscience is how distinct areas of sensory cortex differ in their

  4. Laser sensor with Bragg gratings of fiber optics to physics parameter measuring

    International Nuclear Information System (INIS)

    Vazquez, R.; Garcia, C.; May, M.; Camas, J.

    2009-01-01

    We present the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980nm, an 4.23 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength increases their temperature which can be used as a sensor element. The laser generation thus shows that the Bragg grating is increasing their temperature. We used a Peltier cell for to change gradually the temperature. (Author)

  5. Population and sex differences in Drosophila melanogaster brain gene expression

    Directory of Open Access Journals (Sweden)

    Catalán Ana

    2012-11-01

    Full Text Available Abstract Background Changes in gene regulation are thought to be crucial for the adaptation of organisms to their environment. Transcriptome analyses can be used to identify candidate genes for ecological adaptation, but can be complicated by variation in gene expression between tissues, sexes, or individuals. Here we use high-throughput RNA sequencing of a single Drosophila melanogaster tissue to detect brain-specific differences in gene expression between the sexes and between two populations, one from the ancestral species range in sub-Saharan Africa and one from the recently colonized species range in Europe. Results Relatively few genes (Cyp6g1 and CHKov1. Conclusions Analysis of the brain transcriptome revealed many genes differing in expression between populations that were not detected in previous studies using whole flies. There was little evidence for sex-specific regulatory adaptation in the brain, as most expression differences between populations were observed in both males and females. The enrichment of genes with sexually dimorphic expression on the X chromosome is consistent with dosage compensation mechanisms affecting sex-biased expression in somatic tissues.

  6. Cylinder and metal grating polarization beam splitter

    Science.gov (United States)

    Yang, Junbo; Xu, Suzhi

    2017-08-01

    We propose a novel and compact metal grating polarization beam splitter (PBS) based on its different reflected and transmitted orders. The metal grating exhibits a broadband high reflectivity and polarization dependence. The rigorous coupled wave analysis is used to calculate the reflectivity and the transmitting spectra and optimize the structure parameters to realize the broadband PBS. The finite-element method is used to calculate the field distribution. The characteristics of the broadband high reflectivity, transmitting and the polarization dependence are investigated including wavelength, period, refractive index and the radius of circle grating. When grating period d = 400 nm, incident wavelength λ = 441 nm, incident angle θ = 60° and radius of circle d/5, then the zeroth reflection order R0 = 0.35 and the transmission zeroth order T0 = 0.08 for TE polarization, however, T0 = 0.34 and R0 = 0.01 for TM mode. The simple fabrication method involves only single etch step and good compatibility with complementary metal oxide semiconductor technology. PBS designed here is particularly suited for optical communication and optical information processing.

  7. Breast density in screening mammography in Indian population - Is it different from western population?

    Science.gov (United States)

    Singh, Tulika; Khandelwal, Niranjan; Singla, Veenu; Kumar, Dileep; Gupta, Madhu; Singh, Gurpreet; Bal, Amanjit

    2018-05-01

    Mammography is the only method presently considered appropriate for mass screening of breast cancer. However, higher breast density was strongly associated with lower mammographic sensitivity. Breast density is also identified as independent and strongest risk factors for breast cancer. Studies have shown women with high breast density have four to six times increased risk of breast cancer as compare to women with fatty breast. It varies between different age group it generally decreases with increasing age in postmenopausal women and it can be different in different ethnic groups and people from different geographical areas. This study evaluates the breast density in Indian population and its relationship with the age. We reviewed of all screening mammography examinations performed from May 2012 to January 2015 at our institute PGIMER, Chandigarh, INDIA. Descriptive analyses were used to examine the association between age and breast density. A total of 6132 screening mammograms were performed. Each subgroup categorized by decade of age. There was a significant inverse relationship between age and breast density (P density in Indian and Western population with more Indians having ACR Grade 1 and 2 and Western population having 2 and 3. We found an inverse relationship between patient age and mammographic breast density. However, there were a large proportion of young women who had lower grades of mammographic density which could potentially benefit from the use of routine screening mammography in this subgroup of patients. Moreover, the breast density of Indian population is less when compared to the Western population. This might suggest that mammography is a good modality of choice for screening Indian population. © 2017 Wiley Periodicals, Inc.

  8. Hiring appropriate providers for different populations: acute care nurse practitioners.

    Science.gov (United States)

    Haut, Cathy; Madden, Maureen

    2015-06-01

    Acute care nurse practitioners, prepared as providers for a variety of populations of patients, continue to make substantial contributions to health care. Evidence indicates shorter stays, higher satisfaction among patients, increased work efficiency, and higher quality outcomes when acute care nurse practitioners are part of unit- or service-based provider teams. The Consensus Model for APRN Regulation: Licensure, Accreditation, Certification, and Education outlines detailed guidelines for matching nurse practitioners' education with certification and practice by using a population-focused algorithm. Despite national support for the model, nurse practitioners and employers continue to struggle with finding the right fit. Nurse practitioners often use their interest and previous nursing experience to apply for an available position, and hospitals may not understand preparation or regulations related to matching the appropriate provider to the work environment. Evidence and regulatory guidelines indicate appropriate providers for population-focused positions. This article presents history and recommendations for hiring acute care nurse practitioners as providers for different populations of patients. ©2015 American Association of Critical-Care Nurses.

  9. Personality differences in two minnow populations that differ in their parasitism and predation risk

    Directory of Open Access Journals (Sweden)

    Raine eKortet

    2015-02-01

    Full Text Available Animals are often individually consistent in their behavior, not only over time, but also across different functional contexts. Recent research has focused on phenotypic and evolutionary mechanisms explaining such personality differences through selection. Parasitism and predation induce important mortality and fitness costs, and are thus the main candidates to create and maintain personality differences in the wild. Here, we present data on the behavioral consistency of the Eurasian minnow (Phoxinus phoxinus from two populations that live in different tributaries of the same river, but whose ecological environment differs fundamentally with regard to predation and parasitism. We experimentally demonstrate that minnow in both study populations are consistent in their boldness and activity. However, the two study populations differ notably: in the high predation and parasitism risk population fish show higher mean boldness, but tend to be less active than fish in low predation and parasitism risk population. Parasite (Diplostomum phoxini load was negatively, but not statistically significantly, associated with fish activity level. Our study suggests that parasitism and predation are likely important agents in the ecology and evolution of animal personalities.

  10. Chemical control of different Digitaria insularis populations and management of a glyphosate-resistant population

    OpenAIRE

    CORREIA,N.M.; ACRA,L.T.; BALIEIRO,G.

    2015-01-01

    This study aimed to control different populations of Digitaria insularisby glyphosate herbicide, isolated and mixed, besides the combination of methods (chemical and mechanical) to manage resistant adult plants. Three experiments were conducted, one in pots which were maintained under non-controlled conditions and two under field conditions. In the experiment in pots, twelve populations of D. insularis were sprayed with isolated glyphosate (1.44 and 2.16 kg a.e. ha-1) and mixed (1.44 and 2.16...

  11. A reconfigurable optofluidic Michelson interferometer using tunable droplet grating.

    Science.gov (United States)

    Chin, L K; Liu, A Q; Soh, Y C; Lim, C S; Lin, C L

    2010-04-21

    This paper presents a novel optofluidic Michelson interferometer based on droplet microfluidics used to create a droplet grating. The droplet grating is formed by a stream of plugs in the microchannel with constant refractive index variation. It has a real-time tunability in the grating period through varying the flow rates of the liquids and index variation via different combinations of liquids. The optofluidic Michelson interferometer is highly sensitive and is suitable for the measurement of biomedical and biochemical buffer solutions. The experimental results show that it has a sensitivity of 66.7 nm per refractive index unit (RIU) and a detection range of 0.086 RIU.

  12. [The management of asymptomatic bacteriuria in different patient population].

    Science.gov (United States)

    Ivanov, M-L; Malinverni, R

    2008-11-12

    Who should be screened for asymptomatic bacteriuria (AB) and who should be treated? This review updates some aspects of the management of AB in different patient populations. A systematic screening for AB is recommended for pregnant women because of a significant risk of complications. In these cases as well as before any uro-gynecologic surgical procedure treatment of AB is strongly recommended. The management of AB in immunosuppressed or transplanted patients is more controversial. In other populations treating AB is not recommended and the outcome seems to be worse in case of treatment due to possible side effects and selection of resistant organisms. Recent studies have shown a considerable gap between clinical practice and recommendations.

  13. Suppressing Ghost Diffraction in E-Beam-Written Gratings

    Science.gov (United States)

    Wilson, Daniel; Backlund, Johan

    2009-01-01

    A modified scheme for electron-beam (E-beam) writing used in the fabrication of convex or concave diffraction gratings makes it possible to suppress the ghost diffraction heretofore exhibited by such gratings. Ghost diffraction is a spurious component of diffraction caused by a spurious component of grating periodicity as described below. The ghost diffraction orders appear between the main diffraction orders and are typically more intense than is the diffuse scattering from the grating. At such high intensity, ghost diffraction is the dominant source of degradation of grating performance. The pattern of a convex or concave grating is established by electron-beam writing in a resist material coating a substrate that has the desired convex or concave shape. Unfortunately, as a result of the characteristics of electrostatic deflectors used to control the electron beam, it is possible to expose only a small field - typically between 0.5 and 1.0 mm wide - at a given fixed position of the electron gun relative to the substrate. To make a grating larger than the field size, it is necessary to move the substrate to make it possible to write fields centered at different positions, so that the larger area is synthesized by "stitching" the exposed fields.

  14. Imaging properties of high aspect ratio absorption gratings for use in preclinical x-ray grating interferometry.

    Science.gov (United States)

    Trimborn, Barbara; Meyer, Pascal; Kunka, Danays; Zuber, Marcus; Albrecht, Frederic; Kreuer, Sascha; Volk, Thomas; Baumbach, Tilo; Koenig, Thomas

    2016-01-21

    X-ray grating interferometry is one among various methods that allow extracting the so-called phase and visibility contrasts in addition to the well-known transmission images. Crucial to achieving a high image quality are the absorption gratings employed. Here, we present an in-depth analysis of how the grating type and lamella heights influence the final images. Benchmarking gratings of two different designs, we show that a frequently used proxy for image quality, a grating's so-called visibility, is insufficient to predict contrast-to-noise ratios (CNRs). Presenting scans from an excised rat lung, we demonstrate that the CNRs obtained for transmission and visibility images anti-correlate. This is explained by the stronger attenuation implied by gratings that are engineered to provide high visibilities by means of an increased lamella height. We show that even the visibility contrast can suffer from this effect when the associated reduced photon flux on the detector is not outweighed by a corresponding gain in visibility. Resulting in an inevitable trade-off between the quality of the two contrasts, the question of how an optimal grating should be designed can hence only be answered in terms of Pareto optimality.

  15. Differences in Sleep Duration among Four Different Population Groups of Older Adults in South Africa

    Directory of Open Access Journals (Sweden)

    Karl Peltzer

    2017-05-01

    Full Text Available The study aims to investigate sleep duration in four different population groups in a national probability sample of older South Africans who participated in the Study of Global Ageing and Adult Health (SAGE Wave 1. A national population-based cross-sectional study with a sample of 3284 aged 50 years or older in South Africa was conducted in 2008. The questionnaire included socio-demographic characteristics, health variables, and self-reported sleep duration. Results indicate that White Africans compared to other population groups had the lowest mean sleep duration (7.88 h among men and 7.46 h among women. The prevalence of short sleep was the highest among both men and women among the White African (18.8% in men and 16.9% in women and Indian or Asian African population groups (14.5% in men and 17.1% in women, and lowest among both men and women in the Black African (7.0% in men and 6.5% in women and multi-ancestry population groups (15.6% in men and 12.7% in women. The prevalence of long sleep was among both men and women the highest in the Black African population group (56.2% in men and 58.5% in women, and the lowest in the White African population group (36.4% in men and 24.3% in women. In a Poisson regression model, adjusted for sociodemographics and chronic disease status, coming from the male and female White African population group was associated with short sleep. In addition, coming from the Indian or Asian African population group was associated with short sleep. No population group differences were found regarding long sleep prevalence. White Africans reported more short sleep duration than the other population groups, while there were no racial or ethnic differences in long sleep. White Africans are more likely to have sleep durations that are associated with negative health outcomes. An explanation of the high short sleep prevalence among White Africans may be related to their racial or ethnic minority status in South Africa.

  16. Differences in Sleep Duration among Four Different Population Groups of Older Adults in South Africa.

    Science.gov (United States)

    Peltzer, Karl

    2017-05-09

    The study aims to investigate sleep duration in four different population groups in a national probability sample of older South Africans who participated in the Study of Global Ageing and Adult Health (SAGE) Wave 1. A national population-based cross-sectional study with a sample of 3284 aged 50 years or older in South Africa was conducted in 2008. The questionnaire included socio-demographic characteristics, health variables, and self-reported sleep duration. Results indicate that White Africans compared to other population groups had the lowest mean sleep duration (7.88 h among men and 7.46 h among women). The prevalence of short sleep was the highest among both men and women among the White African (18.8% in men and 16.9% in women) and Indian or Asian African population groups (14.5% in men and 17.1% in women), and lowest among both men and women in the Black African (7.0% in men and 6.5% in women) and multi-ancestry population groups (15.6% in men and 12.7% in women). The prevalence of long sleep was among both men and women the highest in the Black African population group (56.2% in men and 58.5% in women), and the lowest in the White African population group (36.4% in men and 24.3% in women). In a Poisson regression model, adjusted for sociodemographics and chronic disease status, coming from the male and female White African population group was associated with short sleep. In addition, coming from the Indian or Asian African population group was associated with short sleep. No population group differences were found regarding long sleep prevalence. White Africans reported more short sleep duration than the other population groups, while there were no racial or ethnic differences in long sleep. White Africans are more likely to have sleep durations that are associated with negative health outcomes. An explanation of the high short sleep prevalence among White Africans may be related to their racial or ethnic minority status in South Africa.

  17. Experimental depletion of different renal interstitial cell populations

    International Nuclear Information System (INIS)

    Bohman, S.O.; Sundelin, B.; Forsum, U.; Tribukait, B.

    1988-01-01

    To define different populations of renal interstitial cells and investigate some aspects of their function, we studied the kidneys of normal rats and rats with hereditary diabetes insipidus (DI, Brattleboro) after experimental manipulations expected to alter the number of interstitial cells. DI rats showed an almost complete loss of interstitial cells in their renal papillae after treatment with a high dose of vasopressin. In spite of the lack of interstitial cells, the animals concentrated their urine to the same extent as vasopressin-treated normal rats, indicating that the renomedullary interstitial cells do not have an important function in concentrating the urine. The interstitial cells returned nearly to normal within 1 week off vasopressin treatment, suggesting a rapid turnover rate of these cells. To further distinguish different populations of interstitial cells, we studied the distribution of class II MHC antigen expression in the kidneys of normal and bone-marrow depleted Wistar rats. Normal rats had abundant class II antigen-positive interstitial cells in the renal cortex and outer medulla, but not in the inner medulla (papilla). Six days after 1000 rad whole body irradiation, the stainable cells were almost completely lost, but electron microscopic morphometry showed a virtually unchanged volume density of interstitial cells in the cortex and outer medulla, as well as the inner medulla. Thus, irradiation abolished the expression of the class II antigen but caused no significant depletion of interstitial cells

  18. Genetic algorithm for the design of high frequency diffraction gratings for high power laser applications

    Science.gov (United States)

    Thomson, Martin J.; Waddie, Andrew J.; Taghizadeh, Mohammad R.

    2006-04-01

    We present a genetic algorithm with small population sizes for the design of diffraction gratings in the rigorous domain. A general crossover and mutation scheme is defined, forming fifteen offspring from 3 parents, which enables the algorithm to be used for designing gratings with diverse optical properties by careful definition of the merit function. The initial parents are randomly selected and the parents of the subsequent generations are selected by survival of the fittest. The performance of the algorithm is demonstrated by designing diffraction gratings with specific application to high power laser beam lines. Gratings are designed that act as beam deflectors, polarisers, polarising beam splitters, harmonic separation gratings and pulse compression gratings. By imposing fabrication constraints within the design process, we determine which of these elements have true potential for application within high power laser beam lines.

  19. Study the effect of dye concentration on optical history using circular polarization holographic grating in thin polymeric film

    International Nuclear Information System (INIS)

    Mohajerani, E.; Hosain Nataj, N.

    2006-01-01

    By studying the effect of dye concentration, we obtained the optimal dye concentration for recording holographic gratings. The history of circular polarization grating is also investigated. We built polarization holographic grating with more than 2 weeks history. By using a mask in front of pump beam, different pictures could be built up in the film.

  20. Bragg gratings: Optical microchip sensors

    Science.gov (United States)

    Watts, Sam

    2010-07-01

    A direct UV writing technique that can create multiple Bragg gratings and waveguides in a planar silica-on-silicon chip is enabling sensing applications ranging from individual disposable sensors for biotechnology through to multiplexed sensor networks in pharmaceutical manufacturing.

  1. Encapsulation process for diffraction gratings.

    Science.gov (United States)

    Ratzsch, Stephan; Kley, Ernst-Bernhard; Tünnermann, Andreas; Szeghalmi, Adriana

    2015-07-13

    Encapsulation of grating structures facilitates an improvement of the optical functionality and/or adds mechanical stability to the fragile structure. Here, we introduce novel encapsulation process of nanoscale patterns based on atomic layer deposition and micro structuring. The overall size of the encapsulated structured surface area is only restricted by the size of the available microstructuring and coating devices; thus, overcoming inherent limitations of existing bonding processes concerning cleanliness, roughness, and curvature of the components. Finally, the process is demonstrated for a transmission grating. The encapsulated grating has 97.5% transmission efficiency in the -1st diffraction order for TM-polarized light, and is being limited by the experimental grating parameters as confirmed by rigorous coupled wave analysis.

  2. MEMS Bragg grating force sensor

    DEFF Research Database (Denmark)

    Reck, Kasper; Thomsen, Erik Vilain; Hansen, Ole

    2011-01-01

    We present modeling, design, fabrication and characterization of a new type of all-optical frequency modulated MEMS force sensor based on a mechanically amplified double clamped waveguide beam structure with integrated Bragg grating. The sensor is ideally suited for force measurements in harsh...... environments and for remote and distributed sensing and has a measured sensitivity of -14 nm/N, which is several times higher than what is obtained in conventional fiber Bragg grating force sensors. © 2011 Optical Society of America....

  3. [Perception of sweet and salty flavors in different population groups].

    Science.gov (United States)

    González Carnero, J; de la Montaña Miguélez, J; Míguez Bernárdez, M

    2002-01-01

    The flavour perceived by humans when eating varies depending on age, gender, habits, emotional status, etc. The present study reflects the changes in the perception of sweet and salt flavours among different population groups depending on age, with an assessment, for each flavour, of the threshold concentration for the detection of these flavours. Triangular discrimination sensorial tests were performed in three groups, with thirty members in each, classified to represent young, adult and elderly age groups. With regard to sweet flavours, the groups of young people and adults distinguished the different sample at 0.1% of sugar for 95% and 99% significance levels, whereas the elderly required the concentration to reach 1% at both levels before they could distinguish the sugar solution from water. In the case of salt flavours, young people are able to detect the different sample at the lowest concentration level, for both levels of significance. Adults significantly distinguished the sample containing 0.05% of salt, at the 95% significance level, whereas the elderly needed a concentration of 0.1% for both levels of significance. Age-dependent variations in response were observed. As age increases, greater concentrations are required in order to distinguish the salt or sweet solutions from the samples containing only water.

  4. Population spikes in cortical networks during different functional states.

    Directory of Open Access Journals (Sweden)

    Shirley eMark

    2012-07-01

    Full Text Available Brain computational challenges vary between behavioral states. Engaged animals react according to incoming sensory information, while in relaxed and sleeping states consolidation of the learned information is believed to take place. Different states are characterized by different forms of cortical activity. We study a possible neuronal mechanism for generating these diverse dynamics and suggest their possible functional significance. Previous studies demonstrated that brief synchronized increase in a neural firing (Population Spikes can be generated in homogenous recurrent neural networks with short-term synaptic depression. Here we consider more realistic networks with clustered architecture. We show that the level of synchronization in neural activity can be controlled smoothly by network parameters. The network shifts from asynchronous activity to a regime in which clusters synchronized separately, then, the synchronization between the clusters increases gradually to fully synchronized state. We examine the effects of different synchrony levels on the transmission of information by the network. We find that the regime of intermediate synchronization is preferential for the flow of information between sparsely connected areas. Based on these results, we suggest that the regime of intermediate synchronization corresponds to engaged behavioral state of the animal, while global synchronization is exhibited during relaxed and sleeping states.

  5. Influence of Non-uniform Temperature Field on Spectra of Fibre Bragg Grating

    International Nuclear Information System (INIS)

    Yan, Zhou; Xing-Fang, He; Xiao-Yong, Fang; Jie, Yuan; Li-Qun, Yin; Mao-Sheng, Cao

    2009-01-01

    We simulate the spectrum characteristics of fibre Bragg grating (FBG) with non-uniform temperature using the transmission matrix method, and the results are analysed. It is found that firstly the modulated coefficient of average refractive index is a very important parameter that influences the spectrum characteristic of the fibre Bragg grating, and secondly the spectrum curves are different in different temperature fields at the same parameter. Hence, we can determine the metrical temperature by analysing the spectrum of fibre Bragg grating

  6. Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

    Science.gov (United States)

    Min, Rui; Marques, Carlos; Bang, Ole; Ortega, Beatriz

    2018-03-01

    We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured.

  7. Theory of Fiber Optical Bragg Grating: Revisited

    Science.gov (United States)

    Tai, H.

    2003-01-01

    The reflected signature of an optical fiber Bragg grating is analyzed using the transfer function method. This approach is capable to cast all relevant quantities into proper places and provides a better physical understanding. The relationship between reflected signal, number of periods, index of refraction, and reflected wave phase is elucidated. The condition for which the maximum reflectivity is achieved is fully examined. We also have derived an expression to predict the reflectivity minima accurately when the reflected wave is detuned. Furthermore, using the segmented potential approach, this model can handle arbitrary index of refraction profiles and compare the strength of optical reflectivity of different profiles. The condition of a non-uniform grating is also addressed.

  8. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking......-column’’ approach and includes the energy equations for both the fuel and the gas accounting for heat transfer between the two phases. The model gives important insight into the combustion process and provides inlet conditions for a computational fluid dynamics analysis of the freeboard. The model predictions...... indicate the existence of two distinct combustion modes. Combustion air temperature and mass flow-rate are the two parameters determining the mode. There is a significant difference in reaction rates (ignition velocity) and temperature levels between the two modes. Model predictions were compared...

  9. Diffraction Efficiency Testing of Sinusoidal and Blazed Off-Plane Reflection Gratings

    Science.gov (United States)

    Tutt, James H.; McEntaffer, Randall L.; Marlowe, Hannah; Miles, Drew M.; Peterson, Thomas J.; Deroo, Casey T.; Scholze, Frank; Laubis, Christian

    2016-09-01

    Reflection gratings in the off-plane mount have the potential to enhance the performance of future high resolution soft X-ray spectrometers. Diffraction efficiency can be optimized through the use of blazed grating facets, achieving high-throughput on one side of zero-order. This paper presents the results from a comparison between a grating with a sinusoidally grooved profile and two gratings that have been blazed. The results show that the blaze does increase throughput to one side of zero-order; however, the total throughput of the sinusoidal gratings is greater than the blazed gratings, suggesting the method of manufacturing the blazed gratings does not produce precise facets. The blazed gratings were also tested in their Littrow and anti-Littrow configurations to quantify diffraction efficiency sensitivity to rotations about the grating normal. Only a small difference in the energy at which efficiency is maximized between the Littrow and anti-Littrow configurations is seen with a small shift in peak efficiency towards higher energies in the anti-Littrow case. This is due to a decrease in the effective blaze angle in the anti-Littrow mounting. This is supported by PCGrate-SX V6.1 modeling carried out for each blazed grating which predicts similar response trends in the Littrow and anti-Littrow orientations.

  10. Gender differences in smoking behaviors in an Asian population.

    Science.gov (United States)

    Tsai, Yi-Wen; Tsai, Tzu-I; Yang, Chung-Lin; Kuo, Ken N

    2008-01-01

    Gender-sensitive tobacco control policies are being challenged, and new directions are being sought because public health efforts have reduced cigarette consumption more substantially among men than among women. To better target women, it would help to identify the protective cultural factors that promote resiliency in women and discourage them from smoking. Whereas western cultures have generated a great deal of gender-specific research and programs on the prevention of smoking in women, Asian cultures have not. Taking a personal and sociocultural perspective, this study examines the effect of gender on smoking behaviors in Taiwan. In a 2004 cross-sectional random-sampled interview survey, 827 adult men and 90 adult women smokers in Taiwan were queried about the time they began smoking, maintenance of their habits, and their readiness to change. The male/female smoking rate ratio was 9.5 (45.7% vs. 4.8%). Men smoked significantly more cigarettes per day than women (18 vs. 11). We found Taiwanese women started smoking around 20 years old, much later than their western counterparts. We also found that whereas the smoking behavior of the men was very sensitive to social environment and structural factors, that of women revolved around their desire to control their weight and handle their emotions. Differences in the smoking behavior of men and women are a result of a different sociocultural environment and the life trajectories and social circumstances embedded within it. Comprehensive tobacco control policies need to be tailored to not just smoking behavior alone or one population alone but to the determinants of smoking behavior in specific groups, for example, women. Even when targeting women, some effort may be needed on targeting women of different ethnicities, for instance, Asian women in whom the prevalence is increasing at alarming rates.

  11. Holographic grating relaxation technique for soft matter science

    Energy Technology Data Exchange (ETDEWEB)

    Lesnichii, Vasilii, E-mail: vasilii.lesnichii@physchem.uni-freiburg.de [Institute of Physical Chemistry, Albertstraße 21, Institute of Macromolecular Chemistry, Stefan-Meier-Str. 31, Albert-Ludwigs Universität, Freiburg im Breisgau 79104 (Germany); ITMO University, Kronverksky prospekt 49, Saint-Petersburg 197101 (Russian Federation); Kiessling, Andy [Institute of Physical Chemistry, Albertstraße 21, Institute of Macromolecular Chemistry, Stefan-Meier-Str. 31, Albert-Ludwigs Universität, Freiburg im Breisgau 79104 (Germany); Current address: Illinois Institute of Technology, 10 West 33rd Street, Chicago,IL60616 (United States); Bartsch, Eckhard [Institute of Physical Chemistry, Albertstraße 21, Institute of Macromolecular Chemistry, Stefan-Meier-Str. 31, Albert-Ludwigs Universität, Freiburg im Breisgau 79104 (Germany); Veniaminov, Andrey, E-mail: veniaminov@phoi.ifmo.ru [ITMO University, Kronverksky prospekt 49, Saint-Petersburg 197101 (Russian Federation)

    2016-06-17

    The holographic grating relaxation technique also known as forced Rayleigh scattering consists basically in writing a holographic grating in the specimen of interest and monitoring its diffraction efficiency as a function of time, from which valuable information on mass or heat transfer and photoinduced transformations can be extracted. In a more detailed view, the shape of the relaxation curve and the relaxation rate as a function of the grating period were found to be affected by the architecture of diffusing species (molecular probes) that constitute the grating, as well as that of the environment they diffuse in, thus making it possible to access and study spatial heterogeneity of materials and different modes of e.g., polymer motion. Minimum displacements and spatial domains approachable by the technique are in nanometer range, well below spatial periods of holographic gratings. In the present paper, several cases of holographic relaxation in heterogeneous media and complex motions are exemplified. Nano- to micro-structures or inhomogeneities comparable in spatial scale with holographic gratings manifest themselves in relaxation experiments via non-exponential decay (stepwise or stretched), spatial-period-dependent apparent diffusion coefficient, or unusual dependence of diffusion coefficient on molecular volume of diffusing probes.

  12. Time-domain Brillouin scattering assisted by diffraction gratings

    Science.gov (United States)

    Matsuda, Osamu; Pezeril, Thomas; Chaban, Ievgeniia; Fujita, Kentaro; Gusev, Vitalyi

    2018-02-01

    Absorption of ultrashort laser pulses in a metallic grating deposited on a transparent sample launches coherent compression/dilatation acoustic pulses in directions of different orders of acoustic diffraction. Their propagation is detected by delayed laser pulses, which are also diffracted by the metallic grating, through the measurement of the transient intensity change of the first-order diffracted light. The obtained data contain multiple frequency components, which are interpreted by considering all possible angles for the Brillouin scattering of light achieved through multiplexing of the propagation directions of light and coherent sound by the metallic grating. The emitted acoustic field can be equivalently presented as a superposition of plane inhomogeneous acoustic waves, which constitute an acoustic diffraction grating for the probe light. Thus the obtained results can also be interpreted as a consequence of probe light diffraction by both metallic and acoustic gratings. The realized scheme of time-domain Brillouin scattering with metallic gratings operating in reflection mode provides access to wide range of acoustic frequencies from minimal to maximal possible values in a single experimental optical configuration for the directions of probe light incidence and scattered light detection. This is achieved by monitoring the backward and forward Brillouin scattering processes in parallel. Potential applications include measurements of the acoustic dispersion, simultaneous determination of sound velocity and optical refractive index, and evaluation of samples with a single direction of possible optical access.

  13. Thermal-grating contributions to degenerate four-wave mixing in nitric oxide

    International Nuclear Information System (INIS)

    Danehy, P.M.; Paul, P.H.; Farrow, R.L.

    1995-01-01

    We report investigations of degenerate four-wave mixing (DFWM) line intensities in the A 2 Σ + left-arrow X 2 Π electronic transitions of nitric oxide. Contributions from population gratings (spatially varying perturbations in the level populations of absorbing species) and thermal gratings (spatially varying perturbations in the overall density) were distinguished and compared by several experimental and analytical techniques. For small quantities of nitric oxide in a strongly quenching buffer gas (carbon dioxide), we found that thermal-grating contributions dominated at room temperature for gas pressures of ∼0.5 atm and higher. In a nearly nonquenching buffer (nitrogen) the population-grating mechanism dominated at pressures of ∼1.0 atm and lower. At higher temperatures in an atmospheric-pressure methane/air flame, population gratings of nitric oxide also dominated. We propose a simple model for the ratio of thermal- to population-grating scattering intensities that varies as P 4 T -4.4 . Preliminary investigations of the temperature dependence and detailed studies of the pressure dependence are in agreement with this model. Measurements of the temporal evolution and the peak intensity of isolated thermal-grating signals are in detailed agreement with calculations based on a linearized hydrodynamic model [J. Opt. Soc. Am. B 12, 384 (1995)]. copyright 1995 Optical Society of America

  14. Thermal and Structural Analysis of FIMS Grating

    Directory of Open Access Journals (Sweden)

    K.-I. Seon

    2001-06-01

    Full Text Available Far ultraviolet IMaging Spectrograph (FIMS should be designed to maintain its structural stability and to minimize optical performance degradation in launch and in operation enviroments. The structural and thermal analyzes of grating and grating mount system, which are directly related to FIMS optical performance, was performed using finite element method. The grating mount was made to keep the grating stress down, while keeping the natural frequency of the grating mount higher than 100 Hz. Transient and static thermal analyzes were also performed and the results shows that the thermal stress on the grating can be attenuated sufficiently The optical performance variation due to temperature variation was within the allowed range.

  15. Grating scattering BRDF and imaging performances: A test survey performed in the frame of the flex mission

    Science.gov (United States)

    Harnisch, Bernd; Deep, Atul; Vink, Ramon; Coatantiec, Claude

    2017-11-01

    Key components in optical spectrometers are the gratings. Their influence on the overall infield straylight of the spectrometer depends not only on the technology used for grating fabrication but also on the potential existence of ghost images caused by irregularities of the grating constant. For the straylight analysis of spectrometer no general Bidirectional Reflectance Distribution Function (BRDF) model of gratings exist, as it does for optically smooth surfaces. These models are needed for the determination of spectrometer straylight background and for the calculation of spectrometer out of band rejection performances. Within the frame of the Fluorescence Earth Explorer mission (FLEX), gratings manufactured using different technologies have been investigated in terms of straylight background and imaging performance in the used diffraction order. The gratings which have been investigated cover a lithographically written grating, a volume Bragg grating, two holographic gratings and an off-the-shelf ruled grating. In this paper we present a survey of the measured bidirectional reflectance/transmittance distribution function and the determination of an equivalent surface micro-roughness of the gratings, describing the scattering of the grating around the diffraction order. This is specifically needed for the straylight modeling of the spectrometer.

  16. Optimization of top coupling grating for very long wavelength QWIP based on surface plasmon

    Science.gov (United States)

    Wang, Guodong; Shen, Junling; Liu, Xiaolian; Ni, Lu; Wang, Saili

    2017-09-01

    The relative coupling efficiency of two-dimensional (2D) grating based on surface plasmon for very long wavelength quantum well infrared detector is analyzed by using the three-dimensional finite-difference time domain (3D-FDTD) method algorithm. The relative coupling efficiency with respect to the grating parameters, such as grating pitch, duty ratio, and grating thickness, is analyzed. The calculated results show that the relative coupling efficiency would reach the largest value for the 14.5 μm incident infrared light when taking the grating pitch as 4.4 μm, the duty ratio as 0.325, and the grating thickness as 0.07 μm, respectively.

  17. Polarizing beam splitter of deep-etched triangular-groove fused-silica gratings.

    Science.gov (United States)

    Zheng, Jiangjun; Zhou, Changhe; Feng, Jijun; Wang, Bo

    2008-07-15

    We investigated the use of a deep-etched fused-silica grating with triangular-shaped grooves as a highly efficient polarizing beam splitter (PBS). A triangular-groove PBS grating is designed at a wavelength of 1550 nm to be used in optical communication. When it is illuminated in Littrow mounting, the transmitted TE- and TM-polarized waves are mainly diffracted in the minus-first and zeroth orders, respectively. The design condition is based on the average differences of the grating mode indices, which is verified by using rigorous coupled-wave analysis. The designed PBS grating is highly efficient over the C+L band range for both TE and TM polarizations (>97.68%). It is shown that such a triangular-groove PBS grating can exhibit a higher diffraction efficiency, a larger extinction ratio, and less reflection loss than the binary-phase fused-silica PBS grating.

  18. Exploiting a Transmission Grating Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Ronald E. Bell

    2004-12-08

    The availability of compact transmission grating spectrometers now allows an attractive and economical alternative to the more familiar Czerny-Turner configuration for many high-temperature plasma applications. Higher throughput is obtained with short focal length refractive optics and stigmatic imaging. Many more spectra can be obtained with a single spectrometer since smaller, more densely packed optical input fibers can be used. Multiple input slits, along with a bandpass filter, can be used to maximize the number of spectra per detector, providing further economy. Curved slits can correct for the strong image curvature of the short focal length optics. Presented here are the governing grating equations for both standard and high-dispersion transmission gratings, defining dispersion, image curvature, and desired slit curvature, that can be used in the design of improved plasma diagnostics.

  19. Exploiting a Transmission Grating Spectrometer

    International Nuclear Information System (INIS)

    Bell, Ronald E.

    2004-01-01

    The availability of compact transmission grating spectrometers now allows an attractive and economical alternative to the more familiar Czerny-Turner configuration for many high-temperature plasma applications. Higher throughput is obtained with short focal length refractive optics and stigmatic imaging. Many more spectra can be obtained with a single spectrometer since smaller, more densely packed optical input fibers can be used. Multiple input slits, along with a bandpass filter, can be used to maximize the number of spectra per detector, providing further economy. Curved slits can correct for the strong image curvature of the short focal length optics. Presented here are the governing grating equations for both standard and high-dispersion transmission gratings, defining dispersion, image curvature, and desired slit curvature, that can be used in the design of improved plasma diagnostics

  20. On interfaces between cell populations with different mobilities

    KAUST Repository

    Lorenzi, Tommaso; Lorz, Alexander; Perthame, Benoit

    2016-01-01

    Partial differential equations describing the dynamics of cell population densities from a fluid mechanical perspective can model the growth of avascular tumours. In this framework, we consider a system of equations that describes the interaction

  1. Polymer optical fiber bragg grating sensors

    DEFF Research Database (Denmark)

    Stefani, Alessio; Yuan, Scott Wu; Andresen, Søren

    2010-01-01

    Fiber-optical accelerometers based on polymer optical fiber Bragg gratings are reported. We have written fiber Bragg gratings for 1550 nm and 850 nm operations, characterized their temperature and strain response, and tested their performance in a prototype accelerometer....

  2. Enhanced Raman scattering in porous silicon grating.

    Science.gov (United States)

    Wang, Jiajia; Jia, Zhenhong; Lv, Changwu

    2018-03-19

    The enhancement of Raman signal on monocrystalline silicon gratings with varying groove depths and on porous silicon grating were studied for a highly sensitive surface enhanced Raman scattering (SERS) response. In the experiment conducted, porous silicon gratings were fabricated. Silver nanoparticles (Ag NPs) were then deposited on the porous silicon grating to enhance the Raman signal of the detective objects. Results show that the enhancement of Raman signal on silicon grating improved when groove depth increased. The enhanced performance of Raman signal on porous silicon grating was also further improved. The Rhodamine SERS response based on Ag NPs/ porous silicon grating substrates was enhanced relative to the SERS response on Ag NPs/ porous silicon substrates. Ag NPs / porous silicon grating SERS substrate system achieved a highly sensitive SERS response due to the coupling of various Raman enhancement factors.

  3. Grating-Coupled Waveguide Cloaking

    International Nuclear Information System (INIS)

    Wang Jia-Fu; Qu Shao-Bo; Ma Hua; Wang Cong-Min; Wang Xin-Hua; Zhou Hang; Xu Zhuo; Xia Song

    2012-01-01

    Based on the concept of a grating-coupled waveguide (GCW), a new strategy for realizing EM cloaking is presented. Using metallic grating, incident waves are firstly coupled into the effective waveguide and then decoupled into free space behind, enabling EM waves to pass around the obstacle. Phase compensation in the waveguide keeps the wave-front shape behind the obstacle unchanged. Circular, rectangular and triangular cloaks are presented to verify the robustness of the GCW cloaking. Electric field animations and radar cross section (RCS) comparisons convincingly demonstrate the cloaking effect

  4. Fabrication of Polymer Optical Fibre (POF Gratings

    Directory of Open Access Journals (Sweden)

    Yanhua Luo

    2017-03-01

    Full Text Available Gratings inscribed in polymer optical fibre (POF have attracted remarkable interest for many potential applications due to their distinctive properties. This paper overviews the current state of fabrication of POF gratings since their first demonstration in 1999. In particular we summarize and discuss POF materials, POF photosensitivity, techniques and issues of fabricating POF gratings, as well as various types of POF gratings.

  5. Embedded high-contrast distributed grating structures

    Science.gov (United States)

    Zubrzycki, Walter J.; Vawter, Gregory A.; Allerman, Andrew A.

    2002-01-01

    A new class of fabrication methods for embedded distributed grating structures is claimed, together with optical devices which include such structures. These new methods are the only known approach to making defect-free high-dielectric contrast grating structures, which are smaller and more efficient than are conventional grating structures.

  6. Hybrid grating reflectors: Origin of ultrabroad stopband

    DEFF Research Database (Denmark)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug

    2016-01-01

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well ...

  7. Genetic differences between mestizo populations of Bolivia and Peru

    Directory of Open Access Journals (Sweden)

    2003-01-01

    deberse a un grado mayor de mixtura en los mestizos de Bolivia con grupos étnicos andinos, y/o menos rasgos rurales y mayor mixtura caucásica en los mestizos peruanos reportados en la literatura. Estos hallazgos podrían tener un impacto con respecto a la eficacia de formas modernas de inmunización a través de vacunas de ADN en población andina, y en la identificación de riesgo para ciertas condiciones médicas. Data on the genetic background of Peruvian and Bolivian populations is still scarce. Studies have shown that mestizos (i.e. mixed, but of predominantly Native American ancestry present several HLA alleles originally described in genetically isolated Amerindian tribes, and that Peruvian and Bolivian mestizos are closely genetically related. Using Reverse Line Blot Assay, HLA typing for Class I (HLA-A, HLA-B, and HLA-Cw as well as for Class II (HLA-DRB1 and HLA-DQB1 alleles was performed in 57 Bolivian mestizos. Subjects came mainly from La Paz (the main city in the Bolivian Andes and three other important cities located in the Bolivian Central Valley (Sucre, Tarija and Tupiza. Comparison of the allele frequencies of Bolivian mestizos with available data from the literature from Peruvian mestizos, revealed that Class I HLA-Cw*01, and B*40 alleles were higher in the Peruvian mestizo group (Chi-sq = 4,87 p<0,05 and chi-sq = 7,56 p<0,01 respectively. Regarding Class II alleles, HLA-DRB1*1101 and DRB1*1302 alleles were higher in Peruvian mestizos (Chi-sq = 5,12 p<.05 chi-sq = 3,8 p = 0.05 respectively, while HLA-DQB1*0402 was significantly higher in Bolivian mestizos (Chi-sq = 47,2 p<.0001. Differences in allele frequencies, and the absence or presence of certain alleles in either group could be due to a higher grade of admixture with Andean ethnic groups in the mestizos from Bolivia and/or less rural traits and more white (Caucasian admixture in the Peruvian mestizos reported in the literature. These findings may have an impact regarding efficacies of modern

  8. Analysis of surface absorbed dose in X-ray grating interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhili, E-mail: wangnsrl@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China); Wu, Zhao; Gao, Kun; Wang, Dajiang; Chen, Heng; Wang, Shenghao [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China); Wu, Ziyu, E-mail: wuzy@ustc.edu.cn [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026 (China); Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2014-10-15

    Highlights: • Theoretical framework for dose estimation in X-ray grating interferometry. • Potential dose reduction of X-ray grating interferometry compared to conventional radiography. • Guidelines for optimization of X-ray grating interferometry for dose-sensitive applications. • Measure to compare various existing X-ray phase contrast imaging techniques. - Abstract: X-ray phase contrast imaging using grating interferometry has shown increased contrast over conventional absorption imaging, and therefore the great potential of dose reduction. The extent of the dose reduction depends on the geometry of grating interferometry, the photon energy, the properties of the sample under investigation and the utilized detector. These factors also determine the capability of grating interferometry to distinguish between different tissues with a specified statistical certainty in a single raw image. In this contribution, the required photon number for imaging and the resulting surface absorbed dose are determined in X-ray grating interferometry, using a two-component imaging object model. The presented results confirm that compared to conventional radiography, phase contrast imaging using grating interferometry indeed has the potential of dose reduction. And the extent of dose reduction is strongly dependent on the imaging conditions. Those results provide a theoretical framework for dose estimation under given imaging conditions before experimental trials, and general guidelines for optimization of grating interferometry for those dose-sensitive applications.

  9. Analysis of surface absorbed dose in X-ray grating interferometry

    International Nuclear Information System (INIS)

    Wang, Zhili; Wu, Zhao; Gao, Kun; Wang, Dajiang; Chen, Heng; Wang, Shenghao; Wu, Ziyu

    2014-01-01

    Highlights: • Theoretical framework for dose estimation in X-ray grating interferometry. • Potential dose reduction of X-ray grating interferometry compared to conventional radiography. • Guidelines for optimization of X-ray grating interferometry for dose-sensitive applications. • Measure to compare various existing X-ray phase contrast imaging techniques. - Abstract: X-ray phase contrast imaging using grating interferometry has shown increased contrast over conventional absorption imaging, and therefore the great potential of dose reduction. The extent of the dose reduction depends on the geometry of grating interferometry, the photon energy, the properties of the sample under investigation and the utilized detector. These factors also determine the capability of grating interferometry to distinguish between different tissues with a specified statistical certainty in a single raw image. In this contribution, the required photon number for imaging and the resulting surface absorbed dose are determined in X-ray grating interferometry, using a two-component imaging object model. The presented results confirm that compared to conventional radiography, phase contrast imaging using grating interferometry indeed has the potential of dose reduction. And the extent of dose reduction is strongly dependent on the imaging conditions. Those results provide a theoretical framework for dose estimation under given imaging conditions before experimental trials, and general guidelines for optimization of grating interferometry for those dose-sensitive applications

  10. Opiate addicts in and outside of treatment; Different populations?

    NARCIS (Netherlands)

    M.A. Goossensen (Anne)

    1997-01-01

    textabstractThe core of this study is related to the insight that the population of opiate addicls is quite an invisible group. Some paris of this group can be identified at treatment institutions and in prisons. However, a large pari of the opiate addicls is hard to detect. This is because

  11. Two-dimensional grating guided-mode resonance tunable filter.

    Science.gov (United States)

    Kuo, Wen-Kai; Hsu, Che-Jung

    2017-11-27

    A two-dimensional (2D) grating guided-mode resonance (GMR) tunable filter is experimentally demonstrated using a low-cost two-step nanoimprinting technology with a one-dimensional (1D) grating polydimethylsiloxane mold. For the first nanoimprinting, we precisely control the UV LED irradiation dosage and demold the device when the UV glue is partially cured and the 1D grating mold is then rotated by three different angles, 30°, 60°, and 90°, for the second nanoimprinting to obtain 2D grating structures with different crossing angles. A high-refractive-index film ZnO is then coated on the surface of the grating structure to form the GMR filter devices. The simulation and experimental results demonstrate that the passband central wavelength of the filter can be tuned by rotating the device to change azimuth angle of the incident light. We compare these three 2D GMR filters with differential crossing angles and find that the filter device with a crossing angle of 60° exhibits the best performance. The tunable range of its central wavelength is 668-742 nm when the azimuth angle varies from 30° to 90°.

  12. Color multiplexing using directional holographic gratings and linear polarization

    International Nuclear Information System (INIS)

    Lugo, L I; Rodriguez, A; Ramirez, G; Guel, S; Nunez, O F

    2011-01-01

    We propose a system of multiplexing and de-multiplexing, which uses a holographic diffraction grating to compel modulated light of different colors to be sent through an optical fiber. Diffraction gratings were fabricated specifically to pick the desired direction in which we wanted the light of different wavelengths to impinge the optic fiber, and also to be separated at the output. It was been found that the system preserves the polarization of light, which give us a one more freedom degree, allowing us to process twice the original information amount.

  13. The Off-plane Grating Rocket Experiment

    Science.gov (United States)

    Donovan, Benjamin

    2018-01-01

    The next generation of X-ray spectrometers necessitate significant increases in both resolution and effective area to achieve the science goals set forth in the 2010 Decadal Survey and the 2013 Astrophysics Roadmap. The Off-plane Grating Rocket Experiment (OGRE), an X-ray spectroscopy suborbital rocket payload currently scheduled for launch in Q3 2020, will serve as a testbed for several key technologies which can help achieve the desired performance increases of future spectrometers. OGRE will be the first instrument to fly mono-crystalline silicon X-ray mirrors developed at NASA Goddard Space Flight Center. The payload will also utilize an array of off-plane gratings manufactured at The Pennsylvania State University. Additionally, the focal plane will be populated with an array of four electron-multiplying CCDs developed by the Open University and XCAM Ltd. With these key technologies, OGRE hopes to achieve the highest resolution on-sky soft X-ray spectrum to date. We discuss the optical design, expected performance, and the current status of the payload.

  14. The grating as an accelerating structure

    International Nuclear Information System (INIS)

    Fernow, R.C.

    1991-02-01

    This report considers the use of a diffraction grating as an accelerating structure for charged particle beams. We examine the functional dependence of the electromagnetic fields above the surface of a grating. Calculations are made of the strength of the accelerating modes for structures with π and 2π phase advance per period and for incident waves polarized with either the E or H vector along the grooves of the grating. We consider examples of using gratings in a laser linac and in a grating lens. We also briefly examine previous results published about this subject. 36 refs

  15. Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

    DEFF Research Database (Denmark)

    Min, Rui; Marques, Carlos; Bang, Ole

    2018-01-01

    We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different...

  16. Variation in MHC genotypes in two populations of house sparrow (Passer domesticus) with different population histories.

    Science.gov (United States)

    Borg, Asa Alexandra; Pedersen, Sindre Andre; Jensen, Henrik; Westerdahl, Helena

    2011-10-01

    Small populations are likely to have a low genetic ability for disease resistance due to loss of genetic variation through inbreeding and genetic drift. In vertebrates, the highest genetic diversity of the immune system is located at genes within the major histocompatibility complex (MHC). Interestingly, parasite-mediated selection is thought to potentially maintain variation at MHC loci even in populations that are monomorphic at other loci. Therefore, general loss of genetic variation in the genome may not necessarily be associated with low variation at MHC loci. We evaluated inter- and intrapopulation variation in MHC genotypes between an inbred (Aldra) and a relatively outbred population (Hestmannøy) of house sparrows (Passer domesticus) in a metapopulation at Helgeland, Norway. Genomic (gDNA) and transcribed (cDNA) alleles of functional MHC class I and IIB loci, along with neutral noncoding microsatellite markers, were analyzed to obtain relevant estimates of genetic variation. We found lower allelic richness in microsatellites in the inbred population, but high genetic variation in MHC class I and IIB loci in both populations. This suggests that also the inbred population could be under balancing selection to maintain genetic variation for pathogen resistance.

  17. Point-by-point written fiber-Bragg gratings and their application in complex grating designs.

    Science.gov (United States)

    Marshall, Graham D; Williams, Robert J; Jovanovic, Nemanja; Steel, M J; Withford, Michael J

    2010-09-13

    The point-by-point technique of fabricating fibre-Bragg gratings using an ultrafast laser enables complete control of the position of each index modification that comprises the grating. By tailoring the local phase, amplitude and spacing of the grating's refractive index modulations it is possible to create gratings with complex transmission and reflection spectra. We report a series of grating structures that were realized by exploiting these flexibilities. Such structures include gratings with controlled bandwidth, and amplitude- and phase-modulated sampled (or superstructured) gratings. A model based on coupled-mode theory provides important insights into the manufacture of such gratings. Our approach offers a quick and easy method of producing complex, non-uniform grating structures in both fibres and other mono-mode waveguiding structures.

  18. Large allozyme variation within populations and isozyme differences ...

    African Journals Online (AJOL)

    Significant pair-wise contingency chi-square differences, one isozyme and another fixed allele difference at LDH, were found between the species. Nevertheless, a relatively small genetic distance value (D = 0.134) between the species supports recent morphological and DNA results by other researchers, confirming the ...

  19. Highly Sensitive Cadmium Concentration Sensor Using Long Period Grating

    Directory of Open Access Journals (Sweden)

    A. S. Lalasangi

    2011-08-01

    Full Text Available In this paper we have proposed a simple and effective Long Period Grating chemical sensor for detecting the traces of Cadmium (Cd++ in drinking water at ppm level. Long Period gratings (LPG were fabricated by point-by-point technique with CO2 laser. We have characterized the LPG concentration sensor sensitivity for different solutions of Cd concentrations varying from 0.01 ppm to 0.04 ppm by injecting white Light source and observed transmitted spectra using Optical Spectrum Analyzer (OSA. Proper reagents have been used in the solutions for detection of the Cd species. The overall shift in wavelength is 10 nm when surrounding medium gradually changed from water to 0.04 ppm of cadmium concentrations. A comparative study has been done using sophisticated spectroscopic atomic absorption spectrometer (AAS and Inductively Coupled Plasma (ICP instruments. The spectral sensitivity enhancement was done by modifying grating surface with gold nanoparticles.

  20. Geographically distinct Ceratophyllum demersum populations differ in growth, photosynthetic responses and phenotypic plasticity to nitrogen availability

    DEFF Research Database (Denmark)

    Hyldgaard, Benita; Sorrell, Brian Keith; Olesen, Birgit

    2012-01-01

    from New Zealand (NZ) and a noninvasive population from Denmark (DK). The populations were compared with a focus on both morphological and physiological traits. The NZ population had higher relative growth rates (RGRs) and photosynthesis rates (Pmax) (range: RGR, 0.06–0.08 per day; Pmax, 200–395 µmol O......2 g–1 dry mass (DM) h–1) compared with the Danish population (range: RGR, 0.02–0.05 per day; Pmax, 88–169 µmol O2 g–1 DM h–1). The larger, faster-growing NZ population also showed higher plasticity than the DK population in response to nitrogen in traits important for growth. Hence, the observed...... differences in growth behaviour between the two populations are a result of genetic differences and differences in their level of plasticity. Here, we show that two populations of the same species from similar climates but different geographical areas can differ in several ecophysiological traits after growth...

  1. Mechanism of optical unidirectional transmission in subwavelength dual-metal gratings

    Science.gov (United States)

    Gao, H.; Zheng, Z. Y.; Hao, H. Y.; Dong, A. G.; Fan, Z. J.; Liu, D. H.

    2014-03-01

    The mechanism of optical unidirectional (OUD) transmission in parallel subwavelength dual-metal gratings was investigated. It was found that this kind of OUD phenomenon originates from the coupling of the surface plasmon polaritons (SPPs) between the front grating and a layer of metal film which replaces the rear grating. The higher the intensity of the coupled SPPs at the entrances of the rear grating, the higher the transmittance can be achieved. Basing on this property, an effective OUD example was achieved by exploring the intensity difference at the entrances of the rear gratings between the two incidences of opposite directions. In this kind of OUD, the positive transmittance can exceed 80 % and the difference between the transmittances of the two opposite directions can be as large as 63 %. The detailed design process was also presented.

  2. variation of small mammal populations across different habitat types ...

    African Journals Online (AJOL)

    Mwangi

    DIFFERENT HABITAT TYPES IN THE SERENGETI ECOSYSTEM. Flora J. Magige*. Department ... There was moderately high similarity in the number of species caught in the two sites ..... Mountains Tanzania (wet season). MSc. Dissertation ...

  3. Sex Differences in Money Pathology in the General Population.

    Science.gov (United States)

    Furnham, Adrian; von Stumm, Sophie; Fenton-O'Creevy, Mark

    This study examined sex differences in money beliefs and behaviours. Over 100,000 British participants completed two measures online, one of which assessed "money pathology" (Forman in Mind over money, Doubleday, Toronto, 1987), and the other four "money types", based on the emotional associations of money (Furnham et al. in Personal Individ Differ, 52:707-711, 2012). Nearly all measures showed significant sex differences with medium to large effect sizes, and with females exhibiting more "money pathology" than males. The biggest difference on the money types was on money being associated with generosity (money representing love) where men scored much lower than females, and autonomy (money representing freedom) where men scored higher than women. For men, more than women, money represented Power and Security. Men were more likely to be Hoarders while women did more emotional regulatory purchasing. Implications and limitations of this study are discussed.

  4. Ocular injury: Prevalence in different rural population of Bangladesh.

    Science.gov (United States)

    Khan, A K

    2013-12-01

    This population based cross-sectional study was conducted on 8283 persons of all ages in five districts, selected conveniently, to assess the magnitude of ocular injuries, their causes and consequences in rural Bangladesh. Six Upazilas from five districts and from each Upazila one Union was selected randomly. One village, the ultimate cluster, was then selected conveniently from each Union. All people (n = 8283) in the 8 villages were then surveyed. Out of 8283 population (ranging from 1-120 years) surveyed, 167(2%) had history and/or evidence of past ocular trauma with a yearly incidence of 6.2 per 1000 per year. Study demonstrated a female predominance with male to female ratio being roughly 4:5. Majority (82%) had at least one episode of trauma in their life-time with mean age at 1st trauma being 20 years. Nearly 40% of the traumas were caused by blunt objects followed by penetrating object (22.3%) and sharp instrument (18.1%) with home being the primary place of occurrence (55.1%). Evidence of ocular trauma was found on eye-lid (15%), conjunctiva (11.4%) and cornea (10.2%) as scars. The older participants (≥ 30 years), females, illiterates, agriculture labors, housewives and household workers were more likely to receive trauma. Majority (86.8%) of the subjects received treatment following injury. The median time lapsed between injuries and receiving first treatment was 5 days and that between injury and visiting an eye-specialist was 18 days. Self-treatment and treatment from over-the-counter comprised 45% and 42.1% respectively followed by eye-specialists (25.5%), village quack (22.8%), graduate doctors (19.3%) and traditional healers (6.9%). About 87% received conservative management, with 12.4% needing hospitalization. Most of the injured (92.8%) and non-injured (95.2%) eyes had normal vision before trauma as informed by the respondents. Following trauma, 18% had impaired, 10.7% severely impaired vision and about 6% were blind. Job abstinence due to trauma

  5. Serum PSA levels in the Indian population: Is it different?

    Science.gov (United States)

    Agrawal, Amit; Karan, Shailesh Chandra

    2017-04-01

    Serum prostate-specific antigen (PSA) is an important tumour, marker which is widely used to trigger trans-rectal ultrasound (TRUS)-guided prostate biopsy. However, the PSA levels vary with race and ethnicity. Therefore, there is a need to have an Indian reference range. All adult male patients meeting the inclusion and exclusion criteria were enrolled in this study. They were subjected to assessment of serum total PSA, digital rectal examination and trans-abdominal ultrasound. If any one or more of these were found abnormal, then a TRUS-guided 12-core prostate biopsy was done. Patients who were detected to have prostatic cancer were excluded from the final analysis. The data so obtained was grouped among the following three age groups: 40-49, 50-59 and 60-70 years, and the age-specific PSA values, prostatic volume and PSA density were found. A total of 1772 patients were analysed. The mean serum total PSA was 1.76 ng/ml with a standard deviation of 2.566 ng/ml. Group-wise age distribution of the mean serum total PSA was 1.22, 1.97 and 2.08 ng/ml in 40-49, 50-59 and 60-70 years age groups. The mean total PSA and the age-specific PSA range tend to be lower in the Indians than the Western population.

  6. Alternative Placements: Does a Difference Exist in the LD Populations?

    Science.gov (United States)

    Olson, Judy; Midgett, Jeanice

    1984-01-01

    The performance of learning disabled male elementary students in self-contained classes (N=35) and resource rooms (N=50) was compared on five diagnostic tests and factors of retention, chronological age, and behavior. Results indicated a difference only in the intelligence factor between the groups. (Authors)

  7. Reliability of different mark-recapture methods for population size estimation tested against reference population sizes constructed from field data.

    Directory of Open Access Journals (Sweden)

    Annegret Grimm

    Full Text Available Reliable estimates of population size are fundamental in many ecological studies and biodiversity conservation. Selecting appropriate methods to estimate abundance is often very difficult, especially if data are scarce. Most studies concerning the reliability of different estimators used simulation data based on assumptions about capture variability that do not necessarily reflect conditions in natural populations. Here, we used data from an intensively studied closed population of the arboreal gecko Gehyra variegata to construct reference population sizes for assessing twelve different population size estimators in terms of bias, precision, accuracy, and their 95%-confidence intervals. Two of the reference populations reflect natural biological entities, whereas the other reference populations reflect artificial subsets of the population. Since individual heterogeneity was assumed, we tested modifications of the Lincoln-Petersen estimator, a set of models in programs MARK and CARE-2, and a truncated geometric distribution. Ranking of methods was similar across criteria. Models accounting for individual heterogeneity performed best in all assessment criteria. For populations from heterogeneous habitats without obvious covariates explaining individual heterogeneity, we recommend using the moment estimator or the interpolated jackknife estimator (both implemented in CAPTURE/MARK. If data for capture frequencies are substantial, we recommend the sample coverage or the estimating equation (both models implemented in CARE-2. Depending on the distribution of catchabilities, our proposed multiple Lincoln-Petersen and a truncated geometric distribution obtained comparably good results. The former usually resulted in a minimum population size and the latter can be recommended when there is a long tail of low capture probabilities. Models with covariates and mixture models performed poorly. Our approach identified suitable methods and extended options to

  8. Feasibility evaluation of a neutron grating interferometer with an analyzer grating based on a structured scintillator

    Science.gov (United States)

    Kim, Youngju; Kim, Jongyul; Kim, Daeseung; Hussey, Daniel. S.; Lee, Seung Wook

    2018-03-01

    We introduce an analyzer grating based on a structured scintillator fabricated by a gadolinium oxysulfide powder filling method for a symmetric Talbot-Lau neutron grating interferometer. This is an alternative way to analyze the Talbot self-image of a grating interferometer without using an absorption grating to block neutrons. Since the structured scintillator analyzer grating itself generates the signal for neutron detection, we do not need an additional scintillator screen as an absorption analyzer grating. We have developed and tested an analyzer grating based on a structured scintillator in our symmetric Talbot-Lau neutron grating interferometer to produce high fidelity absorption, differential phase, and dark-field contrast images. The acquired images have been compared to results of a grating interferometer utilizing a typical absorption analyzer grating with two commercial scintillation screens. The analyzer grating based on the structured scintillator enhances interference fringe visibility and shows a great potential for economical fabrication, compact system design, and so on. We report the performance of the analyzer grating based on a structured scintillator and evaluate its feasibility for the neutron grating interferometer.

  9. Polarization control method for UV writing of advanced bragg gratings

    DEFF Research Database (Denmark)

    Deyerl, Hans-Jürgen; Plougmann, Nikolai; Jensen, Jesper Bo Damm

    2002-01-01

    We report the application of the polarization control method for the UV writing of advanced fiber Bragg gratings (FBG). We demonstrate the strength of the new method for different apodization profiles, including the Sinc-profile and two designs for dispersion-free square filters. The method has...

  10. Load Coefficients on Grates used for Wind Turbine Access Platforms

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.; Frigaard, Peter

    In this report is presented the results of tests carried out at Dept. of Civil Engineering, Aalborg University (AAU) on behalf of DONG Energy A/S and Vattenfall A/S, Denmark. The objective of the tests was to investigate the load coefficient on different platform grates and a solid plate for desi...

  11. Tunable and reconfigurable multi-tap microwave photonic filter based on dynamic Brillouin gratings in fibers.

    Science.gov (United States)

    Sancho, J; Primerov, N; Chin, S; Antman, Y; Zadok, A; Sales, S; Thévenaz, L

    2012-03-12

    We propose and experimentally demonstrate new architectures to realize multi-tap microwave photonic filters, based on the generation of a single or multiple dynamic Brillouin gratings in polarization maintaining fibers. The spectral range and selectivity of the proposed periodic filters is extensively tunable, simply by reconfiguring the positions and the number of dynamic gratings along the fiber respectively. In this paper, we present a complete analysis of three different configurations comprising a microwave photonic filter implementation: a simple notch-type Mach-Zehnder approach with a single movable dynamic grating, a multi-tap performance based on multiple dynamic gratings and finally a stationary grating configuration based on the phase modulation of two counter-propagating optical waves by a common pseudo-random bit sequence (PRBS).

  12. A rotated transmission grating spectrometer for detecting spectral separation of doublet Na

    Energy Technology Data Exchange (ETDEWEB)

    Santosa, Ignatius Edi [Department of Physics Education, Sanata Dharma University, Paingan Maguwohardjo Depok Sleman, Yogyakarta 55281, Indonesia edi@usd.ac.id (Indonesia)

    2015-04-16

    Transmission gratings are usually used in a spectrometer for measuring the wavelength of light. In the common design, the position of the grating is perpendicular to the incident light. In order to increase the angular dispersion, in contrary to the common design, in this experiment the transmission grating was rotated. Due to the non-zero incident angle, the diffracted light was shifted. This rotated transmission grating spectrometer has been used to determine the separation of doublet Na. In this experiment, the diffraction angle was measured at various incident angles. The spectral separation of doublet Na was identified from the difference in the diffraction angle of two spectral lines. This spectral separation depends on the incident angle, the grating constant and the order of diffraction. As the effect of increasing the incident angle, a significant increase of the spectral separation can be achieved up to three fold.

  13. A rotated transmission grating spectrometer for detecting spectral separation of doublet Na

    International Nuclear Information System (INIS)

    Santosa, Ignatius Edi

    2015-01-01

    Transmission gratings are usually used in a spectrometer for measuring the wavelength of light. In the common design, the position of the grating is perpendicular to the incident light. In order to increase the angular dispersion, in contrary to the common design, in this experiment the transmission grating was rotated. Due to the non-zero incident angle, the diffracted light was shifted. This rotated transmission grating spectrometer has been used to determine the separation of doublet Na. In this experiment, the diffraction angle was measured at various incident angles. The spectral separation of doublet Na was identified from the difference in the diffraction angle of two spectral lines. This spectral separation depends on the incident angle, the grating constant and the order of diffraction. As the effect of increasing the incident angle, a significant increase of the spectral separation can be achieved up to three fold

  14. Model based control of grate combustion; Modellbaserad roststyrning

    Energy Technology Data Exchange (ETDEWEB)

    Broden, Henrik; Kjellstroem, Bjoern; Niklasson, Fredrik; Boecher Poulsen, Kristian

    2006-12-15

    An existing dynamic model for grate combustion has been further developed. The model has been used for studies of possible advantages that can be gained from utilisation of measurements of grate temperatures and fuel bed height for control of a boiler after disturbances caused by varying fuel moisture and fuel feeding. The objective was to asses the possibilities to develop a control system that would adjust for such disturbances quicker than measurements of steam output and oxygen in the exhaust. The model is based on dividing the fuel bed into three layers, where the different layers include fuel being dried, fuel being pyrolysed and char reacting with oxygen. The grate below the fuel bed is also considered. A mass balance, an energy balance and a volume balance is considered for each layer in 22 cells along the grate. The energy balances give the temperature distribution and the volume balances the bed height. The earlier version of the model could not handle layers that are consumed. This weakness has now been eliminated. Comparisons between predicted grate temperatures and measurements in a 25 MW boiler fuelled with biofuel have been used for validation of the model. The comparisons include effects of variations in primary air temperature, fuel moisture and output power. The model shows good agreement with observations for changes in the air temperature but the ability of the model to predict effects of changed fuel moisture is difficult to judge since the steam dome pressure control caused simultaneous changes of the primary air flow, which probably had a larger influence on the grate temperature. A linearised, tuned and reduced version of the model was used for design of a linear quadratic controller. This was used for studies of advantages of using measurements of grate temperatures and bed height for control of pusher velocity, grate speed, primary air flow and air temperature after disturbances of fuel moisture and fuel flow. Measurements of the grate

  15. Study on talbot pattern for grating interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Ju; Oh, Oh Sung; Lee, Seung Wook [Dept. of School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of); Kim, Jong Yul [Neutron Instrument Division, Korea Atomic Energy Reserch Institute, Daejeon (Korea, Republic of)

    2015-04-15

    One of properties which X-ray and Neutron can be applied nondestructive test is penetration into the object with interaction leads to decrease in intensity. X-ray interaction with the matter caused by electrons, Neutron caused by atoms. They share applications in nondestructive test area because of their similarities of interaction mechanism. Grating interferometer is the one of applications produces phase contrast image and dark field image. It is defined by Talbot interferometer and Talbot-Lau interferometer according to Talbot effect and Talbot-Lau effect respectively. Talbot interferometer works with coherence beam like X-ray, and Talbot-Lau has an effect with incoherence beam like Neutron. It is important to expect the interference in grating interferometer compared normal nondestructive system. In this paper, simulation works are conducted according to Talbot and Talbot-Lau interferometer in case of X-ray and Neutron. Variation of interference intensity with X-ray and Neutron based on wave theory is constructed and calculate elements consist the system. Additionally, Talbot and Talbot-Lau interferometer is simulated in different kinds of conditions.

  16. Varied line-space gratings and applications

    International Nuclear Information System (INIS)

    McKinney, W.R.

    1991-01-01

    This paper presents a straightforward analytical and numerical method for the design of a specific type of varied line-space grating system. The mathematical development will assume plane or nearly-plane spherical gratings which are illuminated by convergent light, which covers many interesting cases for synchrotron radiation. The gratings discussed will have straight grooves whose spacing varies across the principal plane of the grating. Focal relationships and formulae for the optical grating-pole-to-exist-slit distance and grating radius previously presented by other authors will be derived with a symbolic algebra system. It is intended to provide the optical designer with the tools necessary to design such a system properly. Finally, some possible advantages and disadvantages for application to synchrotron to synchrotron radiation beamlines will be discussed

  17. Immunological status of different categories of population after Chernobyl accident

    International Nuclear Information System (INIS)

    Chumak, A.A.; Bazyka, D.A.; Minchenko, J.N.

    1997-01-01

    Investigation of immune status of the victims of the Chernobyl Nuclear Power Plant (NPP) accident irradiated in different doses was performed. Acute postradiation immunodeficiency in heavily exposed persons was changed in 6-24 months to the 5-7 year period of restitution and the latter was succeeded by normalization of CD3+, CD+, CD11+ cell count and serum IgG and IgA content in certain patients, while the others revealed immunologic deficiency of the mixed type. HLA-antigenic combinations connected to the increased radiosensitivity were found out. Elaboration of in vitro tests for surface antigens expression in response to thymic peptides allowed to make adequate immunocorrection if needed. (author)

  18. Identifying Gender Differences in an Australian Youth Offender Population

    Directory of Open Access Journals (Sweden)

    Stephane M. Shepherd

    2013-06-01

    Full Text Available The study examined gender differences in risk factors for violence in a sample of 213 male and female youths held in Youth Justice Centres in Victoria, Australia. Although violence risk factors are considered to be commensurate across gender, a growing body of international literature is categorizing gender-specific criminal trajectories. The study aimed to investigate this concept in an Australian juvenile context. Through the use of a widely validated youth violence risk assessment inventory, the prevalence of salient risk items was compared across gender. Young female offenders were found to present with higher levels of family dysfunction, peer rejection and self-injurious behavior reflecting international female offending pathways literature.

  19. Responses to stress of Caenorhabditis elegans populations with different reproductive strategies

    NARCIS (Netherlands)

    Alda Alvarez, O.; Jager, T.; Kooijman, S.A.L.M.; Kammenga, J.E.

    2005-01-01

    Hermaphroditic and gonochoric reproduction are essentially different reproductive strategies that may lead to diverging population responses to adverse environmental conditions. Each strategy implies different physiological mechanisms, which affect life-history traits and represent different ways of

  20. Responses to stress of Caenorhabditis elegans populations with different reproductive strategies.

    NARCIS (Netherlands)

    Alda Alvarez, O.; Jager, D.T.; Kooijman, S.A.L.M.; Kammenga, J.E.

    2005-01-01

    1. Hermaphroditic and gonochoric reproduction are essentially different reproductive strategies that may lead to diverging population responses to adverse environmental conditions. Each strategy implies different physiological mechanisms, which affect life-history traits and represent different ways

  1. Do eating habits of the population living in Roma settlements differ from those of the majority population in Slovakia?

    Science.gov (United States)

    Hijová, Emília; Gecková, Andrea Madarasová; Babinská, Ingrid

    2014-03-01

    Living in Roma settlements is associated with worse health in comparison with the majority population; this might be partially explained by socioeconomic disadvantages as well as cultural differences, including lifestyle. Eating habits represent an important part of lifestyle closely related to primary causes of morbidity and mortality, such as cardiovascular diseases, metabolic diseases or cancers. The eating habits of the population living in Roma settlements in comparison with those of the majority population were explored using the cross-sectional epidemiological HepaMeta study conducted in 2011. A representative sample of Roma (n = 452, mean age = 34.7; 35.2% men) and non-Roma (n = 403, mean age = 33.5; 45.9% men) aged 18-55 years living in the Kosice region were asked about breakfasting and recent consumption of fruits, vegetables, dairy products, meat products, meat, farinaceous dishes, and soft drinks. A logistic regression model was used separately for male and female participants. The population living in Roma settlements reported the recent consumption of fruit, vegetables and dairy products significantly less frequently in comparison with the majority population. Moreover, Roma females, in comparison with non-Roma females, reported significantly more frequently the consumption of meat and soft drinks. No differences were found between Roma and non-Roma in the consumption of meat products and farinaceous dishes. The population living in Roma settlements reported more frequently unhealthy eating habits in comparison with the majority population; this might contribute to worse health status of this population. The differences might be attributed to cultural differences between ethnic as well as socioeconomic groups, reduced availability of certain food items due to segregation or poverty and lower health literacy.

  2. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu

    2012-05-02

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  3. EUV properties of two diffraction gratings

    International Nuclear Information System (INIS)

    Cotton, D.; Chakrabarti, S.; Edelstein, J.; Pranke, J.; Christensen, A.B.

    1988-01-01

    The efficiency and scattering characteristics of a mechanically ruled grating (MRG) and a holographically ruled grating (HRG) are presented. One of these gratings will be employed in the Extreme Ultraviolet Spectrometer, an instrument of the Remote Atmospheric and Ionospheric Detector System to be flown aboard a TIROS satellite in 1991. The HRG showed much less Lyman alpha scattering, while the MRG had the better efficiency over most of the spectral range covered. 8 refs

  4. Nanoporous Polymeric Grating-Based Biosensors

    KAUST Repository

    Gao, Tieyu; Hsiao, Vincent; Zheng, Yue Bing; Huang, Tony Jun

    2012-01-01

    We demonstrate the utilization of an interferometrically created nanoporous polymeric gratings as a platform for biosensing applications. Aminopropyltriethoxysilane (APTES)-functionalized nanoporous polymeric gratings was fabricated by combining holographic interference patterning and APTES-functionalization of pre-polymer syrup. The successful detection of multiple biomolecules indicates that the biofunctionalized nanoporous polymeric gratings can act as biosensing platforms which are label-free, inexpensive, and applicable as high-throughput assays. Copyright © 2010 by ASME.

  5. Fibre gratings for high temperature sensor applications

    Science.gov (United States)

    Canning, J.; Sommer, K.; Englund, M.

    2001-07-01

    Phosphosilicate fibre gratings can be stabilized at temperatures in excess of 500 °C for sensor applications by optimizing thermal and UV presensitization recipes. Furthermore, the use of 193 nm presensitization prevents the formation of OH absorption bands, extending the use of fibre gratings across the entire wavelength spectrum. Gratings for operation at 700 °C retaining up to 70% reflectivity after 30 min are demonstrated.

  6. Photosynthetic plasticity of populations of Heliotropium curassavicum L. originating from differing thermal regimes.

    Science.gov (United States)

    Mooney, H A

    1980-01-01

    Plants of the widely distributed species Heliotropium curassavicum L. have a large photosynthetic acclimation potential to temperature. There are, however, some differences among the acclimation potentials of populations occupying dissimilar thermal regimes. Plants of populations originating from a cool maritime climate have a greater acclimation potential than plants of populations originating from a desert habitat, which is characterized by large seasonal changes in temperature.

  7. Plasmonic Optical Fiber-Grating Immunosensing: A Review.

    Science.gov (United States)

    Guo, Tuan; González-Vila, Álvaro; Loyez, Médéric; Caucheteur, Christophe

    2017-11-26

    Plasmonic immunosensors are usually made of a noble metal (in the form of a film or nanoparticles) on which bioreceptors are grafted to sense analytes based on the antibody/antigen or other affinity mechanism. Optical fiber configurations are a miniaturized counterpart to the bulky Kretschmann prism and allow easy light injection and remote operation. To excite a surface plasmon (SP), the core-guided light is locally outcoupled. Unclad optical fibers were the first configurations reported to this end. Among the different architectures able to bring light in contact with the surrounding medium, a great quantity of research is today being conducted on metal-coated fiber gratings photo-imprinted in the fiber core, as they provide modal features that enable SP generation at any wavelength, especially in the telecommunication window. They are perfectly suited for use with cost-effective high-resolution interrogators, allowing both a high sensitivity and a low limit of detection to be reached in immunosensing. This paper will review recent progress made in this field with different kinds of gratings: uniform, tilted and eccentric short-period gratings as well as long-period fiber gratings. Practical cases will be reported, showing that such sensors can be used in very small volumes of analytes and even possibly applied to in vivo diagnosis.

  8. High-sensitivity bend angle measurements using optical fiber gratings.

    Science.gov (United States)

    Rauf, Abdul; Zhao, Jianlin; Jiang, Biqiang

    2013-07-20

    We present a high-sensitivity and more flexible bend measurement method, which is based on the coupling of core mode to the cladding modes at the bending region in concatenation with optical fiber grating serving as band reflector. The characteristics of a bend sensing arm composed of bending region and optical fiber grating is examined for different configurations including single fiber Bragg grating (FBG), chirped FBG (CFBG), and double FBGs. The bend loss curves for coated, stripped, and etched sections of fiber in the bending region with FBG, CFBG, and double FBG are obtained experimentally. The effect of separation between bending region and optical fiber grating on loss is measured. The loss responses for single FBG and CFBG configurations are compared to discover the effectiveness for practical applications. It is demonstrated that the sensitivity of the double FBG scheme is twice that of the single FBG and CFBG configurations, and hence acts as sensitivity multiplier. The bend loss response for different fiber diameters obtained through etching in 40% hydrofluoric acid, is measured in double FBG scheme that resulted in a significant increase in the sensitivity, and reduction of dead-zone.

  9. Plasmonic Optical Fiber-Grating Immunosensing: A Review

    Directory of Open Access Journals (Sweden)

    Tuan Guo

    2017-11-01

    Full Text Available Plasmonic immunosensors are usually made of a noble metal (in the form of a film or nanoparticles on which bioreceptors are grafted to sense analytes based on the antibody/antigen or other affinity mechanism. Optical fiber configurations are a miniaturized counterpart to the bulky Kretschmann prism and allow easy light injection and remote operation. To excite a surface plasmon (SP, the core-guided light is locally outcoupled. Unclad optical fibers were the first configurations reported to this end. Among the different architectures able to bring light in contact with the surrounding medium, a great quantity of research is today being conducted on metal-coated fiber gratings photo-imprinted in the fiber core, as they provide modal features that enable SP generation at any wavelength, especially in the telecommunication window. They are perfectly suited for use with cost-effective high-resolution interrogators, allowing both a high sensitivity and a low limit of detection to be reached in immunosensing. This paper will review recent progress made in this field with different kinds of gratings: uniform, tilted and eccentric short-period gratings as well as long-period fiber gratings. Practical cases will be reported, showing that such sensors can be used in very small volumes of analytes and even possibly applied to in vivo diagnosis.

  10. Comparison of Y-STR polymorphisms in three different Slovak population groups.

    Science.gov (United States)

    Petrejcíková, Eva; Siváková, Daniela; Soták, Miroslav; Bernasovská, Jarmila; Bernasovský, Ivan; Rebała, Krzysztof; Boronová, Iveta; Bôziková, Alexandra; Sovicová, Adriana; Gabriková, Dana; Maceková, Sona; Svícková, Petra; Carnogurská, Jana

    2010-01-01

    Eleven Y-chromosomal microsatellite loci included in the Powerplex Y multiplex kit were analyzed in different Slovak population samples: Habans (n = 39), Romanies (n = 100) and Slovak Caucasian (n = 148) individuals, respectively, from different regions of Slovakia. The analysis of molecular variance between populations indicated that 89.27% of the haplotypic variations were found within populations and only 10.72% between populations (Fst = 0.1027; p = 0.0000). The haplotype diversities were ranging from 0.9258 to 0.9978, and indicated a high potential for differentiating between male individuals. The study reports differences in allele frequencies between the Romanies, Habans and Slovak Caucasian men. Selected loci showed that both the Romany and Haban population belonged to endogamous and relatively small founder population groups, which developed in relatively reproductive isolated groups surrounded by the Slovak Caucasian population.

  11. Sub-wavelength grating structure on the planar waveguide (Conference Presentation)

    Science.gov (United States)

    Qing-Song, Zhu; Sheng-Hui, Chen

    2016-10-01

    Making progress in recent years, with the technology of the grating, the grating period can be reduced to shrink the size of the light coupler on a waveguide. The working wavelength of the light coupler can be in the range from the near-infrared to visible. In this study , we used E-gun evaporation system with ion-beam-assisted deposition system to fabricate bottom cladding (SiO2), guiding layer (Ta2O5) and Distributed Bragg Reflector(DBR) of the waveguide on the silicon substrate. Electron-beam lithography is used to make sub-wavelength gratings and reflector grating on the planar waveguide which is a coupling device on the guiding layer. The best fabrication parameters were analyzed to deposit the film. The exposure and development times also influenced to fabricate the grating quality. The purpose is to reduce the device size and enhance coupling efficiency which maintain normal incidence of the light . We designed and developed the device using the Finite-Difference Time-Domain (FDTD) method. The grating period, depth, fill factor, film thickness, Distributed Bragg Reflector(DBR) numbers and reflector grating period have been discussed to enhance coupling efficiency and maintained normal incidence of the light. According to the simulation results, when the wavelength is 1300 nm, the coupling grating period is 720 nm and the Ta2O5 film is 460 nm with 360 nm of reflector grating period and 2 layers of Distributed Bragg Reflector, which had the optimum coupling efficiency and normal incidence angle. In the measurement, We successfully measured the TE wave coupling efficiency of the photoresist grating coupling device.

  12. Grating exchange system of independent mirror supported by floating rotary stage

    Science.gov (United States)

    Zhang, Jianhuan; Tao, Jin; Liu, Yan; Nan, Yan

    2015-10-01

    The performance of The Grating Exchange System can satisfy the Thirty Meter Telescope - TMT for astronomical observation WFOS index requirements and satisfy the requirement of accuracy in the grating exchange. It is used to install in the MOBIE and a key device of MOBIE. The Wide Field Optical Spectrograph (WFOS) is one of the three first-light observing capabilities selected by the TMT Science Advisory Committee. The Multi-Object Broadband Imaging Echellette (MOBIE) instrument design concept has been developed to address the WFOS requirements as described in the TMT Science-Based Requirements Document (SRD). The Grating Exchange System uses a new type of separate movement way of three grating devices and a mirror device. Three grating devices with a mirror are able to achieve independence movement. This kind of grating exchange system can effectively solve the problem that the volume of the grating change system is too large and that the installed space of MOBIE instruments is too limit. This system adopts the good stability, high precision of rotary stage - a kind of using air bearing (Air bearing is famous for its ultra-high precision, and can meet the optical accuracy requirement) and rotation positioning feedback gauge turntable to support grating device. And with a kind of device which can carry greater weight bracket fixed on the MOBIE instrument, with two sets of servo motor control rotary stage and the mirror device respectively. And we use the control program to realize the need of exercising of the grating device and the mirror device. Using the stress strain analysis software--SolidWorks for stress and strain analysis of this structure. And then checking the structure of the rationality and feasibility. And prove that this system can realize the positioning precision under different working conditions can meet the requirements of imaging optical grating diffraction efficiency and error by the calculation and optical performance analysis.

  13. Biosensing with optical fiber gratings

    Science.gov (United States)

    Chiavaioli, Francesco; Baldini, Francesco; Tombelli, Sara; Trono, Cosimo; Giannetti, Ambra

    2017-06-01

    Optical fiber gratings (OFGs), especially long-period gratings (LPGs) and etched or tilted fiber Bragg gratings (FBGs), are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI) change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength) as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors), and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

  14. Biosensing with optical fiber gratings

    Directory of Open Access Journals (Sweden)

    Chiavaioli Francesco

    2017-06-01

    Full Text Available Optical fiber gratings (OFGs, especially long-period gratings (LPGs and etched or tilted fiber Bragg gratings (FBGs, are playing an increasing role in the chemical and biochemical sensing based on the measurement of a surface refractive index (RI change through a label-free configuration. In these devices, the electric field evanescent wave at the fiber/surrounding medium interface changes its optical properties (i.e. intensity and wavelength as a result of the RI variation due to the interaction between a biological recognition layer deposited over the fiber and the analyte under investigation. The use of OFG-based technology platforms takes the advantages of optical fiber peculiarities, which are hardly offered by the other sensing systems, such as compactness, lightness, high compatibility with optoelectronic devices (both sources and detectors, and multiplexing and remote measurement capability as the signal is spectrally modulated. During the last decade, the growing request in practical applications pushed the technology behind the OFG-based sensors over its limits by means of the deposition of thin film overlays, nanocoatings, and nanostructures, in general. Here, we review efforts toward utilizing these nanomaterials as coatings for high-performance and low-detection limit devices. Moreover, we review the recent development in OFG-based biosensing and identify some of the key challenges for practical applications. While high-performance metrics are starting to be achieved experimentally, there are still open questions pertaining to an effective and reliable detection of small molecules, possibly up to single molecule, sensing in vivo and multi-target detection using OFG-based technology platforms.

  15. Mathematical modeling and experimental study of biomass combustion in a thermal 108 MW grate-fired boiler

    DEFF Research Database (Denmark)

    Yin, Chungen; Rosendahl, Lasse; Kær, Søren K.

    2008-01-01

    Grate boilers are widely used to fire biomass for heat and power production. However grate-firing systems are often reported to have relatively high un-burnout, low efficiency and high emissions, and need to be optimized and modernized. This paper presents the efforts towards a reliable baseline...... computational fluid dynamics (CFD) model for an industrial biomass-fired grate boiler, which can be used for diagnosis and optimization of the grate boiler as well as design of new grate boilers. First, based on the design conditions, a thorough sensitivity analysis is done to evaluate the relative importance...... of different factors in CFD analysis of the grate boiler. In a late stage, a two-day measuring campaign is carried out to measure the gas temperatures and gas concentrations in the boiler using a fiber optic probe connected to a Fourier transform infrared (FTIR) spectrometer. A baseline model is then defined...

  16. [Research on demodulation system for human body temperature measurement of intelligent clothing based on arrayed waveguide grating].

    Science.gov (United States)

    Yu, Xiao-gang; Miao, Chang-yun; Li, Hong-qiang; Li, En-bang; Liu, Zhi-hui; Wei, Ke-jia

    2012-08-01

    A system for demodulating distributed fiber Bragg grating sensors of the intelligent clothing was researched and realized, which is based on arrayed waveguide grating. The principle of demodulation method based on arrayed waveguide grating was analyzed, intensity--demodulating method was used to interrogate the wavelength of the fiber Bragg grating based on the building up of an experimental platform, and demodulation experiment of pre and post series of fiber Bragg grating was completed. The results show that the wavelength demodulation of the system has high linearity for fiber Bragg grating, the system gives a wavelength accuracy of 0.001 nm, and demodulation error caused by crosstalk between different sensors is 0.0005 nm. The measurement error of human body temperature is +/- 0.16 degrees C. It can be applied to the human body temperature measurement.

  17. Running gratings in photoconductive materials

    DEFF Research Database (Denmark)

    Kukhtarev, N. V.; Kukhtareva, T.; Lyuksyutov, S. F.

    2005-01-01

    Starting from the three-dimensional version of a standard photorefractive model (STPM), we obtain a reduced compact Set of equations for an electric field based on the assumption of a quasi-steady-state fast recombination. The equations are suitable for evaluation of a current induced by running...... gratings at small-contrast approximation and also are applicable for the description of space-charge wave domains. We discuss spatial domain and subharmonic beam formation in bismuth silicon oxide (BSO) crystals in the framework of the small-contrast approximation of STPM. The experimental results...

  18. Differences in oral temperature and body shape in two populations with different propensities for obesity

    DEFF Research Database (Denmark)

    Vozarova, B; Weyer, C; Bogardus, C

    2002-01-01

    Body temperature is a function of heat production and heat dissipation. Substantial interindividual variability has been reported in healthy humans. We hypothesized that Pima Indians, a population with a high prevalence of abdominal obesity, may have a lower surface area relative to volume, that is...

  19. Variability of haloxylon ammodendron (C. A. Mey) bunge populations from different habitats

    International Nuclear Information System (INIS)

    Lv, C.

    2015-01-01

    Haloxylon ammodendron (C.A. Mey) Bunge occupies a wide range of different habitats in north-west China. The aim of this study was to quantify variation in population growth characteristics of H. ammodendron from different sites and to relate this variation to different environmental conditions. To this end, 6 populations with visible differences were chosen and a range of morphological as well as seed-related characteristics like density, height, crown, basal diameter, seed mass, 1000 seed weight, seed number, seed diameter and germination rate were measured. The variations in the averages of overall traits were explained. The differences between-populations were 33 percentage, whereas those within population were 67 percentage. The largest variation was detected in morphological-related traits between-populations (38 percentage). In particular, the density, height, 1000 seed weight and germination rate differed strongly between populations. The population growth characteristics were closely related to the soil property at the sites of origin. The soil property can explain most of the variations in the morphological-related traits. They were concluded that the diversity of population growth characteristics in different habitats provides the potential of population reproduction and the protection of original habitats is extremely important. (author)

  20. Differences in sensitivity to the fungal pathogen Batrachochytrium dendrobatidis among amphibian populations.

    Science.gov (United States)

    Bradley, Paul W; Gervasi, Stephanie S; Hua, Jessica; Cothran, Rickey D; Relyea, Rick A; Olson, Deanna H; Blaustein, Andrew R

    2015-10-01

    Contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. For example, the infectious fungal pathogen Batrachochytrium dendrobatidis (Bd) is associated with worldwide amphibian population declines and extinctions. Sensitivity to Bd varies with species, season, and life stage. However, there is little information on whether sensitivity to Bd differs among populations, which is essential for understanding Bd-infection dynamics and for formulating conservation strategies. We experimentally investigated intraspecific differences in host sensitivity to Bd across 10 populations of wood frogs (Lithobates sylvaticus) raised from eggs to metamorphosis. We exposed the post-metamorphic wood frogs to Bd and monitored survival for 30 days under controlled laboratory conditions. Populations differed in overall survival and mortality rate. Infection load also differed among populations but was not correlated with population differences in risk of mortality. Such population-level variation in sensitivity to Bd may result in reservoir populations that may be a source for the transmission of Bd to other sensitive populations or species. Alternatively, remnant populations that are less sensitive to Bd could serve as sources for recolonization after epidemic events. © 2015 Society for Conservation Biology.

  1. PiC code KARAT simulations of Coherent THz Smith-Purcell Radiation from diffraction gratings of various profiles

    International Nuclear Information System (INIS)

    Artyomov, K P; Ryzhov, V V; Potylitsyn, A P; Sukhikh, L G

    2017-01-01

    Generation of coherent THz Smith-Purcell radiation by single electron bunch or multi-bunched electron beam was simulated for lamellar, sinusoidal and echelette gratings. The dependences of the CSPR intensity of the corrugation gratings depth were investigated. The angular and spectral characteristics of the CSPR for different profiles of diffraction gratings were obtained. It is shown that in the case of femtosecond multi-bunched electron beam with 10 MeV energy sinusoidal grating with period 292 μm and groove depth 60 μm has the uniform angular distribution with high radiation intensity. (paper)

  2. Competition between Plant-Populations with Different Rooting Depths. 2. Pot Experiments

    NARCIS (Netherlands)

    Berendse, F.

    1981-01-01

    In a previous paper in this series a model was proposed lor the competition between plant populations with different rooting depths. This model predicts that in mixtures of plant populations with different rooting depths the Relative Yield Total will exceed unity. Secondly it predicts that in these

  3. Differences in mating behavior between two allopatric populations of a Neotropical scorpion.

    Science.gov (United States)

    Olivero, Paola A; Mattoni, Camilo I; Peretti, Alfredo V

    2017-08-01

    Courtship and mating behavior generally evolve rapidly in diverging populations and species. The adaptation to different environments may cause behavioral divergence in characteristics involved in mate choice. Our objective in this study was to compare the sexual behavior of two distant populations of the scorpion Bothriurus bonariensis. This species has a broad distribution in South America, inhabiting Central Argentina, Uruguay and south-eastern Brazil. It is known that in this species there is a divergence in morphological patterns (body size, coloration, allometry and fluctuating asymmetry indexes) among distant populations. Considering the differences in environmental conditions between localities, we compare the sexual behavior in intra-population and inter-population matings from Central Argentina and southern Uruguay populations. We found significant differences in mating patterns, including differences in the frequency and duration of important stimulatory courtship behaviors. In addition, most inter-population matings were unsuccessful. In this framework, the differences in reproductive behavior could indicate reproductive isolation between these populations, which coincides with their already known morphological differences. This is the first study comparing the sexual behavior of allopatric populations of scorpions; it provides new data about the degree of intraspecific geographical divergence in the sexual behavior of B. bonariensis. Copyright © 2017 Elsevier GmbH. All rights reserved.

  4. Analysis of higher order harmonics with holographic reflection gratings

    Science.gov (United States)

    Mas-Abellan, P.; Madrigal, R.; Fimia, A.

    2017-05-01

    Silver halide emulsions have been considered one of the most energetic sensitive materials for holographic applications. Nonlinear recording effects on holographic reflection gratings recorded on silver halide emulsions have been studied by different authors obtaining excellent experimental results. In this communication specifically we focused our investigation on the effects of refractive index modulation, trying to get high levels of overmodulation that will produce high order harmonics. We studied the influence of the overmodulation and its effects on the transmission spectra for a wide exposure range by use of 9 μm thickness films of ultrafine grain emulsion BB640, exposed to single collimated beams using a red He-Ne laser (wavelength 632.8 nm) with Denisyuk configuration obtaining a spatial frequency of 4990 l/mm recorded on the emulsion. The experimental results show that high overmodulation levels of refractive index produce second order harmonics with high diffraction efficiency (higher than 75%) and a narrow grating bandwidth (12.5 nm). Results also show that overmodulation produce diffraction spectra deformation of the second order harmonic, transforming the spectrum from sinusoidal to approximation of square shape due to very high overmodulation. Increasing the levels of overmodulation of refractive index, we have obtained higher order harmonics, obtaining third order harmonic with diffraction efficiency (up to 23%) and narrowing grating bandwidth (5 nm). This study is the first step to develop a new easy technique to obtain narrow spectral filters based on the use of high index modulation reflection gratings.

  5. All-silicon nanorod-based Dammann gratings.

    Science.gov (United States)

    Li, Zile; Zheng, Guoxing; He, Ping'An; Li, Song; Deng, Qiling; Zhao, Jiangnan; Ai, Yong

    2015-09-15

    Established diffractive optical elements (DOEs), such as Dammann gratings, whose phase profile is controlled by etching different depths into a transparent dielectric substrate, suffer from a contradiction between the complexity of fabrication procedures and the performance of such gratings. In this Letter, we combine the concept of geometric phase and phase modulation in depth, and prove by theoretical analysis and numerical simulation that nanorod arrays etched on a silicon substrate have a characteristic of strong polarization conversion between two circularly polarized states and can act as a highly efficient half-wave plate. More importantly, only by changing the orientation angles of each nanorod can the arrays control the phase of a circularly polarized light, cell by cell. With the above principle, we report the realization of nanorod-based Dammann gratings reaching diffraction efficiencies of 50%-52% in the C-band fiber telecommunications window (1530-1565 nm). In this design, uniform 4×4 spot arrays with an extending angle of 59°×59° can be obtained in the far field. Because of these advantages of the single-step fabrication procedure, accurate phase controlling, and strong polarization conversion, nanorod-based Dammann gratings could be utilized for various practical applications in a range of fields.

  6. Estimating the contribution of genetic variants to difference in incidence of disease between population groups.

    Science.gov (United States)

    Moonesinghe, Ramal; Ioannidis, John P A; Flanders, W Dana; Yang, Quanhe; Truman, Benedict I; Khoury, Muin J

    2012-08-01

    Genome-wide association studies have identified multiple genetic susceptibility variants to several complex human diseases. However, risk-genotype frequency at loci showing robust associations might differ substantially among different populations. In this paper, we present methods to assess the contribution of genetic variants to the difference in the incidence of disease between different population groups for different scenarios. We derive expressions for the contribution of a single genetic variant, multiple genetic variants, and the contribution of the joint effect of a genetic variant and an environmental factor to the difference in the incidence of disease. The contribution of genetic variants to the difference in incidence increases with increasing difference in risk-genotype frequency, but declines with increasing difference in incidence between the two populations. The contribution of genetic variants also increases with increasing relative risk and the contribution of joint effect of genetic and environmental factors increases with increasing relative risk of the gene-environmental interaction. The contribution of genetic variants to the difference in incidence between two populations can be expressed as a function of the population attributable risks of the genetic variants in the two populations. The contribution of a group of genetic variants to the disparity in incidence of disease could change considerably by adding one more genetic variant to the group. Any estimate of genetic contribution to the disparity in incidence of disease between two populations at this stage seems to be an elusive goal.

  7. Estimating the contribution of genetic variants to difference in incidence of disease between population groups

    Science.gov (United States)

    Moonesinghe, Ramal; Ioannidis, John PA; Flanders, W Dana; Yang, Quanhe; Truman, Benedict I; Khoury, Muin J

    2012-01-01

    Genome-wide association studies have identified multiple genetic susceptibility variants to several complex human diseases. However, risk-genotype frequency at loci showing robust associations might differ substantially among different populations. In this paper, we present methods to assess the contribution of genetic variants to the difference in the incidence of disease between different population groups for different scenarios. We derive expressions for the contribution of a single genetic variant, multiple genetic variants, and the contribution of the joint effect of a genetic variant and an environmental factor to the difference in the incidence of disease. The contribution of genetic variants to the difference in incidence increases with increasing difference in risk-genotype frequency, but declines with increasing difference in incidence between the two populations. The contribution of genetic variants also increases with increasing relative risk and the contribution of joint effect of genetic and environmental factors increases with increasing relative risk of the gene–environmental interaction. The contribution of genetic variants to the difference in incidence between two populations can be expressed as a function of the population attributable risks of the genetic variants in the two populations. The contribution of a group of genetic variants to the disparity in incidence of disease could change considerably by adding one more genetic variant to the group. Any estimate of genetic contribution to the disparity in incidence of disease between two populations at this stage seems to be an elusive goal. PMID:22333905

  8. Double-Grating Displacement Structure for Improving the Light Extraction Efficiency of LEDs

    Directory of Open Access Journals (Sweden)

    Zhibin Wang

    2012-01-01

    Full Text Available To improve the light extraction efficiency of light-emitting diodes (LEDs, grating patterns were etched on GaN and silver film surfaces. The grating-patterned surface etching enabled the establishment of an LED model with a double-grating displacement structure that is based on the surface plasmon resonance principle. A numerical simulation was conducted using the finite difference time domain method. The influence of different grating periods for GaN surface and silver film thickness on light extraction efficiency was analyzed. The light extraction efficiency of LEDs was highest when the grating period satisfied grating coupling conditions. The wavelength of the highest value was also close to the light wavelength of the medium. The plasmon resonance frequencies on both sides of the silver film were affected by silver film thickness. With increasing film thickness, plasmon resonance frequency tended toward the same value and light extraction efficiency reached its maximum. When the grating period for the GaN surface was 365 nm and the silver film thickness was 390 nm, light extraction efficiency reached a maximum of 55%.

  9. A novel method for length of chirped fiber Bragg grating sensor

    Science.gov (United States)

    Li, Zhenwei; Wei, Peng; Liu, Taolin

    2018-03-01

    Length of chirped fiber Bragg grating sensor is very important for detonation velocity. Different from other ways, we proposed a novel method based on the optical frequency domain reflection theory to measure the length of chirped fiber grating sensor in non-contact condition. This method adopts a tunable laser source to provide wavelength scanning laser, which covers the Full Width at Half Maximum of spectrum of the chirped fiber Bragg grating sensor. A Michelson interferometer is used to produce optical interference signal. Finally, the grating's length is attainable by distance domain signal. In theory, length resolution of chirped fiber Bragg grating sensor could be 0.02 mm. We perform a series of length measurement experiments for chirped fiber grating sensor, including comparison experiments with hot-tip method. And the experiment results show that the novel method could accurately measure the length of chirped fiber Bragg grating sensors, and the length differences between the optical frequency domain reflection method and the hot-tip probe method are very small.

  10. 21 CFR 133.146 - Grated cheeses.

    Science.gov (United States)

    2010-04-01

    ... Products § 133.146 Grated cheeses. (a) Description. Grated cheeses is the class of foods prepared by..., and skim milk cheese for manufacturing may not be used. All cheese ingredients used are either made... ___ cheese”, the name of the cheese filling the blank. (ii) If only parmesan and romano cheeses are used and...

  11. The Flexibility of Pusher Furnace Grate

    Directory of Open Access Journals (Sweden)

    Słowik J.A.

    2016-12-01

    Full Text Available The lifetime of guide grates in pusher furnaces for heat treatment could be increased by raising the flexibility of their structure through, for example, the replacement of straight ribs, parallel to the direction of grate movement, with more flexible segments. The deformability of grates with flexible segments arranged in two orientations, i.e. crosswise (perpendicular to the direction of compression and lengthwise (parallel to the direction of compression, was examined. The compression process was simulated using SolidWorks Simulation program. Relevant regression equations were also derived describing the dependence of force inducing the grate deformation by 0.25 mm ‒ modulus of grate elasticity ‒ on the number of flexible segments in established orientations. These calculations were made in Statistica and Scilab programs. It has been demonstrated that, with the same number of segments, the crosswise orientation of flexible segments increases the grate structure flexibility in a more efficient way than the lengthwise orientation. It has also been proved that a crucial effect on the grate flexibility has only the quantity and orientation of segments (crosswise / lengthwise, while the exact position of segments changes the grate flexibility by less than 1%.

  12. Femtosecond laser pulse written Volume Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Richter Daniel

    2013-11-01

    Full Text Available Femtosecond laser pulses can be applied for structuring a wide range of ransparent materials. Here we want to show how to use this ability to realize Volume-Bragg-Gratings in various- mainly non-photosensitive - glasses. We will further present the characteristics of the realized gratings and a few elected applications that have been realized.

  13. A MANUALLY OPERATED CASSAVA GRATING MACHINE

    African Journals Online (AJOL)

    Dr Obe

    1984-09-01

    Sep 1, 1984 ... substantial losses arising from the inability of the person to hold small pieces of cassava roots for grating. Happily, there now exist various. Versions of mechanical graters which are driven by electric motors or small internal combustion engines. In fact, it may be said that cassava grating has been effectively.

  14. Plasmonic Transmission Gratings – Fabrication and Characterization

    DEFF Research Database (Denmark)

    Sierant, Aleksandra; Jany, Benedykt; Bartoszek-Bober, Dobrosława

    Surface plasmon polaritons (SPPs) are collective electron oscillations, confined at metal-dielectric interfaces. Coupling incident photons to SPPs may lead to spectrally broad field enhancement and confinement below the diffraction limit [1]. This phenomenon facilitates various applications......, including highly sensitive refractive index sensing [2], and plasmonic dipole mirrors for cold atoms [3]. Key to a successful application is a strong photon-to-SPP coupling. To this end, prism-based coupling is classically used, but this method contradicts compact device applications. An alternative...... the proposed plasmonic transmission gratings via near-field optical scanning microscopy (NSOM) and goniometric far field measurements. We support the evidence of our analyses with numerical calculations, carried out via rigorous coupled wave analysis (RCWA) and finite-difference in time-domain (FDTD...

  15. Process monitoring of glass reinforced polypropylene laminates using fiber Bragg gratings

    KAUST Repository

    Mulle, Matthieu; Wafai, Husam; Yudhanto, Arief; Lubineau, Gilles; Yaldiz, R.; Schijve, W.; Verghese, N.

    2015-01-01

    Hot-press molding of glass-fiber-reinforced polypropylene (GFPP) laminates was monitored using longitudinally and transversely embedded fiber Bragg gratings (FBGs) at different locations in unidirectional laminates. The optical sensors proved

  16. Genetic diversity in different populations of sloths assessed by DNA fingerprinting

    Directory of Open Access Journals (Sweden)

    MORAES N.

    2002-01-01

    Full Text Available In this study we analyzed a population of Bradypus torquatus with individuals originally distributed in different localities of Bahia, and two populations of B. variegatus with individuals from Bahia and São Paulo States. Using the DNA fingerprinting method, we assessed the genetic variability within and between populations. Analysis of the DNA profiles revealed genetic similarity indices ranging from 0.34 ± 0.07 to 0.87 ± 0.04. Similar low levels of genetic variability were found only in isolated mammalian populations or among related individuals. This study presents the first analyses of genetic diversity in sloth populations.

  17. Simulation Studies of the Dielectric Grating as an Accelerating and Focusing Structure

    International Nuclear Information System (INIS)

    Soong, Ken; Peralta, E.A.; Byer, R.L.; Colby, E.

    2011-01-01

    A grating-based design is a promising candidate for a laser-driven dielectric accelerator. Through simulations, we show the merits of a readily fabricated grating structure as an accelerating component. Additionally, we show that with a small design perturbation, the accelerating component can be converted into a focusing structure. The understanding of these two components is critical in the successful development of any complete accelerator. The concept of accelerating electrons with the tremendous electric fields found in lasers has been proposed for decades. However, until recently the realization of such an accelerator was not technologically feasible. Recent advances in the semiconductor industry, as well as advances in laser technology, have now made laser-driven dielectric accelerators imminent. The grating-based accelerator is one proposed design for a dielectric laser-driven accelerator. This design, which was introduced by Plettner, consists of a pair of opposing transparent binary gratings, illustrated in Fig. 1. The teeth of the gratings serve as a phase mask, ensuring a phase synchronicity between the electromagnetic field and the moving particles. The current grating accelerator design has the drive laser incident perpendicular to the substrate, which poses a laser-structure alignment complication. The next iteration of grating structure fabrication seeks to monolithically create an array of grating structures by etching the grating's vacuum channel into a fused silica wafer. With this method it is possible to have the drive laser confined to the plane of the wafer, thus ensuring alignment of the laser-and-structure, the two grating halves, and subsequent accelerator components. There has been previous work using 2-dimensional finite difference time domain (2D-FDTD) calculations to evaluate the performance of the grating accelerator structure. However, this work approximates the grating as an infinite structure and does not accurately model a

  18. Genetic variability and population structure of Plasmodium falciparum parasite populations from different malaria ecological regions of Kenya.

    Science.gov (United States)

    Ingasia, Luicer A; Cheruiyot, Jelagat; Okoth, Sheila Akinyi; Andagalu, Ben; Kamau, Edwin

    2016-04-01

    Transmission intensity, movement of human and vector hosts, biogeographical features, and malaria control measures are some of the important factors that determine Plasmodium falciparum parasite genetic variability and population structure. Kenya has different malaria ecologies which might require different disease intervention methods. Refined parasite population genetic studies are critical for informing malaria control and elimination strategies. This study describes the genetic diversity and population structure of P. falciparum parasites from the different malaria ecological zones in Kenya. Twelve multi-locus microsatellite (MS) loci previously described were genotyped in 225 P. falciparum isolates collected between 2012 and 2013 from five sites; three in lowland endemic regions (Kisumu, Kombewa, and Malindi) and two in highland, epidemic regions (Kisii and Kericho). Parasites from the lowland endemic and highland epidemic regions of western Kenya had high genetic diversity compared to coastal lowland endemic region of Kenya [Malindi]. The Kenyan parasites had a mean genetic differentiation index (FST) of 0.072 (p=0.011). The multi-locus genetic analysis of the 12 MS revealed all the parasites had unique haplotypes. Significant linkage disequilibrium (LD) was observed in all the five parasite populations. Kisumu had the most significant index of association values (0.16; pKenya after introduction of the artemether-lumefantrine is important in refining the spread of drug resistant strains and malaria transmission for more effective control and eventual elimination of malaria in Kenya. Copyright © 2015. Published by Elsevier B.V.

  19. Modeling and experiments of biomass combustion in a large-scale grate boiler

    DEFF Research Database (Denmark)

    Yin, Chungen; Rosendahl, Lasse; Kær, Søren Knudsen

    2007-01-01

    is inherently more difficult due to the complexity of the solid biomass fuel bed on the grate, the turbulent reacting flow in the combustion chamber and the intensive interaction between them. This paper presents the CFD validation efforts for a modern large-scale biomass-fired grate boiler. Modeling...... and experiments are both done for the grate boiler. The comparison between them shows an overall acceptable agreement in tendency. However at some measuring ports, big discrepancies between the modeling and the experiments are observed, mainly because the modeling-based boundary conditions (BCs) could differ...

  20. High force measurement sensitivity with fiber Bragg gratings fabricated in uniform-waist fiber tapers

    International Nuclear Information System (INIS)

    Wieduwilt, Torsten; Brückner, Sven; Bartelt, Hartmut

    2011-01-01

    Fiber Bragg gratings inscribed in the waist of tapered photosensitive fibers offer specific attractive properties for sensing applications. A small-diameter fiber reduces structural influences for imbedded fiber sensing elements. In the case of application as a force-sensing element for tensile forces, sensitivity scales inversely with the fiber cross-sectional area. It is therefore possible to increase force sensitivity by several orders of magnitude compared to Bragg grating sensors in conventionally sized fibers. Special requirements for such Bragg grating arrangements are discussed and experimental measurements for different fiber taper diameters down to 4 µm are presented

  1. The population genetics of Pseudomonas aeruginosa isolates from different patient populations exhibits high-level host specificity.

    Directory of Open Access Journals (Sweden)

    Rosa van Mansfeld

    Full Text Available OBJECTIVE: To determine whether highly prevalent P. aeruginosa sequence types (ST in Dutch cystic fibrosis (CF patients are specifically linked to CF patients we investigated the population structure of P. aeruginosa from different clinical backgrounds. We first selected the optimal genotyping method by comparing pulsed-field gel electrophoresis (PFGE, multilocus sequence typing (MLST and multilocus variable number tandem-repeat analysis (MLVA. METHODS: Selected P. aeruginosa isolates (n = 60 were genotyped with PFGE, MLST and MLVA to determine the diversity index (DI and congruence (adjusted Rand and Wallace coefficients. Subsequently, isolates from patients admitted to two different ICUs (n = 205, from CF patients (n = 100 and from non-ICU, non-CF patients (n = 58, of which 19 were community acquired were genotyped with MLVA to determine distribution of genotypes and genetic diversity. RESULTS: Congruence between the typing methods was >79% and DIs were similar and all >0.963. Based on costs, ease, speed and possibilities to compare results between labs an adapted MLVA scheme called MLVA9-Utrecht was selected as the preferred typing method. In 363 clinical isolates 252 different MLVA types (MTs were identified, indicating a highly diverse population (DI  = 0.995; CI  = 0.993-0.997. DI levels were similarly high in the diverse clinical sources (all >0.981 and only eight genotypes were shared. MTs were highly specific (>80% for the different patient populations, even for similar patient groups (ICU patients in two distinct geographic regions, with only three of 142 ICU genotypes detected in both ICUs. The two major CF clones were unique to CF patients. CONCLUSION: The population structure of P. aeruginosa isolates is highly diverse and population specific without evidence for a core lineage in which major CF, hospital or community clones co-cluster. The two genotypes highly prevalent among Dutch CF patients appeared unique to CF patients

  2. The making of a population: Challenges, implications, and consequences of the quantification of social difference.

    Science.gov (United States)

    Cruz, Taylor M

    2017-02-01

    How do we make a difference? This paper traces the connections made between quantified knowledge, population health, and social justice by examining the efforts of population scientists to assess sexuality as a point of difference within population-based data systems, including on national health and social surveys, electronic medical records, and the Census. Population scientists emphasize the importance of measuring social difference in order to identify and remedy structural disadvantage. This evaluation requires the assessment of difference and the comparison of distinct groups across standardized outcome measures. In quantifying social difference, however, population scientists obscure or minimize several difficulties in creating comparable populations. I explore some of these challenges by highlighting three central tensions: the separation of difference from other aspects and categories of social experience, the reduction of difference through the use of one over several possible measures, and the enactment of difference as quantified knowledge loops back into society. As a theoretical inquiry into the form of social difference as it is conceptualized, operationalized, and materialized across the science-society nexus, this paper identifies the various commitments made during processes of scientific evaluation. By attending to the values and priorities that exist within and through practices of quantification, I aim to address the problem of measuring social difference as it pertains to the issues of social justice and health equity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Electromagnetic resonance modes on a two-dimensional tandem grating and its application for broadband absorption in the visible spectrum.

    Science.gov (United States)

    Han, Sunwoo; Lee, Bong Jae

    2016-01-25

    In this work, we numerically investigate the electromagnetic resonances on two-dimensional tandem grating structures. The base of a tandem grating consists of an opaque Au substrate, a SiO(2) spacer, and a Au grating (concave type); that is, a well-known fishnet structure forming Au/SiO(2)/Au stack. A convex-type Au grating (i.e., topmost grating) is then attached on top of the base fishnet structure with or without additional SiO(2) spacer, resulting in two types of tandem grating structures. In order to calculate the spectral reflectance and local magnetic field distribution, the finite-difference time-domain method is employed. When the topmost Au grating is directly added onto the base fishnet structure, the surface plasmon and magnetic polariton in the base structure are branched out due to the geometric asymmetry with respect to the SiO(2) spacer. If additional SiO(2) spacer is added between the topmost Au grating and the base fishnet structure, new magnetic resonance modes appear due to coupling between two vertically aligned Au/SiO(2)/Au stacks. With the understanding of multiple electromagnetic resonance modes on the proposed tandem grating structures, we successfully design a broadband absorber made of Au and SiO(2) in the visible spectrum.

  4. System and technique for characterizing fluids using ultrasonic diffraction grating spectroscopy

    Science.gov (United States)

    Greenwood, Margaret S [Richland, WA

    2008-07-08

    A system for determining property of multiphase fluids based on ultrasonic diffraction grating spectroscopy includes a diffraction grating on a solid in contact with the fluid. An interrogation device delivers ultrasound through the solid and a captures a reflection spectrum from the diffraction grating. The reflection spectrum exhibits peaks whose relative size depends on the properties of the various phases of the multiphase fluid. For example, for particles in a liquid, the peaks exhibit dependence on the particle size and the particle volume fraction. Where the exact relationship is know know a priori, data from different peaks of the same reflection spectrum or data from the peaks of different spectra obtained from different diffraction gratings can be used to resolve the size and volume fraction.

  5. A probabilistic method for testing and estimating selection differences between populations.

    Science.gov (United States)

    He, Yungang; Wang, Minxian; Huang, Xin; Li, Ran; Xu, Hongyang; Xu, Shuhua; Jin, Li

    2015-12-01

    Human populations around the world encounter various environmental challenges and, consequently, develop genetic adaptations to different selection forces. Identifying the differences in natural selection between populations is critical for understanding the roles of specific genetic variants in evolutionary adaptation. Although numerous methods have been developed to detect genetic loci under recent directional selection, a probabilistic solution for testing and quantifying selection differences between populations is lacking. Here we report the development of a probabilistic method for testing and estimating selection differences between populations. By use of a probabilistic model of genetic drift and selection, we showed that logarithm odds ratios of allele frequencies provide estimates of the differences in selection coefficients between populations. The estimates approximate a normal distribution, and variance can be estimated using genome-wide variants. This allows us to quantify differences in selection coefficients and to determine the confidence intervals of the estimate. Our work also revealed the link between genetic association testing and hypothesis testing of selection differences. It therefore supplies a solution for hypothesis testing of selection differences. This method was applied to a genome-wide data analysis of Han and Tibetan populations. The results confirmed that both the EPAS1 and EGLN1 genes are under statistically different selection in Han and Tibetan populations. We further estimated differences in the selection coefficients for genetic variants involved in melanin formation and determined their confidence intervals between continental population groups. Application of the method to empirical data demonstrated the outstanding capability of this novel approach for testing and quantifying differences in natural selection. © 2015 He et al.; Published by Cold Spring Harbor Laboratory Press.

  6. Susceptibility of Different Populations of Nilaparvata lugens from Major Rice Growing Areas of Karnataka, India to Different Groups of Insecticides

    Directory of Open Access Journals (Sweden)

    Y.S. BASANTH

    2013-09-01

    Full Text Available Susceptibility to insecticides was investigated by collecting field populations of brown planthopper from different locations of southern Karnataka, India (Gangavati, Kathalagere, Kollegala, Soraba and Mandya. All the field populations differed in their susceptibility to insecticides. In general, Soraba and Mandya populations were more susceptible to insecticides compared to Gangavati and Kathalagere populations. The resistance ratios varied greatly among the populations viz., chlorpyriphos (1.13- to 16.82-fold, imidacloprid (0.53- to 13.50-fold, acephate (1.34- to 5.32-fold, fipronil (1.13- to 4.06-fold, thiamethoxam (1.01- to 2.19-fold, clothianidin (1.92- to 4.86-fold, dinotefuran (0.82- to 2.22-fold, buprofezin (1.06- to 5.43-fold and carbofuran (0.41- to 2.17-fold. The populations from Gangavati, Kathalagere and Kollegala exhibited higher resistance to some of the old insecticides and low resistance to new molecules.

  7. Dense Wavelength Division (De Multiplexers Based on Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    S. BENAMEUR

    2014-05-01

    Full Text Available This study is to measure the impact of demultiplexers based on Fiber Bragg Grating (FBG filter on performance of DWDM system for optical access network. An optical transmission link has been established in which we have inserted a demultiplexer based on four different FBG filters. The first step will be the characterization of FBG’s filters (i.e. uniform FBG, Gaussian apodized Grating, chirped FBG to explain their behavior in the optical link. The simulations were conducted for different fiber’s lengths, filter bandwidth and different received power to get the best system performance. This helped to assess their impact on the link performance in terms of Bit Error Rate (BER.

  8. Population differences in dysmorphic features among children with fetal alcohol spectrum disorders.

    Science.gov (United States)

    May, Philip A; Gossage, J Phillip; Smith, Matthew; Tabachnick, Barbara G; Robinson, Luther K; Manning, Melanie; Cecanti, Mauro; Jones, Kenneth Lyons; Khaole, Nathaniel; Buckley, David; Kalberg, Wendy O; Trujillo, Phyllis M; Hoyme, H Eugene

    2010-05-01

    To examine the variation in significant dysmorphic features in children from 3 different populations with the most dysmorphic forms of fetal alcohol spectrum disorders, fetal alcohol syndrome (FAS), and partial fetal alcohol syndrome (PFAS). Advanced multiple regression techniques are used to determine the discriminating physical features in the diagnosis of FAS and PFAS among children from Northern Plains Indian communities, South Africa, and Italy. Within the range of physical features used to identify children with fetal alcohol spectrum disorders, specifically FAS and PFAS, there is some significant variation in salient diagnostic features from one population to the next. Intraclass correlations in diagnostic features between these 3 populations is 0.20, indicating that about 20% of the variability in dysmorphology core features is associated with location and, therefore, specific racial/ethnic population. The highly significant diagnostic indicators present in each population are identified for the full samples of FAS, PFAS, and normals and also among children with FAS only. A multilevel model for these populations combined indicates that these variables predict dysmorphology unambiguously: small palpebral fissures, narrow vermillion, smooth philtrum, flat nasal bridge, and fifth finger clinodactyly. Long philtrum varies substantially as a predictor in the 3 populations. Predictors not significantly related to fetal alcohol spectrum disorders dysmorphology across the 3 populations are centile of height (except in Italy) strabismus, interpupilary distance, intercanthal distance, and heart murmurs. The dysmorphology associated with FAS and PFAS vary across populations, yet a particular array of common features occurs in each population, which permits a consistent diagnosis across populations.

  9. Difference in Health Inequity between Two Population Groups due to a Social Determinant of Health

    Science.gov (United States)

    Moonesinghe, Ramal; Bouye, Karen; Penman-Aguilar, Ana

    2014-01-01

    The World Health Organization defines social determinants of health as “complex, integrated, and overlapping social structures and economic systems” that are responsible for most health inequities. Similar to the individual-level risk factors such as behavioral and biological risk factors that influence disease, we consider social determinants of health such as the distribution of income, wealth, influence and power as risk factors for risk of disease. We operationally define health inequity in a disease within a population due to a risk factor that is unfair and avoidable as the difference between the disease outcome with and without the risk factor in the population. We derive expressions for difference in health inequity between two populations due to a risk factor that is unfair and avoidable for a given disease. The difference in heath inequity between two population groups due to a risk factor increases with increasing difference in relative risks and the difference in prevalence of the risk factor in the two populations. The difference in health inequity could be larger than the difference in health outcomes between the two populations in some situations. Compared to health disparities which are typically measured and monitored using absolute or relative disparities of health outcomes, the methods presented in this manuscript provide a different, yet complementary, picture because they parse out the contributions of unfair and avoidable risk factors. PMID:25522048

  10. All-cause and cause-specific mortality of different migrant populations in Europe

    DEFF Research Database (Denmark)

    Ikram, Umar Z; Mackenbach, Johan P; Harding, Seeromanie

    2015-01-01

    of destination. Most migrants had higher mortality due to infectious diseases and homicide while cancer mortality and suicide were lower. CVD mortality differed by migrant population. To conclude, mortality patterns varied across migrant populations in European countries. Future research should focus both...

  11. Neutron diffraction from holographic gratings in PMMA

    International Nuclear Information System (INIS)

    Havermeyer, F.; Kraetzig, E.; Rupp, R.A.; Schubert, D.W.

    1999-01-01

    Complete text of publication follows. By definition photorefractive materials change the refractive index for light under the action of light. Using the spatially modulated light intensity pattern from the interference of two plane waves, volume phase gratings with accurately defined spacings can be produced. Depending on the material there are many physical origins for these gratings, but in most cases they are linked to a density modulation and, consequently, to a refractive index grating for neutrons. By diffraction of light or neutrons from such gratings even small refractive index changes down to Δn ∼ 10 -7 - 10 -9 can be measured. In our photopolymer system PMMA/MMA (poly(methyl methacrylate) with a content of 10-20% of the residual monomer methyl methacrylate) inhomogeneous illumination leads to local post-polymerisation processes of the residual monomer. The resulting light-optical refractive index grating is caused by the modulation of the monomer/polymer ratio as well as by the modulation of the total density. Only by the unique combination of methods for light and neutron diffraction, available at HOLONS (Holography and Neutron Scattering, instrument at the GKSS research centre), both contributions can be separated. We discuss the angular dependence of the neutron diffraction efficiency for weakly and strongly (efficiencies up to 60% have been achieved) modulated gratings and propose a simple model for the evaluation of the gratings. (author)

  12. Fiber Bragg Grating Sensors for Harsh Environments

    Directory of Open Access Journals (Sweden)

    Stephen J. Mihailov

    2012-02-01

    Full Text Available Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments.

  13. Undergraduate experiment with fractal diffraction gratings

    International Nuclear Information System (INIS)

    Monsoriu, Juan A; Furlan, Walter D; Pons, Amparo; Barreiro, Juan C; Gimenez, Marcos H

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics laboratories and compared with those obtained with conventional periodic gratings. It is shown that fractal gratings produce self-similar diffraction patterns which can be evaluated analytically. Good agreement is obtained between experimental and numerical results.

  14. Nanoscale freestanding gratings for ultraviolet blocking filters

    Energy Technology Data Exchange (ETDEWEB)

    van Beek, J.T.; Fleming, R.C.; Hindle, P.S.; Prentiss, J.D.; Schattenburg, M.L. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Ritzau, S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-11-01

    Ultraviolet (UV) blocking filters are needed for atomic flux imaging in environments where high levels of ultraviolet radiation are present. Freestanding gratings are a promising candidate for UV filtering. They have a high aspect ratio ({approximately}13), narrow ({approximately}40 nm) slots, and effectively block UV radiation. The grating fabrication process makes use of several etching, electroplating, and lithographic steps and includes an optional step to plug pinholes induced by particles during processing. Gratings were successfully manufactured and tested. Measured UV transmissions of {approximately}10{sup {minus}5} and particle transmissions of {approximately}10{percent} are in agreement with theoretical predictions. {copyright} {ital 1998 American Vacuum Society.}

  15. Sensitive visual test for concave diffraction gratings.

    Science.gov (United States)

    Bruner, E. C., Jr.

    1972-01-01

    A simple visual test for the evaluation of concave diffraction gratings is described. It is twice as sensitive as the Foucault knife edge test, from which it is derived, and has the advantage that the images are straight and free of astigmatism. It is particularly useful for grating with high ruling frequency where the above image faults limit the utility of the Foucault test. The test can be interpreted quantitatively and can detect zonal grating space errors of as little as 0.1 A.

  16. Thermal annealing of tilted fiber Bragg gratings

    Science.gov (United States)

    González-Vila, Á.; Rodríguez-Cobo, L.; Mégret, P.; Caucheteur, C.; López-Higuera, J. M.

    2016-05-01

    We report a practical study of the thermal decay of cladding mode resonances in tilted fiber Bragg gratings, establishing an analogy with the "power law" evolution previously observed on uniform gratings. We examine how this process contributes to a great thermal stability, even improving it by means of a second cycle slightly increasing the annealing temperature. In addition, we show an improvement of the grating spectrum after annealing, with respect to the one just after inscription, which suggests the application of this method to be employed to improve saturation issues during the photo-inscription process.

  17. Factors and Mechanisms for Pharmacokinetic Differences between Pediatric Population and Adults

    Directory of Open Access Journals (Sweden)

    Jose T. Ramos

    2011-02-01

    Full Text Available Many physiologic differences between children and adults may result in age-related changes in pharmacokinetics and pharmacodynamics. Factors such as gastric pH and emptying time, intestinal transit time, immaturity of secretion and activity of bile and pancreatic fluid among other factors determine the oral bioavailability of pediatric and adult populations. Anatomical, physiological and biochemical characteristics in children also affect the bioavailability of other routes of administration. Key factors explaining differences in drug distribution between the pediatric population and adults are membrane permeability, plasma protein binding and total body water. As far as drug metabolism is concerned, important differences have been found in the pediatric population compared with adults both for phase I and phase II metabolic enzymes. Immaturity of glomerular filtration, renal tubular secretion and tubular reabsorption at birth and their maturation determine the different excretion of drugs in the pediatric population compared to adults.

  18. Expansion of a globally pervasive grass occurs without substantial trait differences between home and away populations.

    Science.gov (United States)

    Leifso, A; MacDougall, A S; Husband, B; Hierro, J L; Köchy, M; Pärtel, M; Peltzer, D A

    2012-12-01

    The global expansion of species beyond their ancestral ranges can derive from mechanisms that are trait-based (e.g., post-establishment evolved differences compared to home populations) or circumstantial (e.g., propagule pressure, with no trait-based differences). These mechanisms can be difficult to distinguish following establishment, but each makes unique predictions regarding trait similarity between ancestral ('home') and introduced ('away') populations. Here, we tested for trait-based population differences across four continents for the globally distributed grass Dactylis glomerata, to assess the possible role of trait evolution in its worldwide expansion. We used a common-environment glasshouse experiment to quantify trait differences among home and away populations, and the potential relevance of these differences for competitive interactions. Few significant trait differences were found among continents, suggesting minimal change during global expansion. All populations were polyploids, with similar foliar carbon:nitrogen ratios (a proxy for defense), chlorophyll content, and biomass. Emergence time and growth rate favored home populations, resulting in their competitive superiority over away populations. Small but significant trait differences among away populations suggest different introductory histories or local adaptive responses following establishment. In summary, the worldwide distribution of this species appears to have arisen from its pre-adapted traits promoting growth, and its repeated introduction with cultivation and intense propagule pressure. Global expansion can thus occur without substantial shifts in growth, reproduction, or defense. Rather than focusing strictly on the invader, invasion success may also derive from the traits found (or lacking) in the recipient community and from environmental context including human disturbance.

  19. Analysis of changes of demographic parameters in different groups of Chernigiv region population

    International Nuclear Information System (INIS)

    Gridzhuk, M.Yu.

    1998-01-01

    To perform comparison of the changes in different social and age groups of the population of Chernigiv region, Kozeletsky district in particular, which was exposed to considerable radioactive contamination, during the recent 20 years (beginning from 1977). The Chernobyl accident together with social and other unfavorable factors caused negative demographic changes in the contaminated districts. Reduction in the number of different social groups of the population is expected

  20. Cascaded holographic polymer reflection grating filters for optical-code-division multiple-access applications.

    Science.gov (United States)

    Kostuk, Raymond K; Maeda, Wendi; Chen, Chia-Hung; Djordjevic, Ivan; Vasic, Bane

    2005-12-10

    We evaluate the use of edge-illuminated holographic Bragg filters formed in phenanthrenequinone-doped poly(methyl methacrylate) for optical-code-division multiple-access (OCDMA) coding and decoding applications. Experimental cascaded Bragg filters are formed to select two different wavelengths with a fixed distance between the gratings and are directly coupled to a fiber-measurement system. The configuration and tolerances of the cascaded gratings are shown to be practical for time-wavelength OCDMA applications.

  1. Uniform Fiber Bragg Grating modeling and simulation used matrix transfer method

    OpenAIRE

    IKHLEF, Abdallah; HEDARA, Rachida; CHIKH-BLED, Mohamed

    2012-01-01

    This paper presents the modeling and simulation of an optical fiber Bragg grating for maximum reflectivity, minimum side lobe. Gating length represents as one of the critical parameters in contributing to a high performance fiber Bragg grating. The reflection spectra and side lobes strength were analyzed with different lengths .The side lobes have been suppressed using raised cosine apodization while maintaining the peak reflectivity. Such simulations are based on ...

  2. Population differences in self-fertility in the "self-incompatible" milkweed Asclepias exaltata (Asclepiadaceae).

    Science.gov (United States)

    Lipow, S R; Broyles, S B; Wyatt, R

    1999-08-01

    Individual plants of Asclepias exaltata (Asclepiadaceae) typically express an unusual self-incompatibility system under single-gene control. Hand-pollinations performed in six natural populations detected occasional self-fertile plants. The frequency of self-fertile individuals ranged from 0 to 34.0% and differed significantly among populations. Self-fertility appears to be under genetic control, as the ability of most plants (80.0 %) to set fruit following self-pollinations was identical under natural and greenhouse conditions. Seed- and fruit-set, however, were significantly lower from self- vs. cross-pollinations. Allozyme analysis of the population with the highest frequency of self-fertility revealed that adult plants were not significantly inbred. Finally, fruit-set following within-population cross-pollinations did not differ from that following wide, between-population cross-pollinations.

  3. HOX and TALE signatures specify human stromal stem cell populations from different sources.

    Science.gov (United States)

    Picchi, Jacopo; Trombi, Luisa; Spugnesi, Laura; Barachini, Serena; Maroni, Giorgia; Brodano, Giovanni Barbanti; Boriani, Stefano; Valtieri, Mauro; Petrini, Mario; Magli, Maria Cristina

    2013-04-01

    Human stromal stem cell populations reside in different tissues and anatomical sites, however a critical question related to their efficient use in regenerative medicine is whether they exhibit equivalent biological properties. Here, we compared cellular and molecular characteristics of stromal stem cells derived from the bone marrow, at different body sites (iliac crest, sternum, and vertebrae) and other tissues (dental pulp and colon). In particular, we investigated whether homeobox genes of the HOX and TALE subfamilies might provide suitable markers to identify distinct stromal cell populations, as HOX proteins control cell positional identity and, together with their co-factors TALE, are involved in orchestrating differentiation of adult tissues. Our results show that stromal populations from different sources, although immunophenotypically similar, display distinct HOX and TALE signatures, as well as different growth and differentiation abilities. Stromal stem cells from different tissues are characterized by specific HOX profiles, differing in the number and type of active genes, as well as in their level of expression. Conversely, bone marrow-derived cell populations can be essentially distinguished for the expression levels of specific HOX members, strongly suggesting that quantitative differences in HOX activity may be crucial. Taken together, our data indicate that the HOX and TALE profiles provide positional, embryological and hierarchical identity of human stromal stem cells. Furthermore, our data suggest that cell populations derived from different body sites may not represent equivalent cell sources for cell-based therapeutical strategies for regeneration and repair of specific tissues. Copyright © 2012 Wiley Periodicals, Inc.

  4. Characterizing and modeling of an 88 MW grate-fired boiler burning wheat straw: Experience and lessons

    DEFF Research Database (Denmark)

    Yin, Chungen; Rosendahl, Lasse Aistrup; Clausen, Sønnik

    2012-01-01

    and availability. To better understand grate-firing of biomass and to establish a reliable but relatively simple Computational Fluid Dynamics (CFD) modeling methodology for industrial applications, biomass combustion in a number of different grate boilers has been measured and modeled. As one of the case studies......, modeling effort on an 88 MW grate-fired boiler burning wheat straw is presented in this paper. Different modeling issues and their expected impacts on CFD analysis of the kind of grate boilers are discussed. The modeling results are compared with in-flame measurements in the 88 MW boiler, which shows...... measures will be tested in a modern 500 kW grate boiler rig...

  5. The population dynamical implications of male-biased parasitism in different mating systems.

    Directory of Open Access Journals (Sweden)

    Martin R Miller

    2007-07-01

    Full Text Available Although there is growing evidence that males tend to suffer higher levels of parasitism than females, the implications of this for the population dynamics of the host population are not yet understood. Here we build on an established 'two-sex' model and investigate how increased susceptibility to infection in males affects the dynamics, under different mating systems. We investigate the effect of pathogenic disease at different case mortalities, under both monogamous and polygynous mating systems. If the case mortality is low, then male-biased parasitism appears similar to unbiased parasitism in terms of its effect on the population dynamics. At higher case mortalities, we identified significant differences between male-biased and unbiased parasitism. A host population may therefore be differentially affected by male-biased and unbiased parasitism. The dynamical outcome is likely to depend on a complex interaction between the host's mating system and demography, and the parasite virulence.

  6. Dynamics of the population quantity of Juglans mandshurica Maxim. in different habitats in Xinjiang, China

    International Nuclear Information System (INIS)

    Yang, Y.; Li, J.; Zhang, W.

    2015-01-01

    Transects were arranged on the shady and sunny slopes, as well as at different elevations of the main, eastern, central, and western gullies in the Wild Walnut Nature Reserve in Xinjiang, China to survey a large sample of Juglans mandshurica. The structures of height class and diameter at breast height (DBH) class were used to represent age structure to compare and analyze the dynamics of the population quantity of J. mandshurica in different habitats. Results showed that J. mandshurica population comprises numerous young seedlings, which develop into young plants with a high death rate. The number of adult plants is stable. J. mandshurica population is r-strategists in the young stage, and k-strategists supplemented by r-strategists in the juvenile and subsequent stages. The structures of height class and DBH class fluctuate at different slope aspects and elevations. The growth of young seedlings into adult plants is discontinuous. Tree height and DBH are relatively uniform in the same age class, and the coefficient of variation is independent of slope aspect and elevation. The maximum numbers of age classes in J. mandshurica population with different height and DBH classes differ at three elevations. Low- and medium-age classes are dominant in all situations. That is, population is mainly composed of juvenile and adult trees, and age structure is classified as a growth type. Without strong external interference, J. mandshurica population will maintain its superior position in the community. (author)

  7. Multiwavelength optical scatterometry of dielectric gratings

    KAUST Repository

    Yashina, Nataliya P.; Melezhik, Petr N.; Sirenko, Kostyantyn; Granet, Gerard

    2012-01-01

    is based on rigorous solutions of 2-D initial boundary value problems of the gratings theory. The quintessence and advantage of the method is the possibility to perform an efficient analysis simultaneously and interactively both for steady state

  8. Fiber Optic Long Period Grating Based Sensor for Coconut Oil Adulteration Detection

    Directory of Open Access Journals (Sweden)

    T. M. Libish

    2010-03-01

    Full Text Available We report the development and demonstration of a Long-Period Grating (LPG based optical fiber sensor for determining the adulteration of coconut oil by palm oil. The fundamental principle of detection is the sensitive dependence of the resonance peaks of LPG on the changes of the refractive index of the environmental medium around the cladding surface of the grating. Refractive index sensing with LPGs employs light coupling between core and cladding modes in the grating section. The transmittance spectra of a long period grating element immersed in different mixtures of coconut oil and palm oil were recorded. Results show that resonance wavelengths and transmission intensities varied as a function of the adulteration level of coconut oil. Detection limit of adulteration was found to be 2 % for coconut oil–palm oil binary mixture.

  9. Modeling optical transmissivity of graphene grate in on-chip silicon photonic device

    Directory of Open Access Journals (Sweden)

    Iraj S. Amiri

    2018-06-01

    Full Text Available A three-dimensional (3-D finite-difference-time-domain (FDTD analysis was used to simulate a silicon photonic waveguide. We have calculated power and transmission of the graphene used as single or multilayers to study the light transmission behavior. A new technique has been developed to define the straight silicon waveguide integrated with grate graphene layer. The waveguide has a variable grate spacing to be filled by the graphene layer. The number of graphene atomic layers varies between 100 and 1000 (or 380 nm and 3800 nm, the transmitted power obtained varies as ∼30% and ∼80%. The ∼99%, blocking of the light was occurred in 10,000 (or 38,000 nm atomic layers of the graphene grate. Keywords: Optical waveguide, Silicon waveguide, Grate, Graphene, Optical transmissivity

  10. Beam-splitter switches based on zenithal bistable liquid-crystal gratings.

    Science.gov (United States)

    Zografopoulos, Dimitrios C; Beccherelli, Romeo; Kriezis, Emmanouil E

    2014-10-01

    The tunable optical diffractive properties of zenithal bistable nematic liquid-crystal gratings are theoretically investigated. The liquid-crystal orientation is rigorously solved via a tensorial formulation of the Landau-de Gennes theory and the optical transmission properties of the gratings are investigated via full-wave finite-element frequency-domain simulations. It is demonstrated that by proper design the two stable states of the grating can provide nondiffracting and diffracting operation, the latter with equal power splitting among different diffraction orders. An electro-optic switching mechanism, based on dual-frequency nematic materials, and its temporal dynamics are further discussed. Such gratings provide a solution towards tunable beam-steering and beam-splitting components with extremely low power consumption.

  11. A conductive grating sensor for online quantitative monitoring of fatigue crack

    Science.gov (United States)

    Li, Peiyuan; Cheng, Li; Yan, Xiaojun; Jiao, Shengbo; Li, Yakun

    2018-05-01

    Online quantitative monitoring of crack damage due to fatigue is a critical challenge for structural health monitoring systems assessing structural safety. To achieve online quantitative monitoring of fatigue crack, a novel conductive grating sensor based on the principle of electrical potential difference is proposed. The sensor consists of equidistant grating channels to monitor the fatigue crack length and conductive bars to provide the circuit path. An online crack monitoring system is established to verify the sensor's capability. The experimental results prove that the sensor is suitable for online quantitative monitoring of fatigue crack. A finite element model for the sensor is also developed to optimize the sensitivity of crack monitoring, which is defined by the rate of sensor resistance change caused by the break of the first grating channel. Analysis of the model shows that the sensor sensitivity can be enhanced by reducing the number of grating channels and increasing their resistance and reducing the resistance of the conductive bar.

  12. Diffraction from polarization holographic gratings with surface relief in side-chain azobenzene polyesters

    DEFF Research Database (Denmark)

    Naydenova, I; Nikolova, L; Todorov, T

    1998-01-01

    We investigate the polarization properties of holographic gratings in side-chain azobenzene polyesters in which an anisotropic grating that is due to photoinduced linear and circular birefringence is recorded in the volume of the material and a relief grating appears on the surface. A theoretical...... model is proposed to explain the experimental results, making it possible to understand the influence of the different photoinduced effects. It is shown that at low intensity the polarization properties of the diffraction at these gratings are determined by the interaction of the linear and circular...... photobirefringences, and at larger intensity the influence of the surface relief dominates the effect of the circular anisotropy. Owing to the high recording efficiency of the polyesters, the +/-1-order diffracted waves change the polarization interference pattern during the holographic recording, resulting...

  13. Optical fibres sensor based in the intensity switch of a linear laser with two Bragg gratings

    International Nuclear Information System (INIS)

    Basurto P, M.A.; Kuzin, E.A.; Archundia B, C.; Marroquin, E.; May A, M.; Cerecedo N, H.H.; Sanchez M, J.J.; Tentori S, D.; Marquez B, I.; Shliagin, M.; Miridonov, S.

    2000-01-01

    In this work we propose a new configuration for an optical fiber temperature sensor, based on a linear type Er-doped fiber laser. The laser cavity consists of an Er-doped fiber and two identical Bragg gratings at the fiber ends (working as reflectors). Temperature changes are detected by measuring, through one of the gratings, the intensity variations at the system's output. When the temperature of one of the Bragg gratings is modified, a wavelength shift of its spectral reflectivity is observed. Hence, the laser emission intensity of the system is modified. We present experimental results of the intensity switch observed when the temperature difference between the gratings detunes their spectral reflectance. Making use of this effect it is possible to develop limit comparators to bound the temperature range for the object under supervision. This limiting work can be performed with a high sensitivity using a very simple interrogation procedure. (Author)

  14. Large-Area Binary Blazed Grating Coupler between Nanophotonic Waveguide and LED

    Directory of Open Access Journals (Sweden)

    Hongqiang Li

    2014-01-01

    Full Text Available A large-area binary blazed grating coupler for the arrayed waveguide grating (AWG demodulation integrated microsystem on silicon-on-insulator (SOI was designed for the first time. Through the coupler, light can be coupled into the SOI waveguide from the InP-based C-band LED for the AWG demodulation integrated microsystem to function. Both the length and width of the grating coupler are 360 μm, as large as the InP-based C-band LED light emitting area in the system. The coupler was designed and optimized based on the finite difference time domain method. When the incident angle of the light source is 0°, the coupling efficiency of the binary blazed grating is 40.92%, and the 3 dB bandwidth is 72 nm at a wavelength of 1550 nm.

  15. Different Evolutionary History for Basque Diaspora Populations in USA and Argentina Unveiled by Mitochondrial DNA Analysis.

    Science.gov (United States)

    Baeta, Miriam; Núñez, Carolina; Cardoso, Sergio; Palencia-Madrid, Leire; Piñeiro-Hermida, Sergio; Arriba-Barredo, Miren; Villanueva-Millán, María Jesús; M de Pancorbo, Marian

    2015-01-01

    The Basque Diaspora in Western USA and Argentina represents two populations which have maintained strong Basque cultural and social roots in a completely different geographic context. Hence, they provide an exceptional opportunity to study the maternal genetic legacy from the ancestral Basque population and assess the degree of genetic introgression from the host populations in two of the largest Basque communities outside the Basque Country. For this purpose, we analyzed the complete mitochondrial DNA control region of Basque descendants living in Western USA (n = 175) and in Argentina (n = 194). The Diaspora populations studied here displayed a genetic diversity in their European maternal input which was similar to that of the Basque source populations, indicating that not important founder effects would have occurred. Actually, the genetic legacy of the Basque population still prevailed in their present-day maternal pools, by means of a haplogroup distribution similar to the source population characterized by the presence of autochthonous Basque lineages, such as U5b1f1a and J1c5c1. However, introgression of non-Basque lineages, mostly Native American, has been observed in the Diaspora populations, particularly in Argentina, where the quick assimilation of the newcomers would have favored a wider admixture with host populations. In contrast, a longer isolation of the Diaspora groups in USA, because of language and cultural differences, would have limited the introgression of local lineages. This study reveals important differences in the maternal evolutionary histories of these Basque Diaspora populations, which have to be taken into consideration in forensic and medical genetic studies.

  16. Experimental evolution reveals differences between phenotypic and evolutionary responses to population density.

    Science.gov (United States)

    McNamara, K B; Simmons, L W

    2017-09-01

    Group living can select for increased immunity, given the heightened risk of parasite transmission. Yet, it also may select for increased male reproductive investment, given the elevated risk of female multiple mating. Trade-offs between immunity and reproduction are well documented. Phenotypically, population density mediates both reproductive investment and immune function in the Indian meal moth, Plodia interpunctella. However, the evolutionary response of populations to these traits is unknown. We created two replicated populations of P. interpunctella, reared and mated for 14 generations under high or low population densities. These population densities cause plastic responses in immunity and reproduction: at higher numbers, both sexes invest more in one index of immunity [phenoloxidase (PO) activity] and males invest more in sperm. Interestingly, our data revealed divergence in PO and reproduction in a different direction to previously reported phenotypic responses. Males evolving at low population densities transferred more sperm, and both males and females displayed higher PO than individuals at high population densities. These positively correlated responses to selection suggest no apparent evolutionary trade-off between immunity and reproduction. We speculate that the reduced PO activity and sperm investment when evolving under high population density may be due to the reduced population fitness predicted under increased sexual conflict and/or to trade-offs between pre- and post-copulatory traits. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  17. Leaf physico-chemical and physiological properties of maize (Zea mays L.) populations from different origins.

    Science.gov (United States)

    Revilla, Pedro; Fernández, Victoria; Álvarez-Iglesias, Lorena; Medina, Eva T; Cavero, José

    2016-10-01

    In this study we evaluated the leaf surface properties of maize populations native to different water availability environments. Leaf surface topography, wettability and gas exchange performance of five maize populations from the Sahara desert, dry (south) and humid (north-western) areas of Spain were analysed. Differences in wettability, stomatal and trichome densities, surface free energy and solubility parameter values were recorded between populations and leaf sides. Leaves from the humid Spanish population with special regard to the abaxial side, were less wettable and less susceptible to polar interactions. The higher wettability and hydrophilicity of Sahara populations with emphasis on the abaxial leaf surfaces, may favour dew deposition and foliar water absorption, hence improving water use efficiency under extremely dry conditions. Compared to the other Saharan populations, the dwarf one had a higher photosynthesis rate suggesting that dwarfism may be a strategy for improving plant tolerance to arid conditions. The results obtained for different maize populations suggest that leaf surfaces may vary in response to drought, but further studies will be required to examine the potential relationship between leaf surface properties and plant stress tolerance. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  18. Selective Pressures Explain Differences in Flower Color among Gentiana lutea Populations.

    Directory of Open Access Journals (Sweden)

    Mar Sobral

    Full Text Available Flower color variation among plant populations might reflect adaptation to local conditions such as the interacting animal community. In the northwest Iberian Peninsula, flower color of Gentiana lutea varies longitudinally among populations, ranging from orange to yellow. We explored whether flower color is locally adapted and the role of pollinators and seed predators as agents of selection by analyzing the influence of flower color on (i pollinator visitation rate and (ii escape from seed predation and (iii by testing whether differences in pollinator communities correlate with flower color variation across populations. Finally, (iv we investigated whether variation in selective pressures explains flower color variation among 12 G. lutea populations. Flower color influenced pollinator visits and differences in flower color among populations were related to variation in pollinator communities. Selective pressures on flower color vary among populations and explain part of flower color differences among populations of G. lutea. We conclude that flower color in G. lutea is locally adapted and that pollinators play a role in this adaptation.

  19. Do differences in the administrative structure of populations confound comparisons of geographic health inequalities?

    LENUS (Irish Health Repository)

    Jackson, Andrew L

    2010-08-18

    Abstract Background Geographical health inequalities are naturally described by the variation in health outcomes between areas (e.g. mortality rates). However, comparisons made between countries are hampered by our lack of understanding of the effect of the size of administrative units, and in particular the modifiable areal unit problem. Our objective was to assess how differences in geographic and administrative units used for disseminating data affect the description of health inequalities. Methods Retrospective study of standard populations and deaths aggregated by administrative regions within 20 European countries, 1990-1991. Estimated populations and deaths in males aged 0-64 were in 5 year age bands. Poisson multilevel modelling was conducted of deaths as standardised mortality ratios. The variation between regions within countries was tested for relationships with the mean region population size and the unequal distribution of populations within each country measured using Gini coefficients. Results There is evidence that countries whose regions vary more in population size show greater variation and hence greater apparent inequalities in mortality counts. The Gini coefficient, measuring inequalities in population size, ranged from 0.1 to 0.5 between countries; an increase of 0.1 was accompanied by a 12-14% increase in the standard deviation of the mortality rates between regions within a country. Conclusions Apparently differing health inequalities between two countries may be due to differences in geographical structure per se, rather than having any underlying epidemiological cause. Inequalities may be inherently greater in countries whose regions are more unequally populated.

  20. Selective Pressures Explain Differences in Flower Color among Gentiana lutea Populations.

    Science.gov (United States)

    Sobral, Mar; Veiga, Tania; Domínguez, Paula; Guitián, Javier A; Guitián, Pablo; Guitián, José M

    2015-01-01

    Flower color variation among plant populations might reflect adaptation to local conditions such as the interacting animal community. In the northwest Iberian Peninsula, flower color of Gentiana lutea varies longitudinally among populations, ranging from orange to yellow. We explored whether flower color is locally adapted and the role of pollinators and seed predators as agents of selection by analyzing the influence of flower color on (i) pollinator visitation rate and (ii) escape from seed predation and (iii) by testing whether differences in pollinator communities correlate with flower color variation across populations. Finally, (iv) we investigated whether variation in selective pressures explains flower color variation among 12 G. lutea populations. Flower color influenced pollinator visits and differences in flower color among populations were related to variation in pollinator communities. Selective pressures on flower color vary among populations and explain part of flower color differences among populations of G. lutea. We conclude that flower color in G. lutea is locally adapted and that pollinators play a role in this adaptation.

  1. Effect on population dynamics to haloxylon persicum in different edaphic types

    International Nuclear Information System (INIS)

    Song, Y.; Hu, X.; Zhou, C.

    2016-01-01

    This study investigated the age class structure of H. persicum populations in different edaphic types in Gurbantunggut desert and analyzed the survival rate, mortality rate and spectral analysis characteristics. The results showed that the survival curve of H. persicum populations tended to be the type of Deevey, the mortality rate of H. persicum was high at early stage and low at late stage, There existed 2-4 death peak phases in the whole population life span. The natural regeneration process of the H. persicum population can be represented by the fluctuation of the distribution of the number of trees in different age classes. Spectral analysis showed that the fluctuation of H. persicum population was multi-harmonic superposition with large periodic containing small periodic, and had more than two periodic fluctuation. Upscaling process of spectral analysis indicated that the periodic fluctuation of H. persicum population becomes constant in relatively small sampling plot (4400-5600 m2), when it is growing under relatively good environmental conditions in the Gurbantunggut desert. On the other hand, when the growing conditions are poor, large plot (4000-9200 m2) is needed to obtain constant population. Accordingly, different plot sizes should be used for spectral analysis to reveal the periodic fluctuation on the optimal scale. (author)

  2. Grism and immersion grating for space telescope

    Science.gov (United States)

    Ebizuka, Noboru; Oka, Kiko; Yamada, Akiko; Ishikawa, Mami; Kashiwagi, Masako; Kodate, Kashiko; Hirahara, Yasuhiro; Sato, Shuji; Kawabata, Koji S.; Wakaki, Moriaki; Morita, Shin-ya; Simizu, Tomoyuki; Yin, Shaohui; Omori, Hitoshi; Iye, Masanori

    2017-11-01

    The grism is a versatile dispersion element for an astronomical instrument ranging from ultraviolet to infrared. Major benefit of using a grism in a space application, instead of a reflection grating, is the size reduction of optical system because collimator and following optical elements could locate near by the grism. The surface relief (SR) grism is consisted a transmission grating and a prism, vertex angle of which is adjusted to redirect the diffracted beam straight along the direct vision direction at a specific order and wavelength. The volume phase holographic (VPH) grism consists a thick VPH grating sandwiched between two prisms, as specific order and wavelength is aligned the direct vision direction. The VPH grating inheres ideal diffraction efficiency on a higher dispersion application. On the other hand, the SR grating could achieve high diffraction efficiency on a lower dispersion application. Five grisms among eleven for the Faint Object Camera And Spectrograph (FOCAS) of the 8.2m Subaru Telescope with the resolving power from 250 to 3,000 are SR grisms fabricated by a replication method. Six additional grisms of FOCAS with the resolving power from 3,000 to 7,000 are VPH grisms. We propose "Quasi-Bragg grism" for a high dispersion spectroscopy with wide wavelength range. The germanium immersion grating for instance could reduce 1/64 as the total volume of a spectrograph with a conventional reflection grating since refractive index of germanium is over 4.0 from 1.6 to 20 μm. The prototype immersion gratings for the mid-InfraRed High dispersion Spectrograph (IRHS) are successfully fabricated by a nano-precision machine and grinding cup of cast iron with electrolytic dressing method.

  3. PopCORN: Hunting down the differences between binary population synthesis codes

    Science.gov (United States)

    Toonen, S.; Claeys, J. S. W.; Mennekens, N.; Ruiter, A. J.

    2014-02-01

    Context. Binary population synthesis (BPS) modelling is a very effective tool to study the evolution and properties of various types of close binary systems. The uncertainty in the parameters of the model and their effect on a population can be tested in a statistical way, which then leads to a deeper understanding of the underlying (sometimes poorly understood) physical processes involved. Several BPS codes exist that have been developed with different philosophies and aims. Although BPS has been very successful for studies of many populations of binary stars, in the particular case of the study of the progenitors of supernovae Type Ia, the predicted rates and ZAMS progenitors vary substantially between different BPS codes. Aims: To understand the predictive power of BPS codes, we study the similarities and differences in the predictions of four different BPS codes for low- and intermediate-mass binaries. We investigate the differences in the characteristics of the predicted populations, and whether they are caused by different assumptions made in the BPS codes or by numerical effects, e.g. a lack of accuracy in BPS codes. Methods: We compare a large number of evolutionary sequences for binary stars, starting with the same initial conditions following the evolution until the first (and when applicable, the second) white dwarf (WD) is formed. To simplify the complex problem of comparing BPS codes that are based on many (often different) assumptions, we equalise the assumptions as much as possible to examine the inherent differences of the four BPS codes. Results: We find that the simulated populations are similar between the codes. Regarding the population of binaries with one WD, there is very good agreement between the physical characteristics, the evolutionary channels that lead to the birth of these systems, and their birthrates. Regarding the double WD population, there is a good agreement on which evolutionary channels exist to create double WDs and a rough

  4. Seasonal Differences in Determinants of Time Location Patterns in an Urban Population: A Large Population-Based Study in Korea.

    Science.gov (United States)

    Lee, Sewon; Lee, Kiyoung

    2017-06-22

    Time location patterns are a significant factor for exposure assessment models of air pollutants. Factors associated with time location patterns in urban populations are typically due to high air pollution levels in urban areas. The objective of this study was to determine the seasonal differences in time location patterns in two urban cities. A Time Use Survey of Korean Statistics (KOSTAT) was conducted in the summer, fall, and winter of 2014. Time location data from Seoul and Busan were collected, together with demographic information obtained by diaries and questionnaires. Determinants of the time spent at each location were analyzed by multiple linear regression and the stepwise method. Seoul and Busan participants had similar time location profiles over the three seasons. The time spent at own home, other locations, workplace/school and during walk were similar over the three seasons in both the Seoul and Busan participants. The most significant time location pattern factors were employment status, age, gender, monthly income, and spouse. Season affected the time spent at the workplace/school and other locations in the Seoul participants, but not in the Busan participants. The seasons affected each time location pattern of the urban population slightly differently, but overall there were few differences.

  5. Seasonal Differences in Determinants of Time Location Patterns in an Urban Population: A Large Population-Based Study in Korea

    Directory of Open Access Journals (Sweden)

    Sewon Lee

    2017-06-01

    Full Text Available Time location patterns are a significant factor for exposure assessment models of air pollutants. Factors associated with time location patterns in urban populations are typically due to high air pollution levels in urban areas. The objective of this study was to determine the seasonal differences in time location patterns in two urban cities. A Time Use Survey of Korean Statistics (KOSTAT was conducted in the summer, fall, and winter of 2014. Time location data from Seoul and Busan were collected, together with demographic information obtained by diaries and questionnaires. Determinants of the time spent at each location were analyzed by multiple linear regression and the stepwise method. Seoul and Busan participants had similar time location profiles over the three seasons. The time spent at own home, other locations, workplace/school and during walk were similar over the three seasons in both the Seoul and Busan participants. The most significant time location pattern factors were employment status, age, gender, monthly income, and spouse. Season affected the time spent at the workplace/school and other locations in the Seoul participants, but not in the Busan participants. The seasons affected each time location pattern of the urban population slightly differently, but overall there were few differences.

  6. Dynamic optical coupled system employing Dammann gratings

    Science.gov (United States)

    Di, Caihui; Zhou, Changhe; Ru, Huayi

    2004-10-01

    With the increasing of the number of users in optical fiber communications, fiber-to-home project has a larger market value. Then the need of dynamic optical couplers, especially of N broad-band couplers, becomes greater. Though some advanced fiber fusion techniques have been developed, they still have many shortcomings. In this paper we propose a dynamic optical coupled system employing even-numbered Dammann gratings, which have the characteristic that the phase distribution in the first half-period accurately equals to that in the second-period with π phase inversion. In our experiment, we divide a conventional even-numbered Dammann grating into two identical gratings. The system can achieve the beam splitter and combiner as the switch between them according to the relative shift between two complementary gratings. When there is no shift between the gratings, the demonstrated 1×8 dynamic optical coupler achieves good uniformity of 0.06 and insertion loss of around 10.8 dB for each channel as a splitter. When the two gratings have an accurate shift of a half-period between them, our system has a low insertion loss of 0.46 dB as a combiner at a wavelength of 1550 nm.

  7. A measurement of electron-wall interactions using transmission diffraction from nanofabricated gratings

    International Nuclear Information System (INIS)

    Barwick, Brett; Gronniger, Glen; Yuan, Lu; Liou, Sy-Hwang; Batelaan, Herman

    2006-01-01

    Electron diffraction from metal coated freestanding nanofabricated gratings is presented, with a quantitative path integral analysis of the electron-grating interactions. Electron diffraction out to the 20th order was observed indicating the high quality of our nanofabricated gratings. The electron beam is collimated to its diffraction limit with ion-milled material slits. Our path integral analysis is first tested against single slit electron diffraction, and then further expanded with the same theoretical approach to describe grating diffraction. Rotation of the grating with respect to the incident electron beam varies the effective distance between the electron and grating bars. This allows the measurement of the image charge potential between the electron and the grating bars. Image charge potentials that were about 15% of the value for that of a pure electron-metal wall interaction were found. We varied the electron energy from 50 to 900 eV. The interaction time is of the order of typical metal image charge response times and in principle allows the investigation of image charge formation. In addition to the image charge interaction there is a dephasing process reducing the transverse coherence length of the electron wave. The dephasing process causes broadening of the diffraction peaks and is consistent with a model that ascribes the dephasing process to microscopic contact potentials. Surface structures with length scales of about 200 nm observed with a scanning tunneling microscope, and dephasing interaction strength typical of contact potentials of 0.35 eV support this claim. Such a dephasing model motivated the investigation of different metallic coatings, in particular Ni, Ti, Al, and different thickness Au-Pd coatings. Improved quality of diffraction patterns was found for Ni. This coating made electron diffraction possible at energies as low as 50 eV. This energy was limited by our electron gun design. These results are particularly relevant for the

  8. Fetal nasal bone length in the second trimester: comparison between population groups from different ethnic origins.

    Science.gov (United States)

    Papasozomenou, Panayiota; Athanasiadis, Apostolos P; Zafrakas, Menelaos; Panteris, Eleftherios; Loufopoulos, Aristoteles; Assimakopoulos, Efstratios; Tarlatzis, Basil C

    2016-03-01

    To compare normal ranges of ultrasonographically measured fetal nasal bone length in the second trimester between different ethnic groups. A prospective, non-interventional study in order to establish normal ranges of fetal nasal bone length in the second trimester in a Greek population was conducted in 1220 singleton fetuses between 18 completed weeks and 23 weeks and 6 days of gestation. A literature search followed in order to identify similar studies in different population groups. Fetal nasal bone length mean values and percentiles from different population groups were compared. Analysis of measurements in the Greek population showed a linear association, i.e., increasing nasal bone length with increasing gestational age from 5.73 mm at 18 weeks to 7.63 mm at 23 weeks. Eleven studies establishing normal ranges of fetal nasal bone length in the second trimester were identified. Comparison of fetal nasal bone length mean values between the 12 population groups showed statistically significant differences (Pdifferent ethnic groups. Hence, distinct ethnic nomograms of fetal nasal bone length in the second trimester should be used in a given population rather than an international model.

  9. Elastomeric polymer resonant waveguide grating based pressure sensor

    International Nuclear Information System (INIS)

    Song, Fuchuan; Xie, Antonio Jou; Seo, Sang-Woo

    2014-01-01

    In this paper, we demonstrate an elastomeric polymer resonant waveguide grating structure to be used as a pressure sensor. The applied pressure is measured by optical resonance spectrum peak shift. The sensitivity—as high as 86.74 pm psi −1 or 12.58 pm kPa −1 —has been experimentally obtained from a fabricated sensor. Potentially, the sensitivity of the demonstrated sensor can be tuned to different pressure ranges by the choices of elastic properties and layer thicknesses of the waveguide and cladding layers. The simulation results agree well with experimental results and indicate that the dominant effect on the sensor is the change of grating period when external pressure is applied. Based on the two-dimensional planar structure, the demonstrated sensor can be used to measure applied surface pressure optically, which has potential applications for optical ultrasound imaging and pressure wave detection/mapping

  10. Moiré volume Bragg grating filter with tunable bandwidth.

    Science.gov (United States)

    Mokhov, Sergiy; Ott, Daniel; Divliansky, Ivan; Zeldovich, Boris; Glebov, Leonid

    2014-08-25

    We propose a monolithic large-aperture narrowband optical filter based on a moiré volume Bragg grating formed by two sequentially recorded gratings with slightly different resonant wavelengths. Such recording creates a spatial modulation of refractive index with a slowly varying sinusoidal envelope. By cutting a specimen at a small angle, to a thickness of one-period of this envelope, the longitudinal envelope profile will shift from a sine profile to a cosine profile across the face of the device. The transmission peak of the filter has a tunable bandwidth while remaining at a fixed resonant wavelength by a transversal shift of incidence position. Analytical expressions for the tunable bandwidth of such a filter are calculated and experimental data from a filter operating at 1064 nm with bandwidth range 30-90 pm is demonstrated.

  11. Development of generalised model for grate combustion of biomass

    DEFF Research Database (Denmark)

    Rosendahl, Lasse; Kær, Søren Knudsen; Sørensen, Henrik

    for two reasons: 1) to improve emission understanding and reduction measures and 2) to improve boundary conditions for CFD-based furnace modelling. The selected approach has been based on a diffusion coefficient formulation, where conservation equations for the concentration of fuel are solved...... in a spatially resolved grid, much in the same manner as in a finite volume CFD code. Within this porous layer of fuel, gas flows according to the Ergun equation. The diffusion coefficient links the properties of the fuel to the grate type and vibration mode, and is determined for each combination of fuel, grate...... is big enough to represent real, full scale conditions, and yet small enough to be operational in terms of parameter studies of different nature. Apart from full SRO data, measurements (gas sampling, velocity, temperature, particle sampling) can be taken through a heated, water-cooled probe...

  12. Fiber Bragg grating sensor interrogators on chip: challenges and opportunities

    Science.gov (United States)

    Marin, Yisbel; Nannipieri, Tiziano; Oton, Claudio J.; Di Pasquale, Fabrizio

    2017-04-01

    In this paper we present an overview of the current efforts towards integration of Fiber Bragg Grating (FBG) sensor interrogators. Different photonic integration platforms will be discussed, including monolithic planar lightwave circuit technology, silicon on insulator (SOI), indium phosphide (InP) and gallium arsenide (GaAs) material platforms. Also various possible techniques for wavelength metering and methods for FBG multiplexing will be discussed and compared in terms of resolution, dynamic performance, multiplexing capabilities and reliability. The use of linear filters, array waveguide gratings (AWG) as multiple linear filters and AWG based centroid signal processing techniques will be addressed as well as interrogation techniques based on tunable micro-ring resonators and Mach-Zehnder interferometers (MZI) for phase sensitive detection. The paper will also discuss the challenges and perspectives of photonic integration to address the increasing requirements of several industrial applications.

  13. Caesarean Section Rates in South Africa: evidence of bias among differentpopulation groups’

    Science.gov (United States)

    MATSHIDZE, K. PATRICK; RICHTER, LINDA M.; ELLISON, GEORGE T. H.; LEVIN, JONATHAN B.; McINTYRE, JAMES A.

    2007-01-01

    Objective The aim of this study was to assess the effect of ‘population group’ classification, as a specific instance of ‘racial’ categorization, on caesarean section rates in South Africa. Design Information on ‘population group’ classification (‘Black’, ‘Coloured’, ‘Indian’ or ‘White’, as defined under apartheid legislation) and place of delivery, together with basic obstetric, sociodemographic and perinatal data, were extracted from the birth notification forms of 5456 children who made up the birth cohort of the Birth to Ten longitudinal study. This cohort included all births that occurred to mothers resident in Soweto-Johannesburg during a 7-week period in 1990. Results After accounting for differences in maternal age, gravidity, birth weight and gestational age at delivery, the rate of caesarean sections at private facilities was more than twice that at public facilities. Although there were significant differences in the utilisation of private facilities by women from differentpopulation groups’, there was an independent effect of ‘population group’ classification on caesarean section rates: caesarean section rates among women classified as ‘White’ and ‘Coloured’ were significantly higher (95% confidence intervals for odds ratios: 1.40-2.42 and 1.05-1.81, respectively) than among women classified as ‘Black’. Conclusion ‘Population group’ differences in caesarean section rates among South African women are not explained by differences in demographic risk factors for assisted delivery, nor by differences in access to private health care. Instead, the differences in section rates may reflect the effect of bias in clinical decision-making, and/or differences among women from differentpopulation groups’ in their attitude towards assisted delivery, and their capacity to negotiate with clinicians. PMID:9673465

  14. Genetic affinity among five different population groups in India reflecting a Y-chromosome gene flow.

    Science.gov (United States)

    Saha, Anjana; Sharma, Swarkar; Bhat, Audesh; Pandit, Awadesh; Bamezai, Ramesh

    2005-01-01

    Four binary polymorphisms and four multiallelic short tandem repeat (STR) loci from the nonrecombining region of the human Y-chromosome were typed in different Indian population groups from Uttar Pradeh (UP), Bihar (BI), Punjab (PUNJ), and Bengal (WB) speaking the Indo-Aryan dialects and from South India (SI) with the root in the Dravidian language. We identified four major haplogroups [(P) 1+, (C and F) 2+, (R1a) 3, (K) 26+] and 114 combinations of Y-STR haplotypes. Analyses of the haplogroups indicated no single origin from any lineage but a result of a conglomeration of different lineages from time to time. The phylogenetic analyses indicate a high degree of population admixture and a greater genetic proximity for the studied population groups when compared with other world populations.

  15. Competition between Plant-Populations with Different Rooting Depths. 1. Theoretical Considerations

    NARCIS (Netherlands)

    Berendse, F.

    1979-01-01

    As an extension of De Wit's competition theory a theoretical description has been developed of competition between plant populations with different rooting depths. This model shows that in mixtures of plants with different rooting depths the value of the Relative Yield Total can be expected to

  16. Competition Between Plant Populations with Different Rooting Depths I. Theoretical Considerations

    NARCIS (Netherlands)

    Berendse, Frank

    1979-01-01

    As an extension of De Wit’s competition theory a theoretical description has been developed of competition between plant populations with different rooting depths. This model shows that in mixtures of plants with different rooting depths the value of the Relative Yield Total can be expected to

  17. Explaining sex differences in chronic musculoskeletal pain in a general population.

    NARCIS (Netherlands)

    Wijnhoven, Hanneke A H; Vet, Henrica C W de; Picavet, H Susan J

    2006-01-01

    Many studies report a female predominance in the prevalence of chronic musculoskeletal pain (CMP) but the mechanisms explaining these sex differences are poorly understood. Data from a random postal questionnaire survey in the Dutch general population were used to examine whether sex differences in

  18. The differing magnitude distributions of the two Jupiter Trojan color populations

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Ian; Brown, Michael E. [Division of Geological and Planetary Sciences, California Institute of Technology Pasadena, CA 91125 (United States); Emery, Joshua P., E-mail: iwong@caltech.edu [Department of Earth and Planetary Sciences, University of Tennessee Knoxville, TN 37996 (United States)

    2014-12-01

    The Jupiter Trojans are a significant population of minor bodies in the middle solar system that have garnered substantial interest in recent years. Several spectroscopic studies of these objects have revealed notable bimodalities with respect to near-infrared spectra, infrared albedo, and color, which suggest the existence of two distinct groups among the Trojan population. In this paper, we analyze the magnitude distributions of these two groups, which we refer to as the red and less red color populations. By compiling spectral and photometric data from several previous works, we show that the observed bimodalities are self-consistent and categorize 221 of the 842 Trojans with absolute magnitudes in the range H<12.3 into the two color populations. We demonstrate that the magnitude distributions of the two color populations are distinct to a high confidence level (>95%) and fit them individually to a broken power law, with special attention given to evaluating and correcting for incompleteness in the Trojan catalog as well as incompleteness in our categorization of objects. A comparison of the best-fit curves shows that the faint-end power-law slopes are markedly different for the two color populations, which indicates that the red and less red Trojans likely formed in different locations. We propose a few hypotheses for the origin and evolution of the Trojan population based on the analyzed data.

  19. Estimation of the ancestral effective population sizes of African great apes under different selection regimes.

    Science.gov (United States)

    Schrago, Carlos G

    2014-08-01

    Reliable estimates of ancestral effective population sizes are necessary to unveil the population-level phenomena that shaped the phylogeny and molecular evolution of the African great apes. Although several methods have previously been applied to infer ancestral effective population sizes, an analysis of the influence of the selective regime on the estimates of ancestral demography has not been thoroughly conducted. In this study, three independent data sets under different selective regimes were used were composed to tackle this issue. The results showed that selection had a significant impact on the estimates of ancestral effective population sizes of the African great apes. The inference of the ancestral demography of African great apes was affected by the selection regime. The effects, however, were not homogeneous along the ancestral populations of great apes. The effective population size of the ancestor of humans and chimpanzees was more impacted by the selection regime when compared to the same parameter in the ancestor of humans, chimpanzees and gorillas. Because the selection regime influenced the estimates of ancestral effective population size, it is reasonable to assume that a portion of the discrepancy found in previous studies that inferred the ancestral effective population size may be attributable to the differential action of selection on the genes sampled.

  20. Bragg gratings inscription in step-index PMMA optical fiber by femtosecond laser pulses at 400 nm

    Science.gov (United States)

    Hu, X.; Kinet, D.; Chah, K.; Mégret, P.; Caucheteur, C.

    2016-05-01

    In this paper, we report photo-inscription of uniform Bragg gratings in trans-4-stilbenemethanol-doped photosensitive step-index polymer optical fiber. Gratings were produced at ~1575 nm by the phase mask technique with a femtosecond laser emitting at 400 nm with different average optical powers (8 mW, 13 mW and 20 mW). The grating growth dynamics in transmission were monitored during the manufacturing process, showing that the grating grows faster with higher power. Using 20 mW laser beam power, the reflectivity reaches 94 % (8 dB transmission loss) in 70 seconds. Finally, the gratings were characterized in temperature in the range 20 - 45 °C. The thermal sensitivity has been computed equal to - 86.6 pm/°C.

  1. Differences in hydraulic architecture between mesic and xeric Pinus pinaster populations at the seedling stage.

    Science.gov (United States)

    Corcuera, Leyre; Gil-Pelegrín, Eustaquio; Notivol, Eduardo

    2012-12-01

    We studied the intraspecific variability of maritime pine in a set of morphological and physiological traits: soil-to-leaf hydraulic conductance, intrinsic water-use efficiency (WUE, estimated by carbon isotope composition, δ(13)C), root morphology, xylem anatomy, growth and carbon allocation patterns. The data were collected from Pinus pinaster Aiton seedlings (25 half-sib families from five populations) grown in a greenhouse and subjected to water and water-stress treatments. The aims were to relate this variability to differences in water availability at the geographic location of the populations, and to study the potential trade-offs among traits. The drought-stressed seedlings demonstrated a decrease in hydraulic conductance and root surface area and increased WUE and root tip number. The relationships among the growth, morphological, anatomical and physiological traits changed with the scale of study: within the species, among/within populations. The populations showed a highly significant relationship between the percentage reduction in whole-plant hydraulic conductance and WUE. The differences among the populations in root morphology, whole-plant conductance, carbon allocation, plant growth and WUE were significant and consistent with dryness of the site of seed origin. The xeric populations exhibited lower growth and a conservative water use, as opposed to the fast-growing, less water-use-efficient populations from mesic habitats. The xeric and mesic populations, Tamrabta and San Cipriano, respectively, showed the most contrasting traits and were clustered in opposite directions along the main axis in the canonical discriminant analysis under both the control and drought treatments. The results suggest the possibility of selecting the Arenas population, which presents a combination of traits that confer increased growth and drought resistance.

  2. Internal migration and regional differences of population aging: An empirical study of 287 cities in China.

    Science.gov (United States)

    Chen, Rong; Xu, Ping; Li, Fen; Song, Peipei

    2018-04-02

    In addition to birth and death, migration is also an important factor that determines the level of population aging in different regions, especially under the current context of low fertility and low mortality in China. Drawing upon data from the fifth and sixth national population census of 287 prefecture-level cities in China, this study explored the spatial patterns of population aging and its trends from 2000 to 2010 in China. We further examined how the large-scale internal migration was related to the spatial differences and the changes of aging by using multivariate quantitative models. Findings showed that the percentage of elder cities (i.e. proportion of individuals aged 65 and above to total population is higher than 7%) increased from 50% to 90% in the total 287 cities within the decade. We also found that regional imbalances of population aging have changed since 2000 in China. The gap of aging level between East zone and the other three zones (i.e. West, Central, and North-east) has considerably narrowed down. In 2000, Eastern region had the greatest number (65) of and the largest proportion (74.7%) of elder cities among all four regions. By 2010, the proportion (87.4%) of elder cities in the eastern region was slightly lower than Central (91.4%), Western (88.2%) and North-east sectors (91.2%). Results from multivariate quantitative models showed that the regional differences of population aging appear to be affected much more by the large-scale internal migration with clear age selectivity and orientation preference than by the impact of fertility and mortality. Population aging is expected to continue in China, which will in turn exacerbate regional imbalances. Policies and implications are discussed to face the challenges that the divergent aging population may present in China.

  3. Polymorphic Alu Insertion/Deletion in Different Caste and Tribal Populations from South India.

    Science.gov (United States)

    Chinniah, Rathika; Vijayan, Murali; Thirunavukkarasu, Manikandan; Mani, Dhivakar; Raju, Kamaraj; Ravi, Padma Malini; Sivanadham, Ramgopal; C, Kandeepan; N, Mahalakshmi; Karuppiah, Balakrishnan

    2016-01-01

    Seven human-specific Alu markers were studied in 574 unrelated individuals from 10 endogamous groups and 2 hill tribes of Tamil Nadu and Kerala states. DNA was isolated, amplified by PCR-SSP, and subjected to agarose gel electrophoresis, and genotypes were assigned for various Alu loci. Average heterozygosity among caste populations was in the range of 0.292-0.468. Among tribes, the average heterozygosity was higher for Paliyan (0.3759) than for Kani (0.2915). Frequency differences were prominent in all loci studied except Alu CD4. For Alu CD4, the frequency was 0.0363 in Yadavas, a traditional pastoral and herd maintaining population, and 0.2439 in Narikuravars, a nomadic gypsy population. The overall genetic difference (Gst) of 12 populations (castes and tribes) studied was 3.6%, which corresponds to the Gst values of 3.6% recorded earlier for Western Asian populations. Thus, our study confirms the genetic similarities between West Asian populations and South Indian castes and tribes and supported the large scale coastal migrations from Africa into India through West Asia. However, the average genetic difference (Gst) of Kani and Paliyan tribes with other South Indian tribes studied earlier was 8.3%. The average Gst of combined South and North Indian Tribes (CSNIT) was 9.5%. Neighbor joining tree constructed showed close proximity of Kani and Paliyan tribal groups to the other two South Indian tribes, Toda and Irula of Nilgiri hills studied earlier. Further, the analysis revealed the affinities among populations and confirmed the presence of North and South India specific lineages. Our findings have documented the highly diverse (micro differentiated) nature of South Indian tribes, predominantly due to isolation, than the endogamous population groups of South India. Thus, our study firmly established the genetic relationship of South Indian castes and tribes and supported the proposed large scale ancestral migrations from Africa, particularly into South India

  4. Application of holographic sub-wavelength diffraction gratings for monitoring of kinetics of bioprocesses

    International Nuclear Information System (INIS)

    Tamulevičius, Tomas; Šeperys, Rimas; Andrulevičius, Mindaugas; Kopustinskas, Vitoldas; Meškinis, Šarūnas; Tamulevičius, Sigitas; Mikalayeva, Valeryia; Daugelavičius, Rimantas

    2012-01-01

    Highlights: ► Refractive index sensor based on DLC holographic sub-wavelength period grating. ► Spectroscopic analysis of polarized white light reflected from the grating. ► Control of critical wavelength shift and reflectivity changes. ► Testing of model liquid analyte materials. ► Evaluation of interaction between B. subtilis cells and lysozyme. - Abstract: In this work we present a refractive index (RI) sensor based on a sub-wavelength holographic diffraction grating. The sensor chip was fabricated by dry etching of the finely spaced (d = 428 nm) diffraction grating in SiO x doped diamond like carbon (DLC) film. It is shown that employing a fabricated sensor chip, and using the proposed method of analysis of data, one can inspect kinetics of processes in liquids occurring in the vicinity of the grating surface. The method is based on the spectral composition analysis of polarized polychromatic light reflected from the sub-wavelength diffraction grating. The RI measurement system was tested with different model liquid analytes including 25 wt.%, 50 wt.% sugar water solutions, 10 °C, 50 °C distilled water, also Gram-positive bacteria Bacillus subtilis interaction with ion-permeable channels forming antibiotic gramicidin D and a murolytic enzyme lysozyme. Analysis of the data set of specular reflection spectra enabled us to follow the kinetics of the RI changes in the analyte with millisecond resolution. Detectable changes in the effective RI were not worse than Δn = 10 −4 .

  5. Crack displacement sensing and measurement in concrete using circular grating moire fringes and pattern matching

    Science.gov (United States)

    Chan, H. M.; Yen, K. S.; Ratnam, M. M.

    2008-09-01

    The moire method has been extensively studied in the past and applied in various engineering applications. Several techniques are available for generating the moire fringes in these applications, which include moire interferometry, projection moire, shadow moire, moire deflectometry etc. Most of these methods use the superposition of linear gratings to generate the moire patterns. The use of non-linear gratings, such as circular, radial and elongated gratings has received less attention from the research community. The potential of non-linear gratings in engineering measurement has been realized in a limited number of applications, such as rotation measurement, measurement of linear displacement, measurement of expansion coefficients of materials and measurement of strain distribution. In this work, circular gratings of different pitch were applied to the sensing and measurement of crack displacement in concrete structures. Gratings of pitch 0.50 mm and 0.55 mm were generated using computer software and attached to two overlapping acrylic plates that were bonded to either side of the crack. The resulting moire patterns were captured using a standard digital camera and compared with a set of reference patterns generated using a precision positioning stage. Using several image pre-processing stages, such as filtering and morphological operations, and pattern matching the magnitude displacements along two orthogonal axes can be detected with a resolution of 0.05 mm.

  6. Nano-imprint gold grating as refractive index sensor

    International Nuclear Information System (INIS)

    Kumari, Sudha; Mohapatra, Saswat; Moirangthem, Rakesh S.

    2016-01-01

    Large scale of fabrication of plasmonic nanostructures has been a challenging task due to time consuming process and requirement of expensive nanofabrication tools such as electron beam lithography system, focused ion beam system, and extreme UV photolithography system. Here, we present a cost-effective fabrication technique so called soft nanoimprinting to fabricate nanostructures on the larger sample area. In our fabrication process, a commercially available optical DVD disc was used as a template which was imprinted on a polymer glass substrate to prepare 1D polymer nano-grating. A homemade nanoimprinting setup was used in this fabrication process. Further, a label-free refractive index sensor was developed by utilizing the properties of surface plasmon resonance (SPR) of a gold coated 1D polymer nano-grating. Refractive index sensing was tested by exposing different solutions of glycerol-water mixture on the surface of gold nano-grating. The calculated bulk refractive index sensitivity was found to be 751nm/RIU. We believed that our proposed SPR sensor could be a promising candidate for developing low-cost refractive index sensor with high sensitivity on a large scale.

  7. A MEMS torsion magnetic sensor with reflective blazed grating integration

    International Nuclear Information System (INIS)

    Long, Liang; Zhong, Shaolong

    2016-01-01

    A novel magnetic sensor based on a permanent magnet and blazed grating is presented in this paper. The magnetic field is detected by measuring the diffracted wavelength of the blazed grating which is changed by the torsion motion of a torsion sensitive micro-electromechanical system (MEMS) structure with a permanent magnet attached. A V-shape grating structure is obtained by wet etching on a (1 0 0) SOI substrate. When the magnet is magnetized in different directions, the in-plane or out-of-plane magnetic field is detected by a sensor. The MEMS magnetic sensor with a permanent magnet is fabricated after analytical design and bulk micromachining processes. The magnetic-sensing capability of the sensor is tested by fiber-optic detection system. The result shows the sensitivities of the in-plane and out-of-plane magnetic fields are 3.6 pm μ T −1 and 5.7 pm μ T −1 , respectively. Due to utilization of the permanent magnet and fiber-optic detection, the sensor shows excellent capability of covering the high-resolution detection of low-frequency signals. In addition, the sensitive direction of the magnetic sensor can be easily switched by varying the magnetized direction of the permanent magnet, which offers a simple way to achieve tri-axis magnetic sensor application. (paper)

  8. [Results of a cytogenetic study of populations with different radiation risks in the Semipalatinsk region].

    Science.gov (United States)

    Sviatova, G S; Abil'dinova, G Z; Berezina, G M

    2002-03-01

    A cytogenetic study was conducted for the first time on human populations neighboring the Semipalatinsk nuclear test site (STS) and exposed to ionizing radiation for a long period of time. In populations with the extreme and maximum radiation risks, high frequencies of radiation-induced chromosomal markers, including acentric fragments (1.99 +/- 0.10 per 100 cells), dicentrics (0.23 +/- 0.01), ring chromosomes (0.38 +/- 0.14), and stable chromosomal aberrations (1.17 +/- 0.02), were found. These frequencies significantly exceeded those in control populations. The spectrum of chromosomal aberrations and the frequencies of the aberrations of different types in persons living in the areas with the highest radionuclide contamination confirmed the mutagenic effect of radiation on chromosomes in the human populations studied.

  9. Simple design of slanted grating with simplified modal method.

    Science.gov (United States)

    Li, Shubin; Zhou, Changhe; Cao, Hongchao; Wu, Jun

    2014-02-15

    A simplified modal method (SMM) is presented that offers a clear physical image for subwavelength slanted grating. The diffraction characteristic of the slanted grating under Littrow configuration is revealed by the SMM as an equivalent rectangular grating, which is in good agreement with rigorous coupled-wave analysis. Based on the equivalence, we obtained an effective analytic solution for simplifying the design and optimization of a slanted grating. It offers a new approach for design of the slanted grating, e.g., a 1×2 beam splitter can be easily designed. This method should be helpful for designing various new slanted grating devices.

  10. Perturbative approach to continuum generation in a fiber Bragg grating.

    Science.gov (United States)

    Westbrook, P S; Nicholson, J W

    2006-08-21

    We derive a perturbative solution to the nonlinear Schrödinger equation to include the effect of a fiber Bragg grating whose bandgap is much smaller than the pulse bandwidth. The grating generates a slow dispersive wave which may be computed from an integral over the unperturbed solution if nonlinear interaction between the grating and unperturbed waves is negligible. Our approach allows rapid estimation of large grating continuum enhancement peaks from a single nonlinear simulation of the waveguide without grating. We apply our method to uniform and sampled gratings, finding good agreement with full nonlinear simulations, and qualitatively reproducing experimental results.

  11. Genetic distances and phylogenetic trees of different Awassi sheep populations based on DNA sequencing.

    Science.gov (United States)

    Al-Atiyat, R M; Aljumaah, R S

    2014-08-27

    This study aimed to estimate evolutionary distances and to reconstruct phylogeny trees between different Awassi sheep populations. Thirty-two sheep individuals from three different geographical areas of Jordan and the Kingdom of Saudi Arabia (KSA) were randomly sampled. DNA was extracted from the tissue samples and sequenced using the T7 promoter universal primer. Different phylogenetic trees were reconstructed from 0.64-kb DNA sequences using the MEGA software with the best general time reverse distance model. Three methods of distance estimation were then used. The maximum composite likelihood test was considered for reconstructing maximum likelihood, neighbor-joining and UPGMA trees. The maximum likelihood tree indicated three major clusters separated by cytosine (C) and thymine (T). The greatest distance was shown between the South sheep and North sheep. On the other hand, the KSA sheep as an outgroup showed shorter evolutionary distance to the North sheep population than to the others. The neighbor-joining and UPGMA trees showed quite reliable clusters of evolutionary differentiation of Jordan sheep populations from the Saudi population. The overall results support geographical information and ecological types of the sheep populations studied. Summing up, the resulting phylogeny trees may contribute to the limited information about the genetic relatedness and phylogeny of Awassi sheep in nearby Arab countries.

  12. Personality Traits and Behavioral Syndromes in Differently Urbanized Populations of House Sparrows (Passer domesticus)

    Science.gov (United States)

    Bókony, Veronika; Kulcsár, Anna; Tóth, Zoltán; Liker, András

    2012-01-01

    Urbanization creates novel environments for wild animals where selection pressures may differ drastically from those in natural habitats. Adaptation to urban life involves changes in various traits, including behavior. Behavioral traits often vary consistently among individuals, and these so-called personality traits can be correlated with each other, forming behavioral syndromes. Despite their adaptive significance and potential to act as constraints, little is known about the role of animal personality and behavioral syndromes in animals' adaptation to urban habitats. In this study we tested whether differently urbanized habitats select for different personalities and behavioral syndromes by altering the population mean, inter-individual variability, and correlations of personality traits. We captured house sparrows (Passer domesticus) from four different populations along the gradient of urbanization and assessed their behavior in standardized test situations. We found individual consistency in neophobia, risk taking, and activity, constituting three personality axes. On the one hand, urbanization did not consistently affect the mean and variance of these traits, although there were significant differences between some of the populations in food neophobia and risk taking (both in means and variances). On the other hand, both urban and rural birds exhibited a behavioral syndrome including object neophobia, risk taking and activity, whereas food neophobia was part of the syndrome only in rural birds. These results indicate that there are population differences in certain aspects of personality in house sparrows, some of which may be related to habitat urbanization. Our findings suggest that urbanization and/or other population-level habitat differences may not only influence the expression of personality traits but also alter their inter-individual variability and the relationships among them, changing the structure of behavioral syndromes. PMID:22574204

  13. Karyotype Variability and Inter-Population Genomic Differences in Freshwater Ostracods (Crustacea Showing Geographical Parthenogenesis

    Directory of Open Access Journals (Sweden)

    Radka Symonová

    2018-03-01

    Full Text Available Transitions from sexual to asexual reproduction are often associated with polyploidy and increased chromosomal plasticity in asexuals. We investigated chromosomes in the freshwater ostracod species Eucypris virens (Jurine, 1820, where sexual, asexual and mixed populations can be found. Our initial karyotyping of multiple populations from Europe and North Africa, both sexual and asexual, revealed a striking variability in chromosome numbers. This would suggest that chromosomal changes are likely to be accelerated in asexuals because the constraints of meiosis are removed. Hence, we employed comparative genomic hybridization (CGH within and among sexual and asexual populations to get insights into E. virens genome arrangements. CGH disclosed substantial genomic imbalances among the populations analyzed, and three patterns of genome arrangement between these populations: 1. Only putative ribosomal DNA (rDNA-bearing regions were conserved in the two populations compared indicating a high sequence divergence between these populations. This pattern is comparable with our findings at the interspecies level of comparison; 2. Chromosomal regions were shared by both populations to a varying extent with a distinct copy number variation in pericentromeric and presumable rDNA-bearing regions. This indicates a different rate of evolution in repetitive sequences; 3. A mosaic pattern of distribution of genomic material that can be explained as non-reciprocal genetic introgression and evidence of a hybrid origin of these individuals. We show an overall increased chromosomal dynamics in E. virens that is complementary with available phylogenetic and population genetic data reporting highly differentiated diploid sexual and asexual lineages with a wide variety of genetic backgrounds.

  14. Differential tolerance of two Gammarus pulex populations transplanted from different metallogenic regions to a polymetal gradient.

    Science.gov (United States)

    Khan, Farhan R; Irving, Jennifer R; Bury, Nicolas R; Hogstrand, Christer

    2011-03-01

    The River Hayle, Cornwall, UK exhibits pronounced Cu and Zn concentration gradients which were used to compare the metal handling abilities of two populations of Gammarus pulex (Crustacea: Amphipoda). One population was native to the Hayle region (Drym) and presumably has been historically impacted by elevated Cu and Zn levels, whilst naïve gammarids were collected from the River Cray, Kent, UK. Both populations were subject to a 32 day in situ exposure at four R. Hayle sites (Drym, Godolphin, Relubbus and St. Erth). Mortality (LT50), Cu and Zn accumulation and sub-cellular distribution, and oxidative stress (malondialdehyde production) increased with the expected Cu and Zn bioavailabilities at the four sites (i.e. Godolphin>Relubbus>St. Erth>Drym). The naïve population experienced greater metal induced effects in terms of Cu and Zn accumulation, oxidative stress responses and lower LT50s. Analysis of Cu and Zn sub-cellular distribution, however, revealed no significant differences in metal handling. In both populations each metal was localised predominantly to the sub-cellular fraction containing metal bound to metallothionein-like proteins (MTLP) or that holding both metal-rich granules (MRG) and exoskeleton, MTLP and MRG binding being indicative of metal detoxification. However, a greater capacity for detoxified metal storage is not a mechanism implicated in the perceived tolerance of the historically impacted gammarids. Instead our results suggest that the historically impacted population was adapted for lower uptake of Cu and Zn leading to lower bioaccumulation, stress response and ultimately mortality. These results demonstrate not only the usefulness of the in situ methodology, but also that differences in population exposure history can cause significant differences in metal responses during exposure at higher concentrations. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Iridescence in Meat Caused by Surface Gratings

    Directory of Open Access Journals (Sweden)

    Ali Kemal Yetisen

    2013-11-01

    Full Text Available The photonic structure of cut muscle tissues reveals that the well-ordered gratings diffract light, producing iridescent colours. Cut fibrils protruding from the muscle surface create a two-dimensional periodic array, which diffract light at specific wavelengths upon illumination. However, this photonic effect misleads consumers in a negative way to relate the optical phenomenon with the quality of the product. Here we discuss the fundamentals of this optical phenomenon and demonstrate a methodology for quantitatively measuring iridescence caused by diffraction gratings of muscle tissue surface of pork (Sus scrofa domesticus using reflection spectrophotometry. Iridescence was discussed theoretically as a light phenomenon and spectral measurements were taken from the gratings and monitored in real time during controlled drying. The findings show that the intensity of diffraction diminishes as the surface grating was dried with an air flow at 50 °C for 2 min while the diffracted light wavelength was at 585 ± 9 nm. Our findings indicate that the diffraction may be caused by a blazed surface grating. The implications of the study include providing guidelines to minimise the iridescence by altering the surface microstructure, and in consequence, removing the optical effect.

  16. Optical fiber laser sensor with a cavity of 8.6 Km formed by two fiber Bragg gratings used as mirrors

    Energy Technology Data Exchange (ETDEWEB)

    May A, M.; Kuzin, E.A.; Vazquez S, R.A. [Instituto Nacional de Astrofisica, Optica y Electronica, A. P. 51 y 216, C.P. 72000 Puebla (Mexico); Basurto P, M.A. [Universidad Autonoma del Estado de Morelos, Av. Universidad No. 1001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos (Mexico); Shlyagin, M.G.; Marquez B, I. [Centro de Investigacion Cientifica y de Ensenanza Superior de Ensenada, C.P. 22860 Ensenada, Baja California (Mexico)

    2002-07-01

    We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)

  17. Optical fiber laser sensor with a cavity of 8.6 Km formed by two fiber Bragg gratings used as mirrors

    CERN Document Server

    May, M; Vázquez, R A; Basurto, M A; Shlyagin, M G; Márquez, I

    2002-01-01

    We report the operation of a fiber laser sensor made by an Erbium Doped Fiber pumped at 980 nm, an 8.67 km passive fiber and two fiber Bragg gratings placed at the ends of the laser cavity. Under normal conditions, the Bragg gratings have different reflection wavelengths and laser emission is not generated. The two Bragg gratings can be placed at the same reflection wavelength when the Bragg grating with the lowest reflective wavelength is strained which can be used as a sensor element. The laser generation thus shows that the Bragg grating is under strain. Furthermore, our configuration give us the possibility for knowing the distance between two Bragg gratings when the laser beating frequency is measured. A measurement precision better than 25 m in 8.67 Km is shown to be feasible. (Author)

  18. DSM-IV "criterion A" schizophrenia symptoms across ethnically different populations: evidence for differing psychotic symptom content or structural organization?

    Science.gov (United States)

    McLean, Duncan; Thara, Rangaswamy; John, Sujit; Barrett, Robert; Loa, Peter; McGrath, John; Mowry, Bryan

    2014-09-01

    There is significant variation in the expression of schizophrenia across ethnically different populations, and the optimal structural and diagnostic representation of schizophrenia are contested. We contrasted both lifetime frequencies of DSM-IV criterion A (the core symptom criterion of the internationally recognized DSM classification system) symptoms and types/content of delusions and hallucinations in transethnic schizophrenia populations from Australia (n = 776), India (n = 504) and Sarawak, Malaysia (n = 259), to elucidate clinical heterogeneity. Differences in both criterion A symptom composition and symptom content were apparent. Indian individuals with schizophrenia reported negative symptoms more frequently than other sites, whereas individuals from Sarawak reported disorganized symptoms more frequently. Delusions of control and thought broadcast, insertion, or withdrawal were less frequent in Sarawak than Australia. Curiously, a subgroup of 20 Indian individuals with schizophrenia reported no lifetime delusions or hallucinations. These findings potentially challenge the long-held view in psychiatry that schizophrenia is fundamentally similar across cultural groups, with differences in only the content of psychotic symptoms, but equivalence in structural form.

  19. Gender Differences in Depressive Symptom Profile: Results from Nationwide General Population Surveys in Korea.

    Science.gov (United States)

    Kim, Ji-Hyun; Cho, Maeng Je; Hong, Jin Pyo; Bae, Jae Nam; Cho, Seong-Jin; Hahm, Bong-Jin; Lee, Dong-Woo; Park, Jong-Ik; Lee, Jun-Young; Jeon, Hong Jin; Chang, Sung Man

    2015-11-01

    This study investigated gender differences in symptom profiles of major depressive disorder (MDD) in the Korean general population. Data were pooled from the series of nationwide Korean Epidemiologic Catchment Area surveys conducted in 2001, 2006 and 2011, respectively. Of the 18,807 participants, 507 (397 women and 110 men) were diagnosed with MDD within the prior 12 months. In agreement with previous studies, women with MDD appeared to be more vulnerable to experiencing atypical depressive episodes defined as depression with two or more symptoms of fatigue, increased appetite and hypersomnia (P differences in symptomatology of MDD in the general Korean population, and the results are comparable to previous investigations from western societies. Assumingly, the intercultural similarity in female preponderance to atypical depression might reflect the common biological construct underlying the gender difference in mechanism of MDD. In clinical settings, gender differences of MDD should be carefully considered, because these features could be related with treatment response and drug side effects.

  20. Sex differences in subjective and actigraphic sleep measures: A population-based study of elderly persons

    NARCIS (Netherlands)

    Berg, J.F. van den; Miedema, H.M.E.; Tulen, J.H.M.; Hofman, A.; Neven, A.K.; Tiemeier, H.

    2009-01-01

    Study Objectives: To investigate and explain sex differences in subjective and actigraphic sleep parameters in community-dwelling elderly persons. Design: Cross-sectional study. Setting: The study was embedded in the Rotterdam Study, a population-based study. Participants: Nine hundred fifty-six

  1. Neurotoxic and Cytotoxic Effects of Venom from Different Populations of the Egyptian Scorpio Maurus Palmatus

    Science.gov (United States)

    Neurotoxic and cytotoxic effects of venoms from Scorpio maurus palmatus taken from different populations were assessed for geographic based variability in toxicity and to evaluate their insecticidal potency. Scorpions were collected from four regions. Three locations were mutually isolated pockets i...

  2. Genetic analysis of Phytophthora nicotianae populations from different hosts using microsatellite markers

    Science.gov (United States)

    Two hundred thirty-one isolates of P. nicotianae representing 14 populations from different host genera, including agricultural crops (Citrus, Nicotiana, and Lycopersicon), potted ornamental species in nurseries (Lavandula, Convolvulus, Myrtus, Correa and Ruta) and other plant genera of lesser econo...

  3. Polonioum 210 levels in urine of different groups of italian population

    International Nuclear Information System (INIS)

    Mancini, L.; Renzetti, A.; Santori, G.

    1984-01-01

    Samples of urine obtained from different groups of the italian population has been analized to determine the content of polonium-210. The analysis has been carried out with samples from people with high probability of exposure to radon and hits daughters

  4. Behavioural and morphological differences between lake and river populations of Salaria fluviatilis

    NARCIS (Netherlands)

    Neat, F.C.; Lengkeek, W.; Westerbeek, P.; Laarhoven, B.; Videler, J.J

    Three populations (one from a river and two from lakes) of Salaria fluviatilis, the only exclusively freshwater representative of the Blenniidae, showed significant differences in reproductive behaviour and morphology. Breeding males and females were significantly larger at maturity in the river

  5. Population biology of intestinal Enterococcus Isolates from hospitalized and nonhospitalized individuals in different age groups

    NARCIS (Netherlands)

    Tedim, Ana P.; Ruiz-Garbajosa, Patricia; Corander, Jukka; Rodríguez, Concepción M.; Cantón, Rafael; Willems, Rob J.; Baquero, Fernando; Coque, Teresa M.

    2015-01-01

    The diversity of enterococcal populations from fecal samples from hospitalized (n=133) and nonhospitalized individuals (n= 173) of different age groups (group I, ages 0 to 19 years; group II, ages 20 to 59 years; group III, ages≥60 years) was analyzed. Enterococci were recovered at similar rates

  6. Locomotor performance of cane toads differs between native-range and invasive populations.

    Science.gov (United States)

    Kosmala, Georgia; Christian, Keith; Brown, Gregory; Shine, Richard

    2017-07-01

    Invasive species provide a robust opportunity to evaluate how animals deal with novel environmental challenges. Shifts in locomotor performance-and thus the ability to disperse-(and especially, the degree to which it is constrained by thermal and hydric extremes) are of special importance, because they might affect the rate that an invader can spread. We studied cane toads ( Rhinella marina ) across a broad geographical range: two populations within the species' native range in Brazil, two invasive populations on the island of Hawai'i and eight invasive populations encompassing the eastern, western and southern limits of the toad invasion in Australia. A toad's locomotor performance on a circular raceway was strongly affected by both its temperature and its hydration state, but the nature and magnitude of those constraints differed across populations. In their native range, cane toads exhibited relatively low performance (even under optimal test conditions) and a rapid decrease in performance at lower temperatures and hydration levels. At the other extreme, performance was high in toads from southern Australia, and virtually unaffected by desiccation. Hawai'ian toads broadly resembled their Brazilian conspecifics, plausibly reflecting similar climatic conditions. The invasion of Australia has been accompanied by a dramatic enhancement in the toads' locomotor abilities, and (in some populations) by an ability to maintain locomotor performance even when the animal is cold and/or dehydrated. The geographical divergences in performance among cane toad populations graphically attest to the adaptability of invasive species in the face of novel abiotic challenges.

  7. Healthy Eating Habits among the Population of Serbia: Gender and Age Differences

    OpenAIRE

    Jovi?i?, Ana ?.

    2015-01-01

    ABSTRACT The purpose of the study is to examine healthy eating habits of the population of Serbia through three dimensions: knowledge, problems, and feelings as well as to determine whether there are any differences between genders and among different age-groups. The research instrument was an Eating Habits Questionnaire (EHQ) which consisted of 35 items. There were 382 respondents involved in the study. The reliability and factor structure of the questionnaire were verified by using factor a...

  8. Experimental evidence of population differences in reproductive investment conditional on environmental stochasticity

    Energy Technology Data Exchange (ETDEWEB)

    Gauthey, Zoé [INRA, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, Aquapôle, quartier Ibarron, 64310 Saint-Pée sur Nivelle (France); Univ Pau & Pays Adour, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, UFR Sciences et Techniques de la Côte Basque, Allée du parc Montaury, 64600 Anglet (France); Panserat, Stéphane [INRA, UR 107, Nutrition Metabolism Aquaculture, Aquapôle, 64310 Saint Pée sur Nivelle (France); Elosegi, Arturo [Faculty of Science and Technology, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); Herman, Alexandre [INRA, UR 107, Nutrition Metabolism Aquaculture, Aquapôle, 64310 Saint Pée sur Nivelle (France); Tentelier, Cédric [INRA, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, Aquapôle, quartier Ibarron, 64310 Saint-Pée sur Nivelle (France); Univ Pau & Pays Adour, UMR 1224, Ecologie Comportementale et Biologie des Populations de Poissons, UFR Sciences et Techniques de la Côte Basque, Allée du parc Montaury, 64600 Anglet (France); and others

    2016-01-15

    Environmental stochasticity is expected to shape life histories of species, wherein organisms subjected to strong environmental variation should display adaptive response by being able to tune their reproductive investment. For riverine ecosystems, climate models forecast an increase in the frequency and intensity of extreme events such as floods and droughts. The speed and the mechanisms by which organisms may adapt their reproductive investment are therefore of primary importance to understand how species will cope with such radical environmental changes. In the present study, we sampled spawners from two different populations of wild brown trout, originating from two environments with contrasting levels of flow stochasticity. We placed them in sympatry within an experimental channel during reproductive season. In one modality, water flow was maintained constant, whereas in another modality, water flow was highly variable. Reproductive investment of all individuals was monitored using weight and energetic plasma metabolite variation throughout the reproductive season. Only the populations originating from the most variable environment showed a plastic response to experimental manipulation of water flow, the females being able to reduce their weight variation (from 19.2% to 13.1%) and metabolites variations (from 84.2% to 18.6% for triglycerides for instance) under variable flow conditions. These results imply that mechanisms to cope with environmental stochasticity can differ between populations of the same species, where some populations can be plastic whereas other cannot. - Highlights: • We place two populations of brown trout under contrasting water flow for reproduction. • Energetic metabolite variation is used as a cue of reproductive investment. • In constant flow, both populations show the same reproductive investment. • In variable flow, only one of the populations modifies its reproductive investment. • Divergent evolution of reproductive

  9. Experimental evidence of population differences in reproductive investment conditional on environmental stochasticity

    International Nuclear Information System (INIS)

    Gauthey, Zoé; Panserat, Stéphane; Elosegi, Arturo; Herman, Alexandre; Tentelier, Cédric

    2016-01-01

    Environmental stochasticity is expected to shape life histories of species, wherein organisms subjected to strong environmental variation should display adaptive response by being able to tune their reproductive investment. For riverine ecosystems, climate models forecast an increase in the frequency and intensity of extreme events such as floods and droughts. The speed and the mechanisms by which organisms may adapt their reproductive investment are therefore of primary importance to understand how species will cope with such radical environmental changes. In the present study, we sampled spawners from two different populations of wild brown trout, originating from two environments with contrasting levels of flow stochasticity. We placed them in sympatry within an experimental channel during reproductive season. In one modality, water flow was maintained constant, whereas in another modality, water flow was highly variable. Reproductive investment of all individuals was monitored using weight and energetic plasma metabolite variation throughout the reproductive season. Only the populations originating from the most variable environment showed a plastic response to experimental manipulation of water flow, the females being able to reduce their weight variation (from 19.2% to 13.1%) and metabolites variations (from 84.2% to 18.6% for triglycerides for instance) under variable flow conditions. These results imply that mechanisms to cope with environmental stochasticity can differ between populations of the same species, where some populations can be plastic whereas other cannot. - Highlights: • We place two populations of brown trout under contrasting water flow for reproduction. • Energetic metabolite variation is used as a cue of reproductive investment. • In constant flow, both populations show the same reproductive investment. • In variable flow, only one of the populations modifies its reproductive investment. • Divergent evolution of reproductive

  10. Grating array systems having a plurality of gratings operative in a coherently additive mode and methods for making such grating array systems

    Science.gov (United States)

    Kessler, Terrance J [Mendon, NY; Bunkenburg, Joachim [Victor, NY; Huang, Hu [Pittsford, NY

    2007-02-13

    A plurality of gratings (G1, G2) are arranged together with a wavefront sensor, actuators, and feedback system to align the gratings in such a manner, that they operate like a single, large, monolithic grating. Sub-wavelength-scale movements in the mechanical mounting, due to environmental influences, are monitored by an interferometer (28), and compensated by precision actuators (16, 18, 20) that maintain the coherently additive mode. The actuators define the grating plane, and are positioned in response to the wavefronts from the gratings and a reference flat, thus producing the interferogram that contains the alignment information. Movement of the actuators is also in response to a diffraction-limited spot on the CCD (36) to which light diffracted from the gratings is focused. The actuator geometry is implemented to take advantage of the compensating nature of the degrees of freedom between gratings, reducing the number of necessary control variables.

  11. Interarm blood pressure difference and target organ damage in the general population.

    Science.gov (United States)

    Johansson, Jouni K; Puukka, Pauli J; Jula, Antti M

    2014-02-01

    The objective of the study was to investigate interarm differences of blood pressure (BP) and its determinants, and to clarify whether both arms are equally good in assessing BP and target organ damage in the general population. We studied a representative sample of Finnish adult population with 484 study participants, ages 25-74 years. BP was measured twice by an oscillometric monitor simultaneously on both arms. Study participants underwent a clinical examination including measurements of serum lipids, glucose and indicators of target organ damage. BP was 2.3/0.2 mmHg higher on right than on left arm (P differences). SBP and DBP measured on right and left arms correlated equally with left ventricular mass index (LVMI), interventricular septal thickness (IVST), posterior wall thickness (PWT), pulse wave velocity (PWV) and albuminuria. Higher SBP level was an independent determinant of both greater systolic and diastolic interarm BP difference. Exaggerated absolute diastolic interarm BP difference (>5 mmHg) was associated with higher BMI, arm circumference, LVMI, IVST and PWT, whereas exaggerated absolute systolic interarm BP difference (>10 mmHg) was not associated with any clinical variables. There was only a small difference in BP between arms in a healthy general population. Both arms are equally good determinants of target organ damage. BP should be measured at least once on both arms and prefer the arm with higher BP readings in the future BP measurements.

  12. Common features of sexual dimorphism in the cranial airways of different human populations.

    Science.gov (United States)

    Bastir, Markus; Godoy, Paula; Rosas, Antonio

    2011-11-01

    Sexual dimorphism in the human craniofacial system is an important feature of intraspecific variation in recent and fossil humans. Although several studies have reported different morphological patterns of sexual dimorphism in different populations, this study searches for common morphological aspects related to functional anatomy of the respiratory apparatus. 3D geometric morphometrics were used to test the hypothesis that due to higher daily energy expenditure and associated greater respiratory air consumption as well as differences in body composition, males should have absolutely and relatively greater air passages in the bony cranial airways than females. We measured 25 3D landmarks in five populations (N = 212) of adult humans from different geographic regions. Male average cranial airways were larger in centroid sizes than female ones. Males tended to show relatively taller piriform apertures and, more consistently, relatively taller internal nasal cavities and choanae than females. Multivariate regressions and residual analysis further indicated that after standardizing to the same size, males still show relatively larger airway passages than females. Because the dimensions of the choanae are limiting factors for air transmission towards the noncranial part of the respiratory system, the identified sex-specific differences in cranial airways, possibly shared among human populations, may be linked with sex-specific differences in body size, composition, and energetics. These findings may be important to understanding trends in hominin facial evolution. Copyright © 2011 Wiley-Liss, Inc.

  13. Diffraction by m-bonacci gratings

    International Nuclear Information System (INIS)

    Monsoriu, Juan A; Giménez, Marcos H; Furlan, Walter D; Barreiro, Juan C; Saavedra, Genaro

    2015-01-01

    We present a simple diffraction experiment with m-bonacci gratings as a new interesting generalization of the Fibonacci ones. Diffraction by these non-conventional structures is proposed as a motivational strategy to introduce students to basic research activities. The Fraunhofer diffraction patterns are obtained with the standard equipment present in most undergraduate physics labs and are compared with those obtained with regular periodic gratings. We show that m-bonacci gratings produce discrete Fraunhofer patterns characterized by a set of diffraction peaks which positions are related to the concept of a generalized golden mean. A very good agreement is obtained between experimental and numerical results and the students’ feedback is discussed. (paper)

  14. An ultra-high-vacuum multiple grating chamber and scan drive with improved grating change

    International Nuclear Information System (INIS)

    Hulbert, S.L.; Holly, D.J.; Middleton, F.H.; Wallace, D.J.; Wisconsin Univ., Stoughton, WI; Wisconsin Univ., Stoughton, WI

    1989-01-01

    We describe a new grating chamber and scan drive which has been designed, built, and tested by Physical Sciences Laboratory of the University of Wisconsin for the new high flux, high-resolution spectroscopy branch line of the TOK hybrid wiggler/undulator on the NSLS VUV ring. The chamber will contain spherical gratings to be used in the Spherical Grating Monochromator (SGM) configuration introduced by Chen and Sette. The grating chamber houses five 180 mm x 35 mm x 30 mm gratings capable of scanning a range of 12 degree (-14 degree to +8 degree with respect to the incoming beam direction) for VUV and soft X-ray diffraction. The gratings can be switched and precisely indexed while under ultra-high vacuum (UHV) at any scan angle and are mechanically isolated from the vacuum chamber to prevent inaccuracies due to chamber distortions. The gratings can separately be adjusted for height, yaw, pitch, and roll, with the latter three performed while in vacuo. The scan drive provides a resolution of 0.03 arc sec with linearity over the 12 degree range of ∼1.5 arc sec and absolute reproducibility of 1 arc sec. 5 refs., 5 figs

  15. Comparative population structure of Plasmodium malariae and Plasmodium falciparum under different transmission settings in Malawi

    Directory of Open Access Journals (Sweden)

    Molyneux Malcolm E

    2011-02-01

    Full Text Available Abstract Background Described here is the first population genetic study of Plasmodium malariae, the causative agent of quartan malaria. Although not as deadly as Plasmodium falciparum, P. malariae is more common than previously thought, and is frequently in sympatry and co-infection with P. falciparum, making its study increasingly important. This study compares the population parameters of the two species in two districts of Malawi with different malaria transmission patterns - one seasonal, one perennial - to explore the effects of transmission on population structures. Methods Six species-specific microsatellite markers were used to analyse 257 P. malariae samples and 257 P. falciparum samples matched for age, gender and village of residence. Allele sizes were scored to within 2 bp for each locus and haplotypes were constructed from dominant alleles in multiple infections. Analysis of multiplicity of infection (MOI, population differentiation, clustering of haplotypes and linkage disequilibrium was performed for both species. Regression analyses were used to determine association of MOI measurements with clinical malaria parameters. Results Multiple-genotype infections within each species were common in both districts, accounting for 86.0% of P. falciparum and 73.2% of P. malariae infections and did not differ significantly with transmission setting. Mean MOI of P. falciparum was increased under perennial transmission compared with seasonal (3.14 vs 2.59, p = 0.008 and was greater in children compared with adults. In contrast, P. malariae mean MOI was similar between transmission settings (2.12 vs 2.11 and there was no difference between children and adults. Population differentiation showed no significant differences between villages or districts for either species. There was no evidence of geographical clustering of haplotypes. Linkage disequilibrium amongst loci was found only for P. falciparum samples from the seasonal transmission

  16. Karyological studies in ten different populations of desert lily aloe vera from pakistan

    International Nuclear Information System (INIS)

    Jahan, B.; Vahidy, A.A.

    2014-01-01

    To enhance theoretical basis of Aloe feeding and provide cytological basement, the karyotype and morphology of mitotic chromosomes, ten different populations of Aloe vera collected from various geographical locations of Karachi, Pakistan were studied by aceto-orcein staining technique. The results showed that chromosome number of Aloe vera is 2n=14. The karyotype is bimodal and consists of 14 chromosomes (8 large and 6 small) predominantly with submedian, median and subterminal centromere. Average chromosome lengths among populations ranged from 7.95-2.36 micro m. (author)

  17. Lipid Multilayer Grating Arrays Integrated by Nanointaglio for Vapor Sensing by an Optical Nose

    Directory of Open Access Journals (Sweden)

    Troy W. Lowry

    2015-08-01

    Full Text Available Lipid multilayer gratings are recently invented nanomechanical sensor elements that are capable of transducing molecular binding to fluid lipid multilayers into optical signals in a label free manner due to shape changes in the lipid nanostructures. Here, we show that nanointaglio is suitable for the integration of chemically different lipid multilayer gratings into a sensor array capable of distinguishing vapors by means of an optical nose. Sensor arrays composed of six different lipid formulations are integrated onto a surface and their optical response to three different vapors (water, ethanol and acetone in air as well as pH under water is monitored as a function of time. Principal component analysis of the array response results in distinct clustering indicating the suitability of the arrays for distinguishing these analytes. Importantly, the nanointaglio process used here is capable of producing lipid gratings out of different materials with sufficiently uniform heights for the fabrication of an optical nose.

  18. Lipid Multilayer Grating Arrays Integrated by Nanointaglio for Vapor Sensing by an Optical Nose

    Science.gov (United States)

    Lowry, Troy W.; Prommapan, Plengchart; Rainer, Quinn; Van Winkle, David; Lenhert, Steven

    2015-01-01

    Lipid multilayer gratings are recently invented nanomechanical sensor elements that are capable of transducing molecular binding to fluid lipid multilayers into optical signals in a label free manner due to shape changes in the lipid nanostructures. Here, we show that nanointaglio is suitable for the integration of chemically different lipid multilayer gratings into a sensor array capable of distinguishing vapors by means of an optical nose. Sensor arrays composed of six different lipid formulations are integrated onto a surface and their optical response to three different vapors (water, ethanol and acetone) in air as well as pH under water is monitored as a function of time. Principal component analysis of the array response results in distinct clustering indicating the suitability of the arrays for distinguishing these analytes. Importantly, the nanointaglio process used here is capable of producing lipid gratings out of different materials with sufficiently uniform heights for the fabrication of an optical nose. PMID:26308001

  19. Mental health differences between German gay and bisexual men and population-based controls.

    Science.gov (United States)

    Sattler, Frank A; Franke, Gabriele H; Christiansen, Hanna

    2017-07-21

    International studies have revealed that gay and bisexual men present more mental health problems than the general male population. Furthermore, there is evidence that minority stress predicts mental health problems in gay and bisexual men. The aim of the present study is to provide initial data on mental health differences in Germany and to analyze the effect of minority stress. Mental health data on n = 1903 German gay and bisexual men and n = 958 men from a population-based sample were assessed using a shortened version of the SCL-90-S. The mental health of the two samples was compared. Furthermore, a linear regression was conducted for the gay and bisexual sample: mental health was used as the criterion and minority stressors as predictors. As compared to our population sample, gay and bisexual men demonstrated more mental health problems with a moderate effect size. In the regression, minority stress predicted mental health problems in the gay and bisexual sample. We observed pronounced mental health differences between gay and bisexual men versus the population sample. These differences could be at least partly due to the minority stress gay and bisexual men face. Research should focus on how to reduce and cope with minority stress.

  20. Vacuum Predisperser For A Large Plane-Grating Spectrograph

    Science.gov (United States)

    Engleman, R.; Palmer, B. A.; Steinhaus, D. W.

    1980-11-01

    A plane grating predisperser has been constructed which acts as an "order-sorter" for a large plane-grating spectrograph. This combination can photograph relatively wide regions of spectra in a single exposure with no loss of resolution.

  1. Underwater Acoustic Sensors Based on Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    Giuseppe Parente

    2009-06-01

    Full Text Available We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular, new experiments have been carried out using a cylindrical geometry with two different coating, showing that the sensitivity is not influenced by the shape but by the transversal dimension and the material characteristics of the coating.

  2. Multiwavelength optical scatterometry of dielectric gratings

    KAUST Repository

    Yashina, Nataliya P.

    2012-08-01

    Modern scatterometry problems arising in the lithography production of periodic gratings are in the focus of the work. The performance capabilities of a novel theoretical and numerical modeling oriented to these problems are considered. The approach is based on rigorous solutions of 2-D initial boundary value problems of the gratings theory. The quintessence and advantage of the method is the possibility to perform an efficient analysis simultaneously and interactively both for steady state and transient processes of the resonant scattering of electromagnetic waves by the infinite and compact periodic structures. © 2012 IEEE.

  3. Regional differences, socio-demographics, and hidden population of HIV/AIDS in India.

    Science.gov (United States)

    Kumar, Rajeev; Suar, Damodar; Singh, Sanjay Kumar

    2017-02-01

    This study examines the prevalence of HIV/AIDS in different regions of India, their socio-demographic indicators, and the presence of hidden population infected with HIV. Secondary data analyzed were obtained from national and international agencies. Considering the prevalence of HIV/AIDS in India, the low-prevalence regions in the last decade have shown a steady increase in recent years. Productive age, urbanization, male gender, lower level of education, minority religions, low income, and mobile occupations are associated with HIV pandemic. The hidden population vulnerable to HIV/AIDS are: street children, homeless population, and refugees. These observations can help map the high-risk behavior groups and formulate targeted strategies to curb the HIV menace.

  4. Cultural inter-population differences do not reflect biological distances: an example of interdisciplinary analysis of populations from Eastern Adriatic coast.

    Science.gov (United States)

    Bašić, Željana; Fox, Ayano R; Anterić, Ivana; Jerković, Ivan; Polašek, Ozren; Anđelinović, Šimun; Holland, Mitchell M; Primorac, Dragan

    2015-06-01

    To compare the population group from the Šopot graveyard with population groups from traditional Croatian medieval graveyards by using anthropological, craniometrics, and mitochondrial (mtDNA) analysis and to examine if the cultural differences between population groups reflect biological differences. We determined sex, age at death, pathological, and traumatic changes of skeletal remains from the Šopot graveyard and compared them with a cumulative medieval sample from the same region. We also performed principal component analysis to compare skeletal remains from Šopot with those from Ostrovica and other Central European samples according to 8 cranial measurements. Finally, we compared 46 skeletons from Šopot with medieval (Ostrovica) and contemporary populations using mDNA haplogroup profiling. The remains from Šopot were similar to the cumulative sample in lifestyle and quality of life markers. Principal component analysis showed that they were closely related to Eastern Adriatic coast sites (including Ostrovica and Šopot) in terms of cranial morphology, indicating similar biological makeup. According to mDNA testing, Šopot population showed no significant differences in the haplogroup prevalence from either medieval or contemporary populations. This study shows that the Šopot population does not significantly differ from other medieval populations from this area. Besides similar quality of life markers, these populations also had similar biological markers. Substantial archeological differences can therefore be attributed to apparent cultural influences, which in this case do not reflect biological differences.

  5. Transparent Electrochemical Gratings from a Patterned Bistable Silver Mirror.

    Science.gov (United States)

    Park, Chihyun; Na, Jongbeom; Han, Minsu; Kim, Eunkyoung

    2017-07-25

    Silver mirror patterns were formed reversibly on a polystyrene (PS)-patterned electrode to produce gratings through the electrochemical reduction of silver ions. The electrochemical gratings exhibited high transparency (T > 95%), similar to a see-through window, by matching the refractive index of the grating pattern with the surrounding medium. The gratings switch to a diffractive state upon the formation of a mirror pattern (T modulation, NIR light reflection, and on-demand heat transfer.

  6. Multicore optical fiber grating array fabrication for medical sensing applications

    Science.gov (United States)

    Westbrook, Paul S.; Feder, K. S.; Kremp, T.; Taunay, T. F.; Monberg, E.; Puc, G.; Ortiz, R.

    2015-03-01

    In this work we report on a fiber grating fabrication platform suitable for parallel fabrication of Bragg grating arrays over arbitrary lengths of multicore optical fiber. Our system exploits UV transparent coatings and has precision fiber translation that allows for quasi-continuous grating fabrication. Our system is capable of both uniform and chirped fiber grating array spectra that can meet the demands of medical sensors including high speed, accuracy, robustness and small form factor.

  7. Optically controlled tunable dispersion compensators based on pumped fiber gratings.

    Science.gov (United States)

    Shu, Xuewen; Sugden, Kate; Bennion, Ian

    2011-08-01

    We demonstrate optically tunable dispersion compensators based on pumping fiber Bragg gratings made in Er/Yb codoped fiber. The tunable dispersion for a chirped grating and also a uniform-period grating was successfully demonstrated in the experiment. The dispersion of the chirped grating was tuned from 900 to 1990 ps/nm and also from -600 to -950 ps/nm in the experiment. © 2011 Optical Society of America

  8. Distinguishing Antimicrobial Models with Different Resistance Mechanisms via Population Pharmacodynamic Modeling.

    Directory of Open Access Journals (Sweden)

    Matthieu Jacobs

    2016-03-01

    Full Text Available Semi-mechanistic pharmacokinetic-pharmacodynamic (PK-PD modeling is increasingly used for antimicrobial drug development and optimization of dosage regimens, but systematic simulation-estimation studies to distinguish between competing PD models are lacking. This study compared the ability of static and dynamic in vitro infection models to distinguish between models with different resistance mechanisms and support accurate and precise parameter estimation. Monte Carlo simulations (MCS were performed for models with one susceptible bacterial population without (M1 or with a resting stage (M2, a one population model with adaptive resistance (M5, models with pre-existing susceptible and resistant populations without (M3 or with (M4 inter-conversion, and a model with two pre-existing populations with adaptive resistance (M6. For each model, 200 datasets of the total bacterial population were simulated over 24h using static antibiotic concentrations (256-fold concentration range or over 48h under dynamic conditions (dosing every 12h; elimination half-life: 1h. Twelve-hundred random datasets (each containing 20 curves for static or four curves for dynamic conditions were generated by bootstrapping. Each dataset was estimated by all six models via population PD modeling to compare bias and precision. For M1 and M3, most parameter estimates were unbiased (<10% and had good imprecision (<30%. However, parameters for adaptive resistance and inter-conversion for M2, M4, M5 and M6 had poor bias and large imprecision under static and dynamic conditions. For datasets that only contained viable counts of the total population, common statistical criteria and diagnostic plots did not support sound identification of the true resistance mechanism. Therefore, it seems advisable to quantify resistant bacteria and characterize their MICs and resistance mechanisms to support extended simulations and translate from in vitro experiments to animal infection models and

  9. Impact of obesity on pregnancy outcome in different ethnic groups: calculating population attributable fractions.

    Directory of Open Access Journals (Sweden)

    Eugene Oteng-Ntim

    Full Text Available OBJECTIVES: To quantify the proportion of adverse pregnancy outcome attributable to maternal obesity. DESIGN: Cross sectional analysis of routine obstetric dataset. SETTING: Guy's and St Thomas's NHS Foundation Trust (GSTFT. POPULATION: 23,668 women who had singleton deliveries at GSTFT between 2004 and 2008. METHODS: Logistic regression was used to estimate the association between BMI and outcome in different ethnic groups. Adjusted odds ratios, and the proportions of obese women, were used to calculate population attributable risk fractions (PAFs. MAIN OUTCOME MEASURES: (I MATERNAL OUTCOMES: diabetes, type of delivery, post-partum haemorrhage, and preterm delivery. (ii Perinatal outcomes: macrosomia, low birth weight, admission to neonatal intensive care/special care baby unit, and perinatal death. RESULTS: The prevalence of maternal obesity was 14%. Increasing BMI was independently associated with increasing risk of adverse obstetric and neonatal outcome. At the individual level, the effect of obesity on diabetes was highest in Asian women compared to white women (p for interaction = 0.03. Calculation of population attributable risk fractions demonstrated that one third of diabetes cases and one in six Caesarean sections could be avoided in this population if all obese women were of normal BMI. At the population level, the contribution of obesity to diabetes was highest for Black women (42%, and lowest for oriental women (8%. Seven percent of neonatal macrosomia in all the population, and 13% in Black mothers, were attributable to obesity. CONCLUSIONS: Preventing obesity prior to pregnancy will substantially reduce the burden of obstetric and neonatal morbidity in this population. This reduction will be higher in Black women.

  10. Grain yield of corn at different population densities and intercropped with forages

    Directory of Open Access Journals (Sweden)

    José M. do Nascimento

    2015-12-01

    Full Text Available ABSTRACT The no-tillage system optimizes agricultural areas, maintaining the supply of straw and promoting crop rotation and soil conservation. The aim of the present study was to evaluate sowing quality and grain yield of corn intercropped with three forage species of the Urochloa genus associated with two corn population densities. The experiment was conducted at the São Paulo State University (UNESP, in Jaboticabal-SP, Brazil. The experimental design was randomized blocks in a 2 x 3 factorial scheme with four replicates. The treatments consisted of two corn densities (55,000 and 75,000 plants ha-1 intercropped with three forages (Urochloa brizantha, Urochloa decumbens and Urochloa ruziziensis sown between rows of corn in the V4 stage. The following corn variables were analysed: mean number of days for emergence, longitudinal distribution, grain yield, initial population and final population. There were differences between corn populations (p < 0.1 and the intercropping of corn with the species U. brizantha and U. ruziziensis promoted the best results, which permitted concluding that the cultivation of corn at the population density of 75,000 plants ha-1 intercropped U. brizantha and U. ruziziensis promoted better sowing quality and, consequently, higher grain yields.

  11. Estimation of the size of the female sex worker population in Rwanda using three different methods.

    Science.gov (United States)

    Mutagoma, Mwumvaneza; Kayitesi, Catherine; Gwiza, Aimé; Ruton, Hinda; Koleros, Andrew; Gupta, Neil; Balisanga, Helene; Riedel, David J; Nsanzimana, Sabin

    2015-10-01

    HIV prevalence is disproportionately high among female sex workers compared to the general population. Many African countries lack useful data on the size of female sex worker populations to inform national HIV programmes. A female sex worker size estimation exercise using three different venue-based methodologies was conducted among female sex workers in all provinces of Rwanda in August 2010. The female sex worker national population size was estimated using capture-recapture and enumeration methods, and the multiplier method was used to estimate the size of the female sex worker population in Kigali. A structured questionnaire was also used to supplement the data. The estimated number of female sex workers by the capture-recapture method was 3205 (95% confidence interval: 2998-3412). The female sex worker size was estimated at 3348 using the enumeration method. In Kigali, the female sex worker size was estimated at 2253 (95% confidence interval: 1916-2524) using the multiplier method. Nearly 80% of all female sex workers in Rwanda were found to be based in the capital, Kigali. This study provided a first-time estimate of the female sex worker population size in Rwanda using capture-recapture, enumeration, and multiplier methods. The capture-recapture and enumeration methods provided similar estimates of female sex worker in Rwanda. Combination of such size estimation methods is feasible and productive in low-resource settings and should be considered vital to inform national HIV programmes. © The Author(s) 2015.

  12. Heritable oxidative phosphorylation differences in a pollutant resistant Fundulus heteroclitus population

    International Nuclear Information System (INIS)

    Du, Xiao; Crawford, Douglas L.; Nacci, Diane E.; Oleksiak, Marjorie F.

    2016-01-01

    Highlights: • Laboratory reared fish from a highly polluted and clean reference population were compared. • Oxidative phosphorylation (e.g., State 3, enzymes, and proton LEAK) was quantified. • Laboratory reared F3 fish from polluted population displayed higher routine metabolism and complex II activity but lower complex I enzyme activity. • Enhanced OxPhos metabolism and toxicity resistance were retained in laboratory reared F3 fish from the polluted population. - Abstract: Populations can adapt to stress including recent anthropogenic pollution. Our published data suggests heritable differences in hepatocyte oxidative phosphorylation (OxPhos) metabolism in field-caught killifish (Fundulus heteroclitus) from the highly polluted Elizabeth River, VA, USA, relative to fish from a nearby, relatively unpolluted reference site in King’s Creek VA. Consistent with other studies showing that Elizabeth River killifish are resistant to some of the toxic effects of certain contaminants, OxPhos measurements in hepatocytes from field-caught King’s Creek but not field-caught Elizabeth River killifish were altered by acute benzo [a] pyrene exposures. To more definitively test whether the enhanced OxPhos metabolism and toxicity resistance are heritable, we measured OxPhos metabolism in a laboratory-reared F3 generation from the Elizabeth River population versus a laboratory-reared F1 generation from the King’s Creek population and compared these results to previous data from the field-caught fish. The F3 Elizabeth River fish compared to F1 King’s Creek fish had significantly higher State 3 respiration (routine metabolism) and complex II activity, and significantly lower complex I activity. The consistently higher routine metabolism in the F3 and field-caught Elizabeth River fish versus F1 and field-caught King’s Creek fish implies a heritable change in OxPhos function. The observation that LEAK, E-State, Complex I and Complex II were different in laboratory bred

  13. Heritable oxidative phosphorylation differences in a pollutant resistant Fundulus heteroclitus population

    Energy Technology Data Exchange (ETDEWEB)

    Du, Xiao, E-mail: xdu@rsmas.miami.edu [Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 (United States); Crawford, Douglas L. [Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 (United States); Nacci, Diane E. [Population Ecology Branch, Atlantic Ecology Division, Office of Research and Development, U.S. Environmental Protection Agency, 27 Tarzwell Dr., Narragansett, RI 02882 (United States); Oleksiak, Marjorie F., E-mail: moleksiak@rsmas.miami.edu [Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 (United States)

    2016-08-15

    Highlights: • Laboratory reared fish from a highly polluted and clean reference population were compared. • Oxidative phosphorylation (e.g., State 3, enzymes, and proton LEAK) was quantified. • Laboratory reared F3 fish from polluted population displayed higher routine metabolism and complex II activity but lower complex I enzyme activity. • Enhanced OxPhos metabolism and toxicity resistance were retained in laboratory reared F3 fish from the polluted population. - Abstract: Populations can adapt to stress including recent anthropogenic pollution. Our published data suggests heritable differences in hepatocyte oxidative phosphorylation (OxPhos) metabolism in field-caught killifish (Fundulus heteroclitus) from the highly polluted Elizabeth River, VA, USA, relative to fish from a nearby, relatively unpolluted reference site in King’s Creek VA. Consistent with other studies showing that Elizabeth River killifish are resistant to some of the toxic effects of certain contaminants, OxPhos measurements in hepatocytes from field-caught King’s Creek but not field-caught Elizabeth River killifish were altered by acute benzo [a] pyrene exposures. To more definitively test whether the enhanced OxPhos metabolism and toxicity resistance are heritable, we measured OxPhos metabolism in a laboratory-reared F3 generation from the Elizabeth River population versus a laboratory-reared F1 generation from the King’s Creek population and compared these results to previous data from the field-caught fish. The F3 Elizabeth River fish compared to F1 King’s Creek fish had significantly higher State 3 respiration (routine metabolism) and complex II activity, and significantly lower complex I activity. The consistently higher routine metabolism in the F3 and field-caught Elizabeth River fish versus F1 and field-caught King’s Creek fish implies a heritable change in OxPhos function. The observation that LEAK, E-State, Complex I and Complex II were different in laboratory bred

  14. Interarm blood pressure difference in a post-stroke population.

    Science.gov (United States)

    Gaynor, Eva; Brewer, Linda; Mellon, Lisa; Hall, Patricia; Horgan, Frances; Shelley, Emer; Dolan, Eamonn; Hickey, Anne; Bennett, Kathleen; Williams, David J

    2017-09-01

    An increased interarm systolic blood pressure (SBP) difference of ≥10 mm Hg is associated with increased cardiovascular risk and a difference of ≥15 mm Hg with increased cerebrovascular risk. The stroke population presents a high-risk group for future cardiovascular and cerebrovascular events and therefore estimation of interarm SBP difference as a predictive tool may assist with further secondary stroke prevention. The aim of the study was to determine the prevalence of interarm SBP and diastolic blood pressure difference in a post-stroke population. A comprehensive assessment of secondary risk factors along with blood pressure measurements were taken 6-months' post-ischemic stroke from the Action on Secondary Prevention Interventions and Rehabilitation in Stroke cohort. Descriptive and logistic regression analyses were performed. Odds ratios and 95% confidence intervals are presented. Two hundred thirty-eight (M: F,139:99; mean age, 68.4 years) of 256 patients followed up at 6 months post-stroke had suitable blood pressure readings from both arms. Ninety-six patients (40.3%) had an interarm SBP difference of ≥10 mm Hg and 49 (20.6%) had a difference of ≥15 mm Hg. A history of hypertension, diabetes, smoking, and obesity was not significantly associated with an increased risk of interarm SBP difference. After multivariate logistic analysis, a history of alcohol excess was associated with an increased IASBP ≥15 mm Hg (odds ratio 2.32, 95% confidence interval 1.03-5.22). We have demonstrated that interarm SBP difference is commonly seen in a post stroke population. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

  15. Apollo 14 regolith breccias - Different glass populations and their potential for charting space time variations

    Science.gov (United States)

    Delano, John W.

    1988-01-01

    Apollo 14 regolith breccias (14313, 14307, 14301, 14049, 14047) have been found to have different populations of nonagglutinitic, mare-derived glasses. These variations appear to not only reflect different source regoliths but also different closure ages for these breccias. Based upon these different glass populations, 14301 is inferred to have a closure age sometime during the epoch of mare volcanism. All of the other four breccias were formed after the termination of mare volcanism with a possible age sequence from old to young of the following: 14307, 14313, 14049, 14047. Due to the relative simplicity of acquiring high-quality chemical data on large numbers of glasses by electron microprobe, mare glass populations allow: (1) classification of regolith breccias with respect to provenance and (2) estimation of their relative and absolute closure ages. The determination of (Ar-40)-(Ar-39) ages on individual glass spherules within breccias using the laser probe should in the future prove to be a promising extension of the present study.

  16. Liquid filling of photonic crystal fibres for grating writing

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Canning, John; Lægsgaard, Jesper

    2007-01-01

    liquid filling of photonic crystal fibres reduces the scattering from air–glass interfaces during Bragg grating writing in many layered photonic crystal fibres. Within experimental uncertainty, the grating index modulation of a grating written in germanium-doped photonic crystal fibre with 10 rings...

  17. Genetic and morphological differences among populations of the Bonin Islands White-eye in Japan.

    Science.gov (United States)

    Kawakami, Kazuto; Harada, Sachiko; Suzuki, Tadashi; Higuchi, Hiroyoshi

    2008-09-01

    The Bonin Islands White-eye, Apalopteron familiare , is the sole endemic avian species surviving on the Bonin Islands. The current distribution of this species is limited to only three islands of the Hahajima Island group: Hahajima, Imotojima, and Mukohjima. Imotojima and Mukohjima, which are small satellite islands of Hahajima, are about 3.6 km and 5.5 km, respectively, from the larger island. To investigate genetic and morphological differences among A. familiare populations on these islands, we assayed 634 bp of mitochondrial control region sequence for 132 birds from five locations among the three islands. We detected five haplotypes: two endemic haplotypes each on Hahajima and Imotojima and one on Mukohjima. Principal component analysis based on eight morphological characters of 162 birds from the three island populations revealed that birds from the small satellite islands had significantly different beak morphological characters. Our findings indicate that over-sea dispersal is rare in A. familiare , even when islands are separated by only a few kilometers, and suggest that little movement occurs on Hahajima. Thus, each population on each island should be conserved as an evolutionarily significant unit. The low dispersal ability of this species suggests that it is vulnerable to habitat fragmentation. Although the populations are currently stable and do not require rapid countermeasures, they should be monitored, especially those on the smaller islands.

  18. Detection of stable community structures within gut microbiota co-occurrence networks from different human populations.

    Science.gov (United States)

    Jackson, Matthew A; Bonder, Marc Jan; Kuncheva, Zhana; Zierer, Jonas; Fu, Jingyuan; Kurilshikov, Alexander; Wijmenga, Cisca; Zhernakova, Alexandra; Bell, Jordana T; Spector, Tim D; Steves, Claire J

    2018-01-01

    Microbes in the gut microbiome form sub-communities based on shared niche specialisations and specific interactions between individual taxa. The inter-microbial relationships that define these communities can be inferred from the co-occurrence of taxa across multiple samples. Here, we present an approach to identify comparable communities within different gut microbiota co-occurrence networks, and demonstrate its use by comparing the gut microbiota community structures of three geographically diverse populations. We combine gut microbiota profiles from 2,764 British, 1,023 Dutch, and 639 Israeli individuals, derive co-occurrence networks between their operational taxonomic units, and detect comparable communities within them. Comparing populations we find that community structure is significantly more similar between datasets than expected by chance. Mapping communities across the datasets, we also show that communities can have similar associations to host phenotypes in different populations. This study shows that the community structure within the gut microbiota is stable across populations, and describes a novel approach that facilitates comparative community-centric microbiome analyses.

  19. Current and historical drivers of landscape genetic structure differ in core and peripheral salamander populations.

    Directory of Open Access Journals (Sweden)

    Rachael Y Dudaniec

    Full Text Available With predicted decreases in genetic diversity and greater genetic differentiation at range peripheries relative to their cores, it can be difficult to distinguish between the roles of current disturbance versus historic processes in shaping contemporary genetic patterns. To address this problem, we test for differences in historic demography and landscape genetic structure of coastal giant salamanders (Dicamptodon tenebrosus in two core regions (Washington State, United States versus the species' northern peripheral region (British Columbia, Canada where the species is listed as threatened. Coalescent-based demographic simulations were consistent with a pattern of post-glacial range expansion, with both ancestral and current estimates of effective population size being much larger within the core region relative to the periphery. However, contrary to predictions of recent human-induced population decline in the less genetically diverse peripheral region, there was no genetic signature of population size change. Effects of current demographic processes on genetic structure were evident using a resistance-based landscape genetics approach. Among core populations, genetic structure was best explained by length of the growing season and isolation by resistance (i.e. a 'flat' landscape, but at the periphery, topography (slope and elevation had the greatest influence on genetic structure. Although reduced genetic variation at the range periphery of D. tenebrosus appears to be largely the result of biogeographical history rather than recent impacts, our analyses suggest that inherent landscape features act to alter dispersal pathways uniquely in different parts of the species' geographic range, with implications for habitat management.

  20. Do Class III patients have a different growth spurt than the general population?

    Science.gov (United States)

    Lee, Yun-Sik; Lee, Shin-Jae; An, Hongseok; Donatelli, Richard E; Kim, Soo-Hwan

    2012-11-01

    Understanding the timing and length of the growth spurt of Class III prognathic patients is fundamental to the strategy of interceptive orthopedic orthodontics as well as to the timing of orthognathic surgery. Consequently, this study was undertaken to determine whether there are any significant differences in the stature growth pattern of Class III subjects compared with non-Class III subjects and the general population. Twelve-year longitudinal stature growth data were collected for 402 randomly selected adolescents in the general population, 55 Class III mandibular prognathic patients, and 37 non-Class III patients. The growth data were analyzed by using the traditional linear interpolation method and nonlinear growth functions. The 6 stature growth parameters were measured: age at takeoff, stature at takeoff, velocity at takeoff, age at peak height velocity, stature at peak height velocity, and velocity at peak height velocity. Comparisons in the stature growth parameters and 15 cephalometric variables among the general population, Class III subjects, and non-Class III subjects were made with multivariate analysis. Patients with Class III prognathism did not have different growth parameters compared with Class II subjects or the general population. This study does not allow meaningful conclusions with regard to the relationship of mandibular size and stature growth pattern. The application of nonlinear growth curves vs the traditional linear interpolation method was also discussed. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  1. Differences in Fusarium Species in brown midrib Sorghum and in Air Populations in Production Fields.

    Science.gov (United States)

    Funnell-Harris, Deanna L; Scully, Erin D; Sattler, Scott E; French, Roy C; O'Neill, Patrick M; Pedersen, Jeffrey F

    2017-11-01

    Several Fusarium spp. cause sorghum (Sorghum bicolor) grain mold, resulting in deterioration and mycotoxin production in the field and during storage. Fungal isolates from the air (2005 to 2006) and from leaves and grain from wild-type and brown midrib (bmr)-6 and bmr12 plants (2002 to 2003) were collected from two locations. Compared with the wild type, bmr plants have reduced lignin content, altered cell wall composition, and different levels of phenolic intermediates. Multilocus maximum-likelihood analysis identified two Fusarium thapsinum operational taxonomic units (OTU). One was identified at greater frequency in grain and leaves of bmr and wild-type plants but was infrequently detected in air. Nine F. graminearum OTU were identified: one was detected at low levels in grain and leaves while the rest were only detected in air. Wright's F statistic (F ST ) indicated that Fusarium air populations differentiated between locations during crop anthesis but did not differ during vegetative growth, grain development, and maturity. F ST also indicated that Fusarium populations from wild-type grain were differentiated from those in bmr6 or bmr12 grain at one location but, at the second location, populations from wild-type and bmr6 grain were more similar. Thus, impairing monolignol biosynthesis substantially effected Fusarium populations but environment had a strong influence.

  2. Inter-population differences in otolith morphology are genetically encoded in the killifish Aphanius fasciatus (Cyprinodontiformes

    Directory of Open Access Journals (Sweden)

    Ali Annabi

    2013-06-01

    Full Text Available Inter-population differences in otolith shape, morphology and chemistry have been used effectively as indicators for stock assessment or for recognizing environmental adaptation in fishes. However, the precise parameters that affect otolith morphology remain incompletely understood. Here we provide the first direct support for the hypothesis that inter-population differences in otolith morphology are genetically encoded. The study is based on otolith morphology and two mitochondrial markers (D-loop, 16S rRNA of three natural populations of Aphanius fasciatus (Teleostei: Cyprinodontidae from Southeast Tunisia. Otolith and genetic data yielded congruent tree topologies. Divergence of populations likely results from isolation events in the course of the Pleistocene sea level drops. We propose that otolith morphology is a valuable tool for resolving genetic diversity also within other teleost species, which may be important for ecosystem management and conservation of genetic diversity. As reconstructions of ancient teleost fish faunas are often solely based on fossil otoliths, our discoveries may also lead to a new approach to research in palaeontology.

  3. Modeling of circular-grating surface-emitting lasers

    Science.gov (United States)

    Shams-Zadeh-Amiri, Ali M.

    Grating-coupled surface-emitting lasers became an area of growing interest due to their salient features. Emission from a broad area normal to the wafer surface, makes them very well suited in high power applications and two- dimensional laser arrays. These new possibilities have caused an interest in different geometries to fully develop their potential. Among them, circular-grating lasers have the additional advantage of producing a narrow beam with a circular cross section. This special feature makes them ideal for coupling to optical fibers. All existing theoretical models dealing with circular- grating lasers only consider first-order gratings, or second-order gratings, neglecting surface emission. In this thesis, the emphasis is to develop accurate models describing the laser performance by considering the radiation field. Toward this aim, and due to the importance of the radiation modes in surface-emitting structures, a theoretical study of these modes in multilayer planar structures has been done in a rigorous and systematic fashion. Problems like orthogonality of the radiation modes have been treated very accurately. We have considered the inner product of radiation modes using the distribution theory. Orthogonality of degenerate radiation modes is an important issue. We have examined its validity using the transfer matrix method. It has been shown that orthogonality of degenerate radiation modes in a very special case leads to the Brewster theorem. In addition, simple analytical formulas for the normalization of radiation modes have been derived. We have shown that radiation modes can be handled in a much easier way than has been thought before. A closed-form spectral dyadic Green's function formulation of multilayer planar structures has been developed. In this formulation, both rectangular and cylindrical structures can be treated within the same mathematical framework. The Hankel transform of some auxiliary functions defined on a circular aperture has

  4. Theoretical Investigation of Subwavelength Gratings and Vertical Cavity Lasers Employing Grating Structures

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza

    This thesis deals with theoretical investigations of a newly proposed grating structure, referred to as hybrid grating (HG) as well as vertical cavity lasers based on the grating reflectors. The HG consists of a near-subwavelength grating layer and an unpatterned high-refractive-index cap layer...... directions, which is analogous to electronic quantum wells in conduction or valence bands. Several interesting configurations of heterostructures have been investigated and their potential in fundamental physics study and applications are discussed. For numerical and theoretical studies, a three...... feasibility than the HCG-based ones. Furthermore, the concept of cavity dispersion in vertical cavities is introduced and its importance in the modal properties is numerically investigated. The dispersion curvature of a cavity mode is interpreted as the effective photon mass of the cavity mode. In a vertical...

  5. Reflectors and tuning elements for widely-tunable GaAs-based sampled grating DBR lasers

    Science.gov (United States)

    Brox, O.; Wenzel, H.; Della Case, P.; Tawfieq, M.; Sumpf, B.; Weyers, M.; Knigge, A.

    2018-02-01

    Widely-tunable lasers without moving parts are attractive light sources for sensors in industry and biomedicine. In contrast to InP based sampled grating (SG) distributed Bragg reflector (DBR) diode lasers which are commercially available, shorter wavelength GaAs SG-DBR lasers are still under development. One reason is the difficulty to integrate gratings with coupling coefficients that are high enough for functional grating bursts with lengths below 10 μm. Recently we have demonstrated > 20 nm wide quasi-continuous tuning with a GaAs based SG-DBR laser emitting around 975 nm. Wavelength selective reflectors are realized with SGs having different burst periods for the front and back mirrors. Thermal tuning elements (resistors) which are placed on top of the SG allow the control of the spectral positions of the SG reflector combs and hence to adjust the Vernier mode. In this work we characterize subsections of the developed SG-DBR laser to further improve its performance. We study the impact of two different vertical structures (with vertical far field FWHMs of 41° and 24°) and two grating orders on the coupling coefficient. Gratings with coupling coefficients above 350 cm-1 have been integrated into SG-DBR lasers. We also examine electronic tuning elements (a technique which is typically applied in InP based SG-DBR lasers and allows tuning within nanoseconds) and discuss the limitations in the GaAs material system

  6. Spectral analysis in overmodulated holographic reflection gratings recorded with BB640 ultrafine grain emulsion

    Science.gov (United States)

    Mas-Abellán, P.; Madrigal, R.; Fimia, A.

    2015-05-01

    Silver halide emulsions have been considered one of the most energetic sensitive materials for holographic applications. Nonlinear recording effects on holographic reflection gratings recorded on silver halide emulsions have been studied by different authors obtaining excellent experimental results. In this communication specifically we focused our investigation on the effects of refractive index modulation, trying to get high levels of overmodulation. We studied the influence of the grating thickness on the overmodulation and its effects on the transmission spectra for a wide exposure range by use of two different thickness ultrafine grain emulsion BB640, thin films (6 μm) and thick films (9 μm), exposed to single collimated beams using a red He-Ne laser (wavelength 632.8 nm) with Denisyuk configuration obtaining a spatial frequency of 4990 l/mm recorded on the emulsion. The experimental results show that high overmodulation levels of refractive index could offer some benefits such as high diffraction efficiency (reaching 90 %), increase of grating bandwidth (close to 80 nm), making lighter holograms, or diffraction spectra deformation, transforming the spectrum from sinusoidal to approximation of square shape. Based on these results, we demonstrate that holographic reflection gratings spectra recorded with overmodulation of refractive index is formed by the combination of several non-linear components due to very high overmodulation. This study is the first step to develop a new easy multiplexing technique based on the use of high index modulation reflection gratings.

  7. Adaptations to different habitats in sexual and asexual populations of parasitoid wasps: a meta-analysis

    OpenAIRE

    Amat, I; Kacelnik, A; van Alphen, JJM; Desouhant, E; Bernstein, C

    2017-01-01

    Background Coexistence of sexual and asexual populations remains a key question in evolutionary ecology. We address the question how an asexual and a sexual form of the parasitoid Venturia canescens can coexist in southern Europe. We test the hypothesis that both forms are adapted to different habitats within their area of distribution. Sexuals inhabit natural environments that are highly unpredictable, and where density of wasps and their hosts is low and patchily distributed. Asexuals in...

  8. Volatile Constituents of Different Plant Parts and Populations of Malabaila aurea Boiss. from Montenegro

    Directory of Open Access Journals (Sweden)

    Ivan Vučković

    2014-03-01

    Full Text Available The volatile constituents of different plant parts and populations of Malabaila aurea Boiss. from Montenegro were obtained by simultaneous distillation-extraction and analyzed by GC-FID and GC-MS. A total of 12 samples were examined and 45 compounds were identified. The volatile content of different M. aurea populations was very similar, while the volatile fractions obtained from different plant parts showed significant qualitative and quantitative differences. The most abundant compounds found in stems & leaves were apiole (51.0-56.3%, myristicin (16.3-25.4%, and falcarinol (4.1-10.7%. The roots showed the same major components, but with different relative abundances: 30.9-49.1% of apiole, 12.9-34.7% of falcarinol, and 9.9-31.1% of myristicin. The volatile constituents of fruits & flowers were remarkably different, containing up to 71.2-80.5% octyl butyrate, 11.4-18.0% octanol, and 2.7-6.8% octyl hexanoate. The results were discussed as possible indication of relatedness of Malabaila aurea and Pastinacasativa (parsnip .

  9. Smart photogalvanic running-grating interferometer

    DEFF Research Database (Denmark)

    Kukhtarev, N. V.; Kukhtareva, T.; Edwards, M. E.

    2005-01-01

    Photogalvanic effect produces actuation of periodic motion of macroscopic LiNbO3 crystal. This effect was applied to the development of an all-optical moving-grating interferometer usable for optical trapping and transport of algae chlorella microorganisms diluted in water with a concentration of...

  10. Computer simulation of multiple dynamic photorefractive gratings

    DEFF Research Database (Denmark)

    Buchhave, Preben

    1998-01-01

    The benefits of a direct visualization of space-charge grating buildup are described. The visualization is carried out by a simple repetitive computer program, which simulates the basic processes in the band-transport model and displays the result graphically or in the form of numerical data. The...

  11. Surface Fluctuation Scattering using Grating Heterodyne Spectroscopy

    DEFF Research Database (Denmark)

    Edwards, R. V.; Sirohi, R. S.; Mann, J. A.

    1982-01-01

    Heterodyne photon spectroscopy is used for the study of the viscoelastic properties of the liquid interface by studying light scattered from thermally generated surface fluctuations. A theory of a heterodyne apparatus based on a grating is presented, and the heterodyne condition is given in terms...

  12. Disorder effects in subwavelength grating metamaterial waveguides

    Czech Academy of Sciences Publication Activity Database

    Ortega-Moñux, A.; Čtyroký, Jiří; Cheben, P.; Schmid, J. H.; Wang, S.; Molina-Fernández, I.; Halíř, R.

    2017-01-01

    Roč. 25, č. 11 (2017), s. 12222-12236 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GA16-00329S Institutional support: RVO:67985882 Keywords : Subwavelength grating * Integrated photonics * Diffraction effects Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 3.307, year: 2016

  13. Hybrid grating reflectors: Origin of ultrabroad stopband

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gyeong Cheol; Taghizadeh, Alireza; Chung, Il-Sug, E-mail: ilch@fotonik.dtu.dk [DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2016-04-04

    Hybrid grating (HG) reflectors with a high-refractive-index cap layer added onto a high contrast grating (HCG) provide a high reflectance close to 100% over a broader wavelength range than HCGs. The combination of a cap layer and a grating layer brings a strong Fabry-Perot (FP) resonance as well as a weak guided mode (GM) resonance. Most of the reflected power results from the FP resonance, while the GM resonance plays a key role in achieving a reflectance close to 100% as well as broadening the stopband. An HG sample with 7 InGaAlAs quantum wells included in the cap layer has been fabricated by directly wafer-bonding a III-V cap layer onto a Si grating layer. Its reflection property has been characterized. This heterogeneously integrated HG reflector may allow for a hybrid III-V on Si laser to be thermally efficient, which has promising prospects for silicon photonics light sources and high-speed operation.

  14. Undergraduate Experiment with Fractal Diffraction Gratings

    Science.gov (United States)

    Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

  15. Haptoglobin gene subtypes in three Brazilian population groups of different ethnicities

    Directory of Open Access Journals (Sweden)

    Ana L. Miranda-Vilela

    2009-01-01

    Full Text Available Haptoglobin is a plasma hemoglobin-binding protein that limits iron loss during normal erythrocyte turnover and hemolysis, thereby preventing oxidative damage mediated by iron excess in the circulation. Haptoglobin polymorphism in humans, characterized by the Hp*1 and Hp*2 alleles, results in distinct phenotypes known as Hp1-1, Hp2-1 and Hp2-2, whose frequencies vary according to the ethnic origin of the population. The Hp*1 allele has two subtypes, Hp*1F and Hp*1S, that also vary in their frequencies among populations worldwide. In this work, we examined the distribution frequencies of haptoglobin subtypes in three Brazilian population groups of different ethnicities. The haptoglobin genotypes of Kayabi Amerindians (n = 56, Kalunga Afro-descendants (n = 70 and an urban population (n = 132 were determined by allele-specific PCR. The Hp*1F allele frequency was highest in Kalunga (29.3% and lowest in Kayabi (2.6%. The Hp*1F/Hp*1S allele frequency ratios were 0.6, 1.0 and 0.26 for the Kayabi, Kalunga and urban populations, respectively. This variation was attributable largely to the Hp*1F allele. However, despite the large variation in Hp*1F frequencies, results of FST (0.0291 indicated slight genetic differentiation among subpopulations of the general Brazilian population studied here. This is the first Brazilian report of variations in the Hp *1F and Hp*1S frequencies among non-Amerindian Brazilians.

  16. Differences Between Expressive Suppression and Cognitive Reappraisal Between Heart Disease and Generalal Population

    Directory of Open Access Journals (Sweden)

    Seyyed Mohammad Reza Mirlohi

    2017-09-01

    Full Text Available Aim: Heart disease and emotional disorders often co-occur, but effective role in dysregulation of heart disease that is often overlooked. Evidence suggests that people with heart disease are more problems in regulating their emotions. The study compared the re-evaluation of cognitive emotion regulation commonly used two strategies- and suppression- between heart disease and the general population. Methods: Sixty men (30 with heart complaints and 30 without the condition were selected by convenience sampling method and they responded to the Emotion Regulation Questionnaire (Gross and John and a demographic questionnaire responded. To analyze the results and descriptive statistics such as frequency tables and inferential statistics, independent T-test was used SPSS software was used. Results: The result shows that heart disease and general population re-evaluation strategies groups (P<0.01. This is not only different from the strategy reassessment, but in different repression, too. (P <0.001. Conclusion: The results showed that heart disease and general population used different strategies to regulate their emotions. The key to finding the heart disease group prefer repression to regulate their emotions.

  17. Parallel Gene Expression Differences between Low and High Latitude Populations of Drosophila melanogaster and D. simulans.

    Science.gov (United States)

    Zhao, Li; Wit, Janneke; Svetec, Nicolas; Begun, David J

    2015-05-01

    Gene expression variation within species is relatively common, however, the role of natural selection in the maintenance of this variation is poorly understood. Here we investigate low and high latitude populations of Drosophila melanogaster and its sister species, D. simulans, to determine whether the two species show similar patterns of population differentiation, consistent with a role for spatially varying selection in maintaining gene expression variation. We compared at two temperatures the whole male transcriptome of D. melanogaster and D. simulans sampled from Panama City (Panama) and Maine (USA). We observed a significant excess of genes exhibiting differential expression in both species, consistent with parallel adaptation to heterogeneous environments. Moreover, the majority of genes showing parallel expression differentiation showed the same direction of differential expression in the two species and the magnitudes of expression differences between high and low latitude populations were correlated across species, further bolstering the conclusion that parallelism for expression phenotypes results from spatially varying selection. However, the species also exhibited important differences in expression phenotypes. For example, the genomic extent of genotype × environment interaction was much more common in D. melanogaster. Highly differentiated SNPs between low and high latitudes were enriched in the 3' UTRs and CDS of the geographically differently expressed genes in both species, consistent with an important role for cis-acting variants in driving local adaptation for expression-related phenotypes.

  18. Using latent selection difference to model persistence in a declining population.

    Directory of Open Access Journals (Sweden)

    Mara E Erickson

    Full Text Available Population persistence is a direct measure of the viability of a population. Monitoring the distribution of declining populations or subpopulations over time can yield estimates of persistence, which we show can be modeled as a latent selection difference (LSD contrasting attributes of sites where populations have persisted versus those that have not. Predicted persistence can be modeled with predictor covariates to identify factors correlated with species persistence. We demonstrate how to model persistence based on changes in occupancy that can include adjustments for detection probability. Using a known historical distribution of the western grebe (Aechmophorus occidentalis, we adapted methods originally developed for occupancy modeling to evaluate how environmental covariates including emergent vegetation and human developments have affected western grebe persistence in Alberta. The relative probability of persistence was correlated with the extent of shoreline bulrush (Scirpus lacustris, which is important vegetation for nesting cover. We also documented that western grebe populations were less likely to persist on lakes in the boreal forest, primarily located on the northern boundary of the species' range. Factors influencing occupancy were different than those determining persistence by western grebes; persistence and occupancy were not correlated. Persistence was more likely on lakes with recreational development, reflecting reliance by grebes on the larger, fish-bearing waterbodies that also are attractive for lakeshore development. Unfortunately, the correlation with recreational development on Alberta's lakes puts grebes at risk for loss of brood-rearing habitats--primary threats to altricial birds--if steps are not taken to prevent disturbance to bulrush stands. Identifying factors related to the persistence of a species--especially one in decline--is a fundamental step in conservation management.

  19. Different Lactobacillus populations dominate in "Chorizo de León" manufacturing performed in different production plants.

    Science.gov (United States)

    Quijada, Narciso M; De Filippis, Francesca; Sanz, José Javier; García-Fernández, María Del Camino; Rodríguez-Lázaro, David; Ercolini, Danilo; Hernández, Marta

    2018-04-01

    "Chorizo de Léon" is a high-value Spanish dry fermented sausage traditionally manufactured without the use of starter cultures, owing to the activity of a house-specific autochthonous microbiota that naturally contaminates the meat from the environment, the equipment and the raw materials. Lactic acid bacteria (particularly Lactobacillus) and coagulase-negative cocci (mainly Staphylococcus) have been reported as the most important bacterial groups regarding the organoleptic and safety properties of the dry fermented sausages. In this study, samples from raw minced meat to final products were taken from five different producers and the microbial diversity was investigated by high-throughput sequencing of 16S rRNA gene amplicons. The diverse microbial composition observed during the first stages of "Chorizo de Léon" evolved during ripening to a microbiota mainly composed by Lactobacillus in the final product. Oligotyping performed on 16S rRNA gene sequences of Lactobacillus and Staphylococcus populations revealed sub-genus level diversity within the different manufacturers, likely responsible of the characteristic organoleptic properties of the products from different companies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Multiplexing of adjacent vortex modes with the forked grating coupler

    Science.gov (United States)

    Nadovich, Christopher T.; Kosciolek, Derek J.; Crouse, David T.; Jemison, William D.

    2017-08-01

    For vortex fiber multiplexing to reach practical commercial viability, simple silicon photonic interfaces with vortex fiber will be required. These interfaces must support multiplexing. Toward this goal, an efficient singlefed multimode Forked Grating Coupler (FGC) for coupling two different optical vortex OAM charges to or from the TE0 and TE1 rectangular waveguide modes has been developed. A simple, apodized device implemented with e-beam lithography and a conventional dual-etch processing on SOI wafer exhibits low crosstalk and reasonable mode match. Advanced designs using this concept are expected to further improve performance.

  1. Ethnic differences in social participation and social capital in Malmo, Sweden: a population-based study.

    OpenAIRE

    Lindström, Martin

    2005-01-01

    The aim of this study was to investigate ethnic differences in different aspects of social participation in Malmö, Sweden. The public health survey in Malmö 1994 is a cross-sectional study. A total of 5600 randomly chosen individuals aged 20–80 years were asked to complete a postal questionnaire. The participation rate was 71%. The population was divided into categories born in Sweden, Denmark/Norway, other Western countries, former Yugoslavia, Poland, Arabic speaking countries and all other ...

  2. Time trends in social differences in nutrition habits of a Lithuanian population: 1994-2010

    Directory of Open Access Journals (Sweden)

    Kriaucioniene Vilma

    2012-03-01

    Full Text Available Abstract Background During the post-communist transition period, political, economic, and social changes affected the lifestyles of the Lithuanian population, including their nutritional habits. However, people of lower socio-economic position were more vulnerable to these changes. The aim of the present study was to evaluate the trends in selected food habits of the Lithuanian adult population by their level of education and place of residence from 1994 to 2010. Methods The data were obtained from nine biannual cross-sectional postal surveys of Lithuanian health behaviours, beginning in 1994. Each survey used a randomly selected nationally representative sample of 3000 inhabitants aged 20-64 drawn from the population register. In total, 7358 men and 9796 women participated in these surveys. Questions about food consumption were included within all health behaviour questionnaires. Results During the transition period, use of vegetable oil in cooking and the frequency of consumption of fresh vegetables increased, use of butter on bread decreased, and the proportion of women drinking high-fat milk declined. Lithuanians with higher education reported more frequent use of vegetable oil in cooking as well as daily consumption of fresh vegetables than those with a lower level of education. Consumption of high-fat milk was inversely associated with educational background. In addition, the proportion of persons spreading butter on bread increased with higher education level. The greatest urban-rural difference was observed in high-fat milk consumption. The increase in the use of vegetable oil in cooking, and the reduction of spreading butter on bread was more evident among less educated and rural inhabitants. Meanwhile, a greater proportion of the rural population, compared to urban, reduced their use of butter on bread. Daily consumption of fresh vegetables increased most among highly educated Lithuanians. Conclusions The data from our study indicate

  3. Heritable differences in schooling behavior among threespine stickleback populations revealed by a novel assay.

    Directory of Open Access Journals (Sweden)

    Abigail R Wark

    2011-03-01

    Full Text Available Identifying the proximate and ultimate mechanisms of social behavior remains a major goal of behavioral biology. In particular, the complex social interactions mediating schooling behavior have long fascinated biologists, leading to theoretical and empirical investigations that have focused on schooling as a group-level phenomenon. However, methods to examine the behavior of individual fish within a school are needed in order to investigate the mechanisms that underlie both the performance and the evolution of schooling behavior. We have developed a technique to quantify the schooling behavior of an individual in standardized but easily manipulated social circumstances. Using our model school assay, we show that threespine sticklebacks (Gasterosteus aculeatus from alternative habitats differ in behavior when tested in identical social circumstances. Not only do marine sticklebacks show increased association with the model school relative to freshwater benthic sticklebacks, they also display a greater degree of parallel swimming with the models. Taken together, these data indicate that marine sticklebacks exhibit a stronger tendency to school than benthic sticklebacks. We demonstrate that these population-level differences in schooling tendency are heritable and are shared by individuals within a population even when they have experienced mixed-population housing conditions. Finally, we begin to explore the stimuli that elicit schooling behavior in these populations. Our data suggest that the difference in schooling tendency between marine and benthic sticklebacks is accompanied by differential preferences for social vs. non-social and moving vs. stationary shelter options. Our study thus provides novel insights into the evolution of schooling behavior, as well as a new experimental approach to investigate the genetic and neural mechanisms that underlie this complex social behavior.

  4. Fundamental limit of light trapping in grating structures

    KAUST Repository

    Yu, Zongfu

    2010-08-11

    We use a rigorous electromagnetic approach to analyze the fundamental limit of light-trapping enhancement in grating structures. This limit can exceed the bulk limit of 4n 2, but has significant angular dependency. We explicitly show that 2D gratings provide more enhancement than 1D gratings. We also show the effects of the grating profile’s symmetry on the absorption enhancement limit. Numerical simulations are applied to support the theory. Our findings provide general guidance for the design of grating structures for light-trapping solar cells.

  5. Development of a segmented grating mount system for FIREX-1

    International Nuclear Information System (INIS)

    Ezaki, Y; Tabata, M; Kihara, M; Horiuchi, Y; Endo, M; Jitsuno, T

    2008-01-01

    A mount system for segmented meter-sized gratings has been developed, which has a high precision grating support mechanism and drive mechanism to minimize both deformation of the optical surfaces and misalignments in setting a segmented grating for obtaining sufficient performance of the pulse compressor. From analytical calculations, deformation of the grating surface is less than 1/20 lambda RMS and the estimated drive resolution for piston and tilt drive of the segmented grating is 1/20 lambda, which are both compliant with the requirements for the rear-end subsystem of FIREX-1

  6. Metrology measurements for large-aperture VPH gratings

    Science.gov (United States)

    Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

    2013-09-01

    The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

  7. Sub-wavelength grating mode transformers in silicon slab waveguides.

    Science.gov (United States)

    Bock, Przemek J; Cheben, Pavel; Schmid, Jens H; Delâge, André; Xu, Dan-Xia; Janz, Siegfried; Hall, Trevor J

    2009-10-12

    We report on several new types of sub-wavelength grating (SWG) gradient index structures for efficient mode coupling in high index contrast slab waveguides. Using a SWG, an adiabatic transition is achieved at the interface between silicon-on-insulator waveguides of different geometries. The SWG transition region minimizes both fundamental mode mismatch loss and coupling to higher order modes. By creating the gradient effective index region in the direction of propagation, we demonstrate that efficient vertical mode transformation can be achieved between slab waveguides of different core thickness. The structures which we propose can be fabricated by a single etch step. Using 3D finite-difference time-domain simulations we study the loss, polarization dependence and the higher order mode excitation for two types (triangular and triangular-transverse) of SWG transition regions between silicon-on-insulator slab waveguides of different core thicknesses. We demonstrate two solutions to reduce the polarization dependent loss of these structures. Finally, we propose an implementation of SWG structures to reduce loss and higher order mode excitation between a slab waveguide and a phase array of an array waveguide grating (AWG). Compared to a conventional AWG, the loss is reduced from -1.4 dB to < -0.2 dB at the slab-array interface.

  8. Sex differences in correlates of intermediate phenotypes and prevalent cardiovascular disease in the general population

    Directory of Open Access Journals (Sweden)

    Renate B. Schnabel

    2015-04-01

    Full Text Available Background-There are marked sex differences in cardiovascular disease [CVD] manifestation. It is largely unknown how the distribution of CVD risk factors or intermediate phenotypes explain sex-specific differences.Methods and Results-In 5000 individuals of the population-based Gutenberg Health Study, mean age 55±11 years, 51% males, we examined sex-specific associations of classical CVD risk factors with intima-media thickness, ankle-brachial index, flow-mediated dilation, peripheral arterial tonometry, echocardiographic and electrocardiographic variables. Intermediate cardiovascular phenotypes were related to prevalent CVD (coronary artery disease, heart failure, stroke, myocardial infarction, lower extremity artery disease [LEAD] N=561.We observed differential distributions of CVD risk factors with a higher risk factor burden in men. Manifest coronary artery disease, stroke, myocardial infarction and LEAD were more frequent in men; the proportion of heart failure was higher in women. Intermediate phenotypes showed clear sex differences with more beneficial values in women. Fairly linear changes towards less beneficial values with age were observed in both sexes. In multivariable-adjusted regression analyses age, systolic blood pressure and body mass index were consistently associated with intermediate phenotypes in both sexes with different ranking according to random forests, maximum model R² 0.43. Risk factor-adjusted associations with prevalent CVD showed some differences by sex. No interactions by menopausal status were observed. Conclusions-In a population-based cohort we observed sex differences in risk factors and a broad range of intermediate phenotypes of noninvasive cardiovascular structure and function. Their relation to prevalent CVD differed markedly. Our results indicate the need of future investigations to understand sex differences in CVD manifestation.

  9. Evaluation of arch width variations among different skeletal patterns in South Indian population.

    Science.gov (United States)

    Prasad, Mandava; Kannampallil, Senny Thomas; Talapaneni, Ashok Kumar; George, Suja Ani; Shetty, Sharath Kumar

    2013-01-01

    Anterior cranial base can be taken as a reference line (SN) to determine the steepness of mandibular plane. Subjects with high mandibular plane angle tend to have a long face and one with low MP-SN angle has a shorter face. This study was done to investigate if dental arch widths correlated with vertical facial types and if there are any differences in arch widths between untreated male and female adults in South Indian population. Lateral cephalogram and dental casts were obtained from 180 untreated South Indian adults (90 males and 90 females) above 18 year old with no cross bite, minimal crowding and spacing. The angle between the anterior cranial base and the mandibular plane was measured on lateral cephalogram of each patient. Dental casts were used to obtain comprehensive dental measurements including maxillary and mandibular inter canine, inter premolar and inter molar widths, as well as amount of crowding or spacing. The results showed that male arch widths were significantly larger than those of females (P population. The results obtained in our study when compared with studies done in other population groups showed that there is difference in inter arch widths according to ethnicity and race. It was concluded that the dental arch width is associated with gender, race and vertical facial morphology. Thus using individualized arch wires according to each patient's pre treatment arch form and width is suggested during orthodontic treatment.

  10. Sex differences in risk factors for coronary heart disease: a study in a Brazilian population

    Directory of Open Access Journals (Sweden)

    Oliveira Helena CF

    2001-04-01

    Full Text Available Abstract Background In Brazil coronary heart disease (CHD constitutes the most important cause of death in both sexes in all the regions of the country and interestingly, the difference between the sexes in the CHD mortality rates is one of the smallest in the world because of high rates among women. Since a question has been raised about whether or how the incidence of several CHD risk factors differs between the sexes in Brazil the prevalence of various risk factors for CHD such as high blood cholesterol, diabetes mellitus, hypertension, obesity, sedentary lifestyle and cigarette smoking was compared between the sexes in a Brazilian population; also the relationships between blood cholesterol and the other risk factors were evaluated. Results The population presented high frequencies of all the risk factors evaluated. High blood cholesterol (CHOL and hypertension were more prevalent among women as compared to men. Hypertension, diabetes and smoking showed equal or higher prevalence in women in pre-menopausal ages as compared to men. Obesity and physical inactivity were equally prevalent in both sexes respectively in the postmenopausal age group and at all ages. CHOL was associated with BMI, sex, age, hypertension and physical inactivity. Conclusions In this population the high prevalence of the CHD risk factors indicated that there is an urgent need for its control; the higher or equal prevalences of several risk factors in women could in part explain the high rates of mortality from CHD in females as compared to males.

  11. Differences in problem-solving between canid populations: Do domestication and lifetime experience affect persistence?

    Science.gov (United States)

    Brubaker, Lauren; Dasgupta, Sandipan; Bhattacharjee, Debottam; Bhadra, Anindita; Udell, Monique A R

    2017-07-01

    Past research has suggested that a variety of factors, phylogenetic and ontogenetic, play a role in how canines behave during problem-solving tasks and the degree to which the presence of a human influences their problem-solving behaviour. While comparisons between socialized wolves and domestic dogs have commonly been used to tease apart these predictive factors, in many cases a single dog population, often pets, have been used for these comparisons. Less is understood about how different populations of dogs may behave when compared with wolves, or with each other, during an independent problem-solving task. This experiment compared the independent persistence of four populations of canines (two groups of pet domestic dogs, a group of free-ranging domestic dogs, and human-socialized wolves) on an independent problem-solving task in the presence of an on looking human. Results showed that wolves persisted the most at the task while free-ranging dogs persisted the least. Free-ranging dogs gazed at the human experimenter for the longest durations during the task. While further research is needed to understand why these differences exist, this study demonstrates that dogs, even those living outside human homes as scavengers, show comparatively low levels of persistence when confronted with a solvable task in the presence of a human as well as significantly greater duration of human-directed gaze when compared with wolves.

  12. Investigation on hepatitis C virus infection among different population group in eastern Guangdong province

    International Nuclear Information System (INIS)

    Hong Kai; Chen Linxing; Zhang Renhua; Yao Zhanchen; Xu Pinghui

    2004-01-01

    Objective: To investigate the HCV infection rate and the route of transmission among different population groups in Eastern Gruangdong province. Methods: Anti HCV was detected with EL ISA and HCV-RNA with FQ-PCR in selected population groups in Eastern Guangdong (total 8990 subjects). Results: The anti-HCV positive rates for general population, pregnant women, medical personnel, hepatitis B patients and patients on hemodialysis (HD) were: 0.89%(58/6468), 0.93%(17/1836), 2.93%(5/171), 11.5%(47/410) and 51.4%(54/105) respectively. Twelve of the 17 anti-HCV positive mothers were found to be HCV-RNA positive and two of the 12 infants were also HCV-RNA positive: a mother-to-infant transmission rate of 16.7%. In MD patients, anti HCV positive rate in those with history of transfusion and those without transfusion was 58% and 17% respectively, the difference being significant (P<0.01). Conclusion: Blood transmission was the main route for HCV infection transmission and mother-to-infant transmission as well as infections in medical personnel should be of great concern. (authors)

  13. Comparative performance of different stochastic methods to simulate drug exposure and variability in a population.

    Science.gov (United States)

    Tam, Vincent H; Kabbara, Samer

    2006-10-01

    Monte Carlo simulations (MCSs) are increasingly being used to predict the pharmacokinetic variability of antimicrobials in a population. However, various MCS approaches may differ in the accuracy of the predictions. We compared the performance of 3 different MCS approaches using a data set with known parameter values and dispersion. Ten concentration-time profiles were randomly generated and used to determine the best-fit parameter estimates. Three MCS methods were subsequently used to simulate the AUC(0-infinity) of the population, using the central tendency and dispersion of the following in the subject sample: 1) K and V; 2) clearance and V; 3) AUC(0-infinity). In each scenario, 10000 subject simulations were performed. Compared to true AUC(0-infinity) of the population, mean biases by various methods were 1) 58.4, 2) 380.7, and 3) 12.5 mg h L(-1), respectively. Our results suggest that the most realistic MCS approach appeared to be based on the variability of AUC(0-infinity) in the subject sample.

  14. Different requirements for GFRα2-signaling in three populations of cutaneous sensory neurons.

    Science.gov (United States)

    Kupari, Jussi; Airaksinen, Matti S

    2014-01-01

    Many primary sensory neurons in mouse dorsal root ganglia (DRG) express one or several GFRα's, the ligand-binding receptors of the GDNF family, and their common signaling receptor Ret. GFRα2, the principal receptor for neurturin, is expressed in most of the small nonpeptidergic DRG neurons, but also in some large DRG neurons that start to express Ret earlier. Previously, GFRα2 has been shown to be crucial for the soma size of small nonpeptidergic nociceptors and for their target innervation of glabrous epidermis. However, little is known about this receptor in other Ret-expressing DRG neuron populations. Here we have investigated two populations of Ret-positive low-threshold mechanoreceptors that innervate different types of hair follicles on mouse back skin: the small C-LTMRs and the large Aβ-LTMRs. Using GFRα2-KO mice and immunohistochemistry we found that, similar to the nonpeptidergic nociceptors, GFRα2 controls the cell size but not the survival of both C-LTMRs and Aβ-LTMRs. In contrast to the nonpeptidergic neurons, GFRα2 is not required for the target innervation of C-LTMRs and Aβ-LTMRs in the back skin. These results suggest that different factors drive target innervation in these three populations of neurons. In addition, the observation that the large Ret-positive DRG neurons lack GFRα2 immunoreactivity in mature animals suggests that these neurons switch their GFRα signaling pathways during postnatal development.

  15. Talbot Carpet Simulation for X-ray grating interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Youngju; Oh, Ohsung; Jeong, Hanseong; Kim, Jeongho; Lee, Seung Wook [Pusan National University, Busan (Korea, Republic of); Kim, Jongyul; Moon, Myungkook [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    In this study, Talbot carpet simulator has been developed to visualize the X-ray grating interference patterns in grating interferometer. We have simulated X-ray interference for a variety of simulations and demonstrated a few examples in this summary. Grating interferometer produces interference of X-ray called Talbot pattern with gratings manufactured in micro scale. Talbot pattern is self-images of phase grating which develops interference as beam splitter that is one of gratings consisted of interferometer. As the other gratings, there are source grating makes coherence and analyze grating is used to analyze interference onto detector. Talbot carpet has been studied as the beam behavior which is distinguished with common X-ray imaging systems. It is helpful to understand grating interferometer and possible to expect beams' oscillation for designing theoretically. We confirm pattern has periodicity produced by interference after pi and pi/2 phase grating and changes in the perpendicular direction to entrance face according to phase objects.

  16. Polarization-selective infrared bandpass filter based on a two-layer subwavelength metallic grating

    Science.gov (United States)

    Hohne, Andrew J.; Moon, Benjamin; Baumbauer, Carol L.; Gray, Tristan; Dilts, James; Shaw, Joseph A.; Dickensheets, David L.; Nakagawa, Wataru

    2017-08-01

    We present the design, fabrication, and characterization of a polarization-selective infrared bandpass filter based on a two-layer subwavelength metallic grating for use in polarimetric imaging. Gold nanowires were deposited via physical vapor deposition (PVD) onto a silicon surface relief grating that was patterned using electron beam lithography (EBL) and fabricated using standard silicon processing techniques. Optical characterization with a broad-spectrum tungsten halogen light source and a grating spectrometer showed normalized peak TM transmission of 53% with a full-width at half-maximum (FWHM) of 122 nm, which was consistent with rigorous coupled-wave analysis (RCWA) simulations. Simulation results suggested that device operation relied on suppression of the TM transmission caused by surface plasmon polariton (SPP) excitation at the gold-silicon interface and an increase in TM transmission caused by a Fabry-Perot (FP) resonance in the cavity between the gratings. TE rejection occurred at the initial air/gold interface. We also present simulation results of an improved design based on a two-dielectric grating where two different SPP resonances allowed us to improve the shape of the passband by suppressing the side lobes. This newer design resulted in improved side-band performance and increased peak TM transmission.

  17. Highly sensitive fiber grating chemical sensors: An effective alternative to atomic absorption spectroscopy

    Science.gov (United States)

    Laxmeshwar, Lata. S.; Jadhav, Mangesh S.; Akki, Jyoti. F.; Raikar, Prasad; Kumar, Jitendra; prakash, Om; Raikar, U. S.

    2017-06-01

    Accuracy in quantitative determination of trace elements like Zinc, present in drinking water in ppm level, is a big challenge and optical fiber gratings as chemical sensors may provide a promising solution to overcome the same. This paper presents design of two simple chemical sensors based on the principle of shift in characteristic wavelength of gratings with change in their effective refractive index, to measure the concentration of Zinc in drinking water using etched short period grating (FBG) and Long period grating (LPG) respectively. Three samples of drinking water from different places have been examined for presence of Zinc. Further, the results obtained by our sensors have also been verified with the results obtained by a standard method, Atomic absorption spectroscopy (AAS). The whole experiment has been performed by fixing the fibers in a horizontal position with the sensor regions at the center of the fibers, making it less prone to disturbance and breaking. The sensitivity of LPG sensor is about 205 times that of the FBG sensor. A few advantages of Fiber grating sensors, besides their regular features, over AAS have also been discussed, that make our sensors potential alternatives for existing techniques in determination of trace elements in drinking water.

  18. Sex disparities in acute myocardial infarction incidence: do ethnic minority groups differ from the majority population?

    Science.gov (United States)

    van Oeffelen, Aloysia A M; Vaartjes, Ilonca; Stronks, Karien; Bots, Michiel L; Agyemang, Charles

    2015-02-01

    The incidence of acute myocardial infarction (AMI) in men exceeds that in women. The extent of this sex disparity varies widely between countries. Variations may also exist between ethnic minority groups and the majority population, but scientific evidence is lacking. A nationwide register-based cohort study was conducted (n = 7,601,785) between 1997 and 2007. Cox Proportional Hazard Models were used to estimate sex disparities in AMI incidence within the Dutch majority population and within ethnic minority groups, stratified by age (30-54, 55-64, ≥65 years). AMI incidence was higher in men than in women in all groups under study. Compared with the majority population (hazard ratio (HR): 2.23; 95% confidence interval (95% CI): 2.21-2.25), sex disparities were similar among minorities originating from the immediate surrounding countries (Belgium, Germany), whereas they were greater in most other minority groups. Most pronounced results were found among minorities from Morocco (HR: 3.48; 95% CI: 2.48-4.88), South Asia (HR: 3.92; 95% CI: 2.45-6.26) and Turkey (HR: 3.98; 95% CI: 3.51-4.51). Sex disparity differences were predominantly evident in those below 55 years of age, and were mainly provoked by a higher AMI incidence in ethnic minority men compared with men belonging to the Dutch majority population. Sex disparities in AMI incidence clearly varied between ethnic minorities and the Dutch majority population. Health prevention strategies may first target at a reduction of AMI incidence in young ethnic minority men, especially those originating from Turkey and South Asia. Furthermore, an increase in AMI incidence in their female counterparts should be prevented. © The European Society of Cardiology 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  19. Differences in aggression, activity and boldness between native and introduced populations of an invasive crayfish

    Science.gov (United States)

    Pintor, L.M.; Sih, A.; Bauer, M.L.

    2008-01-01

    Aggressiveness, along with foraging voracity and boldness, are key behavioral mechanisms underlying the competitive displacement and invasion success of exotic species. However, do aggressiveness, voracity and boldness of the invader depend on the presence of an ecologically similar native competitor in the invaded community? We conducted four behavioral assays to compare aggression, foraging voracity, threat response and boldness to forage under predation risk of multiple populations of exotic signal crayfish Pacifastacus leniusculus across its native and invaded range with and without a native congener, the Shasta crayfish P. fortis. We predicted that signal crayfish from the invaded range and sympatric with a native congener (IRS) should be more aggressive to outcompete a close competitor than populations from the native range (NR) or invaded range and allopatric to a native congener (IRA). Furthermore, we predicted that IRS populations of signal crayfish should be more voracious, but less bold to forage under predation risk since native predators and prey likely possess appropriate behavioral responses to the invader. Contrary to our predictions, results indicated that IRA signal crayfish were more aggressive towards conspecifics and more voracious and active foragers, yet also bolder to forage under predation risk in comparison to NR and IRS populations, which did not differ in behavior. Higher aggression/voracity/ boldness was positively correlated with prey consumption rates, and hence potential impacts on prey. We suggest that the positive correlations between aggression/voracity/boldness are the result of an overall aggression syndrome. Results of stream surveys indicated that IRA streams have significantly lower prey biomass than in IRS streams, which may drive invading signal crayfish to be more aggressive/voracious/bold to acquire resources to establish a population. ?? 2008 The Authors.

  20. Population structure and virulence gene profiles of Streptococcus agalactiae collected from different hosts worldwide.

    Science.gov (United States)

    Morach, Marina; Stephan, Roger; Schmitt, Sarah; Ewers, Christa; Zschöck, Michael; Reyes-Velez, Julian; Gilli, Urs; Del Pilar Crespo-Ortiz, María; Crumlish, Margaret; Gunturu, Revathi; Daubenberger, Claudia A; Ip, Margaret; Regli, Walter; Johler, Sophia

    2018-03-01

    Streptococcus agalactiae is a leading cause of morbidity and mortality among neonates and causes severe infections in pregnant women and nonpregnant predisposed adults, in addition to various animal species worldwide. Still, information on the population structure of S. agalactiae and the geographical distribution of different clones is limited. Further data are urgently needed to identify particularly successful clones and obtain insights into possible routes of transmission within one host species and across species borders. We aimed to determine the population structure and virulence gene profiles of S. agalactiae strains from a diverse set of sources and geographical origins. To this end, 373 S. agalactiae isolates obtained from humans and animals from five different continents were typed by DNA microarray profiling. A total of 242 different S. agalactiae strains were identified and further analyzed. Particularly successful clonal lineages, hybridization patterns, and strains were identified that were spread across different continents and/or were present in more than one host species. In particular, several strains were detected in both humans and cattle, and several canine strains were also detected in samples from human, bovine, and porcine hosts. The findings of our study suggest that although S. agalactiae is well adapted to various hosts including humans, cattle, dogs, rodents, and fish, interspecies transmission is possible and occurs between humans and cows, dogs, and rabbits. The virulence and resistance gene profiles presented enable new insights into interspecies transmission and make a crucial contribution to the identification of suitable targets for therapeutic agents and vaccines.

  1. Environmental Challenges and Physiological Solutions: Comparative Energetic Daily Rhythms of Field Mice Populations from Different Ecosystems

    Science.gov (United States)

    Scantlebury, Michael; Haim, Abraham

    2012-01-01

    Daily and seasonal variations in physiological characteristics of mammals can be considered adaptations to temporal habitat variables. Across different ecosystems, physiological adjustments are expected to be sensitive to different environmental signals such as changes in photoperiod, temperature or water and food availability; the relative importance of a particular signal being dependent on the ecosystem in question. Energy intake, oxygen consumption (VO2) and body temperature (Tb) daily rhythms were compared between two populations of the broad-toothed field mouse Apodemus mystacinus, one from a Mediterranean and another from a sub-Alpine ecosystem. Mice were acclimated to short-day (SD) ‘winter’ and long-day (LD) ‘summer’ photoperiods under different levels of salinity simulating osmotic challenges. Mediterranean mice had higher VO2 values than sub-Alpine mice. In addition, mice exposed to short days had higher VO2 values when given water with a high salinity compared with mice exposed to long days. By comparison, across both populations, increasing salinity resulted in a decreased Tb in SD- but not in LD-mice. Thus, SD-mice may conserve energy by decreasing Tb during (‘winter’) conditions which are expected to be cool, whereas LD-mice might do the opposite and maintain a higher Tb during (‘summer’) conditions which are expected to be warm. LD-mice behaved to reduce energy expenditure, which might be considered a useful trait during ‘summer’ conditions. Overall, increasing salinity was a clear signal for Mediterranean-mice with resultant effects on VO2 and Tb daily rhythms but had less of an effect on sub-Alpine mice, which were more responsive to changes in photoperiod. Results provide an insight into how different populations respond physiologically to various environmental challenges. PMID:23251469

  2. Sex and Gender Related Health Status Differences in Ancient and Contemporary Skeletal Populations

    Directory of Open Access Journals (Sweden)

    Velissaria Vanna

    2007-11-01

    Full Text Available Human skeletal and dental remains are an invaluable source of information for interpreting the way of life of past people and also provide the only direct evidence of non-living populations’ health status. This research paper discusses the sex-related health differences observed in two skeletal populations from Greece, an ancient and a modern, by employing multiple health indicators, and aims at determining the biological and possible social factors that contribute to this variation. Particular emphasis is given to the importance of hypotheses-driven, population-based studies of human remains as the most effective means of reconstructing life in the past. The results showed that fracture ('ancient': females 0.08%, males 0.12%; 'modern': females 0.38%, males 0.19% and osteoarthritis ('ancient': females 0.7%, males: 3.0%; 'modern': females 4.4%, males 3.2% frequencies were higher for male individuals than females in the ancient population, which can be explained by greater engagement in strenuous and risky activity. Dental caries ('ancient': females 1.2%, males 1.8%; 'modern': females 23.6%, males 17.4% and ante-mortem tooth loss ('ancient': females 12.3%, males 7.7%; 'modern': females 69.5%, males 49.5% rates were higher for females than males (with the exception of the almost equal caries rates for the ancient population, most likely due to hormonal fluctuations, saliva content and flow, because female teeth erupt earlier and also perhaps as a result of differences in dietary habits. Periodontitis levels were more elevated in males ('ancient': females 9.6%, males 30.1%; 'modern': females 29.1%, males 38.3%, possibly due to poor oral hygiene practices and excessive masticatory loading. Dental enamel defects rates showed that in the ancient population, males had more chances of surviving childhood stress than females (females 19.5%, males 20.0%, whereas, in the modern population, the exact opposite was the case (females 6.1%, males 22.7%.

  3. Assessing Nutritional Parameters of Brown Bear Diets among Ecosystems Gives Insight into Differences among Populations.

    Science.gov (United States)

    López-Alfaro, Claudia; Coogan, Sean C P; Robbins, Charles T; Fortin, Jennifer K; Nielsen, Scott E

    2015-01-01

    Food habit studies are among the first steps used to understand wildlife-habitat relationships. However, these studies are in themselves insufficient to understand differences in population productivity and life histories, because they do not provide a direct measure of the energetic value or nutritional composition of the complete diet. Here, we developed a dynamic model integrating food habits and nutritional information to assess nutritional parameters of brown bear (Ursus arctos) diets among three interior ecosystems of North America. Specifically, we estimate the average amount of digestible energy and protein (per kilogram fresh diet) content in the diet and across the active season by bears living in western Alberta, the Flathead River (FR) drainage of southeast British Columbia, and the Greater Yellowstone Ecosystem (GYE). As well, we estimate the proportion of energy and protein in the diet contributed by different food items, thereby highlighting important food resources in each ecosystem. Bear diets in Alberta had the lowest levels of digestible protein and energy through all seasons, which might help explain the low reproductive rates of this population. The FR diet had protein levels similar to the recent male diet in the GYE during spring, but energy levels were lower during late summer and fall. Historic and recent diets in GYE had the most energy and protein, which is consistent with their larger body sizes and higher population productivity. However, a recent decrease in consumption of trout (Oncorhynchus clarki), whitebark pine nuts (Pinus albicaulis), and ungulates, particularly elk (Cervus elaphus), in GYE bears has decreased the energy and protein content of their diet. The patterns observed suggest that bear body size and population densities are influenced by seasonal availability of protein an energy, likely due in part to nutritional influences on mass gain and reproductive success.

  4. Assessing Nutritional Parameters of Brown Bear Diets among Ecosystems Gives Insight into Differences among Populations.

    Directory of Open Access Journals (Sweden)

    Claudia López-Alfaro

    Full Text Available Food habit studies are among the first steps used to understand wildlife-habitat relationships. However, these studies are in themselves insufficient to understand differences in population productivity and life histories, because they do not provide a direct measure of the energetic value or nutritional composition of the complete diet. Here, we developed a dynamic model integrating food habits and nutritional information to assess nutritional parameters of brown bear (Ursus arctos diets among three interior ecosystems of North America. Specifically, we estimate the average amount of digestible energy and protein (per kilogram fresh diet content in the diet and across the active season by bears living in western Alberta, the Flathead River (FR drainage of southeast British Columbia, and the Greater Yellowstone Ecosystem (GYE. As well, we estimate the proportion of energy and protein in the diet contributed by different food items, thereby highlighting important food resources in each ecosystem. Bear diets in Alberta had the lowest levels of digestible protein and energy through all seasons, which might help explain the low reproductive rates of this population. The FR diet had protein levels similar to the recent male diet in the GYE during spring, but energy levels were lower during late summer and fall. Historic and recent diets in GYE had the most energy and protein, which is consistent with their larger body sizes and higher population productivity. However, a recent decrease in consumption of trout (Oncorhynchus clarki, whitebark pine nuts (Pinus albicaulis, and ungulates, particularly elk (Cervus elaphus, in GYE bears has decreased the energy and protein content of their diet. The patterns observed suggest that bear body size and population densities are influenced by seasonal availability of protein an energy, likely due in part to nutritional influences on mass gain and reproductive success.

  5. Assessing Nutritional Parameters of Brown Bear Diets among Ecosystems Gives Insight into Differences among Populations

    Science.gov (United States)

    López-Alfaro, Claudia; Coogan, Sean C. P.; Robbins, Charles T.; Fortin, Jennifer K.; Nielsen, Scott E.

    2015-01-01

    Food habit studies are among the first steps used to understand wildlife-habitat relationships. However, these studies are in themselves insufficient to understand differences in population productivity and life histories, because they do not provide a direct measure of the energetic value or nutritional composition of the complete diet. Here, we developed a dynamic model integrating food habits and nutritional information to assess nutritional parameters of brown bear (Ursus arctos) diets among three interior ecosystems of North America. Specifically, we estimate the average amount of digestible energy and protein (per kilogram fresh diet) content in the diet and across the active season by bears living in western Alberta, the Flathead River (FR) drainage of southeast British Columbia, and the Greater Yellowstone Ecosystem (GYE). As well, we estimate the proportion of energy and protein in the diet contributed by different food items, thereby highlighting important food resources in each ecosystem. Bear diets in Alberta had the lowest levels of digestible protein and energy through all seasons, which might help explain the low reproductive rates of this population. The FR diet had protein levels similar to the recent male diet in the GYE during spring, but energy levels were lower during late summer and fall. Historic and recent diets in GYE had the most energy and protein, which is consistent with their larger body sizes and higher population productivity. However, a recent decrease in consumption of trout (Oncorhynchus clarki), whitebark pine nuts (Pinus albicaulis), and ungulates, particularly elk (Cervus elaphus), in GYE bears has decreased the energy and protein content of their diet. The patterns observed suggest that bear body size and population densities are influenced by seasonal availability of protein an energy, likely due in part to nutritional influences on mass gain and reproductive success. PMID:26083536

  6. Precise rotational alignment of x-ray transmission diffraction gratings

    International Nuclear Information System (INIS)

    Hill, S.L.

    1988-01-01

    Gold transmission diffraction gratings used for x-ray spectroscopy must sometimes be rotationally aligned to the axis of a diagnostic instrument to within sub-milliradian accuracy. We have fabricated transmission diffraction gratings with high line-densities (grating period of 200 and 300 nm) using uv holographic and x-ray lithography. Since the submicron features of the gratings are not optically visible, precision alignment is time consuming and difficult to verify in situ. We have developed a technique to write an optically visible alignment pattern onto these gratings using a scanning electron microscope (SEM). At high magnification (15000 X) several submicron lines of the grating are observable in the SEM, making it possible to write an alignment pattern parallel to the grating lines in an electron-beam-sensitive coating that overlays the grating. We create an alignment pattern by following a 1-cm-long grating line using the SEM's joystick-controlled translation stage. By following the same grating line we are assured the traveled direction of the SEM electron beam is parallel to the grating to better than 10 μradian. The electron-beam-exposed line-width can be large (5 to 15 μm wide) depending on the SEM magnification, and is therefore optically visible. The exposed pattern is eventually made a permanent feature of the grating by ion beam etching or gold electroplating. The pattern can be used to accurately align the grating to the axis of a diagnostic instrument. More importantly, the alignment of the grating can be quickly verified in situ

  7. Different populations of blacklegged tick nymphs exhibit differences in questing behavior that have implications for human lyme disease risk

    Science.gov (United States)

    Arsnoe, Isis M.; Hickling, Graham J.; Ginsberg, Howard S.; McElreath, Richard; Tsao, Jean I.

    2015-01-01

    Animal behavior can have profound effects on pathogen transmission and disease incidence. We studied the questing (= host-seeking) behavior of blacklegged tick (Ixodes scapularis) nymphs, which are the primary vectors of Lyme disease in the eastern United States. Lyme disease is common in northern but not in southern regions, and prior ecological studies have found that standard methods used to collect host-seeking nymphs in northern regions are unsuccessful in the south. This led us to hypothesize that there are behavior differences between northern and southern nymphs that alter how readily they are collected, and how likely they are to transmit the etiological agent of Lyme disease to humans. To examine this question, we compared the questing behavior of I. scapularis nymphs originating from one northern (Lyme disease endemic) and two southern (non-endemic) US regions at field sites in Wisconsin, Rhode Island, Tennessee, and Florida. Laboratory-raised uninfected nymphs were monitored in circular 0.2 m2 arenas containing wooden dowels (mimicking stems of understory vegetation) for 10 (2011) and 19 (2012) weeks. The probability of observing nymphs questing on these stems (2011), and on stems, on top of leaf litter, and on arena walls (2012) was much greater for northern than for southern origin ticks in both years and at all field sites (19.5 times greater in 2011; 3.6-11.6 times greater in 2012). Our findings suggest that southern origin I. scapularis nymphs rarely emerge from the leaf litter, and consequently are unlikely to contact passing humans. We propose that this difference in questing behavior accounts for observed geographic differences in the efficacy of the standard sampling techniques used to collect questing nymphs. These findings also support our hypothesis that very low Lyme disease incidence in southern states is, in part, a consequence of the type of host-seeking behavior exhibited by southern populations of the key Lyme disease vector.

  8. EPSTEIN–BARR VIRUS IN THE POPULATION OF TWO GEOGRAPHICALLY DIFFERENT REGIONS OF RUSSIA

    Directory of Open Access Journals (Sweden)

    N. B. Senyuta

    2017-01-01

    Full Text Available It is well known that the Epstein–Barr virus (EBV being widely spread in the human population is also the etiologic agent for a number of malignancies. A notable feature of tumors associated with EBV is their different incidence in various geographical regions, that, as suggested, related with mutational events in multiple loci of the EBV genome and its oncogene, the latent membrane protein 1 (LMP1, associated with the transforming potential of the virus. Given the multi-ethnic composition of Russian population and the diversity of geographical areas and conditions of their residence, it was relevant to examine the representatives of different geographical regions for the nature of their relationship with EBV. To solve this task the antibody response to locally circulating EBV strains, determined by indirect immunofluorescence, was studied in residents of the Central, North Caucasus and Far Eastern Federal Districts, represented by healthy individuals and patients with various head and neck tumors. The levels of antibody titers obtained were compared with the incidence rates of nasopharyngeal tumors (NPT in population of above Districts. In order to determine possible structural modifications in LMP1 gene of EBV strains persisting in selected geographic regions, samples of the gene have been amplified from a biological material collected by “nested” PCR and sequenced. The results obtained have shown that levels of antibody response to EBV among representatives of the regions included in the study vary significantly. It was found that in residents of the Dagestan and the Chechen Republics, the inhabitants of the North Caucasus Federal District, the correlation between enhanced humoral response to EBV and increased incidence of NPT was detected. Since among NPT the EBV-associated form of nasopharyngeal carcinoma (NPCEBV is dominated, the findings allow us to suggest that the population of these Republics have genetic

  9. Sex and age differences in physical performance: A comparison of Army basic training and operational populations.

    Science.gov (United States)

    Dada, Esther O; Anderson, Morgan K; Grier, Tyson; Alemany, Joseph A; Jones, Bruce H

    2017-11-01

    To determine the age- and sex-specific differences of physical fitness performances and Body Mass Index (BMI) in basic training and the operational Army. Cross-sectional Study. This secondary analysis utilizes retrospective surveys of U.S. Army Soldiers in Basic Combat Training (BCT) and operational units to compare physical performances between men and women as measured by the Army Physical Readiness Test (APFT). An ANOVA was used to compare mean differences in APFT results and BMI within sex-specific populations. A post hoc Tukey test identified specific mean differences. Adjusting for age, an ANCOVA was used to compare sex and occupation (infantry and non-infantry) differences in APFT results. Surveyed populations consisted of 2216 BCT Soldiers (1573 men and 643 women) and 5515 Operational Soldiers (4987 men and 528 women). Male and female operational Soldiers had greater muscular performance (79%-125% higher APFT push-ups, 66%-85% higher APFT sit-ups) and cardiorespiratory performance (22%-24% faster APFT 2-mile run times) than BCT Soldiers. Male BCT and operational Soldiers outperform their female counterparts on tests of muscular and cardiorespiratory endurance. Sex differences in physical performances attenuated among female Soldiers in operational units compared to BCT. Among male operational Soldiers, infantry Soldiers exhibited greater cardiorespiratory and muscular performance than non-infantry Soldiers. Higher BMI was associated with higher age groups, except for female BCT Soldiers. Gaps in cardiorespiratory and muscular performances between men and women should be addressed through targeted physical training programs that aim to minimize physiological differences. Published by Elsevier Ltd.

  10. Developmental dyslexia in Chinese and English populations: dissociating the effect of dyslexia from language differences

    Science.gov (United States)

    Hu, Wei; Lee, Hwee Ling; Zhang, Qiang; Liu, Tao; Geng, Li Bo; Seghier, Mohamed L.; Shakeshaft, Clare; Twomey, Tae; Green, David W.; Yang, Yi Ming

    2010-01-01

    Previous neuroimaging studies have suggested that developmental dyslexia has a different neural basis in Chinese and English populations because of known differences in the processing demands of the Chinese and English writing systems. Here, using functional magnetic resonance imaging, we provide the first direct statistically based investigation into how the effect of dyslexia on brain activation is influenced by the Chinese and English writing systems. Brain activation for semantic decisions on written words was compared in English dyslexics, Chinese dyslexics, English normal readers and Chinese normal readers, while controlling for all other experimental parameters. By investigating the effects of dyslexia and language in one study, we show common activation in Chinese and English dyslexics despite different activation in Chinese versus English normal readers. The effect of dyslexia in both languages was observed as less than normal activation in the left angular gyrus and in left middle frontal, posterior temporal and occipitotemporal regions. Differences in Chinese and English normal reading were observed as increased activation for Chinese relative to English in the left inferior frontal sulcus; and increased activation for English relative to Chinese in the left posterior superior temporal sulcus. These cultural differences were not observed in dyslexics who activated both left inferior frontal sulcus and left posterior superior temporal sulcus, consistent with the use of culturally independent strategies when reading is less efficient. By dissociating the effect of dyslexia from differences in Chinese and English normal reading, our results reconcile brain activation results with a substantial body of behavioural studies showing commonalities in the cognitive manifestation of dyslexia in Chinese and English populations. They also demonstrate the influence of cognitive ability and learning environment on a common neural system for reading. PMID:20488886

  11. 1-D grating based SPR biosensor for the detection of lung cancer biomarkers using Vroman effect

    Science.gov (United States)

    Teotia, Pradeep Kumar; Kaler, R. S.

    2018-01-01

    Grating based surface plasmon resonance waveguide biosensor have been reported for the detection of lung cancer biomarkers using Vroman effect. The proposed grating based multilayered biosensor is designed with high detection accuracy for Epidermal growth factor receptor (EGFR) and also analysed to show high detection accuracy with acceptable sensitivity for both cancer biomarkers. The introduction of periodic grating with multilayer metals generates a good resonance that make it possible for early detection of cancerous cells. Using finite difference time domain method, it is observed wavelength of biosensor get red-shifted on variations of the refractive index due to the presence of both the cancerous bio-markers. The reported detection accuracy and sensitivity of proposed biosensor is quite acceptable for both lung cancer biomarkers i.e. Carcinoembryonic antigen (CEA) and Epidermal growth factor receptor (EGFR) which further offer us label free early detection of lung cancer using these biomarkers.

  12. Modeling optical transmissivity of graphene grate in on-chip silicon photonic device

    Science.gov (United States)

    Amiri, Iraj S.; Ariannejad, M. M.; Jalil, M. A.; Ali, J.; Yupapin, P.

    2018-06-01

    A three-dimensional (3-D) finite-difference-time-domain (FDTD) analysis was used to simulate a silicon photonic waveguide. We have calculated power and transmission of the graphene used as single or multilayers to study the light transmission behavior. A new technique has been developed to define the straight silicon waveguide integrated with grate graphene layer. The waveguide has a variable grate spacing to be filled by the graphene layer. The number of graphene atomic layers varies between 100 and 1000 (or 380 nm and 3800 nm), the transmitted power obtained varies as ∼30% and ∼80%. The ∼99%, blocking of the light was occurred in 10,000 (or 38,000 nm) atomic layers of the graphene grate.

  13. Deposit Probe Measurements in Danish Grate and Pulverized Fuel Biomass Power Boilers

    DEFF Research Database (Denmark)

    Hansen, Stine Broholm; Jensen, Peter Arendt; Jappe Frandsen, Flemming

    2012-01-01

    . Corresponding samples of fuels, ash deposits and fly ash have provided information on the transformation of inorganics in the boiler. Generally, grate fired boilers provide a fly ash containing high contents of K, Cl and S compared to the fuel ash, while suspension fired boilers fly ash has a composition nearly...... similar to the fuel ash. Inner most biomass deposits are always salt-rich, while thicker deposit layers also contain some Si and Ca. Deposit probe formation rate measurements have been performed in different ways on several boilers. Grate and suspension fired boilers seems to cause similar deposit...... formation rates. Suspension fired boilers generate more fly ash, while grate boilers form a fly ash with a higher fraction of melt formation (and thereby a higher sticking probability) at similar temperatures. For suspension fired units it is observed that wood with a lower ash content than straw gives rise...

  14. Influence of Surface Geometry of Grating Substrate on Director in Nematic Liquid Crystal Cell

    International Nuclear Information System (INIS)

    Ye Wenjiang; Xing Hongyu; Yang Guochen; Zhang Zhidong; Sun Yubao; Chen Guoying; Xuan Li

    2011-01-01

    The director in nematic liquid crystal cell with a weak anchoring grating substrate and a strong anchoring planar substrate is relative to the coordinates x and z. The influence of the surface geometry of the grating substrate in the cell on the director profile is numerically simulated using the two-dimensional finite-difference iterative method under the condition of one elastic constant approximation and zero driven voltage. The deepness of groove and the cell gap affect the distribution of director. For the relatively shallow groove and the relatively thick cell gap, the director is only dependent on the coordinate z. For the relatively deep groove and the relatively thin cell gap, the director must be dependent on the two coordinates x and z because of the increased elastic strain energy induced by the grating surface. (condensed matter: structural, mechanical, and thermal properties)

  15. Optical superimposed vortex beams generated by integrated holographic plates with blazed grating

    Science.gov (United States)

    Zhang, Xue-Dong; Su, Ya-Hui; Ni, Jin-Cheng; Wang, Zhong-Yu; Wang, Yu-Long; Wang, Chao-Wei; Ren, Fei-Fei; Zhang, Zhen; Fan, Hua; Zhang, Wei-Jie; Li, Guo-Qiang; Hu, Yan-Lei; Li, Jia-Wen; Wu, Dong; Chu, Jia-Ru

    2017-08-01

    In this paper, we demonstrate that the superposition of two vortex beams with controlled topological charges can be realized by integrating two holographic plates with blazed grating. First, the holographic plate with blazed grating was designed and fabricated by laser direct writing for generating well-separated vortex beam. Then, the relationship between the periods of blazed grating and the discrete angles of vortex beams was systemically investigated. Finally, through setting the discrete angle and different revolving direction of the holographic plates, the composite fork-shaped field was realized by the superposition of two vortex beams in a particular position. The topological charges of composite fork-shaped field (l = 1, 0, 3, and 4) depend on the topological charges of compositional vortex beams, which are well agreed with the theoretical simulation. The method opens up a wide range of opportunities and possibilities for applying in optical communication, optical manipulations, and photonic integrated circuits.

  16. Bragg grating induced cladding mode coupling due to asymmetrical index modulation in depressed cladding fibers

    DEFF Research Database (Denmark)

    Berendt, Martin Ole; Grüne-Nielsen, Lars; Soccolich, C.F.

    1998-01-01

    to reduce this problem. None of these designs seems to give complete solutions. In particular, the otherwise promising depressed cladding design gives a pronounced coupling to one LP01 mode, this has been referred to as a Ghost grating. To find the modes of the fiber we have established a numerical mode......UV-written Bragg gratings find wide spread use as wavelength selective components. In reflection high extinction ratios are routinely obtained. However, coupling to cladding modes gives excess loss on the short wavelength side of the main reflection. Different fiber-designs have been proposed......-solver based on the staircase-approximation method. The Bragg grating causes coupling between the fundamental LP01 mode and higher order LP1p modes that satisfy phase-matching. The coupling strength is determined by the overlap integral of the LP01, the LP1p mode, and the UV-induced index perturbation. For LP0...

  17. Fabrication of locally micro-structured fiber Bragg gratings by fs-laser machining

    Science.gov (United States)

    Dutz, Franz J.; Stephan, Valentin; Marchi, Gabriele; Koch, Alexander W.; Roths, Johannes; Huber, Heinz P.

    2018-06-01

    Here, we describe a method for producing locally micro-structured fiber Bragg gratings (LMFGB) by fs-laser machining. This technique enables the precise and reproducible ablation of cladding material to create circumferential grooves inside the claddings of optical fibers. From initial ablation experiments we acquired optimized process parameters. The fabricated grooves were located in the middle of uniform type I fiber Bragg gratings. LMFBGs with four different groove widths of 48, 85, 135 and 205 μ { {m}} were produced. The grooves exhibited constant depths of about 30 μ {m} and steep sidewall angles. With the combination of micro-structures and fiber Bragg gratings, fiber optic sensor elements with enhanced functionalities can be achieved.

  18. Multi-resonance peaks fiber Bragg gratings based on largely-chirped structure

    Science.gov (United States)

    Chen, Chao; Zhang, Xuan-Yu; Wei, Wei-Hua; Chen, Yong-Yi; Qin, Li; Ning, Yong-Qiang; Yu, Yong-Sen

    2018-04-01

    A composite fiber Bragg grating (FBG) with multi-resonance peaks (MRPs) has been realized by using femtosecond (fs) laser point-by-point inscription in single-mode fiber. This device contains a segment of largely-chirped gratings with the ultrahigh chirp coefficients and a segment of uniform high-order gratings. The observed MRPs are distributed in an ultra-broadband wavelength range from 1200 nm to 1700 nm in the form of quasi-period or multi-peak-group. For the 8th-order MRPs-FBG, we studied the axial strain and high-temperature sensing characteristics of different resonance peaks experimentally. Moreover, we have demonstrated a multi-wavelength fiber lasers with three-wavelength stable output by using a 9th-order MRPs-FBG as the wavelength selector. This work is significant for the fabrication and functionalization of FBGs with complicated spectra characteristics.

  19. Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating.

    Science.gov (United States)

    Zhang, Yu; Lin, Bo; Tjin, Swee Chuan; Zhang, Han; Wang, Guanghui; Shum, Ping; Zhang, Xinliang

    2010-12-06

    A fiber Bragg grating written in a photosensitive microfiber using KrF excimer laser via a uniform phase mask is demonstrated. We have successfully fabricated two Bragg gratings in microfibers having different diameters. In the reflection spectrum of a microfiber Bragg grating (MFBG), we observed two reflection peaks,which agrees with our numerical simulation results. Compared with the fundamental mode reflection, the higher-order reflection mode is more sensitive to the refractive index (RI) variation of the surrounding fluid due to its larger evanescent field. The measured maximum sensitivity is ~102 nm/RIU (RI unit) at an RI value of 1.378 in an MFBG with a diameter of 6 μm.

  20. Living bacteria rheology: Population growth, aggregation patterns, and collective behavior under different shear flows

    Science.gov (United States)

    Patrício, P.; Almeida, P. L.; Portela, R.; Sobral, R. G.; Grilo, I. R.; Cidade, T.; Leal, C. R.

    2014-08-01

    The activity of growing living bacteria was investigated using real-time and in situ rheology—in stationary and oscillatory shear. Two different strains of the human pathogen Staphylococcus aureus—strain COL and its isogenic cell wall autolysis mutant, RUSAL9—were considered in this work. For low bacteria density, strain COL forms small clusters, while the mutant, presenting deficient cell separation, forms irregular larger aggregates. In the early stages of growth, when subjected to a stationary shear, the viscosity of the cultures of both strains increases with the population of cells. As the bacteria reach the exponential phase of growth, the viscosity of the cultures of the two strains follows different and rich behaviors, with no counterpart in the optical density or in the population's colony-forming units measurements. While the viscosity of strain COL culture keeps increasing during the exponential phase and returns close to its initial value for the late phase of growth, where the population stabilizes, the viscosity of the mutant strain culture decreases steeply, still in the exponential phase, remains constant for some time, and increases again, reaching a constant plateau at a maximum value for the late phase of growth. These complex viscoelastic behaviors, which were observed to be shear-stress-dependent, are a consequence of two coupled effects: the cell density continuous increase and its changing interacting properties. The viscous and elastic moduli of strain COL culture, obtained with oscillatory shear, exhibit power-law behaviors whose exponents are dependent on the bacteria growth stage. The viscous and elastic moduli of the mutant culture have complex behaviors, emerging from the different relaxation times that are associated with the large molecules of the medium and the self-organized structures of bacteria. Nevertheless, these behaviors reflect the bacteria growth stage.

  1. Differences in attitudes towards medication between population groups in the Durban Metropolitan Area of South Africa.

    Science.gov (United States)

    Suleman, Fatima; Ally, Shabnam; Bayat, Samirah; Essack, Razia; Moodley, Renalda; Mtembu, Thobekile; Ramalingham, Emily

    2009-08-01

    Personal factors, especially attitude, have been implicated in the utilization of health care services, and in access to medical treatment. There is little information on the attitudes of the general public in South Africa towards medications and whether attitudes differ across population groups or among the different users of the health care system. This study aimed to determine the general attitude of a local population to medications, self-care orientation and health professional contact, and whether differences existed between age groups, gender and race groups. METHODS We carried out a randomized, cross-sectional quantitative study via telephonic questionnaire survey (adapted from a previous study) of a sample of 1132 telephone numbers. The setting was the Durban Metropolitan Area, KwaZulu-Natal, South Africa. KEY FINDINGS A total of 500 (44.2%) people responded. The majority had a positive attitude towards medication. An increase in age resulted in increased medication use. Females were more likely than males to use medication and seek professional health care (P = 0.0406). Most of the respondents (86.0%) were self-care-orientated and displayed moderate medication knowledge (46.2%). Some 295 (59.0%) of the 500 respondents had visited a pharmacy within the last 6 months. Conclusions Health care professionals can adopt an informed approach to address the needs of the population with regard to medication, by targeting groups more likely to use medication (females and the older age group). In addition, gaps in medication knowledge were identified which could be used for health-promotion interventions by health care workers.

  2. Population-based differences in treatment outcome following anticancer drug therapies.

    Science.gov (United States)

    Ma, Brigette By; Hui, Edwin P; Mok, Tony Sk

    2010-01-01

    Population-based differences in toxicity and clinical outcome following treatment with anticancer drugs have an important effect on oncology practice and drug development. These differences arise from complex interactions between biological and environmental factors, which include genetic diversity affecting drug metabolism and the expression of drug targets, variations in tumour biology and host physiology, socioeconomic disparities, and regional preferences in treatment standards. Some well-known examples include the high prevalence of activating epidermal growth factor receptor (EGFR) mutations in pulmonary adenocarcinoma among northeast (China, Japan, Korea) and parts of southeast Asia (excluding India) non-smokers, which predict sensitivity to EGFR kinase inhibitors, and the sharp contrast between Japan and the west in the management and survival outcome of gastric cancer. This review is a critical overview of population-based differences in the four most prevalent cancers in the world: lung, breast, colorectal, and stomach cancer. Particular attention is given to the clinical relevance of such knowledge in terms of the individualisation of drug therapy and in the design of clinical trials. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  3. Health Differences between Roma and Non-Roma in the Slovak Dialyzed Population

    Directory of Open Access Journals (Sweden)

    Gabriel Kolvek

    2018-02-01

    Full Text Available Background: Roma health has not been studied systematically. Thus far, it has been shown that Roma compared to non-Roma have a significantly higher likelihood of getting end-stage renal disease and that their chances for survival on dialysis are lower. Evidence is lacking regarding morbidity between Roma and non-Roma. The aim was to compare the health status of dialyzed Roma and non-Roma using the Charlson comorbidity index (CCI. All Slovak dialysis centers for adults were asked to fill in a questionaire with demographic and clinical data, including comorbidity. Cross-sectional analysis of 2082 patients with an average age of 63.8 ± 13.8 years was performed. Comorbidity was expressed as the CCI, and ethnic differences were calculated. Linear regression was performed to adjust for differences in gender and age in both ethnic groups. Roma represented 13.0% of the whole dialyzed population (n = 270. Comorbidity expressed as CCI was significantly lower in the Roma population (p < 0.001. After adjusting for gender and age, ethnicity failed to be associated with the CCI in the linear regression analysis (p = 0.965, variance of the model—adjusted R2 38.6%. The health status of dialyzed Slovak Roma does not differ cross-sectionally when adjusted for age and gender from the health status of dialyzed non-Roma.

  4. Prevalence of Dental Caries among the Population of Gwalior (India) in Relation of Different Associated Factors

    Science.gov (United States)

    Khan, Abdul Arif; Jain, Sudhir K.; Shrivastav, Archana

    2008-01-01

    Objectives India is unique in entire world due to variety of dietary habits in population. Many people of India follow totally vegetarian life style through their entire life time due to some religious and cultural reasons. Present study tried to analyze the role of different factors in the occurrence of dental caries including dietary habit. Methods Persons suffering with dental caries were examined for the type of dental caries in relation to different factors. Dental examination was performed and patients were asked a questionnaire and the data was recorded and analyzed. Results Incidence of dental caries was higher in female. High number of dental caries patients was observed among vegetarian population. 21–30 year age group was found to be most infected with dental caries. Conclusions This study can be helpful to analyze respective role of different dietary factors including protein rich diet, age, gender etc. on the prevalence of dental caries, which can be helpful to counteract the potential increase in the cases of dental caries and to design and plan preventive strategies for the persons at greatest risk. PMID:19212515

  5. A study of distribution, sex differences and stability of lip print patterns in an Indian population.

    Science.gov (United States)

    Kapoor, Neeti; Badiye, Ashish

    2017-09-01

    Lip prints are very useful in forensic investigations. The objective of this study is to determine predominant lip print pattern found among a central Indian population, to evaluate whether any sex difference exists and to study the permanence of the pattern over a 6 month duration. This study included 200 healthy adult subjects comprising of 100 males and 100 females in the age group of 18-25 years. A convenient and easier method of data collection i.e., digital photography was used instead of the traditional lipstick methods. Lip prints were then divided into four quadrants and recognized as per Suzuki and Tsuchihashi's classification. Type I (30.63%) was found to be most predominant overall in the Marathi population. Type I (29.75%) and Type III (35.75%) were found most prevalent in males and females respectively. Applying the Chi-Square test, statistically significant differences ( p  < 0.05) were observed between male and female lip print patterns in each of the quadrants individually and all quadrants taken together. The lip print patterns remained stable over a period of six-months. Being stable and with significant sex differences, lip prints can be effectively used as an important tool in forensic investigations for individualization as well as identification of sex of the donor, thus, narrowing down the scope of investigation to almost half.

  6. Differences Between Patients that Made an Impulsive or Premeditated Suicide Attempt in a Mexican Population.

    Science.gov (United States)

    Reyes-Tovilla, Jorge E; Hernández Yánez, Homero Daniel; Peralta-Jiménez, Yesenia; Ramón-Frías, Teresa; Juárez-Rojop, Isela; Pool-García, Sherezada; Velázquez-Sánchez, Martha Patricia; López-Narvóez, Lilia; Fresán, Ana; Tovilla-Zárate, Carlos Alfonso

    2015-01-01

    We performed a study to identify differences between patients with impulsive suicide attempt and those with premeditated suicide attempt in a Mexican population. We studied 144 patients who recently attempted suicide. Impulsive and premeditated suicide attempts were evaluated with the Suicide Intent Scale. These data were divided according to the type of attempt. Subsequently, the characteristics between the two groups were compared. The rate of patients that made an impulsive attempt was 61.8% and only 9.7% of the patients carried out a premeditated suicide attempt. More years of schooling/education and less severity of the attempt were observed in patients that carried out an impulsive suicide attempt (p suicide attempt. Our findings demonstrate that there are clinical differences among the individuals who carried out an impulsive suicide attempt from those who premeditated an attempt in a Mexican population. As a result, when planning interventions and prevention efforts it may be helpful to consider these clinical differences and demographic characteristics. © 2015 The Author(s).

  7. Population differences in brain morphology and microstructure among Chinese, Malay, and Indian neonates.

    Science.gov (United States)

    Bai, Jordan; Abdul-Rahman, Muhammad Farid; Rifkin-Graboi, Anne; Chong, Yap-Seng; Kwek, Kenneth; Saw, Seang-Mei; Godfrey, Keith M; Gluckman, Peter D; Fortier, Marielle V; Meaney, Michael J; Qiu, Anqi

    2012-01-01

    We studied a sample of 75 Chinese, 73 Malay, and 29 Indian healthy neonates taking part in a cohort study to examine potential differences in neonatal brain morphology and white matter microstructure as a function of ethnicity using both structural T2-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). We first examined the differences in global size and morphology of the brain among the three groups. We then constructed the T2-weighted MRI and DTI atlases and employed voxel-based analysis to investigate ethnic differences in morphological shape of the brain from the T2-weighted MRI, and white matter microstructure measured by fractional anisotropy derived from DTI. Compared with Malay neonates, the brains of Indian neonates' tended to be more elongated in anterior and posterior axis relative to the superior-inferior axis of the brain even though the total brain volume was similar among the three groups. Although most anatomical regions of the brain were similar among Chinese, Malay, and Indian neonates, there were anatomical variations in the spinal-cerebellar and cortical-striatal-thalamic neural circuits among the three populations. The population-related brain regions highlighted in our study are key anatomical substrates associated with sensorimotor functions.

  8. Motivation and readiness for drug treatment: differences by modality and special populations.

    Science.gov (United States)

    Melnick, Gerald; Hawke, Josephine; De Leon, George

    2014-01-01

    The purpose of this research is to expand our knowledge of motivational factors among admissions to various substance abuse treatment modalities and among those entering special programs. Differences in motivation are reported in a convenience sample of more than 6,000 admissions to 38 programs. Results from multilevel analyses show (a) an ordered increase in motivation by settings from referral to outpatient, to methadone maintenance, and to the highest levels in residential programs and (b) significantly lower motivation among admissions to programs for special populations. Results are discussed in relation to the demand characteristics of treatment and non-recovery reasons for entering treatment.

  9. The “potato road” and biogeographic history of potato cyst nematode populations from different continents

    Directory of Open Access Journals (Sweden)

    Or Violeta

    2014-01-01

    Full Text Available The general opinion about the introduction of potato in Europe is the one regarding the direction from South America to Spain and subsequent distribution to other continents. Some historical data point out an alternative road. The potato spread from its place of origin to other continents in the light of parasite-host relationship, relying on nematode molecular data, is discussed in the present work. Biogeographic history of potato cyst nematode populations from different continents is in congruence with historical records. [Projekat Ministarstva nauke Republike Srbije, br. TR 31018 i br. III 46007

  10. Similar traits, different genes? Examining convergent evolution in related weedy rice populations.

    Science.gov (United States)

    Thurber, Carrie S; Jia, Melissa H; Jia, Yulin; Caicedo, Ana L

    2013-02-01

    Convergent phenotypic evolution may or may not be associated with convergent genotypic evolution. Agricultural weeds have repeatedly been selected for weed-adaptive traits such as rapid growth, increased seed dispersal and dormancy, thus providing an ideal system for the study of convergent evolution. Here, we identify QTL underlying weedy traits and compare their genetic architecture to assess the potential for convergent genetic evolution in two distinct populations of weedy rice. F(2) offspring from crosses between an indica cultivar and two individuals from genetically differentiated U.S. weedy rice populations were used to map QTL for four quantitative (heading date, seed shattering, plant height and growth rate) and two qualitative traits. We identified QTL on nine of the twelve rice chromosomes, yet most QTL locations do not overlap between the two populations. Shared QTL among weed groups were only seen for heading date, a trait for which weedy groups have diverged from their cultivated ancestors and from each other. Sharing of some QTL with wild rice also suggests a possible role in weed evolution for genes under selection during domestication. The lack of overlapping QTL for the remaining traits suggests that, despite a close evolutionary relationship, weedy rice groups have adapted to the same agricultural environment through different genetic mechanisms. © 2012 Blackwell Publishing Ltd.

  11. FUNGAL POPULATION, AFLATOXIN AND FREE FATTY ACID CONTENTS OF PEANUTS PACKED IN DIFFERENT BAG TYPES

    Directory of Open Access Journals (Sweden)

    SONIA S.P. BULAONG

    2002-01-01

    Full Text Available Shelled peanuts of Gajah var. with initial moisture content of 7% were stored at 11 kg/bag in four bag types namely: jute bag, polypropylene bag, jute bag doubled with thin polyethylene (PE, and jute bag doubled with thick PE. Storage was done for six months under warehouse conditions with monitoring of relative humidity and temperature. Samples taken at the be ginning of storage and every month thereafter were analyzed for moisture content, fungal population, aflatoxin and free fatty acid contents. Statistical analyses showed that moisture content, fungal population, and free fatty acid contents were signifi cantly higher in jute and polypropylene bags than in PE-dou,bled jute bags. No significant differences were obtained in aflatoxin contents among bag types but at the end of six months storage, toxin level in jute bag exceeded the 30 ppb limit. Polypropylene had second highest toxin level at 23 ppb. The PE-doubled bags ha d 17 and 19 ppb total aflatoxins for thin and thick films, respectively. The results indicated that the immediate packag ing of dried shelled peanuts at safe moisture level in plastic films with water vapor transmission rated of 1 g/m2/24 hr or lower is recommended. This p ackaging will delay critical increases in moisture content, fungal population, aflatoxin and free fatty acid contents of peanut kernels at ambient storage conditions.

  12. Characterization of the human DNA gut virome across populations with different subsistence strategies and geographical origin.

    Science.gov (United States)

    Rampelli, Simone; Turroni, Silvia; Schnorr, Stephanie L; Soverini, Matteo; Quercia, Sara; Barone, Monica; Castagnetti, Andrea; Biagi, Elena; Gallinella, Giorgio; Brigidi, Patrizia; Candela, Marco

    2017-11-01

    It is a matter of fact that the human gut microbiome also includes a non-bacterial fraction represented by eukaryotic cells and viruses. To further explore the gut microbiome variation in human populations, here we characterized the human DNA viral community from publicly available gut metagenome data sets from human populations with different geographical origin and lifestyle. In particular, such data sets encompass microbiome information from two western urban societies (USA and Italy), as well as two traditional hunter-gatherer communities (the Hadza from Tanzania and Matses from Peru) and one pre-agricultural tribe (Tunapuco from Peru). Our results allowed for the first taxonomic reconstruction of the complex viral metacommunities within the human gut. The core virome structure included herpesviruses, papillomaviruses, polyomaviruses, adenoviruses and anelloviruses. Using Random Forests and a co-occurrence analysis approach, we identified the viruses that distinguished populations according to their geographical origin and/or lifestyle. This paves the way for new research aimed at investigating the biological role of the gut virome in human physiology, and the importance of our viral counterpart in the microbiome-host co-evolutionary process. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  13. Phosphatase Activity of Microbial Populations in Different Milk Samples in Relation to Protein and Carbohydrate Content

    Directory of Open Access Journals (Sweden)

    Sosanka Protim SANDILYA

    2014-12-01

    Full Text Available Cattle milk is a rich source of protein, carbohydrate, vitamins, minerals and all other major and micro nutrients. At a moderate pH, milk is an excellent media for the growth of microbes and thus, intake of raw milk is precarious. In this study, attempt was made for a qualitative study of eight raw milk samples of different varieties of cow and goat milk, collected from Jorhat district of Assam, India, on the basis of nutritional value and microbial population. The highest microbial population was found in the milk collected from cross hybrid variety of cow, whereas microbial contamination was the least in Jersey cow milk. Samples of C1 (Jersey cow variety showed presence of the highest amount of protein and carbohydrate content as compared to the others. Almost all the milk samples showed positive acid and alkaline phosphatase activity. Maximum acid phosphatase activity was observed in cross hybrid cow milk, whereas local cow milk exhibited the highest alkaline phosphatase activity. Phosphatase activity did not show any co-relationship with microbial population of the milk samples. Similarly, the protein and carbohydrate content of the samples did not have any significant impact on both acid and alkaline phosphatase activity.

  14. Seroepidemiological Study of Epstein-Barr Virus in Different Population Groups in Croatia.

    Science.gov (United States)

    Beader, Nataša; Kolarić, Branko; Slačanac, Domagoj; Tabain, Irena; Vilibić-Čavlek, Tatjana

    2018-02-01

    The Epstein-Barr virus (EBV) is one of the most common viruses found in humans, causing lifelong infection in up to 95% of the world population. To analyze the seroprevalence of EBV infection in different population groups in Croatia. During a 2 year period (2015-2016), a total of 2022 consecutive serum samples collected from Croatian residents were tested for the presence of EBV-specific viral capsid antigen (VCA) immunoglobulin M (IgM) and IgG antibodies using an enzyme-linked immunoassay. IgM/IgG-positive samples were further tested for IgG avidity. The overall prevalence of EBV IgG antibodies was 91.4%. Females had significantly higher IgG seroprevalence than males (93.1% vs. 89.9%, P = 0.008). According to age, IgG seropositivity increased progressively from 59.6% in children age 40. All IgM positive participants > 40 years showed high IgG avidity. Logistic regression showed that age is associated with EBV IgG seropositivity. EBV is widespread in the Croatian population. Older age appears to be the main risk factor for EBV seropositivity.

  15. Continuous anneal method for characterizing the thermal stability of ultraviolet Bragg gratings

    DEFF Research Database (Denmark)

    Rathje, Jacob; Kristensen, Martin; Pedersen, Jens Engholm

    2000-01-01

    We present a new method for determining the long-term stability of UV-induced fiber Bragg gratings. We use a continuous temperature ramp method in which systematic variation of the ramp speed probes both the short- and long-term stability. Results are obtained both for gratings written in D2 loaded...... we resolve two separate energy distributions, suggesting that two different defects are involved. The experiments show that complicated decays originating from various energy distributions can be analyzed with this continuous isochronal anneal method. The results have both practical applications...

  16. Holographic Storage of Multiple Coherence Gratings in a Bose-Einstein Condensate

    International Nuclear Information System (INIS)

    Yoshikawa, Yutaka; Torii, Yoshio; Kuga, Takahiro; Nakayama, Kazuyuki

    2007-01-01

    We demonstrate superradiant conversion between a two-mode collective atomic state and a single-mode light field in an elongated cloud of Bose-condensed atoms. Two off-resonant write beams induce superradiant Raman scattering, producing two independent coherence gratings with different wave vectors in the cloud. By applying phase-matched read beams after a controllable delay, the gratings can be selectively converted into the light field also in a superradiant way. Because of the large optical density and the small velocity width of the condensate, a high conversion efficiency of >70% and a long storage time of >120 μs were achieved

  17. Bandwidth-narrowed Bragg gratings inscribed in double-cladding fiber by femtosecond laser.

    Science.gov (United States)

    Shi, Jiawei; Li, Yuhua; Liu, Shuhui; Wang, Haiyan; Liu, Ningliang; Lu, Peixiang

    2011-01-31

    Bragg gratings with the bandwidth(FWHM) narrowed up to 79 pm were inscribed in double-cladding fiber with femtosecond radiation and a phase mask followed by an annealing treatment. With the annealing temperature below a critical value, the bandwidth of Bragg gratings induced by Type I-IR and Type II-IR index change was narrowed without the reduction of reflectivity. The bandwidth narrowing is due to the profile transformation of the refractive index modulation caused by the annealing treatment. This mechanism was verified by comparing bandwidth narrowing processes of FBGs written with different power densities.

  18. Analytic theory of alternate multilayer gratings operating in single-order regime.

    Science.gov (United States)

    Yang, Xiaowei; Kozhevnikov, Igor V; Huang, Qiushi; Wang, Hongchang; Hand, Matthew; Sawhney, Kawal; Wang, Zhanshan

    2017-07-10

    Using the coupled wave approach (CWA), we introduce the analytical theory for alternate multilayer grating (AMG) operating in the single-order regime, in which only one diffraction order is excited. Differing from previous study analogizing AMG to crystals, we conclude that symmetrical structure, or equal thickness of the two multilayer materials, is not the optimal design for AMG and may result in significant reduction in diffraction efficiency. The peculiarities of AMG compared with other multilayer gratings are analyzed. An influence of multilayer structure materials on diffraction efficiency is considered. The validity conditions of analytical theory are also discussed.

  19. Comparing modelling techniques when designing VPH gratings for BigBOSS

    Science.gov (United States)

    Poppett, Claire; Edelstein, Jerry; Lampton, Michael; Jelinsky, Patrick; Arns, James

    2012-09-01

    BigBOSS is a Stage IV Dark Energy instrument based on the Baryon Acoustic Oscillations (BAO) and Red Shift Distortions (RSD) techniques using spectroscopic data of 20 million ELG and LRG galaxies at 0.5VPH) gratings have been identified as a key technology which will enable the efficiency requirement to be met, however it is important to be able to accurately predict their performance. In this paper we quantitatively compare different modelling techniques in order to assess the parameter space over which they are more capable of accurately predicting measured performance. Finally we present baseline parameters for grating designs that are most suitable for the BigBOSS instrument.

  20. Compound grating structures in photonic crystals for resonant excitation of azobenzene

    DEFF Research Database (Denmark)

    Jahns, Sabrina; Kallweit, Christine; Adam, Jost

    Photo-switchable molecules such as azobenzene are of high interest for “smart” surfaces. Such “smart” surfaces respond to external light excitation by changing their macroscopic properties. The absorbance of light on a single normal path through a layer of azobenzene immobilized on a surface......-difference time-domain (FDTD) calculations for determination of resonance positions and electric field strengths in compound grating structures. By superimposing two single-period gratings a photonic crystal can be designed supporting multiple guided mode resonances suitable to switch azobenzenes between...

  1. Body Dysmorphic Disorder: Gender differences and prevalence in a Pakistani medical student population

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    Vaqar Talha

    2008-04-01

    Full Text Available Abstract Background Body dysmorphic disorder (BDD is a psychiatric disorder characterized by a preoccupation with an imagined or slight defect which causes significant distress or impairment in functioning. Few studies have assessed gender differences in BDD in a non clinical population. Also no study assessed BDD in medical students. This study was designed to determine the point prevalence of BDD in Pakistani medical students and the gender differences in prevalence of BDD, body foci of concern and symptoms of BDD. Methods The medical students enrolled in a medical university in Karachi, Pakistan filled out a self-report questionnaire which assessed clinical features of BDD. BDD was diagnosed according to the DSM-IV criteria. Results Out of the 156 students, 57.1% were female. A total of 78.8% of the students reported dissatisfaction with some aspect of their appearance and 5.8% met the DSM-IV criteria for BDD. The male to female ratio for BDD was 1.7. Regarding gender differences in body foci of concern, the top three reported foci of concern in male students were head hair (34.3%, being fat (32.8%, skin (14.9% and nose(14.9%, whereas in females they were being fat (40.4%, skin (24.7% and teeth (18%. Females were significantly more concerned about being fat (p = 0.005. Male students were significantly more concerned about being thin (p = 0.01 and about head hair (p = 0.012. Conclusion BDD is fairly common in our medical student population, with a higher prevalence in males. Important gender differences in BDD symptomatology and reported body foci of concern were identified which reflected the influence of media on body image perception. The impact of cultural factors on the prevalence as well as gender differences in BDD symptomatology was also established.

  2. Palladium coated fibre Bragg grating based hydrogen sensor

    International Nuclear Information System (INIS)

    Kasinathan, M.; Sosamma, S.; Kishore, S.; Elumalai, V.; Krishnan, R.; Babu Rao, C.; Dash, Sitaram; Murali, N.; Jayakumar, T.

    2011-01-01

    Detection of steam generator leaks in fast nuclear reactors is carried out by monitoring hydrogen in argon cover-gas. Hydrogen released during sodium cleaning of fast reactor components is required to be monitored. Hydrogen sensors with good sensitivity, stability and response time are required for all the above applications. We report a new type of hydrogen sensor with a Fibre Bragg Grating (FBG) coated with palladium thin film which is used to detect the leak of hydrogen gas in the Steam Generator (SG) module of the Fast Breeder Reactor (FBR). If water leaks into sodium, it results in sodium-water reaction. In this reaction hydrogen and sodium hydroxide are formed. Due to the explosive risk of hydrogen system, hydrogen sensors are of great interest in this case. It is known that hydrogen forms an explosive mixture with air once its concentration exceeds beyond the explosion limit of four percent. The advantages of FBG based hydrogen sensor over the other hydrogen sensors are its inherent property of safety from sparking, immunity to ambient electromagnetic interference. The sensing mechanism in this device is based on mechanical strain that is induced in the palladium coating when it absorbs hydrogen. This process physically stretches the grating and causes the grating period and grating's refractive index, to change. The Bragg wavelength shift is directly proportional to the strain induced and can be directly related to the percentage of hydrogen exposure. The online monitoring of palladium thin film coating on FBG is carried out and recorded the wavelength change and strain induced on the FBG. A hydrogen sensor set up have been fabricated which consists of SS vessel of capacity 10 litres, provided with pressure gauge, Argon filling line with a valve, Hydrogen injection line with flange, a vent line with valve and Hydrogen sensor fixing point. The Palladium coated FBG based Hydrogen sensor is tested in this experimental facility in the exposure of hydrogen in

  3. Sex differences in jealousy: a population-based twin study in Sweden.

    Science.gov (United States)

    Walum, Hasse; Larsson, Henrik; Westberg, Lars; Lichtenstein, Paul; Magnusson, Patrik K E

    2013-10-01

    According to the theory of evolved sex differences in jealousy, the challenge for women to ensure paternal investment increased their jealousy response to emotional infidelity, whereas paternal uncertainty exerted selective pressures that shaped men to become more distressed by sexual infidelity. Several studies have investigated whether the effect of these sexually dimorphic selection pressures can be detected in contemporary human populations, with conflicting results. To date, no genetically informed studies of sex differences in jealousy have been conducted. We used data from the Screening Across the Lifespan of Twins Younger (SALTY) sample, containing information concerning self-rated jealousy from 3,197 complete twin pairs collected by the Swedish Twin Registry. Intra-class correlations and structural equation models were used to assess the genetic influence on jealousy and to investigate sex differences at genetic level. We saw a highly significant sex effect on the relationship between infidelity types, indicating that men, relative to women, reported greater jealousy in response to sexual infidelity than in response to emotional infidelity. The twin models revealed significant heritabilities for both sexual (32%) and emotional (26%) jealousy. The heritabilities were of a similar magnitude in both sexes, and no qualitative sex differences could be detected. We show for the first time that variance in jealousy is to some extent explained by genetic factors. Even though our results from the mean value analyses are in line with the theory of evolved sex differences in jealousy, we could not identify any sex differences on a genetic level.

  4. Electromagnetically induced grating with Rydberg atoms

    Science.gov (United States)

    Asghar, Sobia; Ziauddin, Qamar, Shahid; Qamar, Sajid

    2016-09-01

    We present a scheme to realize electromagnetically induced grating in an ensemble of strongly interacting Rydberg atoms, which act as superatoms due to the dipole blockade mechanism. The ensemble of three-level cold Rydberg-dressed (87Rb) atoms follows a cascade configuration where a strong standing-wave control field and a weak probe pulse are employed. The diffraction intensity is influenced by the strength of the probe intensity, the control field strength, and the van der Waals (vdW) interaction. It is noticed that relatively large first-order diffraction can be obtained for low-input intensity with a small vdW shift and a strong control field. The scheme can be considered as an amicable solution to realize the atomic grating at the microscopic level, which can provide background- and dark-current-free diffraction.

  5. Differences of knowledge, attitudes, and behaviors towards epilepsy between populations in municipal and nonmunicipal areas

    Directory of Open Access Journals (Sweden)

    Tiamkao S

    2013-10-01

    Full Text Available Somsak Tiamkao,1 Kittisak Sawanyawisuth,1,3 Karnchanasri Singhpoo,2 Sukanda Ariyanuchitkul,2 Ratchada Ngamroop4On behalf of the Integrated Epilepsy Research Group1Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; 2Community Medicine Service Section, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; 3The Research and Training Center for Enhancing Quality of Life of Working-Age People, Khon Kaen University, Khon Kaen, Thailand; 4Health Promoting Hospital Tumbon Banladchang, Nakhon Nayok Provincial Health Office, Nakhon Nayok, ThailandBackground: Information on the knowledge of, and attitudes and practices towards epilepsy of the general population in Thailand is still limited, particularly with respect to the differences between populations in municipal and nonmunicipal areas.Methods: A descriptive cross-sectional survey was conducted in a sample population of 1,000, with 500 participants each from municipal and nonmunicipal areas, in the Khon Kaen district.Results: The participants in the municipal area had higher incomes and higher education than did the participants in the nonmunicipal area. Both groups had low knowledge regarding epilepsy definition, causes, and treatment, but participants in the municipal area were more knowledgeable on the causes, types, and treatment of epilepsy. With respect to attitude, there were a significantly higher number of nonmunicipal participants than municipal participants who thought epilepsy was a disgusting disorder or that persons with epilepsy were sinful, had brain damage, and could not attend school. The municipal participants showed greater knowledge of correct practice than did nonmunicipal participants with regard to the following: not driving a car; avoiding acrobatic sports, fighting, or water sport; able to eat pork, not having to resign from work; not having to quit school; and able to have sexual relations.Conclusion: The

  6. Inter-Arm Difference in Brachial Blood Pressure in the General Population of Koreans.

    Science.gov (United States)

    Song, Bo Mi; Kim, Hyeon Chang; Shim, Jee-Seon; Lee, Myung Ha; Choi, Dong Phil

    2016-05-01

    We investigated the inter-arm difference in blood pressure of the general Korean population to identify associated factors. A total of 806 participants aged 30 to 64 years without history of major cardiovascular disease were analyzed in this cross-sectional study. They participated in the Cardiovascular and Metabolic Disease Etiology Research Center cohort study that began in 2013. Brachial blood pressure was measured simultaneously for both arms using an automated oscillometric device equipped with two cuffs in seated position. After five minutes of rest, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured three times. The average of the three measurements was used for analysis. Multivariate logistic regression models were used to identify factors associated with inter-arm differences in blood pressure. The mean inter-arm difference was 3.3 mmHg for SBP and 2.0 mmHg for DBP. Large inter-arm differences (≥10 mmHg) in SBP and in DBP were found in 3.7% and 0.9% of subjects, respectively. A large inter-arm difference in SBP was associated with mean SBP (p=0.002) and C-reactive protein (p=0.014) while a large inter-arm different in DBP was only associated with body mass index (p=0.015). Sex, age, and anti-hypertensive medication use were not associated with differences in inter-arm blood pressure. Large inter-arm difference in blood pressure is only present in a small portion of healthy Korean adults. Our findings suggest that high SBP, chronic inflammation, and obesity may be associated with larger difference in inter-arm blood pressure.

  7. Varied line-space gratings: past, present and future

    International Nuclear Information System (INIS)

    Hettrick, M.C.

    1985-08-01

    A classically ruled diffraction grating consists of grooves which are equidistant, straight and parallel. Conversely, the so-called ''holographic'' grating (formed by the interfering waves of coherent visible light), although severely constrained by the recording wavelength and recording geometry, has grooves which are typically neither equidistant, straight nor parallel. In contrast, a varied line-space (VLS) grating, in common nomenclature, is a design in which the groove positions are relatively unconstrained yet possess sufficient symmetry to permit mechanical ruling. Such seemingly exotic gratings are no longer only a theoretical curiosity, but have been ruled and used in a wide variety of applications. These include: (1) aberration-corrected normal incidence concave gratings for Seya-Namioka monochromators and optical de-multiplexers, (2) flat-field grazing incidence concave gratings for plasma diagnostics, (3) aberration-corrected grazing incidence plane gratings for space-borne spectrometers, (4) focusing grazing incidence plane grating for synchrotron radiation monochromators, and (5) wavefront generators for visible interferometry of optical surfaces (particularly aspheres). Future prospects of VLS gratings as dispersing elements, wavefront correctors and beamsplitters appear promising. The author discusses the history of VLS gratings, their present applications, and their potential in the future. 61 refs., 24 figs

  8. Phenotypic differences in teeth dimensions among Chennai population: An aid in sex determination

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    Sreedevi Dharman

    2015-01-01

    Full Text Available Objective: To investigate the presence of sexual dimorphism by studying the size of the teeth among males and females in Chennai population, which aids in sex determination. Materials and Methods: Incisocervical length, mesiodistal and buccolingual diameters were measured in teeth of 60 subjects (30 males, 30 females in the age group of 18-22 years from Chennai population. The differences in the mean values of parameters in males and females were calculated using independent t-test. Discriminant functional analysis was performed to determine the accuracy of sex. Results: Significant differences were found in mean incisocervical length which were found to be larger in males with P < 0.05 in 11, 12, 14, 17, 21, 22, 24, 26, 27, 31, 32, 33, 34, 41, 43, and 45 and with P < 0.001 in 13, 23, 32, 42, 43, and 44, with the exception of 37 and 47 which were larger in females. Mean mesiodistal diameter was larger in males with P < 0.05 in 11, 12, and 21 and with P < 0.001 in 13, 23, 33, and 43. Mean buccolingual diameter was larger in males with P < 0.05 in 12, 21, 31, 33, and 41 and with P < 0.001 in 11, 13, 23, and 43. Accuracy rate of predicting sex based on incisocervical length (17, 23, 47 and mesiodistal diameter (13, 33 was 78.3% and based on buccolingual diameter (13 was 76.7%. Conclusion: Males showed greater sexual dimorphism than females. Application of incisocervical, mesiodistal, and buccolingual dimensional variability among males and females in the Chennai population can aid in sex determination in forensic odontology, as the results showed moderate extent of dimorphism with an overall accuracy rate of predicting sex to be 78%.

  9. High prevalence of asymptomatic carriers of Tropheryma whipplei in different populations from the North of Spain.

    Science.gov (United States)

    García-Álvarez, Lara; Pérez-Matute, Patricia; Blanco, José Ramón; Ibarra, Valvanera; Oteo, José Antonio

    2016-01-01

    Tropheryma whipplei is the causative agent of Whipple disease. T. whipplei has also been detected in asymptomatic carriers with a very different prevalence. To date, in Spain, there are no data regarding the prevalence of T. whipplei in a healthy population or in HIV-positive patients, or in chronic fatigue syndrome (CFS). Therefore, the aim of this work was to assess the prevalence of T. whipplei in stools in those populations. Stools from 21 HIV-negative subjects, 65 HIV-infected, and 12 CFS patients were analysed using real time-PCR. HIV-negative and positive subjects were divided into two groups, depending on the presence/absence of metabolic syndrome (MS). Positive samples were sequenced. The prevalence of T. whipplei was 25.51% in 98 stool samples analysed. Prevalence in HIV-positive patients was significantly higher than in HIV-negative (33.8% vs. 9.09%, p=0.008). Prevalence in the control group with no associated diseases was 20%, whereas no positive samples were observed in HIV-negative patients with MS, or in those diagnosed with CFS. The prevalence observed in HIV-positive patients without MS was 30.35%, and with MS it was 55.5%. The number of positive samples varies depending on the primers used, although no statistically significant differences were observed. There is a high prevalence of asymptomatic carriers of T. whipplei among healthy and in HIV-infected people from Spain. The role of T. whipplei in HIV patients with MS is unclear, but the prevalence is higher than in other populations. Copyright © 2015 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  10. [BEHAVIOR OF HEMOGLOBIN CONCENTRATION, HEMATOCRIT AND OXYGEN SATURATION IN COLOMBIAN UNIVERSITY POPULATION AT DIFFERENT ALTITUDES].

    Science.gov (United States)

    Trompetero González, Andrea Catalina; Cristancho Mejía, Edgar; Benavides Pinzón, William Fernando; Serrato Roa, Mauricio; Landinez Macias, María Paula; Rojas, Joel

    2015-11-01

    the development of this research is base on the growing interest in understanding the adaptations to chronic hipoxia mainly in the range of intermediate altitudes (1 500-3 000 m.s.n.m) and the need to establish parameters of normality in the variables [Hb], Hct and SO2 for diagnostic and characterization of the population purposes. to analyze the behavior of the [Hb], Hct and SaO2 at different intermediate altitudes (970 m.s.n.m, 1 520 m.s.n.m, 1 728 m.s.n.m, 1 923 m.s.n.m, 2 180 m.s.n.m and 2 600 m.s.n.m) in order to contribute to the knowledge of the high altitude physiology and the clinical field to support the diagnosis of anemia. clinically healthy subjects with low levels of physical activity and food consumption report containing iron. Total of 264 participants of both genders between 18 and 30 years. The blood samples were collected from the antecubital vein and the earlobe and analyzed in a radiometer. A non-parametric statistical analysis was performed. with increasing of altitude, [Hb] and Hct values were increased while the SO2 decreased. Men showed higher values than women in [Hb] and Hct, related to lower values of SO2 than women. a threshold variable was not found, perhaps because of the small distance between the altitudes. The values reported were similar but not identical to other studies. This difference could be explained by genetic diversity among populations. this study allows for the first values of characterization of the study population. All altitudes were above the cutoff for the diagnosis of anemia ([Hb] 12 g/dl). Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  11. Response of fiber Bragg gratings to longitudinal ultrasonic waves.

    Science.gov (United States)

    Minardo, Aldo; Cusano, Andrea; Bernini, Romeo; Zeni, Luigi; Giordano, Michele

    2005-02-01

    In the last years, fiber optic sensors have been widely exploited for several sensing applications, including static and dynamic strain measurements up to acoustic detection. Among these, fiber Bragg grating sensors have been indicated as the ideal candidate for practical structural health monitoring in light of their unique advantages over conventional sensing devices. Although this class of sensors has been successfully tested for static and low-frequency measurements, the identification of sensor performances for high-frequency detection, including acoustic emission and ultrasonic investigations, is required. To this aim, the analysis of feasibilty on the use of fiber Bragg grating sensors as ultrasonic detectors has been carried out. In particular, the response of fiber Bragg gratings subjected to the longitudinal ultrasonic (US) field has been theoretically and numerically investigated. Ultrasonic field interaction has been modeled, taking into account the direct deformation of the grating pitch combined with changes in local refractive index due to the elasto-optic effect. Numerical results, obtained for both uniform and Gaussian-apodized fiber Bragg gratings, show that the grating spectrum is strongly influenced by the US field in terms of shape and central wavelength. In particular, a key parameter affecting the grating response is the ratio between the US wavelength and the grating length. Normal operation characterized by changes in wavelength of undistorted Bragg peak is possible only for US wavelengths longer than the grating length. For US wavelengths approaching the grating length, the wavelength change is accompanied by subpeaks formation and main peak amplitude modulation. This effect can be attributed to the nonuniformity of the US perturbation along the grating length. At very high US frequencies, the grating is not sensitive any longer. The results of this analysis provide useful tools for the design of grating-based ultrasound sensors for

  12. THE EFFECT OF DIFFERENT MEAT SHOP ON MEAT PHYSICAL CHARACTERISTICS AND BACTERIA POPULATION

    Directory of Open Access Journals (Sweden)

    S.H.C. Dewi

    2014-10-01

    Full Text Available An experiment was conducted to study the effect of different meat shops on meat physicalcharacteristics and bacteria population. Sixteen PO carcasses were used in the experiment which wasarranged in a completely randomized design with 4 treatments of different meat shops (traditionalmarket, meat shop, supermarket and slaughter house. Parameters measured were meat pH, waterholding capacity, cooking loss and bacterial total count. The result showed that the average of pH was5.25- 6.03; water holding capacity was 17.07-38.87%; cooking loss was 33.15-48.20 and bacterial totalcount was 1.48x106-10.75x106 CFU/g. It was concluded that bacterial total count in slaughter house andspecial market (meat shop and supermarket were less than those in traditional market.

  13. Individual-dose distribution for the population in different regions with radioactive contamination

    International Nuclear Information System (INIS)

    Keirim-Markus, I.B.; Kleshchenko, E.D.; Kushnereva, K.K.

    1995-01-01

    The reconstruction of individual doses as a result of the Chernobyl accident often relied on the method of EPR measurement from the enamel from extracted teeth. This method was used reliably, with individual confirmations of its indications being obtained. In determining the relatively small irradiation dose to the population, doubts arise because of the fact that the measured dose is often greater than the dose calculated by an indirect method---from external radiation fields at the location and the contents of radionuclides in foods. It is necessary, therefore, to perform an independent check of the results. In this paper, we describe one method for checking the reliability---comparing the measurements of the dose from several teeth in the same individual---in determining the dose from tooth enamel for the population of the Kamensk-Ural region of Sverdlovsk province. This group lived in the zone of passage for the eastern Ural radioactive wake in 1957. The error of the dose determination for different samples was different, since it depends on the mass and quality of the enamel obtained. The results presented show that the method of EPR dosimetry using the enamel of extracted teeth makes it possible to determine quite reliably the individual dose of external radiation from the background up to several Gy of the measurements. Our method compares measurements

  14. Haematological parameters in different african populations: an experience from united nations level 3 hospital

    International Nuclear Information System (INIS)

    Iftikhar, R.; Khan, N.U.; Iqbal, Z.; Anwar, M.I.

    2017-01-01

    To evaluate hematological parameters in African population to estimate normal reference intervals for these tests. Study Design: Cross sectional observational study. Place and Duration of Study: Department of Pathology, United Nations level 3 hospital, Nyala, Darfur from 1st Mar to 30th Dec 2014. Material and Methods: There were 396 healthy African male and female volunteers selected between 18-65 years of age, belonging to different countries. Fresh whole blood was used to measure haemoglobin (Hb) concentration, haematocrit (Hct), total red blood cell (TRBC) count, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), platelet count, total leucocyte count (TLC) and differential white blood cells count. Data were analysed using SPSS version 19. Results: Mean Hb of study group was 13.81 +- 1.99 g/dl. Mean TLC was 5.50 +- 1.96 x 103/ul. Mean lymphocyte count was 2.58 +- 0.95. Mean platelet count was 234 +- 92 x103 /ul. Mean values for Hb Concentration, TRBC, Hct Ratio, MCV, MCH and MCHC were all higher for African Males than Females; this difference was statistically significant (p<0.05). Conclusion: This multi-national African population based study confirms the variations in haematological parameters previously described in single nation African studies. The commonly observed variations in normal adults are low RBC indices, relative neutropenia and lymphocytosis. (author)

  15. Implications of storing urinary DNA from different populations for molecular analyses.

    Directory of Open Access Journals (Sweden)

    Angela Cannas

    2009-09-01

    Full Text Available Molecular diagnosis using urine is established for many sexually transmitted diseases and is increasingly used to diagnose tumours and other infectious diseases. Storage of urine prior to analysis, whether due to home collection or bio-banking, is increasingly advocated yet no best practice has emerged. Here, we examined the stability of DNA in stored urine in two populations over 28 days.Urine from 40 (20 male healthy volunteers from two populations, Italy and Zambia, was stored at four different temperatures (RT, 4 degrees C, -20 degrees C & -80 degrees C with and without EDTA preservative solution. Urines were extracted at days 0, 1, 3, 7 and 28 after storage. Human DNA content was measured using multi-copy (ALU J and single copy (TLR2 targets by quantitative real-time PCR. Zambian and Italian samples contained comparable DNA quantity at time zero. Generally, two trends were observed during storage; no degradation, or rapid degradation from days 0 to 7 followed by little further degradation to 28 days. The biphasic degradation was always observed in Zambia regardless of storage conditions, but only twice in Italy.Site-specific differences in urine composition significantly affect the stability of DNA during storage. Assessing the quality of stored urine for molecular analysis, by using the type of strategy described here, is paramount before these samples are used for molecular prognostic monitoring, genetic analyses and disease diagnosis.

  16. Gender differences in a resources-demands model in the general population.

    Science.gov (United States)

    Kocalevent, Rüya-Daniela; Klapp, Burghard F; Albani, Cornelia; Brähler, Elmar

    2014-09-01

    The population-based study examined postulated effects, derived from a resources-demands-model about gender-related aspects of self-efficacy, optimism, chronic stress, and exhaustion. Data acquisition was carried out by a market research institute with a multi-topic questionnaire in the general population (N = 2,552). Instruments administered were the Questionnaire for Self-Efficacy and Optimism, the Trier Inventory for Chronic Stress, and the Chalder-Fatigue-Scale. Households and target persons were selected randomly. The analyses focused on structural equation modeling. There were significant differences in structural relations among the resource paths. In particular, significant gender differences were found with respect to self-efficacy, and among the exhaustion paths, namely in the mental dimension of exhaustion. The observed measures of chronic stress were found to be operating equivalently for both genders. Results suggest that resources play an important role in the understanding of how chronic stress is preceded and may lead to exhaustion in both genders. Personal resources seem to be more expressed by men than by woman, for whom the relation of resources to health is of greater importance than for men.

  17. Family reintegration of children and adolescents in foster care in Brazilian municipalities with different population sizes.

    Science.gov (United States)

    Iannelli, Andrea M; Assis, Simone Gonçalves; Pinto, Liana Wernersbach; Pinto, Liana Wenersbach

    2015-01-01

    The scope of this article is to present and analyze data from Brazilian foster care services for children / adolescents from the perspective of family reintegration. It also seeks to support the implementation of public policies in order to provide effective reintegration in accordance with the differing local contexts. It uses data from 1,157 municipalities that have foster care services. The methodology takes into account the data collection of 2,624 Brazilian centers and 36,929 children and adolescents in care. The growing number of children/adolescents in care is in line with the increase in population size: 8.4 per small city; 60 per large city and 602.4 per metropolis. With respect to care residence in a different municipality there are varying indices: 12.4% in metropolises and 33.6% in small cities, revealing the absence of centers close to family units in the smaller communities. Regarding the activities promoted together with families, it was seen that there are still units that do not perform any activities, which runs contrary to Brazilian law. It is clear that policies for the child/adolescent in foster care centers need to consider the capacity of the municipality in accordance with population size to implement support actions for families to assist in family reintegration.

  18. Family reintegration of children and adolescents in foster care in Brazilian municipalities with different population sizes

    Directory of Open Access Journals (Sweden)

    Andrea M. Iannelli

    2015-01-01

    Full Text Available The scope of this article is to present and analyze data from Brazilian foster care services for children / adolescents from the perspective of family reintegration. It also seeks to support the implementation of public policies in order to provide effective reintegration in accordance with the differing local contexts. It uses data from 1,157 municipalities that have foster care services. The methodology takes into account the data collection of 2,624 Brazilian centers and 36,929 children and adolescents in care. The growing number of children/adolescents in care is in line with the increase in population size: 8.4 per small city; 60 per large city and 602.4 per metropolis. With respect to care residence in a different municipality there are varying indices: 12.4% in metropolises and 33.6% in small cities, revealing the absence of centers close to family units in the smaller communities. Regarding the activities promoted together with families, it was seen that there are still units that do not perform any activities, which runs contrary to Brazilian law. It is clear that policies for the child/adolescent in foster care centers need to consider the capacity of the municipality in accordance with population size to implement support actions for families to assist in family reintegration.

  19. Genetic similarities and differences between discoid and systemic lupus erythematosus patients within the Polish population

    Directory of Open Access Journals (Sweden)

    Katarzyna Skonieczna

    2017-05-01

    Full Text Available Introduction: Many studies have shown that some SNPs might be a risk factor for systemic lupus erythematosus (SLE, but little is known about potential susceptibility loci of the skin types of the disease. Discoid lupus erythematosus (DLE is the most common form of the cutaneous lupus erythematosus. Nevertheless, a genetic contribution to DLE is not fully recognized. Aim: We aimed to analyze three SNPs located in the STAT4 (rs7574865, ITGAM (rs1143679 and TNXB (rs1150754 genes in both DLE and SLE patients from Poland. Material and methods: SNPs were genotyped using real-time polymerase chain reaction (PCR. Statistical significance of the differences between patient and control groups in both allele and genotype frequencies were calculated using two tailed Fisher’s exact test. The correction for multiple testing by the Bonferroni adjustment and odds ratio were also calculated. Results : For the first time, we have shown that the polymorphisms located in the STAT4 (rs7574865, but not in the ITGAM (rs1143679 nor the TNXB (rs1150754 genes, might be associated with the development of DLE within the Polish population. The variation of the three investigated SNPs was found to be associated with SLE in our dataset. Conclusions : The results of our study suggest differences in the molecular background between DLE and SLE within the Polish population.

  20. Genetic similarities and differences between discoid and systemic lupus erythematosus patients within the Polish population.

    Science.gov (United States)

    Skonieczna, Katarzyna; Czajkowski, Rafał; Kaszewski, Sebastian; Gawrych, Mariusz; Jakubowska, Aneta; Grzybowski, Tomasz

    2017-06-01

    Many studies have shown that some SNPs might be a risk factor for systemic lupus erythematosus (SLE), but little is known about potential susceptibility loci of the skin types of the disease. Discoid lupus erythematosus (DLE) is the most common form of the cutaneous lupus erythematosus. Nevertheless, a genetic contribution to DLE is not fully recognized. We aimed to analyze three SNPs located in the STAT4 (rs7574865), ITGAM (rs1143679) and TNXB (rs1150754) genes in both DLE and SLE patients from Poland. SNPs were genotyped using real-time polymerase chain reaction (PCR). Statistical significance of the differences between patient and control groups in both allele and genotype frequencies were calculated using two tailed Fisher's exact test. The correction for multiple testing by the Bonferroni adjustment and odds ratio were also calculated. For the first time, we have shown that the polymorphisms located in the STAT4 (rs7574865), but not in the ITGAM (rs1143679) nor the TNXB (rs1150754) genes, might be associated with the development of DLE within the Polish population. The variation of the three investigated SNPs was found to be associated with SLE in our dataset. The results of our study suggest differences in the molecular background between DLE and SLE within the Polish population.

  1. Contextual interactions in grating plaid configurations are explained by natural image statistics and neural modeling

    Directory of Open Access Journals (Sweden)

    Udo Alexander Ernst

    2016-10-01

    Full Text Available Processing natural scenes requires the visual system to integrate local features into global object descriptions. To achieve coherent representations, the human brain uses statistical dependencies to guide weighting of local feature conjunctions. Pairwise interactions among feature detectors in early visual areas may form the early substrate of these local feature bindings. To investigate local interaction structures in visual cortex, we combined psychophysical experiments with computational modeling and natural scene analysis. We first measured contrast thresholds for 2x2 grating patch arrangements (plaids, which differed in spatial frequency composition (low, high or mixed, number of grating patch co-alignments (0, 1 or 2, and inter-patch distances (1° and 2° of visual angle. Contrast thresholds for the different configurations were compared to the prediction of probability summation (PS among detector families tuned to the four retinal positions. For 1° distance the thresholds for all configurations were larger than predicted by PS, indicating inhibitory interactions. For 2° distance, thresholds were significantly lower compared to PS when the plaids were homogeneous in spatial frequency and orientation, but not when spatial frequencies were mixed or there was at least one misalignment. Next, we constructed a neural population model with horizontal laminar structure, which reproduced the detection thresholds after adaptation of connection weights. Consistent with prior work, contextual interactions were medium-range inhibition and long-range, orientation-specific excitation. However, inclusion of orientation-specific, inhibitory interactions between populations with different spatial frequency preferences were crucial for explaining detection thresholds. Finally, for all plaid configurations we computed their likelihood of occurrence in natural images. The likelihoods turned out to be inversely related to the detection thresholds obtained

  2. Application of holographic sub-wavelength diffraction gratings for monitoring of kinetics of bioprocesses

    Energy Technology Data Exchange (ETDEWEB)

    Tamulevicius, Tomas, E-mail: tomas.tamulevicius@ktu.lt [Institute of Materials Science of Kaunas University of Technology, Savanoriu Ave. 271, LT-50131, Kaunas (Lithuania); Seperys, Rimas; Andrulevicius, Mindaugas; Kopustinskas, Vitoldas; Meskinis, Sarunas; Tamulevicius, Sigitas [Institute of Materials Science of Kaunas University of Technology, Savanoriu Ave. 271, LT-50131, Kaunas (Lithuania); Mikalayeva, Valeryia; Daugelavicius, Rimantas [Department of Biochemistry and Biotechnologies of Vytautas Magnus University, Vileikos St. 8, LT-44404 Kaunas (Lithuania)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Refractive index sensor based on DLC holographic sub-wavelength period grating. Black-Right-Pointing-Pointer Spectroscopic analysis of polarized white light reflected from the grating. Black-Right-Pointing-Pointer Control of critical wavelength shift and reflectivity changes. Black-Right-Pointing-Pointer Testing of model liquid analyte materials. Black-Right-Pointing-Pointer Evaluation of interaction between B. subtilis cells and lysozyme. - Abstract: In this work we present a refractive index (RI) sensor based on a sub-wavelength holographic diffraction grating. The sensor chip was fabricated by dry etching of the finely spaced (d = 428 nm) diffraction grating in SiO{sub x} doped diamond like carbon (DLC) film. It is shown that employing a fabricated sensor chip, and using the proposed method of analysis of data, one can inspect kinetics of processes in liquids occurring in the vicinity of the grating surface. The method is based on the spectral composition analysis of polarized polychromatic light reflected from the sub-wavelength diffraction grating. The RI measurement system was tested with different model liquid analytes including 25 wt.%, 50 wt.% sugar water solutions, 10 Degree-Sign C, 50 Degree-Sign C distilled water, also Gram-positive bacteria Bacillus subtilis interaction with ion-permeable channels forming antibiotic gramicidin D and a murolytic enzyme lysozyme. Analysis of the data set of specular reflection spectra enabled us to follow the kinetics of the RI changes in the analyte with millisecond resolution. Detectable changes in the effective RI were not worse than {Delta}n = 10{sup -4}.

  3. Finite gratings of many thin silver nanostrips: Optical resonances and role of periodicity

    Directory of Open Access Journals (Sweden)

    Olga V. Shapoval

    2013-04-01

    Full Text Available We study numerically the optical properties of the periodic in one dimension flat gratings made of multiple thin silver nanostrips suspended in free space. Unlike other publications, we consider the gratings that are finite however made of many strips that are well thinner than the wavelength. Our analysis is based on the combined use of two techniques earlier verified by us in the scattering by a single thin strip of conventional dielectric: the generalized (effective boundary conditions (GBCs imposed on the strip median lines and the Nystrom-type discretization of the associated singular and hyper-singular integral equations (IEs. The first point means that in the case of the metal strip thickness being only a small fraction of the free-space wavelength (typically 5 nm to 50 nm versus 300 nm to 1 μm we can neglect the internal field and consider only the field limit values. In its turn, this enables reduction of the integration contour in the associated IEs to the strip median lines. This brings significant simplification of the scattering analysis while preserving a reasonably adequate modeling. The second point guarantees fast convergence and controlled accuracy of computations that enables us to compute the gratings consisting of hundreds of thin strips, with total size in hundreds of wavelengths. Thanks to this, in the H-polarization case we demonstrate the build-up of sharp grating resonances (a.k.a. as collective or lattice resonances in the scattering and absorption cross-sections of sparse multi-strip gratings, in addition to better known localized surface-plasmon resonances on each strip. The grating modes, which are responsible for these resonances, have characteristic near-field patterns that are distinctively different from the plasmons as can be seen if the strip number gets larger. In the E-polarization case, no such resonances are detectable however the build-up of Rayleigh anomalies is observed, accompanied by the reduced

  4. Crack Growth Monitoring by Embedded Optical Fibre Bragg Grating Sensors: Fibre Reinforced Plastic Crack Growing Detection

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    This article presents a novel method to asses a crack growing/damage event in fibre reinforced plastic, or adhesive using Fibre Bragg Grating (FBG) sensors embedded in a host material. Different features of the crack mechanism that induce a change in the FBG response were identified. Double Canti...

  5. Crack growth monitoring in composite materials using embedded optical Fiber Bragg Grating sensor

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    In this paper a novel method to assess a crack growing/damage event in fiber reinforced plastic, or adhesive using Fiber Bragg Grating (FBG) sensors embedded in a host material is shown. Different features of the crack mechanism that induce a change in the FBG response were identified. Double...

  6. Grating-based X-ray tomography of 3D food structures

    DEFF Research Database (Denmark)

    Miklos, Rikke; Nielsen, Mikkel Schou; Einarsdottir, Hildur

    2016-01-01

    A novel grating based X-ray phase-contrast tomographic method has been used to study how partly substitution of meat proteins with two different types of soy proteins affect the structure of the formed protein gel in meat emulsions. The measurements were performed at the Swiss synchrotron radiati...

  7. Modelling non-uniform strain distributions in aerospace composites using fibre Bragg gratings

    NARCIS (Netherlands)

    Rajabzadehdizaji, Aydin; Groves, R.M.; Hendriks, R.C.; Heusdens, R.; Chung, Y.; Jin, W.; Lee, B.; Canning, J.; Nakamura, K.; Yuan, L.

    2017-01-01

    In this paper the behaviour of fibre Bragg grating (FBG) sensors under non-uniform strain distributions was analysed. Using the fundamental matrix approach, the length of the FBG sensor was discretised, with each segment undergoing different strain values. FBG sensors that are embedded inside

  8. Optical fiber grating based technologies and their applications: from nuclear fusion to medical

    NARCIS (Netherlands)

    Cheng, L.K.; Vliegenhart, W.A.; Habisreuther, T.

    2012-01-01

    In the last decades, Fiber Optic (FO) sensor has gained increasing acceptance. Among the different FO sensor types, Fiber Bragg Grating is most widely used due to its commercial availability and the unique multiplexing potential. The latter feature enables the development of large sensor array

  9. Population responses in V1 encode different figures by response amplitude.

    Science.gov (United States)

    Gilad, Ariel; Slovin, Hamutal

    2015-04-22

    The visual system simultaneously segregates between several objects presented in a visual scene. The neural code for encoding different objects or figures is not well understood. To study this question, we trained two monkeys to discriminate whether two elongated bars are either separate, thus generating two different figures, or connected, thus generating a single figure. Using voltage-sensitive dyes, we imaged at high spatial and temporal resolution V1 population responses evoked by the two bars, while keeping their local attributes similar among the two conditions. In the separate condition, unlike the connected condition, the population response to one bar is enhanced, whereas the response to the other is simultaneously suppressed. The response to the background remained unchanged between the two conditions. This divergent pattern developed ∼200 ms poststimulus onset and could discriminate well between the separate and connected single trials. The stimulus separation saliency and behavioral report were highly correlated with the differential response to the bars. In addition, the proximity and/or the specific location of the connectors seemed to have only a weak effect on this late activity pattern, further supporting the involvement of top-down influences. Additional neural codes were less informative about the separate and connected conditions, with much less consistency and discriminability compared with a response amplitude code. We suggest that V1 is involved in the encoding of each figure by different neuronal response amplitude, which can mediate their segregation and perception. Copyright © 2015 the authors 0270-6474/15/356335-15$15.00/0.

  10. Microbial quality of food available to populations of differing socioeconomic status.

    Science.gov (United States)

    Koro, Marlen E; Anandan, Shivanthi; Quinlan, Jennifer J

    2010-05-01

    Low SES has been shown to be linked to poorer-quality diets, decreased consumption of fresh produce, and an increased reliance on small retail stores. The objective of this research was to determine if there is a difference in the microbial quality and potential safety of food available to low-SES versus high-SES populations at the retail level. Aerobic plate count (APC); yeast and mold counts (Y & M); and total coliforms were determined in ready-to-eat (RTE) greens, pre-cut watermelon, broccoli, strawberries, cucumbers, milk, and orange juice and compared among products purchased in stores in low- versus those purchased in high-SES neighborhoods between June 2005 and September 2006. APC, fecal coliforms, and E. coli in ground beef and the presence of Salmonella and Campylobacter in chicken were also compared. Results showed higher microbial loads on produce from markets in low-SES areas. Significant differences observed included (1) APC and Y&M in RTE greens, (2) APC and Y&M in strawberries, and (3) YMCs in cucumbers. No difference was detected in the level of pathogens in raw meat and poultry; however, the APC in ground beef available in high-SES markets was significantly higher compared with that found in low-SES markets. The results presented here indicate that populations of low SES may be more likely to experience produce of poorer microbial quality, which may have an impact on both the appeal and potential safety of the produce. 2010 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  11. Sum-frequency generation echo and grating from interface

    International Nuclear Information System (INIS)

    Volkov, Victor

    2014-01-01

    The work addresses spectroscopy of fourth-order Sum Frequency Generation Echo and Grating responses as an experimental tool to study structure and dynamics at interfaces. First, it addresses experimental geometry to extract background-free fourth-order Echo and Grating responses. Further, the article provides the analytical expressions of the response functions for these nonlinearities. The derived expressions are used to model the χ (4) two-dimensional spectral responses of a hydrated methyl acetate, which resembles a hydrated carbonyl moiety at the polar outer side of a phospholipid membrane. Orientation, transition dipole moments, and Raman tensors are obtained from the results of classical and quantum calculations, respectively. The numerical studies for the nonlinear responses under different polarization schemes and timings suggest the possibility of securely factoring of spectral contributions of χ YYYZX and χ YYYZY macroscopic susceptibilities. As such, the nonlinearities provide an experimental perspective on orientation of a generic (low-symmetry) molecular system at interfaces. Besides, the spectral properties of the tensors may reflect correlations of the in-plane and out-of-plane field components specific to the interface. For the case of a phospholipid membrane, the experiment would address in-plane and out-of-plane anisotropy of hydrogen bonding and related dynamics

  12. Flexible organic solar cells including efficiency enhancing grating structures

    International Nuclear Information System (INIS)

    De Oliveira Hansen, Roana Melina; Liu Yinghui; Madsen, Morten; Rubahn, Horst-Günter

    2013-01-01

    In this work, a new method for the fabrication of organic solar cells containing functional light-trapping nanostructures on flexible substrates is presented. Polyimide is spin-coated on silicon support substrates, enabling standard micro- and nanotechnology fabrication techniques, such as photolithography and electron-beam lithography, besides the steps required for the bulk-heterojunction organic solar cell fabrication. After the production steps, the solar cells on polyimide are peeled off the silicon support substrates, resulting in flexible devices containing nanostructures for light absorption enhancement. Since the solar cells avoid using brittle electrodes, the performance of the flexible devices is not affected by the peeling process. We have investigated three different nanostructured grating designs and conclude that gratings with a 500 nm pitch distance have the highest light-trapping efficiency for the selected active layer material (P3HT:PCBM), resulting in an enhancement of about 34% on the solar cell efficiency. The presented method can be applied to a large variety of flexible nanostructured devices in future applications. (paper)

  13. Sum-frequency generation echo and grating from interface

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, Victor [Bereozovaya 2A, Konstantinovo, Moscow Region 140207 (Russian Federation)

    2014-10-14

    The work addresses spectroscopy of fourth-order Sum Frequency Generation Echo and Grating responses as an experimental tool to study structure and dynamics at interfaces. First, it addresses experimental geometry to extract background-free fourth-order Echo and Grating responses. Further, the article provides the analytical expressions of the response functions for these nonlinearities. The derived expressions are used to model the χ{sup (4)} two-dimensional spectral responses of a hydrated methyl acetate, which resembles a hydrated carbonyl moiety at the polar outer side of a phospholipid membrane. Orientation, transition dipole moments, and Raman tensors are obtained from the results of classical and quantum calculations, respectively. The numerical studies for the nonlinear responses under different polarization schemes and timings suggest the possibility of securely factoring of spectral contributions of χ{sub YYYZX} and χ{sub YYYZY} macroscopic susceptibilities. As such, the nonlinearities provide an experimental perspective on orientation of a generic (low-symmetry) molecular system at interfaces. Besides, the spectral properties of the tensors may reflect correlations of the in-plane and out-of-plane field components specific to the interface. For the case of a phospholipid membrane, the experiment would address in-plane and out-of-plane anisotropy of hydrogen bonding and related dynamics.

  14. Differences in the workforce experiences of women and men with arthritis disability: a population health perspective.

    Science.gov (United States)

    Kaptein, Simone A; Gignac, Monique A M; Badley, Elizabeth M

    2009-05-15

    To examine the employment status characteristics of people with arthritis disability, with a focus on gender differences and who remains in the workforce. Analyses were based on cross-sectional, self-reported data of the Canadian Participation and Activity Limitation Survey, administered in 2001-2002 (n = 28,908). Labor force status was categorized into employed, unemployed, and not in the labor force. Prevalence estimates were derived from descriptive analyses, and logistic regression determined the factors associated with being out of the labor force. Chi-square and sex-stratified analyses examined gender differences. An estimated 2.3% of the working-age population (ages 25-64 years) reported arthritis disability, and >50% were out of the labor force. Being female, single, older, and having less education and more severe pain and disability were associated with being out of the labor force. Employed women with arthritis disability required more accommodations in the workplace and reported more activity limitations than men. Perceived discrimination was more likely to be reported by employed men, and men reported more changes to their work than women. This study underscores the importance of looking more closely at differences in the employment experiences of women and men. Specifically, the results suggest that arthritis may marginalize women and men in different ways. Women may be more likely to leave employment, whereas men may be more likely to remain working and report negative workplace experiences.

  15. Refining clinical phenotypes by contrasting ethnically different populations with schizophrenia from Australia, India and Sarawak.

    Science.gov (United States)

    McLean, Duncan; John, Sujit; Barrett, Robert; McGrath, John; Loa, Peter; Thara, Rangaswamy; Mowry, Bryan

    2012-04-30

    We contrasted demographic and clinical characteristics in transethnic schizophrenia populations from Australia (n=821), India (n=520) and Sarawak, Malaysia (n=298) and proposed cultural explanations for identified site differences. From these we aimed to identify candidate variables free from significant cultural confounding that are hence suitable for inclusion in genetic analyses. We observed five phenomena: (1) more individuals were living alone in Australia than India or Sarawak; (2) drug use was lower in India than Australia or Sarawak; (3) duration of untreated psychosis (DUP) was longer in India than Australia or Sarawak; (4) the rate of schizoaffective disorder was lower in India than Australia or Sarawak; and (5) age at psychosis onset (AAO) was older in Sarawak than Australia or India. We suggest that site differences for living arrangements, drug use and DUP are culturally confounded. The schizoaffective site difference likely results from measurement bias. The AAO site difference, however, has no obvious cultural or measurement bias explanation. Therefore, this may be an ideal candidate for use in genetic studies, given that genetic variants affecting AAO have already been proposed. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  16. [Health risks in different living circumstances of mothers. Analyses based on a population study].

    Science.gov (United States)

    Sperlich, Stefanie

    2014-12-01

    The objective of this study was to determine the living circumstances ('Lebenslagen') in mothers which are associated with elevated health risks. Data were derived from a cross-sectional population based sample of German women (n = 3129) with underage children. By means of a two-step cluster analysis ten different maternal living circumstances were assessed which proved to be distinct with respect to indicators of socioeconomic position, employment status and family-related factors. Out of the ten living circumstances, one could be attributed to higher socioeconomic status (SES), while five were assigned to a middle SES and four to a lower SES. In line with previous findings, mothers with a high SES predominantly showed the best health while mothers with a low SES tended to be at higher health risk with respect to subjective health, mental health (anxiety and depression), obesity and smoking. However, there were important health differences between the different living circumstances within the middle and lower SES. In addition, varying health risks were found among different living circumstances of single mothers, pointing to the significance of family and job-related living conditions in establishing health risks. With this exploratory analysis strategy small-scale living conditions could be detected which were associated with specific health risks. This approach seemed particularly suitable to provide a more precise definition of target groups for health promotion. The findings encourage a more exrensive application of the concept of living conditions in medical sociology research as well as health monitoring.

  17. Aging and differentiation in yeast populations: elders with different properties and functions.

    Science.gov (United States)

    Palková, Zdena; Wilkinson, Derek; Váchová, Libuše

    2014-02-01

    Over the past decade, it has become evident that similarly to cells forming metazoan tissues, yeast cells have the ability to differentiate and form specialized cell types. Examples of yeast cellular differentiation have been identified both in yeast liquid cultures and within multicellular structures occupying solid surfaces. Most current knowledge on different cell types comes from studies of the spatiotemporal internal architecture of colonies developing on various media. With a few exceptions, yeast cell differentiation often concerns nongrowing, stationary-phase cells and leads to the formation of cell subpopulations differing in stress resistance, cell metabolism, respiration, ROS production, and others. These differences can affect longevity of particular subpopulations. In contrast to liquid cultures, where various cell types are dispersed within stationary-phase populations, cellular differentiation depends on the specific position of particular cells within multicellular colonies. Differentiated colonies, thus, resemble primitive multicellular organisms, in which the gradients of certain compounds and the position of cells within the structure affect cellular differentiation. In this review, we summarize and compare the properties of diverse types of differentiated chronologically aging yeast cells that have been identified in colonies growing on different media, as well as of those found in liquid cultures. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  18. Population kinetics studies in mouse jejunum exposed prenatally to gamma rays at different dose rates

    International Nuclear Information System (INIS)

    Godha, Meena; Nand Chahal, K.

    2001-01-01

    Pregnant Swiss albino mice of 18 days post conception were exposed to 0.80 Gy, 0.40 Gy and 0.20 Gy of gamma rays from a Cobalt-60 source at different dose rates (.0584 Gy/min and .00091 Gy/min). Post irradiation variations in the cell population of crypts and villus of jejunum were studied in the F 1 -generation at 1 day, 3 day and 1,2,4,6 and 12 weeks of post-partum age. In all the exposure groups at 1 day post-partum age, crypts show a decrease in total cells, mitotic figures and goblet cells on one hand and an increase in PNNC on the other hand in comparison to coeval controls. At this interval a decrease in the number of total cells as well as goblet cells/villus column was also noticeable. Dead cells which were prominently seen in crypts were totally absent in villi. The first signs of recovery can be observed on day 3 p.p. when total cell population, mitotic activity and goblet cells of crypt registered an increase while percentage of PNNC showed a fall. Percentage of total cell population and goblet cells/villus column also increased. The recovery continued up to 2 week of p.p. age. At p.p. age of 4 weeks a relapse of damage was observed when values for all the parameters of crypt and villi registered a fall except PNNC. This is followed by a second phase of recovery and by 6 and 12 weeks of post-partum age, normal value were obtained for all the parameters. (author)

  19. Epidemiological analysis of HTLV-1 and HTLV-2 infection among different population in Central China.

    Directory of Open Access Journals (Sweden)

    Yunyun Ma

    Full Text Available BACKGROUND: HTLV-1 and HTLV-2 are retroviruses linked etiologically to various human diseases, and both of them can be transmitted by vertical route, sexual intercourse, blood transfusion and intravenous drug use. Recently, some HTLV-infected cases have been reported and this virus is mainly present in the Southeast coastal areas in China, but has not been studied for the people in Central China. OBJECTIVES: To know the epidemiologic patterns among different population samples in Central China and further identify risk factor for HTLV-1 and HTLV-2 infection. METHODS: From January 2008 to December 2011, 5480 blood samples were screened for HTLV-1/2 antibodies by using enzyme immunoassay, followed by Western Blot. RESULTS: The prevalence of HTLV-1 and HTLV-2 was found with infection rates 0.13% and 0.05% among all population samples for HTLV-1 and HTLV-2, respectively. The highest percentages of infection, 0.39% and 0.20%, were found in the high risk group, while only 0.06% and 0.03% in the blood donor group. There was only one case of HTLV-1 infection (0.11% among patients with malignant hematological diseases. Of seven HTLV-1 positive cases, six were co-infected with HBV, two with HCV and one with HIV. Among three HTLV-2 positive individuals all were co-infected with HBV, one with HCV. CONCLUSIONS: HTLV-1 and HTLV-2 have been detected in the Central China at low prevalence, with the higher infection rate among high risk group. It was also found that co-infection of HTLV-1/2 with HIV and HBV occurred, presumably due to their similar transmission routes. HTLV-1/2 antibody screen among certain population would be important to prevent the spread of the viruses.

  20. Age-related differences in internalizing psychopathology amongst the Australian general population.

    Science.gov (United States)

    Sunderland, Matthew; Slade, Tim; Carragher, Natacha; Batterham, Philip; Buchan, Heather

    2013-11-01

    Two methodological criticisms have limited the reliability and validity of findings from previous studies that seek to examine change across the life span in levels of internalizing psychopathology using general population surveys. The first criticism involves the potential influence of cohort effects that confound true age-related changes whereas the second criticism involves the use of a single form of assessment to measure and compare levels of internalizing psychopathology. This study seeks to address these criticisms by modeling age-related change using multiple measures and multiple surveys. Data from 2 epidemiological surveys conducted 10 years apart in the Australian general population were combined and used for the current study. The latent construct of internalizing psychopathology was modeled using a combination of Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) depression and anxiety diagnoses as well as items from the Kessler Psychological Distress scale (K10; Kessler et al., 2002). Confirmatory factor analysis (CFA) indicated that a single internalizing dimension provided good model fit to the data. Multigroup CFA indicated that strict measurement invariance of the model can be assumed across survey administrations and age bands, justifying comparisons of mean differences in latent trait levels. Significant changes in mean levels of latent internalizing psychopathology were evident between respondents aged 30-39 years old in 1997 and respondents aged 40-49 years old in 2007, suggesting a minor but significant increase in psychopathology across middle age. By contrast, a minor but significant decrease in psychopathology was noted when transitioning from late middle age (50-59 years old) to old age (60-69 years old). The majority of individuals in the general population will experience constant levels of internalizing psychopathology as they age, suggesting that the construct is relatively

  1. Dietary exposure to non-dioxin-like PCBs of different population groups in Austria.

    Science.gov (United States)

    Mihats, Daniela; Moche, Wolfgang; Prean, Michael; Rauscher-Gabernig, Elke

    2015-05-01

    The dietary exposure to the sum of the six indicator PCBs (Σ6 PCBs; PCB 28, 52, 101, 138, 153, and 180) across different Austrian population groups was assessed in this study by combining data on occurrence from food of the Austrian market (n=157) analysed during 2006-2011 with national food consumption data. The most contaminated food group was meat, poultry, game and offal with average levels of ndl-PCBs of 5.20 ng g(-1) fat. In fish and fish products and eggs, mean concentrations of 3.89 ng g(-1) fresh weight (fw) and 4.00 ng g(-1) fat, respectively, were found. In milk and dairy products average concentrations ranged from 3.07 to 4.44 ng g(-1) fat. The mean dietary intake of Σ6 PCBs was estimated to be 3.37 ng kg(-1) bw d(-1) for children (6-15 years old), 3.19 ng kg(-1) bw d(-1) for women (19-65 years) and 2.64 ng kg(-1) bw d(-1) for men (19-65 years). In all three population groups, milk and dairy products was the major contributing food group to the total dietary intake (50-55%) followed by fish and fish products (23-27%). The exposure of all Austrian population groups is well below the tolerable daily intake (TDI) of 10 ng kg(-1) bw d(-1) proposed by WHO, accounting for 34% in children, 32% in women and 26% in men. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Assessment of current exposure levels in different population groups of the Kola Peninsula

    International Nuclear Information System (INIS)

    Travnikova, I.G.; Shutov, V.N.; Ya Bruk, G.; Balonov, M.I.; Skuterud, L.; Strand, P.; Pogorely, Ju.A.; Burkova, T.F.

    2002-01-01

    Activity concentrations of 137 Cs and 90 Sr in samples of vegetation and natural food products collected in the Kola Peninsula in 1998 and 1999 indicate a very slow decrease in contamination levels during the last decade, mainly due to the physical decay of the radionuclides. The activity concentrations of 137 Cs in reindeer meat decreased with a half-life of about 9 years. 137 Cs in lichen, moss and fungi is significantly higher than in natural vegetation (grasses) and agricultural plants (potatoes). The activity concentrations of 137 Cs in reindeer meat were two orders of magnitude higher than those in locally produced beef and pork. Consumption of reindeer meat, fish, mushrooms and berries constituted the main contribution to the internal dose from 137 Cs and 90 Sr for reindeer-breeders in the Lovozero area. The estimated committed doses due to 137 Cs intake in this group were about 10 μSv per month in summer 1998 and 15 μSv per month in winter, 1999. There was good agreement between internal dose estimates based on intake assessment and whole body measurements. The population of Umba settlement, which is not involved in reindeer breeding, received individual committed doses due to 137 Cs intake of about 0.5 μSv per month, about a factor of 20 less than the reindeer-breeders in Lovozero. In this case, the main contribution to the internal dose of the general population came from consumption the of 137 Cs in mushrooms and forest berries. The contribution of 90 Sr to the internal dose varied from 1% to 5% in the different population groups studied

  3. An X-ray grazing incidence phase multilayer grating

    CERN Document Server

    Chernov, V A; Mytnichenko, S V

    2001-01-01

    An X-ray grazing incidence phase multilayer grating, representing a thin grating placed on a multilayer mirror, is proposed. A high efficiency of grating diffraction can be obtained by the possibility of changing the phase shift of the wave diffracted from the multilayer under the Bragg and total external reflection conditions. A grazing incidence phase multilayer grating consisting of Pt grating stripes on a Ni/C multilayer and optimized for the hard X-ray range was fabricated. Its diffraction properties were studied at photon energies of 7 and 8 keV. The obtained maximum value of the diffraction efficiency of the +1 grating order was 9% at 7 keV and 6.5% at 8 keV. The data obtained are in a rather good accordance with the theory.

  4. Towards freeform curved blazed gratings using diamond machining

    Science.gov (United States)

    Bourgenot, C.; Robertson, D. J.; Stelter, D.; Eikenberry, S.

    2016-07-01

    Concave blazed gratings greatly simplify the architecture of spectrographs by reducing the number of optical components. The production of these gratings using diamond-machining offers practically no limits in the design of the grating substrate shape, with the possibility of making large sag freeform surfaces unlike the alternative and traditional method of holography and ion etching. In this paper, we report on the technological challenges and progress in the making of these curved blazed gratings using an ultra-high precision 5 axes Moore-Nanotech machine. We describe their implementation in an integral field unit prototype called IGIS (Integrated Grating Imaging Spectrograph) where freeform curved gratings are used as pupil mirrors. The goal is to develop the technologies for the production of the next generation of low-cost, compact, high performance integral field unit spectrometers.

  5. Apodized grating coupler using fully-etched nanostructures

    International Nuclear Information System (INIS)

    Wu Hua; Li Chong; Guo Xia; Li Zhi-Yong

    2016-01-01

    A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency. Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer. (paper)

  6. Grate-firing of biomass for heat and power production

    DEFF Research Database (Denmark)

    Yin, Chungen; Rosendahl, Lasse; Kær, Søren Knudsen

    2008-01-01

    bed on the grate, and the advanced secondary air supply (a real breakthrough in this technology) are highlighted for grate-firing systems. Amongst all the issues or problems associated with grate-fired boilers burning biomass, primary pollutant formation and control, deposition formation and corrosion......As a renewable and environmentally friendly energy source, biomass (i.e., any organic non-fossil fuel) and its utilization are gaining an increasingly important role worldwide Grate-firing is one of the main competing technologies in biomass combustion for heat and power production, because it can...... combustion mechanism, the recent breakthrough in the technology, the most pressing issues, the current research and development activities, and the critical future problems to be resolved. The grate assembly (the most characteristic element in grate-fired boilers), the key combustion mechanism in the fuel...

  7. Does the population living in Roma settlements differ in physical activity, smoking and alcohol consumption from the majority population in Slovakia?

    Science.gov (United States)

    Babinská, Ingrid; Gecková, Andrea Madarasová; Jarcuska, Peter; Pella, Daniel; Mareková, Mária; Stefková, Gabriela; Veselská, Zuzana Dankulincová

    2014-03-01

    Several studies have revealed a high prevalence of risk factors associated with unhealthy lifestyle among individuals with lower socioeconomic status. In Slovakia, one of the most socially and health-disadvantaged groups is the Roma minority. The aim of this study is to explore differences in physical activity, smoking and alcohol consumption between the population living in Roma settlements and the majority population in Slovakia. Data from the cross-sectional epidemiological HepaMeta study conducted in Slovakia in 2011 were used. The sample consisted of 452 Roma (mean age = 34.7; 35.2% men) and 403 non-Roma (mean age = 33.5; 45.9% men) respondents. The differences in health-related behaviour between the population living in Roma settlements and the majority population were analysed using logistic models separately for males and females. These data show a clear difference between the population living in Roma settlements and the majority population with regard to leisure-time physical activity (only in women) and smoking, although not alcohol consumption. The prevalence of leisure-time physical activities such as walking or some other type of sport was significantly lower among Roma women than among non-Roma women. Men and women living in Roma settlements are more likely to smoke on a daily basis and they are heavier smokers in comparison with the majority population. HepaMeta study did not find differences in alcohol consumption between the Roma and non-Roma men. However, Roma women reported less frequent recent drinking and binge-drinking of 6 or more doses of alcohol on a single occasion. The higher prevalence of unhealthy lifestyle activities among Roma seem to contribute to these inequalities in cardiovascular diseases morbidity and mortality in comparison with the majority population.

  8. Prevalence of different palatal rugae patterns in a sample Lucknow population

    Directory of Open Access Journals (Sweden)

    Mohammed Asdullah

    2014-01-01

    Full Text Available Introduction: Palatoscopy is the study of palatal rugae pattern and it can be used to establish the identity of a person. The rugae are unique internal structures protected by the lips, buccal pad of fat and teeth that resist decomposition, thus serving an important role in forensic identification. The appearance of palatal rugae is constant, as they do not demonstrate changes after the completion of growth of the individual, thus increasing its utility as a personal identification tool. Aims and Objectives: To study the prevalence of different palatal rugae patterns in a sample of Lucknow, India population. Materials and Methods: The study comprised 100 healthy (50 males and 50 females subjects of age between 18 and 40 years, who were randomly selected. In this study we used the classification of rugae patterns suggested by Kapali et al. (straight, curved, wavy andcircular, and Thomas and Kotze (unification and nonspecific. Results: The mean rugae number in females was slightly more than males. The most prevalent forms in both genders were curved type followed by wavy, straight and diverging types. Straight and curved forms were significantly more in numbers in females than males. Conclusion: This is a preliminary study on a localized Indian population. Scope still exists for further studies to determine gender as well as personal identification. We believe that rugae can be used as a reliable guide in forensic identification.

  9. Different levels of shade on population of grasshoppers and its oviposition preference on heliconias

    Directory of Open Access Journals (Sweden)

    Ana Cristina Bittar

    2018-02-01

    Full Text Available ABSTRACT: Grasshoppers of the families Acrididae and Romaleidae (Orthoptera are among the insects that defoliate heliconias and have been gaining status as pests of commercial crops of these plants in Brazil. The objectives of the present study were to identify the grasshopper defoliating heliconias in the municipality of Santo Antônio de Pádua, RJ (Brazil, to evaluate the effect of different levels of shade on the population of this grasshopper and the production parameters of heliconias, and to determine if this grasshopper has an oviposition preference among the heliconias evaluated. The experiment was in a completely randomized block design, in subdivided plots (four levels of shade in the plot, 0%, 30%, 50% and 80%, and four species of Heliconia: H. psittacorum, H. stricta, H. wagneriana and H. psittacorum x H. spathocircinata ‘Golden Torch’ in the subplot, with four replications. The grasshopper was identified as Cornops frenatum frenatum (Acrididae. An increase in shade resulted in a decrease in the number of oviposition holes from the grasshopper and the number of lateral buds. Shade did not influence the number of C. f. frenatum nymphs and adults and the number of flower stems. H. wagneriana was the most preferred species for oviposition by C. f. frenatum. Results suggested using screens to shade heliconia plants can help control C. f. frenatum populations, however, the light requirements of the heliconias should be considered to guarantee productivity.

  10. Phytochemical composition of the essential oil of different populations of Stachys lavandulifolia Vahl

    Institute of Scientific and Technical Information of China (English)

    Abdollah Ghasemi Pirbalouti; Maryam Mohammadi

    2013-01-01

    Objective: To examine the chemical variability in inflorescences of wild populations of Stachys lavandulifolia Vahl (S. lavandulifolia) collected throughout two provinces (Isfahan and Chaharmahal va Bakhtiary), Southwest Iran. Methods: The essential oils of S. lavandulifolia Vahl from seven locations were obtained by hydro-distillation and analysed by gas chromatography and gas chromatography-mass spectrometry. Results: The results revealed that distinct differences in the content of compounds depending on region of sample collection. The main constituents of the essential oils were α-thujone (0.3%-32.3%), α-pinene (trace to 37.3%), myrcene (0.5%-15.9%),β-phellandrene (1.1%-37.9%), germacrene D (0.4%-11.3%),∆-cadinene (trace to 11.6%) and 1, 4-methano-1 H-indene (trace to 10.1%). Conclusions:The results of the present study indicated that essential oil components of S. lavandulifolia Vahl can be varied with genetic (ecotype), environmental conditions and geographic origin. In general, the essential oils of various populations of S. lavandulifolia Vahl were rich in monoterpenoids and sesquiterpenoids.

  11. Design Parameter Optimization of a Silicon-Based Grating Waveguide for Performance Improvement in Biochemical Sensor Application.

    Science.gov (United States)

    Hong, Yoo-Seung; Cho, Chun-Hyung; Sung, Hyuk-Kee

    2018-03-05

    We performed numerical analysis and design parameter optimization of a silicon-based grating waveguide refractive index (RI) sensor. The performance of the grating waveguide RI sensor was determined by the full-width at half-maximum (FWHM) and the shift in the resonance wavelength in the transmission spectrum. The transmission extinction, a major figure-of-merit of an RI sensor that reflects both FWHM and resonance shift performance, could be significantly improved by the proper determination of three major grating waveguide parameters: duty ratio, grating period, and etching depth. We analyzed the transmission characteristics of the grating waveguide under various design parameter conditions using a finite-difference time domain method. We achieved a transmission extinction improvement of >26 dB under a given bioenvironmental target change by the proper choice of the design procedure and parameters. This design procedure and choice of appropriate parameters would enable the widespread application of silicon-based grating waveguide in high-performance RI biochemical sensor.

  12. Grating-coupled surface plasmon enhanced short-circuit current in organic thin-film photovoltaic cells.

    Science.gov (United States)

    Baba, Akira; Aoki, Nobutaka; Shinbo, Kazunari; Kato, Keizo; Kaneko, Futao

    2011-06-01

    In this study, we demonstrate the fabrication of grating-coupled surface plasmon resonance (SPR) enhanced organic thin-film photovoltaic cells and their improved photocurrent properties. The cell consists of a grating substrate/silver/P3HT:PCBM/PEDOT:PSS structure. Blu-ray disk recordable substrates are used as the diffraction grating substrates on which silver films are deposited by vacuum evaporation. P3HT:PCBM films are spin-coated on silver/grating substrates. Low conductivity PEDOT:PSS/PDADMAC layer-by-layer ultrathin films deposited on P3HT:PCBM films act as the hole transport layer, whereas high conductivity PEDOT:PSS films deposited by spin-coating act as the anode. SPR excitations are observed in the fabricated cells upon irradiation with white light. Up to a 2-fold increase in the short-circuit photocurrent is observed when the surface plasmon (SP) is excited on the silver gratings as compared to that without SP excitation. The finite-difference time-domain simulation indicates that the electric field in the P3HT:PCBM layer can be increased using the grating-coupled SP technique. © 2011 American Chemical Society

  13. The cross waveguide grating: proposal, theory and applications.

    Science.gov (United States)

    Muñoz, Pascual; Pastor, Daniel; Capmany, José

    2005-04-18

    In this paper a novel grating-like integrated optics device is proposed, the Cross Waveguide Grating (XWG). The device is based upon a modified configuration of a traditional Arrayed Waveguide Grating (AWG). The Arrayed Waveguides part is changed, as detailed along this document, giving the device both the ability of multi/demultiplexing and power splitting/coupling. Design examples and transfer function simulations show good agreement with the presented theory. Finally, some of the envisaged applications are outlined.

  14. Observation of narrowband intrinsic spectra of Brillouin dynamic gratings.

    Science.gov (United States)

    Song, Kwang Yong; Yoon, Hyuk Jin

    2010-09-01

    We experimentally demonstrate that the reflection spectrum of a Brillouin dynamic grating in a polarization-maintaining fiber can be much narrower than the intrinsic linewidth of the stimulated Brillouin scattering, matching well with the theory of a fiber Bragg grating in terms of the linewidth and the reflectivity. A 3 dB bandwidth as narrow as 10.5 MHz is observed with the Brillouin dynamic grating generated in a 9 m uniform fiber.

  15. Gender differences of cannabis smoking on serum leptin levels: population-based study

    Directory of Open Access Journals (Sweden)

    Fernanda P. Moreira

    2018-02-01

    Full Text Available Objective: To evaluate the serum leptin levels in cannabis smokers. Methods: This was a cross-sectional population-based study of participants between the ages of 18 and 35 years. The data were collected through a self-administered questionnaire covering sociodemographic data and the use of psychoactive substances. Leptin levels were measured using a commercial ELISA kit. Results: Of the 911 participants, 6.7% were identified as cannabis smokers and had significantly lower leptin levels (p = 0.008. When stratified by gender, there was a significant decrease in leptin levels among male smokers (p = 0.039. Conclusion: Cannabis smoking was linked to leptin levels in men, suggesting that the response to biological signals may be different between men and women.

  16. Urban-rural differences in a population-based breast cancer screening program in Croatia

    Science.gov (United States)

    Stamenić, Valerija; Strnad, Marija

    2011-01-01

    Aim To investigate urban-rural differences in the distribution of risk factors for breast cancer. Methods We analyzed the data from the first round of the “Mamma” population based-screening program conducted in Croatia between 2007 and 2009 and self-reported questionnaire results for 924 patients with histologically verified breast cancer. Reproductive and anthropometric characteristics, family history of breast cancer, history of breast disease, and prior breast screening history were compared between participants from the city of Zagreb (n = 270) and participants from 13 counties with more than 50% of rural inhabitants (n = 654). Results The screen-detected breast cancer rate was 4.5 per 1000 mammographies in rural counties and 4.6 in the city of Zagreb, while the participation rate was 61% in rural counties and 59% in Zagreb. Women from Zagreb had significantly more characteristics associated with an increased risk of breast cancer (P < 0.001 in all cases): no pregnancies (15% vs 7%), late age of first pregnancy (≥30 years) (10% vs 4%), and the most recent mammogram conducted 2-3 years ago (32% vs 14%). Women from rural counties were more often obese (41% vs 28%) and had early age of first live birth (<20 years) (20% vs 7%, P < 0.001 for both). Conclusion Identification of rural-urban differences in mammography use and their causes at the population level can be useful in designing and implementing interventions targeted at the reduction of inequalities and modifiable risk factors. PMID:21328724

  17. A PCR survey of vector-borne pathogens in different dog populations from Turkey.

    Science.gov (United States)

    Guo, Huanping; Sevinc, Ferda; Ceylan, Onur; Sevinc, Mutlu; Ince, Ege; Gao, Yang; Moumouni, Paul Franck Adjou; Liu, Mingming; Efstratiou, Artemis; Wang, Guanbo; Cao, Shinuo; Zhou, Mo; Jirapattharasate, Charoonluk; Ringo, Aaron Edmond; Zheng, Weiqing; Xuan, Xuenan

    2017-09-26

    In the present study, a total of 192 blood samples were collected from pet dogs, kennel dogs and shepherd dogs in Konya district, Turkey, and tested by specific PCR for the presence of vector-borne pathogens. Several pathogens were identified, most of which can cause substantial morbidity in dogs. PCR results revealed that 54 (28.1%) dogs were infected with one or more pathogens. Positive results were obtained for Babesia spp. in 4 dogs (2.1%), Hepatozoon spp. in 8 dogs (4.2%) and Mycoplasma spp. in 46 dogs (24%). Three dogs (1.6%) were infected with two or three pathogens. The sequence analysis of the positive DNA samples revealed the presence of Babesia canis vogeli, Hepatozoon canis, Hepatozoon sp. MF, Mycoplasma haemocanis and Candidatus Mycoplasma haematoparvum. Ehrlichia canis and Anaplasma platys were not detected. Regardless of ownership status, vector-borne diseases were common in these dog populations. There was significant difference of pathogen prevalence among the different dog populations. Mycoplasma spp. was more frequent in the kennel dogs (31.9%) than in the pet (21.4%) and shepherd dogs (13.8%). Additionally, the frequency of Babesia spp. and Hepatozoon spp. was higher in the shepherd dogs which account for three quarters and half of the total number of Babesia spp. and Hepatozoon spp., respectively. To our knowledge, this is the first report of Mycoplasma infection in dogs in Turkey. The results of the present study provide a foundation for understanding the epidemiology of canine vector-borne diseases (CVBDs), and for strategies to control these diseases in Turkey.

  18. Prevalence of depression: Comparisons of different depression definitions in population-based samples of older adults.

    Science.gov (United States)

    Sjöberg, Linnea; Karlsson, Björn; Atti, Anna-Rita; Skoog, Ingmar; Fratiglioni, Laura; Wang, Hui-Xin

    2017-10-15

    Depression prevalence in older adults varies largely across studies, which probably reflects methodological rather than true differences. This study aims to explore whether and to what extent the prevalence of depression varies when using different diagnostic criteria and rating scales, and various samples of older adults. A population-based sample of 3353 individuals aged 60-104 years from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K) were examined in 2001-2004. Point prevalence of depression was estimated by: 1) diagnostic criteria, ICD-10 and DSM-IV-TR/DSM-5; 2) rating scales, MADRS and GDS-15; and 3) self-report. Depression prevalence in sub-samples by dementia status, living place, and socio-demographics were compared. The prevalence of any depression (including all severity grades) was 4.2% (moderate/severe: 1.6%) for ICD-10 and 9.3% (major: 2.1%) for DSM-IV-TR; 10.6% for MADRS and 9.2% for GDS-15; and 9.1% for self-report. Depression prevalence was lower in the dementia-free sample as compared to the total population. Furthermore, having poor physical function, or not having a partner were independently associated with higher depression prevalence, across most of the depression definitions. The response rate was 73.3% and this may have resulted in an underestimation of depression. Depression prevalence was similar across all depression definitions except for ICD-10, showing much lower figures. However, independent of the definition used, depression prevalence varies greatly by dementia status, physical functioning, and marital status. These findings may be useful for clinicians when assessing depression in older adults and for researchers when exploring and comparing depression prevalence across studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Clinical Implications of Human Population Differences in Genome-wide Rates of Functional Genotypes

    Directory of Open Access Journals (Sweden)

    Ali eTorkamani

    2012-11-01

    Full Text Available There have been a number of recent successes in the use of whole genome sequencing and sophisticated bioinformatics techniques to identify pathogenic DNA sequence variants responsible for individual idiopathic congenital conditions. However, the success of this identification process is heavily influenced by the ancestry or genetic background of a patient with an idiopathic condition. This is so because potential pathogenic variants in a patient’s genome must be contrasted with variants in a reference set of genomes made up of other individuals’ genomes of the same ancestry as the patient. We explored the effect of ignoring the ancestries of both an individual patient and the individuals used to construct reference genomes. We pursued this exploration in two major steps. We first considered variation in the per-genome number and rates likely functional derived (i.e., non-ancestral, based on the chimp genome single nucleotide variants and small indels in 52 individual whole human genomes sampled from 10 different global populations. We took advantage of a suite of computational and bioinformatics techniques to predict the functional effect of over 24 million genomic variants, both coding and non-coding, across these genomes. We found that the typical human genome harbors ~5.5-6.1 million total derived variants, of which ~12,000 are likely to have a functional effect (~5000 coding and ~7000 non-coding. We also found that the rates of functional genotypes per the total number of genotypes in individual whole genomes differ dramatically between human populations. We then created tables showing how the use of comparator or reference genome panels comprised of genomes from individuals that do not have the same ancestral background as a patient can negatively impact pathogenic variant identification. Our results have important implications for clinical sequencing initiatives.

  20. Cell population data in neonates: differences by age group and associations with perinatal factors.

    Science.gov (United States)

    Lee, J; Kim, S Y; Lee, W; Han, K; Sung, I K

    2015-10-01

    Cell population data (CPD) describe physical parameters of white blood cell subpopulations and are reported to be of some value in the diagnosis of sepsis in neonates. Before using the CPD for diagnosing sepsis, the baseline features of the CPD distribution in healthy neonates should be clarified. The aim of this study was to compare the CPD distributions of healthy neonates and other age groups and to identify perinatal factors that are associated with changes in the CPD distribution of healthy neonates. The CPD distribution of 69 samples from term neonates was compared with adolescents and adults. The CPD distribution of 163 samples from healthy neonates was analyzed in association with perinatal factors, including gestational age, chronologic age, birthweight, delivery mode, premature rupture of membranes, diabetes, and pregnancy-induced hypertension. The CPD distribution for term neonates was significantly different from those in adolescents and adults. The mean lymphocyte volume showed a negative correlation with gestational age at birth (r = -0.305; P group than in the normal delivery group. The small for gestational age (SGA) group had smaller mean neutrophil volume and mean monocyte volume than the appropriate for gestational age group. The CPD distribution of healthy neonates differed from those of adolescents or adults, and the differences were associated with gestational age, delivery mode, and being SGA. © 2015 John Wiley & Sons Ltd.

  1. A comparison of pectoral fin contact between two different wild dolphin populations

    Science.gov (United States)

    Dudzinski, K.M.; Gregg, J.D.; Ribic, C.A.; Kuczaj, S.A.

    2009-01-01

    Contact behaviour involving the pectoral fin has been documented in a number of dolphin species, and various explanations about its function have been offered. Pectoral fin contact can take a variety of forms, and involves a number of body parts and movements, likely differing depending upon social or ecological context. For this study, we compare the pectoral fin contact behaviour of two species of wild dolphins: Indo-Pacific bottlenose dolphins (Tursiops aduncus) from around Mikura Island, Japan, and Atlantic spotted dolphins (Stenella frontalis) from The Bahamas. The two study populations exhibit surprising similarity in the ways in which pectoral fin contacts are used, despite differences in species and environmental conditions at the two sites. Differences in contact rates for calves between the two sites suggest that calf-focused aggression from adult dolphins is more prevalent at Mikura than in The Bahamas. Our results suggest that pectoral fin contact behaviour seems to be driven primarily by social pressures, and may be similar in function to allogrooming described in primates. ?? 2008 Elsevier B.V.

  2. Components of the metabolic syndrome differ between young and old adults in the US population.

    Science.gov (United States)

    Sumner, Andrew D; Sardi, Gabriel L; Reed, James F

    2012-08-01

    Prevalence of the metabolic syndrome (MetS) is high in the United States and is associated with increased risk of cardiovascular disease and diabetes. The authors examined whether the prevalence of the MetS and its components differs across age groups. Data were analyzed from 4 National Health and Nutrition Examination Surveys between the years 1999 and 2006. Prevalence of MetS as defined by the Third Report of the Adult Treatment Panel criteria and prevalence of associated cardiac risk factors were determined in 41,474 participants aged 18 years and older without a history of cardiovascular disease (CVD). All estimates were weighted. Prevalence of MetS among asymptomatic adults without CVD was 20.5% and remained stable for the total population during survey periods. Prevalence of MetS increased with age: 6.6% in young adults (age 18-29 years) and 34.6% in older adults (70 and older). Components of MetS differed between young and old adults. Young adults had lower levels of high-density lipoprotein cholesterol, less glucose intolerance, and less hypertension. This study provides an estimate of MetS prevalence in asymptomatic adults in the United States during an 8-year period revealing that MetS affects a large number of Americans. Components of MetS differ between young and old adults and may have important implications in their clinical management. © 2012 Wiley Periodicals, Inc.

  3. Adaptations to different habitats in sexual and asexual populations of parasitoid wasps: a meta-analysis.

    Science.gov (United States)

    Amat, Isabelle; van Alphen, Jacques J M; Kacelnik, Alex; Desouhant, Emmanuel; Bernstein, Carlos

    2017-01-01

    Coexistence of sexual and asexual populations remains a key question in evolutionary ecology. We address the question how an asexual and a sexual form of the parasitoid Venturia canescens can coexist in southern Europe. We test the hypothesis that both forms are adapted to different habitats within their area of distribution. Sexuals inhabit natural environments that are highly unpredictable, and where density of wasps and their hosts is low and patchily distributed. Asexuals instead are common in anthropic environments (e.g., grain stores) where host outbreaks offer periods when egg-load is the main constraint on reproductive output. We present a meta-analysis of known adaptations to these habitats. Differences in behavior, physiology and life-history traits between sexual and asexual wasps were standardized in term of effect size (Cohen's d value; Cohen, 1988). Seeking consilience from the differences between multiple traits, we found that sexuals invest more in longevity at the expense of egg-load, are more mobile, and display higher plasticity in response to thermal variability than asexual counterparts. Thus, each form has consistent multiple adaptations to the ecological circumstances in the contrasting environments.

  4. Adaptations to different habitats in sexual and asexual populations of parasitoid wasps: a meta-analysis

    Directory of Open Access Journals (Sweden)

    Isabelle Amat

    2017-09-01

    Full Text Available Background Coexistence of sexual and asexual populations remains a key question in evolutionary ecology. We address the question how an asexual and a sexual form of the parasitoid Venturia canescens can coexist in southern Europe. We test the hypothesis that both forms are adapted to different habitats within their area of distribution. Sexuals inhabit natural environments that are highly unpredictable, and where density of wasps and their hosts is low and patchily distributed. Asexuals instead are common in anthropic environments (e.g., grain stores where host outbreaks offer periods when egg-load is the main constraint on reproductive output. Methods We present a meta-analysis of known adaptations to these habitats. Differences in behavior, physiology and life-history traits between sexual and asexual wasps were standardized in term of effect size (Cohen’s d value; Cohen, 1988. Results Seeking consilience from the differences between multiple traits, we found that sexuals invest more in longevity at the expense of egg-load, are more mobile, and display higher plasticity in response to thermal variability than asexual counterparts. Discussion Thus, each form has consistent multiple adaptations to the ecological circumstances in the contrasting environments.

  5. Nanoporous Polymeric Grating-Based Optical Biosensors (Preprint)

    National Research Council Canada - National Science Library

    Hsiao, Vincent K; Waldeisen, John R; Lloyd, Pamela F; Bunning, Timothy J; Huang, Tony J

    2007-01-01

    .... The fabrication process of the nanoporous polymeric grating involves holographic interference patterning and a functionalized pre-polymer syrup that facilitates the immobilization of biomolecules...

  6. High-mechanical-strength single-pulse draw tower gratings

    Science.gov (United States)

    Rothhardt, Manfred W.; Chojetzki, Christoph; Mueller, Hans Rainer

    2004-11-01

    The inscription of fiber Bragg gratings during the drawing process is a very useful method to realize sensor arrays with high numbers of gratings and excellent mechanical strength and also type II gratings with high temperature stability. Results of single pulse grating arrays with numbers up to 100 and definite wavelengths and positions for sensor applications were achieved at 1550 nm and 830 nm using new photosensitive fibers developed in IPHT. Single pulse type I gratings at 1550 nm with more than 30% reflectivity were shown first time to our knowledge. The mechanical strength of this fiber with an Ormocer coating with those single pulse gratings is the same like standard telecom fibers. Weibull plots of fiber tests will be shown. At 830 nm we reached more than 10% reflectivity with single pulse writing during the fiber drawing in photosensitive fibers with less than 16 dB/km transmission loss. These gratings are useful for stress and vibration sensing applications. Type II gratings with reflectivity near 100% and smooth spectral shape and spectral width of about 1 nm are temperature stable up to 1200 K for short time. They are also realized in the fiber drawing process. These gratings are useful for temperature sensor applications.

  7. Bragg Fibers with Soliton-like Grating Profiles

    Directory of Open Access Journals (Sweden)

    Bugaychuk S.

    2016-01-01

    Full Text Available Nonlinear dynamical system corresponding to the optical holography in a nonlocal nonlinear medium with dissipation contains stable localized spatio-temporal states, namely the grid dissipative solitons. These solitons display a non-uniform profile of the grating amplitude, which has the form of the dark soliton in the reflection geometry. The transformation of the grating amplitude gives rise many new atypical effects for the beams diffracted on such grating, and they are very suitable for the fiber Brass gratings. The damped nonlinear Schrodinger equation is derived that describes the properties of the grid dissipative soliton.

  8. Spherical grating based x-ray Talbot interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Cong, Wenxiang, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Xi, Yan, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Wang, Ge, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu [Biomedical Imaging Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-15

    Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and

  9. Spherical grating based x-ray Talbot interferometry

    International Nuclear Information System (INIS)

    Cong, Wenxiang; Xi, Yan; Wang, Ge

    2015-01-01

    Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and

  10. Ethnic differences in fetal size and growth in a multi-ethnic population.

    Science.gov (United States)

    Sletner, Line; Rasmussen, Svein; Jenum, Anne Karen; Nakstad, Britt; Jensen, Odd Harald Rognerud; Vangen, Siri

    2015-09-01

    Impaired or excessive fetal growth is associated with adverse short- and long-term health outcomes that differ between ethnic groups. We explored ethnic differences in fetal size and growth from mid pregnancy until birth. Data are from the multi-ethnic STORK-Groruddalen study, a population-based, prospective cohort of 823 pregnant women and their offspring in Oslo, Norway. Measures were z-scores of estimated fetal weight (EFW), head circumference (HC), abdominal circumference (AC) and femur length (FL), in gestational week 24, 32 and 37, measured by ultrasound, and similar measures at birth. Differences in fetal size and growth were assessed using separate Linear Mixed Models including all four time points, with ethnic Europeans as reference. In week 24 South Asian fetuses had smaller AC, but larger FL than Europeans, and slightly lower EFW (-0.17 SD (-0.33, -0.01), p=0.04). Middle East/North African fetuses also had larger FL, but similar AC, and hence slightly higher EFW (0.18 (0.003, 0.36), p=0.05). Both groups had slower growth of AC, FL and EFW from this time until birth, and had -0.61 SD (-0.73, -0.49) and -0.28 SD (-0.41, -0.15) lower birth weight respectively. Ethnic East Asians, on the other hand, were smaller throughout pregnancy and had -0.58 SD (-0.82, -0.34) lower birth weight. Significant ethnic differences remained after adjusting for maternal factors. We observed ethnic differences in fetal size and body proportions already in gestational week 24, and in fetal growth from this time until birth, which were only partly explained by key maternal factors. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  11. Healthy eating habits among the population of Serbia: gender and age differences.

    Science.gov (United States)

    Jovičić, Ana Đ

    2015-03-01

    The purpose of the study is to examine healthy eating habits of the population of Serbia through three dimensions: knowledge, problems, and feelings as well as to determine whether there are any differences between genders and among different age-groups. The research instrument was an Eating Habits Questionnaire (EHQ) which consisted of 35 items. There were 382 respondents involved in the study. The reliability and factor structure of the questionnaire were verified by using factor analysis. The results of MANOVA showed that there is a significant difference in the habits concerning healthy eating between men and women [F (3,378)=4.26, p=0.006; Wilks' Lambda=0.97]. When the results for the dependent variables (knowledge, problems, and feelings) were considered separately, it was determined that there is no significant difference between men and women, which confirms the results of the t-test. The effect of age on the three dimensions of healthy eating habits was examined within three age-groups, by using ANOVA. The results showed that knowledge about healthy eating increases with age [F (2,379)=6.14, p=0.002] as well as positive feelings which occur as a result of healthy eating [F (2,379)=3.66, p=0.027]. Unlike ANOVA, MANOVA showed difference among the age-groups only when it came to the 'knowledge' variable. This study is important as it shows the current state of awareness on healthy eating habits in the researched populace and may be the basis for further research in this field in Serbia.

  12. InTeGrate's model for developing innovative, adaptable, interdisciplinary curricular materials that reach beyond the geosciences

    Science.gov (United States)

    Egger, A. E.; Baldassari, C.; Bruckner, M. Z.; Iverson, E. A.; Manduca, C. A.; Mcconnell, D. A.; Steer, D. N.

    2013-12-01

    InTeGrate is NSF's STEP Center in the geosciences. A major goal of the project is to develop curricula that will increase the geoscience literacy of all students such that they are better positioned to make sustainable decisions in their lives and as part of the broader society. This population includes the large majority of students that do not major in the geosciences, those historically under-represented in the geosciences, and future K-12 teachers. To achieve this goal, we established a model for the development of curricular materials that draws on the distributed expertise of the undergraduate teaching community. Our model seeks proposals from across the higher education community for courses and modules that meet InTeGrate's overarching goals. From these proposals, we select teams of 3-5 instructors from three or more different institutions (and institution types) and pair them with assessment and web experts. Their communication and development process is supported by a robust, web-based content management system (CMS). Over two years, this team develops materials that explicitly address a geoscience-related societal challenge, build interdisciplinary problem-solving skills, make use of real geoscience data, and incorporate geoscientific and systems thinking. Materials are reviewed with the InTeGrate design rubric and then tested by the authors in their own courses, where student learning is assessed. Results are reviewed by the authors and our assessment team to guide revisions. Several student audiences are targeted: students in general education and introductory geoscience courses, pre-service K-12 teachers, students in other science and engineering majors, as well as those in the humanities and social sciences. Curriculum development team members from beyond the geosciences are critical to producing materials that can be adopted for all of these audiences, and we have been successful in engaging faculty from biology, economics, engineering, sociology

  13. Region-wide and ecotype-specific differences in demographic histories of threespine stickleback populations, estimated from whole genome sequences.

    Science.gov (United States)

    Liu, Shenglin; Hansen, Michael M; Jacobsen, Magnus W

    2016-10-01

    We analysed 81 whole genome sequences of threespine sticklebacks from Pacific North America, Greenland and Northern Europe, representing 16 populations. Principal component analysis of nuclear SNPs grouped populations according to geographical location, with Pacific populations being more divergent from each other relative to European and Greenlandic populations. Analysis of mitogenome sequences showed Northern European populations to represent a single phylogeographical lineage, whereas Greenlandic and particularly Pacific populations showed admixture between lineages. We estimated demographic history using a genomewide coalescence with recombination approach. The Pacific populations showed gradual population expansion starting >100 Kya, possibly reflecting persistence in cryptic refuges near the present distributional range, although we do not rule out possible influence of ancient admixture. Sharp population declines ca. 14-15 Kya were suggested to reflect founding of freshwater populations by marine ancestors. In Greenland and Northern Europe, demographic expansion started ca. 20-25 Kya coinciding with the end of the Last Glacial Maximum. In both regions, marine and freshwater populations started to show different demographic trajectories ca. 8-9 Kya, suggesting that this was the time of recolonization. In Northern Europe, this estimate was surprisingly late, but found support in subfossil evidence for presence of several freshwater fish species but not sticklebacks 12 Kya. The results demonstrate distinctly different demographic histories across geographical regions with potential consequences for adaptive processes. They also provide empirical support for previous assumptions about freshwater populations being founded independently from large, coherent marine populations, a key element in the Transporter Hypothesis invoked to explain the widespread occurrence of parallel evolution across freshwater stickleback populations. © 2016 John Wiley & Sons Ltd.

  14. Gender differences of the morphology of the distal femur and proximal tibia in a Korean population.

    Science.gov (United States)

    Lim, Hong-Chul; Bae, Ji-Hoon; Yoon, Ji-Yeol; Kim, Seung-Ju; Kim, Jae-Gyoon; Lee, Jae-Moon

    2013-01-01

    We conducted this study to determine whether the sizes of distal femurs and proximal tibiae in Korean men and women are different, and to assess suitability of the sizes of prostheses currently used in Korea. We performed morphological analysis of proximal tibia and distal femur on 115 patients (56 male, 59 female) using MRI to investigate a gender difference. Tibial mediolateral dimension (tMAP), tibial medial anteroposterior dimension (tMAP), tibial lateral anteroposterior dimension (tLAP) femoral mediolateral dimension (fML), femoral medial anteroposterior dimension (fMAP), and femoral lateral anteroposterior dimension (fLAP) were measured. The ratio of tMAP and tLAP to tML (plateau aspect ratio, tAP/tML×100%), and that of fMAP and fLAP to fML (condylar aspect ratio, fAP/fML×100%) were calculated. The measurements were compared with the similar dimensions of four total knee implants currently used. The tML and tAP lengths showed a significant gender difference (PtMAP/tML) revealed a significant difference between male (0.74±0.05) and female (0.68±0.04, P<0.05). For morphotype of distal femur, males were found to have significantly large values (P<0.05) in the parameters, except for fLAP. With regards to the ratio of the ML width to the AP length, the women showed a narrower ML width than the men. Both genders were distributed within the range of the dimensions of the prostheses currently used prostheses. Korean population revealed that women have smaller dimensions than male counterparts. In both genders, a relatively small size of prostheses matches distal femur and proximal tibia better among the implants currently used in Korea. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Sensing Features of Long Period Gratings in Hollow Core Fibers

    Directory of Open Access Journals (Sweden)

    Agostino Iadicicco

    2015-04-01

    Full Text Available We report on the investigation of the sensing features of the Long-Period fiber Gratings (LPGs fabricated in hollow core photonic crystal fibers (HC-PCFs by the pressure assisted Electric Arc Discharge (EAD technique. In particular, the characterization of the LPG in terms of shift in resonant wavelengths and changes in attenuation band depth to the environmental parameters: strain, temperature, curvature, refractive index and pressure is presented. The achieved results show that LPGs in HC-PCFs represent a novel high performance sensing platform for measurements of different physical parameters including strain, temperature and, especially, for measurements of environmental pressure. The pressure sensitivity enhancement is about four times greater if we compare LPGs in HC and standard fibers. Moreover, differently from LPGs in standard fibers, these LPGs realized in innovative fibers, i.e., the HC-PCFs, are not sensitive to surrounding refractive index.

  16. Population Analysis of Adverse Events in Different Age Groups Using Big Clinical Trials Data.

    Science.gov (United States)

    Luo, Jake; Eldredge, Christina; Cho, Chi C; Cisler, Ron A

    2016-10-17

    Understanding adverse event patterns in clinical studies across populations is important for patient safety and protection in clinical trials as well as for developing appropriate drug therapies, procedures, and treatment plans. The objective of our study was to conduct a data-driven population-based analysis to estimate the incidence, diversity, and association patterns of adverse events by age of the clinical trials patients and participants. Two aspects of adverse event patterns were measured: (1) the adverse event incidence rate in each of the patient age groups and (2) the diversity of adverse events defined as distinct types of adverse events categorized by organ system. Statistical analysis was done on the summarized clinical trial data. The incident rate and diversity level in each of the age groups were compared with the lowest group (reference group) using t tests. Cohort data was obtained from ClinicalTrials.gov, and 186,339 clinical studies were analyzed; data were extracted from the 17,853 clinical trials that reported clinical outcomes. The total number of clinical trial participants was 6,808,619, and total number of participants affected by adverse events in these trials was 1,840,432. The trial participants were divided into eight different age groups to support cross-age group comparison. In general, children and older patients are more susceptible to adverse events in clinical trial studies. Using the lowest incidence age group as the reference group (20-29 years), the incidence rate of the 0-9 years-old group was 31.41%, approximately 1.51 times higher (P=.04) than the young adult group (20-29 years) at 20.76%. The second-highest group is the 50-59 years-old group with an incidence rate of 30.09%, significantly higher (Pgroup. The adverse event diversity also increased with increase in patient age. Clinical studies that recruited older patients (older than 40 years) were more likely to observe a diverse range of adverse events (Page group (older

  17. High-accuracy measurement and compensation of grating line-density error in a tiled-grating compressor

    Science.gov (United States)

    Zhao, Dan; Wang, Xiao; Mu, Jie; Li, Zhilin; Zuo, Yanlei; Zhou, Song; Zhou, Kainan; Zeng, Xiaoming; Su, Jingqin; Zhu, Qihua

    2017-02-01

    The grating tiling technology is one of the most effective means to increase the aperture of the gratings. The line-density error (LDE) between sub-gratings will degrade the performance of the tiling gratings, high accuracy measurement and compensation of the LDE are of significance to improve the output pulses characteristics of the tiled-grating compressor. In this paper, the influence of LDE on the output pulses of the tiled-grating compressor is quantitatively analyzed by means of numerical simulation, the output beams drift and output pulses broadening resulting from the LDE are presented. Based on the numerical results we propose a compensation method to reduce the degradations of the tiled grating compressor by applying angular tilt error and longitudinal piston error at the same time. Moreover, a monitoring system is setup to measure the LDE between sub-gratings accurately and the dispersion variation due to the LDE is also demonstrated based on spatial-spectral interference. In this way, we can realize high-accuracy measurement and compensation of the LDE, and this would provide an efficient way to guide the adjustment of the tiling gratings.

  18. Experiments with mathematical models to simulate hepatitis A population dynamics under different levels of endemicity

    Directory of Open Access Journals (Sweden)

    Mariana Alves de Guimaraens

    Full Text Available Heterogeneous access to sanitation services is a characteristic of communities in Brazil. This heterogeneity leads to different patterns of hepatitis A endemicity: areas with low infection rates have higher probability of outbreaks, and areas with higher infection rates have high prevalence and low risk of outbreaks. Here we develop a mathematical model to study the effect of variable exposure to infection on the epidemiological dynamics of hepatitis A. Differential equations were used to simulate population dynamics and were numerically solved using the software StellaTM. The model uses parameters from serological surveys in the Greater Metropolitan Rio de Janeiro, in areas with different sanitation conditions. Computer simulation experiments show that the range of infection rates observed in these communities are characteristic of high and low levels of hepatitis A endemicity. We also found that the functional relationship between sanitation and exposure to infection is an important component of the model. The analysis of the public health impact of partial sanitation requires a better understanding of this relationship.

  19. Gender differences in metabolic risk factor prevalence in a South African student population.

    Science.gov (United States)

    Smith, Carine; Essop, M Faadiel

    2009-01-01

    We determined selected risk factors for the metabolic syndrome and assessed the metabolic risk status (using IDF criteria) of third-year physiology students at Stellenbosch University (88 males and 178 females). Outcome measures included anthropometry [body mass index (BMI), waist circumference, waist-to-hip ratio], blood pressure (BP), resting pulse rate, and fasting blood glucose, total cholesterol and triglyceride levels. In addition, students completed a lifestyle questionnaire. A number of gender-based differences were found, with male students displaying a greater incidence of risk factors for the metabolic syndrome: 6% of males versus 3% of females displayed a cluster of three risk factors. Twenty-five per cent of female students (but only 14% of males) exhibited waist circumferences above the accepted range, which was positively correlated, for males and females, with both systolic and diastolic BP, and in females only, also with total cholesterol levels. Male students on average exercised more than their female counterparts, but also exhibited poorer eating habits. Average blood triglyceride levels for both male and female students exceeded the accepted threshold (1.85 +/- 1.62 mmol/l and 2.15 +/- 1.79 mmol/l, respectively). We concluded that metabolic risk factors were evident in a much younger population than commonly expected. Moreover, the gender-specific differences observed may impact on future risk assessment and preventative measures adopted.

  20. Comparing different stimulus configurations for population receptive field mapping in human fMRI

    Directory of Open Access Journals (Sweden)

    Ivan eAlvarez

    2015-02-01

    Full Text Available Population receptive field (pRF mapping is a widely used approach to measuring aggregate human visual receptive field properties by recording non-invasive signals using functional MRI. Despite growing interest, no study to date has systematically investigated the effects of different stimulus configurations on pRF estimates from human visual cortex. Here we compared the effects of three different stimulus configurations on a model-based approach to pRF estimation: size-invariant bars and eccentricity-scaled bars defined in Cartesian coordinates and traveling along the cardinal axes, and a novel simultaneous ‘wedge and ring’ stimulus defined in polar coordinates, systematically covering polar and eccentricity axes. We found that the presence or absence of eccentricity scaling had a significant effect on goodness of fit and pRF size estimates. Further, variability in pRF size estimates was directly influenced by stimulus configuration, particularly for higher visual areas including V5/MT+. Finally, we compared eccentricity estimation between phase-encoded and model-based pRF approaches. We observed a tendency for more peripheral eccentricity estimates using phase-encoded methods, independent of stimulus size. We conclude that both eccentricity scaling and polar rather than Cartesian stimulus configuration are important considerations for optimal experimental design in pRF mapping. While all stimulus configurations produce adequate estimates, simultaneous wedge and ring stimulation produced higher fit reliability, with a significant advantage in reduced acquisition time.

  1. Different populations of subthalamic neurons encode cocaine vs. sucrose reward and predict future error.

    Science.gov (United States)

    Lardeux, Sylvie; Paleressompoulle, Dany; Pernaud, Remy; Cador, Martine; Baunez, Christelle

    2013-10-01

    The search for treatment of cocaine addiction raises the challenge to find a way to diminish motivation for the drug without decreasing it for natural rewards. Subthalamic nucleus (STN) inactivation decreases motivation for cocaine while increasing motivation for food, suggesting that STN can dissociate different rewards. Here, we investigated how rat STN neurons respond to cues predicting cocaine or sucrose and to reward delivery while rats are performing a discriminative stimuli task. We show that different neuronal populations of STN neurons encode cocaine and sucrose. In addition, we show that STN activity at the cue onset predicts future error. When changing the reward predicted unexpectedly, STN neurons show capacities of adaptation, suggesting a role in reward-prediction error. Furthermore, some STN neurons show a response to executive error (i.e., "oops neurons") that is specific to the missed reward. These results position the STN as a nexus where natural rewards and drugs of abuse are coded differentially and can influence the performance. Therefore, STN can be viewed as a structure where action could be taken for the treatment of cocaine addiction.

  2. Are rapid population estimates accurate? A field trial of two different assessment methods.

    Science.gov (United States)

    Grais, Rebecca F; Coulombier, Denis; Ampuero, Julia; Lucas, Marcelino E S; Barretto, Avertino T; Jacquier, Guy; Diaz, Francisco; Balandine, Serge; Mahoudeau, Claude; Brown, Vincent

    2006-09-01

    Emergencies resulting in large-scale displacement often lead to populations resettling in areas where basic health services and sanitation are unavailable. To plan relief-related activities quickly, rapid population size estimates are needed. The currently recommended Quadrat method estimates total population by extrapolating the average population size living in square blocks of known area to the total site surface. An alternative approach, the T-Square, provides a population estimate based on analysis of the spatial distribution of housing units taken throughout a site. We field tested both methods and validated the results against a census in Esturro Bairro, Beira, Mozambique. Compared to the census (population: 9,479), the T-Square yielded a better population estimate (9,523) than the Quadrat method (7,681; 95% confidence interval: 6,160-9,201), but was more difficult for field survey teams to implement. Although applicable only to similar sites, several general conclusions can be drawn for emergency planning.

  3. Age-Group and Gender Differences in Stroke Knowledge in an Israeli Jewish Adult Population.

    Science.gov (United States)

    Melnikov, Semyon; Itzhaki, Michal; Koton, Silvia

    Stroke is a leading cause of long-term disability and the fifth leading cause of death in Israel. Knowledge of stroke warning signs has been linked to early seeking of medical help. Little is known about knowledge of stroke warning signs in Israeli Jewish adults. Stroke knowledge was examined among Jewish Israeli adults. Using a structured questionnaire, registered nurses interviewed a convenience sample of the respondents, 18 years or older, with no stroke history. Stroke knowledge and demographics were examined by 3 age groups (64 years) in men and women. In total, 1137 Jewish Israelis were interviewed, 457 (40.2%) men and 680 women (59.8%); 493 (43.4%) were younger than 45 years, 541 (47.6%) were aged 45 to 64 years, and 102 (9%) were older than 64 years; 1 (0.1%) did not report age. On average, each interview lasted for 25 to 30 minutes. Participants younger than 45 years showed the lowest knowledge of stroke cause. Women younger than 45 years were less likely to identify at least 2 stroke warning signs. Participants younger than 45 years were less likely to identify at least 2 risk factors, compared with participants aged 45 to 64 years and older than 64 years. Women younger than 45 years were less likely to identify at least 2 stroke prevention strategies. Participants younger than 45 years showed the lowest levels of stroke knowledge. The highest stroke knowledge was found in the 45 to 64 years age group. Stroke knowledge among different age groups was similar in both genders. Educational campaigns aimed at increasing knowledge of stroke among the general population and targeting the younger population are recommended.

  4. Population-level differences in revascularization treatment and outcomes among various United States subpopulations

    Institute of Scientific and Technical Information of China (English)

    Garth Graham; Yang-Yu Karen Xiao; Dan Rappoport; Saima Siddiqi

    2016-01-01

    Despite recent general improvements in health care, significant disparities persist in the cardiovascular care of women and racial/ethnic minorities. This is true even when income, education level, and site of care are taken into consideration. Possible explanations for these disparities include socioeconomic considerations, elements of discrimination and racism that affect socioeconomic status, and access to adequate medical care. Coronary revascularization has become the accepted and recommended treatment for myocardial infarction(MI) today and is one of the most common major medical interventions in the United States, with more than 1 million procedures each year. This review discusses recent data on disparities in co-morbidities and presentation symptoms, care and access to medical resources, and outcomes in revascularization as treatment for acute coronary syndrome, looking especially at women and minority populations in the United States. The data show that revascularization is used less in both female and minority patients. We summarize recent data on disparities in co-morbidities and presentation symptoms related to MI; access to care, medical resources, and treatments; and outcomes in women, blacks, and Hispanics. The picture is complicated among the last group by the many Hispanic/Latino subgroups in the United States. Some differences in outcomes are partially explained by presentation symptoms and co-morbidities and external conditions such as local hospital capacity. Of particular note is the striking differential in both presentation co-morbidities and mortality rates seen in women, compared to men, especially in women ≤ 55 years of age. Surveillance data on other groups in the United States such as American Indians/Alaska Natives and the many Asian subpopulations show disparities in risk factors and co-morbidities, but revascularization as treatment for MI in these populations has not been adequately studied. Significant research is required to

  5. Streaked, x-ray-transmission-grating spectrometer

    International Nuclear Information System (INIS)

    Ceglio, N.M.; Roth, M.; Hawryluk, A.M.

    1981-08-01

    A free standing x-ray transmission grating has been coupled with a soft x-ray streak camera to produce a time resolved x-ray spectrometer. The instrument has a temporal resolution of approx. 20 psec, is capable of covering a broad spectral range, 2 to 120 A, has high sensitivity, and is simple to use requiring no complex alignment procedure. In recent laser fusion experiments the spectrometer successfully recorded time resolved spectra over the range 10 to 120 A with a spectral resolving power, lambda/Δlambda of 4 to 50, limited primarily by source size and collimation effects

  6. Transcriptome analysis of fat bodies from two brown planthopper (Nilaparvata lugens populations with different virulence levels in rice.

    Directory of Open Access Journals (Sweden)

    Haixin Yu

    Full Text Available BACKGROUND: The brown planthopper (BPH, Nilaparvata lugens (Stål, one of the most serious rice insect pests in Asia, can quickly overcome rice resistance by evolving new virulent populations. The insect fat body plays essential roles in the life cycles of insects and in plant-insect interactions. However, whether differences in fat body transcriptomes exist between insect populations with different virulence levels and whether the transcriptomic differences are related to insect virulence remain largely unknown. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we performed transcriptome-wide analyses on the fat bodies of two BPH populations with different virulence levels in rice. The populations were derived from rice variety TN1 (TN1 population and Mudgo (M population. In total, 33,776 and 32,332 unigenes from the fat bodies of TN1 and M populations, respectively, were generated using Illumina technology. Gene ontology annotations and Kyoto Encyclopedia of Genes and Genomes (KEGG orthology classifications indicated that genes related to metabolism and immunity were significantly active in the fat bodies. In addition, a total of 339 unigenes showed homology to genes of yeast-like symbionts (YLSs from 12 genera and endosymbiotic bacteria Wolbachia. A comparative analysis of the two transcriptomes generated 7,860 differentially expressed genes. GO annotations and enrichment analysis of KEGG pathways indicated these differentially expressed transcripts might be involved in metabolism and immunity. Finally, 105 differentially expressed genes from YLSs and Wolbachia were identified, genes which might be associated with the formation of different virulent populations. CONCLUSIONS/SIGNIFICANCE: This study was the first to compare the fat-body transcriptomes of two BPH populations having different virulence traits and to find genes that may be related to this difference. Our findings provide a molecular resource for future investigations of fat bodies

  7. Transcriptome Analysis of Fat Bodies from Two Brown Planthopper (Nilaparvata lugens) Populations with Different Virulence Levels in Rice

    Science.gov (United States)

    Chen, Hongdan; Lai, Wenxiang; Fu, Qiang; Lou, Yonggen

    2014-01-01

    Background The brown planthopper (BPH), Nilaparvata lugens (Stål), one of the most serious rice insect pests in Asia, can quickly overcome rice resistance by evolving new virulent populations. The insect fat body plays essential roles in the life cycles of insects and in plant-insect interactions. However, whether differences in fat body transcriptomes exist between insect populations with different virulence levels and whether the transcriptomic differences are related to insect virulence remain largely unknown. Methodology/Principal Findings In this study, we performed transcriptome-wide analyses on the fat bodies of two BPH populations with different virulence levels in rice. The populations were derived from rice variety TN1 (TN1 population) and Mudgo (M population). In total, 33,776 and 32,332 unigenes from the fat bodies of TN1 and M populations, respectively, were generated using Illumina technology. Gene ontology annotations and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology classifications indicated that genes related to metabolism and immunity were significantly active in the fat bodies. In addition, a total of 339 unigenes showed homology to genes of yeast-like symbionts (YLSs) from 12 genera and endosymbiotic bacteria Wolbachia. A comparative analysis of the two transcriptomes generated 7,860 differentially expressed genes. GO annotations and enrichment analysis of KEGG pathways indicated these differentially expressed transcripts might be involved in metabolism and immunity. Finally, 105 differentially expressed genes from YLSs and Wolbachia were identified, genes which might be associated with the formation of different virulent populations. Conclusions/Significance This study was the first to compare the fat-body transcriptomes of two BPH populations having different virulence traits and to find genes that may be related to this difference. Our findings provide a molecular resource for future investigations of fat bodies and will be useful

  8. Transcriptome analysis of fat bodies from two brown planthopper (Nilaparvata lugens) populations with different virulence levels in rice.

    Science.gov (United States)

    Yu, Haixin; Ji, Rui; Ye, Wenfeng; Chen, Hongdan; Lai, Wenxiang; Fu, Qiang; Lou, Yonggen

    2014-01-01

    The brown planthopper (BPH), Nilaparvata lugens (Stål), one of the most serious rice insect pests in Asia, can quickly overcome rice resistance by evolving new virulent populations. The insect fat body plays essential roles in the life cycles of insects and in plant-insect interactions. However, whether differences in fat body transcriptomes exist between insect populations with different virulence levels and whether the transcriptomic differences are related to insect virulence remain largely unknown. In this study, we performed transcriptome-wide analyses on the fat bodies of two BPH populations with different virulence levels in rice. The populations were derived from rice variety TN1 (TN1 population) and Mudgo (M population). In total, 33,776 and 32,332 unigenes from the fat bodies of TN1 and M populations, respectively, were generated using Illumina technology. Gene ontology annotations and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology classifications indicated that genes related to metabolism and immunity were significantly active in the fat bodies. In addition, a total of 339 unigenes showed homology to genes of yeast-like symbionts (YLSs) from 12 genera and endosymbiotic bacteria Wolbachia. A comparative analysis of the two transcriptomes generated 7,860 differentially expressed genes. GO annotations and enrichment analysis of KEGG pathways indicated these differentially expressed transcripts might be involved in metabolism and immunity. Finally, 105 differentially expressed genes from YLSs and Wolbachia were identified, genes which might be associated with the formation of different virulent populations. This study was the first to compare the fat-body transcriptomes of two BPH populations having different virulence traits and to find genes that may be related to this difference. Our findings provide a molecular resource for future investigations of fat bodies and will be useful in examining the interactions between the fat body and virulence

  9. Earth's influx of different populations of sporadic meteoroids from photographic and television data

    International Nuclear Information System (INIS)

    Ceplecha, Z.

    1988-01-01

    Precise photographic and television double- and multi-station data on 3624 sporadic meteors in the mass range from 2 x 10 -5 grams to 2 x 10 7 grams form the basis of this paper. The applied classification criteria and procedures are defined and described. A survey of 7 different populations of sporadic meteoroids known so far is presented. The total numbers and masses of meteoroids as a function of mass are given for individual groups and for all sporadic meteors. The absolute calibration of the influx to the Earth was carried out by comparison with the results of Halliday et al. (1984). The comparison with the visual and cratering data revealed good agreement in the narrow ''visual'' interval of masses, and disagreement in the extrapolated parts of the visual and cratering flux curves. The slope of the cumulative number curve for the meteorite-dropping fireballs (type I) with masses larger than 1 kg was found as -0.69 in perfect agreement with the results of Halliday et al. (1984). The final mass scale derived in this paper is situated between the scale of McCrosky and the scale of Halliday. The relative significance of the different groups of meteoroids changes with the mass quite dramatically. The total influx of sporadic meteoroids in the mass interval of 12 orders from 2 x 10 7 to 2 x 10 -5 grams resulted in 5 x 10 9 grams per year for the entire Earth's surface. Most of this mass comes in the form of larger meteoroids. Bulk densities and ablation coefficient are presented for the individual meteor groups depending on different ablation models of several authors and some extreme concepts of this problem are discussed. (author). 3 figs., 6 tabs., 38 refs

  10. Explaining differences in perceived health-related quality of life: a study within the Spanish population.

    Science.gov (United States)

    Martín-Fernández, Jesús; Ariza-Cardiel, Gloria; Polentinos-Castro, Elena; Sanz-Cuesta, Teresa; Sarria-Santamera, Antonio; Del Cura-González, Isabel

    2017-09-25

    To assess the burden of several determinants on health-related quality of life (HRQOL) and to study its heterogeneity among the different Spanish regions. Cross-sectional study. Data were obtained from the Spanish National Health Survey (2012), and HRQOL was measured using the EQ-5D-5L questionnaire (utility and visual analogue scale -VAS- scores). Demographic variables, physical health condition, social variables, mental health status, and lifestyle were also analysed. Tobit regression models were employed to study the relationships between expressed HRQOL and personal characteristics. A total of 20,979 surveys were obtained. Of them, 62.4% expressed a utility score of 1, corresponding to perfect health (95%CI: 61.8%-63.2%), and 54.2% showed VAS scores ≥80 (95%CI: 53.5%-54.9%). HRQOL was mainly described as a function of age, chronic limitation in daily activities, and mental health status. Belonging to a higher-class strata and physical activity were related to better self-perceived HRQOL. Ageing worsened perceived HRQOL, but did not influence its determinants, and differences in HRQOL by regions were also not significant after model adjustment. HRQOL perception in the Spanish population varied slightly depending on the measure used (utilities index or VAS). Age, chronic limitations in daily life, and mental health status best explained the variability in perception, and no meaningful differences in HRQOL perception among regions were found after adjustment. Copyright © 2017 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

  11. Comparison of trap types and colors for capturing emerald ash borer adults at different population densities.

    Science.gov (United States)

    Poland, Therese M; Mccullough, Deborah G

    2014-02-01

    Results of numerous trials to evaluate artificial trap designs and lures for detection of Agrilus planipennis Fairmaire, the emerald ash borer, have yielded inconsistent results, possibly because of different A. planipennis population densities in the field sites. In 2010 and 2011, we compared 1) green canopy traps, 2) purple canopy traps, 3) green double-decker traps, and 4) purple double-decker traps in sites representing a range of A. planipennis infestation levels. Traps were baited with cis-3-hexenol in both years, plus an 80:20 mixture of Manuka and Phoebe oil (2010) or Manuka oil alone (2011). Condition of trees bearing canopy traps, A. planipennis infestation level of trees in the vicinity of traps, and number of A. planipennis captured per trap differed among sites in both years. Overall in both years, more females, males, and beetles of both sexes were captured on double-decker traps than canopy traps, and more beetles of both sexes (2010) or females (2011) were captured on purple traps than green traps. In 2010, detection rates were higher for purple (100%) and green double-decker traps (100%) than for purple (82%) or green canopy traps (64%) at sites with very low to low A. planipennis infestation levels. Captures of A. planipennis on canopy traps consistently increased with the infestation level of the canopy trap-bearing trees. Differences among trap types were most pronounced at sites with low A. planipennis densities, where more beetles were captured on purple double-decker traps than on green canopy traps in both years.

  12. [Overweight and obesity prevalence estimates in a population from Zaragoza by using different growth references].

    Science.gov (United States)

    Lasarte-Velillas, J J; Hernández-Aguilar, M T; Martínez-Boyero, T; Soria-Cabeza, G; Soria-Ruiz, D; Bastarós-García, J C; Gil-Hernández, I; Pastor-Arilla, C; Lasarte-Sanz, I

    2015-03-01

    To investigate the prevalence of overweight and obesity among our pediatric population and observe whether the use of different growth references for classification produce significant differences. A total of 35824 boys and girls aged between 2 and 14 years were included. Body mass index (BMI) was used to calculate the prevalence of overweight-obesity by age and sex. Prevalence was obtained by using a set of national references (Hernández's standards) and the references of World Health Organization (WHO standards). Prevalences were compared for each age and sex subset, as well as with the percentage of patients who had an overweight-obesity diagnosis in the clinical record. The overall prevalence of overweight-obesity among children aged 2 to 14 years was 17.0% (95% CI; 16.1%-18.0%) according to the Hernández standards vs 30.8% (95% CI; 29.9%-31.7%) according to WHO standards (10.1% vs 12.2% obese, and 6.9% vs 18.6% overweight). It was significantly higher in boys, by both standards, due to the higher prevalence of obesity. By using the Hernández standards the prevalence was significantly lower than by using WHO standards for all ages and for both sexes. A low percentage of patients were found to have an obesity-overweight diagnosis in the clinical record (from 3% to 22% at the ages of 2 and 14 years, respectively). The prevalence of overweight-obesity in our population is high, especially among boys. Using Hernández standards leads to an under-estimation of the problem, especially because it detects less overweight patients, thus we recommend using the WHO standards in our daily practice. The low number of overweight-obesity diagnoses in the clinical records might reflect that there is little awareness of the problem by the professionals. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

  13. Genetic Structure of Natural Populations of Escherichia coli in Wild Hosts on Different Continents

    Science.gov (United States)

    Souza, Valeria; Rocha, Martha; Valera, Aldo; Eguiarte, Luis E.

    1999-01-01

    plasmids than did strains isolated from wild mammals. Previous studies have shown that natural populations of E. coli harbor an extensive genetic diversity that is organized in a limited number of clones. However, knowledge of this worldwide bacterium has been limited. Here, we suggest that the strains from a wide range of wild hosts from different regions of the world are organized in an ecotypic structure where adaptation to the host plays an important role in the population structure. PMID:10427022

  14. ASQ-3 scores are sensitive to small differences in age in a Peruvian infant population.

    Science.gov (United States)

    Chong, K C; Zhou, V L; Tarazona, D; Tuesta, H; Velásquez-Hurtado, J E; Sadeghi, R; Llanos, F

    2017-07-01

    The Ages and Stages Questionnaires Edition 3 (ASQ-3) are a well-validated international screen for developmental delays in young children. However, previous studies demonstrate variable scores between children eligible to take the same ASQ-3 interval. This study aimed to determine a relationship between age and ASQ-3 score for each screening interval. This was a baseline exploratory cross-sectional study of infants under 2 years old evaluated for the Peruvian social programme Cuna Más. Participants were included in Cuna Más if they lived in districts with fewer than 2000 inhabitants or 400 homes, indicating a predominantly rural population. The appropriate ASQ-3 screening interval was administered to each subject. Subjects were divided into four 2-week chronological subgroups based on age within each 2-month screening window and aggregated across all 12 screening intervals. Fisher's exact test, analysis of variance and Bonferonni post hoc test were used to compare differences between age subgroups. Linear regression was performed to assess the relationship between ASQ-3 score and both aggregated and disaggregated age subgroup. A total of 5850 Peruvian infants were evaluated in 2013. Mean age was 13 ± 6.6 months, 50.7% were male and mean maternal education was 6.6 ± 4.0 years; 34.8% infants were stunted, 7.8% were underweight, 0.9% were wasted and 2% had age adjusted greater than 35 days for prematurity for ASQ-3 interval assignment. Mean total ASQ-3 was 42.2 ± 8.2. The ASQ-3 allocated 49.6% with suspected delay in one or more developmental areas. Before and after adjusting for wealth quintile, maternal education level, infant nutritional status and prematurity adjustment, age subgroup remained significantly associated with total ASQ-3 score (β = 1.8, CI: 1.7-2.0, P < 0.001), sectional ASQ-3 score (all P < 0.001) and inversely associated with one or more scores indicating suspected developmental delay (P < 0.001). The ASQ-3 may underestimate

  15. Furnance grate monitoring by computer vision; Rosteroevervakning med bildanalys

    Energy Technology Data Exchange (ETDEWEB)

    Blom, Elisabet; Gustafsson, Bengt; Olsson, Magnus

    2005-01-01

    During the last couple of year's computer vision has developed a lot beside computers and video technic. This makes it technical and economical possible to use cameras as a monitoring instrument. The first experiments with this type of equipment were made in the early 1990s. Most of the experiments were made to measure the bed length from the back of the grate. In this experiment the cameras were mounted in the front instead. The highest priority was to detect the topography of the fuel bed. An uneven fuel bed means combustion with local temperature variations that do the combustion more difficult to control. The goal was to show possibilities to measure fuel bed highs, particle size and combustion intensity or the combustion spreading with pictures from one or two cameras. The test was done in a bark-fuelled boiler in Karlsborg because that boiler has doors from the fuel feeding side suitable for looking down on the grate. The results shows that the cameras mounting that were done in Karlsborg were not good enough to do a 3D calculation of the fuel bed. It was however possible to se the drying and it was possible to see the flames in the pictures. To see the flames and steam without over exposure because of different light in different points, it is possible to use a filter or an on linear sensibility camera. To test if a parallel mounting of the two cameras would work a cold test were done in the grate test facility at KMW in Norrtaelje. With the pictures from this test we were able to do 3D measurements of the bed topography. The conclusions are that it is possible to measure bed height and bed topography with other camera positions than we were able to use in this experiment. The particle size is easier to measure before entering the boiler for examples over a rim were the particles falling down. It is also possible to estimate a temperature zone were the steam goes off.

  16. ISSR-PCR: tool for discrimination and genetic structure analysis of Plutella xylostella populations native to different geographical areas.

    Science.gov (United States)

    Roux, O; Gevrey, M; Arvanitakis, L; Gers, C; Bordat, D; Legal, L

    2007-04-01

    The diamondback moth (DBM), Plutella xylostella (L.) is considered as the most destructive pest of Brassicaceae crops world-wide. Its migratory capacities and development of insecticide resistance in many populations leads to more difficulties for population management. To control movement of populations and apparitions of resistance carried by resistant migrant individuals, populations must be identified using genetic markers. Here, seven different ISSR markers have been tested as a tool for population discrimination and genetic variations among 19 DBM populations from Canada, USA, Brazil, Martinique Island, France, Romania, Austria, Uzbekistan, Egypt, Benin, South Africa, Réunion Island, Hong Kong, Laos, Japan and four localities in Australia were assessed. Two classification methods were tested and compared: a common method of genetic distance analyses and a novel method based on an advanced statistical method of the Artificial Neural Networks' family, the Self-Organizing Map (SOM). The 188 loci selected revealed a very high variability between populations with a total polymorphism of 100% and a global coefficient of gene differentiation estimated by the Nei's index (Gst) of 0.238. Nevertheless, the largest part of variability was expressed among individuals within populations (AMOVA: 73.71% and mean polymorphism of 94% within populations). Genetic differentiation among the DBM populations did not reflect geographical distances between them. The two classification methods have given excellent results with less than 1.3% of misclassified individuals. The origin of the high genetic differentiation and efficiency of the two classification methods are discussed.

  17. Application of holographic sub-wavelength diffraction gratings for monitoring of kinetics of bioprocesses

    Science.gov (United States)

    Tamulevičius, Tomas; Šeperys, Rimas; Andrulevičius, Mindaugas; Kopustinskas, Vitoldas; Meškinis, Šarūnas; Tamulevičius, Sigitas; Mikalayeva, Valeryia; Daugelavičius, Rimantas

    2012-09-01

    In this work we present a refractive index (RI) sensor based on a sub-wavelength holographic diffraction grating. The sensor chip was fabricated by dry etching of the finely spaced (d = 428 nm) diffraction grating in SiOx doped diamond like carbon (DLC) film. It is shown that employing a fabricated sensor chip, and using the proposed method of analysis of data, one can inspect kinetics of processes in liquids occurring in the vicinity of the grating surface. The method is based on the spectral composition analysis of polarized polychromatic light reflected from the sub-wavelength diffraction grating. The RI measurement system was tested with different model liquid analytes including 25 wt.%, 50 wt.% sugar water solutions, 10 °C, 50 °C distilled water, also Gram-positive bacteria Bacillus subtilis interaction with ion-permeable channels forming antibiotic gramicidin D and a murolytic enzyme lysozyme. Analysis of the data set of specular reflection spectra enabled us to follow the kinetics of the RI changes in the analyte with millisecond resolution. Detectable changes in the effective RI were not worse than Δn = 10-4.

  18. Gratefulness and subjective well-being: Social connectedness and presence of meaning as mediators.

    Science.gov (United States)

    Liao, Kelly Yu-Hsin; Weng, Chih-Yuan

    2018-04-01

    The association between gratefulness and well-being is well established; however, few studies have examined the mechanisms that underlie this association. The broaden-and-build theory (Fredrickson, 1998, 2001) posits that positive emotions broaden individuals' momentary thought-action repertoires, which serve to build personal resources that can be drawn upon during future stressful encounters. Based on this theory, the current study examined whether gratefulness, a positive emotion, would build social and cognitive resources in terms of social connectedness and presence of meaning in life (i.e., mediators), which subsequently contribute to subjective well-being (SWB). A total of 232 students participated in an online survey at 2 different time points (3 months apart). The mediational hypothesis was tested by latent change score analyses using structural equation modeling techniques. The results showed that changes in gratefulness predicted changes in social connectedness and presence of meaning in life, which, in turn, predicted changes in SWB. The study's findings provided further support for the broaden-and-build theory and suggested that gratefulness is an important positive emotion that contributes to SWB through increased social connectedness and a greater presence of meaning in life. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  19. Salinity measurement in water environment with a long period grating based interferometer

    International Nuclear Information System (INIS)

    Possetti, G R C; Kamikawachi, R C; Muller, M; Fabris, J L; Prevedello, C L

    2009-01-01

    In this work, a comparative study of the behaviour of an in-fibre Mach–Zehnder interferometer for salinity measurement in a water solution is presented. The fibre transducer is composed of two nearly identical long period gratings forming an in-series 7.38 cm long device written in the same fibre optic. Two inorganic and one organic salts (NaCl, KCl, NaCOOH) were characterized within the concentration range from 0 to 150 g L −1 . For the long period grating interferometer, the average obtained sensitivities were −6.61, −5.58 and −3.83 pm/(g L −1 ) for the above salts, respectively, or equivalently −40.8, −46.5 and −39.1 nm RIU −1 . Salinity measured by means of fibre refractometry is compared with measurements obtained using an Abbe refractometer as well as via electrical conductivity. For the long period grating refractometer, the best resolutions attained were 1.30, 1.54 and 2.03 g of salt per litre for NaCl, KCl and NaCOOH, respectively, about two times better than the resolutions obtained by the Abbe refractometer. An average thermal sensitivity of 53 pm °C −1 was measured for the grating transducer immersed in water, indicating the need for the thermal correction of the sensor. Resolutions for the same ionic constituent in different salts are also analysed

  20. Studies on measurement of chloride ion concentration in concrete structures with long-period grating sensors

    Science.gov (United States)

    Tang, Jaw-Luen; Chiang, Tsung-Yu; Chang, Hsiang-Ping; Wang, Jian-Neng

    2006-03-01

    We report the development and demonstration of a simple and low-cost long-period grating (LPG) sensor for chloride ion concentration measurement in concrete structures. The LPG sensor is extremely sensitive to the refractive index of the medium surrounding the cladding surface of the sensing grating, thus allowing it to be used as an ambient index sensor or chemical concentration indicator with high stability and reliability. We have measured chloride ion levels in a concrete sample immersed in salt water solution with different weight concentration ranging from 0 % to 20 %, and results showed that the LPG sensor exhibited a linear decrease in the transmission loss and resonance wavelength shift when the concentration increased. The measurement accuracy for concentration of salt in water solution is estimated to be 0.6 % and the limit of detection for chloride ion is about 0.04 %. To further enhance its sensitivity for chloride concentrations, we have coated gold nanoparticles on the grating surface of the LPG sensor. The sensing mechanism is based on the sensitivity of localized surface plasmon resonance of self-assembled Au colloids on the grating portion of the LPG. With this method, a factor of two increases in sensitivity of detecting chemical solution concentrations was obtained. The advantage of this type of the sensor is relatively simple of construction and ease of use. Moreover, the sensor has the potential capability for on-site, in vivo, and remote sensing, and has the potential use for disposable sensors.

  1. Single- and two-phase flow characterization using optical fiber bragg gratings.

    Science.gov (United States)

    Baroncini, Virgínia H V; Martelli, Cicero; da Silva, Marco José; Morales, Rigoberto E M

    2015-03-17

    Single- and two-phase flow characterization using optical fiber Bragg gratings (FBGs) is presented. The sensor unit consists of the optical fiber Bragg grating positioned transversely to the flow and fixed in the pipe walls. The hydrodynamic pressure applied by the liquid or air/liquid flow to the optical fiber induces deformation that can be detected by the FBG. Given that the applied pressure is directly related to the mass flow, it is possible to establish a relationship using the grating resonance wavelength shift to determine the mass flow when the flow velocity is well known. For two phase flows of air and liquid, there is a significant change in the force applied to the fiber that accounts for the very distinct densities of these substances. As a consequence, the optical fiber deformation and the correspondent grating wavelength shift as a function of the flow will be very different for an air bubble or a liquid slug, allowing their detection as they flow through the pipe. A quasi-distributed sensing tool with 18 sensors evenly spread along the pipe is developed and characterized, making possible the characterization of the flow, as well as the tracking of the bubbles over a large section of the test bed. Results show good agreement with standard measurement methods and open up plenty of opportunities to both laboratory measurement tools and field applications.

  2. Highly reflective Bragg gratings in slightly etched step-index polymer optical fiber.

    Science.gov (United States)

    Hu, Xuehao; Pun, Chi-Fung Jeff; Tam, Hwa-Yaw; Mégret, Patrice; Caucheteur, Christophe

    2014-07-28

    During the past few years, a strong progress has been made in the photo-writing of fiber Bragg gratings (FBGs) in polymer optical fibers (POFs), animated by the constant wish to enhance the grating reflectivity and improve the sensing performances. In this paper, we report the photo-inscription of highly reflective gratings in step-index POFs, obtained thanks to a slight etching of the cladding. We demonstrate that a cladding diameter decrease of ~12% is an ideal trade-off to produce highly reflective gratings with enhanced axial strain sensitivity, while keeping almost intact their mechanical resistance. For this, we make use of Trans-4-stilbenemethanol-doped photosensitive step-index poly(methyl methacrylate) (PMMA) POFs. FBGs are inscribed at ~1550 nm by the scanning phase mask technique in POFs of different external diameters. Reflectivity reaching 97% is achieved for 6 mm long FBGs, compared to 25% for non-etched POFs. We also report that a cladding decrease enhances the FBG axial tension while keeping unchanged temperature and surrounding refractive index sensitivities. Finally and for the first time, a measurement is conducted in transmission with polarized light, showing that a photo-induced birefringence of 7 × 10(-6) is generated (one order of magnitude higher than the intrinsic fiber birefringence), which is similar to the one generated in silica fiber using ultra-violet laser.

  3. Bragg solitons in systems with separated nonuniform Bragg grating and nonlinearity

    Science.gov (United States)

    Ahmed, Tanvir; Atai, Javid

    2017-09-01

    The existence and stability of quiescent Bragg grating solitons are systematically investigated in a dual-core fiber, where one of the cores is uniform and has Kerr nonlinearity while the other one is linear and incorporates a Bragg grating with dispersive reflectivity. Three spectral gaps are identified in the system, in which both lower and upper band gaps overlap with one branch of the continuous spectrum; therefore, these are not genuine band gaps. However, the central band gap is a genuine band gap. Soliton solutions are found in the lower and upper gaps only. It is found that in certain parameter ranges, the solitons develop side lobes. To analyze the side lobes, we have derived exact analytical expressions for the tails of solitons that are in excellent agreement with the numerical solutions. We have analyzed the stability of solitons in the system by means of systematic numerical simulations. We have found vast stable regions in the upper and lower gaps. The effect and interplay of dispersive reflectivity, the group velocity difference, and the grating-induced coupling on the stability of solitons are investigated. A key finding is that a stronger grating-induced coupling coefficient counteracts the stabilization effect of dispersive reflectivity.

  4. Genetic differences among Haplorchis taichui populations in Indochina revealed by mitochondrial COX1 sequences.

    Science.gov (United States)

    Thaenkham, U; Phuphisut, O; Nuamtanong, S; Yoonuan, T; Sa-Nguankiat, S; Vonghachack, Y; Belizario, V Y; Dung, D T; Dekumyoy, P; Waikagul, J

    2017-09-01

    Haplorchis taichui is an intestinal heterophyid fluke that is pathogenic to humans. It is widely distributed in Asia, with a particularly high prevalence in Indochina. Previous work revealed that the lack of gene flow between three distinct populations of Vietnamese H. taichui can be attributed to their geographic isolation with no interconnected river basins. To test the hypothesis that interconnected river basins allow gene flow between otherwise isolated populations of H. taichui, as previously demonstrated for another trematode, Opisthorchis viverrini, we compared the genetic structures of seven populations of H. taichui from various localities in the lower Mekong Basin, in Thailand and Laos, with those in Vietnam, using the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene. To determine the gene flow between these H. taichui populations, we calculated their phylogenetic relationships, genetic distances and haplotype diversity. Each population showed very low nucleotide diversity at this locus. However, high levels of genetic differentiation between the populations indicated very little gene flow. A phylogenetic analysis divided the populations into four clusters that correlated with the country of origin. The negligible gene flow between the Thai and Laos populations, despite sharing the Mekong Basin, caused us to reject our hypothesis. Our data suggest that the distribution of H. taichui populations was incidentally associated with national borders.

  5. 2011 Population Grid for Spain. Methodological assessment of different construction possibilities

    Directory of Open Access Journals (Sweden)

    Francisco J. Goerlich Gisbert

    2017-08-01

    Full Text Available This paper presents an evaluation, from the user point of view, of the regular population grid, with 1 km2 resolution, that the Spanish National Statistical Institute (INE, has released as a product from the last Population and Dwellings Census 2011. This way of disseminating population data is novel, and has a lot of analytical potential uses, since population is no longer linked to administrative divisions. For the first time this information about the population distribution has been generated using a bottom-up approach for the whole of Spain, this is, by georeferencing the population at its place of residence. The availability of another grid at the same spatial resolution, but generated using a top-down approach, this is, by spatial disaggregation methods from administrative population data and other auxiliary land cover information, allow us to explore the benefits associated to georeferencing the population in the context of the methodological changes introduced by the Population and Dwellings Census 2011. At the same time, we are able to evaluate the merits of the census grid .

  6. Polynomial modal analysis of lamellar diffraction gratings in conical mounting.

    Science.gov (United States)

    Randriamihaja, Manjakavola Honore; Granet, Gérard; Edee, Kofi; Raniriharinosy, Karyl

    2016-09-01

    An efficient numerical modal method for modeling a lamellar grating in conical mounting is presented. Within each region of the grating, the electromagnetic field is expanded onto Legendre polynomials, which allows us to enforce in an exact manner the boundary conditions that determine the eigensolutions. Our code is successfully validated by comparison with results obtained with the analytical modal method.

  7. Linear Fresnel Spectrometer Chip with Gradient Line Grating

    Science.gov (United States)

    Choi, Sang Hyouk (Inventor); Park, Yeonjoon (Inventor)

    2015-01-01

    A spectrometer that includes a grating that disperses light via Fresnel diffraction according to wavelength onto a sensing area that coincides with an optical axis plane of the grating. The sensing area detects the dispersed light and measures the light intensity associated with each wavelength of the light. Because the spectrometer utilizes Fresnel diffraction, it can be miniaturized and packaged as an integrated circuit.

  8. Electromagnetically induced two-dimensional grating assisted by incoherent pump

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Yuan; Liu, Zhuan-Zhuan; Wan, Ren-Gang, E-mail: wrg@snnu.edu.cn

    2017-04-25

    We propose a scheme for realizing electromagnetically induced two-dimensional grating in a double-Λ system driven simultaneously by a coherent field and an incoherent pump field. In such an atomic configuration, the absorption is suppressed owing to the incoherent pumping process and the probe can be even amplified, while the refractivity is mainly attributed to the dynamically induced coherence. With the help of a standing-wave pattern coherent field, we obtain periodically modulated refractive index without or with gain, and therefore phase grating or gain-phase grating which diffracts a probe light into high-order direction efficiently can be formed in the medium via appropriate manipulation of the system parameters. The diffraction efficiency attainable by the present gratings can be controlled by tuning the coherent field intensity or the interaction length. Hence, the two-dimensional grating can be utilized as all-optical splitter or router in optical networking and communication. - Highlights: • Two-dimensional grating is coherently induced in four-level atoms. • Phase and gain-phase gratings are obtained assisted by incoherent pump. • The diffraction power is improved due to the enhanced refraction modulation. • The gratings can be utilized as multi-channel all-optical splitter and router.

  9. Discrete dipole approximation simulation of bead enhanced diffraction grating biosensor

    International Nuclear Information System (INIS)

    Arif, Khalid Mahmood

    2016-01-01

    We present the discrete dipole approximation simulation of light scattering from bead enhanced diffraction biosensor and report the effect of bead material, number of beads forming the grating and spatial randomness on the diffraction intensities of 1st and 0th orders. The dipole models of gratings are formed by volume slicing and image processing while the spatial locations of the beads on the substrate surface are randomly computed using discrete probability distribution. The effect of beads reduction on far-field scattering of 632.8 nm incident field, from fully occupied gratings to very coarse gratings, is studied for various bead materials. Our findings give insight into many difficult or experimentally impossible aspects of this genre of biosensors and establish that bead enhanced grating may be used for rapid and precise detection of small amounts of biomolecules. The results of simulations also show excellent qualitative similarities with experimental observations. - Highlights: • DDA was used to study the relationship between the number of beads forming gratings and ratio of first and zeroth order diffraction intensities. • A very flexible modeling program was developed to design complicated objects for DDA. • Material and spatial effects of bead distribution on surfaces were studied. • It has been shown that bead enhanced grating biosensor can be useful for fast detection of small amounts of biomolecules. • Experimental results qualitatively support the simulations and thus open a way to optimize the grating biosensors.

  10. Photoanisotropic polarization gratings beyond the small recording angle regime

    NARCIS (Netherlands)

    Xu, M.; De Boer, D.K.G.; Van Heesch, C.M.; Wachters, A.J.H.; Urbach, H.P.

    2010-01-01

    Polarization gratings can be realized by polarization holographic recording in photoanisotropic materials. In this paper, we study two types of polarization gratings. One is recorded with two orthogonally circularly (OC) polarized beams and the other one with two orthogonally linearly (OL) polarized

  11. Holographic gratings in photorefractive polymers without external electric field

    DEFF Research Database (Denmark)

    Kukhtarev, N.; Lyuksyutov, S.; Buchhave, Preben

    1997-01-01

    Using anomalous large diffusion we report a recording of reflection type gratings in a PVK-based photorefractive polymer without any external electric field. The diffraction efficiency of the gratings was measured to be 7%. An efficient modulation of beams during two-beam coupling up to 12...

  12. Smith-Purcell radiation from concave dotted gratings

    Science.gov (United States)

    Sergeeva, D. Yu.; Tishchenko, A. A.; Aryshev, A. S.; Strikhanov, M. N.

    2018-02-01

    We present the first-principles theory of Smith-Purcell effect from the concave dotted grating consisting of bent chains of separated micro- or nanoparticles. The numerical analysis demonstrates that the obtained spectral-angular distributions change significantly depending on the structure of the grating.

  13. Analysis of the optical parameters of phase holographic gratings

    Directory of Open Access Journals (Sweden)

    Є.О. Тихонов

    2008-03-01

    Full Text Available  Suitability of 2- wave approximation of the coupled waves theory tor description of holographic phase gratings recorded on photopolymer compound ФПК-488 is proved. Using the basic formulas of the theory, main grating optical parameters - a depth of modulation and finished thickness are not measured immediately are determined.

  14. Cholera and shigellosis in Bangladesh: similarities and differences in population dynamics under climate forcing

    Science.gov (United States)

    Pascual, M.; Cash, B.; Reiner, R.; King, A.; Emch, M.; Yunus, M.; Faruque, A. S.

    2012-12-01

    The influence of climate variability on the population dynamics of infectious diseases is considered a large scale, regional, phenomenon, and as such, has been previously addressed for cholera with temporal models that do not incorporate fine-scale spatial structure. In our previous work, evidence for a role of ENSO (El Niño Southern Oscillation) on cholera in Bangladesh was elucidated, and shown to influence the regional climate through precipitation. With a probabilistic spatial model for cholera dynamics in the megacity of Dhaka, we found that the action of climate variability (ENSO and flooding) is localized: there is a climate-sensitive urban core that acts to propagate risk to the rest of the city. Here, we consider long-term surveillance data for shigellosis, another diarrheal disease that coexists with cholera in Bangladesh. We compare the patterns of association with climate variables for these two diseases in a rural setting, as well as the spatial structure in their spatio-temporal dynamics in an urban one. Evidence for similar patterns is presented, and discussed in the context of the differences in the routes of transmission of the two diseases and the proposed role of an environmental reservoir in cholera. The similarities provide evidence for a more general influence of hydrology and of socio-economic factors underlying human susceptibility and sanitary conditions.

  15. Performance of irrigated green corn cultivars in different plant populations at sowing

    Directory of Open Access Journals (Sweden)

    José C. Soares Neto

    Full Text Available ABSTRACT This study aimed to evaluate the yield of green corn hybrids grown under irrigation in different plant populations at sowing. The assay was carried out in the experimental area located in the city of Arapiraca, Alagoas State, Brazil, from November 2015 to January 2016. A randomized complete block design (RCBD was used, in a 2 x 5 factorial scheme with four replicates. A double- and a single-cross hybrid (AG 1051 and BM 3061, which are suitable for green corn production, were cultivated in five spacings between plants at sowing (15.0, 17.5, 20.0, 22.5 and 25.0 cm. The characteristics photosynthetic rate (PR, ear length with rusk (HEL and without husk (UEL, husked ear weight (HEW, unhusked ear weight (UEW, percentage of marketable ears (%ME and weight of husk (HW were evaluated. The double- and single-cross hybrids AG 1051 and BM 3061 showed green ears with commercial standard. The cultivar BM 3061 showed the best results for most of the characteristics related to the performance of green corn (PR, HEL, UEL, UEW, HEW, %ME. The spacing of 17.5 cm between plants at sowing was the most indicated for irrigated green corn cultivation.

  16. Simulation of Population-Based Commuter Exposure to NO2 Using Different Air Pollution Models

    Directory of Open Access Journals (Sweden)

    Martina S. Ragettli

    2014-05-01

    Full Text Available We simulated commuter routes and long-term exposure to traffic-related air pollution during commute in a representative population sample in Basel (Switzerland, and evaluated three air pollution models with different spatial resolution for estimating commute exposures to nitrogen dioxide (NO2 as a marker of long-term exposure to traffic-related air pollution. Our approach includes spatially and temporally resolved data on actual commuter routes, travel modes and three air pollution models. Annual mean NO2 commuter exposures were similar between models. However, we found more within-city and within-subject variability in annual mean (±SD NO2 commuter exposure with a high resolution dispersion model (40 ± 7 µg m−3, range: 21–61 than with a dispersion model with a lower resolution (39 ± 5 µg m−3; range: 24–51, and a land use regression model (41 ± 5 µg m−3; range: 24–54. Highest median cumulative exposures were calculated along motorized transport and bicycle routes, and the lowest for walking. For estimating commuter exposure within a city and being interested also in small-scale variability between roads, a model with a high resolution is recommended. For larger scale epidemiological health assessment studies, models with a coarser spatial resolution are likely sufficient, especially when study areas include suburban and rural areas.

  17. Topological variability and sex differences in fingerprint ridge density in a sample of the Sudanese population.

    Science.gov (United States)

    Ahmed, Altayeb Abdalla; Osman, Samah

    2016-08-01

    Fingerprints are important biometric variables that show manifold utilities in human biology, human morphology, anthropology, and genetics. Their role in forensics as a legally admissible tool of identification is well recognized and is based on their stability following full development, individualistic characteristics, easy classification of their patterns, and uniqueness. Nevertheless, fingerprint ridge density and its variability have not been previously studied in the Sudanese population. Hence, this study was conducted to analyze the topological variability in epidermal ridge density and to assess the possibility of its application in determining sex of Sudanese Arabs. The data used for this study were prints of all 10 fingers of 200 Sudanese Arab individuals (100 men and 100 women) aged between 18 and 28 years. Fingerprint ridge density was assessed for three different areas (radial, ulnar and proximal) for all 10 fingers of each subject. Significant variability was found between the areas (p crime scenes can be useful to determine sex of Sudanese individuals based on fingerprint ridge density; furthermore, ridge density can be considered a morphological trait for individual variation in forensic anthropology. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  18. [Population structure of soil arthropod in different age Pinus massoniana plantations].

    Science.gov (United States)

    Tan, Bo; Wu, Fu-zhong; Yang, Wan-qin; Zhang, Jian; Xu, Zhen-feng; Liu, Yang; Gou, Xiao-lin

    2013-04-01

    An investigation was conducted on the population structure of soil arthropod community in the 3-, 8-, 14-, 31-, and 40-years old Pinus massoniana plantations in the upper reaches of the Yangtze River in spring (May) and autumn (October), 2011, aimed to search for the scientific management of the plantation. A total of 4045 soil arthropods were collected, belonging to 57 families. Both the individual density and the taxonomic group number of the soil arthropod community decreased obviously with increasing soil depth, and this trend increased with increasing stand age. The dominant groups and ordinary groups of the soil arthropod community varied greatly with the stand age of P. massoniana plantation, and a significant difference (Parthropod community, and the similarity index of the soil arthropod community was lower. The individual density, taxonomic group number, and diversity of soil arthropod community were the highest in 8-years old P. massoniana plantation, and then, decreased obviously with increasing stand age. It was suggested that the land fertility of the P. massoniana plantations could be degraded with increasing stand age, and it would be appropriate to make artificial regulation and restoration in 8-years old P. massoniana plantation.

  19. Total phenolic content, radical scavenging properties, and essential oil composition of Origanum species from different populations.

    Science.gov (United States)

    Dambolena, José S; Zunino, María P; Lucini, Enrique I; Olmedo, Rubén; Banchio, Erika; Bima, Paula J; Zygadlo, Julio A

    2010-01-27

    The aim of this work was to compare the antiradical activity, total phenol content (TPC), and essential oil composition of Origanum vulgare spp. virens, Origanum x applii, Origanum x majoricum, and O. vulgare spp. vulgare cultivated in Argentina in different localities. The experiment was conducted in the research station of La Consulta (INTA-Mendoza), the research station of Santa Lucia (INTA-San Juan), and Agronomy Faculty of National University of La Pampa, from 2007 to 2008. The composition of the essential oils of oregano populations was independent of cultivation conditions. In total, 39 compounds were identified in essential oils of oregano from Argentina by means of GC-MS. Thymol and trans-sabinene hydrate were the most prominent compounds, followed by gamma-terpinene, terpinen-4-ol, and alpha-terpinene. O. vulgare vulgare is the only Origanum studied which is rich in gamma-terpinene. Among tested oregano, O. x majoricum showed the highest essential oil content, 3.9 mg g(-1) dry matter. The plant extract of O. x majoricum had greater total phenol content values, 19.36 mg/g dry weight, than the rest of oregano studied. To find relationships among TPC, free radical scavenging activity (FRSA), and climate variables, canonical correlations were calculated. The results obtained allow us to conclude that 70% of the TPC and FRSA variability can be explained by the climate variables (R(2) = 0.70; p = 8.3 x 10(-6)), the temperature being the most important climatic variable.

  20. Magnetoresistance and magnetization in submicron ferromagnetic gratings

    Science.gov (United States)

    Shearwood, C.; Blundell, S. J.; Baird, M. J.; Bland, J. A. C.; Gester, M.; Ahmed, H.; Hughes, H. P.

    1994-05-01

    A technique for engineering micron and submicron scale structures from magnetic films of transition metals has been developed using a combination of electron- and ion-beam lithography enabling high-quality arrays of submicron magnetic Fe wires to be fabricated. This process can be used to fabricate novel devices from a variety of metal combinations which would not be possible by the usual liftoff metallization method. The structure and magnetic properties are reported of an epitaxial 25 nm Fe(001)/GaAs(001) film and the wire gratings which are fabricated from it. The width of the wires in the grating is 0.5 μm for all structures studied, but the separation of each wire is varied in the range 0.5 to 16 μm. An artificially induced shape anisotropy field of around 1 kG, consistent with a magnetostatic calculation, was observed for all separations studied. The field dependence of the magneto-optic Kerr effect and magnetoresistance (MR) data is consistent with a twisted magnetization configuration across the width of the sample beneath saturation for transverse applied fields. In this case, the detailed form of the field dependence of the MR is strikingly modified from that observed in the continuous film and is consistent with coherent rotation of the magnetization.