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Sample records for aberration coma astigmatism

  1. Transmissive liquid-crystal device correcting primary coma aberration and astigmatism in laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2016-03-01

    Laser scanning microscopy allows 3D cross-sectional imaging inside biospecimens. However, certain aberrations produced can degrade the quality of the resulting images. We previously reported a transmissive liquid-crystal device that could compensate for the predominant spherical aberrations during the observations, particularly in deep regions of the samples. The device, inserted between the objective lens and the microscope revolver, improved the image quality of fixed-mouse-brain slices that were observed using two-photon excitation laser scanning microscopy, which was originally degraded by spherical aberration. In this study, we developed a transmissive device that corrects primary coma aberration and astigmatism, motivated by the fact that these asymmetric aberrations can also often considerably deteriorate image quality, even near the sample surface. The device's performance was evaluated by observing fluorescent beads using single-photon excitation laser scanning microscopy. The fluorescence intensity in the image of the bead under a cover slip tilted in the y-direction was increased by 1.5 times after correction by the device. Furthermore, the y- and z-widths of the imaged bead were reduced to 66% and 65%, respectively. On the other hand, for the imaged bead sucked into a glass capillary in the longitudinal x-direction, correction with the device increased the fluorescence intensity by 2.2 times compared to that of the aberrated image. In addition, the x-, y-, and z-widths of the bead image were reduced to 75%, 53%, and 40%, respectively. Our device successfully corrected several asymmetric aberrations to improve the fluorescent signal and spatial resolution, and might be useful for observing various biospecimens.

  2. Optical advantages of astigmatic aberration corrected heliostats

    NASA Astrophysics Data System (ADS)

    van Rooyen, De Wet; Schöttl, Peter; Bern, Gregor; Heimsath, Anna; Nitz, Peter

    2016-05-01

    Astigmatic aberration corrected heliostats adapt their shape in dependence of the incidence angle of the sun on the heliostat. Simulations show that this optical correction leads to a higher concentration ratio at the target and thus in a decrease in required receiver aperture in particular for smaller heliostat fields.

  3. A unique astigmatic nodal property in misaligned Ritchey-Chrétien telescopes with misalignment coma removed.

    PubMed

    Schmid, Tobias; Thompson, Kevin P; Rolland, Jannick P

    2010-03-01

    We present the aberration field response of Ritchey-Chrétien telescopes, with the aperture stop on the primary mirror, to secondary mirror misalignments. More specifically, we derive a general condition for the geometry of the binodal astigmatic aberration field for a telescope that has been aligned to remove field-constant coma. It has been observed that when the coma caused by secondary mirror misalignments is removed the astigmatic field is typically not symmetric around the periphery, but, significantly, it is always effectively zero on-axis. This observation is a manifestation of binodal astigmatism where one of the astigmatic nodes remains near the field center. Here, we show how the condition to remove field-constant coma simultaneously creates a constraint whereby one of the astigmatic nodes must remain effectively on-axis. This result points to why the alignment of a large telescope based on axial imagery is insufficient and demonstrates exactly the geometry of the remaining misalignment aberration field, which dominates the performance of the telescope, providing insights into more complete alignment approaches.

  4. Impact of astigmatism and high-order aberrations on subjective best focus.

    PubMed

    Marcos, Susana; Velasco-Ocana, Miriam; Dorronsoro, Carlos; Sawides, Lucie; Hernandez, Martha; Marin, Gildas

    2015-08-01

    We studied the role of native astigmatism and ocular aberrations on best-focus setting and its shift upon induction of astigmatism in 42 subjects (emmetropes, myopes, hyperopes, with-the-rule [WTR] and against-the-rule [ATR] myopic astigmats). Stimuli were presented in a custom-developed adaptive optics simulator, allowing correction for native aberrations and astigmatism induction (+1 D; 6-mm pupil). Best-focus search consisted on randomized-step interleaved staircase method. Each subject searched best focus for four different images, and four different conditions (with/without aberration correction, with/without astigmatism induction). The presence of aberrations induced a significant shift in subjective best focus (0.4 D; p < 0.01), significantly correlated (p = 0.005) with the best-focus shift predicted from optical simulations. The induction of astigmatism produced a statistically significant shift of the best-focus setting in all groups under natural aberrations (p = 0.001), and in emmetropes and in WTR astigmats under corrected aberrations (p < 0.0001). Best-focus shift upon induced astigmatism was significantly different across groups, both for natural aberrations and AO-correction (p < 0.0001). Best focus shifted in opposite directions in WTR and ATR astigmats upon induction of astigmatism, symmetrically with respect to the best-focus shift in nonastigmatic myopes. The shifts are consistent with a bias towards vertical and horizontal retinal blur in WTR and ATR astigmats, respectively, indicating adaptation to native astigmatism.

  5. Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism

    PubMed Central

    Miller, Joseph M.; Harvey, Erin M.; Schwiegerling, Jim

    2016-01-01

    Purpose To determine whether higher-order aberrations (HOAs) in children from a highly astigmatic population differ from population norms and whether HOAs are associated with astigmatism and reduced best-corrected visual acuity. Methods Subjects were 218 Tohono O’odham Native American children 5–9 years of age. Noncycloplegic HOA measurements were obtained with a handheld Shack-Hartmann sensor (SHS). Signed (z06s to z14s) and unsigned (z06u to z14u) wavefront aberration Zernike coefficients Z(3,−3) to Z(4,4) were rescaled for a 4 mm diameter pupil and compared to adult population norms. Cycloplegic refraction and best-corrected logMAR letter visual acuity (BCVA) were also measured. Regression analyses assessed the contribution of astigmatism (J0) and HOAs to BCVA. Results The mean root-mean-square (RMS) HOA of 0.191 ± 0.072 μm was significantly greater than population norms (0.100 ± 0.044 μm. All unsigned HOA coefficients (z06u to z14u) and all signed coefficients except z09s, z10s, and z11s were significantly larger than population norms. Decreased BCVA was associated with astigmatism (J0) and spherical aberration (z12u) but not RMS coma, with the effect of J0 about 4 times as great as z12u. Conclusions Tohono O’odham children show elevated HOAs compared to population norms. Astigmatism and unsigned spherical aberration are associated with decreased acuity, but the effects of spherical aberration are minimal and not clinically significant. PMID:26239206

  6. Optimum form of posterior chamber intraocular lenses to minimize aberrational astigmatism.

    PubMed

    Takei, K; Hommura, S; Okajima, H

    1995-01-01

    To optically determine the optimum form for a posterior chamber intraocular lens (PC IOL), we calculated the aberrational astigmatism induced by tilt and decentration of the PCIOL using an exact raytracing. First, the position and the radii of curvatures of the IOL were determined to make an emmetropic eye model using a paraxial raytracing. Next, the chief rays originating from the fovea centralis were traced backward through the tilted and/or decentrated PC IOL, the center of the pupil and the cornea, using trigonometric raytracing. Finally, the maximum and minimum aberrational astigmatism were calculated based on the Coddington's Equations for the sagittal and the tangential foci of the ray. All the refractive parameters in Gullstrand's No. 1 schematic eye were adopted. The effect of varying anterior corneal asphericity on the results was also examined. Four forms of polymethylmethacrylate PC IOLs (refractive index: 1.491) were analyzed; a plano-convex IOL with the curved surface facing the cornea, and three bi-convex forms with the ratio of anterior-to-posterior radii of curvatures of 1:4, 1:2 and 1:1, respectively. The 1:4 bi-convex form showed the lowest values for the maximum aberrational astigmatism calculated at every combination of tilt and decentration except 0 degrees tilt and/or 0 mm decentration. The aberrational astigmatism with the 1:4 bi-convex form of PC IOL did not exceed 1.0 D at the maximum tilt and decentration. The variation of anterior corneal asphericity did not influence the results. We conclude that the 1:4 bi-convex form of PC IOL minimizes the postoperative astigmatism induced by tilt and/or decentration of the lens. PMID:8926647

  7. Focal plane internal energy flows of singular beams in astigmatically aberrated low numerical aperture systems.

    PubMed

    Bahl, Monika; Senthilkumaran, P

    2014-09-01

    Singular beams have circulating energy components. When such beams are focused by low numerical aperture systems suffering from astigmatic aberration, these circulating energy components get modified. The phase gradient introduced by this type of aberration splits the higher charge vortices. The dependence of the charge, the aberration coefficient, and the size of the aperture on the nature of the splitting process are reported in this paper. The transverse components of the Poynting vector fields that can be derived from the phase gradient vector field distributions are further decomposed into solenoidal and irrotational components using the Helmholtz-Hodge decomposition method. The solenoidal components relate to the orbital angular momentum of the beams, and the irrotational components are useful in the transport of intensity equations for phase retrieval.

  8. Computation of astigmatic and trefoil figure errors and misalignments for two-mirror telescopes using nodal-aberration theory.

    PubMed

    Ju, Guohao; Yan, Changxiang; Gu, Zhiyuan; Ma, Hongcai

    2016-05-01

    In active optics systems, one concern is how to quantitatively separate the effects of astigmatic and trefoil figure errors and misalignments that couple together in determining the total aberration fields when wavefront measurements are available at only a few field points. In this paper, we first quantitatively describe the impact of mount-induced trefoil deformation on the net aberration fields by proposing a modified theoretical formulation for the field-dependent aberration behavior of freeform surfaces based on the framework of nodal aberration theory. This formulation explicitly expresses the quantitative relationships between the magnitude of freeform surfaces and the induced aberration components where the freeform surfaces can be located away from the aperture stop and decentered from the optical axis. On this basis, and in combination with the mathematical presentation of nodal aberration theory for the effects of misalignments, we present the analytic expressions for the aberration fields of two-mirror telescopes in the presence of astigmatic primary mirror figure errors, mount-induced trefoil deformations on both mirrors, and misalignments. We quantitatively separate these effects using the analytical expressions with wavefront measurements at a few field points and pointing errors. Valuable insights are provided on how to separate these coupled effects in the computation process. Monte Carlo simulations are conducted to demonstrate the correctness and accuracy of the analytic method presented in this paper. PMID:27140345

  9. Computation of astigmatic and trefoil figure errors and misalignments for two-mirror telescopes using nodal-aberration theory.

    PubMed

    Ju, Guohao; Yan, Changxiang; Gu, Zhiyuan; Ma, Hongcai

    2016-05-01

    In active optics systems, one concern is how to quantitatively separate the effects of astigmatic and trefoil figure errors and misalignments that couple together in determining the total aberration fields when wavefront measurements are available at only a few field points. In this paper, we first quantitatively describe the impact of mount-induced trefoil deformation on the net aberration fields by proposing a modified theoretical formulation for the field-dependent aberration behavior of freeform surfaces based on the framework of nodal aberration theory. This formulation explicitly expresses the quantitative relationships between the magnitude of freeform surfaces and the induced aberration components where the freeform surfaces can be located away from the aperture stop and decentered from the optical axis. On this basis, and in combination with the mathematical presentation of nodal aberration theory for the effects of misalignments, we present the analytic expressions for the aberration fields of two-mirror telescopes in the presence of astigmatic primary mirror figure errors, mount-induced trefoil deformations on both mirrors, and misalignments. We quantitatively separate these effects using the analytical expressions with wavefront measurements at a few field points and pointing errors. Valuable insights are provided on how to separate these coupled effects in the computation process. Monte Carlo simulations are conducted to demonstrate the correctness and accuracy of the analytic method presented in this paper.

  10. Coma aberrations in combined two- and three-dimensional STED nanoscopy

    PubMed Central

    Antonello, Jacopo; Kromann, Emil B.; Burke, Daniel; Bewersdorf, Joerg; Booth, Martin J.

    2016-01-01

    Stimulated emission depletion (STED) microscopes, like all super-resolution methods, are sensitive to aberrations. Of particular importance are aberrations that affect the quality of the depletion focus, which requires a point of near-zero intensity surrounded by strong illumination. We present analysis, modeling, and experimental measurements that show the effects of coma aberrations on depletion patterns of two-dimensional (2D) and three-dimensional (3D) STED configurations. Specifically, we find that identical coma aberrations create focal shifts in opposite directions in 2D and 3D STED. This phenomenon could affect the precision of microscopic measurements and has ramifications for the efficacy of combined 2D/3D STED systems. PMID:27472636

  11. Coma aberrations in combined two- and three-dimensional STED nanoscopy.

    PubMed

    Antonello, Jacopo; Kromann, Emil B; Burke, Daniel; Bewersdorf, Joerg; Booth, Martin J

    2016-08-01

    Stimulated emission depletion (STED) microscopes, like all super-resolution methods, are sensitive to aberrations. Of particular importance are aberrations that affect the quality of the depletion focus, which requires a point of near-zero intensity surrounded by strong illumination. We present analysis, modeling, and experimental measurements that show the effects of coma aberrations on depletion patterns of two-dimensional (2D) and three-dimensional (3D) STED configurations. Specifically, we find that identical coma aberrations create focal shifts in opposite directions in 2D and 3D STED. This phenomenon could affect the precision of microscopic measurements and has ramifications for the efficacy of combined 2D/3D STED systems. PMID:27472636

  12. Coma

    MedlinePlus

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  13. Aberration influenced generation of rotating two-lobe light fields

    NASA Astrophysics Data System (ADS)

    Kotova, S. P.; Losevsky, N. N.; Prokopova, D. V.; Samagin, S. A.; Volostnikov, V. G.; Vorontsov, E. N.

    2016-08-01

    The influence of aberrations on light fields with a rotating intensity distribution is considered. Light fields were generated with the phase masks developed using the theory of spiral beam optics. The effects of basic aberrations, such as spherical aberration, astigmatism and coma are studied. The experimental implementation of the fields was achieved with the assistance of a liquid crystal spatial light modulator HOLOEYE HEO-1080P, operating in reflection mode. The results of mathematical modelling and experiments have been qualitatively compared.

  14. Alignment of two mirror astronomical telescopes (the astigmatic component)

    NASA Astrophysics Data System (ADS)

    Schmid, Tobias; Thompson, Kevin; Rolland, Jannick

    2008-07-01

    The effects of alignment perturbations on the aberration fields of two mirror astronomical telescopes are discussed. It is demonstrated that expressions describing alignment induced field-linear astigmatism, published by McLeod based on the work of Schroeder, can be obtained using nodal aberration theory. Rather than merely providing a different derivation for alignment induced astigmatism, it is shown that nodal theory can provide several insights that are significant for the development of effective alignment techniques. In the example of a specific telescope sited on Mt. Hopkins (Ritchey- Chretien), two approaches to identify misalignments of the secondary mirror are demonstrated. One approach utilizes the eccentricity of defocused star images and their orientation angles to calculate the misalignment of the secondary mirror after axial coma is removed. A second approach based on the location of the two zeros of the astigmatic aberration field is then shown to give equivalent results, but at the same time ensuring a complete model of all possible effects of misalignment on the performance of the telescope.

  15. Image transfer with spatial coherence for aberration corrected transmission electron microscopes.

    PubMed

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-08-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field's components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field's derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope.

  16. Corneal primary aberrations compensation by oblique light incidence

    NASA Astrophysics Data System (ADS)

    Espinosa, Julian; Mas, David; Kasprzak, Henryk T.

    2009-07-01

    The eye is not a centered system. The line of sight connects the fovea with the center of the pupil and is usually tilted in the temporal direction. Thus, off-axis optical aberrations, mainly coma and oblique astigmatism, are introduced at the fovea. Tabernero et al. [J. Opt. Soc. Am. A 24(10), 3274-3283 (2007)] showed that a horizontal tilt of the crystalline lens generates a horizontal coma aberration that is compensated by the oblique light incidence on the eye. Here we suggest that corneal astigmatism may also play a role in compensation of oblique aberrations, and we propose a simple model to analyze such a possibility. A theoretical Kooijman eye model with a slight (~0.6 D) with-the-rule astigmatism is analyzed. Light rays at different incidence angles to the optical axis are considered, and the corresponding point spread functions (PSFs) at the retina are calculated. A quality criterion is used to determine the incidence angle that provides the narrowest and highest PSF energy peak. We show that the best image is obtained for a tilted incidence angle compatible with mean values of the angle kappa. This suggests that angle kappa, lens tilt, and corneal astigmatism may combine to provide a passive compensation mechanism to minimize aberrations on the fovea.

  17. The misalignment induced aberrations of TMA telescopes.

    PubMed

    Thompson, Kevin P; Schmid, Tobias; Rolland, Jannick P

    2008-12-01

    The next major space-borne observatory, the James Webb Space Telescope, will be a 6.6M field-biased, obscured, three-mirror anastigmat (TMA). Over the used field of view, the performance of TMA telescopes is dominated by 3(rd) order misalignment aberrations. Here it is shown that two dominant 3(rd) order misalignment aberrations arise for any TMA telescope. One aberration, field constant 3(rd) order coma is a well known misalignment aberration commonly seen in two-mirror Ritchey Chretien telescopes. The second aberration, field-asymmetric, field-linear, 3(rd) order astigmatism is a new and unique image orientation dependence with field derived here for the first time using nodal aberration theory.

  18. Tunable liquid crystal cylindrical micro-optical array for aberration compensation.

    PubMed

    Algorri, J F; Urruchi, V; Bennis, N; Sánchez-Pena, J M; Otón, J M

    2015-06-01

    A tunable aberration compensation device for rectangular micro-optical systems is proposed and demonstrated. This device, which is based in nematic liquid crystal and a micro-electrode structure, forms gradients in the index of refraction as a function of voltage. We have developed a fringe skeletonizing application in order to extract the 3D wavefront from an interference pattern. This software tool obtains the optical aberrations using Chebyshev polynomials. By using phase shifted electrical signals the aberrations can be controlled independently. A complete independent control over the spherical and coma aberration has been demonstrated. Also, an independent control over the astigmatism aberration has been demonstrated in a broad range. This device has promising applications where aberration compensation is required. The independent compensation achieved for some coefficients, such as astigmatism for example, is more than 2.4 waves. PMID:26072760

  19. Aberration measurement from specific photolithographic images: a different approach.

    PubMed

    Nomura, H; Tawarayama, K; Kohno, T

    2000-03-01

    Techniques for measurement of higher-order aberrations of a projection optical system in photolithographic exposure tools have been established. Even-type and odd-type aberrations are independently obtained from printed grating patterns on a wafer by three-beam interference under highly coherent illumination. Even-type aberrations, i.e., spherical aberration and astigmatism, are derived from the best focus positions of vertical, horizontal, and oblique grating patterns by an optical microscope. Odd-type aberrations, i.e., coma and three-foil, are obtained by detection of relative shifts of a fine grating pattern to a large pattern by an overlay inspection tool. Quantitative diagnosis of lens aberrations with a krypton fluoride (KrF) excimer laser scanner is demonstrated.

  20. Aberrations of a facet-type transmission grating for cosmic x-ray and XUV spectroscopy.

    PubMed

    Beuermann, K P; Bräuninger, H; Trümper, J

    1978-08-01

    The aberrations of various types of curved constant-period transmission gratings are discussed, using Fermat's principle. We show that optimal performance is achieved with a grating assembled from individual facets which form a nonclosed surface. For this geometry, primary coma and astigmatism are proportional to the facet size and, hence, may be adapted to the angular resolution of a Wolter-type telescope. PMID:20203778

  1. Analysis of nodal aberration properties in off-axis freeform system design.

    PubMed

    Shi, Haodong; Jiang, Huilin; Zhang, Xin; Wang, Chao; Liu, Tao

    2016-08-20

    Freeform surfaces have the advantage of balancing off-axis aberration. In this paper, based on the framework of nodal aberration theory (NAT) applied to the coaxial system, the third-order astigmatism and coma wave aberration expressions of an off-axis system with Zernike polynomial surfaces are derived. The relationship between the off-axis and surface shape acting on the nodal distributions is revealed. The nodal aberration properties of the off-axis freeform system are analyzed and validated by using full-field displays (FFDs). It has been demonstrated that adding Zernike terms, up to nine, to the off-axis system modifies the nodal locations, but the field dependence of the third-order aberration does not change. On this basis, an off-axis two-mirror freeform system with 500 mm effective focal length (EFL) and 300 mm entrance pupil diameter (EPD) working in long-wave infrared is designed. The field constant aberrations induced by surface tilting are corrected by selecting specific Zernike terms. The design results show that the nodes of third-order astigmatism and coma move back into the field of view (FOV). The modulation transfer function (MTF) curves are above 0.4 at 20 line pairs per millimeter (lp/mm) which meets the infrared reconnaissance requirement. This work provides essential insight and guidance for aberration correction in off-axis freeform system design. PMID:27557003

  2. Analysis of nodal aberration properties in off-axis freeform system design.

    PubMed

    Shi, Haodong; Jiang, Huilin; Zhang, Xin; Wang, Chao; Liu, Tao

    2016-08-20

    Freeform surfaces have the advantage of balancing off-axis aberration. In this paper, based on the framework of nodal aberration theory (NAT) applied to the coaxial system, the third-order astigmatism and coma wave aberration expressions of an off-axis system with Zernike polynomial surfaces are derived. The relationship between the off-axis and surface shape acting on the nodal distributions is revealed. The nodal aberration properties of the off-axis freeform system are analyzed and validated by using full-field displays (FFDs). It has been demonstrated that adding Zernike terms, up to nine, to the off-axis system modifies the nodal locations, but the field dependence of the third-order aberration does not change. On this basis, an off-axis two-mirror freeform system with 500 mm effective focal length (EFL) and 300 mm entrance pupil diameter (EPD) working in long-wave infrared is designed. The field constant aberrations induced by surface tilting are corrected by selecting specific Zernike terms. The design results show that the nodes of third-order astigmatism and coma move back into the field of view (FOV). The modulation transfer function (MTF) curves are above 0.4 at 20 line pairs per millimeter (lp/mm) which meets the infrared reconnaissance requirement. This work provides essential insight and guidance for aberration correction in off-axis freeform system design.

  3. Development of optical design algorithms on the base of the exact (all orders) geometrical aberration theory

    NASA Astrophysics Data System (ADS)

    Hristov, Boian A.

    2011-10-01

    The process of optical design today is both an art and a science mainly due to the lack of exact and suitable aberration theory. In this paper we propose an exact (without any approximations) analytical aberration theory. It describes exactly the relations between the on-axis image aberrations and on-axis object aberrations via so called relative parameters, real aperture incidence angles, real aperture slope angles, refraction indexes and object distance. The image field aberrations (distortion, astigmatism, tangential curvature, sagittal curvature and field curvature) are described in a mathematically exact way by means of relative parameters, real incidence angles and slope angles of the chief rays, refraction indexes, object distance and corresponding object aberrations. For the image tangential coma and image sagittal coma we propose differential formulae. To verify the correction of every single aberration we use the commercial program OSLO. The differences between our and OSLO results for each aberration (except for the tangential and sagittal coma) are less than 1x10-8 mm. In addition we propose some exact aberration's correction algorithms for a very distant object and variety of constructive design solutions which confirm the truth of the proposed theory.

  4. Influence of aberrations in microholographic recording

    NASA Astrophysics Data System (ADS)

    Katayama, Ryuichi

    2015-11-01

    The influence of various types of aberrations (spherical, coma, and astigmatic) of recording and readout beams on the readout signal in a microholographic recording was investigated through a numerical simulation. The simulation conditions were that the wavelength of the laser was 405 nm and the numerical aperture of the objective lenses was 0.85. The tolerance of the root-mean-square (RMS) wavefront aberrations was defined as the aberration when the normalized signal level decreased to 0.8. Among the three types of aberrations, the influence of the spherical aberration was the most significant. When both the recording and readout beams were aberrated and the signs of the aberrations were in the worst case, the tolerance of the RMS wavefront aberrations was less than half of the Maréchal's criterion. Moreover, when the RMS wavefront aberrations of the recording and readout beams were within the above tolerance, the bit intervals of 0.13 and 0.65 μm in the inplane and vertical directions, respectively, which correspond to the recording density of 91 bit/μm3 (recording capacity of 16 TB for a 120-mm-diameter optical disk having a 300-μm-thick recording layer), were shown to be feasible for confocal detection with an allowable signal-to-noise ratio.

  5. Analytical expressions for field astigmatism in decentered two mirror telescopes and application to the collimation of the ESO VLT

    NASA Astrophysics Data System (ADS)

    Noethe, L.; Guisard, S.

    2000-05-01

    We derive formulae for all parameters defining the field astigmatism of misaligned two mirror telescopes with arbitrary geometries and with stop positions anywhere on the line connecting the vertices of the two mirrors. The formulae show explicitly the dependence of the field astigmatism on the fundamental design parameters and characteristics of the telescope and on the stop position. Special attention is given to the particular case where such a schiefspiegler has been corrected for coma at the field center. In addition, we study the effects of the practical definition that the center of the field is the center of the adapter. Following a recent paper by McLeod, where the field dependence of astigmatism is used to collimate a Ritchey-Chretien telescope with the stop at the primary mirror, we apply our formulae to the Cassegrain focus of the ESO Very Large Telescope (VLT), where the stop is at the secondary mirror and the telescope is only corrected for spherical aberration. We present measurements of the field astigmatism and discuss the accuracy of the collimation method.

  6. A first-order treatment of aberrations in Cassegrainian and Gregorian antennas

    NASA Astrophysics Data System (ADS)

    Dragone, C.

    1982-05-01

    The decrease in aperture efficiency caused by small aberrations in a reflector antenna is determined. The important case of a Cassegrainian (or Gregorian) antenna with a feed placed in the vicinity of the focal point is treated in detail. For this case the various aberration components due to astigmatism, coma, etc., are derived explicitly, their effect on aperture efficiency is shown, and the conditions that optimize performance are given. The results are useful for the design of multibeam antennas in ground stations and satellites.

  7. [Wave front aberrations -- practical conclusions in eye with Restor 3+ difractive multifocal lens].

    PubMed

    Staicu, Corina; Moraru, Ozana; Moraru, Cristian

    2014-01-01

    Implantation of multifocal intraocular lenses has become a rutine nowadays, but achieving good visual results requires a perfect intraoperative technique and also an adequate preoperative selection of the patients. We analysed the wave front aberrations (spherical aberations, coma and astigmatism) in the eyes implanted with ReStor + 3 IOL, and we realized some clinical correlations of these aberations with the pupil diameter in scotopic and fotopic conditions, kappa angle, IOL centration, residual refraction errors postoperatively. Taking into account the causes of postoperative high order aberration will allow the surgeon to make a good selection of the patiens and to a higher degree of satisfaction of both sides.

  8. [Wave front aberrations -- practical conclusions in eye with Restor 3+ difractive multifocal lens].

    PubMed

    Staicu, Corina; Moraru, Ozana; Moraru, Cristian

    2014-01-01

    Implantation of multifocal intraocular lenses has become a rutine nowadays, but achieving good visual results requires a perfect intraoperative technique and also an adequate preoperative selection of the patients. We analysed the wave front aberrations (spherical aberations, coma and astigmatism) in the eyes implanted with ReStor + 3 IOL, and we realized some clinical correlations of these aberations with the pupil diameter in scotopic and fotopic conditions, kappa angle, IOL centration, residual refraction errors postoperatively. Taking into account the causes of postoperative high order aberration will allow the surgeon to make a good selection of the patiens and to a higher degree of satisfaction of both sides. PMID:25300127

  9. Geometrical theory of aberrations near the axis in classical off-axis reflecting telescopes.

    PubMed

    Chang, Seunghyuk; Prata, Aluizio

    2005-11-01

    A geometrical theory of aberrations for the vicinity of the focus of arbitrary off-axis sections of conic mirrors is derived. It is shown that an off-axis conic mirror introduces linear astigmatism in the image. However, in classical two-mirror telescopes this aberration can be eliminated by tilting the secondary parent mirror axis. It is also shown that the practical geometrical-optics performance of a classical off-axis two-mirror telescope with no linear astigmatism is equivalent to the performance of an on-axis system, proving that both systems have identical third-order coma. To demonstrate the applicability of the theory developed in a practical system, a fast (i.e., f/2), compact, obstruction-free classical off-axis Cassegrain telescope is designed.

  10. Astigmatism in cataract surgery.

    PubMed Central

    Luntz, M. H.; Livingston, D. G.

    1977-01-01

    We report on our investigation into astigmatism in 40 eyes following a corneal cataract incision closed with a continuous 10/0 nylon monofilament suture (Ethilon). Immediately after surgery there was astigmatism caused by the nylon suture (suture-induced astigmatism), its severity depending on the tightness of the suture. It ranged from 1 to 10-5 dioptres, the mean value 4-09 dioptres with a standard deviation of +/-2-5. Removing the nylon suture eliminated this astigmatism and within a few weeks the corneal astigmatism correction in 48% of eyes returned to the preoperative level. In 80% of eyes the difference between the final postoperative corneal astigmatism (4 months after removing the continuous suture) and the preoperative astigmatism was 0-75 dioptres or less and the maximum change was 1-5 dioptres. In 40% of eyes the axis of the cylinder changed from a horizontal to an oblique axis but did not change from a with- to against-the-rule axis. The degree of astigmatism remained constant while the suture was in place and in 50% of eyes was equal to or less than 3 dioptres. The mean of the spherical equivalents was 11-31 dioptres with a standard deviation of +/-1-25. A spectacle correction 14 days after operation prescribed either as the mean spherical equivalent (11-50 dioptres) or according to the patient's refraction will give satisfactory vision until the suture is removed 4 months after operation. The degree of astigmatism following a corneal section and continuous nylon suture compares very favourably with astigmatism following other suturing techniques for cataract. Images PMID:326304

  11. Improved astigmatic focus error detection method

    NASA Technical Reports Server (NTRS)

    Bernacki, Bruce E.

    1992-01-01

    All easy-to-implement focus- and track-error detection methods presently used in magneto-optical (MO) disk drives using pre-grooved media suffer from a side effect known as feedthrough. Feedthrough is the unwanted focus error signal (FES) produced when the optical head is seeking a new track, and light refracted from the pre-grooved disk produces an erroneous FES. Some focus and track-error detection methods are more resistant to feedthrough, but tend to be complicated and/or difficult to keep in alignment as a result of environmental insults. The astigmatic focus/push-pull tracking method is an elegant, easy-to-align focus- and track-error detection method. Unfortunately, it is also highly susceptible to feedthrough when astigmatism is present, with the worst effects caused by astigmatism oriented such that the tangential and sagittal foci are at 45 deg to the track direction. This disclosure outlines a method to nearly completely eliminate the worst-case form of feedthrough due to astigmatism oriented 45 deg to the track direction. Feedthrough due to other primary aberrations is not improved, but performance is identical to the unimproved astigmatic method.

  12. Tubular astigmatism-tunable fluidic lens.

    PubMed

    Kopp, Daniel; Zappe, Hans

    2016-06-15

    We demonstrate a new means to fabricate three-dimensional liquid lenses which may be tuned in focal length and astigmatism. Using actuation by electrowetting-on-dielectrics, astigmatism in arbitrary directions may be tuned independently, with almost no cross talk between orthogonal orientations. The lens is based on electrodes structured on planar polyimide foils and subsequently rolled, enabling high-resolution patterning of complex electrodes along the azimuthal and radial directions of the lens. Based on a design established through fluidic and optical simulations, the astigmatism tuning is experimentally verified by a change of the corresponding Zernike coefficients measured using a Shack-Hartmann wavefront sensor. It was seen that the back focal length can be tuned by 5 mm and 0° and 45° astigmatism by 3 μm through application of voltages in the range of 50  Vrms. It was observed that the cross talk with other aberrations is very low, suggesting a novel means for astigmatism control in imaging systems.

  13. Using aberration test patterns to optimize the performance of EUV aerial imaging microscopes

    SciTech Connect

    Mochi, Iacopo; Goldberg, Kenneth A.; Miyakawa, Ryan; Naulleau, Patrick; Han, Hak-Seung; Huh, Sungmin

    2009-06-16

    The SEMATECH Berkeley Actinic Inspection Tool (AIT) is a prototype EUV-wavelength zoneplate microscope that provides high quality aerial image measurements of EUV reticles. To simplify and improve the alignment procedure we have created and tested arrays of aberration-sensitive patterns on EUV reticles and we have compared their images collected with the AIT to the expected shapes obtained by simulating the theoretical wavefront of the system. We obtained a consistent measure of coma and astigmatism in the center of the field of view using two different patterns, revealing a misalignment condition in the optics.

  14. Different aberrations raise contrast thresholds for single-letter identification in line with their effect on cross-correlation-based confusability.

    PubMed

    Young, Laura K; Love, Gordon D; Smithson, Hannah E

    2013-01-01

    We previously showed that different types of aberration defocus, coma, and secondary astigmatism affect reading performance via different mechanisms. In this paper, we show the contrary result that, for identification of isolated letters, the effects of rendering different types of aberration can be described by a single cross-correlation-based metric. Aberrations reduce the effective resolution of an optical system, quantified by the high-frequency fall-off of the modulation transfer function. They additionally cause spatial-frequency-dependent phase and contrast changes, which have a size-dependent effect on letter forms. We used contrast threshold as our performance measure, instead of distance acuity, to separate the effects of form alterations from those of resolution limits. This measure is additionally appropriate in comparing single-letter-based performance to reading at a fixed distance. The relationship between a cross-correlation-based measure of letter confusability and performance was the same for all three types of aberration. For reading, we had found a different relationship for coma than for defocus and secondary astigmatism. We conclude that even when two tasks--letter identification and reading--use the same component stimulus set, the combination of multiple letters in a reading task produces functional differences between the effects of these aberrations that are not present for isolated letters. PMID:23788460

  15. Astigmatism following cataract surgery.

    PubMed

    Reading, V M

    1984-02-01

    The changes in corneal curvature were determined at regular intervals over a one-year period following intracapsular cataract extraction by microsurgical techniques. During the first postoperative month photokeratometric measurements showed rapid changes in astigmatism associated with large changes in the direction of the axis. Thereafter astigmatism against-the-rule predominated. Data from the small group of patients who underwent surgery in which the technique of phacoemulsification was used show that the smaller changes in corneal curvature are attributable to the smaller incision size and reduced number of sutures. With patients who underwent intracapsular extraction a comparison has been made between the effects of large and small section sizes, and a procedure is outlined whereby surgically induced astigmatism may be minimised.

  16. Astigmatism and diagnostic procedures.

    PubMed

    Visnjić, Mirna Belovari; Zrinsćak, Ognjen; Barisić, Freja; Iveković, Renata; Laus, Katia Novak; Mandić, Zdravko

    2012-06-01

    Astigmatism represents an inability of the cornea and lens to provide a sharp image onto the retina. Correcting astigmatic errors, whether congenital, contact lens induced or surgically induced, is now an integral part of modern cataract and refractive procedures. Development of modern technology has enabled accurate diagnosis and perfect opportunities for correction; however, while cataract and keratorefractive surgery have come a long way in the last decade, the treatment and diagnosis of astigmatism continue to challenge ophthalmologists. There are several diagnostic procedures and tools available today, some standard and some contemporary that include keratometry, corneal topography, apparatus using wavefront or Scheimpflug analysis like Orbscan, Pentacam, Wavescan, etc. With the introduction of several new diagnostic tools, measurements of astigmatism have become less of an issue, but in some cases it is still difficult to obtain consistent results. What remains still unanswered is the question of the best diagnostic tool on the market. Further research is needed to evaluate both tools as well as their clinical application for optimal use. PMID:23115957

  17. Misalignment-induced nodal aberration fields in two-mirror astronomical telescopes.

    PubMed

    Schmid, Tobias; Thompson, Kevin P; Rolland, Jannick P

    2010-06-01

    We present the effects of misalignments on the field dependence of the third-order aberration fields of traditional, two-mirror astronomical telescopes in the context of nodal aberration theory, which we believe is the most general and extensible framework for describing and improving on-station performance. While many of the advantages of nodal aberration theory, compared to other, often power series expansion-based descriptions of misalignment effects on aberrations, become particularly important when analyzing telescopes with more than two mirrors, or in the presence of figure errors; this paper aims to provide and demonstrate the fundamental concepts needed to fully describe the state of correction of misaligned two-mirror telescopes. Importantly, it is shown that the assumption that perfect performance on axis ensures a fully aligned telescope is false, and we demonstrate that if Ritchey-Chrétien telescopes are aligned for zero coma on axis as the sole criterion, formidable misalignments will likely remain, leading to image quality degradation, particularly beyond midfield caused by astigmatism with binodal field dependence (i.e., astigmatism goes to zero at two points in the field).

  18. Infant astigmatism and meridional amblyopia.

    PubMed

    Gwiazda, J; Mohindra, I; Brill, S; Held, R

    1985-01-01

    The orientation preferences of 70 infants aged 7 to 53 weeks with significant astigmatism [1.0 or more diopters (D)] were measured using a preferential looking procedure with paired gratings. The preference data show the consequences of the blurring effects of astigmatism when these are not compensatable by accommodation. Data from infant astigmats tested with optical correction look like those of nonastigmats. We have found no evidence for the development of meridional amblyopia during the first year of life. PMID:4072007

  19. Eye aberration analysis with Zernike polynomials

    NASA Astrophysics Data System (ADS)

    Molebny, Vasyl V.; Chyzh, Igor H.; Sokurenko, Vyacheslav M.; Pallikaris, Ioannis G.; Naoumidis, Leonidas P.

    1998-06-01

    New horizons for accurate photorefractive sight correction, afforded by novel flying spot technologies, require adequate measurements of photorefractive properties of an eye. Proposed techniques of eye refraction mapping present results of measurements for finite number of points of eye aperture, requiring to approximate these data by 3D surface. A technique of wave front approximation with Zernike polynomials is described, using optimization of the number of polynomial coefficients. Criterion of optimization is the nearest proximity of the resulted continuous surface to the values calculated for given discrete points. Methodology includes statistical evaluation of minimal root mean square deviation (RMSD) of transverse aberrations, in particular, varying consecutively the values of maximal coefficient indices of Zernike polynomials, recalculating the coefficients, and computing the value of RMSD. Optimization is finished at minimal value of RMSD. Formulas are given for computing ametropia, size of the spot of light on retina, caused by spherical aberration, coma, and astigmatism. Results are illustrated by experimental data, that could be of interest for other applications, where detailed evaluation of eye parameters is needed.

  20. Amblyopia in Astigmatic Infants and Toddlers

    PubMed Central

    Dobson, Velma; Harvey, Erin M.; Clifford-Donaldson, Candice E.; Green, Tina K.; Miller, Joseph M.

    2010-01-01

    Purpose To determine if reduced astigmatism-corrected acuity for vertical (V) and/or horizontal (H) gratings and/or meridional amblyopia (MA) are present prior to age three years in children who have with-the-rule astigmatism. Methods Subjects were 448 children, 6 months through 2 years of age with no known ocular abnormalities other than with-the-rule astigmatism, who were recruited through Women, Infants and Children clinics on the Tohono O’odham reservation. Children were classified as non-astigmats (≤ 2.00 D) or astigmats (> 2.00 D) based on right eye (RE) non-cycloplegic autorefraction measurements (Welch Allyn SureSight). RE astigmatism-corrected grating acuity for V and H stimuli was measured using the Teller Acuity Card procedure while children wore cross-cylinder lenses to correct their astigmatism or plano lenses if they had no astigmatism. Results Astigmatism-corrected acuity for both V and H gratings was significantly poorer in the astigmats than in the non-astigmats, and the reduction in acuity for astigmats was present for children in all three age groups examined (6 months to <1 year, 1 to <2 years, 2 to <3 years). There was no significant difference in V-H grating acuity (no evidence of MA) for the astigmatic group as a whole, or when data were analyzed for each age group. Conclusions Even in the youngest age group, astigmats tested with astigmatism correction showed reduced acuity for both V and H gratings, which suggests that astigmatism is having a negative influence on visual development. We found no evidence of orientation-related differences in astigmatism-corrected grating acuity, indicating either that MA does not develop prior to age 3 years, or that most of the astigmatic children had a type of astigmatism, i.e., hyperopic, that has proven to be less likely than myopic or mixed astigmatism to result in MA. PMID:20351602

  1. Characterisation of the effects of optical aberrations in single molecule techniques.

    PubMed

    Coles, Benjamin C; Webb, Stephen E D; Schwartz, Noah; Rolfe, Daniel J; Martin-Fernandez, Marisa; Lo Schiavo, Valentina

    2016-05-01

    Optical aberrations degrade image quality in fluorescence microscopy, including for single-molecule based techniques. These depend on post-processing to localize individual molecules in an image series. Using simulated data, we show the impact of optical aberrations on localization success, accuracy and precision. The peak intensity and the proportion of successful localizations strongly reduces when the aberration strength is greater than 1.0 rad RMS, while the precision of each of those localisations is halved. The number of false-positive localisations exceeded 10% of the number of true-positive localisations at an aberration strength of only ~0.6 rad RMS when using the ThunderSTORM package, but at greater than 1.0 rad RMS with the Radial Symmetry package. In the presence of coma, the localization error reaches 100 nm at ~0.6 rad RMS of aberration strength. The impact of noise and of astigmatism for axial resolution are also considered. Understanding the effect of aberrations is crucial when deciding whether the addition of adaptive optics to a single-molecule microscope could significantly increase the information obtainable from an image series. PMID:27231619

  2. Characterisation of the effects of optical aberrations in single molecule techniques.

    PubMed

    Coles, Benjamin C; Webb, Stephen E D; Schwartz, Noah; Rolfe, Daniel J; Martin-Fernandez, Marisa; Lo Schiavo, Valentina

    2016-05-01

    Optical aberrations degrade image quality in fluorescence microscopy, including for single-molecule based techniques. These depend on post-processing to localize individual molecules in an image series. Using simulated data, we show the impact of optical aberrations on localization success, accuracy and precision. The peak intensity and the proportion of successful localizations strongly reduces when the aberration strength is greater than 1.0 rad RMS, while the precision of each of those localisations is halved. The number of false-positive localisations exceeded 10% of the number of true-positive localisations at an aberration strength of only ~0.6 rad RMS when using the ThunderSTORM package, but at greater than 1.0 rad RMS with the Radial Symmetry package. In the presence of coma, the localization error reaches 100 nm at ~0.6 rad RMS of aberration strength. The impact of noise and of astigmatism for axial resolution are also considered. Understanding the effect of aberrations is crucial when deciding whether the addition of adaptive optics to a single-molecule microscope could significantly increase the information obtainable from an image series.

  3. Characterisation of the effects of optical aberrations in single molecule techniques

    PubMed Central

    Coles, Benjamin C.; Webb, Stephen E. D.; Schwartz, Noah; Rolfe, Daniel J.; Martin-Fernandez, Marisa; Lo Schiavo, Valentina

    2016-01-01

    Optical aberrations degrade image quality in fluorescence microscopy, including for single-molecule based techniques. These depend on post-processing to localize individual molecules in an image series. Using simulated data, we show the impact of optical aberrations on localization success, accuracy and precision. The peak intensity and the proportion of successful localizations strongly reduces when the aberration strength is greater than 1.0 rad RMS, while the precision of each of those localisations is halved. The number of false-positive localisations exceeded 10% of the number of true-positive localisations at an aberration strength of only ~0.6 rad RMS when using the ThunderSTORM package, but at greater than 1.0 rad RMS with the Radial Symmetry package. In the presence of coma, the localization error reaches 100 nm at ~0.6 rad RMS of aberration strength. The impact of noise and of astigmatism for axial resolution are also considered. Understanding the effect of aberrations is crucial when deciding whether the addition of adaptive optics to a single-molecule microscope could significantly increase the information obtainable from an image series. PMID:27231619

  4. Higher-Order Aberrations when wearing Sphere and Toric Soft Contact Lenses

    PubMed Central

    Berntsen, David A.; Merchea, Mohinder M.; Richdale, Kathryn; Mack, Carla J.; Barr, Joseph T.

    2009-01-01

    Purpose To determine the on-eye effect of spherical and toric contact lens design on higher-order aberrations (HOA). Methods Thirty eyes (15 subjects) entered a masked, randomized, cross-over study. Each eye was fitted with the spherical and toric lens of the following brands in random order: Acuvue Advance, Biomedics 55, Frequency 55, and SofLens 66. HOAs were measured using the Zywave II Aberrometer over a 6-mm aperture up to fifth order. A linear model accounting for the fixed effect of lens type and random effects of subject and eye was created. Paired t-tests were completed between lens brands within the spherical and toric lenses and between the spherical and toric lens within each brand. Best-corrected visual acuity (VA) was measured and compared. Results No clinically meaningful differences in total HOAs were found between brands or between the spherical and toric lens within a brand. Positive spherical aberration (SA) was reduced by all spherical and toric lenses compared to wearing no lens by 0.07 to 0.23 μm (p<0.0001). Frequency toric induced the greatest change in SA. The thin-zone design lens (Acuvue Advance for Astigmatism) had a statistically different amount of vertical coma (−0.04 μm) than the three prism-balast toric lenses (0.11 to 0.23 μm; p<0.0001). SofLens toric had the greatest amount of vertical coma, but better VA than Acuvue Advance for Astigmatism and Frequency toric. With the exception of Acuvue Advance for Astigmatism, toric lenses had greater absolute magnitude of vertical coma than their sphere counterparts (all p<0.002). No other significant HOA differences were observed. Conclusions Toric contact lenses with prism-ballast designs demonstrated more vertical coma, but better VA. Positive SA was reduced by spherical and toric contact lenses. The visual quality effect of lens design and material on induced HOAs warrants further investigation. PMID:19156015

  5. Coma full-field display for freeform imaging systems

    NASA Astrophysics Data System (ADS)

    Bauer, Aaron; Thompson, Kevin P.; Rolland, Jannick P.

    2015-10-01

    With the recent advances in optical fabrication technology, the manufacturing of freeform optical surfaces is no longer prohibitive. To spur the development of freeform systems, however, optical designers must be given the necessary tools to efficiently design, analyze, and tolerance these systems. The process for designing freeform imaging systems is enhanced by the knowledge of the individual aberration contributions across the full field-of-view. As shown in the recent aberration theory for freeform surfaces, identifying the field dependence of the dominant aberrations is critical for a controlled freeform optimization. Coma, an often system-limiting aberration and an aberration that has recently been directly addressed with freeform surfaces, is of specific interest. Currently, a coma full-field display (FFD) of a system can be generated in commercial ray-tracing software by fitting the wavefront at the exit pupil with Zernike polynomials, but this process can involve tracing thousands of rays. Moreover, the circular coma FFDs are inherently separate from the elliptical coma FFDs. In this research, we use nodal aberration theory to develop a method to generate a coma FFD that requires only a few (less than 10) rays per field point to be traced through the optical system. Both the magnitude and orientation of the coma aberrations at the image plane are shown in our FFDs, including the effects of elliptical coma. These coma FFDs save computation time during the design and offer valuable insight to the designer. Examples of the plots will be shown for multiple freeform optical systems.

  6. The Visual Impact of Zernike and Seidel Forms of Monochromatic Aberrations

    PubMed Central

    Cheng, Xu; Bradley, Arthur; Ravikumar, Sowmya; Thibos, Larry N.

    2010-01-01

    Purpose To examine the impact on visual acuity of different aberrations modes (e.g. coma, astigmatism, spherical aberration (SA)) and different aberration basis functions (Zernike or Seidel). Methods Computational optics was used to generate retinal images degraded by either the Zernike or Seidel forms of 2nd through 4th order aberrations for an eye with a 5mm pupil diameter. High contrast, photopic visual acuity was measured using method of constant stimuli for letters displayed on a computer-controlled, linearized, quasi-monochromatic (λ=556 nm) display. Results Minimum angle of resolution (MAR) varied linearly with the magnitude (root mean square error, RMS) of all modes of aberration. The impact of individual Zernike lower and higher order aberrations (HOAs) varied significantly with mode, e.g. arc minutes of MAR/micron of RMS slopes varied from 7 (spherical defocus) to 0.5 (quadrafoil). Seidel forms of these aberrations always had a smaller visual impact. Notably, Seidel spherical aberration (SA) had 1/17th the impact of Zernike SA with the same wavefront variance, and about 1/4th the impact of Zernike SA with matching levels of r4 wavefront error. With lower order components removed, HOAs near the center of the Zernike pyramid do not have a large visual impact. Conclusions The majority of the visual impact of high levels of 4th order Zernike aberrations can be attributed to the 2nd order terms within these polynomials. Therefore, the impact of SA can be minimized by balancing it with a defocus term that flattens the central wavefront (paraxial focus) or maximizes the area of the pupil with a flat wavefront. Over this wide range of aberration types and levels, image quality metrics based upon the PSF and OTF can predict VA as reliably as VA measures can predict retests of VA, and thus such metrics may become valuable predictors of both VA and, via optimization, refractions. PMID:20351600

  7. Low-cost adaptive astigmatism compensator for improvement of eye fundus camera.

    PubMed

    Arines, Justo; Acosta, Eva

    2011-11-01

    In this work we show a conceptually simple and cheap means by which to improve retinal image quality in fundus cameras. We will explain how to build a low-cost variable astigmatism-correcting device with a pair of identical commercial ophthalmic lenses. We have developed and tested a low order aberration compensation device capable of correcting astigmatism prescriptions up to -8.00 D with no significant addition of higher order aberrations. A theoretical description of the device, calibration, and improvement in retinal images without employing any image restoration technique will be shown. PMID:22048352

  8. Myxedema coma.

    PubMed

    Wartofsky, Leonard

    2006-12-01

    Myxedema coma is the term given to the most severe presentation of profound hypothyroidism and is often fatal in spite of therapy. Decompensation of the hypothyroid patient into a coma may be precipitated by a number of drugs, systemic illnesses (eg, pneumonia), and other causes. It typically presents in older women in the winter months and is associated with signs of hypothyroidism, hypothermia, hyponatremia, hypercarbia, and hypoxemia. Treatment must be initiated promptly in an intensive care unit setting. Although thyroid hormone therapy is critical to survival, it remains uncertain whether it should be administered as thyroxine, triiodothyronine, or both. Adjunctive measures, such as ventilation, warming, fluids, antibiotics, pressors, and corticosteroids, may be essential for survival.

  9. Myxedema coma.

    PubMed

    Kwaku, Maxwell P; Burman, Kenneth D

    2007-01-01

    Untreated or unrecognized hypothyroidism may progress to severe decompensated hypothyroidism or myxedema coma. Relatively few cases are reported in the literature since the first case was apparently reported from the St. Thomas Hospital in London in 1879. The paucity of cases may be due to either underreporting or improvement in the diagnosis and treatment of uncomplicated hypothyroidism. However, despite the ready availability of sensitive thyrotropin assays, the recognition and treatment of myxedema coma remains a challenge. Although thyroid hormone treatment is highly effective when combined with ventilatory and hemodynamic support in the intensive care unit setting, controversies abound on the optimal and most effective choice of thyroid hormone preparation: thyroxine and triiodothyronine and in what amount. Accumulated evidence now shows that proper use of either thyroxine alone or in combination with triiodothyronine may be effective therapy. PMID:17712058

  10. Coma recovery

    NASA Technical Reports Server (NTRS)

    Dimancescu, M. D.

    1978-01-01

    Arousal from coma is defined as a function of the reticular activating system that is located between the spinal cord and the diencephalon core of the brain stem. This system receives information from all the sensory functions of the body for distribution to the various parts of the cortex in order to maintain normal activities. Multimodal, neurosensory stimulation techniques are outlined that are designed to help the patient recover from the comatose state.

  11. [Results of corneal and total astigmatism estimation by different methods in myopic patients wearing orthokeratology contact lenses].

    PubMed

    Tarutta, E P; Aliaeva, O O; Verzhanskaia, T Iu; Milash, S V

    2013-01-01

    Reports have been made that corneal aberrations of all orders, including astigmatism, often significantly increase with the use of night orthokeratology lenses. In this study the dynamic changes of total and corneal astigmatism in myopes using orthokeratology lenses was evaluated by different methods. The study enrolled 38 patients (76 eyes) with low and medium myopia (28 and 48 eyes correspondingly) and initial astigmatism less than 2 diopters. The assessment was made before and in different terms after the patient started to wear orthokeratology lenses. Induced astigmatism (> or =1 diopter) was found in more than 50% of cases. The degree of astigmatism gradually increased from the centre to the periphery within the papillary zone. The maximum values were found within a 4-mm zone ("uptake zone") and minimal - within a 8-mm zone ("equalization zone"). In all patients, despite the presence of induced astigmatism and residual myopia (0.83+/-0.09 diopters in average), distance visual acuity was high enough without an additional correction (0.82+/-0.05 in average). Apparently, in these patients the aberrations (astigmatism in particular) exceed the focal depth.

  12. [Results of corneal and total astigmatism estimation by different methods in myopic patients wearing orthokeratology contact lenses].

    PubMed

    Tarutta, E P; Aliaeva, O O; Verzhanskaia, T Iu; Milash, S V

    2013-01-01

    Reports have been made that corneal aberrations of all orders, including astigmatism, often significantly increase with the use of night orthokeratology lenses. In this study the dynamic changes of total and corneal astigmatism in myopes using orthokeratology lenses was evaluated by different methods. The study enrolled 38 patients (76 eyes) with low and medium myopia (28 and 48 eyes correspondingly) and initial astigmatism less than 2 diopters. The assessment was made before and in different terms after the patient started to wear orthokeratology lenses. Induced astigmatism (> or =1 diopter) was found in more than 50% of cases. The degree of astigmatism gradually increased from the centre to the periphery within the papillary zone. The maximum values were found within a 4-mm zone ("uptake zone") and minimal - within a 8-mm zone ("equalization zone"). In all patients, despite the presence of induced astigmatism and residual myopia (0.83+/-0.09 diopters in average), distance visual acuity was high enough without an additional correction (0.82+/-0.05 in average). Apparently, in these patients the aberrations (astigmatism in particular) exceed the focal depth. PMID:24137984

  13. A simple method for astigmatic compensation of folded resonator without Brewster window.

    PubMed

    Qiao, Wen; Xiaojun, Zhang; Yonggang, Wang; Liqun, Sun; Hanben, Niu

    2014-02-10

    A folded resonator requires an oblique angle of incidence on the folded curved mirror, which introduces astigmatic distortions that limit the performance of the lasers. We present a simple method to compensate the astigmatism of folded resonator without Brewster windows for the first time to the best of our knowledge. Based on the theory of the propagation and transformation of Gaussian beams, the method is both effective and reliable. Theoretical results show that the folded resonator can be compensated astigmatism completely when the following two conditions are fulfilled. Firstly, when the Gaussian beam with a determined size beam waist is obliquely incident on an off-axis concave mirror, two new Gaussian beam respectively in the tangential and sagittal planes are formed. Another off-axis concave mirror is located at another intersection point of the two new Gaussian beams. Secondly, adjusting the incident angle of the second concave mirror or its focal length can make the above two Gaussian beam coincide in the image plane of the second concave mirror, which compensates the astigmatic aberration completely. A side-pumped continues-wave (CW) passively mode locked Nd:YAG laser was taken as an example of the astigmatically compensated folded resonators. The experimental results show good agreement with the theoretical predictions. This method can be used effectively to design astigmatically compensated cavities resonator of high-performance lasers.

  14. Astigmatism

    MedlinePlus

    Katz M, Kruger PB. The human eye as an optical system. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology . 2013 ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:chap 33. Kramarevsky N, Hardten ...

  15. Optical aberrations measurement with a low cost optometric instrument

    NASA Astrophysics Data System (ADS)

    Furlan, Walter D.; Muñoz-Escrivá, L.; Pons, A.; Martínez-Corral, M.

    2002-08-01

    A simple experimental method for measuring optical aberrations of a single lens is proposed. The technique is based on the use of an optometric instrument employed for the assessment of the refractive state of the eye: the retinoscope. Experimental results for spherical aberration and astigmatism are obtained.

  16. Astigmatism among institutionalized and noninstitutionalized mentally retarded.

    PubMed

    Courtney, G R

    1977-06-01

    Astigmatism was measured retinoscopically for 709 subjects residing in an institution for the mentally retarded and for 56 noninstitutionalized mentally retarded subjects at a community training center. About 60% of the subjects were between 15 and 45 years old. Compared to an intellectually normal sample of young men, astigmatism in the mentally retarded was greater in frequency and degree. For subjects with greater degrees of mental retardation, the prevalence of high astigmastism was significantly greater for whites than for nonwhites. There was no difference in astigmatism between institutionalized retardates and those living in a community setting, a finding that implies that the institutional environment was not the cause of the astigmatic differences between retarded and normal subjects.

  17. A design of PAL with astigmatism

    NASA Astrophysics Data System (ADS)

    Wei, Yefei; Xiang, Huazhong; Zhu, Tianfeng; Chen, Jiabi

    2015-08-01

    Progressive addition lens (PAL) is designed for those who suffer from myopia and presbyopia to have a clear vision from a far distance to a nearby distance. Additionally there are many people that also suffer from astigmatism and need to be corrected. The cylinder power can't be simply added to the diopter of the PAL directly, because the diopter of the PAL needs to be changed smoothly. A methods has been proposed in this article to solve the problem, the freeform surface height of a PAL without astigmatism and the cylindrical lens surface height for the correction of astigmatism are calculated separately. The both two surface heights were added together, then the final surface is produced and shown with the both properties of PALs and cylindrical lenses used to correct the astigmatism.

  18. Extended depth of focus intra-ocular lens: a solution for presbyopia and astigmatism

    NASA Astrophysics Data System (ADS)

    Zlotnik, Alex; Raveh, Ido; Ben Yaish, Shai; Yehezkel, Oren; Belkin, Michael; Zalevsky, Zeev

    2010-02-01

    Purpose: Subjects after cataract removal and intra-ocular lens (IOL) implantation lose their accommodation capability and are left with a monofocal visual system. The IOL refraction and the precision of the surgery determine the focal distance and amount of astigmatic aberrations. We present a design, simulations and experimental bench testing of a novel, non-diffractive, non-multifocal, extended depth of focus (EDOF) technology incorporated into an IOL that allows the subject to have astigmatic and chromatic aberrations-free continuous focusing ability from 35cm to infinity as well as increased tolerance to IOL decentration. Methods: The EDOF element was engraved on a surface of a monofocal rigid IOL as a series of shallow (less than one micron deep) concentric grooves around the optical axis. These grooves create an interference pattern extending the focus from a point to a length of about one mm providing a depth of focus of 3.00D (D stands for Diopters) with negligible loss of energy at any point of the focus while significantly reducing the astigmatic aberration of the eye and that generated during the IOL implantation. The EDOF IOL was tested on an optical bench simulating the eye model. In the experimental testing we have explored the characteristics of the obtained EDOF capability, the tolerance to astigmatic aberrations and decentration. Results: The performance of the proposed IOL was tested for pupil diameters of 2 to 5mm and for various spectral illuminations. The MTF charts demonstrate uniform performance of the lens for up to 3.00D at various illumination wavelengths and pupil diameters while preserving a continuous contrast of above 25% for spatial frequencies of up to 25 cycles/mm. Capability of correcting astigmatism of up to 1.00D was measured. Conclusions: The proposed EDOF IOL technology was tested by numerical simulations as well as experimentally characterized on an optical bench. The new lens is capable of solving presbyopia and astigmatism

  19. Astigmatism and the development of myopia in children.

    PubMed

    Gwiazda, J; Grice, K; Held, R; McLellan, J; Thorn, F

    2000-01-01

    While it is now established that astigmatism is more prevalent in infants and young children than in the adult population, little is known about the functional significance of this astigmatism, especially its role, if any, in emmetropization and the development of myopia. Manifest refractions (mean of 16 per subject) were obtained from 245 subjects starting in the first year, with 6-23 years of regular follow-up. Results showed that infantile astigmatism is associated with increased astigmatism and myopia during the school years. Two possible mechanisms underlying this association are discussed: (1) infantile astigmatism disrupts focusing mechanisms; and (2) ocular growth induces astigmatism and myopia.

  20. Wavefront aberration and contrast sensitivity after implantation of foldable and rigid iris claw phakic intraocular lenses: Artiflex versus artisan

    PubMed Central

    Parsipour, Faroogh; Razmju, Hassan; Khatavi, Fatima; Panahi, Maryam; Nouralishahi, Alireza; Peyman, Alireza

    2016-01-01

    Aim of study: The aim of this study is to assess wavefront aberration and contrast sensitivity (CS) after implantation of foldable iris claw – artiflex- and rigid iris claw – artisan- phakic intraocular lenses (pIOLs). Materials and Methods: A nonrandomized prospective comparative case study was performed on 57 eyes; of which, 54 were myopia and 3 were hyperopia. Twenty-four patients had artisan pIOL implantation and 33 had artiflex pIOL implantation. Higher-order aberration (HOA) and CS were obtained 1 year after surgery. Results: Total HOA in artisan group was greater than artiflex group (P = 0.044) with a mean HOA of 0.44 ± 0.15 root mean square (RMS) for artisan and 0.35 ± 0.15 RMS for artiflex. Although, there were no significant differences in the vertical trefoil, vertical coma, horizontal trefoil, horizontal coma, secondary astigmatism, quatrefoil, and fourth order spherical aberration in two groups. CS in mesopic conditions was better in artiflex-treated eyes at three spatial frequencies of 6, 12, and 18 cycles per degree (cpd) (P = 0.003, P = 0.007, and P = 0.00, respectively), and no significant difference was seen between two lenses at 3 cpd. Conclusion: Although the components of HOA were not significantly different between two groups, total HOA was higher in artisan group, which may be due to the slight differences in each component, increasing the HOA as a total. CS was significantly better in artiflex group. PMID:27380978

  1. Coma of modified Gregorian and Cassegrainian mirror systems

    NASA Technical Reports Server (NTRS)

    Jones, R. T.

    1976-01-01

    The equivalence of the classical Newtonian, Cassegrainian, and Gregorian mirror systems with respect to the first two Seidel aberrations is rederived by means of a simple congruence. The effects of arbitrary small modifications of the two mirror systems are then studied and general formulas are derived for the effects of such modifications on the spherical aberration and coma. Spherical aberration is corrected to the third order if the amount of glass removed from one surface is replaced at the corresponding zone of the other surface. Modifications in which one surface is made spherical while the other is adjusted to eliminate spherical aberration result in large increases of coma for systems having the usual amplifying ratios.

  2. The child in coma

    NASA Technical Reports Server (NTRS)

    Lewinn, E. B.

    1978-01-01

    Children in coma continue to pose medical, social, economic, ethical, moral, and legal problems. Modern life-support technology has aggravated these problems. Coma is viewed as a pathological state of unconsciousness from which the patient has not achieved arousal, and which calls for vigorous action to help him regain consciousness. There are two variables that have an especially important bearing on the ability to achieve arousal. These are: the character of the brain injury that caused the coma, and environmental factors that affect the patient after the injury.

  3. What Is a Coma?

    MedlinePlus

    ... Quizzes Kids' Dictionary of Medical Words En Español What Other Kids Are Reading Back-to-School Butterflies? ... Got Homework? Here's Help White House Lunch Recipes What Is a Coma? KidsHealth > For Kids > What Is ...

  4. Criteria for admissible values of smooth aberrations for nondiffractive laser beams

    SciTech Connect

    Malashko, Ya I; Khabibulin, V M

    2014-04-28

    We have derived analytical expressions, verified by the methods of numerical simulation, to evaluate the angular divergence of nondiffractive laser beams containing smooth aberrations, i.e., spherical defocusing, astigmatism and toroid. Using these expressions we have formulated the criteria for admissible values of smooth aberrations. (laser applications and other topics in quantum electronics)

  5. Effects of posterior corneal astigmatism on the accuracy of AcrySof toric intraocular lens astigmatism correction

    PubMed Central

    Zhang, Bin; Ma, Jing-Xue; Liu, Dan-Yan; Guo, Cong-Rong; Du, Ying-Hua; Guo, Xiu-Jin; Cui, Yue-Xian

    2016-01-01

    AIM To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism. METHODS Fifty-seven patients with toric intraocular lens (IOL) implantation and posterior corneal astigmatism exceeding 0.5 diopter were enrolled in this retrospective study. The keratometric astigmatism (KA) and total corneal astigmatism (TA) were measured using a Pentacam rotating Scheimpflug camera to assess the outcomes of AcrySof IOL implantation. Toric IOLs were evaluated in 26 eyes using KA measurements and in 31 eyes using TA measurements. Preoperative corneal astigmatism and postoperative refractive astigmatism were recorded for statistical analysis. The cylindrical power of toric IOLs was estimated in all eyes. RESULTS In all cases, the difference of toric IOL astigmatism magnitude between KA and TA measurements for the estimation of preoperative corneal astigmatism was statistically significant. Of a total of 57 cases, the 50.88% decreased from Tn to Tn-1, and 10.53% decreased from Tn to Tn-2. In all cases, 5.26% increased from Tn to Tn+1. The mean postoperative astigmatism within the TA group was significantly lower than that in the KA group. CONCLUSION The accuracy of total corneal astigmatism calculations and the efficacy of toric IOL correction can be enhanced by measuring both the anterior and posterior corneal surfaces using a Pentacam rotating Scheimpflug camera. PMID:27672591

  6. Corneal topography in the study of astigmatic excimer laser ablation

    NASA Astrophysics Data System (ADS)

    McDonnell, Peter J.

    1992-08-01

    Corneal astigmatism, both naturally occurring and iatrogenically induced, is a commonly encountered problem. Examination of corneal topography with instruments that digitize reflected ring images and calculate corneal geometry suggests that corneal astigmatism often deviates from spherocylindrical optics; the observed topography may be highly asymmetrical about the center of the pupil. Currently used incisional procedures are limited in terms of predictability of surgical outcome. The 193 nm excimer laser can be used to alter anterior corneal curvature and flatten the cornea to correct myopia. For correction of astigmatism, a slit-opening in the laser delivery system can be used to selectively flatten the steep meridian. Early results using this procedure for correction of iatrogenically induced high corneal astigmatism are promising. A nationwide multicenter clinical trial is now underway in the United States to evaluate this technique for the correction of naturally occurring astigmatism and compound myopic astigmatism.

  7. Two-mirror telescope design with third-order coma insensitive to decenter misalignment.

    PubMed

    Scaduto, Lucimara Cristina Nakata; Sasian, Jose; Stefani, Mario Antonio; Neto, Jarbas Caiado de Castro

    2013-03-25

    Misalignments always occur in real optical systems. These misalignments do not generate new aberration forms, but they change the aberration field dependence. Two-mirror telescopes have been used in several applications. We analyze a two-mirror telescope configuration that has negligible sensitivity to decenter misalignments. By applying the wave aberration theory for plane-symmetric optical systems it is shown that the asphericity in the secondary mirror, if properly chosen, can compensate for any decenter perturbation allowing third-order coma unchanged across the field of view. For any two-mirror system it is possible to find a configuration in which decenter misalignments do not generate field-uniform coma.

  8. On multisoliton solutions of the constant astigmatism equation

    NASA Astrophysics Data System (ADS)

    Hlaváč, Adam

    2015-09-01

    We introduce an algebraic formula producing infinitely many exact solutions of the constant astigmatism equation {z}{yy}+{(1/z)}{xx}+2=0 from a given seed. A construction of corresponding surfaces of constant astigmatism is then a matter of routine. As a special case, we consider multisoliton solutions of the constant astigmatism equation defined as counterparts of famous multisoliton solutions of the sine-Gordon equation. A few particular examples are surveyed as well.

  9. Axially astigmatic surfaces: different types and their properties

    NASA Astrophysics Data System (ADS)

    Malacara-Doblado, Daniel; Malacara-Hernandez, Daniel; Garcia-Marquez, Jorge L.

    1996-12-01

    Axially astigmatic surfaces have different curvatures in orthogonal diameters. Toroidal and spherocylindrical optical surfaces are two mathematically different special cases of axially astigmatic surfaces as noted by Menchaca and Malacara (1986), but they are almost identical in the vicinity of the optical axis. The different between these two surfaces increases when the distance to the optical axis increases. We study the general properties of astigmatic surfaces and some special interesting cases.

  10. Astigmatism in Monkeys with Experimentally Induced Myopia or Hyperopia

    PubMed Central

    KEE, CHEA-SU; HUNG, LI-FANG; QIAO-GRIDER, YING; RAMAMIRTHAM, RAMKUMAR; SMITH, EARL L.

    2006-01-01

    Purpose Astigmatism is the most common ametropia found in humans and is often associated with large spherical ametropias. However, little is known about the etiology of astigmatism or the reason(s) for the association between spherical and astigmatic refractive errors. This study examines the frequency and characteristics of astigmatism in infant monkeys that developed axial ametropias as a result of altered early visual experience. Methods Data were obtained from 112 rhesus monkeys that experienced a variety of lens-rearing regimens that were intended to alter the normal course of emmetropization. These visual manipulations included form deprivation (n = 13); optically imposed defocus (n = 48); and continuous ambient lighting with (n = 6) or without optically imposed defocus (n = 6). In addition, data from 19 control monkeys and 39 infants reared with an optically imposed astigmatism were used for comparison purposes. The lens-rearing period started at approximately 3 weeks of age and ended by 4 to 5 months of age. Refractive development for all monkeys was assessed periodically throughout the treatment and subsequent recovery periods by retinoscopy, keratometry, and A-scan ultrasonography. Results In contrast to control monkeys, the monkeys that had experimentally induced axial ametropias frequently developed significant amounts of astigmatism (mean refractive astigmatism = 0.37 ± 0.33 D [control] vs. 1.24 ± 0.81 D [treated]; two-sample t-test, p < 0.0001), especially when their eyes exhibited relative hyperopic shifts in refractive error. The astigmatism was corneal in origin (Pearson’s r; p < 0.001 for total astigmatism and the JO and J45 components), and the axes of the astigmatism were typically oblique and bilaterally mirror symmetric. Interestingly, the astigmatism was not permanent; the majority of the monkeys exhibited substantial reductions in the amount of astigmatism at or near the end of the lens-rearing procedures. Conclusions In infant monkeys

  11. Minimizing camera-eye optical aberrations during the 3D reconstruction of retinal structures

    NASA Astrophysics Data System (ADS)

    Aldana-Iuit, Javier; Martinez-Perez, M. Elena; Espinosa-Romero, Arturo; Diaz-Uribe, Rufino

    2010-05-01

    3D reconstruction of blood vessels is a powerful visualization tool for physicians, since it allows them to refer to qualitative representation of their subject of study. In this paper we propose a 3D reconstruction method of retinal vessels from fundus images. The reconstruction method propose herein uses images of the same retinal structure in epipolar geometry. Images are preprocessed by RISA system for segmenting blood vessels and obtaining feature points for correspondences. The correspondence points process is solved using correlation. The LMedS analysis and Graph Transformation Matching algorithm are used for outliers suppression. Camera projection matrices are computed with the normalized eight point algorithm. Finally, we retrieve 3D position of the retinal tree points by linear triangulation. In order to increase the power of visualization, 3D tree skeletons are represented by surfaces via generalized cylinders whose radius correspond to morphological measurements obtained by RISA. In this paper the complete calibration process including the fundus camera and the optical properties of the eye, the so called camera-eye system is proposed. On one hand, the internal parameters of the fundus camera are obtained by classical algorithms using a reference pattern. On the other hand, we minimize the undesirable efects of the aberrations induced by the eyeball optical system assuming that contact enlarging lens corrects astigmatism, spherical and coma aberrations are reduced changing the aperture size and eye refractive errors are suppressed adjusting camera focus during image acquisition. Evaluation of two self-calibration proposals and results of 3D blood vessel surface reconstruction are presented.

  12. Peripheral refraction and higher-order aberrations with cycloplegia and fogging lenses using the BHVI-EyeMapper

    PubMed Central

    Bakaraju, Ravi Chandra; Fedtke, Cathleen; Ehrmann, Klaus; Falk, Darrin; Thomas, Varghese; Holden, Brien Anthony

    2015-01-01

    Purpose To determine if a fogging lens ameliorates accommodative effects driven by the closed-view design of the BHVI-EyeMapper (EM) instrument. We compared cycloplegic refraction and higher-order aberration measurements of the EM with those obtained with a fogging lens. Methods Twenty-six, young, participants (15F, 25 ± 5 years, range: 18–35 years, SE: +0.25 D and −3.50 D) with good ocular health were recruited. Five independent measurements of on- and off-axis refraction and higher-order aberrations were recorded across the horizontal visual field, under two conditions: non-cycloplegic measurements with +1.00 D fogging lens and cycloplegia, always in the same sequence. The contralateral eye was occluded during the measurements. Two drops of 1% Tropicamide delivered within 5 min facilitated cycloplegic measurements. All participants were refracted 30 min after installation of the second drop. Results Mean spherical equivalent measures of the non-cycloplegic condition were significantly more myopic than their cycloplegic counterparts (p < 0.05); approximately by 0.50 D centrally, increasing to 1.00 D towards the periphery. The horizontal astigmatic component, J180, demonstrated small but statistically significant differences between the test conditions. Differences were predominant for eccentricities greater than 30°, in both nasal and temporal meridians. The oblique astigmatic component, J45, was not significantly different between the test conditions. The primary spherical aberration coefficient C(4, 0) was significantly less positive for the non-cycloplegic state than its cycloplegic counterpart. This result held true across the entire horizontal visual field. The horizontal coma and trefoil coefficients C(3, 1) and C(3, 3) were not significantly different between the two conditions. Conclusions The use of +1.00 D fogging lens without cycloplegia did not provide complete relaxation of accommodation. The discrepancies between cycloplegic and non

  13. [Corneal higher order aberrations and their changes with aging].

    PubMed

    Cermáková, S; Skorkovská, S

    2010-12-01

    Cornea is the most important refractive medium of the eye and affects its total aberration state. This paper deals with corneal higher order aberrations in healthy humans and evaluates their changes with aging and corneal curvature. The influence of the corneal anterior and posterior surfaces on aberrations of the whole cornea was also investigated. The examination was performed with a Scheimpflug camera which enables to examine the anterior and posterior corneal surface separately. The results show that higher order aberrations of the whole cornea are influenced mainly by the anterior surface aberrations. The main corneal higher order aberration is the Z (4,0) spherical aberration which has a positive value and increases with age. Also, 3rd order aberration values are of importance, especially coma which also increases with age. As a consequence, the root-mean-square of the 3rd and 4th order aberrations in elderly people has a higher value.

  14. Effect of suture material on postoperative astigmatism.

    PubMed

    Gimbel, H V; Raanan, M G; DeLuca, M

    1992-01-01

    Two hundred patients were enrolled in a randomized, prospective clinical trial comparing the use of 10-0 nylon, 10-0 polypropylene (Prolene), 11-0 polyester (Mersilene), and 10-0 polyethylene (Novafil) suture materials on the amount and decay curves of surgically induced astigmatism following intraocular lens (IOL) surgery. Patients with Mersilene and nylon sutures had the highest amounts of induced with-the-rule (WTR) cylinder (significantly more than Prolene) at one day after surgery. However, the WTR cylinder decayed rapidly for nylon during the first three months but more slowly for Mersilene because of its lack of stretchability. The Prolene group had the lowest level of induced WTR cylinder at one day, but against-the-rule (ATR) drift occurred, leaving cases with ATR astigmatism by a year. The nylon group had the second highest amount of induced WTR cylinder at one day, which had decayed to ATR cylinder by five months. Between one and two years postoperatively, the nylon group experienced a significant ATR shift. The amount of early induced WTR cylinder seemed to be related to the knot-tying technique and tissue gripping characteristics, whereas the shape of the decay curve was related to the material characteristics of the suture. PMID:1531234

  15. 3D astigmatic depth sensing camera

    NASA Astrophysics Data System (ADS)

    Birch, Gabriel C.; Tyo, J. Scott; Schwiegerling, Jim

    2011-10-01

    Three-dimensional displays have become increasingly present in consumer markets. However, the ability to capture threedimensional images inexpensively and without major modifications to current cameras is uncommon. Our goal is to create a modification to a common commercial camera that allows a three dimensional reconstruction. We desire such an imaging system to be inexpensive and easy to use. Furthermore, we require that any three-dimensional modification to a camera does not reduce its resolution. Here we present a possible solution to this problem. A commercial digital camera is used with a projector system with astigmatic focus to capture images of a scene. By using an astigmatic projected pattern we can create two different focus depths for horizontal and vertical features of the projected pattern, thereby encoding depth. This projector could be integrated into the flash unit of the camera. By carefully choosing a pattern we are able to exploit this differential focus in image processing. Wavelet transforms are performed on the image that pick out the projected pattern. By taking ratios of certain wavelet coefficients we are able to correlate the distance an object at a particular transverse position is from the camera to the contrast ratios. We present our information regarding construction, calibration, and images produced by this system. The nature of linking a projected pattern design and image processing algorithms will be discussed.

  16. Accommodation in Astigmatic Children During Visual Task Performance

    PubMed Central

    Harvey, Erin M.; Miller, Joseph M.; Apple, Howard P.; Parashar, Pavan; Twelker, J. Daniel; Crescioni, Mabel; Davis, Amy L.; Leonard-Green, Tina K.; Campus, Irene; Sherrill, Duane L.

    2014-01-01

    Purpose. To determine the accuracy and stability of accommodation in uncorrected children during visual task performance. Methods. Subjects were second- to seventh-grade children from a highly astigmatic population. Measurements of noncycloplegic right eye spherical equivalent (Mnc) were obtained while uncorrected subjects performed three visual tasks at near (40 cm) and distance (2 m). Tasks included reading sentences with stimulus letter size near acuity threshold and an age-appropriate letter size (high task demands) and viewing a video (low task demand). Repeated measures ANOVA assessed the influence of astigmatism, task demand, and accommodative demand on accuracy (mean Mnc) and variability (mean SD of Mnc) of accommodation. Results. For near and distance analyses, respectively, sample size was 321 and 247, mean age was 10.37 (SD 1.77) and 10.30 (SD 1.74) years, mean cycloplegic M was 0.48 (SD 1.10) and 0.79 diopters (D) (SD 1.00), and mean astigmatism was 0.99 (SD 1.15) and 0.75 D (SD 0.96). Poor accommodative accuracy was associated with high astigmatism, low task demand (video viewing), and high accommodative demand. The negative effect of accommodative demand on accuracy increased with increasing astigmatism, with the poorest accommodative accuracy observed in high astigmats (≥3.00 D) with high accommodative demand/high hyperopia (1.53 D and 2.05 D of underaccommodation for near and distant stimuli, respectively). Accommodative variability was greatest in high astigmats and was uniformly high across task condition. No/low and moderate astigmats showed higher variability for the video task than the reading tasks. Conclusions. Accuracy of accommodation is reduced in uncorrected children with high astigmatism and high accommodative demand/high hyperopia, but improves with increased visual task demand (reading). High astigmats showed the greatest variability in accommodation. PMID:25103265

  17. Lack of oblique astigmatism in the chicken eye.

    PubMed

    Maier, Felix M; Howland, Howard C; Ohlendorf, Arne; Wahl, Siegfried; Schaeffel, Frank

    2015-04-01

    Primate eyes display considerable oblique off-axis astigmatism which could provide information on the sign of defocus that is needed for emmetropization. The pattern of peripheral astigmatism is not known in the chicken eye, a common model of myopia. Peripheral astigmatism was mapped out over the horizontal visual field in three chickens, 43 days old, and in three near emmetropic human subjects, average age 34.7years, using infrared photoretinoscopy. There were no differences in astigmatism between humans and chickens in the central visual field (chicks -0.35D, humans -0.65D, n.s.) but large differences in the periphery (i.e. astigmatism at 40° in the temporal visual field: humans -4.21D, chicks -0.63D, p<0.001, unpaired t-test). The lack of peripheral astigmatism in chicks was not due to differences in corneal shape. Perhaps related to their superior peripheral optics, we found that chickens had excellent visual performance also in the far periphery. Using an automated optokinetic nystagmus paradigm, no difference was observed in spatial visual performance with vision restricted to either the central 67° of the visual field or to the periphery beyond 67°. Accommodation was elicited by stimuli presented far out in the visual field. Transscleral images of single infrared LEDs showed no sign of peripheral astigmatism. The chick may be the first terrestrial vertebrate described to lack oblique astigmatism. Since corneal shape cannot account for the difference in astigmatism in humans and chicks, it must trace back to the design of the crystalline lens. The lack of peripheral astigmatism in chicks also excludes a role in emmetropization.

  18. Accommodative lag and fluctuations when optical aberrations are manipulated.

    PubMed

    Gambra, Enrique; Sawides, Lucie; Dorronsoro, Carlos; Marcos, Susana

    2009-06-09

    We evaluated the accommodative response to a stimulus moving from 0 to 6 D following a staircase function under natural, corrected, and induced optical aberrations, using an adaptive-optics (AO) electromagnetic deformable mirror. The accommodative response of the eye (through the mirror) and the change of aberrations were measured on 5 subjects using a Hartmann-Shack wavefront sensor operating at 12.8 Hz. Five conditions were tested: (1) natural aberrations, (2) AO correction of the unaccommodated state and induction (over 6-mm pupils) of (3) +1 microm and (4) -1 microm of spherical aberration and (5) -2 microm of vertical coma. Four subjects showed a better accommodative response with AO correction than with their natural aberrations. The induction of negative spherical aberration also produced a better accommodative response in the same subjects. Accommodative lag increased in all subjects when positive spherical aberration and coma were induced. Fluctuations of the accommodative response (computed during each 1-D period of steady accommodation) increased with accommodative response when high-order aberrations were induced. The largest fluctuations occurred for induced negative spherical aberration and the smallest for natural and corrected aberrations. The study demonstrates that aberrations influence accommodative lag and fluctuations of accommodation and that correcting aberrations improves rather than compromises the accommodative response.

  19. Ray-based optical design tool for freeform optics: coma full-field display.

    PubMed

    Bauer, Aaron; Rolland, Jannick P; Thompson, Kevin P

    2016-01-11

    The field of optical fabrication has progressed to a point where manufacturing optical quality freeform surfaces is no longer prohibitive. However, to stimulate the development of freeform systems, optical designers must be provided with the necessary tools. Full-field displays are an example of such a tool. Identifying the field dependence of the dominant aberrations of a freeform system is critical for a controlled optimization and with the help of full-field displays, this can be accomplished. Of specific interest is coma, an often system-limiting aberration and an aberration that has recently been directly addressed with freeform surfaces. In this research, we utilize nodal aberration theory to develop a ray-based method to generate a coma full-field display that circumvents wavefront fitting errors that can affect Zernike polynomial-based full-field displays for highly aberrated freeform starting designs.

  20. Study on the modification of measured wavefront aberration data for customized visual correction

    NASA Astrophysics Data System (ADS)

    Liu, Ming; Zhang, Yong; Zhang, Zhidong; Quan, Wei; An, Li

    2008-12-01

    Wavefront aberration of human eye is an important foundation for customized vision correction. In most current aberrometers, near infrared light is used to measure ocular wavefront aberration, whereas for customized visual correction, wavefront aberration data in visible range are required. With the measured wavefront aberration, corneal topography and eye's axial lengths data, individual eye models for twenty normal human eyes are constructed with the optical design software ZEMAX. Changing the incidence light wavelength and the refractive indexes of eye models, the values of defocus, astigmatism, higher-order aberrations in the measuring wavelength (833nm) and at the most sensitive wavelength of human eye (555nm) are obtained. Average focus shift between 833nm and 555nm is found to be about 0.94D, and different slightly for different individuals; the differences of astigmatism and higher-order aberrations between 833nm and 555nm are quite slight. For customized visual correction, the measured defocus value should be modified, whereas the measured astigmatism and higher-order aberrations could be used directly for the current correction precision. Individual eye model is a useful tool for accurate transformation of the measured wavefront aberration data into the data for visible spectrum.

  1. Membrane-based deformable mirror: intrinsic aberrations and alignment issues

    NASA Astrophysics Data System (ADS)

    Raja Bayanna, A.; Louis, Rohan E.; Chatterjee, S.; Mathew, Shibu K.; Venkatakrishnan, P.

    2015-03-01

    A Deformable Mirror (DM) is an important component of an Adaptive Optics system. It is known that an on-axis spherical/parabolic optical component, placed at an angle to the incident beam introduces defocus as well as astigmatism in the image plane. Although the former can be compensated by changing the focal plane position, the latter cannot be removed by mere optical re-alignment. Since the DM is to be used to compensate a turbulence-induced curvature term in addition to other aberrations, it is necessary to determine the aberrations induced by such (curved DM surface) an optical element when placed at an angle (other than 0 degree) of incidence in the optical path. To this effect, we estimate to a first order, the aberrations introduced by a DM as a function of the incidence angle and deformation of the DM surface. We record images using a simple setup in which the incident beam is reflected by a 37 channel Micro-machined Membrane Deformable Mirror for various angles of incidence. It is observed that astigmatism is a dominant aberration which was determined by measuring the difference between the tangential and sagital focal planes. We justify our results on the basis of theoretical simulations and discuss the feasibility of using such a system for adaptive optics considering a trade-off between wavefront correction and astigmatism due to deformation.

  2. Optical imaging module for astigmatic detection system.

    PubMed

    Wang, Wei-Min; Cheng, Chung-Hsiang; Molnar, Gabor; Hwang, Ing-Shouh; Huang, Kuang-Yuh; Danzebrink, Hans-Ulrich; Hwu, En-Te

    2016-05-01

    In this paper, an optical imaging module design for an astigmatic detection system (ADS) is presented. The module is based on a commercial optical pickup unit (OPU) and it contains a coaxial illuminant for illuminating a specimen. Furthermore, the imaging module facilitates viewing the specimen and the detection laser spot of the ADS with a lateral resolution of approximately 1 μm without requiring the removal of an element of the OPU. Two polarizers and one infrared filter are used to eliminate stray laser light in the OPU and stray light produced by the illuminant. Imaging modules designed for digital versatile disks (DVDs) and Blu-ray DVDs were demonstrated. Furthermore, the module can be used for imaging a small cantilever with approximate dimensions of 2 μm (width) × 5 μm (length), and therefore, it has the potential to be used in high-speed atomic force microscopy. PMID:27250434

  3. Chemistry in cometary comae.

    PubMed

    Irvine, W M; Dickens, J E; Lovell, A J; Schloerb, F P; Senay, M; Bergin, E A; Jewitt, D; Matthews, H E

    1998-01-01

    Significant gas-phase chemistry occurs in the comae of bright comets, as is demonstrated here for the case of Comet Hale-Bopp. The abundance ratio of the two isomers, hydrogen cyanide and hydrogen isocyanide, is shown to vary with heliocentric distance in a way that is consistent with production of HNC by ion-molecule chemistry initiated by the photoionization of water. Likewise, the first maps of emission from HCO+ show an abundance and an extended distribution that are consistent with the same chemical model.

  4. Chemistry in cometary comae

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Dickens, J. E.; Lovell, A. J.; Schloerb, F. P.; Senay, M.; Bergin, E. A.; Jewitt, D.; Matthews, H. E.

    1998-01-01

    Significant gas-phase chemistry occurs in the comae of bright comets, as is demonstrated here for the case of Comet Hale-Bopp. The abundance ratio of the two isomers, hydrogen cyanide and hydrogen isocyanide, is shown to vary with heliocentric distance in a way that is consistent with production of HNC by ion-molecule chemistry initiated by the photoionization of water. Likewise, the first maps of emission from HCO+ show an abundance and an extended distribution that are consistent with the same chemical model.

  5. Wave-front aberrations in the anterior corneal surface and the whole eye.

    PubMed

    He, Ji C; Gwiazda, Jane; Thorn, Frank; Held, Richard

    2003-07-01

    In order to investigate the sources of wave-front aberrations in the human eye, we have measured the aberrations of the anterior cornea and the whole eye using a topographic system and a psychophysical wave-front sensor. We have also calculated the aberrations for the internal optics of both eyes of 45 young subjects (aged 9 to 29 years). The mean rms for the anterior cornea was similar to that for the internal optics and thewhole eye when astigmatism was included, but less than that for both the internal optics and the whole eye with astigmatism removed. For eyes with low whole-eye rms values, mean rms for the anterior cornea was greater than that for the whole eye, suggesting that the anterior corneal aberration is partially compensated by the internal optics of the eye to produce the low whole-eye rms. For eyes with larger whole-eye rms values, the rms values for both the anterior cornea and the internal optics were less than that for the whole eye. Thus the aberrations for the two elements tend to be primarily additive. This pattern exists whether or not astigmatism was included in the wave-front aberration rms. For individual Zernike terms, astigmatism and spherical aberration in the anterior cornea were partially compensated by internal optics, while some other Zernike terms showed addition between the anterior cornea and internal optics. Individual eyes show different combinations of compensation and addition across different Zernike terms. Our data suggest that the reported loss of internal compensation for anterior corneal aberrations in elderly eyes with large whole-eye aberrations [J. Opt. Soc. Am. A 19, 137 (2002)] may also occur in young eyes.

  6. FASTDEF: fast defocus and astigmatism estimation for high-throughput transmission electron microscopy.

    PubMed

    Vargas, J; Otón, J; Marabini, R; Jonic, S; de la Rosa-Trevín, J M; Carazo, J M; Sorzano, C O S

    2013-02-01

    In this work we present a fast and automated algorithm for estimating the contrast transfer function (CTF) of a transmission electron microscope. The approach is very suitable for High Throughput work because: (a) it does not require any initial defocus estimation, (b) it is almost an order of magnitude faster than existing approaches, (c) it opens the way to well-defined extensions to the estimation of higher order aberrations, at the same time that provides defocus and astigmatism estimations comparable in accuracy to well established methods, such as Xmipp and CTFFIND3 approaches. The new algorithm is based on obtaining the wrapped modulating phase of the power spectra density pattern by the use of a quadrature filter. This phase is further unwrapped in order to obtain the continuous and smooth absolute phase map; then a Zernike polynomial fitting is performed and the defocus and astigmatism parameters are determined. While the method does not require an initial estimation of the defocus parameters or any non-linear optimization procedure, these approaches can be used if further refinement is desired. Results of the CTF estimation method are presented for standard negative stained images, cryo-electron microscopy images in the absence of carbon support, as well as micrographs with only ice. Additionally, we have also tested the proposed method with micrographs acquired from tilted and untilted samples, obtaining good results. The algorithm is freely available as a part of the Xmipp package [http://xmipp.cnb.csic.es].

  7. Dual quantum cascade laser trace gas instrument with astigmatic Herriott cell at high pass number.

    PubMed

    McManus, J Barry; Zahniser, Mark S; Nelson, David D

    2011-02-01

    We have developed and demonstrated a high-sensitivity trace gas instrument employing two mid-infrared quantum cascade lasers and an astigmatic Herriott sample cell with up to a 240 m path length. Several aspects of astigmatic Herriott cell optics have been addressed to enable operation at a high pass number (up to 554), including aberrations and pattern selection to minimize interference fringes. The new instrument design, based on the 200 m cell, can measure various atmospheric trace gases, depending on the installed lasers, with multiple trace gases measured simultaneously. Demonstrated concentration noise levels (1 s average) are 40 parts per trillion [(ppt) 10(-12)] for formaldehyde, 10 ppt for carbonyl sulfide, 110 ppt for hydrogen peroxide (H2O2), and 180 ppt for nitrous acid (HONO). High-precision measurements of nitrous oxide and methane have been recorded at the same time as high-sensitivity measurements of HONO and H2O2.

  8. Induced corneal astigmatism with hydrophilic contact lenses.

    PubMed

    Morgan, J F

    1975-04-01

    Changes in keratometer readings were measured in 87 patients, wearing hydrophilic contact lenses for three to more than eighteen months. Twenty-four eyes in the group had an increase of +0.75 or more in the keratometer readings, which invariably involved the vertical reading and was often associated with a distortion of the mire reflex. The change was high as +2.75 diopters. If greater than +1.00 diopter, it was associated with decreased visual acuity with forward correction and with the hydrophilic contact lenses. All but one of the patients who showedchanges of greater than +0.75 diopters over their baseline keratometer readings, were wearing their lenses on an average of 14-16 hours a day. The keratometer readings reverted to the baseline levels with a loss of the distrotion, if the patient reduced the wearing time to less than 12 hours daily. We believe that a maximum average daily wearing time of 12 hours is the safety limit required to minimize the development of induced corneal astigmatism.

  9. Transverse chromatic aberration after corneal refractive surgery

    NASA Astrophysics Data System (ADS)

    Anera, R. G.; Jiménez, J. R.; Jiménez del Barco, L.; Hita, E.

    2005-05-01

    An expression has been deduced theoretically from a schematic-eye model, for the transverse or lateral chromatic aberration (TCA) after refractive surgery. The aim was to investigate analytically how chromatic aberration varies after the emmetropization process. These changes in the TCA have been characterized from changes in corneal asphericity. The results indicate that TCA after refractive surgery diminishes as the degree of myopia increases, a trend contrary to that occurring with monochromatic aberrations, such as spherical or coma. These results can explain the fact that the real deterioration of the visual function under photopic conditions detected in those operated on for myopia is less than expected when only monochromatic aberrations are taken into account.

  10. Three Methods for Correction of Astigmatism during Phacoemulsification

    PubMed Central

    Mohammad-Rabei, Hossein; Mohammad-Rabei, Elham; Espandar, Goldis; Javadi, Mohammad Ali; Jafarinasab, Mohammad Reza; Hashemian, Seyed Javad; Feizi, Sepehr

    2016-01-01

    Purpose: To compare the safety and efficacy of three methods for correcting pre-existing astigmatism during phacoemulsification. Methods: This prospective, comparative, non-randomized study was conducted from March 2010 to January 2011, and included patients with keratometric astigmatism ≥1.25 D undergoing cataract surgery. Astigmatism was corrected using the following approaches: limbal relaxing incisions (LRI) on the steep meridian, extension and suturing of the phaco incision created at the steep meridian (extended-on-axis incision, EOAI), and toric intraocular lens (tIOL) implantation. Keratometric and refractive astigmatism were evaluated 1, 8, and 24 weeks postoperatively. Results: Eighty-three eyes of 72 patients (35 male and 37 female) with mean age of 62.4 ± 14.3 (range, 41-86) years were enrolled. The astigmatism was corrected by using the LRI, EOAI and tIOL implantation methods in 17, 33 and 33 eyes, respectively. Postoperative uncorrected distance visual acuity (UDVA) was significantly improved in all three groups. The difference in postoperative UDVA was not statistically significant among the study groups throughout follow-up except at week 24, when UCVA was significantly better in the tIOL group as compared to the EOAI group (P = 0.024). There is no statistically significant difference of correction index and index of success between three groups at week 24 (P = 0.085 and P = 0.085 respectively). Conclusion: There was no significant difference in astigmatism reduction among the three methods of astigmatism correction during phacoemulsification. Each of these methods can be used at the discretion of the surgeon. PMID:27413496

  11. Observations of FK Comae stars

    NASA Technical Reports Server (NTRS)

    Bopp, B. W.

    1981-01-01

    Observations on the FK Comae stars are described. FK Com, UZ Lib and HD 199178 are compared and related as a group of stars. The crucial observational tests of the proposed evolutionary status of these stars are noted.

  12. Comparison of Aberrations After Standard and Customized Refractive Surgery

    NASA Astrophysics Data System (ADS)

    Fang, L.; He, X.; Wang, Y.

    2013-09-01

    To detect possible differences in residual wavefront aberrations between standard and customized laser refractive surgery based onmathematical modeling, the residual optical aberrations after conventional and customized laser refractive surgery were compared accordingto the ablation profile with transition zone. The results indicated that ablation profile has a significant impact on the residual aberrations.The amount of residual aberrations for conventional correction is higher than that for customized correction. Additionally, the residualaberrations for high myopia eyes are markedly larger than those for moderate myopia eyes. For a 5 mm pupil, the main residual aberrationterm is coma and yet it is spherical aberration for a 7 mm pupil. When the pupil diameter is the same as optical zone or greater, themagnitudes of residual aberrations is obviously larger than that for a smaller pupil. In addition, the magnitudes of the residual fifth orsixth order aberrations are relatively large, especially secondary coma in a 6 mm pupil and secondary spherical aberration in a 7 mm pupil.Therefore, the customized ablation profile may be superior to the conventional correction even though the transition zone and treatmentdecentration are taken into account. However, the customized ablation profile will still induce significant amount of residual aberrations.

  13. Insulinoma Causing Prolonged Hypoglycaemic Coma.

    PubMed

    Kumar, Prabhat; Chauhan, Ajay; Dixit, Juhi; Jyotsana; Gupta, Harish

    2016-08-01

    Insulinoma is a rare pancreatic endocrine tumour with an incidence of four cases per million per year. A recurrent episode of fasting hypoglycaemia is the most common manifestation of these tumours. Diagnosis is often delayed due to varied presentation but once diagnosed, prognosis is often good after surgical resection of the lesion. Severe hypoglycaemia in insulinoma causing coma and death is rare. We report a case of hypoglycaemic coma secondary to an insulinoma in an elderly man which proved fatal. PMID:27656487

  14. Small Incision Lenticule Extraction for Postkeratoplasty Myopia and Astigmatism

    PubMed Central

    Ibrahim, Osama; Shehata, Kitty; Abdalla, Moones F.

    2016-01-01

    Purpose. To evaluate the visual and refractive outcomes after small incision lenticule extraction (SMILE) for treating myopia and myopic astigmatism after penetrating keratoplasty (PKP). Design. Case-series. Methods. Ten eyes of 10 patients with previous PKP and residual myopic astigmatism for whom pentacam imaging and thickness measurements were acceptable for laser vision correction. Manifest refraction (MR), uncorrected distance visual acuity (UDVA), and corrected distance visual acuity (CDVA) were obtained preoperatively and one day, one week, and one, 3, and 6 months postoperatively. Cases were operated on the VisuMax® femtosecond laser platform with 500 kHz repetition rate. Results. The mean correction ratio for spherical errors was 0.84 ± 0.19 D and for the mean refractive spherical equivalent (MRSE) was 0.79 ± 0.13 D. Vector analysis showed a mean astigmatism reduction at the intended axis of 67 ± 25.25%, a correction index of 0.81 ± 0.21, and an overall mean percentage of success of astigmatism surgery of 53 ± 37.9%. The postoperative MRSE was stable throughout the 6-month follow-up period. The efficacy index was 0.93 and the safety index was 1.12. Conclusion. SMILE for correction of post-PKP myopia and astigmatism is effective, safe, and stable with moderate accuracy and predictability. Centration of the treatment within the grafts was easily performed. PMID:27446606

  15. EUV phase-shifting masks and aberration monitors

    NASA Astrophysics Data System (ADS)

    Deng, Yunfei; Neureuther, Andrew R.

    2002-07-01

    Rigorous electromagnetic simulation with TEMPEST is used to examine the use of phase-shifting masks in EUV lithography. The effects of oblique incident illumination and mask patterning by ion-mixing of multilayers are analyzed. Oblique incident illumination causes streamers at absorber edges and causes position shifting in aerial images. The diffraction waves between ion-mixed and pristine multilayers are observed. The phase-shifting caused by stepped substrates is simulated and images show that it succeeds in creation of phase-shifting effects. The diffraction process at the phase boundary is also analyzed. As an example of EUV phase-shifting masks, a coma pattern and probe based aberration monitor is simulated and aerial images are formed under different levels of coma aberration. The probe signal rises quickly as coma increases as designed.

  16. Quasi-Bessel beams from asymmetric and astigmatic illumination sources.

    PubMed

    Müller, Angelina; Wapler, Matthias C; Schwarz, Ulrich T; Reisacher, Markus; Holc, Katarzyna; Ambacher, Oliver; Wallrabe, Ulrike

    2016-07-25

    We study the spatial intensity distribution and the self-reconstruction of quasi-Bessel beams produced from refractive axicon lenses with edge emitting laser diodes as asymmetric and astigmatic illumination sources. Comparing these to a symmetric mono-mode fiber source, we find that the asymmetry results in a transition of a quasi-Bessel beam into a bow-tie shaped pattern and eventually to a line shaped profile at a larger distance along the optical axis. Furthermore, we analytically estimate and discuss the effects of astigmatism, substrate modes and non-perfect axicons. We find a good agreement between experiment, simulation and analytic considerations. Results include the derivation of a maximal axicon angle related to astigmatism of the illuminating beam, impact of laser diode beam profile imperfections like substrate modes and a longitudinal oscillation of the core intensity and radius caused by a rounded axicon tip. PMID:27464190

  17. Graded nonintersecting transverse incisions for correction of idiopathic astigmatism.

    PubMed

    Thornton, S P; Sanders, D R

    1987-01-01

    We present the results of a consecutive series of graded transverse (T) incisions for correcting idiopathic astigmatism evaluated by vector analysis, a method not previously used to report T-incision results. In fact, no clinical studies on the results of the T-incision method have been reported. For comparison with conventional reporting methods, the results of graded T incisions on a series of eyes were evaluated, using both vector analysis and simplified analytic procedures. Sixty eyes were evaluated following surgery based on the Thornton guide for astigmatism correction. The mean preoperative cylinder in the series was 1.5 diopters (D) (SD = 0.43, range 1.00 D to 2.25 D); mean postoperative cylinder was 0.4 D (SD = 0.61, range 0 to 3.75 D). The mean decrease of 1.1 D was statistically significant. The results show that it is possible to quantify astigmatism correction using vector analysis. PMID:3559948

  18. Interaction of axial and oblique astigmatism in theoretical and physical eye models.

    PubMed

    Liu, Tao; Thibos, Larry N

    2016-09-01

    The interaction between oblique and axial astigmatism was investigated analytically (generalized Coddington's equations) and numerically (ray tracing) for a theoretical eye model with a single refracting surface. A linear vector-summation rule for power vector descriptions of axial and oblique astigmatism was found to account for their interaction over the central 90° diameter of the visual field. This linear summation rule was further validated experimentally using a physical eye model measured with a laboratory scanning aberrometer. We then used the linear summation rule to evaluate the relative contributions of axial and oblique astigmatism to the total astigmatism measured across the central visual field. In the central visual field, axial astigmatism dominates because the oblique astigmatism is negligible near the optical axis. At intermediate eccentricities, axial and oblique astigmatism may have equal magnitude but orthogonal axes, which nullifies total astigmatism at two locations in the visual field. At more peripheral locations, oblique astigmatism dominates axial astigmatism, and the axes of total astigmatism become radially oriented, which is a trait of oblique astigmatism. When eccentricity is specified relative to a foveal line-of-sight that is displaced from the eye's optical axis, asymmetries in the visual field map of total astigmatism can be used to locate the optical axis empirically and to estimate the relative contributions of axial and oblique astigmatism at any retinal location, including the fovea. We anticipate the linear summation rule will benefit many topics in vision science (e.g., peripheral correction, emmetropization, meridional amblyopia) by providing improved understanding of how axial and oblique astigmatism interact to produce net astigmatism. PMID:27607493

  19. Internal energy flows of coma-affected singular beams in low-numerical-aperture systems.

    PubMed

    Bahl, Monika; Singh, Brijesh Kumar; Singh, Rakesh Kumar; Senthilkumaran, P

    2015-04-01

    The circulating phase gradient component of a singular beam gets modified when focused by a low-numerical-aperature system suffering from coma aberration. The gradient due to this coma aberration splits the higher charge vortex into elementary vortices and distributes them spatially. This splitting depends on the charge and polarity of the incident singular beam as well as the sign and magnitude of the aberration coefficient. The transverse component of the Poynting vector field distribution at the focal plane is decomposed into the curl or solenoidal component and divergence or irrotational component using the Helmholtz-Hodge decomposition technique. The solenoidal component that relates to the orbital angular momentum carries the circulating energy, while the irrotational component shows the sources and sinks of the energy. Intriguing results of the study of energy flow around the edge dislocations apart from the point phase defects in the irrotational components are also presented.

  20. Changes of Corneal Wavefront Aberrations in Dry Eye Patients after Treatment with Artificial Lubricant Drops

    PubMed Central

    Lu, Ning; Lin, Fangyu; Huang, Zhu; He, Qin

    2016-01-01

    Purpose. To evaluate the corneal aberration changes in dry eye patients after treatment with artificial eye drops. Methods. Thirty mild to moderate dry eye patients treated with artificial eye drops and twenty comparable dry eye patients were recruited as controls. Anterior corneal aberrations over 3 mm and 5 mm analytical zones including total, 3rd to 5th high order aberrations (HOAs), spherical aberration (SA), and vertical (V-coma) and horizontal coma (H-coma) obtained from corneal topography data at baseline and 2 weeks after treatment were evaluated. Results. For 3 mm zone, trefoils, V-coma, H-coma terms, and 3rd and 5th HOAs were significantly decreased (p < 0.05) in the treatment group. For 5 mm zone, instillation of eye drops reduced H-coma, SA terms, 3rd to 5th orders, and total HOAs all showed a significant decrease (p < 0.05). The root mean square analysis of the Zernike terms also showed similar statistical results. For control group, all individual terms and total HOAs did not have significant changes over 3 mm and 5 mm zones (p > 0.05). Conclusions. Treatment with artificial eye drops can effectively improve the corneal optical quality of dry eye patients by ameliorating the HOAs of anterior corneal surface. PMID:27051526

  1. Myxoedema coma presenting in status epilepticus.

    PubMed

    Woods, K L; Holmes, G K

    1977-01-01

    A 71-year-old woman with myxoedema coma presenting in status epilepticus is reported. Although this complication of myxoedema coma is considered to be fatal the patient described responded dramatically to treatment and remains in good health. PMID:876913

  2. A Reciprocal Transformation for the Constant Astigmatism Equation

    NASA Astrophysics Data System (ADS)

    Hlaváč, Adam; Marvan, Michal

    2014-08-01

    We introduce a nonlocal transformation to generate exact solutions of the constant astigmatism equation z_{yy} + (1/z)_{xx} + 2 = 0. The transformation is related to the special case of the famous Bäcklund transformation of the sine-Gordon equation with the Bäcklund parameter λ = ±1. It is also a nonlocal symmetry.

  3. Efficacy of Wavefront-guided Photorefractive Keratectomy with Iris Registration for Management of Moderate to High Astigmatism by Advanced Personalized Treatment Nomogram

    PubMed Central

    Mohammadpour, Mehrdad; Hashemi, Hassan; Jabbarvand, Mahmoud; Rahmatnejad, Kamran; Sabet, Fatemeh Alsadat

    2016-01-01

    Purpose: To evaluate the efficacy of photorefractive keratectomy (PRK) using the advanced personalized treatment (APT) nomogram for correction of moderate to high astigmatism. Methods: This prospective interventional case series included 60 consecutive eyes of 30 patients undergoing wavefront-guided PRK (Zyoptix 217 Z100 excimer laser, Bausch & Lomb, Munich, Germany) using the APT nomogram and iris registration for myopic astigmatism. Mitomycin-C was applied intraoperatively in all eyes. Ophthalmic examination was performed preoperatively and 1, 3 and 6 months postoperatively. Results: Preoperatively, mean sphere was -1.68 ± 2.08 diopters (D), mean refractive astigmatism was -3.04 ± 1.05 D and mean spherical equivalent (SE) was -3.12 ± 1.77 D. Six months postoperatively, mean sphere was + 0.60 ± 0.64 D (P < 0.005), mean cylinder was -0.43 ± 0.46 D (P < 0.005) and mean SE was + 0.28 ± 0.48 D (P < 0.005). Hyperopic overcorrection (≥ +1.0 D) occurred in 3 (5%) eyes. Postoperatively, root mean square (RMS) of higher order aberrations (HOAs) was significantly increased (P = 0.041). RMS of spherical aberration (Z [4, 0]) showed no significant change after surgery (P = 0.972). Conclusion: Considering the acceptable residual refractive error, low rate of hyperopic overcorrection, acceptable uncorrected visual acuity, and low risk of postoperative corneal haze, PRK using the APT nomogram with iris registration and mitomycin-C use is a safe and effective modality for treatment of moderate to high astigmatism. PMID:27413491

  4. Wavefront aberration statistics in normal eye populations: are they well described by the Kolmogorov model?

    PubMed

    Pailos, Eliseo; Bará, Salvador

    2014-06-01

    This Letter studies the statistics of wavefront aberrations in a sample of eyes with normal vision. Methods relying on the statistics of the measured wavefront slopes are used, not including the aberration estimation stage. Power-law aberration models, an extension of the Kolmogorov one, are rejected by χ2-tests performed on fits to the slope structure function data. This is due to the large weight of defocus and astigmatism variations in normal eyes. Models of only second-order changes are not ruled out. The results are compared with previous works in the area.

  5. Correction of low corneal astigmatism in cataract surgery

    PubMed Central

    Leon, Pia; Pastore, Marco Rocco; Zanei, Andrea; Umari, Ingrid; Messai, Meriem; Negro, Corrado; Tognetto, Daniele

    2015-01-01

    AIM To evaluate and compare aspheric toric intraocular lens (IOL) implantation and aspheric monofocal IOL implantation with limbal relaxing incisions (LRI) to manage low corneal astigmatism (1.0-2.0 D) in cataract surgery. METHODS A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes (102 patients) with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were: visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III (Nidek Co, Japan). Follow-up lasted 6mo. RESULTS The mean uncorrected distance visual acuity (UCVA) and the best corrected visual acuity (BCVA) demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group (P<0.01). No difference was observed in the postoperative endothelial cell count between the two groups. CONCLUSION The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision. PMID:26309869

  6. Wavefront aberrations in eyes of emmetropic and moderately myopic school children and young adults.

    PubMed

    He, Ji C; Sun, Pei; Held, Richard; Thorn, Frank; Sun, Xiuru; Gwiazda, Jane E

    2002-04-01

    Wavefront aberrations were measured using a psychophysical ray-tracing technique in both eyes of 316 emmetropic and moderately myopic school children and young adults. Myopic subjects were found to have greater mean root mean square (RMS) value of wavefront aberrations than emmetropic subjects. Emmetropic adults had the smallest mean RMS, which remained smaller than the values for myopic adults and children and for emmetropic children both when second order Zernike aberrations (astigmatism) and third order Zernike aberrations were removed. Twenty percent of myopic adults had RMS values greater than values for all of the emmetropic adults, with significantly greater values for Zernike aberrations from second to seventh orders. High amounts of wavefront aberrations, which degrade the retinal image, may play a role in the development of myopia.

  7. Correlation Between Stereoacuity and Experimentally Induced Graded Monocular and Binocular Astigmatism

    PubMed Central

    Puthran, Neelam; Gagal, Bhavna

    2016-01-01

    Introduction Stereopsis, the highest grade of binocular single vision, is affected by various factors, such as mis-alignment of visual axes, refractive errors especially anisometropia and astigmatism, both of which may result in amblyopia. There are very few studies in literature regarding the relationship between stereoacuity and refractive errors, especially astigmatism. Aim The present study was conducted to determine the correlation between stereoacuity and experimentally induced graded astigmatism in emmetropes. Materials and Methods A randomized study was conducted on 2000 individuals of either gender, between the ages of 8-35 years, at tertiary care centre attached to a medical college during the period of August 2012 to August 2014, All subjects were emmetropic with normal binocular single vision. Participants were randomly divided into four groups of 500 individuals each. Two groups were subjected to induced myopic astigmatism, either uni-ocularly or binocularly, using + 1.0 D and + 2.0 D cylinders at varying axes i.e., 450, 900 and 1800. Similarily, the remaining two groups were subjected to induced hypermetropic astigmatism, using - 1.0 D and - 2.0D cylinders at varying axes i.e. 450, 900 and 1800. Near stereoacuity was determined by the Titmus Fly Stereo Test, both before and after induction of astigmatism. Statistical analysis was done using paired t-test and ANOVA. Results The mean stereoacuity in emmetropes was 28.81±4.97 seconds of arc. There was a decrease in stereoacuity with increase in dioptric power of astigmatism (p<0.001). Oblique astigmatism reduced the stereoacuity maximally, while stereoacuity was least affected at 180o axis. Hypermetropic astigmatism caused more deterioration in stereoacuity than myopic astigmatism. A gross reduction in stereoacuity was noted in induced monocular astigmatism as against binocular astigmatism. Conclusion This study suggests that stereoacuity is significantly affected by even minor degrees of monocular or

  8. Generalized design of a zero-geometric-loss, astigmatism-free, modified four-objective multipass matrix system.

    PubMed

    Guo, Yin; Sun, LiQun; Yang, Zheng; Liu, Zilong

    2016-02-20

    During this study we constructed a generalized parametric modified four-objective multipass matrix system (MMS). We used an optical system comprising four asymmetrical spherical mirrors to improve the alignment process. The use of a paraxial equation for the design of the front transfer optics yielded the initial condition for modeling our MMS. We performed a ray tracing simulation to calculate the significant aberration of the system (astigmatism). Based on the calculated meridional and sagittal focus positions, the complementary focusing mirror was easily designed to provide an output beam free of astigmatism. We have presented an example of a 108-transit multipass system (5×7 matrix arrangement) with a relatively larger numerical aperture source (xenon light source). The whole system exhibits zero theoretical geometrical loss when simulated with Zemax software. The MMS construction strategy described in this study provides an anastigmatic output beam and the generalized approach to design a controllable matrix spot pattern on the field mirrors. Asymmetrical reflective mirrors aid in aligning the whole system with high efficiency. With the generalized design strategy in terms of optics configuration and asymmetrical fabrication method in this paper, other kinds of multipass matrix system coupled with different sources and detector systems also can be achieved. PMID:26906598

  9. [Results of refractive surgery in hyperopic and combined astigmatism].

    PubMed

    Vlaicu, Valeria

    2013-01-01

    The refractive surgery includes a lot of procedures for changing the refraction of the eye to obtain a better visual acuity with no glasses or contact lenses. LASIK is the most commonly performed laser refractive surgery today. The goal is to present the postoperative evolution of the refraction and visual acuity after LASIK for Mixed and Hyperopic Astigmatism. The results show that LASIK is safe and predictible if we have well performed interventions and well-selected patients.

  10. Water Chemistry in Cometary Comae

    NASA Astrophysics Data System (ADS)

    Boice, D. C.

    2005-12-01

    Water chemistry is central in understanding the physics and chemistry of cometary comae. A rather advanced knowledge of water chemistry has been attained from studies of various comets via ground-based observations and in situ spacecraft measurements, especially the Giotto encounter with comet 1P/Halley. Photochemistry and the effects of photoelectrons that react via electron impact reactions, ion-molecule reactions, and the interaction with solar wind plasma are important processes that affect the overall composition and ionization state in the coma. However, initial results from the PEPE instrument onboard Deep Space 1 (DS1) concerning water-group ions around closest approach significantly differ from those expected from model results, challenging conventional notions. We have attempted to reconcile these differences in ion composition between the DS1 in situ measurements and model results with an extensive modeling investigation, unique from previous studies. This work should be relevant to past, on-going, and future spacecraft missions to comets.

  11. High-resolution OCT balloon imaging catheter with astigmatism correction

    PubMed Central

    Xi, Jiefeng; Huo, Li; Wu, Yicong; Cobb, Michael J.; Hwang, Joo Ha; Li, Xingde

    2014-01-01

    We report new optics designs for an optical coherence tomography (OCT) balloon imaging catheter to achieve diffraction-limited high resolution at a large working distance and enable the correction of severe astigmatism in the catheter. The designs employed a 1 mm diameter gradient-index lens of a properly chosen pitch number and a glass rod spacer to fully utilize the available NA of the miniature optics. Astigmatism caused by the balloon tubing was analyzed, and a method based on a cylindrical reflector was proposed and demonstrated to compensate the astigmatism. A catheter based on the new designs was successfully developed with a measured diffraction-limited lateral resolution of ∼21 μm, a working distance of ∼ 11 –12 mm, and a round-shape beam profile. The performance of the OCT balloon catheter was demonstrated by 3D full-circumferential imaging of a swine esophagus in vivo along with a high-speed, Fourier-domain, mode-locked swept-source OCT system. PMID:19571960

  12. Excimer laser surgery for myopia and myopic astigmatism.

    PubMed

    Hadden, O B; Morris, A T; Ring, C P

    1995-08-01

    Photorefractive keratectomy using the Summit Excimer Laser has been carried out on 1333 eyes with myopia or myopic astigmatism which have been followed up for six months or longer. Of those, 607 have been followed up for one year. Of the eyes with myopia or myopic astigmatism of up to 3 dioptres spherical equivalent, at one year 85.6% had unaided vision of 6/6, 97.2% 6/9 or better, and 99.4% 6/12 or better. Of the eyes between -3.25 and -6.00 dioptres spherical equivalent at one year 72.1% achieved 6/6 vision unaided, 88.8% 6/9 or better, and 94.2% 6/12 or better. Of the eyes between -6.25 and -10.00 dioptres, at one year 49.6% achieved 6/6 vision unaided, 76.1% 6/9 or better and 88.0% 6/12 or better. To achieve these figures, 28% of the patients had astigmatic keratotomy, either two or three weeks before photorefractive keratectomy, or at the same time as photorefractive keratectomy. Photorefractive keratectomy is as predictable as radial keratotomy in eyes of under 6 dioptres myopia, but is more predictable than radial keratotomy in higher myopia. Photorefractive keratectomy has the advantages of leaving an eye which is structurally sound, and without diurnal variation of focusing. PMID:8534441

  13. Comet coma sample return instrument

    NASA Technical Reports Server (NTRS)

    Albee, A. L.; Brownlee, Don E.; Burnett, Donald S.; Tsou, Peter; Uesugi, K. T.

    1994-01-01

    The sample collection technology and instrument concept for the Sample of Comet Coma Earth Return Mission (SOCCER) are described. The scientific goals of this Flyby Sample Return are to return to coma dust and volatile samples from a known comet source, which will permit accurate elemental and isotopic measurements for thousands of individual solid particles and volatiles, detailed analysis of the dust structure, morphology, and mineralogy of the intact samples, and identification of the biogenic elements or compounds in the solid and volatile samples. Having these intact samples, morphologic, petrographic, and phase structural features can be determined. Information on dust particle size, shape, and density can be ascertained by analyzing penetration holes and tracks in the capture medium. Time and spatial data of dust capture will provide understanding of the flux dynamics of the coma and the jets. Additional information will include the identification of cosmic ray tracks in the cometary grains, which can provide a particle's process history and perhaps even the age of the comet. The measurements will be made with the same equipment used for studying micrometeorites for decades past; hence, the results can be directly compared without extrapolation or modification. The data will provide a powerful and direct technique for comparing the cometary samples with all known types of meteorites and interplanetary dust. This sample collection system will provide the first sample return from a specifically identified primitive body and will allow, for the first time, a direct method of matching meteoritic materials captured on Earth with known parent bodies.

  14. Astigmatism after a large scleral pocket incision in extracapsular cataract extraction.

    PubMed

    Lemagne, J M; Kallay, O

    1993-09-01

    In this four-month prospective study, we measured astigmatism in 116 patients who had extracapsular cataract extraction through a 13 mm scleral pocket incision. In one group, the wound was closed with five radial 10-0 polypropylene sutures. Early and late postoperative astigmatism in this group was approximately 2 diopters (D), but a significant shift to against-the-rule astigmatism occurred. In a second group, an additional 10-0 polypropylene horizontal suture was placed anteriorly to the radial suture at the 12 o'clock meridian. This reduced the against-the-rule astigmatic decay. Moreover, this group had less postoperative astigmatism. Mean corneal astigmatism was 2.27 D at one week, 1.76 D at one month, 1.37 D at two months, and 1.70 D at four months. In neither group was cutting the sutures necessary. PMID:8229717

  15. Vision improvement by correcting higher-order aberrations with customized soft contact lenses in keratoconic eyes

    NASA Astrophysics Data System (ADS)

    Sabesan, Ramkumar; Jeong, Tae Moon; Carvalho, Luis; Cox, Ian G.; Williams, David R.; Yoon, Geunyoung

    2007-04-01

    Higher-order aberration correction in abnormal eyes can result in significant vision improvement, especially in eyes with abnormal corneas. Customized optics such as phase plates and customized contact lenses are one of the most practical, nonsurgical ways to correct these ocular higher-order aberrations. We demonstrate the feasibility of correcting higher-order aberrations and improving visual performance with customized soft contact lenses in keratoconic eyes while compensating for the static decentration and rotation of the lens. A reduction of higher-order aberrations by a factor of 3 on average was obtained in these eyes. The higher-order aberration correction resulted in an average improvement of 2.1 lines in visual acuity over the conventional correction of defocus and astigmatism alone.

  16. Astigmatism-corrected Czerny-Turner imaging spectrometer for broadband spectral simultaneity

    SciTech Connect

    Xue Qingsheng

    2011-04-01

    A low-cost, broadband, astigmatism-corrected Czerny-Turner arrangement with a fixed plane grating is proposed. A wedge cylindrical lens is used to correct astigmatism over a broadband spectral range. The principle and method of astigmatism correction are described in detail. We compare the performance of this modified Czerny-Turner arrangement with that of the traditional Czerny-Turner arrangement by using a practical Czerny-Turner imaging spectrometer example.

  17. Transverse-mode astigmatism in a diode-pumped unstable resonator Nd:YVO(4) laser.

    PubMed

    Cheng, Y J; Fanning, C G; Siegman, A E

    1997-02-20

    We have observed a sizable astigmatism in the output beam from a diode-pumped unstable resonator Nd:YVO(4) laser operating in a single polarization and a single-longitudinal and transverse mode. The anisotropic index of refraction of the vanadate crystal has been identified as the source of this astigmatism. A theoretical prediction of the eigenmode astigmatism based on this index anisotropy is consistent with our experimental measurements. PMID:18250780

  18. Finite element simulation of arcuates for astigmatism correction.

    PubMed

    Lanchares, Elena; Calvo, Begoña; Cristóbal, José A; Doblaré, Manuel

    2008-01-01

    In order to simulate the corneal incisions used to correct astigmatism, a three-dimensional finite element model was generated from a simplified geometry of the anterior half of the ocular globe. A hyperelastic constitutive behavior was assumed for cornea, limbus and sclera, which are collagenous materials with a fiber structure. Due to the preferred orientations of the collagen fibrils, corneal and limbal tissues were considered anisotropic, whereas the sclera was simplified to an isotropic one assuming that fibrils are randomly disposed. The reference configuration, which includes the initial strain distribution that balances the intraocular pressure, is obtained by an iterative process. Then the incisions are simulated. The final positions of the nodes belonging to the incised meridian and to the perpendicular one are fitted by both radii of curvature, which are used to calculate the optical power. The simulated incisions were those specified by Lindstrom's nomogram [Chu, Y., Hardten, D., Lindquist, T., Lindstrom, R., 2005. Astigmatic keratotomy. Duane's Ophthalmology. Lippincott Williams and Wilkins, Philadelphia] to achieve 1.5, 2.25, 3.0, 4.5 and 6.0D of astigmatic change, using the next values for the parameters: length of 45 degrees , 60 degrees and 90 degrees , an optical zone of 6mm, single or paired incisions. The model gives results similar to those in Lindstrom's nomogram [Chu et al., 2005] and can be considered a useful tool to plan and simulate refractive surgery by predicting the outcomes of different sorts of incisions and to optimize the values for the parameters involved: depth, length, position. PMID:18177656

  19. Propagation of the Lissajous singularity dipole through an astigmatic lens

    NASA Astrophysics Data System (ADS)

    Chen, Haitao; Gao, Zenghui; Zou, Xuefang; Huang, Weigang; Wang, Fanhou

    2013-11-01

    The propagation was investigated of a pair of Lissajous singularities of opposite singularity index called the Lissajous singularity dipole (LSD) through an astigmatic lens. It is shown that after passing through the lens the positions of the singularities are inverted and more than two LSDs occur. Changes in the degree of polarization of the LSDs as well as in the shape of the Lissajous figures also occur. In addition, Lissajous singularities may take place at the focal plane, and a single Lissajous singularity may appear and vanish under certain conditions. The results are compared with those of previous work.

  20. Amiodarone-induced myxoedema coma.

    PubMed

    Hassan, Syed; Ayoub, Walaa; Hassan, Mona; Wisgerhof, Max

    2014-01-01

    A 62-year-old man was found to have bradycardia, hypothermia and respiratory failure 3 weeks after initiation of amiodarone therapy for atrial fibrillation. Thyroid-stimulating hormone was found to be 168 μIU/mL (nl. 0.3-5 μIU/mL) and free thyroxine (FT4) was <0.2 ng/dL (nl. 0.8-1.8 ng/dL). He received intravenous fluids, vasopressor therapy and stress dose steroids; he was intubated and admitted to the intensive care unit. He received 500 μg of intravenous levothyroxine in the first 18 h of therapy, and 150 µg intravenous daily thereafter. Haemodynamic improvement, along with complete recovery of mental status, occurred after 48 h. Twelve hours after the initiation of therapy, FT4 was 0.96 ng/dL. The patient was maintained on levothyroxine 175 (g POorally daily. A thyroid ultrasound showed diffuse heterogeneity. The 24 hour excretion of iodine was 3657 (mcg (25-756 ( mcg). The only two cases of amiodarone-induced myxoedema coma in the literature report patient death despite supportive therapy and thyroid hormone replacement. This case represents the most thoroughly investigated case of amiodarone-induced myxoedema coma with a history significant for subclinical thyroid disease. PMID:24729111

  1. Amiodarone-induced myxoedema coma

    PubMed Central

    Hassan, Syed; Ayoub, Walaa; Hassan, Mona; Wisgerhof, Max

    2014-01-01

    A 62-year-old man was found to have bradycardia, hypothermia and respiratory failure 3 weeks after initiation of amiodarone therapy for atrial fibrillation. Thyroid-stimulating hormone was found to be 168 μIU/mL (nl. 0.3–5 μIU/mL) and free thyroxine (FT4) was <0.2 ng/dL (nl. 0.8–1.8 ng/dL). He received intravenous fluids, vasopressor therapy and stress dose steroids; he was intubated and admitted to the intensive care unit. He received 500 μg of intravenous levothyroxine in the first 18 h of therapy, and 150 µg intravenous daily thereafter. Haemodynamic improvement, along with complete recovery of mental status, occurred after 48 h. Twelve hours after the initiation of therapy, FT4 was 0.96 ng/dL. The patient was maintained on levothyroxine 175 (g POorally daily. A thyroid ultrasound showed diffuse heterogeneity. The 24 hour excretion of iodine was 3657 (mcg (25–756 ( mcg). The only two cases of amiodarone-induced myxoedema coma in the literature report patient death despite supportive therapy and thyroid hormone replacement. This case represents the most thoroughly investigated case of amiodarone-induced myxoedema coma with a history significant for subclinical thyroid disease. PMID:24729111

  2. Quasi two-dimensional astigmatic solitons in soft chiral metastructures.

    PubMed

    Laudyn, Urszula A; Jung, Paweł S; Karpierz, Mirosław A; Assanto, Gaetano

    2016-01-01

    We investigate a non-homogeneous layered structure encompassing dual spatial dispersion: continuous diffraction in one transverse dimension and discrete diffraction in the orthogonal one. Such dual diffraction can be balanced out by one and the same nonlinear response, giving rise to light self-confinement into astigmatic spatial solitons: self-focusing can compensate for the spreading of a bell-shaped beam, leading to quasi-2D solitary wavepackets which result from 1D transverse self-localization combined with a discrete soliton. We demonstrate such intensity-dependent beam trapping in chiral soft matter, exhibiting one-dimensional discrete diffraction along the helical axis and one-dimensional continuous diffraction in the orthogonal plane. In nematic liquid crystals with suitable birefringence and chiral arrangement, the reorientational nonlinearity is shown to support bell-shaped solitary waves with simple astigmatism dependent on the medium birefringence as well as on the dual diffraction of the input wavepacket. The observations are in agreement with a nonlinear nonlocal model for the all-optical response. PMID:26975651

  3. Photographic simulation of off-axis blurring due to chromatic aberration in spectacle lenses.

    PubMed

    Doroslovački, Pavle; Guyton, David L

    2015-02-01

    Spectacle lens materials of high refractive index (nd) tend to have high chromatic dispersion (low Abbé number [V]), which may contribute to visual blurring with oblique viewing. A patient who noted off-axis blurring with new high-refractive-index spectacle lenses prompted us to do a photographic simulation of the off-axis aberrations in 3 readily available spectacle lens materials, CR-39 (nd = 1.50), polyurethane (nd = 1.60), and polycarbonate (nd = 1.59). Both chromatic and monochromatic aberrations were found to cause off-axis image degradation. Chromatic aberration was more prominent in the higher-index materials (especially polycarbonate), whereas the lower-index CR-39 had more astigmatism of oblique incidence. It is important to consider off-axis aberrations when a patient complains of otherwise unexplained blurred vision with a new pair of spectacle lenses, especially given the increasing promotion of high-refractive-index materials with high chromatic dispersion.

  4. [Circulatory survival of irreversible comas].

    PubMed

    Cartier, F; Chevet, D; Garré, M; Launois, B; Thomas, R; Le Pollès, R

    1975-01-18

    On the basis of a series of 53 cases of irreversible coma maintained in circulatory survival with the aim of removing the kidneys, the authors discuss the mode of treatment, with particular reference to the intravenous fluids used and the use of medications influencing the circulation. Fluid and electrolytes given must be adjusted hourly to ensure the exact replacement of urinary losses. Isoprotenerol is the only medication usually necessary. In the event of circulatory insufficiency, which is difficult to foresee and hence prevent, immediate volume expansion in a short a time as possible and isoprotenerol most frequently correct the situation (14 out of 17 cases). Thus effective circulation may be maintained until the kidneys are removed (48 out of 53 cases). 92 p.cent of the grafted kidneys functioned from the first day onwards. PMID:1093120

  5. [Coma: a new humanistic discipline].

    PubMed

    Costantini, M

    1993-01-01

    Two researches merge together in this article: the former originates in coma clinical practice and aims at reaching a more abstract formulation, while the latter originates in the theory of narrative and tries to find practical applications. The interest of this merger lies in opening up a new field of study, comatics, whose object is to conceive the best possible conditions for comatose people, for specific varieties of comatose people and even for this or that individual comatose person to fit back into social life, which involves grasping meaning and clues and signals and signs, and finding one's way about in the circuit of communication. Comatics, in short, is semiotics as applied to awakening from comatose states.

  6. High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric, aberration correcting monofocal intraocular lens

    PubMed Central

    Kretz, Florian T A; Tandogan, Tamer; Khoramnia, Ramin; Auffarth, Gerd U

    2015-01-01

    AIM To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting, monofocal intraocular lens (IOL). METHODS Twenty-one patients (34 eyes) aged 50 to 83y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL (Tecnis ZCB00, Abbott Medical Optics). Three months after surgery they were examined for uncorrected (UDVA) and corrected distance visual acuity (CDVA), contrast sensitivity (CS) under photopic and mesopic conditions with and without glare source, ocular high order aberrations (HOA, Zywave II) and retinal straylight (C-Quant). RESULTS Postoperatively, patients achieved a postoperative CDVA of 0.0 logMAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27 (primary coma components) and -0.04±0.16 (spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed (P≥0.28). CONCLUSION The implantation of an aspherical aberration correcting monofocal IOL after cataract surgery resulted in very low residual higher order aberration (HOA) and normal straylight. PMID:26309872

  7. Coma compensation of o-ring driven liquid-filled lenses

    NASA Astrophysics Data System (ADS)

    Shaw, Dein; Lin, Chih-Wei

    2009-03-01

    The purpose of this study was to analyze the coma compensation of bi-convex o-ring driven liquid-filled lenses. In a previous study, the o-ring driven liquid-filled lens was composed of a base plate, a glass covered liquid container, an elastic membrane, an o-ring, a spring, and three hand-driven screws. The movement of the ring is used to control the focal length or the focus position. However, the o-ring driven liquid lens exhibited a coma effect when trying to use it to tilt the direction of light. To resolve this problem, in this study the bi-convex o-ring driven liquid-filled lens was constructed of two single o-ring driven liquid-filled lenses, and a coma compensation analysis of this new design is carried out. zemax software was used to construct the model, and the Zernike polynomials were used to estimate the compensation result. According to the simulation results, the following two actions could compensate for the initial coma aberration: (1) the same tilt direction of the front and back lenses; (2) increased the curvature of the back lens.

  8. Accuracy of the Spot and Plusoptix photoscreeners for detection of astigmatism

    PubMed Central

    Crescioni, Mabel; Miller, Joseph M.; Harvey, Erin M.

    2015-01-01

    Purpose To evaluate the accuracy of the Spot (V2.0.16) and Plusoptix S12 (ROC4, V6.1.4.0) photoscreeners in detecting astigmatism meeting AAPOS referral criteria in students from a population with high prevalence of astigmatism. Methods Students attending grades 3–8 on the Tohono O’odham reservation were examined. Screening was attempted with both the Spot and Plusoptix photoscreeners. Results were compared to cycloplegic refraction. Screening attempts providing no estimate of refractive error were considered fail/refer. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of refractive errors were determined using AAPOS referral criteria and receiver operating characteristic area under the curve (ROC AUC) analysis was conducted for measures of astigmatism. Agreement between screening and cycloplegic refraction measurements of astigmatism, spherical equivalent, and anisometropia were assessed using t tests and correlation analyses. Results A total of 209 students were included. Of the total, 116 (55%) met examination-positive criteria based on cycloplegic refraction, with 105 of those (90%) meeting the criterion for astigmatism. Measurements success rates were 97% for Spot and 54% for Plusoptix. Comparing the Spot and the Plusoptix, sensitivity was 96% versus 100%, specificity was 87% versus 61%, PPV was 90% versus 76%, and NPV was 94% versus 100% for detection of refractive error. Both screeners overestimated astigmatism by 1/3 D to 2/3 D. AUC for astigmatism was 0.97 for Spot and 0.83 for Plusoptix. Conclusions In this highly astigmatic population, the Spot and the Plusoptix had similar sensitivity, but the Spot had better specificity and measurement success rates. Compared with results from study samples with lower rates of astigmatism, our results highlight the need to assess the ability of screening instruments to detect individual types of refractive errors. PMID:26486025

  9. Models for Cometary Comae Containing Negative Ions

    NASA Technical Reports Server (NTRS)

    Cordiner, M. A.; Charnley, S. B.

    2012-01-01

    The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of IP/Halley. The anions O(-), OH(-), C(-), CH(-) and CN(-) have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu [I]. Organic molecular anions such as C4H(-) and C6H(-) are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been fully explored. We present details of our new models for the chemistry of cometary comae that include atomic and molecular anions. We calculate the impact of these anions on the charge balance and examine their importance for cometary coma chemistry.

  10. [Now soft toric contact lenses; silicone hydrogel lens for astigmatism].

    PubMed

    Radu, Simona

    2006-01-01

    Soft toric contact lenses are a good alternative for the optical correction of astigmatism. They provide a wide visual field, quick adaptation process, negligible aniseikonia, together with enhanced comfort and reduced incidence of complications introduced by the lenses for frequent replacement. Still practitioners do not recommend them proactively and the satisfaction obtained by the patients is not high enough. This paper presents two recent studies that investigate the opinions of specialists and contact lens wearers and introduce a new contact lens, with an original design, born after 30 years of domination of only 2 modalities of rotational stabilization: prism ballast and dual thin zones. The lens is manufactured using a silicon-hydrogel material of 2-nd generation that provides sustained comfort and better oxygenation. PMID:16773940

  11. Experimental validation of a novel imaging scheme to eliminate astigmatism

    NASA Astrophysics Data System (ADS)

    Fierroz, S.; Bitter, M.; Delgado-Aparicio, L.; Hill, K. W.; Pablant, N.; Scott, S.; Scotti, F.; Rice, J. E.

    2010-11-01

    Recent papers by Bitter et al.^1-3 have proposed novel imaging schemes to eliminate astigmatism by matched pairs of spherically bent crystals or reflectors. These imaging schemes should allow stigmatic (or point-to point) imaging at arbitrarily large angles of incidence and be applicable to a broad spectrum of the electromagnetic radiation, including microwaves, visible light, EUV radiation, and x-rays, if appropriate spherically bent reflectors are used. This paper presents experimental results from tests of one of these imaging schemes with visible light, which validate the concept of this scheme and show that stigmatic imaging of objects with areas of about 5 mm x 5 mm is possible. ^1M. Bitter et al, Rev Sci. Instrum. 79, 10E927 (2008); ^2M. Bitter et al., J. Xray Sci. Technol. 17, 153 (2009); ^3M. Bitter et al., J. Phys. B: At. Mol. Opt. Phys. 43, 144011 (2010)

  12. Risk Factors for Astigmatism in the Vision in Preschoolers (VIP) Study

    PubMed Central

    Huang, Jiayan; Maguire, Maureen G.; Ciner, Elise; Kulp, Marjean Taylor; Cyert, Lynn A.; Quinn, Graham E.; Orel-Bixler, Deborah; Moore, Bruce; Ying, Gui-Shuang

    2014-01-01

    Purpose To determine demographic and refractive risk factors for astigmatism in the Vision in Preschoolers (VIP) Study. Methods Three- to 5-year old Head Start preschoolers (N=4,040) from 5 clinical centers underwent comprehensive eye examinations by study-certified optometrists and ophthalmologists, including monocular visual acuity (VA) testing, cover testing, and cycloplegic retinoscopy. Astigmatism was defined as the presence of ≥ +1.5 diopters (D) cylinder in either eye, measured with cycloplegic refraction. The associations of risk factors with astigmatism were evaluated using the odds ratio (OR) and its 95% confidence intervals (95% CI) from logistic regression models. Results Among 4,040 VIP Study participants over-representing children with vision disorders, 687 (17%) had astigmatism, and majority of astigmatism was with-the-rule (83.8%). In multivariate analyses, African-American (OR=1.65, 95% CI: 1.22–2.24), Hispanic (OR=2.25, 95% CI: 1.62–3.12) and Asian children (OR=1.76, 95% CI: 1.06–2.93) were more likely to have astigmatism compared with non-Hispanic white children, while American Indian children were less likely to have astigmatism than Hispanic, African American and Asian children (P<0.0001). Refractive error was associated with astigmatism in a non-linear manner, with an OR of 4.50 (95% CI: 3.00 – 6.76) for myopia (≤ −1.0D in spherical equivalent), and 1.55 (95% CI: 1.29 –1.86) for hyperopia (≥ +2.0D) when compared to children without refractive error (> −1.0D, < +2.0D). There was a trend of an increasing percentage of astigmatism among older children (linear trend p=0.06). The analysis for risk factors of with-the-rule astigmatism provided similar results. Conclusions Among Head Start preschoolers, Hispanic ethnicity, African-American and Asian race, myopic and hyperopic refractive error were associated with an increased risk of astigmatism, consistent with findings from the population-based Multi-ethnic Pediatric Eye Disease

  13. Gurnis, McComas receive Macelwane Medals

    NASA Astrophysics Data System (ADS)

    O'Connell, Richard; Gurnis, Michael; Burch, James L.; McComas, David J.

    Michael Gurnis and David J. McComas were honored as recipients of James B. Macelwane Medals at the AGU 1993 Spring Meeting in Baltimore last May. The medal recognizes significant contributions to the geophysical sciences by a young scientist of outstanding ability. Richard O'Connell presented Gurnis' medal, and James L. Burch presented McComas' medal. Citations and responses are presented below.

  14. Chemical and Hydrodynamical Models of Cometary Comae

    NASA Technical Reports Server (NTRS)

    Charnley, Steven

    2012-01-01

    Multi-fluid modelling of the outflowing gases which sublimate from cometary nuclei as they approach the Sun is necessary for understanding the important physical and chemical processes occurring in this complex plasma. Coma chemistry models can be employed to interpret observational data and to ultimately determine chemical composition and structure of the nuclear ices and dust. We describe a combined chemical and hydrodynamical model [1] in which differential equations for the chemical abundances and the energy balance are solved as a function of distance from the cometary nucleus. The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of 1P/Halley. The anions O(-), OH(-), C(-), CH(-) and CN(-) have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu [2]. Organic molecular anions such as C4H(-) and C6H(-) are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas-phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been fully explored. We present details of new models for the chemistry of cometary comae that include atomic and molecular anions and calculate the impact of these anions on the coma physics and chemistry af the coma.

  15. Interpreting Chromosome Aberration Spectra

    NASA Technical Reports Server (NTRS)

    Levy, Dan; Reeder, Christopher; Loucas, Bradford; Hlatky, Lynn; Chen, Allen; Cornforth, Michael; Sachs, Rainer

    2007-01-01

    Ionizing radiation can damage cells by breaking both strands of DNA in multiple locations, essentially cutting chromosomes into pieces. The cell has enzymatic mechanisms to repair such breaks; however, these mechanisms are imperfect and, in an exchange process, may produce a large-scale rearrangement of the genome, called a chromosome aberration. Chromosome aberrations are important in killing cells, during carcinogenesis, in characterizing repair/misrepair pathways, in retrospective radiation biodosimetry, and in a number of other ways. DNA staining techniques such as mFISH ( multicolor fluorescent in situ hybridization) provide a means for analyzing aberration spectra by examining observed final patterns. Unfortunately, an mFISH observed final pattern often does not uniquely determine the underlying exchange process. Further, resolution limitations in the painting protocol sometimes lead to apparently incomplete final patterns. We here describe an algorithm for systematically finding exchange processes consistent with any observed final pattern. This algorithm uses aberration multigraphs, a mathematical formalism that links the various aspects of aberration formation. By applying a measure to the space of consistent multigraphs, we will show how to generate model-specific distributions of aberration processes from mFISH experimental data. The approach is implemented by software freely available over the internet. As a sample application, we apply these algorithms to an aberration data set, obtaining a distribution of exchange cycle sizes, which serves to measure aberration complexity. Estimating complexity, in turn, helps indicate how damaging the aberrations are and may facilitate identification of radiation type in retrospective biodosimetry.

  16. Numerical simulation of astigmatic liquid lenses tuned by a stripe electrode.

    PubMed

    Lima, N C; Cavalli, A; Mishra, K; Mugele, F

    2016-02-22

    We propose a new design for tuning the astigmatism of liquid micro-lenses using electric field and hydrostatic pressure as control parameters. We explore the feasibility and operating range of the lens with a self-consistent numerical calculation of the electric field distribution and the shape of the two-phase interface. Equilibrium shapes, including surface profiles parallel and perpendicular to a stripe electrode, are extracted to determine the astigmatism. The wavefronts are decomposed into Zernike polynomials under zero defocus conditions using a commercial ray-tracing software. We observe that the global curvature of the lens is primarily controlled by the hydrostatic pressure, while asphericity and astigmatism are controlled by the electric field. For optimized electrode geometries and simultaneous control of pressure and electric fields the astigmatism can be tuned from Z6 = 0…0.38 μm with minor changes in the focal length. PMID:26907069

  17. Coma Cluster: Hot and Cool Mixture

    NASA Astrophysics Data System (ADS)

    Ishizaka, Chiharu; Mineshige, Shin

    1996-06-01

    ASCA has revealed a rather complex temperature structure in the intraclus ter medium (ICM) around the Coma cluster. Significantly, hot parts (with kT g eq 10 keV) are located far ( ~ 1 Mpc) distant from both the center of the Coma cluster and the galaxy group NGC 4839. There also exist relatively cool re gions (with kT <~ 5 keV). Using N-body + Hydrodynamic simulations, w e have demonstrated that such an observed temperature distribution is naturally accounted for if the subgroup NGC 4839 passed through the center of the Coma c luster about 1 Gyr ago, which was first proposed by Burns et al. When the subc luster passed through the Coma cluster, the ICM in the subcluster was compresse d due to the ram pressure by the ICM in the Coma, and there formed a bow shock with an arc shape just between the two centers. The ICM has thus been heated th ere, emitting hard radiation. A part of the ICM is reflected by the shock front , and flows backward (with respect to the! direction of the subcluster motio n) around the Coma cluster center, being cooled due to an adiabatic expansion. After detouring the center, cooled gas collides with each other at the opposit e side of the Coma cluster (to the place of the subcluster), producing another hot region. These simulate d features are in good agreement with what ASCA found. Further, we present rath er unique features in the temperature profiles that can be caused by a merger ( or an encounter) with a subgroup of galaxies.

  18. Wavefront aberration function in terms of R. V. Shack's vector product and Zernike polynomial vectors.

    PubMed

    Gray, Robert W; Rolland, Jannick P

    2015-10-01

    Previous papers have shown how, for rotationally symmetric optical imaging systems, nodes in the field dependence of the wavefront aberration function develop when a rotationally symmetric optical surface within an imaging optical system is decentered and/or tilted. In this paper, we show how Shack's vector product (SVP) can be used to express the wavefront aberration function and to define vectors in terms of the Zernike polynomials. The wavefront aberration function is then expressed in terms of the Zernike vectors. It is further shown that SVP fits within the framework of two-dimensional geometric algebra (GA). Within the GA framework, an equation for the third-order node locations for the binodal astigmatism term that emerge in the presence of tilts and decenters is then demonstrated. A computer model of a three-mirror telescope system is used to demonstrate the validity of the mathematical development. PMID:26479937

  19. Coma Chemistry of Sun-grazing Comets

    NASA Astrophysics Data System (ADS)

    Charnley, Steven B.; Cordiner, Martin A.; Milam, Stefanie N.; Gicquel, Adeline

    2014-11-01

    The recent apparition of comet C/2012 S1 (ISON), and its disruption during perihelion passage, has motivated numerous observations of the associated variations in the gas and dust composition. More generally, comet ISON has regenerated interest in the physics and chemistry of Sun-grazing comets. Chemical models of cometary comae have typically always been developed to model comets at about 1 AU and beyond [1]. Apart from one early coma chemistry model [2], which calculated the coma chemistry of a comet at 0.125 AU with assumed single-fluid physics, there have been no detailed studies of coma chemistry at the small heliocentric distances experienced by comet ISON and other Sun-grazing comets.In this contribution we will discuss the various physical and chemical processes that have to be considered when modeling the comae of Sun-grazing comets. We will present comet models in which the physical and chemical structures of the multi-fluid flow are calculated self-consistently [3] as a function of decreasing heliocentric distance.[1] Rodgers, S.D., Charnley S.B., Boice, D.C. & Huebner, W.F. (2004) In COMETS II, Eds. Festou, M., Keller, H.U. & Weaver, H.A., University of Arizona Press, 505-522 [2] Swift, M.B. & Mitchell, G.F. (1978) Icarus, 47, 412 [3] Rodgers, S.D. & Charnley, S.B. (2002) MNRAS, 330, 660This work was supported by NASA's Planetary Atmospheres and Planetary Astronomy Programs.

  20. Modeling the coma of 2060 Chiron

    NASA Technical Reports Server (NTRS)

    Boice, D. C.; Konno, I.; Stern, S. Alan; Huebner, W. F.

    1991-01-01

    Observations of comet-like activity and a resolved coma have established that 2060 Chiron is a comet. Determinations of its radius range from 65 to 200 km. This unusually large size for a comet suggests that the atmosphere of Chiron is intermediate to the tightly bound, thin atmospheres typical of planets and satellite and the greatly extended atmospheres in free expansion typical of cometary comae. Under certain conditions it may gravitationally bind an atmosphere that is thick compared to its size, while a significant amount of gas escapes to an extensive exosphere. These attributes coupled with reports of sporadic outbursts at large heliocentric distances and the identification of CN in the coma make Chiron a challenging object to model. Simple models of gas production and the dusty coma were recently presented but a general concensus on many basic features has not emerged. Development was begun on a more complete coma model of Chiron. The objectives are to report progress on this model and give the preliminary results for understanding Chiron.

  1. Aberration corrected emittance exchange

    NASA Astrophysics Data System (ADS)

    Nanni, E. A.; Graves, W. S.

    2015-08-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (rf) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by multiple orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dogleg emittance exchange setup with a five cell rf deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of an EEX line with emittances differing by four orders of magnitude, i.e., an initial transverse emittance of 1 pm-rad is exchanged with a longitudinal emittance of 10 nm-rad.

  2. Acute Effect of Cigarette Smoking on Pupil Size and Ocular Aberrations: A Pre- and Postsmoking Study

    PubMed Central

    Erdem, Uzeyir; Gundogan, Fatih C.; Dinc, Umut Aslı; Yolcu, Umit; Ilhan, Abdullah; Altun, Salih

    2015-01-01

    Aim. To evaluate the acute effects of cigarette smoking on photopic and mesopic pupil sizes and wavefront aberrations. Methods. Cigarette smoker volunteers were recruited in the study. Photopic and mesopic pupil sizes and total ocular aberrations were measured before smoking and immediately after smoking. All volunteers were asked to smoke a single cigarette containing 1.0 mg nicotine. Pupil sizes and total ocular aberrations were assessed by optical path difference scanning system (OPD-Scan II ARK-10000, NIDEK). Only the right eyes were considered for statistical analysis. The changes of pupil size and total ocular aberrations after smoking were tested for significance by Wilcoxon signed ranks test. Results. Mean photopic pupil size decreased from 3.52 ± 0.73 mm to 3.29 ± 0.58 mm (P = 0.001) after smoking. Mean mesopic pupil size was also decreased from 6.42 ± 0.75 mm to 6.14 ± 0.75 mm after smoking (P = 0.001). There was a decrease in all the measured components of aberrations (total wavefront aberration, higher-order aberration, total coma, total trefoil, total tetrafoil, total spherical aberration and total higher-order aberration) after smoking; however the differences were insignificant for all (P > 0.05). Conclusion. Our results indicate that pupil constricts after smoking. On the other hand, smoking does not alter ocular aberrations. PMID:25699189

  3. Ray vector fields, prismatic effect, and thick astigmatic optical systems.

    PubMed

    Harris, W F

    1996-06-01

    The application of the concept of ray vector fields to optical systems is reexamined. Paraxial or linear optics defines a four-dimensional ray vector field for any optical system: the vector field maps the incident ray vector into the emergent ray vector. In the case of thin systems, including thin astigmatic lenses, one can define a vector field of reduced dimensionality: the vector field is two-dimensional and maps the ray's incident position into the change in reduced direction. When the index of refraction is the same before and after a thin system, the change in reduced direction is the reduced deflection through the system or the reduced prismatic effect. Contrary to what has recently been claimed, this type of two-dimensional vector field does not apply in general to thick systems. However, a number of different types of two-dimensional vector fields can be defined for various particular classes of optical systems. Thick systems differ qualitatively from thin systems. They do not have equivalent thin lenses and cannot generally be replaced by thin lenses. Equations are derived for the change in reduced direction and deflection for a ray through optical systems in general and through separated two- and three-lens systems in particular. PMID:8807654

  4. Calibration results using highly aberrated images for aligning the JWST instruments to the telescope

    NASA Astrophysics Data System (ADS)

    Smith, Koby Z.; Acton, D. Scott; Gallagher, Ben B.; Knight, J. Scott; Dean, Bruce H.; Jurling, Alden S.; Zielinski, Thomas P.

    2016-07-01

    mostly of 3rd-order astigmatism and coma. This is because the elliptical tertiary mirror of the AOS is used off of its ideal foci locations without the compensating wavefront effects of the JWST primary and secondary mirrors. Therefore, the PSFs created are highly asymmetric with relatively complex structure and the centroid and encircled energy analyses traditionally used to locate images are not sufficient for ensuring the AOS to ISIM alignment. A novel approach combining phase retrieval and spatial metrology was developed to both locate the images with respect to the AOS and provide calibration information for eventual AOS to ISIM alignment verification. During final JWST OTE and ISIM (OTIS) testing, only a single thru-focus image will be collected by the instruments. Therefore, tools and processes were developed to perform single-image phase retrieval on these highly aberrated images such that any single image of the ASPA source can provide calibrated knowledge of the instruments' position relative to the AOS. This paper discusses the results of the methodology, hardware, and calibration performed to ensure that the AOS and ISIM are aligned within their respective tolerances at JWST OTIS testing.

  5. FK Comae: King of Spin

    NASA Astrophysics Data System (ADS)

    Ayres, T. R.; Korhonen, H.; Harper, G. M.; Brown, A.; Redfield, S.

    2004-12-01

    Fast-rotating early-G giants often display ultraviolet profiles of ``hot lines,'' like O VI (3×105 K), up to twice as broad as anticipated from the photospheric υsin {i}. This peculiar behavior has been attributed to highly extended coronal outer atmospheres. FUSE recently has contributed fundamentally to the exploration of these ``super-rotational'' effects by observing the fascinating object FK Comae Berenices (G5 III). It is prototype of a class of rapidly rotating single giants which display spectacular emission activity from X-rays to radio. FK Com has a spin period of only 2.4 d, and a remarkable υsin {i} of 160 km s-1. The origins of such ultra-fast--rotating stars are controversial. They might result from a coalesced contact binary, cannibalism of a ``hot Jupiter,'' or simply represent the top of the natural spin distribution of moderate-mass Hertzsprung gap giants. In February 2004, FUSE obtained a 13 ks exposure of FK Com in the 920--1180 Å range, the first UV observation of this unusual object since the IUE era a decade ago, and by far the best quality spectrum to date. The FUV emissions of O VI λ 1031 and C III λ 977 are enormously broad, asymmetric, but nearly identical in shape, aside from a blue-shifted absorption component in the latter. The FHWM's are a remarkable 600 km s-1, about twice the broadest FUV profile of any late-type star observed up to that point. The blueshifted C III feature might represent a wind at ˜ 3×104 K, or alternatively a scattering structure in the highly extended coronal envelope, something like the ``prominences'' seen already in Hα . The asymmetric O VI profile might indicate an outflow at higher ˜ 3× 105 K temperatures; or simply reflects a skewed distribution of high-altitude activity in the equatorial zones of FK Com. The relationship between the hot lines and photospheric active regions---deduced from contemporaneous optical Doppler mapping---also will be discussed. This work was supported by FUSE Guest

  6. Dynamics & Morphology of Coma Cluster Galaxies

    NASA Astrophysics Data System (ADS)

    Beijersbergen, M.; van der Hulst, J. M.

    The principal aim of this project is to explore the link between the cluster and its environment, and to study the effects that changes in environment have on the properties of galaxies. Coma, the richest of the nearby clusters, appears to be a close equivalent to clusters at higher redshift. The most remarkable similarity is the presence of blue disk galaxies and galaxies with E+A type spectra, making Coma the perfect link between nearby and distant clusters. Despite numerous observations, many aspects of both the dynamics of the Coma cluster and of its galaxy populations remain unexplained. One of the most notable pieces of information that is as yet unavailable, is a proper, unbiased HI survey of the entire Coma area. The few pointed observations that have been done show a variety in HI properties: stripped disks, blue disk galaxies with quite a range in HI content and galaxies with low surface brightness companions. We have used the Westerbork Synthesis Radio Telescope (WSRT) to perform a blind survey of galaxies in Coma in the redshifted HI line. We have covered an area of 4.6 square degrees with 17 MHz bandwidth in 432 hours of total integration time. This allows us to study the HI properties as function of environment and assess the importance of merging and stripping. The HI observations will be used in combination with optical data from the wide field camera on the Isaac Newton Telescope (INT) to address a large number of interesting problems. Our data sets are unrivalled by what is available for any other cluster and will greatly enhance the ability to study the structure and dynamics of Coma. Here, I will discuss the data and the status of this ongoing project.

  7. Prevalence of Corneal Astigmatism in Tohono O'odham Native American Children 6 Months to 8 Years of Age

    PubMed Central

    Dobson, Velma; Miller, Joseph M.; Schwiegerling, Jim; Clifford-Donaldson, Candice E.; Green, Tina K.; Messer, Dawn H.

    2011-01-01

    Purpose. To describe the prevalence of corneal astigmatism in infants and young children who are members of a Native American tribe with a high prevalence of refractive astigmatism. Methods. The prevalence of corneal astigmatism was assessed by obtaining infant keratometer (IK4) measurements from 1235 Tohono O'odham children, aged 6 months to 8 years. Results. The prevalence of corneal astigmatism >2.00 D was lower in the 1- to <2-year-old age group when compared with all other age groups, except the 6- to <7-year-old group. The magnitude of mean corneal astigmatism was significantly lower in the 1- to <2-year age group than in the 5- to <6-, 6- to <7-, and 7- to <8-year age groups. Corneal astigmatism was with-the-rule (WTR) in 91.4% of astigmatic children (≥1.00 D). Conclusions. The prevalence and mean amount of corneal astigmatism were higher than reported in non–Native American populations. Mean astigmatism increased from 1.43 D in 1-year-olds to nearly 2.00 D by school age. PMID:21460261

  8. Changes in falling risk depending on induced axis directions of astigmatism on static posture

    PubMed Central

    Kim, Sang-Yeob; Moon, Byeong-Yeon; Cho, Hyun Gug

    2015-01-01

    [Purpose] To assess the changes in falling risk depending on the induced axis direction of astigmatism using cylindrical lenses in a static posture. [Subjects and Methods] Twenty subjects (10 males, 10 females; mean age, 23.4 ± 2.70 years) fully corrected by subjective refraction participated. To induce myopic simple astigmatism conditions, cylindrical lenses of +0.50, +1.00, +1.50, +2.00, +3.00, +4.00, and +5.00 D were used. The direction of astigmatic axes were induced under five conditions with increased cylindrical powers:, 180°, 90°, and 45° on both eyes; 180°/90° right/left eye, and 45°/135° right/left eye. Changes in the fall risk index were analyzed using the TETRAX biofeedback system. Measurements were performed for 32 seconds for each condition. [Results] The fall risk index increased significantly from C+4.00 D in 180°/90° right/left eye, C+3.00 D in 45°/135° right/left eye, and C+3.00 D in 45° on both eyes versus corrected emmetropia. Among the five axis conditions with the same cylindrical power lenses, the increase in the fall risk index was highest at 45° in both eyes. [Conclusion] Uncorrected oblique astigmatism may increase falling risk compared to with-the-rule and against-the-rule astigmatism. Clinical specialists should consider appropriate correction of astigmatism for preventing falls, especially for uncorrected oblique astigmatism. PMID:26180360

  9. The effect of corneal irregularity on astigmatism measurement by automated versus ray tracing keratometry.

    PubMed

    Roh, Hyun Cheol; Chuck, Roy S; Lee, Jimmy K; Park, Choul Yong

    2015-04-01

    The aim of this study was to compare the effect of corneal irregularity on astigmatism assessment using automated keratometry (AK) (IOLMaster) versus ray tracing keratometry (Pentacam). This is an observational case series approved by the institutional review board of Dongguk University Hospital, Goyang, South Korea. A total of 207 eyes of 207 cataract patients were included. Preoperative corneal astigmatism was measured by both IOLMaster and Pentacam. Corneal irregularity index (IR) was calculated in Fourier analysis map of Pentacam. AK by IOLMaster and total corneal refractive power (TCRP, 3 mm and 4 mm zone analysis with pupil centered) by Pentacam were selected and the difference between the 2 measurements (delta Δ) was calculated using vector analysis. Ocular residual astigmatism (ORA) after cataract surgery was calculated by subtracting 6-month postoperative refractive astigmatism (RA) measurements from corresponding preoperative values (AK, TCRP3, and TCRP4). The mean irregularity index measured was 0.042 ± 0.019 mm (mean ± standard deviation) and was positively correlated with age and magnitude of corneal astigmatism (P < 0.001 and P < 0.05). The difference (Δ) between TCRPs and AK (ΔTCRPs-AK) was 0.43 ± 0.37 (TCRP3) and 0.39 ± 0.35 (TCRP4) diopters. Linear regression analysis revealed that age (P < 0.001), IR (P < 0.001), and AK (P < 0.001) were positively correlated with ΔTCRPs-AK. In highly irregular corneas (IR over 0.77 diopters: mean + 2 standard deviation), postoperative ORAs calculated using TCRPs were significantly lower than ORAs calculated using AK. Corneal irregularities significantly impact astigmatism assessment by IOLMaster (AK) and Pentacam (TCRPs). Compared with AK, TCRPs were more accurate in predicting postoperative residual astigmatism in highly irregular corneas.

  10. A novel color-LED corneal topographer to assess astigmatism in pseudophakic eyes

    PubMed Central

    Ferreira, Tiago B; Ribeiro, Filomena J

    2016-01-01

    Purpose To assess the accuracy of corneal astigmatism evaluation measured by four techniques, Orbscan IIz®, Lenstar LS900®, Cassini®, and Total Cassini (anterior + posterior surface), in pseudophakic eyes. Patients and methods A total of 30 patients (46 eyes) who had undergone cataract surgery with the implantation of a monofocal intraocular lens (AcrySof IQ) were assessed after surgery. For each eye, subjective assessment of astigmatism and its axis was performed. Minimum, maximum, and mean keratometry and astigmatism and its axis were evaluated using the four measurement techniques. All measurements were compared with the subjective measurements. Agreement between each measurement technique and subjective assessment was evaluated using Bland–Altman plots. Linear regressions were performed and compared. Results Linear regression analysis of astigmatism axis showed very high R2 for all models, with Total Cassini showing the least difference to the unit slope (0.052) and the least difference to a null constant (3.790), although not statistically different from the other models. Regarding astigmatism value, the Cassini and Total Cassini models were similar and statistically better than the Lenstar model. Cassini and Total Cassini showed better J0 compared with Orbscan. Conclusion On linear regression models, Cassini and Total Cassini showed the best performance regarding astigmatism value. Cassini and Total Cassini also showed the least J0 deviation from the Cartesian origin compared with Orbscan, which had the lowest performance. Total corneal measurement with the color LED topographer seems to be a better technique for astigmatism assessment. PMID:27574391

  11. Functional MRI and Outcome in Traumatic Coma

    PubMed Central

    Giacino, Joseph T.; Wu, Ona

    2013-01-01

    Advances in task-based functional MRI (fMRI), resting-state fMRI (rs-fMRI), and arterial-spin labeled (ASL) perfusion MRI have occurred at a rapid pace in recent years. These techniques for measuring brain function have great potential to improve the accuracy of prognostication for civilian and military patients with traumatic coma. In addition, fMRI, rs-fMRI, and ASL have provided novel insights into the pathophysiology of traumatic disorders of consciousness, as well as mechanisms of recovery from coma. However, functional neuroimaging techniques have yet to achieve widespread clinical use as prognostic tests for patients with traumatic coma. Rather, a broad spectrum of methodological hurdles currently limits the feasibility of clinical implementation. In this review, we discuss the basic principles of fMRI, rs-fMRI and ASL and their potential applications as prognostic tools for patients with traumatic coma. We also discuss future strategies for overcoming the current barriers to clinical implementation. PMID:23881623

  12. Coma Patient Monitoring System Using Image Processing

    NASA Astrophysics Data System (ADS)

    Sankalp, Meenu

    2011-12-01

    COMA PATIENT MONITORING SYSTEM provides high quality healthcare services in the near future. To provide more convenient and comprehensive medical monitoring in big hospitals since it is tough job for medical personnel to monitor each patient for 24 hours.. The latest development in patient monitoring system can be used in Intensive Care Unit (ICU), Critical Care Unit (CCU), and Emergency Rooms of hospital. During treatment, the patient monitor is continuously monitoring the coma patient to transmit the important information. Also in the emergency cases, doctor are able to monitor patient condition efficiently to reduce time consumption, thus it provides more effective healthcare system. So due to importance of patient monitoring system, the continuous monitoring of the coma patient can be simplified. This paper investigates about the effects seen in the patient using "Coma Patient Monitoring System" which is a very advanced product related to physical changes in body movement of the patient and gives Warning in form of alarm and display on the LCD in less than one second time. It also passes a sms to a person sitting at the distant place if there exists any movement in any body part of the patient. The model for the system uses Keil software for the software implementation of the developed system.

  13. New red jewels in Coma Berenices

    SciTech Connect

    Terrien, Ryan C.; Mahadevan, Suvrath; Deshpande, Rohit; Bender, Chad F.; Hearty, Frederick R.; Schneider, Donald P.; Cargile, Phillip A.; Pepper, Joshua; Rodriguez, Joseph E.; Siverd, Robert J.; Stassun, Keivan G.; Cottaar, Michiel; Allende Prieto, Carlos; Frinchaboy, Peter M.; Jackson, Kelly M.; Johnson, Jennifer A.; Majewski, Steven R.; Nidever, David L.; Weaver, Benjamin A.; and others

    2014-02-20

    We have used Sloan Digital Sky Survey-III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) radial velocity observations in the near-infrared H-band to explore the membership of the nearby (86.7 ± 0.9 pc) open cluster Coma Berenices (Melotte 111), concentrating on the poorly populated low-mass end of the main sequence. Using SDSS-III APOGEE radial velocity measurements, we confirm the membership of eight K/M dwarf members, providing the first confirmed low-mass members of the Coma Berenices cluster. Using R ∼ 2000 spectra from IRTF-SpeX, we confirm the independently luminosity classes of these targets, and find their metallicities to be consistent with the known solar mean metallicity of Coma Berenices and of M dwarfs in the solar neighborhood. In addition, the APOGEE spectra have enabled measurement of vsin i for each target and detection for the first time of the low-mass secondary components of the known binary systems Melotte 111 102 and Melotte 111 120, as well as identification of the previously unknown binary system 2MASS J12214070+2707510. Finally, we use Kilodegree Extremely Little Telescope photometry to measure photometric variability and rotation periods for a subset of the Coma Berenices members.

  14. Toric intraocular lenses for correction of astigmatism in keratoconus and after corneal surgery

    PubMed Central

    Mol, Ilse EMA; Van Dooren, Bart TH

    2016-01-01

    Purpose To describe the results of cataract extraction with toric intraocular lens (IOL) implantation in patients with preexisting astigmatism from three corneal conditions (keratoconus, postkeratoplasty, and postpterygium surgery). Methods Cataract patients with topographically stable, fairly regular (although sometimes very high) corneal astigmatism underwent phacoemulsification with implantation of a toric IOL (Zeiss AT TORBI 709, Alcon Acrysof IQ toric SN6AT, AMO Tecnis ZCT). Postoperative astigmatism and refractive outcomes, as well as visual acuities, vector reduction, and complications were recorded for all eyes. Results This study evaluated 17 eyes of 16 patients with a mean age of 60 years at the time of surgery. Mean follow-up in this study was 12 months. The corrected distance Snellen visual acuity (with spectacles or contact lenses) 12 months postoperatively was 20/32 or better in 82% of eyes. The mean corneal astigmatism was 6.7 diopters (D) preoperatively, and 1.5 D of refractive cylinder at 1-year follow-up. No vision-compromising intra- or postoperative complications occurred and decentration or off-axis alignment of toric IOLs were not observed. Conclusion Phacoemulsification with toric IOL implantation was a safe and effective procedure in the three mentioned corneal conditions. Patient selection, counseling, and IOL placement with optimal astigmatism correction are crucial. PMID:27382249

  15. Convergence Insufficiency, Accommodative Insufficiency, Visual Symptoms, and Astigmatism in Tohono O'odham Students

    PubMed Central

    Twelker, J. Daniel; Miller, Joseph M.; Campus, Irene

    2016-01-01

    Purpose. To determine rate of convergence insufficiency (CI) and accommodative insufficiency (AI) and assess the relation between CI, AI, visual symptoms, and astigmatism in school-age children. Methods. 3rd–8th-grade students completed the Convergence Insufficiency Symptom Survey (CISS) and binocular vision testing with correction if prescribed. Students were categorized by astigmatism magnitude (no/low: <1.00 D, moderate: 1.00 D to <3.00 D, and high: ≥3.00 D), presence/absence of clinical signs of CI and AI, and presence of symptoms. Analyses determine rate of clinical CI and AI and symptomatic CI and AI and assessed the relation between CI, AI, visual symptoms, and astigmatism. Results. In the sample of 484 students (11.67 ± 1.81 years of age), rate of symptomatic CI was 6.2% and symptomatic AI 18.2%. AI was more common in students with CI than without CI. Students with AI only (p = 0.02) and with CI and AI (p = 0.001) had higher symptom scores than students with neither CI nor AI. Moderate and high astigmats were not at increased risk for CI or AI. Conclusions. With-the-rule astigmats are not at increased risk for CI or AI. High comorbidity rates of CI and AI and higher symptoms scores with AI suggest that research is needed to determine symptomatology specific to CI. PMID:27525112

  16. Chemical Recycling of HCN in Cometary Comae

    NASA Astrophysics Data System (ADS)

    Boice, Daniel C.; Kawakita, Hideyo; Shinnaka, Yoshiharu; Mumma, Michael J.; Kobayashi, Hitomi; Ogawa, Sayuri

    2014-11-01

    Modeling is essential to understand the important physical and chemical processes that occur in cometary comae, especially the relationship between putative parent and daughter molecules, such as, HCN and CN. Photochemistry is a major source of ions and electrons that further initiate key gas-phase reactions, contributing to the plethora of molecules and atoms observed in comets. The effects of photoelectrons that interact via impacts are important to the overall excitation and dissociation processes in the inner coma. We consider the relevant processes in the collision-dominated, inner coma of a comet within a global modeling framework to understand observations of HCN and CN. The CN source(s) must be able to produce highly collimated jets, be consistent with the observed CN parent scale length, and have a production rate consistent with the observed CN production. HCN fulfills these conditions in some comets (e.g., 1P/Halley, Hale-Bopp) while it does not in others (e.g., 8P/Tuttle, 6P/d’Arrest, 73P/S-W3, 2P/Encke, 9P/Temple 1 and C/2007 W1).We investigate the chemistry of HCN with our chemical kinetics coma model including a network with other possible CN parents, as well as a dust component that may be a potential source of CN. It is seen that the major destruction pathways of HCN are via photo dissociation (into H and CN) and protonation with water group ions - primarily H3O+. We point out the intriguing “recycling” of HCN via protonation reactions with H3O+, H2O+, OH+, and subsequent dissociative recombination. It seems that HCN molecules observed in the coma can consist of those initially released from the nucleus and those that are freshly formed at different locations in the coma via these protonation/dissociation reactions. We will investigate implications for reconciling discrepancies between observations of HCN and CN in cometary comae.Acknowledgements: We appreciate support from the NSF Planetary Astronomy Program. This program is partially

  17. Accuracy of the Welch Allyn Suresight for measurement of magnitude of astigmatism in 3- to 7-year-old children

    PubMed Central

    Harvey, Erin M.; Dobson, Velma; Miller, Joseph M.; Clifford-Donaldson, Candice E.; Green, Tina K.; Messer, Dawn H.; Garvey, Katherine A.

    2009-01-01

    Purpose To evaluate the accuracy of the Welch Allyn SureSight in noncycloplegic measurements of astigmatism as compared to cycloplegic Retinomax K+ autorefractor measurements of astigmatism in children from a Native American population with a high prevalence of high astigmatism. Methods Data are reported for 825 3- to 7-year-old children with no ocular abnormalities. Each child had a Retinomax K+ cycloplegic measurement of right eye astigmatism with a confidence rating ≥8 and 3 attempts to obtain a SureSight measurement on the right eye. Results SureSight measurement success rates did not differ significantly across age or measurement confidence rating (<6 vs ≥6). Ninety-six percent of children had at least 1 measurement (any confidence), and 89% had at least 1 measurement with confidence at the manufacturer's recommended value (≥6). Overall, the SureSight tended to overestimate astigmatism. If the SureSight measurement had any dioptric value (0.00 D to 3.00 D), astigmatism of 2.00 D or less was likely to be present. If the SureSight showed astigmatism beyond the instrument's dioptric range (>3.00 D), Retinomax K+ measurements indicated that >2.00 D of astigmatism was present in 136 of 157 (86.6%). In cooperative children for whom the SureSight would not give a reading, 32 of 34 (94%) had >3.00 D of astigmatism. Conclusions The SureSight does not provide an accurate, quantitative measure of amount of astigmatism. However, it does allow accurate categorization of amount of astigmatism as ≤2.00 D, >2.00 D, or >3.00 D, and it has high measurement success rate in young children. PMID:19840726

  18. Distribution and Repeatability of Corneal Astigmatism Measurements (Magnitude and Axis) Evaluated With Color Light Emitting Diode Reflection Topography

    PubMed Central

    Asimellis, George

    2015-01-01

    Purpose: To evaluate and investigate the distribution and repeatability of anterior corneal surface astigmatism measurements (axis and magnitude) using a novel corneal topographer. Methods: Anterior corneal surface astigmatism was investigated in a total of 195 eyes using a novel multicolored spot reflection topographer (Cassini; i-Optics). Two patient groups were studied, a younger-age group A and an older-age group B. Three consecutive acquisitions were obtained from each eye. The repeatability of measurement was assessed using Bland–Altman plot analysis and is reported as the coefficient of repeatability. Results: Group A (average age 34.3 years) had on average with-the-rule astigmatism, whereas the older-age group B (average age 72.3 years) had on average against-the-rule astigmatism. Average astigmatism magnitude measurement repeatability in group A was 0.4 diopters (D) and in group B 0.4 D. Average astigmatism axis measurement repeatability in group A was 5.4 degrees and in group B 5.5 degrees. The axis measurement repeatability improved with increasing magnitude of astigmatism: in the subgroups with astigmatism between 3.0 and 6.0 D, the axis repeatability was 1.4 degrees (group A) and 1.2 degrees (group B), whereas in the subgroups with astigmatism larger than 6.0 D, the repeatability was 1.1 and 0.6 degrees, respectively. Conclusions: This novel corneal topography device seems to offer high precision in reporting corneal astigmatism. This study reaffirms the established trend of a corneal astigmatism shift from an average “with-the-rule” to “against-the-rule” with aging. PMID:26057324

  19. Refractive and Aberration Outcomes after Customized Photorefractive Keratectomy in Comparison with Customized Femtosecond Laser

    PubMed Central

    Sajjadi, Valleh; Ghoreishi, Mohammad; Jafarzadehpour, Ebrahim

    2015-01-01

    To compare the refractive and visual outcomes and higher order aberrations in patients with low to moderate myopia who underwent customized photorefractive keratectomy (PRK) or femtosecond laser in situ keratomileusis (Femto-LASIK) this research performed. This study includes data of 120 consecutive eyes of 60 patients with myopia between -3.00 D and -7.00 D with or without astigmatism in two surgery groups: PRK and Femto-LASIK. Refractive, visual, and aberration outcomes of the two methods of surgery were compared after 6 months of follow-up. After six months of follow-up, sphere and cylinder were found significantly decreased and there was no statistically significant difference between the two groups. The mean of uncorrected distance visual acuity in LogMar format for the PRK and Femto-LASIK groups was -0.03±0.07 and -0.01±0.08, respectively, which was not significantly different between the two groups. Higher orders and spherical aberrations increased in both groups significantly, while total aberrations decreased in both groups. After surgery, no differences were observed between the two groups in the amount of aberrations. In conclusion, Both PRK and Femto-LASIK are effective and safe in correcting myopia. In this study PRK induced more spherical and higher order aberrations than Femto-LASIK. PMID:27800501

  20. The mass of the Coma cluster

    NASA Astrophysics Data System (ADS)

    The, Lih-Sin

    The dynamical mass determination of galaxies and systems of galaxies shows a large excess of mass above what is directly observed. This excess of mass indicates the presence of dark matter. The nature of this dark matter is still unknown and dark matter in the outer regions of large stellar structures such as clusters of galaxies might provide enough matter to close the universe. The mass distribution of the Coma cluster is investigated. It is shown that optical data alone are unable to distinguish between a wide range of possible mass distribution for the Coma cluster. Low-mass models must have larger density than high-mass models and require that the galaxies move on near-circular orbits, whereas high-mass models require the galaxy orbits to be predominantly radial. The optical data constrain the amount of dark matter very poorly. The x ray data can also be used for a mass determination of the Coma cluster. These data may require the mass of the cluster to be more concentrated to the core than a light-traces-mass model if the central temperature of the gas is high. The above analysis, and most other approaches, assume the existence of dark matter. An alternative approach was proposed by Milgrom (1983a,b,c): the Newtonian law of motion breaks down in a weak field, and must be modified. The present analysis shows that this model is also consistent with optical and x ray data on the Coma cluster, although a good fit required values for Milgrom's universal parameter ao to be 2h1.5 (Ho) = 50 h km/s/Mpc) higher than those inferred from the rotation curves of spiral galaxies. Finally, whether the model of an expanding cluster dominated by a massive binary galaxy is consistent with optical data on the surface density and velocity dispersion of the Coma cluster is investigated. The evolution of the model is simulated for a wide variety of initial conditions. This model is not a viable representation of the Coma cluster.

  1. [First experience of intrastromal ring segments insertion for correction of posttraumatic cicatricial corneal astigmatism].

    PubMed

    Neroev, V V; Gundorova, R A; Beliaev, D S; Petukhova, A B; Oganesian, O G; Penkina, A V

    2013-01-01

    The potential of MAGELLAN MAPPER corneal topographer in evaluation of corneal refraction in the early postoperative period after surgical debrigement of scleral and corneal penetrating wounds is shown. The accuracy of corneal topography is satisfactory and its results reproducible what makes the method suitable for evaluation of corneal refraction and follow-up in patients with penetrating wounds and scarring of sclera and cornea. The possibility of posttraumatic cicatricial astigmatism correction by insertion of Keraring intrastromal corneal ring segments (ICRS) using femtosecond surgical laser FEMTO LDV were studied. Results of cicatricial corneal astigmatism correction in early posttraumatic period are encouraging.

  2. Broadband astigmatism-corrected spectrometer design using a toroidal lens and a special filter

    NASA Astrophysics Data System (ADS)

    Ge, Xianying; Chen, Siying; Zhang, Yinchao; Chen, He; Guo, Pan; Mu, Taotao; Yang, Jian; Bu, Zhichao

    2015-01-01

    In the paper, a method to obtain a broadband, astigmatism-corrected spectrometer based on the existing Czerny-Turner spectrometer is proposed. The theories of astigmatism correction using a toroidal lens and a special filter are described in detail. Performance comparisons of the modified spectrometer and the traditional spectrometer are also presented. Results show that with the new design the RMS spot radius in sagittal view is one-eightieth of that in the traditional spectrometer over a broadband spectral range from 300 to 700 nm, without changing or moving any optical elements in the traditional spectrometer.

  3. Toric intraocular lens orientation and residual refractive astigmatism: an analysis

    PubMed Central

    Potvin, Rick; Kramer, Brent A; Hardten, David R; Berdahl, John P

    2016-01-01

    Purpose To analyze intraocular lens (IOL) orientation data from an online toric back-calculator (astigmatismfix.com) for determining if differences were apparent by lens type. Methods A retrospective review of astigmatismfix.com toric back-calculations that included IOL identification and intended orientation axis. Results Of 12,812 total validated calculation records, 8,229 included intended orientation and lens identification data. Of the latter, 5,674 calculations (69%) involved lenses oriented 5° or more from their intended position. Using estimated toric lens usage data, the percentage of lenses with orientation ≥5° from intended was 0.89% overall, but the percentage varied significantly between specific toric lens brands (P<0.05). The percentage of back-calculations related to lenses that were not oriented as intended was also statistically significantly different by lens brand (P<0.05). When IOLs were misoriented, they were significantly more likely to be misoriented in a counterclockwise direction (P<0.05). This was found to be due to a bias toward counterclockwise orientation observed with one specific brand, a bias that was not observed with the other three brands analyzed here. Conclusion The percentage of eyes with lens orientation ≥5° from intended in the Toric Results Analyzer data set was <1% of toric IOLs in general, with the relative percentage of Tecnis® Toric IOLs significantly higher than AcrySof® Toric IOLs. Both of these had higher rates than the Staar® Toric and Trulign® Toric lenses, with the availability of higher Tecnis and AcrySof cylinder powers a likely contributing factor. The AcrySof Toric IOL appears to be less likely than the Tecnis Toric IOL to cause residual astigmatism as a result of misorientation. The Tecnis Toric IOL appears more likely to be misoriented in a counterclockwise direction; no such bias was observed with the AcrySof Toric, the Trulign® Toric, or the Staar Toric IOLs. PMID:27703323

  4. [Hysterical pseudo-coma: A case report].

    PubMed

    Chouaib, N; Chouaib, H; Belyamani, L; Otheman, Y; Bichra, M Z

    2015-09-01

    Hysterical pseudo-coma corresponds to a state of clinical sleep with contrasting waking electroencephalogram. It can last several hours or even several days in the absence of an underlying organic disease. In psychiatry, this disorder is currently part of the "dissociative disorder not otherwise specified". Through this case report, we describe the evolution of a hysterical pseudo-coma that lasted four days in a 28-year-old man. The normality of biological, radiological and electroencephalographic assessments, and responsiveness of the patient during the implementation of a nasogastric tube, led us to suspect a mental origin. An adapted psychiatric care allowed the patient to recover his autonomy after three days of hospitalization. This had prevented the escalation of explorations and invasive treatments. However, the search for organic comorbidity and its management remains a priority.

  5. Another collision for the Coma cluster

    NASA Technical Reports Server (NTRS)

    Vikhlinin, A.; Forman, W.; Jones, C.

    1996-01-01

    The wavelet transform analysis of the Rosat position sensitive proportional counter (PSPC) images of the Coma cluster are presented. The analysis shows, on small scales, a substructure dominated by two extended sources surrounding the two bright clusters NGC 4874 and NGC 4889. On scales of about 2 arcmin to 3 arcmin, the analysis reveals a tail of X-ray emission originating near the cluster center, curving to the south and east for approximately 25 arcmin and ending near the galaxy NGC 4911. The results are interpreted in terms of a merger of a group, having a core mass of approximately 10(exp 13) solar mass, with the main body of the Coma cluster.

  6. Peritoneal dialysis in hypernatraemic, ketoacidotic diabetic coma.

    PubMed

    Køolendorf, K; Møoller, B B

    1976-01-01

    Hypertonic dehydration in a 13-year-old boy with ketoacidotic diabetic coma has been treated successfully with peritoneal dialysis and isotonic fluids. Modes of treatment with either hypotonic or isotonic fluids are discussed, as is the feasibility of peritoneal dialysis. We recommend isotonic solutions composed of equal parts of 5.5% glucose and 0.9% sodium chloride combined with peritoneal dialysis in order to secure a relatively slow correction of the hypertonic state.

  7. Respiratory complications during artificial barbiturate coma.

    PubMed

    Ducati, A; Signoroni, G; Meli, M; Lobascio, A E; Massei, R; Infuso, L

    1981-01-01

    Artificial barbiturate coma was induced in 13 patients with disorders of consciousness from traumatic or spontaneous diseases. Early respiratory complications consisting with Adult Respiratory Distress Syndrome (ARDS) were found in 10 out of these 13 patients; on the contrary, only 2 out of 13 patients, treated with routine intensive care therapy without barbiturate, showed analogous respiratory complications. The literature on the subject and the possible pathophysiological mechanism of respiratory distress are discussed.

  8. Chemical Recycling of Molecules in Cometary Comae

    NASA Astrophysics Data System (ADS)

    Boice, Daniel C.; Kawakita, Hideyo; Shinnaka, Yoshiharu; Kobayashi, Hitomi

    2015-08-01

    Modeling is essential to understand the important physical and chemical processes that occur in cometary comae, especially the relationship between native and sibling molecules, such as, HCN and CN. Photochemistry is a major source of ions and electrons that further initiate key gas-phase reactions, leading to the plethora of molecules and atoms observed in comets. The effects of photoelectrons that react via impacts are important to the overall ionization in the inner coma. We have found that many molecules undergo protonation reactions with primarily water, followed by electron recombination resulting in the original molecules in a vibrationally excited state. These excited molecules spontaneously emit photons back to the ground state. We identify this series of reactions as chemical “recycling.” We discuss the importance of this mechanism for HCN, NH3, and water in comets. We also identify other relevant processes in the collision-dominated, inner coma of a comet within a global modeling framework to better understand observations and in situ measurements of cometary species, especially relationships between native and sibling molecules for the Rosetta Mission to Comet 67P/Churyumov-Gerasimenko.Acknowledgements: We appreciate support from the NSF Planetary Astronomy Program under Grant No. 0908529. This program is partially supported by the MEXT Supported Program for the Strategic Research Foundation at Private Universities, 2014-2018.

  9. Optical-vortex pair creation and annihilation and helical astigmatism of a nonplanar ring resonator

    SciTech Connect

    Heckenberg, N.R.; Vaupel, M.; Malos, J.T.; Weiss, C.O.

    1996-09-01

    The creation and annihilation of pairs of optical vortices have been studied in transitions between patterns produced in a photorefractive oscillator. Smooth metamorphosis between stable patterns occurs through pair creation or annihilation but can be modeled using superposition of modes taking into account lifting of degeneracy of helical modes by helical astigmatism of the resonator. {copyright} {ital 1996 The American Physical Society.}

  10. On the relation between power and astigmatism near an umbilic line.

    PubMed

    Rubinstein, Jacob

    2011-05-01

    The relation between the variation of power and astigmatism in a progressive power optical element is considered. The classical Minkwitz identity is revisited. Then, it is shown how to extend this identity, which applies to the geometry of surfaces, to optical parameters that are determined by the geometry of reflected or refracted wavefronts. PMID:21532682

  11. [Laser correction of myopia and myopic astigmatism in children--literature review].

    PubMed

    Mrukwa-Kominek, Ewa; Gierek-Ciaciura, Stanisława

    2003-01-01

    Anisometropic myopia and myopic astigmatism are very often refractive error in children. Suitable correction of different vision defects in children might prevent the consequences of amblyopia and lack of development of binocular vision. This article presents the effectiveness of correction in myopia and myopic anisometropia using laser method such as PRK, LASEK and LASIK. It is the literature review. PMID:15049271

  12. Evaluation of the toric implantable collamer lens for simultaneous treatment of myopia and astigmatism.

    PubMed

    Price, Marianne O; Price, Francis W

    2015-01-01

    Myopic astigmatism is a prevalent condition that can be treated with spectacles, contact lenses, or laser refractive surgery. However, these treatment options have functional limitations at higher levels of refractive error. The toric implantable collamer lens is designed to treat a broad range of refractive error, generally up to -18 diopters with +1 to +6 diopters of astigmatism. Approval for a more limited treatment range of up to 15 diopters of myopia with +1 to +4 diopters of astigmatism is being sought in the US, where this device has not yet received marketing approval. Surgical correction of high-myopic astigmatism can be life-altering and allow people to participate in activities that were not previously feasible because of visual limitations. The toric implantable collamer lens is implanted behind the iris and in front of the natural crystalline lens. With earlier lens designs, it was necessary to create an iridectomy or iridotomy to prevent pupillary block. The newest toric implantable collamer lens model has a small central hole that is not visually noticeable. This eliminates the need to create a hole in the iris, thereby enhancing the safety of the procedure.

  13. Optical aberrations, retinal image quality and eye growth: Experimentation and modeling

    NASA Astrophysics Data System (ADS)

    Tian, Yibin

    2007-12-01

    subsequently elongated. The performance of some focus measures was very poor when non-defocus aberrations exceeded a certain level; presumably, these non-defocus aberrations might interfere with the eye's ability to interpret defocus. In anisomyopic human adults, more myopic eyes had larger anterior and vitreous chambers, greater astigmatism, and more positive spherical aberration. However, compared to isometropes, only interocular differences in spherical equivalent refractive errors were significantly increased.

  14. A two-stage method to correct aberrations induced by slide slant in bright-field microscopy.

    PubMed

    Fan, Yilun; Bradley, Andrew P

    2016-08-01

    To achieve optimal image quality in bright field microscopy, the slide surface should be perpendicular to the optical axis of the microscope. However, in the recently proposed "slanted scan" slide acquisition technique, scan speed is increased by purposely slanting the slide by a small angle (of 3-5°) so that multiple focal depths can be imaged simultaneously. In this case, the slanted slide introduces a bend in the point spread function (PSF), resulting in a coma and other aberrations that degrade image quality. In this paper, we propose a two-stage deconvolution method specifically designed to correct the aberrations induced by a slanted scan, but with general applicability to high-resolution bright-field microscopy. Specifically, we initially apply phase deconvolution to correct the dominating coma aberration, before applying a conventional semi-blind deconvolution method to further improve image resolution and contrast. We also propose a novel method to estimate the degree of coma aberration and the PSF of the optics utilising actual cytology specimens. The efficacy of the proposed algorithm is demonstrated quantitatively on simulated data, against a ground-truth (object) image, and qualitatively on cervical cytology specimens. Results demonstrate both improved convergence speed of the two-stage approach, especially when correcting the bend in the PSF, and a resultant image quality that is comparable to a conventionally (flat) scanned specimen. PMID:27182660

  15. Phase from chromatic aberrations.

    PubMed

    Waller, Laura; Kou, Shan Shan; Sheppard, Colin J R; Barbastathis, George

    2010-10-25

    We show that phase objects may be computed accurately from a single color image in a brightfield microscope, with no hardware modification. Our technique uses the chromatic aberration that is inherent to every lens-based imaging system as a phase contrast mechanism. This leads to a simple and inexpensive way of achieving single-shot quantitative phase recovery by a modified Transport of Intensity Equation (TIE) solution, allowing real-time phase imaging in a traditional microscope. PMID:21164620

  16. Thermodynamics of the Coma Cluster Outskirts

    NASA Astrophysics Data System (ADS)

    Simionescu, A.; Werner, N.; Urban, O.; Allen, S. W.; Fabian, A. C.; Mantz, A.; Matsushita, K.; Nulsen, P. E. J.; Sanders, J. S.; Sasaki, T.; Sato, T.; Takei, Y.; Walker, S. A.

    2013-09-01

    We present results from a large mosaic of Suzaku observations of the Coma Cluster, the nearest and X-ray brightest hot (~8 keV), dynamically active, non-cool core system, focusing on the thermodynamic properties of the intracluster medium on large scales. For azimuths not aligned with an infalling subcluster toward the southwest, our measured temperature and X-ray brightness profiles exhibit broadly consistent radial trends, with the temperature decreasing from about 8.5 keV at the cluster center to about 2 keV at a radius of 2 Mpc, which is the edge of our detection limit. The southwest merger significantly boosts the surface brightness, allowing us to detect X-ray emission out to ~2.2 Mpc along this direction. Apart from the southwestern infalling subcluster, the surface brightness profiles show multiple edges around radii of 30-40 arcmin. The azimuthally averaged temperature profile, as well as the deprojected density and pressure profiles, all show a sharp drop consistent with an outwardly-propagating shock front located at 40 arcmin, corresponding to the outermost edge of the giant radio halo observed at 352 MHz with the Westerbork Synthesis Radio Telescope. The shock front may be powering this radio emission. A clear entropy excess inside of r 500 reflects the violent merging events linked with these morphological features. Beyond r 500, the entropy profiles of the Coma Cluster along the relatively relaxed directions are consistent with the power-law behavior expected from simple models of gravitational large-scale structure formation. The pressure is also in agreement at these radii with the expected values measured from Sunyaev-Zel'dovich data from the Planck satellite. However, due to the large uncertainties associated with the Coma Cluster measurements, we cannot yet exclude an entropy flattening in this system consistent with that seen in more relaxed cool core clusters.

  17. Aberrations of sphero-cylindrical ophthalmic lenses.

    PubMed

    Malacara, Z; Malacara, D

    1990-04-01

    The authors have presented in two previous articles the graphic solutions resembling Tscherning ellipses, for spherical as well as for aspherical ophthalmic lenses free of astigmatism or power error. These solutions were exact, inasmuch as they were based on exact ray tracing, and not third-order theory as frequently done. In this paper sphero-cylindrical lenses are now analyzed, also using exact ray tracing. The functional dependence of the astigmatism and the power error for these lenses is described extensively.

  18. Predictors of outcome in myxoedema coma

    PubMed Central

    Beynon, Jennifer; Akhtar, Simeen; Kearney, Tara

    2008-01-01

    Myxoedema coma is a rare and life-threatening illness the outcome of which has not been robustly studied in large numbers, partly due to its low incidence. Dutta and colleagues have explored outcome predictors in a developing country where access to thyroid function tests is more limited than in the Western world. Cardiovascular instability, reduced consciousness, persistent hypothermia, and sepsis all contributed to a poorer outcome, as has been demonstrated before, but a generic outcome predictor model was shown to be useful in this group of patients. Unfortunately, this observational study was unable to show differences in outcome based on replacement treatment methods and the mortality remains at 40%. PMID:18254932

  19. Aspheric spectacles for correcting presbyopia with myopia and astigmatism.

    PubMed

    Zheng, Shaolin; Wang, Zhaoqi; Liu, Yongji; Li, Rui

    2012-10-10

    The aim of this paper is to propose a method for designing aspheric spectacles capable of realizing good optical performance at both far and near vision for presbyopia. We have experimentally measured wavefront aberrations and axial lengths for eight myopic eyes. In consideration of the field of view (FOV), the rotation of the eyeball, and a small amount of accommodation retained for presbyopia, we constructed individual eye models and optimized all the spectacle-eye systems for visible wavelengths by Zemax's simulation. Finally, we evaluated the image quality by the modulation transfer function (MTF) and visual acuity (VA) with different pupil sizes (2, 2.8, 4 mm). Results show that when the pupil size is 2 mm or 2.8 mm, the spectacles designed for the full FOV (0° and ±4° FOV) provide a strong ability to transfer low contrast at both far and near vision, and the VA for all reaches 0.8, and up to 1.1 for eyes NO. 1, NO. 5, NO. 6, and NO. 8 for the 0° FOV. As the pupil size increases to 4 mm, the VA for all comes to 0.6 for the full FOV, indicating that presbyopia is able to acquire a good visual resolution at both far and near vision by the designed aspheric spectacles. Furthermore, we verified the visual continuity of the spectacle-eye systems by studying intermediate vision, which demonstrates that the method used in our design is accurate and practicable.

  20. The use of toric intraocular lens to correct astigmatism at the time of cataract surgery

    PubMed Central

    Khan, Mohammad I.; Ch’ng, Soon W.; Muhtaseb, Mohammed

    2015-01-01

    Background: To evaluate the visual and refractive outcomes of cataract surgery with toric intraocular lens (IOL) implantation at a teaching hospital of the United Kingdom. Design: Prospective interventional case series. Materials and Methods: This study compared the outcome of 3 groups of patients: Group 1 included 25 eyes with cataract and more than 2.5 diopters (D) of corneal astigmatism receiving a toric monofocal IOL; Group 2 had 18 patients with cataract and more than 2.5 D of astigmatism but receiving a non-toric monofocal IOL; while Group 3 had 25 patients with cataract and less than 1.5 D of astigmatism and receiving a non-toric monofocal IOL. Data collected included uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction and corneal keratometry. Postoperative examinations were scheduled at 1 and 6 weeks. Results: Postoperatively the mean UDVA was LogMAR 0.27 ± 0.20 (equivalent snellen acuity of 20/37) in Group 1, 0.54 ± 0.22 (20/69) in Group 2 and 0.16 ± 0.20 (20/29) in Group 3. The mean CDVA was LogMAR 0.08 ± 0.13 (20/24) in Group 1, 0.23 ± 0.16 (20/34) in Group 2 and 0.04 ± 0.13 in Group 3 (20/22). The mean preoperative keratometric cylinder was 3.78 ± 1.0 D in Group 1, 3.41 ± 1.47 D in Group 2 and 0.97 ± 0.43D in Group 3; the mean postoperative subjective cylinder was 1.2 ± 0.68 D in Group 1, 3.23 ± 1.41 D in Group 2 and 0.95 ± 0.58 D in Group 3. The difference was statistically significant for the postoperative refractive cylinder values when comparing Group 1 to Group 2 (P = <0.0001) but the difference was insignificant between Group 1 and Group 3 (P = 0.23). Conclusion: Toric IOL implantation is an effective option to manage corneal astigmatism at the time of cataract surgery and to optimise visual outcomes for astigmatic patients when comparing to outcomes for their non-astigmatic counterparts. PMID:25709273

  1. [The coma awakening unit, between intensive care and rehabilitation].

    PubMed

    Mimouni, Arnaud

    2015-01-01

    After intensive care and before classic neurological rehabilitation is possible, patients in an altered state of consciousness are cared for at early stages in so-called coma awakening units. The care involves, on the one hand, the complex support of the patient's awakening from coma as a neurological and existential process, and on the other, support for their families. PMID:26365640

  2. The JFK Coma Recovery Scale--Revised.

    PubMed

    Kalmar, Kathleen; Giacino, Joseph T

    2005-01-01

    The JFK Coma Recovery Scale (CRS) was developed to help characterise and monitor patients functioning at Rancho Levels I-IV and has been used widely in both clinical and research settings within the US and Europe. The CRS was recently revised to address a number of concerns emanating from our own clinical experience with the scale, feedback from users and researchers as well as the results of Rasch analyses. Additionally, the CRS did not include all of the behavioural criteria necessary to diagnose the minimally conscious state (MCS), thereby limiting diagnostic utility. The revised JFK Coma Recovery Scale (CRS-R) includes addition of new items, merging of items found to be statistically similar, deletion or modification of items showing poor fit with the scale's underlying construct, renaming of items, more stringent scoring criteria, and quantification of elicited behaviours to improve accuracy of rating. Psychometric properties of the CRS-R appear to meet standards for measurement and evaluation tools for use in clinical and research settings, and diagnostic application suggests that the scale is capable of discriminating patients in the minimally conscious state from those in the vegetative state.

  3. X ray archeology in the Coma cluster

    NASA Technical Reports Server (NTRS)

    White, Simon D. M.; Briel, Ulrich G.; Henry, J. Patrick

    1993-01-01

    Images of X-ray emission from hot gas within the Coma cluster of galaxies are presented. These maps, made with the Rosat satellite, have high signal to noise ratio and allow cluster structure to be analyzed in unprecedented detail. They show greater structural irregularity than could be anticipated from earlier observations of Coma. Emission is detected from a number of bright cluster galaxies in addition to the two known previously. In four cases there is evidence that these galaxies lie at the center of an extended subconcentration within the cluster, possibly the remnant of their associated groups. For at least two galaxies the images show direct evidence for ongoing disruption of their gaseous atmosphere. The luminosity associated with these galaxies is comparable to that detected around similar ellipticals in much poorer environments. Emission is easily detected and appears to become more regular at large radii. The data show that this archetype of a rich and regular galaxy cluster was formed by the merging of several distinct subunits which are not yet fully destroyed.

  4. Thermal correction of astigmatism in the gravitational wave observatory GEO 600

    NASA Astrophysics Data System (ADS)

    Wittel, H.; Lück, H.; Affeldt, C.; Dooley, K. L.; Grote, H.; Leong, J. R.; Prijatelj, M.; Schreiber, E.; Slutsky, J.; Strain, K.; Was, M.; Willke, B.; Danzmann, K.

    2014-03-01

    The output port of GEO 600 is dominated by unwanted higher order modes (HOMs). The current thermal actuation system, a ring heater behind one of the folding mirrors, causes a significant amount of astigmatism, which produces HOMs. We have built and installed an astigmatism correction system, based on heating this folding mirror at the sides (laterally). With these side heaters and the ring heater behind the mirror, it is possible to tune its radius of curvature in the horizontal and the vertical degree of freedom. We use this system to match the mirrors in the two arms of GEO 600 to each other, thereby reducing the contrast defect. The use of the side heaters reduces the power of the HOMs at the output of GEO 600 by approximately 37%.

  5. Autorefraction, Retinoscopy, Javal's Rule, and Grosvenor's Modified Javal's Rule: The Best Predictor of Refractive Astigmatism

    PubMed Central

    Asiedu, Kofi; Ampiah, Emmanuel Ekow

    2016-01-01

    The aim of the study was to determine the level of agreement between Javal's rule, autorefraction, retinoscopy, and refractive astigmatism and to determine which technique is the most suitable substitute when subjective refraction is not applicable using a clinical sample. A total of 36 subjects, 14 males and 22 females, were involved in this study. The intraclass correlation coefficients between subjective refraction, autorefraction, and retinoscopy were 0.895 and 0.989, respectively, for the spherical equivalent. The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; and autorefraction and retinoscopy were −2.84 to 3.58, −0.88 to 1.12, and −3.01 to 3.53, respectively, for the spherical equivalent. The intraclass correlation coefficients between spectacle total astigmatism and the following techniques were as follows: retinoscopy (0.85); autorefraction (0.92); Javal's rule (0.82); and Grosvenor et al. version (0.85). The Bland-Altman 95% limits of agreement between subjective refraction and autorefraction; subjective refraction and retinoscopy; subjective refraction and Javal's rule; and subjective refraction and Grosvenor et al. version were −0.87 to 1.25, −1.49 to 1.99, −0.73 to 1.93, and −0.89 to 1.7, respectively, for the total astigmatism. The study showed that autorefraction and Javal's rule may provide a starting point for subjective refraction cylinder power determination but only retinoscopy may satisfactorily replace subjective refraction total astigmatism when subjective refraction is not applicable. PMID:27803811

  6. The approximate analysis of the electromagnetic characters of 3-D radome by complex astigmatic wave theory

    NASA Astrophysics Data System (ADS)

    Wang, Yueqing; Wu, Guisheng; Chen, Zhenyang

    The complex astigmatic wave, which imitates the 3-D beam in high-frequency, is an effective method to analyze the electromagnetic characters of the 3-D arbitrarily curved radome. A number of calculations for the ellipsoidal sandwich radome are performed, and the stereoscopic graphics of the results are constructed. Comparing with the experiments, it is shown that this method can be used to simplify analysis and optimization design for many kinds of 3-D radome.

  7. [Optimization of broad-band flat-field holographic concave grating without astigmatism].

    PubMed

    Kong, Peng; Tang, Yu-guo; Bayanheshig; Li, Wen-hao; Cui, Jin-jiang

    2012-02-01

    The desirable imaging locations of the flat-field holographic concave gratings should be in a plane. And the object can be imaged perfectly by the grating when the tangential focal curve and sagittal focal curve both superpose the intersection of the image plane and dispersion plane. But actually, the defocus can not be eliminated over the entire wavelength range, while the astigmatism vanishes when the grating parameters satisfy some conditions. An optimization method for broad-band flat-field holographic concave gratings with absolute astigmatism correction was proposed. The ray tracing software ZEMAX was used for investigating the imaging properties of the grating. And we made a comparison between spectral performance of gratings designed by this new method and that by conventional method, respectively. The results indicated that the spectral performance of gratings designed by using the absolute astigmatism correction method can be as good as gratings designed with the conventional method. And the focusing performance in the sagittal direction is much better, so that the S/N ratio can be greatly improved.

  8. Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

    PubMed Central

    Rho, Chang Rae; Kim, Min-Ji

    2016-01-01

    Purpose. To evaluate surgically induced astigmatism (SIA) and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS) implantation. Methods. The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was used to evaluate the SIA. Hotelling's trace test was used to compare intraindividual changes. Results. Three months postoperatively, the combined mean polar value for SIA changed significantly (Hotelling's T2 = 0.375; P = 0.006). The SIA was 1.54 D at 99° and the average corneal power decreased significantly by 3.8 D. Conclusion. Intacs SK ICRS placement decreased the average corneal power and corneal astigmatism compared to the preoperative corneal power and astigmatism when the corneal pocket incision was made at the preoperative steep meridian. PMID:27795856

  9. A computational investigation of the impact of aberrated Gaussian laser pulses on electron beam properties in laser-wakefield acceleration experiments

    SciTech Connect

    Cummings, P.; Thomas, A. G. R.

    2011-05-15

    Critical to the performance of any future accelerator based on the laser wakefield accelerator is the response of the system to perturbations from ideal. In this paper, we use particle-in-cell simulation using a modified version of the OSIRIS 2.0 framework to demonstrate that comatic optical aberrations in a nominally Gaussian laser pulse are self-corrected by the plasma response, leading to stable propagation and therefore little variation in peak energy, energy spread, or peak current of the accelerated bunch, even for serious aberrations. However, the comatic aberration does lead to enhanced transverse beam emittance in the direction of the coma. Although this may be deleterious to the performance of an accelerator, one useful outcome is that the increased oscillation amplitude of electrons in the wake structure may lead to increased synchrotron radiation emission, which would be partially polarized in the direction of coma.

  10. Use of a Toric Intraocular Lens and a Limbal-Relaxing Incision for the Management of Astigmatism in Combined Glaucoma and Cataract Surgery

    PubMed Central

    Gibbons, Allister

    2016-01-01

    Purpose We report the surgical management of a patient with glaucoma undergoing cataract surgery with high preexisting astigmatism. A combination of techniques was employed for her astigmatism management. Methods A 76-year-old female with 5.5 dpt of corneal astigmatism underwent surgery in her left eye consisting of one-site trabeculectomy, phacoemulsification, toric intraocular lens implantation and a single inferior limbal-relaxing incision. Results Intraocular pressure control was achieved with no medication at 11 mm Hg; before the filtering procedure, the pressure was 16 mm Hg on two topical drugs. Astigmatism was reduced to 0.75 dpt, and both corrected and uncorrected visual acuity improved. Conclusions Astigmatism management can have a good outcome in combined procedures. We encourage surgeons to address astigmatism in the preoperative planning of patients undergoing glaucoma surgery associated with phacoemulsification. PMID:27293408

  11. Aberration correction of unstable resonators

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1994-01-01

    Construction of aspheric reflectors for unstable resonator lasers to provide an arbitrary laser mode inside the resonator to correct aberrations of an output beam by the construction of the shape of an end reflector opposite the output reflector of the resonator cavity, such as aberrations resulting from refraction of a beam exiting the solid of the resonator having an index of refraction greater than 1 or to produce an aberration in the output beam that will precisely compensate for the aberration of an optical train into which the resonator beam is coupled.

  12. SOCCER: Comet Coma Sample Return Mission

    NASA Technical Reports Server (NTRS)

    Albee, A. L.; Uesugi, K. T.; Tsou, Peter

    1994-01-01

    Comets, being considered the most primitive bodies in the solar system, command the highest priority among solar system objects for studying solar nebula evolution and the evolution of life through biogenic elements and compounds. Sample Of Comet Coma Earth Return (SOCCER), a joint effort between NASA and the Institute of Space and Astronautical Science (ISAS) in Japan, has two primary science objectives: (1) the imaging of the comet nucleus and (2) the return to Earth of samples of volatile species and intact dust. This effort makes use of the unique strengths and capabilities of both countries in realizing this important quest for the return of samples from a comet. This paper presents an overview of SOCCER's science payloads, engineering flight system, and its mission operations.

  13. Characterization of Continuum Coma features in Comets

    NASA Astrophysics Data System (ADS)

    Mueller, Beatrice E. A.; Samarasinha, Nalin H.; Hergenrother, Carl W.

    2016-10-01

    We will present the results of an analysis of continuum coma features of comets belonging to different dynamical classes at geocentric distances less than 1.5 AU. Our analysis focusses on groundbased visible observations of over a dozen comets. The position angles of the continuum features close to the nucleus, the curvatures, and extents of radial features will be determined, and the dynamics of dust grains will be investigated. We will also use the change in position angles (if relevant) to place constraints on the periodicity of the repeatability of the features. The prevalence of the features in the sunward direction compared to other orientations will be investigated. We will further compare continuum features with CN features when available. This investigation will eventually lead to the discrimination between hemispherical and localized outgassing for the sunward continuum features seen in comets.We acknowledge support from the NASA SSW and PAST programs.

  14. Endozepine-4 levels are increased in hepatic coma

    PubMed Central

    Malaguarnera, Giulia; Vacante, Marco; Drago, Filippo; Bertino, Gaetano; Motta, Massimo; Giordano, Maria; Malaguarnera, Michele

    2015-01-01

    AIM: To evaluate the serum levels of endozepine-4, their relation with ammonia serum levels, the grading of coma and the severity of cirrhosis, in patients with hepatic coma. METHODS: In this study we included 20 subjects with Hepatic coma, 20 subjects with minimal hepatic encephalopathy (MHE) and 20 subjects control. All subjects underwent blood analysis, Child Pugh and Model for End - stage liver disease (MELD) assessment, endozepine-4 analysis. RESULTS: Subjects with hepatic coma showed significant difference in endozepine-4 (P < 0.001) and NH3 levels (P < 0.001) compared both to MHE and controls patients. Between NH3 and endozepine-4 we observed a significant correlation (P = 0.009; Pearson correlation 0.570). There was a significant correlation between endozepine-4 and MELD (P = 0.017; Pearson correlation = 0.529). In our study blood ammonia concentration was noted to be raised in patients with hepatic coma, with the highest ammonia levels being found in those who were comatose. We also found a high correlation between endozepine-4 and ammonia (P < 0.001). In patients with grade IV hepatic coma, endozepine levels were significantly higher compared to other groups. CONCLUSION: This study suggests that an increased level of endozepine in subjects with higher levels of MELD was observed. In conclusion, data concerning involvement of the GABA-ergic system in HE coma could be explained by stage-specific alterations. PMID:26290636

  15. Comets: Gas in the Inner Coma

    NASA Astrophysics Data System (ADS)

    Ford, Holland

    2003-07-01

    Our target of opportunity program aims at understanding the nucleus-coma interface in comets. Imaging of the near-nucleus region, from both the in situ spacecraft missions to comet Halley in 1986, and more recently with the WFPC2 Planetary Camera, has revealed the structure and evolution of the dust jets associated with active areas on the surface of the nucleus. These dust jets are thought to be driven by the vaporization of the volatiles trapped in the cometary ice. However, the total source inventory of the gaseous component of the coma is not known as there has not been to date direct imaging of a "parent" molecule vaporized directly from the nucleus. In the spectral range of the SBC, the dominant emissions are the Fourth Positive band system of CO and the resonance transitions of its dissociation products carbon and oxygen {oxygen is also produced by the photodissociation of water}. The latter, as dissociation products, are rather extended but the CO emission is concentrated close to the nucleus {McPhate et al. 1999}. Thus, imaging with the SBC using the BaF_2 filter to remove the OI 1304 A will provide a measure of the gas flow leaving the comet's nucleus. In the event of outbursts {often associated with the rotation of active areas into the sunlit hemisphere}, sequential images can provide a direct measure of the gas outflow velocity. The possible presence of a distributed source of CO {such as the purported "CHON" grains invoked to explain the distribution recorded by the Giotto neutral mass spectrometer at Halley} will also be determined. We note that while CO can be detected spectroscopically from the ground at both infrared and millimeter wavelengths, both of these require very high spectral resolving power and the techniques are not suitable for direct imaging of the CO.

  16. Which EEG patterns in coma are nonconvulsive status epilepticus?

    PubMed

    Trinka, Eugen; Leitinger, Markus

    2015-08-01

    Nonconvulsive status epilepticus (NCSE) is common in patients with coma with a prevalence between 5% and 48%. Patients in deep coma may exhibit epileptiform EEG patterns, such as generalized periodic spikes, and there is an ongoing debate about the relationship of these patterns and NCSE. The purposes of this review are (i) to discuss the various EEG patterns found in coma, its fluctuations, and transitions and (ii) to propose modified criteria for NCSE in coma. Classical coma patterns such as diffuse polymorphic delta activity, spindle coma, alpha/theta coma, low output voltage, or burst suppression do not reflect NCSE. Any ictal patterns with a typical spatiotemporal evolution or epileptiform discharges faster than 2.5 Hz in a comatose patient reflect nonconvulsive seizures or NCSE and should be treated. Generalized periodic diacharges or lateralized periodic discharges (GPDs/LPDs) with a frequency of less than 2.5 Hz or rhythmic discharges (RDs) faster than 0.5 Hz are the borderland of NCSE in coma. In these cases, at least one of the additional criteria is needed to diagnose NCSE (a) subtle clinical ictal phenomena, (b) typical spatiotemporal evolution, or (c) response to antiepileptic drug treatment. There is currently no consensus about how long these patterns must be present to qualify for NCSE, and the distinction from nonconvulsive seizures in patients with critical illness or in comatose patients seems arbitrary. The Salzburg Consensus Criteria for NCSE [1] have been modified according to the Standardized Terminology of the American Clinical Neurophysiology Society [2] and validated in three different cohorts, with a sensitivity of 97.2%, a specificity of 95.9%, and a diagnostic accuracy of 96.3% in patients with clinical signs of NCSE. Their diagnostic utility in different cohorts with patients in deep coma has to be studied in the future. This article is part of a Special Issue entitled "Status Epilepticus".

  17. SMILE and Wavefront-Guided LASIK Out-Compete Other Refractive Surgeries in Ameliorating the Induction of High-Order Aberrations in Anterior Corneal Surface

    PubMed Central

    2016-01-01

    Purpose. To compare the change of anterior corneal higher-order aberrations (HOAs) after laser in situ keratomileusis (LASIK), wavefront-guided LASIK with iris registration (WF-LASIK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE). Methods. In a prospective study, 82 eyes underwent LASIK, 119 eyes underwent WF-LASIK, 88 eyes underwent FS-LASIK, and 170 eyes underwent SMILE surgery. HOAs were measured with Pentacam device preoperatively and 6 months after surgery. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs, spherical aberration (SA), horizontal coma, and vertical coma over 6 mm diameter central corneal zone. Results. Six months postoperatively, all procedures result in increase of anterior corneal total HOAs and SA. There were no significant differences in the induced HOAs between LASIK and FS-LASIK, while SMILE induced fewer total HOAs and SA compared with LASIK and FS-LASIK. Similarly, WF-LASIK also induced less total HOAs than LASIK and FS-LASIK, but only fewer SA than FS-LASIK (P < 0.05). No significant difference could be detected in the induced total HOAs and SA between SMILE and WF-LASIK, whereas SMILE induced more horizontal coma and vertical coma compared with WF-LASIK (P < 0.05). Conclusion. FS-LASIK and LASIK induced comparable anterior corneal HOAs. Compared to LASIK and FS-LASIK, both SMILE and WF-LASIK showed advantages in inducing less total HOAs. In addition, SMILE also possesses better ability to reduce the induction of SA in comparison with LASIK and FS-LASIK. However, SMILE induced more horizontal coma and vertical coma compared with WF-LASIK, indicating that the centration of SMILE procedure is probably less precise than WF-LASIK.

  18. Camera processing with chromatic aberration.

    PubMed

    Korneliussen, Jan Tore; Hirakawa, Keigo

    2014-10-01

    Since the refractive index of materials commonly used for lens depends on the wavelengths of light, practical camera optics fail to converge light to a single point on an image plane. Known as chromatic aberration, this phenomenon distorts image details by introducing magnification error, defocus blur, and color fringes. Though achromatic and apochromatic lens designs reduce chromatic aberration to a degree, they are complex and expensive and they do not offer a perfect correction. In this paper, we propose a new postcapture processing scheme designed to overcome these problems computationally. Specifically, the proposed solution is comprised of chromatic aberration-tolerant demosaicking algorithm and post-demosaicking chromatic aberration correction. Experiments with simulated and real sensor data verify that the chromatic aberration is effectively corrected. PMID:25163060

  19. An optical tomography PSF almost insensitive to aberrations: the benefit of a spatial incoherent illumination (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Xiao, Peng; Fink, Mathias; Boccara, A. Claude

    2016-03-01

    An aberrated imaging system PSF is broadened; this broadening is responsible of the blurring of the images. A lot of effort has been carried out to correct the effects of aberrations on OCT images for eye examination or biological samples. We have worked on quantifying the effect of geometrical aberrations on Full-Field OCT images and found that there is mostly no loss of resolution but a decrease of the signal level. This is obviously why we use these signals as metric to correct the wavefront distortion. Moreover we found that this absence of blurring, which is due to the fact that we record the dot product of a diffraction limited reference signal and the distorted sample signal, is specific to the use of an incoherent illumination and did not show up with OCT approaches that use spatially coherent sources. More precisely the loss in signal is roughly proportional to the square root of the Strehl ratio: for example, a Strehl ratio of 1/9, which is considered to give a low quality image, would only be 1/3 in Full-Field OCT while keeping the sharpness of the image. Using both an USAF resolution target and a transmissive SLM we have demonstrated this unique feature of sharpness conservation. It was also confirmed by using biological samples. We think that we can thus restrict the aberration corrections in eye examination to the main aberrations (e.g. focus and astigmatism) that will increase the speed of the correction.

  20. Between My Body and My "Dead Body": Narratives of Coma.

    PubMed

    Meoded Danon, Limor

    2016-01-01

    This article is based on narrative research that focuses on corporeal experience during coma and during the rehabilitation process. Seventeen participants from different areas of Israel who had been in various kinds of coma states reveal what the corporeal experience of coma is. The participants are divided into three types of narrative protagonists--"dead-alive," "rational," and "emissaries." Each of the participants redefined the boundaries of the body, especially in cases when they spoke of experiences they did not understand as corporeal, for example, out-of-body experiences, near-death experiences, or experiences of being between the earthly and unearthly. Their struggle to find suitable words to tell their coma stories emphasizes these boundaries between experiencing and telling, which crossed the normative discursive border of the medical establishment and illustrates the ambiguous nature of human existence.

  1. [Intracranial hypertension in severe diabetic ketoacidosis with coma. Two cases].

    PubMed

    Blanc, P L; Bedock, B; Jay, S; Martin, A; Marc, J M

    1994-11-19

    We observed two cases of severe diabetic ketoacidosis with coma and shock. In one case, coma was present at admission and in the second occurred within 15 hours. In both cases, intracranial hypertension was confirmed with an extradural captor. These findings are in agreement with observations of brain oedema in diabetic ketoacidosis with coma. Clinical data suggest that brain oedema may occur after a latency period but that clinical expression is much more rare, perhaps favoured by treatment (excessive rehydratation, alkalinization, too sharp drop in blood glucose level). In our cases, despite major fluid infusion, shock persisted requiring norepinephrine. This shock could have been the expression of the severe ketoacidosis or have resulted from an underlying infection. In case of sudden onset coma, a regularly encountered manifestation of brain oedema, respiratory assistance and mannitol infusion must be instituted rapidly. With this type of management, it should be possible to improve the severe prognosis of brain oedema in diabetic ketoacidosis. PMID:7899292

  2. Sublimating grains model of cometary coma.

    NASA Astrophysics Data System (ADS)

    Faggi, S.; Tozzi, G. P.; Brucato, J. R.

    Billion years of space weathering produces a crust of organic matter (see e.g. Kanuchova et al. 2012) that will be released when a comet enter for the first time in the inner Solar System. New comets, coming form the Oort Colud at their first passage close to the Sun, are particularly important because they are not differentiated by the Solar radiation and they are supposed to have a large quantity of ice organic matter close to the surface. When a comet approach to the Sun, its activity is driven by the sublimation of these nucleus ices: if the heliocentric distances, R_H , is greater than 3 AU the sublimation of CO and CO_2 ices is the main source of comet activity, otherwise at shorter distances, the sublimation of water become the most important mechanism of activity. These gases, escaping from the nucleus, drag in the coma grains that can be refractory dust (silicates, carbon), water ice and/or organic ices. Oort comets at their first passage in the inner Solar System, should produce an halo of organic or water icy particles. Our group has been monitoring new, inbound, bright Oort comets (C/2011 F1, C/2012 S1, C/2012 K1, C/2013 V5, C/2012 F3, C/2013 US10, C/2013 X1) to search for these icy grains. The method consists in detecting the cloud of sublimating grains in the inner coma by using the Sigma Af function (Tozzi et al. 2007) directly from images. However this over-population of grains, beside the sublimation, can be also due to short time activity (outburst) or too big grains expanding at very slow velocity, as it has been found in comet 67P/C-G (Tozzi eta al, 2011, A&A, 531, 54). To disentangle between the phenomena it is necessary to monitor the comet both at short timescale, for the outbursts (by repeating the observations after few nights), and at long term (weeks-months). If the cloud does not expand with the decreasing of the heliocentric distance there is high probability that we are in presence of organic and/or water ice grains. We can disentangle

  3. Cometary Coma Chemical Composition (C4) Mission

    NASA Technical Reports Server (NTRS)

    Carle, Glenn C.; Clark, Benton C.; Knocke, Philip C.; OHara, Bonnie J.; Adams, Larry; Niemann, Hasso B.; Alexander, Merle; Veverka, Joseph; Goldstein, Raymond; Huebner, Walter; Morrison, David (Technical Monitor)

    1994-01-01

    Cometary exploration remains of great importance to virtually all of space science. Because comets are presumed to be remnants of the early solar nebula, they are expected to provide fundamental knowledge as to the origin and development of the solar system as well as to be key to understanding of the source of volatiles and even life itself in the inner solar system. Clearly the time for a detailed study of the composition of these apparent messages from the past has come. A comet rendezvous mission, the Cometary Coma Chemical Composition (C4) Mission, is now being studied as a candidate for the new Discovery program. This mission is a highly-focussed and usefully-limited subset of the Cometary Rendezvous Asteroid Flyby (CRAF) Mission. The C4 mission will concentrate on measurements that will produce an understanding of the composition and physical makeup of a cometary nucleus. The core science goals of the C4 mission are 1) to determine the chemical, elemental, and isotopic composition of a cometary nucleus and 2) to characterize the chemical and isotopic nature of its atmosphere. A related goal is to obtain temporal information about the development of the cometary coma as a function of time and orbital position. The four short-period comets -- Tempel 1, Tempel 2, Churyumov-Gerasimenko, and Wirtanen -which all appear to have acceptable dust production rates, were identified as candidate targets. Mission opportunities have been identified beginning as early as 1998. Tempel I with a launch in 1999, however, remains the baseline comet for studies of and planning the C4 mission. The C4 mission incorporates two science instruments and two engineering instruments in the payload to obtain the desired measurements. The science instruments include an advanced version of the Cometary Ice and Dust Experiment (CIDEX), a mini-CIDEX with a sample collection system, an X-ray Fluorescence Spectrometer and a Pyrolysis-Gas Chromatograph, and a simplified version of the Neutral

  4. Chromosome Aberrations in Astronauts

    NASA Technical Reports Server (NTRS)

    George, Kerry A.; Durante, M.; Cucinotta, Francis A.

    2007-01-01

    A review of currently available data on in vivo induced chromosome damage in the blood lymphocytes of astronauts proves that, after protracted exposure of a few months or more to space radiation, cytogenetic biodosimetry analyses of blood collected within a week or two of return from space provides a reliable estimate of equivalent radiation dose and risk. Recent studies indicate that biodosimetry estimates from single spaceflights lie within the range expected from physical dosimetry and biophysical models, but very large uncertainties are associated with single individual measurements and the total sample population remains low. Retrospective doses may be more difficult to estimate because of the fairly rapid time-dependent loss of "stable" aberrations in blood lymphocytes. Also, biodosimetry estimates from individuals who participate in multiple missions, or very long (interplanetary) missions, may be complicated by an adaptive response to space radiation and/or changes in lymphocyte survival and repopulation. A discussion of published data is presented and specific issues related to space radiation biodosimetry protocols are discussed.

  5. Visual outcomes of topography-guided excimer laser surgery for treatment of patients with irregular astigmatism.

    PubMed

    Ghoreishi, Mohammad; Naderi Beni, Afsaneh; Naderi Beni, Zahra

    2014-01-01

    The aim of this study was to evaluate the efficacy, safety, and predictability of topography-guided treatments to enhance refractive status following other corneal surgical procedures. In a prospective case series study, 28 consecutive eyes of 26 patients with irregular astigmatism after radial keratotomy, corneal transplant, small hyperopic and myopic excimer laser optical zones, and corneal scars were operated. Laser-assisted in situ keratomileusis (LASIK) (n = 8) and photorefractive keratectomy (PRK) (n = 20) were performed using the ALLEGRETTO WAVE excimer laser and topography-guided customized ablation treatment software. Preoperative and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest and cycloplegic refraction, and corneal topography with asphericity were analyzed in 12 months follow-up. Uncorrected visual acuity (UCVA) changed from 0.2 ± 0.2 or (20/100 ± 20/100) to 0.51 ± 0.31 or (20/40 ± 20/60) in the LASIK group (P = 0.01) and from 0.34 ± 0.16 or (20/60 ± 20/120) to 0.5 ± 0.23 or (20/40 ± 20/80) in the PRK group (P = 0.01). Refractive cylinder decreased from -3.2 ± 0.84 diopters (D) to -2.06 ± 0.42 D in the LASIK group (P = 0.07) and from -2.25 ± 0.39 D to -1.5 ± 0.23 D in the PRK group (P = 0.008). Best corrected visual acuity did not change significantly in either group. Topography-guided treatment is effective in correcting the irregular astigmatism after refractive surgery. Topography-guided PRK can significantly reduce irregular astigmatism and increase the UCVA and BCVA.

  6. Astigmatic multifocus microscopy enables deep 3D super-resolved imaging

    PubMed Central

    Oudjedi, Laura; Fiche, Jean-Bernard; Abrahamsson, Sara; Mazenq, Laurent; Lecestre, Aurélie; Calmon, Pierre-François; Cerf, Aline; Nöllmann, Marcelo

    2016-01-01

    We have developed a 3D super-resolution microscopy method that enables deep imaging in cells. This technique relies on the effective combination of multifocus microscopy and astigmatic 3D single-molecule localization microscopy. We describe the optical system and the fabrication process of its key element, the multifocus grating. Then, two strategies for localizing emitters with our imaging method are presented and compared with a previously described deep 3D localization algorithm. Finally, we demonstrate the performance of the method by imaging the nuclear envelope of eukaryotic cells reaching a depth of field of ~4µm. PMID:27375935

  7. Astigmatic multifocus microscopy enables deep 3D super-resolved imaging.

    PubMed

    Oudjedi, Laura; Fiche, Jean-Bernard; Abrahamsson, Sara; Mazenq, Laurent; Lecestre, Aurélie; Calmon, Pierre-François; Cerf, Aline; Nöllmann, Marcelo

    2016-06-01

    We have developed a 3D super-resolution microscopy method that enables deep imaging in cells. This technique relies on the effective combination of multifocus microscopy and astigmatic 3D single-molecule localization microscopy. We describe the optical system and the fabrication process of its key element, the multifocus grating. Then, two strategies for localizing emitters with our imaging method are presented and compared with a previously described deep 3D localization algorithm. Finally, we demonstrate the performance of the method by imaging the nuclear envelope of eukaryotic cells reaching a depth of field of ~4µm.

  8. The construction of sutureless cataract incision and the management of corneal astigmatism.

    PubMed

    Hall, G W; Krischer, C; Mobasher, B; Rajan, S D

    1993-02-01

    Extrapolating information from equations that govern fluid flow, a theoretical formula is developed for a sutureless cataract incision. This theoretical formula defines the resistance of aqueous outflow as a function of three variables: length of cataract incision, the length of the scleral tunnel, the tortuosity of the outflow channel, and one constant friction factor. The nonlinear relationship of corneal incisions to length, depth, and distance from the visual axis is also examined with respect to their effect on central corneal curvature and control of astigmatism. Finite element analysis of differential equations is discussed as the most plausible technique for predicting these incisional effects.

  9. Correction of Distributed Optical Aberrations

    SciTech Connect

    Baker, K; Olivier, S; Carrano, C; Phillion, D

    2006-02-12

    The objective of this project was to demonstrate the use of multiple distributed deformable mirrors (DMs) to improve the performance of optical systems with distributed aberrations. This concept is expected to provide dramatic improvement in the optical performance of systems in applications where the aberrations are distributed along the optical path or within the instrument itself. Our approach used multiple actuated DMs distributed to match the aberration distribution. The project developed the algorithms necessary to determine the required corrections and simulate the performance of these multiple DM systems.

  10. Long-term outcomes of wedge resection at the limbus for high irregular corneal astigmatism after repaired corneal laceration

    PubMed Central

    Du, Jun; Zheng, Guang-Ying; Wen, Cheng-Lin; Zhang, Xiao-Fang; Zhu, Yu

    2016-01-01

    AIM To evaluate the clinical value of wedge resection at corneal limbus in patients with traumatic corneal scarring and high irregular astigmatism. METHODS Patients with traumatic corneal astigmatism received wedge resection at least 6mo after suture removal from corneal wound. The uncorrected distance visual acuities (UCVA) and best corrected distance visual acuities (BCVA), pre- and post-operation astigmatism, spherical equivalent (SE), safety and complications were evaluated. RESULTS Ten eyes (10 patients) were enrolled in this study. Mean follow-up time after wedge resection was 37.8±15.4mo (range, 20-61mo). The mean UCVA improved from +1.07±0.55 logMAR to +0.43±0.22 logMAR (P=0.000) and the mean BCVA from +0.50±0.30 logMAR to +0.15±0.17 logMAR (P=0.000). The mean astigmatism power measured by retinoscopy was -2.03±2.27 D postoperatively and -2.83±4.52 D preoperatively (P=0.310). The mean SE was -0.74±1.61 D postoperatively and -0.64±1.89 D preoperatively (P=0.601). Two cases developed mild pannus near the sutures. No corneal perforation, infectious keratitis or wound gape occurred. CONCLUSION Corneal-scleral limbal wedge resection with compression suture is a safe, effective treatment for poor patients with high irregular corneal astigmatism after corneal-scleral penetrating injury. Retinoscopy can prove particularly useful for high irregular corneal astigmatism when other measurements are not amenable. PMID:27366685

  11. Phase aberration effects in elastography.

    PubMed

    Varghese, T; Bilgen, M; Ophir, J

    2001-06-01

    In sonography, phase aberration plays a role in the corruption of sonograms. Phase aberration does not have a significant impact on elastography, if statistically similar phase errors are present in both the pre- and postcompression signals. However, if the phase errors are present in only one of the pre- or postcompression signal pairs, the precision of the strain estimation process will be reduced. In some cases, increased phase errors may occur only in the postcompression signal due to changes in the tissue structure with the applied compression. Phase-aberration effects increase with applied strain and may be viewed as an image quality derating factor, much like frequency-dependent attenuation or undesired lateral tissue motion. In this paper, we present a theoretical and simulation study of the effects of phase aberration on the elastographic strain-estimation process, using the strain filter approach.

  12. Optimization of nonimaging focusing heliostat in dynamic correction of astigmatism for a wide range of incident angles.

    PubMed

    Chong, Kok-Keong

    2010-05-15

    To overcome astigmatism has always been a great challenge in designing a heliostat capable of focusing the sunlight on a small receiver throughout the year. In this Letter, a nonimaging focusing heliostat with a dynamic adjustment of facet mirrors in a group manner has been analyzed for optimizing the astigmatic correction in a wide range of incident angles. This what is to the author's knowledge a new heliostat is not only designed to serve the purpose of concentrating sunlight to several hundreds of suns, but also to significantly reduce the variation of the solar flux distribution with the incident angle.

  13. Refractive lenticule extraction (ReLEx) through a small incision (SMILE) for correction of myopia and myopic astigmatism: current perspectives

    PubMed Central

    Ağca, Alper; Demirok, Ahmet; Yıldırım, Yusuf; Demircan, Ali; Yaşa, Dilek; Yeşilkaya, Ceren; Perente, İrfan; Taşkapılı, Muhittin

    2016-01-01

    Small-incision lenticule extraction (SMILE) is an alternative to laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for the correction of myopia and myopic astigmatism. SMILE can be performed for the treatment of myopia ≤−12 D and astigmatism ≤5 D. The technology is currently only available in the VisuMax femtosecond laser platform. It offers several advantages over LASIK and PRK; however, hyperopia treatment, topography-guided treatment, and cyclotorsion control are not available in the current platform. The working principles, potential advantages, and disadvantages are discussed in this review. PMID:27757010

  14. Apparatus for and method of correcting for astigmatism in a light beam reflected off of a light reflecting surface

    DOEpatents

    Sawicki, R.H.; Sweatt, W.

    1985-11-21

    A technique for adjustably correcting for astigmatism in a light beam is disclosed herein. This technique defines a flat, rectangular light reflecting surface having opposite reinforced side edges and which is resiliently bendable, to a limited extent, into different concave and/or convex cylindrical curvatures about a particular axis and provides for adjustably bending the light reflecting surface into one of different curvatures depending upon the astigmatism to be corrected and for fixedly maintaining the curvature selected. In the embodiment disclosed, the light reflecting surface is adjustably bendable into the selected cylindrical curvature by application of a particular bending moment to the reinforced side edges of the light reflecting surface.

  15. Testing chameleon gravity with the Coma cluster

    SciTech Connect

    Terukina, Ayumu; Yamamoto, Kazuhiro; Lombriser, Lucas; Bacon, David; Koyama, Kazuya; Nichol, Robert C. E-mail: lucas.lombriser@port.ac.uk E-mail: david.bacon@port.ac.uk E-mail: bob.nichol@port.ac.uk

    2014-04-01

    We propose a novel method to test the gravitational interactions in the outskirts of galaxy clusters. When gravity is modified, this is typically accompanied by the introduction of an additional scalar degree of freedom, which mediates an attractive fifth force. The presence of an extra gravitational coupling, however, is tightly constrained by local measurements. In chameleon modifications of gravity, local tests can be evaded by employing a screening mechanism that suppresses the fifth force in dense environments. While the chameleon field may be screened in the interior of the cluster, its outer region can still be affected by the extra force, introducing a deviation between the hydrostatic and lensing mass of the cluster. Thus, the chameleon modification can be tested by combining the gas and lensing measurements of the cluster. We demonstrate the operability of our method with the Coma cluster, for which both a lensing measurement and gas observations from the X-ray surface brightness, the X-ray temperature, and the Sunyaev-Zel'dovich effect are available. Using the joint observational data set, we perform a Markov chain Monte Carlo analysis of the parameter space describing the different profiles in both the Newtonian and chameleon scenarios. We report competitive constraints on the chameleon field amplitude and its coupling strength to matter. In the case of f(R) gravity, corresponding to a specific choice of the coupling, we find an upper bound on the background field amplitude of |f{sub R0}| < 6 × 10{sup −5}, which is currently the tightest constraint on cosmological scales.

  16. 3D high-density localization microscopy using hybrid astigmatic/ biplane imaging and sparse image reconstruction.

    PubMed

    Min, Junhong; Holden, Seamus J; Carlini, Lina; Unser, Michael; Manley, Suliana; Ye, Jong Chul

    2014-11-01

    Localization microscopy achieves nanoscale spatial resolution by iterative localization of sparsely activated molecules, which generally leads to a long acquisition time. By implementing advanced algorithms to treat overlapping point spread functions (PSFs), imaging of densely activated molecules can improve the limited temporal resolution, as has been well demonstrated in two-dimensional imaging. However, three-dimensional (3D) localization of high-density data remains challenging since PSFs are far more similar along the axial dimension than the lateral dimensions. Here, we present a new, high-density 3D imaging system and algorithm. The hybrid system is implemented by combining astigmatic and biplane imaging. The proposed 3D reconstruction algorithm is extended from our state-of-the art 2D high-density localization algorithm. Using mutual coherence analysis of model PSFs, we validated that the hybrid system is more suitable than astigmatic or biplane imaging alone for 3D localization of high-density data. The efficacy of the proposed method was confirmed via simulation and real data of microtubules. Furthermore, we also successfully demonstrated fluorescent-protein-based live cell 3D localization microscopy with a temporal resolution of just 3 seconds, capturing fast dynamics of the endoplasmic recticulum.

  17. Independent control of beam astigmatism and ellipticity using a SLM for fs-laser waveguide writing.

    PubMed

    Ruiz de la Cruz, A; Ferrer, A; Gawelda, W; Puerto, D; Sosa, M Galván; Siegel, J; Solis, J

    2009-11-01

    We have used a low repetition rate (1 kHz), femtosecond laser amplifier in combination with a spatial light modulator (SLM) to write optical waveguides with controllable cross-section inside a phosphate glass sample. The SLM is used to induce a controllable amount of astigmatism in the beam wavefront while the beam ellipticity is controlled through the propagation distance from the SLM to the focusing optics of the writing set-up. The beam astigmatism leads to the formation of two separate disk-shaped foci lying in orthogonal planes. Additionally, the ellipticity has the effect of enabling control over the relative peak irradiances of the two foci, making it possible to bring the peak irradiance of one of them below the material transformation threshold. This allows producing a single waveguide with controllable cross-section. Numerical simulations of the irradiance distribution at the focal region under different beam shaping conditions are compared to in situ obtained experimental plasma emission images and structures produced inside the glass, leading to a very satisfactory agreement. Finally, guiding structures with controllable cross-section are successfully produced in the phosphate glass using this approach.

  18. Comparison of Two Different Scheimpflug Devices in the Detection of Keratoconus, Regular Astigmatism, and Healthy Corneas

    PubMed Central

    Finis, David; Ralla, Bernhard; Karbe, Maria; Borrelli, Maria; Schrader, Stefan; Geerling, Gerd

    2015-01-01

    Aim. The aim of this study was to determine the intra- and interobserver variability of two Scheimpflug based camera systems, Pentacam and Sirius. In addition, the comparability of the measurements was tested in healthy subjects, subjects with regular astigmatism, and keratoconus patients. Methods. Intra- and interobserver variability were assessed in 20 healthy corneas. Pachymetry values were also compared with ultrasound pachymetry as a reference measurement. To detect possible differences between the two devices, 82 eyes with clinically established keratoconus, 30 eyes with regular astigmatism (>1.5 D), and 60 eyes without corneal pathologies were included in this prospective study. Results. Pachymetry and keratometry showed good intra- and interobserver variability for both devices. Pachymetry values obtained with the Sirius system (579 ± 58 μm) were significantly higher compared to the Pentacam system (551 ± 40 μm, P < 0.001) and to ultrasound pachymetry (550 ± 43 μm, P < 0.001). Significant interdevice differences were found regarding the majority of the detected keratometry parameters. Conclusions. Both devices show almost perfect reproducibility in healthy subjects. However, pachymetry and keratometry values of the two devices should not be used interchangeably. PMID:25954510

  19. Immunohistochemical investigation of the coma blister and its pathogenesis.

    PubMed

    Kashiwagi, Masayuki; Ishigami, Akiko; Hara, Kenji; Matsusue, Aya; Waters, Brian; Takayama, Mio; Tokunaga, Itsuo; Nishimura, Akiyoshi; Kubo, Shin-ichi

    2013-01-01

    The erythematous patches and vesicles that are observed in coma patients, usually from an overdose of medication, are known as coma blisters. However, it is unknown whether the degenerated sweat gland is a necrosis or apoptosis. We immunohistochemically examined such skin lesions to investigate the characteristics and pathogenesis of the coma blister. Skin lesions were obtained from a forensic autopsy case, a woman in her thirties, of caffeine intoxication. Those lesions were observed in the left femoral, the lower left thigh, and the right knee. Histologically, the skin lesions showed that the keratinocytes had necrosed and the epidermis was thin in some areas. Eccrine sweat gland degeneration was observed. Obvious inflammatory cell infiltrations were not detected. Immunohistochemically, we stained each skin lesion against CD3, CD8, CD45RO, cytokeratin, 70 kD heat shock protein, ubiquitin, 150 kD oxygen regulated protein, and caspase-cleaved keratin 18 neo-epitope M30. They were also stained with an in situ apoptosis detection kit. Degenerated sweat glands featured CD45RO and M30 immunoreactivity. Immunohistochemical staining for CD45RO, CK-L, and M30 might be useful to observe sweat gland degeneration in the coma blister. Therefore, the apoptosis might be related to coma blisters and sweat gland degenerations.

  20. Bacteriology of aspiration pneumonia in patients with acute coma.

    PubMed

    Lauterbach, Enise; Voss, Frederik; Gerigk, Roland; Lauterbach, Michael

    2014-12-01

    Loss of protective airway reflexes in patients with acute coma puts these patients at risk of aspiration pneumonia complicating the course of the primary disease. Available data vary considerably with regard to bacteriology, role of anaerobic bacteria, and antibiotic treatment. Our objective was to research the bacteriology of aspiration pneumonia in acute coma patients who were not pre-treated with antibiotics or hospitalized within 30 days prior to the event. We prospectively analyzed 127 patient records from adult patients admitted, intubated and ventilated to a tertiary medical intensive care unit with acute coma. Bacteriology and antibiotic resistance testing from tracheal aspirate sampled within 24 h after admission, blood cultures, ICU scores (APACHE II, SOFA), hematology, and clinical chemistry were assessed. Patients were followed up until death or hospital discharge. The majority of patients with acute coma suffered from acute cardiovascular disorders, predominantly myocardial infarction, followed by poisonings, and coma of unknown cause. In a majority of our patients, microaspiration resulted in overt infection. Most frequently S. aureus, H. influenzae, and S. pneumoniae were isolated. Anaerobic bacteria (Bacteroides spec., Fusobacteria, Prevotella spec.) were isolated from tracheal aspirate in a minority of patients, and predominantly as part of a mixed infection. Antibiotic monotherapy with a 2nd generation cephalosporin, or a 3rd generation gyrase inhibitor, was most effective in our patients regardless of the presence of anaerobic bacteria.

  1. Efficacy of Nasya (nasal medication) in coma: A case study.

    PubMed

    Ramteke, Rajkala S; Patil, Panchakshari D; Thakar, Anup B

    2016-01-01

    For emergency conditions, Ayurveda has never been given importance in recent times. However, there are certain emergency conditions where biomedicine has limitations but, Ayurveda can provide solution. Classics have many references regarding management of acute conditions like syncope, coma, episodic conditions of bronchial asthma, epilepsy, etc., In the present study, a 61 year female patient had a two year history of hypertension and was suffering with coma. She was treated with an Ayurvedic treatment modality. Nasya (nasal medication) of Trikaṭu cūrṇa (powder) for seven days, followed by dhūmapāna (~fumigation) with saṅkhyāsthāpana (consciousness restorative) drugs for seven days was administered. The outcome of this management was appreciable, as it resulted in positive changes in Glasgow Coma Scale (GSCS) from 3 to 11. PMID:27621522

  2. Efficacy of Nasya (nasal medication) in coma: A case study

    PubMed Central

    Ramteke, Rajkala S.; Patil, Panchakshari D.; Thakar, Anup B.

    2016-01-01

    For emergency conditions, Ayurveda has never been given importance in recent times. However, there are certain emergency conditions where biomedicine has limitations but, Ayurveda can provide solution. Classics have many references regarding management of acute conditions like syncope, coma, episodic conditions of bronchial asthma, epilepsy, etc., In the present study, a 61 year female patient had a two year history of hypertension and was suffering with coma. She was treated with an Ayurvedic treatment modality. Nasya (nasal medication) of Trikaṭu cūrṇa (powder) for seven days, followed by dhūmapāna (~fumigation) with saṅkhyāsthāpana (consciousness restorative) drugs for seven days was administered. The outcome of this management was appreciable, as it resulted in positive changes in Glasgow Coma Scale (GSCS) from 3 to 11.

  3. EXTINCTION IN THE COMA OF COMET 17P/HOLMES

    SciTech Connect

    Lacerda, Pedro; Jewitt, David

    2012-11-20

    On 2007 October 29, the outbursting comet 17P/Holmes passed within 0.''79 of a background star. We recorded the event using optical, narrowband photometry and detect a 3%-4% dip in stellar brightness bracketing the time of closest approach to the comet nucleus. The detected dimming implies an optical depth {tau} Almost-Equal-To 0.04 at 1.''5 from the nucleus and an optical depth toward the nucleus center {tau}{sub n} < 13.3. At the time of our observations, the coma was optically thick only within {rho} {approx}< 0.''01 from the nucleus. By combining the measured extinction and the scattered light from the coma, we estimate a dust red albedo p{sub d} = 0.006 {+-} 0.002 at {alpha} = 16 Degree-Sign phase angle. Our measurements place the most stringent constraints on the extinction optical depth of any cometary coma.

  4. Efficacy of Nasya (nasal medication) in coma: A case study

    PubMed Central

    Ramteke, Rajkala S.; Patil, Panchakshari D.; Thakar, Anup B.

    2016-01-01

    For emergency conditions, Ayurveda has never been given importance in recent times. However, there are certain emergency conditions where biomedicine has limitations but, Ayurveda can provide solution. Classics have many references regarding management of acute conditions like syncope, coma, episodic conditions of bronchial asthma, epilepsy, etc., In the present study, a 61 year female patient had a two year history of hypertension and was suffering with coma. She was treated with an Ayurvedic treatment modality. Nasya (nasal medication) of Trikaṭu cūrṇa (powder) for seven days, followed by dhūmapāna (~fumigation) with saṅkhyāsthāpana (consciousness restorative) drugs for seven days was administered. The outcome of this management was appreciable, as it resulted in positive changes in Glasgow Coma Scale (GSCS) from 3 to 11. PMID:27621522

  5. An analysis of the coma of comet Bennett 1970 II

    NASA Technical Reports Server (NTRS)

    Oppenheimer, M.

    1978-01-01

    Brightness profiles for emission features of H2O(+) in comet Bennett 1970 II are analyzed, taking into account the role of chemical reactions in the coma. By comparing the rates of transport processes derived from the brightness profile with known chemical rate constants, upper limits on the abundances and production rates of H2O, CH4, NH3, and other possible coma constituents are found. The derived upper limit on the H2O production rate inside 10 to the 4th power km is less than the observed OH production rate averaged over the coma of this comet. It is concluded that the brightness profiles of H2O(+) and OH in comet Bennett 1970 II which are presently available are inconsistent with production of OH primarily by photodissociation of H2O molecules sublimating from the nucleus. The existence of an extended source of H2O is not ruled out.

  6. Flip-flops of FK Comae Berenices

    NASA Astrophysics Data System (ADS)

    Hackman, T.; Pelt, J.; Mantere, M. J.; Jetsu, L.; Korhonen, H.; Granzer, T.; Kajatkari, P.; Lehtinen, J.; Strassmeier, K. G.

    2013-05-01

    Context.FK Comae Berenices is a rapidly rotating magnetically active star, the light curve of which is modulated by cool spots on its surface. It was the first star where the "flip-flop" phenomenon was discovered. Since then, flip-flops in the spot activity have been reported in many other stars. Follow-up studies with increasing length have shown, however, that the phenomenon is more complex than was thought right after its discovery. Aims: Therefore, it is of interest to perform a more thorough study of the evolution of the spot activity in FK Com. In this study, we analyse 15 years of photometric observations with two different time series analysis methods, with a special emphasis on detecting flip-flop type events from the data. Methods: We apply the continuous period search and carrier fit methods on long-term standard Johnson-Cousins V-observations from the years 1995-2010. The observations were carried out with two automated photometric telescopes, Phoenix-10 and Amadeus T7 located in Arizona. Results: We identify complex phase behaviour in 6 of the 15 analysed data segments. We identify five flip-flop events and two cases of phase jumps, where the phase shift is Δφ < 0.4. In addition we see two mergers of spot regions and two cases where the apparent phase shifts are caused by spot regions drifting with respect to each other. Furthermore we detect variations in the rotation period corresponding to a differential rotation coefficient of |k| > 0.031. Conclusions: The flip-flop cannot be interpreted as a single phenomenon, where the main activity jumps from one active longitude to another. In some of our cases the phase shifts can be explained by differential rotation: two spot regions move with different angular velocity and even pass each other. Comparison between the methods show that the carrier fit utility is better in retrieving slow evolution especially from a low amplitude light curve, while the continuous period search is more sensitive in case of

  7. Sexual aberration or instinctual vicissitude? Revisiting freud's "the sexual aberrations".

    PubMed

    Phillips, Sidney H

    2014-04-01

    The author reconsiders Freud's "The Sexual Aberrations," the first of his Three Essays on the Theory of Sexuality (1905), in light of contemporary psychoanalytic theory. Are the concepts of sexual aberration and norm still viable? The author argues that they are necessary but insufficient elements in current theory. He then presents a competing model in which sexuality can be reduced to a more elemental level of disturbance and wish, where it is an expression of a nonsexual wish--for example, to possess or control the object to eliminate separateness. The author presents clinical material to demonstrate this alternative model. PMID:24777366

  8. Polarization Aberrations in Astronomical Telescopes: The Point Spread Function

    NASA Astrophysics Data System (ADS)

    Breckinridge, James B.; Lam, Wai Sze T.; Chipman, Russell A.

    2015-05-01

    and coronagraph applications. (4) Part of the aberration is a polarization-dependent astigmatism, with a magnitude of 22 milliwaves, which enlarges the PSF image. (5) The orthogonally polarized components of unpolarized sources contain different wavefront aberrations, which differ by approximately 32 milliwaves. This implies that a wavefront correction system cannot optimally correct the aberrations for all polarizations simultaneously. (6) The polarization aberrations couple small parts of each polarization component of the light (~10-4) into the orthogonal polarization where these components cause highly distorted secondary, or "ghost" PSF images. (7) The radius of the spatial extent of the 90% encircled energy of these two ghost PSF image is twice as large as the radius of the Airy diffraction pattern. Coronagraphs for terrestrial exoplanet science are expected to image objects 10-10, or 6 orders of magnitude less than the intensity of the instrument-induced "ghost" PSF image, which will interfere with exoplanet measurements. A polarization aberration expansion which approximates the Jones pupil of the example telescope in six polarization terms is presented in the appendix. Individual terms can be associated with particular polarization defects. The dependence of these terms on angles of incidence, numerical aperture, and the Taylor series representation of the Fresnel equations lead to algebraic relations between these parameters and the scaling of the polarization aberrations. These "design rules" applicable to the example telescope are collected in § 5. Currently, exoplanet coronagraph masks are designed and optimized for scalar diffraction in optical systems. Radiation from the "ghost" PSF image leaks around currently designed image plane masks. Here, we show a vector-wave or polarization optimization is recommended. These effects follow from a natural description of the optical system in terms of the Jones matrices associated with each ray path of interest

  9. Hco+ in the Coma of Comet Hale-Bopp

    NASA Astrophysics Data System (ADS)

    Lovell, A. J.; Schloerb, F. P.; Bergin, E. A.; Dickens, J. E.; De Vries, C. H.; Senay, M. C.; Irvine, W. M.

    1997-05-01

    Maps of comet C/1995 O1 (Hale-Bopp) in the millimeter-wave emission of the ion HCO^+ revealed a local minimum near the nucleus position, with a maximum about 100,000 km in the antisolar direction. These observed features of the HCO^+ emission require a low abundance of HCO^+ due to enhanced destruction in the inner coma of the comet, within a region of low electron temperature (T_e). To set constraints on the formation of HCO^+ in the coma, as well as the location and magnitude of the transition to higher T_e, the data are compared with the results of ion-molecule chemistry models.

  10. Emergency Neurological Life Support: Approach to the Patient with Coma.

    PubMed

    Stevens, Robert D; Cadena, Rhonda S; Pineda, Jose

    2015-12-01

    Coma is an acute failure of neuronal systems governing arousal and awareness and represents a medical emergency. When encountering a comatose patient, the clinician must have an organized approach to detect easily remediable causes, prevent ongoing neurologic injury, and determine a hierarchical plan for diagnostic tests, treatments, and neuromonitoring. Coma was chosen as an Emergency Neurological Life Support protocol because timely medical and surgical interventions can be life-saving, and the initial work-up of such patients is critical to establishing a correct diagnosis.

  11. HCO+ in the coma of comet Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Lovell, A. J.; Schloerb, F. P.; Bergin, E. A.; Dickens, J. E.; Devries, C. H.; Senay, M. C.; Irvine, W. M.; Ferris, J. P. (Principal Investigator)

    1997-01-01

    Maps of comet C/1995 O1 (Hale-Bopp) in the millimeter-wave emission of the ion HCO+ revealed a local minimum near the nucleus position, with a maximum about 100,000 km in the antisolar direction. These observed features of the HCO+ emission require a low abundance of HCO+ due to enhanced destruction in the inner coma of the comet, within a region of low electron temperature (Te). To set constraints on the formation of HCO+ in the coma, as well as the location and magnitude of the transition to higher Te, the data are compared with the results of ion-molecule chemistry models.

  12. Electrodynamics of submicron dust in the cometary coma

    NASA Astrophysics Data System (ADS)

    Wallis, M. K.; Hassan, M. H. A.

    1983-05-01

    Electromagnetic forces derived from the solar wind fields act strongly on submicron dust grains in the cometary coma. The grain charge and thus the forces are sensitive to composition and cometary plasma conditions, as well as to grain size. For dielectric grains of 0.1 μm and conducting grains of 0.3 μm or less, the electromagnetic forces dominate over radiation pressure. The stronger accelerations may produce fan-like structures as sometimes observed. They would also cause grains to circumvent the shields designed to protect the Giotto and Vega spacecrafts speeding through comet Halley's dust coma.

  13. Astigmatism management in cataract surgery with Precizon® toric intraocular lens: a prospective study

    PubMed Central

    Vale, Carolina; Menezes, Carlos; Firmino-Machado, J; Rodrigues, Pedro; Lume, Miguel; Tenedório, Paula; Menéres, Pedro; Brochado, Maria do Céu

    2016-01-01

    Purpose The purpose of this study was to evaluate the visual and refractive outcomes and rotational stability of the new aspheric Precizon® toric intraocular lens (IOL) for the correction of corneal astigmatism in cataract surgery. Setting Department of Ophthalmology, Hospital Geral de Santo António – Centro Hospitalar do Porto, EPE and Hospital de Pedro Hispano, Matosinhos, Portugal. Design This was a prospective clinical study. Patients and methods A total of 40 eyes of 27 patients with corneal astigmatism greater than 1.0 diopter (D) underwent cataract surgery with implantation of Precizon® toric IOL. IOL power calculation was performed using optical coherence biometry (IOLMaster®). Outcomes of uncorrected (UDVA) and best-spectacle corrected distance visual acuities (BCDVA), refraction, and IOL rotation were analyzed at the 1st week, 1st, 3rd, and 6th month’s evaluations. Results The median postoperative UDVA was better than preoperative best-spectacle corrected distance visual acuity (0.02 [0.06] logMAR vs 0.19 [0.20] logMAR, P<0.001). At 6 months, postoperative UDVA was 0.1 logMAR or better in 95% of the eyes. At last follow-up, the mean spherical equivalent was reduced from −3.35±3.10 D to −0.02±0.30 D (P<0.001) with 97.5% of the eyes within ±0.50 D of emmetropia. The mean preoperative keratometric cylinder was 2.34±0.95 D and the mean postoperative refractive cylinder was 0.24±0.27 D (P<0.001). The mean IOL rotation was 2.43°±1.55°. None of the IOLs required realignment. Conclusion Precizon® toric IOL revealed very good rotational stability and performance regarding predictability, efficacy, and safety in the correction of preexisting regular corneal astigmatism associated with cataract surgery. PMID:26855559

  14. Active mirrors warped using Zernike polynomials for correcting off-axis aberrations of fixed primary mirrors. II. Optical testing and performance evaluation.

    NASA Astrophysics Data System (ADS)

    Moretto, G.; Lemaitre, G. R.; Bactivelane, T.; Wang, M.; Ferrari, M.; Mazzanti, S.; di Biagio, B.; Borra, E. F.

    1995-12-01

    We investigate the aspherization of an active mirror for correcting third and fifth-order aberrations. We use a stainless steel AISI 420 mirror with a controlled pressure load, two series of 12-punctual radial positions of force application distributed symmetrically in two concentric rings around the mirror. We obtain the wavefronts for Cv1, Sph3, Coma3, Astm3, Comatri, Astm5 as well as those of the added wavefronts. Although this active prototype mirror has general uses, our goal is to compensate the aberrations of a liquid mirror observing at large angles from the zenith.

  15. Three traps in stellar aberration

    NASA Astrophysics Data System (ADS)

    Liebscher, Dierck-E.; Brosche, Peter

    The effect of aberration seems to be one of the simplest in astronomical observations. Nevertheless, it has a long and pertaining history of misunderstanding and wrong interpretation. In the time just before the advent of the theory of relativity, aberration and drag of the aether (as found in Michelson's experiment) are interpreted as contradiction. This contradiction vanishes with the theory of relativity. More obstinate is the misunderstanding that the aberration depends on the relative velocity of source and observer. In the twenties, some physicists and astronomers believed that the consequences of such a relativity, wrongly supposed but never found, would constitute a firm argument against Einstein's theory (Hayn, Tomaschek, Osten, v. Brunn, Courvoisier, Mohorovicic). History forgot their argument, but it is difficult to find a correct explanation of their error (Emden). Instead, the subject is forgotten, and one can conjecture it because of the political side of the argument. This attitude takes its revenge: Misunderstandings are still handed down from textbook to textbook.

  16. Overcoming Polarization Aberrations In Microscopy

    NASA Astrophysics Data System (ADS)

    Hansen, Eric W.

    1988-06-01

    A long-standing problem in polarized light microscopy has been the inability, due to polarization aberrations, to achieve simultaneously high spatial resolution and high contrast. The rotation of the plane of polarization at oblique interfaces between crossed polars causes the pupil function to resemble a dark cross rather than being uniformly dark. Likewise, the point spread function has the visual appearance of a four-leaf clover rather than the ideal Airy disk, and is also space-variant. Images formed with these systems are severely degraded. In this paper the theory of polarization aberrations is applied to the analysis of three solutions to this problem: Reducing the system aperture to block troublesome high-aperture rays; the AVEC-POL method, in which high bias compensation introduces counterbalancing aberrations; and the polarization rectifier, an optical element designed to introduce equal and opposite rotations of the electric vector.

  17. Aberrant DNA Methylation in Keratoacanthoma

    PubMed Central

    Nakagawa, Hidemi

    2016-01-01

    Background Keratoacanthoma (KA) is a self-limiting epidermal tumor for which histopathological examination sometimes suggests malignancy. Based on inconsistent clinical views, KA can be regarded as both a benign tumor and a variant of squamous cell carcinoma (SCC). Aberrant DNA methylation frequently occurs in malignant tumors but it scarcely occurs in benign tumors. Whether aberrant methylation occurs in KA has not been previously examined. Objective The aim is to elucidate whether aberrant methylation of CpG islands (CGI) containing a high density of cytosine-guanine dinucleotide (CpG) sites occurs in KA. Methods Five SCC cell lines, two cultured samples of normal human epidermal keratinocytes (NHEKs), 18 clinical SCC samples, and 21 clinical KA samples were analyzed with Infinium HumanMethylation450 BeadChips, quantitative real-time methylation-specific PCR (RT-MSP) and/or bisulfite sequencing. Results Genome-wide analyses of NHEK, KA, and SCC indicated that there was a greater number of aberrantly hypermethylated CGIs in SCC than in KA and there were aberrantly hypermethylated CGIs which are common in both. Among the common hypermethylated CGIs, RT-MSP and bisulfite sequencing targeting CGIs located on CCDC17, PVR, and MAP3K11 gene bodies also showed that methylation levels were significantly higher in KA than in normal epidermis. Statistical analyses suggested that the methylation level of CGI located on PVR in SCC might be correlated to lymph node metastasis (P = 0.013, Mann-Whitney U test) and that the methylation level of CGI in MAP3K11 in KA might be correlated to age (P = 0.031, linear regression analysis). Conclusion Aberrant DNA methylation occurs in KA. PMID:27788211

  18. How To Measure Gravitational Aberration?

    NASA Astrophysics Data System (ADS)

    Krizek, M.; Solcova, A.

    2007-08-01

    In 1905, Henri Poincaré predicted the existence of gravitational waves and assumed that their speed c[g] would be that of the speed of light c. If the gravitational aberration would also have the same magnitude as the aberration of light, we would observe several paradoxical phenomena. For instance, the orbit of two bodies of equal mass would be unstable, since two attractive forces arise that are not in line and hence form a couple. This tends to increase the angular momentum, period, and total energy of the system. This can be modelled by a system of ordinary differential equations with delay. A big advantage of computer simulation is that we can easily perform many test for various possible values of the speed of gravity [1]. In [2], Carlip showed that gravitational aberration in general relativity is almost cancelled out by velocity-dependent interactions. This means that rays of sunlight are not parallel to the attractive gravitational force of the Sun, i.e., we do not see the Sun in the direction of its attractive force, but slightly shifted about an angle less than 20``. We show how the actual value of the gravitational aberration can be obtained by measurement of a single angle at a suitable time instant T corresponding to the perihelion of an elliptic orbit. We also derive an a priori error estimate that expresses how acurately T has to be determined to attain the gravitational aberration to a prescribed tolerance. [1] M. Křížek: Numerical experience with the finite speed of gravitational interaction, Math. Comput. Simulation 50 (1999), 237-245. [2] S. Carlip: Aberration and the speed of gravity, Phys. Lett. A 267 (2000), 81-87.

  19. Chromosome Aberrations by Heavy Ions

    NASA Astrophysics Data System (ADS)

    Ballarini, Francesca; Ottolenghi, Andrea

    It is well known that mammalian cells exposed to ionizing radiation can show different types of chromosome aberrations (CAs) including dicentrics, translocations, rings, deletions and complex exchanges. Chromosome aberrations are a particularly relevant endpoint in radiobiology, because they play a fundamental role in the pathways leading either to cell death, or to cell conversion to malignancy. In particular, reciprocal translocations involving pairs of specific genes are strongly correlated (and probably also causally-related) with specific tumour types; a typical example is the BCR-ABL translocation for Chronic Myeloid Leukaemia. Furthermore, aberrations can be used for applications in biodosimetry and more generally as biomarkers of exposure and risk, that is the case for cancer patients monitored during Carbon-ion therapy and astronauts exposed to space radiation. Indeed hadron therapy and astronauts' exposure to space radiation represent two of the few scenarios where human beings can be exposed to heavy ions. After a brief introduction on the main general features of chromosome aberrations, in this work we will address key aspects of the current knowledge on chromosome aberration induction, both from an experimental and from a theoretical point of view. More specifically, in vitro data will be summarized and discussed, outlining important issues such as the role of interphase death/mitotic delay and that of complex-exchange scoring. Some available in vivo data on cancer patients and astronauts will be also reported, together with possible interpretation problems. Finally, two of the few available models of chromosome aberration induction by ionizing radiation (including heavy ions) will be described and compared, focusing on the different assumptions adopted by the authors and on how these models can deal with heavy ions.

  20. Acoustically-tuned optical spectrometer

    NASA Technical Reports Server (NTRS)

    Sklar, E.

    1981-01-01

    Lens arrangement corrects for aberrations and gives resolution of 0.7 seconds of arc. In spectrometer, light from telescope is relayed by doublet lens to acoustically tuned optical filter. Selected wavelengths are relayed by triplet lens to charge coupled device camera. Intervening cylindrical lens, tilted at 12 degree angle, corrects for astigmatism and coma introduced by two element birefringent crystal in filter.

  1. Extended wavelet transformation to digital holographic reconstruction: application to the elliptical, astigmatic Gaussian beams.

    PubMed

    Remacha, Clément; Coëtmellec, Sébastien; Brunel, Marc; Lebrun, Denis

    2013-02-01

    Wavelet analysis provides an efficient tool in numerous signal processing problems and has been implemented in optical processing techniques, such as in-line holography. This paper proposes an improvement of this tool for the case of an elliptical, astigmatic Gaussian (AEG) beam. We show that this mathematical operator allows reconstructing an image of a spherical particle without compression of the reconstructed image, which increases the accuracy of the 3D location of particles and of their size measurement. To validate the performance of this operator we have studied the diffraction pattern produced by a particle illuminated by an AEG beam. This study used mutual intensity propagation, and the particle is defined as a chirped Gaussian sum. The proposed technique was applied and the experimental results are presented.

  2. Advanced astigmatism-corrected Czerny-Turner imaging spectrometer in spectral broadband

    NASA Astrophysics Data System (ADS)

    Cong, Hai-fang

    2014-12-01

    This paper reports an advanced Czerny-Turner optical structure which is used for the application in imaging spectrometers. To obtain the excellent imaging quality, a cylindrical lens with a wedge angle is used between the focusing mirror and the imaging plane to remove astigmatism in broadband. It makes the advanced optical system presents high resolution over the full bandwidth and decreases the cost. An example of the imaging spectrometer in the waveband of 260nm~520nm has been designed to prove our theory. It yields the excellent modulation transfer functions (MTF) of all fields of view which are more than 0.75 over the broadband under the required Nyquist frequency (20lp/mm).

  3. Astigmatic visual and deprivation in cat: behavioral, optical and retinophysiological consequences.

    PubMed

    Thibos, L N; Levick, W R

    1982-01-01

    Kittens were deprived of clear vision in one eye only by +7D or -7D cylindrical lenses worn from eye opening until 7.5 months of age. Behavioral measurements subsequently demonstrated diminished acuity through the affected eye relative to the opposite control eye. However, single unit recordings at 3.5 years of age from retinal ganglion cells located within 1-11 degrees of the centre of the area centralis showed neither loss of grating resolution nor any abnormal orientation bias. Furthermore, the astigmatic rearing had minimal effect on the development of the cat's natural optics to the emmetropic state. The experiments indicate that the amblyopic defect induced by the cylindrical lenses occurs in the brain rather than the eye. PMID:7101750

  4. [Orthokeratology for the high myopia and high astigmatism is worth watching].

    PubMed

    Xie, Peiying

    2015-01-01

    The prevalence of high myopia in teenagers is rising. Due to both genetic factors and environmental factors, most of myopia occurs in early age with rapid progress, and the prevention and control are very difficult. Orthokeratology is considered as one of the most effective ways of controlling myopia for children. It is proved effective through many years of clinical studies not only for low to moderate myopia, but also for high myopia with astigmatism. However, professional knowledge is lacking domestically. This paper introduces the local and overseas research results in recent years, and discusses the necessity and feasibility of high diopter orthokeratology correction, implementation methods and requirements, and safety and effectiveness evaluation standards for reference.

  5. [Orthokeratology for the high myopia and high astigmatism is worth watching].

    PubMed

    Xie, Peiying

    2015-01-01

    The prevalence of high myopia in teenagers is rising. Due to both genetic factors and environmental factors, most of myopia occurs in early age with rapid progress, and the prevention and control are very difficult. Orthokeratology is considered as one of the most effective ways of controlling myopia for children. It is proved effective through many years of clinical studies not only for low to moderate myopia, but also for high myopia with astigmatism. However, professional knowledge is lacking domestically. This paper introduces the local and overseas research results in recent years, and discusses the necessity and feasibility of high diopter orthokeratology correction, implementation methods and requirements, and safety and effectiveness evaluation standards for reference. PMID:25877704

  6. Extended wavelet transformation to digital holographic reconstruction: application to the elliptical, astigmatic Gaussian beams.

    PubMed

    Remacha, Clément; Coëtmellec, Sébastien; Brunel, Marc; Lebrun, Denis

    2013-02-01

    Wavelet analysis provides an efficient tool in numerous signal processing problems and has been implemented in optical processing techniques, such as in-line holography. This paper proposes an improvement of this tool for the case of an elliptical, astigmatic Gaussian (AEG) beam. We show that this mathematical operator allows reconstructing an image of a spherical particle without compression of the reconstructed image, which increases the accuracy of the 3D location of particles and of their size measurement. To validate the performance of this operator we have studied the diffraction pattern produced by a particle illuminated by an AEG beam. This study used mutual intensity propagation, and the particle is defined as a chirped Gaussian sum. The proposed technique was applied and the experimental results are presented. PMID:23385926

  7. Effect of location of opening incision on astigmatic correction after small-incision lenticule extraction

    PubMed Central

    Chan, Tommy C. Y.; Ng, Alex LK; Cheng, George P. M.; Wang, Zheng; Woo, Victor C. P.; Jhanji, Vishal

    2016-01-01

    We compared the visual and refractive outcomes between 2 different incisional sites in small incision lenticule extraction (SMILE) for low myopic astigmatism. This was a contralateral eye study. Consecutive cases that underwent bilateral SMILE surgery were included. Procedures for both eyes were identical apart from the location of opening incision. The incision was set on the temporal side for the right eye (Group 1), while a superior incision was set for the left eye (Group 2). Twenty-nine patients with a mean age of 35.0 ± 9.6 years were included. Preoperative visual and refractive parameters were comparable between the 2 groups (p > 0.250). At 3 months, the logMAR uncorrected distance visual acuity was 0.074 ± 0.090 in Group 1 and 0.084 ± 0.130 in Group 2 (p = 0.861). No difference was found in the postoperative manifest spherical equivalent (p = 0.501) and manifest cylinder (p = 0.178) between the 2 groups. The efficacy index was 0.85 ± 0.16 in Group 1 and 0.85 ± 0.20 in Group 2 (p = 0.828). Astigmatic correction was not significantly affected by the location of opening incisions using vector analysis. Our study did not find significant differences in visual and refractive outcomes with temporal or superior opening incision during SMILE surgery. PMID:27775085

  8. [Efficiency of interlamellar refractive tunnel keratoplasty in myopia and astigmatism correction].

    PubMed

    Shusterov, Y

    2014-10-01

    Correction of high degree myopia, anisometropia and astigmatism continues to remain one of actual problems of ophthalmology. The purpose of the present work - the analysis of results of application of refractive interlamellar tunnel keratoplasty variants. We develop 6 updatings tunnel keratoplasty. In total in clinic 310 operations from which in 158 cases as a transfer material used a donor cornea, in 63 cases - brephocornea (a fruit cornea) and in 89 cases - hydrogel synthetic implant, modified in low-temperature to gas-discharge plasma are spent. From the specified number of operative interventions, on 86 eyes of operation tunnel keratoplasty have been spent at those patients by whom earlier it has been given up in carrying out eximerlaser corrections, in connection with presence of a "thin", "flat" and "convex" cornea. Maximum refractive effect fell first two weeks after operation. Definitive stabilisation of a refraction occurred on 2-3 month, thus regress of the reached effect made an order of 10-12 %. It is reached refractive effect from 5,5 to 20,0 D. Undercorrection in some cases made to 3,5 D, that spoke very high myopia (more than 20,0 D) degrees. It has been noticed, that refractive effect of operations with ecsplants was above (on the average on 10 %), than at use of a donor cornea, at identical cross-section section of used transfer materials. It spoke that the synthetic material, unlike a donor cornea, kept the form. At all patients substantial increase of visual acuities has been received, and in 75 % it was equal or exceeded visual acuity before operation with the greatest possible correction. Thus, clinical approbation has proved, that the variants of tunnel keratoplasty, are effective ways of high myopia, anisometropia and astigmatism correction. Updating in gaseous plasma is represented in the perspective way of improvement of biocompatibility of synthetic materials.

  9. Chromosome aberrations in workers exposed to arsenic.

    PubMed

    Beckman, G; Beckman, L; Nordenson, I

    1977-08-01

    The occurrence of chromosome aberrations was studied in short-term cultured lymphocytes from nine workers exposed to arsenic at the Rönnskär smeltery in northern Sweden. In the smelter workers, 87 aberrations were found in 819 mitoses. The number of aberrations varied individually from 0 to 25 aberrations per 100 cells. In a control material 13 aberrations were found in 1012 mitoses. The frequency of chromosome aberrations was significantly increased among the smelter workers, but due to the simultaneous exposure to other agents the effect of arsenic per se can not be assessed with certainty.

  10. Epidemiology and prognosis of coma in daytime television dramas

    PubMed Central

    Casarett, David; Fishman, Jessica M; MacMoran, Holly Jo; Pickard, Amy; Asch, David A

    2005-01-01

    Objective To determine how soap operas portray, and possibly misrepresent, the likelihood of recovery for patients in coma. Design Retrospective cohort study. Setting Nine soap operas in the United States reviewed between 1 January 1995 and 15 May 2005. Subjects 64 characters who experienced a period of unconsciousness lasting at least 24 hours. Their final status at the end of the follow-up period was compared with pooled data from a meta-analysis. Results Comas lasted a median of 13 days (interquartile range 7-25 days). Fifty seven (89%) patients recovered fully, five (8%) died, and two (3%) remained in a vegetative state. Mortality for non-traumatic and traumatic coma was significantly lower than would be predicted from the meta-analysis data (non-traumatic 4% v 53%; traumatic 6% v 67%; Fisher's exact test both P < 0.001). On the day that patients regained consciousness, most (49/57; 86%) had no evidence of limited function, cognitive deficit, or residual disability needing rehabilitation. Compared with meta-analysis data, patients in this sample had a much better than expected chance of returning to normal function (non-traumatic 91% v 1%; traumatic 89% v 7%; both P < 0.001). Conclusions The portrayal of coma in soap operas is overly optimistic. Although these programmes are presented as fiction, they may contribute to unrealistic expectations of recovery. PMID:16373744

  11. Coma chemical composition at the Abydos landing site

    NASA Astrophysics Data System (ADS)

    Morse, A.; Sheridan, S.; Morgan, G.; Andrews, D.; Barber, S.; Wright, I.

    2015-10-01

    The Ptolemy instrument, onboard the Rosetta Philae Lander, made measurements of the chemical composition of the coma mid-bounce, just after the non-nominal landing on the surface, and subsequently at the Abydos landing site. This presentation will discuss Ptolemy's operations throughout this 45 hour period and the results obtained.

  12. Modeling Coma Gas Jets in Comet Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Lederer, S. M.; Campins, H.

    2001-01-01

    We present an analysis of OH, CN, and C2 jets observed in Comet Hale-Bopp. The relative contributions from and composition of the coma gas sources, and the parameters describing the active areas responsible for the gas jets will be discussed. Additional information is contained in the original extended abstract.

  13. A preliminary model of the coma of 2060 Chiron

    NASA Technical Reports Server (NTRS)

    Boice, Daniel C.; Konno, I.; Stern, S. Alan; Huebner, Walter F.

    1992-01-01

    We have included gravity in our fluid dynamic model with chemical kinetics of dusty comet comae and applied it with two dust sizes to 2060 Chiron. A progress report on the model and preliminary results concerning gas/dust dynamics and chemistry is given.

  14. Color gradients in the coma of P/Halley

    NASA Technical Reports Server (NTRS)

    Meech, Karen

    1988-01-01

    Some important information relevant to the understanding of the gas/dust dynamics near the surface of a comet nucleus concerns knowledge of the grain composition and scattering properties as well as the particle size distribution of dust in the coma. Ground based measurements of light scattered from the dust comae can provide some information about the physical grain properties, in particular about the mean optically dominant grain size. Optical spectra of continua of nine comets presented by Jewitt and Meech, 1986, show that all of the scattered light is reddened with respect to the Sun. There is significant scatter in the amount of reddening seen for different comets. In the near IF regions, the reddening decreases until near 2 to 3 micrometers where the reflectivity is nearly neutral. It is of particular interest to see if there are any observable changes in the grain size distribution during outburst. Although no coma colar changes were observed during the Nov. 1985 outbursts, a color gradient within the coma has been observed in Halley. Radial color gradients in J, H, and K images of Halley as reported by Campins have not been observed by the author.

  15. Focal properties of a plane grating in a convergent beam.

    PubMed

    Hall, J T

    1966-06-01

    Focusing from a plane grating can be accomplished by using convergent radiation incident on the grating in such a manner that any incident angle alpha(n), the resulting diffraction angle beta(n), will be on the same side of the grating normal. The theory for the focal properties is developed by applying Fermat's principle of least time to selected terms resulting from a finite series expansion of the system's distance function. Derivations are given for finding the focal curve equation, astigmatism, and coma, of the most usable configuration of the optical components. Discussions of the aberrations disclose methods for eliminating the astigmatism and reducing the coma. PMID:20049009

  16. Correlation among auto-refractor, wavefront aberration, and subjective manual refraction

    NASA Astrophysics Data System (ADS)

    Li, Qi; Ren, Qiushi

    2005-01-01

    Three optometry methods which include auto-refractor, wavefront aberrometer and subjective manual refraction were studied and compared in measuring low order aberrations of 60 people"s 117 normal eyes. Paired t-test and linear regression were used to study these three methods" relationship when measuring myopia with astigmatism. In order to make the analysis more clear, we divided the 117 normal eyes into different groups according to their subjective manual refraction and redid the statistical analysis. Correlations among three methods show significant in sphere, cylinder and axis in all groups, with sphere"s correlation coefficients largest(R>0.98, P<0.01) and cylinder"s smallest (0.900.01). Auto-refractor had significant change from the other two methods when measuring cylinder (P<0.01). The results after grouping differed a little from the analysis among total people. Although three methods showed significant change from each other in certain parameters, the amplitude of these differences were not large, which indicated that the coherence of auto-refractor, wavefront aberrometer and subjective refraction is good. However, we suggested that wavefront aberration measurement could be a good starting point of optometry, subjective refraction is still necessary for refinement.

  17. Risk factors for nosocomial nontraumatic coma: sepsis and respiratory failure

    PubMed Central

    Zhou, Ye-Ting; Wang, Shao-Dan; Wang, Guang-Sheng; Chen, Xiao-Dong; Tong, Dao-Ming

    2016-01-01

    Background Coma’s are a major cause of clinical deterioration or death. Identification of risks that predispose to coma are important in managing patients; however, the risk factors for nosocomial nontraumatic coma (NNC) are not well known. Our aim was to investigate the risk factors in patients with NNC. Methods A retrospective case–control design was used to compare patients with NNC and a control group of patients without coma in a population-based cohort of 263 participants from the neurological intensive care unit in Shuyang County People’s Hospital of Northern China. Coma was diagnosed by a Glasgow Coma Scale score ≤8. Adjusted odds ratios for patients with NNC were derived from multivariate logistic regression analyses. Results A total of 96 subjects had NNC. The prevalence of NNC was 36.5% among the subjects. Among these, 82% had acute cerebrovascular etiology. Most of the NNC usually occurred at day 3 after admission to the neurological intensive care unit. Patients with NNC had higher hospital mortality rates (67.7% vs 3%, P<0.0001) and were more likely to have a central herniation (47.9% vs 0%, P<0.001) or uncal herniation (11.5% vs 0%, P<0.001) than those without NNC. Multiple logistic regression showed that systemic inflammatory response syndrome-positive sepsis (odds ratio =4, 95% confidence interval =1.875−8.567, P<0.001) and acute respiratory failure (odds ratio =3.275, 95% confidence interval =1.014−10.573, P<0.05) were the factors independently associated with a higher risk of NNC. Conclusion Systemic inflammatory response syndrome-positive sepsis and acute respiratory failure are independently associated with an increased risk of NNC. This information may be important for patients with NNC.

  18. Evaluation of the orientation of the steepest meridian of regular astigmatism among highly myopic Egyptian patients seeking non-ablative surgical correction of the refractive error

    PubMed Central

    Refai, Tamer Adel

    2015-01-01

    Introduction: LASIK surgery is currently the preferred procedure to correct low to moderate myopia. The aim of this study was to determine the orientation of the steepest meridian of regular astigmatism in order to determine the relative incidence of vertical, horizontal, and oblique regular astigmatism among highly myopic Egyptian patients seeking non-ablative surgical correction of the refractive error. Methods: One hundred and one eyes of 68 highly myopic patients who were seeking refractive surgery were included in this consecutive case series study. The refractive errors were measured using an autorefractometer and confirmed by trial. We measured the uncorrected and best corrected visual acuity in Snellen lines. Keratometry, central corneal thickness, and anterior chamber depth also were measured. The cylinder power in diopters and the axis in degrees were reported. Astigmatism was graded as with the rule (i.e., vertical meridian steeper), against the rule (i.e., horizontal meridian steeper), and oblique astigmatism. The number and the percentage of eyes with the rule, against the rule, and oblique astigmatism were calculated, and the chi-squared test was performed to analyze the data. Results: The spherical refractive error ranged from −6.5 to −24.5 diopters (−13.45 ± 4.60). The cylinder power (Cyl) ranged from −0.25 to −7.5 diopters (−2.23 ± 1.28). The uncorrected visual acuity (UCVA) in Snellen lines ranged from 0.01 – 0.1 (0.03 ± 0.02). The mean for best corrected visual acuity (BCVA) in Snellen lines was 0.40 (± 0.23). The steepest meridian was vertical (i.e., with-the-rule astigmatism) in 44 eyes (43.56%), horizontal (i.e., against-the-rule astigmatism) in 27 eyes (26.73%), and oblique (i.e., oblique astigmatism) in 30 eyes (29.70%). Conclusions: The incidence of with-the-rule astigmatism in patients with high myopia was found to be much lower than in previous studies for non-myopic patients, with a higher incidence for against

  19. Phase Aberrations in Diffraction Microscopy

    SciTech Connect

    Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M

    2005-09-29

    In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.

  20. Three-dimensional localization precision of the double-helix point spread function versus astigmatism and biplane

    NASA Astrophysics Data System (ADS)

    Badieirostami, Majid; Lew, Matthew D.; Thompson, Michael A.; Moerner, W. E.

    2010-10-01

    Wide-field microscopy with a double-helix point spread function (DH-PSF) provides three-dimensional (3D) position information beyond the optical diffraction limit. We compare the theoretical localization precision for an unbiased estimator of the DH-PSF to that for 3D localization by astigmatic and biplane imaging using Fisher information analysis including pixelation and varying levels of background. The DH-PSF results in almost constant localization precision in all three dimensions for a 2 μm thick depth of field while astigmatism and biplane improve the axial localization precision over smaller axial ranges. For high signal-to-background ratio, the DH-PSF on average achieves better localization precision.

  1. Three-dimensional localization precision of the double-helix point spread function versus astigmatism and biplane.

    PubMed

    Badieirostami, Majid; Lew, Matthew D; Thompson, Michael A; Moerner, W E

    2010-10-18

    Wide-field microscopy with a double-helix point spread function (DH-PSF) provides three-dimensional (3D) position information beyond the optical diffraction limit. We compare the theoretical localization precision for an unbiased estimator of the DH-PSF to that for 3D localization by astigmatic and biplane imaging using Fisher information analysis including pixelation and varying levels of background. The DH-PSF results in almost constant localization precision in all three dimensions for a 2 μm thick depth of field while astigmatism and biplane improve the axial localization precision over smaller axial ranges. For high signal-to-background ratio, the DH-PSF on average achieves better localization precision.

  2. Photorefractive keratectomy with mitomycin-C for the treatment of compound moderate myopia with astigmatism in buccal pemphigus vulgaris.

    PubMed

    Taheri, Seyed Mohammad Reza; Kheiltash, Azita

    2007-10-01

    We report a case of controlled buccal pemphigus vulgaris with compound moderate myopia with astigmatism that was treated with photorefractive keratectomy with mitomycin-C (PRK+MMC) in both eyes. The preoperative manifest refraction was -6.50 sphere and -5.5 -0.75 x 20 in the right eye and left eye, respectively, with a best corrected visual acuity of 10/10 in both eyes. Seven months after surgery, the uncorrected visual acuity was 10/10 in both eyes. The manifest refraction was 0.75 sphere and 0.50 -0.75 x 120 in the right eye and left eye, respectively. Haze was not detected in the follow-up examinations. Reepithelialization was complete 5 days after surgery in both eyes. The results show that PRK+MMC for compound moderate myopia with astigmatism in a patient with controlled pemphigus vulgaris may be an effective and safe treatment.

  3. Apparatus for and method of correcting for astigmatism in a light beam reflected off of a light reflecting surface

    DOEpatents

    Sawicki, Richard H.; Sweatt, William

    1987-01-01

    A technique for adjustably correcting for astigmatism in a light beam is disclosed herein. This technique utilizes first means which defines a flat, rectangular light reflecting surface having opposite reinforced side edges and which is resiliently bendable, to a limited extent, into different concave and/or convex cylindrical curvatures about a particular axis and second means acting on the first means for adjustably bending the light reflecting surface into a particular selected one of the different curvatures depending upon the astigmatism to be corrected for and for fixedly maintaining the curvature selected. In the embodiment disclosed, the light reflecting surface is adjustably bendable into the selected cylindrical curvature by application of a particular bending moment to the reinforced side edges of the light reflecting surface.

  4. Orbital angular moment of a partially coherent beam propagating through an astigmatic ABCD optical system with loss or gain.

    PubMed

    Cai, Yangjian; Zhu, Shijun

    2014-04-01

    We derive the general expression for the orbital angular momentum (OAM) flux of an astigmatic partially coherent beam carrying twist phase [i.e., twisted anisotropic Gaussian-Schell model (TAGSM) beam] propagating through an astigmatic ABCD optical system with loss or gain. The evolution properties of the OAM flux of a TAGSM beam in a Gaussian cavity or propagating through a cylindrical thin lens are illustrated numerically with the help of the derived formula. It is found that we can modulate the OAM of a partially coherent beam by varying the parameters of the cavity or the orientation angle of the cylindrical thin lens, which will be useful in some applications, such as free-space optical communications and particle trapping.

  5. Management of moderate and severe corneal astigmatism with AcrySof® toric intraocular lens implantation – Our experience

    PubMed Central

    Farooqui, Javed Hussain; Koul, Archana; Dutta, Ranjan; Shroff, Noshir Minoo

    2015-01-01

    Purpose Visual performance following toric intraocular lens implantation for cataract with moderate and severe astigmatism. Setting Cataract services, Shroff Eye Centre, New Delhi, India. Design Case series. Method This prospective study included 64 eyes of 40 patients with more than 1.50 dioptre (D) of pre-existing corneal astigmatism undergoing phacoemulsification with implantation of the AcrySof® toric IntraOcular Lens (IOL). The unaided visual acuity (UCVA), best corrected visual acuity (BCVA), residual refractive sphere and refractive cylinders were evaluated. Toric IOL axis and alignment error was measured by slit lamp method and Adobe Photoshop (version 7) method. Patient satisfaction was evaluated using a satisfaction questionnaire at 3 months. Results The mean residual refractive astigmatism was 0.57 D at the final follow-up of 3 months. Mean alignment error was 3.44 degrees (SD = 2.60) by slit lamp method and 3.88 degrees (SD = 2.86) by Photoshop method. Forty-six (71.9%) eyes showed misalignment of 5 degrees or less, and 60 (93.8%) eyes showed misalignment of 10 degrees or less. The mean log MAR UCVA at 1st post-op day was 0.172 (SD = 0.02), on 7th post-op day was 0.138 (SD = 0.11), and on 30th post-op day was 0.081 (SD = 0.11). The mean log MAR BCVA at three months was −0.04 (SD = 0.76). Conclusion We believe that implantation of AcrySof® toric IOL is an effective, safe and predictable method to correct high amounts of corneal astigmatism during cataract surgery. PMID:26586976

  6. Stability and astigmatic compensation analysis of five- and six- or seven-mirror cavities for mode-locked dye lasers

    SciTech Connect

    Cojocaru, E.; Julea, T.; Herisanu, N.

    1989-07-01

    An analysis of the stability and astigmatic compensation of five- and six- or seven-mirror cavities for mode-locked dye lasers and simple relations for the folding angle to get a maximum stability region are given in this paper. Analytical relations referring to equivalent resonators are deduced. We draw attention to the lack of opportunity to use long cavity approximation to obtain stability diagrams and made some considerations on beam waist sizes.

  7. New formulations between spherical aberration and spherical aberration coefficient using the Abbe sine condition

    NASA Astrophysics Data System (ADS)

    Kang, Songgao; Lu, Kaichang; Zhu, Yafei

    1991-12-01

    The relationship between aberration and the aberration coefficient is the basic formulation in the field of aberration theory. The Seidel's formulations can only be used in the case of low performance (small aperture and small field), so that a set of correct relations between spherical aberration (SA) and spherical aberration coefficient (SAC) must be derived for the application of large aperture and small viewing field.

  8. Disconnection of the Ascending Arousal System in Traumatic Coma

    PubMed Central

    Edlow, Brian L.; Haynes, Robin L.; Takahashi, Emi; Klein, Joshua P.; Cummings, Peter; Benner, Thomas; Greer, David M.; Greenberg, Steven M.; Wu, Ona; Kinney, Hannah C.; Folkerth, Rebecca D.

    2013-01-01

    Traumatic coma is associated with disruption of axonal pathways throughout the brain but the specific pathways involved in humans are incompletely understood. In this study, we used high angular resolution diffusion imaging (HARDI) to map the connectivity of axonal pathways that mediate the 2 critical components of consciousness – arousal and awareness – in the postmortem brain of a 62-year-old woman with acute traumatic coma and in 2 control brains. HARDI tractography guided tissue sampling in the neuropathological analysis. HARDI tractography demonstrated complete disruption of white matter pathways connecting brainstem arousal nuclei to the basal forebrain and thalamic intralaminar and reticular nuclei. In contrast, hemispheric arousal pathways connecting the thalamus and basal forebrain to the cerebral cortex were only partially disrupted, as were the cortical “awareness pathways.” Neuropathologic examination, which utilized β-amyloid precursor protein and fractin immunomarkers, revealed axonal injury in the white matter of the brainstem and cerebral hemispheres that corresponded to sites of HARDI tract disruption. Axonal injury was also present within the grey matter of the hypothalamus, thalamus, basal forebrain, and cerebral cortex. We propose that traumatic coma may be a subcortical disconnection syndrome related to the disconnection of specific brainstem arousal nuclei from the thalamus and basal forebrain. PMID:23656993

  9. Radical formation in the coma from photodissociation of ice grains

    NASA Technical Reports Server (NTRS)

    Jackson, William M.; Gerth, Christopher

    1990-01-01

    Long ago visual observations of comets suggested that there are jets in comets but it has only been recently that A'Hearn et al. have proven that some of these jets are due to emission from the CN radical. Recent studies in the lab have shown that CN radicals can be ejected directly into the gas phase from the photolysis of frozen vapors if the parent molecular has been excited to repulsive excited state. This later observation suggests that the jets that have been observed may be due to photodissociation of icy grains in the coma. A theory of radical formation from icy grains is presented. It is shown that direct formation of free radicals in the coma is an effective way to produce radicals from icy grains in the coma. The model predicts that icy grains could produce from 6 to 800,000 OH radicals/s per grain depending upon whether the radius of the grain is 0.3 to 100 micron.

  10. Truncation of the krebs cycle during hypoglycemic coma.

    PubMed

    Sutherland, Garnette R; Tyson, Randy L; Auer, Roland N

    2008-07-01

    There is a misconception that hypoglycemic nerve cell death occurs easily, and can happen in the absence of coma. In fact, coma is the prerequisite for neuronal death, which occurs via metabolic excitatory amino acid release. The focus on nerve cell death does not explain how most brain neurons and all glia survive. Brain metabolism was interrogated in rats during and following recovery from 40 min of profound hypoglycemia using ex vivo (1)H MR spectroscopy to determine alterations accounting for survival of brain tissue. As previously shown, a time-dependent increase in aspartate was equaled by a reciprocal decrease in glutamate/glutamine. We here show that the kinetics of aspartate formation during the first 30 min (0.36 +/- 0.03 micromol g(-1) min(-1)) are altered such that glutamate, via aspartate aminotransferase, becomes the primary source of carbon when glucose-derived pyruvate is unavailable. Oxaloacetate is produced directly from alpha-ketoglutarate, so that reactions involving the six-carbon intermediates of the tricarboxylic acid cycle are bypassed. These fundamental observations in basic metabolic pathways in effect redraw the tricarboxylic acid cycle from a tricarboxylic to a dicarboxylic acid cycle during hypoglycemia. The basic neurochemical alterations according to the chemical equilibrium of mass action augments flux through a truncated Krebs cycle that continues to turn during hypoglycemic coma. This explains the partial preservation of energy charge and brain cell survival during periods of glucose deficiency.

  11. Non-astigmatic imaging with matched pairs of spherically bent reflectors

    DOEpatents

    Bitter, Manfred Ludwig; Hill, Kenneth Wayne; Scott, Steven Douglas; Feder, Russell; Ko, Jinseok; Rice, John E.; Ince-Cushman, Alexander Charles; Jones, Frank

    2012-07-10

    Arrangements for the point-to-point imaging of a broad spectrum of electromagnetic radiation and ultrasound at large angles of incidence employ matched pairs of spherically bent reflectors to eliminate astigmatic imaging errors. Matched pairs of spherically bent crystals or spherically bent multi-layers are used for X-rays and EUV radiation; and matched pairs of spherically bent mirrors that are appropriate for the type of radiation are used with microwaves, infrared and visible light, or ultrasound. The arrangements encompass the two cases, where the Bragg angle--the complement to the angle of incidence in optics--is between 45.degree. and 90.degree. on both crystals/mirrors or between 0.degree. and 45.degree. on the first crystal/mirror and between 45.degree. and 90.degree. on the second crystal/mirror, where the angles of convergence and divergence are equal. For x-rays and EUV radiation, also the Bragg condition is satisfied on both spherically bent crystals/multi-layers.

  12. Inspection focus technology of space tridimensional mapping camera based on astigmatic method

    NASA Astrophysics Data System (ADS)

    Wang, Zhi; Zhang, Liping

    2010-10-01

    The CCD plane of the space tridimensional mapping camera will be deviated from the focal plane(including the CCD plane deviated due to camera focal length changed), under the condition of space environment and vibration, impact when satellite is launching, image resolution ratio will be descended because defocusing. For tridimensional mapping camera, principal point position and focal length variation of the camera affect positioning accuracy of ground target, conventional solution is under the condition of vacuum and focusing range, calibrate the position of CCD plane with code of photoelectric encoder, when the camera defocusing in orbit, the magnitude and direction of defocusing amount are obtained by photoelectric encoder, then the focusing mechanism driven by step motor to compensate defocusing amount of the CCD plane. For tridimensional mapping camera, under the condition of space environment and vibration, impact when satellite is launching, if the camera focal length changes, above focusing method has been meaningless. Thus, the measuring and focusing method was put forward based on astigmation, a quadrant detector was adopted to measure the astigmation caused by the deviation of the CCD plane, refer to calibrated relation between the CCD plane poison and the asrigmation, the deviation vector of the CCD plane can be obtained. This method includes all factors caused deviation of the CCD plane, experimental results show that the focusing resolution of mapping camera focusing mechanism based on astigmatic method can reach 0.25 μm.

  13. Advanced astigmatism-corrected tandem Wadsworth mounting for small-scale spectral broadband imaging spectrometer.

    PubMed

    Lei, Yu; Lin, Guan-yu

    2013-01-01

    Tandem gratings of double-dispersion mount make it possible to design an imaging spectrometer for the weak light observation with high spatial resolution, high spectral resolution, and high optical transmission efficiency. The traditional tandem Wadsworth mounting is originally designed to match the coaxial telescope and large-scale imaging spectrometer. When it is used to connect the off-axis telescope such as off-axis parabolic mirror, it presents lower imaging quality than to connect the coaxial telescope. It may also introduce interference among the detector and the optical elements as it is applied to the short focal length and small-scale spectrometer in a close volume by satellite. An advanced tandem Wadsworth mounting has been investigated to deal with the situation. The Wadsworth astigmatism-corrected mounting condition for which is expressed as the distance between the second concave grating and the imaging plane is calculated. Then the optimum arrangement for the first plane grating and the second concave grating, which make the anterior Wadsworth condition fulfilling each wavelength, is analyzed by the geometric and first order differential calculation. These two arrangements comprise the advanced Wadsworth mounting condition. The spectral resolution has also been calculated by these conditions. An example designed by the optimum theory proves that the advanced tandem Wadsworth mounting performs excellently in spectral broadband. PMID:23292378

  14. Mild myopic astigmatism corrected by accidental flap complication: a case report.

    PubMed

    Fahed, Daoud C; Fahed, Charbel D

    2009-10-01

    A 35-year-old female presented for laser in-situ keratomileusis (LASIK). Her preoperative eye exam was normal, with a preop refraction of OD -2.50 D Sph +1.25 D Cyl x175 and OS -2.75 D Sph +1.50 D Cyl x165 (cycloplegic and manifest), with 20/20 BCVA OU. The central pachymetry reading was 553 mum in the right eye. Preoperative topography was normal. At the start of the pendular microkeratome path, some resistance was felt, but the microkeratome continued along its path. Upon inspection of the flap, there was a central rectangle of intact epithelium with two mirror-image flaps on both sides. The flap was repositioned and LASIK was discontinued. The cornea healed with two faint thin linear vertical parallel scars at the edge of the pupil. Postoperative inspection of the blade revealed central blunting. One month postoperatively, the uncorrected visual acuity (UCVA) was 20/20. Manifest and cycloplegic refractions were plano. This is an interesting case of accidental flap complication resulting in the correction of mild myopic astigmatism.

  15. THE HST/ACS COMA CLUSTER SURVEY. VIII. BARRED DISK GALAXIES IN THE CORE OF THE COMA CLUSTER

    SciTech Connect

    Marinova, Irina; Jogee, Shardha; Weinzirl, Tim; Erwin, Peter; Trentham, Neil; Ferguson, Henry C.; Goudfrooij, Paul; Hammer, Derek; Den Brok, Mark; Peletier, Reynier F.; Kleijn, Gijs V.; Graham, Alister W.; Carter, David; Mouhcine, Mustapha; Balcells, Marc; Guzman, Rafael; Hoyos, Carlos; Mobasher, Bahram; Peng, Eric W. E-mail: sj@astro.as.utexas.edu

    2012-02-20

    We use high-resolution ({approx}0.''1) F814W Advanced Camera for Surveys (ACS) images from the Hubble Space Telescope ACS Treasury survey of the Coma cluster at z {approx} 0.02 to study bars in massive disk galaxies (S0s), as well as low-mass dwarf galaxies in the core of the Coma cluster, the densest environment in the nearby universe. Our study helps to constrain the evolution of bars and disks in dense environments and provides a comparison point for studies in lower density environments and at higher redshifts. Our results are: (1) we characterize the fraction and properties of bars in a sample of 32 bright (M{sub V} {approx}< -18, M{sub *} > 10{sup 9.5} M{sub Sun }) S0 galaxies, which dominate the population of massive disk galaxies in the Coma core. We find that the measurement of a bar fraction among S0 galaxies must be handled with special care due to the difficulty in separating unbarred S0s from ellipticals, and the potential dilution of the bar signature by light from a relatively large, bright bulge. The results depend sensitively on the method used: the bar fraction for bright S0s in the Coma core is 50% {+-} 11%, 65% {+-} 11%, and 60% {+-} 11% based on three methods of bar detection, namely, strict ellipse fit criteria, relaxed ellipse fit criteria, and visual classification. (2) We compare the S0 bar fraction across different environments (the Coma core, A901/902, and Virgo) adopting the critical step of using matched samples and matched methods in order to ensure robust comparisons. We find that the bar fraction among bright S0 galaxies does not show a statistically significant variation (within the error bars of {+-}11%) across environments which span two orders of magnitude in galaxy number density (n {approx} 300-10,000 galaxies Mpc{sup -3}) and include rich and poor clusters, such as the core of Coma, the A901/902 cluster, and Virgo. We speculate that the bar fraction among S0s is not significantly enhanced in rich clusters compared to low

  16. Determination of aberration center of Ronchigram for automated aberration correctors in scanning transmission electron microscopy.

    PubMed

    Sannomiya, Takumi; Sawada, Hidetaka; Nakamichi, Tomohiro; Hosokawa, Fumio; Nakamura, Yoshio; Tanishiro, Yasumasa; Takayanagi, Kunio

    2013-12-01

    A generic method to determine the aberration center is established, which can be utilized for aberration calculation and axis alignment for aberration corrected electron microscopes. In this method, decentering induced secondary aberrations from inherent primary aberrations are minimized to find the appropriate axis center. The fitness function to find the optimal decentering vector for the axis was defined as a sum of decentering induced secondary aberrations with properly distributed weight values according to the aberration order. Since the appropriate decentering vector is determined from the aberration values calculated at an arbitrary center axis, only one aberration measurement is in principle required to find the center, resulting in /very fast center search. This approach was tested for the Ronchigram based aberration calculation method for aberration corrected scanning transmission electron microscopy. Both in simulation and in experiments, the center search was confirmed to work well although the convergence to find the best axis becomes slower with larger primary aberrations. Such aberration center determination is expected to fully automatize the aberration correction procedures, which used to require pre-alignment of experienced users. This approach is also applicable to automated aperture positioning.

  17. Unique reflector arrangement within very wide field of view for multibeam antennas

    NASA Astrophysics Data System (ADS)

    Dragone, C.

    1983-12-01

    It is pointed out that Cassegrainian and Gregorian reflector arrangements are needed for multibeam ground station and satellite antennas. A Cassegrainian arrangement is considered, taking into account aberrations. Dragone (1982) has presented a requirement for the minimization of astigmatism. In the present investigation a formula is presented for describing the deformation coefficients needed to eliminate coma on the basis of a slight deformation of the reflectors. The importance of residual astigmatism due to a derived equation is examined, and attention is given to a compact reflector arrangement which is the result of three optimizations with respect to aberration minimization.

  18. Chromosome aberrations induced by zebularine in triticale.

    PubMed

    Ma, Xuhui; Wang, Qing; Wang, Yanzhi; Ma, Jieyun; Wu, Nan; Ni, Shuang; Luo, Tengxiao; Zhuang, Lifang; Chu, Chenggen; Cho, Seong-Woo; Tsujimoto, Hisashi; Qi, Zengjun

    2016-07-01

    Chromosome engineering is an important approach for generating wheat germplasm. Efficient development of chromosome aberrations will facilitate the introgression and application of alien genes in wheat. In this study, zebularine, a DNA methylation transferase inhibitor, was successfully used to induce chromosome aberrations in the octoploid triticale cultivar Jinghui#1. Dry seeds were soaked in zebularine solutions (250, 500, and 750 μmol/L) for 24 h, and the 500 μmol/L treatment was tested in three additional treatment times, i.e., 12, 36, and 48 h. All treatments induced aberrations involving wheat and rye chromosomes. Of the 920 cells observed in 67 M1 plants, 340 (37.0%) carried 817 aberrations with an average of 0.89 aberrations per cell (range: 0-12). The aberrations included probable deletions, telosomes and acentric fragments (49.0%), large segmental translocations (28.9%), small segmental translocations (17.1%), intercalary translocations (2.6%), long chromosomes that could carry more than one centromere (2.0%), and ring chromosomes (0.5%). Of 510 M2 plants analyzed, 110 (21.6%) were found to carry stable aberrations. Such aberrations included 79 with varied rye chromosome numbers, 7 with wheat and rye chromosome translocations, 15 with possible rye telosomes/deletions, and 9 with complex aberrations involving variation in rye chromosome number and wheat-rye translocations. These indicated that aberrations induced by zebularine can be steadily transmitted, suggesting that zebularine is a new efficient agent for chromosome manipulation. PMID:27334255

  19. A Rare Case of Myxedema Coma with Neuroleptic Malignant Syndrome (NMS)

    PubMed Central

    Dutta, Manoj Kumar; Namdeo, Mayank

    2015-01-01

    Myxedema coma or hypothyroid crisis is an endocrine emergency and needs ICU management. Neuroleptic malignant syndrome (NMS) is another medical emergency which needs high degree of clinical suspicion else mortality can be high. There is a paradox in co existence of myxedema coma and NMS. While one is hypometabolic state another is hypermetabolic state and both can be precipitated by antipsychotics use. Hypothermia and flaccidity commonly expected in myxedema coma may mask fever and rigidity of classical NMS contributing to diagnostic problem and treatment delay. Scientific literature on coexistance of myxedema coma and NMS is sparse. We hereby report first case with coexisting myxedema coma and NMS in a patient of schizophrenia treated with antipsychotic, where classical symptoms of NMS were masked by myxedema coma. Prompt diagnosis and effective management by a team resulted in favourable outcome in our patient. This case is reported to alert intensive care physicians to atypical manifestations of NMS in presence of hypothyroidism. PMID:26155541

  20. A Rare Case of Myxedema Coma with Neuroleptic Malignant Syndrome (NMS).

    PubMed

    Dixit, Siddharth; Dutta, Manoj Kumar; Namdeo, Mayank

    2015-05-01

    Myxedema coma or hypothyroid crisis is an endocrine emergency and needs ICU management. Neuroleptic malignant syndrome (NMS) is another medical emergency which needs high degree of clinical suspicion else mortality can be high. There is a paradox in co existence of myxedema coma and NMS. While one is hypometabolic state another is hypermetabolic state and both can be precipitated by antipsychotics use. Hypothermia and flaccidity commonly expected in myxedema coma may mask fever and rigidity of classical NMS contributing to diagnostic problem and treatment delay. Scientific literature on coexistance of myxedema coma and NMS is sparse. We hereby report first case with coexisting myxedema coma and NMS in a patient of schizophrenia treated with antipsychotic, where classical symptoms of NMS were masked by myxedema coma. Prompt diagnosis and effective management by a team resulted in favourable outcome in our patient. This case is reported to alert intensive care physicians to atypical manifestations of NMS in presence of hypothyroidism.

  1. The coma cluster after lunch: Has a galaxcy group passed through the cluster core?

    NASA Technical Reports Server (NTRS)

    Burns, Jack O.; Roettiger, Kurt; Ledlow, Michael; Klypin, Anatoly

    1994-01-01

    We propose that the Coma cluster has recently undergone a collision with the NGC 4839 galaxy group. The ROSAT X-ray morphology, the Coma radio halo, the presence of poststarburst galaxies in the bridge between Coma and NGC 4839, the usually high velocity dispersion for the NGC 4839 group, and the position of a large-scale galaxy filament to the NE of Coma are all used to argue that the NGC 4839 group passed through the core of Coma approximately 2 Gyr ago. We present a new Hydro/N-body simulation of the merger between a galaxy group and a rich cluster that reproduces many of the observed X-ray and optical properties of Coma/NGC 4839.

  2. The coma cluster after lunch: Has a galaxcy group passed through the cluster core?

    NASA Astrophysics Data System (ADS)

    Burns, Jack O.; Roettiger, Kurt; Ledlow, Michael; Klypin, Anatoly

    1994-06-01

    We propose that the Coma cluster has recently undergone a collision with the NGC 4839 galaxy group. The ROSAT X-ray morphology, the Coma radio halo, the presence of poststarburst galaxies in the bridge between Coma and NGC 4839, the usually high velocity dispersion for the NGC 4839 group, and the position of a large-scale galaxy filament to the NE of Coma are all used to argue that the NGC 4839 group passed through the core of Coma approximately 2 Gyr ago. We present a new Hydro/N-body simulation of the merger between a galaxy group and a rich cluster that reproduces many of the observed X-ray and optical properties of Coma/NGC 4839.

  3. A Rare Case of Myxedema Coma with Neuroleptic Malignant Syndrome (NMS).

    PubMed

    Dixit, Siddharth; Dutta, Manoj Kumar; Namdeo, Mayank

    2015-05-01

    Myxedema coma or hypothyroid crisis is an endocrine emergency and needs ICU management. Neuroleptic malignant syndrome (NMS) is another medical emergency which needs high degree of clinical suspicion else mortality can be high. There is a paradox in co existence of myxedema coma and NMS. While one is hypometabolic state another is hypermetabolic state and both can be precipitated by antipsychotics use. Hypothermia and flaccidity commonly expected in myxedema coma may mask fever and rigidity of classical NMS contributing to diagnostic problem and treatment delay. Scientific literature on coexistance of myxedema coma and NMS is sparse. We hereby report first case with coexisting myxedema coma and NMS in a patient of schizophrenia treated with antipsychotic, where classical symptoms of NMS were masked by myxedema coma. Prompt diagnosis and effective management by a team resulted in favourable outcome in our patient. This case is reported to alert intensive care physicians to atypical manifestations of NMS in presence of hypothyroidism. PMID:26155541

  4. Comparison of Toric Foldable Iris-Fixated Phakic Intraocular Lens Implantation and Limbal Relaxing Incisions for Moderate-to-High Myopic Astigmatism

    PubMed Central

    Lee, Jeihoon; Lee, Hun; Kang, David Sung Yong; Choi, Jin Young; Kim, Eung Kweon

    2016-01-01

    Purpose To compare the effectiveness of toric foldable iris-fixated phakic intraocular lens (pIOL) implantation and non-toric foldable iris-fixated pIOL implantation with limbal relaxing incisions (LRIs) for correcting moderate-to-high astigmatism in myopic eyes. Materials and Methods The medical records of 146 patients (195 eyes) with myopic astigmatism who underwent toric foldable iris-fixated pIOL implantation (toric group; 94 eyes) or non-toric foldable iris-fixated pIOL implantation with concurrent LRIs (LRI group; 101 eyes) were retrospectively reviewed. For subgroup analysis, the two groups were subdivided according to preoperative astigmatic severity [moderate, 2.00 to <3.00 diopters (D); high, 3.00–4.00 D]. Visual and astigmatic outcomes were compared 6 months postoperatively. Results The uncorrected distance visual acuity was at least 20/25 in 100% and 98% of the toric and LRI group eyes, respectively. The toric group had lower mean residual cylindrical error (-0.67±0.39 D vs. -1.14±0.56 D; p<0.001) and greater mean cylindrical error change (2.17±0.56 D vs. 1.63±0.72 D; p<0.001) than the LRI group, regardless of the preoperative astigmatic severity. The mean correction index (1.10±0.16 vs. 0.72±0.24; p<0.001) and success index (0.24±0.14 vs. 0.42±0.21; p<0.001) also differed significantly between the groups. Conclusion Both surgical techniques considerably reduced astigmatism and had comparable visual outcomes. However, toric foldable iris-fixated pIOL implantation was more reliable for correcting moderate-to-high astigmatism in myopic eyes. PMID:27593877

  5. Phase and birefringence aberration correction

    DOEpatents

    Bowers, Mark; Hankla, Allen

    1996-01-01

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90.degree. such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system.

  6. Phase and birefringence aberration correction

    DOEpatents

    Bowers, M.; Hankla, A.

    1996-07-09

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90{degree} such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system. 5 figs.

  7. Aberrations of ellipsoidal reflectors for unit magnification.

    PubMed

    Mielenz, K D

    1974-12-01

    Ellipsoidal reflectors are useful for the 1:1 imaging of small objects without spherical and chromatic aberration. The magnitude of the off-axis aberrations of such reflectors is computed by application of Fermat's principle to the Hamiltonian point characteristic. The limiting form of the mirror aperture for which these aberrations do not exceed a set tolerance is an ellipse whose semiaxes depend on object size and angle of incidence. PMID:20134811

  8. Effect of Corneal Incision Enlargement on Surgically Induced Astigmatism in Biaxial Microincision Cataract Surgery

    PubMed Central

    Tetikoğlu, Mehmet; Yeter, Celal; Helvacıoğlu, Fırat; Aktaş, Serdar; Sağdık, Hacı Murat; Özcura, Fatih

    2016-01-01

    Objectives: To evaluate surgically induced astigmatism (SIA) in biaxial microincision cataract surgery with enlargement of one corneal incision during intraocular lens implantation (IOL). Materials and Methods: Data from 683 eyes with cataract that underwent biaxial microincision cataract surgery and IOL were retrospectively analyzed. The operated eyes were divided into 4 groups defined by final corneal incision length after IOL implantation. There were 83 eyes with 1.6 mm corneal incisions (group 1) and 200 eyes in each of the 2, 2.4, and 2.8 mm corneal incision groups (groups 2, 3 and 4, respectively). SIA was assessed using preoperative and postoperative keratometric values at one month. Results: The mean magnitude of SIA was 0.83±0.4 D in group 1, 0.93±0.5 D in group 2, 1.03±0.6 D in group 3 and 1.04±0.7 D in group 4. The SIA showed statistically significant differences between the four groups (p=0.05). Pairwise group comparisons revealed significant differences between groups 1 and 3 and groups 1 and 4 (p=0.005). Conclusion: Biaxial microincision cataract surgery with an incision size of 1.6 mm resulted in the least SIA. Enlargement of the corneal incision beyond 2.0 mm during IOL implantation led to significant increases in SIA. We believe that with the development and dissemination of IOLs which can be inserted through small corneal incisions, biaxial microincision cataract surgery will be the best choice to prevent SIA and increase visual acuity. PMID:27800270

  9. Formation of C3 and C2 in Cometary Comae

    NASA Astrophysics Data System (ADS)

    Hölscher, Alexander

    2015-03-01

    Comets are remnants from the Solar System formation. They reside at large distances from the Sun and are believed to store deep freeze imprints of the chemical and physical conditions at the time the Solar System formed. The main ice component of a comet is H2O followed by CO and CO2 with additional small amounts of molecules with varying complexity. Comets also contain large amounts of dust. If a comet approaches the Sun the ices begin to sublimate giving rise to the cometary coma. The molecules producing the coma can be observed in the infrared, the radio wavelength range and at optical wavelengths. To constrain the formation of the Solar System, models require knowledge of the composition for a statistically significant number of comets. This favors optical observations of e.g. C3 (tricarbon) and C2 (dicarbon) since these species allow observations even of relatively faint comets and do not require space missions (infrared observations). However, one has to link these observed photodissociation product species (daughter species) to the molecules that originally sublimated from the comet nucleus surface, i.e. the so-called parent molecules, as e.g. C2H2 (acetylene) for C2. However, for C3 no parent molecules have been identified so far. This thesis investigates the formation of C3 and C2 radicals in cometary comae due to photodissociation of observed and in the literature proposed hydrocarbon parent molecules. For this purpose a one-dimensional multi-fluid coma chemistry model has been improved and applied. This work added new photo reactions to the model, updated the hydrocarbon photo rate coefficients and quantified their uncertainty. A sensitivity analysis has been carried out to determine the reactions whose uncertainty most affect the model output uncertainty. Special attention should be paid to these so-called key reactions in future laboratory experiments and quantum chemical computations to reduce the model output uncertainty more effectively. This will

  10. Analysis of CCD images of the coma of comet P/Halley

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.

    1992-01-01

    The modeling analysis objective of this project is to make use of the skill acquired in the development of Monte Carlo particle trajectory models for the distributions of gas species in cometary comae as a basis for a new dust coma model. This model will include a self-consistent picture of the time-dependent dusty-gas dynamics of the inner coma and the three-dimensional time-dependent trajectories of the dust particles under the influence of solar gravity and solar radiation pressure in the outer coma. Our purpose is to use this model as a tool to analyze selected images from two sets of data of the comet P/Halley with the hope that we can help to understand the effects of a number of important processes on the spatial morphology of the observed dust coma. The study will proceed much in the same way as our study of the spatially extended hydrogen coma where we were able to understand the spatial morphology of the Lyman-alpha coma in terms of the partial thermalization of the hot H atoms produced by the photodissociation of cometary H2O and OH. The processes of importance to the observed dust coma include: (1) the dust particle size distribution function; (2) the terminal velocities of various sized dust particles in the inner coma; (3) the radiation scattering properties of dust particles, which are important both in terms of the observed scattered radiation and the radiation pressure acceleration on dust particles; (4) the fragmentation and/or vaporization of dust particles; (5) the relative importance of CHON and silicate dust particles as they contribute both to the dusty-gas dynamics in the inner coma (that produce the dust particle terminal velocities) and to the observed spatial morphology of the outer dust coma; and (6) the time and direction dependence of the source of dust.

  11. An analysis of CCD images of the coma of Comet Halley

    NASA Technical Reports Server (NTRS)

    Combi, Michael

    1990-01-01

    The analysis of selected CCD images of the coma of comet P/Halley is presented. The images were taken using specially designed filters that isolate regions of a comet's spectrum such that only sunlight which has been scattered by the dust in the coma is recorded. The modeling analysis objective is to make use of the skills developed in the development of Monte Carlo particle trajectory models for the distributions of gas species in cometary comae and to use those models as a basis for a new dust coma model. This model will include a self-consistant picture of the time-dependent dusty-gas dynamics of the inner coma and the three-dimensional time-dependent trajectories of the dust particles under the influence of solar gravity and solar radiation pressure in the outer coma. The model is intended to be used as a tool to analyze selected images from the two sets of CCD images with the hope that it will help the understanding of the effects of a number of important processes on the spatial morphology of the observed dust coma. The processes of importance to the observed dust coma include: (1) the dust particle size distribution function; (2) the terminal velocities of various sized dust particles in the inner coma; (3) the radiation scattering properties of dust particles, which are important both in terms of the observe scattered radiation and the radiation pressure acceleration on dust particles; (4) the fragmentation and/or vaporization of dust particles; and (5) the relative importance of CHON and silicate dust particles as they contribute both to the dusty-gasdynamics in the inner coma (that produce the dust particle terminal velocities) and to the observed spatial morphology on the outer dust coma.

  12. Hyperammonemia and coma without hepatic dysfunction induced by valproate therapy.

    PubMed

    Barrueto, F; Hack, J B

    2001-10-01

    The authors report a case of a 41-year-old mentally disabled man with bipolar disorder who presented to the emergency department with altered mental status. He was found to have a significantly elevated ammonia level (377 microM/L) with no signs of hepatic insufficiency. His coma and hyperammonemia were attributed to his chronic valproate therapy. This patient had the highest serum ammonia level ever reported with a therapeutic valproate level in the absence of any other anticonvulsant therapy, metabolic abnormality, or hepatic dysfunction. The authors discuss this case and review the current literature on hyperammonemia in valproic acid therapy and the use of L-carnitine in these patients.

  13. Infrared imaging of the coma of Comet Wilson

    SciTech Connect

    Campins, H.; Lien, D.J.; Decher, R.; Telesco, C.M.; Clifton, K.S.; Kansas State Univ., Manhattan; NASA, Marshall Space Flight Center, Huntsville, AL )

    1989-08-01

    The brightness of the nuclear condensation noted in March 13-15, 1987 thermal IR images of Comet Wilson did not vary, in contrast to Comet Halley's behavior; a dynamical analysis of the dust coma/tail structure establishes that the particle size distribution in this comet, while different from that of Comet Giacobini-Zinner, is nevertheless more similar to that in Comet Halley. The nonisotropic character of the dust ejection is taken to be evidence for prograde rotation of the nucleus, and it is speculated that Comet Wilson is too young to have developed a dust mantle; this would account for the lack of short time scale variability. 25 refs.

  14. The kinetics and dynamics of the coma of Halley's comet

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.

    1994-01-01

    This grant to the University of Michigan supported the efforts of Michael R. Combi to serve as a co-investigator in collaboration with a larger effort by the principal investigator, William Smyth of Atmospheric and Environmental Research, Inc. The overall objective of this project was to analyze in a self-consistent manner unique optical O((sup 1)D) and NH2 ultra-high resolution line profile data of excellent quality and other supporting lower-resolution spectral data for the coma of comet P/Halley by using highly developed and physically-based cometary coma models in order to determine and explain in terms of physical processes the actual dynamics and photochemical kinetics that occur in the coma. The justification for this work is that it provides a valuable and underlying physical base from which to interpret significantly different types of coma observations in a self-consistent manner and hence bring into agreement (or avoid) apparent inconsistencies that arise from non-physically based interpretations. The level of effort for the Michigan component amounted to less than three person-months over a planned period of three years. The period had been extended at no extra cost to four years because the Michigan grant and the AER contract did not have coincident time periods. An effort of somewhat larger scope was undertaken by the PI. The importance of the O((sup 1)D) profiles is that they provide a direct trace of the water distribution in comets. The line profile shape is produced by the convolution of the outflow velocity and thermal dispersion of the parent water molecules with the photokinetic ejection of the oxygen atoms upon photodissociation of the parent water molecules. Our understanding of the NH2 and its precursor ammonia are important for comet-to-comet composition variations as they relate to the cosmo-chemistry of the early solar nebula. Modeling of the distribution of NH2 is necessary in order to infer the ammonia production rates from NH2

  15. Coma dust scattering concepts applied to the Rosetta mission

    NASA Astrophysics Data System (ADS)

    Fink, Uwe; Rinaldi, Giovanna

    2015-09-01

    This paper describes basic concepts, as well as providing a framework, for the interpretation of the light scattered by the dust in a cometary coma as observed by instruments on a spacecraft such as Rosetta. It is shown that the expected optical depths are small enough that single scattering can be applied. Each of the quantities that contribute to the scattered intensity is discussed in detail. Using optical constants of the likely coma dust constituents, olivine, pyroxene and carbon, the scattering properties of the dust are calculated. For the resulting observable scattering intensities several particle size distributions are considered, a simple power law, power laws with a small particle cut off and a log-normal distributions with various parameters. Within the context of a simple outflow model, the standard definition of Afρ for a circular observing aperture is expanded to an equivalent Afρ for an annulus and specific line-of-sight observation. The resulting equivalence between the observed intensity and Afρ is used to predict observable intensities for 67P/Churyumov-Gerasimenko at the spacecraft encounter near 3.3 AU and near perihelion at 1.3 AU. This is done by normalizing particle production rates of various size distributions to agree with observed ground based Afρ values. Various geometries for the column densities in a cometary coma are considered. The calculations for a simple outflow model are compared with more elaborate Direct Simulation Monte Carlo Calculation (DSMC) models to define the limits of applicability of the simpler analytical approach. Thus our analytical approach can be applied to the majority of the Rosetta coma observations, particularly beyond several nuclear radii where the dust is no longer in a collisional environment, without recourse to computer intensive DSMC calculations for specific cases. In addition to a spherically symmetric 1-dimensional approach we investigate column densities for the 2-dimensional DSMC model on the

  16. Automated surface photometry for the Coma Cluster galaxies: The catalog

    NASA Technical Reports Server (NTRS)

    Doi, M.; Fukugita, M.; Okamura, S.; Tarusawa, K.

    1995-01-01

    A homogeneous photometry catalog is presented for 450 galaxies with B(sub 25.5) less than or equal to 16 mag located in the 9.8 deg x 9.8 deg region centered on the Coma Cluster. The catalog is based on photographic photometry using an automated surface photometry software for data reduction applied to B-band Schmidt plates. The catalog provides accurate positions, isophotal and total magnitudes, major and minor axes, and a few other photometric parameters including rudimentary morphology (early of late type).

  17. Evolution of near UV Halley's spectrum in the inner coma

    NASA Technical Reports Server (NTRS)

    Rousselot, Phillippe; Clairemidi, Jacques; Vernotte, F.; Moreels, Guy

    1992-01-01

    A direct way to observe the photodissociation of water vapor in a cometary coma is to detect the OH prompt emission. This emission is shifted of delta lambda = 4 nm with respect to the OH 309 nm fluorescence band. The extended data set obtained with the three-channel spectrometer on-board Vega 2 reveals at short distance of the nucleus (i.e., less than 600 km) an excess of emission on the right wing of the OH band which may be interpreted as being mainly due to prompt emission.

  18. Correction of Spherical Aberration in Grazing-Incidence X-ray Optics by Combination of Spherical-Concave Mirrors

    SciTech Connect

    Suzuki, Y.; Takeuchi, A.

    2011-09-09

    In grazing-incidence total-reflection mirror optics for x-rays, spherical aberrations and coma are the most serious aberrations for microfocusing and microimaging. High-resolution imaging is believed to be possible only when an aspherical mirror system is used. However, the spherical aberrations of a spherical-concave mirror in a grazing-incidence condition can be eliminated by sequential reflection of spherical mirrors of similar shapes. A sub-micrometer one-dimensional focusing is easily achieved by the spherical-aberration-corrected tandem-spherical mirror optics. By configuring four spherical mirrors in an analogy of the crossed mirror optics (Kirkpatrick-Baez optics), it is possible to achieve sub-micrometer focused beam size in the hard x-ray region. Preliminary experiments on x-ray microfocusing have been carried out at beamline 20XU of SPring-8, and a 0.5 {mu}mx0.4 {mu}m beam size was achieved at 8 keV.

  19. Effect of Single Administration of Coffee on Pupil Size and Ocular Wavefront Aberration Measurements in Healthy Subjects.

    PubMed

    Bardak, Handan; Gunay, Murat; Mumcu, Ugur; Bardak, Yavuz

    2016-01-01

    No study has so far evaluated the impact of coffee drinking on ocular wavefront aberration (OWA) measurements. This study presents novel findings regarding the OWA of the eye following coffee intake. We aimed to evaluate the acute changes in pupil size and OWA of the eye after single administration of coffee. A total of 30 otherwise healthy participants were included in this prospective study. All subjects drank a cup of coffee containing 57 mg caffeine. Measurements of pupil size, total coma (TC), total trefoil (TF), total spherical aberration (TSA), and total higher order aberration (HOA) were performed before and at 5 minutes, at 30 minutes, and at 4 hours after coffee drinking using a wavefront aberrometer device (Irx3, Imagine Eyes, Orsay, France). The mean age of the study population was 20.30 ± 2.74 years. Pupil size did not show a significant change during the measurements (p > 0.05). A significant increase was observed in TF and HOA measurements following coffee intake (p = 0.029 and p = 0.009, resp.). Single administration of coffee results in significant increase in TF and total HOAs in healthy subjects without any effect on pupil diameter. Ultrastructural changes in the cornea following coffee intake might be of relevance to the alterations in ocular aberrations in healthy subjects. PMID:27437402

  20. Effect of Single Administration of Coffee on Pupil Size and Ocular Wavefront Aberration Measurements in Healthy Subjects

    PubMed Central

    Bardak, Handan; Gunay, Murat; Mumcu, Ugur; Bardak, Yavuz

    2016-01-01

    No study has so far evaluated the impact of coffee drinking on ocular wavefront aberration (OWA) measurements. This study presents novel findings regarding the OWA of the eye following coffee intake. We aimed to evaluate the acute changes in pupil size and OWA of the eye after single administration of coffee. A total of 30 otherwise healthy participants were included in this prospective study. All subjects drank a cup of coffee containing 57 mg caffeine. Measurements of pupil size, total coma (TC), total trefoil (TF), total spherical aberration (TSA), and total higher order aberration (HOA) were performed before and at 5 minutes, at 30 minutes, and at 4 hours after coffee drinking using a wavefront aberrometer device (Irx3, Imagine Eyes, Orsay, France). The mean age of the study population was 20.30 ± 2.74 years. Pupil size did not show a significant change during the measurements (p > 0.05). A significant increase was observed in TF and HOA measurements following coffee intake (p = 0.029 and p = 0.009, resp.). Single administration of coffee results in significant increase in TF and total HOAs in healthy subjects without any effect on pupil diameter. Ultrastructural changes in the cornea following coffee intake might be of relevance to the alterations in ocular aberrations in healthy subjects. PMID:27437402

  1. Design and Performance Assessment of a Stable Astigmatic Herriott Cell for Trace Gas Measurements on Airborne Platforms

    NASA Technical Reports Server (NTRS)

    Dyroff, Christoph; Fried, Alan; Richter, Dirk; Walega, James G.; Zahniser, Mark S.; McManus, J. Barry

    2005-01-01

    The present paper discusses a new, more stable, astigmatic Herriott cell employing carbon fiber stabilizing rods. Laboratory tests using a near-IR absorption feature of CO at 1564.168-nm revealed a factor of two improvement in measurement stability compared with the present commercial design when the sampling pressure was changed by +/-2 Torr around 50 Torr. This new cell should significantly enhance our efforts to measure trace gases employing pathlengths of 100 to 200-meters on airborne platforms with minimum detectable line center absorbances of less than 10(exp -6).

  2. Air bubble in anterior chamber as indicator of full-thickness incisions in femtosecond-assisted astigmatic keratotomy.

    PubMed

    Vaddavalli, Pravin K; Hurmeric, Volkan; Yoo, Sonia H

    2011-09-01

    Femtosecond-assisted astigmatic keratotomy is predictable and precise but may occasionally lead to a full-thickness incision on the cornea and the attendant complications. The presence of an air bubble in the anterior chamber soon after creation of the keratotomy by the femtosecond laser may indicate a full-thickness incision. We present a case in which recognition of this clinical finding early in the procedure might have prevented undesirable complications, such as leakage of aqueous and the potential for intraocular infection.

  3. Psychometric Characteristics of the Aberrant Behavior Checklist.

    ERIC Educational Resources Information Center

    Aman, Michael G.; And Others

    1985-01-01

    Information is presented on the psychometric characteristics of the Aberrant Behavior Checklist, a measure of psychotropic drug effects. Internal consistency and test-retest reliability of the checklist appeared very good. Interrater reliability was generally in the moderate range. In general, validity was established for most Aberrant Behavior…

  4. Harmonic oscillator states in aberration optics

    NASA Technical Reports Server (NTRS)

    Wolf, Kurt Bernardo

    1993-01-01

    The states of the three-dimensional quantum harmonic oscillator classify optical aberrations of axis-symmetric systems due to the isomorphism between the two mathematical structures. Cartesian quanta and angular momentum classifications have their corresponding aberration classifications. The operation of concatenation of optical elements introduces a new operation between harmonic oscillator states.

  5. CHOP Infant Coma Scale ("Infant Face Scale"): a novel coma scale for children less than two years of age.

    PubMed

    Durham, S R; Clancy, R R; Leuthardt, E; Sun, P; Kamerling, S; Dominguez, T; Duhaime, A C

    2000-09-01

    The Glasgow Coma Scale (GCS) is the most frequently used tool worldwide for assessing the severity of neurologic injury after brain trauma, although applying this scale to infants and younger children can be problematic. The CHOP Infant Coma Scale, or Infant Face Scale (IFS), is a novel scale for children under 2 years of age which differs from other pediatric coma scales in the following ways: (1) it relies on objective behavioral observations; (2) it assesses cortical as well as brainstem function; (3) it parallels the GCS in scoring but is based on infant-appropriate behaviors; and (4) it can be applied to intubated patients. We report the results of a prospective study designed to compare interrater reliability between the IFS and GCS in children less than 2 years of age. Seventy-five hospitalized children less than 2 years of age were assessed simultaneously by a pair of observers, representing a spectrum of health care professionals, who scored the children using both the IFS and GCS. Interrater reliability for each pair of observers for each scale was assessed using the kappa statistic. A second series of 10 infants in the intensive care unit with specific diagnoses of acute traumatic or hypoxic/ischemic brain injury were similarly assessed. In the 75 hospitalized infants with a variety of diagnoses, interrater reliability for the GCS was in the "almost perfect," "slight," and "fair" range for the eye-opening, motor, and verbal subtests, respectively. In contrast, the IFS showed interrater reliability in the "almost perfect," "substantial," and "almost perfect" ranges for the three subtests. When applied to infants in an intensive care unit with acute traumatic brain injury or hypoxia/ischemia, the GCS interrater reliability scores were in the "fair" range, while the IFS scores were in the "almost perfect" range. The IFS demonstrates improved interrater reliability in direct comparison to the GCS, particularly in the "verbal/face" component where most

  6. Aberrant Radial Artery Causing Carpal Tunnel Syndrome

    PubMed Central

    Kokkalis, Zinon T.; Tolis, Konstantinos E.; Megaloikonomos, Panayiotis D.; Panagopoulos, Georgios N.; Igoumenou, Vasilios G.; Mavrogenis, Andreas F.

    2016-01-01

    Anatomical vascular variations are rare causes of carpal tunnel syndrome. An aberrant medial artery is the most common vascular variation, while an aberrant radial artery causing carpal tunnel syndrome is even more rare, with an incidence ranging less than 3%. This article reports a patient with compression of the median nerve at the carpal tunnel by an aberrant superficial branch of the radial artery. An 80- year- old man presented with a 5-year history of right hand carpal tunnel syndrome; Tinel sign, Phalen test and neurophysiological studies were positive. Open carpal tunnel release showed an aberrant superficial branch of the radial artery with its accompanying veins running from radially to medially, almost parallel to the median nerve, ending at the superficial palmar arterial arch. The median nerve was decompressed without ligating the aberrant artery. At the last follow-up, 2 years after diagnosis and treatment the patient is asymptomatic. PMID:27517078

  7. Aberrant Radial Artery Causing Carpal Tunnel Syndrome.

    PubMed

    Kokkalis, Zinon T; Tolis, Konstantinos E; Megaloikonomos, Panayiotis D; Panagopoulos, Georgios N; Igoumenou, Vasilios G; Mavrogenis, Andreas F

    2016-06-01

    Anatomical vascular variations are rare causes of carpal tunnel syndrome. An aberrant medial artery is the most common vascular variation, while an aberrant radial artery causing carpal tunnel syndrome is even more rare, with an incidence ranging less than 3%. This article reports a patient with compression of the median nerve at the carpal tunnel by an aberrant superficial branch of the radial artery. An 80- year- old man presented with a 5-year history of right hand carpal tunnel syndrome; Tinel sign, Phalen test and neurophysiological studies were positive. Open carpal tunnel release showed an aberrant superficial branch of the radial artery with its accompanying veins running from radially to medially, almost parallel to the median nerve, ending at the superficial palmar arterial arch. The median nerve was decompressed without ligating the aberrant artery. At the last follow-up, 2 years after diagnosis and treatment the patient is asymptomatic.

  8. Aberrant Radial Artery Causing Carpal Tunnel Syndrome.

    PubMed

    Kokkalis, Zinon T; Tolis, Konstantinos E; Megaloikonomos, Panayiotis D; Panagopoulos, Georgios N; Igoumenou, Vasilios G; Mavrogenis, Andreas F

    2016-06-01

    Anatomical vascular variations are rare causes of carpal tunnel syndrome. An aberrant medial artery is the most common vascular variation, while an aberrant radial artery causing carpal tunnel syndrome is even more rare, with an incidence ranging less than 3%. This article reports a patient with compression of the median nerve at the carpal tunnel by an aberrant superficial branch of the radial artery. An 80- year- old man presented with a 5-year history of right hand carpal tunnel syndrome; Tinel sign, Phalen test and neurophysiological studies were positive. Open carpal tunnel release showed an aberrant superficial branch of the radial artery with its accompanying veins running from radially to medially, almost parallel to the median nerve, ending at the superficial palmar arterial arch. The median nerve was decompressed without ligating the aberrant artery. At the last follow-up, 2 years after diagnosis and treatment the patient is asymptomatic. PMID:27517078

  9. X-ray archaeology in the Coma cluster

    NASA Technical Reports Server (NTRS)

    White, Simon D. M.; Briel, Ulrich G.; Henry, J. P.

    1993-01-01

    We present images of X-ray emission from hot gas within the Coma cluster of galaxies. These maps, made with the ROSAT satellite, have much higher SNR than any previous X-ray image of a galaxy cluster, and allow cluster structure to be analyzed in unprecedented detail. They show greater structural irregularity than might have been anticipated from earlier observations of Coma. Emission is detected from a number of bright cluster galaxies in addition to the two known previously. In four cases, there is evidence that these galaxies lie at the center of an extended subconcentration within the cluster, possibly the remnant of their associated groups. For at least two galaxies, the images show direct evidence for ongoing disruption of their gaseous atmosphere. The luminosity associated with these galaxies is comparable to that detected around similar ellipticals in much poorer environments. Emission is easily detected to the limit of our field, about 1 deg from the cluster center, and appears to become more regular at large radii. The data show clearly that this archetype of a rich and regular galaxy cluster was, in fact, formed by the merging of several distinct subunits which are not yet fully destroyed.

  10. Water chemistry in comet comae in support of spacecraft missions

    NASA Astrophysics Data System (ADS)

    Wegmann, R.; Boice, D. C.

    Water chemistry is central in understanding the physics and chemistry of comets It is a major source of ions and electrons that further initiate key gas-phase reactions leading to the plethora of molecules and atoms seen in cometary atmospheres The relevant physico-chemical processes are identified within a modeling framework to understand in situ measurements of comets from spacecraft missions e g Halley Borrelly Tempel 1 Wild 2 and to provide valuable insights into the intrinsic properties of their nuclei Rodgers S D Charnley S B Huebner W F and Boice D C Physical Processes and Chemical Reactions in Cometary Comae in underline Comets II Festou Keller Weaver eds Univ Arizona Press pp 505-522 2005 Details of these processes are presented from the collision-dominated inner coma to the solar wind interaction region The results include thermodynamics e g temperature and velocity structure and photo- and gas-phase chemistry e g composition gas and electron energetics throughout the cometary atmosphere The effects of photoelectrons that react via electron impact reactions are important to the overall ionization as originally discussed by Boice et al Geophys Res Lett 13 381 1986 and recently revisited by Bhardwaj Geophys Res Lett 30 2244 2003 and Boice and Wegmann Modeling Comet 19P Borrelly for the Deep Space 1 Encounter Highlights of Astronomy 13 in press 2006 This extensive modeling effort to investigate these

  11. Analysis for simplified optics coma effection on spectral image inversion of coded aperture spectral imager

    NASA Astrophysics Data System (ADS)

    Liu, Yangyang; Lv, Qunbo; Li, Weiyan; Xiangli, Bin

    2015-09-01

    As a novel spectrum imaging technology was developed recent years, push-broom coded aperture spectral imaging (PCASI) has the advantages of high throughput, high SNR, high stability etc. This coded aperture spectral imaging utilizes fixed code templates and push-broom mode, which can realize the high-precision reconstruction of spatial and spectral information. But during optical lens designing, manufacturing and debugging, it is inevitably exist some minor coma errors. Even minor coma errors can reduce image quality. In this paper, we simulated the system optical coma error's influence to the quality of reconstructed image, analyzed the variant of the coded aperture in different optical coma effect, then proposed an accurate curve of image quality and optical coma quality in 255×255 size code template, which provide important references for design and development of push-broom coded aperture spectrometer.

  12. Gas Dynamics and Kinetics in the Cometary Coma: Theory and Observations

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.; Harris, Walter M.; Smyth, William H.

    2005-01-01

    Our ability to describe the physical state of the expanding coma affects fundamental areas of cometary study both directly and indirectly. In order to convert measured abundances of gas species in the coma to gas production rates, models for the distribution and kinematics of gas species in the coma are required. Conversely, many different types of observations, together with laboratory data and theory, are still required to determine coma model attributes and parameters. Accurate relative and absolute gas production rates and their variations with time and from comet to comet are crucial to our basic understanding of the composition and structure of cometary nuclei and their place in the solar system. We review the gas dynamics and kinetics of cometary comae from both theoretical and observational perspectives, which are important for understanding the wide variety of physical conditions that are encountered.

  13. An Explicitly Solvable Case of the Construction of the Fundamental Cavity Mode in the Form of a Gaussian Beam with a Complex Astigmatism

    NASA Astrophysics Data System (ADS)

    Kudashov, V. N.; Plachenov, A. B.; Radin, A. M.

    2000-01-01

    An analysis is carried out of the ring cavities whose fundamental modes represent Gaussian beams with complex astigmatism. The analysis is made for the case where the block B or C in the cavity ray matrix ABCD of dimension 4×4 is a symmetric nondegenerate matrix. Explicit formulas are obtained, which permits the expression of beam characteristics directly in terms of the cavity ray matrix without the laborious process of finding its eigenvectors. The results obtained in the study can be used for controlling astigmatism in lasers and laser systems, the calculation of polarization of three-dimensional active media in linear and ring optical cavities of complex configuration, etc.

  14. Observed medical and surgical complications of prolonged barbiturate coma for refractory status epilepticus

    PubMed Central

    Newey, Christopher R.; Wisco, Dolora; Nattanmai, Premkumar; Sarwal, Aarti

    2016-01-01

    Background: Refractory status epilepticus is often treated with third-line therapy, such as pentobarbital coma. However, its use is limited by side effects. Recognizing and preventing major and minor adverse effects of prolonged pentobarbital coma may increase good outcomes. This study retrospectively reviewed direct and indirect medical and surgical pentobarbital coma. Methods: Retrospective chart review of all patients with refractory status epilepticus treated with pentobarbital over a 1 year period at a large tertiary care center. We collected baseline data, EEG data, and complications that were observed. Results: Overall, nine patients [median age 46.4 (IQR 21.7, 75.5) years] were induced with pentobarbital coma median 11 (IQR 3, 33) days after seizure onset for a median of 9 (IQR 3.5, 45.4) days. A total of four to eight concurrent antiepileptics were tried prior to the pentobarbital coma. Phenobarbital, due to recurrence of seizures on weaning pentobarbital coma, was required in seven patients. Observed complications included peripheral neuropathy (77.8%), cerebral atrophy (33.3%), volume overload (44.4%), renal/metabolic (77.8%), gastrointestinal (66.6%), endocrine (55.6%), cardiac/hemodynamic/vascular (77.8%), respiratory (100%), and infectious (77.8%). The number of complications trended with duration of induced coma but was nonsignificant. Median ICU length of stay was 40 (IQR 28, 97.5) days. Overall, five patients were able to follow commands after a median 37 (IQR 25.5, 90) days from coma onset. There were eight patients that were discharged from hospital with three remaining in a prolonged unresponsive state. There was one patient that died prior to discharge. Conclusions: This study highlights the high morbidity in patients with refractory status epilepticus requiring pentobarbital coma. Anticipating and addressing the indirect and direct complications in prolonged pentobarbital coma may improve survival and functional outcomes in patients with

  15. Quantitative analysis of radiation-induced chromosome aberrations.

    PubMed

    Sachs, R K; Levy, D; Hahnfeldt, P; Hlatky, L

    2004-01-01

    We review chromosome aberration modeling and its applications, especially to biodosimetry and to characterizing chromosome geometry. Standard results on aberration formation pathways, randomness, dose-response, proximity effects, transmissibility, kinetics, and relations to other radiobiological endpoints are summarized. We also outline recent work on graph-theoretical descriptions of aberrations, Monte-Carlo computer simulations of aberration spectra, software for quantifying aberration complexity, and systematic links of apparently incomplete with complete or truly incomplete aberrations. PMID:15162028

  16. Image-based EUVL aberration metrology

    NASA Astrophysics Data System (ADS)

    Fenger, Germain Louis

    A significant factor in the degradation of nanolithographic image fidelity is optical wavefront aberration. As resolution of nanolithography systems increases, effects of wavefront aberrations on aerial image become more influential. The tolerance of such aberrations is governed by the requirements of features that are being imaged, often requiring lenses that can be corrected with a high degree of accuracy and precision. Resolution of lithographic systems is driven by scaling wavelength down and numerical aperture (NA) up. However, aberrations are also affected from the changes in wavelength and NA. Reduction in wavelength or increase in NA result in greater impact of aberrations, where the latter shows a quadratic dependence. Current demands in semiconductor manufacturing are constantly pushing lithographic systems to operate at the diffraction limit; hence, prompting a need to reduce all degrading effects on image properties to achieve maximum performance. Therefore, the need for highly accurate in-situ aberration measurement and correction is paramount. In this work, an approach has been developed in which several targets including phase wheel, phase disk, phase edges, and binary structures are used to generate optical images to detect and monitor aberrations in extreme ultraviolet (EUV) lithographic systems. The benefit of using printed patterns as opposed to other techniques is that the lithography system is tested under standard operating conditions. Mathematical models in conjunction with iterative lithographic simulations are used to determine pupil phase wavefront errors and describe them as combinations of Zernike polynomials.

  17. Aberration correction past and present.

    PubMed

    Hawkes, P W

    2009-09-28

    Electron lenses are extremely poor: if glass lenses were as bad, we should see as well with the naked eye as with a microscope! The demonstration by Otto Scherzer in 1936 that skillful lens design could never eliminate the spherical and chromatic aberrations of rotationally symmetric electron lenses was therefore most unwelcome and the other great electron optician of those years, Walter Glaser, never ceased striving to find a loophole in Scherzer's proof. In the wartime and early post-war years, the first proposals for correcting C(s) were made and in 1947, in a second milestone paper, Scherzer listed these and other ways of correcting lenses; soon after, Dennis Gabor invented holography for the same purpose. These approaches will be briefly summarized and the work that led to the successful implementation of quadupole-octopole and sextupole correctors in the 1990 s will be analysed. In conclusion, the elegant role of image algebra in describing image formation and processing and, above all, in developing new methods will be mentioned. PMID:19687058

  18. Distribucion de Hidrogeno Neutro EN Galaxias Espirales de Coma

    NASA Astrophysics Data System (ADS)

    Bravo-Alfaro, H.; van Gorkom, J. H.; Balkowski, C.; Cayatte, V.

    1998-11-01

    We have carried out a study of environmental effects on the properties and evolution of galaxies in clusters. We have studied the HI content of spiral galaxies in two nearby clusters, Abell~262 and Abell~1656 (Coma), from 21cm observations obtained with the Westerbork Synthesis Radio Telescope and with the Very Large Array. These observations have provided us the HI images of a sample of 11 galaxies in Abell~262, and 19 in Coma. We have computed the HI content and analyzed the HI distribution of detected galaxies, what enabled us to study the environmental effects on cluster galaxies, as well as the possible involved physical mechanisms. We confirm the tendency of HI deficient galaxies to be closer to the cluster core. We also estimate in a quantitative fashion the role that ram pressure stripping can play in the central cluster region, where the intra--cluster medium shows its most hostile density and temperature conditions. Most of galaxies showing a perturbed neutral hydrogen distribution are likely affected by ram pressure. Five star--bursting galaxies and one post--starburst were detected among the 19 HI detected objects in Coma. We conclude, from the analysis of their HI distribution and from the correlations of their positions in the cluster and U--V colors with the HI deficiency, that some cluster galaxies may follow an evolutionary sequence: galaxies would first become blue because of the interaction with the ICM, what trigger a burst of star--formation. Galaxies appear at this stage as HI deficient. The next step in this sequence would be the PSB stage, where galaxies arrive once they quench most of their HI reservoir and the star--formation stops in a short time-scale. The deep neutral gas stripping explain why these galaxies are hardly detected in HI. None of the closest galaxies to NGC~4839 have been detected in our observations around the Southwest group, what hints a previous passage across the cluster core with the consequence of a stripping process

  19. On the chemistry of CS and NS in cometary comae

    NASA Astrophysics Data System (ADS)

    Canaves, M.; de Almeida, A.; Boice, D.; Sanzovo, G.

    The most fundamental scientific reason for studying comets is to retrieve information on their origin, relationship to interstellar and interplanetary material and implication for the formation of the Solar System or Cosmogony. The determination of the basic parameters of the nucleus and its activity and comp osition is desirable in order to establish a consistent database for comparative studies of comets and, as such, is vital for the safety and success of space missions. The objective of the present work is to contribute to the establishment of a unique description of the physical-chemical nature of the nucleus. We study carbon monosulfide (CS) - which is the only sulfur compound that persistently appears in cometary ultraviolet spectra and, therefore, seems to play a key role in sulfur photochemistry in cometary comae - and nitrogen monosulfide (NS) - the first cometary molecular species to contain both nitrogen and sulfur atoms which was recently observed by Irvine et al. (2000) in comet Hale -Bopp. The determination of the abundance of each such species helps to constrain the chemistry and physics of comets and hence their place and mode of origin of the nucleus. With this purpose in mind we have developed a multifluid chemical model of cometary comae (Boice 1990) with gas-phase chemical kinetics and gas dynamics to predict molecular abundance variations in a sensitive manner with cometocentric distance. We apply the model to the recent bright comets Hyakutake and Hale-Bopp at a heliocentric distance of 1 AU to study the abundances of CS and NS in their comae using a detailed photo and chemical reaction network with more than 100 species and over 1000 reactions. We conclude that the CS abundance in comets does not seem to vary much with the cometocentric distance. In particular, if NS is the daughter of an unknown long-lived parent molecular species, its production rate and abundance should be much larger than the obtained values. These results should be

  20. A spectroscopic and photometric study of FK Comae in 1989

    NASA Technical Reports Server (NTRS)

    Huenemoerder, David P.; Ramsey, Lawrence W.; Buzasi, Derek L.; Nations, Harold L.

    1993-01-01

    Results of an observational campaign, coordinated between visual photometry, optical spectroscopy, and UV spectroscopy, to elucidate the characteristics of FK Comae are presented. The photometry showed complicated but systematic behavior. Photospheric absorption lines were distorted by a Doppler-shifted bump caused by dark starspots resulting in small apparent radial velocity variations. No radial velocity variations characteristic of orbital motion were seen to a level of 3 km/s. Broad emission in H-alpha was modulated at the photospheric rotational amplitude, implying an origin no farther from the rotational axis than 1 stellar radius. The strengths of Ca II lines are modulated in phase with H-alpha but do not have velocity-modulated wings like H-alpha.

  1. A flare event in the peculiar giant FK Comae

    NASA Technical Reports Server (NTRS)

    Ramsey, L. W.; Nations, H. L.

    1981-01-01

    Observations are presented of a very energetic flare event in the peculiar rapidly rotating star FK Comae. During this event on June 18th 1981 the usual asymmetrical double peaked H alpha emission feature with an equivalent width (EW) approx 3-4 A changed to a broad emission feature with EW approx 13 A. Sixteen spectra were obtained over 2 hours. Some changes in the emission profile are apparent on this time scale. The following night the enhanced emission persisted but at lower levels and it was substantially redshifted. This event is interpreted in terms of a model where material is injected into a disk co-rotating with the angular velocity of the stellar surface. A localized region of surface activity is conjectured to be the source of the event.

  2. Morgagni: his book, vision and views on hepatic coma.

    PubMed

    Chen, T S; Chen, P S

    1996-11-01

    The study of pathological anatomy reached a culmination in the magnum opus of Morgagni, The Seats and Causes of Diseases. It represented an innovative way of looking at the patient and his illness, a change that Foucault described as occurring in the 18th century. Physicians saw symptoms penetrating the body and converging upon an organ. We suggest that Morgagni and his fellow workers derived their vision from the practice of visual perspective discovered by Italian Renaissance artists. Perceiving in three dimensional terms, Morgagni added spatial depth to our understanding of disease. His acute vision was brilliantly displayed in his views of hepatic coma. He was among the first to provide the clinical-pathological associations of acute liver failure. The limitations of gross morphology precluded a complete elucidation of the disorder.

  3. Image Ellipticity from Atmospheric Aberrations

    SciTech Connect

    de Vries, W H; Olivier, S S; Asztalos, S J; Rosenberg, L J; Baker, K L

    2007-03-06

    We investigate the ellipticity of the point-spread function (PSF) produced by imaging an unresolved source with a telescope, subject to the effects of atmospheric turbulence. It is important to quantify these effects in order to understand the errors in shape measurements of astronomical objects, such as those used to study weak gravitational lensing of field galaxies. The PSF modeling involves either a Fourier transform of the phase information in the pupil plane or a ray-tracing approach, which has the advantage of requiring fewer computations than the Fourier transform. Using a standard method, involving the Gaussian weighted second moments of intensity, we then calculate the ellipticity of the PSF patterns. We find significant ellipticity for the instantaneous patterns (up to more than 10%). Longer exposures, which we approximate by combining multiple (N) images from uncorrelated atmospheric realizations, yield progressively lower ellipticity (as 1/{radical}N). We also verify that the measured ellipticity does not depend on the sampling interval in the pupil plane using the Fourier method. However, we find that the results using the ray-tracing technique do depend on the pupil sampling interval, representing a gradual breakdown of the geometric approximation at high spatial frequencies. Therefore, ray tracing is generally not an accurate method of modeling PSF ellipticity induced by atmospheric turbulence unless some additional procedure is implemented to correctly account for the effects of high spatial frequency aberrations. The Fourier method, however, can be used directly to accurately model PSF ellipticity, which can give insights into errors in the statistics of field galaxy shapes used in studies of weak gravitational lensing.

  4. Phase Synchronization in Electroencephalographic Recordings Prognosticates Outcome in Paediatric Coma

    PubMed Central

    Nenadovic, Vera; Perez Velazquez, Jose Luis; Hutchison, James Saunders

    2014-01-01

    Brain injury from trauma, cardiac arrest or stroke is the most important cause of death and acquired disability in the paediatric population. Due to the lifetime impact of brain injury, there is a need for methods to stratify patient risk and ultimately predict outcome. Early prognosis is fundamental to the implementation of interventions to improve recovery, but no clinical model as yet exists. Healthy physiology is associated with a relative high variability of physiologic signals in organ systems. This was first evaluated in heart rate variability research. Brain variability can be quantified through electroencephalographic (EEG) phase synchrony. We hypothesised that variability in brain signals from EEG recordings would correlate with patient outcome after brain injury. Lower variability in EEG phase synchronization, would be associated with poor patient prognosis. A retrospective study, spanning 10 years (2000–2010) analysed the scalp EEGs of children aged 1 month to 17 years in coma (Glasgow Coma Scale, GCS, <8) admitted to the paediatric critical care unit (PCCU) following brain injury from TBI, cardiac arrest or stroke. Phase synchrony of the EEGs was evaluated using the Hilbert transform and the variability of the phase synchrony calculated. Outcome was evaluated using the 6 point Paediatric Performance Category Score (PCPC) based on chart review at the time of hospital discharge. Outcome was dichotomized to good outcome (PCPC score 1 to 3) and poor outcome (PCPC score 4 to 6). Children who had a poor outcome following brain injury secondary to cardiac arrest, TBI or stroke, had a higher magnitude of synchrony (R index), a lower spatial complexity of the synchrony patterns and a lower temporal variability of the synchrony index values at 15 Hz when compared to those patients with a good outcome. PMID:24752289

  5. Spherical aberration in electrically thin flat lenses.

    PubMed

    Ruphuy, Miguel; Ramahi, Omar M

    2016-08-01

    We analyze the spherical aberration of a new generation of lenses made of flat electrically thin inhomogeneous media. For such lenses, spherical aberration is analyzed quantitatively and qualitatively, and comparison is made to the classical gradient index rod. Both flat thin and thick lenses are made of gradient index materials, but the physical mechanisms and design equations are different. Using full-wave three-dimensional numerical simulation, we evaluate the spherical aberrations using the Maréchal criterion and show that the thin lens gives significantly better performance than the thick lens (rod). Additionally, based on ray tracing formulation, third-order analysis for longitudinal aberration and optical path difference are presented, showing strong overall performance of thin lenses in comparison to classical rod lenses. PMID:27505651

  6. Analysis of dust in the coma of comet 67P using VIRTIS-M observations

    NASA Astrophysics Data System (ADS)

    Rinaldi, G.; Tozzi, G. P.; Fink, U.; Doose, L.; Capaccioni, F.; Filacchione, G.; Bockelée-Morvan, D.; Leyrat, C.; Piccioni, G.; Blecka, M.; Ciarniello, M.; Irwin, P.; Combi, M.; Palomba, E.; Migliorini, A.; Capria, M. T.; Faggi, S.; Tosi, F.

    2015-10-01

    We present a preliminary overview of the analysis on the dust spectrophotometry in the inner coma of comet 67/P that was obtained during the escort phase (started on December 2014) with the imaging spectrometer VIRTIS-M onboard the Rosetta mission [1]. The morphology and behavior of the dust coma has been monitored by VIRTIS-M from the arrival at the comet (~August 2014) throughout the early escort phase. The data reveal intricate details and numerous radial jets coming from different regions on the surface. On March 15, 2015, VIRTIS-M performed a set of 22 coma observations, each about 23 minutes in duration and offset from the nucleus by about 1 km. The 22 observations lasted about 12 hours and thus covered a complete rotation of the comet. The maps of the dust distribution in the coma reveal three major structures: a roughly uniform background dusty coma, several enhanced radiance jet features and a region that shows a thermal radiation component between 3.5 and 5.0 μm. (Figure 1 and Figure 2) The jets features can be traced back to several region of the comet, neck,body and head. We shall analyse the three major structures to provide the basis to understand coma composition and properties and the relation between gas and dust. We will discuss the morphology of the background coma, the jet and the enhanced thermal radiation. We will also examine correlations between the water vapor column density and the coma/ jet /thermal radiation intensity. For the thermal radiation component there are several explanations, viz: stray instrumental scattered light or instrumental ghosts from heated part of the nucleus, or thermal rad iation emanating from the nucleus and scattered by the dust in closest proximity or a region of small particles in the coma heated by solar radiation.

  7. Chromosome aberrations in decondensed sperm DNA

    SciTech Connect

    Preston, R.J.

    1982-01-01

    Factors that could influence the chromosomal aberration frequency observed at first cleavage following in vivo exposure of germ cells to chemical mutagens are discussed. The techniques of chromosome aberration analysis following sperm DNA condensation by in vitro fertilization or fusion seem to be viable research areas for providing information of human germ cell exposures. However, the potential sensitivity of the assay needs to be better understood, and factors that can influence this sensitivity require a great deal of further study using animal models.

  8. The dust coma of 67P/Churyumov-Gerasimenko as seen by OSIRIS onboard Rosetta

    NASA Astrophysics Data System (ADS)

    Tubiana, C.; Bertini, I.; Bodewits, D.; Davidsson, B.; Güttler, C.; Lara, L. M.; Moreno, F.; Cremonese, G.; La Forgia, F.; Oklay, N.; Pajola, M.; Sierks, H.

    2015-10-01

    The dust coma of 67P was detected and monitored by OSIRIS, the scientific camera onboard Rosetta, since the beginning of the post-hibernation operations in March 2014. A complete description of the coma during the approach phase to the comet was presented in [5], including the detection of a sudden cometary outburst at the end of April 2014. OSIRIS images acquired at the end of the approach (July 2014) and during the escort phase were used to characterize dust particles present in the comet's inner coma ([4], [3], [2], [1]).

  9. Dynamics of the eye's wave aberration.

    PubMed

    Hofer, H; Artal, P; Singer, B; Aragón, J L; Williams, D R

    2001-03-01

    It is well known that the eye's optics exhibit temporal instability in the form of microfluctuations in focus; however, almost nothing is known of the temporal properties of the eye's other aberrations. We constructed a real-time Hartmann-Shack (HS) wave-front sensor to measure these dynamics at frequencies as high as 60 Hz. To reduce spatial inhomogeneities in the short-exposure HS images, we used a low-coherence source and a scanning system. HS images were collected on three normal subjects with natural and paralyzed accommodation. Average temporal power spectra were computed for the wave-front rms, the Seidel aberrations, and each of 32 Zernike coefficients. The results indicate the presence of fluctuations in all of the eye's aberration, not just defocus. Fluctuations in higher-order aberrations share similar spectra and bandwidths both within and between subjects, dropping at a rate of approximately 4 dB per octave in temporal frequency. The spectrum shape for higher-order aberrations is generally different from that for microfluctuations of accommodation. The origin of these measured fluctuations is not known, and both corneal/lenticular and retinal causes are considered. Under the assumption that they are purely corneal or lenticular, calculations suggest that a perfect adaptive optics system with a closed-loop bandwidth of 1-2 Hz could correct these aberrations well enough to achieve diffraction-limited imaging over a dilated pupil. PMID:11265680

  10. Pulse compressor with aberration correction

    SciTech Connect

    Mankos, Marian

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  11. Methods for calculating the vergence of an astigmatic ray bundle in an optical system that contains a freeform surface

    NASA Astrophysics Data System (ADS)

    Shirayanagi, Moriyasu

    2016-07-01

    A method using the generalized Coddington equations enables calculating the vergence of an astigmatic ray bundle in the vicinity of a skew ray in an optical system containing a freeform surface. Because this method requires time-consuming calculations, however, there is still room for increasing the calculation speed. In addition, this method cannot be applied to optical systems containing a medium with a gradient index. Therefore, we propose two new calculation methods in this paper. The first method, using differential ray tracing, enables us to shorten computation time by using simpler algorithms than those used by conventional methods. The second method, using proximate rays, employs only the ray data obtained from the rays exiting an optical system. Therefore, this method can be applied to an optical system that contains a medium with a gradient index. We show some sample applications of these methods in the field of ophthalmic optics.

  12. Cometary science. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko.

    PubMed

    Hässig, M; Altwegg, K; Balsiger, H; Bar-Nun, A; Berthelier, J J; Bieler, A; Bochsler, P; Briois, C; Calmonte, U; Combi, M; De Keyser, J; Eberhardt, P; Fiethe, B; Fuselier, S A; Galand, M; Gasc, S; Gombosi, T I; Hansen, K C; Jäckel, A; Keller, H U; Kopp, E; Korth, A; Kührt, E; Le Roy, L; Mall, U; Marty, B; Mousis, O; Neefs, E; Owen, T; Rème, H; Rubin, M; Sémon, T; Tornow, C; Tzou, C-Y; Waite, J H; Wurz, P

    2015-01-23

    Comets contain the best-preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov-Gerasimenko with well-sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water, carbon monoxide, and carbon dioxide. These results indicate a complex coma-nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface. PMID:25613892

  13. The origin of low mass particles within and beyond the dust coma envelopes of Comet Halley

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Rabinowitz, D.; Tuzzolino, A. J.; Ksanfomality, L. V.; Sagdeev, R. Z.

    1987-01-01

    Measurements from the Dust Counter and Mass Analyzer (DUCMA) instruments on VEGA-1 and -2 revealed unexpected fluxes of low mass (up to 10 to the minus 13th power g) dust particles at very great distances from the nucleus (300,000 to 600,000 km). These particles are detected in clusters (10 sec duration), preceded and followed by relatively long time intervals during which no dust is detected. This cluster phenomenon also occurs inside the envelope boundaries. Clusters of low mass particles are intermixed with the overall dust distribution throughout the coma. The clusters account for many of the short-term small-scale intensity enhancements previously ascribed to microjets in the coma. The origin of these clusters appears to be emission from the nucleus of large conglomerates which disintegrate in the coma to yield clusters of discrete, small particles continuing outward to the distant coma.

  14. Streaming Clumps Ejection Model and the Heterogeneous Inner Coma of Comet Wild 2

    NASA Technical Reports Server (NTRS)

    Clark, B. C.; Economou, T. E.; Green, S. F.; Sandford, S. A.; Zolensky, M. E.

    2004-01-01

    The conventional concept of cometary comae is that they are dominated by fine particulates released individually by sublimation of surface volatiles and subsequent entrainment in the near-surface gas. It has long been recognized that such particulates could be relatively large, with early estimates that objects perhaps up to one meter in size may be levitated from the surface of the typical cometary nucleus. However, the general uniformity and small average particulate size of observed comae and the relatively smooth, monotonic increases and decreases in particle density during the Giotto flythrough of comet Halley s coma in 1986 reinforced the view that the bulk of the particles are released at the surface, are fine-sized and inert. Jets have been interpreted as geometrically constrained release of these particulates. With major heterogeneities observed during the recent flythrough of the inner coma of comet Wild 2, these views deserve reconsideration.

  15. Cometary science. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko.

    PubMed

    Hässig, M; Altwegg, K; Balsiger, H; Bar-Nun, A; Berthelier, J J; Bieler, A; Bochsler, P; Briois, C; Calmonte, U; Combi, M; De Keyser, J; Eberhardt, P; Fiethe, B; Fuselier, S A; Galand, M; Gasc, S; Gombosi, T I; Hansen, K C; Jäckel, A; Keller, H U; Kopp, E; Korth, A; Kührt, E; Le Roy, L; Mall, U; Marty, B; Mousis, O; Neefs, E; Owen, T; Rème, H; Rubin, M; Sémon, T; Tornow, C; Tzou, C-Y; Waite, J H; Wurz, P

    2015-01-23

    Comets contain the best-preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov-Gerasimenko with well-sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water, carbon monoxide, and carbon dioxide. These results indicate a complex coma-nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface.

  16. Post-perihelion coma monitoring of comet Hale-Bopp at ESO

    NASA Astrophysics Data System (ADS)

    Boehnhardt, H.; Bonfils, X.; Petit, Y.; Hainaut, O.; Delahodde, C.; Jorda, L.; Rauer, H.; Colas, F.; Manfroid, J.; Marchis, F.; Schulz, R.; Tanabe, R.; Tozzi, G. P.

    2002-11-01

    The post-perihelion coma activity of Comet C/1995 O1 Hale-Bopp is monitored at ESO telescopes in La Silla and Paranal since Sept. 1997. Imaging through broadband filters in the visible and near-IR wavelength ranges allows to investigate the evolution of the dust coma, namely the appearance of jets, fans, shells and clouds. Long-term evolution: the comet had a porcupine-like embedded fan coma in autumn 1997 that evolved into a northern fan plus shell pattern in 1998 and remains like this since. Thus, the evolution of the coma structure post-perihelion was similar to that pre-perihelion at about the same heliocentric distances, but is occurred in reversed order. This long-term evolution can be characterized by quasi-continuous dust emission from a few (minimum 4) active regions (producing the fan structures) on the nucleus that is modulated by occasional, repetitive and short-term activity increases (generating shell features in the coma). Outbursts: a number of outbursts and unusual activity patterns occurred in the coma of the comet post-perihelion that are documented through the appearance of complex "palm-tree-like" structures of temporary nature in association with outbursts in the visual lightcurve of the comet and a series of 3 dust clouds resembling "mini-comets" and passing through the northern coma at projected velocities of 30-50m/s. The similarity of coma patterns and cometary viewing geometry from Earth before and after perihelion suggests that some nuclear regions had enhanced long-term activity, possibly driven by super-volatile ices at larger (>10AU) heliocentric distances and that the orientation of the rotation axis of the nucleus did not change much over the past 7 years.

  17. 'Is she alive? Is she dead?' Representations of chronic disorders of consciousness in Douglas Coupland's Girlfriend in a Coma.

    PubMed

    Colbeck, Matthew

    2016-09-01

    Depictions of coma have come to dominate literary and filmic texts over the last half century, a phenomenon coinciding with advancements in medical technology that have led to remarkable increases in the survival rates of patients with chronic disorders of consciousness. Authors of coma fiction are preoccupied with the imagined subjective experience of coma, often creating complex, dream-like worlds from which the protagonist must escape if survival is to be achieved. However, such representations appear to conflict with medical case studies and patient narratives that reveal that most often survivors of coma have no recollection of the coma itself. Providing a close reading of Douglas Coupland's Girlfriend in a Coma (1998) against the context of medical literature and diagnoses, this article examines how the coma patient is represented, often depicting the realities of a prolonged vegetative state, in contrast with other popular representations of coma. It explores how the author develops a work of 'fantastic' fiction (a genre defined by the structuralist critic Tzvetan Todorov), using the condition of coma as a metaphor for a postmodern existential crisis, while simultaneously employing mimetic techniques that raise important medical, ethical and philosophical questions surrounding the ontological status of the comatose patient. It is argued that coma fiction, even in its misrepresentation of the condition, can help us to engage with and interrogate how we think about chronic disorders of consciousness, thereby providing a valuable insight into our attitudes towards illness and mortality.

  18. Robust control of burst suppression for medical coma

    NASA Astrophysics Data System (ADS)

    Westover, M. Brandon; Kim, Seong-Eun; Ching, ShiNung; Purdon, Patrick L.; Brown, Emery N.

    2015-08-01

    Objective. Medical coma is an anesthetic-induced state of brain inactivation, manifest in the electroencephalogram by burst suppression. Feedback control can be used to regulate burst suppression, however, previous designs have not been robust. Robust control design is critical under real-world operating conditions, subject to substantial pharmacokinetic and pharmacodynamic parameter uncertainty and unpredictable external disturbances. We sought to develop a robust closed-loop anesthesia delivery (CLAD) system to control medical coma. Approach. We developed a robust CLAD system to control the burst suppression probability (BSP). We developed a novel BSP tracking algorithm based on realistic models of propofol pharmacokinetics and pharmacodynamics. We also developed a practical method for estimating patient-specific pharmacodynamics parameters. Finally, we synthesized a robust proportional integral controller. Using a factorial design spanning patient age, mass, height, and gender, we tested whether the system performed within clinically acceptable limits. Throughout all experiments we subjected the system to disturbances, simulating treatment of refractory status epilepticus in a real-world intensive care unit environment. Main results. In 5400 simulations, CLAD behavior remained within specifications. Transient behavior after a step in target BSP from 0.2 to 0.8 exhibited a rise time (the median (min, max)) of 1.4 [1.1, 1.9] min; settling time, 7.8 [4.2, 9.0] min; and percent overshoot of 9.6 [2.3, 10.8]%. Under steady state conditions the CLAD system exhibited a median error of 0.1 [-0.5, 0.9]%; inaccuracy of 1.8 [0.9, 3.4]%; oscillation index of 1.8 [0.9, 3.4]%; and maximum instantaneous propofol dose of 4.3 [2.1, 10.5] mg kg-1. The maximum hourly propofol dose was 4.3 [2.1, 10.3] mg kg-1 h-1. Performance fell within clinically acceptable limits for all measures. Significance. A CLAD system designed using robust control theory achieves clinically acceptable

  19. Robust control of burst suppression for medical coma

    PubMed Central

    Westover, M Brandon; Kim, Seong-Eun; Ching, ShiNung; Purdon, Patrick L; Brown, Emery N

    2015-01-01

    Objective Medical coma is an anesthetic-induced state of brain inactivation, manifest in the electroencephalogram by burst suppression. Feedback control can be used to regulate burst suppression, however, previous designs have not been robust. Robust control design is critical under real-world operating conditions, subject to substantial pharmacokinetic and pharmacodynamic parameter uncertainty and unpredictable external disturbances. We sought to develop a robust closed-loop anesthesia delivery (CLAD) system to control medical coma. Approach We developed a robust CLAD system to control the burst suppression probability (BSP). We developed a novel BSP tracking algorithm based on realistic models of propofol pharmacokinetics and pharmacodynamics. We also developed a practical method for estimating patient-specific pharmacodynamics parameters. Finally, we synthesized a robust proportional integral controller. Using a factorial design spanning patient age, mass, height, and gender, we tested whether the system performed within clinically acceptable limits. Throughout all experiments we subjected the system to disturbances, simulating treatment of refractory status epilepticus in a real-world intensive care unit environment. Main results In 5400 simulations, CLAD behavior remained within specifications. Transient behavior after a step in target BSP from 0.2 to 0.8 exhibited a rise time (the median (min, max)) of 1.4 [1.1, 1.9] min; settling time, 7.8 [4.2, 9.0] min; and percent overshoot of 9.6 [2.3, 10.8]%. Under steady state conditions the CLAD system exhibited a median error of 0.1 [−0.5, 0.9]%; inaccuracy of 1.8 [0.9, 3.4]%; oscillation index of 1.8 [0.9, 3.4]%; and maximum instantaneous propofol dose of 4.3 [2.1, 10.5] mg kg−1. The maximum hourly propofol dose was 4.3 [2.1, 10.3] mg kg−1 h−1. Performance fell within clinically acceptable limits for all measures. Significance A CLAD system designed using robust control theory achieves clinically acceptable

  20. Zonal spherical aberration correction utilizing axial electrodes

    NASA Astrophysics Data System (ADS)

    Chao, Liang C.

    2005-01-01

    Spherical aberration is important in focused ion beam applications where large aperture angles are needed to obtain high beam currents because it results in large tails on the current density distribution. Merwe has shown that for coaxial lenses, negative spherical aberration can be found for rays pass through zonal regions. Merwe"s calculation is valid only for periodic or quasi-periodic lenses and requires a constant axial potential distribution. We have calculated zonal focusing properties of lenses with axial electrodes using nine-point finite difference method and direct ray tracing. Our calculation results indicate that an axial electrode protruding partially into the lens can correct the spherical aberration. When a three-element electrostatic lens is operated at deceleration mode, the introduction of an axial electrode creates zonal regions where the spherical aberration is negative. At deceleration mode, the induced surface charges on the axial electrode have an opposite sign relative to the primary beam. This is in agreement with our previous findings on the study of the correction of spherical aberration utilizing space charges. Same phenomenon was found when an axial electrode is used in conjunction with a cathode lens.

  1. Aberration in proper motions for Galactic stars

    NASA Astrophysics Data System (ADS)

    Liu, J.-C.; Xie, Y.; Zhu, Z.

    2014-12-01

    Accelerations of both the solar system barycenter (SSB) and stars in the MilkyWay cause a systematic observational effect on the stellar proper motions, which was first studied by J. Kovalevsky (2003). This paper intends to extend that work and aims to estimate the magnitude and significance of the aberration in proper motions of stars, especially in the region near the Galactic center (GC). We adopt two models for the Galactic rotation curve to evaluate the aberrational effect on the Galactic plane. We show that the effect of aberration in proper motions depends on the galactocentric distance of stars; it is dominated by the acceleration of stars in the central region of the Galaxy. Then we investigate the applicability of the theoretical expressions: if the orbital period of stars is only a fraction of the light time from the star to the SSB, the expression with approximation proposed by Kovalevsky is not appropriate. With a more suitable formulation, we found that the aberration has no effect on the determination of the stellar orbits on the celestial sphere. In the future this aberrational effect under consideration should be considered with high-accurate astrometry, particularly in constructing the Gaia celestial reference system realized by Galactic stars.

  2. Feeding impairs chill coma recovery in the migratory locust (Locusta migratoria).

    PubMed

    Andersen, Jonas Lembcke; Findsen, Anders; Overgaard, Johannes

    2013-10-01

    Low temperature causes loss of neuromuscular function in a wide range of insects, such that the animals enter a state known as chill coma. The ability to recover from chill coma (chill coma recovery time) is often a popular phenotype to characterise chill tolerance in insects. Chill coma in insects has been shown to be associated with a decrease in haemolymph volume and a marked increase in [K(+)], causing dissipation of K(+) equilibrium potential and resting membrane potential. High potassium diet (wheat) has also previously been shown to increase haemolymph [K(+)] in Locusta migratoria leading to sluggish behaviour. The present study combined these two independent stressors of ion and water homeostasis, in order to investigate the role of K(+)- and water-balance during recovery from chill coma, in the chill sensitive insect L. migratoria. We confirmed that cold shock elicits a fast increase in haemolymph [K(+)] which is likely caused by a water shift from the haemolymph to the muscles and other tissues. Recovery of haemolymph [K(+)] is however not only reliant on recovery of haemolymph volume, as the recovery of water and K(+) is decoupled. Chill coma recovery time, after 2h at -4 °C, differed significantly between fasted animals and those fed on high K(+) diet. This difference was not associated with an increased disturbance of haemolymph [K(+)] in the fed animals, instead it was associated with a slowed recovery of muscle [K(+)], muslce water, haemolymph [Na(+)] and K(+)equilibrium potential in the fed animals.

  3. MMN and Novelty P3 in Coma and Other Altered States of Consciousness: A Review

    PubMed Central

    Morlet, Dominique; Fischer, Catherine

    2014-01-01

    In recent decades, there has been a growing interest in the assessment of patients in altered states of consciousness. There is a need for accurate and early prediction of awakening and recovery from coma. Neurophysiological assessment of coma was once restricted to brainstem auditory and primary cortex somatosensory evoked potentials elicited in the thirty millisecond range, which have both shown good predictive value for poor coma outcome only. In this paper, we review how passive auditory oddball paradigms including deviant and novel sounds have proved their efficiency in assessing brain function at a higher level, without requiring the patient’s active involvement, thus providing an enhanced tool for the prediction of coma outcome. The presence of an MMN in response to deviant stimuli highlights preserved automatic sensory memory processes. Recorded during coma, MMN has shown high specificity as a predictor of recovery of consciousness. The presence of a novelty P3 in response to the subject’s own first name presented as a novel (rare) stimulus has shown a good correlation with coma awakening. There is now a growing interest in the search for markers of consciousness, if there are any, in unresponsive patients (chronic vegetative or minimally conscious states). We discuss the different ERP patterns observed in these patients. The presence of novelty P3, including parietal components and possibly followed by a late parietal positivity, raises the possibility that some awareness processes are at work in these unresponsive patients. PMID:24281786

  4. Psychometric characteristics of the aberrant behavior checklist.

    PubMed

    Aman, M G; Singh, N N; Stewart, A W; Field, C J

    1985-03-01

    Information was presented on the psychometric characteristics of the Aberrant Behavior Checklist. The internal consistency and test-retest reliability of the Checklist appeared to be very good. Interrater reliability tended to vary across raters and subscales and ranged from mediocre to good but was generally in the moderate range and acceptable for research purposes. Validity was assessed by comparing Checklist scores for residents presenting with attributes thought to reflect varying degrees of social adaptation. Validity was also evaluated by comparing Aberrant Behavior Checklist scores with ratings on adaptive behavior scales and with objective observations of behavior. In general, validity was established for most Aberrant Behavior Checklist subscales. Preliminary data from drug investigations suggested that the Checklist may provide a useful adjunct for the assessment of psychotropic drug effects.

  5. Chromosome aberrations as bioindicators of environmental genotoxicity.

    PubMed

    Ibrulj, Slavica; Haverić, Sanin; Haverić, Anja

    2007-11-01

    Due to the exposure to various potentially genotoxic xenobiotics, derived from recent war activities such as NATO air strikes with antitank ammunition containing depleted uranium, we have evaluated chromosome aberrations in 84 peripheral blood samples from three local populations. One population sample included 30 individuals who lived in the Sarajevo area during and after the war (exposed to potential genotoxins), second population was presented with 26 employees of the tank repair facility in Hadzići (target of NATO air strikes), and 28 inhabitants of Posusje (not exposed to war-related activities) were treated as sample of control population. The mean of chromosome aberration frequencies for the population from Hadzići was significantly higher than the frequencies for the two other populations. Point bi-serial coefficient analysis did not reveal any relationship between the frequencies of chromosome aberrations and smoking habits or gender. Results suggest that depleted uranium could be a risk factor for human health.

  6. An aberrant precision account of autism

    PubMed Central

    Lawson, Rebecca P.; Rees, Geraint; Friston, Karl J.

    2014-01-01

    Autism is a neurodevelopmental disorder characterized by problems with social-communication, restricted interests and repetitive behavior. A recent and thought-provoking article presented a normative explanation for the perceptual symptoms of autism in terms of a failure of Bayesian inference (Pellicano and Burr, 2012). In response, we suggested that when Bayesian inference is grounded in its neural instantiation—namely, predictive coding—many features of autistic perception can be attributed to aberrant precision (or beliefs about precision) within the context of hierarchical message passing in the brain (Friston et al., 2013). Here, we unpack the aberrant precision account of autism. Specifically, we consider how empirical findings—that speak directly or indirectly to neurobiological mechanisms—are consistent with the aberrant encoding of precision in autism; in particular, an imbalance of the precision ascribed to sensory evidence relative to prior beliefs. PMID:24860482

  7. Stability of auditory event-related potentials in coma research.

    PubMed

    Schorr, Barbara; Schlee, Winfried; Arndt, Marion; Lulé, Dorothée; Kolassa, Iris-Tatjana; Lopez-Rolon, Alex; Lopez-Rolon, Alexander; Bender, Andreas

    2015-02-01

    Patients with unresponsive wakefulness syndrome (UWS) or in minimally conscious state (MCS) after brain injury show significant fluctuations in their behavioural abilities over time. As the importance of event-related potentials (ERPs) in the detection of traces of consciousness increases, we investigated the retest reliability of ERPs with repeated tests at four different time points. Twelve healthy controls and 12 inpatients (8 UWS, 4 MCS; 6 traumatic, 6 non-traumatic) were tested twice a day (morning, afternoon) for 2 days with an auditory oddball task. ERPs were recorded with a 256-channel-EEG system, and correlated with behavioural test scores in the Coma Recovery Scale-revised (CRS-R). The number of identifiable P300 responses varied between zero and four in both groups. Reliabilities varied between Krippendorff's α = 0.43 for within-day comparison, and α = 0.25 for between-day comparison in the patient group. Retest reliability was strong for the CRS-R scores for all comparisons (α = 0.83-0.95). The stability of auditory information processing in patients with disorders of consciousness is the basis for other, even more demanding tasks and cognitive potentials. The relatively low ERP-retest reliability suggests that it is necessary to perform repeated tests, especially when probing for consciousness with ERPs. A single negative ERP test result may be mistaken for proof that a UWS patient truly is unresponsive.

  8. Seizure and coma following Kratom (Mitragynina speciosa Korth) exposure.

    PubMed

    Nelsen, Jamie L; Lapoint, Jeff; Hodgman, Michael J; Aldous, Kenneth M

    2010-12-01

    Reports of toxicity secondary to Kratom are rare and lack of diagnostic testing in human specimens has prevented confirmatory explanation of observed clinical effects. We present a novel case of serious human toxicity following Kratom use confirmed via quantitative analysis of urine by high performance liquid chromatography coupled to electrospray tandem mass spectrometry. A 64 year-old male was witnessed to have a seizure at home following kratom consumption. Upon arrival to the emergency department (ED), the patient was unresponsive. While in the ED, the patient sustained a second seizure. He was intubated to protect his airway. The remainder of his hospital course was uneventful. A urine specimen was collected shortly after admission and sent for analysis. The mitragynine concentration in the urine was 167 ± 15 ng/ml. We report a rare case of Kratom toxicity characterized by a seizure and coma confirmed by urinary analysis of mitragynine by high performance liquid chromatography coupled to electrospray tandem mass spectrometry. The proposed mechanism for this reaction is unclear but suggested mechanisms include adenosine binding or stimulation of adrenergic and/or serotonergic receptors similar to tramadol. PMID:20411370

  9. Dwarf galaxies in the Coma cluster - I. Velocity dispersion measurements

    NASA Astrophysics Data System (ADS)

    Kourkchi, E.; Khosroshahi, H. G.; Carter, D.; Karick, A. M.; Mármol-Queraltó, E.; Chiboucas, K.; Tully, R. B.; Mobasher, B.; Guzmán, R.; Matković, A.; Gruel, N.

    2012-03-01

    We present the study of a large sample of early-type dwarf galaxies in the Coma cluster observed with DEIMOS on the Keck II to determine their internal velocity dispersion. We focus on a subsample of 41 member dwarf elliptical galaxies for which the velocity dispersion can be reliably measured, 26 of which were studied for the first time. The magnitude range of our sample is -21 < MR < -15 mag. This paper (Paper I) focuses on the measurement of the velocity dispersion and their error estimates. The measurements were performed using penalized pixel fitting (PPXF) and using the calcium triplet absorption lines. We use Monte Carlo bootstrapping to study various sources of uncertainty in our measurements, namely statistical uncertainty, template mismatch and other systematics. We find that the main source of uncertainty is the template mismatch effect which is reduced by using templates with a range of spectral types. Combining our measurements with those from the literature, we study the Faber-Jackson relation (L∝σα) and find that the slope of the relation is α= 1.99 ± 0.14 for galaxies brighter than MR≃-16 mag. A comprehensive analysis of the results combined with the photometric properties of these galaxies is reported in Paper II.

  10. Myxedema Coma: A New Look into an Old Crisis

    PubMed Central

    Mathew, Vivek; Misgar, Raiz Ahmad; Ghosh, Sujoy; Mukhopadhyay, Pradip; Roychowdhury, Pradip; Pandit, Kaushik; Mukhopadhyay, Satinath; Chowdhury, Subhankar

    2011-01-01

    Myxedema crisis is a severe life threatening form of decompensated hypothyroidism which is associated with a high mortality rate. Infections and discontinuation of thyroid supplements are the major precipitating factors while hypothermia may not play a major role in tropical countries. Low intracellular T3 leads to cardiogenic shock, respiratory depression, hypothermia and coma. Patients are identified on the basis of a low index of suspicion with a careful history and examination focused on features of hypothyroidism and precipitating factors. Arrythmias and coagulation disorders are increasingly being identified in myxedema crisis. Thyroid replacement should be initiated as early as possible with careful attention to hypotension, fluid replacement and steroid replacement in an intensive care facility. Studies have shown that replacement of thyroid hormone through ryles tube with a loading dose and maintenance therapy is as efficacious as intravenous therapy. In many countries T3 is not available and oral therapy with T4 can be used effectively without major significant difference in outcomes. Hypotension, bradycardia at presentation, need for mechanical ventilation, hypothermia unresponsive to treatment, sepsis, intake of sedative drugs, lower GCS and high APACHE II scores and Sequential Organ Failure Assessment (SOFA) scores more than 6 are significant predictors of mortality in myxedema crisis. Early intervention in hypothyroid patients developing sepsis and other precipitating factors and ensuring continued intake of thyroid supplements may prevent mortality and morbidity associated with myxedema crisis. PMID:21941682

  11. A Giant Warm Baryonic Halo for the Coma Cluster

    NASA Technical Reports Server (NTRS)

    Bonamente, Max; Lieu, Richard; Joy, Marshall K.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Several deep PSPC observations of the Coma cluster unveil a very large-scale halo of soft X-ray emission, substantially in excess of the well know radiation from the hot intra-cluster medium. The excess emission, previously reported in the central cluster regions through lower-sensitivity EUVE and ROSAT data, is now evident out to a radius of 2.5 Mpc, demonstrating that the soft excess radiation from clusters is a phenomenon of cosmological significance. The spectrum at these large radii cannot be modeled non-thermally, but is consistent with the original scenario of thermal emission at warm temperatures. The mass of this plasma is at least on par with that of the hot X-ray emitting plasma, and significantly more massive if the plasma resides in low-density filamentary structures. Thus the data lend vital support to current theories of cosmic evolution, which predict greater than 50 percent by mass of today's baryons reside in warm-hot filaments converging at clusters of galaxies.

  12. A Massive Warm Baryonic Halo in the Coma Cluster

    NASA Technical Reports Server (NTRS)

    Bonamente, Massimiliano; Joy, Marshall K.; Lieu, Richard

    2003-01-01

    Several deep PSPC observations of the Coma Cluster reveal a very large scale halo of soft X-ray emission, substantially in excess of the well-known radiation from the hot intracluster medium. The excess emission, previously reported in the central region of the cluster using lower sensitivity Extreme Ultraviolet Explorer (EUVE) and ROSAT data, is now evident out to a radius of 2.6 Mpc, demonstrating that the soft excess radiation from clusters is a phenomenon of cosmological significance. The X-ray spectrum at these large radii cannot be modeled nonthermally but is consistent with the original scenario of thermal emission from warm gas at approx. 10(exp 6) K. The mass of the warm gas is on par with that of the hot X-ray-emitting plasma and significantly more massive if the warm gas resides in low-density filamentary structures. Thus, the data lend vital support to current theories of cosmic evolution, which predict that at low redshift approx. 30%-40% of the baryons reside in warm filaments converging at clusters of galaxies.

  13. [New research and considerations in managing minimally conscious coma patients].

    PubMed

    Zieger, A

    1998-11-01

    The "Wachkoma", minimally conscious state (synonyms in use: "apallic syndrome", "vegetative state"), is a severe, complex condition arising from brain damage of diverse etiologies, for which definitional consensus does not exist internationally; it gives rise to frequent misdiagnosis and carries substantial insecurities concerning treatment outcomes. In the framework of expanding early rehabilitation, however, recent years have seen a distinct shift away from a defect-oriented, reductionist view towards a relational-medicine based understanding of patients with severe brain damage, seeking to gain a comprehensive perception of the patient's altered physical existence and taking a multidisciplinary--nursing, medical, therapeutic and neuropsychological--perspective which includes the patient's relatives and family. Historically, a transition is under way away from the classical brain-pathology focus toward a neuropsychologically grounded, differentiated perspective. Along with in-depth differential diagnostics and assessment of rehab potentials (early intervention diagnostics), comprehensive intervention measures are initiated as early as possible by an interdisciplinary team. These include "coma stimulation" measures, body language forms of interaction ("dialogue management"), and technical communication devices. By building long-term care assistance in ambulatory and residential service delivery systems ("small social network"), social reintegration of these very severely affected patients is attempted, involving the familial and social resources available. Recurrently raised within the bioethical discourse, demands to consider doctor-assisted dying or food withdrawal are to be rejected from a clinical, medical and social-ethical perspective. PMID:10063504

  14. [Neuroanatomical basis for traumatic coma: clinical and magnetic resonance correlates].

    PubMed

    Potapov, A A; Zakharova, N E; Kornienko, V N; Pronin, I N; Alexandrova, E V; Zaitsev, O S; Likhterman, L B; Gavrilov, A G; Danilov, G V; Oshorov, A V; Sychev, A A; Polupan, A A

    2014-01-01

    In this paper, the relationship between brain lesion localization (verified by magnetic resonance imaging (MRI)) and the severity of traumatic brain injury (TBI) and its outcomes is presented. Magnetic resonance studies in different modes (T1, T2, FLAIR, DWI, DTI, T2 * GRE, SWAN) were performed in 162 patients with acute TBI. Statistical analysis was done using Statistica 6, 8 software and R programming language. A new advanced MRI-based classification of TBI was introduced implying the assessment of hemispheric and brainstem traumatic lesions level and localization. Statistically significant correlations were found between the Glasgow coma and outcome scales scores (p < 0.001), and the proposed MRI grading scale scores, which means a high prognostic value of the new classification. The knowledge of injured brain microanatomy coming from sensitive neuroimaging, in conjunction with the assessment of mechanisms, aggravating factors and clinical manifestation of brain trauma is the basis for the actual predictive model of TBI. The proposed advanced MRI classification contributes to this concept development. PMID:24761591

  15. Designing Aberration-Corrected Solid Unstable Resonators

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1994-01-01

    In improved method of designing solid unstable resonator of laser diode, shapes of mirrors calculated to yield specified mode. Ray tracing used to compute shape of initially unspecified end mirror, given shape of initially specified end mirror and specified output mode. No need to accept aberrations or suboptimal circular shapes, to make iterative design computations in effort to converge on desired mode, or to assume paraxiality of rays: Angles between rays and optical axis large, cross sections of surfaces noncircular, and computed shape of end mirror exact. End mirror corrects for all aberrations.

  16. Seidel aberrations of an inflated membrane.

    PubMed

    Vaughan, H

    1980-09-15

    The Seidel aberrations of a shallow reflecting bowl are examined. In particular the bowl is formed by pressurizing a prestretched polymer membrane over the end of a cylindrical pressure vessel. Precise values for each of the five aberrations are given in terms of the bowl depth, radius, and amount of prestretch in the membrane for the case of an object at infinity and aperture stop in contact with the mirror. The analysis neglects terms of order (4)compared to unity where = bowl depth/bowl radius.

  17. Aberration corrected Lorentz scanning transmission electron microscopy.

    PubMed

    McVitie, S; McGrouther, D; McFadzean, S; MacLaren, D A; O'Shea, K J; Benitez, M J

    2015-05-01

    We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale.

  18. Multinodal fifth-order optical aberrations of optical systems without rotational symmetry: spherical aberration.

    PubMed

    Thompson, Kevin P

    2009-05-01

    Building off an earlier work on multinodal third-order aberrations [J. Opt. Soc. Am. A22, 1389 (2005)], this is the first in a series of papers that derives and illustrates the characteristic multinodal geometry for each of the fifth-order aberrations. Part I (as this paper will be referred to) will present the spherical aberration family: specifically, W(060), W(240M) and W(242), and W(080) (fifth-order spherical, oblique spherical, and seventh-order spherical). Nodal aberration theory is proving to be very effective as both an optical design tool for fully unobscured off-axis telescopes and as an analysis method, particularly in the context of the response of any imaging optical systems to misalignment. It is important to recognize that this multinodal approach to aberration theory is not restricted to small perturbations. The remaining papers in this series will result in a complete presentation of the intrinsic characteristic multinodal properties of each of the fifth-order aberrations. As such, this series provides a definitive theory of the optical aberrations of (nonanamorphic) imaging systems with a circular aperture stop. PMID:19412225

  19. Aberrations of diffracted wave fields. II. Diffraction gratings.

    PubMed

    Mahajan, V N

    2000-12-01

    The Rayleigh-Sommerfeld theory is applied to diffraction of a spherical wave by a grating. The grating equation is obtained from the aberration-free diffraction pattern, and its aberrations are shown to be the same as the conventional aberrations obtained by using Fermat's principle. These aberrations are shown to be not associated with the diffraction process. Moreover, it is shown that the irradiance distribution of a certain diffraction order is the Fraunhofer diffraction pattern of the grating aperture as a whole aberrated by the aberration of that order. PMID:11140481

  20. Aberration averaging using point spread function for scanning projection systems

    NASA Astrophysics Data System (ADS)

    Ooki, Hiroshi; Noda, Tomoya; Matsumoto, Koichi

    2000-07-01

    Scanning projection system plays a leading part in current DUV optical lithography. It is frequently pointed out that the mechanically induced distortion and field curvature degrade image quality after scanning. On the other hand, the aberration of the projection lens is averaged along the scanning direction. This averaging effect reduces the residual aberration significantly. The aberration averaging based on the point spread function and phase retrieval technique in order to estimate the effective wavefront aberration after scanning is described in this paper. Our averaging method is tested using specified wavefront aberration, and its accuracy is discussed based on the measured wavefront aberration of recent Nikon projection lens.

  1. Analysis of focusing error signals by differential astigmatic method under off-center tracking in the land-groove-type optical disk

    NASA Astrophysics Data System (ADS)

    Shinoda, Masahisa; Nakatani, Hidehiko

    2015-04-01

    We theoretically calculate the behavior of the focusing error signal in the land-groove-type optical disk when the objective lens traverses on out of the radius of the optical disk. The differential astigmatic method is employed instead of the conventional astigmatic method for generating the focusing error signals. The signal behaviors are compared and analyzed in terms of the gain difference of the slope sensitivity of the focusing error signals from the land and the groove. In our calculation, the format of digital versatile disc-random access memory (DVD-RAM) is adopted as the land-groove-type optical disk model, and advantageous conditions for suppressing the gain difference are investigated. The calculation method and results described in this paper will be reflected in the next generation land-groove-type optical disks.

  2. Cosmological parameter estimation: impact of CMB aberration

    SciTech Connect

    Catena, Riccardo; Notari, Alessio E-mail: notari@ffn.ub.es

    2013-04-01

    The peculiar motion of an observer with respect to the CMB rest frame induces an apparent deflection of the observed CMB photons, i.e. aberration, and a shift in their frequency, i.e. Doppler effect. Both effects distort the temperature multipoles a{sub lm}'s via a mixing matrix at any l. The common lore when performing a CMB based cosmological parameter estimation is to consider that Doppler affects only the l = 1 multipole, and neglect any other corrections. In this paper we reconsider the validity of this assumption, showing that it is actually not robust when sky cuts are included to model CMB foreground contaminations. Assuming a simple fiducial cosmological model with five parameters, we simulated CMB temperature maps of the sky in a WMAP-like and in a Planck-like experiment and added aberration and Doppler effects to the maps. We then analyzed with a MCMC in a Bayesian framework the maps with and without aberration and Doppler effects in order to assess the ability of reconstructing the parameters of the fiducial model. We find that, depending on the specific realization of the simulated data, the parameters can be biased up to one standard deviation for WMAP and almost two standard deviations for Planck. Therefore we conclude that in general it is not a solid assumption to neglect aberration in a CMB based cosmological parameter estimation.

  3. Aberration features in directional dark matter detection

    SciTech Connect

    Bozorgnia, Nassim; Gelmini, Graciela B.; Gondolo, Paolo E-mail: gelmini@physics.ucla.edu

    2012-08-01

    The motion of the Earth around the Sun causes an annual change in the magnitude and direction of the arrival velocity of dark matter particles on Earth, in a way analogous to aberration of stellar light. In directional detectors, aberration of weakly interacting massive particles (WIMPs) modulates the pattern of nuclear recoil directions in a way that depends on the orbital velocity of the Earth and the local galactic distribution of WIMP velocities. Knowing the former, WIMP aberration can give information on the latter, besides being a curious way of confirming the revolution of the Earth and the extraterrestrial provenance of WIMPs. While observing the full aberration pattern requires extremely large exposures, we claim that the annual variation of the mean recoil direction or of the event counts over specific solid angles may be detectable with moderately large exposures. For example, integrated counts over Galactic hemispheres separated by planes perpendicular to Earth's orbit would modulate annually, resulting in Galactic Hemisphere Annual Modulations (GHAM) with amplitudes larger than the usual non-directional annual modulation.

  4. Anti-forensics of chromatic aberration

    NASA Astrophysics Data System (ADS)

    Mayer, Owen; Stamm, Matthew C.

    2015-03-01

    Over the past decade, a number of information forensic techniques have been developed to identify digital image manipulation and falsification. Recent research has shown, however, that an intelligent forger can use anti-forensic countermeasures to disguise their forgeries. In this paper, an anti-forensic technique is proposed to falsify the lateral chromatic aberration present in a digital image. Lateral chromatic aberration corresponds to the relative contraction or expansion between an image's color channels that occurs due to a lens's inability to focus all wavelengths of light on the same point. Previous work has used localized inconsistencies in an image's chromatic aberration to expose cut-and-paste image forgeries. The anti-forensic technique presented in this paper operates by estimating the expected lateral chromatic aberration at an image location, then removing deviations from this estimate caused by tampering or falsification. Experimental results are presented that demonstrate that our anti-forensic technique can be used to effectively disguise evidence of an image forgery.

  5. Designing refractive beam shapers via aberration theory

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Shealy, David

    2014-10-01

    In this paper, we use aberration theory to design a refractive laser beam shaper in the configuration of two-aspheric lenses, whose analytical equations are known, but rather complicated. Specifically, we use results from third order aberration theory to obtain the parameters of the refracting laser beam shaper from the transverse aberration, which are then used as a starting point for further optimization by using optical design software. This approach was developed during the beginning of the twentieth century, works well for systems with a low numerical aperture, and allows one to define the following parameters of an optical system: radii of curvature, indices of refraction, thicknesses or air gaps, and conic constants of second order aspheric surfaces. We shall consider surfaces of the second-order spherical and conic sections and shall consider the example of designing of a two-lens beam shaper of the Keplerian 1-to-1 telescopic design providing a theoretical flat phase front and a flat-top irradiance profile of the output beam, where the ray mapping function from the input aperture to the output aperture is known from the literature. Explicit expression for third order longitudinal aberration and the Seidel coefficients are expressed in terms beam waist and input beam geometrical parameter, indices, lens radii and conic constants.

  6. Single-Step Transepithelial PRK vs Alcohol-Assisted PRK in Myopia and Compound Myopic Astigmatism Correction.

    PubMed

    Kaluzny, Bartlomiej J; Cieslinska, Iwona; Mosquera, Samuel A; Verma, Shwetabh

    2016-02-01

    Transepithelial photorefractive keratectomy (tPRK), where both the epithelium and stroma are removed in a single-step, is a relatively new procedure of laser refractive error correction. This study compares the 3-month results of myopia and compound myopic astigmatism correction by tPRK or conventional alcohol-assisted PRK (aaPRK).This prospective, nonrandomized, case-control study recruited 148 consecutive patients; 93 underwent tPRK (173 eyes) and 55 aaPRK (103 eyes). Refractive results, predictability, safety, and efficacy were evaluated during the 3-month follow-up. The main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and mean refractive spherical equivalent (MRSE).Mean preoperative MRSE was -4.30 ± 1.72 D and -4.33 ± 1.96 D, respectively (P = 0.87). The 3-month follow-up rate was 82.1% in the tPRK group (n = 145) and 86.4% in aaPRK group (n = 90), P = 0.81. Postoperative UDVA was 20/20 or better in 97% and 94% of eyes, respectively (P = 0.45). In the tPRK and aaPRK groups, respectively, 13% and 21% of eyes lost 1 line of CDVA, and 30% and 31% gained 1 or 2 lines (P = 0.48). Mean postoperative MRSE was -0.14 ± 0.26 D in the tPRK group and -0.12 ± 0.20 D in the aaPRK group (P = 0.9). The correlation between attempted versus achieved MRSE was equally high in both groups.Single-step transepithelial PRK and conventional PRK provide very similar results 3 months postoperatively. These procedures are predictable, effective, and safe for correction of myopia and compound myopic astigmatism.

  7. Efficacy, safety, predictability, aberrations and corneal biomechnical parameters after SMILE and FLEx: Meta-analysis

    PubMed Central

    Ma, Jing; Cao, Nan-Jue; Xia, Li-Kun

    2016-01-01

    AIM To identify possible differences of efficacy, safety, predictability, higher-order aberrations and corneal biomechnical parameters after small-incision lenticule extraction (SMILE) and femtosecond lenticule extraction (FLEx). METHODS A systematic literature retrieval was conducted in Medline, Embase and the Cochrane Library, up to October, 2015. The included studies were subject to a Meta-analysis. Comparison between SMILE and FLEx was measured as pooled odds ratio (OR) or weighted mean differences (WMD). Of 95% confidence intervals (CI) were used to analyze data. RESULTS A total of seven studies were included. Firstly, there were no differences in uncorrected distance visual acuity (UDVA) 20/20 or better (OR, 1.37; 95% CI, 0.69 to 2.69; P=0.37) and logMAR UDVA (WMD, -0.02; 95% CI, -0.05 to 0.01; P=0.17) after SMILE versus FLEx. We found no differences in corrected distance visual acuity (CDVA) unchanged (OR, 0.98; 95% CI, 0.46 to 2.11; P=0.97) and logMAR CDVA (WMD, -0.00; 95% CI, -0.01 to 0.01; P=0.90) either. Secondly, we found no differences in refraction within ±1.00 D (OR, 0.98; 95% CI, 0.13 to 7.28; P=0.99) and ±0.50 D (OR, 1.62; 95% CI, 0.62 to 4.28; P=0.33) of target postoperatively. Thirdly, for higher-order aberrations, we found no differences in the total higher-order aberrations (WMD, -0.04; 95% CI, -0.09 to 0.01; P=0.14), coma (WMD, -0.04; 95% CI, -0.09 to 0.01; P=0.11), spherical (WMD, 0.01; 95% CI, -0.02 to 0.03; P=0.60) and trefoil (WMD, -0.00; 95% CI, -0.04 to 0.03; P=0.76). Furthermore, for corneal biomechanical parameters, we also found no differences (WMD, 0.08; 95% CI, -0.17 to 0.33; P=0.54) after SMILE versus FLEx. CONCLUSION There are no statistically differences in efficacy, safety, predictability, higher-order aberrations and corneal biomechnical parameters postoperative between SMILE and FLEx. PMID:27275436

  8. Concerning the alignment of modern telescopes: theory, practice, and tolerances illustrated by the ESO NTT

    NASA Astrophysics Data System (ADS)

    Wilson, Ray N.; Delabre, Bernard

    1997-01-01

    A recent paper by Bhatia (1995) suggest from calculations based on the optical geometry of the NTT that the zero-coma condition is a necessary but insufficient condition for the alignment of modern telescopes and that analysis of separate decenter effects is necessary to cope with decentering astigmatism aberrations near the field c enter. We show here that, while Bhatia's calculations are quite correct, their basis shows a misunderstanding of how the NTT was actually aligned and that this "passive" alignment was sufficiently good that the decentering astigmatism effects he indicates were negligible. More dangerous are the wide-field effects of decentering astigmatism discussed by McLeod (1996). However, we show that these effects, linear with field, are also negligible with the NTT alignment quality achieved, provided the correct effective shift of the astigmatic field center is allowed for int he active correction software. This is of great importance in the NTT because the image analyser operates at the edge of the field and the correct field astigmatism must be subtracted to give the necessary active correction at the mechanical field center. This approach is valid for the technical use of the edge field of an aplanatic (RC) telescope limited by field astigmatism. Decentering astigmatism will be much more critical at the field edge for anastigmatic telescopes is a wide field is also used for astronomical observation. (SECTION: Astronomical Instrumentation)

  9. Aberration sensitivity of unstable resonator with semitransparent output coupler

    SciTech Connect

    Mikheyev, P.A.; Shepelenko, A.A.; Zaikin, A.P.

    1994-12-31

    Unstable resonator with semitransparent output coupler is feasible for lasers with moderate gain and large cross section of active medium. The resonator fundamental mode can be obtained up to Fresnel numbers of 10 or more. Output beam quality does not differ much from the Gaussian beam, but at the same time intensity distribution is rather flat and mode-medium coupling is better. This approach does not require the mirrors with tapered reflectivity profile. In practice the design of this type of resonator often requires to place a spherical mirror inside to fold the optical path and that inevitably causes astigmatism. Current presentation describes the results of the investigation of resonator sensitivity to intracavity astigmatism. The requirements for the resonator setup to obtain nearly unperturbed fundamental mode operation, and a convenient resonator design to meet this requirements are discussed.

  10. ALMA observations of gas and dust in the coma of comet C/2012 S1 (ISON)

    NASA Astrophysics Data System (ADS)

    Cordiner, M.; Remijan, A.; Milam, S.; Mumma, M.; Charnley, S.; Paganini, L.; Boissier, J.; Villanueva, G.; Bockelee-Morvan, D.; Biver, N.; Kuan, Y.; Lis, D.; Crovisier, J.; Coulson, I.; Minniti, D.

    2014-07-01

    Ground-based studies of cometary comae provide indirect information on the compositions of the nuclear ices, and thus provide insight into the physical and chemical conditions of the early solar nebula. To realize the full potential of gas-phase coma observations as probes of solar-system evolution requires a complete understanding of the gas-release mechanisms. However, previous observations have been unable to ascertain the precise origins of fundamental coma species including H_2CO, HCN, and HNC, and details regarding the possible formation of these species in the coma are not well understood. Here, we present spatially and spectrally-resolved ALMA sub-mm images of the distributions of HCN, HNC, CH_3OH, H_2CO, and dust in the coma of comet C/2012 S1 (ISON), observed during the outburst event on November 15-17 (at r_H = 0.54-0.61 au and Δ = 0.9 au). Our observations reveal an unprecedented level of detail in the distributions of these fundamental coma constituents, and permit accurate measurement of their origins in the coma. Observations were made using ALMA Band 7 in Cycle 1 (Early Science) mode in the frequency range 339-364 GHz, with 25-29 12-m antennae. Weather conditions were excellent, with good atmospheric phase stability and low precipitable water vapor (0.5-0.8 mm at zenith). The spatial resolution was 0.4-0.8'' (with maximum recoverable angular scales approx. 5-10''), and the spectral resolution was 0.4 km s^{-1}. The ALMA image cubes show kinematically and spatially-resolved structures in HCN, HNC, CH_3OH, and H_2CO emission. Whereas the CH_3OH and HCN distributions are consistent with release from (or within 100 km of) the nucleus, the H_2CO data indicate coma release from a parent species with scale-length on the order of a few hundred km. The HNC distribution suggests release in clumpy, collimated outflows possibly as a result of the breakdown of a macromolecular/dust precursor. Clear 0.9-mm continuum emission was detected, showing a sharp central

  11. Aberration analysis of the putative projector for Lorenzo Lotto's Husband and wife: image analysis through computer ray-tracing

    NASA Astrophysics Data System (ADS)

    Robinson, Dirk; Stork, David G.

    2008-02-01

    A recent theory claims that the late-Italian Renaissance painter Lorenzo Lotto secretly built a concave-mirror projector to project an image of a carpet onto his canvas and trace it during the execution of Husband and wife (c. 1543). Key evidence adduced to support this claim includes "perspective anomalies" and changes in "magnification" that the theory's proponents ascribe to Lotto refocusing his projector to overcome its limitations in depth of field. We find, though, that there are important geometrical constraints upon such a putative optical projector not incorporated into the proponents' analyses, and that when properly included, the argument for the use of optics loses its force. We used Zemax optical design software to create a simple model of Lotto's studio and putative projector, and incorporated the optical properties proponents inferred from geometrical properties of the depicted carpet. Our central contribution derives from including the 116-cm-wide canvas screen; we found that this screen forces the incident light to strike the concave mirror at large angles (>= 15°) and that this, in turn, means that the projected image would reveal severe off-axis aberrations, particularly astigmatism. Such aberrations are roughly as severe as the defocus blur claimed to have led Lotto to refocus the projector. In short, we find that the projected images would not have gone in and out of focus in the way claimed by proponents, a result that undercuts their claim that Lotto used a projector for this painting. We speculate on the value of further uses of sophisticated ray-tracing analyses in the study of fine arts.

  12. Abundant molecular oxygen in the coma of comet 67P/Churyumov-Gerasimenko.

    PubMed

    Bieler, A; Altwegg, K; Balsiger, H; Bar-Nun, A; Berthelier, J-J; Bochsler, P; Briois, C; Calmonte, U; Combi, M; De Keyser, J; van Dishoeck, E F; Fiethe, B; Fuselier, S A; Gasc, S; Gombosi, T I; Hansen, K C; Hässig, M; Jäckel, A; Kopp, E; Korth, A; Le Roy, L; Mall, U; Maggiolo, R; Marty, B; Mousis, O; Owen, T; Rème, H; Rubin, M; Sémon, T; Tzou, C-Y; Waite, J H; Walsh, C; Wurz, P

    2015-10-29

    The composition of the neutral gas comas of most comets is dominated by H2O, CO and CO2, typically comprising as much as 95 per cent of the total gas density. In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen (O2), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn, has remained undetected in cometary comas. Here we report in situ measurement of O2 in the coma of comet 67P/Churyumov-Gerasimenko, with local abundances ranging from one per cent to ten per cent relative to H2O and with a mean value of 3.80 ± 0.85 per cent. Our observations indicate that the O2/H2O ratio is isotropic in the coma and does not change systematically with heliocentric distance. This suggests that primordial O2 was incorporated into the nucleus during the comet's formation, which is unexpected given the low upper limits from remote sensing observations. Current Solar System formation models do not predict conditions that would allow this to occur. PMID:26511578

  13. Dark energy and the structure of the Coma cluster of galaxies

    NASA Astrophysics Data System (ADS)

    Chernin, A. D.; Bisnovatyi-Kogan, G. S.; Teerikorpi, P.; Valtonen, M. J.; Byrd, G. G.; Merafina, M.

    2013-05-01

    Context. We consider the Coma cluster of galaxies as a gravitationally bound physical system embedded in the perfectly uniform static dark energy background as implied by ΛCDM cosmology. Aims: We ask if the density of dark energy is high enough to affect the structure of a large and rich cluster of galaxies. Methods: We base our work on recent observational data on the Coma cluster, and apply our theory of local dynamical effects of dark energy, including the zero-gravity radius RZG of the local force field as the key parameter. Results: 1) Three masses are defined that characterize the structure of a regular cluster: the matter mass MM, the dark-energy effective mass MDE (<0), and the gravitating mass MG (=MM + MDE). 2) A new matter-density profile is suggested that reproduces the observational data well for the Coma cluster in the radius range from 1.4 Mpc to 14 Mpc and takes the dark energy background into account. 3) Using this profile, we calculate upper limits for the total size of the Coma cluster, R ≤ RZG ≈ 20 Mpc, and its total matter mass, MM ≲ MM(RZG) = 6.2 × 1015 M⊙. Conclusions: The dark energy antigravity affects the structure of the Coma cluster strongly at large radii R ≳ 14 Mpc and should be considered when its total mass is derived.

  14. The distribution of early- and late-type galaxies in the Coma cluster

    NASA Technical Reports Server (NTRS)

    Doi, M.; Fukugita, M.; Okamura, S.; Turner, E. L.

    1995-01-01

    The spatial distribution and the morohology-density relation of Coma cluster galaxies are studied using a new homogeneous photmetric sample of 450 galaxies down to B = 16.0 mag with quantitative morphology classification. The sample covers a wide area (10 deg X 10 deg), extending well beyond the Coma cluster. Morphological classifications into early- (E+SO) and late-(S) type galaxies are made by an automated algorithm using simple photometric parameters, with which the misclassification rate is expected to be approximately 10% with respect to early and late types given in the Third Reference Catalogue of Bright Galaxies. The flattened distribution of Coma cluster galaxies, as noted in previous studies, is most conspicuously seen if the early-type galaxies are selected. Early-type galaxies are distributed in a thick filament extended from the NE to the WSW direction that delineates a part of large-scale structure. Spiral galaxies show a distribution with a modest density gradient toward the cluster center; at least bright spiral galaxies are present close to the center of the Coma cluster. We also examine the morphology-density relation for the Coma cluster including its surrounding regions.

  15. THE SPATIAL DISTRIBUTION OF OH AND CN RADICALS IN THE COMA OF COMET ENCKE

    SciTech Connect

    Ihalawela, Chandrasiri A.; Pierce, Donna M.; Dorman, Garrett R.; Cochran, Anita L. E-mail: ci856509@ohio.edu E-mail: grd33@msstate.edu

    2011-11-10

    Multiple potential parent species have been proposed to explain CN abundances in comet comae, but the parent has not been definitively identified for all comets. This study examines the spatial distribution of CN radicals in the coma of comet Encke and determines the likelihood that CN is a photodissociative daughter of HCN in the coma. Comet Encke is the shortest orbital period (3.3 years) comet known and also has a low dust-to-gas ratio based on optical observations. Observations of CN were obtained from 2003 October 22 to 24, using the 2.7 m telescope at McDonald Observatory. To determine the parent of CN, the classical vectorial model was modified by using a cone shape in order to reproduce Encke's highly aspherical and asymmetric coma. To test the robustness of the modified model, the spatial distribution of OH was also modeled. This also allowed us to obtain CN/OH ratios in the coma. Overall, we find the CN/OH ratio to be 0.009 {+-} 0.004. The results are consistent with HCN being the photodissociative parent of CN, but we cannot completely rule out other possible parents such as CH{sub 3}CN and HC{sub 3}N. We also found that the fan-like feature spans {approx}90 Degree-Sign , consistent with the results of Woodney et al..

  16. Incidence, aetiology, and outcome of non-traumatic coma: a population based study

    PubMed Central

    Wong, C; Forsyth, R; Kelly, T; Eyre, J

    2001-01-01

    AIM—To determine the incidence, presentation, aetiology, and outcome of non-traumatic coma in children aged between 1 month and 16years.
METHODS—In this prospective, population based, epidemiological study in the former Northern NHS region of the UK, cases were notified following any hospital admission or community death associated with non-traumatic coma. Coma was defined as a Glasgow Coma Score below 12 for more than six hours.
RESULTS—The incidence of non-traumatic coma was 30.8 per 100 000 children under 16 per year (6.0 per 100 000 general population per year). The age specific incidence was notably higher in the first year of life (160 per 100 000 children per year). CNS specific presentations became commoner with increasing age. In infants, nearly two thirds of presentations were with non-specific, systemic signs. Infection was the commonest overall aetiology. Aetiology remained unknown in 14% despite extensive investigation and/or autopsy. Mortality was highly dependent on aetiology, with aetiology specific mortality rates varying from 3% to 84%. With follow up to approximately 12 months, overall series mortality was 46%.

 PMID:11207161

  17. Abundant molecular oxygen in the coma of comet 67P/Churyumov-Gerasimenko.

    PubMed

    Bieler, A; Altwegg, K; Balsiger, H; Bar-Nun, A; Berthelier, J-J; Bochsler, P; Briois, C; Calmonte, U; Combi, M; De Keyser, J; van Dishoeck, E F; Fiethe, B; Fuselier, S A; Gasc, S; Gombosi, T I; Hansen, K C; Hässig, M; Jäckel, A; Kopp, E; Korth, A; Le Roy, L; Mall, U; Maggiolo, R; Marty, B; Mousis, O; Owen, T; Rème, H; Rubin, M; Sémon, T; Tzou, C-Y; Waite, J H; Walsh, C; Wurz, P

    2015-10-29

    The composition of the neutral gas comas of most comets is dominated by H2O, CO and CO2, typically comprising as much as 95 per cent of the total gas density. In addition, cometary comas have been found to contain a rich array of other molecules, including sulfuric compounds and complex hydrocarbons. Molecular oxygen (O2), however, despite its detection on other icy bodies such as the moons of Jupiter and Saturn, has remained undetected in cometary comas. Here we report in situ measurement of O2 in the coma of comet 67P/Churyumov-Gerasimenko, with local abundances ranging from one per cent to ten per cent relative to H2O and with a mean value of 3.80 ± 0.85 per cent. Our observations indicate that the O2/H2O ratio is isotropic in the coma and does not change systematically with heliocentric distance. This suggests that primordial O2 was incorporated into the nucleus during the comet's formation, which is unexpected given the low upper limits from remote sensing observations. Current Solar System formation models do not predict conditions that would allow this to occur.

  18. Hard X-ray Spectroscopy and Imaging by a Reflection Zone Plate in the Presence of Astigmatism

    SciTech Connect

    Braig, Christoph; Lochel, Heike; Hafner, Aljosa; Firsov, Alexander; Rehanek, Jens; Brzhezinskaya, Maria; Wojcik, Michael; Macrander, Albert; Assoufid, Lahsen; Erko, Alexei

    2016-01-01

    The feasibility of an off-axis x-ray reflection zone plate to perform wavelength-dispersive spectroscopy, on-axis point focusing, and two-dimensional imaging is demonstrated by means of one and the same diffractive optical element (DOE) at a synchrotron radiation facility. The resolving power varies between 3×101 and 4×102 in the range of 7.6 keV to 9.0 keV, with its maximum at the design energy of 8.3 keV. This result is verified using an adjustable entrance slit, by which horizontal (H) and vertical (V) focusing to 0.85 μm(H) and 1.29 μm(V) is obtained near the sagittal focal plane of the astigmatic configuration. An angular and axial scan proves an accessible field of view of at least 0.6 arcmin × 0.8 arcmin and a focal depth of ±0.86 mm. Supported by the grating efficiency of around 17.5% and a very short pulse elongation, future precision x-ray fluorescence and absorption studies of transition metals at their K-edge on an ultrashort timescale could benefit from our findings.

  19. Q-value customized ablation (custom-Q) versus wavefront optimized ablation for primary myopia and myopic astigmatism.

    PubMed

    Tawfik, Ahmed; Eid, Ahmed Mostafa; Hasanen, Rabei; Moftah, Ismail A N

    2014-04-01

    Comparison between treatment with wavefront optimized and custom-Q laser-assisted in situ keratomileusis (LASIK) ablations. Our study included 400 eyes of 200 patients divided into two equal groups. All patients were treated for myopia and myopic astigmatism with LASIK. The first group was treated with wavefront optimized ablation and the second group with custom-Q ablation. They were examined preoperatively and postoperatively to assess asphericity, image quality, and other classical outcome parameters. The wavefront optimized ablation group comprised 200 eyes with a mean spherical equivalent refraction (SE) of -5.2188 diopters (D) (range: -1.15 to -10.50 D); the mean Q-value changed from 0.30 preoperatively to 0.06 postoperatively. The custom-Q ablation group also comprised 200 eyes with a mean SE of -5.1575 D (range: -1.35 to -9.00 D); the mean Q-value changed from 0.32 preoperatively to 0.03 postoperatively. A statistically significant difference in postoperative change in Q-values (P = 0.02) and in postoperative visual acuity (P = 0.42) between the two groups was noted. There was no difference between the two groups regarding refractive correction. There was a marginally significant change in BSCVA (best spectacle-corrected visual acuity) between the two groups, and less impairment in the corneal asphericity in the custom-Q group.

  20. Genome-wide association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the CREAM consortium.

    PubMed

    Li, Qing; Wojciechowski, Robert; Simpson, Claire L; Hysi, Pirro G; Verhoeven, Virginie J M; Ikram, Mohammad Kamran; Höhn, René; Vitart, Veronique; Hewitt, Alex W; Oexle, Konrad; Mäkelä, Kari-Matti; MacGregor, Stuart; Pirastu, Mario; Fan, Qiao; Cheng, Ching-Yu; St Pourcain, Beaté; McMahon, George; Kemp, John P; Northstone, Kate; Rahi, Jugnoo S; Cumberland, Phillippa M; Martin, Nicholas G; Sanfilippo, Paul G; Lu, Yi; Wang, Ya Xing; Hayward, Caroline; Polašek, Ozren; Campbell, Harry; Bencic, Goran; Wright, Alan F; Wedenoja, Juho; Zeller, Tanja; Schillert, Arne; Mirshahi, Alireza; Lackner, Karl; Yip, Shea Ping; Yap, Maurice K H; Ried, Janina S; Gieger, Christian; Murgia, Federico; Wilson, James F; Fleck, Brian; Yazar, Seyhan; Vingerling, Johannes R; Hofman, Albert; Uitterlinden, André; Rivadeneira, Fernando; Amin, Najaf; Karssen, Lennart; Oostra, Ben A; Zhou, Xin; Teo, Yik-Ying; Tai, E Shyong; Vithana, Eranga; Barathi, Veluchamy; Zheng, Yingfeng; Siantar, Rosalynn Grace; Neelam, Kumari; Shin, Youchan; Lam, Janice; Yonova-Doing, Ekaterina; Venturini, Cristina; Hosseini, S Mohsen; Wong, Hoi-Suen; Lehtimäki, Terho; Kähönen, Mika; Raitakari, Olli; Timpson, Nicholas J; Evans, David M; Khor, Chiea-Chuen; Aung, Tin; Young, Terri L; Mitchell, Paul; Klein, Barbara; van Duijn, Cornelia M; Meitinger, Thomas; Jonas, Jost B; Baird, Paul N; Mackey, David A; Wong, Tien Yin; Saw, Seang-Mei; Pärssinen, Olavi; Stambolian, Dwight; Hammond, Christopher J; Klaver, Caroline C W; Williams, Cathy; Paterson, Andrew D; Bailey-Wilson, Joan E; Guggenheim, Jeremy A

    2015-02-01

    To identify genetic variants associated with refractive astigmatism in the general population, meta-analyses of genome-wide association studies were performed for: White Europeans aged at least 25 years (20 cohorts, N = 31,968); Asian subjects aged at least 25 years (7 cohorts, N = 9,295); White Europeans aged <25 years (4 cohorts, N = 5,640); and all independent individuals from the above three samples combined with a sample of Chinese subjects aged <25 years (N = 45,931). Participants were classified as cases with refractive astigmatism if the average cylinder power in their two eyes was at least 1.00 diopter and as controls otherwise. Genome-wide association analysis was carried out for each cohort separately using logistic regression. Meta-analysis was conducted using a fixed effects model. In the older European group the most strongly associated marker was downstream of the neurexin-1 (NRXN1) gene (rs1401327, P = 3.92E-8). No other region reached genome-wide significance, and association signals were lower for the younger European group and Asian group. In the meta-analysis of all cohorts, no marker reached genome-wide significance: The most strongly associated regions were, NRXN1 (rs1401327, P = 2.93E-07), TOX (rs7823467, P = 3.47E-07) and LINC00340 (rs12212674, P = 1.49E-06). For 34 markers identified in prior GWAS for spherical equivalent refractive error, the beta coefficients for genotype versus spherical equivalent, and genotype versus refractive astigmatism, were highly correlated (r = -0.59, P = 2.10E-04). This work revealed no consistent or strong genetic signals for refractive astigmatism; however, the TOX gene region previously identified in GWAS for spherical equivalent refractive error was the second most strongly associated region. Analysis of additional markers provided evidence supporting widespread genetic co-susceptibility for spherical and astigmatic refractive errors.

  1. Understanding and managing coma stimulation: are we doing everything we can?

    PubMed

    Gerber, Carolyn S

    2005-01-01

    The incidence of people surviving with traumatic brain injury is rising at a remarkable pace. Unfortunately, patients also experience some form of coma and significant deficits (ie, cognitive, functional, etc). The focus is shifting from saving these patients to trying to figure out what else can be done for them? In the past, patients were medically maintained, stabilized, and then sent to rehabilitation centers for coma stimulation, in the hope of waking up their reticular activating system. Today, healthcare professionals are being encouraged to research and explore the possibility of implementing structured coma stimulation programs as early as 72 hours postinjury in the intensive care unit. Starting early is of paramount importance to a patient's survival, quality of life, and overall long-term prognosis. The goal of this article is to educate healthcare professionals (in the hospital setting) about managing and implementing structured sensory stimulation sessions. PMID:15875441

  2. ALP conversion and the soft X-ray excess in the outskirts of the Coma cluster

    SciTech Connect

    Kraljic, David; Rummel, Markus; Conlon, Joseph P. E-mail: Markus.Rummel@physics.ox.ac.uk

    2015-01-01

    It was recently found that the soft X-ray excess in the center of the Coma cluster can be fitted by conversion of axion-like-particles (ALPs) of a cosmic axion background (CAB) to photons. We extend this analysis to the outskirts of Coma, including regions up to 5 Mpc from the center of the cluster. We extract the excess soft X-ray flux from ROSAT All-Sky Survey data and compare it to the expected flux from ALP to photon conversion of a CAB. The soft X-ray excess both in the center and the outskirts of Coma can be simultaneously fitted by ALP to photon conversion of a CAB. Given the uncertainties of the cluster magnetic field in the outskirts we constrain the parameter space of the CAB. In particular, an upper limit on the CAB mean energy and a range of allowed ALP-photon couplings are derived.

  3. Dust counter and mass analyser (DUCMA) measurements of comet Halley's coma from Vega spacecraft

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Tuzzolino, A. J.; Perkins, M. A.; Sagdeev, R. Z.; Ksanfomaliti, L. V.

    1986-01-01

    Measurements of dust particles in comet Halley's coma from Vega spacecraft made with instruments using a new principle of dust detection and having a high time resolution over a large range of dust fluxes and masses are reported. The dust coma, whether quiescent (as seen by Vega 2) or containing a major jet structure, (as seen by Vega 1) displays large, short-term variations throughout which are at times quasi-periodic. The integral mass spectra increase in intensity to the lowest masses measured, and the flux levels lie approximately in the ranges estimated previously from ground-based observations. The coma is highly dynamical on all spatial and temporal scales, suggesting a complex structure of localized regions of dust emission from the nucleus.

  4. Dwarf galaxies in the coma cluster: Star formation properties and evolution

    NASA Astrophysics Data System (ADS)

    Hammer, Derek M.

    The infall regions of galaxy clusters are unique laboratories for studying the impact of environment on galaxy evolution. This intermediate region links the low-density field environment and the dense core of the cluster, and is thought to host recently accreted galaxies whose star formation is being quenched by external processes associated with the cluster. In this dissertation, we measure the star formation properties of galaxies at the infall region of the nearby rich cluster of galaxies, Coma. We rely primarily on Ultraviolet (UV) data owing to its sensitivity to recent star formation and we place more emphasis on the properties of dwarf galaxies. Dwarf galaxies are good tracers of external processes in clusters but their evolution is poorly constrained as they are intrinsically faint and hence more challenging to detect. We make use of deep GALEX far-UV and near-UV observations at the infall region of the Coma cluster. This area of the cluster has supporting photometric coverage at optical and IR wavelengths in addition to optical spectroscopic data that includes deep redshift coverage of dwarf galaxies in Coma. Our GALEX observations were the deepest exposures taken for a local galaxy cluster. The depth of these images required alternative data analysis techniques to overcome systematic effects that limit the default GALEX pipeline analysis. Specifically, we used a deblending method that improved detection efficiency by a factor of ˜2 and allowed reliable photometry a few magnitudes deeper than the pipeline catalog. We performed deep measurements of the total UV galaxy counts in our field that were used to measure the source confusion limit for crowded GALEX fields. The star formation properties of Coma members were studied for galaxies that span from starbursts to passive galaxies. Star-forming galaxies in Coma tend to have lower specific star formation rates, on average, as compared to field galaxies. We show that the majority of these galaxies are likely

  5. Successful steroid treatment of coma induced by severe spontaneous intracranial hypotension

    PubMed Central

    Goto, Shunsaku; Ohshima, Tomotaka; Yamamoto, Taiki; Shimato, Shinji; Nishizawa, Toshihisa; Kato, Kyozo

    2016-01-01

    ABSTRACT Spontaneous intracranial hypotension (SIH) is a syndrome characterized by low cerebrospinal fluid (CSF) pressure and postural headaches. It is a rare condition which may sometimes present with severe symptoms such as stupor or coma. The standard treatment protocol includes conservative measures such as bed rest, hydration, and steroids. However, severe cases may require invasive measures such as epidural blood patch (EBP), continuous epidural saline infusion, epidural fibrin glue, or surgical repair of the dural defect. In this report, we describe a case of severe SIH resulting in coma that exhibited dramatic improvement on intravenous administration of steroids. This is the first report of severe SIH causing coma that was treated non-invasively by steroids only. PMID:27303109

  6. Successful steroid treatment of coma induced by severe spontaneous intracranial hypotension.

    PubMed

    Goto, Shunsaku; Ohshima, Tomotaka; Yamamoto, Taiki; Shimato, Shinji; Nishizawa, Toshihisa; Kato, Kyozo

    2016-05-01

    Spontaneous intracranial hypotension (SIH) is a syndrome characterized by low cerebrospinal fluid (CSF) pressure and postural headaches. It is a rare condition which may sometimes present with severe symptoms such as stupor or coma. The standard treatment protocol includes conservative measures such as bed rest, hydration, and steroids. However, severe cases may require invasive measures such as epidural blood patch (EBP), continuous epidural saline infusion, epidural fibrin glue, or surgical repair of the dural defect. In this report, we describe a case of severe SIH resulting in coma that exhibited dramatic improvement on intravenous administration of steroids. This is the first report of severe SIH causing coma that was treated non-invasively by steroids only. PMID:27303109

  7. Chameleonic contribution to the Sunyaev-Zel'dovich radial profile of the Coma cluster

    NASA Astrophysics Data System (ADS)

    Davis, Anne-Christine; Schelpe, Camilla A. O.; Shaw, Douglas J.

    2011-02-01

    We constrain the chameleonic Sunyaev-Zel’dovich (CSZ) effect in the Coma cluster from measurements of the Coma radial profile presented in the WMAP 7-year results. The CSZ effect arises from the interaction of a scalar (or pseudoscalar) particle with the cosmic microwave background in the magnetic field of galaxy clusters. We combine this radial profile data with SZ measurements towards the center of the Coma cluster in different frequency bands, to find ΔTSZ,RJ(0)=-410±50μK and ΔTCSZ204GHz(0)≳-50μK (at 95% confidence) for the thermal SZ and CSZ effects in the cluster, respectively. This leads to an estimated bound on the photon to scalar (or pseudoscalar) coupling strength of geff≲(8.3-37.6)×10-10GeV-1.

  8. Chameleonic contribution to the Sunyaev-Zel'dovich radial profile of the Coma cluster

    SciTech Connect

    Davis, Anne-Christine; Schelpe, Camilla A. O.; Shaw, Douglas J.

    2011-02-15

    We constrain the chameleonic Sunyaev-Zel'dovich (CSZ) effect in the Coma cluster from measurements of the Coma radial profile presented in the WMAP 7-year results. The CSZ effect arises from the interaction of a scalar (or pseudoscalar) particle with the cosmic microwave background in the magnetic field of galaxy clusters. We combine this radial profile data with SZ measurements towards the center of the Coma cluster in different frequency bands, to find {Delta}T{sub SZ,RJ}(0)=-410{+-}50 {mu}K and {Delta}T{sub CSZ}{sup 204} {sup GHz}(0) > or approx. -50 {mu}K (at 95% confidence) for the thermal SZ and CSZ effects in the cluster, respectively. This leads to an estimated bound on the photon to scalar (or pseudoscalar) coupling strength of g{sub eff} < or approx. (8.3-37.6)x10{sup -10} GeV{sup -1}.

  9. Results from the worldwide coma morphology campaign for comet ISON (C/2012 S1)

    NASA Astrophysics Data System (ADS)

    Samarasinha, Nalin H.; Mueller, Beatrice E. A.; Knight, Matthew M.; Farnham, Tony L.; Briol, John; Brosch, Noah; Caruso, John; Gao, Xing; Gomez, Edward; Lister, Tim; Hergenrother, Carl; Hoban, Susan; Prouty, Roy; Holloway, Mike; Howes, Nick; Guido, Ernesto; Hui, Man-To; Jones, Joseph H.; Penland, Tyler B.; Thomas, Samuel R.; Wyrosdick, Jim; Kiselev, Nikolai; Ivanova, Aleksandra V.; Kaye, Thomas G.; Eluo, Jean-Baptist Kikwaya; Lau, Betty P. S.; Lin, Zhong-Yi; Martin, José Luis; Moskvitin, Alexander S.; Nicolini, Martino; Ottum, Brian D.; Pruzenski, Chris; Vogel, David C.; Kellett, Leo; Rapson, Valerie; Schmid, Joel; Doyle, Brandon; Dimino, Frank; Carlino, Stephanie; Safonova, Margarita; Murthy, Jayant; Sutaria, Firoza; Schleicher, David G.; Snodgrass, Colin; Tezcan, Cihan T.; Yorukoglu, Onur; Trowbridge, David; Whitmer, Dennis; Ye, Quan-Zhi

    2015-12-01

    We present the results of a global coma morphology campaign for comet C/2012 S1 (ISON), which was organized to involve both professional and amateur observers. In response to the campaign, many hundreds of images, from nearly two dozen groups were collected. Images were taken primarily in the continuum, which help to characterize the behavior of dust in the coma of comet ISON. The campaign received images from January 12 through November 22, 2013 (an interval over which the heliocentric distance decreased from 5.1 AU to 0.35 AU), allowing monitoring of the long-term evolution of coma morphology during comet ISON's pre-perihelion leg. Data were contributed by observers spread around the world, resulting in particularly good temporal coverage during November when comet ISON was brightest but its visibility was limited from any one location due to the small solar elongation. We analyze the northwestern sunward continuum coma feature observed in comet ISON during the first half of 2013, finding that it was likely present from at least February through May and did not show variations on diurnal time scales. From these images we constrain the grain velocities to ~10 m s-1, and we find that the grains spent 2-4 weeks in the sunward side prior to merging with the dust tail. We present a rationale for the lack of continuum coma features from September until mid-November 2013, determining that if the feature from the first half of 2013 was present, it was likely too small to be clearly detected. We also analyze the continuum coma morphology observed subsequent to the November 12 outburst, and constrain the first appearance of new features in the continuum to later than November 13.99 UT.

  10. Deep Ultraviolet Luminosity Functions at the Infall Region of the Coma Cluster

    NASA Astrophysics Data System (ADS)

    Hammer, D. M.; Hornschemeier, A. E.; Salim, S.; Smith, R.; Jenkins, L.; Mobasher, B.; Miller, N.; Ferguson, H.

    2012-02-01

    We have used deep GALEX observations at the infall region of the Coma cluster to measure the faintest ultraviolet (UV) luminosity functions (LFs) presented for a rich galaxy cluster thus far. The Coma UV LFs are measured to M UV = -10.5 in the GALEX FUV and NUV bands, or 3.5 mag fainter than previous studies, and reach the dwarf early-type galaxy population in Coma for the first time. The Schechter faint-end slopes (α ≈ -1.39 in both GALEX bands) are shallower than reported in previous Coma UV LF studies owing to a flatter LF at faint magnitudes. A Gaussian-plus-Schechter model provides a slightly better parameterization of the UV LFs resulting in a faint-end slope of α ≈ -1.15 in both GALEX bands. The two-component model gives faint-end slopes shallower than α = -1 (a turnover) for the LFs constructed separately for passive and star-forming galaxies. The UV LFs for star-forming galaxies show a turnover at M UV ≈ -14 owing to a deficit of dwarf star-forming galaxies in Coma with stellar masses below M * = 108 M ⊙. A similar turnover is identified in recent UV LFs measured for the Virgo cluster suggesting this may be a common feature of local galaxy clusters, whereas the field UV LFs continue to rise at faint magnitudes. We did not identify an excess of passive galaxies as would be expected if the missing dwarf star-forming galaxies were quenched inside the cluster. In fact, the LFs for both dwarf passive and star-forming galaxies show the same turnover at faint magnitudes. We discuss the possible origin of the missing dwarf star-forming galaxies in Coma and their expected properties based on comparisons to local field galaxies.

  11. Deep UV Luminosity Functions at the Infall Region of the Coma Cluster

    NASA Technical Reports Server (NTRS)

    Hammer, D. M.; Hornschemeier, A. E.; Salim, S.; Smith, R.; Jenkins, L.; Mobasher, B.; Miller, N.; Ferguson, H.

    2011-01-01

    We have used deep GALEX observations at the infall region of the Coma cluster to measure the faintest UV luminosity functions (LFs) presented for a rich galaxy cluster thus far. The Coma UV LFs are measured to M(sub uv) = -10.5 in the GALEX FUV and NUV bands, or 3.5 mag fainter than previous studies, and reach the dwarf early-type galaxy population in Coma for the first time. The Schechter faint-end slopes (alpha approximately equal to -1.39 in both GALEX bands) are shallower than reported in previous Coma UV LF studies owing to a flatter LF at faint magnitudes. A Gaussian-plus-Schechter model provides a slightly better parametrization of the UV LFs resulting in a faint-end slope of alpha approximately equal to -1.15 in both GALEX bands. The two-component model gives faint-end slopes shallower than alpha = -1 (a turnover) for the LFs constructed separately for passive and star forming galaxies. The UV LFs for star forming galaxies show a turnover at M(sub UV) approximately equal to -14 owing to a deficit of dwarf star forming galaxies in Coma with stellar masses below M(sub *) = 10(sup 8) solar mass. A similar turnover is identified in recent UV LFs measured for the Virgo cluster suggesting this may be a common feature of local galaxy clusters, whereas the field UV LFs continue to rise at faint magnitudes. We did not identify an excess of passive galaxies as would be expected if the missing dwarf star forming galaxies were quenched inside the cluster. In fact, the LFs for both dwarf passive and star forming galaxies show the same turnover at faint magnitudes. We discuss the possible origin of the missing dwarf star forming galaxies in Coma and their expected properties based on comparisons to local field galaxies.

  12. Prognosis of patients in coma after acute subdural hematoma due to ruptured intracranial aneurysm.

    PubMed

    Torné, Ramon; Rodríguez-Hernández, Ana; Romero-Chala, Fabián; Arikan, Fuat; Vilalta, Jordi; Sahuquillo, Juan

    2016-04-01

    Acute subdural hematomas (aSDH) secondary to intracranial aneurysm rupture are rare. Most patients present with coma and their functional prognosis has been classically considered to be very poor. Previous studies mixed good-grade and poor-grade patients and reported variable outcomes. We reviewed our experience by focusing on patients in coma only and hypothesized that aSDH might worsen initial mortality but not long-term functional outcome. Between 2005 and 2013, 440 subarachnoid hemorrhage (SAH) patients were admitted to our center. Nineteen (4.3%) were found to have an associated aSDH and 13 (2.9%) of these presented with coma. Their prospectively collected clinical and outcome data were reviewed and compared with that of 104 SAH patients without aSDH who presented with coma during the same period. Median aSDH thickness was 10mm. Four patients presented with an associated aneurysmal cortical laceration and only one had good recovery. Overall, we observed good long-term outcomes in both SAH patients in coma with aSDH and those without aSDH (38.5% versus 26.4%). Associated aSDH does not appear to indicate a poorer long-term functional prognosis in SAH patients presenting with coma. Anisocoria and brain herniation are observed in patients with aSDH thicknesses that are smaller than those observed in trauma patients. Despite a high initial mortality, early surgery to remove the aSDH results in a good outcome in over 60% of survivors. Aneurysmal cortical laceration appears to be an independent entity which shows a poorer prognosis than other types of aneurysmal aSDH.

  13. A challenging case due to uncommon aberrancies.

    PubMed

    Waleed, Mohammad; Raza, Ali; Minhaj, Tariq; Houghton, Timothy

    2015-09-24

    A 71-year-old man was referred to a rapid access chest pain clinic by his general practitioner. He presented with a 6-month history of twice weekly central chest pain lasting 2-3 min with walking and exertion, relieved with rest or co-codamol tablets. After initial investigations and a positive myoview scan, he was listed for an elective coronary angiogram. Unfortunately, the procedure was abandoned due to unclear course of the guide wire and a possible aberrant aortic course. Further non-invasive tests were arranged to clarify the anatomy of the vessels. After getting a clear idea of the aberrancies, coronary angiogram was replanned, and the patient underwent successful angiography with angioplasty to one of the coronary arteries, without any complications.

  14. Chromosome aberrations among the Yanomamma Indians.

    PubMed

    Bloom, A D; Neel, J V; Choi, K W; Iida, S; Chagnon, N

    1970-07-01

    The chromosomes of leucocytes cultured from the peripheral blood of 49 primitive Yanomama Indians of Venezuela were studied to determine the types and frequencies of aberrations in a human population not exposed to the same exogenous agents as civilized man. In all but one instance, 100 cells per individual were scored. In 13 cases, we found one or more cells with multiple complex breaks and rearrangements, represented by tetracentric, tricentric, and numerous dicentric chromosomes. From the standpoint of chromosomal damage, these cells are among the most abnormal cells yet described in vivo in man, and were not seen in the controls. There was also a higher than expected frequency of cells with an isolated structural aberration in both Indians and controls. This may be the result of a 24- to 48-hour delay in the initiation of culture. The cause of the more extensive damage to some cells remains to be determined.

  15. Chromosomal aberrations in oral solitary fibrous tumor.

    PubMed

    Manor, Esther; Bodner, Lipa

    2007-04-15

    The results of cytogenetic analysis of a solitary fibrous tumor (SFT) of the oral cavity in a 43-year-old man is reported. The abnormal cells carried a complex translocation with the karyotype 46,XY [15 cells]/46,XYt(1;17;18)(p13;q11.2;q21)[5 cells]. This is the first case reporting chromosomal aberrations in an oral SFT.

  16. Compact, holographic correction of aberrated telescopes.

    PubMed

    Andersen, G; Munch, J; Veitch, P

    1997-03-01

    We demonstrate a compact reflector telescope design that incorporates the holographic correction of a large, low-quality primary spherical mirror by using a laser beacon located at the center of curvature. The simple design makes use of conventional optics and is easily scalable to much larger apertures. Experimental results indicate diffraction-limited performance from a heavily aberrated 0.5-m-diameter spherical mirror.

  17. Familial lysinuric protein intolerance presenting as coma in two adult siblings.

    PubMed

    Shaw, P J; Dale, G; Bates, D

    1989-05-01

    Lysinuric protein intolerance (LPI) is an inborn error of metabolism which usually presents in infancy with failure to thrive and vomiting. Two patients are described who presented in adult life with hyperammonaemic coma due to LPI. Both had been underweight and had had intermittent gastrointestinal symptoms during childhood. They were of normal intellect and had maintained good health, until presentation in their thirties, by unconscious dietary protein avoidance. The diagnosis of LPI should be considered in patients who present with obscure relapsing coma associated with hyperammonaemia. Considerable clinical improvement may result from dietary protein restriction and citrulline supplementation.

  18. VizieR Online Data Catalog: HST/ACS Coma Cluster Survey. X. (den Brok+, 2014)

    NASA Astrophysics Data System (ADS)

    den Brok, M.; Peletier, R. F.; Seth, A.; Balcells, M.; Dominguez, L.; Graham, A. W.; Carter, D.; Erwin, P.; Ferguson, H. C.; Goudfrooij, P.; Guzman, R.; Hoyos, C.; Jogee, S.; Lucey, J.; Phillipps, S.; Puzia, T.; Valentijn, E.; Kleijn, G. V.; Weinzirl, T.

    2015-05-01

    The Coma ACS Survey (Carter et al., 2008ApJS..176..424C) provides data in two passbands for 25 fields pointed at the core of the Coma cluster and at the outskirts. The exposure times in the two passbands, F814W and F475W (which are roughly equivalent to the IC and g band) were ~1400 and ~2600s. The original envisaged coverage of the cluster was much larger than 25 fields, but due to the ACS failure in 2008 January the survey was not completed. (2 data files).

  19. Analysis of hydrogen H-alpha observations of the coma of Comet P/Halley

    NASA Technical Reports Server (NTRS)

    Smyth, William H.; Marconi, M. L.; Scherb, Frank; Roesler, Fred L.

    1993-01-01

    The Monte Carlo Particle Trajectory Model of Combi and Smyth (1988) is used here to analyze observations of the H-alpha coma of Comet Halley. The solar excitation mechanism for the H-alpha emissions line is described. The H2O production rates derived for the H-alpha brightness measurements are shown to be very consistent with the H2O production rates determined from other Comet Halley observations of the H, O, and OH comae. Revised H2O production rates determined from 6300 A brightness measurements are presented.

  20. Repeatability of the Dust and Gas Morphological Structures in the Coma of Comet

    NASA Astrophysics Data System (ADS)

    Lejoly, Cassandra; Samarasinha, N. H.; Ojha, L.; Schleicher, D. G.

    2013-10-01

    Comet 1P/Halley is the most famous comet in history and has been observed for over two millennia, making it one of the most extensively studied comets. The morphology in the coma of comet 1P/Halley originates due to the activity at the nucleus and could be used as a probe of the nuclear rotation and the activity. We will present the results from a study summarizing the evolution of coma morphology of comet 1P/Halley observed from ground between October 1985 and June 1986. The results to be presented include analysis of dust features as well as gas (CN) features in the coma and comparisons will be made between their spatial and temporal evolution. About 80 CN images and 300 continuum images from the Small Bodies Node of the NASA Planetary Data System were analyzed using image enhancement techniques that were not available n the 1980s. This enables us to see coma structure never observed before in comet 1P/Halley. Because of the comet's proximity to Earth, most of our best signal-to-noise images were taken in the March-April interval of 1986. Despite the limited coverage of preceding and following months, there is a sufficient number of images to monitor morphological evolution over many months. The initial synodic periods as a function of time used to phase the images together were extrapolated from the lightcurves of the active coma (Schleicher et al. 1990, AJ, 100, 896-912). We will present the periods of repeatability of individual coma features measured using the position angle at different spatial distances from the nucleus in adjacent cycles. Separate features appear to have slightly different periods of repeatability, perhaps depending on the corresponding source regions on the nucleus and/or projection effects. The periods of repeatability of coma morphologies will be presented as a function of time from the perihelion. These results will ultimately be used in detailed modeling of the coma morphologies of comet 1P/Halley over the 1985-1986 apparition in

  1. Aberrant phenotypes in Kikuchi’s disease

    PubMed Central

    Wei, Xue-Jing; Zhou, Xiao-Ge; Xie, Jian-Lan; Zheng, Xiao-Dan; Zheng, Yuan-Yuan

    2014-01-01

    Initial reports emphasized the immunophenotypic similarities between benign and malignant T cell populations, while some previous studies indicating that aberrant T-cell antigen loss is a good marker for detecting malignant T-cell proliferation. Recently, we found a very interesting and thought-provoking phenomenon: In benign disease-28 of 38 (73.7%) cases of Kikuchi’s disease also showed aberrant phenotypes with loss of pan-T cell antigens, which makes the differential diagnosis between Kikuchi’s disease and T cell lymphoma more challenging. In our study, 38 cases of Kikuchi’s disease and 30 cases of reactive lymphoid hyperplasia (RLH) were studied by EliVision immunohistochemical staining. As well as TCR gene rearrangement using PCR was negative in 10 tested cases of the Kikuchi’s disease. Among these cases, the most common antigen deficiency was CD5 (22 cases), then CD7 (11 cases), CD2 (8 cases) and CD3 (2 cases). Compared with proliferative and xanthomatous types of Kikuchi’s disease, antigens tended to be lost in necrotizing type. Based on follow-up data, a correlation was not found between the occurrence of aberrant phenotypes and prognosis. In RLH, obvious pan-T cell antigen loss was also not found. In conclusion, this is the first study to demonstrate distinct patterns of antigen loss in Kikuchi’s disease, suggesting that T cell antigen loss is not reliable as an auxiliary diagnostic standard for T cell lymphoma. PMID:25337197

  2. Coma imaging of comet P/Brorsen-Metcalf at Calar Alto in late July to mid August 1989

    NASA Technical Reports Server (NTRS)

    Boehnhardt, Hermann; Vanysek, Vladimir; Birkle, K.; Hopp, U.

    1992-01-01

    Comet P/Brorsen-Metcalf was observed on 1989/07/28+30 and on 1989/08/04+12(+14) with the 3.5 m telescope and the 0.8 m Schmidt camera at Calar Alto/Spain. The images exhibit a narrow plasma tail pointing into anti-solar direction. On 1989/07/30 a triple tail was found which can be interpreted as tail ray event. The coma isophotes show prominent asymmetries with the nucleus located on the tailward side of the isophote foci and with a slightly higher brightness in the Northern Hemisphere of the coma. A strong curved jet feature was detected in the coma on 1989/07/30. The jet extended at least 30,000 km into the sunward coma hemisphere. The rotation period of about 1.3 days, estimated from the curvature of the coma jet, needs verification by other observations.

  3. DNA Repair Defects and Chromosomal Aberrations

    NASA Technical Reports Server (NTRS)

    Hada, Megumi; George, K. A.; Huff, J. L.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Yields of chromosome aberrations were assessed in cells deficient in DNA doublestrand break (DSB) repair, after exposure to acute or to low-dose-rate (0.018 Gy/hr) gamma rays or acute high LET iron nuclei. We studied several cell lines including fibroblasts deficient in ATM (ataxia telangiectasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. Chromosomes were analyzed using the fluorescence in situ hybridization (FISH) chromosome painting method in cells at the first division post irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma irradiation induced greater yields of both simple and complex exchanges in the DSB repair-defective cells than in the normal cells. The quadratic dose-response terms for both simple and complex chromosome exchanges were significantly higher for the ATM- and NBS-deficient lines than for normal fibroblasts. However, in the NBS cells the linear dose-response term was significantly higher only for simple exchanges. The large increases in the quadratic dose-response terms in these repair-defective cell lines points the importance of the functions of ATM and NBS in chromatin modifications to facilitate correct DSB repair and minimize the formation of aberrations. The differences found between ATM- and NBS-deficient cells at low doses suggest that important questions should with regard to applying observations of radiation sensitivity at high dose to low-dose exposures. For aberrations induced by iron nuclei, regression models preferred purely linear dose responses for simple exchanges and quadratic dose responses for complex exchanges. Relative biological effectiveness (RBE) factors of all of

  4. Evidence-based improvement of the National Trauma Triage Protocol: The Glasgow Coma Scale versus Glasgow Coma Scale motor subscale

    PubMed Central

    Brown, Joshua B.; Forsythe, Raquel M.; Stassen, Nicole A.; Peitzman, Andrew B.; Billiar, Timothy R.; Sperry, Jason L.; Gestring, Mark L.

    2015-01-01

    BACKGROUND Ideal triage uses simple criteria to identify severely injured patients. Glasgow Coma Scale motor (GCSm) may be easier for field use and was considered for the National Trauma Triage Protocol (NTTP). This study evaluated performance of the NTTP if GCSm is substituted for the current GCS score ≤ 13 criterion. METHODS Subjects in the National Trauma Data Bank undergoing scene transport were included. Presence of NTTP physiologic (Step 1) and anatomic (Step 2) criteria was determined. GCSm score ≤ 5 was defined as a positive criterion. Trauma center need (TCN) was defined as Injury Severity Score (ISS) > 15, intensive care unit admission, urgent operation, or emergency department death. Test characteristics were calculated to predict TCN. Area under the curve was compared between GCSm and GCS scores, individually and within the NTTP. Logistic regression was used to determine the association of GCSm score ≤ 5 and GCS score ≤ 13 with TCN after adjusting for other triage criteria. Predicted versus actual TCN was compared. RESULTS There were 811,143 subjects. Sensitivity was lower (26.7% vs. 30.3%), specificity was higher (95.1% vs. 93.1%), and accuracy was similar (66.1% vs. 66.3%) for GCSm score ≤ 5 compared with GCS score ≤ 13. Incorporated into the NTTP Steps 1 + 2, GCSm score ≤ 5 traded sensitivity (60.4% vs. 62.1%) for specificity (67.1% vs. 65.7%) with similar accuracy (64.2% vs. 64.2%) to GCS score ≤ 13. There was no difference in the area under the curve between GCSm score ≤ 5 and GCS score ≤ 13 when incorporated into the NTTP Steps 1 + 2 (p = 0.10). GCSm score ≤ 5 had a stronger association with TCN (odds ratio, 3.37; 95% confidence interval, 3.27–3.48; p < 0.01) than GCS score ≤ 13 (odds ratio, 3.03; 95% confidence interval, 2.94–3.13; p < 0.01). GCSm had a better fit of predicted versus actual TCN than GCS at the lower end of the scales. CONCLUSION GCSm score ≤ 5 increases specificity at the expense of sensitivity

  5. Chromatic variation of aberration: the role of induced aberrations and raytrace direction

    NASA Astrophysics Data System (ADS)

    Berner, A.; Nobis, T.; Shafer, D.; Gross, H.

    2015-09-01

    The design and optimization process of an optical system contains several first order steps. The definition of the appropriate lens type and the fixation of the raytrace direction are some of them. The latter can be understood as a hidden assumption rather than an aware design step. This is usually followed by the determination of the paraxial lens layout calculated for the primary wavelength. It is obvious, that for this primary wavelength the paraxial calculations are independent of raytrace direction. Today, most of the lens designs are specified not to work only for one wavelength, but in a certain wavelength range. Considering such rays of other wavelengths, one can observe that depending on the direction there will already occur differences in the first order chromatic aberrations and additionally in the chromatic variation of the third-order aberrations. The reason for this effect are induced aberrations emerging from one surface to the following surfaces by perturbed ray heights and ray angles. It can be shown, that the total amount of surface-resolved first order chromatic aberrations and the chromatic variation of the five primary aberrations can be split into an intrinsic part and an induced part. The intrinsic part is independent of the raytrace direction whereas the induced part is not.

  6. Ultra-high-speed 3D astigmatic particle tracking velocimetry: application to particle-laden supersonic impinging jets

    NASA Astrophysics Data System (ADS)

    Buchmann, N. A.; Cierpka, C.; Kähler, C. J.; Soria, J.

    2014-11-01

    The paper demonstrates ultra-high-speed three-component, three-dimensional (3C3D) velocity measurements of micron-sized particles suspended in a supersonic impinging jet flow. Understanding the dynamics of individual particles in such flows is important for the design of particle impactors for drug delivery or cold gas dynamic spray processing. The underexpanded jet flow is produced via a converging nozzle, and micron-sized particles ( d p = 110 μm) are introduced into the gas flow. The supersonic jet impinges onto a flat surface, and the particle impact velocity and particle impact angle are studied for a range of flow conditions and impingement distances. The imaging system consists of an ultra-high-speed digital camera (Shimadzu HPV-1) capable of recording rates of up to 1 Mfps. Astigmatism particle tracking velocimetry (APTV) is used to measure the 3D particle position (Cierpka et al., Meas Sci Technol 21(045401):13, 2010) by coding the particle depth location in the 2D images by adding a cylindrical lens to the high-speed imaging system. Based on the reconstructed 3D particle positions, the particle trajectories are obtained via a higher-order tracking scheme that takes advantage of the high temporal resolution to increase robustness and accuracy of the measurement. It is shown that the particle velocity and impingement angle are affected by the gas flow in a manner depending on the nozzle pressure ratio and stand-off distance where higher pressure ratios and stand-off distances lead to higher impact velocities and larger impact angles.

  7. Chemical processing in the coma as the source of cometary HNC.

    PubMed

    Irvine, W M; Bergin, E A; Dickens, J E; Jewitt, D; Lovell, A J; Matthews, H E; Schloerb, F P; Senay, M

    1998-06-11

    The discovery of hydrogen isocyanide (HNC) in comet Hyakutake with an abundance (relative to hydrogen cyanide, HCN) similar to that seen in dense interstellar clouds raised the possibility that these molecules might be surviving interstellar material. The preservation of material from the Sun's parent molecular cloud would provide important constraints on the processes that took place in the protostellar nebula. But another possibility is that HNC is produced by photochemical processes in the coma, which means that its abundance could not be used as a direct constraint on conditions in the early Solar System. Here we show that the HNC/HCN ratio determined for comet Hale-Bopp varied with heliocentric distance in a way that matches the predictions of models of gas-phase chemical production of HNC in the coma, but cannot be explained if the HNC molecules were coming from the comet's nucleus. We conclude that HNC forms mainly by chemical reactions in the coma, and that such reactions need to be considered when attempting to deduce the composition of the nucleus from observations of the coma.

  8. The Coma of Comet 67P/Churyumov-Gerasimenko Pre- and Post- Equinox

    NASA Astrophysics Data System (ADS)

    Fougere, Nicolas; Altwegg, Kathrin; Berthelier, Jean-Jacques; Bieler, Andre; Bockelee-Morvan, Dominique; Calmonte, Ursina; Capaccioni, Fabrizio; Combi, Mike; Dekeyser, Johan; Debout, Vincent; Erard, Stephane; Fiethe, Bjorn; Fillacchione, Gianrico; Fink, Uwe; Fuselier, Stephen; Gombosi, Tamas; Hansen, Kenneth; Hassig, Myrtha; Huang, Zhenguang; Leroy, Lena; Leyrat, Cedric; Migliorini, Alessandra; Piccioni, Giuseppe; Rinaldi, Giovanna; Rubin, Martin; Tenishev, Valeriy; Toth, Gabor; Tzou, Chia-Yu; Shou, Yinsi

    2016-04-01

    As the Rosetta spacecraft escorts comet 67P/Churyumov-Gerasimenko (67P) during its journey in the Solar System, it monitors the evolution of the neutrals' distribution in the coma of 67P. Indeed, while the comet orbits around the Sun, the energy input received by the different regions of the nucleus varies, directly impacting 67P's outgassing pattern. We model the H2O, CO2, and CO coma of Comet 67P/Churyumov-Gerasimenko (67P) pre- and post- equinox using a 3D Direct Monte-Carlo Simulation approach. The use of a kinetic method enables us to model the coma from the nucleus' surface to a few hundreds of kilometers even in the regions where collisions cannot maintain a fluid regime. The activity at the surface of the nucleus is described using a spherical harmonic expansion with 25 terms constrained by ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) observations. The model outputs contain information about numerous macroscopic parameters such as number densities, velocities, and temperatures of each species. Then, the results from the simulations are integrated along the line of sight to be compared with the remote sensing observations from the VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) instrument. The model shows a good agreement with the data, giving a clear evidence of our understanding of the physics of the coma of comet 67P.

  9. Morfología de la Coma del Cometa Hale - Bopp

    NASA Astrophysics Data System (ADS)

    Gil-Hutton, R.; Caballero, M.; Coldwell, G.; Cañada, M.; Godoy, G.; Trozzo, C.; Gómez, G.

    Para lograr comprender plenamente los procesos físicos que se desarrollan en los núcleos cometarios y obtener un modelo que explique, no sólo su actividad, sino también sus efectos sobre la coma, es necesario obtener información detallada para el mayor número de cometas posible, siendo las características más interesantes para estudiar la ubicación de las regiones activas, la presencia de jets, las tasas de producción de gas y polvo y la interacción de la coma con el viento solar. En la actualidad, con técnicas de procesamiento de imágenes y tecnología CCD se pueden obtener este tipo de datos para cometas que ingresan al sistema solar interior y estudiar, de esta manera, la morfología de sus comas, tratando de correlacionar la actividad detectada con algún modelo teórico. En este trabajo se presenta un estudio parcial de la actividad desarrollada por el cometa Hale-Bopp, y sus efectos sobre la morfología de su coma, desde agosto de 1995 hasta la fecha en base a imágenes adquiridas con el telescopio de 0.76 m. de la Estación Astronómica Dr. Carlos Ulrrico Cesco.

  10. Dust in Cometary Comae: Present Understanding of the Structure and Composition of Dust Particles

    NASA Technical Reports Server (NTRS)

    Levasseur-Regourd, A. C.; Zolensky, M.; Lasue, J.

    2007-01-01

    In situ probing of a very few cometary comae has shown that dust particles present a low albedo and a low density, and that they consist of both rocky material and refractory organics. Remote observations of solar light scattered by cometary dust provide information on the properties of dust particles in the coma of a larger set of comets. The observations of the linear polarization in the coma indicate that the dust particles are irregular, with a size greater (on the average) than about one micron. Besides, they suggest, through numerical and experimental simulations, that both compact grains and fluffy aggregates (with a power law of the size distribution in the -2.6 to -3 range), and both rather transparent silicates and absorbing organics are present in the coma. Recent analysis of the cometary dust samples collected by the Stardust mission provide a unique ground truth and confirm, for comet 81P/Wild 2, the results from remote sensing observations. Future space missions to comets should, in the next decade, lead to a more precise characterization of the structure and composition of cometary dust particles.

  11. Spatial and temporal variations in the column density distribution of comet Halley's CN coma

    NASA Technical Reports Server (NTRS)

    Schulz, Rita; Schlosser, W.; Meisser, W.; Koczet, P.; Celnik, W. E.

    1992-01-01

    Mean radial column density profiles of comet P/Halley's CN coma were derived by combining photographic and photoelectric observations. The shape of the profiles as well as their temporal variations were analyzed in detail and compared with the results of other CN observations of the comet.

  12. Relationship between inner coma water emissions and ice deposits in comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Migliorini, Alessandra; Filacchione, Gianrico; De Sanctis, Maria Cristina; Capaccioni, Fabrizio; Piccioni, Giuseppe; Bockelée-Morvan, Dominique; Erard, Stephane; Leyrat, Cedric; Ciarniello, Mauro; Combi, Michael; Fougere, Nicolas; Taylor, Fred

    2016-04-01

    Data acquired in April 2015 with the VIRTIS spectrometer on board the Rosetta mission provided information on the possible correlation between the H2O emission in the inner coma and the exposed water deposits detected in the Hapi region on the 67P/Churyumov-Gerasimenko surface (Migliorini et al. submitted). Further bright spots attributed to exposed water ice have been identified in other regions by OSIRIS at visible wavelengths (Pommerol, et al., 2015) and confirmed in the infrared by VIRTIS-M in the Imothep region (Filacchione et al., 2016). Furthermore, new water ice deposits have been identified in regions located both at the equator and at southern latitudes. These regions might be localised sources of water emissions in the inner coma of 67P/C-G. The present investigation seeks to identify the spatial and temporal correlations between the H2O emissions in the inner coma and the water ice rich deposits on the surface in order to identify the mechanisms operating at the surface-coma interface. It extends the study already carried out for a limited region located in the comet's neck, and identifies how the observed emissions and deposits evolve with the heliocentric distance, as observed by VIRTIS during the Rosetta escort phase mission.

  13. H-ATLAS: the far-infrared properties of galaxies in and around the Coma cluster

    NASA Astrophysics Data System (ADS)

    Fuller, C.; Davies, J. I.; Smith, M. W. L.; Valiante, E.; Eales, S.; Bourne, N.; Dunne, L.; Dye, S.; Furlanetto, C.; Ibar, E.; Ivison, R.; Maddox, S.; Sansom, A.; Michałowski, M. J.; Davis, T.

    2016-05-01

    We describe a far-infrared survey of the Coma cluster and the galaxy filament it resides within. Our survey covers an area of ˜150 deg2 observed by Herschel H-ATLAS (Herschel Astrophysical Terahertz Large Area Survey) in five bands at 100, 160, 250, 350 and 500 μm. The SDSS spectroscopic survey (mr ≤ 17.8) is used to define an area (within the virial radius) and redshift selected (4268 < v < 9700 km s-1) sample of 744 Coma cluster galaxies - the Coma Cluster Catalogue. For comparison, we also define a sample of 951 galaxies in the connecting filament - the Coma Filament Catalogue. The optical positions and parameters are used to define appropriate apertures to measure each galaxy's far-infrared emission. We have detected 99 of 744 (13 per cent) and 422 of 951 (44 per cent) of the cluster and filament galaxies in the SPIRE 250 μm band. We consider the relative detection rates of galaxies of different morphological types finding that it is only the S0/Sa population that shows clear differences between the cluster and filament. We find no differences between the dust masses and temperatures of cluster and filament galaxies with the exception of early-type galaxy dust temperatures, which are significantly hotter in the cluster than in the filament (X-ray heating?). From a chemical evolution model, we find no evidence for different evolutionary processes (gas loss or infall) between galaxies in the cluster and filament.

  14. Prospective Cohort Study Evaluating the Prognostic Value of Simple EEG Parameters in Postanoxic Coma.

    PubMed

    Azabou, Eric; Fischer, Catherine; Mauguiere, François; Vaugier, Isabelle; Annane, Djillali; Sharshar, Tarek; Lofaso, Fréderic

    2016-01-01

    We prospectively studied early bedside standard EEG characteristics in 61 acute postanoxic coma patients. Five simple EEG features, namely, isoelectric, discontinuous, nonreactive to intense auditory and nociceptive stimuli, dominant delta frequency, and occurrence of paroxysms were classified yes or no. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUC) of each of these variables for predicting an unfavorable outcome, defined as death, persistent vegetative state, minimally conscious state, or severe neurological disability, as assessed 1 year after coma onset were computed as well as Synek's score. The outcome was unfavorable in 56 (91.8%) patients. Sensitivity, specificity, PPV, NPV, and AUC of nonreactive EEG for predicting an unfavorable outcome were 84%, 80%, 98%, 31%, and 0.82, respectively; and were all very close to the ones of Synek score>3, which were 82%, 80%, 98%, 29%, and 0.81, respectively. Specificities for predicting an unfavorable outcome were 100% for isoelectric, discontinuous, or dominant delta activity EEG. These 3 last features were constantly associated to unfavorable outcome. Absent EEG reactivity strongly predicted an unfavorable outcome in postanoxic coma, and performed as accurate as a Synek score>3. Analyzing characteristics of some simple EEG features may easily help nonneurophysiologist physicians to investigate prognostic issue of postanoxic coma patient. In this study (a) discontinuous, isoelectric, or delta-dominant EEG were constantly associated with unfavorable outcome and (b) nonreactive EEG performed prognostic as accurate as a Synek score>3.

  15. Communication Opportunities via Special Messaging Technology for Two Post-Coma Persons with Multiple Disabilities

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; O'Reilly, Mark F.; Singh, Nirbhay N.; Sigafoos, Jeff; Buonocunto, Francesca; Sacco, Valentina; Colonna, Fabio; Navarro, Jorge; Lanzilotti, Crocifissa; de Pace, Claudia; Megna, Marisa; Oliva, Doretta

    2011-01-01

    This study extended the assessment of a special messaging technology with two additional post-coma adults who had emerged from a minimally conscious state, but showed multiple disabilities including profound motor and communication impairments. For each participant, the study involved an ABAB design, in which the A represented baseline phases and…

  16. Wavefront aberrations of x-ray dynamical diffraction beams.

    PubMed

    Liao, Keliang; Hong, Youli; Sheng, Weifan

    2014-10-01

    The effects of dynamical diffraction in x-ray diffractive optics with large numerical aperture render the wavefront aberrations difficult to describe using the aberration polynomials, yet knowledge of them plays an important role in a vast variety of scientific problems ranging from optical testing to adaptive optics. Although the diffraction theory of optical aberrations was established decades ago, its application in the area of x-ray dynamical diffraction theory (DDT) is still lacking. Here, we conduct a theoretical study on the aberration properties of x-ray dynamical diffraction beams. By treating the modulus of the complex envelope as the amplitude weight function in the orthogonalization procedure, we generalize the nonrecursive matrix method for the determination of orthonormal aberration polynomials, wherein Zernike DDT and Legendre DDT polynomials are proposed. As an example, we investigate the aberration evolution inside a tilted multilayer Laue lens. The corresponding Legendre DDT polynomials are obtained numerically, which represent balanced aberrations yielding minimum variance of the classical aberrations of an anamorphic optical system. The balancing of classical aberrations and their standard deviations are discussed. We also present the Strehl ratio of the primary and secondary balanced aberrations.

  17. Comet 67P/Churyumov-Gerasimenko during the Rosetta mission: numerical simulation of dusty gas coma

    NASA Astrophysics Data System (ADS)

    Tenishev, Valeriy; Combi, Michael; Rubin, Martin; Hansen, Kenneth; Gombosi, Tamas

    The Rosetta spacecraft is en route to comet 67P/Churyumov-Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. Having a limited amount of information regarding its coma, interpretation of measurements and safety consideration of the spacecraft will require modeling of the comet's environment. Such models should be able to simulate both the gas and dust phases of the coma as well as the interaction between them in a self-consistent manner. The relevant physical processes in the coma include photolytic reactions and interaction with the nucleus for the gas phase and drag by the gas, gravity of the nucleus, solar gravity and radiation pressure, and charging by the ambient plasma for the dust phase. Developing of such modeling capabilities will be able to link measurements obtained by different instruments onboard of spacecraft. Some examples of cometary comae simulations can be found in [1-3]. In this work we present our kinetic model of a dusty gas coma [4] with results of its application to the case of comet Churyumov-Gerasimenko at conditions corresponding to some stages the during the Rosetta mission. Based on the surface properties and local production rates obtained by MIRO, RSI and VIRTIS the model will be able to propagate the injected gas and dust into the coma linking the measurements to those obtained by ALICE, MIDAS and ROSINA for the gas phase and COSIMA and GIADA for the dust phase of the coma. A simultaneous simulation of the major components of the multi-phase coma will allow us to link observations of the gas and dust phases. In this work we present results of a numerical study of neutral/ionized multispecies gaseous and electrically charged dust environment of the comet Churyumov-Gerasimenko at a helio-centric distance of 1.3 AU. The simulation is performed in fully 3D geometry with a realistic nucleus model that describes its topological features and source distribution. Both, neutral and ionized components of the

  18. These are two images of the inner coma of Comet Hyakutake

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These are two images of the inner coma of Comet Hyakutake made on April 3 and 4, 1996, using the NASA Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2). The first one, shown in red, was taken through a narrow-band red filter that shows only sunlight scattered by dust particles in the inner coma of the comet. The second one, shown in blue was taken with an ultraviolet 'Woods' filter image that shows the distribution of scattered ultraviolet radiation from hydrogen atoms in the inner coma. The coma is the head or dusty-gas atmosphere of a comet. The square field of view is 14,000 km on a side and the sun is toward the upper right corner of the image. Hydrogen atoms represent the most abundant gas in the whole coma of the comet. They are produced when solar ultraviolet light breaks up molecules of water, the major constitutent of the nucleus of the comet. These images were taken as part of an observing program to study water photochemistry in comets. Measurements of hydrogen (H) and hydroxyl (OH) in the coma (or atmosphere) of Comet Hyakutake were also made using the Goddard High Resolution Spectrograph (GHRS) and the Faint Object Spectrograph (FOS). A self-consistent analysis of all the data shows that the water production rate of the comet was between 7 and 8 tons per second on the April 3 and 4. A theoretical model was used in the analysis which accounts for the detailed physics and chemistry of the photochemical destruction of the water, the production of the H and OH, and their expansion in the coma (or atmosphere) of the comet. The model matched the velocity measurements of hydrogen atoms made using the high spectral resolution capabilities of the GHRS instrument. The importance of such a detailed model is that is permits the accurate calculation of the production rate of water from observations of H and OH. The inner yellow region near the center of the red dust image is dominated by the contribution from the dust which shows sunward directed spiral

  19. Chromosomal aberrations in ISS crew members

    NASA Astrophysics Data System (ADS)

    Johannes, Christian; Goedecke, Wolfgang; Antonopoulos, Alexandra

    2012-07-01

    High energy radiation is a major risk factor in manned space missions. Astronauts and cosmonauts are exposed to ionising radiations of cosmic and solar origin, while on the Earth's surface people are well protected by the atmosphere and a deflecting magnetic field. There are now data available describing the dose and the quality of ionising radiation on-board of the International Space Station (ISS). Nonetheless, the effect of increased radiation dose on mutation rates of ISS crew members are hard to predict. Therefore, direct measurements of mutation rates are required in order to better estimate the radiation risk for longer duration missions. The analysis of chromosomal aberrations in peripheral blood lymphocytes is a well established method to measure radiation-induced mutations. We present data of chromosome aberration analyses from lymphocyte metaphase spreads of ISS crew members participating in short term (10-14 days) or long term (around 6 months) missions. From each subject we received two blood samples. The first sample was drawn about 10 days before launch and a second one within 3 days after return from flight. From lymphocyte cultures metaphase plates were prepared on glass slides. Giemsa stained and in situ hybridised metaphases were scored for chromosome changes in pre-flight and post-flight blood samples and the mutation rates were compared. Results obtained in chromosomal studies on long-term flight crew members showed pronounced inter-individual differences in the response to elevated radiation levels. Overall slight but significant elevations of typical radiation induced aberrations, i.e., dicentric chromosomes and reciprocal translocations have been observed. Our data indicate no elevation of mutation rates due to short term stays on-board the ISS.

  20. Predicting aberrant CpG island methylation

    PubMed Central

    Feltus, F. A.; Lee, E. K.; Costello, J. F.; Plass, C.; Vertino, P. M.

    2003-01-01

    Epigenetic silencing associated with aberrant methylation of promoter region CpG islands is one mechanism leading to loss of tumor suppressor function in human cancer. Profiling of CpG island methylation indicates that some genes are more frequently methylated than others, and that each tumor type is associated with a unique set of methylated genes. However, little is known about why certain genes succumb to this aberrant event. To address this question, we used Restriction Landmark Genome Scanning to analyze the susceptibility of 1,749 unselected CpG islands to de novo methylation driven by overexpression of DNA cytosine-5-methyltransferase 1 (DNMT1). We found that although the overall incidence of CpG island methylation was increased in cells overexpressing DNMT1, not all loci were equally affected. The majority of CpG islands (69.9%) were resistant to de novo methylation, regardless of DNMT1 overexpression. In contrast, we identified a subset of methylation-prone CpG islands (3.8%) that were consistently hypermethylated in multiple DNMT1 overexpressing clones. Methylation-prone and methylation-resistant CpG islands were not significantly different with respect to size, C+G content, CpG frequency, chromosomal location, or promoter association. We used DNA pattern recognition and supervised learning techniques to derive a classification function based on the frequency of seven novel sequence patterns that was capable of discriminating methylation-prone from methylation-resistant CpG islands with 82% accuracy. The data indicate that CpG islands differ in their intrinsic susceptibility to de novo methylation, and suggest that the propensity for a CpG island to become aberrantly methylated can be predicted based on its sequence context. PMID:14519846

  1. Peripheral Aberrations and Image Quality for Contact Lens Correction

    PubMed Central

    Shen, Jie; Thibos, Larry N.

    2011-01-01

    Purpose Contact lenses reduced the degree of hyperopic field curvature present in myopic eyes and rigid contact lenses reduced sphero-cylindrical image blur on the peripheral retina, but their effect on higher order aberrations and overall optical quality of the eye in the peripheral visual field is still unknown. The purpose of our study was to evaluate peripheral wavefront aberrations and image quality across the visual field before and after contact lens correction. Methods A commercial Hartmann-Shack aberrometer was used to measure ocular wavefront errors in 5° steps out to 30° of eccentricity along the horizontal meridian in uncorrected eyes and when the same eyes are corrected with soft or rigid contact lenses. Wavefront aberrations and image quality were determined for the full elliptical pupil encountered in off-axis measurements. Results Ocular higher-order aberrations increase away from fovea in the uncorrected eye. Third-order aberrations are larger and increase faster with eccentricity compared to the other higher-order aberrations. Contact lenses increase all higher-order aberrations except 3rd-order Zernike terms. Nevertheless, a net increase in image quality across the horizontal visual field for objects located at the foveal far point is achieved with rigid lenses, whereas soft contact lenses reduce image quality. Conclusions Second order aberrations limit image quality more than higher-order aberrations in the periphery. Although second-order aberrations are reduced by contact lenses, the resulting gain in image quality is partially offset by increased amounts of higher-order aberrations. To fully realize the benefits of correcting higher-order aberrations in the peripheral field requires improved correction of second-order aberrations as well. PMID:21873925

  2. Aberrations in Fresnel Lenses and Mirrors

    NASA Technical Reports Server (NTRS)

    Gregory, Don

    1999-01-01

    The NASA/MSFC Shooting Star program revealed a number of technical problems that must be solved before solar thermal propulsion can become a reality. The fundamental problem of interest here is the collection of solar energy. This is the first step in the propulsion process and indeed the most important. Everything else depends on the efficiency and focusing ability of the collection lens or mirror. An initial model of Fresnel lens behavior using a wave optics approach has been completed and the results were encouraging enough to warrant an experimental investigation. This experimental investigation confirmed some of the effects predicted and produced invaluable photographic evidence of coherence based diffraction and aberration.

  3. Aberrant splicing and drug resistance in AML.

    PubMed

    de Necochea-Campion, Rosalia; Shouse, Geoffrey P; Zhou, Qi; Mirshahidi, Saied; Chen, Chien-Shing

    2016-01-01

    The advent of next-generation sequencing technologies has unveiled a new window into the heterogeneity of acute myeloid leukemia (AML). In particular, recurrent mutations in spliceosome machinery and genome-wide aberrant splicing events have been recognized as a prominent component of this disease. This review will focus on how these factors influence drug resistance through altered splicing of tumor suppressor and oncogenes and dysregulation of the apoptotic signaling network. A better understanding of these factors in disease progression is necessary to design appropriate therapeutic strategies recognizing specific alternatively spliced or mutated oncogenic targets. PMID:27613060

  4. Variable zoom system with aberration correction capability

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Stockbridge, Christopher R.; Hoffman, Samuel M.; Bifano, Thomas G.

    2012-07-01

    We describe experiments conducted with two deformable mirrors (DMs) at fixed locations in an optical microscope imaging system. In this configuration, the DM shapes are controlled to provide 2.5× zoom capability, to allow dynamic focus control and to compensate for aberrations of the fixed optical components. Zoom is achieved by simultaneously adjusting focal lengths of the two DMs, which are inserted between an infinity-corrected microscope objective and a tube lens. Image quality is measured using contrast modulation, and performance of the system is quantified, demonstrating an improved point spread function in the adaptively compensated system.

  5. Progression of auditory discrimination based on neural decoding predicts awakening from coma.

    PubMed

    Tzovara, Athina; Rossetti, Andrea O; Spierer, Lucas; Grivel, Jeremy; Murray, Micah M; Oddo, Mauro; De Lucia, Marzia

    2013-01-01

    Auditory evoked potentials are informative of intact cortical functions of comatose patients. The integrity of auditory functions evaluated using mismatch negativity paradigms has been associated with their chances of survival. However, because auditory discrimination is assessed at various delays after coma onset, it is still unclear whether this impairment depends on the time of the recording. We hypothesized that impairment in auditory discrimination capabilities is indicative of coma progression, rather than of the comatose state itself and that rudimentary auditory discrimination remains intact during acute stages of coma. We studied 30 post-anoxic comatose patients resuscitated from cardiac arrest and five healthy, age-matched controls. Using a mismatch negativity paradigm, we performed two electroencephalography recordings with a standard 19-channel clinical montage: the first within 24 h after coma onset and under mild therapeutic hypothermia, and the second after 1 day and under normothermic conditions. We analysed electroencephalography responses based on a multivariate decoding algorithm that automatically quantifies neural discrimination at the single patient level. Results showed high average decoding accuracy in discriminating sounds both for control subjects and comatose patients. Importantly, accurate decoding was largely independent of patients' chance of survival. However, the progression of auditory discrimination between the first and second recordings was informative of a patient's chance of survival. A deterioration of auditory discrimination was observed in all non-survivors (equivalent to 100% positive predictive value for survivors). We show, for the first time, evidence of intact auditory processing even in comatose patients who do not survive and that progression of sound discrimination over time is informative of a patient's chance of survival. Tracking auditory discrimination in comatose patients could provide new insight to the chance

  6. DARK MATTER SUBHALOS AND THE X-RAY MORPHOLOGY OF THE COMA CLUSTER

    SciTech Connect

    Andrade-Santos, Felipe; Nulsen, Paul E. J.; Kraft, Ralph P.; Forman, William R.; Jones, Christine; Vikhlinin, Alexey; Churazov, Eugene

    2013-04-01

    Structure formation models predict that clusters of galaxies contain numerous massive subhalos. The gravity of a subhalo in a cluster compresses the surrounding intracluster gas and enhances its X-ray emission. We present a simple model, which treats subhalos as slow moving and gasless, for computing this effect. Recent weak lensing measurements by Okabe et al. have determined masses of {approx}10{sup 13} M{sub Sun} for three mass concentrations projected within 300 kpc of the center of the Coma Cluster, two of which are centered on the giant elliptical galaxies NGC 4889 and NGC 4874. Adopting a smooth spheroidal {beta}-model for the gas distribution in the unperturbed cluster, we model the effect of these subhalos on the X-ray morphology of the Coma Cluster, comparing our results to Chandra and XMM-Newton X-ray data. The agreement between the models and the X-ray morphology of the central Coma Cluster is striking. With subhalo parameters from the lensing measurements, the distances of the three subhalos from the Coma Cluster midplane along our line of sight are all tightly constrained. Using the model to fit the subhalo masses for NGC 4889 and NGC 4874 gives 9.1 Multiplication-Sign 10{sup 12} M{sub Sun} and 7.6 Multiplication-Sign 10{sup 12} M{sub Sun }, respectively, in good agreement with the lensing masses. These results lend strong support to the argument that NGC 4889 and NGC 4874 are each associated with a subhalo that resides near the center of the Coma Cluster. In addition to constraining the masses and 3-d location of subhalos, the X-ray data show promise as a means of probing the structure of central subhalos.

  7. NUMERICAL SIMULATION OF DUST IN A COMETARY COMA: APPLICATION TO COMET 67P/CHURYUMOV-GERASIMENKO

    SciTech Connect

    Tenishev, Valeriy; Combi, Michael R.; Rubin, Martin

    2011-05-10

    The Rosetta spacecraft is en route to comet 67P/Churyumov-Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. With a limited amount of available observational data, planning of the mission as well as the interpretation of measurements obtained by instruments on board the spacecraft requires modeling of the dusty/gas environment of the comet. During the mission, the collision regime in the inner coma will change starting from transitional to fully collisionless. As a result, a physically correct model has to be valid at conditions that are far from equilibrium and account for the kinetic nature of the processes occurring in the coma. A study of the multi-species coma of comet 67P/Churyumov-Gerasimenko is presented in our previous paper, where we describe our kinetic model and discuss the results of its application to cases that correspond to the different stages during the mission. In this work, we focus on numerical modeling of the dust phase in the coma of comet 67P/Churyumov-Gerasimenko and its interaction with the surrounding gas. The basic phenomena that govern the dynamics and energy balance of the dust grains are outlined. The effect of solar radiation pressure and the nucleus gravity in limiting the maximum liftable mass of the grains is discussed. The distribution of the terminal velocity of the dust grains as a function of subsolar angle is derived in the paper. We have found that in the regions with high gradients of the gas density, spike-like features can form in the dust flow. The obtained results represent the state of the coma in the vicinity of the nucleus for a series of stages throughout the Rosetta mission. The implications of the model results for future measurements by the GIADA instrument are discussed.

  8. The effects of carbon dioxide anesthesia and anoxia on rapid cold-hardening and chill coma recovery in Drosophila melanogaster.

    PubMed

    Nilson, Theresa L; Sinclair, Brent J; Roberts, Stephen P

    2006-10-01

    Carbon dioxide gas is used as an insect anesthetic in many laboratories, despite recent studies which have shown that CO(2) can alter behavior and fitness. We examine the effects of CO(2) and anoxia (N(2)) on cold tolerance, measuring the rapid cold-hardening (RCH) response and chill coma recovery in Drosophila melanogaster. Short exposures to CO(2) or N(2) do not significantly affect RCH, but 60 min of exposure negates RCH. Exposure to CO(2) anesthesia increases chill coma recovery time, but this effect disappears if the flies are given 90 min recovery in air before chill coma induction. Flies treated with N(2) show a similar pattern, but require significantly longer chill coma recovery times even after 90 min of recovery from anoxia. Our results suggest that CO(2) anesthesia is an acceptable way to manipulate flies before cold tolerance experiments (when using RCH or chill coma recovery as a measure), provided exposure duration is minimized and recovery is permitted before chill coma induction. However, we recommend that exposure to N(2) not be used as a method of anesthesia for chill coma studies. PMID:16996534

  9. Lymphocyte chromosomal aberration assay in radiation biodosimetry

    PubMed Central

    Agrawala, Paban K.; Adhikari, J. S.; Chaudhury, N. K.

    2010-01-01

    Exposure to ionizing radiations, whether medical, occupational or accidental, leads to deleterious biological consequences like mortality or carcinogenesis. It is considered that no dose of ionizing radiation exposure is safe. However, once the accurate absorbed dose is estimated, one can be given appropriate medical care and the severe consequences can be minimized. Though several accurate physical dose estimation modalities exist, it is essential to estimate the absorbed dose in biological system taking into account the individual variation in radiation response, so as to plan suitable medical care. Over the last several decades, lots of efforts have been taken to design a rapid and easy biological dosimeter requiring minimum invasive procedures. The metaphase chromosomal aberration assay in human lymphocytes, though is labor intensive and requires skilled individuals, still remains the gold standard for radiation biodosimetry. The current review aims at discussing the human lymphocyte metaphase chromosomal aberration assay and recent developments involving the application of molecular cytogenetic approaches and other technological advancements to make the assay more authentic and simple to use even in the events of mass radiation casualties. PMID:21829315

  10. Relationships between chromosome structure and chromosomal aberrations

    NASA Astrophysics Data System (ADS)

    Eidelman, Yuri; Andreev, Sergey

    An interphase nucleus of human lymphocyte was simulated by the novel Monte Carlo tech-nique. The main features of interphase chromosome structure and packaging were taken into account: different levels of chromatin organisation; nonrandom localisation of chromosomes within a nucleus; chromosome loci dynamics. All chromosomes in a nucleus were modelled as polymer globules. A dynamic pattern of intra/interchromosomal contacts was simulated. The detailed information about chromosomal contacts, such as distribution of intrachromoso-mal contacts over the length of each chromosome and dependence of contact probability on genomic separation between chromosome loci, were calculated and compared to the new exper-imental data obtained by the Hi-C technique. Types and frequencies of simple and complex radiation-induced chromosomal exchange aberrations (CA) induced by X-rays were predicted with taking formation and decay of chromosomal contacts into account. Distance dependence of exchange formation probability was calculated directly. mFISH data for human lymphocytes were analysed. The calculated frequencies of simple CA agreed with the experimental data. Complex CA were underestimated despite the dense packaging of chromosome territories within a nucleus. Possible influence of chromosome-nucleus structural organisation on the frequency and spectrum of radiation-induced chromosome aberrations is discussed.

  11. Correcting Aberrations in Complex Magnet Systems for Muon Cooling Channels

    SciTech Connect

    J.A. Maloney, B. Erdelyi, A. Afanaciev, R.P. Johnson, Y.S. Derbenev, V.S. Morozov

    2011-03-01

    Designing and simulating complex magnet systems needed for cooling channels in both neutrino factories and muon colliders requires innovative techniques to correct for both chromatic and spherical aberrations. Optimizing complex systems, such as helical magnets for example, is also difficult but essential. By using COSY INFINITY, a differential algebra based code, the transfer and aberration maps can be examined to discover what critical terms have the greatest influence on these aberrations.

  12. Aberration design of zoom lens systems using thick lens modules.

    PubMed

    Zhang, Jinkai; Chen, Xiaobo; Xi, Juntong; Wu, Zhuoqi

    2014-12-20

    A systematic approach for the aberration design of a zoom lens system using a thick lens module is presented. Each component is treated as a thick lens module at the beginning of the design. A thick lens module refers to a thick lens component with a real lens structure, like lens materials, lens curvatures, lens thicknesses, and lens interval distances. All nine third-order aberrations of a thick lens component are considered during the design. The relationship of component aberrations in different zoom positions can be approximated from the aberration shift. After minimizing the aberrations of the zoom lens system, the nine third-order aberrations of every lens component can be determined. Then the thick lens structure of every lens component can be determined after optimization according to their first-order properties and third-order aberration targets. After a third optimization for minimum practical third-order aberrations of a zoom lens system, the aberration design using the thick lens module is complete, which provides a practical zoom lens system with thick lens structures. A double-sided telecentric zoom lens system is designed using the thick lens module in this paper, which shows that this method is practical for zoom lens design.

  13. Transverse ray aberrations of Wolter type 1 telescopes

    NASA Technical Reports Server (NTRS)

    Saha, Timo T.

    1986-01-01

    Transverse ray aberration expansions are derived for Wolter type 1 telescopes. The analysis gives third order aberration terms, most of the fifth order terms and two seventh order terms as functions of system parameters and entrance aperture coordinates. The third order distortion is negligible and, therefore, this term is omitted in the expansions. The spot diagrams derived from exact ray tracing and aberration expansions agree well. The importance of fifth and seventh order terms is discussed. The derived aberration expansions are also valid for Wolter type 2 telescopes.

  14. Aberrant glycosylation associated with enzymes as cancer biomarkers

    PubMed Central

    2011-01-01

    Background One of the new roles for enzymes in personalized medicine builds on a rational approach to cancer biomarker discovery using enzyme-associated aberrant glycosylation. A hallmark of cancer, aberrant glycosylation is associated with differential expressions of enzymes such as glycosyltransferase and glycosidases. The aberrant expressions of the enzymes in turn cause cancer cells to produce glycoproteins with specific cancer-associated aberrations in glycan structures. Content In this review we provide examples of cancer biomarker discovery using aberrant glycosylation in three areas. First, changes in glycosylation machinery such as glycosyltransferases/glycosidases could be used as cancer biomarkers. Second, most of the clinically useful cancer biomarkers are glycoproteins. Discovery of specific cancer-associated aberrations in glycan structures of these existing biomarkers could improve their cancer specificity, such as the discovery of AFP-L3, fucosylated glycoforms of AFP. Third, cancer-associated aberrations in glycan structures provide a compelling rationale for discovering new biomarkers using glycomic and glycoproteomic technologies. Summary As a hallmark of cancer, aberrant glycosylation allows for the rational design of biomarker discovery efforts. But more important, we need to translate these biomarkers from discovery to clinical diagnostics using good strategies, such as the lessons learned from translating the biomarkers discovered using proteomic technologies to OVA 1, the first FDA-cleared In Vitro Diagnostic Multivariate Index Assay (IVDMIA). These lessons, providing important guidance in current efforts in biomarker discovery and translation, are applicable to the discovery of aberrant glycosylation associated with enzymes as cancer biomarkers as well. PMID:21906357

  15. Properties of the Nucleus, Dust Coma, and Gas Coma of Comet 29P/Schwassmann-Wachmann 1 As Observed By WISE/NEOWISE

    NASA Astrophysics Data System (ADS)

    Fernandez, Yanga R.; Bauer, J. M.; Lisse, C. M.; Grav, T.; Mainzer, A. K.; Masiero, J. R.; Walker, R. G.; Meech, K. J.

    2012-10-01

    We present our analysis of mid-infrared imaging of comet 29P/Schwassmann-Wachmann 1 by the Wide-field Infrared Survey Explorer (WISE) [1,2]. The comet was observed on May 3-4, 2010 - not in strong outburst - with imaging at 3.4, 4.6, 12, and 22 microns (a.k.a. bands W1, W2, W3, and W4). W1 and W2 were sensitive to the reflected-sunlight continuum and W3 and W4 to thermal emission. The comet's coma was seen in all bands, with a point-source clearly embedded in W1, W3, and W4 imaging. A coma-fitting technique [3,4] let us photometrically extract this point-source from the images, thereby letting us measure the nucleus's size, W1-band geometric albedo, and infrared beaming. The dust coma was most clearly seen at bands W1, W3, and W4, letting us estimate the dust production rate, extract spatially-resolved information about the dust albedo and color temperature, and constrain the grain composition and size distribution. W2 imaging shows a coma whose radial surface-brightness profile and photometry suggest we are seeing a gas component, specifically emission from CO and/or CO2, i.e. high-abundance species with emission lines within the bandpass. This lets us estimate 29P’s gas production rate and dust-to-gas ratio independently from earlier methods. We present a comparison of our dust, gas, and nucleus results to those from earlier studies of this comet. References: [1] E. L. Wright et al. 2010, AJ, 140, 1868. [2] A. K. Mainzer et al. 2011, ApJ, 731, 53. [3] C. M. Lisse et al. 1999, Icarus, 140, 189. [4] P. L. Lamy et al. 2004, in Comets II, pp. 223-264. Acknowledgements: This publication makes use of data products from (1) WISE, which is a joint project of UCLA and JPL/Caltech, funded by NASA; and (2) NEOWISE, which is a project of JPL/Caltech, funded by the Planetary Science Division of NASA.

  16. DEEP GALEX OBSERVATIONS OF THE COMA CLUSTER: SOURCE CATALOG AND GALAXY COUNTS

    SciTech Connect

    Hammer, D.; Hornschemeier, A. E.; Miller, N.; Jenkins, L.; Mobasher, B.; Smith, R.; Arnouts, S.; Milliard, B.

    2010-09-15

    We present a source catalog from a deep 26 ks Galaxy Evolution Explorer (GALEX) observation of the Coma cluster in the far-UV (FUV; 1530 A) and near-UV (NUV; 2310 A) wavebands. The observed field is centered {approx}0.{sup 0}9 (1.6 Mpc) southwest of the Coma core in a well-studied region of the cluster known as 'Coma-3'. The entire field is located within the apparent virial radius of the Coma cluster, and has optical photometric coverage with Sloan Digital Sky Survey (SDSS) and deep spectroscopic coverage to r {approx} 21. We detect GALEX sources to NUV = 24.5 and FUV = 25.0, which corresponds to a star formation rate of {approx}10{sup -3} M {sub sun} yr{sup -1} for galaxies at the distance of Coma. We have assembled a catalog of 9700 galaxies with GALEX and SDSS photometry, including 242 spectroscopically confirmed Coma member galaxies that span a large range of galaxy types from giant spirals and elliptical galaxies to dwarf irregular and early-type galaxies. The full multi-wavelength catalog (cluster plus background galaxies) is {approx}80% complete to NUV = 23 and FUV = 23.5. The GALEX images presented here are very deep and include detections of many resolved cluster members superposed on a dense field of unresolved background galaxies. This required a two-fold approach to generating a source catalog: we used a Bayesian deblending algorithm to measure faint and compact sources (using SDSS coordinates as position prior), and used the GALEX pipeline catalog for bright and/or extended objects. We performed simulations to assess the importance of systematic effects (e.g., object blends, source confusion, Eddington Bias) that influence the source detection and photometry when using both methods. The Bayesian deblending method roughly doubles the number of source detections and provides reliable photometry to a few magnitudes deeper than the GALEX pipeline catalog. This method is free from source confusion over the UV magnitude range studied here; we estimate that

  17. Jet morphology and coma analysis of comet 103P/Hartley 2

    NASA Astrophysics Data System (ADS)

    Vaughan, Charles M.

    In 2010, comet 103P/Hartley 2 was observed pre- and post-perihelion using the George and Cynthia Mitchell Integral Field Spectrometer on the 2.7-m telescope at McDonald Observatory in Texas. Data for gaseous radicals C2, C3, CH, CN, and NH2 were collected over six nights from 15 July to 10 November. The spectral data were used to create coma maps for each of the observed species, and the maps were processed using radial and azimuthal mean division techniques to create enhanced images of the coma, revealing subtle morphological features. 340 enhanced coma images were created for each observation and species. Visual inspection reveals that the coma is heterogeneous between the five detected radicals, and statistical analyses verify this result. To compliment the ongoing investigation of Hartley 2 as studied by the EPOXI flyby mission, findings from other researchers (Belton et al., 2012; Syal et al., 2012; and Thomas et al., 2012) are used to characterize the nucleus spin state and identify dust jet locations on the nucleus. With rotational period measurements from EPOXI, dust jet vectors on the nucleus surface are rotated to relevant observation times in November to compare the computed jet directions with the radical densities in the coma. Dust jet sites on the smaller nucleus lobe show a stronger correlation with high radical concentrations than the dust sites on the larger nucleus lobe. Production rates for potential parentage of radical species are calculated using the radial outflow Haser model (Haser, 1957), which are compared to mixing ratios relative to water from separate campaigns to constrain parentage. NH3 is likely the sole producer of NH2, whereas CN may be produced from a combination of HCN, C2N2, and CH3CN. Traditional parentage of C2, C3, and CH do not yield acceptable fits or suitable mixing ratios with the Haser model, and it is possible that extended coma ices having relatively short scale lengths greatly contribute to production of these

  18. THE HST/ACS COMA CLUSTER SURVEY. II. DATA DESCRIPTION AND SOURCE CATALOGS

    SciTech Connect

    Hammer, Derek; Verdoes Kleijn, Gijs; Den Brok, Mark; Peletier, Reynier F.; Hoyos, Carlos; Balcells, Marc; Aguerri, Alfonso L.; Ferguson, Henry C.; Goudfrooij, Paul; Carter, David; Guzman, Rafael; Smith, Russell J.; Lucey, John R.; Graham, Alister W.; Trentham, Neil; Peng, Eric; Puzia, Thomas H.; Jogee, Shardha; Batcheldor, Dan; Bridges, Terry J.

    2010-11-15

    The Coma cluster, Abell 1656, was the target of an HST-ACS Treasury program designed for deep imaging in the F475W and F814W passbands. Although our survey was interrupted by the ACS instrument failure in early 2007, the partially completed survey still covers {approx}50% of the core high-density region in Coma. Observations were performed for 25 fields that extend over a wide range of cluster-centric radii ({approx}1.75 Mpc or 1{sup 0}) with a total coverage area of 274 arcmin{sup 2}. The majority of the fields are located near the core region of Coma (19/25 pointings) with six additional fields in the southwest region of the cluster. In this paper, we present reprocessed images and SEXTRACTOR source catalogs for our survey fields, including a detailed description of the methodology used for object detection and photometry, the subtraction of bright galaxies to measure faint underlying objects, and the use of simulations to assess the photometric accuracy and completeness of our catalogs. We also use simulations to perform aperture corrections for the SEXTRACTOR Kron magnitudes based only on the measured source flux and its half-light radius. We have performed photometry for {approx}73,000 unique objects; approximately one-half of our detections are brighter than the 10{sigma} point-source detection limit at F814W = 25.8 mag (AB). The slight majority of objects (60%) are unresolved or only marginally resolved by ACS. We estimate that Coma members are 5%-10% of all source detections, which consist of a large population of unresolved compact sources (primarily globular clusters but also ultra-compact dwarf galaxies) and a wide variety of extended galaxies from a cD galaxy to dwarf low surface brightness galaxies. The red sequence of Coma member galaxies has a color-magnitude relation with a constant slope and dispersion over 9 mag (-21 < M {sub F814W} < -13). The initial data release for the HST-ACS Coma Treasury program was made available to the public in 2008

  19. Variant of the anastigmatic telescope with three mirrors for back focal length.

    PubMed

    Herrera, J; Vázquez, S; Luna, E; Salas, L; Nuñez, J; Sohn, E; Ruiz, E

    2011-05-01

    In this paper, an optical design is presented for an anastigmatic telescope with back focal length corrected with exact ray tracing to eliminate spherical, coma, and astigmatism aberrations. The telescope is formed of three conical mirrors, two of them polished on the same substratum. The optical design is divided into three stages: we began the design obtaining the Gaussian parameters in a first-order solution; posteriorly, were obtained analytically the three mirrors' asphericity in a third-order design. The final design stage consists of the implementation of the Fermat's principle, the Abbe sine condition, and the Coddington equations for the exact correction for the three aforementioned aberrations. PMID:21532673

  20. On-orbit performance of the Hubble Space Telescope optical control system.

    PubMed

    Basedow, R; Ftaclas, C; Crout, R; Nonnenmacher, A

    1993-04-01

    On-orbit data are used to examine the performance of the Hubble Space Telescope optical control system. The precision, relative accuracy, and absolute accuracy of the off-axis Wavefront-Sensor measurements are evaluated and compared with design requirements. The internal stability of the sensors is better than 0.006 microm rms over five years, including launch. Random errors are estimated to be within 0.01 microm rms. Systematic errors are present in the estimates of focus, spherical, and coma aberrations, but none has been identified for astigmatism. Primary-mirror spherical aberration is believed to be the probable cause of all subspecification performances.

  1. Composition of Dust Particles Collected in the Inner Coma of Comet 67P/Churymumo-Gerasimenko by Rosetta

    NASA Astrophysics Data System (ADS)

    Hilchenbach, M.; Kissel, J.; Langevin, Y.; Briois, C.; Koch, A.; Schulz, R.; Silen, J.; Altobelli, N.; Altwegg, K.; Baklouti, D.; Bardyn, A.; Colangeli, L.; Cottin, H.; Engrand, C.; Fischer, H.; Fray, N.; Glasmachers, A.; Grün, E.; Haerendel, G.; Henkel, H.; Höfner, H.; Hornung, K.; Jessberger, E.-K.; Lehto, H.; Ligier, N.; Martin, P.; Merouane, S.; Orthous-Daunay, F.-R.; Paquette, J.; Raulin, F.; Le Roy, L.; Rynö, J.; Silieström, S.; Steiger, W.; Stenzel, O.; Stephan, T.; Thirkell, L.; Thomas, R.; Torkar, K.; Varmuza, K.; Wanczek, K.-P.; Zaprudin, B.

    2016-08-01

    The dust particle instrument COSIMA - COmetary Secondary Ion Mass Analyser - on board ESA’s ROSETTA mission is collecting and analyzing dust particles in the inner coma of Jupiter-family comet 67P/Churyumov-Gerasimenko.

  2. Coma Morphology Due to an Extended Active Region and Implications for the Spin State of Comet Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Samarasinha, Nalin H.

    2000-01-01

    We show that the circular character of continuum structures observed in the coma of comet Hale-Bopp around the perihelion passage is most likely due to a dust jet from a large extended active region on the surface. Coma morphology due to a wide jet is different from that due to a narrow jet. The latter shows foreshortening effects due to observing geometry, wider jet produces more circular features. This circularization effect provides a self-consistent explanation for the evolution of near-perihelion coma morphology. No changes in the direction of the rotational angular momentum vector are required during this period in contrast to the models of Schleicher et al. This circularization effect also enables us to produce near-circular coma features in the S-E quadrant during 1997 late February and therefore questions the basic premise on which Sekanina bases his morphological arguments for a gravitationally bound satellite nucleus.

  3. A Case of Myxedema Coma Presenting as a Brain Stem Infarct in a 74-Year-Old Korean Woman

    PubMed Central

    Ahn, Ji Yun; Kwon, Hyuk-Sool; Ahn, Hee Chol

    2010-01-01

    Myxedema coma is the extreme form of untreated hypothyroidism. In reality, few patients present comatose with severe myxedema. We describe a patient with myxedema coma which was initially misdiagnosed as a brain stem infarct. She presented to the hospital with alteration of the mental status, generalized edema, hypothermia, hypoventilation, and hypotension. Initially her brain stem reflexes were absent. After respiratory and circulatory support, her neurologic status was not improved soon. The diagnosis of myxedema coma was often missed or delayed due to various clinical findings and concomitant medical condition and precipitating factors. It is more difficult to diagnose when a patient has no medical history of hypothyroidism. A high index of clinical suspicion can make a timely diagnosis and initiate appropriate treatment. We report this case to alert clinicians considering diagnosis of myxedema coma in patients with severe decompensated metabolic state including mental change. PMID:20808690

  4. Aberration correction by maximizing generalized sharpness metrics.

    PubMed

    Fienup, J R; Miller, J J

    2003-04-01

    The technique of maximizing sharpness metrics has been used to estimate and compensate for aberrations with adaptive optics, to correct phase errors in synthetic-aperture radar, and to restore images. The largest class of sharpness metrics is the sum over a nonlinear point transformation of the image intensity. How the second derivative of the point nonlinearity varies with image intensity determines the effects of various metrics on the imagery. Some metrics emphasize making shadows darker, and other emphasize making bright points brighter. One can determine the image content needed to pick the best metric by computing the statistics of the image autocorrelation or of the Fourier magnitude, either of which is independent of the phase error. Computationally efficient, closed-form expressions for the gradient make possible efficient search algorithms to maximize sharpness.

  5. Overlapped Fourier coding for optical aberration removal

    PubMed Central

    Horstmeyer, Roarke; Ou, Xiaoze; Chung, Jaebum; Zheng, Guoan; Yang, Changhuei

    2014-01-01

    We present an imaging procedure that simultaneously optimizes a camera’s resolution and retrieves a sample’s phase over a sequence of snapshots. The technique, termed overlapped Fourier coding (OFC), first digitally pans a small aperture across a camera’s pupil plane with a spatial light modulator. At each aperture location, a unique image is acquired. The OFC algorithm then fuses these low-resolution images into a full-resolution estimate of the complex optical field incident upon the detector. Simultaneously, the algorithm utilizes redundancies within the acquired dataset to computationally estimate and remove unknown optical aberrations and system misalignments via simulated annealing. The result is an imaging system that can computationally overcome its optical imperfections to offer enhanced resolution, at the expense of taking multiple snapshots over time. PMID:25321982

  6. Patterns of Chromosomal Aberrations in Solid Tumors.

    PubMed

    Grade, Marian; Difilippantonio, Michael J; Camps, Jordi

    2015-01-01

    Chromosomal abnormalities are a defining feature of solid tumors. Such cytogenetic alterations are mainly classified into structural chromosomal aberrations and copy number alterations, giving rise to aneuploid karyotypes. The increasing detection of these genetic changes allowed the description of specific tumor entities and the associated patterns of gene expression. In fact, tumor-specific landscapes of gross genomic copy number changes, including aneuploidies of entire chromosome arms and chromosomes result in a global deregulation of the transcriptome of cancer cells. Furthermore, the molecular characterization of cytogenetic abnormalities has provided insights into the mechanisms of tumorigenesis and has, in a few instances, led to the clinical implementation of effective diagnostic and prognostic tools, as well as treatment strategies that target a specific genetic abnormality. PMID:26376875

  7. Aberrant pancreatic ductal organisation: a case report.

    PubMed

    Goel, Shivi; Rustagi, Shaifaly Madan; Saha, Susmita; Mehta, Vandana; Suri, Rajesh Kumar; Rath, Gayatri

    2015-07-01

    Anomalous pancreatic ductal system has always enthralled the anatomists, surgeons, gastroenterologists and radiologists alike. With the growing use of MRCP, ERCP and endoscopic and surgical procedures, the knowledge of anatomical aberrations of pancreaticobiliary tract becomes extremely important. Moreover, the anomalous pancreatic duct morphology may be responsible for atypical gastrointestinal complains. We report an exceptionally rare case of two accessory ventral pancreatic ducts opening separately into the common bile duct proximal to the hepato pancreatic ampulla. Concomitant occurrence of an ectopic major duodenal papilla, 3.8 cm distal to the pyloric end of stomach was also seen. Moreover, the accessory pancreatic duct and the minor duodenal papilla were absent. Clinical implications and embryological description of these rare anomalies are discussed. Awareness of such rare morphological variants can go a long way in assisting effective patient management.

  8. Patterns of Chromosomal Aberrations in Solid Tumors

    PubMed Central

    Grade, Marian; Difilippantonio, Michael J.

    2016-01-01

    Chromosomal abnormalities are a defining feature of solid tumors. Such cytogenetic alterations are mainly classified into structural chromosomal aberrations and copy number alterations, giving rise to aneuploid karyotypes. The increasing detection of these genetic changes allowed the description of specific tumor entities and the associated patterns of gene expression. In fact, tumor-specific landscapes of gross genomic copy number changes, including aneuploidies of entire chromosome arms and chromosomes result in a global deregulation of the transcriptome of cancer cells. Furthermore, the molecular characterization of cytogenetic abnormalities has provided insights into the mechanisms of tumorigenesis and has, in a few instances, led to the clinical implementation of effective diagnostic and prognostic tools, as well as treatment strategies that target a specific genetic abnormality. PMID:26376875

  9. Structural aberrations in group A Staphylococcus bacteriophages.

    PubMed Central

    Ackermann, H W; Berthiaume, L; Sonea, S; Kasatiya, S S

    1976-01-01

    Six related Staphylococcus phages spontaneously produced various abnormal head and tail structures: (i) giant capsids which were tailed and apparently contained nucleic acid; (ii) regular and irregular smooth polyheads; (iii) heads and polyheads with wavy outlines; (iv) mottled heads and polyheads; (v) abnormally long and short tails; and (vi) "double capsids" connected by a small bridge. Some of these structures are rare, or have not yet been reported. The frequency os specific aberrant particles varied from one phage to another. Length distribution of smooth irregular polyheads and of abnormal tails indicated that these structures assemble at random from protein synthesized in excess. These phages represent an interesting model for genetic and morphogentic studies. Images PMID:131865

  10. Aberrant diagnoses by individual surgical pathologists.

    PubMed

    Wakely, S L; Baxendine-Jones, J A; Gallagher, P J; Mullee, M; Pickering, R

    1998-01-01

    Methods of auditing the performance of histopathologists, such as external and internal quality assurance, clinicopathological conferences, and "double-reporting" of microscopic slides, show significant diagnostic errors in at least 1.2% of reports. Although some of these are in well-recognized areas of difficulty, such as melanoma or lymphoma, most errors are in common biopsy specimens. We have developed a method that compares diagnostic patterns of individual histopathologists. This aims to identify specific diagnoses that a pathologist makes more or less frequently than other colleagues and enables the individual to reflect on his or her own histologic expertise in reporting on specific biopsy results. The bottom line diagnoses of transurethral resection of prostate specimens; rectal, gastric, and bladder biopsy samples; and endometrial curettages were analyzed retrospectively. Analyses were performed on diagnoses made by at least 15 pathologists on each specimen type and expressed as a standardized ratio (SR) with 95% confidence intervals (CI). An SR of 1.0 indicated a pattern of diagnosis matching the combined pattern of other colleagues. An SR <1.0 indicated relative "underdiagnosis" and an SR >1.0 indicated relative "overdiagnosis." Diagnostic rates of individual pathologists whose CIs did not straddle the value of 1.0 were considered aberrant, although not necessarily incorrect. The 47 of 226 (20.8%) aberrant SRs included four pathologists' diagnoses of prostatic carcinoma, three each of endometrial, rectal, and bladder carcinoma, and one of gastric malignancy. This method, which could easily be automated and used regionally or nationally, should provide pathologists with a profile of their diagnostic patterns in comparison with their peers.

  11. Congenital Aberrant Tearing: A Re-Look

    PubMed Central

    Miller, Marilyn T.; Strömland, Kerstin; Ventura, Liana

    2008-01-01

    Purpose Congenital aberrant tearing is characterized by tearing when eating (“crocodile tears”), lack of emotional tearing, or both. Most reported cases are associated with Duane syndrome. In our previous studies we observed aberrant tearing in individuals with thalidomide embryopathy and Möbius sequence. This report summarizes the literature on the subject and adds 3 new studies that give information on this unusual condition. Methods Twenty-eight individuals with Möbius sequence were interviewed about tearing symptoms at a support group meeting in Italy. In Sweden 30 adults primarily from the original thalidomide series were reexamined. In this latter study, a Schirmer test was done at baseline and repeated 5 minutes after eating. Twenty families in Brazil who have children with Möbius sequence were questioned about tearing symptoms and exposure to misoprostol during pregnancy. Results In the 28 Italian individuals, either “crocodile tears” or lack of emotional tearing was noted in 7 cases. In the thalidomide study, 10 of 30 patients had tearing when eating and 7 had no emotional tearing. Low Schirmer scores or increased tearing after eating was noted in a few asymptomatic individuals. Among the 20 Brazilian children with Möbius sequence, 10 had some tearing abnormality. Conclusion Congenital anomalous lacrimation is rare but usually associated with Duane syndrome or abduction deficits, as in Möbius sequence and, less frequently, facial nerve palsy. Studies implicate an early insult in development at 4 to 6 weeks. At that time the facial nerve, sixth nerve, and lacrimal nucleus are in close proximity in the embryo. PMID:19277226

  12. Artificial selection on chill-coma recovery time in Drosophila melanogaster: Direct and correlated responses to selection.

    PubMed

    Gerken, Alison R; Mackay, Trudy F C; Morgan, Theodore J

    2016-07-01

    Artificial selection can be used to create populations with extreme phenotypic responses to environmental stressors. When artificial selection is applied to a single component of a stress response, this selection may result in correlated responses in other stress responses, a phenomenon called cross-tolerance, which is ultimately controlled by the genetic correlations among traits. We selected for extreme responses to cold tolerance by selecting for chill-coma recovery time from a single temperate population of Drosophila melanogaster. Chill-coma recovery time is a common metric of low, but non-lethal, cold temperature tolerance. Replicated divergent artificial selection was applied to a genetically variable base population for 31 generations, resulting in two cold resistant, two cold susceptible, and two unselected control lines. To quantify the relationship between selection on chill-coma recovery and other metrics of thermal performance, we also measured survivorship after acute cold exposure, survivorship after chronic cold exposure, survivorship after cold exposure following a pre-treatment period (rapid cold hardening), starvation tolerance, and heat tolerance. We find that chill-coma recovery time is heritable within this population and that there is an asymmetric response to increased and decreased chill-coma recovery time. Surprisingly, we found no cross-tolerances between selection on chill-coma recovery time and the other environmental stress response traits. These results suggest that although artificial selection has dramatically altered chill-coma recovery time, the correlated response to selection on other stress response phenotypes has been negligible. The lack of a correlated response suggests that chill-coma recovery time in these selection lines is likely genetically independent from measures of cold survivorship tested here. PMID:27264892

  13. Artificial selection on chill-coma recovery time in Drosophila melanogaster: Direct and correlated responses to selection.

    PubMed

    Gerken, Alison R; Mackay, Trudy F C; Morgan, Theodore J

    2016-07-01

    Artificial selection can be used to create populations with extreme phenotypic responses to environmental stressors. When artificial selection is applied to a single component of a stress response, this selection may result in correlated responses in other stress responses, a phenomenon called cross-tolerance, which is ultimately controlled by the genetic correlations among traits. We selected for extreme responses to cold tolerance by selecting for chill-coma recovery time from a single temperate population of Drosophila melanogaster. Chill-coma recovery time is a common metric of low, but non-lethal, cold temperature tolerance. Replicated divergent artificial selection was applied to a genetically variable base population for 31 generations, resulting in two cold resistant, two cold susceptible, and two unselected control lines. To quantify the relationship between selection on chill-coma recovery and other metrics of thermal performance, we also measured survivorship after acute cold exposure, survivorship after chronic cold exposure, survivorship after cold exposure following a pre-treatment period (rapid cold hardening), starvation tolerance, and heat tolerance. We find that chill-coma recovery time is heritable within this population and that there is an asymmetric response to increased and decreased chill-coma recovery time. Surprisingly, we found no cross-tolerances between selection on chill-coma recovery time and the other environmental stress response traits. These results suggest that although artificial selection has dramatically altered chill-coma recovery time, the correlated response to selection on other stress response phenotypes has been negligible. The lack of a correlated response suggests that chill-coma recovery time in these selection lines is likely genetically independent from measures of cold survivorship tested here.

  14. Jet Morphology and Coma Analysis of 103P/Hartley 2

    NASA Astrophysics Data System (ADS)

    Vaughan, Charles; Pierce, D.; Dorman, G.; Cochran, A.

    2012-10-01

    We have observed comet 103P/Hartley 2 using the George and Cynthia Mitchell Spectrograph (formerly VIRUS-P) on the 2.7 m telescope at McDonald Observatory (Hill et al. 2008). Data for CN, C2, C3, and NH2 were collected over six nights from 2010 July 15 to November 10. The data were processed to form images of the coma for each of the observed species. We have performed azimuthal average division on each of the coma images to examine jet morphology and have investigated the nature of the production of the radical species using our modified vectorial model (Ihalawela et al. 2011). This work enhances the ongoing investigation of the chemistry and outgassing behavior of Hartley 2 as studied by the EPOXI flyby mission.

  15. 67P/Churyumov-Gerasimenko: the dust coma as seen through Rosetta/OSIRIS

    NASA Astrophysics Data System (ADS)

    Tubiana, Cecilia; Bertini, Ivano; Güttler, Carsten; Sierks, Holger

    2016-04-01

    OSIRIS, the Optical, Spectroscopic, and Infrared Remote Imaging System onboard Rosetta, is imaging the nucleus and the coma of 67/Churyumov-Gerasimenko since the beginning of post-hibernation operations in March 2014. We focus here on dust studies performed with OSIRIS. Images obtained in different filters in the visible wavelength range are used to study the unresolved coma, investigating its diurnal and seasonal variations and providing insights into the dust composition. Individual grains are characterized in terms of color, size, distance, light curves, orbits. Images acquired spanning the phase angle range 0-165 deg are used to determine the dust phase function in different colors and to investigate the intimate nature of cometary dust particles by solving the inverse scattering problem.

  16. Linear structures in the core of the Coma cluster of galaxies.

    PubMed

    Sanders, J S; Fabian, A C; Churazov, E; Schekochihin, A A; Simionescu, A; Walker, S A; Werner, N

    2013-09-20

    The hot x-ray-emitting plasma in galaxy clusters is predicted to have turbulent motion, which can contribute around 10% of the cluster's central energy density. We report deep Chandra X-ray Observatory observations of the Coma cluster core, showing the presence of quasi-linear high-density arms spanning 150 kiloparsecs, consisting of low-entropy material that was probably stripped from merging subclusters. Two appear to be connected with a subgroup of galaxies at a 650-kiloparsec radius that is merging into the cluster, implying coherence over several hundred million years. Such a long lifetime implies that strong isotropic turbulence and conduction are suppressed in the core, despite the unrelaxed state of the cluster. Magnetic fields are presumably responsible. The structures seen in Coma present insight into the past billion years of subcluster merger activity.

  17. Magnetic field draping in the Comet Halley coma - Comparison of VEGA observations with computer simulations

    NASA Astrophysics Data System (ADS)

    Schwingenschuh, K.; Riedler, W.; Yeroshenko, Ye.; Phillips, J. L.; Russell, C. T.; Luhmann, J. G.; Fedder, J. A.

    1987-06-01

    During the Vega-1 encounter with Comet Halley, the magnetometer observed draping and compression of the interplanetary magnetic field. These are reproduced well by a three-dimensional MHD simulation of the cometary interaction. Rotations in the magnetic field similar to those at closest approach are also observed 2.75 hours earlier. It is suggested that both rotations correspond to the same IMF interval and that the spacecraft had overtaken the plasma and encountered 'older' magnetic field as it penetrated the coma. Analysis of the MHD model indicates that it should take about 3 to 5 hours for a solar wind parcel to pass from the unperturbed solar wind to Vega-1 at closest approach. A simulated magnetic field profile composed of nested sections for different IMF orientations closely resembles the observations. This result supports the hypothesis of layered magnetic orientations in the coma.

  18. VizieR Online Data Catalog: Hα3 V. Coma cluster (Gavazzi+, 2015)

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Consolandi, G.; Viscardi, E.; Fossati, M.; Savorgnan, G.; Fumagalli, M.; Gutierrez, L.; Hernandez-Toledo, H.; Boselli, A.; Giovanelli, R.; Haynes, M. P.

    2015-05-01

    Our sample is drawn from the 360-square degree region 10hComa supercluster, including half of the Coma cluster. This region has been fully mapped by ALFALFA (Haynes et al., 2011, Cat. J/AJ/142/170), which provides us with a complete sample of HI selected galaxies, with HI masses as low as 109-9.5M⊙. The goal of the Hα3 survey is to follow up with Hα imaging observations the ALFALFA targets with high signal-to-noise ratio (typically S/N>6.5), and with consistent detection between two independent polarizations (code=1 sources in Haynes et al., 2011, Cat. J/AJ/142/170). We will refer to these targets as the HI or radio targets. (3 data files).

  19. Spectroscopic studies of the molecular parentage of radical species in cometary comae

    NASA Astrophysics Data System (ADS)

    Lewis, Benjamin; Pierce, Donna; Cochran, Anita

    2015-11-01

    We have observed several comets using an integral-field unit spectrograph (the George and Cynthia Mitchell Spectrograph) on the 2.7m Harlan J. Smith telescope at McDonald Observatory. Full-coma spectroscopic images were obtained for various radical species (C2, C3, CH, CN, NH2). By constructing azimuthal average profiles from the full-coma spectroscopic images we can test Haser model parameters with our observations. The Haser model was used to determine production rates and possible parent lifetimes that would be consistent with the model. By iterating through a large range of possible parents lifetimes, we can see what range of values in which the Haser model is consistent with observations. Also, this type of analysis gives us perspective on how sensitive the model's fit quality is to changes in parent lifetimes. Here, we present the work completed to date, and we compare our results to other comet taxonomic surveys.

  20. CCD imaging of the inner coma jets of comet P/Halley

    NASA Technical Reports Server (NTRS)

    Boswell, James; Hughes, David W.

    1992-01-01

    We analyze the inner coma section of a CCD image of comet P/Halley taken at 1807 UT on 13 March 1986 using a C2 filter (wavelength 5000 to 5200A, half maximum) with the 3.8 m Anglo Australian Telescope at Siding Springs, Australia. Atmospheric turbulence leads to a spreading of the image detail and this produces a blander image of the inner coma region with a slower radial decrease of brightness in comparison to the unaffected image. We remove this smearing by utilizing the point spread function of a star on the same CCD image. Jets were then revealed by removing the average background. Analysis of the jet structure enabled us to estimate the lower limit of the parent molecule velocity. This is found to be 0.3 km s(exp -1).

  1. The origin of complex organic ions in the coma of Comet Halley

    NASA Technical Reports Server (NTRS)

    Mitchell, D. L.; Lin, R. P.; Carlson, C. W.; Korth, A.; Reme, H.; Mendis, D. A.

    1992-01-01

    The Giotto-PICCA instrument has obtained heavy-ion mass spectra in the inner coma of Comet Halley; the spectra exhibit a series of distinct mass groups separated by a constant about 15 amu, and extending to at least 120 amu, whose pattern is typical of CHON molecules. It is found that neither coma gas-phase chemistry nor UV photon, solar wind particle, or cosmic irradiation of the nucleus in its current orbit can generate enough heavy molecules to account for the PICCA abundances. It is suggested that these abundances may be supplied by UV and cosmic irradiation of the icy, precometary grains within interstellar molecular clouds and/or the protosolar nebula.

  2. [Rare consciousness disturbances in toxicological practice: akinetic mutism, somnambulism, locked-in syndrome, and psychogenic coma].

    PubMed

    Ciszowski, Krzysztof; Mietka-Ciszowska, Aneta

    2013-01-01

    The toxicity of xenobiotics can result inrare disorders of consciousness, such as akinetic mutism and somnambulism as well as syndromes mimicking consciousness disturbances, such as locked-in syndrome and psychogenic coma. Akinetic mutism is a condition characterized by a lack of spontaneous movements and little or no vocalization. Somnambulism include performing of complex motor activity in an automatic manner during deep sleep, without any awareness of its execution. The locked-in syndrome is a state with quadriplegia coexisting with cranial nerves palsies and mutism, but with fully preserved consciousness. Psychogenic coma is a condition in which the patient has preserved level of consciousness and awareness, but does not communicate with theenvironment and does not exhibit the external manifestations of consciousness. This paper presents the etiology, clinical characteristics, as well as diagnostic and therapeutic issues for the above syndromes. PMID:24466703

  3. [Rare consciousness disturbances in toxicological practice: akinetic mutism, somnambulism, locked-in syndrome, and psychogenic coma].

    PubMed

    Ciszowski, Krzysztof; Mietka-Ciszowska, Aneta

    2013-01-01

    The toxicity of xenobiotics can result inrare disorders of consciousness, such as akinetic mutism and somnambulism as well as syndromes mimicking consciousness disturbances, such as locked-in syndrome and psychogenic coma. Akinetic mutism is a condition characterized by a lack of spontaneous movements and little or no vocalization. Somnambulism include performing of complex motor activity in an automatic manner during deep sleep, without any awareness of its execution. The locked-in syndrome is a state with quadriplegia coexisting with cranial nerves palsies and mutism, but with fully preserved consciousness. Psychogenic coma is a condition in which the patient has preserved level of consciousness and awareness, but does not communicate with theenvironment and does not exhibit the external manifestations of consciousness. This paper presents the etiology, clinical characteristics, as well as diagnostic and therapeutic issues for the above syndromes.

  4. Using Brief Assessments to Evaluate Aberrant Behavior Maintained by Attention.

    ERIC Educational Resources Information Center

    O'Reilly, Mark F.; Lancioni, Giulio E.; King, Lisa; Lally, Grainne; Dhomhnaill, Orla Nic

    2000-01-01

    Functional assessments were conducted for two Irish individuals with severe disabilities and aberrant behavior. A modified attention condition was introduced, which involved both parents interacting with a third person. Aberrant behavior occurred only in the modified attention condition. Successful treatment consisted of delivery of attention on a…

  5. Aberration analysis calculations for synchrotron radiation beamline design

    SciTech Connect

    McKinney, W.R.; Howells, M.; Padmore, H.A.

    1997-09-01

    The application of ray deviation calculations based on aberration coefficients for a single optical surface for the design of beamline optical systems is reviewed. A systematic development is presented which allows insight into which aberration may be causing the rays to deviate from perfect focus. A new development allowing analytical calculation of line shape is presented.

  6. Sextupole system for the correction of spherical aberration

    DOEpatents

    Crewe, A.V.; Kopf, D.A.

    In an electron beam device in which an electron beam is developed and then focused by a lens to a particular spot, there is provided a means for eliminating spherical aberration. A sextupole electromagnetic lens is positioned between two focusing lenses. The interaction of the sextupole with the beam compensates for spherical aberration. (GHT)

  7. Modified Matching Ronchi Test to Visualize Lens Aberrations

    ERIC Educational Resources Information Center

    Hassani, Kh; Ziafi, H. Hooshmand

    2011-01-01

    We introduce a modification to the matching Ronchi test to visualize lens aberrations with simple and inexpensive equipment available in educational optics labs. This method can help instructors and students to observe and estimate lens aberrations in real time. It is also a semi-quantitative tool for primary tests in research labs. In this work…

  8. Aerobraking strategies for the sample of comet coma earth return mission

    NASA Technical Reports Server (NTRS)

    Abe, Takashi; Kawaguchi, Jun'ichiro; Uesugi, Kuninori; Yen, Chen-Wan L.

    1990-01-01

    The results of a study to the validate the applicability of the aerobraking concept to the SOCCER (sample of comet coma earth return) mission using a six-DOF computer simulation of the aerobraking process are presented. The SOCCER spacecraft and the aerobraking scenario and power supply problem are briefly described. Results are presented for the spin effect, payload exposure problem, and sun angle effect.

  9. Human brain activity patterns beyond the isoelectric line of extreme deep coma.

    PubMed

    Kroeger, Daniel; Florea, Bogdan; Amzica, Florin

    2013-01-01

    The electroencephalogram (EEG) reflects brain electrical activity. A flat (isoelectric) EEG, which is usually recorded during very deep coma, is considered to be a turning point between a living brain and a deceased brain. Therefore the isoelectric EEG constitutes, together with evidence of irreversible structural brain damage, one of the criteria for the assessment of brain death. In this study we use EEG recordings for humans on the one hand, and on the other hand double simultaneous intracellular recordings in the cortex and hippocampus, combined with EEG, in cats. They serve to demonstrate that a novel brain phenomenon is observable in both humans and animals during coma that is deeper than the one reflected by the isoelectric EEG, and that this state is characterized by brain activity generated within the hippocampal formation. This new state was induced either by medication applied to postanoxic coma (in human) or by application of high doses of anesthesia (isoflurane in animals) leading to an EEG activity of quasi-rhythmic sharp waves which henceforth we propose to call ν-complexes (Nu-complexes). Using simultaneous intracellular recordings in vivo in the cortex and hippocampus (especially in the CA3 region) we demonstrate that ν-complexes arise in the hippocampus and are subsequently transmitted to the cortex. The genesis of a hippocampal ν-complex depends upon another hippocampal activity, known as ripple activity, which is not overtly detectable at the cortical level. Based on our observations, we propose a scenario of how self-oscillations in hippocampal neurons can lead to a whole brain phenomenon during coma. PMID:24058669

  10. Globular Clusters and Spur Clusters in NGC 4921, the Brightest Spiral Galaxy in the Coma Cluster

    NASA Astrophysics Data System (ADS)

    Lee, Myung Gyoon; Jang, In Sung

    2016-03-01

    We resolve a significant fraction of globular clusters (GCs) in NGC 4921, the brightest spiral galaxy in the Coma cluster. We also find a number of extended bright star clusters (star complexes) in the spur region of the arms. The latter are much brighter and bluer than those in the normal star-forming region, being as massive as 3 × 105 M⊙. The color distribution of the GCs in this galaxy is found to be bimodal. The turnover magnitudes of the luminosity functions of the blue (metal-poor) GCs (0.70 < (V - I) ≤ 1.05) in the halo are estimated V(max) = 27.11 ± 0.09 mag and I(max) = 26.21 ± 0.11 mag. We obtain similar values for NGC 4923, a companion S0 galaxy, and two Coma cD galaxies (NGC 4874 and NGC 4889). The mean value for the turnover magnitudes of these four galaxies is I(max) = 26.25 ± 0.03 mag. Adopting MI (max) = -8.56 ± 0.09 mag for the metal-poor GCs, we determine the mean distance to the four Coma galaxies to be 91 ± 4 Mpc. Combining this with the Coma radial velocity, we derive a value of the Hubble constant, H0 = 77.9 ± 3.6 km s-1 Mpc-1. We estimate the GC specific frequency of NGC 4921 to be SN = 1.29 ± 0.25, close to the values for early-type galaxies. This indicates that NGC 4921 is in the transition phase to S0s.

  11. Composition of Dust Particles Collected in the Coma of Comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Hilchenbach, Martin; Kissel, Jochen; Langevin, Yves; Briois, Christelle; Koch, Andreas; Schulz, Rita; Silen, Johan; Rynö, Jouni

    2016-04-01

    The COmetary Secondary Ion Mass Analyser (COSIMA) is a dust particle composition analyzing instrument onboard the ROSETTA spacecraft orbiting comet 67P/Churyumov-Gerasimenko since August 2014. COSIMA is collecting cometary particles on metal targets in the inner coma, identifies the collected particle on microscopic images and analyses their composition by secondary ion mass spectrometry. We will report on the high resolution mass spectra containing positive or negative ions of elements, organic molecules and molecular fragments originating from the cometary particle surfaces.

  12. Forty-seven Milky Way-sized, Extremely Diffuse Galaxies in the Coma Cluster

    NASA Astrophysics Data System (ADS)

    van Dokkum, Pieter G.; Abraham, Roberto; Merritt, Allison; Zhang, Jielai; Geha, Marla; Conroy, Charlie

    2015-01-01

    We report the discovery of 47 low surface brightness objects in deep images of a 3° × 3° field centered on the Coma cluster, obtained with the Dragonfly Telephoto Array. The objects have central surface brightness μ(g, 0) ranging from 24-26 mag arcsec-2 and effective radii r eff = 3''-10'', as measured from archival Canada-France-Hawaii Telescope images. From their spatial distribution we infer that most or all of the objects are galaxies in the Coma cluster. This relatively large distance is surprising as it implies that the galaxies are very large: with r eff = 1.5-4.6 kpc their sizes are similar to those of L * galaxies even though their median stellar mass is only ~6 × 107 M ⊙. The galaxies are relatively red and round, with langg - irang = 0.8 and langb/arang = 0.74. One of the 47 galaxies is fortuitously covered by a deep Hubble Space Telescope Advanced Camera for Surveys (ACS) observation. The ACS imaging shows a large spheroidal object with a central surface brightness μ475 = 25.8 mag arcsec-2, a Sérsic index n = 0.6, and an effective radius of 7'', corresponding to 3.4 kpc at the distance of Coma. The galaxy is not resolved into stars, consistent with expectations for a Coma cluster object. We speculate that these "ultra-diffuse galaxies" may have lost their gas supply at early times, possibly resulting in very high dark matter fractions.

  13. FORTY-SEVEN MILKY WAY-SIZED, EXTREMELY DIFFUSE GALAXIES IN THE COMA CLUSTER

    SciTech Connect

    Van Dokkum, Pieter G.; Merritt, Allison; Geha, Marla; Abraham, Roberto; Zhang, Jielai; Conroy, Charlie

    2015-01-10

    We report the discovery of 47 low surface brightness objects in deep images of a 3° × 3° field centered on the Coma cluster, obtained with the Dragonfly Telephoto Array. The objects have central surface brightness μ(g, 0) ranging from 24-26 mag arcsec{sup –2} and effective radii r {sub eff} = 3''-10'', as measured from archival Canada-France-Hawaii Telescope images. From their spatial distribution we infer that most or all of the objects are galaxies in the Coma cluster. This relatively large distance is surprising as it implies that the galaxies are very large: with r {sub eff} = 1.5-4.6 kpc their sizes are similar to those of L {sub *} galaxies even though their median stellar mass is only ∼6 × 10{sup 7} M {sub ☉}. The galaxies are relatively red and round, with (g – i) = 0.8 and (b/a) = 0.74. One of the 47 galaxies is fortuitously covered by a deep Hubble Space Telescope Advanced Camera for Surveys (ACS) observation. The ACS imaging shows a large spheroidal object with a central surface brightness μ{sub 475} = 25.8 mag arcsec{sup –2}, a Sérsic index n = 0.6, and an effective radius of 7'', corresponding to 3.4 kpc at the distance of Coma. The galaxy is not resolved into stars, consistent with expectations for a Coma cluster object. We speculate that these ''ultra-diffuse galaxies'' may have lost their gas supply at early times, possibly resulting in very high dark matter fractions.

  14. The Radio Luminosity Function and Galaxy Evolution in the Coma Cluster

    NASA Technical Reports Server (NTRS)

    Miller, Neal A.; Hornschemeier, Ann E.; Mabasher, Bahram; Brudgesm Terrry J.; Hudson, Michael J.; Marzke, Ronald O.; Smith, Russell J.

    2008-01-01

    We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 (mu)Jy per 4.4" beam, we identify 249 radio sources with optical counterparts brighter than r = 22 (equivalent to M(sub r) = -13 for cluster member galaxies). Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are restricted to radio luminosities between about 10(exp 21) and 10(exp 22) W/Hz, an interesting result given that star formation dominates field radio luminosity functions below about 10(exp 23) W/Hz. The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies (Mr less than or equals -20.5) make the largest contribution to the radio luminosity function at both the high (> approx. 3x10(exp 22) W/Hz) and low (< approx. 10(exp 21) W/Hz) ends. Through a stacking analysis of these optically-bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3x10(exp 19) W/Hz. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (M(sub r) approx. equals -14) dwarf ellipticals hosting strong radio AGN.

  15. Human brain activity patterns beyond the isoelectric line of extreme deep coma.

    PubMed

    Kroeger, Daniel; Florea, Bogdan; Amzica, Florin

    2013-01-01

    The electroencephalogram (EEG) reflects brain electrical activity. A flat (isoelectric) EEG, which is usually recorded during very deep coma, is considered to be a turning point between a living brain and a deceased brain. Therefore the isoelectric EEG constitutes, together with evidence of irreversible structural brain damage, one of the criteria for the assessment of brain death. In this study we use EEG recordings for humans on the one hand, and on the other hand double simultaneous intracellular recordings in the cortex and hippocampus, combined with EEG, in cats. They serve to demonstrate that a novel brain phenomenon is observable in both humans and animals during coma that is deeper than the one reflected by the isoelectric EEG, and that this state is characterized by brain activity generated within the hippocampal formation. This new state was induced either by medication applied to postanoxic coma (in human) or by application of high doses of anesthesia (isoflurane in animals) leading to an EEG activity of quasi-rhythmic sharp waves which henceforth we propose to call ν-complexes (Nu-complexes). Using simultaneous intracellular recordings in vivo in the cortex and hippocampus (especially in the CA3 region) we demonstrate that ν-complexes arise in the hippocampus and are subsequently transmitted to the cortex. The genesis of a hippocampal ν-complex depends upon another hippocampal activity, known as ripple activity, which is not overtly detectable at the cortical level. Based on our observations, we propose a scenario of how self-oscillations in hippocampal neurons can lead to a whole brain phenomenon during coma.

  16. Selections from 2015: Discovery of Diffuse Galaxies in the Coma Cluster

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-12-01

    Editors Note:In these last two weeks of 2015, well be looking at a few selections from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma ClusterPublished January 2015Main takeaway:Using the Dragonfly Telephoto Array, a team led by Pieter van Dokkum (Yale University) discovered 47 ultra-diffuse galaxies in the Coma galaxy cluster. These galaxies are very large, with half-light (effective) radii of 1.54.6 kpc, similar to that of the Milky Ways disk. But their stellar masses are a factor of 1000 lower than the Milky Ways, and theyre accordingly much dimmer.Plot of the effective radius versus the central surface brightness for the ultra-diffuse Coma cluster galaxies (red markers). These galaxies are similar in size to the Milky Ways disk (blue), but significantly dimmer. [Van Dokkum et al. 2015]Why its interesting:These galaxies make up an odd population. Why are their stellar masses so low? The authors posit that these objects may be failed galaxies that lost their gas after having formed their first generation of stars. Adding to the intrigue, the authors find that in order for these galaxies to hold themselves together at their current distance from the cluster core, they must have a whopping dark-matter fraction of 98%.About the discovery:These ultra-diffuse galaxies were actually discovered entirely by accident. Van Dokkum and collaborators observed the Coma cluster in a project to measure properties of the intra-cluster light and look for streams and tidal features. Surprisingly, their images revealed these faint, uncataloged galaxies.CitationPieter G. van Dokkum et al 2015 ApJ 798 L45. doi:10.1088/2041-8205/798/2/L45

  17. The interaction between the solar wind and the heterogeneous neutral gas coma of comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Rubin, Martin; Toth, Gabor; Tenishev, Valeriy; Fougere, Nicolas; Huang, Zhenguang

    2016-07-01

    Comets are surrounded by an extended gas and dust coma. Neutral particles are continuously ionized by solar irradiation and then picked-up by the solar wind. This leads to a complex interaction between the neutral gas coma and the solar wind, which changes over the course of the comet's orbit around the Sun. The European Space Agency's Rosetta spacecraft has been in orbit around comet 67P/Churyumov-Gerasimenko since August 2014. Rosetta carries several instruments to investigate the comet's nucleus and surrounding neutral gas coma and plasma. Part of the payload is the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) that consists of two mass spectrometers and a pressure sensor. ROSINA was designed to measure the neutral gas abundance and composition and low energy ions in the coma in situ. ROSINA observations have shown that the coma is very heterogeneous both in total density and composition of the neutral gas. This heterogeneity is driven in large part by the complex shape of the nucleus and the varying illumination conditions associated with the comet's rotation. In this presentation we will show the time-dependent distribution of the major volatiles around the comet constrained by ROSINA observations. Furthermore we will investigate the impact of the highly non-symmetric neutral gas coma on the interaction of the solar wind with the comet.

  18. Aberrations of the cathode objective lens up to fifth order.

    PubMed

    Tromp, R M; Wan, W; Schramm, S M

    2012-08-01

    In this paper we discuss a topic that was close to Prof. Gertrude Rempfer s interests for many years. On this occasion of her 100th birthday, we remember and honor Gertrude for her many outstanding contributions, and for the inspiring example that she set. We derive theoretical expressions for the aberration coefficients of the uniform electrostatic field up to 5th order and compare these with raytracing calculations for the cathode lens used in Low Energy Electron Microscopy and Photo Electron Emission Microscopy experiments. These higher order aberration coefficients are of interest for aberration corrected experiments in which chromatic (C(c)) and spherical (C₃) aberrations of the microscope are set to zero. The theoretical predictions are in good agreement with the results of raytracing. Calculations of image resolution using the Contrast Transfer Function method show that sub-nanometer resolution is achievable in an aberration corrected LEEM system. PMID:22188906

  19. Chaos in ocular aberration dynamics of the human eye

    PubMed Central

    Hampson, Karen M.; Mallen, Edward A. H.

    2012-01-01

    Since the characterization of the eye’s monochromatic aberration fluctuations in 2001, the power spectrum has remained the most widely used method for analyzing their dynamics. However, the power spectrum does not capture the complexities of the fluctuations. We measured the monochromatic aberration dynamics of six subjects using a Shack-Hartmann sensor sampling at 21 Hz. We characterized the dynamics using techniques from chaos theory. We found that the attractor embedding dimension for all aberrations, for all subjects, was equal to three. The embedding lag averaged across aberrations and subjects was 0.31 ± 0.07 s. The Lyapunov exponent of the rms wavefront error was positive for each subject, with an average value of 0.44 ± 0.15 µm/s. This indicates that the aberration dynamics are chaotic. Implications for future modeling are discussed. PMID:22567581

  20. Correction of spherochromatic aberration by system of thin layers

    NASA Astrophysics Data System (ADS)

    Miks, A.; Novak, J.

    2005-08-01

    It is well-known from the theory of optical imaging that optical systems generally show a presence of a chromatic aberration, which originates from a variation of the refraction index of glass on the wavelength of light. The chromatic aberration must be well corrected in order to obtain a good quality of optical image. In practice, it is used a proper combination of optical elements manufactured from different types of optical glass with a different dispersion in order to suppress the chromatic aberration. Our work shows a way how to correct spherochromatic aberration using a system of thin aspherical layers. The equations are derived for determination of parameters of thin layers with respect to a required spherochromatic aberration.

  1. Minimum change in spherical aberration that can be perceived

    PubMed Central

    Manzanera, Silvestre; Artal, Pablo

    2016-01-01

    It is important to know the visual sensitivity to optical blur from both a basic science perspective and a practical point of view. Of particular interest is the sensitivity to blur induced by spherical aberration because it is being used to increase depth of focus as a component of a presbyopic solution. Using a flicker detection-based procedure implemented on an adaptive optics visual simulator, we measured the spherical aberration thresholds that produce just-noticeable differences in perceived image quality. The thresholds were measured for positive and negative values of spherical aberration, for best focus and + 0.5 D and + 1.0 D of defocus. At best focus, the SA thresholds were 0.20 ± 0.01 µm and −0.17 ± 0.03 µm for positive and negative spherical aberration respectively (referred to a 6-mm pupil). These experimental values may be useful in setting spherical aberration permissible levels in different ophthalmic techniques.

  2. End-of-life and brain death in acute coma and disorders of consciousness.

    PubMed

    Greer, David M; Curiale, Gioacchino G

    2013-04-01

    Consulting neurologists are often asked to evaluate patients in acute nontraumatic coma. The authors review prognostication of functional outcomes, determining brain death, and managing end-of-life care. Prognostication of outcome after cardiac arrest in comatose patients is a frequently encountered scenario with high-stakes implications. However, current guidelines are limited by a failure to address the use of therapeutic hypothermia and thus may lead to overly pessimistic outcome prediction. Pupillary light responses and corneal reflexes remain highly predictive clinical signs of a poor prognosis. Motor responses have a high false-positive rate for predicting a poor outcome, especially in patients treated with therapeutic hypothermia. Ancillary testing with electroencephalography, somatosensory evoked potentials, serum neuron-specific enolase, and neuroimaging is often useful in predicting outcomes. Brain death is a clinical condition of irreversible coma of known cause with absent brainstem reflexes and apnea. An understanding of the value of confirmatory testing and the potential for confounding factors is essential in making a correct diagnosis. As coma carries a high mortality rate, neurologists must be capable of guiding goals of care, discussing end-of-life issues, and understanding organ-procurement procedures. PMID:23888399

  3. The quenching and survival of ultra diffuse galaxies in the Coma cluster

    NASA Astrophysics Data System (ADS)

    Yozin, C.; Bekki, K.

    2015-09-01

    We conduct the first self-consistent numerical simulations of a recently discovered population of 47 large, faint (ultra diffuse) galaxies, speculated to lie in the Coma cluster. With structural properties consistent with very large low surface brightness systems (LSBs; i.e. μ(g,0) <24 mag arcsec-2; re comparable to the Galaxy), the red colour ( ˜ 0.8) and assumed low metallicity of these objects compels us to consider a scenario in which these are underdeveloped galaxies whose early (z ≃ 2) accretion to an overdense environment quenched further growth. Our simulations demonstrate the efficacy of this scenario, with respect to available observational constraints, using progenitor galaxy models derived from scaling relations, and idealized tidal/hydrodynamical models of the Coma cluster. The apparent ubiquity of these objects in Coma implies they constitute an important galaxy population; we accordingly discuss their properties with respect to a ΛCDM cosmology, classical LSBs, and the role of baryonic physics in their early formation.

  4. Negative Ion Chemistry in the Coma of Comet 1P/Halley

    NASA Technical Reports Server (NTRS)

    Cordiner, M. A.; Charnley, S. B.

    2012-01-01

    Negative ions (anions) were identified in the coma of comet 1P/Halley from in-situ measurements performed by the Giotto spacecraft in 1986. These anions were detected with masses in the range 7-110 amu, but with insufficient mass resolution to permit unambiguous identification. We present details of a new chemical-hydrodynamic model for the coma of comet Halley that includes - for the first time - atomic and molecular anions, in addition to a comprehensive hydrocarbon chemistry. Anion number densities arc calculated as a function of radius in the coma, and compared with the Giotto results. Important anion production mechanisms arc found to include radiative electron attachment, polar photodissociation, dissociative electron attachment, and proton transfer. The polyyne anions C4H(-) and C6H(-) arc found to be likely candidates to explain the Giotto anion mass spectrum in the range 49-73 amu. Thc CN(-) anion probably makes a significant contribution to the mass spectrum at 26 amu. Larger carbon-chain anions such as C8H(1) can explain the peak near 100 amu provided there is a source of large carbon-chain-bearing molecules from the cometary nucleus.

  5. The orientation of rotation axes of disk galaxies in the Coma cluster

    NASA Astrophysics Data System (ADS)

    Wu, Guo-xiang; Hu, Fu-xing; Su, Hong-jun; Liu, Yong-zhen

    1998-02-01

    The rotation axes of 138 disk galaxies (94 S0, 44 S and Irr) within an area of 2.63° × 2.63° in the Coma cluster have been studied statistically and an anisotropic distribution is revealed. Relative to the isotropic distribution there are more S0 galaxies having their rotation axes parallel to the cluster plane and the projections of the axes on the cluster plane tend to make angles of about 45° with the direction from the cluster center. As to the S and Irr galaxies, their rotation axes tend to be either parallel or perpendicular to the cluster plane and their projections tend to be parallel to the direction fro the center. A morphological dependence of the distribution of rotation axes in Coma is confirmed and there is evidence for a possible luminosity dependence: the distribution for the fainter galaxies appear to be more anisotropic. Our results imply the presence of a preferential plane in Coma and tend to support the "pancake" scenario among the theories of galzxy and cluster formation.

  6. Evidence for methane and ammonia in the coma of comet P/Halley

    NASA Technical Reports Server (NTRS)

    Allen, M.; Delitsky, M.; Huntress, W.; Yung, Y.; Ip, W.-H.

    1987-01-01

    Methane and ammonia abundances in the coma of Halley are derived from Giotto ion mass spectrometer data using an Eulerian model of chemical and physical processes inside the contact surface to simulate Giotto high-intensity spectrometer ion mass spectral data for mass-to-charge ratios (m/q) from 15 to 19. The ratio m/q = 19/18 as a function of distance from the nucleus is not reproduced by a model for a pure water coma. It is necessary to include the presence of NH3, and uniquely NH3, in coma gases in order to explain the data. A ratio of production rates Q(NH3)/Q(H2O) = 0.01 = 0.02 results in model values approximating the Giotto data. Methane is identified as the most probable source of the distinct peak at m/q = 15. The observations are fit best with Q(CH4)/Q(Q2O) = 0.02. The chemical composition of the comet nucleus implied by these production rate ratios is unlike that of the outer planets. On the other hand, there are also significant differences from observations of gas phase interstellar material.

  7. Remote sensing of a comet nucleus with Rosetta/ROSINA in-situ coma measurements.

    NASA Astrophysics Data System (ADS)

    Dhooghe, Frederik; De Keyser, Johan

    2013-04-01

    Rosetta will rendez-vous with comet 67P/Churyumov-Gerasimenko in 2014 and will, among other tasks, study the physicochemical evolution of the cometary coma from onset of activity at large solar distances through perihelion at 1.2 AU. The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) allows the determination of both neutrals and positive ions in the coma. This research effort is focused on using in situ gas density measurements at small distances from the nucleus to get information about gas production rates and volatile composition at the nucleus, which reveals information about the nucleus and its origin. Furthermore, if sufficient data is available, a 2D activity map of the nucleus surface can be created and inputs concerning the nucleus surface can be valuable to assist in finding a suitable landing location for Philae, the Rosetta lander. The volatile outgassing rate and the surface composition at the nucleus can be accurately determined from in situ coma composition measurements provided accurate information is available concerning solar activity, the flow field and reactions that transform the neutral gas as it expands outward (e.g. photo-ionization). This contribution describes the principle of the data inversion technique and illustrates it with model data.

  8. THE PLANCK SUNYAEV-ZEL'DOVICH VERSUS THE X-RAY VIEW OF THE COMA CLUSTER

    SciTech Connect

    Fusco-Femiano, R.; Lapi, A.; Cavaliere, A.

    2013-01-20

    The Planck collaboration has recently published precise and resolved measurements of the Sunyaev-Zel'dovich (SZ) effect in Abell 1656 (the Coma cluster of galaxies), thus directly gauging the electron pressure profile in the intracluster plasma. On the other hand, such a quantity may be also derived from combining the density and temperature provided by X-ray observations of the thermal bremsstrahlung radiation emitted by the plasma. We find a model-independent tension between the SZ and the X-ray pressure, with the SZ one being definitely lower by 15%-20%. We propose that such a challenging tension can be resolved in terms of an additional, non-thermal support to the gravitational equilibrium of the intracluster plasma. This can be straightforwardly included in our Supermodel, so as to fit in detail the Planck SZ profile while being consistent with the X-ray observables. Possible origins of the non-thermal component include cosmic-ray protons, ongoing turbulence, and relativistic electrons; given the existing observational constraints on the first two options, here we focus on the third. For this to be effective, we find that the electron population must include not only an energetic tail accelerated to {gamma} {approx}> 10{sup 3} responsible for the Coma radiohalo, but also many more, lower energy electrons. The electron acceleration is to be started by merging events similar to those that provided the very high central entropy of the thermal intracluster plasma in Coma.

  9. Coma models of comet 19P/Borrelly for the Deep Space 1 encounter

    NASA Astrophysics Data System (ADS)

    Boice, Daniel; Wegmann, Rudolf; Goldstein, Raymond; Reisenfeld, Daniel; Jessop, Amber

    Water chemistry is central in understanding the physics and chemistry of comets. It is the major source of ions and electrons via photochemistry that further initiate key gas-phase and electron impact reactions, leading to the plethora of molecules and atoms seen in cometary comae. In this paper, relevant physico-chemical processes in the coma of comet 19P/Borrelly are identified within a modeling framework to understand in situ measurements from the ion mass spectrometer (PEPE) aboard the Deep Space 1 (DS1) spacecraft. Details of these processes are presented, from the collision-dominated inner coma to the solar wind interaction region. This work represents an extension of our previous work as a result of a thorough recalibration of the PEPE flight spare. The ion abundances show good agreement with the in situ data for the water-group ions, with the exception of H3 O+ . A bow shock was predicted and confirmed by DS1. (No penetration of the contact surface was predicted or observed.) The steady decrease of the plasma speed, electron and ion temperatures at closest approach are consistent with the in situ measurements of the PEPE instrument. This extensive modeling effort to investigate important cometary processes is highly relevant to past, on going, and future spacecraft missions to comets. Acknowledgements: We acknowledge funding and support from the SwRI Internal Research and Development Program and the NSF Planetary Astronomy Program.

  10. Catalog of Ultra-diffuse Galaxies in the Coma Clusters from Subaru Imaging Data

    NASA Astrophysics Data System (ADS)

    Yagi, Masafumi; Koda, Jin; Komiyama, Yutaka; Yamanoi, Hitomo

    2016-07-01

    We present a catalog of ultra-diffuse galaxies (UDGs) in the Coma cluster. UDGs are a subset of low surface brightness (SB) galaxies with very large effective radii defined by van Dokkum et al. We surveyed the Subaru data archive for deep Suprime-Cam/Subaru R-band images, and used data covering the 1.°7 × 2.°7 region of the Coma cluster. The data are ˜1 magnitude deeper than the data of van Dokkum et al (2015a) in limiting SB. This paper explains the details of our sample selection procedure. This UDG catalog includes positions, magnitudes, effective radii, mean and central SBs, and colors (when available). Comparisons with previous galaxy catalogs in the literature are performed, and we show that the current catalog is the largest for UDGs. We also discuss that most of the UDGs are members of the Coma cluster, and the major axis of the UDGs tends to align toward the cluster center (radial alignment). Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  11. Prevalence of Delirium and Coma In Mechanically Ventilated Patients Sedated With Dexmedetomidine or Propofol

    PubMed Central

    Jiang, Yi Kai (Johnny); Wang, Shan; Lam, Timothy S.; Hanna, Adel; DeMuro, Jonas P.; Calixte, Rose; Brathwaite, Collin E.M.

    2016-01-01

    Objective: To assess the prevalence of delirium and coma in mechanically ventilated patients sedated with dexmedetomidine or propofol alone; to evaluate the hospital length of stay for both treatment groups; and to evaluate the level of sedation, adverse effects, and hospital outcomes. Methods: Medical records were reviewed retrospectively for patients who were admitted to the medical or surgical intensive care units (ICUs) in a 591-bed teaching hospital and who received either dexmedetomidine or propofol alone for 24 hours or more for sedation. Results: A total of 111 patients were included in the study, with 56 patients in the dexmedetomidine group and 55 patients in the propofol group. Results of the analysis showed that the propofol group had a higher prevalence of coma (43.6% versus 12.5%; P < 0.001). Dexmedetomidine patients had a longer median hospital length of stay of 23.5 days (interquartile range [IQR], 11.5–39.5 days) versus 15.0 days (IQR, 7.0–24.0 days; P = 0.01). The rates of delirium were similar in both groups, with 16% in dexmedetomidine-treated patients versus 20% in propofol-treated patients (P = 0.63). Conclusion: No difference in the prevalence of delirium was found when comparing the dexmedetomidine- and propofol-treated groups. Propofol was associated with more coma and oversedation; dexmedetomidine was associated with longer time to extubation, longer length of stay in the ICU, and longer hospital length of stay. PMID:27408521

  12. Spectroscopic Investigations of the Chemical Composition and Coma Morphology of Comets

    NASA Astrophysics Data System (ADS)

    Pierce, D.; Lewis, B.; Vaughan, C.; Cochran, A.

    2014-12-01

    Ground-based emission spectroscopy at optical wavelengths is important for understanding the chemical composition of comets. We have made spectroscopic observations of comets using both long-slit and integral-field unit spectrographs on the Harlan J. Smith telescope at the University of Texas McDonald Observatory in order to study radical species in cometary comae. We will discuss the techniques used to extract chemical abundances in comets from these data and show how the spatial distribution of the observed species and large-scale coma morphological features (e.g. jets or fans) are mapped and characterized. Analyses of data we have acquired for several comets to date will be presented that examine their chemical abundances, track the temporal evolution of coma morphology in relation to nuclear rotational behavior (where known), and gauge potential chemical heterogeneity of cometary nuclei. We will also place this work into broader context by comparing our results to existing large-sample photometric and spectroscopic surveys of comets, as well as comparing our results to those obtained during prior apparitions to determine whether these comets show any evolutionary changes in measured chemical abundances or sources of outgassing on their surfaces. This work has been funded by the NSF GK-12 STEM Fellowship program, NASA's Planetary Astronomy and Planetary Atmospheres programs, and the Fund for Astrophysical Research, Inc.

  13. Galaxy Interactions, Tidal Debris, and the Origin of Intracluster Light in the Coma Cluster

    NASA Astrophysics Data System (ADS)

    Gregg, Michael

    1999-07-01

    We propose to obtain deep WFPC2 and parallel STIS images of low surface brightness tidal debris that we have recently discovered in the Coma cluster; the material is being stripped from its parent galaxy and added to the general cluster background. These images will enable direct study of the brightest blue and red supergiants, globular clusters, and star forming regions which may be present, or will place strong limits on the numbers of such objects and any recent star formation. We also propose similar observations of the parent spiral, NGC4911, in the core of Coma; it is losing its ISM to the hot cluster gas and as well as the low surface brightness tidal debris. By imaging this galaxy, we will get a high resolution look at the interaction between the galaxy and interstellar medium, as well as any ram-pressure induced star formation. The tidal features in Coma appear to be adding material to the background light and cD galaxy envelopes at a significant rate; determining the nature of the added stellar population and the interactions which produce it are critical to understanding the formation and evolution of cD galaxies and clusters.

  14. Multidetector computed tomographic angiography of aberrant subclavian arteries.

    PubMed

    Türkvatan, Aysel; Büyükbayraktar, Fatma Gül; Olçer, Tülay; Cumhur, Turhan

    2009-02-01

    The purpose of this study was to evaluate the utility of 16-slice multidetector computed tomographic (MDCT) angiography for identifying anatomic features of aberrant subclavian arteries. Seventeen patients with aberrant subclavian arteries were assessed by MDCT angiography. The aortic arch position, the presence of a Kommerell's diverticulum, aneurysm, vascular compression of trachea and oesophagus and associated cardiovascular abnormalities were evaluated. MDCT findings were confirmed by surgery in eight patients but in the other nine patients no further evaluation or management was warranted as the aberrant subclavian artery had no significant clinical consequence. Eleven patients had an aberrant right subclavian artery arising from the left aortic arch and six patients had an aberrant left subclavian artery arising from the right aortic arch. Kommerell's diverticulum was identified in three patients with an aberrant right subclavian artery and in five patients with an aberrant left subclavian artery. In two patients it was aneurysmal. Oesophageal compression was detected in eight patients, and tracheal compression was identified in only one paediatric patient. An aberrant subclavian artery was associated with complex congenital heart disease in one patient, intracardiac defects in two patients, aortic coarctation in two patients, patent ductus arteriosus in two patients and an aberrant vertebral artery in one patient. In conclusion, MDCT angiography is superior to digital subtraction angiography for the assessment of aberrant subclavian arteries since digital subtraction angiography has only a poor ability to visualize adjacent structures completely and is invasive in nature. MDCT angiography or magnetic resonance angiography are the current standard in the initial evaluation of thoracic vascular anomalies.

  15. Influence of higher order aberrations and retinal image quality in myopisation of emmetropic eyes.

    PubMed

    Philip, Krupa; Sankaridurg, Padmaja; Holden, Brien; Ho, Arthur; Mitchell, Paul

    2014-12-01

    Refractive error, higher order aberrations (HOA), axial length (AL), anterior chamber depth (ACD) and average corneal radius of curvature were measured after cycloplegia from 166 emmetropic participants at the Sydney Myopia Study (SMS, 2004-2005, age 12.63 ± 0.48 years). Measurements were repeated approximately 5 years later at the Sydney Adolescent Vascular and Eye Study (SAVES, 2009-2010, age 17.08 ± 0.67 years). The baseline spherical equivalent (M) did not differ significantly between the participants lost to follow-up (65%) and the participants enrolled in SAVES study (p = 0.932). Refractive error and HOA were measured using a Shack-Hartmann aberrometer for a pupil diameter of 5 mm and AL, ACD and average corneal curvature measured using IOL Master at both visits. Retinal image quality in terms of Visual Strehl ratio (VSOTF) for a 5 mm pupil diameter was determined using on-axis lower and HOA. General linear model was used to determine the association of HOA and retinal image quality with change in refraction. Of the 166 emmetropes, 41 (25%) had myopic change (change in M > -0.50 D) and 125 (75%) had no change in refraction (change in M between +0.49 D and -0.49 D). Change in C[4, 0] (p < 0.001, R² = 0.236), fourth order RMS (p = 0.003, R² = 0.097) and coma RMS (p = 0.004, R² = 0.056) from baseline were significantly correlated with change in refraction. More positive change in C[4, 0] was associated with lesser myopic change in refraction. The eyes with myopic change in refraction decreased in positive C[4, 0] (at baseline = +0.049 ± 0.05 μm, at follow-up = +0.024 ± 0.05 μm, p < 0.05). In comparison, eyes with no change increased in positive C[4, 0] (at baseline = +0.033 ± 0.04 μm, at follow-up = +0.047 ± 0.04 μm, p < 0.05). Thus in conclusion, no significant association was observed between HOA and retinal image quality at baseline and development and progression of myopia among emmetropic eyes. The change in spherical aberration (C[4, 0]) with

  16. The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs

    NASA Technical Reports Server (NTRS)

    Hammer, Derek; Kleijn, Gijs Verdoes; Hoyos, Carlos; Den Brok, Mark; Balcells, Marc; Ferguson, Henry C.; Goudfrooij, Paul; Carter, David; Guzman, Rafael; Peletier, Reynier F.; Smith, Russell J.; Graham, Alister W.; Trentham, Neil; Peng, Eric; Puzia, Thomas H.; Lucey, John R.; Jogee, Shardha; Aguerri, Alfonso L.; Batcheldor, Dan; Bridges, Terry J.; Davies, Jonathan I.; Del Burgo, Carlos; Erwin, Peter; Hornschemeier, Ann; Hudson, Michael J.

    2010-01-01

    The Coma cluster, Abell 1656, was the target of a HST-ACS Treasury program designed for deep imaging in the F475W and F814W passbands. Although our survey was interrupted by the ACS instrument failure in early 2007, the partially-completed survey still covers approximately 50% of the core high density region in Coma. Observations were performed for twenty-five fields with a total coverage area of 274 aremin(sup 2), and extend over a wide range of cluster-centric radii (approximately 1.75 Mpe or 1 deg). The majority of the fields are located near the core region of Coma (19/25 pointings) with six additional fields in the south-west region of the cluster. In this paper we present SEXTRACTOR source catalogs generated from the processed images, including a detailed description of the methodology used for object detection and photometry, the subtraction of bright galaxies to measure faint underlying objects, and the use of simulations to assess the photometric accuracy and completeness of our catalogs. We also use simulations to perform aperture corrections for the SEXTRACTOR Kron magnitudes based only on the measured source flux and its half-light radius. We have performed photometry for 76,000 objects that consist of roughly equal numbers of extended galaxies and unresolved objects. Approximately two-thirds of all detections are brighter than F814W=26.5 mag (AB), which corresponds to the 10sigma, point-source detection limit. We estimate that Coma members are 5-10% of the source detections, including a large population of compact objects (primarily GCs, but also cEs and UCDs), and a wide variety of extended galaxies from cD galaxies to dwarf low surface brightness galaxies. The initial data release for the HST-ACS Coma Treasury program was made available to the public in August 2008. The images and catalogs described in this study relate to our second data release.

  17. AN ANALYSIS OF CO PRODUCTION IN COMETARY COMAE: CONTRIBUTIONS FROM GAS-PHASE PHENOMENA

    SciTech Connect

    Pierce, Donna M.; A'Hearn, Michael F. E-mail: ma@astro.umd.ed

    2010-07-20

    Understanding the sources of CO in cometary comae is important for understanding comet chemistry and the roles comets have played in the development of the solar system. Among comets sampled to date, the CO abundances vary widely and no direct correlation of CO abundance with other known comet properties has been identified. The picture is complicated further by the discovery of CO production in the comae of some comets, most notably comets Halley and Hale-Bopp. In this study, we investigate the conditions under which CO can be produced in the coma via gas-phase phenomena. We include photochemistry of several parent molecules, as well as two-body chemical reactions that involve the parents and their photodissociative daughter and granddaughter products. We also consider the level of excitation of 'hot' hydrogen (H*) and O({sup 1}D) in the network, because the level of excitation of these reactants strongly influences reaction rates. Our results suggest that the dominant gas-phase contributor to CO formation is the photodissociation of H{sub 2}CO. Even though typical abundances of H{sub 2}CO are at {approx}1% relative to water in the coma, it produces more CO than other processes due to its relatively short photodissociation lifetime. Because other studies have shown H{sub 2}CO to have a distributed source as well, it suggests that at least some CO formation in the coma is connected to the H{sub 2}CO distributed source. We take the time to examine the CO{sub 2}/CO ratio and note that while the CO{sub 2}/CO ratio in comets Halley, Hale-Bopp, and Hyakutake are noticeably different when only native CO is considered, the CO{sub 2}/CO ratios show greater similarity when total CO is considered. Although this sample is relatively small, should the relatively similar CO{sub 2}/CO{sub Total} ratio of {approx}0.25 indeed be constant for comets with distributed CO sources, it suggests that the extended CO source of these comets is tied directly to the overall C, H, O chemistry

  18. Comet 67P Nucleus Water Ice Distribution and Evolution Inferred from Inner Coma Structure Seen by Rosetta/MIRO

    NASA Astrophysics Data System (ADS)

    Lee, Seungwon; von Allmen, Paul; MIRO Team

    2016-10-01

    The spatial structure and temporal evolution of the inner coma of Comet 67P have been observed by Microwave Instrument on Rosetta Orbiter (MIRO) since the Rosetta Orbiter has rendezvoused with Comet 67P in August 2014. Among the several cometary gas emission lines that the MIRO spectrometer is tuned to, the water isotopologue H218O line is optically thin and is used to probe the inner coma structure as the MIRO beam scans the space near the comet nucleus. The water line area/strength shows clearly that the day side of coma has a lot more gas than the night side of coma and the summer hemisphere side of coma has a lot more gas than the winter hemisphere side of coma. These diurnal and seasonal dependencies strongly suggest that the water gas in the coma is from the sublimation of ice in the nucleus, where its rate greatly depends on the thermal condition of surface and near-surface governed by the sun illumination condition. In addition to the sun illumination condition, the water ice distribution on 67P nucleus affects the inner coma structure. We model the inner coma structures with various ice distributions and compare them with the observation. The comparison undoubtedly shows that the ice is not uniformly distributed on 67P nucleus. The observation favors the model with the ice distributed only in polar caps in both poles. The observation also shows the evidence of temporal evolution of the ice distribution. The southern polar ice cap was less active a few months before the perihelion (August 2015), became more active near the perihelion, and became less active a few months after the perihelion. Note that the ice cap activity change due to the temperature-dependent sublimation rate change is already taken into account, and does not explain the temporal variation of the inner coma structure. This result indicates that there was a change of ice distribution (polar cap size) or ice location near the surface (how deep the dust layer covers the ice).

  19. Using graph theory to describe and model chromosome aberrations.

    PubMed

    Sachs, Rainer K; Arsuaga, Javier; Vázquez, Mariel; Hlatky, Lynn; Hahnfeldt, Philip

    2002-11-01

    A comprehensive description of chromosome aberrations is introduced that is suitable for all cytogenetic protocols (e.g. solid staining, banding, FISH, mFISH, SKY, bar coding) and for mathematical analyses. "Aberration multigraphs" systematically characterize and interrelate three basic aberration elements: (1) the initial configuration of chromosome breaks; (2) the exchange process, whose cycle structure helps to describe aberration complexity; and (3) the final configuration of rearranged chromosomes, which determines the observed pattern but may contain cryptic misrejoinings in addition. New aberration classification methods and a far-reaching generalization of mPAINT descriptors, applicable to any protocol, emerge. The difficult problem of trying to infer actual exchange processes from cytogenetically observed final patterns is analyzed using computer algorithms, adaptations of known theorems on cubic graphs, and some new graph-theoretical constructs. Results include the following: (1) For a painting protocol, unambiguously inferring the occurrence of a high-order cycle requires a corresponding number of different colors; (2) cycle structure can be computed by a simple trick directly from mPAINT descriptors if the initial configuration has no more than one break per homologue pair; and (3) higher-order cycles are more frequent than the obligate cycle structure specifies. Aberration multigraphs are a powerful new way to describe, classify and quantitatively analyze radiation-induced chromosome aberrations. They pinpoint (but do not eliminate) the problem that, with present cytogenetic techniques, one observed pattern corresponds to many possible initial configurations and exchange processes. PMID:12385633

  20. The Mechanisms of Aberrant Protein Aggregation

    NASA Astrophysics Data System (ADS)

    Cohen, Samuel; Vendruscolo, Michele; Dobson, Chris; Knowles, Tuomas

    2012-02-01

    We discuss the development of a kinetic theory for understanding the aberrant loss of solubility of proteins. The failure to maintain protein solubility results often in the assembly of organized linear structures, commonly known as amyloid fibrils, the formation of which is associated with over 50 clinical disorders including Alzheimer's and Parkinson's diseases. A true microscopic understanding of the mechanisms that drive these aggregation processes has proved difficult to achieve. To address this challenge, we apply the methodologies of chemical kinetics to the biomolecular self-assembly pathways related to protein aggregation. We discuss the relevant master equation and analytical approaches to studying it. In particular, we derive the underlying rate laws in closed-form using a self-consistent solution scheme; the solutions that we obtain reveal scaling behaviors that are very generally present in systems of growing linear aggregates, and, moreover, provide a general route through which to relate experimental measurements to mechanistic information. We conclude by outlining a study of the aggregation of the Alzheimer's amyloid-beta peptide. The study identifies the dominant microscopic mechanism of aggregation and reveals previously unidentified therapeutic strategies.